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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Tejun Heoc54fce62010-09-10 16:51:36 +02002 * kernel/workqueue.c - generic async execution with shared worker pool
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
Tejun Heoc54fce62010-09-10 16:51:36 +02004 * Copyright (C) 2002 Ingo Molnar
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 *
Tejun Heoc54fce62010-09-10 16:51:36 +02006 * Derived from the taskqueue/keventd code by:
7 * David Woodhouse <dwmw2@infradead.org>
8 * Andrew Morton
9 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
10 * Theodore Ts'o <tytso@mit.edu>
Christoph Lameter89ada672005-10-30 15:01:59 -080011 *
Christoph Lametercde53532008-07-04 09:59:22 -070012 * Made to use alloc_percpu by Christoph Lameter.
Tejun Heoc54fce62010-09-10 16:51:36 +020013 *
14 * Copyright (C) 2010 SUSE Linux Products GmbH
15 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
16 *
17 * This is the generic async execution mechanism. Work items as are
18 * executed in process context. The worker pool is shared and
Libinb11895c2013-08-21 08:50:39 +080019 * automatically managed. There are two worker pools for each CPU (one for
20 * normal work items and the other for high priority ones) and some extra
21 * pools for workqueues which are not bound to any specific CPU - the
22 * number of these backing pools is dynamic.
Tejun Heoc54fce62010-09-10 16:51:36 +020023 *
24 * Please read Documentation/workqueue.txt for details.
Linus Torvalds1da177e2005-04-16 15:20:36 -070025 */
26
Paul Gortmaker9984de12011-05-23 14:51:41 -040027#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/kernel.h>
29#include <linux/sched.h>
30#include <linux/init.h>
31#include <linux/signal.h>
32#include <linux/completion.h>
33#include <linux/workqueue.h>
34#include <linux/slab.h>
35#include <linux/cpu.h>
36#include <linux/notifier.h>
37#include <linux/kthread.h>
James Bottomley1fa44ec2006-02-23 12:43:43 -060038#include <linux/hardirq.h>
Christoph Lameter46934022006-10-11 01:21:26 -070039#include <linux/mempolicy.h>
Rafael J. Wysocki341a5952006-12-06 20:34:49 -080040#include <linux/freezer.h>
Peter Zijlstrad5abe662006-12-06 20:37:26 -080041#include <linux/kallsyms.h>
42#include <linux/debug_locks.h>
Johannes Berg4e6045f2007-10-18 23:39:55 -070043#include <linux/lockdep.h>
Tejun Heoc34056a2010-06-29 10:07:11 +020044#include <linux/idr.h>
Tejun Heo29c91e92013-03-12 11:30:03 -070045#include <linux/jhash.h>
Sasha Levin42f85702012-12-17 10:01:23 -050046#include <linux/hashtable.h>
Tejun Heo76af4d92013-03-12 11:30:00 -070047#include <linux/rculist.h>
Tejun Heobce90382013-04-01 11:23:32 -070048#include <linux/nodemask.h>
Tejun Heo4c16bd32013-04-01 11:23:36 -070049#include <linux/moduleparam.h>
Tejun Heo3d1cb202013-04-30 15:27:22 -070050#include <linux/uaccess.h>
Tejun Heoe22bee72010-06-29 10:07:14 +020051
Tejun Heoea138442013-01-18 14:05:55 -080052#include "workqueue_internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070053
Tejun Heoc8e55f32010-06-29 10:07:12 +020054enum {
Tejun Heobc2ae0f2012-07-17 12:39:27 -070055 /*
Tejun Heo24647572013-01-24 11:01:33 -080056 * worker_pool flags
Tejun Heobc2ae0f2012-07-17 12:39:27 -070057 *
Tejun Heo24647572013-01-24 11:01:33 -080058 * A bound pool is either associated or disassociated with its CPU.
Tejun Heobc2ae0f2012-07-17 12:39:27 -070059 * While associated (!DISASSOCIATED), all workers are bound to the
60 * CPU and none has %WORKER_UNBOUND set and concurrency management
61 * is in effect.
62 *
63 * While DISASSOCIATED, the cpu may be offline and all workers have
64 * %WORKER_UNBOUND set and concurrency management disabled, and may
Tejun Heo24647572013-01-24 11:01:33 -080065 * be executing on any CPU. The pool behaves as an unbound one.
Tejun Heobc2ae0f2012-07-17 12:39:27 -070066 *
Tejun Heobc3a1af2013-03-13 19:47:39 -070067 * Note that DISASSOCIATED should be flipped only while holding
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +080068 * attach_mutex to avoid changing binding state while
Lai Jiangshan4736cbf2014-05-20 17:46:35 +080069 * worker_attach_to_pool() is in progress.
Tejun Heobc2ae0f2012-07-17 12:39:27 -070070 */
Tejun Heo24647572013-01-24 11:01:33 -080071 POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
Tejun Heodb7bccf2010-06-29 10:07:12 +020072
Tejun Heoc8e55f32010-06-29 10:07:12 +020073 /* worker flags */
Tejun Heoc8e55f32010-06-29 10:07:12 +020074 WORKER_DIE = 1 << 1, /* die die die */
75 WORKER_IDLE = 1 << 2, /* is idle */
Tejun Heoe22bee72010-06-29 10:07:14 +020076 WORKER_PREP = 1 << 3, /* preparing to run works */
Tejun Heofb0e7be2010-06-29 10:07:15 +020077 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
Tejun Heof3421792010-07-02 10:03:51 +020078 WORKER_UNBOUND = 1 << 7, /* worker is unbound */
Tejun Heoa9ab7752013-03-19 13:45:21 -070079 WORKER_REBOUND = 1 << 8, /* worker was rebound */
Tejun Heoe22bee72010-06-29 10:07:14 +020080
Tejun Heoa9ab7752013-03-19 13:45:21 -070081 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE |
82 WORKER_UNBOUND | WORKER_REBOUND,
Tejun Heodb7bccf2010-06-29 10:07:12 +020083
Tejun Heoe34cdddb2013-01-24 11:01:33 -080084 NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
Tejun Heo4ce62e92012-07-13 22:16:44 -070085
Tejun Heo29c91e92013-03-12 11:30:03 -070086 UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
Tejun Heoc8e55f32010-06-29 10:07:12 +020087 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
Tejun Heodb7bccf2010-06-29 10:07:12 +020088
Tejun Heoe22bee72010-06-29 10:07:14 +020089 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
90 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
91
Tejun Heo3233cdb2011-02-16 18:10:19 +010092 MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
93 /* call for help after 10ms
94 (min two ticks) */
Tejun Heoe22bee72010-06-29 10:07:14 +020095 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
96 CREATE_COOLDOWN = HZ, /* time to breath after fail */
Tejun Heoe22bee72010-06-29 10:07:14 +020097
98 /*
99 * Rescue workers are used only on emergencies and shared by
Dongsheng Yang8698a742014-03-11 18:09:12 +0800100 * all cpus. Give MIN_NICE.
Tejun Heoe22bee72010-06-29 10:07:14 +0200101 */
Dongsheng Yang8698a742014-03-11 18:09:12 +0800102 RESCUER_NICE_LEVEL = MIN_NICE,
103 HIGHPRI_NICE_LEVEL = MIN_NICE,
Tejun Heoecf68812013-04-01 11:23:34 -0700104
105 WQ_NAME_LEN = 24,
Tejun Heoc8e55f32010-06-29 10:07:12 +0200106};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107
108/*
Tejun Heo4690c4a2010-06-29 10:07:10 +0200109 * Structure fields follow one of the following exclusion rules.
110 *
Tejun Heoe41e7042010-08-24 14:22:47 +0200111 * I: Modifiable by initialization/destruction paths and read-only for
112 * everyone else.
Tejun Heo4690c4a2010-06-29 10:07:10 +0200113 *
Tejun Heoe22bee72010-06-29 10:07:14 +0200114 * P: Preemption protected. Disabling preemption is enough and should
115 * only be modified and accessed from the local cpu.
116 *
Tejun Heod565ed62013-01-24 11:01:33 -0800117 * L: pool->lock protected. Access with pool->lock held.
Tejun Heo4690c4a2010-06-29 10:07:10 +0200118 *
Tejun Heod565ed62013-01-24 11:01:33 -0800119 * X: During normal operation, modification requires pool->lock and should
120 * be done only from local cpu. Either disabling preemption on local
121 * cpu or grabbing pool->lock is enough for read access. If
122 * POOL_DISASSOCIATED is set, it's identical to L.
Tejun Heoe22bee72010-06-29 10:07:14 +0200123 *
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +0800124 * A: pool->attach_mutex protected.
Tejun Heo822d8402013-03-19 13:45:21 -0700125 *
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700126 * PL: wq_pool_mutex protected.
Tejun Heo76af4d92013-03-12 11:30:00 -0700127 *
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700128 * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
Tejun Heo5bcab332013-03-13 19:47:40 -0700129 *
Lai Jiangshan3c25a552013-03-25 16:57:17 -0700130 * WQ: wq->mutex protected.
131 *
Lai Jiangshanb5927602013-03-25 16:57:19 -0700132 * WR: wq->mutex protected for writes. Sched-RCU protected for reads.
Tejun Heo2e109a22013-03-13 19:47:40 -0700133 *
134 * MD: wq_mayday_lock protected.
Tejun Heo4690c4a2010-06-29 10:07:10 +0200135 */
136
Tejun Heo2eaebdb2013-01-18 14:05:55 -0800137/* struct worker is defined in workqueue_internal.h */
Tejun Heoc34056a2010-06-29 10:07:11 +0200138
Tejun Heobd7bdd42012-07-12 14:46:37 -0700139struct worker_pool {
Tejun Heod565ed62013-01-24 11:01:33 -0800140 spinlock_t lock; /* the pool lock */
Tejun Heod84ff052013-03-12 11:29:59 -0700141 int cpu; /* I: the associated cpu */
Tejun Heof3f90ad2013-04-01 11:23:34 -0700142 int node; /* I: the associated node ID */
Tejun Heo9daf9e62013-01-24 11:01:33 -0800143 int id; /* I: pool ID */
Tejun Heo11ebea52012-07-12 14:46:37 -0700144 unsigned int flags; /* X: flags */
Tejun Heobd7bdd42012-07-12 14:46:37 -0700145
146 struct list_head worklist; /* L: list of pending works */
147 int nr_workers; /* L: total number of workers */
Lai Jiangshanea1abd62012-09-18 09:59:22 -0700148
149 /* nr_idle includes the ones off idle_list for rebinding */
Tejun Heobd7bdd42012-07-12 14:46:37 -0700150 int nr_idle; /* L: currently idle ones */
151
152 struct list_head idle_list; /* X: list of idle workers */
153 struct timer_list idle_timer; /* L: worker idle timeout */
154 struct timer_list mayday_timer; /* L: SOS timer for workers */
155
Tejun Heoc5aa87b2013-03-13 16:51:36 -0700156 /* a workers is either on busy_hash or idle_list, or the manager */
Tejun Heoc9e7cf22013-01-24 11:01:33 -0800157 DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
158 /* L: hash of busy workers */
159
Tejun Heobc3a1af2013-03-13 19:47:39 -0700160 /* see manage_workers() for details on the two manager mutexes */
Tejun Heo34a06bd2013-03-12 11:30:00 -0700161 struct mutex manager_arb; /* manager arbitration */
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +0800162 struct mutex attach_mutex; /* attach/detach exclusion */
163 struct list_head workers; /* A: attached workers */
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +0800164 struct completion *detach_completion; /* all workers detached */
Tejun Heoe19e3972013-01-24 11:39:44 -0800165
Lai Jiangshan7cda9aa2014-05-20 17:46:32 +0800166 struct ida worker_ida; /* worker IDs for task name */
Tejun Heoe19e3972013-01-24 11:39:44 -0800167
Tejun Heo7a4e3442013-03-12 11:30:00 -0700168 struct workqueue_attrs *attrs; /* I: worker attributes */
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700169 struct hlist_node hash_node; /* PL: unbound_pool_hash node */
170 int refcnt; /* PL: refcnt for unbound pools */
Tejun Heo7a4e3442013-03-12 11:30:00 -0700171
Tejun Heoe19e3972013-01-24 11:39:44 -0800172 /*
173 * The current concurrency level. As it's likely to be accessed
174 * from other CPUs during try_to_wake_up(), put it in a separate
175 * cacheline.
176 */
177 atomic_t nr_running ____cacheline_aligned_in_smp;
Tejun Heo29c91e92013-03-12 11:30:03 -0700178
179 /*
180 * Destruction of pool is sched-RCU protected to allow dereferences
181 * from get_work_pool().
182 */
183 struct rcu_head rcu;
Tejun Heo8b03ae32010-06-29 10:07:12 +0200184} ____cacheline_aligned_in_smp;
185
186/*
Tejun Heo112202d2013-02-13 19:29:12 -0800187 * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
188 * of work_struct->data are used for flags and the remaining high bits
189 * point to the pwq; thus, pwqs need to be aligned at two's power of the
190 * number of flag bits.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 */
Tejun Heo112202d2013-02-13 19:29:12 -0800192struct pool_workqueue {
Tejun Heobd7bdd42012-07-12 14:46:37 -0700193 struct worker_pool *pool; /* I: the associated pool */
Tejun Heo4690c4a2010-06-29 10:07:10 +0200194 struct workqueue_struct *wq; /* I: the owning workqueue */
Tejun Heo73f53c42010-06-29 10:07:11 +0200195 int work_color; /* L: current color */
196 int flush_color; /* L: flushing color */
Tejun Heo8864b4e2013-03-12 11:30:04 -0700197 int refcnt; /* L: reference count */
Tejun Heo73f53c42010-06-29 10:07:11 +0200198 int nr_in_flight[WORK_NR_COLORS];
199 /* L: nr of in_flight works */
Tejun Heo1e19ffc2010-06-29 10:07:12 +0200200 int nr_active; /* L: nr of active works */
Tejun Heoa0a1a5f2010-06-29 10:07:12 +0200201 int max_active; /* L: max active works */
Tejun Heo1e19ffc2010-06-29 10:07:12 +0200202 struct list_head delayed_works; /* L: delayed works */
Lai Jiangshan3c25a552013-03-25 16:57:17 -0700203 struct list_head pwqs_node; /* WR: node on wq->pwqs */
Tejun Heo2e109a22013-03-13 19:47:40 -0700204 struct list_head mayday_node; /* MD: node on wq->maydays */
Tejun Heo8864b4e2013-03-12 11:30:04 -0700205
206 /*
207 * Release of unbound pwq is punted to system_wq. See put_pwq()
208 * and pwq_unbound_release_workfn() for details. pool_workqueue
209 * itself is also sched-RCU protected so that the first pwq can be
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -0700210 * determined without grabbing wq->mutex.
Tejun Heo8864b4e2013-03-12 11:30:04 -0700211 */
212 struct work_struct unbound_release_work;
213 struct rcu_head rcu;
Tejun Heoe904e6c2013-03-12 11:29:57 -0700214} __aligned(1 << WORK_STRUCT_FLAG_BITS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216/*
Tejun Heo73f53c42010-06-29 10:07:11 +0200217 * Structure used to wait for workqueue flush.
218 */
219struct wq_flusher {
Lai Jiangshan3c25a552013-03-25 16:57:17 -0700220 struct list_head list; /* WQ: list of flushers */
221 int flush_color; /* WQ: flush color waiting for */
Tejun Heo73f53c42010-06-29 10:07:11 +0200222 struct completion done; /* flush completion */
223};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224
Tejun Heo226223a2013-03-12 11:30:05 -0700225struct wq_device;
226
Tejun Heo73f53c42010-06-29 10:07:11 +0200227/*
Tejun Heoc5aa87b2013-03-13 16:51:36 -0700228 * The externally visible workqueue. It relays the issued work items to
229 * the appropriate worker_pool through its pool_workqueues.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 */
231struct workqueue_struct {
Lai Jiangshan3c25a552013-03-25 16:57:17 -0700232 struct list_head pwqs; /* WR: all pwqs of this wq */
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700233 struct list_head list; /* PL: list of all workqueues */
Tejun Heo73f53c42010-06-29 10:07:11 +0200234
Lai Jiangshan3c25a552013-03-25 16:57:17 -0700235 struct mutex mutex; /* protects this wq */
236 int work_color; /* WQ: current work color */
237 int flush_color; /* WQ: current flush color */
Tejun Heo112202d2013-02-13 19:29:12 -0800238 atomic_t nr_pwqs_to_flush; /* flush in progress */
Lai Jiangshan3c25a552013-03-25 16:57:17 -0700239 struct wq_flusher *first_flusher; /* WQ: first flusher */
240 struct list_head flusher_queue; /* WQ: flush waiters */
241 struct list_head flusher_overflow; /* WQ: flush overflow list */
Tejun Heo73f53c42010-06-29 10:07:11 +0200242
Tejun Heo2e109a22013-03-13 19:47:40 -0700243 struct list_head maydays; /* MD: pwqs requesting rescue */
Tejun Heoe22bee72010-06-29 10:07:14 +0200244 struct worker *rescuer; /* I: rescue worker */
245
Lai Jiangshan87fc7412013-03-25 16:57:18 -0700246 int nr_drainers; /* WQ: drain in progress */
Lai Jiangshana357fc02013-03-25 16:57:19 -0700247 int saved_max_active; /* WQ: saved pwq max_active */
Tejun Heo226223a2013-03-12 11:30:05 -0700248
Tejun Heo6029a912013-04-01 11:23:34 -0700249 struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */
Tejun Heo4c16bd32013-04-01 11:23:36 -0700250 struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */
Tejun Heo6029a912013-04-01 11:23:34 -0700251
Tejun Heo226223a2013-03-12 11:30:05 -0700252#ifdef CONFIG_SYSFS
253 struct wq_device *wq_dev; /* I: for sysfs interface */
254#endif
Johannes Berg4e6045f2007-10-18 23:39:55 -0700255#ifdef CONFIG_LOCKDEP
Tejun Heo4690c4a2010-06-29 10:07:10 +0200256 struct lockdep_map lockdep_map;
Johannes Berg4e6045f2007-10-18 23:39:55 -0700257#endif
Tejun Heoecf68812013-04-01 11:23:34 -0700258 char name[WQ_NAME_LEN]; /* I: workqueue name */
Tejun Heo2728fd22013-04-01 11:23:35 -0700259
260 /* hot fields used during command issue, aligned to cacheline */
261 unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
262 struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */
Tejun Heodf2d5ae2013-04-01 11:23:35 -0700263 struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264};
265
Tejun Heoe904e6c2013-03-12 11:29:57 -0700266static struct kmem_cache *pwq_cache;
267
Tejun Heobce90382013-04-01 11:23:32 -0700268static int wq_numa_tbl_len; /* highest possible NUMA node id + 1 */
269static cpumask_var_t *wq_numa_possible_cpumask;
270 /* possible CPUs of each node */
271
Tejun Heod55262c2013-04-01 11:23:38 -0700272static bool wq_disable_numa;
273module_param_named(disable_numa, wq_disable_numa, bool, 0444);
274
Viresh Kumarcee22a12013-04-08 16:45:40 +0530275/* see the comment above the definition of WQ_POWER_EFFICIENT */
276#ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
277static bool wq_power_efficient = true;
278#else
279static bool wq_power_efficient;
280#endif
281
282module_param_named(power_efficient, wq_power_efficient, bool, 0444);
283
Tejun Heobce90382013-04-01 11:23:32 -0700284static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
285
Tejun Heo4c16bd32013-04-01 11:23:36 -0700286/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
287static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
288
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700289static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
Tejun Heo2e109a22013-03-13 19:47:40 -0700290static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
Tejun Heo5bcab332013-03-13 19:47:40 -0700291
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700292static LIST_HEAD(workqueues); /* PL: list of all workqueues */
293static bool workqueue_freezing; /* PL: have wqs started freezing? */
Tejun Heo7d19c5c2013-03-13 19:47:40 -0700294
295/* the per-cpu worker pools */
296static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
297 cpu_worker_pools);
298
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700299static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
Tejun Heo7d19c5c2013-03-13 19:47:40 -0700300
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700301/* PL: hash of all unbound pools keyed by pool->attrs */
Tejun Heo29c91e92013-03-12 11:30:03 -0700302static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
303
Tejun Heoc5aa87b2013-03-13 16:51:36 -0700304/* I: attributes used when instantiating standard unbound pools on demand */
Tejun Heo29c91e92013-03-12 11:30:03 -0700305static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
306
Tejun Heo8a2b7532013-09-05 12:30:04 -0400307/* I: attributes used when instantiating ordered pools on demand */
308static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
309
Tejun Heod320c032010-06-29 10:07:14 +0200310struct workqueue_struct *system_wq __read_mostly;
Marc Dionnead7b1f82013-05-06 17:44:55 -0400311EXPORT_SYMBOL(system_wq);
Valentin Ilie044c7822012-08-19 00:52:42 +0300312struct workqueue_struct *system_highpri_wq __read_mostly;
Joonsoo Kim1aabe902012-08-15 23:25:39 +0900313EXPORT_SYMBOL_GPL(system_highpri_wq);
Valentin Ilie044c7822012-08-19 00:52:42 +0300314struct workqueue_struct *system_long_wq __read_mostly;
Tejun Heod320c032010-06-29 10:07:14 +0200315EXPORT_SYMBOL_GPL(system_long_wq);
Valentin Ilie044c7822012-08-19 00:52:42 +0300316struct workqueue_struct *system_unbound_wq __read_mostly;
Tejun Heof3421792010-07-02 10:03:51 +0200317EXPORT_SYMBOL_GPL(system_unbound_wq);
Valentin Ilie044c7822012-08-19 00:52:42 +0300318struct workqueue_struct *system_freezable_wq __read_mostly;
Tejun Heo24d51ad2011-02-21 09:52:50 +0100319EXPORT_SYMBOL_GPL(system_freezable_wq);
Viresh Kumar06681062013-04-24 17:12:54 +0530320struct workqueue_struct *system_power_efficient_wq __read_mostly;
321EXPORT_SYMBOL_GPL(system_power_efficient_wq);
322struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly;
323EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq);
Tejun Heod320c032010-06-29 10:07:14 +0200324
Tejun Heo7d19c5c2013-03-13 19:47:40 -0700325static int worker_thread(void *__worker);
326static void copy_workqueue_attrs(struct workqueue_attrs *to,
327 const struct workqueue_attrs *from);
328
Tejun Heo97bd2342010-10-05 10:41:14 +0200329#define CREATE_TRACE_POINTS
330#include <trace/events/workqueue.h>
331
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700332#define assert_rcu_or_pool_mutex() \
Tejun Heo5bcab332013-03-13 19:47:40 -0700333 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700334 lockdep_is_held(&wq_pool_mutex), \
335 "sched RCU or wq_pool_mutex should be held")
Tejun Heo5bcab332013-03-13 19:47:40 -0700336
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -0700337#define assert_rcu_or_wq_mutex(wq) \
Tejun Heo76af4d92013-03-12 11:30:00 -0700338 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
Lai Jiangshanb5927602013-03-25 16:57:19 -0700339 lockdep_is_held(&wq->mutex), \
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -0700340 "sched RCU or wq->mutex should be held")
Tejun Heo76af4d92013-03-12 11:30:00 -0700341
Tejun Heof02ae732013-03-12 11:30:03 -0700342#define for_each_cpu_worker_pool(pool, cpu) \
343 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
344 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
Tejun Heo7a62c2c2013-03-12 11:30:03 -0700345 (pool)++)
Tejun Heo4ce62e92012-07-13 22:16:44 -0700346
Tejun Heo49e3cf42013-03-12 11:29:58 -0700347/**
Tejun Heo17116962013-03-12 11:29:58 -0700348 * for_each_pool - iterate through all worker_pools in the system
349 * @pool: iteration cursor
Tejun Heo611c92a2013-03-13 16:51:36 -0700350 * @pi: integer used for iteration
Tejun Heofa1b54e2013-03-12 11:30:00 -0700351 *
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700352 * This must be called either with wq_pool_mutex held or sched RCU read
353 * locked. If the pool needs to be used beyond the locking in effect, the
354 * caller is responsible for guaranteeing that the pool stays online.
Tejun Heofa1b54e2013-03-12 11:30:00 -0700355 *
356 * The if/else clause exists only for the lockdep assertion and can be
357 * ignored.
Tejun Heo17116962013-03-12 11:29:58 -0700358 */
Tejun Heo611c92a2013-03-13 16:51:36 -0700359#define for_each_pool(pool, pi) \
360 idr_for_each_entry(&worker_pool_idr, pool, pi) \
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700361 if (({ assert_rcu_or_pool_mutex(); false; })) { } \
Tejun Heofa1b54e2013-03-12 11:30:00 -0700362 else
Tejun Heo17116962013-03-12 11:29:58 -0700363
364/**
Tejun Heo822d8402013-03-19 13:45:21 -0700365 * for_each_pool_worker - iterate through all workers of a worker_pool
366 * @worker: iteration cursor
Tejun Heo822d8402013-03-19 13:45:21 -0700367 * @pool: worker_pool to iterate workers of
368 *
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +0800369 * This must be called with @pool->attach_mutex.
Tejun Heo822d8402013-03-19 13:45:21 -0700370 *
371 * The if/else clause exists only for the lockdep assertion and can be
372 * ignored.
373 */
Lai Jiangshanda028462014-05-20 17:46:31 +0800374#define for_each_pool_worker(worker, pool) \
375 list_for_each_entry((worker), &(pool)->workers, node) \
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +0800376 if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \
Tejun Heo822d8402013-03-19 13:45:21 -0700377 else
378
379/**
Tejun Heo49e3cf42013-03-12 11:29:58 -0700380 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
381 * @pwq: iteration cursor
382 * @wq: the target workqueue
Tejun Heo76af4d92013-03-12 11:30:00 -0700383 *
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -0700384 * This must be called either with wq->mutex held or sched RCU read locked.
Tejun Heo794b18b2013-03-13 19:47:40 -0700385 * If the pwq needs to be used beyond the locking in effect, the caller is
386 * responsible for guaranteeing that the pwq stays online.
Tejun Heo76af4d92013-03-12 11:30:00 -0700387 *
388 * The if/else clause exists only for the lockdep assertion and can be
389 * ignored.
Tejun Heo49e3cf42013-03-12 11:29:58 -0700390 */
391#define for_each_pwq(pwq, wq) \
Tejun Heo76af4d92013-03-12 11:30:00 -0700392 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -0700393 if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
Tejun Heo76af4d92013-03-12 11:30:00 -0700394 else
Tejun Heof3421792010-07-02 10:03:51 +0200395
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900396#ifdef CONFIG_DEBUG_OBJECTS_WORK
397
398static struct debug_obj_descr work_debug_descr;
399
Stanislaw Gruszka99777282011-03-07 09:58:33 +0100400static void *work_debug_hint(void *addr)
401{
402 return ((struct work_struct *) addr)->func;
403}
404
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900405/*
406 * fixup_init is called when:
407 * - an active object is initialized
408 */
409static int work_fixup_init(void *addr, enum debug_obj_state state)
410{
411 struct work_struct *work = addr;
412
413 switch (state) {
414 case ODEBUG_STATE_ACTIVE:
415 cancel_work_sync(work);
416 debug_object_init(work, &work_debug_descr);
417 return 1;
418 default:
419 return 0;
420 }
421}
422
423/*
424 * fixup_activate is called when:
425 * - an active object is activated
426 * - an unknown object is activated (might be a statically initialized object)
427 */
428static int work_fixup_activate(void *addr, enum debug_obj_state state)
429{
430 struct work_struct *work = addr;
431
432 switch (state) {
433
434 case ODEBUG_STATE_NOTAVAILABLE:
435 /*
436 * This is not really a fixup. The work struct was
437 * statically initialized. We just make sure that it
438 * is tracked in the object tracker.
439 */
Tejun Heo22df02b2010-06-29 10:07:10 +0200440 if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900441 debug_object_init(work, &work_debug_descr);
442 debug_object_activate(work, &work_debug_descr);
443 return 0;
444 }
445 WARN_ON_ONCE(1);
446 return 0;
447
448 case ODEBUG_STATE_ACTIVE:
449 WARN_ON(1);
450
451 default:
452 return 0;
453 }
454}
455
456/*
457 * fixup_free is called when:
458 * - an active object is freed
459 */
460static int work_fixup_free(void *addr, enum debug_obj_state state)
461{
462 struct work_struct *work = addr;
463
464 switch (state) {
465 case ODEBUG_STATE_ACTIVE:
466 cancel_work_sync(work);
467 debug_object_free(work, &work_debug_descr);
468 return 1;
469 default:
470 return 0;
471 }
472}
473
474static struct debug_obj_descr work_debug_descr = {
475 .name = "work_struct",
Stanislaw Gruszka99777282011-03-07 09:58:33 +0100476 .debug_hint = work_debug_hint,
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900477 .fixup_init = work_fixup_init,
478 .fixup_activate = work_fixup_activate,
479 .fixup_free = work_fixup_free,
480};
481
482static inline void debug_work_activate(struct work_struct *work)
483{
484 debug_object_activate(work, &work_debug_descr);
485}
486
487static inline void debug_work_deactivate(struct work_struct *work)
488{
489 debug_object_deactivate(work, &work_debug_descr);
490}
491
492void __init_work(struct work_struct *work, int onstack)
493{
494 if (onstack)
495 debug_object_init_on_stack(work, &work_debug_descr);
496 else
497 debug_object_init(work, &work_debug_descr);
498}
499EXPORT_SYMBOL_GPL(__init_work);
500
501void destroy_work_on_stack(struct work_struct *work)
502{
503 debug_object_free(work, &work_debug_descr);
504}
505EXPORT_SYMBOL_GPL(destroy_work_on_stack);
506
Thomas Gleixnerea2e64f2014-03-23 14:20:44 +0000507void destroy_delayed_work_on_stack(struct delayed_work *work)
508{
509 destroy_timer_on_stack(&work->timer);
510 debug_object_free(&work->work, &work_debug_descr);
511}
512EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack);
513
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +0900514#else
515static inline void debug_work_activate(struct work_struct *work) { }
516static inline void debug_work_deactivate(struct work_struct *work) { }
517#endif
518
Li Bin4e8b22b2013-09-10 09:52:35 +0800519/**
520 * worker_pool_assign_id - allocate ID and assing it to @pool
521 * @pool: the pool pointer of interest
522 *
523 * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
524 * successfully, -errno on failure.
525 */
Tejun Heo9daf9e62013-01-24 11:01:33 -0800526static int worker_pool_assign_id(struct worker_pool *pool)
527{
528 int ret;
529
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700530 lockdep_assert_held(&wq_pool_mutex);
Tejun Heo5bcab332013-03-13 19:47:40 -0700531
Li Bin4e8b22b2013-09-10 09:52:35 +0800532 ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE,
533 GFP_KERNEL);
Tejun Heo229641a2013-04-01 17:08:13 -0700534 if (ret >= 0) {
Tejun Heoe68035f2013-03-13 14:59:38 -0700535 pool->id = ret;
Tejun Heo229641a2013-04-01 17:08:13 -0700536 return 0;
537 }
Tejun Heo9daf9e62013-01-24 11:01:33 -0800538 return ret;
539}
540
Tejun Heo76af4d92013-03-12 11:30:00 -0700541/**
Tejun Heodf2d5ae2013-04-01 11:23:35 -0700542 * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
543 * @wq: the target workqueue
544 * @node: the node ID
545 *
546 * This must be called either with pwq_lock held or sched RCU read locked.
547 * If the pwq needs to be used beyond the locking in effect, the caller is
548 * responsible for guaranteeing that the pwq stays online.
Yacine Belkadid185af32013-07-31 14:59:24 -0700549 *
550 * Return: The unbound pool_workqueue for @node.
Tejun Heodf2d5ae2013-04-01 11:23:35 -0700551 */
552static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq,
553 int node)
554{
555 assert_rcu_or_wq_mutex(wq);
556 return rcu_dereference_raw(wq->numa_pwq_tbl[node]);
557}
558
Tejun Heo73f53c42010-06-29 10:07:11 +0200559static unsigned int work_color_to_flags(int color)
560{
561 return color << WORK_STRUCT_COLOR_SHIFT;
562}
563
564static int get_work_color(struct work_struct *work)
565{
566 return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
567 ((1 << WORK_STRUCT_COLOR_BITS) - 1);
568}
569
570static int work_next_color(int color)
571{
572 return (color + 1) % WORK_NR_COLORS;
Oleg Nesterova848e3b2007-05-09 02:34:17 -0700573}
574
David Howells4594bf12006-12-07 11:33:26 +0000575/*
Tejun Heo112202d2013-02-13 19:29:12 -0800576 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
577 * contain the pointer to the queued pwq. Once execution starts, the flag
Tejun Heo7c3eed52013-01-24 11:01:33 -0800578 * is cleared and the high bits contain OFFQ flags and pool ID.
Tejun Heo7a22ad72010-06-29 10:07:13 +0200579 *
Tejun Heo112202d2013-02-13 19:29:12 -0800580 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
581 * and clear_work_data() can be used to set the pwq, pool or clear
Tejun Heobbb68df2012-08-03 10:30:46 -0700582 * work->data. These functions should only be called while the work is
583 * owned - ie. while the PENDING bit is set.
Tejun Heo7a22ad72010-06-29 10:07:13 +0200584 *
Tejun Heo112202d2013-02-13 19:29:12 -0800585 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
Tejun Heo7c3eed52013-01-24 11:01:33 -0800586 * corresponding to a work. Pool is available once the work has been
Tejun Heo112202d2013-02-13 19:29:12 -0800587 * queued anywhere after initialization until it is sync canceled. pwq is
Tejun Heo7c3eed52013-01-24 11:01:33 -0800588 * available only while the work item is queued.
Tejun Heobbb68df2012-08-03 10:30:46 -0700589 *
590 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
591 * canceled. While being canceled, a work item may have its PENDING set
592 * but stay off timer and worklist for arbitrarily long and nobody should
593 * try to steal the PENDING bit.
David Howells4594bf12006-12-07 11:33:26 +0000594 */
Tejun Heo7a22ad72010-06-29 10:07:13 +0200595static inline void set_work_data(struct work_struct *work, unsigned long data,
596 unsigned long flags)
David Howells365970a2006-11-22 14:54:49 +0000597{
Tejun Heo6183c002013-03-12 11:29:57 -0700598 WARN_ON_ONCE(!work_pending(work));
Tejun Heo7a22ad72010-06-29 10:07:13 +0200599 atomic_long_set(&work->data, data | flags | work_static(work));
David Howells365970a2006-11-22 14:54:49 +0000600}
David Howells365970a2006-11-22 14:54:49 +0000601
Tejun Heo112202d2013-02-13 19:29:12 -0800602static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq,
Tejun Heo7a22ad72010-06-29 10:07:13 +0200603 unsigned long extra_flags)
Oleg Nesterov4d707b92010-04-23 17:40:40 +0200604{
Tejun Heo112202d2013-02-13 19:29:12 -0800605 set_work_data(work, (unsigned long)pwq,
606 WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags);
Oleg Nesterov4d707b92010-04-23 17:40:40 +0200607}
608
Lai Jiangshan4468a002013-02-06 18:04:53 -0800609static void set_work_pool_and_keep_pending(struct work_struct *work,
610 int pool_id)
611{
612 set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
613 WORK_STRUCT_PENDING);
614}
615
Tejun Heo7c3eed52013-01-24 11:01:33 -0800616static void set_work_pool_and_clear_pending(struct work_struct *work,
617 int pool_id)
David Howells365970a2006-11-22 14:54:49 +0000618{
Tejun Heo23657bb2012-08-13 17:08:19 -0700619 /*
620 * The following wmb is paired with the implied mb in
621 * test_and_set_bit(PENDING) and ensures all updates to @work made
622 * here are visible to and precede any updates by the next PENDING
623 * owner.
624 */
625 smp_wmb();
Tejun Heo7c3eed52013-01-24 11:01:33 -0800626 set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
Tejun Heo7a22ad72010-06-29 10:07:13 +0200627}
628
629static void clear_work_data(struct work_struct *work)
630{
Tejun Heo7c3eed52013-01-24 11:01:33 -0800631 smp_wmb(); /* see set_work_pool_and_clear_pending() */
632 set_work_data(work, WORK_STRUCT_NO_POOL, 0);
Tejun Heo7a22ad72010-06-29 10:07:13 +0200633}
634
Tejun Heo112202d2013-02-13 19:29:12 -0800635static struct pool_workqueue *get_work_pwq(struct work_struct *work)
Tejun Heo7a22ad72010-06-29 10:07:13 +0200636{
Tejun Heoe1201532010-07-22 14:14:25 +0200637 unsigned long data = atomic_long_read(&work->data);
Tejun Heo7a22ad72010-06-29 10:07:13 +0200638
Tejun Heo112202d2013-02-13 19:29:12 -0800639 if (data & WORK_STRUCT_PWQ)
Tejun Heoe1201532010-07-22 14:14:25 +0200640 return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
641 else
642 return NULL;
Tejun Heo7a22ad72010-06-29 10:07:13 +0200643}
644
Tejun Heo7c3eed52013-01-24 11:01:33 -0800645/**
646 * get_work_pool - return the worker_pool a given work was associated with
647 * @work: the work item of interest
648 *
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700649 * Pools are created and destroyed under wq_pool_mutex, and allows read
650 * access under sched-RCU read lock. As such, this function should be
651 * called under wq_pool_mutex or with preemption disabled.
Tejun Heofa1b54e2013-03-12 11:30:00 -0700652 *
653 * All fields of the returned pool are accessible as long as the above
654 * mentioned locking is in effect. If the returned pool needs to be used
655 * beyond the critical section, the caller is responsible for ensuring the
656 * returned pool is and stays online.
Yacine Belkadid185af32013-07-31 14:59:24 -0700657 *
658 * Return: The worker_pool @work was last associated with. %NULL if none.
Tejun Heo7c3eed52013-01-24 11:01:33 -0800659 */
660static struct worker_pool *get_work_pool(struct work_struct *work)
Tejun Heo7a22ad72010-06-29 10:07:13 +0200661{
Tejun Heoe1201532010-07-22 14:14:25 +0200662 unsigned long data = atomic_long_read(&work->data);
Tejun Heo7c3eed52013-01-24 11:01:33 -0800663 int pool_id;
Tejun Heo7a22ad72010-06-29 10:07:13 +0200664
Lai Jiangshan68e13a62013-03-25 16:57:17 -0700665 assert_rcu_or_pool_mutex();
Tejun Heofa1b54e2013-03-12 11:30:00 -0700666
Tejun Heo112202d2013-02-13 19:29:12 -0800667 if (data & WORK_STRUCT_PWQ)
668 return ((struct pool_workqueue *)
Tejun Heo7c3eed52013-01-24 11:01:33 -0800669 (data & WORK_STRUCT_WQ_DATA_MASK))->pool;
Tejun Heo7a22ad72010-06-29 10:07:13 +0200670
Tejun Heo7c3eed52013-01-24 11:01:33 -0800671 pool_id = data >> WORK_OFFQ_POOL_SHIFT;
672 if (pool_id == WORK_OFFQ_POOL_NONE)
Tejun Heo7a22ad72010-06-29 10:07:13 +0200673 return NULL;
674
Tejun Heofa1b54e2013-03-12 11:30:00 -0700675 return idr_find(&worker_pool_idr, pool_id);
Tejun Heo7c3eed52013-01-24 11:01:33 -0800676}
677
678/**
679 * get_work_pool_id - return the worker pool ID a given work is associated with
680 * @work: the work item of interest
681 *
Yacine Belkadid185af32013-07-31 14:59:24 -0700682 * Return: The worker_pool ID @work was last associated with.
Tejun Heo7c3eed52013-01-24 11:01:33 -0800683 * %WORK_OFFQ_POOL_NONE if none.
684 */
685static int get_work_pool_id(struct work_struct *work)
686{
Lai Jiangshan54d5b7d2013-02-07 13:14:20 -0800687 unsigned long data = atomic_long_read(&work->data);
Tejun Heo7c3eed52013-01-24 11:01:33 -0800688
Tejun Heo112202d2013-02-13 19:29:12 -0800689 if (data & WORK_STRUCT_PWQ)
690 return ((struct pool_workqueue *)
Lai Jiangshan54d5b7d2013-02-07 13:14:20 -0800691 (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
692
693 return data >> WORK_OFFQ_POOL_SHIFT;
Tejun Heo7c3eed52013-01-24 11:01:33 -0800694}
695
Tejun Heobbb68df2012-08-03 10:30:46 -0700696static void mark_work_canceling(struct work_struct *work)
697{
Tejun Heo7c3eed52013-01-24 11:01:33 -0800698 unsigned long pool_id = get_work_pool_id(work);
Tejun Heobbb68df2012-08-03 10:30:46 -0700699
Tejun Heo7c3eed52013-01-24 11:01:33 -0800700 pool_id <<= WORK_OFFQ_POOL_SHIFT;
701 set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
Tejun Heobbb68df2012-08-03 10:30:46 -0700702}
703
704static bool work_is_canceling(struct work_struct *work)
705{
706 unsigned long data = atomic_long_read(&work->data);
707
Tejun Heo112202d2013-02-13 19:29:12 -0800708 return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
Tejun Heobbb68df2012-08-03 10:30:46 -0700709}
710
David Howells365970a2006-11-22 14:54:49 +0000711/*
Tejun Heo32704762012-07-13 22:16:45 -0700712 * Policy functions. These define the policies on how the global worker
713 * pools are managed. Unless noted otherwise, these functions assume that
Tejun Heod565ed62013-01-24 11:01:33 -0800714 * they're being called with pool->lock held.
David Howells365970a2006-11-22 14:54:49 +0000715 */
Tejun Heoe22bee72010-06-29 10:07:14 +0200716
Tejun Heo63d95a92012-07-12 14:46:37 -0700717static bool __need_more_worker(struct worker_pool *pool)
David Howells365970a2006-11-22 14:54:49 +0000718{
Tejun Heoe19e3972013-01-24 11:39:44 -0800719 return !atomic_read(&pool->nr_running);
David Howells365970a2006-11-22 14:54:49 +0000720}
721
Tejun Heoe22bee72010-06-29 10:07:14 +0200722/*
723 * Need to wake up a worker? Called from anything but currently
724 * running workers.
Tejun Heo974271c2012-07-12 14:46:37 -0700725 *
726 * Note that, because unbound workers never contribute to nr_running, this
Tejun Heo706026c2013-01-24 11:01:34 -0800727 * function will always return %true for unbound pools as long as the
Tejun Heo974271c2012-07-12 14:46:37 -0700728 * worklist isn't empty.
Tejun Heoe22bee72010-06-29 10:07:14 +0200729 */
Tejun Heo63d95a92012-07-12 14:46:37 -0700730static bool need_more_worker(struct worker_pool *pool)
David Howells365970a2006-11-22 14:54:49 +0000731{
Tejun Heo63d95a92012-07-12 14:46:37 -0700732 return !list_empty(&pool->worklist) && __need_more_worker(pool);
David Howells365970a2006-11-22 14:54:49 +0000733}
734
Tejun Heoe22bee72010-06-29 10:07:14 +0200735/* Can I start working? Called from busy but !running workers. */
Tejun Heo63d95a92012-07-12 14:46:37 -0700736static bool may_start_working(struct worker_pool *pool)
Tejun Heoe22bee72010-06-29 10:07:14 +0200737{
Tejun Heo63d95a92012-07-12 14:46:37 -0700738 return pool->nr_idle;
Tejun Heoe22bee72010-06-29 10:07:14 +0200739}
740
741/* Do I need to keep working? Called from currently running workers. */
Tejun Heo63d95a92012-07-12 14:46:37 -0700742static bool keep_working(struct worker_pool *pool)
Tejun Heoe22bee72010-06-29 10:07:14 +0200743{
Tejun Heoe19e3972013-01-24 11:39:44 -0800744 return !list_empty(&pool->worklist) &&
745 atomic_read(&pool->nr_running) <= 1;
Tejun Heoe22bee72010-06-29 10:07:14 +0200746}
747
748/* Do we need a new worker? Called from manager. */
Tejun Heo63d95a92012-07-12 14:46:37 -0700749static bool need_to_create_worker(struct worker_pool *pool)
Tejun Heoe22bee72010-06-29 10:07:14 +0200750{
Tejun Heo63d95a92012-07-12 14:46:37 -0700751 return need_more_worker(pool) && !may_start_working(pool);
Tejun Heoe22bee72010-06-29 10:07:14 +0200752}
753
Tejun Heoe22bee72010-06-29 10:07:14 +0200754/* Do we have too many workers and should some go away? */
Tejun Heo63d95a92012-07-12 14:46:37 -0700755static bool too_many_workers(struct worker_pool *pool)
Tejun Heoe22bee72010-06-29 10:07:14 +0200756{
Tejun Heo34a06bd2013-03-12 11:30:00 -0700757 bool managing = mutex_is_locked(&pool->manager_arb);
Tejun Heo63d95a92012-07-12 14:46:37 -0700758 int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
759 int nr_busy = pool->nr_workers - nr_idle;
Tejun Heoe22bee72010-06-29 10:07:14 +0200760
761 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
762}
763
764/*
765 * Wake up functions.
766 */
767
Lai Jiangshan1037de32014-05-22 16:44:07 +0800768/* Return the first idle worker. Safe with preemption disabled */
769static struct worker *first_idle_worker(struct worker_pool *pool)
Tejun Heo7e116292010-06-29 10:07:13 +0200770{
Tejun Heo63d95a92012-07-12 14:46:37 -0700771 if (unlikely(list_empty(&pool->idle_list)))
Tejun Heo7e116292010-06-29 10:07:13 +0200772 return NULL;
773
Tejun Heo63d95a92012-07-12 14:46:37 -0700774 return list_first_entry(&pool->idle_list, struct worker, entry);
Tejun Heo7e116292010-06-29 10:07:13 +0200775}
776
777/**
778 * wake_up_worker - wake up an idle worker
Tejun Heo63d95a92012-07-12 14:46:37 -0700779 * @pool: worker pool to wake worker from
Tejun Heo7e116292010-06-29 10:07:13 +0200780 *
Tejun Heo63d95a92012-07-12 14:46:37 -0700781 * Wake up the first idle worker of @pool.
Tejun Heo7e116292010-06-29 10:07:13 +0200782 *
783 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -0800784 * spin_lock_irq(pool->lock).
Tejun Heo7e116292010-06-29 10:07:13 +0200785 */
Tejun Heo63d95a92012-07-12 14:46:37 -0700786static void wake_up_worker(struct worker_pool *pool)
Tejun Heo7e116292010-06-29 10:07:13 +0200787{
Lai Jiangshan1037de32014-05-22 16:44:07 +0800788 struct worker *worker = first_idle_worker(pool);
Tejun Heo7e116292010-06-29 10:07:13 +0200789
790 if (likely(worker))
791 wake_up_process(worker->task);
792}
793
Tejun Heo4690c4a2010-06-29 10:07:10 +0200794/**
Tejun Heoe22bee72010-06-29 10:07:14 +0200795 * wq_worker_waking_up - a worker is waking up
796 * @task: task waking up
797 * @cpu: CPU @task is waking up to
798 *
799 * This function is called during try_to_wake_up() when a worker is
800 * being awoken.
801 *
802 * CONTEXT:
803 * spin_lock_irq(rq->lock)
804 */
Tejun Heod84ff052013-03-12 11:29:59 -0700805void wq_worker_waking_up(struct task_struct *task, int cpu)
Tejun Heoe22bee72010-06-29 10:07:14 +0200806{
807 struct worker *worker = kthread_data(task);
808
Joonsoo Kim36576002012-10-26 23:03:49 +0900809 if (!(worker->flags & WORKER_NOT_RUNNING)) {
Tejun Heoec22ca52013-01-24 11:01:33 -0800810 WARN_ON_ONCE(worker->pool->cpu != cpu);
Tejun Heoe19e3972013-01-24 11:39:44 -0800811 atomic_inc(&worker->pool->nr_running);
Joonsoo Kim36576002012-10-26 23:03:49 +0900812 }
Tejun Heoe22bee72010-06-29 10:07:14 +0200813}
814
815/**
816 * wq_worker_sleeping - a worker is going to sleep
817 * @task: task going to sleep
818 * @cpu: CPU in question, must be the current CPU number
819 *
820 * This function is called during schedule() when a busy worker is
821 * going to sleep. Worker on the same cpu can be woken up by
822 * returning pointer to its task.
823 *
824 * CONTEXT:
825 * spin_lock_irq(rq->lock)
826 *
Yacine Belkadid185af32013-07-31 14:59:24 -0700827 * Return:
Tejun Heoe22bee72010-06-29 10:07:14 +0200828 * Worker task on @cpu to wake up, %NULL if none.
829 */
Tejun Heod84ff052013-03-12 11:29:59 -0700830struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu)
Tejun Heoe22bee72010-06-29 10:07:14 +0200831{
832 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
Tejun Heo111c2252013-01-17 17:16:24 -0800833 struct worker_pool *pool;
Tejun Heoe22bee72010-06-29 10:07:14 +0200834
Tejun Heo111c2252013-01-17 17:16:24 -0800835 /*
836 * Rescuers, which may not have all the fields set up like normal
837 * workers, also reach here, let's not access anything before
838 * checking NOT_RUNNING.
839 */
Steven Rostedt2d646722010-12-03 23:12:33 -0500840 if (worker->flags & WORKER_NOT_RUNNING)
Tejun Heoe22bee72010-06-29 10:07:14 +0200841 return NULL;
842
Tejun Heo111c2252013-01-17 17:16:24 -0800843 pool = worker->pool;
Tejun Heo111c2252013-01-17 17:16:24 -0800844
Tejun Heoe22bee72010-06-29 10:07:14 +0200845 /* this can only happen on the local cpu */
Tejun Heo6183c002013-03-12 11:29:57 -0700846 if (WARN_ON_ONCE(cpu != raw_smp_processor_id()))
847 return NULL;
Tejun Heoe22bee72010-06-29 10:07:14 +0200848
849 /*
850 * The counterpart of the following dec_and_test, implied mb,
851 * worklist not empty test sequence is in insert_work().
852 * Please read comment there.
853 *
Tejun Heo628c78e2012-07-17 12:39:27 -0700854 * NOT_RUNNING is clear. This means that we're bound to and
855 * running on the local cpu w/ rq lock held and preemption
856 * disabled, which in turn means that none else could be
Tejun Heod565ed62013-01-24 11:01:33 -0800857 * manipulating idle_list, so dereferencing idle_list without pool
Tejun Heo628c78e2012-07-17 12:39:27 -0700858 * lock is safe.
Tejun Heoe22bee72010-06-29 10:07:14 +0200859 */
Tejun Heoe19e3972013-01-24 11:39:44 -0800860 if (atomic_dec_and_test(&pool->nr_running) &&
861 !list_empty(&pool->worklist))
Lai Jiangshan1037de32014-05-22 16:44:07 +0800862 to_wakeup = first_idle_worker(pool);
Tejun Heoe22bee72010-06-29 10:07:14 +0200863 return to_wakeup ? to_wakeup->task : NULL;
864}
865
866/**
867 * worker_set_flags - set worker flags and adjust nr_running accordingly
Tejun Heocb444762010-07-02 10:03:50 +0200868 * @worker: self
Tejun Heod302f012010-06-29 10:07:13 +0200869 * @flags: flags to set
870 * @wakeup: wakeup an idle worker if necessary
871 *
Tejun Heoe22bee72010-06-29 10:07:14 +0200872 * Set @flags in @worker->flags and adjust nr_running accordingly. If
873 * nr_running becomes zero and @wakeup is %true, an idle worker is
874 * woken up.
Tejun Heod302f012010-06-29 10:07:13 +0200875 *
Tejun Heocb444762010-07-02 10:03:50 +0200876 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -0800877 * spin_lock_irq(pool->lock)
Tejun Heod302f012010-06-29 10:07:13 +0200878 */
879static inline void worker_set_flags(struct worker *worker, unsigned int flags,
880 bool wakeup)
881{
Tejun Heobd7bdd42012-07-12 14:46:37 -0700882 struct worker_pool *pool = worker->pool;
Tejun Heoe22bee72010-06-29 10:07:14 +0200883
Tejun Heocb444762010-07-02 10:03:50 +0200884 WARN_ON_ONCE(worker->task != current);
885
Tejun Heoe22bee72010-06-29 10:07:14 +0200886 /*
887 * If transitioning into NOT_RUNNING, adjust nr_running and
888 * wake up an idle worker as necessary if requested by
889 * @wakeup.
890 */
891 if ((flags & WORKER_NOT_RUNNING) &&
892 !(worker->flags & WORKER_NOT_RUNNING)) {
Tejun Heoe22bee72010-06-29 10:07:14 +0200893 if (wakeup) {
Tejun Heoe19e3972013-01-24 11:39:44 -0800894 if (atomic_dec_and_test(&pool->nr_running) &&
Tejun Heobd7bdd42012-07-12 14:46:37 -0700895 !list_empty(&pool->worklist))
Tejun Heo63d95a92012-07-12 14:46:37 -0700896 wake_up_worker(pool);
Tejun Heoe22bee72010-06-29 10:07:14 +0200897 } else
Tejun Heoe19e3972013-01-24 11:39:44 -0800898 atomic_dec(&pool->nr_running);
Tejun Heoe22bee72010-06-29 10:07:14 +0200899 }
900
Tejun Heod302f012010-06-29 10:07:13 +0200901 worker->flags |= flags;
902}
903
904/**
Tejun Heoe22bee72010-06-29 10:07:14 +0200905 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
Tejun Heocb444762010-07-02 10:03:50 +0200906 * @worker: self
Tejun Heod302f012010-06-29 10:07:13 +0200907 * @flags: flags to clear
908 *
Tejun Heoe22bee72010-06-29 10:07:14 +0200909 * Clear @flags in @worker->flags and adjust nr_running accordingly.
Tejun Heod302f012010-06-29 10:07:13 +0200910 *
Tejun Heocb444762010-07-02 10:03:50 +0200911 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -0800912 * spin_lock_irq(pool->lock)
Tejun Heod302f012010-06-29 10:07:13 +0200913 */
914static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
915{
Tejun Heo63d95a92012-07-12 14:46:37 -0700916 struct worker_pool *pool = worker->pool;
Tejun Heoe22bee72010-06-29 10:07:14 +0200917 unsigned int oflags = worker->flags;
918
Tejun Heocb444762010-07-02 10:03:50 +0200919 WARN_ON_ONCE(worker->task != current);
920
Tejun Heod302f012010-06-29 10:07:13 +0200921 worker->flags &= ~flags;
Tejun Heoe22bee72010-06-29 10:07:14 +0200922
Tejun Heo42c025f2011-01-11 15:58:49 +0100923 /*
924 * If transitioning out of NOT_RUNNING, increment nr_running. Note
925 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
926 * of multiple flags, not a single flag.
927 */
Tejun Heoe22bee72010-06-29 10:07:14 +0200928 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
929 if (!(worker->flags & WORKER_NOT_RUNNING))
Tejun Heoe19e3972013-01-24 11:39:44 -0800930 atomic_inc(&pool->nr_running);
Tejun Heod302f012010-06-29 10:07:13 +0200931}
932
933/**
Tejun Heo8cca0ee2010-06-29 10:07:13 +0200934 * find_worker_executing_work - find worker which is executing a work
Tejun Heoc9e7cf22013-01-24 11:01:33 -0800935 * @pool: pool of interest
Tejun Heo8cca0ee2010-06-29 10:07:13 +0200936 * @work: work to find worker for
937 *
Tejun Heoc9e7cf22013-01-24 11:01:33 -0800938 * Find a worker which is executing @work on @pool by searching
939 * @pool->busy_hash which is keyed by the address of @work. For a worker
Tejun Heoa2c1c572012-12-18 10:35:02 -0800940 * to match, its current execution should match the address of @work and
941 * its work function. This is to avoid unwanted dependency between
942 * unrelated work executions through a work item being recycled while still
943 * being executed.
944 *
945 * This is a bit tricky. A work item may be freed once its execution
946 * starts and nothing prevents the freed area from being recycled for
947 * another work item. If the same work item address ends up being reused
948 * before the original execution finishes, workqueue will identify the
949 * recycled work item as currently executing and make it wait until the
950 * current execution finishes, introducing an unwanted dependency.
951 *
Tejun Heoc5aa87b2013-03-13 16:51:36 -0700952 * This function checks the work item address and work function to avoid
953 * false positives. Note that this isn't complete as one may construct a
954 * work function which can introduce dependency onto itself through a
955 * recycled work item. Well, if somebody wants to shoot oneself in the
956 * foot that badly, there's only so much we can do, and if such deadlock
957 * actually occurs, it should be easy to locate the culprit work function.
Tejun Heo8cca0ee2010-06-29 10:07:13 +0200958 *
959 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -0800960 * spin_lock_irq(pool->lock).
Tejun Heo8cca0ee2010-06-29 10:07:13 +0200961 *
Yacine Belkadid185af32013-07-31 14:59:24 -0700962 * Return:
963 * Pointer to worker which is executing @work if found, %NULL
Tejun Heo8cca0ee2010-06-29 10:07:13 +0200964 * otherwise.
965 */
Tejun Heoc9e7cf22013-01-24 11:01:33 -0800966static struct worker *find_worker_executing_work(struct worker_pool *pool,
Tejun Heo8cca0ee2010-06-29 10:07:13 +0200967 struct work_struct *work)
968{
Sasha Levin42f85702012-12-17 10:01:23 -0500969 struct worker *worker;
Sasha Levin42f85702012-12-17 10:01:23 -0500970
Sasha Levinb67bfe02013-02-27 17:06:00 -0800971 hash_for_each_possible(pool->busy_hash, worker, hentry,
Tejun Heoa2c1c572012-12-18 10:35:02 -0800972 (unsigned long)work)
973 if (worker->current_work == work &&
974 worker->current_func == work->func)
Sasha Levin42f85702012-12-17 10:01:23 -0500975 return worker;
976
977 return NULL;
Tejun Heo8cca0ee2010-06-29 10:07:13 +0200978}
979
980/**
Tejun Heobf4ede02012-08-03 10:30:46 -0700981 * move_linked_works - move linked works to a list
982 * @work: start of series of works to be scheduled
983 * @head: target list to append @work to
984 * @nextp: out paramter for nested worklist walking
985 *
986 * Schedule linked works starting from @work to @head. Work series to
987 * be scheduled starts at @work and includes any consecutive work with
988 * WORK_STRUCT_LINKED set in its predecessor.
989 *
990 * If @nextp is not NULL, it's updated to point to the next work of
991 * the last scheduled work. This allows move_linked_works() to be
992 * nested inside outer list_for_each_entry_safe().
993 *
994 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -0800995 * spin_lock_irq(pool->lock).
Tejun Heobf4ede02012-08-03 10:30:46 -0700996 */
997static void move_linked_works(struct work_struct *work, struct list_head *head,
998 struct work_struct **nextp)
999{
1000 struct work_struct *n;
1001
1002 /*
1003 * Linked worklist will always end before the end of the list,
1004 * use NULL for list head.
1005 */
1006 list_for_each_entry_safe_from(work, n, NULL, entry) {
1007 list_move_tail(&work->entry, head);
1008 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1009 break;
1010 }
1011
1012 /*
1013 * If we're already inside safe list traversal and have moved
1014 * multiple works to the scheduled queue, the next position
1015 * needs to be updated.
1016 */
1017 if (nextp)
1018 *nextp = n;
1019}
1020
Tejun Heo8864b4e2013-03-12 11:30:04 -07001021/**
1022 * get_pwq - get an extra reference on the specified pool_workqueue
1023 * @pwq: pool_workqueue to get
1024 *
1025 * Obtain an extra reference on @pwq. The caller should guarantee that
1026 * @pwq has positive refcnt and be holding the matching pool->lock.
1027 */
1028static void get_pwq(struct pool_workqueue *pwq)
1029{
1030 lockdep_assert_held(&pwq->pool->lock);
1031 WARN_ON_ONCE(pwq->refcnt <= 0);
1032 pwq->refcnt++;
1033}
1034
1035/**
1036 * put_pwq - put a pool_workqueue reference
1037 * @pwq: pool_workqueue to put
1038 *
1039 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1040 * destruction. The caller should be holding the matching pool->lock.
1041 */
1042static void put_pwq(struct pool_workqueue *pwq)
1043{
1044 lockdep_assert_held(&pwq->pool->lock);
1045 if (likely(--pwq->refcnt))
1046 return;
1047 if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND)))
1048 return;
1049 /*
1050 * @pwq can't be released under pool->lock, bounce to
1051 * pwq_unbound_release_workfn(). This never recurses on the same
1052 * pool->lock as this path is taken only for unbound workqueues and
1053 * the release work item is scheduled on a per-cpu workqueue. To
1054 * avoid lockdep warning, unbound pool->locks are given lockdep
1055 * subclass of 1 in get_unbound_pool().
1056 */
1057 schedule_work(&pwq->unbound_release_work);
1058}
1059
Tejun Heodce90d42013-04-01 11:23:35 -07001060/**
1061 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1062 * @pwq: pool_workqueue to put (can be %NULL)
1063 *
1064 * put_pwq() with locking. This function also allows %NULL @pwq.
1065 */
1066static void put_pwq_unlocked(struct pool_workqueue *pwq)
1067{
1068 if (pwq) {
1069 /*
1070 * As both pwqs and pools are sched-RCU protected, the
1071 * following lock operations are safe.
1072 */
1073 spin_lock_irq(&pwq->pool->lock);
1074 put_pwq(pwq);
1075 spin_unlock_irq(&pwq->pool->lock);
1076 }
1077}
1078
Tejun Heo112202d2013-02-13 19:29:12 -08001079static void pwq_activate_delayed_work(struct work_struct *work)
Tejun Heobf4ede02012-08-03 10:30:46 -07001080{
Tejun Heo112202d2013-02-13 19:29:12 -08001081 struct pool_workqueue *pwq = get_work_pwq(work);
Tejun Heobf4ede02012-08-03 10:30:46 -07001082
1083 trace_workqueue_activate_work(work);
Tejun Heo112202d2013-02-13 19:29:12 -08001084 move_linked_works(work, &pwq->pool->worklist, NULL);
Tejun Heobf4ede02012-08-03 10:30:46 -07001085 __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
Tejun Heo112202d2013-02-13 19:29:12 -08001086 pwq->nr_active++;
Tejun Heobf4ede02012-08-03 10:30:46 -07001087}
1088
Tejun Heo112202d2013-02-13 19:29:12 -08001089static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
Lai Jiangshan3aa62492012-09-18 10:40:00 -07001090{
Tejun Heo112202d2013-02-13 19:29:12 -08001091 struct work_struct *work = list_first_entry(&pwq->delayed_works,
Lai Jiangshan3aa62492012-09-18 10:40:00 -07001092 struct work_struct, entry);
1093
Tejun Heo112202d2013-02-13 19:29:12 -08001094 pwq_activate_delayed_work(work);
Lai Jiangshan3aa62492012-09-18 10:40:00 -07001095}
1096
Tejun Heobf4ede02012-08-03 10:30:46 -07001097/**
Tejun Heo112202d2013-02-13 19:29:12 -08001098 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1099 * @pwq: pwq of interest
Tejun Heobf4ede02012-08-03 10:30:46 -07001100 * @color: color of work which left the queue
Tejun Heobf4ede02012-08-03 10:30:46 -07001101 *
1102 * A work either has completed or is removed from pending queue,
Tejun Heo112202d2013-02-13 19:29:12 -08001103 * decrement nr_in_flight of its pwq and handle workqueue flushing.
Tejun Heobf4ede02012-08-03 10:30:46 -07001104 *
1105 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -08001106 * spin_lock_irq(pool->lock).
Tejun Heobf4ede02012-08-03 10:30:46 -07001107 */
Tejun Heo112202d2013-02-13 19:29:12 -08001108static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
Tejun Heobf4ede02012-08-03 10:30:46 -07001109{
Tejun Heo8864b4e2013-03-12 11:30:04 -07001110 /* uncolored work items don't participate in flushing or nr_active */
Tejun Heobf4ede02012-08-03 10:30:46 -07001111 if (color == WORK_NO_COLOR)
Tejun Heo8864b4e2013-03-12 11:30:04 -07001112 goto out_put;
Tejun Heobf4ede02012-08-03 10:30:46 -07001113
Tejun Heo112202d2013-02-13 19:29:12 -08001114 pwq->nr_in_flight[color]--;
Tejun Heobf4ede02012-08-03 10:30:46 -07001115
Tejun Heo112202d2013-02-13 19:29:12 -08001116 pwq->nr_active--;
1117 if (!list_empty(&pwq->delayed_works)) {
Lai Jiangshanb3f9f402012-09-18 10:40:00 -07001118 /* one down, submit a delayed one */
Tejun Heo112202d2013-02-13 19:29:12 -08001119 if (pwq->nr_active < pwq->max_active)
1120 pwq_activate_first_delayed(pwq);
Tejun Heobf4ede02012-08-03 10:30:46 -07001121 }
1122
1123 /* is flush in progress and are we at the flushing tip? */
Tejun Heo112202d2013-02-13 19:29:12 -08001124 if (likely(pwq->flush_color != color))
Tejun Heo8864b4e2013-03-12 11:30:04 -07001125 goto out_put;
Tejun Heobf4ede02012-08-03 10:30:46 -07001126
1127 /* are there still in-flight works? */
Tejun Heo112202d2013-02-13 19:29:12 -08001128 if (pwq->nr_in_flight[color])
Tejun Heo8864b4e2013-03-12 11:30:04 -07001129 goto out_put;
Tejun Heobf4ede02012-08-03 10:30:46 -07001130
Tejun Heo112202d2013-02-13 19:29:12 -08001131 /* this pwq is done, clear flush_color */
1132 pwq->flush_color = -1;
Tejun Heobf4ede02012-08-03 10:30:46 -07001133
1134 /*
Tejun Heo112202d2013-02-13 19:29:12 -08001135 * If this was the last pwq, wake up the first flusher. It
Tejun Heobf4ede02012-08-03 10:30:46 -07001136 * will handle the rest.
1137 */
Tejun Heo112202d2013-02-13 19:29:12 -08001138 if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
1139 complete(&pwq->wq->first_flusher->done);
Tejun Heo8864b4e2013-03-12 11:30:04 -07001140out_put:
1141 put_pwq(pwq);
Tejun Heobf4ede02012-08-03 10:30:46 -07001142}
1143
Tejun Heo36e227d2012-08-03 10:30:46 -07001144/**
Tejun Heobbb68df2012-08-03 10:30:46 -07001145 * try_to_grab_pending - steal work item from worklist and disable irq
Tejun Heo36e227d2012-08-03 10:30:46 -07001146 * @work: work item to steal
1147 * @is_dwork: @work is a delayed_work
Tejun Heobbb68df2012-08-03 10:30:46 -07001148 * @flags: place to store irq state
Tejun Heo36e227d2012-08-03 10:30:46 -07001149 *
1150 * Try to grab PENDING bit of @work. This function can handle @work in any
Yacine Belkadid185af32013-07-31 14:59:24 -07001151 * stable state - idle, on timer or on worklist.
Tejun Heo36e227d2012-08-03 10:30:46 -07001152 *
Yacine Belkadid185af32013-07-31 14:59:24 -07001153 * Return:
Tejun Heo36e227d2012-08-03 10:30:46 -07001154 * 1 if @work was pending and we successfully stole PENDING
1155 * 0 if @work was idle and we claimed PENDING
1156 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
Tejun Heobbb68df2012-08-03 10:30:46 -07001157 * -ENOENT if someone else is canceling @work, this state may persist
1158 * for arbitrarily long
Tejun Heo36e227d2012-08-03 10:30:46 -07001159 *
Yacine Belkadid185af32013-07-31 14:59:24 -07001160 * Note:
Tejun Heobbb68df2012-08-03 10:30:46 -07001161 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
Tejun Heoe0aecdd2012-08-21 13:18:24 -07001162 * interrupted while holding PENDING and @work off queue, irq must be
1163 * disabled on entry. This, combined with delayed_work->timer being
1164 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
Tejun Heobbb68df2012-08-03 10:30:46 -07001165 *
1166 * On successful return, >= 0, irq is disabled and the caller is
1167 * responsible for releasing it using local_irq_restore(*@flags).
1168 *
Tejun Heoe0aecdd2012-08-21 13:18:24 -07001169 * This function is safe to call from any context including IRQ handler.
Tejun Heobf4ede02012-08-03 10:30:46 -07001170 */
Tejun Heobbb68df2012-08-03 10:30:46 -07001171static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
1172 unsigned long *flags)
Tejun Heobf4ede02012-08-03 10:30:46 -07001173{
Tejun Heod565ed62013-01-24 11:01:33 -08001174 struct worker_pool *pool;
Tejun Heo112202d2013-02-13 19:29:12 -08001175 struct pool_workqueue *pwq;
Tejun Heobf4ede02012-08-03 10:30:46 -07001176
Tejun Heobbb68df2012-08-03 10:30:46 -07001177 local_irq_save(*flags);
1178
Tejun Heo36e227d2012-08-03 10:30:46 -07001179 /* try to steal the timer if it exists */
1180 if (is_dwork) {
1181 struct delayed_work *dwork = to_delayed_work(work);
1182
Tejun Heoe0aecdd2012-08-21 13:18:24 -07001183 /*
1184 * dwork->timer is irqsafe. If del_timer() fails, it's
1185 * guaranteed that the timer is not queued anywhere and not
1186 * running on the local CPU.
1187 */
Tejun Heo36e227d2012-08-03 10:30:46 -07001188 if (likely(del_timer(&dwork->timer)))
1189 return 1;
1190 }
1191
1192 /* try to claim PENDING the normal way */
Tejun Heobf4ede02012-08-03 10:30:46 -07001193 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
1194 return 0;
1195
1196 /*
1197 * The queueing is in progress, or it is already queued. Try to
1198 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1199 */
Tejun Heod565ed62013-01-24 11:01:33 -08001200 pool = get_work_pool(work);
1201 if (!pool)
Tejun Heobbb68df2012-08-03 10:30:46 -07001202 goto fail;
Tejun Heobf4ede02012-08-03 10:30:46 -07001203
Tejun Heod565ed62013-01-24 11:01:33 -08001204 spin_lock(&pool->lock);
Lai Jiangshan0b3dae62013-02-06 18:04:53 -08001205 /*
Tejun Heo112202d2013-02-13 19:29:12 -08001206 * work->data is guaranteed to point to pwq only while the work
1207 * item is queued on pwq->wq, and both updating work->data to point
1208 * to pwq on queueing and to pool on dequeueing are done under
1209 * pwq->pool->lock. This in turn guarantees that, if work->data
1210 * points to pwq which is associated with a locked pool, the work
Lai Jiangshan0b3dae62013-02-06 18:04:53 -08001211 * item is currently queued on that pool.
1212 */
Tejun Heo112202d2013-02-13 19:29:12 -08001213 pwq = get_work_pwq(work);
1214 if (pwq && pwq->pool == pool) {
Tejun Heo16062832013-02-06 18:04:53 -08001215 debug_work_deactivate(work);
Lai Jiangshan3aa62492012-09-18 10:40:00 -07001216
Tejun Heo16062832013-02-06 18:04:53 -08001217 /*
1218 * A delayed work item cannot be grabbed directly because
1219 * it might have linked NO_COLOR work items which, if left
Tejun Heo112202d2013-02-13 19:29:12 -08001220 * on the delayed_list, will confuse pwq->nr_active
Tejun Heo16062832013-02-06 18:04:53 -08001221 * management later on and cause stall. Make sure the work
1222 * item is activated before grabbing.
1223 */
1224 if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
Tejun Heo112202d2013-02-13 19:29:12 -08001225 pwq_activate_delayed_work(work);
Lai Jiangshan3aa62492012-09-18 10:40:00 -07001226
Tejun Heo16062832013-02-06 18:04:53 -08001227 list_del_init(&work->entry);
Tejun Heo112202d2013-02-13 19:29:12 -08001228 pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work));
Tejun Heo36e227d2012-08-03 10:30:46 -07001229
Tejun Heo112202d2013-02-13 19:29:12 -08001230 /* work->data points to pwq iff queued, point to pool */
Tejun Heo16062832013-02-06 18:04:53 -08001231 set_work_pool_and_keep_pending(work, pool->id);
Lai Jiangshan4468a002013-02-06 18:04:53 -08001232
Tejun Heo16062832013-02-06 18:04:53 -08001233 spin_unlock(&pool->lock);
1234 return 1;
Tejun Heobf4ede02012-08-03 10:30:46 -07001235 }
Tejun Heod565ed62013-01-24 11:01:33 -08001236 spin_unlock(&pool->lock);
Tejun Heobbb68df2012-08-03 10:30:46 -07001237fail:
1238 local_irq_restore(*flags);
1239 if (work_is_canceling(work))
1240 return -ENOENT;
1241 cpu_relax();
Tejun Heo36e227d2012-08-03 10:30:46 -07001242 return -EAGAIN;
Tejun Heobf4ede02012-08-03 10:30:46 -07001243}
1244
1245/**
Tejun Heo706026c2013-01-24 11:01:34 -08001246 * insert_work - insert a work into a pool
Tejun Heo112202d2013-02-13 19:29:12 -08001247 * @pwq: pwq @work belongs to
Tejun Heo4690c4a2010-06-29 10:07:10 +02001248 * @work: work to insert
1249 * @head: insertion point
1250 * @extra_flags: extra WORK_STRUCT_* flags to set
1251 *
Tejun Heo112202d2013-02-13 19:29:12 -08001252 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
Tejun Heo706026c2013-01-24 11:01:34 -08001253 * work_struct flags.
Tejun Heo4690c4a2010-06-29 10:07:10 +02001254 *
1255 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -08001256 * spin_lock_irq(pool->lock).
Tejun Heo4690c4a2010-06-29 10:07:10 +02001257 */
Tejun Heo112202d2013-02-13 19:29:12 -08001258static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
1259 struct list_head *head, unsigned int extra_flags)
Oleg Nesterovb89deed2007-05-09 02:33:52 -07001260{
Tejun Heo112202d2013-02-13 19:29:12 -08001261 struct worker_pool *pool = pwq->pool;
Frederic Weisbeckere1d8aa92009-01-12 23:15:46 +01001262
Tejun Heo4690c4a2010-06-29 10:07:10 +02001263 /* we own @work, set data and link */
Tejun Heo112202d2013-02-13 19:29:12 -08001264 set_work_pwq(work, pwq, extra_flags);
Oleg Nesterov1a4d9b02008-07-25 01:47:47 -07001265 list_add_tail(&work->entry, head);
Tejun Heo8864b4e2013-03-12 11:30:04 -07001266 get_pwq(pwq);
Tejun Heoe22bee72010-06-29 10:07:14 +02001267
1268 /*
Tejun Heoc5aa87b2013-03-13 16:51:36 -07001269 * Ensure either wq_worker_sleeping() sees the above
1270 * list_add_tail() or we see zero nr_running to avoid workers lying
1271 * around lazily while there are works to be processed.
Tejun Heoe22bee72010-06-29 10:07:14 +02001272 */
1273 smp_mb();
1274
Tejun Heo63d95a92012-07-12 14:46:37 -07001275 if (__need_more_worker(pool))
1276 wake_up_worker(pool);
Oleg Nesterovb89deed2007-05-09 02:33:52 -07001277}
1278
Tejun Heoc8efcc22010-12-20 19:32:04 +01001279/*
1280 * Test whether @work is being queued from another work executing on the
Tejun Heo8d03ecf2013-02-13 19:29:10 -08001281 * same workqueue.
Tejun Heoc8efcc22010-12-20 19:32:04 +01001282 */
1283static bool is_chained_work(struct workqueue_struct *wq)
1284{
Tejun Heo8d03ecf2013-02-13 19:29:10 -08001285 struct worker *worker;
Tejun Heoc8efcc22010-12-20 19:32:04 +01001286
Tejun Heo8d03ecf2013-02-13 19:29:10 -08001287 worker = current_wq_worker();
1288 /*
1289 * Return %true iff I'm a worker execuing a work item on @wq. If
1290 * I'm @worker, it's safe to dereference it without locking.
1291 */
Tejun Heo112202d2013-02-13 19:29:12 -08001292 return worker && worker->current_pwq->wq == wq;
Tejun Heoc8efcc22010-12-20 19:32:04 +01001293}
1294
Tejun Heod84ff052013-03-12 11:29:59 -07001295static void __queue_work(int cpu, struct workqueue_struct *wq,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 struct work_struct *work)
1297{
Tejun Heo112202d2013-02-13 19:29:12 -08001298 struct pool_workqueue *pwq;
Tejun Heoc9178082013-03-12 11:30:04 -07001299 struct worker_pool *last_pool;
Tejun Heo1e19ffc2010-06-29 10:07:12 +02001300 struct list_head *worklist;
Tejun Heo8a2e8e5d2010-08-25 10:33:56 +02001301 unsigned int work_flags;
Joonsoo Kimb75cac92012-08-15 23:25:37 +09001302 unsigned int req_cpu = cpu;
Tejun Heo8930cab2012-08-03 10:30:45 -07001303
1304 /*
1305 * While a work item is PENDING && off queue, a task trying to
1306 * steal the PENDING will busy-loop waiting for it to either get
1307 * queued or lose PENDING. Grabbing PENDING and queueing should
1308 * happen with IRQ disabled.
1309 */
1310 WARN_ON_ONCE(!irqs_disabled());
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +09001312 debug_work_activate(work);
Tejun Heo1e19ffc2010-06-29 10:07:12 +02001313
Li Bin9ef28a72013-09-09 13:13:58 +08001314 /* if draining, only works from the same workqueue are allowed */
Tejun Heo618b01e2013-03-12 11:30:04 -07001315 if (unlikely(wq->flags & __WQ_DRAINING) &&
Tejun Heoc8efcc22010-12-20 19:32:04 +01001316 WARN_ON_ONCE(!is_chained_work(wq)))
Tejun Heoe41e7042010-08-24 14:22:47 +02001317 return;
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07001318retry:
Tejun Heodf2d5ae2013-04-01 11:23:35 -07001319 if (req_cpu == WORK_CPU_UNBOUND)
1320 cpu = raw_smp_processor_id();
1321
Tejun Heoc9178082013-03-12 11:30:04 -07001322 /* pwq which will be used unless @work is executing elsewhere */
Tejun Heodf2d5ae2013-04-01 11:23:35 -07001323 if (!(wq->flags & WQ_UNBOUND))
Tejun Heo7fb98ea2013-03-12 11:30:00 -07001324 pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
Tejun Heodf2d5ae2013-04-01 11:23:35 -07001325 else
1326 pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
Tejun Heodbf25762012-08-20 14:51:23 -07001327
Tejun Heoc9178082013-03-12 11:30:04 -07001328 /*
1329 * If @work was previously on a different pool, it might still be
1330 * running there, in which case the work needs to be queued on that
1331 * pool to guarantee non-reentrancy.
1332 */
1333 last_pool = get_work_pool(work);
1334 if (last_pool && last_pool != pwq->pool) {
1335 struct worker *worker;
Tejun Heo18aa9ef2010-06-29 10:07:13 +02001336
Tejun Heoc9178082013-03-12 11:30:04 -07001337 spin_lock(&last_pool->lock);
Tejun Heo18aa9ef2010-06-29 10:07:13 +02001338
Tejun Heoc9178082013-03-12 11:30:04 -07001339 worker = find_worker_executing_work(last_pool, work);
Tejun Heo18aa9ef2010-06-29 10:07:13 +02001340
Tejun Heoc9178082013-03-12 11:30:04 -07001341 if (worker && worker->current_pwq->wq == wq) {
1342 pwq = worker->current_pwq;
Tejun Heo8930cab2012-08-03 10:30:45 -07001343 } else {
Tejun Heoc9178082013-03-12 11:30:04 -07001344 /* meh... not running there, queue here */
1345 spin_unlock(&last_pool->lock);
Tejun Heo112202d2013-02-13 19:29:12 -08001346 spin_lock(&pwq->pool->lock);
Tejun Heo8930cab2012-08-03 10:30:45 -07001347 }
Tejun Heof3421792010-07-02 10:03:51 +02001348 } else {
Tejun Heo112202d2013-02-13 19:29:12 -08001349 spin_lock(&pwq->pool->lock);
Tejun Heo502ca9d2010-06-29 10:07:13 +02001350 }
1351
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07001352 /*
1353 * pwq is determined and locked. For unbound pools, we could have
1354 * raced with pwq release and it could already be dead. If its
1355 * refcnt is zero, repeat pwq selection. Note that pwqs never die
Tejun Heodf2d5ae2013-04-01 11:23:35 -07001356 * without another pwq replacing it in the numa_pwq_tbl or while
1357 * work items are executing on it, so the retrying is guaranteed to
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07001358 * make forward-progress.
1359 */
1360 if (unlikely(!pwq->refcnt)) {
1361 if (wq->flags & WQ_UNBOUND) {
1362 spin_unlock(&pwq->pool->lock);
1363 cpu_relax();
1364 goto retry;
1365 }
1366 /* oops */
1367 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1368 wq->name, cpu);
1369 }
1370
Tejun Heo112202d2013-02-13 19:29:12 -08001371 /* pwq determined, queue */
1372 trace_workqueue_queue_work(req_cpu, pwq, work);
Tejun Heo502ca9d2010-06-29 10:07:13 +02001373
Dan Carpenterf5b25522012-04-13 22:06:58 +03001374 if (WARN_ON(!list_empty(&work->entry))) {
Tejun Heo112202d2013-02-13 19:29:12 -08001375 spin_unlock(&pwq->pool->lock);
Dan Carpenterf5b25522012-04-13 22:06:58 +03001376 return;
1377 }
Tejun Heo1e19ffc2010-06-29 10:07:12 +02001378
Tejun Heo112202d2013-02-13 19:29:12 -08001379 pwq->nr_in_flight[pwq->work_color]++;
1380 work_flags = work_color_to_flags(pwq->work_color);
Tejun Heo1e19ffc2010-06-29 10:07:12 +02001381
Tejun Heo112202d2013-02-13 19:29:12 -08001382 if (likely(pwq->nr_active < pwq->max_active)) {
Tejun Heocdadf002010-10-05 10:49:55 +02001383 trace_workqueue_activate_work(work);
Tejun Heo112202d2013-02-13 19:29:12 -08001384 pwq->nr_active++;
1385 worklist = &pwq->pool->worklist;
Tejun Heo8a2e8e5d2010-08-25 10:33:56 +02001386 } else {
1387 work_flags |= WORK_STRUCT_DELAYED;
Tejun Heo112202d2013-02-13 19:29:12 -08001388 worklist = &pwq->delayed_works;
Tejun Heo8a2e8e5d2010-08-25 10:33:56 +02001389 }
Tejun Heo1e19ffc2010-06-29 10:07:12 +02001390
Tejun Heo112202d2013-02-13 19:29:12 -08001391 insert_work(pwq, work, worklist, work_flags);
Tejun Heo1e19ffc2010-06-29 10:07:12 +02001392
Tejun Heo112202d2013-02-13 19:29:12 -08001393 spin_unlock(&pwq->pool->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394}
1395
Rolf Eike Beer0fcb78c2006-07-30 03:03:42 -07001396/**
Zhang Ruic1a220e2008-07-23 21:28:39 -07001397 * queue_work_on - queue work on specific cpu
1398 * @cpu: CPU number to execute work on
1399 * @wq: workqueue to use
1400 * @work: work to queue
1401 *
Zhang Ruic1a220e2008-07-23 21:28:39 -07001402 * We queue the work to a specific CPU, the caller must ensure it
1403 * can't go away.
Yacine Belkadid185af32013-07-31 14:59:24 -07001404 *
1405 * Return: %false if @work was already on a queue, %true otherwise.
Zhang Ruic1a220e2008-07-23 21:28:39 -07001406 */
Tejun Heod4283e92012-08-03 10:30:44 -07001407bool queue_work_on(int cpu, struct workqueue_struct *wq,
1408 struct work_struct *work)
Zhang Ruic1a220e2008-07-23 21:28:39 -07001409{
Tejun Heod4283e92012-08-03 10:30:44 -07001410 bool ret = false;
Tejun Heo8930cab2012-08-03 10:30:45 -07001411 unsigned long flags;
1412
1413 local_irq_save(flags);
Zhang Ruic1a220e2008-07-23 21:28:39 -07001414
Tejun Heo22df02b2010-06-29 10:07:10 +02001415 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
Tejun Heo4690c4a2010-06-29 10:07:10 +02001416 __queue_work(cpu, wq, work);
Tejun Heod4283e92012-08-03 10:30:44 -07001417 ret = true;
Zhang Ruic1a220e2008-07-23 21:28:39 -07001418 }
Tejun Heo8930cab2012-08-03 10:30:45 -07001419
1420 local_irq_restore(flags);
Zhang Ruic1a220e2008-07-23 21:28:39 -07001421 return ret;
1422}
Marc Dionnead7b1f82013-05-06 17:44:55 -04001423EXPORT_SYMBOL(queue_work_on);
Zhang Ruic1a220e2008-07-23 21:28:39 -07001424
Tejun Heod8e794d2012-08-03 10:30:45 -07001425void delayed_work_timer_fn(unsigned long __data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426{
David Howells52bad642006-11-22 14:54:01 +00001427 struct delayed_work *dwork = (struct delayed_work *)__data;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428
Tejun Heoe0aecdd2012-08-21 13:18:24 -07001429 /* should have been called from irqsafe timer with irq already off */
Lai Jiangshan60c057b2013-02-06 18:04:53 -08001430 __queue_work(dwork->cpu, dwork->wq, &dwork->work);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431}
Konstantin Khlebnikov1438ade52013-01-24 16:36:31 +04001432EXPORT_SYMBOL(delayed_work_timer_fn);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433
Tejun Heo7beb2ed2012-08-03 10:30:46 -07001434static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
1435 struct delayed_work *dwork, unsigned long delay)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436{
Tejun Heo7beb2ed2012-08-03 10:30:46 -07001437 struct timer_list *timer = &dwork->timer;
1438 struct work_struct *work = &dwork->work;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439
Tejun Heo7beb2ed2012-08-03 10:30:46 -07001440 WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
1441 timer->data != (unsigned long)dwork);
Tejun Heofc4b5142012-12-04 07:40:39 -08001442 WARN_ON_ONCE(timer_pending(timer));
1443 WARN_ON_ONCE(!list_empty(&work->entry));
Tejun Heo7beb2ed2012-08-03 10:30:46 -07001444
Tejun Heo8852aac2012-12-01 16:23:42 -08001445 /*
1446 * If @delay is 0, queue @dwork->work immediately. This is for
1447 * both optimization and correctness. The earliest @timer can
1448 * expire is on the closest next tick and delayed_work users depend
1449 * on that there's no such delay when @delay is 0.
1450 */
1451 if (!delay) {
1452 __queue_work(cpu, wq, &dwork->work);
1453 return;
1454 }
1455
Tejun Heo7beb2ed2012-08-03 10:30:46 -07001456 timer_stats_timer_set_start_info(&dwork->timer);
1457
Lai Jiangshan60c057b2013-02-06 18:04:53 -08001458 dwork->wq = wq;
Tejun Heo12650572012-08-08 09:38:42 -07001459 dwork->cpu = cpu;
Tejun Heo7beb2ed2012-08-03 10:30:46 -07001460 timer->expires = jiffies + delay;
1461
1462 if (unlikely(cpu != WORK_CPU_UNBOUND))
1463 add_timer_on(timer, cpu);
1464 else
1465 add_timer(timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466}
1467
Rolf Eike Beer0fcb78c2006-07-30 03:03:42 -07001468/**
1469 * queue_delayed_work_on - queue work on specific CPU after delay
1470 * @cpu: CPU number to execute work on
1471 * @wq: workqueue to use
Randy Dunlapaf9997e2006-12-22 01:06:52 -08001472 * @dwork: work to queue
Rolf Eike Beer0fcb78c2006-07-30 03:03:42 -07001473 * @delay: number of jiffies to wait before queueing
1474 *
Yacine Belkadid185af32013-07-31 14:59:24 -07001475 * Return: %false if @work was already on a queue, %true otherwise. If
Tejun Heo715f1302012-08-03 10:30:46 -07001476 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1477 * execution.
Rolf Eike Beer0fcb78c2006-07-30 03:03:42 -07001478 */
Tejun Heod4283e92012-08-03 10:30:44 -07001479bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1480 struct delayed_work *dwork, unsigned long delay)
Venkatesh Pallipadi7a6bc1c2006-06-28 13:50:33 -07001481{
David Howells52bad642006-11-22 14:54:01 +00001482 struct work_struct *work = &dwork->work;
Tejun Heod4283e92012-08-03 10:30:44 -07001483 bool ret = false;
Tejun Heo8930cab2012-08-03 10:30:45 -07001484 unsigned long flags;
1485
1486 /* read the comment in __queue_work() */
1487 local_irq_save(flags);
Venkatesh Pallipadi7a6bc1c2006-06-28 13:50:33 -07001488
Tejun Heo22df02b2010-06-29 10:07:10 +02001489 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
Tejun Heo7beb2ed2012-08-03 10:30:46 -07001490 __queue_delayed_work(cpu, wq, dwork, delay);
Tejun Heod4283e92012-08-03 10:30:44 -07001491 ret = true;
Venkatesh Pallipadi7a6bc1c2006-06-28 13:50:33 -07001492 }
Tejun Heo8930cab2012-08-03 10:30:45 -07001493
1494 local_irq_restore(flags);
Venkatesh Pallipadi7a6bc1c2006-06-28 13:50:33 -07001495 return ret;
1496}
Marc Dionnead7b1f82013-05-06 17:44:55 -04001497EXPORT_SYMBOL(queue_delayed_work_on);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498
Tejun Heoc8e55f32010-06-29 10:07:12 +02001499/**
Tejun Heo8376fe22012-08-03 10:30:47 -07001500 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1501 * @cpu: CPU number to execute work on
1502 * @wq: workqueue to use
1503 * @dwork: work to queue
1504 * @delay: number of jiffies to wait before queueing
1505 *
1506 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1507 * modify @dwork's timer so that it expires after @delay. If @delay is
1508 * zero, @work is guaranteed to be scheduled immediately regardless of its
1509 * current state.
1510 *
Yacine Belkadid185af32013-07-31 14:59:24 -07001511 * Return: %false if @dwork was idle and queued, %true if @dwork was
Tejun Heo8376fe22012-08-03 10:30:47 -07001512 * pending and its timer was modified.
1513 *
Tejun Heoe0aecdd2012-08-21 13:18:24 -07001514 * This function is safe to call from any context including IRQ handler.
Tejun Heo8376fe22012-08-03 10:30:47 -07001515 * See try_to_grab_pending() for details.
1516 */
1517bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
1518 struct delayed_work *dwork, unsigned long delay)
1519{
1520 unsigned long flags;
1521 int ret;
1522
1523 do {
1524 ret = try_to_grab_pending(&dwork->work, true, &flags);
1525 } while (unlikely(ret == -EAGAIN));
1526
1527 if (likely(ret >= 0)) {
1528 __queue_delayed_work(cpu, wq, dwork, delay);
1529 local_irq_restore(flags);
1530 }
1531
1532 /* -ENOENT from try_to_grab_pending() becomes %true */
1533 return ret;
1534}
1535EXPORT_SYMBOL_GPL(mod_delayed_work_on);
1536
1537/**
Tejun Heoc8e55f32010-06-29 10:07:12 +02001538 * worker_enter_idle - enter idle state
1539 * @worker: worker which is entering idle state
1540 *
1541 * @worker is entering idle state. Update stats and idle timer if
1542 * necessary.
1543 *
1544 * LOCKING:
Tejun Heod565ed62013-01-24 11:01:33 -08001545 * spin_lock_irq(pool->lock).
Tejun Heoc8e55f32010-06-29 10:07:12 +02001546 */
1547static void worker_enter_idle(struct worker *worker)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548{
Tejun Heobd7bdd42012-07-12 14:46:37 -07001549 struct worker_pool *pool = worker->pool;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550
Tejun Heo6183c002013-03-12 11:29:57 -07001551 if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
1552 WARN_ON_ONCE(!list_empty(&worker->entry) &&
1553 (worker->hentry.next || worker->hentry.pprev)))
1554 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555
Tejun Heocb444762010-07-02 10:03:50 +02001556 /* can't use worker_set_flags(), also called from start_worker() */
1557 worker->flags |= WORKER_IDLE;
Tejun Heobd7bdd42012-07-12 14:46:37 -07001558 pool->nr_idle++;
Tejun Heoe22bee72010-06-29 10:07:14 +02001559 worker->last_active = jiffies;
Peter Zijlstrad5abe662006-12-06 20:37:26 -08001560
Tejun Heoc8e55f32010-06-29 10:07:12 +02001561 /* idle_list is LIFO */
Tejun Heobd7bdd42012-07-12 14:46:37 -07001562 list_add(&worker->entry, &pool->idle_list);
Tejun Heodb7bccf2010-06-29 10:07:12 +02001563
Tejun Heo628c78e2012-07-17 12:39:27 -07001564 if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
1565 mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
Tejun Heocb444762010-07-02 10:03:50 +02001566
Tejun Heo544ecf32012-05-14 15:04:50 -07001567 /*
Tejun Heo706026c2013-01-24 11:01:34 -08001568 * Sanity check nr_running. Because wq_unbind_fn() releases
Tejun Heod565ed62013-01-24 11:01:33 -08001569 * pool->lock between setting %WORKER_UNBOUND and zapping
Tejun Heo628c78e2012-07-17 12:39:27 -07001570 * nr_running, the warning may trigger spuriously. Check iff
1571 * unbind is not in progress.
Tejun Heo544ecf32012-05-14 15:04:50 -07001572 */
Tejun Heo24647572013-01-24 11:01:33 -08001573 WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
Tejun Heobd7bdd42012-07-12 14:46:37 -07001574 pool->nr_workers == pool->nr_idle &&
Tejun Heoe19e3972013-01-24 11:39:44 -08001575 atomic_read(&pool->nr_running));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001576}
1577
Tejun Heoc8e55f32010-06-29 10:07:12 +02001578/**
1579 * worker_leave_idle - leave idle state
1580 * @worker: worker which is leaving idle state
1581 *
1582 * @worker is leaving idle state. Update stats.
1583 *
1584 * LOCKING:
Tejun Heod565ed62013-01-24 11:01:33 -08001585 * spin_lock_irq(pool->lock).
Tejun Heoc8e55f32010-06-29 10:07:12 +02001586 */
1587static void worker_leave_idle(struct worker *worker)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588{
Tejun Heobd7bdd42012-07-12 14:46:37 -07001589 struct worker_pool *pool = worker->pool;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590
Tejun Heo6183c002013-03-12 11:29:57 -07001591 if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
1592 return;
Tejun Heod302f012010-06-29 10:07:13 +02001593 worker_clr_flags(worker, WORKER_IDLE);
Tejun Heobd7bdd42012-07-12 14:46:37 -07001594 pool->nr_idle--;
Tejun Heoc8e55f32010-06-29 10:07:12 +02001595 list_del_init(&worker->entry);
1596}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597
Tejun Heoc34056a2010-06-29 10:07:11 +02001598static struct worker *alloc_worker(void)
1599{
1600 struct worker *worker;
1601
1602 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
Tejun Heoc8e55f32010-06-29 10:07:12 +02001603 if (worker) {
1604 INIT_LIST_HEAD(&worker->entry);
Tejun Heoaffee4b2010-06-29 10:07:12 +02001605 INIT_LIST_HEAD(&worker->scheduled);
Lai Jiangshanda028462014-05-20 17:46:31 +08001606 INIT_LIST_HEAD(&worker->node);
Tejun Heoe22bee72010-06-29 10:07:14 +02001607 /* on creation a worker is in !idle && prep state */
1608 worker->flags = WORKER_PREP;
Tejun Heoc8e55f32010-06-29 10:07:12 +02001609 }
Tejun Heoc34056a2010-06-29 10:07:11 +02001610 return worker;
1611}
1612
1613/**
Lai Jiangshan4736cbf2014-05-20 17:46:35 +08001614 * worker_attach_to_pool() - attach a worker to a pool
1615 * @worker: worker to be attached
1616 * @pool: the target pool
1617 *
1618 * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
1619 * cpu-binding of @worker are kept coordinated with the pool across
1620 * cpu-[un]hotplugs.
1621 */
1622static void worker_attach_to_pool(struct worker *worker,
1623 struct worker_pool *pool)
1624{
1625 mutex_lock(&pool->attach_mutex);
1626
1627 /*
1628 * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1629 * online CPUs. It'll be re-applied when any of the CPUs come up.
1630 */
1631 set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
1632
1633 /*
1634 * The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
1635 * stable across this function. See the comments above the
1636 * flag definition for details.
1637 */
1638 if (pool->flags & POOL_DISASSOCIATED)
1639 worker->flags |= WORKER_UNBOUND;
1640
1641 list_add_tail(&worker->node, &pool->workers);
1642
1643 mutex_unlock(&pool->attach_mutex);
1644}
1645
1646/**
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08001647 * worker_detach_from_pool() - detach a worker from its pool
1648 * @worker: worker which is attached to its pool
1649 * @pool: the pool @worker is attached to
1650 *
Lai Jiangshan4736cbf2014-05-20 17:46:35 +08001651 * Undo the attaching which had been done in worker_attach_to_pool(). The
1652 * caller worker shouldn't access to the pool after detached except it has
1653 * other reference to the pool.
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08001654 */
1655static void worker_detach_from_pool(struct worker *worker,
1656 struct worker_pool *pool)
1657{
1658 struct completion *detach_completion = NULL;
1659
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08001660 mutex_lock(&pool->attach_mutex);
Lai Jiangshanda028462014-05-20 17:46:31 +08001661 list_del(&worker->node);
1662 if (list_empty(&pool->workers))
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08001663 detach_completion = pool->detach_completion;
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08001664 mutex_unlock(&pool->attach_mutex);
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08001665
1666 if (detach_completion)
1667 complete(detach_completion);
1668}
1669
1670/**
Tejun Heoc34056a2010-06-29 10:07:11 +02001671 * create_worker - create a new workqueue worker
Tejun Heo63d95a92012-07-12 14:46:37 -07001672 * @pool: pool the new worker will belong to
Tejun Heoc34056a2010-06-29 10:07:11 +02001673 *
Lai Jiangshan73eb7fe2014-05-20 17:46:28 +08001674 * Create a new worker which is attached to @pool. The new worker must be
1675 * started by start_worker().
Tejun Heoc34056a2010-06-29 10:07:11 +02001676 *
1677 * CONTEXT:
1678 * Might sleep. Does GFP_KERNEL allocations.
1679 *
Yacine Belkadid185af32013-07-31 14:59:24 -07001680 * Return:
Tejun Heoc34056a2010-06-29 10:07:11 +02001681 * Pointer to the newly created worker.
1682 */
Tejun Heobc2ae0f2012-07-17 12:39:27 -07001683static struct worker *create_worker(struct worker_pool *pool)
Tejun Heoc34056a2010-06-29 10:07:11 +02001684{
Tejun Heoc34056a2010-06-29 10:07:11 +02001685 struct worker *worker = NULL;
Tejun Heof3421792010-07-02 10:03:51 +02001686 int id = -1;
Tejun Heoe3c916a2013-04-01 11:23:32 -07001687 char id_buf[16];
Tejun Heoc34056a2010-06-29 10:07:11 +02001688
Lai Jiangshan7cda9aa2014-05-20 17:46:32 +08001689 /* ID is needed to determine kthread name */
1690 id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);
Tejun Heo822d8402013-03-19 13:45:21 -07001691 if (id < 0)
1692 goto fail;
Tejun Heoc34056a2010-06-29 10:07:11 +02001693
1694 worker = alloc_worker();
1695 if (!worker)
1696 goto fail;
1697
Tejun Heobd7bdd42012-07-12 14:46:37 -07001698 worker->pool = pool;
Tejun Heoc34056a2010-06-29 10:07:11 +02001699 worker->id = id;
1700
Tejun Heo29c91e92013-03-12 11:30:03 -07001701 if (pool->cpu >= 0)
Tejun Heoe3c916a2013-04-01 11:23:32 -07001702 snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
1703 pool->attrs->nice < 0 ? "H" : "");
Tejun Heof3421792010-07-02 10:03:51 +02001704 else
Tejun Heoe3c916a2013-04-01 11:23:32 -07001705 snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
1706
Tejun Heof3f90ad2013-04-01 11:23:34 -07001707 worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
Tejun Heoe3c916a2013-04-01 11:23:32 -07001708 "kworker/%s", id_buf);
Tejun Heoc34056a2010-06-29 10:07:11 +02001709 if (IS_ERR(worker->task))
1710 goto fail;
1711
Oleg Nesterov91151222013-11-14 12:56:18 +01001712 set_user_nice(worker->task, pool->attrs->nice);
1713
1714 /* prevent userland from meddling with cpumask of workqueue workers */
1715 worker->task->flags |= PF_NO_SETAFFINITY;
1716
Lai Jiangshanda028462014-05-20 17:46:31 +08001717 /* successful, attach the worker to the pool */
Lai Jiangshan4736cbf2014-05-20 17:46:35 +08001718 worker_attach_to_pool(worker, pool);
Tejun Heo822d8402013-03-19 13:45:21 -07001719
Tejun Heoc34056a2010-06-29 10:07:11 +02001720 return worker;
Tejun Heo822d8402013-03-19 13:45:21 -07001721
Tejun Heoc34056a2010-06-29 10:07:11 +02001722fail:
Lai Jiangshan9625ab12014-05-20 17:46:27 +08001723 if (id >= 0)
Lai Jiangshan7cda9aa2014-05-20 17:46:32 +08001724 ida_simple_remove(&pool->worker_ida, id);
Tejun Heoc34056a2010-06-29 10:07:11 +02001725 kfree(worker);
1726 return NULL;
1727}
1728
1729/**
1730 * start_worker - start a newly created worker
1731 * @worker: worker to start
1732 *
Tejun Heo706026c2013-01-24 11:01:34 -08001733 * Make the pool aware of @worker and start it.
Tejun Heoc34056a2010-06-29 10:07:11 +02001734 *
1735 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -08001736 * spin_lock_irq(pool->lock).
Tejun Heoc34056a2010-06-29 10:07:11 +02001737 */
1738static void start_worker(struct worker *worker)
1739{
Tejun Heobd7bdd42012-07-12 14:46:37 -07001740 worker->pool->nr_workers++;
Tejun Heoc8e55f32010-06-29 10:07:12 +02001741 worker_enter_idle(worker);
Tejun Heoc34056a2010-06-29 10:07:11 +02001742 wake_up_process(worker->task);
1743}
1744
1745/**
Tejun Heoebf44d12013-03-13 19:47:39 -07001746 * create_and_start_worker - create and start a worker for a pool
1747 * @pool: the target pool
1748 *
Tejun Heocd549682013-03-13 19:47:39 -07001749 * Grab the managership of @pool and create and start a new worker for it.
Yacine Belkadid185af32013-07-31 14:59:24 -07001750 *
1751 * Return: 0 on success. A negative error code otherwise.
Tejun Heoebf44d12013-03-13 19:47:39 -07001752 */
1753static int create_and_start_worker(struct worker_pool *pool)
1754{
1755 struct worker *worker;
1756
1757 worker = create_worker(pool);
1758 if (worker) {
1759 spin_lock_irq(&pool->lock);
1760 start_worker(worker);
1761 spin_unlock_irq(&pool->lock);
1762 }
1763
1764 return worker ? 0 : -ENOMEM;
1765}
1766
1767/**
Tejun Heoc34056a2010-06-29 10:07:11 +02001768 * destroy_worker - destroy a workqueue worker
1769 * @worker: worker to be destroyed
1770 *
Lai Jiangshan73eb7fe2014-05-20 17:46:28 +08001771 * Destroy @worker and adjust @pool stats accordingly. The worker should
1772 * be idle.
Tejun Heoc8e55f32010-06-29 10:07:12 +02001773 *
1774 * CONTEXT:
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08001775 * spin_lock_irq(pool->lock).
Tejun Heoc34056a2010-06-29 10:07:11 +02001776 */
1777static void destroy_worker(struct worker *worker)
1778{
Tejun Heobd7bdd42012-07-12 14:46:37 -07001779 struct worker_pool *pool = worker->pool;
Tejun Heoc34056a2010-06-29 10:07:11 +02001780
Tejun Heocd549682013-03-13 19:47:39 -07001781 lockdep_assert_held(&pool->lock);
1782
Tejun Heoc34056a2010-06-29 10:07:11 +02001783 /* sanity check frenzy */
Tejun Heo6183c002013-03-12 11:29:57 -07001784 if (WARN_ON(worker->current_work) ||
Lai Jiangshan73eb7fe2014-05-20 17:46:28 +08001785 WARN_ON(!list_empty(&worker->scheduled)) ||
1786 WARN_ON(!(worker->flags & WORKER_IDLE)))
Tejun Heo6183c002013-03-12 11:29:57 -07001787 return;
Tejun Heoc34056a2010-06-29 10:07:11 +02001788
Lai Jiangshan73eb7fe2014-05-20 17:46:28 +08001789 pool->nr_workers--;
1790 pool->nr_idle--;
Lai Jiangshan5bdfff92014-02-15 22:02:28 +08001791
Tejun Heoc8e55f32010-06-29 10:07:12 +02001792 list_del_init(&worker->entry);
Tejun Heocb444762010-07-02 10:03:50 +02001793 worker->flags |= WORKER_DIE;
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08001794 wake_up_process(worker->task);
Tejun Heoc34056a2010-06-29 10:07:11 +02001795}
1796
Tejun Heo63d95a92012-07-12 14:46:37 -07001797static void idle_worker_timeout(unsigned long __pool)
Tejun Heoe22bee72010-06-29 10:07:14 +02001798{
Tejun Heo63d95a92012-07-12 14:46:37 -07001799 struct worker_pool *pool = (void *)__pool;
Tejun Heoe22bee72010-06-29 10:07:14 +02001800
Tejun Heod565ed62013-01-24 11:01:33 -08001801 spin_lock_irq(&pool->lock);
Tejun Heoe22bee72010-06-29 10:07:14 +02001802
Lai Jiangshan3347fc92014-05-20 17:46:30 +08001803 while (too_many_workers(pool)) {
Tejun Heoe22bee72010-06-29 10:07:14 +02001804 struct worker *worker;
1805 unsigned long expires;
1806
1807 /* idle_list is kept in LIFO order, check the last one */
Tejun Heo63d95a92012-07-12 14:46:37 -07001808 worker = list_entry(pool->idle_list.prev, struct worker, entry);
Tejun Heoe22bee72010-06-29 10:07:14 +02001809 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1810
Lai Jiangshan3347fc92014-05-20 17:46:30 +08001811 if (time_before(jiffies, expires)) {
Tejun Heo63d95a92012-07-12 14:46:37 -07001812 mod_timer(&pool->idle_timer, expires);
Lai Jiangshan3347fc92014-05-20 17:46:30 +08001813 break;
Tejun Heoe22bee72010-06-29 10:07:14 +02001814 }
Lai Jiangshan3347fc92014-05-20 17:46:30 +08001815
1816 destroy_worker(worker);
Tejun Heoe22bee72010-06-29 10:07:14 +02001817 }
1818
Tejun Heod565ed62013-01-24 11:01:33 -08001819 spin_unlock_irq(&pool->lock);
Tejun Heoe22bee72010-06-29 10:07:14 +02001820}
1821
Tejun Heo493a1722013-03-12 11:29:59 -07001822static void send_mayday(struct work_struct *work)
Tejun Heoe22bee72010-06-29 10:07:14 +02001823{
Tejun Heo112202d2013-02-13 19:29:12 -08001824 struct pool_workqueue *pwq = get_work_pwq(work);
1825 struct workqueue_struct *wq = pwq->wq;
Tejun Heo493a1722013-03-12 11:29:59 -07001826
Tejun Heo2e109a22013-03-13 19:47:40 -07001827 lockdep_assert_held(&wq_mayday_lock);
Tejun Heoe22bee72010-06-29 10:07:14 +02001828
Tejun Heo493008a2013-03-12 11:30:03 -07001829 if (!wq->rescuer)
Tejun Heo493a1722013-03-12 11:29:59 -07001830 return;
Tejun Heoe22bee72010-06-29 10:07:14 +02001831
1832 /* mayday mayday mayday */
Tejun Heo493a1722013-03-12 11:29:59 -07001833 if (list_empty(&pwq->mayday_node)) {
Lai Jiangshan77668c82014-04-18 11:04:16 -04001834 /*
1835 * If @pwq is for an unbound wq, its base ref may be put at
1836 * any time due to an attribute change. Pin @pwq until the
1837 * rescuer is done with it.
1838 */
1839 get_pwq(pwq);
Tejun Heo493a1722013-03-12 11:29:59 -07001840 list_add_tail(&pwq->mayday_node, &wq->maydays);
Tejun Heoe22bee72010-06-29 10:07:14 +02001841 wake_up_process(wq->rescuer->task);
Tejun Heo493a1722013-03-12 11:29:59 -07001842 }
Tejun Heoe22bee72010-06-29 10:07:14 +02001843}
1844
Tejun Heo706026c2013-01-24 11:01:34 -08001845static void pool_mayday_timeout(unsigned long __pool)
Tejun Heoe22bee72010-06-29 10:07:14 +02001846{
Tejun Heo63d95a92012-07-12 14:46:37 -07001847 struct worker_pool *pool = (void *)__pool;
Tejun Heoe22bee72010-06-29 10:07:14 +02001848 struct work_struct *work;
1849
Tejun Heo2e109a22013-03-13 19:47:40 -07001850 spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */
Tejun Heo493a1722013-03-12 11:29:59 -07001851 spin_lock(&pool->lock);
Tejun Heoe22bee72010-06-29 10:07:14 +02001852
Tejun Heo63d95a92012-07-12 14:46:37 -07001853 if (need_to_create_worker(pool)) {
Tejun Heoe22bee72010-06-29 10:07:14 +02001854 /*
1855 * We've been trying to create a new worker but
1856 * haven't been successful. We might be hitting an
1857 * allocation deadlock. Send distress signals to
1858 * rescuers.
1859 */
Tejun Heo63d95a92012-07-12 14:46:37 -07001860 list_for_each_entry(work, &pool->worklist, entry)
Tejun Heoe22bee72010-06-29 10:07:14 +02001861 send_mayday(work);
1862 }
1863
Tejun Heo493a1722013-03-12 11:29:59 -07001864 spin_unlock(&pool->lock);
Tejun Heo2e109a22013-03-13 19:47:40 -07001865 spin_unlock_irq(&wq_mayday_lock);
Tejun Heoe22bee72010-06-29 10:07:14 +02001866
Tejun Heo63d95a92012-07-12 14:46:37 -07001867 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
Tejun Heoe22bee72010-06-29 10:07:14 +02001868}
1869
1870/**
1871 * maybe_create_worker - create a new worker if necessary
Tejun Heo63d95a92012-07-12 14:46:37 -07001872 * @pool: pool to create a new worker for
Tejun Heoe22bee72010-06-29 10:07:14 +02001873 *
Tejun Heo63d95a92012-07-12 14:46:37 -07001874 * Create a new worker for @pool if necessary. @pool is guaranteed to
Tejun Heoe22bee72010-06-29 10:07:14 +02001875 * have at least one idle worker on return from this function. If
1876 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
Tejun Heo63d95a92012-07-12 14:46:37 -07001877 * sent to all rescuers with works scheduled on @pool to resolve
Tejun Heoe22bee72010-06-29 10:07:14 +02001878 * possible allocation deadlock.
1879 *
Tejun Heoc5aa87b2013-03-13 16:51:36 -07001880 * On return, need_to_create_worker() is guaranteed to be %false and
1881 * may_start_working() %true.
Tejun Heoe22bee72010-06-29 10:07:14 +02001882 *
1883 * LOCKING:
Tejun Heod565ed62013-01-24 11:01:33 -08001884 * spin_lock_irq(pool->lock) which may be released and regrabbed
Tejun Heoe22bee72010-06-29 10:07:14 +02001885 * multiple times. Does GFP_KERNEL allocations. Called only from
1886 * manager.
1887 *
Yacine Belkadid185af32013-07-31 14:59:24 -07001888 * Return:
Tejun Heoc5aa87b2013-03-13 16:51:36 -07001889 * %false if no action was taken and pool->lock stayed locked, %true
Tejun Heoe22bee72010-06-29 10:07:14 +02001890 * otherwise.
1891 */
Tejun Heo63d95a92012-07-12 14:46:37 -07001892static bool maybe_create_worker(struct worker_pool *pool)
Tejun Heod565ed62013-01-24 11:01:33 -08001893__releases(&pool->lock)
1894__acquires(&pool->lock)
Tejun Heoe22bee72010-06-29 10:07:14 +02001895{
Tejun Heo63d95a92012-07-12 14:46:37 -07001896 if (!need_to_create_worker(pool))
Tejun Heoe22bee72010-06-29 10:07:14 +02001897 return false;
1898restart:
Tejun Heod565ed62013-01-24 11:01:33 -08001899 spin_unlock_irq(&pool->lock);
Tejun Heo9f9c2362010-07-14 11:31:20 +02001900
Tejun Heoe22bee72010-06-29 10:07:14 +02001901 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
Tejun Heo63d95a92012-07-12 14:46:37 -07001902 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
Tejun Heoe22bee72010-06-29 10:07:14 +02001903
1904 while (true) {
1905 struct worker *worker;
1906
Tejun Heobc2ae0f2012-07-17 12:39:27 -07001907 worker = create_worker(pool);
Tejun Heoe22bee72010-06-29 10:07:14 +02001908 if (worker) {
Tejun Heo63d95a92012-07-12 14:46:37 -07001909 del_timer_sync(&pool->mayday_timer);
Tejun Heod565ed62013-01-24 11:01:33 -08001910 spin_lock_irq(&pool->lock);
Tejun Heoe22bee72010-06-29 10:07:14 +02001911 start_worker(worker);
Tejun Heo6183c002013-03-12 11:29:57 -07001912 if (WARN_ON_ONCE(need_to_create_worker(pool)))
1913 goto restart;
Tejun Heoe22bee72010-06-29 10:07:14 +02001914 return true;
1915 }
1916
Tejun Heo63d95a92012-07-12 14:46:37 -07001917 if (!need_to_create_worker(pool))
Tejun Heoe22bee72010-06-29 10:07:14 +02001918 break;
1919
Tejun Heoe22bee72010-06-29 10:07:14 +02001920 __set_current_state(TASK_INTERRUPTIBLE);
1921 schedule_timeout(CREATE_COOLDOWN);
Tejun Heo9f9c2362010-07-14 11:31:20 +02001922
Tejun Heo63d95a92012-07-12 14:46:37 -07001923 if (!need_to_create_worker(pool))
Tejun Heoe22bee72010-06-29 10:07:14 +02001924 break;
1925 }
1926
Tejun Heo63d95a92012-07-12 14:46:37 -07001927 del_timer_sync(&pool->mayday_timer);
Tejun Heod565ed62013-01-24 11:01:33 -08001928 spin_lock_irq(&pool->lock);
Tejun Heo63d95a92012-07-12 14:46:37 -07001929 if (need_to_create_worker(pool))
Tejun Heoe22bee72010-06-29 10:07:14 +02001930 goto restart;
1931 return true;
1932}
1933
1934/**
Tejun Heoe22bee72010-06-29 10:07:14 +02001935 * manage_workers - manage worker pool
1936 * @worker: self
1937 *
Tejun Heo706026c2013-01-24 11:01:34 -08001938 * Assume the manager role and manage the worker pool @worker belongs
Tejun Heoe22bee72010-06-29 10:07:14 +02001939 * to. At any given time, there can be only zero or one manager per
Tejun Heo706026c2013-01-24 11:01:34 -08001940 * pool. The exclusion is handled automatically by this function.
Tejun Heoe22bee72010-06-29 10:07:14 +02001941 *
1942 * The caller can safely start processing works on false return. On
1943 * true return, it's guaranteed that need_to_create_worker() is false
1944 * and may_start_working() is true.
1945 *
1946 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -08001947 * spin_lock_irq(pool->lock) which may be released and regrabbed
Tejun Heoe22bee72010-06-29 10:07:14 +02001948 * multiple times. Does GFP_KERNEL allocations.
1949 *
Yacine Belkadid185af32013-07-31 14:59:24 -07001950 * Return:
Libin2d498db2013-08-21 08:50:40 +08001951 * %false if the pool don't need management and the caller can safely start
1952 * processing works, %true indicates that the function released pool->lock
1953 * and reacquired it to perform some management function and that the
1954 * conditions that the caller verified while holding the lock before
1955 * calling the function might no longer be true.
Tejun Heoe22bee72010-06-29 10:07:14 +02001956 */
1957static bool manage_workers(struct worker *worker)
1958{
Tejun Heo63d95a92012-07-12 14:46:37 -07001959 struct worker_pool *pool = worker->pool;
Tejun Heoe22bee72010-06-29 10:07:14 +02001960 bool ret = false;
1961
Tejun Heobc3a1af2013-03-13 19:47:39 -07001962 /*
Tejun Heobc3a1af2013-03-13 19:47:39 -07001963 * Anyone who successfully grabs manager_arb wins the arbitration
1964 * and becomes the manager. mutex_trylock() on pool->manager_arb
1965 * failure while holding pool->lock reliably indicates that someone
1966 * else is managing the pool and the worker which failed trylock
1967 * can proceed to executing work items. This means that anyone
1968 * grabbing manager_arb is responsible for actually performing
1969 * manager duties. If manager_arb is grabbed and released without
1970 * actual management, the pool may stall indefinitely.
Tejun Heobc3a1af2013-03-13 19:47:39 -07001971 */
Tejun Heo34a06bd2013-03-12 11:30:00 -07001972 if (!mutex_trylock(&pool->manager_arb))
Tejun Heoe22bee72010-06-29 10:07:14 +02001973 return ret;
1974
Tejun Heo63d95a92012-07-12 14:46:37 -07001975 ret |= maybe_create_worker(pool);
Tejun Heoe22bee72010-06-29 10:07:14 +02001976
Tejun Heo34a06bd2013-03-12 11:30:00 -07001977 mutex_unlock(&pool->manager_arb);
Tejun Heoe22bee72010-06-29 10:07:14 +02001978 return ret;
1979}
1980
Tejun Heoa62428c2010-06-29 10:07:10 +02001981/**
1982 * process_one_work - process single work
Tejun Heoc34056a2010-06-29 10:07:11 +02001983 * @worker: self
Tejun Heoa62428c2010-06-29 10:07:10 +02001984 * @work: work to process
1985 *
1986 * Process @work. This function contains all the logics necessary to
1987 * process a single work including synchronization against and
1988 * interaction with other workers on the same cpu, queueing and
1989 * flushing. As long as context requirement is met, any worker can
1990 * call this function to process a work.
1991 *
1992 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -08001993 * spin_lock_irq(pool->lock) which is released and regrabbed.
Tejun Heoa62428c2010-06-29 10:07:10 +02001994 */
Tejun Heoc34056a2010-06-29 10:07:11 +02001995static void process_one_work(struct worker *worker, struct work_struct *work)
Tejun Heod565ed62013-01-24 11:01:33 -08001996__releases(&pool->lock)
1997__acquires(&pool->lock)
Tejun Heoa62428c2010-06-29 10:07:10 +02001998{
Tejun Heo112202d2013-02-13 19:29:12 -08001999 struct pool_workqueue *pwq = get_work_pwq(work);
Tejun Heobd7bdd42012-07-12 14:46:37 -07002000 struct worker_pool *pool = worker->pool;
Tejun Heo112202d2013-02-13 19:29:12 -08002001 bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
Tejun Heo73f53c42010-06-29 10:07:11 +02002002 int work_color;
Tejun Heo7e116292010-06-29 10:07:13 +02002003 struct worker *collision;
Tejun Heoa62428c2010-06-29 10:07:10 +02002004#ifdef CONFIG_LOCKDEP
2005 /*
2006 * It is permissible to free the struct work_struct from
2007 * inside the function that is called from it, this we need to
2008 * take into account for lockdep too. To avoid bogus "held
2009 * lock freed" warnings as well as problems when looking into
2010 * work->lockdep_map, make a copy and use that here.
2011 */
Peter Zijlstra4d82a1d2012-05-15 08:06:19 -07002012 struct lockdep_map lockdep_map;
2013
2014 lockdep_copy_map(&lockdep_map, &work->lockdep_map);
Tejun Heoa62428c2010-06-29 10:07:10 +02002015#endif
Tejun Heo6fec10a2012-07-22 10:16:34 -07002016 /*
2017 * Ensure we're on the correct CPU. DISASSOCIATED test is
2018 * necessary to avoid spurious warnings from rescuers servicing the
Tejun Heo24647572013-01-24 11:01:33 -08002019 * unbound or a disassociated pool.
Tejun Heo6fec10a2012-07-22 10:16:34 -07002020 */
Lai Jiangshan5f7dabf2012-09-18 09:59:23 -07002021 WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) &&
Tejun Heo24647572013-01-24 11:01:33 -08002022 !(pool->flags & POOL_DISASSOCIATED) &&
Tejun Heoec22ca52013-01-24 11:01:33 -08002023 raw_smp_processor_id() != pool->cpu);
Tejun Heo25511a42012-07-17 12:39:27 -07002024
Tejun Heo7e116292010-06-29 10:07:13 +02002025 /*
2026 * A single work shouldn't be executed concurrently by
2027 * multiple workers on a single cpu. Check whether anyone is
2028 * already processing the work. If so, defer the work to the
2029 * currently executing one.
2030 */
Tejun Heoc9e7cf22013-01-24 11:01:33 -08002031 collision = find_worker_executing_work(pool, work);
Tejun Heo7e116292010-06-29 10:07:13 +02002032 if (unlikely(collision)) {
2033 move_linked_works(work, &collision->scheduled, NULL);
2034 return;
2035 }
2036
Tejun Heo8930cab2012-08-03 10:30:45 -07002037 /* claim and dequeue */
Tejun Heoa62428c2010-06-29 10:07:10 +02002038 debug_work_deactivate(work);
Tejun Heoc9e7cf22013-01-24 11:01:33 -08002039 hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
Tejun Heoc34056a2010-06-29 10:07:11 +02002040 worker->current_work = work;
Tejun Heoa2c1c572012-12-18 10:35:02 -08002041 worker->current_func = work->func;
Tejun Heo112202d2013-02-13 19:29:12 -08002042 worker->current_pwq = pwq;
Tejun Heo73f53c42010-06-29 10:07:11 +02002043 work_color = get_work_color(work);
Tejun Heo7a22ad72010-06-29 10:07:13 +02002044
Tejun Heoa62428c2010-06-29 10:07:10 +02002045 list_del_init(&work->entry);
2046
Tejun Heo649027d2010-06-29 10:07:14 +02002047 /*
Tejun Heofb0e7be2010-06-29 10:07:15 +02002048 * CPU intensive works don't participate in concurrency
2049 * management. They're the scheduler's responsibility.
2050 */
2051 if (unlikely(cpu_intensive))
2052 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
2053
Tejun Heo974271c2012-07-12 14:46:37 -07002054 /*
Tejun Heod565ed62013-01-24 11:01:33 -08002055 * Unbound pool isn't concurrency managed and work items should be
Tejun Heo974271c2012-07-12 14:46:37 -07002056 * executed ASAP. Wake up another worker if necessary.
2057 */
Tejun Heo63d95a92012-07-12 14:46:37 -07002058 if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
2059 wake_up_worker(pool);
Tejun Heo974271c2012-07-12 14:46:37 -07002060
Tejun Heo8930cab2012-08-03 10:30:45 -07002061 /*
Tejun Heo7c3eed52013-01-24 11:01:33 -08002062 * Record the last pool and clear PENDING which should be the last
Tejun Heod565ed62013-01-24 11:01:33 -08002063 * update to @work. Also, do this inside @pool->lock so that
Tejun Heo23657bb2012-08-13 17:08:19 -07002064 * PENDING and queued state changes happen together while IRQ is
2065 * disabled.
Tejun Heo8930cab2012-08-03 10:30:45 -07002066 */
Tejun Heo7c3eed52013-01-24 11:01:33 -08002067 set_work_pool_and_clear_pending(work, pool->id);
Tejun Heoa62428c2010-06-29 10:07:10 +02002068
Tejun Heod565ed62013-01-24 11:01:33 -08002069 spin_unlock_irq(&pool->lock);
Tejun Heoa62428c2010-06-29 10:07:10 +02002070
Tejun Heo112202d2013-02-13 19:29:12 -08002071 lock_map_acquire_read(&pwq->wq->lockdep_map);
Tejun Heoa62428c2010-06-29 10:07:10 +02002072 lock_map_acquire(&lockdep_map);
Arjan van de Vene36c8862010-08-21 13:07:26 -07002073 trace_workqueue_execute_start(work);
Tejun Heoa2c1c572012-12-18 10:35:02 -08002074 worker->current_func(work);
Arjan van de Vene36c8862010-08-21 13:07:26 -07002075 /*
2076 * While we must be careful to not use "work" after this, the trace
2077 * point will only record its address.
2078 */
2079 trace_workqueue_execute_end(work);
Tejun Heoa62428c2010-06-29 10:07:10 +02002080 lock_map_release(&lockdep_map);
Tejun Heo112202d2013-02-13 19:29:12 -08002081 lock_map_release(&pwq->wq->lockdep_map);
Tejun Heoa62428c2010-06-29 10:07:10 +02002082
2083 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
Valentin Ilie044c7822012-08-19 00:52:42 +03002084 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2085 " last function: %pf\n",
Tejun Heoa2c1c572012-12-18 10:35:02 -08002086 current->comm, preempt_count(), task_pid_nr(current),
2087 worker->current_func);
Tejun Heoa62428c2010-06-29 10:07:10 +02002088 debug_show_held_locks(current);
2089 dump_stack();
2090 }
2091
Tejun Heob22ce272013-08-28 17:33:37 -04002092 /*
2093 * The following prevents a kworker from hogging CPU on !PREEMPT
2094 * kernels, where a requeueing work item waiting for something to
2095 * happen could deadlock with stop_machine as such work item could
2096 * indefinitely requeue itself while all other CPUs are trapped in
2097 * stop_machine.
2098 */
2099 cond_resched();
2100
Tejun Heod565ed62013-01-24 11:01:33 -08002101 spin_lock_irq(&pool->lock);
Tejun Heoa62428c2010-06-29 10:07:10 +02002102
Tejun Heofb0e7be2010-06-29 10:07:15 +02002103 /* clear cpu intensive status */
2104 if (unlikely(cpu_intensive))
2105 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
2106
Tejun Heoa62428c2010-06-29 10:07:10 +02002107 /* we're done with it, release */
Sasha Levin42f85702012-12-17 10:01:23 -05002108 hash_del(&worker->hentry);
Tejun Heoc34056a2010-06-29 10:07:11 +02002109 worker->current_work = NULL;
Tejun Heoa2c1c572012-12-18 10:35:02 -08002110 worker->current_func = NULL;
Tejun Heo112202d2013-02-13 19:29:12 -08002111 worker->current_pwq = NULL;
Tejun Heo3d1cb202013-04-30 15:27:22 -07002112 worker->desc_valid = false;
Tejun Heo112202d2013-02-13 19:29:12 -08002113 pwq_dec_nr_in_flight(pwq, work_color);
Tejun Heoa62428c2010-06-29 10:07:10 +02002114}
2115
Tejun Heoaffee4b2010-06-29 10:07:12 +02002116/**
2117 * process_scheduled_works - process scheduled works
2118 * @worker: self
2119 *
2120 * Process all scheduled works. Please note that the scheduled list
2121 * may change while processing a work, so this function repeatedly
2122 * fetches a work from the top and executes it.
2123 *
2124 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -08002125 * spin_lock_irq(pool->lock) which may be released and regrabbed
Tejun Heoaffee4b2010-06-29 10:07:12 +02002126 * multiple times.
2127 */
2128static void process_scheduled_works(struct worker *worker)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129{
Tejun Heoaffee4b2010-06-29 10:07:12 +02002130 while (!list_empty(&worker->scheduled)) {
2131 struct work_struct *work = list_first_entry(&worker->scheduled,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132 struct work_struct, entry);
Tejun Heoc34056a2010-06-29 10:07:11 +02002133 process_one_work(worker, work);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002134 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002135}
2136
Tejun Heo4690c4a2010-06-29 10:07:10 +02002137/**
2138 * worker_thread - the worker thread function
Tejun Heoc34056a2010-06-29 10:07:11 +02002139 * @__worker: self
Tejun Heo4690c4a2010-06-29 10:07:10 +02002140 *
Tejun Heoc5aa87b2013-03-13 16:51:36 -07002141 * The worker thread function. All workers belong to a worker_pool -
2142 * either a per-cpu one or dynamic unbound one. These workers process all
2143 * work items regardless of their specific target workqueue. The only
2144 * exception is work items which belong to workqueues with a rescuer which
2145 * will be explained in rescuer_thread().
Yacine Belkadid185af32013-07-31 14:59:24 -07002146 *
2147 * Return: 0
Tejun Heo4690c4a2010-06-29 10:07:10 +02002148 */
Tejun Heoc34056a2010-06-29 10:07:11 +02002149static int worker_thread(void *__worker)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150{
Tejun Heoc34056a2010-06-29 10:07:11 +02002151 struct worker *worker = __worker;
Tejun Heobd7bdd42012-07-12 14:46:37 -07002152 struct worker_pool *pool = worker->pool;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153
Tejun Heoe22bee72010-06-29 10:07:14 +02002154 /* tell the scheduler that this is a workqueue worker */
2155 worker->task->flags |= PF_WQ_WORKER;
Tejun Heoc8e55f32010-06-29 10:07:12 +02002156woke_up:
Tejun Heod565ed62013-01-24 11:01:33 -08002157 spin_lock_irq(&pool->lock);
Oleg Nesterov3af244332007-05-09 02:34:09 -07002158
Tejun Heoa9ab7752013-03-19 13:45:21 -07002159 /* am I supposed to die? */
2160 if (unlikely(worker->flags & WORKER_DIE)) {
Tejun Heod565ed62013-01-24 11:01:33 -08002161 spin_unlock_irq(&pool->lock);
Tejun Heoa9ab7752013-03-19 13:45:21 -07002162 WARN_ON_ONCE(!list_empty(&worker->entry));
2163 worker->task->flags &= ~PF_WQ_WORKER;
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08002164
2165 set_task_comm(worker->task, "kworker/dying");
Lai Jiangshan7cda9aa2014-05-20 17:46:32 +08002166 ida_simple_remove(&pool->worker_ida, worker->id);
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08002167 worker_detach_from_pool(worker, pool);
2168 kfree(worker);
Tejun Heoa9ab7752013-03-19 13:45:21 -07002169 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170 }
Oleg Nesterov3af244332007-05-09 02:34:09 -07002171
Tejun Heoc8e55f32010-06-29 10:07:12 +02002172 worker_leave_idle(worker);
Tejun Heodb7bccf2010-06-29 10:07:12 +02002173recheck:
Tejun Heoe22bee72010-06-29 10:07:14 +02002174 /* no more worker necessary? */
Tejun Heo63d95a92012-07-12 14:46:37 -07002175 if (!need_more_worker(pool))
Tejun Heoe22bee72010-06-29 10:07:14 +02002176 goto sleep;
2177
2178 /* do we need to manage? */
Tejun Heo63d95a92012-07-12 14:46:37 -07002179 if (unlikely(!may_start_working(pool)) && manage_workers(worker))
Tejun Heoe22bee72010-06-29 10:07:14 +02002180 goto recheck;
2181
Tejun Heoc8e55f32010-06-29 10:07:12 +02002182 /*
2183 * ->scheduled list can only be filled while a worker is
2184 * preparing to process a work or actually processing it.
2185 * Make sure nobody diddled with it while I was sleeping.
2186 */
Tejun Heo6183c002013-03-12 11:29:57 -07002187 WARN_ON_ONCE(!list_empty(&worker->scheduled));
Tejun Heoc8e55f32010-06-29 10:07:12 +02002188
Tejun Heoe22bee72010-06-29 10:07:14 +02002189 /*
Tejun Heoa9ab7752013-03-19 13:45:21 -07002190 * Finish PREP stage. We're guaranteed to have at least one idle
2191 * worker or that someone else has already assumed the manager
2192 * role. This is where @worker starts participating in concurrency
2193 * management if applicable and concurrency management is restored
2194 * after being rebound. See rebind_workers() for details.
Tejun Heoe22bee72010-06-29 10:07:14 +02002195 */
Tejun Heoa9ab7752013-03-19 13:45:21 -07002196 worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND);
Tejun Heoe22bee72010-06-29 10:07:14 +02002197
2198 do {
Tejun Heoc8e55f32010-06-29 10:07:12 +02002199 struct work_struct *work =
Tejun Heobd7bdd42012-07-12 14:46:37 -07002200 list_first_entry(&pool->worklist,
Tejun Heoc8e55f32010-06-29 10:07:12 +02002201 struct work_struct, entry);
2202
2203 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
2204 /* optimization path, not strictly necessary */
2205 process_one_work(worker, work);
2206 if (unlikely(!list_empty(&worker->scheduled)))
2207 process_scheduled_works(worker);
2208 } else {
2209 move_linked_works(work, &worker->scheduled, NULL);
2210 process_scheduled_works(worker);
2211 }
Tejun Heo63d95a92012-07-12 14:46:37 -07002212 } while (keep_working(pool));
Tejun Heoc8e55f32010-06-29 10:07:12 +02002213
Tejun Heoe22bee72010-06-29 10:07:14 +02002214 worker_set_flags(worker, WORKER_PREP, false);
Tejun Heod313dd82010-07-02 10:03:51 +02002215sleep:
Tejun Heoc8e55f32010-06-29 10:07:12 +02002216 /*
Tejun Heod565ed62013-01-24 11:01:33 -08002217 * pool->lock is held and there's no work to process and no need to
2218 * manage, sleep. Workers are woken up only while holding
2219 * pool->lock or from local cpu, so setting the current state
2220 * before releasing pool->lock is enough to prevent losing any
2221 * event.
Tejun Heoc8e55f32010-06-29 10:07:12 +02002222 */
2223 worker_enter_idle(worker);
2224 __set_current_state(TASK_INTERRUPTIBLE);
Tejun Heod565ed62013-01-24 11:01:33 -08002225 spin_unlock_irq(&pool->lock);
Tejun Heoc8e55f32010-06-29 10:07:12 +02002226 schedule();
2227 goto woke_up;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002228}
2229
Tejun Heoe22bee72010-06-29 10:07:14 +02002230/**
2231 * rescuer_thread - the rescuer thread function
Tejun Heo111c2252013-01-17 17:16:24 -08002232 * @__rescuer: self
Tejun Heoe22bee72010-06-29 10:07:14 +02002233 *
2234 * Workqueue rescuer thread function. There's one rescuer for each
Tejun Heo493008a2013-03-12 11:30:03 -07002235 * workqueue which has WQ_MEM_RECLAIM set.
Tejun Heoe22bee72010-06-29 10:07:14 +02002236 *
Tejun Heo706026c2013-01-24 11:01:34 -08002237 * Regular work processing on a pool may block trying to create a new
Tejun Heoe22bee72010-06-29 10:07:14 +02002238 * worker which uses GFP_KERNEL allocation which has slight chance of
2239 * developing into deadlock if some works currently on the same queue
2240 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2241 * the problem rescuer solves.
2242 *
Tejun Heo706026c2013-01-24 11:01:34 -08002243 * When such condition is possible, the pool summons rescuers of all
2244 * workqueues which have works queued on the pool and let them process
Tejun Heoe22bee72010-06-29 10:07:14 +02002245 * those works so that forward progress can be guaranteed.
2246 *
2247 * This should happen rarely.
Yacine Belkadid185af32013-07-31 14:59:24 -07002248 *
2249 * Return: 0
Tejun Heoe22bee72010-06-29 10:07:14 +02002250 */
Tejun Heo111c2252013-01-17 17:16:24 -08002251static int rescuer_thread(void *__rescuer)
Tejun Heoe22bee72010-06-29 10:07:14 +02002252{
Tejun Heo111c2252013-01-17 17:16:24 -08002253 struct worker *rescuer = __rescuer;
2254 struct workqueue_struct *wq = rescuer->rescue_wq;
Tejun Heoe22bee72010-06-29 10:07:14 +02002255 struct list_head *scheduled = &rescuer->scheduled;
Lai Jiangshan4d595b82014-04-18 11:04:16 -04002256 bool should_stop;
Tejun Heoe22bee72010-06-29 10:07:14 +02002257
2258 set_user_nice(current, RESCUER_NICE_LEVEL);
Tejun Heo111c2252013-01-17 17:16:24 -08002259
2260 /*
2261 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2262 * doesn't participate in concurrency management.
2263 */
2264 rescuer->task->flags |= PF_WQ_WORKER;
Tejun Heoe22bee72010-06-29 10:07:14 +02002265repeat:
2266 set_current_state(TASK_INTERRUPTIBLE);
2267
Lai Jiangshan4d595b82014-04-18 11:04:16 -04002268 /*
2269 * By the time the rescuer is requested to stop, the workqueue
2270 * shouldn't have any work pending, but @wq->maydays may still have
2271 * pwq(s) queued. This can happen by non-rescuer workers consuming
2272 * all the work items before the rescuer got to them. Go through
2273 * @wq->maydays processing before acting on should_stop so that the
2274 * list is always empty on exit.
2275 */
2276 should_stop = kthread_should_stop();
Tejun Heoe22bee72010-06-29 10:07:14 +02002277
Tejun Heo493a1722013-03-12 11:29:59 -07002278 /* see whether any pwq is asking for help */
Tejun Heo2e109a22013-03-13 19:47:40 -07002279 spin_lock_irq(&wq_mayday_lock);
Tejun Heo493a1722013-03-12 11:29:59 -07002280
2281 while (!list_empty(&wq->maydays)) {
2282 struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
2283 struct pool_workqueue, mayday_node);
Tejun Heo112202d2013-02-13 19:29:12 -08002284 struct worker_pool *pool = pwq->pool;
Tejun Heoe22bee72010-06-29 10:07:14 +02002285 struct work_struct *work, *n;
2286
2287 __set_current_state(TASK_RUNNING);
Tejun Heo493a1722013-03-12 11:29:59 -07002288 list_del_init(&pwq->mayday_node);
2289
Tejun Heo2e109a22013-03-13 19:47:40 -07002290 spin_unlock_irq(&wq_mayday_lock);
Tejun Heoe22bee72010-06-29 10:07:14 +02002291
Lai Jiangshan51697d392014-05-20 17:46:36 +08002292 worker_attach_to_pool(rescuer, pool);
2293
2294 spin_lock_irq(&pool->lock);
Lai Jiangshanb3104102013-02-19 12:17:02 -08002295 rescuer->pool = pool;
Tejun Heoe22bee72010-06-29 10:07:14 +02002296
2297 /*
2298 * Slurp in all works issued via this workqueue and
2299 * process'em.
2300 */
Tejun Heo6183c002013-03-12 11:29:57 -07002301 WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
Tejun Heobd7bdd42012-07-12 14:46:37 -07002302 list_for_each_entry_safe(work, n, &pool->worklist, entry)
Tejun Heo112202d2013-02-13 19:29:12 -08002303 if (get_work_pwq(work) == pwq)
Tejun Heoe22bee72010-06-29 10:07:14 +02002304 move_linked_works(work, scheduled, &n);
2305
2306 process_scheduled_works(rescuer);
Lai Jiangshan51697d392014-05-20 17:46:36 +08002307 spin_unlock_irq(&pool->lock);
2308
2309 worker_detach_from_pool(rescuer, pool);
2310
2311 spin_lock_irq(&pool->lock);
Tejun Heo75769582011-02-14 14:04:46 +01002312
2313 /*
Lai Jiangshan77668c82014-04-18 11:04:16 -04002314 * Put the reference grabbed by send_mayday(). @pool won't
2315 * go away while we're holding its lock.
2316 */
2317 put_pwq(pwq);
2318
2319 /*
Tejun Heod565ed62013-01-24 11:01:33 -08002320 * Leave this pool. If keep_working() is %true, notify a
Tejun Heo75769582011-02-14 14:04:46 +01002321 * regular worker; otherwise, we end up with 0 concurrency
2322 * and stalling the execution.
2323 */
Tejun Heo63d95a92012-07-12 14:46:37 -07002324 if (keep_working(pool))
2325 wake_up_worker(pool);
Tejun Heo75769582011-02-14 14:04:46 +01002326
Lai Jiangshanb3104102013-02-19 12:17:02 -08002327 rescuer->pool = NULL;
Tejun Heo493a1722013-03-12 11:29:59 -07002328 spin_unlock(&pool->lock);
Tejun Heo2e109a22013-03-13 19:47:40 -07002329 spin_lock(&wq_mayday_lock);
Tejun Heoe22bee72010-06-29 10:07:14 +02002330 }
2331
Tejun Heo2e109a22013-03-13 19:47:40 -07002332 spin_unlock_irq(&wq_mayday_lock);
Tejun Heo493a1722013-03-12 11:29:59 -07002333
Lai Jiangshan4d595b82014-04-18 11:04:16 -04002334 if (should_stop) {
2335 __set_current_state(TASK_RUNNING);
2336 rescuer->task->flags &= ~PF_WQ_WORKER;
2337 return 0;
2338 }
2339
Tejun Heo111c2252013-01-17 17:16:24 -08002340 /* rescuers should never participate in concurrency management */
2341 WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
Tejun Heoe22bee72010-06-29 10:07:14 +02002342 schedule();
2343 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002344}
2345
Oleg Nesterovfc2e4d72007-05-09 02:33:51 -07002346struct wq_barrier {
2347 struct work_struct work;
2348 struct completion done;
2349};
2350
2351static void wq_barrier_func(struct work_struct *work)
2352{
2353 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
2354 complete(&barr->done);
2355}
2356
Tejun Heo4690c4a2010-06-29 10:07:10 +02002357/**
2358 * insert_wq_barrier - insert a barrier work
Tejun Heo112202d2013-02-13 19:29:12 -08002359 * @pwq: pwq to insert barrier into
Tejun Heo4690c4a2010-06-29 10:07:10 +02002360 * @barr: wq_barrier to insert
Tejun Heoaffee4b2010-06-29 10:07:12 +02002361 * @target: target work to attach @barr to
2362 * @worker: worker currently executing @target, NULL if @target is not executing
Tejun Heo4690c4a2010-06-29 10:07:10 +02002363 *
Tejun Heoaffee4b2010-06-29 10:07:12 +02002364 * @barr is linked to @target such that @barr is completed only after
2365 * @target finishes execution. Please note that the ordering
2366 * guarantee is observed only with respect to @target and on the local
2367 * cpu.
2368 *
2369 * Currently, a queued barrier can't be canceled. This is because
2370 * try_to_grab_pending() can't determine whether the work to be
2371 * grabbed is at the head of the queue and thus can't clear LINKED
2372 * flag of the previous work while there must be a valid next work
2373 * after a work with LINKED flag set.
2374 *
2375 * Note that when @worker is non-NULL, @target may be modified
Tejun Heo112202d2013-02-13 19:29:12 -08002376 * underneath us, so we can't reliably determine pwq from @target.
Tejun Heo4690c4a2010-06-29 10:07:10 +02002377 *
2378 * CONTEXT:
Tejun Heod565ed62013-01-24 11:01:33 -08002379 * spin_lock_irq(pool->lock).
Tejun Heo4690c4a2010-06-29 10:07:10 +02002380 */
Tejun Heo112202d2013-02-13 19:29:12 -08002381static void insert_wq_barrier(struct pool_workqueue *pwq,
Tejun Heoaffee4b2010-06-29 10:07:12 +02002382 struct wq_barrier *barr,
2383 struct work_struct *target, struct worker *worker)
Oleg Nesterovfc2e4d72007-05-09 02:33:51 -07002384{
Tejun Heoaffee4b2010-06-29 10:07:12 +02002385 struct list_head *head;
2386 unsigned int linked = 0;
2387
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +09002388 /*
Tejun Heod565ed62013-01-24 11:01:33 -08002389 * debugobject calls are safe here even with pool->lock locked
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +09002390 * as we know for sure that this will not trigger any of the
2391 * checks and call back into the fixup functions where we
2392 * might deadlock.
2393 */
Andrew Mortonca1cab32010-10-26 14:22:34 -07002394 INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
Tejun Heo22df02b2010-06-29 10:07:10 +02002395 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
Oleg Nesterovfc2e4d72007-05-09 02:33:51 -07002396 init_completion(&barr->done);
Oleg Nesterov83c22522007-05-09 02:33:54 -07002397
Tejun Heoaffee4b2010-06-29 10:07:12 +02002398 /*
2399 * If @target is currently being executed, schedule the
2400 * barrier to the worker; otherwise, put it after @target.
2401 */
2402 if (worker)
2403 head = worker->scheduled.next;
2404 else {
2405 unsigned long *bits = work_data_bits(target);
2406
2407 head = target->entry.next;
2408 /* there can already be other linked works, inherit and set */
2409 linked = *bits & WORK_STRUCT_LINKED;
2410 __set_bit(WORK_STRUCT_LINKED_BIT, bits);
2411 }
2412
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +09002413 debug_work_activate(&barr->work);
Tejun Heo112202d2013-02-13 19:29:12 -08002414 insert_work(pwq, &barr->work, head,
Tejun Heoaffee4b2010-06-29 10:07:12 +02002415 work_color_to_flags(WORK_NO_COLOR) | linked);
Oleg Nesterovfc2e4d72007-05-09 02:33:51 -07002416}
2417
Tejun Heo73f53c42010-06-29 10:07:11 +02002418/**
Tejun Heo112202d2013-02-13 19:29:12 -08002419 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
Tejun Heo73f53c42010-06-29 10:07:11 +02002420 * @wq: workqueue being flushed
2421 * @flush_color: new flush color, < 0 for no-op
2422 * @work_color: new work color, < 0 for no-op
2423 *
Tejun Heo112202d2013-02-13 19:29:12 -08002424 * Prepare pwqs for workqueue flushing.
Tejun Heo73f53c42010-06-29 10:07:11 +02002425 *
Tejun Heo112202d2013-02-13 19:29:12 -08002426 * If @flush_color is non-negative, flush_color on all pwqs should be
2427 * -1. If no pwq has in-flight commands at the specified color, all
2428 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2429 * has in flight commands, its pwq->flush_color is set to
2430 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
Tejun Heo73f53c42010-06-29 10:07:11 +02002431 * wakeup logic is armed and %true is returned.
2432 *
2433 * The caller should have initialized @wq->first_flusher prior to
2434 * calling this function with non-negative @flush_color. If
2435 * @flush_color is negative, no flush color update is done and %false
2436 * is returned.
2437 *
Tejun Heo112202d2013-02-13 19:29:12 -08002438 * If @work_color is non-negative, all pwqs should have the same
Tejun Heo73f53c42010-06-29 10:07:11 +02002439 * work_color which is previous to @work_color and all will be
2440 * advanced to @work_color.
2441 *
2442 * CONTEXT:
Lai Jiangshan3c25a552013-03-25 16:57:17 -07002443 * mutex_lock(wq->mutex).
Tejun Heo73f53c42010-06-29 10:07:11 +02002444 *
Yacine Belkadid185af32013-07-31 14:59:24 -07002445 * Return:
Tejun Heo73f53c42010-06-29 10:07:11 +02002446 * %true if @flush_color >= 0 and there's something to flush. %false
2447 * otherwise.
2448 */
Tejun Heo112202d2013-02-13 19:29:12 -08002449static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
Tejun Heo73f53c42010-06-29 10:07:11 +02002450 int flush_color, int work_color)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002451{
Tejun Heo73f53c42010-06-29 10:07:11 +02002452 bool wait = false;
Tejun Heo49e3cf42013-03-12 11:29:58 -07002453 struct pool_workqueue *pwq;
Oleg Nesterov14441962007-05-23 13:57:57 -07002454
Tejun Heo73f53c42010-06-29 10:07:11 +02002455 if (flush_color >= 0) {
Tejun Heo6183c002013-03-12 11:29:57 -07002456 WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
Tejun Heo112202d2013-02-13 19:29:12 -08002457 atomic_set(&wq->nr_pwqs_to_flush, 1);
Thomas Gleixnerdc186ad2009-11-16 01:09:48 +09002458 }
Oleg Nesterov14441962007-05-23 13:57:57 -07002459
Tejun Heo49e3cf42013-03-12 11:29:58 -07002460 for_each_pwq(pwq, wq) {
Tejun Heo112202d2013-02-13 19:29:12 -08002461 struct worker_pool *pool = pwq->pool;
Tejun Heo73f53c42010-06-29 10:07:11 +02002462
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07002463 spin_lock_irq(&pool->lock);
Tejun Heo73f53c42010-06-29 10:07:11 +02002464
2465 if (flush_color >= 0) {
Tejun Heo6183c002013-03-12 11:29:57 -07002466 WARN_ON_ONCE(pwq->flush_color != -1);
Tejun Heo73f53c42010-06-29 10:07:11 +02002467
Tejun Heo112202d2013-02-13 19:29:12 -08002468 if (pwq->nr_in_flight[flush_color]) {
2469 pwq->flush_color = flush_color;
2470 atomic_inc(&wq->nr_pwqs_to_flush);
Tejun Heo73f53c42010-06-29 10:07:11 +02002471 wait = true;
2472 }
2473 }
2474
2475 if (work_color >= 0) {
Tejun Heo6183c002013-03-12 11:29:57 -07002476 WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
Tejun Heo112202d2013-02-13 19:29:12 -08002477 pwq->work_color = work_color;
Tejun Heo73f53c42010-06-29 10:07:11 +02002478 }
2479
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07002480 spin_unlock_irq(&pool->lock);
Tejun Heo73f53c42010-06-29 10:07:11 +02002481 }
2482
Tejun Heo112202d2013-02-13 19:29:12 -08002483 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
Tejun Heo73f53c42010-06-29 10:07:11 +02002484 complete(&wq->first_flusher->done);
2485
2486 return wait;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487}
2488
Rolf Eike Beer0fcb78c2006-07-30 03:03:42 -07002489/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002490 * flush_workqueue - ensure that any scheduled work has run to completion.
Rolf Eike Beer0fcb78c2006-07-30 03:03:42 -07002491 * @wq: workqueue to flush
Linus Torvalds1da177e2005-04-16 15:20:36 -07002492 *
Tejun Heoc5aa87b2013-03-13 16:51:36 -07002493 * This function sleeps until all work items which were queued on entry
2494 * have finished execution, but it is not livelocked by new incoming ones.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002495 */
Harvey Harrison7ad5b3a2008-02-08 04:19:53 -08002496void flush_workqueue(struct workqueue_struct *wq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002497{
Tejun Heo73f53c42010-06-29 10:07:11 +02002498 struct wq_flusher this_flusher = {
2499 .list = LIST_HEAD_INIT(this_flusher.list),
2500 .flush_color = -1,
2501 .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
2502 };
2503 int next_color;
Oleg Nesterovb1f4ec12007-05-09 02:34:12 -07002504
Ingo Molnar3295f0e2008-08-11 10:30:30 +02002505 lock_map_acquire(&wq->lockdep_map);
2506 lock_map_release(&wq->lockdep_map);
Tejun Heo73f53c42010-06-29 10:07:11 +02002507
Lai Jiangshan3c25a552013-03-25 16:57:17 -07002508 mutex_lock(&wq->mutex);
Tejun Heo73f53c42010-06-29 10:07:11 +02002509
2510 /*
2511 * Start-to-wait phase
2512 */
2513 next_color = work_next_color(wq->work_color);
2514
2515 if (next_color != wq->flush_color) {
2516 /*
2517 * Color space is not full. The current work_color
2518 * becomes our flush_color and work_color is advanced
2519 * by one.
2520 */
Tejun Heo6183c002013-03-12 11:29:57 -07002521 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
Tejun Heo73f53c42010-06-29 10:07:11 +02002522 this_flusher.flush_color = wq->work_color;
2523 wq->work_color = next_color;
2524
2525 if (!wq->first_flusher) {
2526 /* no flush in progress, become the first flusher */
Tejun Heo6183c002013-03-12 11:29:57 -07002527 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
Tejun Heo73f53c42010-06-29 10:07:11 +02002528
2529 wq->first_flusher = &this_flusher;
2530
Tejun Heo112202d2013-02-13 19:29:12 -08002531 if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
Tejun Heo73f53c42010-06-29 10:07:11 +02002532 wq->work_color)) {
2533 /* nothing to flush, done */
2534 wq->flush_color = next_color;
2535 wq->first_flusher = NULL;
2536 goto out_unlock;
2537 }
2538 } else {
2539 /* wait in queue */
Tejun Heo6183c002013-03-12 11:29:57 -07002540 WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
Tejun Heo73f53c42010-06-29 10:07:11 +02002541 list_add_tail(&this_flusher.list, &wq->flusher_queue);
Tejun Heo112202d2013-02-13 19:29:12 -08002542 flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
Tejun Heo73f53c42010-06-29 10:07:11 +02002543 }
2544 } else {
2545 /*
2546 * Oops, color space is full, wait on overflow queue.
2547 * The next flush completion will assign us
2548 * flush_color and transfer to flusher_queue.
2549 */
2550 list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2551 }
2552
Lai Jiangshan3c25a552013-03-25 16:57:17 -07002553 mutex_unlock(&wq->mutex);
Tejun Heo73f53c42010-06-29 10:07:11 +02002554
2555 wait_for_completion(&this_flusher.done);
2556
2557 /*
2558 * Wake-up-and-cascade phase
2559 *
2560 * First flushers are responsible for cascading flushes and
2561 * handling overflow. Non-first flushers can simply return.
2562 */
2563 if (wq->first_flusher != &this_flusher)
2564 return;
2565
Lai Jiangshan3c25a552013-03-25 16:57:17 -07002566 mutex_lock(&wq->mutex);
Tejun Heo73f53c42010-06-29 10:07:11 +02002567
Tejun Heo4ce48b32010-07-02 10:03:51 +02002568 /* we might have raced, check again with mutex held */
2569 if (wq->first_flusher != &this_flusher)
2570 goto out_unlock;
2571
Tejun Heo73f53c42010-06-29 10:07:11 +02002572 wq->first_flusher = NULL;
2573
Tejun Heo6183c002013-03-12 11:29:57 -07002574 WARN_ON_ONCE(!list_empty(&this_flusher.list));
2575 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
Tejun Heo73f53c42010-06-29 10:07:11 +02002576
2577 while (true) {
2578 struct wq_flusher *next, *tmp;
2579
2580 /* complete all the flushers sharing the current flush color */
2581 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2582 if (next->flush_color != wq->flush_color)
2583 break;
2584 list_del_init(&next->list);
2585 complete(&next->done);
2586 }
2587
Tejun Heo6183c002013-03-12 11:29:57 -07002588 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
2589 wq->flush_color != work_next_color(wq->work_color));
Tejun Heo73f53c42010-06-29 10:07:11 +02002590
2591 /* this flush_color is finished, advance by one */
2592 wq->flush_color = work_next_color(wq->flush_color);
2593
2594 /* one color has been freed, handle overflow queue */
2595 if (!list_empty(&wq->flusher_overflow)) {
2596 /*
2597 * Assign the same color to all overflowed
2598 * flushers, advance work_color and append to
2599 * flusher_queue. This is the start-to-wait
2600 * phase for these overflowed flushers.
2601 */
2602 list_for_each_entry(tmp, &wq->flusher_overflow, list)
2603 tmp->flush_color = wq->work_color;
2604
2605 wq->work_color = work_next_color(wq->work_color);
2606
2607 list_splice_tail_init(&wq->flusher_overflow,
2608 &wq->flusher_queue);
Tejun Heo112202d2013-02-13 19:29:12 -08002609 flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
Tejun Heo73f53c42010-06-29 10:07:11 +02002610 }
2611
2612 if (list_empty(&wq->flusher_queue)) {
Tejun Heo6183c002013-03-12 11:29:57 -07002613 WARN_ON_ONCE(wq->flush_color != wq->work_color);
Tejun Heo73f53c42010-06-29 10:07:11 +02002614 break;
2615 }
2616
2617 /*
2618 * Need to flush more colors. Make the next flusher
Tejun Heo112202d2013-02-13 19:29:12 -08002619 * the new first flusher and arm pwqs.
Tejun Heo73f53c42010-06-29 10:07:11 +02002620 */
Tejun Heo6183c002013-03-12 11:29:57 -07002621 WARN_ON_ONCE(wq->flush_color == wq->work_color);
2622 WARN_ON_ONCE(wq->flush_color != next->flush_color);
Tejun Heo73f53c42010-06-29 10:07:11 +02002623
2624 list_del_init(&next->list);
2625 wq->first_flusher = next;
2626
Tejun Heo112202d2013-02-13 19:29:12 -08002627 if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
Tejun Heo73f53c42010-06-29 10:07:11 +02002628 break;
2629
2630 /*
2631 * Meh... this color is already done, clear first
2632 * flusher and repeat cascading.
2633 */
2634 wq->first_flusher = NULL;
2635 }
2636
2637out_unlock:
Lai Jiangshan3c25a552013-03-25 16:57:17 -07002638 mutex_unlock(&wq->mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002639}
Dave Jonesae90dd52006-06-30 01:40:45 -04002640EXPORT_SYMBOL_GPL(flush_workqueue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002641
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002642/**
2643 * drain_workqueue - drain a workqueue
2644 * @wq: workqueue to drain
2645 *
2646 * Wait until the workqueue becomes empty. While draining is in progress,
2647 * only chain queueing is allowed. IOW, only currently pending or running
2648 * work items on @wq can queue further work items on it. @wq is flushed
2649 * repeatedly until it becomes empty. The number of flushing is detemined
2650 * by the depth of chaining and should be relatively short. Whine if it
2651 * takes too long.
2652 */
2653void drain_workqueue(struct workqueue_struct *wq)
2654{
2655 unsigned int flush_cnt = 0;
Tejun Heo49e3cf42013-03-12 11:29:58 -07002656 struct pool_workqueue *pwq;
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002657
2658 /*
2659 * __queue_work() needs to test whether there are drainers, is much
2660 * hotter than drain_workqueue() and already looks at @wq->flags.
Tejun Heo618b01e2013-03-12 11:30:04 -07002661 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002662 */
Lai Jiangshan87fc7412013-03-25 16:57:18 -07002663 mutex_lock(&wq->mutex);
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002664 if (!wq->nr_drainers++)
Tejun Heo618b01e2013-03-12 11:30:04 -07002665 wq->flags |= __WQ_DRAINING;
Lai Jiangshan87fc7412013-03-25 16:57:18 -07002666 mutex_unlock(&wq->mutex);
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002667reflush:
2668 flush_workqueue(wq);
2669
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07002670 mutex_lock(&wq->mutex);
Tejun Heo76af4d92013-03-12 11:30:00 -07002671
Tejun Heo49e3cf42013-03-12 11:29:58 -07002672 for_each_pwq(pwq, wq) {
Thomas Tuttlefa2563e2011-09-14 16:22:28 -07002673 bool drained;
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002674
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07002675 spin_lock_irq(&pwq->pool->lock);
Tejun Heo112202d2013-02-13 19:29:12 -08002676 drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07002677 spin_unlock_irq(&pwq->pool->lock);
Thomas Tuttlefa2563e2011-09-14 16:22:28 -07002678
2679 if (drained)
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002680 continue;
2681
2682 if (++flush_cnt == 10 ||
2683 (flush_cnt % 100 == 0 && flush_cnt <= 1000))
Tejun Heoc5aa87b2013-03-13 16:51:36 -07002684 pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
Valentin Ilie044c7822012-08-19 00:52:42 +03002685 wq->name, flush_cnt);
Tejun Heo76af4d92013-03-12 11:30:00 -07002686
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07002687 mutex_unlock(&wq->mutex);
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002688 goto reflush;
2689 }
2690
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002691 if (!--wq->nr_drainers)
Tejun Heo618b01e2013-03-12 11:30:04 -07002692 wq->flags &= ~__WQ_DRAINING;
Lai Jiangshan87fc7412013-03-25 16:57:18 -07002693 mutex_unlock(&wq->mutex);
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02002694}
2695EXPORT_SYMBOL_GPL(drain_workqueue);
2696
Tejun Heo606a5022012-08-20 14:51:23 -07002697static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
Tejun Heobaf59022010-09-16 10:42:16 +02002698{
2699 struct worker *worker = NULL;
Tejun Heoc9e7cf22013-01-24 11:01:33 -08002700 struct worker_pool *pool;
Tejun Heo112202d2013-02-13 19:29:12 -08002701 struct pool_workqueue *pwq;
Tejun Heobaf59022010-09-16 10:42:16 +02002702
2703 might_sleep();
Tejun Heobaf59022010-09-16 10:42:16 +02002704
Tejun Heofa1b54e2013-03-12 11:30:00 -07002705 local_irq_disable();
2706 pool = get_work_pool(work);
2707 if (!pool) {
2708 local_irq_enable();
2709 return false;
2710 }
2711
2712 spin_lock(&pool->lock);
Lai Jiangshan0b3dae62013-02-06 18:04:53 -08002713 /* see the comment in try_to_grab_pending() with the same code */
Tejun Heo112202d2013-02-13 19:29:12 -08002714 pwq = get_work_pwq(work);
2715 if (pwq) {
2716 if (unlikely(pwq->pool != pool))
Tejun Heobaf59022010-09-16 10:42:16 +02002717 goto already_gone;
Tejun Heo606a5022012-08-20 14:51:23 -07002718 } else {
Tejun Heoc9e7cf22013-01-24 11:01:33 -08002719 worker = find_worker_executing_work(pool, work);
Tejun Heobaf59022010-09-16 10:42:16 +02002720 if (!worker)
2721 goto already_gone;
Tejun Heo112202d2013-02-13 19:29:12 -08002722 pwq = worker->current_pwq;
Tejun Heo606a5022012-08-20 14:51:23 -07002723 }
Tejun Heobaf59022010-09-16 10:42:16 +02002724
Tejun Heo112202d2013-02-13 19:29:12 -08002725 insert_wq_barrier(pwq, barr, work, worker);
Tejun Heod565ed62013-01-24 11:01:33 -08002726 spin_unlock_irq(&pool->lock);
Tejun Heobaf59022010-09-16 10:42:16 +02002727
Tejun Heoe1594892011-01-09 23:32:15 +01002728 /*
2729 * If @max_active is 1 or rescuer is in use, flushing another work
2730 * item on the same workqueue may lead to deadlock. Make sure the
2731 * flusher is not running on the same workqueue by verifying write
2732 * access.
2733 */
Tejun Heo493008a2013-03-12 11:30:03 -07002734 if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)
Tejun Heo112202d2013-02-13 19:29:12 -08002735 lock_map_acquire(&pwq->wq->lockdep_map);
Tejun Heoe1594892011-01-09 23:32:15 +01002736 else
Tejun Heo112202d2013-02-13 19:29:12 -08002737 lock_map_acquire_read(&pwq->wq->lockdep_map);
2738 lock_map_release(&pwq->wq->lockdep_map);
Tejun Heoe1594892011-01-09 23:32:15 +01002739
Tejun Heobaf59022010-09-16 10:42:16 +02002740 return true;
2741already_gone:
Tejun Heod565ed62013-01-24 11:01:33 -08002742 spin_unlock_irq(&pool->lock);
Tejun Heobaf59022010-09-16 10:42:16 +02002743 return false;
2744}
2745
Oleg Nesterovdb700892008-07-25 01:47:49 -07002746/**
Tejun Heo401a8d02010-09-16 10:36:00 +02002747 * flush_work - wait for a work to finish executing the last queueing instance
2748 * @work: the work to flush
Oleg Nesterovdb700892008-07-25 01:47:49 -07002749 *
Tejun Heo606a5022012-08-20 14:51:23 -07002750 * Wait until @work has finished execution. @work is guaranteed to be idle
2751 * on return if it hasn't been requeued since flush started.
Tejun Heo401a8d02010-09-16 10:36:00 +02002752 *
Yacine Belkadid185af32013-07-31 14:59:24 -07002753 * Return:
Tejun Heo401a8d02010-09-16 10:36:00 +02002754 * %true if flush_work() waited for the work to finish execution,
2755 * %false if it was already idle.
Oleg Nesterovdb700892008-07-25 01:47:49 -07002756 */
Tejun Heo401a8d02010-09-16 10:36:00 +02002757bool flush_work(struct work_struct *work)
Oleg Nesterovdb700892008-07-25 01:47:49 -07002758{
Bjorn Helgaas12997d12013-11-18 11:00:29 -07002759 struct wq_barrier barr;
2760
Stephen Boyd0976dfc2012-04-20 17:28:50 -07002761 lock_map_acquire(&work->lockdep_map);
2762 lock_map_release(&work->lockdep_map);
2763
Bjorn Helgaas12997d12013-11-18 11:00:29 -07002764 if (start_flush_work(work, &barr)) {
2765 wait_for_completion(&barr.done);
2766 destroy_work_on_stack(&barr.work);
2767 return true;
2768 } else {
2769 return false;
2770 }
Oleg Nesterovdb700892008-07-25 01:47:49 -07002771}
2772EXPORT_SYMBOL_GPL(flush_work);
2773
Tejun Heo36e227d2012-08-03 10:30:46 -07002774static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
Tejun Heo401a8d02010-09-16 10:36:00 +02002775{
Tejun Heobbb68df2012-08-03 10:30:46 -07002776 unsigned long flags;
Oleg Nesterov1f1f6422007-07-15 23:41:44 -07002777 int ret;
2778
2779 do {
Tejun Heobbb68df2012-08-03 10:30:46 -07002780 ret = try_to_grab_pending(work, is_dwork, &flags);
2781 /*
2782 * If someone else is canceling, wait for the same event it
2783 * would be waiting for before retrying.
2784 */
2785 if (unlikely(ret == -ENOENT))
Tejun Heo606a5022012-08-20 14:51:23 -07002786 flush_work(work);
Oleg Nesterov1f1f6422007-07-15 23:41:44 -07002787 } while (unlikely(ret < 0));
2788
Tejun Heobbb68df2012-08-03 10:30:46 -07002789 /* tell other tasks trying to grab @work to back off */
2790 mark_work_canceling(work);
2791 local_irq_restore(flags);
2792
Tejun Heo606a5022012-08-20 14:51:23 -07002793 flush_work(work);
Tejun Heo7a22ad72010-06-29 10:07:13 +02002794 clear_work_data(work);
Oleg Nesterov1f1f6422007-07-15 23:41:44 -07002795 return ret;
2796}
2797
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002798/**
Tejun Heo401a8d02010-09-16 10:36:00 +02002799 * cancel_work_sync - cancel a work and wait for it to finish
2800 * @work: the work to cancel
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002801 *
Tejun Heo401a8d02010-09-16 10:36:00 +02002802 * Cancel @work and wait for its execution to finish. This function
2803 * can be used even if the work re-queues itself or migrates to
2804 * another workqueue. On return from this function, @work is
2805 * guaranteed to be not pending or executing on any CPU.
Oleg Nesterov1f1f6422007-07-15 23:41:44 -07002806 *
Tejun Heo401a8d02010-09-16 10:36:00 +02002807 * cancel_work_sync(&delayed_work->work) must not be used for
2808 * delayed_work's. Use cancel_delayed_work_sync() instead.
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002809 *
Tejun Heo401a8d02010-09-16 10:36:00 +02002810 * The caller must ensure that the workqueue on which @work was last
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002811 * queued can't be destroyed before this function returns.
Tejun Heo401a8d02010-09-16 10:36:00 +02002812 *
Yacine Belkadid185af32013-07-31 14:59:24 -07002813 * Return:
Tejun Heo401a8d02010-09-16 10:36:00 +02002814 * %true if @work was pending, %false otherwise.
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002815 */
Tejun Heo401a8d02010-09-16 10:36:00 +02002816bool cancel_work_sync(struct work_struct *work)
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002817{
Tejun Heo36e227d2012-08-03 10:30:46 -07002818 return __cancel_work_timer(work, false);
Oleg Nesterovb89deed2007-05-09 02:33:52 -07002819}
Oleg Nesterov28e53bd2007-05-09 02:34:22 -07002820EXPORT_SYMBOL_GPL(cancel_work_sync);
Oleg Nesterovb89deed2007-05-09 02:33:52 -07002821
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002822/**
Tejun Heo401a8d02010-09-16 10:36:00 +02002823 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2824 * @dwork: the delayed work to flush
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002825 *
Tejun Heo401a8d02010-09-16 10:36:00 +02002826 * Delayed timer is cancelled and the pending work is queued for
2827 * immediate execution. Like flush_work(), this function only
2828 * considers the last queueing instance of @dwork.
Oleg Nesterov1f1f6422007-07-15 23:41:44 -07002829 *
Yacine Belkadid185af32013-07-31 14:59:24 -07002830 * Return:
Tejun Heo401a8d02010-09-16 10:36:00 +02002831 * %true if flush_work() waited for the work to finish execution,
2832 * %false if it was already idle.
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002833 */
Tejun Heo401a8d02010-09-16 10:36:00 +02002834bool flush_delayed_work(struct delayed_work *dwork)
2835{
Tejun Heo8930cab2012-08-03 10:30:45 -07002836 local_irq_disable();
Tejun Heo401a8d02010-09-16 10:36:00 +02002837 if (del_timer_sync(&dwork->timer))
Lai Jiangshan60c057b2013-02-06 18:04:53 -08002838 __queue_work(dwork->cpu, dwork->wq, &dwork->work);
Tejun Heo8930cab2012-08-03 10:30:45 -07002839 local_irq_enable();
Tejun Heo401a8d02010-09-16 10:36:00 +02002840 return flush_work(&dwork->work);
2841}
2842EXPORT_SYMBOL(flush_delayed_work);
2843
2844/**
Tejun Heo57b30ae2012-08-21 13:18:24 -07002845 * cancel_delayed_work - cancel a delayed work
2846 * @dwork: delayed_work to cancel
Tejun Heo09383492010-09-16 10:48:29 +02002847 *
Yacine Belkadid185af32013-07-31 14:59:24 -07002848 * Kill off a pending delayed_work.
2849 *
2850 * Return: %true if @dwork was pending and canceled; %false if it wasn't
2851 * pending.
2852 *
2853 * Note:
2854 * The work callback function may still be running on return, unless
2855 * it returns %true and the work doesn't re-arm itself. Explicitly flush or
2856 * use cancel_delayed_work_sync() to wait on it.
Tejun Heo09383492010-09-16 10:48:29 +02002857 *
Tejun Heo57b30ae2012-08-21 13:18:24 -07002858 * This function is safe to call from any context including IRQ handler.
Tejun Heo09383492010-09-16 10:48:29 +02002859 */
Tejun Heo57b30ae2012-08-21 13:18:24 -07002860bool cancel_delayed_work(struct delayed_work *dwork)
Tejun Heo09383492010-09-16 10:48:29 +02002861{
Tejun Heo57b30ae2012-08-21 13:18:24 -07002862 unsigned long flags;
2863 int ret;
2864
2865 do {
2866 ret = try_to_grab_pending(&dwork->work, true, &flags);
2867 } while (unlikely(ret == -EAGAIN));
2868
2869 if (unlikely(ret < 0))
2870 return false;
2871
Tejun Heo7c3eed52013-01-24 11:01:33 -08002872 set_work_pool_and_clear_pending(&dwork->work,
2873 get_work_pool_id(&dwork->work));
Tejun Heo57b30ae2012-08-21 13:18:24 -07002874 local_irq_restore(flags);
Dan Magenheimerc0158ca2012-10-18 16:31:37 -07002875 return ret;
Tejun Heo09383492010-09-16 10:48:29 +02002876}
Tejun Heo57b30ae2012-08-21 13:18:24 -07002877EXPORT_SYMBOL(cancel_delayed_work);
Tejun Heo09383492010-09-16 10:48:29 +02002878
2879/**
Tejun Heo401a8d02010-09-16 10:36:00 +02002880 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2881 * @dwork: the delayed work cancel
2882 *
2883 * This is cancel_work_sync() for delayed works.
2884 *
Yacine Belkadid185af32013-07-31 14:59:24 -07002885 * Return:
Tejun Heo401a8d02010-09-16 10:36:00 +02002886 * %true if @dwork was pending, %false otherwise.
2887 */
2888bool cancel_delayed_work_sync(struct delayed_work *dwork)
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002889{
Tejun Heo36e227d2012-08-03 10:30:46 -07002890 return __cancel_work_timer(&dwork->work, true);
Oleg Nesterov6e84d642007-05-09 02:34:46 -07002891}
Oleg Nesterovf5a421a2007-07-15 23:41:44 -07002892EXPORT_SYMBOL(cancel_delayed_work_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002893
Rolf Eike Beer0fcb78c2006-07-30 03:03:42 -07002894/**
Tejun Heo31ddd872010-10-19 11:14:49 +02002895 * schedule_on_each_cpu - execute a function synchronously on each online CPU
Andrew Mortonb6136772006-06-25 05:47:49 -07002896 * @func: the function to call
Andrew Mortonb6136772006-06-25 05:47:49 -07002897 *
Tejun Heo31ddd872010-10-19 11:14:49 +02002898 * schedule_on_each_cpu() executes @func on each online CPU using the
2899 * system workqueue and blocks until all CPUs have completed.
Andrew Mortonb6136772006-06-25 05:47:49 -07002900 * schedule_on_each_cpu() is very slow.
Tejun Heo31ddd872010-10-19 11:14:49 +02002901 *
Yacine Belkadid185af32013-07-31 14:59:24 -07002902 * Return:
Tejun Heo31ddd872010-10-19 11:14:49 +02002903 * 0 on success, -errno on failure.
Andrew Mortonb6136772006-06-25 05:47:49 -07002904 */
David Howells65f27f32006-11-22 14:55:48 +00002905int schedule_on_each_cpu(work_func_t func)
Christoph Lameter15316ba2006-01-08 01:00:43 -08002906{
2907 int cpu;
Namhyung Kim38f51562010-08-08 14:24:09 +02002908 struct work_struct __percpu *works;
Christoph Lameter15316ba2006-01-08 01:00:43 -08002909
Andrew Mortonb6136772006-06-25 05:47:49 -07002910 works = alloc_percpu(struct work_struct);
2911 if (!works)
Christoph Lameter15316ba2006-01-08 01:00:43 -08002912 return -ENOMEM;
Andrew Mortonb6136772006-06-25 05:47:49 -07002913
Gautham R Shenoy95402b32008-01-25 21:08:02 +01002914 get_online_cpus();
Tejun Heo93981802009-11-17 14:06:20 -08002915
Christoph Lameter15316ba2006-01-08 01:00:43 -08002916 for_each_online_cpu(cpu) {
Ingo Molnar9bfb1832006-12-18 20:05:09 +01002917 struct work_struct *work = per_cpu_ptr(works, cpu);
2918
2919 INIT_WORK(work, func);
Tejun Heob71ab8c2010-06-29 10:07:14 +02002920 schedule_work_on(cpu, work);
Andi Kleen65a64462009-10-14 06:22:47 +02002921 }
Tejun Heo93981802009-11-17 14:06:20 -08002922
2923 for_each_online_cpu(cpu)
2924 flush_work(per_cpu_ptr(works, cpu));
2925
Gautham R Shenoy95402b32008-01-25 21:08:02 +01002926 put_online_cpus();
Andrew Mortonb6136772006-06-25 05:47:49 -07002927 free_percpu(works);
Christoph Lameter15316ba2006-01-08 01:00:43 -08002928 return 0;
2929}
2930
Alan Sterneef6a7d2010-02-12 17:39:21 +09002931/**
2932 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2933 *
2934 * Forces execution of the kernel-global workqueue and blocks until its
2935 * completion.
2936 *
2937 * Think twice before calling this function! It's very easy to get into
2938 * trouble if you don't take great care. Either of the following situations
2939 * will lead to deadlock:
2940 *
2941 * One of the work items currently on the workqueue needs to acquire
2942 * a lock held by your code or its caller.
2943 *
2944 * Your code is running in the context of a work routine.
2945 *
2946 * They will be detected by lockdep when they occur, but the first might not
2947 * occur very often. It depends on what work items are on the workqueue and
2948 * what locks they need, which you have no control over.
2949 *
2950 * In most situations flushing the entire workqueue is overkill; you merely
2951 * need to know that a particular work item isn't queued and isn't running.
2952 * In such cases you should use cancel_delayed_work_sync() or
2953 * cancel_work_sync() instead.
2954 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002955void flush_scheduled_work(void)
2956{
Tejun Heod320c032010-06-29 10:07:14 +02002957 flush_workqueue(system_wq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002958}
Dave Jonesae90dd52006-06-30 01:40:45 -04002959EXPORT_SYMBOL(flush_scheduled_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002960
2961/**
James Bottomley1fa44ec2006-02-23 12:43:43 -06002962 * execute_in_process_context - reliably execute the routine with user context
2963 * @fn: the function to execute
James Bottomley1fa44ec2006-02-23 12:43:43 -06002964 * @ew: guaranteed storage for the execute work structure (must
2965 * be available when the work executes)
2966 *
2967 * Executes the function immediately if process context is available,
2968 * otherwise schedules the function for delayed execution.
2969 *
Yacine Belkadid185af32013-07-31 14:59:24 -07002970 * Return: 0 - function was executed
James Bottomley1fa44ec2006-02-23 12:43:43 -06002971 * 1 - function was scheduled for execution
2972 */
David Howells65f27f32006-11-22 14:55:48 +00002973int execute_in_process_context(work_func_t fn, struct execute_work *ew)
James Bottomley1fa44ec2006-02-23 12:43:43 -06002974{
2975 if (!in_interrupt()) {
David Howells65f27f32006-11-22 14:55:48 +00002976 fn(&ew->work);
James Bottomley1fa44ec2006-02-23 12:43:43 -06002977 return 0;
2978 }
2979
David Howells65f27f32006-11-22 14:55:48 +00002980 INIT_WORK(&ew->work, fn);
James Bottomley1fa44ec2006-02-23 12:43:43 -06002981 schedule_work(&ew->work);
2982
2983 return 1;
2984}
2985EXPORT_SYMBOL_GPL(execute_in_process_context);
2986
Tejun Heo226223a2013-03-12 11:30:05 -07002987#ifdef CONFIG_SYSFS
2988/*
2989 * Workqueues with WQ_SYSFS flag set is visible to userland via
2990 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
2991 * following attributes.
2992 *
2993 * per_cpu RO bool : whether the workqueue is per-cpu or unbound
2994 * max_active RW int : maximum number of in-flight work items
2995 *
2996 * Unbound workqueues have the following extra attributes.
2997 *
2998 * id RO int : the associated pool ID
2999 * nice RW int : nice value of the workers
3000 * cpumask RW mask : bitmask of allowed CPUs for the workers
3001 */
3002struct wq_device {
3003 struct workqueue_struct *wq;
3004 struct device dev;
3005};
3006
3007static struct workqueue_struct *dev_to_wq(struct device *dev)
3008{
3009 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
3010
3011 return wq_dev->wq;
3012}
3013
Greg Kroah-Hartman1a6661d2013-08-23 14:24:41 -07003014static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr,
3015 char *buf)
Tejun Heo226223a2013-03-12 11:30:05 -07003016{
3017 struct workqueue_struct *wq = dev_to_wq(dev);
3018
3019 return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
3020}
Greg Kroah-Hartman1a6661d2013-08-23 14:24:41 -07003021static DEVICE_ATTR_RO(per_cpu);
Tejun Heo226223a2013-03-12 11:30:05 -07003022
Greg Kroah-Hartman1a6661d2013-08-23 14:24:41 -07003023static ssize_t max_active_show(struct device *dev,
3024 struct device_attribute *attr, char *buf)
Tejun Heo226223a2013-03-12 11:30:05 -07003025{
3026 struct workqueue_struct *wq = dev_to_wq(dev);
3027
3028 return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
3029}
3030
Greg Kroah-Hartman1a6661d2013-08-23 14:24:41 -07003031static ssize_t max_active_store(struct device *dev,
3032 struct device_attribute *attr, const char *buf,
3033 size_t count)
Tejun Heo226223a2013-03-12 11:30:05 -07003034{
3035 struct workqueue_struct *wq = dev_to_wq(dev);
3036 int val;
3037
3038 if (sscanf(buf, "%d", &val) != 1 || val <= 0)
3039 return -EINVAL;
3040
3041 workqueue_set_max_active(wq, val);
3042 return count;
3043}
Greg Kroah-Hartman1a6661d2013-08-23 14:24:41 -07003044static DEVICE_ATTR_RW(max_active);
Tejun Heo226223a2013-03-12 11:30:05 -07003045
Greg Kroah-Hartman1a6661d2013-08-23 14:24:41 -07003046static struct attribute *wq_sysfs_attrs[] = {
3047 &dev_attr_per_cpu.attr,
3048 &dev_attr_max_active.attr,
3049 NULL,
Tejun Heo226223a2013-03-12 11:30:05 -07003050};
Greg Kroah-Hartman1a6661d2013-08-23 14:24:41 -07003051ATTRIBUTE_GROUPS(wq_sysfs);
Tejun Heo226223a2013-03-12 11:30:05 -07003052
Tejun Heod55262c2013-04-01 11:23:38 -07003053static ssize_t wq_pool_ids_show(struct device *dev,
3054 struct device_attribute *attr, char *buf)
Tejun Heo226223a2013-03-12 11:30:05 -07003055{
3056 struct workqueue_struct *wq = dev_to_wq(dev);
Tejun Heod55262c2013-04-01 11:23:38 -07003057 const char *delim = "";
3058 int node, written = 0;
Tejun Heo226223a2013-03-12 11:30:05 -07003059
3060 rcu_read_lock_sched();
Tejun Heod55262c2013-04-01 11:23:38 -07003061 for_each_node(node) {
3062 written += scnprintf(buf + written, PAGE_SIZE - written,
3063 "%s%d:%d", delim, node,
3064 unbound_pwq_by_node(wq, node)->pool->id);
3065 delim = " ";
3066 }
3067 written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
Tejun Heo226223a2013-03-12 11:30:05 -07003068 rcu_read_unlock_sched();
3069
3070 return written;
3071}
3072
3073static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr,
3074 char *buf)
3075{
3076 struct workqueue_struct *wq = dev_to_wq(dev);
3077 int written;
3078
Tejun Heo6029a912013-04-01 11:23:34 -07003079 mutex_lock(&wq->mutex);
3080 written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
3081 mutex_unlock(&wq->mutex);
Tejun Heo226223a2013-03-12 11:30:05 -07003082
3083 return written;
3084}
3085
3086/* prepare workqueue_attrs for sysfs store operations */
3087static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq)
3088{
3089 struct workqueue_attrs *attrs;
3090
3091 attrs = alloc_workqueue_attrs(GFP_KERNEL);
3092 if (!attrs)
3093 return NULL;
3094
Tejun Heo6029a912013-04-01 11:23:34 -07003095 mutex_lock(&wq->mutex);
3096 copy_workqueue_attrs(attrs, wq->unbound_attrs);
3097 mutex_unlock(&wq->mutex);
Tejun Heo226223a2013-03-12 11:30:05 -07003098 return attrs;
3099}
3100
3101static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr,
3102 const char *buf, size_t count)
3103{
3104 struct workqueue_struct *wq = dev_to_wq(dev);
3105 struct workqueue_attrs *attrs;
3106 int ret;
3107
3108 attrs = wq_sysfs_prep_attrs(wq);
3109 if (!attrs)
3110 return -ENOMEM;
3111
3112 if (sscanf(buf, "%d", &attrs->nice) == 1 &&
Dongsheng Yang14481842014-02-11 15:34:52 +08003113 attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)
Tejun Heo226223a2013-03-12 11:30:05 -07003114 ret = apply_workqueue_attrs(wq, attrs);
3115 else
3116 ret = -EINVAL;
3117
3118 free_workqueue_attrs(attrs);
3119 return ret ?: count;
3120}
3121
3122static ssize_t wq_cpumask_show(struct device *dev,
3123 struct device_attribute *attr, char *buf)
3124{
3125 struct workqueue_struct *wq = dev_to_wq(dev);
3126 int written;
3127
Tejun Heo6029a912013-04-01 11:23:34 -07003128 mutex_lock(&wq->mutex);
3129 written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask);
3130 mutex_unlock(&wq->mutex);
Tejun Heo226223a2013-03-12 11:30:05 -07003131
3132 written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
3133 return written;
3134}
3135
3136static ssize_t wq_cpumask_store(struct device *dev,
3137 struct device_attribute *attr,
3138 const char *buf, size_t count)
3139{
3140 struct workqueue_struct *wq = dev_to_wq(dev);
3141 struct workqueue_attrs *attrs;
3142 int ret;
3143
3144 attrs = wq_sysfs_prep_attrs(wq);
3145 if (!attrs)
3146 return -ENOMEM;
3147
3148 ret = cpumask_parse(buf, attrs->cpumask);
3149 if (!ret)
3150 ret = apply_workqueue_attrs(wq, attrs);
3151
3152 free_workqueue_attrs(attrs);
3153 return ret ?: count;
3154}
3155
Tejun Heod55262c2013-04-01 11:23:38 -07003156static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr,
3157 char *buf)
3158{
3159 struct workqueue_struct *wq = dev_to_wq(dev);
3160 int written;
3161
3162 mutex_lock(&wq->mutex);
3163 written = scnprintf(buf, PAGE_SIZE, "%d\n",
3164 !wq->unbound_attrs->no_numa);
3165 mutex_unlock(&wq->mutex);
3166
3167 return written;
3168}
3169
3170static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr,
3171 const char *buf, size_t count)
3172{
3173 struct workqueue_struct *wq = dev_to_wq(dev);
3174 struct workqueue_attrs *attrs;
3175 int v, ret;
3176
3177 attrs = wq_sysfs_prep_attrs(wq);
3178 if (!attrs)
3179 return -ENOMEM;
3180
3181 ret = -EINVAL;
3182 if (sscanf(buf, "%d", &v) == 1) {
3183 attrs->no_numa = !v;
3184 ret = apply_workqueue_attrs(wq, attrs);
3185 }
3186
3187 free_workqueue_attrs(attrs);
3188 return ret ?: count;
3189}
3190
Tejun Heo226223a2013-03-12 11:30:05 -07003191static struct device_attribute wq_sysfs_unbound_attrs[] = {
Tejun Heod55262c2013-04-01 11:23:38 -07003192 __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL),
Tejun Heo226223a2013-03-12 11:30:05 -07003193 __ATTR(nice, 0644, wq_nice_show, wq_nice_store),
3194 __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
Tejun Heod55262c2013-04-01 11:23:38 -07003195 __ATTR(numa, 0644, wq_numa_show, wq_numa_store),
Tejun Heo226223a2013-03-12 11:30:05 -07003196 __ATTR_NULL,
3197};
3198
3199static struct bus_type wq_subsys = {
3200 .name = "workqueue",
Greg Kroah-Hartman1a6661d2013-08-23 14:24:41 -07003201 .dev_groups = wq_sysfs_groups,
Tejun Heo226223a2013-03-12 11:30:05 -07003202};
3203
3204static int __init wq_sysfs_init(void)
3205{
3206 return subsys_virtual_register(&wq_subsys, NULL);
3207}
3208core_initcall(wq_sysfs_init);
3209
3210static void wq_device_release(struct device *dev)
3211{
3212 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
3213
3214 kfree(wq_dev);
3215}
3216
3217/**
3218 * workqueue_sysfs_register - make a workqueue visible in sysfs
3219 * @wq: the workqueue to register
3220 *
3221 * Expose @wq in sysfs under /sys/bus/workqueue/devices.
3222 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
3223 * which is the preferred method.
3224 *
3225 * Workqueue user should use this function directly iff it wants to apply
3226 * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
3227 * apply_workqueue_attrs() may race against userland updating the
3228 * attributes.
3229 *
Yacine Belkadid185af32013-07-31 14:59:24 -07003230 * Return: 0 on success, -errno on failure.
Tejun Heo226223a2013-03-12 11:30:05 -07003231 */
3232int workqueue_sysfs_register(struct workqueue_struct *wq)
3233{
3234 struct wq_device *wq_dev;
3235 int ret;
3236
3237 /*
3238 * Adjusting max_active or creating new pwqs by applyting
3239 * attributes breaks ordering guarantee. Disallow exposing ordered
3240 * workqueues.
3241 */
3242 if (WARN_ON(wq->flags & __WQ_ORDERED))
3243 return -EINVAL;
3244
3245 wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
3246 if (!wq_dev)
3247 return -ENOMEM;
3248
3249 wq_dev->wq = wq;
3250 wq_dev->dev.bus = &wq_subsys;
3251 wq_dev->dev.init_name = wq->name;
3252 wq_dev->dev.release = wq_device_release;
3253
3254 /*
3255 * unbound_attrs are created separately. Suppress uevent until
3256 * everything is ready.
3257 */
3258 dev_set_uevent_suppress(&wq_dev->dev, true);
3259
3260 ret = device_register(&wq_dev->dev);
3261 if (ret) {
3262 kfree(wq_dev);
3263 wq->wq_dev = NULL;
3264 return ret;
3265 }
3266
3267 if (wq->flags & WQ_UNBOUND) {
3268 struct device_attribute *attr;
3269
3270 for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
3271 ret = device_create_file(&wq_dev->dev, attr);
3272 if (ret) {
3273 device_unregister(&wq_dev->dev);
3274 wq->wq_dev = NULL;
3275 return ret;
3276 }
3277 }
3278 }
3279
3280 kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
3281 return 0;
3282}
3283
3284/**
3285 * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
3286 * @wq: the workqueue to unregister
3287 *
3288 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
3289 */
3290static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
3291{
3292 struct wq_device *wq_dev = wq->wq_dev;
3293
3294 if (!wq->wq_dev)
3295 return;
3296
3297 wq->wq_dev = NULL;
3298 device_unregister(&wq_dev->dev);
3299}
3300#else /* CONFIG_SYSFS */
3301static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
3302#endif /* CONFIG_SYSFS */
3303
Tejun Heo7a4e3442013-03-12 11:30:00 -07003304/**
3305 * free_workqueue_attrs - free a workqueue_attrs
3306 * @attrs: workqueue_attrs to free
3307 *
3308 * Undo alloc_workqueue_attrs().
3309 */
3310void free_workqueue_attrs(struct workqueue_attrs *attrs)
3311{
3312 if (attrs) {
3313 free_cpumask_var(attrs->cpumask);
3314 kfree(attrs);
3315 }
3316}
3317
3318/**
3319 * alloc_workqueue_attrs - allocate a workqueue_attrs
3320 * @gfp_mask: allocation mask to use
3321 *
3322 * Allocate a new workqueue_attrs, initialize with default settings and
Yacine Belkadid185af32013-07-31 14:59:24 -07003323 * return it.
3324 *
3325 * Return: The allocated new workqueue_attr on success. %NULL on failure.
Tejun Heo7a4e3442013-03-12 11:30:00 -07003326 */
3327struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask)
3328{
3329 struct workqueue_attrs *attrs;
3330
3331 attrs = kzalloc(sizeof(*attrs), gfp_mask);
3332 if (!attrs)
3333 goto fail;
3334 if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask))
3335 goto fail;
3336
Tejun Heo13e2e552013-04-01 11:23:31 -07003337 cpumask_copy(attrs->cpumask, cpu_possible_mask);
Tejun Heo7a4e3442013-03-12 11:30:00 -07003338 return attrs;
3339fail:
3340 free_workqueue_attrs(attrs);
3341 return NULL;
3342}
3343
Tejun Heo29c91e92013-03-12 11:30:03 -07003344static void copy_workqueue_attrs(struct workqueue_attrs *to,
3345 const struct workqueue_attrs *from)
3346{
3347 to->nice = from->nice;
3348 cpumask_copy(to->cpumask, from->cpumask);
Shaohua Li2865a8f2013-08-01 09:56:36 +08003349 /*
3350 * Unlike hash and equality test, this function doesn't ignore
3351 * ->no_numa as it is used for both pool and wq attrs. Instead,
3352 * get_unbound_pool() explicitly clears ->no_numa after copying.
3353 */
3354 to->no_numa = from->no_numa;
Tejun Heo29c91e92013-03-12 11:30:03 -07003355}
3356
Tejun Heo29c91e92013-03-12 11:30:03 -07003357/* hash value of the content of @attr */
3358static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
3359{
3360 u32 hash = 0;
3361
3362 hash = jhash_1word(attrs->nice, hash);
Tejun Heo13e2e552013-04-01 11:23:31 -07003363 hash = jhash(cpumask_bits(attrs->cpumask),
3364 BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
Tejun Heo29c91e92013-03-12 11:30:03 -07003365 return hash;
3366}
3367
3368/* content equality test */
3369static bool wqattrs_equal(const struct workqueue_attrs *a,
3370 const struct workqueue_attrs *b)
3371{
3372 if (a->nice != b->nice)
3373 return false;
3374 if (!cpumask_equal(a->cpumask, b->cpumask))
3375 return false;
3376 return true;
3377}
3378
Tejun Heo7a4e3442013-03-12 11:30:00 -07003379/**
3380 * init_worker_pool - initialize a newly zalloc'd worker_pool
3381 * @pool: worker_pool to initialize
3382 *
3383 * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
Yacine Belkadid185af32013-07-31 14:59:24 -07003384 *
3385 * Return: 0 on success, -errno on failure. Even on failure, all fields
Tejun Heo29c91e92013-03-12 11:30:03 -07003386 * inside @pool proper are initialized and put_unbound_pool() can be called
3387 * on @pool safely to release it.
Tejun Heo7a4e3442013-03-12 11:30:00 -07003388 */
3389static int init_worker_pool(struct worker_pool *pool)
Tejun Heo4e1a1f92013-03-12 11:30:00 -07003390{
3391 spin_lock_init(&pool->lock);
Tejun Heo29c91e92013-03-12 11:30:03 -07003392 pool->id = -1;
3393 pool->cpu = -1;
Tejun Heof3f90ad2013-04-01 11:23:34 -07003394 pool->node = NUMA_NO_NODE;
Tejun Heo4e1a1f92013-03-12 11:30:00 -07003395 pool->flags |= POOL_DISASSOCIATED;
3396 INIT_LIST_HEAD(&pool->worklist);
3397 INIT_LIST_HEAD(&pool->idle_list);
3398 hash_init(pool->busy_hash);
3399
3400 init_timer_deferrable(&pool->idle_timer);
3401 pool->idle_timer.function = idle_worker_timeout;
3402 pool->idle_timer.data = (unsigned long)pool;
3403
3404 setup_timer(&pool->mayday_timer, pool_mayday_timeout,
3405 (unsigned long)pool);
3406
3407 mutex_init(&pool->manager_arb);
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08003408 mutex_init(&pool->attach_mutex);
Lai Jiangshanda028462014-05-20 17:46:31 +08003409 INIT_LIST_HEAD(&pool->workers);
Tejun Heo7a4e3442013-03-12 11:30:00 -07003410
Lai Jiangshan7cda9aa2014-05-20 17:46:32 +08003411 ida_init(&pool->worker_ida);
Tejun Heo29c91e92013-03-12 11:30:03 -07003412 INIT_HLIST_NODE(&pool->hash_node);
3413 pool->refcnt = 1;
3414
3415 /* shouldn't fail above this point */
Tejun Heo7a4e3442013-03-12 11:30:00 -07003416 pool->attrs = alloc_workqueue_attrs(GFP_KERNEL);
3417 if (!pool->attrs)
3418 return -ENOMEM;
3419 return 0;
Tejun Heo4e1a1f92013-03-12 11:30:00 -07003420}
3421
Tejun Heo29c91e92013-03-12 11:30:03 -07003422static void rcu_free_pool(struct rcu_head *rcu)
3423{
3424 struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
3425
Lai Jiangshan7cda9aa2014-05-20 17:46:32 +08003426 ida_destroy(&pool->worker_ida);
Tejun Heo29c91e92013-03-12 11:30:03 -07003427 free_workqueue_attrs(pool->attrs);
3428 kfree(pool);
3429}
3430
3431/**
3432 * put_unbound_pool - put a worker_pool
3433 * @pool: worker_pool to put
3434 *
3435 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
Tejun Heoc5aa87b2013-03-13 16:51:36 -07003436 * safe manner. get_unbound_pool() calls this function on its failure path
3437 * and this function should be able to release pools which went through,
3438 * successfully or not, init_worker_pool().
Tejun Heoa892cac2013-04-01 11:23:32 -07003439 *
3440 * Should be called with wq_pool_mutex held.
Tejun Heo29c91e92013-03-12 11:30:03 -07003441 */
3442static void put_unbound_pool(struct worker_pool *pool)
3443{
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08003444 DECLARE_COMPLETION_ONSTACK(detach_completion);
Tejun Heo29c91e92013-03-12 11:30:03 -07003445 struct worker *worker;
3446
Tejun Heoa892cac2013-04-01 11:23:32 -07003447 lockdep_assert_held(&wq_pool_mutex);
3448
3449 if (--pool->refcnt)
Tejun Heo29c91e92013-03-12 11:30:03 -07003450 return;
Tejun Heo29c91e92013-03-12 11:30:03 -07003451
3452 /* sanity checks */
Lai Jiangshan61d0fbb2014-06-03 15:31:45 +08003453 if (WARN_ON(!(pool->cpu < 0)) ||
Tejun Heoa892cac2013-04-01 11:23:32 -07003454 WARN_ON(!list_empty(&pool->worklist)))
Tejun Heo29c91e92013-03-12 11:30:03 -07003455 return;
Tejun Heo29c91e92013-03-12 11:30:03 -07003456
3457 /* release id and unhash */
3458 if (pool->id >= 0)
3459 idr_remove(&worker_pool_idr, pool->id);
3460 hash_del(&pool->hash_node);
3461
Tejun Heoc5aa87b2013-03-13 16:51:36 -07003462 /*
3463 * Become the manager and destroy all workers. Grabbing
3464 * manager_arb prevents @pool's workers from blocking on
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08003465 * attach_mutex.
Tejun Heoc5aa87b2013-03-13 16:51:36 -07003466 */
Tejun Heo29c91e92013-03-12 11:30:03 -07003467 mutex_lock(&pool->manager_arb);
Tejun Heo29c91e92013-03-12 11:30:03 -07003468
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08003469 spin_lock_irq(&pool->lock);
Lai Jiangshan1037de32014-05-22 16:44:07 +08003470 while ((worker = first_idle_worker(pool)))
Tejun Heo29c91e92013-03-12 11:30:03 -07003471 destroy_worker(worker);
3472 WARN_ON(pool->nr_workers || pool->nr_idle);
Tejun Heo29c91e92013-03-12 11:30:03 -07003473 spin_unlock_irq(&pool->lock);
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08003474
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08003475 mutex_lock(&pool->attach_mutex);
Lai Jiangshanda028462014-05-20 17:46:31 +08003476 if (!list_empty(&pool->workers))
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08003477 pool->detach_completion = &detach_completion;
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08003478 mutex_unlock(&pool->attach_mutex);
Lai Jiangshan60f5a4b2014-05-20 17:46:29 +08003479
3480 if (pool->detach_completion)
3481 wait_for_completion(pool->detach_completion);
3482
Tejun Heo29c91e92013-03-12 11:30:03 -07003483 mutex_unlock(&pool->manager_arb);
3484
3485 /* shut down the timers */
3486 del_timer_sync(&pool->idle_timer);
3487 del_timer_sync(&pool->mayday_timer);
3488
3489 /* sched-RCU protected to allow dereferences from get_work_pool() */
3490 call_rcu_sched(&pool->rcu, rcu_free_pool);
3491}
3492
3493/**
3494 * get_unbound_pool - get a worker_pool with the specified attributes
3495 * @attrs: the attributes of the worker_pool to get
3496 *
3497 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3498 * reference count and return it. If there already is a matching
3499 * worker_pool, it will be used; otherwise, this function attempts to
Yacine Belkadid185af32013-07-31 14:59:24 -07003500 * create a new one.
Tejun Heoa892cac2013-04-01 11:23:32 -07003501 *
3502 * Should be called with wq_pool_mutex held.
Yacine Belkadid185af32013-07-31 14:59:24 -07003503 *
3504 * Return: On success, a worker_pool with the same attributes as @attrs.
3505 * On failure, %NULL.
Tejun Heo29c91e92013-03-12 11:30:03 -07003506 */
3507static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
3508{
Tejun Heo29c91e92013-03-12 11:30:03 -07003509 u32 hash = wqattrs_hash(attrs);
3510 struct worker_pool *pool;
Tejun Heof3f90ad2013-04-01 11:23:34 -07003511 int node;
Tejun Heo29c91e92013-03-12 11:30:03 -07003512
Tejun Heoa892cac2013-04-01 11:23:32 -07003513 lockdep_assert_held(&wq_pool_mutex);
Tejun Heo29c91e92013-03-12 11:30:03 -07003514
3515 /* do we already have a matching pool? */
Tejun Heo29c91e92013-03-12 11:30:03 -07003516 hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
3517 if (wqattrs_equal(pool->attrs, attrs)) {
3518 pool->refcnt++;
3519 goto out_unlock;
3520 }
3521 }
Tejun Heo29c91e92013-03-12 11:30:03 -07003522
3523 /* nope, create a new one */
3524 pool = kzalloc(sizeof(*pool), GFP_KERNEL);
3525 if (!pool || init_worker_pool(pool) < 0)
3526 goto fail;
3527
Tejun Heo8864b4e2013-03-12 11:30:04 -07003528 lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
Tejun Heo29c91e92013-03-12 11:30:03 -07003529 copy_workqueue_attrs(pool->attrs, attrs);
3530
Shaohua Li2865a8f2013-08-01 09:56:36 +08003531 /*
3532 * no_numa isn't a worker_pool attribute, always clear it. See
3533 * 'struct workqueue_attrs' comments for detail.
3534 */
3535 pool->attrs->no_numa = false;
3536
Tejun Heof3f90ad2013-04-01 11:23:34 -07003537 /* if cpumask is contained inside a NUMA node, we belong to that node */
3538 if (wq_numa_enabled) {
3539 for_each_node(node) {
3540 if (cpumask_subset(pool->attrs->cpumask,
3541 wq_numa_possible_cpumask[node])) {
3542 pool->node = node;
3543 break;
3544 }
3545 }
3546 }
3547
Tejun Heo29c91e92013-03-12 11:30:03 -07003548 if (worker_pool_assign_id(pool) < 0)
3549 goto fail;
3550
3551 /* create and start the initial worker */
Tejun Heoebf44d12013-03-13 19:47:39 -07003552 if (create_and_start_worker(pool) < 0)
Tejun Heo29c91e92013-03-12 11:30:03 -07003553 goto fail;
3554
Tejun Heo29c91e92013-03-12 11:30:03 -07003555 /* install */
Tejun Heo29c91e92013-03-12 11:30:03 -07003556 hash_add(unbound_pool_hash, &pool->hash_node, hash);
3557out_unlock:
Tejun Heo29c91e92013-03-12 11:30:03 -07003558 return pool;
3559fail:
Tejun Heo29c91e92013-03-12 11:30:03 -07003560 if (pool)
3561 put_unbound_pool(pool);
3562 return NULL;
3563}
3564
Tejun Heo8864b4e2013-03-12 11:30:04 -07003565static void rcu_free_pwq(struct rcu_head *rcu)
3566{
3567 kmem_cache_free(pwq_cache,
3568 container_of(rcu, struct pool_workqueue, rcu));
3569}
3570
3571/*
3572 * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3573 * and needs to be destroyed.
3574 */
3575static void pwq_unbound_release_workfn(struct work_struct *work)
3576{
3577 struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
3578 unbound_release_work);
3579 struct workqueue_struct *wq = pwq->wq;
3580 struct worker_pool *pool = pwq->pool;
Tejun Heobc0caf02013-04-01 11:23:31 -07003581 bool is_last;
Tejun Heo8864b4e2013-03-12 11:30:04 -07003582
3583 if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
3584 return;
3585
Tejun Heo75ccf592013-03-12 11:30:04 -07003586 /*
Lai Jiangshan3c25a552013-03-25 16:57:17 -07003587 * Unlink @pwq. Synchronization against wq->mutex isn't strictly
Tejun Heo75ccf592013-03-12 11:30:04 -07003588 * necessary on release but do it anyway. It's easier to verify
3589 * and consistent with the linking path.
3590 */
Lai Jiangshan3c25a552013-03-25 16:57:17 -07003591 mutex_lock(&wq->mutex);
Tejun Heo8864b4e2013-03-12 11:30:04 -07003592 list_del_rcu(&pwq->pwqs_node);
Tejun Heobc0caf02013-04-01 11:23:31 -07003593 is_last = list_empty(&wq->pwqs);
Lai Jiangshan3c25a552013-03-25 16:57:17 -07003594 mutex_unlock(&wq->mutex);
Tejun Heo8864b4e2013-03-12 11:30:04 -07003595
Tejun Heoa892cac2013-04-01 11:23:32 -07003596 mutex_lock(&wq_pool_mutex);
Tejun Heo8864b4e2013-03-12 11:30:04 -07003597 put_unbound_pool(pool);
Tejun Heoa892cac2013-04-01 11:23:32 -07003598 mutex_unlock(&wq_pool_mutex);
3599
Tejun Heo8864b4e2013-03-12 11:30:04 -07003600 call_rcu_sched(&pwq->rcu, rcu_free_pwq);
3601
3602 /*
3603 * If we're the last pwq going away, @wq is already dead and no one
3604 * is gonna access it anymore. Free it.
3605 */
Tejun Heo6029a912013-04-01 11:23:34 -07003606 if (is_last) {
3607 free_workqueue_attrs(wq->unbound_attrs);
Tejun Heo8864b4e2013-03-12 11:30:04 -07003608 kfree(wq);
Tejun Heo6029a912013-04-01 11:23:34 -07003609 }
Tejun Heo8864b4e2013-03-12 11:30:04 -07003610}
3611
Tejun Heo0fbd95a2013-03-13 16:51:35 -07003612/**
Tejun Heo699ce092013-03-13 16:51:35 -07003613 * pwq_adjust_max_active - update a pwq's max_active to the current setting
Tejun Heo0fbd95a2013-03-13 16:51:35 -07003614 * @pwq: target pool_workqueue
Tejun Heo0fbd95a2013-03-13 16:51:35 -07003615 *
Tejun Heo699ce092013-03-13 16:51:35 -07003616 * If @pwq isn't freezing, set @pwq->max_active to the associated
3617 * workqueue's saved_max_active and activate delayed work items
3618 * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
Tejun Heo0fbd95a2013-03-13 16:51:35 -07003619 */
Tejun Heo699ce092013-03-13 16:51:35 -07003620static void pwq_adjust_max_active(struct pool_workqueue *pwq)
Tejun Heo0fbd95a2013-03-13 16:51:35 -07003621{
Tejun Heo699ce092013-03-13 16:51:35 -07003622 struct workqueue_struct *wq = pwq->wq;
3623 bool freezable = wq->flags & WQ_FREEZABLE;
Tejun Heo0fbd95a2013-03-13 16:51:35 -07003624
Tejun Heo699ce092013-03-13 16:51:35 -07003625 /* for @wq->saved_max_active */
Lai Jiangshana357fc02013-03-25 16:57:19 -07003626 lockdep_assert_held(&wq->mutex);
Tejun Heo699ce092013-03-13 16:51:35 -07003627
3628 /* fast exit for non-freezable wqs */
3629 if (!freezable && pwq->max_active == wq->saved_max_active)
3630 return;
3631
Lai Jiangshana357fc02013-03-25 16:57:19 -07003632 spin_lock_irq(&pwq->pool->lock);
Tejun Heo699ce092013-03-13 16:51:35 -07003633
Lai Jiangshan74b414e2014-05-22 19:01:16 +08003634 /*
3635 * During [un]freezing, the caller is responsible for ensuring that
3636 * this function is called at least once after @workqueue_freezing
3637 * is updated and visible.
3638 */
3639 if (!freezable || !workqueue_freezing) {
Tejun Heo699ce092013-03-13 16:51:35 -07003640 pwq->max_active = wq->saved_max_active;
3641
3642 while (!list_empty(&pwq->delayed_works) &&
3643 pwq->nr_active < pwq->max_active)
3644 pwq_activate_first_delayed(pwq);
Lai Jiangshan951a0782013-03-20 10:52:30 -07003645
3646 /*
3647 * Need to kick a worker after thawed or an unbound wq's
3648 * max_active is bumped. It's a slow path. Do it always.
3649 */
3650 wake_up_worker(pwq->pool);
Tejun Heo699ce092013-03-13 16:51:35 -07003651 } else {
3652 pwq->max_active = 0;
3653 }
3654
Lai Jiangshana357fc02013-03-25 16:57:19 -07003655 spin_unlock_irq(&pwq->pool->lock);
Tejun Heo0fbd95a2013-03-13 16:51:35 -07003656}
3657
Tejun Heoe50aba92013-04-01 11:23:35 -07003658/* initialize newly alloced @pwq which is associated with @wq and @pool */
Tejun Heof147f292013-04-01 11:23:35 -07003659static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
3660 struct worker_pool *pool)
Tejun Heod2c1d402013-03-12 11:30:04 -07003661{
3662 BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
3663
Tejun Heoe50aba92013-04-01 11:23:35 -07003664 memset(pwq, 0, sizeof(*pwq));
3665
Tejun Heod2c1d402013-03-12 11:30:04 -07003666 pwq->pool = pool;
3667 pwq->wq = wq;
3668 pwq->flush_color = -1;
Tejun Heo8864b4e2013-03-12 11:30:04 -07003669 pwq->refcnt = 1;
Tejun Heod2c1d402013-03-12 11:30:04 -07003670 INIT_LIST_HEAD(&pwq->delayed_works);
Tejun Heo1befcf32013-04-01 11:23:35 -07003671 INIT_LIST_HEAD(&pwq->pwqs_node);
Tejun Heod2c1d402013-03-12 11:30:04 -07003672 INIT_LIST_HEAD(&pwq->mayday_node);
Tejun Heo8864b4e2013-03-12 11:30:04 -07003673 INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
Tejun Heof147f292013-04-01 11:23:35 -07003674}
Tejun Heod2c1d402013-03-12 11:30:04 -07003675
Tejun Heof147f292013-04-01 11:23:35 -07003676/* sync @pwq with the current state of its associated wq and link it */
Tejun Heo1befcf32013-04-01 11:23:35 -07003677static void link_pwq(struct pool_workqueue *pwq)
Tejun Heof147f292013-04-01 11:23:35 -07003678{
3679 struct workqueue_struct *wq = pwq->wq;
3680
3681 lockdep_assert_held(&wq->mutex);
Tejun Heo75ccf592013-03-12 11:30:04 -07003682
Tejun Heo1befcf32013-04-01 11:23:35 -07003683 /* may be called multiple times, ignore if already linked */
3684 if (!list_empty(&pwq->pwqs_node))
3685 return;
3686
Tejun Heo983ca252013-03-13 16:51:35 -07003687 /*
3688 * Set the matching work_color. This is synchronized with
Lai Jiangshan3c25a552013-03-25 16:57:17 -07003689 * wq->mutex to avoid confusing flush_workqueue().
Tejun Heo983ca252013-03-13 16:51:35 -07003690 */
Tejun Heo75ccf592013-03-12 11:30:04 -07003691 pwq->work_color = wq->work_color;
Tejun Heo983ca252013-03-13 16:51:35 -07003692
3693 /* sync max_active to the current setting */
3694 pwq_adjust_max_active(pwq);
3695
3696 /* link in @pwq */
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07003697 list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
Tejun Heof147f292013-04-01 11:23:35 -07003698}
Lai Jiangshana357fc02013-03-25 16:57:19 -07003699
Tejun Heof147f292013-04-01 11:23:35 -07003700/* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3701static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq,
3702 const struct workqueue_attrs *attrs)
3703{
3704 struct worker_pool *pool;
3705 struct pool_workqueue *pwq;
3706
3707 lockdep_assert_held(&wq_pool_mutex);
3708
3709 pool = get_unbound_pool(attrs);
3710 if (!pool)
3711 return NULL;
3712
Tejun Heoe50aba92013-04-01 11:23:35 -07003713 pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
Tejun Heof147f292013-04-01 11:23:35 -07003714 if (!pwq) {
3715 put_unbound_pool(pool);
3716 return NULL;
Tejun Heodf2d5ae2013-04-01 11:23:35 -07003717 }
Tejun Heo6029a912013-04-01 11:23:34 -07003718
Tejun Heof147f292013-04-01 11:23:35 -07003719 init_pwq(pwq, wq, pool);
3720 return pwq;
Tejun Heod2c1d402013-03-12 11:30:04 -07003721}
3722
Tejun Heo4c16bd32013-04-01 11:23:36 -07003723/* undo alloc_unbound_pwq(), used only in the error path */
3724static void free_unbound_pwq(struct pool_workqueue *pwq)
3725{
3726 lockdep_assert_held(&wq_pool_mutex);
3727
3728 if (pwq) {
3729 put_unbound_pool(pwq->pool);
Wei Yongjuncece95d2013-04-09 14:29:11 +08003730 kmem_cache_free(pwq_cache, pwq);
Tejun Heo4c16bd32013-04-01 11:23:36 -07003731 }
3732}
3733
3734/**
3735 * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node
3736 * @attrs: the wq_attrs of interest
3737 * @node: the target NUMA node
3738 * @cpu_going_down: if >= 0, the CPU to consider as offline
3739 * @cpumask: outarg, the resulting cpumask
3740 *
3741 * Calculate the cpumask a workqueue with @attrs should use on @node. If
3742 * @cpu_going_down is >= 0, that cpu is considered offline during
Yacine Belkadid185af32013-07-31 14:59:24 -07003743 * calculation. The result is stored in @cpumask.
Tejun Heo4c16bd32013-04-01 11:23:36 -07003744 *
3745 * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3746 * enabled and @node has online CPUs requested by @attrs, the returned
3747 * cpumask is the intersection of the possible CPUs of @node and
3748 * @attrs->cpumask.
3749 *
3750 * The caller is responsible for ensuring that the cpumask of @node stays
3751 * stable.
Yacine Belkadid185af32013-07-31 14:59:24 -07003752 *
3753 * Return: %true if the resulting @cpumask is different from @attrs->cpumask,
3754 * %false if equal.
Tejun Heo4c16bd32013-04-01 11:23:36 -07003755 */
3756static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
3757 int cpu_going_down, cpumask_t *cpumask)
3758{
Tejun Heod55262c2013-04-01 11:23:38 -07003759 if (!wq_numa_enabled || attrs->no_numa)
Tejun Heo4c16bd32013-04-01 11:23:36 -07003760 goto use_dfl;
3761
3762 /* does @node have any online CPUs @attrs wants? */
3763 cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask);
3764 if (cpu_going_down >= 0)
3765 cpumask_clear_cpu(cpu_going_down, cpumask);
3766
3767 if (cpumask_empty(cpumask))
3768 goto use_dfl;
3769
3770 /* yeap, return possible CPUs in @node that @attrs wants */
3771 cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
3772 return !cpumask_equal(cpumask, attrs->cpumask);
3773
3774use_dfl:
3775 cpumask_copy(cpumask, attrs->cpumask);
3776 return false;
3777}
3778
Tejun Heo1befcf32013-04-01 11:23:35 -07003779/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3780static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
3781 int node,
3782 struct pool_workqueue *pwq)
3783{
3784 struct pool_workqueue *old_pwq;
3785
3786 lockdep_assert_held(&wq->mutex);
3787
3788 /* link_pwq() can handle duplicate calls */
3789 link_pwq(pwq);
3790
3791 old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
3792 rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
3793 return old_pwq;
3794}
3795
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07003796/**
3797 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
3798 * @wq: the target workqueue
3799 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
3800 *
Tejun Heo4c16bd32013-04-01 11:23:36 -07003801 * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
3802 * machines, this function maps a separate pwq to each NUMA node with
3803 * possibles CPUs in @attrs->cpumask so that work items are affine to the
3804 * NUMA node it was issued on. Older pwqs are released as in-flight work
3805 * items finish. Note that a work item which repeatedly requeues itself
3806 * back-to-back will stay on its current pwq.
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07003807 *
Yacine Belkadid185af32013-07-31 14:59:24 -07003808 * Performs GFP_KERNEL allocations.
3809 *
3810 * Return: 0 on success and -errno on failure.
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07003811 */
3812int apply_workqueue_attrs(struct workqueue_struct *wq,
3813 const struct workqueue_attrs *attrs)
3814{
Tejun Heo4c16bd32013-04-01 11:23:36 -07003815 struct workqueue_attrs *new_attrs, *tmp_attrs;
3816 struct pool_workqueue **pwq_tbl, *dfl_pwq;
Tejun Heof147f292013-04-01 11:23:35 -07003817 int node, ret;
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07003818
Tejun Heo8719dce2013-03-12 11:30:04 -07003819 /* only unbound workqueues can change attributes */
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07003820 if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
3821 return -EINVAL;
3822
Tejun Heo8719dce2013-03-12 11:30:04 -07003823 /* creating multiple pwqs breaks ordering guarantee */
3824 if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
3825 return -EINVAL;
3826
Tejun Heo4c16bd32013-04-01 11:23:36 -07003827 pwq_tbl = kzalloc(wq_numa_tbl_len * sizeof(pwq_tbl[0]), GFP_KERNEL);
Tejun Heo13e2e552013-04-01 11:23:31 -07003828 new_attrs = alloc_workqueue_attrs(GFP_KERNEL);
Tejun Heo4c16bd32013-04-01 11:23:36 -07003829 tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL);
3830 if (!pwq_tbl || !new_attrs || !tmp_attrs)
Tejun Heo13e2e552013-04-01 11:23:31 -07003831 goto enomem;
3832
Tejun Heo4c16bd32013-04-01 11:23:36 -07003833 /* make a copy of @attrs and sanitize it */
Tejun Heo13e2e552013-04-01 11:23:31 -07003834 copy_workqueue_attrs(new_attrs, attrs);
3835 cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
3836
Tejun Heo4c16bd32013-04-01 11:23:36 -07003837 /*
3838 * We may create multiple pwqs with differing cpumasks. Make a
3839 * copy of @new_attrs which will be modified and used to obtain
3840 * pools.
3841 */
3842 copy_workqueue_attrs(tmp_attrs, new_attrs);
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07003843
Tejun Heo4c16bd32013-04-01 11:23:36 -07003844 /*
3845 * CPUs should stay stable across pwq creations and installations.
3846 * Pin CPUs, determine the target cpumask for each node and create
3847 * pwqs accordingly.
3848 */
3849 get_online_cpus();
3850
3851 mutex_lock(&wq_pool_mutex);
3852
3853 /*
3854 * If something goes wrong during CPU up/down, we'll fall back to
3855 * the default pwq covering whole @attrs->cpumask. Always create
3856 * it even if we don't use it immediately.
3857 */
3858 dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
3859 if (!dfl_pwq)
3860 goto enomem_pwq;
3861
3862 for_each_node(node) {
3863 if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) {
3864 pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
3865 if (!pwq_tbl[node])
3866 goto enomem_pwq;
3867 } else {
3868 dfl_pwq->refcnt++;
3869 pwq_tbl[node] = dfl_pwq;
3870 }
3871 }
3872
3873 mutex_unlock(&wq_pool_mutex);
3874
3875 /* all pwqs have been created successfully, let's install'em */
Tejun Heof147f292013-04-01 11:23:35 -07003876 mutex_lock(&wq->mutex);
3877
Tejun Heof147f292013-04-01 11:23:35 -07003878 copy_workqueue_attrs(wq->unbound_attrs, new_attrs);
Tejun Heo4c16bd32013-04-01 11:23:36 -07003879
3880 /* save the previous pwq and install the new one */
Tejun Heof147f292013-04-01 11:23:35 -07003881 for_each_node(node)
Tejun Heo4c16bd32013-04-01 11:23:36 -07003882 pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]);
3883
3884 /* @dfl_pwq might not have been used, ensure it's linked */
3885 link_pwq(dfl_pwq);
3886 swap(wq->dfl_pwq, dfl_pwq);
Tejun Heof147f292013-04-01 11:23:35 -07003887
3888 mutex_unlock(&wq->mutex);
3889
Tejun Heo4c16bd32013-04-01 11:23:36 -07003890 /* put the old pwqs */
3891 for_each_node(node)
3892 put_pwq_unlocked(pwq_tbl[node]);
3893 put_pwq_unlocked(dfl_pwq);
3894
3895 put_online_cpus();
Tejun Heo48621252013-04-01 11:23:31 -07003896 ret = 0;
3897 /* fall through */
3898out_free:
Tejun Heo4c16bd32013-04-01 11:23:36 -07003899 free_workqueue_attrs(tmp_attrs);
Tejun Heo48621252013-04-01 11:23:31 -07003900 free_workqueue_attrs(new_attrs);
Tejun Heo4c16bd32013-04-01 11:23:36 -07003901 kfree(pwq_tbl);
Tejun Heo48621252013-04-01 11:23:31 -07003902 return ret;
Tejun Heo13e2e552013-04-01 11:23:31 -07003903
Tejun Heo4c16bd32013-04-01 11:23:36 -07003904enomem_pwq:
3905 free_unbound_pwq(dfl_pwq);
3906 for_each_node(node)
3907 if (pwq_tbl && pwq_tbl[node] != dfl_pwq)
3908 free_unbound_pwq(pwq_tbl[node]);
3909 mutex_unlock(&wq_pool_mutex);
3910 put_online_cpus();
Tejun Heo13e2e552013-04-01 11:23:31 -07003911enomem:
Tejun Heo48621252013-04-01 11:23:31 -07003912 ret = -ENOMEM;
3913 goto out_free;
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07003914}
3915
Tejun Heo4c16bd32013-04-01 11:23:36 -07003916/**
3917 * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
3918 * @wq: the target workqueue
3919 * @cpu: the CPU coming up or going down
3920 * @online: whether @cpu is coming up or going down
3921 *
3922 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
3923 * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
3924 * @wq accordingly.
3925 *
3926 * If NUMA affinity can't be adjusted due to memory allocation failure, it
3927 * falls back to @wq->dfl_pwq which may not be optimal but is always
3928 * correct.
3929 *
3930 * Note that when the last allowed CPU of a NUMA node goes offline for a
3931 * workqueue with a cpumask spanning multiple nodes, the workers which were
3932 * already executing the work items for the workqueue will lose their CPU
3933 * affinity and may execute on any CPU. This is similar to how per-cpu
3934 * workqueues behave on CPU_DOWN. If a workqueue user wants strict
3935 * affinity, it's the user's responsibility to flush the work item from
3936 * CPU_DOWN_PREPARE.
3937 */
3938static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
3939 bool online)
3940{
3941 int node = cpu_to_node(cpu);
3942 int cpu_off = online ? -1 : cpu;
3943 struct pool_workqueue *old_pwq = NULL, *pwq;
3944 struct workqueue_attrs *target_attrs;
3945 cpumask_t *cpumask;
3946
3947 lockdep_assert_held(&wq_pool_mutex);
3948
3949 if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND))
3950 return;
3951
3952 /*
3953 * We don't wanna alloc/free wq_attrs for each wq for each CPU.
3954 * Let's use a preallocated one. The following buf is protected by
3955 * CPU hotplug exclusion.
3956 */
3957 target_attrs = wq_update_unbound_numa_attrs_buf;
3958 cpumask = target_attrs->cpumask;
3959
3960 mutex_lock(&wq->mutex);
Tejun Heod55262c2013-04-01 11:23:38 -07003961 if (wq->unbound_attrs->no_numa)
3962 goto out_unlock;
Tejun Heo4c16bd32013-04-01 11:23:36 -07003963
3964 copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
3965 pwq = unbound_pwq_by_node(wq, node);
3966
3967 /*
3968 * Let's determine what needs to be done. If the target cpumask is
3969 * different from wq's, we need to compare it to @pwq's and create
3970 * a new one if they don't match. If the target cpumask equals
Daeseok Youn534a3fb2014-04-18 09:08:14 +09003971 * wq's, the default pwq should be used.
Tejun Heo4c16bd32013-04-01 11:23:36 -07003972 */
3973 if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) {
3974 if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
3975 goto out_unlock;
3976 } else {
Daeseok Youn534a3fb2014-04-18 09:08:14 +09003977 goto use_dfl_pwq;
Tejun Heo4c16bd32013-04-01 11:23:36 -07003978 }
3979
3980 mutex_unlock(&wq->mutex);
3981
3982 /* create a new pwq */
3983 pwq = alloc_unbound_pwq(wq, target_attrs);
3984 if (!pwq) {
Fabian Frederick2d916032014-05-12 13:59:35 -04003985 pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
3986 wq->name);
Daeseok Youn77f300b2014-04-16 14:32:29 +09003987 mutex_lock(&wq->mutex);
3988 goto use_dfl_pwq;
Tejun Heo4c16bd32013-04-01 11:23:36 -07003989 }
3990
3991 /*
3992 * Install the new pwq. As this function is called only from CPU
3993 * hotplug callbacks and applying a new attrs is wrapped with
3994 * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
3995 * inbetween.
3996 */
3997 mutex_lock(&wq->mutex);
3998 old_pwq = numa_pwq_tbl_install(wq, node, pwq);
3999 goto out_unlock;
4000
4001use_dfl_pwq:
4002 spin_lock_irq(&wq->dfl_pwq->pool->lock);
4003 get_pwq(wq->dfl_pwq);
4004 spin_unlock_irq(&wq->dfl_pwq->pool->lock);
4005 old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
4006out_unlock:
4007 mutex_unlock(&wq->mutex);
4008 put_pwq_unlocked(old_pwq);
4009}
4010
Tejun Heo30cdf242013-03-12 11:29:57 -07004011static int alloc_and_link_pwqs(struct workqueue_struct *wq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004012{
Tejun Heo49e3cf42013-03-12 11:29:58 -07004013 bool highpri = wq->flags & WQ_HIGHPRI;
Tejun Heo8a2b7532013-09-05 12:30:04 -04004014 int cpu, ret;
Frederic Weisbeckere1d8aa92009-01-12 23:15:46 +01004015
Tejun Heo30cdf242013-03-12 11:29:57 -07004016 if (!(wq->flags & WQ_UNBOUND)) {
Tejun Heo420c0dd2013-03-12 11:29:59 -07004017 wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
4018 if (!wq->cpu_pwqs)
Tejun Heo30cdf242013-03-12 11:29:57 -07004019 return -ENOMEM;
4020
4021 for_each_possible_cpu(cpu) {
Tejun Heo7fb98ea2013-03-12 11:30:00 -07004022 struct pool_workqueue *pwq =
4023 per_cpu_ptr(wq->cpu_pwqs, cpu);
Tejun Heo7a62c2c2013-03-12 11:30:03 -07004024 struct worker_pool *cpu_pools =
Tejun Heof02ae732013-03-12 11:30:03 -07004025 per_cpu(cpu_worker_pools, cpu);
Tejun Heo30cdf242013-03-12 11:29:57 -07004026
Tejun Heof147f292013-04-01 11:23:35 -07004027 init_pwq(pwq, wq, &cpu_pools[highpri]);
4028
4029 mutex_lock(&wq->mutex);
Tejun Heo1befcf32013-04-01 11:23:35 -07004030 link_pwq(pwq);
Tejun Heof147f292013-04-01 11:23:35 -07004031 mutex_unlock(&wq->mutex);
Tejun Heo30cdf242013-03-12 11:29:57 -07004032 }
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07004033 return 0;
Tejun Heo8a2b7532013-09-05 12:30:04 -04004034 } else if (wq->flags & __WQ_ORDERED) {
4035 ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
4036 /* there should only be single pwq for ordering guarantee */
4037 WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node ||
4038 wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
4039 "ordering guarantee broken for workqueue %s\n", wq->name);
4040 return ret;
Tejun Heo30cdf242013-03-12 11:29:57 -07004041 } else {
Tejun Heo9e8cd2f2013-03-12 11:30:04 -07004042 return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
Tejun Heo30cdf242013-03-12 11:29:57 -07004043 }
Oleg Nesterov3af244332007-05-09 02:34:09 -07004044}
4045
Tejun Heof3421792010-07-02 10:03:51 +02004046static int wq_clamp_max_active(int max_active, unsigned int flags,
4047 const char *name)
Tejun Heob71ab8c2010-06-29 10:07:14 +02004048{
Tejun Heof3421792010-07-02 10:03:51 +02004049 int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
4050
4051 if (max_active < 1 || max_active > lim)
Valentin Ilie044c7822012-08-19 00:52:42 +03004052 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
4053 max_active, name, 1, lim);
Tejun Heob71ab8c2010-06-29 10:07:14 +02004054
Tejun Heof3421792010-07-02 10:03:51 +02004055 return clamp_val(max_active, 1, lim);
Tejun Heob71ab8c2010-06-29 10:07:14 +02004056}
4057
Tejun Heob196be82012-01-10 15:11:35 -08004058struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
Tejun Heod320c032010-06-29 10:07:14 +02004059 unsigned int flags,
4060 int max_active,
4061 struct lock_class_key *key,
Tejun Heob196be82012-01-10 15:11:35 -08004062 const char *lock_name, ...)
Oleg Nesterov3af244332007-05-09 02:34:09 -07004063{
Tejun Heodf2d5ae2013-04-01 11:23:35 -07004064 size_t tbl_size = 0;
Tejun Heoecf68812013-04-01 11:23:34 -07004065 va_list args;
Oleg Nesterov3af244332007-05-09 02:34:09 -07004066 struct workqueue_struct *wq;
Tejun Heo49e3cf42013-03-12 11:29:58 -07004067 struct pool_workqueue *pwq;
Tejun Heob196be82012-01-10 15:11:35 -08004068
Viresh Kumarcee22a12013-04-08 16:45:40 +05304069 /* see the comment above the definition of WQ_POWER_EFFICIENT */
4070 if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
4071 flags |= WQ_UNBOUND;
4072
Tejun Heoecf68812013-04-01 11:23:34 -07004073 /* allocate wq and format name */
Tejun Heodf2d5ae2013-04-01 11:23:35 -07004074 if (flags & WQ_UNBOUND)
4075 tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]);
4076
4077 wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL);
Tejun Heob196be82012-01-10 15:11:35 -08004078 if (!wq)
Tejun Heod2c1d402013-03-12 11:30:04 -07004079 return NULL;
Tejun Heob196be82012-01-10 15:11:35 -08004080
Tejun Heo6029a912013-04-01 11:23:34 -07004081 if (flags & WQ_UNBOUND) {
4082 wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL);
4083 if (!wq->unbound_attrs)
4084 goto err_free_wq;
4085 }
4086
Tejun Heoecf68812013-04-01 11:23:34 -07004087 va_start(args, lock_name);
4088 vsnprintf(wq->name, sizeof(wq->name), fmt, args);
Tejun Heob196be82012-01-10 15:11:35 -08004089 va_end(args);
Oleg Nesterov3af244332007-05-09 02:34:09 -07004090
Tejun Heod320c032010-06-29 10:07:14 +02004091 max_active = max_active ?: WQ_DFL_ACTIVE;
Tejun Heob196be82012-01-10 15:11:35 -08004092 max_active = wq_clamp_max_active(max_active, flags, wq->name);
Oleg Nesterov3af244332007-05-09 02:34:09 -07004093
Tejun Heob196be82012-01-10 15:11:35 -08004094 /* init wq */
Tejun Heo97e37d72010-06-29 10:07:10 +02004095 wq->flags = flags;
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004096 wq->saved_max_active = max_active;
Lai Jiangshan3c25a552013-03-25 16:57:17 -07004097 mutex_init(&wq->mutex);
Tejun Heo112202d2013-02-13 19:29:12 -08004098 atomic_set(&wq->nr_pwqs_to_flush, 0);
Tejun Heo30cdf242013-03-12 11:29:57 -07004099 INIT_LIST_HEAD(&wq->pwqs);
Tejun Heo73f53c42010-06-29 10:07:11 +02004100 INIT_LIST_HEAD(&wq->flusher_queue);
4101 INIT_LIST_HEAD(&wq->flusher_overflow);
Tejun Heo493a1722013-03-12 11:29:59 -07004102 INIT_LIST_HEAD(&wq->maydays);
Oleg Nesterov3af244332007-05-09 02:34:09 -07004103
Johannes Bergeb13ba82008-01-16 09:51:58 +01004104 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
Oleg Nesterovcce1a162007-05-09 02:34:13 -07004105 INIT_LIST_HEAD(&wq->list);
Oleg Nesterov3af244332007-05-09 02:34:09 -07004106
Tejun Heo30cdf242013-03-12 11:29:57 -07004107 if (alloc_and_link_pwqs(wq) < 0)
Tejun Heod2c1d402013-03-12 11:30:04 -07004108 goto err_free_wq;
Oleg Nesterov3af244332007-05-09 02:34:09 -07004109
Tejun Heo493008a2013-03-12 11:30:03 -07004110 /*
4111 * Workqueues which may be used during memory reclaim should
4112 * have a rescuer to guarantee forward progress.
4113 */
4114 if (flags & WQ_MEM_RECLAIM) {
Tejun Heoe22bee72010-06-29 10:07:14 +02004115 struct worker *rescuer;
4116
Tejun Heod2c1d402013-03-12 11:30:04 -07004117 rescuer = alloc_worker();
Tejun Heoe22bee72010-06-29 10:07:14 +02004118 if (!rescuer)
Tejun Heod2c1d402013-03-12 11:30:04 -07004119 goto err_destroy;
Tejun Heoe22bee72010-06-29 10:07:14 +02004120
Tejun Heo111c2252013-01-17 17:16:24 -08004121 rescuer->rescue_wq = wq;
4122 rescuer->task = kthread_create(rescuer_thread, rescuer, "%s",
Tejun Heob196be82012-01-10 15:11:35 -08004123 wq->name);
Tejun Heod2c1d402013-03-12 11:30:04 -07004124 if (IS_ERR(rescuer->task)) {
4125 kfree(rescuer);
4126 goto err_destroy;
4127 }
Tejun Heoe22bee72010-06-29 10:07:14 +02004128
Tejun Heod2c1d402013-03-12 11:30:04 -07004129 wq->rescuer = rescuer;
Tejun Heo14a40ff2013-03-19 13:45:20 -07004130 rescuer->task->flags |= PF_NO_SETAFFINITY;
Tejun Heoe22bee72010-06-29 10:07:14 +02004131 wake_up_process(rescuer->task);
Oleg Nesterov3af244332007-05-09 02:34:09 -07004132 }
Oleg Nesterov3af244332007-05-09 02:34:09 -07004133
Tejun Heo226223a2013-03-12 11:30:05 -07004134 if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
4135 goto err_destroy;
4136
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004137 /*
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004138 * wq_pool_mutex protects global freeze state and workqueues list.
4139 * Grab it, adjust max_active and add the new @wq to workqueues
4140 * list.
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004141 */
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004142 mutex_lock(&wq_pool_mutex);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004143
Lai Jiangshana357fc02013-03-25 16:57:19 -07004144 mutex_lock(&wq->mutex);
Tejun Heo699ce092013-03-13 16:51:35 -07004145 for_each_pwq(pwq, wq)
4146 pwq_adjust_max_active(pwq);
Lai Jiangshana357fc02013-03-25 16:57:19 -07004147 mutex_unlock(&wq->mutex);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004148
Tejun Heo15376632010-06-29 10:07:11 +02004149 list_add(&wq->list, &workqueues);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004150
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004151 mutex_unlock(&wq_pool_mutex);
Tejun Heo15376632010-06-29 10:07:11 +02004152
Oleg Nesterov3af244332007-05-09 02:34:09 -07004153 return wq;
Tejun Heod2c1d402013-03-12 11:30:04 -07004154
4155err_free_wq:
Tejun Heo6029a912013-04-01 11:23:34 -07004156 free_workqueue_attrs(wq->unbound_attrs);
Tejun Heod2c1d402013-03-12 11:30:04 -07004157 kfree(wq);
4158 return NULL;
4159err_destroy:
4160 destroy_workqueue(wq);
Tejun Heo4690c4a2010-06-29 10:07:10 +02004161 return NULL;
Oleg Nesterov3af244332007-05-09 02:34:09 -07004162}
Tejun Heod320c032010-06-29 10:07:14 +02004163EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
Oleg Nesterov3af244332007-05-09 02:34:09 -07004164
4165/**
4166 * destroy_workqueue - safely terminate a workqueue
4167 * @wq: target workqueue
4168 *
4169 * Safely destroy a workqueue. All work currently pending will be done first.
4170 */
4171void destroy_workqueue(struct workqueue_struct *wq)
4172{
Tejun Heo49e3cf42013-03-12 11:29:58 -07004173 struct pool_workqueue *pwq;
Tejun Heo4c16bd32013-04-01 11:23:36 -07004174 int node;
Oleg Nesterov3af244332007-05-09 02:34:09 -07004175
Tejun Heo9c5a2ba2011-04-05 18:01:44 +02004176 /* drain it before proceeding with destruction */
4177 drain_workqueue(wq);
Tejun Heoc8efcc22010-12-20 19:32:04 +01004178
Tejun Heo6183c002013-03-12 11:29:57 -07004179 /* sanity checks */
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07004180 mutex_lock(&wq->mutex);
Tejun Heo49e3cf42013-03-12 11:29:58 -07004181 for_each_pwq(pwq, wq) {
Tejun Heo6183c002013-03-12 11:29:57 -07004182 int i;
4183
Tejun Heo76af4d92013-03-12 11:30:00 -07004184 for (i = 0; i < WORK_NR_COLORS; i++) {
4185 if (WARN_ON(pwq->nr_in_flight[i])) {
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07004186 mutex_unlock(&wq->mutex);
Tejun Heo6183c002013-03-12 11:29:57 -07004187 return;
Tejun Heo76af4d92013-03-12 11:30:00 -07004188 }
4189 }
4190
Lai Jiangshan5c529592013-04-04 10:05:38 +08004191 if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) ||
Tejun Heo8864b4e2013-03-12 11:30:04 -07004192 WARN_ON(pwq->nr_active) ||
Tejun Heo76af4d92013-03-12 11:30:00 -07004193 WARN_ON(!list_empty(&pwq->delayed_works))) {
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07004194 mutex_unlock(&wq->mutex);
Tejun Heo6183c002013-03-12 11:29:57 -07004195 return;
Tejun Heo76af4d92013-03-12 11:30:00 -07004196 }
Tejun Heo6183c002013-03-12 11:29:57 -07004197 }
Lai Jiangshanb09f4fd2013-03-25 16:57:18 -07004198 mutex_unlock(&wq->mutex);
Tejun Heo6183c002013-03-12 11:29:57 -07004199
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004200 /*
4201 * wq list is used to freeze wq, remove from list after
4202 * flushing is complete in case freeze races us.
4203 */
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004204 mutex_lock(&wq_pool_mutex);
Tejun Heod2c1d402013-03-12 11:30:04 -07004205 list_del_init(&wq->list);
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004206 mutex_unlock(&wq_pool_mutex);
Oleg Nesterov3af244332007-05-09 02:34:09 -07004207
Tejun Heo226223a2013-03-12 11:30:05 -07004208 workqueue_sysfs_unregister(wq);
4209
Tejun Heo493008a2013-03-12 11:30:03 -07004210 if (wq->rescuer) {
Tejun Heoe22bee72010-06-29 10:07:14 +02004211 kthread_stop(wq->rescuer->task);
Xiaotian Feng8d9df9f2010-08-16 09:54:28 +02004212 kfree(wq->rescuer);
Tejun Heo493008a2013-03-12 11:30:03 -07004213 wq->rescuer = NULL;
Tejun Heoe22bee72010-06-29 10:07:14 +02004214 }
4215
Tejun Heo8864b4e2013-03-12 11:30:04 -07004216 if (!(wq->flags & WQ_UNBOUND)) {
4217 /*
4218 * The base ref is never dropped on per-cpu pwqs. Directly
4219 * free the pwqs and wq.
4220 */
4221 free_percpu(wq->cpu_pwqs);
4222 kfree(wq);
4223 } else {
4224 /*
4225 * We're the sole accessor of @wq at this point. Directly
Tejun Heo4c16bd32013-04-01 11:23:36 -07004226 * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
4227 * @wq will be freed when the last pwq is released.
Tejun Heo8864b4e2013-03-12 11:30:04 -07004228 */
Tejun Heo4c16bd32013-04-01 11:23:36 -07004229 for_each_node(node) {
4230 pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
4231 RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL);
4232 put_pwq_unlocked(pwq);
4233 }
4234
4235 /*
4236 * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
4237 * put. Don't access it afterwards.
4238 */
4239 pwq = wq->dfl_pwq;
4240 wq->dfl_pwq = NULL;
Tejun Heodce90d42013-04-01 11:23:35 -07004241 put_pwq_unlocked(pwq);
Tejun Heo29c91e92013-03-12 11:30:03 -07004242 }
Oleg Nesterov3af244332007-05-09 02:34:09 -07004243}
4244EXPORT_SYMBOL_GPL(destroy_workqueue);
4245
Tejun Heodcd989c2010-06-29 10:07:14 +02004246/**
4247 * workqueue_set_max_active - adjust max_active of a workqueue
4248 * @wq: target workqueue
4249 * @max_active: new max_active value.
4250 *
4251 * Set max_active of @wq to @max_active.
4252 *
4253 * CONTEXT:
4254 * Don't call from IRQ context.
4255 */
4256void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
4257{
Tejun Heo49e3cf42013-03-12 11:29:58 -07004258 struct pool_workqueue *pwq;
Tejun Heodcd989c2010-06-29 10:07:14 +02004259
Tejun Heo8719dce2013-03-12 11:30:04 -07004260 /* disallow meddling with max_active for ordered workqueues */
4261 if (WARN_ON(wq->flags & __WQ_ORDERED))
4262 return;
4263
Tejun Heof3421792010-07-02 10:03:51 +02004264 max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
Tejun Heodcd989c2010-06-29 10:07:14 +02004265
Lai Jiangshana357fc02013-03-25 16:57:19 -07004266 mutex_lock(&wq->mutex);
Tejun Heodcd989c2010-06-29 10:07:14 +02004267
4268 wq->saved_max_active = max_active;
4269
Tejun Heo699ce092013-03-13 16:51:35 -07004270 for_each_pwq(pwq, wq)
4271 pwq_adjust_max_active(pwq);
Tejun Heodcd989c2010-06-29 10:07:14 +02004272
Lai Jiangshana357fc02013-03-25 16:57:19 -07004273 mutex_unlock(&wq->mutex);
Tejun Heodcd989c2010-06-29 10:07:14 +02004274}
4275EXPORT_SYMBOL_GPL(workqueue_set_max_active);
4276
4277/**
Tejun Heoe6267612013-03-12 17:41:37 -07004278 * current_is_workqueue_rescuer - is %current workqueue rescuer?
4279 *
4280 * Determine whether %current is a workqueue rescuer. Can be used from
4281 * work functions to determine whether it's being run off the rescuer task.
Yacine Belkadid185af32013-07-31 14:59:24 -07004282 *
4283 * Return: %true if %current is a workqueue rescuer. %false otherwise.
Tejun Heoe6267612013-03-12 17:41:37 -07004284 */
4285bool current_is_workqueue_rescuer(void)
4286{
4287 struct worker *worker = current_wq_worker();
4288
Lai Jiangshan6a092df2013-03-20 03:28:03 +08004289 return worker && worker->rescue_wq;
Tejun Heoe6267612013-03-12 17:41:37 -07004290}
4291
4292/**
Tejun Heodcd989c2010-06-29 10:07:14 +02004293 * workqueue_congested - test whether a workqueue is congested
4294 * @cpu: CPU in question
4295 * @wq: target workqueue
4296 *
4297 * Test whether @wq's cpu workqueue for @cpu is congested. There is
4298 * no synchronization around this function and the test result is
4299 * unreliable and only useful as advisory hints or for debugging.
4300 *
Tejun Heod3251852013-05-10 11:10:17 -07004301 * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
4302 * Note that both per-cpu and unbound workqueues may be associated with
4303 * multiple pool_workqueues which have separate congested states. A
4304 * workqueue being congested on one CPU doesn't mean the workqueue is also
4305 * contested on other CPUs / NUMA nodes.
4306 *
Yacine Belkadid185af32013-07-31 14:59:24 -07004307 * Return:
Tejun Heodcd989c2010-06-29 10:07:14 +02004308 * %true if congested, %false otherwise.
4309 */
Tejun Heod84ff052013-03-12 11:29:59 -07004310bool workqueue_congested(int cpu, struct workqueue_struct *wq)
Tejun Heodcd989c2010-06-29 10:07:14 +02004311{
Tejun Heo7fb98ea2013-03-12 11:30:00 -07004312 struct pool_workqueue *pwq;
Tejun Heo76af4d92013-03-12 11:30:00 -07004313 bool ret;
4314
Lai Jiangshan88109452013-03-20 03:28:10 +08004315 rcu_read_lock_sched();
Tejun Heo7fb98ea2013-03-12 11:30:00 -07004316
Tejun Heod3251852013-05-10 11:10:17 -07004317 if (cpu == WORK_CPU_UNBOUND)
4318 cpu = smp_processor_id();
4319
Tejun Heo7fb98ea2013-03-12 11:30:00 -07004320 if (!(wq->flags & WQ_UNBOUND))
4321 pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
4322 else
Tejun Heodf2d5ae2013-04-01 11:23:35 -07004323 pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
Tejun Heodcd989c2010-06-29 10:07:14 +02004324
Tejun Heo76af4d92013-03-12 11:30:00 -07004325 ret = !list_empty(&pwq->delayed_works);
Lai Jiangshan88109452013-03-20 03:28:10 +08004326 rcu_read_unlock_sched();
Tejun Heo76af4d92013-03-12 11:30:00 -07004327
4328 return ret;
Tejun Heodcd989c2010-06-29 10:07:14 +02004329}
4330EXPORT_SYMBOL_GPL(workqueue_congested);
4331
4332/**
Tejun Heodcd989c2010-06-29 10:07:14 +02004333 * work_busy - test whether a work is currently pending or running
4334 * @work: the work to be tested
4335 *
4336 * Test whether @work is currently pending or running. There is no
4337 * synchronization around this function and the test result is
4338 * unreliable and only useful as advisory hints or for debugging.
Tejun Heodcd989c2010-06-29 10:07:14 +02004339 *
Yacine Belkadid185af32013-07-31 14:59:24 -07004340 * Return:
Tejun Heodcd989c2010-06-29 10:07:14 +02004341 * OR'd bitmask of WORK_BUSY_* bits.
4342 */
4343unsigned int work_busy(struct work_struct *work)
4344{
Tejun Heofa1b54e2013-03-12 11:30:00 -07004345 struct worker_pool *pool;
Tejun Heodcd989c2010-06-29 10:07:14 +02004346 unsigned long flags;
4347 unsigned int ret = 0;
4348
Tejun Heodcd989c2010-06-29 10:07:14 +02004349 if (work_pending(work))
4350 ret |= WORK_BUSY_PENDING;
Tejun Heodcd989c2010-06-29 10:07:14 +02004351
Tejun Heofa1b54e2013-03-12 11:30:00 -07004352 local_irq_save(flags);
4353 pool = get_work_pool(work);
Lai Jiangshan038366c2013-02-06 18:04:53 -08004354 if (pool) {
Tejun Heofa1b54e2013-03-12 11:30:00 -07004355 spin_lock(&pool->lock);
Lai Jiangshan038366c2013-02-06 18:04:53 -08004356 if (find_worker_executing_work(pool, work))
4357 ret |= WORK_BUSY_RUNNING;
Tejun Heofa1b54e2013-03-12 11:30:00 -07004358 spin_unlock(&pool->lock);
Lai Jiangshan038366c2013-02-06 18:04:53 -08004359 }
Tejun Heofa1b54e2013-03-12 11:30:00 -07004360 local_irq_restore(flags);
Tejun Heodcd989c2010-06-29 10:07:14 +02004361
4362 return ret;
4363}
4364EXPORT_SYMBOL_GPL(work_busy);
4365
Tejun Heo3d1cb202013-04-30 15:27:22 -07004366/**
4367 * set_worker_desc - set description for the current work item
4368 * @fmt: printf-style format string
4369 * @...: arguments for the format string
4370 *
4371 * This function can be called by a running work function to describe what
4372 * the work item is about. If the worker task gets dumped, this
4373 * information will be printed out together to help debugging. The
4374 * description can be at most WORKER_DESC_LEN including the trailing '\0'.
4375 */
4376void set_worker_desc(const char *fmt, ...)
4377{
4378 struct worker *worker = current_wq_worker();
4379 va_list args;
4380
4381 if (worker) {
4382 va_start(args, fmt);
4383 vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
4384 va_end(args);
4385 worker->desc_valid = true;
4386 }
4387}
4388
4389/**
4390 * print_worker_info - print out worker information and description
4391 * @log_lvl: the log level to use when printing
4392 * @task: target task
4393 *
4394 * If @task is a worker and currently executing a work item, print out the
4395 * name of the workqueue being serviced and worker description set with
4396 * set_worker_desc() by the currently executing work item.
4397 *
4398 * This function can be safely called on any task as long as the
4399 * task_struct itself is accessible. While safe, this function isn't
4400 * synchronized and may print out mixups or garbages of limited length.
4401 */
4402void print_worker_info(const char *log_lvl, struct task_struct *task)
4403{
4404 work_func_t *fn = NULL;
4405 char name[WQ_NAME_LEN] = { };
4406 char desc[WORKER_DESC_LEN] = { };
4407 struct pool_workqueue *pwq = NULL;
4408 struct workqueue_struct *wq = NULL;
4409 bool desc_valid = false;
4410 struct worker *worker;
4411
4412 if (!(task->flags & PF_WQ_WORKER))
4413 return;
4414
4415 /*
4416 * This function is called without any synchronization and @task
4417 * could be in any state. Be careful with dereferences.
4418 */
4419 worker = probe_kthread_data(task);
4420
4421 /*
4422 * Carefully copy the associated workqueue's workfn and name. Keep
4423 * the original last '\0' in case the original contains garbage.
4424 */
4425 probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
4426 probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
4427 probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
4428 probe_kernel_read(name, wq->name, sizeof(name) - 1);
4429
4430 /* copy worker description */
4431 probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid));
4432 if (desc_valid)
4433 probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
4434
4435 if (fn || name[0] || desc[0]) {
4436 printk("%sWorkqueue: %s %pf", log_lvl, name, fn);
4437 if (desc[0])
4438 pr_cont(" (%s)", desc);
4439 pr_cont("\n");
4440 }
4441}
4442
Tejun Heodb7bccf2010-06-29 10:07:12 +02004443/*
4444 * CPU hotplug.
4445 *
Tejun Heoe22bee72010-06-29 10:07:14 +02004446 * There are two challenges in supporting CPU hotplug. Firstly, there
Tejun Heo112202d2013-02-13 19:29:12 -08004447 * are a lot of assumptions on strong associations among work, pwq and
Tejun Heo706026c2013-01-24 11:01:34 -08004448 * pool which make migrating pending and scheduled works very
Tejun Heoe22bee72010-06-29 10:07:14 +02004449 * difficult to implement without impacting hot paths. Secondly,
Tejun Heo94cf58b2013-01-24 11:01:33 -08004450 * worker pools serve mix of short, long and very long running works making
Tejun Heoe22bee72010-06-29 10:07:14 +02004451 * blocked draining impractical.
4452 *
Tejun Heo24647572013-01-24 11:01:33 -08004453 * This is solved by allowing the pools to be disassociated from the CPU
Tejun Heo628c78e2012-07-17 12:39:27 -07004454 * running as an unbound one and allowing it to be reattached later if the
4455 * cpu comes back online.
Tejun Heodb7bccf2010-06-29 10:07:12 +02004456 */
4457
Tejun Heo706026c2013-01-24 11:01:34 -08004458static void wq_unbind_fn(struct work_struct *work)
Tejun Heodb7bccf2010-06-29 10:07:12 +02004459{
Tejun Heo38db41d2013-01-24 11:01:34 -08004460 int cpu = smp_processor_id();
Tejun Heo4ce62e92012-07-13 22:16:44 -07004461 struct worker_pool *pool;
Tejun Heodb7bccf2010-06-29 10:07:12 +02004462 struct worker *worker;
Tejun Heodb7bccf2010-06-29 10:07:12 +02004463
Tejun Heof02ae732013-03-12 11:30:03 -07004464 for_each_cpu_worker_pool(pool, cpu) {
Tejun Heo6183c002013-03-12 11:29:57 -07004465 WARN_ON_ONCE(cpu != smp_processor_id());
Tejun Heo94cf58b2013-01-24 11:01:33 -08004466
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08004467 mutex_lock(&pool->attach_mutex);
Tejun Heo94cf58b2013-01-24 11:01:33 -08004468 spin_lock_irq(&pool->lock);
4469
4470 /*
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08004471 * We've blocked all attach/detach operations. Make all workers
Tejun Heo94cf58b2013-01-24 11:01:33 -08004472 * unbound and set DISASSOCIATED. Before this, all workers
4473 * except for the ones which are still executing works from
4474 * before the last CPU down must be on the cpu. After
4475 * this, they may become diasporas.
4476 */
Lai Jiangshanda028462014-05-20 17:46:31 +08004477 for_each_pool_worker(worker, pool)
Tejun Heoc9e7cf22013-01-24 11:01:33 -08004478 worker->flags |= WORKER_UNBOUND;
Tejun Heodb7bccf2010-06-29 10:07:12 +02004479
Tejun Heo24647572013-01-24 11:01:33 -08004480 pool->flags |= POOL_DISASSOCIATED;
Tejun Heof2d5a0e2012-07-17 12:39:26 -07004481
Tejun Heo94cf58b2013-01-24 11:01:33 -08004482 spin_unlock_irq(&pool->lock);
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08004483 mutex_unlock(&pool->attach_mutex);
Tejun Heoe22bee72010-06-29 10:07:14 +02004484
Lai Jiangshaneb283422013-03-08 15:18:28 -08004485 /*
4486 * Call schedule() so that we cross rq->lock and thus can
4487 * guarantee sched callbacks see the %WORKER_UNBOUND flag.
4488 * This is necessary as scheduler callbacks may be invoked
4489 * from other cpus.
4490 */
4491 schedule();
Tejun Heo628c78e2012-07-17 12:39:27 -07004492
Lai Jiangshaneb283422013-03-08 15:18:28 -08004493 /*
4494 * Sched callbacks are disabled now. Zap nr_running.
4495 * After this, nr_running stays zero and need_more_worker()
4496 * and keep_working() are always true as long as the
4497 * worklist is not empty. This pool now behaves as an
4498 * unbound (in terms of concurrency management) pool which
4499 * are served by workers tied to the pool.
4500 */
Tejun Heoe19e3972013-01-24 11:39:44 -08004501 atomic_set(&pool->nr_running, 0);
Lai Jiangshaneb283422013-03-08 15:18:28 -08004502
4503 /*
4504 * With concurrency management just turned off, a busy
4505 * worker blocking could lead to lengthy stalls. Kick off
4506 * unbound chain execution of currently pending work items.
4507 */
4508 spin_lock_irq(&pool->lock);
4509 wake_up_worker(pool);
4510 spin_unlock_irq(&pool->lock);
4511 }
Tejun Heodb7bccf2010-06-29 10:07:12 +02004512}
4513
Tejun Heobd7c0892013-03-19 13:45:21 -07004514/**
4515 * rebind_workers - rebind all workers of a pool to the associated CPU
4516 * @pool: pool of interest
4517 *
Tejun Heoa9ab7752013-03-19 13:45:21 -07004518 * @pool->cpu is coming online. Rebind all workers to the CPU.
Tejun Heobd7c0892013-03-19 13:45:21 -07004519 */
4520static void rebind_workers(struct worker_pool *pool)
4521{
Tejun Heoa9ab7752013-03-19 13:45:21 -07004522 struct worker *worker;
Tejun Heobd7c0892013-03-19 13:45:21 -07004523
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08004524 lockdep_assert_held(&pool->attach_mutex);
Tejun Heobd7c0892013-03-19 13:45:21 -07004525
Tejun Heoa9ab7752013-03-19 13:45:21 -07004526 /*
4527 * Restore CPU affinity of all workers. As all idle workers should
4528 * be on the run-queue of the associated CPU before any local
4529 * wake-ups for concurrency management happen, restore CPU affinty
4530 * of all workers first and then clear UNBOUND. As we're called
4531 * from CPU_ONLINE, the following shouldn't fail.
4532 */
Lai Jiangshanda028462014-05-20 17:46:31 +08004533 for_each_pool_worker(worker, pool)
Tejun Heoa9ab7752013-03-19 13:45:21 -07004534 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4535 pool->attrs->cpumask) < 0);
4536
4537 spin_lock_irq(&pool->lock);
4538
Lai Jiangshanda028462014-05-20 17:46:31 +08004539 for_each_pool_worker(worker, pool) {
Tejun Heoa9ab7752013-03-19 13:45:21 -07004540 unsigned int worker_flags = worker->flags;
Tejun Heobd7c0892013-03-19 13:45:21 -07004541
4542 /*
Tejun Heoa9ab7752013-03-19 13:45:21 -07004543 * A bound idle worker should actually be on the runqueue
4544 * of the associated CPU for local wake-ups targeting it to
4545 * work. Kick all idle workers so that they migrate to the
4546 * associated CPU. Doing this in the same loop as
4547 * replacing UNBOUND with REBOUND is safe as no worker will
4548 * be bound before @pool->lock is released.
Tejun Heobd7c0892013-03-19 13:45:21 -07004549 */
Tejun Heoa9ab7752013-03-19 13:45:21 -07004550 if (worker_flags & WORKER_IDLE)
4551 wake_up_process(worker->task);
4552
4553 /*
4554 * We want to clear UNBOUND but can't directly call
4555 * worker_clr_flags() or adjust nr_running. Atomically
4556 * replace UNBOUND with another NOT_RUNNING flag REBOUND.
4557 * @worker will clear REBOUND using worker_clr_flags() when
4558 * it initiates the next execution cycle thus restoring
4559 * concurrency management. Note that when or whether
4560 * @worker clears REBOUND doesn't affect correctness.
4561 *
4562 * ACCESS_ONCE() is necessary because @worker->flags may be
4563 * tested without holding any lock in
4564 * wq_worker_waking_up(). Without it, NOT_RUNNING test may
4565 * fail incorrectly leading to premature concurrency
4566 * management operations.
4567 */
4568 WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
4569 worker_flags |= WORKER_REBOUND;
4570 worker_flags &= ~WORKER_UNBOUND;
4571 ACCESS_ONCE(worker->flags) = worker_flags;
Tejun Heobd7c0892013-03-19 13:45:21 -07004572 }
4573
Tejun Heoa9ab7752013-03-19 13:45:21 -07004574 spin_unlock_irq(&pool->lock);
Tejun Heobd7c0892013-03-19 13:45:21 -07004575}
4576
Tejun Heo7dbc7252013-03-19 13:45:21 -07004577/**
4578 * restore_unbound_workers_cpumask - restore cpumask of unbound workers
4579 * @pool: unbound pool of interest
4580 * @cpu: the CPU which is coming up
4581 *
4582 * An unbound pool may end up with a cpumask which doesn't have any online
4583 * CPUs. When a worker of such pool get scheduled, the scheduler resets
4584 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4585 * online CPU before, cpus_allowed of all its workers should be restored.
4586 */
4587static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
4588{
4589 static cpumask_t cpumask;
4590 struct worker *worker;
Tejun Heo7dbc7252013-03-19 13:45:21 -07004591
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08004592 lockdep_assert_held(&pool->attach_mutex);
Tejun Heo7dbc7252013-03-19 13:45:21 -07004593
4594 /* is @cpu allowed for @pool? */
4595 if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
4596 return;
4597
4598 /* is @cpu the only online CPU? */
4599 cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
4600 if (cpumask_weight(&cpumask) != 1)
4601 return;
4602
4603 /* as we're called from CPU_ONLINE, the following shouldn't fail */
Lai Jiangshanda028462014-05-20 17:46:31 +08004604 for_each_pool_worker(worker, pool)
Tejun Heo7dbc7252013-03-19 13:45:21 -07004605 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4606 pool->attrs->cpumask) < 0);
4607}
4608
Tejun Heo8db25e72012-07-17 12:39:28 -07004609/*
4610 * Workqueues should be brought up before normal priority CPU notifiers.
4611 * This will be registered high priority CPU notifier.
4612 */
Paul Gortmaker0db06282013-06-19 14:53:51 -04004613static int workqueue_cpu_up_callback(struct notifier_block *nfb,
Tejun Heo8db25e72012-07-17 12:39:28 -07004614 unsigned long action,
4615 void *hcpu)
Oleg Nesterov3af244332007-05-09 02:34:09 -07004616{
Tejun Heod84ff052013-03-12 11:29:59 -07004617 int cpu = (unsigned long)hcpu;
Tejun Heo4ce62e92012-07-13 22:16:44 -07004618 struct worker_pool *pool;
Tejun Heo4c16bd32013-04-01 11:23:36 -07004619 struct workqueue_struct *wq;
Tejun Heo7dbc7252013-03-19 13:45:21 -07004620 int pi;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004621
Tejun Heo8db25e72012-07-17 12:39:28 -07004622 switch (action & ~CPU_TASKS_FROZEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004623 case CPU_UP_PREPARE:
Tejun Heof02ae732013-03-12 11:30:03 -07004624 for_each_cpu_worker_pool(pool, cpu) {
Tejun Heo3ce63372012-07-17 12:39:27 -07004625 if (pool->nr_workers)
4626 continue;
Tejun Heoebf44d12013-03-13 19:47:39 -07004627 if (create_and_start_worker(pool) < 0)
Tejun Heo3ce63372012-07-17 12:39:27 -07004628 return NOTIFY_BAD;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004629 }
Tejun Heodb7bccf2010-06-29 10:07:12 +02004630 break;
Oleg Nesterov00dfcaf2008-04-29 01:00:27 -07004631
Tejun Heo65758202012-07-17 12:39:26 -07004632 case CPU_DOWN_FAILED:
4633 case CPU_ONLINE:
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004634 mutex_lock(&wq_pool_mutex);
Tejun Heo7dbc7252013-03-19 13:45:21 -07004635
4636 for_each_pool(pool, pi) {
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08004637 mutex_lock(&pool->attach_mutex);
Tejun Heo94cf58b2013-01-24 11:01:33 -08004638
Tejun Heo7dbc7252013-03-19 13:45:21 -07004639 if (pool->cpu == cpu) {
4640 spin_lock_irq(&pool->lock);
4641 pool->flags &= ~POOL_DISASSOCIATED;
4642 spin_unlock_irq(&pool->lock);
Tejun Heoa9ab7752013-03-19 13:45:21 -07004643
Tejun Heo7dbc7252013-03-19 13:45:21 -07004644 rebind_workers(pool);
4645 } else if (pool->cpu < 0) {
4646 restore_unbound_workers_cpumask(pool, cpu);
4647 }
Tejun Heo94cf58b2013-01-24 11:01:33 -08004648
Lai Jiangshan92f9c5c2014-05-20 17:46:34 +08004649 mutex_unlock(&pool->attach_mutex);
Tejun Heo94cf58b2013-01-24 11:01:33 -08004650 }
Tejun Heo7dbc7252013-03-19 13:45:21 -07004651
Tejun Heo4c16bd32013-04-01 11:23:36 -07004652 /* update NUMA affinity of unbound workqueues */
4653 list_for_each_entry(wq, &workqueues, list)
4654 wq_update_unbound_numa(wq, cpu, true);
4655
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004656 mutex_unlock(&wq_pool_mutex);
Tejun Heo8db25e72012-07-17 12:39:28 -07004657 break;
Tejun Heo65758202012-07-17 12:39:26 -07004658 }
4659 return NOTIFY_OK;
4660}
4661
4662/*
4663 * Workqueues should be brought down after normal priority CPU notifiers.
4664 * This will be registered as low priority CPU notifier.
4665 */
Paul Gortmaker0db06282013-06-19 14:53:51 -04004666static int workqueue_cpu_down_callback(struct notifier_block *nfb,
Tejun Heo65758202012-07-17 12:39:26 -07004667 unsigned long action,
4668 void *hcpu)
4669{
Tejun Heod84ff052013-03-12 11:29:59 -07004670 int cpu = (unsigned long)hcpu;
Tejun Heo8db25e72012-07-17 12:39:28 -07004671 struct work_struct unbind_work;
Tejun Heo4c16bd32013-04-01 11:23:36 -07004672 struct workqueue_struct *wq;
Tejun Heo8db25e72012-07-17 12:39:28 -07004673
Tejun Heo65758202012-07-17 12:39:26 -07004674 switch (action & ~CPU_TASKS_FROZEN) {
4675 case CPU_DOWN_PREPARE:
Tejun Heo4c16bd32013-04-01 11:23:36 -07004676 /* unbinding per-cpu workers should happen on the local CPU */
Tejun Heo706026c2013-01-24 11:01:34 -08004677 INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
Joonsoo Kim7635d2f2012-08-15 23:25:41 +09004678 queue_work_on(cpu, system_highpri_wq, &unbind_work);
Tejun Heo4c16bd32013-04-01 11:23:36 -07004679
4680 /* update NUMA affinity of unbound workqueues */
4681 mutex_lock(&wq_pool_mutex);
4682 list_for_each_entry(wq, &workqueues, list)
4683 wq_update_unbound_numa(wq, cpu, false);
4684 mutex_unlock(&wq_pool_mutex);
4685
4686 /* wait for per-cpu unbinding to finish */
Tejun Heo8db25e72012-07-17 12:39:28 -07004687 flush_work(&unbind_work);
Chuansheng Liu440a1132014-01-11 22:26:33 -05004688 destroy_work_on_stack(&unbind_work);
Tejun Heo8db25e72012-07-17 12:39:28 -07004689 break;
Tejun Heo65758202012-07-17 12:39:26 -07004690 }
4691 return NOTIFY_OK;
4692}
4693
Rusty Russell2d3854a2008-11-05 13:39:10 +11004694#ifdef CONFIG_SMP
Rusty Russell8ccad402009-01-16 15:31:15 -08004695
Rusty Russell2d3854a2008-11-05 13:39:10 +11004696struct work_for_cpu {
Tejun Heoed48ece2012-09-18 12:48:43 -07004697 struct work_struct work;
Rusty Russell2d3854a2008-11-05 13:39:10 +11004698 long (*fn)(void *);
4699 void *arg;
4700 long ret;
4701};
4702
Tejun Heoed48ece2012-09-18 12:48:43 -07004703static void work_for_cpu_fn(struct work_struct *work)
Rusty Russell2d3854a2008-11-05 13:39:10 +11004704{
Tejun Heoed48ece2012-09-18 12:48:43 -07004705 struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
4706
Rusty Russell2d3854a2008-11-05 13:39:10 +11004707 wfc->ret = wfc->fn(wfc->arg);
4708}
4709
4710/**
4711 * work_on_cpu - run a function in user context on a particular cpu
4712 * @cpu: the cpu to run on
4713 * @fn: the function to run
4714 * @arg: the function arg
4715 *
Rusty Russell31ad9082009-01-16 15:31:15 -08004716 * It is up to the caller to ensure that the cpu doesn't go offline.
Andrew Morton6b440032009-04-09 09:50:37 -06004717 * The caller must not hold any locks which would prevent @fn from completing.
Yacine Belkadid185af32013-07-31 14:59:24 -07004718 *
4719 * Return: The value @fn returns.
Rusty Russell2d3854a2008-11-05 13:39:10 +11004720 */
Tejun Heod84ff052013-03-12 11:29:59 -07004721long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
Rusty Russell2d3854a2008-11-05 13:39:10 +11004722{
Tejun Heoed48ece2012-09-18 12:48:43 -07004723 struct work_for_cpu wfc = { .fn = fn, .arg = arg };
Rusty Russell2d3854a2008-11-05 13:39:10 +11004724
Tejun Heoed48ece2012-09-18 12:48:43 -07004725 INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
4726 schedule_work_on(cpu, &wfc.work);
Bjorn Helgaas12997d12013-11-18 11:00:29 -07004727 flush_work(&wfc.work);
Chuansheng Liu440a1132014-01-11 22:26:33 -05004728 destroy_work_on_stack(&wfc.work);
Rusty Russell2d3854a2008-11-05 13:39:10 +11004729 return wfc.ret;
4730}
4731EXPORT_SYMBOL_GPL(work_on_cpu);
4732#endif /* CONFIG_SMP */
4733
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004734#ifdef CONFIG_FREEZER
Rusty Russelle7577c52009-01-01 10:12:25 +10304735
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004736/**
4737 * freeze_workqueues_begin - begin freezing workqueues
4738 *
Tejun Heo58a69cb2011-02-16 09:25:31 +01004739 * Start freezing workqueues. After this function returns, all freezable
Tejun Heoc5aa87b2013-03-13 16:51:36 -07004740 * workqueues will queue new works to their delayed_works list instead of
Tejun Heo706026c2013-01-24 11:01:34 -08004741 * pool->worklist.
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004742 *
4743 * CONTEXT:
Lai Jiangshana357fc02013-03-25 16:57:19 -07004744 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004745 */
4746void freeze_workqueues_begin(void)
4747{
Tejun Heo24b8a842013-03-12 11:29:58 -07004748 struct workqueue_struct *wq;
4749 struct pool_workqueue *pwq;
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004750
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004751 mutex_lock(&wq_pool_mutex);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004752
Tejun Heo6183c002013-03-12 11:29:57 -07004753 WARN_ON_ONCE(workqueue_freezing);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004754 workqueue_freezing = true;
4755
Tejun Heo24b8a842013-03-12 11:29:58 -07004756 list_for_each_entry(wq, &workqueues, list) {
Lai Jiangshana357fc02013-03-25 16:57:19 -07004757 mutex_lock(&wq->mutex);
Tejun Heo699ce092013-03-13 16:51:35 -07004758 for_each_pwq(pwq, wq)
4759 pwq_adjust_max_active(pwq);
Lai Jiangshana357fc02013-03-25 16:57:19 -07004760 mutex_unlock(&wq->mutex);
Tejun Heo24b8a842013-03-12 11:29:58 -07004761 }
Tejun Heo5bcab332013-03-13 19:47:40 -07004762
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004763 mutex_unlock(&wq_pool_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004764}
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004765
4766/**
Tejun Heo58a69cb2011-02-16 09:25:31 +01004767 * freeze_workqueues_busy - are freezable workqueues still busy?
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004768 *
4769 * Check whether freezing is complete. This function must be called
4770 * between freeze_workqueues_begin() and thaw_workqueues().
4771 *
4772 * CONTEXT:
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004773 * Grabs and releases wq_pool_mutex.
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004774 *
Yacine Belkadid185af32013-07-31 14:59:24 -07004775 * Return:
Tejun Heo58a69cb2011-02-16 09:25:31 +01004776 * %true if some freezable workqueues are still busy. %false if freezing
4777 * is complete.
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004778 */
4779bool freeze_workqueues_busy(void)
4780{
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004781 bool busy = false;
Tejun Heo24b8a842013-03-12 11:29:58 -07004782 struct workqueue_struct *wq;
4783 struct pool_workqueue *pwq;
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004784
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004785 mutex_lock(&wq_pool_mutex);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004786
Tejun Heo6183c002013-03-12 11:29:57 -07004787 WARN_ON_ONCE(!workqueue_freezing);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004788
Tejun Heo24b8a842013-03-12 11:29:58 -07004789 list_for_each_entry(wq, &workqueues, list) {
4790 if (!(wq->flags & WQ_FREEZABLE))
4791 continue;
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004792 /*
4793 * nr_active is monotonically decreasing. It's safe
4794 * to peek without lock.
4795 */
Lai Jiangshan88109452013-03-20 03:28:10 +08004796 rcu_read_lock_sched();
Tejun Heo24b8a842013-03-12 11:29:58 -07004797 for_each_pwq(pwq, wq) {
Tejun Heo6183c002013-03-12 11:29:57 -07004798 WARN_ON_ONCE(pwq->nr_active < 0);
Tejun Heo112202d2013-02-13 19:29:12 -08004799 if (pwq->nr_active) {
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004800 busy = true;
Lai Jiangshan88109452013-03-20 03:28:10 +08004801 rcu_read_unlock_sched();
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004802 goto out_unlock;
4803 }
4804 }
Lai Jiangshan88109452013-03-20 03:28:10 +08004805 rcu_read_unlock_sched();
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004806 }
4807out_unlock:
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004808 mutex_unlock(&wq_pool_mutex);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004809 return busy;
4810}
4811
4812/**
4813 * thaw_workqueues - thaw workqueues
4814 *
4815 * Thaw workqueues. Normal queueing is restored and all collected
Tejun Heo706026c2013-01-24 11:01:34 -08004816 * frozen works are transferred to their respective pool worklists.
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004817 *
4818 * CONTEXT:
Lai Jiangshana357fc02013-03-25 16:57:19 -07004819 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004820 */
4821void thaw_workqueues(void)
4822{
Tejun Heo24b8a842013-03-12 11:29:58 -07004823 struct workqueue_struct *wq;
4824 struct pool_workqueue *pwq;
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004825
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004826 mutex_lock(&wq_pool_mutex);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004827
4828 if (!workqueue_freezing)
4829 goto out_unlock;
4830
Lai Jiangshan74b414e2014-05-22 19:01:16 +08004831 workqueue_freezing = false;
Tejun Heo8b03ae32010-06-29 10:07:12 +02004832
Tejun Heo24b8a842013-03-12 11:29:58 -07004833 /* restore max_active and repopulate worklist */
4834 list_for_each_entry(wq, &workqueues, list) {
Lai Jiangshana357fc02013-03-25 16:57:19 -07004835 mutex_lock(&wq->mutex);
Tejun Heo699ce092013-03-13 16:51:35 -07004836 for_each_pwq(pwq, wq)
4837 pwq_adjust_max_active(pwq);
Lai Jiangshana357fc02013-03-25 16:57:19 -07004838 mutex_unlock(&wq->mutex);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004839 }
4840
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004841out_unlock:
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004842 mutex_unlock(&wq_pool_mutex);
Tejun Heoa0a1a5f2010-06-29 10:07:12 +02004843}
4844#endif /* CONFIG_FREEZER */
4845
Tejun Heobce90382013-04-01 11:23:32 -07004846static void __init wq_numa_init(void)
4847{
4848 cpumask_var_t *tbl;
4849 int node, cpu;
4850
4851 /* determine NUMA pwq table len - highest node id + 1 */
4852 for_each_node(node)
4853 wq_numa_tbl_len = max(wq_numa_tbl_len, node + 1);
4854
4855 if (num_possible_nodes() <= 1)
4856 return;
4857
Tejun Heod55262c2013-04-01 11:23:38 -07004858 if (wq_disable_numa) {
4859 pr_info("workqueue: NUMA affinity support disabled\n");
4860 return;
4861 }
4862
Tejun Heo4c16bd32013-04-01 11:23:36 -07004863 wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL);
4864 BUG_ON(!wq_update_unbound_numa_attrs_buf);
4865
Tejun Heobce90382013-04-01 11:23:32 -07004866 /*
4867 * We want masks of possible CPUs of each node which isn't readily
4868 * available. Build one from cpu_to_node() which should have been
4869 * fully initialized by now.
4870 */
4871 tbl = kzalloc(wq_numa_tbl_len * sizeof(tbl[0]), GFP_KERNEL);
4872 BUG_ON(!tbl);
4873
4874 for_each_node(node)
Tejun Heo1be0c252013-05-15 14:24:24 -07004875 BUG_ON(!alloc_cpumask_var_node(&tbl[node], GFP_KERNEL,
4876 node_online(node) ? node : NUMA_NO_NODE));
Tejun Heobce90382013-04-01 11:23:32 -07004877
4878 for_each_possible_cpu(cpu) {
4879 node = cpu_to_node(cpu);
4880 if (WARN_ON(node == NUMA_NO_NODE)) {
4881 pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
4882 /* happens iff arch is bonkers, let's just proceed */
4883 return;
4884 }
4885 cpumask_set_cpu(cpu, tbl[node]);
4886 }
4887
4888 wq_numa_possible_cpumask = tbl;
4889 wq_numa_enabled = true;
4890}
4891
Suresh Siddha6ee05782010-07-30 14:57:37 -07004892static int __init init_workqueues(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07004893{
Tejun Heo7a4e3442013-03-12 11:30:00 -07004894 int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
4895 int i, cpu;
Tejun Heoc34056a2010-06-29 10:07:11 +02004896
Tejun Heoe904e6c2013-03-12 11:29:57 -07004897 WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
4898
4899 pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
4900
Tejun Heo65758202012-07-17 12:39:26 -07004901 cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
Lai Jiangshana5b4e572012-09-18 09:59:23 -07004902 hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
Tejun Heo8b03ae32010-06-29 10:07:12 +02004903
Tejun Heobce90382013-04-01 11:23:32 -07004904 wq_numa_init();
4905
Tejun Heo706026c2013-01-24 11:01:34 -08004906 /* initialize CPU pools */
Tejun Heo29c91e92013-03-12 11:30:03 -07004907 for_each_possible_cpu(cpu) {
Tejun Heo4ce62e92012-07-13 22:16:44 -07004908 struct worker_pool *pool;
Tejun Heo8b03ae32010-06-29 10:07:12 +02004909
Tejun Heo7a4e3442013-03-12 11:30:00 -07004910 i = 0;
Tejun Heof02ae732013-03-12 11:30:03 -07004911 for_each_cpu_worker_pool(pool, cpu) {
Tejun Heo7a4e3442013-03-12 11:30:00 -07004912 BUG_ON(init_worker_pool(pool));
Tejun Heoec22ca52013-01-24 11:01:33 -08004913 pool->cpu = cpu;
Tejun Heo29c91e92013-03-12 11:30:03 -07004914 cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
Tejun Heo7a4e3442013-03-12 11:30:00 -07004915 pool->attrs->nice = std_nice[i++];
Tejun Heof3f90ad2013-04-01 11:23:34 -07004916 pool->node = cpu_to_node(cpu);
Tejun Heo7a4e3442013-03-12 11:30:00 -07004917
Tejun Heo9daf9e62013-01-24 11:01:33 -08004918 /* alloc pool ID */
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004919 mutex_lock(&wq_pool_mutex);
Tejun Heo9daf9e62013-01-24 11:01:33 -08004920 BUG_ON(worker_pool_assign_id(pool));
Lai Jiangshan68e13a62013-03-25 16:57:17 -07004921 mutex_unlock(&wq_pool_mutex);
Tejun Heo4ce62e92012-07-13 22:16:44 -07004922 }
Tejun Heo8b03ae32010-06-29 10:07:12 +02004923 }
4924
Tejun Heoe22bee72010-06-29 10:07:14 +02004925 /* create the initial worker */
Tejun Heo29c91e92013-03-12 11:30:03 -07004926 for_each_online_cpu(cpu) {
Tejun Heo4ce62e92012-07-13 22:16:44 -07004927 struct worker_pool *pool;
Tejun Heoe22bee72010-06-29 10:07:14 +02004928
Tejun Heof02ae732013-03-12 11:30:03 -07004929 for_each_cpu_worker_pool(pool, cpu) {
Tejun Heo29c91e92013-03-12 11:30:03 -07004930 pool->flags &= ~POOL_DISASSOCIATED;
Tejun Heoebf44d12013-03-13 19:47:39 -07004931 BUG_ON(create_and_start_worker(pool) < 0);
Tejun Heo4ce62e92012-07-13 22:16:44 -07004932 }
Tejun Heoe22bee72010-06-29 10:07:14 +02004933 }
4934
Tejun Heo8a2b7532013-09-05 12:30:04 -04004935 /* create default unbound and ordered wq attrs */
Tejun Heo29c91e92013-03-12 11:30:03 -07004936 for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
4937 struct workqueue_attrs *attrs;
4938
4939 BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
Tejun Heo29c91e92013-03-12 11:30:03 -07004940 attrs->nice = std_nice[i];
Tejun Heo29c91e92013-03-12 11:30:03 -07004941 unbound_std_wq_attrs[i] = attrs;
Tejun Heo8a2b7532013-09-05 12:30:04 -04004942
4943 /*
4944 * An ordered wq should have only one pwq as ordering is
4945 * guaranteed by max_active which is enforced by pwqs.
4946 * Turn off NUMA so that dfl_pwq is used for all nodes.
4947 */
4948 BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
4949 attrs->nice = std_nice[i];
4950 attrs->no_numa = true;
4951 ordered_wq_attrs[i] = attrs;
Tejun Heo29c91e92013-03-12 11:30:03 -07004952 }
4953
Tejun Heod320c032010-06-29 10:07:14 +02004954 system_wq = alloc_workqueue("events", 0, 0);
Joonsoo Kim1aabe902012-08-15 23:25:39 +09004955 system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
Tejun Heod320c032010-06-29 10:07:14 +02004956 system_long_wq = alloc_workqueue("events_long", 0, 0);
Tejun Heof3421792010-07-02 10:03:51 +02004957 system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
4958 WQ_UNBOUND_MAX_ACTIVE);
Tejun Heo24d51ad2011-02-21 09:52:50 +01004959 system_freezable_wq = alloc_workqueue("events_freezable",
4960 WQ_FREEZABLE, 0);
Viresh Kumar06681062013-04-24 17:12:54 +05304961 system_power_efficient_wq = alloc_workqueue("events_power_efficient",
4962 WQ_POWER_EFFICIENT, 0);
4963 system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient",
4964 WQ_FREEZABLE | WQ_POWER_EFFICIENT,
4965 0);
Joonsoo Kim1aabe902012-08-15 23:25:39 +09004966 BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||
Viresh Kumar06681062013-04-24 17:12:54 +05304967 !system_unbound_wq || !system_freezable_wq ||
4968 !system_power_efficient_wq ||
4969 !system_freezable_power_efficient_wq);
Suresh Siddha6ee05782010-07-30 14:57:37 -07004970 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004971}
Suresh Siddha6ee05782010-07-30 14:57:37 -07004972early_initcall(init_workqueues);