2 * linux/kernel/workqueue.c
4 * Generic mechanism for defining kernel helper threads for running
5 * arbitrary tasks in process context.
7 * Started by Ingo Molnar, Copyright (C) 2002
9 * Derived from the taskqueue/keventd code by:
11 * David Woodhouse <dwmw2@infradead.org>
13 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
14 * Theodore Ts'o <tytso@mit.edu>
16 * Made to use alloc_percpu by Christoph Lameter.
19 #include <linux/module.h>
20 #include <linux/kernel.h>
21 #include <linux/sched.h>
22 #include <linux/init.h>
23 #include <linux/signal.h>
24 #include <linux/completion.h>
25 #include <linux/workqueue.h>
26 #include <linux/slab.h>
27 #include <linux/cpu.h>
28 #include <linux/notifier.h>
29 #include <linux/kthread.h>
30 #include <linux/hardirq.h>
31 #include <linux/mempolicy.h>
32 #include <linux/freezer.h>
33 #include <linux/kallsyms.h>
34 #include <linux/debug_locks.h>
35 #include <linux/lockdep.h>
36 #include <linux/idr.h>
38 #include "workqueue_sched.h"
41 /* global_cwq flags */
42 GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
43 GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */
44 GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
45 GCWQ_FREEZING = 1 << 3, /* freeze in progress */
46 GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */
49 WORKER_STARTED = 1 << 0, /* started */
50 WORKER_DIE = 1 << 1, /* die die die */
51 WORKER_IDLE = 1 << 2, /* is idle */
52 WORKER_PREP = 1 << 3, /* preparing to run works */
53 WORKER_ROGUE = 1 << 4, /* not bound to any cpu */
54 WORKER_REBIND = 1 << 5, /* mom is home, come back */
55 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
56 WORKER_UNBOUND = 1 << 7, /* worker is unbound */
58 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND |
59 WORKER_CPU_INTENSIVE | WORKER_UNBOUND,
61 /* gcwq->trustee_state */
62 TRUSTEE_START = 0, /* start */
63 TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */
64 TRUSTEE_BUTCHER = 2, /* butcher workers */
65 TRUSTEE_RELEASE = 3, /* release workers */
66 TRUSTEE_DONE = 4, /* trustee is done */
68 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
69 BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER,
70 BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1,
72 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
73 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
75 MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */
76 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
77 CREATE_COOLDOWN = HZ, /* time to breath after fail */
78 TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */
81 * Rescue workers are used only on emergencies and shared by
84 RESCUER_NICE_LEVEL = -20,
88 * Structure fields follow one of the following exclusion rules.
90 * I: Set during initialization and read-only afterwards.
92 * P: Preemption protected. Disabling preemption is enough and should
93 * only be modified and accessed from the local cpu.
95 * L: gcwq->lock protected. Access with gcwq->lock held.
97 * X: During normal operation, modification requires gcwq->lock and
98 * should be done only from local cpu. Either disabling preemption
99 * on local cpu or grabbing gcwq->lock is enough for read access.
100 * If GCWQ_DISASSOCIATED is set, it's identical to L.
102 * F: wq->flush_mutex protected.
104 * W: workqueue_lock protected.
110 * The poor guys doing the actual heavy lifting. All on-duty workers
111 * are either serving the manager role, on idle list or on busy hash.
114 /* on idle list while idle, on busy hash table while busy */
116 struct list_head entry; /* L: while idle */
117 struct hlist_node hentry; /* L: while busy */
120 struct work_struct *current_work; /* L: work being processed */
121 struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
122 struct list_head scheduled; /* L: scheduled works */
123 struct task_struct *task; /* I: worker task */
124 struct global_cwq *gcwq; /* I: the associated gcwq */
125 /* 64 bytes boundary on 64bit, 32 on 32bit */
126 unsigned long last_active; /* L: last active timestamp */
127 unsigned int flags; /* X: flags */
128 int id; /* I: worker id */
129 struct work_struct rebind_work; /* L: rebind worker to cpu */
133 * Global per-cpu workqueue. There's one and only one for each cpu
134 * and all works are queued and processed here regardless of their
138 spinlock_t lock; /* the gcwq lock */
139 struct list_head worklist; /* L: list of pending works */
140 unsigned int cpu; /* I: the associated cpu */
141 unsigned int flags; /* L: GCWQ_* flags */
143 int nr_workers; /* L: total number of workers */
144 int nr_idle; /* L: currently idle ones */
146 /* workers are chained either in the idle_list or busy_hash */
147 struct list_head idle_list; /* X: list of idle workers */
148 struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE];
149 /* L: hash of busy workers */
151 struct timer_list idle_timer; /* L: worker idle timeout */
152 struct timer_list mayday_timer; /* L: SOS timer for dworkers */
154 struct ida worker_ida; /* L: for worker IDs */
156 struct task_struct *trustee; /* L: for gcwq shutdown */
157 unsigned int trustee_state; /* L: trustee state */
158 wait_queue_head_t trustee_wait; /* trustee wait */
159 struct worker *first_idle; /* L: first idle worker */
160 } ____cacheline_aligned_in_smp;
163 * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
164 * work_struct->data are used for flags and thus cwqs need to be
165 * aligned at two's power of the number of flag bits.
167 struct cpu_workqueue_struct {
168 struct global_cwq *gcwq; /* I: the associated gcwq */
169 struct workqueue_struct *wq; /* I: the owning workqueue */
170 int work_color; /* L: current color */
171 int flush_color; /* L: flushing color */
172 int nr_in_flight[WORK_NR_COLORS];
173 /* L: nr of in_flight works */
174 int nr_active; /* L: nr of active works */
175 int max_active; /* L: max active works */
176 struct list_head delayed_works; /* L: delayed works */
180 * Structure used to wait for workqueue flush.
183 struct list_head list; /* F: list of flushers */
184 int flush_color; /* F: flush color waiting for */
185 struct completion done; /* flush completion */
189 * All cpumasks are assumed to be always set on UP and thus can't be
190 * used to determine whether there's something to be done.
193 typedef cpumask_var_t mayday_mask_t;
194 #define mayday_test_and_set_cpu(cpu, mask) \
195 cpumask_test_and_set_cpu((cpu), (mask))
196 #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
197 #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
198 #define alloc_mayday_mask(maskp, gfp) alloc_cpumask_var((maskp), (gfp))
199 #define free_mayday_mask(mask) free_cpumask_var((mask))
201 typedef unsigned long mayday_mask_t;
202 #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
203 #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
204 #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
205 #define alloc_mayday_mask(maskp, gfp) true
206 #define free_mayday_mask(mask) do { } while (0)
210 * The externally visible workqueue abstraction is an array of
211 * per-CPU workqueues:
213 struct workqueue_struct {
214 unsigned int flags; /* I: WQ_* flags */
216 struct cpu_workqueue_struct __percpu *pcpu;
217 struct cpu_workqueue_struct *single;
219 } cpu_wq; /* I: cwq's */
220 struct list_head list; /* W: list of all workqueues */
222 struct mutex flush_mutex; /* protects wq flushing */
223 int work_color; /* F: current work color */
224 int flush_color; /* F: current flush color */
225 atomic_t nr_cwqs_to_flush; /* flush in progress */
226 struct wq_flusher *first_flusher; /* F: first flusher */
227 struct list_head flusher_queue; /* F: flush waiters */
228 struct list_head flusher_overflow; /* F: flush overflow list */
230 mayday_mask_t mayday_mask; /* cpus requesting rescue */
231 struct worker *rescuer; /* I: rescue worker */
233 int saved_max_active; /* W: saved cwq max_active */
234 const char *name; /* I: workqueue name */
235 #ifdef CONFIG_LOCKDEP
236 struct lockdep_map lockdep_map;
240 struct workqueue_struct *system_wq __read_mostly;
241 struct workqueue_struct *system_long_wq __read_mostly;
242 struct workqueue_struct *system_nrt_wq __read_mostly;
243 struct workqueue_struct *system_unbound_wq __read_mostly;
244 EXPORT_SYMBOL_GPL(system_wq);
245 EXPORT_SYMBOL_GPL(system_long_wq);
246 EXPORT_SYMBOL_GPL(system_nrt_wq);
247 EXPORT_SYMBOL_GPL(system_unbound_wq);
249 #define for_each_busy_worker(worker, i, pos, gcwq) \
250 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
251 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
253 static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
256 if (cpu < nr_cpu_ids) {
258 cpu = cpumask_next(cpu, mask);
259 if (cpu < nr_cpu_ids)
263 return WORK_CPU_UNBOUND;
265 return WORK_CPU_NONE;
268 static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
269 struct workqueue_struct *wq)
271 return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
277 * An extra gcwq is defined for an invalid cpu number
278 * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
279 * specific CPU. The following iterators are similar to
280 * for_each_*_cpu() iterators but also considers the unbound gcwq.
282 * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
283 * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
284 * for_each_cwq_cpu() : possible CPUs for bound workqueues,
285 * WORK_CPU_UNBOUND for unbound workqueues
287 #define for_each_gcwq_cpu(cpu) \
288 for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
289 (cpu) < WORK_CPU_NONE; \
290 (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
292 #define for_each_online_gcwq_cpu(cpu) \
293 for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
294 (cpu) < WORK_CPU_NONE; \
295 (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
297 #define for_each_cwq_cpu(cpu, wq) \
298 for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
299 (cpu) < WORK_CPU_NONE; \
300 (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
302 #ifdef CONFIG_DEBUG_OBJECTS_WORK
304 static struct debug_obj_descr work_debug_descr;
307 * fixup_init is called when:
308 * - an active object is initialized
310 static int work_fixup_init(void *addr, enum debug_obj_state state)
312 struct work_struct *work = addr;
315 case ODEBUG_STATE_ACTIVE:
316 cancel_work_sync(work);
317 debug_object_init(work, &work_debug_descr);
325 * fixup_activate is called when:
326 * - an active object is activated
327 * - an unknown object is activated (might be a statically initialized object)
329 static int work_fixup_activate(void *addr, enum debug_obj_state state)
331 struct work_struct *work = addr;
335 case ODEBUG_STATE_NOTAVAILABLE:
337 * This is not really a fixup. The work struct was
338 * statically initialized. We just make sure that it
339 * is tracked in the object tracker.
341 if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
342 debug_object_init(work, &work_debug_descr);
343 debug_object_activate(work, &work_debug_descr);
349 case ODEBUG_STATE_ACTIVE:
358 * fixup_free is called when:
359 * - an active object is freed
361 static int work_fixup_free(void *addr, enum debug_obj_state state)
363 struct work_struct *work = addr;
366 case ODEBUG_STATE_ACTIVE:
367 cancel_work_sync(work);
368 debug_object_free(work, &work_debug_descr);
375 static struct debug_obj_descr work_debug_descr = {
376 .name = "work_struct",
377 .fixup_init = work_fixup_init,
378 .fixup_activate = work_fixup_activate,
379 .fixup_free = work_fixup_free,
382 static inline void debug_work_activate(struct work_struct *work)
384 debug_object_activate(work, &work_debug_descr);
387 static inline void debug_work_deactivate(struct work_struct *work)
389 debug_object_deactivate(work, &work_debug_descr);
392 void __init_work(struct work_struct *work, int onstack)
395 debug_object_init_on_stack(work, &work_debug_descr);
397 debug_object_init(work, &work_debug_descr);
399 EXPORT_SYMBOL_GPL(__init_work);
401 void destroy_work_on_stack(struct work_struct *work)
403 debug_object_free(work, &work_debug_descr);
405 EXPORT_SYMBOL_GPL(destroy_work_on_stack);
408 static inline void debug_work_activate(struct work_struct *work) { }
409 static inline void debug_work_deactivate(struct work_struct *work) { }
412 /* Serializes the accesses to the list of workqueues. */
413 static DEFINE_SPINLOCK(workqueue_lock);
414 static LIST_HEAD(workqueues);
415 static bool workqueue_freezing; /* W: have wqs started freezing? */
418 * The almighty global cpu workqueues. nr_running is the only field
419 * which is expected to be used frequently by other cpus via
420 * try_to_wake_up(). Put it in a separate cacheline.
422 static DEFINE_PER_CPU(struct global_cwq, global_cwq);
423 static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);
426 * Global cpu workqueue and nr_running counter for unbound gcwq. The
427 * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
428 * workers have WORKER_UNBOUND set.
430 static struct global_cwq unbound_global_cwq;
431 static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */
433 static int worker_thread(void *__worker);
435 static struct global_cwq *get_gcwq(unsigned int cpu)
437 if (cpu != WORK_CPU_UNBOUND)
438 return &per_cpu(global_cwq, cpu);
440 return &unbound_global_cwq;
443 static atomic_t *get_gcwq_nr_running(unsigned int cpu)
445 if (cpu != WORK_CPU_UNBOUND)
446 return &per_cpu(gcwq_nr_running, cpu);
448 return &unbound_gcwq_nr_running;
451 static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
452 struct workqueue_struct *wq)
454 if (!(wq->flags & WQ_UNBOUND)) {
455 if (likely(cpu < nr_cpu_ids)) {
457 return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
459 return wq->cpu_wq.single;
462 } else if (likely(cpu == WORK_CPU_UNBOUND))
463 return wq->cpu_wq.single;
467 static unsigned int work_color_to_flags(int color)
469 return color << WORK_STRUCT_COLOR_SHIFT;
472 static int get_work_color(struct work_struct *work)
474 return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
475 ((1 << WORK_STRUCT_COLOR_BITS) - 1);
478 static int work_next_color(int color)
480 return (color + 1) % WORK_NR_COLORS;
484 * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
485 * work is on queue. Once execution starts, WORK_STRUCT_CWQ is
486 * cleared and the work data contains the cpu number it was last on.
488 * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
489 * cwq, cpu or clear work->data. These functions should only be
490 * called while the work is owned - ie. while the PENDING bit is set.
492 * get_work_[g]cwq() can be used to obtain the gcwq or cwq
493 * corresponding to a work. gcwq is available once the work has been
494 * queued anywhere after initialization. cwq is available only from
495 * queueing until execution starts.
497 static inline void set_work_data(struct work_struct *work, unsigned long data,
500 BUG_ON(!work_pending(work));
501 atomic_long_set(&work->data, data | flags | work_static(work));
504 static void set_work_cwq(struct work_struct *work,
505 struct cpu_workqueue_struct *cwq,
506 unsigned long extra_flags)
508 set_work_data(work, (unsigned long)cwq,
509 WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
512 static void set_work_cpu(struct work_struct *work, unsigned int cpu)
514 set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING);
517 static void clear_work_data(struct work_struct *work)
519 set_work_data(work, WORK_STRUCT_NO_CPU, 0);
522 static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
524 unsigned long data = atomic_long_read(&work->data);
526 if (data & WORK_STRUCT_CWQ)
527 return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
532 static struct global_cwq *get_work_gcwq(struct work_struct *work)
534 unsigned long data = atomic_long_read(&work->data);
537 if (data & WORK_STRUCT_CWQ)
538 return ((struct cpu_workqueue_struct *)
539 (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq;
541 cpu = data >> WORK_STRUCT_FLAG_BITS;
542 if (cpu == WORK_CPU_NONE)
545 BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND);
546 return get_gcwq(cpu);
550 * Policy functions. These define the policies on how the global
551 * worker pool is managed. Unless noted otherwise, these functions
552 * assume that they're being called with gcwq->lock held.
555 static bool __need_more_worker(struct global_cwq *gcwq)
557 return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) ||
558 gcwq->flags & GCWQ_HIGHPRI_PENDING;
562 * Need to wake up a worker? Called from anything but currently
565 static bool need_more_worker(struct global_cwq *gcwq)
567 return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq);
570 /* Can I start working? Called from busy but !running workers. */
571 static bool may_start_working(struct global_cwq *gcwq)
573 return gcwq->nr_idle;
576 /* Do I need to keep working? Called from currently running workers. */
577 static bool keep_working(struct global_cwq *gcwq)
579 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
581 return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1;
584 /* Do we need a new worker? Called from manager. */
585 static bool need_to_create_worker(struct global_cwq *gcwq)
587 return need_more_worker(gcwq) && !may_start_working(gcwq);
590 /* Do I need to be the manager? */
591 static bool need_to_manage_workers(struct global_cwq *gcwq)
593 return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS;
596 /* Do we have too many workers and should some go away? */
597 static bool too_many_workers(struct global_cwq *gcwq)
599 bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS;
600 int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */
601 int nr_busy = gcwq->nr_workers - nr_idle;
603 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
610 /* Return the first worker. Safe with preemption disabled */
611 static struct worker *first_worker(struct global_cwq *gcwq)
613 if (unlikely(list_empty(&gcwq->idle_list)))
616 return list_first_entry(&gcwq->idle_list, struct worker, entry);
620 * wake_up_worker - wake up an idle worker
621 * @gcwq: gcwq to wake worker for
623 * Wake up the first idle worker of @gcwq.
626 * spin_lock_irq(gcwq->lock).
628 static void wake_up_worker(struct global_cwq *gcwq)
630 struct worker *worker = first_worker(gcwq);
633 wake_up_process(worker->task);
637 * wq_worker_waking_up - a worker is waking up
638 * @task: task waking up
639 * @cpu: CPU @task is waking up to
641 * This function is called during try_to_wake_up() when a worker is
645 * spin_lock_irq(rq->lock)
647 void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
649 struct worker *worker = kthread_data(task);
651 if (likely(!(worker->flags & WORKER_NOT_RUNNING)))
652 atomic_inc(get_gcwq_nr_running(cpu));
656 * wq_worker_sleeping - a worker is going to sleep
657 * @task: task going to sleep
658 * @cpu: CPU in question, must be the current CPU number
660 * This function is called during schedule() when a busy worker is
661 * going to sleep. Worker on the same cpu can be woken up by
662 * returning pointer to its task.
665 * spin_lock_irq(rq->lock)
668 * Worker task on @cpu to wake up, %NULL if none.
670 struct task_struct *wq_worker_sleeping(struct task_struct *task,
673 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
674 struct global_cwq *gcwq = get_gcwq(cpu);
675 atomic_t *nr_running = get_gcwq_nr_running(cpu);
677 if (unlikely(worker->flags & WORKER_NOT_RUNNING))
680 /* this can only happen on the local cpu */
681 BUG_ON(cpu != raw_smp_processor_id());
684 * The counterpart of the following dec_and_test, implied mb,
685 * worklist not empty test sequence is in insert_work().
686 * Please read comment there.
688 * NOT_RUNNING is clear. This means that trustee is not in
689 * charge and we're running on the local cpu w/ rq lock held
690 * and preemption disabled, which in turn means that none else
691 * could be manipulating idle_list, so dereferencing idle_list
692 * without gcwq lock is safe.
694 if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist))
695 to_wakeup = first_worker(gcwq);
696 return to_wakeup ? to_wakeup->task : NULL;
700 * worker_set_flags - set worker flags and adjust nr_running accordingly
702 * @flags: flags to set
703 * @wakeup: wakeup an idle worker if necessary
705 * Set @flags in @worker->flags and adjust nr_running accordingly. If
706 * nr_running becomes zero and @wakeup is %true, an idle worker is
710 * spin_lock_irq(gcwq->lock)
712 static inline void worker_set_flags(struct worker *worker, unsigned int flags,
715 struct global_cwq *gcwq = worker->gcwq;
717 WARN_ON_ONCE(worker->task != current);
720 * If transitioning into NOT_RUNNING, adjust nr_running and
721 * wake up an idle worker as necessary if requested by
724 if ((flags & WORKER_NOT_RUNNING) &&
725 !(worker->flags & WORKER_NOT_RUNNING)) {
726 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
729 if (atomic_dec_and_test(nr_running) &&
730 !list_empty(&gcwq->worklist))
731 wake_up_worker(gcwq);
733 atomic_dec(nr_running);
736 worker->flags |= flags;
740 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
742 * @flags: flags to clear
744 * Clear @flags in @worker->flags and adjust nr_running accordingly.
747 * spin_lock_irq(gcwq->lock)
749 static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
751 struct global_cwq *gcwq = worker->gcwq;
752 unsigned int oflags = worker->flags;
754 WARN_ON_ONCE(worker->task != current);
756 worker->flags &= ~flags;
758 /* if transitioning out of NOT_RUNNING, increment nr_running */
759 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
760 if (!(worker->flags & WORKER_NOT_RUNNING))
761 atomic_inc(get_gcwq_nr_running(gcwq->cpu));
765 * busy_worker_head - return the busy hash head for a work
766 * @gcwq: gcwq of interest
767 * @work: work to be hashed
769 * Return hash head of @gcwq for @work.
772 * spin_lock_irq(gcwq->lock).
775 * Pointer to the hash head.
777 static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
778 struct work_struct *work)
780 const int base_shift = ilog2(sizeof(struct work_struct));
781 unsigned long v = (unsigned long)work;
783 /* simple shift and fold hash, do we need something better? */
785 v += v >> BUSY_WORKER_HASH_ORDER;
786 v &= BUSY_WORKER_HASH_MASK;
788 return &gcwq->busy_hash[v];
792 * __find_worker_executing_work - find worker which is executing a work
793 * @gcwq: gcwq of interest
794 * @bwh: hash head as returned by busy_worker_head()
795 * @work: work to find worker for
797 * Find a worker which is executing @work on @gcwq. @bwh should be
798 * the hash head obtained by calling busy_worker_head() with the same
802 * spin_lock_irq(gcwq->lock).
805 * Pointer to worker which is executing @work if found, NULL
808 static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,
809 struct hlist_head *bwh,
810 struct work_struct *work)
812 struct worker *worker;
813 struct hlist_node *tmp;
815 hlist_for_each_entry(worker, tmp, bwh, hentry)
816 if (worker->current_work == work)
822 * find_worker_executing_work - find worker which is executing a work
823 * @gcwq: gcwq of interest
824 * @work: work to find worker for
826 * Find a worker which is executing @work on @gcwq. This function is
827 * identical to __find_worker_executing_work() except that this
828 * function calculates @bwh itself.
831 * spin_lock_irq(gcwq->lock).
834 * Pointer to worker which is executing @work if found, NULL
837 static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
838 struct work_struct *work)
840 return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),
845 * gcwq_determine_ins_pos - find insertion position
846 * @gcwq: gcwq of interest
847 * @cwq: cwq a work is being queued for
849 * A work for @cwq is about to be queued on @gcwq, determine insertion
850 * position for the work. If @cwq is for HIGHPRI wq, the work is
851 * queued at the head of the queue but in FIFO order with respect to
852 * other HIGHPRI works; otherwise, at the end of the queue. This
853 * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that
854 * there are HIGHPRI works pending.
857 * spin_lock_irq(gcwq->lock).
860 * Pointer to inserstion position.
862 static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq,
863 struct cpu_workqueue_struct *cwq)
865 struct work_struct *twork;
867 if (likely(!(cwq->wq->flags & WQ_HIGHPRI)))
868 return &gcwq->worklist;
870 list_for_each_entry(twork, &gcwq->worklist, entry) {
871 struct cpu_workqueue_struct *tcwq = get_work_cwq(twork);
873 if (!(tcwq->wq->flags & WQ_HIGHPRI))
877 gcwq->flags |= GCWQ_HIGHPRI_PENDING;
878 return &twork->entry;
882 * insert_work - insert a work into gcwq
883 * @cwq: cwq @work belongs to
884 * @work: work to insert
885 * @head: insertion point
886 * @extra_flags: extra WORK_STRUCT_* flags to set
888 * Insert @work which belongs to @cwq into @gcwq after @head.
889 * @extra_flags is or'd to work_struct flags.
892 * spin_lock_irq(gcwq->lock).
894 static void insert_work(struct cpu_workqueue_struct *cwq,
895 struct work_struct *work, struct list_head *head,
896 unsigned int extra_flags)
898 struct global_cwq *gcwq = cwq->gcwq;
900 /* we own @work, set data and link */
901 set_work_cwq(work, cwq, extra_flags);
904 * Ensure that we get the right work->data if we see the
905 * result of list_add() below, see try_to_grab_pending().
909 list_add_tail(&work->entry, head);
912 * Ensure either worker_sched_deactivated() sees the above
913 * list_add_tail() or we see zero nr_running to avoid workers
914 * lying around lazily while there are works to be processed.
918 if (__need_more_worker(gcwq))
919 wake_up_worker(gcwq);
922 static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
923 struct work_struct *work)
925 struct global_cwq *gcwq;
926 struct cpu_workqueue_struct *cwq;
927 struct list_head *worklist;
930 debug_work_activate(work);
932 /* determine gcwq to use */
933 if (!(wq->flags & WQ_UNBOUND)) {
934 struct global_cwq *last_gcwq;
936 if (unlikely(cpu == WORK_CPU_UNBOUND))
937 cpu = raw_smp_processor_id();
940 * It's multi cpu. If @wq is non-reentrant and @work
941 * was previously on a different cpu, it might still
942 * be running there, in which case the work needs to
943 * be queued on that cpu to guarantee non-reentrance.
945 gcwq = get_gcwq(cpu);
946 if (wq->flags & WQ_NON_REENTRANT &&
947 (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) {
948 struct worker *worker;
950 spin_lock_irqsave(&last_gcwq->lock, flags);
952 worker = find_worker_executing_work(last_gcwq, work);
954 if (worker && worker->current_cwq->wq == wq)
957 /* meh... not running there, queue here */
958 spin_unlock_irqrestore(&last_gcwq->lock, flags);
959 spin_lock_irqsave(&gcwq->lock, flags);
962 spin_lock_irqsave(&gcwq->lock, flags);
964 gcwq = get_gcwq(WORK_CPU_UNBOUND);
965 spin_lock_irqsave(&gcwq->lock, flags);
968 /* gcwq determined, get cwq and queue */
969 cwq = get_cwq(gcwq->cpu, wq);
971 BUG_ON(!list_empty(&work->entry));
973 cwq->nr_in_flight[cwq->work_color]++;
975 if (likely(cwq->nr_active < cwq->max_active)) {
977 worklist = gcwq_determine_ins_pos(gcwq, cwq);
979 worklist = &cwq->delayed_works;
981 insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color));
983 spin_unlock_irqrestore(&gcwq->lock, flags);
987 * queue_work - queue work on a workqueue
988 * @wq: workqueue to use
989 * @work: work to queue
991 * Returns 0 if @work was already on a queue, non-zero otherwise.
993 * We queue the work to the CPU on which it was submitted, but if the CPU dies
994 * it can be processed by another CPU.
996 int queue_work(struct workqueue_struct *wq, struct work_struct *work)
1000 ret = queue_work_on(get_cpu(), wq, work);
1005 EXPORT_SYMBOL_GPL(queue_work);
1008 * queue_work_on - queue work on specific cpu
1009 * @cpu: CPU number to execute work on
1010 * @wq: workqueue to use
1011 * @work: work to queue
1013 * Returns 0 if @work was already on a queue, non-zero otherwise.
1015 * We queue the work to a specific CPU, the caller must ensure it
1019 queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
1023 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1024 __queue_work(cpu, wq, work);
1029 EXPORT_SYMBOL_GPL(queue_work_on);
1031 static void delayed_work_timer_fn(unsigned long __data)
1033 struct delayed_work *dwork = (struct delayed_work *)__data;
1034 struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
1036 __queue_work(smp_processor_id(), cwq->wq, &dwork->work);
1040 * queue_delayed_work - queue work on a workqueue after delay
1041 * @wq: workqueue to use
1042 * @dwork: delayable work to queue
1043 * @delay: number of jiffies to wait before queueing
1045 * Returns 0 if @work was already on a queue, non-zero otherwise.
1047 int queue_delayed_work(struct workqueue_struct *wq,
1048 struct delayed_work *dwork, unsigned long delay)
1051 return queue_work(wq, &dwork->work);
1053 return queue_delayed_work_on(-1, wq, dwork, delay);
1055 EXPORT_SYMBOL_GPL(queue_delayed_work);
1058 * queue_delayed_work_on - queue work on specific CPU after delay
1059 * @cpu: CPU number to execute work on
1060 * @wq: workqueue to use
1061 * @dwork: work to queue
1062 * @delay: number of jiffies to wait before queueing
1064 * Returns 0 if @work was already on a queue, non-zero otherwise.
1066 int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1067 struct delayed_work *dwork, unsigned long delay)
1070 struct timer_list *timer = &dwork->timer;
1071 struct work_struct *work = &dwork->work;
1073 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1076 BUG_ON(timer_pending(timer));
1077 BUG_ON(!list_empty(&work->entry));
1079 timer_stats_timer_set_start_info(&dwork->timer);
1082 * This stores cwq for the moment, for the timer_fn.
1083 * Note that the work's gcwq is preserved to allow
1084 * reentrance detection for delayed works.
1086 if (!(wq->flags & WQ_UNBOUND)) {
1087 struct global_cwq *gcwq = get_work_gcwq(work);
1089 if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND)
1092 lcpu = raw_smp_processor_id();
1094 lcpu = WORK_CPU_UNBOUND;
1096 set_work_cwq(work, get_cwq(lcpu, wq), 0);
1098 timer->expires = jiffies + delay;
1099 timer->data = (unsigned long)dwork;
1100 timer->function = delayed_work_timer_fn;
1102 if (unlikely(cpu >= 0))
1103 add_timer_on(timer, cpu);
1110 EXPORT_SYMBOL_GPL(queue_delayed_work_on);
1113 * worker_enter_idle - enter idle state
1114 * @worker: worker which is entering idle state
1116 * @worker is entering idle state. Update stats and idle timer if
1120 * spin_lock_irq(gcwq->lock).
1122 static void worker_enter_idle(struct worker *worker)
1124 struct global_cwq *gcwq = worker->gcwq;
1126 BUG_ON(worker->flags & WORKER_IDLE);
1127 BUG_ON(!list_empty(&worker->entry) &&
1128 (worker->hentry.next || worker->hentry.pprev));
1130 /* can't use worker_set_flags(), also called from start_worker() */
1131 worker->flags |= WORKER_IDLE;
1133 worker->last_active = jiffies;
1135 /* idle_list is LIFO */
1136 list_add(&worker->entry, &gcwq->idle_list);
1138 if (likely(!(worker->flags & WORKER_ROGUE))) {
1139 if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer))
1140 mod_timer(&gcwq->idle_timer,
1141 jiffies + IDLE_WORKER_TIMEOUT);
1143 wake_up_all(&gcwq->trustee_wait);
1145 /* sanity check nr_running */
1146 WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle &&
1147 atomic_read(get_gcwq_nr_running(gcwq->cpu)));
1151 * worker_leave_idle - leave idle state
1152 * @worker: worker which is leaving idle state
1154 * @worker is leaving idle state. Update stats.
1157 * spin_lock_irq(gcwq->lock).
1159 static void worker_leave_idle(struct worker *worker)
1161 struct global_cwq *gcwq = worker->gcwq;
1163 BUG_ON(!(worker->flags & WORKER_IDLE));
1164 worker_clr_flags(worker, WORKER_IDLE);
1166 list_del_init(&worker->entry);
1170 * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
1173 * Works which are scheduled while the cpu is online must at least be
1174 * scheduled to a worker which is bound to the cpu so that if they are
1175 * flushed from cpu callbacks while cpu is going down, they are
1176 * guaranteed to execute on the cpu.
1178 * This function is to be used by rogue workers and rescuers to bind
1179 * themselves to the target cpu and may race with cpu going down or
1180 * coming online. kthread_bind() can't be used because it may put the
1181 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1182 * verbatim as it's best effort and blocking and gcwq may be
1183 * [dis]associated in the meantime.
1185 * This function tries set_cpus_allowed() and locks gcwq and verifies
1186 * the binding against GCWQ_DISASSOCIATED which is set during
1187 * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters
1188 * idle state or fetches works without dropping lock, it can guarantee
1189 * the scheduling requirement described in the first paragraph.
1192 * Might sleep. Called without any lock but returns with gcwq->lock
1196 * %true if the associated gcwq is online (@worker is successfully
1197 * bound), %false if offline.
1199 static bool worker_maybe_bind_and_lock(struct worker *worker)
1201 struct global_cwq *gcwq = worker->gcwq;
1202 struct task_struct *task = worker->task;
1206 * The following call may fail, succeed or succeed
1207 * without actually migrating the task to the cpu if
1208 * it races with cpu hotunplug operation. Verify
1209 * against GCWQ_DISASSOCIATED.
1211 if (!(gcwq->flags & GCWQ_DISASSOCIATED))
1212 set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
1214 spin_lock_irq(&gcwq->lock);
1215 if (gcwq->flags & GCWQ_DISASSOCIATED)
1217 if (task_cpu(task) == gcwq->cpu &&
1218 cpumask_equal(¤t->cpus_allowed,
1219 get_cpu_mask(gcwq->cpu)))
1221 spin_unlock_irq(&gcwq->lock);
1223 /* CPU has come up inbetween, retry migration */
1229 * Function for worker->rebind_work used to rebind rogue busy workers
1230 * to the associated cpu which is coming back online. This is
1231 * scheduled by cpu up but can race with other cpu hotplug operations
1232 * and may be executed twice without intervening cpu down.
1234 static void worker_rebind_fn(struct work_struct *work)
1236 struct worker *worker = container_of(work, struct worker, rebind_work);
1237 struct global_cwq *gcwq = worker->gcwq;
1239 if (worker_maybe_bind_and_lock(worker))
1240 worker_clr_flags(worker, WORKER_REBIND);
1242 spin_unlock_irq(&gcwq->lock);
1245 static struct worker *alloc_worker(void)
1247 struct worker *worker;
1249 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
1251 INIT_LIST_HEAD(&worker->entry);
1252 INIT_LIST_HEAD(&worker->scheduled);
1253 INIT_WORK(&worker->rebind_work, worker_rebind_fn);
1254 /* on creation a worker is in !idle && prep state */
1255 worker->flags = WORKER_PREP;
1261 * create_worker - create a new workqueue worker
1262 * @gcwq: gcwq the new worker will belong to
1263 * @bind: whether to set affinity to @cpu or not
1265 * Create a new worker which is bound to @gcwq. The returned worker
1266 * can be started by calling start_worker() or destroyed using
1270 * Might sleep. Does GFP_KERNEL allocations.
1273 * Pointer to the newly created worker.
1275 static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
1277 bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND;
1278 struct worker *worker = NULL;
1281 spin_lock_irq(&gcwq->lock);
1282 while (ida_get_new(&gcwq->worker_ida, &id)) {
1283 spin_unlock_irq(&gcwq->lock);
1284 if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL))
1286 spin_lock_irq(&gcwq->lock);
1288 spin_unlock_irq(&gcwq->lock);
1290 worker = alloc_worker();
1294 worker->gcwq = gcwq;
1297 if (!on_unbound_cpu)
1298 worker->task = kthread_create(worker_thread, worker,
1299 "kworker/%u:%d", gcwq->cpu, id);
1301 worker->task = kthread_create(worker_thread, worker,
1302 "kworker/u:%d", id);
1303 if (IS_ERR(worker->task))
1307 * A rogue worker will become a regular one if CPU comes
1308 * online later on. Make sure every worker has
1309 * PF_THREAD_BOUND set.
1311 if (bind && !on_unbound_cpu)
1312 kthread_bind(worker->task, gcwq->cpu);
1314 worker->task->flags |= PF_THREAD_BOUND;
1316 worker->flags |= WORKER_UNBOUND;
1322 spin_lock_irq(&gcwq->lock);
1323 ida_remove(&gcwq->worker_ida, id);
1324 spin_unlock_irq(&gcwq->lock);
1331 * start_worker - start a newly created worker
1332 * @worker: worker to start
1334 * Make the gcwq aware of @worker and start it.
1337 * spin_lock_irq(gcwq->lock).
1339 static void start_worker(struct worker *worker)
1341 worker->flags |= WORKER_STARTED;
1342 worker->gcwq->nr_workers++;
1343 worker_enter_idle(worker);
1344 wake_up_process(worker->task);
1348 * destroy_worker - destroy a workqueue worker
1349 * @worker: worker to be destroyed
1351 * Destroy @worker and adjust @gcwq stats accordingly.
1354 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1356 static void destroy_worker(struct worker *worker)
1358 struct global_cwq *gcwq = worker->gcwq;
1359 int id = worker->id;
1361 /* sanity check frenzy */
1362 BUG_ON(worker->current_work);
1363 BUG_ON(!list_empty(&worker->scheduled));
1365 if (worker->flags & WORKER_STARTED)
1367 if (worker->flags & WORKER_IDLE)
1370 list_del_init(&worker->entry);
1371 worker->flags |= WORKER_DIE;
1373 spin_unlock_irq(&gcwq->lock);
1375 kthread_stop(worker->task);
1378 spin_lock_irq(&gcwq->lock);
1379 ida_remove(&gcwq->worker_ida, id);
1382 static void idle_worker_timeout(unsigned long __gcwq)
1384 struct global_cwq *gcwq = (void *)__gcwq;
1386 spin_lock_irq(&gcwq->lock);
1388 if (too_many_workers(gcwq)) {
1389 struct worker *worker;
1390 unsigned long expires;
1392 /* idle_list is kept in LIFO order, check the last one */
1393 worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
1394 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1396 if (time_before(jiffies, expires))
1397 mod_timer(&gcwq->idle_timer, expires);
1399 /* it's been idle for too long, wake up manager */
1400 gcwq->flags |= GCWQ_MANAGE_WORKERS;
1401 wake_up_worker(gcwq);
1405 spin_unlock_irq(&gcwq->lock);
1408 static bool send_mayday(struct work_struct *work)
1410 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1411 struct workqueue_struct *wq = cwq->wq;
1414 if (!(wq->flags & WQ_RESCUER))
1417 /* mayday mayday mayday */
1418 cpu = cwq->gcwq->cpu;
1419 /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
1420 if (cpu == WORK_CPU_UNBOUND)
1422 if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask))
1423 wake_up_process(wq->rescuer->task);
1427 static void gcwq_mayday_timeout(unsigned long __gcwq)
1429 struct global_cwq *gcwq = (void *)__gcwq;
1430 struct work_struct *work;
1432 spin_lock_irq(&gcwq->lock);
1434 if (need_to_create_worker(gcwq)) {
1436 * We've been trying to create a new worker but
1437 * haven't been successful. We might be hitting an
1438 * allocation deadlock. Send distress signals to
1441 list_for_each_entry(work, &gcwq->worklist, entry)
1445 spin_unlock_irq(&gcwq->lock);
1447 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL);
1451 * maybe_create_worker - create a new worker if necessary
1452 * @gcwq: gcwq to create a new worker for
1454 * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to
1455 * have at least one idle worker on return from this function. If
1456 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1457 * sent to all rescuers with works scheduled on @gcwq to resolve
1458 * possible allocation deadlock.
1460 * On return, need_to_create_worker() is guaranteed to be false and
1461 * may_start_working() true.
1464 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1465 * multiple times. Does GFP_KERNEL allocations. Called only from
1469 * false if no action was taken and gcwq->lock stayed locked, true
1472 static bool maybe_create_worker(struct global_cwq *gcwq)
1474 if (!need_to_create_worker(gcwq))
1477 spin_unlock_irq(&gcwq->lock);
1479 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1480 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
1483 struct worker *worker;
1485 worker = create_worker(gcwq, true);
1487 del_timer_sync(&gcwq->mayday_timer);
1488 spin_lock_irq(&gcwq->lock);
1489 start_worker(worker);
1490 BUG_ON(need_to_create_worker(gcwq));
1494 if (!need_to_create_worker(gcwq))
1497 __set_current_state(TASK_INTERRUPTIBLE);
1498 schedule_timeout(CREATE_COOLDOWN);
1500 if (!need_to_create_worker(gcwq))
1504 del_timer_sync(&gcwq->mayday_timer);
1505 spin_lock_irq(&gcwq->lock);
1506 if (need_to_create_worker(gcwq))
1512 * maybe_destroy_worker - destroy workers which have been idle for a while
1513 * @gcwq: gcwq to destroy workers for
1515 * Destroy @gcwq workers which have been idle for longer than
1516 * IDLE_WORKER_TIMEOUT.
1519 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1520 * multiple times. Called only from manager.
1523 * false if no action was taken and gcwq->lock stayed locked, true
1526 static bool maybe_destroy_workers(struct global_cwq *gcwq)
1530 while (too_many_workers(gcwq)) {
1531 struct worker *worker;
1532 unsigned long expires;
1534 worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
1535 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1537 if (time_before(jiffies, expires)) {
1538 mod_timer(&gcwq->idle_timer, expires);
1542 destroy_worker(worker);
1550 * manage_workers - manage worker pool
1553 * Assume the manager role and manage gcwq worker pool @worker belongs
1554 * to. At any given time, there can be only zero or one manager per
1555 * gcwq. The exclusion is handled automatically by this function.
1557 * The caller can safely start processing works on false return. On
1558 * true return, it's guaranteed that need_to_create_worker() is false
1559 * and may_start_working() is true.
1562 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1563 * multiple times. Does GFP_KERNEL allocations.
1566 * false if no action was taken and gcwq->lock stayed locked, true if
1567 * some action was taken.
1569 static bool manage_workers(struct worker *worker)
1571 struct global_cwq *gcwq = worker->gcwq;
1574 if (gcwq->flags & GCWQ_MANAGING_WORKERS)
1577 gcwq->flags &= ~GCWQ_MANAGE_WORKERS;
1578 gcwq->flags |= GCWQ_MANAGING_WORKERS;
1581 * Destroy and then create so that may_start_working() is true
1584 ret |= maybe_destroy_workers(gcwq);
1585 ret |= maybe_create_worker(gcwq);
1587 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
1590 * The trustee might be waiting to take over the manager
1591 * position, tell it we're done.
1593 if (unlikely(gcwq->trustee))
1594 wake_up_all(&gcwq->trustee_wait);
1600 * move_linked_works - move linked works to a list
1601 * @work: start of series of works to be scheduled
1602 * @head: target list to append @work to
1603 * @nextp: out paramter for nested worklist walking
1605 * Schedule linked works starting from @work to @head. Work series to
1606 * be scheduled starts at @work and includes any consecutive work with
1607 * WORK_STRUCT_LINKED set in its predecessor.
1609 * If @nextp is not NULL, it's updated to point to the next work of
1610 * the last scheduled work. This allows move_linked_works() to be
1611 * nested inside outer list_for_each_entry_safe().
1614 * spin_lock_irq(gcwq->lock).
1616 static void move_linked_works(struct work_struct *work, struct list_head *head,
1617 struct work_struct **nextp)
1619 struct work_struct *n;
1622 * Linked worklist will always end before the end of the list,
1623 * use NULL for list head.
1625 list_for_each_entry_safe_from(work, n, NULL, entry) {
1626 list_move_tail(&work->entry, head);
1627 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1632 * If we're already inside safe list traversal and have moved
1633 * multiple works to the scheduled queue, the next position
1634 * needs to be updated.
1640 static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
1642 struct work_struct *work = list_first_entry(&cwq->delayed_works,
1643 struct work_struct, entry);
1644 struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
1646 move_linked_works(work, pos, NULL);
1651 * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
1652 * @cwq: cwq of interest
1653 * @color: color of work which left the queue
1655 * A work either has completed or is removed from pending queue,
1656 * decrement nr_in_flight of its cwq and handle workqueue flushing.
1659 * spin_lock_irq(gcwq->lock).
1661 static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
1663 /* ignore uncolored works */
1664 if (color == WORK_NO_COLOR)
1667 cwq->nr_in_flight[color]--;
1670 if (!list_empty(&cwq->delayed_works)) {
1671 /* one down, submit a delayed one */
1672 if (cwq->nr_active < cwq->max_active)
1673 cwq_activate_first_delayed(cwq);
1676 /* is flush in progress and are we at the flushing tip? */
1677 if (likely(cwq->flush_color != color))
1680 /* are there still in-flight works? */
1681 if (cwq->nr_in_flight[color])
1684 /* this cwq is done, clear flush_color */
1685 cwq->flush_color = -1;
1688 * If this was the last cwq, wake up the first flusher. It
1689 * will handle the rest.
1691 if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
1692 complete(&cwq->wq->first_flusher->done);
1696 * process_one_work - process single work
1698 * @work: work to process
1700 * Process @work. This function contains all the logics necessary to
1701 * process a single work including synchronization against and
1702 * interaction with other workers on the same cpu, queueing and
1703 * flushing. As long as context requirement is met, any worker can
1704 * call this function to process a work.
1707 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1709 static void process_one_work(struct worker *worker, struct work_struct *work)
1711 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1712 struct global_cwq *gcwq = cwq->gcwq;
1713 struct hlist_head *bwh = busy_worker_head(gcwq, work);
1714 bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
1715 work_func_t f = work->func;
1717 struct worker *collision;
1718 #ifdef CONFIG_LOCKDEP
1720 * It is permissible to free the struct work_struct from
1721 * inside the function that is called from it, this we need to
1722 * take into account for lockdep too. To avoid bogus "held
1723 * lock freed" warnings as well as problems when looking into
1724 * work->lockdep_map, make a copy and use that here.
1726 struct lockdep_map lockdep_map = work->lockdep_map;
1729 * A single work shouldn't be executed concurrently by
1730 * multiple workers on a single cpu. Check whether anyone is
1731 * already processing the work. If so, defer the work to the
1732 * currently executing one.
1734 collision = __find_worker_executing_work(gcwq, bwh, work);
1735 if (unlikely(collision)) {
1736 move_linked_works(work, &collision->scheduled, NULL);
1740 /* claim and process */
1741 debug_work_deactivate(work);
1742 hlist_add_head(&worker->hentry, bwh);
1743 worker->current_work = work;
1744 worker->current_cwq = cwq;
1745 work_color = get_work_color(work);
1747 /* record the current cpu number in the work data and dequeue */
1748 set_work_cpu(work, gcwq->cpu);
1749 list_del_init(&work->entry);
1752 * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI,
1753 * wake up another worker; otherwise, clear HIGHPRI_PENDING.
1755 if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) {
1756 struct work_struct *nwork = list_first_entry(&gcwq->worklist,
1757 struct work_struct, entry);
1759 if (!list_empty(&gcwq->worklist) &&
1760 get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI)
1761 wake_up_worker(gcwq);
1763 gcwq->flags &= ~GCWQ_HIGHPRI_PENDING;
1767 * CPU intensive works don't participate in concurrency
1768 * management. They're the scheduler's responsibility.
1770 if (unlikely(cpu_intensive))
1771 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
1773 spin_unlock_irq(&gcwq->lock);
1775 work_clear_pending(work);
1776 lock_map_acquire(&cwq->wq->lockdep_map);
1777 lock_map_acquire(&lockdep_map);
1779 lock_map_release(&lockdep_map);
1780 lock_map_release(&cwq->wq->lockdep_map);
1782 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
1783 printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
1785 current->comm, preempt_count(), task_pid_nr(current));
1786 printk(KERN_ERR " last function: ");
1787 print_symbol("%s\n", (unsigned long)f);
1788 debug_show_held_locks(current);
1792 spin_lock_irq(&gcwq->lock);
1794 /* clear cpu intensive status */
1795 if (unlikely(cpu_intensive))
1796 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
1798 /* we're done with it, release */
1799 hlist_del_init(&worker->hentry);
1800 worker->current_work = NULL;
1801 worker->current_cwq = NULL;
1802 cwq_dec_nr_in_flight(cwq, work_color);
1806 * process_scheduled_works - process scheduled works
1809 * Process all scheduled works. Please note that the scheduled list
1810 * may change while processing a work, so this function repeatedly
1811 * fetches a work from the top and executes it.
1814 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1817 static void process_scheduled_works(struct worker *worker)
1819 while (!list_empty(&worker->scheduled)) {
1820 struct work_struct *work = list_first_entry(&worker->scheduled,
1821 struct work_struct, entry);
1822 process_one_work(worker, work);
1827 * worker_thread - the worker thread function
1830 * The gcwq worker thread function. There's a single dynamic pool of
1831 * these per each cpu. These workers process all works regardless of
1832 * their specific target workqueue. The only exception is works which
1833 * belong to workqueues with a rescuer which will be explained in
1836 static int worker_thread(void *__worker)
1838 struct worker *worker = __worker;
1839 struct global_cwq *gcwq = worker->gcwq;
1841 /* tell the scheduler that this is a workqueue worker */
1842 worker->task->flags |= PF_WQ_WORKER;
1844 spin_lock_irq(&gcwq->lock);
1846 /* DIE can be set only while we're idle, checking here is enough */
1847 if (worker->flags & WORKER_DIE) {
1848 spin_unlock_irq(&gcwq->lock);
1849 worker->task->flags &= ~PF_WQ_WORKER;
1853 worker_leave_idle(worker);
1855 /* no more worker necessary? */
1856 if (!need_more_worker(gcwq))
1859 /* do we need to manage? */
1860 if (unlikely(!may_start_working(gcwq)) && manage_workers(worker))
1864 * ->scheduled list can only be filled while a worker is
1865 * preparing to process a work or actually processing it.
1866 * Make sure nobody diddled with it while I was sleeping.
1868 BUG_ON(!list_empty(&worker->scheduled));
1871 * When control reaches this point, we're guaranteed to have
1872 * at least one idle worker or that someone else has already
1873 * assumed the manager role.
1875 worker_clr_flags(worker, WORKER_PREP);
1878 struct work_struct *work =
1879 list_first_entry(&gcwq->worklist,
1880 struct work_struct, entry);
1882 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
1883 /* optimization path, not strictly necessary */
1884 process_one_work(worker, work);
1885 if (unlikely(!list_empty(&worker->scheduled)))
1886 process_scheduled_works(worker);
1888 move_linked_works(work, &worker->scheduled, NULL);
1889 process_scheduled_works(worker);
1891 } while (keep_working(gcwq));
1893 worker_set_flags(worker, WORKER_PREP, false);
1895 if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker))
1899 * gcwq->lock is held and there's no work to process and no
1900 * need to manage, sleep. Workers are woken up only while
1901 * holding gcwq->lock or from local cpu, so setting the
1902 * current state before releasing gcwq->lock is enough to
1903 * prevent losing any event.
1905 worker_enter_idle(worker);
1906 __set_current_state(TASK_INTERRUPTIBLE);
1907 spin_unlock_irq(&gcwq->lock);
1913 * rescuer_thread - the rescuer thread function
1914 * @__wq: the associated workqueue
1916 * Workqueue rescuer thread function. There's one rescuer for each
1917 * workqueue which has WQ_RESCUER set.
1919 * Regular work processing on a gcwq may block trying to create a new
1920 * worker which uses GFP_KERNEL allocation which has slight chance of
1921 * developing into deadlock if some works currently on the same queue
1922 * need to be processed to satisfy the GFP_KERNEL allocation. This is
1923 * the problem rescuer solves.
1925 * When such condition is possible, the gcwq summons rescuers of all
1926 * workqueues which have works queued on the gcwq and let them process
1927 * those works so that forward progress can be guaranteed.
1929 * This should happen rarely.
1931 static int rescuer_thread(void *__wq)
1933 struct workqueue_struct *wq = __wq;
1934 struct worker *rescuer = wq->rescuer;
1935 struct list_head *scheduled = &rescuer->scheduled;
1936 bool is_unbound = wq->flags & WQ_UNBOUND;
1939 set_user_nice(current, RESCUER_NICE_LEVEL);
1941 set_current_state(TASK_INTERRUPTIBLE);
1943 if (kthread_should_stop())
1947 * See whether any cpu is asking for help. Unbounded
1948 * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
1950 for_each_mayday_cpu(cpu, wq->mayday_mask) {
1951 unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
1952 struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
1953 struct global_cwq *gcwq = cwq->gcwq;
1954 struct work_struct *work, *n;
1956 __set_current_state(TASK_RUNNING);
1957 mayday_clear_cpu(cpu, wq->mayday_mask);
1959 /* migrate to the target cpu if possible */
1960 rescuer->gcwq = gcwq;
1961 worker_maybe_bind_and_lock(rescuer);
1964 * Slurp in all works issued via this workqueue and
1967 BUG_ON(!list_empty(&rescuer->scheduled));
1968 list_for_each_entry_safe(work, n, &gcwq->worklist, entry)
1969 if (get_work_cwq(work) == cwq)
1970 move_linked_works(work, scheduled, &n);
1972 process_scheduled_works(rescuer);
1973 spin_unlock_irq(&gcwq->lock);
1981 struct work_struct work;
1982 struct completion done;
1985 static void wq_barrier_func(struct work_struct *work)
1987 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
1988 complete(&barr->done);
1992 * insert_wq_barrier - insert a barrier work
1993 * @cwq: cwq to insert barrier into
1994 * @barr: wq_barrier to insert
1995 * @target: target work to attach @barr to
1996 * @worker: worker currently executing @target, NULL if @target is not executing
1998 * @barr is linked to @target such that @barr is completed only after
1999 * @target finishes execution. Please note that the ordering
2000 * guarantee is observed only with respect to @target and on the local
2003 * Currently, a queued barrier can't be canceled. This is because
2004 * try_to_grab_pending() can't determine whether the work to be
2005 * grabbed is at the head of the queue and thus can't clear LINKED
2006 * flag of the previous work while there must be a valid next work
2007 * after a work with LINKED flag set.
2009 * Note that when @worker is non-NULL, @target may be modified
2010 * underneath us, so we can't reliably determine cwq from @target.
2013 * spin_lock_irq(gcwq->lock).
2015 static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
2016 struct wq_barrier *barr,
2017 struct work_struct *target, struct worker *worker)
2019 struct list_head *head;
2020 unsigned int linked = 0;
2023 * debugobject calls are safe here even with gcwq->lock locked
2024 * as we know for sure that this will not trigger any of the
2025 * checks and call back into the fixup functions where we
2028 INIT_WORK_ON_STACK(&barr->work, wq_barrier_func);
2029 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
2030 init_completion(&barr->done);
2033 * If @target is currently being executed, schedule the
2034 * barrier to the worker; otherwise, put it after @target.
2037 head = worker->scheduled.next;
2039 unsigned long *bits = work_data_bits(target);
2041 head = target->entry.next;
2042 /* there can already be other linked works, inherit and set */
2043 linked = *bits & WORK_STRUCT_LINKED;
2044 __set_bit(WORK_STRUCT_LINKED_BIT, bits);
2047 debug_work_activate(&barr->work);
2048 insert_work(cwq, &barr->work, head,
2049 work_color_to_flags(WORK_NO_COLOR) | linked);
2053 * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
2054 * @wq: workqueue being flushed
2055 * @flush_color: new flush color, < 0 for no-op
2056 * @work_color: new work color, < 0 for no-op
2058 * Prepare cwqs for workqueue flushing.
2060 * If @flush_color is non-negative, flush_color on all cwqs should be
2061 * -1. If no cwq has in-flight commands at the specified color, all
2062 * cwq->flush_color's stay at -1 and %false is returned. If any cwq
2063 * has in flight commands, its cwq->flush_color is set to
2064 * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
2065 * wakeup logic is armed and %true is returned.
2067 * The caller should have initialized @wq->first_flusher prior to
2068 * calling this function with non-negative @flush_color. If
2069 * @flush_color is negative, no flush color update is done and %false
2072 * If @work_color is non-negative, all cwqs should have the same
2073 * work_color which is previous to @work_color and all will be
2074 * advanced to @work_color.
2077 * mutex_lock(wq->flush_mutex).
2080 * %true if @flush_color >= 0 and there's something to flush. %false
2083 static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
2084 int flush_color, int work_color)
2089 if (flush_color >= 0) {
2090 BUG_ON(atomic_read(&wq->nr_cwqs_to_flush));
2091 atomic_set(&wq->nr_cwqs_to_flush, 1);
2094 for_each_cwq_cpu(cpu, wq) {
2095 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2096 struct global_cwq *gcwq = cwq->gcwq;
2098 spin_lock_irq(&gcwq->lock);
2100 if (flush_color >= 0) {
2101 BUG_ON(cwq->flush_color != -1);
2103 if (cwq->nr_in_flight[flush_color]) {
2104 cwq->flush_color = flush_color;
2105 atomic_inc(&wq->nr_cwqs_to_flush);
2110 if (work_color >= 0) {
2111 BUG_ON(work_color != work_next_color(cwq->work_color));
2112 cwq->work_color = work_color;
2115 spin_unlock_irq(&gcwq->lock);
2118 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush))
2119 complete(&wq->first_flusher->done);
2125 * flush_workqueue - ensure that any scheduled work has run to completion.
2126 * @wq: workqueue to flush
2128 * Forces execution of the workqueue and blocks until its completion.
2129 * This is typically used in driver shutdown handlers.
2131 * We sleep until all works which were queued on entry have been handled,
2132 * but we are not livelocked by new incoming ones.
2134 void flush_workqueue(struct workqueue_struct *wq)
2136 struct wq_flusher this_flusher = {
2137 .list = LIST_HEAD_INIT(this_flusher.list),
2139 .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
2143 lock_map_acquire(&wq->lockdep_map);
2144 lock_map_release(&wq->lockdep_map);
2146 mutex_lock(&wq->flush_mutex);
2149 * Start-to-wait phase
2151 next_color = work_next_color(wq->work_color);
2153 if (next_color != wq->flush_color) {
2155 * Color space is not full. The current work_color
2156 * becomes our flush_color and work_color is advanced
2159 BUG_ON(!list_empty(&wq->flusher_overflow));
2160 this_flusher.flush_color = wq->work_color;
2161 wq->work_color = next_color;
2163 if (!wq->first_flusher) {
2164 /* no flush in progress, become the first flusher */
2165 BUG_ON(wq->flush_color != this_flusher.flush_color);
2167 wq->first_flusher = &this_flusher;
2169 if (!flush_workqueue_prep_cwqs(wq, wq->flush_color,
2171 /* nothing to flush, done */
2172 wq->flush_color = next_color;
2173 wq->first_flusher = NULL;
2178 BUG_ON(wq->flush_color == this_flusher.flush_color);
2179 list_add_tail(&this_flusher.list, &wq->flusher_queue);
2180 flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
2184 * Oops, color space is full, wait on overflow queue.
2185 * The next flush completion will assign us
2186 * flush_color and transfer to flusher_queue.
2188 list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2191 mutex_unlock(&wq->flush_mutex);
2193 wait_for_completion(&this_flusher.done);
2196 * Wake-up-and-cascade phase
2198 * First flushers are responsible for cascading flushes and
2199 * handling overflow. Non-first flushers can simply return.
2201 if (wq->first_flusher != &this_flusher)
2204 mutex_lock(&wq->flush_mutex);
2206 /* we might have raced, check again with mutex held */
2207 if (wq->first_flusher != &this_flusher)
2210 wq->first_flusher = NULL;
2212 BUG_ON(!list_empty(&this_flusher.list));
2213 BUG_ON(wq->flush_color != this_flusher.flush_color);
2216 struct wq_flusher *next, *tmp;
2218 /* complete all the flushers sharing the current flush color */
2219 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2220 if (next->flush_color != wq->flush_color)
2222 list_del_init(&next->list);
2223 complete(&next->done);
2226 BUG_ON(!list_empty(&wq->flusher_overflow) &&
2227 wq->flush_color != work_next_color(wq->work_color));
2229 /* this flush_color is finished, advance by one */
2230 wq->flush_color = work_next_color(wq->flush_color);
2232 /* one color has been freed, handle overflow queue */
2233 if (!list_empty(&wq->flusher_overflow)) {
2235 * Assign the same color to all overflowed
2236 * flushers, advance work_color and append to
2237 * flusher_queue. This is the start-to-wait
2238 * phase for these overflowed flushers.
2240 list_for_each_entry(tmp, &wq->flusher_overflow, list)
2241 tmp->flush_color = wq->work_color;
2243 wq->work_color = work_next_color(wq->work_color);
2245 list_splice_tail_init(&wq->flusher_overflow,
2246 &wq->flusher_queue);
2247 flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
2250 if (list_empty(&wq->flusher_queue)) {
2251 BUG_ON(wq->flush_color != wq->work_color);
2256 * Need to flush more colors. Make the next flusher
2257 * the new first flusher and arm cwqs.
2259 BUG_ON(wq->flush_color == wq->work_color);
2260 BUG_ON(wq->flush_color != next->flush_color);
2262 list_del_init(&next->list);
2263 wq->first_flusher = next;
2265 if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1))
2269 * Meh... this color is already done, clear first
2270 * flusher and repeat cascading.
2272 wq->first_flusher = NULL;
2276 mutex_unlock(&wq->flush_mutex);
2278 EXPORT_SYMBOL_GPL(flush_workqueue);
2281 * flush_work - block until a work_struct's callback has terminated
2282 * @work: the work which is to be flushed
2284 * Returns false if @work has already terminated.
2286 * It is expected that, prior to calling flush_work(), the caller has
2287 * arranged for the work to not be requeued, otherwise it doesn't make
2288 * sense to use this function.
2290 int flush_work(struct work_struct *work)
2292 struct worker *worker = NULL;
2293 struct global_cwq *gcwq;
2294 struct cpu_workqueue_struct *cwq;
2295 struct wq_barrier barr;
2298 gcwq = get_work_gcwq(work);
2302 spin_lock_irq(&gcwq->lock);
2303 if (!list_empty(&work->entry)) {
2305 * See the comment near try_to_grab_pending()->smp_rmb().
2306 * If it was re-queued to a different gcwq under us, we
2307 * are not going to wait.
2310 cwq = get_work_cwq(work);
2311 if (unlikely(!cwq || gcwq != cwq->gcwq))
2314 worker = find_worker_executing_work(gcwq, work);
2317 cwq = worker->current_cwq;
2320 insert_wq_barrier(cwq, &barr, work, worker);
2321 spin_unlock_irq(&gcwq->lock);
2323 lock_map_acquire(&cwq->wq->lockdep_map);
2324 lock_map_release(&cwq->wq->lockdep_map);
2326 wait_for_completion(&barr.done);
2327 destroy_work_on_stack(&barr.work);
2330 spin_unlock_irq(&gcwq->lock);
2333 EXPORT_SYMBOL_GPL(flush_work);
2336 * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
2337 * so this work can't be re-armed in any way.
2339 static int try_to_grab_pending(struct work_struct *work)
2341 struct global_cwq *gcwq;
2344 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
2348 * The queueing is in progress, or it is already queued. Try to
2349 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
2351 gcwq = get_work_gcwq(work);
2355 spin_lock_irq(&gcwq->lock);
2356 if (!list_empty(&work->entry)) {
2358 * This work is queued, but perhaps we locked the wrong gcwq.
2359 * In that case we must see the new value after rmb(), see
2360 * insert_work()->wmb().
2363 if (gcwq == get_work_gcwq(work)) {
2364 debug_work_deactivate(work);
2365 list_del_init(&work->entry);
2366 cwq_dec_nr_in_flight(get_work_cwq(work),
2367 get_work_color(work));
2371 spin_unlock_irq(&gcwq->lock);
2376 static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
2378 struct wq_barrier barr;
2379 struct worker *worker;
2381 spin_lock_irq(&gcwq->lock);
2383 worker = find_worker_executing_work(gcwq, work);
2384 if (unlikely(worker))
2385 insert_wq_barrier(worker->current_cwq, &barr, work, worker);
2387 spin_unlock_irq(&gcwq->lock);
2389 if (unlikely(worker)) {
2390 wait_for_completion(&barr.done);
2391 destroy_work_on_stack(&barr.work);
2395 static void wait_on_work(struct work_struct *work)
2401 lock_map_acquire(&work->lockdep_map);
2402 lock_map_release(&work->lockdep_map);
2404 for_each_gcwq_cpu(cpu)
2405 wait_on_cpu_work(get_gcwq(cpu), work);
2408 static int __cancel_work_timer(struct work_struct *work,
2409 struct timer_list* timer)
2414 ret = (timer && likely(del_timer(timer)));
2416 ret = try_to_grab_pending(work);
2418 } while (unlikely(ret < 0));
2420 clear_work_data(work);
2425 * cancel_work_sync - block until a work_struct's callback has terminated
2426 * @work: the work which is to be flushed
2428 * Returns true if @work was pending.
2430 * cancel_work_sync() will cancel the work if it is queued. If the work's
2431 * callback appears to be running, cancel_work_sync() will block until it
2434 * It is possible to use this function if the work re-queues itself. It can
2435 * cancel the work even if it migrates to another workqueue, however in that
2436 * case it only guarantees that work->func() has completed on the last queued
2439 * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not
2440 * pending, otherwise it goes into a busy-wait loop until the timer expires.
2442 * The caller must ensure that workqueue_struct on which this work was last
2443 * queued can't be destroyed before this function returns.
2445 int cancel_work_sync(struct work_struct *work)
2447 return __cancel_work_timer(work, NULL);
2449 EXPORT_SYMBOL_GPL(cancel_work_sync);
2452 * cancel_delayed_work_sync - reliably kill off a delayed work.
2453 * @dwork: the delayed work struct
2455 * Returns true if @dwork was pending.
2457 * It is possible to use this function if @dwork rearms itself via queue_work()
2458 * or queue_delayed_work(). See also the comment for cancel_work_sync().
2460 int cancel_delayed_work_sync(struct delayed_work *dwork)
2462 return __cancel_work_timer(&dwork->work, &dwork->timer);
2464 EXPORT_SYMBOL(cancel_delayed_work_sync);
2467 * schedule_work - put work task in global workqueue
2468 * @work: job to be done
2470 * Returns zero if @work was already on the kernel-global workqueue and
2471 * non-zero otherwise.
2473 * This puts a job in the kernel-global workqueue if it was not already
2474 * queued and leaves it in the same position on the kernel-global
2475 * workqueue otherwise.
2477 int schedule_work(struct work_struct *work)
2479 return queue_work(system_wq, work);
2481 EXPORT_SYMBOL(schedule_work);
2484 * schedule_work_on - put work task on a specific cpu
2485 * @cpu: cpu to put the work task on
2486 * @work: job to be done
2488 * This puts a job on a specific cpu
2490 int schedule_work_on(int cpu, struct work_struct *work)
2492 return queue_work_on(cpu, system_wq, work);
2494 EXPORT_SYMBOL(schedule_work_on);
2497 * schedule_delayed_work - put work task in global workqueue after delay
2498 * @dwork: job to be done
2499 * @delay: number of jiffies to wait or 0 for immediate execution
2501 * After waiting for a given time this puts a job in the kernel-global
2504 int schedule_delayed_work(struct delayed_work *dwork,
2505 unsigned long delay)
2507 return queue_delayed_work(system_wq, dwork, delay);
2509 EXPORT_SYMBOL(schedule_delayed_work);
2512 * flush_delayed_work - block until a dwork_struct's callback has terminated
2513 * @dwork: the delayed work which is to be flushed
2515 * Any timeout is cancelled, and any pending work is run immediately.
2517 void flush_delayed_work(struct delayed_work *dwork)
2519 if (del_timer_sync(&dwork->timer)) {
2520 __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq,
2524 flush_work(&dwork->work);
2526 EXPORT_SYMBOL(flush_delayed_work);
2529 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
2531 * @dwork: job to be done
2532 * @delay: number of jiffies to wait
2534 * After waiting for a given time this puts a job in the kernel-global
2535 * workqueue on the specified CPU.
2537 int schedule_delayed_work_on(int cpu,
2538 struct delayed_work *dwork, unsigned long delay)
2540 return queue_delayed_work_on(cpu, system_wq, dwork, delay);
2542 EXPORT_SYMBOL(schedule_delayed_work_on);
2545 * schedule_on_each_cpu - call a function on each online CPU from keventd
2546 * @func: the function to call
2548 * Returns zero on success.
2549 * Returns -ve errno on failure.
2551 * schedule_on_each_cpu() is very slow.
2553 int schedule_on_each_cpu(work_func_t func)
2556 struct work_struct *works;
2558 works = alloc_percpu(struct work_struct);
2564 for_each_online_cpu(cpu) {
2565 struct work_struct *work = per_cpu_ptr(works, cpu);
2567 INIT_WORK(work, func);
2568 schedule_work_on(cpu, work);
2571 for_each_online_cpu(cpu)
2572 flush_work(per_cpu_ptr(works, cpu));
2580 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2582 * Forces execution of the kernel-global workqueue and blocks until its
2585 * Think twice before calling this function! It's very easy to get into
2586 * trouble if you don't take great care. Either of the following situations
2587 * will lead to deadlock:
2589 * One of the work items currently on the workqueue needs to acquire
2590 * a lock held by your code or its caller.
2592 * Your code is running in the context of a work routine.
2594 * They will be detected by lockdep when they occur, but the first might not
2595 * occur very often. It depends on what work items are on the workqueue and
2596 * what locks they need, which you have no control over.
2598 * In most situations flushing the entire workqueue is overkill; you merely
2599 * need to know that a particular work item isn't queued and isn't running.
2600 * In such cases you should use cancel_delayed_work_sync() or
2601 * cancel_work_sync() instead.
2603 void flush_scheduled_work(void)
2605 flush_workqueue(system_wq);
2607 EXPORT_SYMBOL(flush_scheduled_work);
2610 * execute_in_process_context - reliably execute the routine with user context
2611 * @fn: the function to execute
2612 * @ew: guaranteed storage for the execute work structure (must
2613 * be available when the work executes)
2615 * Executes the function immediately if process context is available,
2616 * otherwise schedules the function for delayed execution.
2618 * Returns: 0 - function was executed
2619 * 1 - function was scheduled for execution
2621 int execute_in_process_context(work_func_t fn, struct execute_work *ew)
2623 if (!in_interrupt()) {
2628 INIT_WORK(&ew->work, fn);
2629 schedule_work(&ew->work);
2633 EXPORT_SYMBOL_GPL(execute_in_process_context);
2635 int keventd_up(void)
2637 return system_wq != NULL;
2640 static int alloc_cwqs(struct workqueue_struct *wq)
2643 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
2644 * Make sure that the alignment isn't lower than that of
2645 * unsigned long long.
2647 const size_t size = sizeof(struct cpu_workqueue_struct);
2648 const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
2649 __alignof__(unsigned long long));
2651 bool percpu = !(wq->flags & WQ_UNBOUND);
2653 bool percpu = false;
2657 wq->cpu_wq.pcpu = __alloc_percpu(size, align);
2662 * Allocate enough room to align cwq and put an extra
2663 * pointer at the end pointing back to the originally
2664 * allocated pointer which will be used for free.
2666 ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
2668 wq->cpu_wq.single = PTR_ALIGN(ptr, align);
2669 *(void **)(wq->cpu_wq.single + 1) = ptr;
2673 /* just in case, make sure it's actually aligned */
2674 BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
2675 return wq->cpu_wq.v ? 0 : -ENOMEM;
2678 static void free_cwqs(struct workqueue_struct *wq)
2681 bool percpu = !(wq->flags & WQ_UNBOUND);
2683 bool percpu = false;
2687 free_percpu(wq->cpu_wq.pcpu);
2688 else if (wq->cpu_wq.single) {
2689 /* the pointer to free is stored right after the cwq */
2690 kfree(*(void **)(wq->cpu_wq.single + 1));
2694 static int wq_clamp_max_active(int max_active, unsigned int flags,
2697 int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
2699 if (max_active < 1 || max_active > lim)
2700 printk(KERN_WARNING "workqueue: max_active %d requested for %s "
2701 "is out of range, clamping between %d and %d\n",
2702 max_active, name, 1, lim);
2704 return clamp_val(max_active, 1, lim);
2707 struct workqueue_struct *__alloc_workqueue_key(const char *name,
2710 struct lock_class_key *key,
2711 const char *lock_name)
2713 struct workqueue_struct *wq;
2717 * Unbound workqueues aren't concurrency managed and should be
2718 * dispatched to workers immediately.
2720 if (flags & WQ_UNBOUND)
2721 flags |= WQ_HIGHPRI;
2723 max_active = max_active ?: WQ_DFL_ACTIVE;
2724 max_active = wq_clamp_max_active(max_active, flags, name);
2726 wq = kzalloc(sizeof(*wq), GFP_KERNEL);
2731 wq->saved_max_active = max_active;
2732 mutex_init(&wq->flush_mutex);
2733 atomic_set(&wq->nr_cwqs_to_flush, 0);
2734 INIT_LIST_HEAD(&wq->flusher_queue);
2735 INIT_LIST_HEAD(&wq->flusher_overflow);
2738 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
2739 INIT_LIST_HEAD(&wq->list);
2741 if (alloc_cwqs(wq) < 0)
2744 for_each_cwq_cpu(cpu, wq) {
2745 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2746 struct global_cwq *gcwq = get_gcwq(cpu);
2748 BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
2751 cwq->flush_color = -1;
2752 cwq->max_active = max_active;
2753 INIT_LIST_HEAD(&cwq->delayed_works);
2756 if (flags & WQ_RESCUER) {
2757 struct worker *rescuer;
2759 if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL))
2762 wq->rescuer = rescuer = alloc_worker();
2766 rescuer->task = kthread_create(rescuer_thread, wq, "%s", name);
2767 if (IS_ERR(rescuer->task))
2770 wq->rescuer = rescuer;
2771 rescuer->task->flags |= PF_THREAD_BOUND;
2772 wake_up_process(rescuer->task);
2776 * workqueue_lock protects global freeze state and workqueues
2777 * list. Grab it, set max_active accordingly and add the new
2778 * workqueue to workqueues list.
2780 spin_lock(&workqueue_lock);
2782 if (workqueue_freezing && wq->flags & WQ_FREEZEABLE)
2783 for_each_cwq_cpu(cpu, wq)
2784 get_cwq(cpu, wq)->max_active = 0;
2786 list_add(&wq->list, &workqueues);
2788 spin_unlock(&workqueue_lock);
2794 free_mayday_mask(wq->mayday_mask);
2800 EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
2803 * destroy_workqueue - safely terminate a workqueue
2804 * @wq: target workqueue
2806 * Safely destroy a workqueue. All work currently pending will be done first.
2808 void destroy_workqueue(struct workqueue_struct *wq)
2812 flush_workqueue(wq);
2815 * wq list is used to freeze wq, remove from list after
2816 * flushing is complete in case freeze races us.
2818 spin_lock(&workqueue_lock);
2819 list_del(&wq->list);
2820 spin_unlock(&workqueue_lock);
2823 for_each_cwq_cpu(cpu, wq) {
2824 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2827 for (i = 0; i < WORK_NR_COLORS; i++)
2828 BUG_ON(cwq->nr_in_flight[i]);
2829 BUG_ON(cwq->nr_active);
2830 BUG_ON(!list_empty(&cwq->delayed_works));
2833 if (wq->flags & WQ_RESCUER) {
2834 kthread_stop(wq->rescuer->task);
2835 free_mayday_mask(wq->mayday_mask);
2841 EXPORT_SYMBOL_GPL(destroy_workqueue);
2844 * workqueue_set_max_active - adjust max_active of a workqueue
2845 * @wq: target workqueue
2846 * @max_active: new max_active value.
2848 * Set max_active of @wq to @max_active.
2851 * Don't call from IRQ context.
2853 void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
2857 max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
2859 spin_lock(&workqueue_lock);
2861 wq->saved_max_active = max_active;
2863 for_each_cwq_cpu(cpu, wq) {
2864 struct global_cwq *gcwq = get_gcwq(cpu);
2866 spin_lock_irq(&gcwq->lock);
2868 if (!(wq->flags & WQ_FREEZEABLE) ||
2869 !(gcwq->flags & GCWQ_FREEZING))
2870 get_cwq(gcwq->cpu, wq)->max_active = max_active;
2872 spin_unlock_irq(&gcwq->lock);
2875 spin_unlock(&workqueue_lock);
2877 EXPORT_SYMBOL_GPL(workqueue_set_max_active);
2880 * workqueue_congested - test whether a workqueue is congested
2881 * @cpu: CPU in question
2882 * @wq: target workqueue
2884 * Test whether @wq's cpu workqueue for @cpu is congested. There is
2885 * no synchronization around this function and the test result is
2886 * unreliable and only useful as advisory hints or for debugging.
2889 * %true if congested, %false otherwise.
2891 bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
2893 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2895 return !list_empty(&cwq->delayed_works);
2897 EXPORT_SYMBOL_GPL(workqueue_congested);
2900 * work_cpu - return the last known associated cpu for @work
2901 * @work: the work of interest
2904 * CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
2906 unsigned int work_cpu(struct work_struct *work)
2908 struct global_cwq *gcwq = get_work_gcwq(work);
2910 return gcwq ? gcwq->cpu : WORK_CPU_NONE;
2912 EXPORT_SYMBOL_GPL(work_cpu);
2915 * work_busy - test whether a work is currently pending or running
2916 * @work: the work to be tested
2918 * Test whether @work is currently pending or running. There is no
2919 * synchronization around this function and the test result is
2920 * unreliable and only useful as advisory hints or for debugging.
2921 * Especially for reentrant wqs, the pending state might hide the
2925 * OR'd bitmask of WORK_BUSY_* bits.
2927 unsigned int work_busy(struct work_struct *work)
2929 struct global_cwq *gcwq = get_work_gcwq(work);
2930 unsigned long flags;
2931 unsigned int ret = 0;
2936 spin_lock_irqsave(&gcwq->lock, flags);
2938 if (work_pending(work))
2939 ret |= WORK_BUSY_PENDING;
2940 if (find_worker_executing_work(gcwq, work))
2941 ret |= WORK_BUSY_RUNNING;
2943 spin_unlock_irqrestore(&gcwq->lock, flags);
2947 EXPORT_SYMBOL_GPL(work_busy);
2952 * There are two challenges in supporting CPU hotplug. Firstly, there
2953 * are a lot of assumptions on strong associations among work, cwq and
2954 * gcwq which make migrating pending and scheduled works very
2955 * difficult to implement without impacting hot paths. Secondly,
2956 * gcwqs serve mix of short, long and very long running works making
2957 * blocked draining impractical.
2959 * This is solved by allowing a gcwq to be detached from CPU, running
2960 * it with unbound (rogue) workers and allowing it to be reattached
2961 * later if the cpu comes back online. A separate thread is created
2962 * to govern a gcwq in such state and is called the trustee of the
2965 * Trustee states and their descriptions.
2967 * START Command state used on startup. On CPU_DOWN_PREPARE, a
2968 * new trustee is started with this state.
2970 * IN_CHARGE Once started, trustee will enter this state after
2971 * assuming the manager role and making all existing
2972 * workers rogue. DOWN_PREPARE waits for trustee to
2973 * enter this state. After reaching IN_CHARGE, trustee
2974 * tries to execute the pending worklist until it's empty
2975 * and the state is set to BUTCHER, or the state is set
2978 * BUTCHER Command state which is set by the cpu callback after
2979 * the cpu has went down. Once this state is set trustee
2980 * knows that there will be no new works on the worklist
2981 * and once the worklist is empty it can proceed to
2982 * killing idle workers.
2984 * RELEASE Command state which is set by the cpu callback if the
2985 * cpu down has been canceled or it has come online
2986 * again. After recognizing this state, trustee stops
2987 * trying to drain or butcher and clears ROGUE, rebinds
2988 * all remaining workers back to the cpu and releases
2991 * DONE Trustee will enter this state after BUTCHER or RELEASE
2994 * trustee CPU draining
2995 * took over down complete
2996 * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
2998 * | CPU is back online v return workers |
2999 * ----------------> RELEASE --------------
3003 * trustee_wait_event_timeout - timed event wait for trustee
3004 * @cond: condition to wait for
3005 * @timeout: timeout in jiffies
3007 * wait_event_timeout() for trustee to use. Handles locking and
3008 * checks for RELEASE request.
3011 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3012 * multiple times. To be used by trustee.
3015 * Positive indicating left time if @cond is satisfied, 0 if timed
3016 * out, -1 if canceled.
3018 #define trustee_wait_event_timeout(cond, timeout) ({ \
3019 long __ret = (timeout); \
3020 while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \
3022 spin_unlock_irq(&gcwq->lock); \
3023 __wait_event_timeout(gcwq->trustee_wait, (cond) || \
3024 (gcwq->trustee_state == TRUSTEE_RELEASE), \
3026 spin_lock_irq(&gcwq->lock); \
3028 gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \
3032 * trustee_wait_event - event wait for trustee
3033 * @cond: condition to wait for
3035 * wait_event() for trustee to use. Automatically handles locking and
3036 * checks for CANCEL request.
3039 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3040 * multiple times. To be used by trustee.
3043 * 0 if @cond is satisfied, -1 if canceled.
3045 #define trustee_wait_event(cond) ({ \
3047 __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
3048 __ret1 < 0 ? -1 : 0; \
3051 static int __cpuinit trustee_thread(void *__gcwq)
3053 struct global_cwq *gcwq = __gcwq;
3054 struct worker *worker;
3055 struct work_struct *work;
3056 struct hlist_node *pos;
3060 BUG_ON(gcwq->cpu != smp_processor_id());
3062 spin_lock_irq(&gcwq->lock);
3064 * Claim the manager position and make all workers rogue.
3065 * Trustee must be bound to the target cpu and can't be
3068 BUG_ON(gcwq->cpu != smp_processor_id());
3069 rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS));
3072 gcwq->flags |= GCWQ_MANAGING_WORKERS;
3074 list_for_each_entry(worker, &gcwq->idle_list, entry)
3075 worker->flags |= WORKER_ROGUE;
3077 for_each_busy_worker(worker, i, pos, gcwq)
3078 worker->flags |= WORKER_ROGUE;
3081 * Call schedule() so that we cross rq->lock and thus can
3082 * guarantee sched callbacks see the rogue flag. This is
3083 * necessary as scheduler callbacks may be invoked from other
3086 spin_unlock_irq(&gcwq->lock);
3088 spin_lock_irq(&gcwq->lock);
3091 * Sched callbacks are disabled now. Zap nr_running. After
3092 * this, nr_running stays zero and need_more_worker() and
3093 * keep_working() are always true as long as the worklist is
3096 atomic_set(get_gcwq_nr_running(gcwq->cpu), 0);
3098 spin_unlock_irq(&gcwq->lock);
3099 del_timer_sync(&gcwq->idle_timer);
3100 spin_lock_irq(&gcwq->lock);
3103 * We're now in charge. Notify and proceed to drain. We need
3104 * to keep the gcwq running during the whole CPU down
3105 * procedure as other cpu hotunplug callbacks may need to
3106 * flush currently running tasks.
3108 gcwq->trustee_state = TRUSTEE_IN_CHARGE;
3109 wake_up_all(&gcwq->trustee_wait);
3112 * The original cpu is in the process of dying and may go away
3113 * anytime now. When that happens, we and all workers would
3114 * be migrated to other cpus. Try draining any left work. We
3115 * want to get it over with ASAP - spam rescuers, wake up as
3116 * many idlers as necessary and create new ones till the
3117 * worklist is empty. Note that if the gcwq is frozen, there
3118 * may be frozen works in freezeable cwqs. Don't declare
3119 * completion while frozen.
3121 while (gcwq->nr_workers != gcwq->nr_idle ||
3122 gcwq->flags & GCWQ_FREEZING ||
3123 gcwq->trustee_state == TRUSTEE_IN_CHARGE) {
3126 list_for_each_entry(work, &gcwq->worklist, entry) {
3131 list_for_each_entry(worker, &gcwq->idle_list, entry) {
3134 wake_up_process(worker->task);
3137 if (need_to_create_worker(gcwq)) {
3138 spin_unlock_irq(&gcwq->lock);
3139 worker = create_worker(gcwq, false);
3140 spin_lock_irq(&gcwq->lock);
3142 worker->flags |= WORKER_ROGUE;
3143 start_worker(worker);
3147 /* give a breather */
3148 if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
3153 * Either all works have been scheduled and cpu is down, or
3154 * cpu down has already been canceled. Wait for and butcher
3155 * all workers till we're canceled.
3158 rc = trustee_wait_event(!list_empty(&gcwq->idle_list));
3159 while (!list_empty(&gcwq->idle_list))
3160 destroy_worker(list_first_entry(&gcwq->idle_list,
3161 struct worker, entry));
3162 } while (gcwq->nr_workers && rc >= 0);
3165 * At this point, either draining has completed and no worker
3166 * is left, or cpu down has been canceled or the cpu is being
3167 * brought back up. There shouldn't be any idle one left.
3168 * Tell the remaining busy ones to rebind once it finishes the
3169 * currently scheduled works by scheduling the rebind_work.
3171 WARN_ON(!list_empty(&gcwq->idle_list));
3173 for_each_busy_worker(worker, i, pos, gcwq) {
3174 struct work_struct *rebind_work = &worker->rebind_work;
3177 * Rebind_work may race with future cpu hotplug
3178 * operations. Use a separate flag to mark that
3179 * rebinding is scheduled.
3181 worker->flags |= WORKER_REBIND;
3182 worker->flags &= ~WORKER_ROGUE;
3184 /* queue rebind_work, wq doesn't matter, use the default one */
3185 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
3186 work_data_bits(rebind_work)))
3189 debug_work_activate(rebind_work);
3190 insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
3191 worker->scheduled.next,
3192 work_color_to_flags(WORK_NO_COLOR));
3195 /* relinquish manager role */
3196 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
3198 /* notify completion */
3199 gcwq->trustee = NULL;
3200 gcwq->trustee_state = TRUSTEE_DONE;
3201 wake_up_all(&gcwq->trustee_wait);
3202 spin_unlock_irq(&gcwq->lock);
3207 * wait_trustee_state - wait for trustee to enter the specified state
3208 * @gcwq: gcwq the trustee of interest belongs to
3209 * @state: target state to wait for
3211 * Wait for the trustee to reach @state. DONE is already matched.
3214 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3215 * multiple times. To be used by cpu_callback.
3217 static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
3219 if (!(gcwq->trustee_state == state ||
3220 gcwq->trustee_state == TRUSTEE_DONE)) {
3221 spin_unlock_irq(&gcwq->lock);
3222 __wait_event(gcwq->trustee_wait,
3223 gcwq->trustee_state == state ||
3224 gcwq->trustee_state == TRUSTEE_DONE);
3225 spin_lock_irq(&gcwq->lock);
3229 static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
3230 unsigned long action,
3233 unsigned int cpu = (unsigned long)hcpu;
3234 struct global_cwq *gcwq = get_gcwq(cpu);
3235 struct task_struct *new_trustee = NULL;
3236 struct worker *uninitialized_var(new_worker);
3237 unsigned long flags;
3239 action &= ~CPU_TASKS_FROZEN;
3242 case CPU_DOWN_PREPARE:
3243 new_trustee = kthread_create(trustee_thread, gcwq,
3244 "workqueue_trustee/%d\n", cpu);
3245 if (IS_ERR(new_trustee))
3246 return notifier_from_errno(PTR_ERR(new_trustee));
3247 kthread_bind(new_trustee, cpu);
3249 case CPU_UP_PREPARE:
3250 BUG_ON(gcwq->first_idle);
3251 new_worker = create_worker(gcwq, false);
3254 kthread_stop(new_trustee);
3259 /* some are called w/ irq disabled, don't disturb irq status */
3260 spin_lock_irqsave(&gcwq->lock, flags);
3263 case CPU_DOWN_PREPARE:
3264 /* initialize trustee and tell it to acquire the gcwq */
3265 BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE);
3266 gcwq->trustee = new_trustee;
3267 gcwq->trustee_state = TRUSTEE_START;
3268 wake_up_process(gcwq->trustee);
3269 wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);
3271 case CPU_UP_PREPARE:
3272 BUG_ON(gcwq->first_idle);
3273 gcwq->first_idle = new_worker;
3278 * Before this, the trustee and all workers except for
3279 * the ones which are still executing works from
3280 * before the last CPU down must be on the cpu. After
3281 * this, they'll all be diasporas.
3283 gcwq->flags |= GCWQ_DISASSOCIATED;
3287 gcwq->trustee_state = TRUSTEE_BUTCHER;
3289 case CPU_UP_CANCELED:
3290 destroy_worker(gcwq->first_idle);
3291 gcwq->first_idle = NULL;
3294 case CPU_DOWN_FAILED:
3296 gcwq->flags &= ~GCWQ_DISASSOCIATED;
3297 if (gcwq->trustee_state != TRUSTEE_DONE) {
3298 gcwq->trustee_state = TRUSTEE_RELEASE;
3299 wake_up_process(gcwq->trustee);
3300 wait_trustee_state(gcwq, TRUSTEE_DONE);
3304 * Trustee is done and there might be no worker left.
3305 * Put the first_idle in and request a real manager to
3308 spin_unlock_irq(&gcwq->lock);
3309 kthread_bind(gcwq->first_idle->task, cpu);
3310 spin_lock_irq(&gcwq->lock);
3311 gcwq->flags |= GCWQ_MANAGE_WORKERS;
3312 start_worker(gcwq->first_idle);
3313 gcwq->first_idle = NULL;
3317 spin_unlock_irqrestore(&gcwq->lock, flags);
3319 return notifier_from_errno(0);
3324 struct work_for_cpu {
3325 struct completion completion;
3331 static int do_work_for_cpu(void *_wfc)
3333 struct work_for_cpu *wfc = _wfc;
3334 wfc->ret = wfc->fn(wfc->arg);
3335 complete(&wfc->completion);
3340 * work_on_cpu - run a function in user context on a particular cpu
3341 * @cpu: the cpu to run on
3342 * @fn: the function to run
3343 * @arg: the function arg
3345 * This will return the value @fn returns.
3346 * It is up to the caller to ensure that the cpu doesn't go offline.
3347 * The caller must not hold any locks which would prevent @fn from completing.
3349 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
3351 struct task_struct *sub_thread;
3352 struct work_for_cpu wfc = {
3353 .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
3358 sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
3359 if (IS_ERR(sub_thread))
3360 return PTR_ERR(sub_thread);
3361 kthread_bind(sub_thread, cpu);
3362 wake_up_process(sub_thread);
3363 wait_for_completion(&wfc.completion);
3366 EXPORT_SYMBOL_GPL(work_on_cpu);
3367 #endif /* CONFIG_SMP */
3369 #ifdef CONFIG_FREEZER
3372 * freeze_workqueues_begin - begin freezing workqueues
3374 * Start freezing workqueues. After this function returns, all
3375 * freezeable workqueues will queue new works to their frozen_works
3376 * list instead of gcwq->worklist.
3379 * Grabs and releases workqueue_lock and gcwq->lock's.
3381 void freeze_workqueues_begin(void)
3385 spin_lock(&workqueue_lock);
3387 BUG_ON(workqueue_freezing);
3388 workqueue_freezing = true;
3390 for_each_gcwq_cpu(cpu) {
3391 struct global_cwq *gcwq = get_gcwq(cpu);
3392 struct workqueue_struct *wq;
3394 spin_lock_irq(&gcwq->lock);
3396 BUG_ON(gcwq->flags & GCWQ_FREEZING);
3397 gcwq->flags |= GCWQ_FREEZING;
3399 list_for_each_entry(wq, &workqueues, list) {
3400 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3402 if (cwq && wq->flags & WQ_FREEZEABLE)
3403 cwq->max_active = 0;
3406 spin_unlock_irq(&gcwq->lock);
3409 spin_unlock(&workqueue_lock);
3413 * freeze_workqueues_busy - are freezeable workqueues still busy?
3415 * Check whether freezing is complete. This function must be called
3416 * between freeze_workqueues_begin() and thaw_workqueues().
3419 * Grabs and releases workqueue_lock.
3422 * %true if some freezeable workqueues are still busy. %false if
3423 * freezing is complete.
3425 bool freeze_workqueues_busy(void)
3430 spin_lock(&workqueue_lock);
3432 BUG_ON(!workqueue_freezing);
3434 for_each_gcwq_cpu(cpu) {
3435 struct workqueue_struct *wq;
3437 * nr_active is monotonically decreasing. It's safe
3438 * to peek without lock.
3440 list_for_each_entry(wq, &workqueues, list) {
3441 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3443 if (!cwq || !(wq->flags & WQ_FREEZEABLE))
3446 BUG_ON(cwq->nr_active < 0);
3447 if (cwq->nr_active) {
3454 spin_unlock(&workqueue_lock);
3459 * thaw_workqueues - thaw workqueues
3461 * Thaw workqueues. Normal queueing is restored and all collected
3462 * frozen works are transferred to their respective gcwq worklists.
3465 * Grabs and releases workqueue_lock and gcwq->lock's.
3467 void thaw_workqueues(void)
3471 spin_lock(&workqueue_lock);
3473 if (!workqueue_freezing)
3476 for_each_gcwq_cpu(cpu) {
3477 struct global_cwq *gcwq = get_gcwq(cpu);
3478 struct workqueue_struct *wq;
3480 spin_lock_irq(&gcwq->lock);
3482 BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
3483 gcwq->flags &= ~GCWQ_FREEZING;
3485 list_for_each_entry(wq, &workqueues, list) {
3486 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3488 if (!cwq || !(wq->flags & WQ_FREEZEABLE))
3491 /* restore max_active and repopulate worklist */
3492 cwq->max_active = wq->saved_max_active;
3494 while (!list_empty(&cwq->delayed_works) &&
3495 cwq->nr_active < cwq->max_active)
3496 cwq_activate_first_delayed(cwq);
3499 wake_up_worker(gcwq);
3501 spin_unlock_irq(&gcwq->lock);
3504 workqueue_freezing = false;
3506 spin_unlock(&workqueue_lock);
3508 #endif /* CONFIG_FREEZER */
3510 static int __init init_workqueues(void)
3515 hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
3517 /* initialize gcwqs */
3518 for_each_gcwq_cpu(cpu) {
3519 struct global_cwq *gcwq = get_gcwq(cpu);
3521 spin_lock_init(&gcwq->lock);
3522 INIT_LIST_HEAD(&gcwq->worklist);
3524 if (cpu == WORK_CPU_UNBOUND)
3525 gcwq->flags |= GCWQ_DISASSOCIATED;
3527 INIT_LIST_HEAD(&gcwq->idle_list);
3528 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
3529 INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
3531 init_timer_deferrable(&gcwq->idle_timer);
3532 gcwq->idle_timer.function = idle_worker_timeout;
3533 gcwq->idle_timer.data = (unsigned long)gcwq;
3535 setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout,
3536 (unsigned long)gcwq);
3538 ida_init(&gcwq->worker_ida);
3540 gcwq->trustee_state = TRUSTEE_DONE;
3541 init_waitqueue_head(&gcwq->trustee_wait);
3544 /* create the initial worker */
3545 for_each_online_gcwq_cpu(cpu) {
3546 struct global_cwq *gcwq = get_gcwq(cpu);
3547 struct worker *worker;
3549 worker = create_worker(gcwq, true);
3551 spin_lock_irq(&gcwq->lock);
3552 start_worker(worker);
3553 spin_unlock_irq(&gcwq->lock);
3556 system_wq = alloc_workqueue("events", 0, 0);
3557 system_long_wq = alloc_workqueue("events_long", 0, 0);
3558 system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
3559 system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
3560 WQ_UNBOUND_MAX_ACTIVE);
3561 BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);
3564 early_initcall(init_workqueues);