/*
- * linux/kernel/workqueue.c
+ * kernel/workqueue.c - generic async execution with shared worker pool
*
- * Generic mechanism for defining kernel helper threads for running
- * arbitrary tasks in process context.
+ * Copyright (C) 2002 Ingo Molnar
*
- * Started by Ingo Molnar, Copyright (C) 2002
+ * Derived from the taskqueue/keventd code by:
+ * David Woodhouse <dwmw2@infradead.org>
+ * Andrew Morton
+ * Kai Petzke <wpp@marie.physik.tu-berlin.de>
+ * Theodore Ts'o <tytso@mit.edu>
*
- * Derived from the taskqueue/keventd code by:
+ * Made to use alloc_percpu by Christoph Lameter.
*
- * David Woodhouse <dwmw2@infradead.org>
- * Andrew Morton
- * Kai Petzke <wpp@marie.physik.tu-berlin.de>
- * Theodore Ts'o <tytso@mit.edu>
+ * Copyright (C) 2010 SUSE Linux Products GmbH
+ * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
*
- * Made to use alloc_percpu by Christoph Lameter.
+ * This is the generic async execution mechanism. Work items as are
+ * executed in process context. The worker pool is shared and
+ * automatically managed. There is one worker pool for each CPU and
+ * one extra for works which are better served by workers which are
+ * not bound to any specific CPU.
+ *
+ * Please read Documentation/workqueue.txt for details.
*/
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/debug_locks.h>
#include <linux/lockdep.h>
+#include <linux/idr.h>
+
+#include "workqueue_sched.h"
+
+enum {
+ /* global_cwq flags */
+ GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
+ GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */
+ GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
+ GCWQ_FREEZING = 1 << 3, /* freeze in progress */
+ GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */
+
+ /* worker flags */
+ WORKER_STARTED = 1 << 0, /* started */
+ WORKER_DIE = 1 << 1, /* die die die */
+ WORKER_IDLE = 1 << 2, /* is idle */
+ WORKER_PREP = 1 << 3, /* preparing to run works */
+ WORKER_ROGUE = 1 << 4, /* not bound to any cpu */
+ WORKER_REBIND = 1 << 5, /* mom is home, come back */
+ WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
+ WORKER_UNBOUND = 1 << 7, /* worker is unbound */
+
+ WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND |
+ WORKER_CPU_INTENSIVE | WORKER_UNBOUND,
+
+ /* gcwq->trustee_state */
+ TRUSTEE_START = 0, /* start */
+ TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */
+ TRUSTEE_BUTCHER = 2, /* butcher workers */
+ TRUSTEE_RELEASE = 3, /* release workers */
+ TRUSTEE_DONE = 4, /* trustee is done */
+
+ BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
+ BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER,
+ BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1,
+
+ MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
+ IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
+
+ MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */
+ MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
+ CREATE_COOLDOWN = HZ, /* time to breath after fail */
+ TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */
+
+ /*
+ * Rescue workers are used only on emergencies and shared by
+ * all cpus. Give -20.
+ */
+ RESCUER_NICE_LEVEL = -20,
+};
/*
- * The per-CPU workqueue (if single thread, we always use the first
- * possible cpu).
+ * Structure fields follow one of the following exclusion rules.
+ *
+ * I: Modifiable by initialization/destruction paths and read-only for
+ * everyone else.
+ *
+ * P: Preemption protected. Disabling preemption is enough and should
+ * only be modified and accessed from the local cpu.
+ *
+ * L: gcwq->lock protected. Access with gcwq->lock held.
+ *
+ * X: During normal operation, modification requires gcwq->lock and
+ * should be done only from local cpu. Either disabling preemption
+ * on local cpu or grabbing gcwq->lock is enough for read access.
+ * If GCWQ_DISASSOCIATED is set, it's identical to L.
+ *
+ * F: wq->flush_mutex protected.
+ *
+ * W: workqueue_lock protected.
*/
-struct cpu_workqueue_struct {
- spinlock_t lock;
+struct global_cwq;
+
+/*
+ * The poor guys doing the actual heavy lifting. All on-duty workers
+ * are either serving the manager role, on idle list or on busy hash.
+ */
+struct worker {
+ /* on idle list while idle, on busy hash table while busy */
+ union {
+ struct list_head entry; /* L: while idle */
+ struct hlist_node hentry; /* L: while busy */
+ };
+
+ struct work_struct *current_work; /* L: work being processed */
+ struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
+ struct list_head scheduled; /* L: scheduled works */
+ struct task_struct *task; /* I: worker task */
+ struct global_cwq *gcwq; /* I: the associated gcwq */
+ /* 64 bytes boundary on 64bit, 32 on 32bit */
+ unsigned long last_active; /* L: last active timestamp */
+ unsigned int flags; /* X: flags */
+ int id; /* I: worker id */
+ struct work_struct rebind_work; /* L: rebind worker to cpu */
+};
+
+/*
+ * Global per-cpu workqueue. There's one and only one for each cpu
+ * and all works are queued and processed here regardless of their
+ * target workqueues.
+ */
+struct global_cwq {
+ spinlock_t lock; /* the gcwq lock */
+ struct list_head worklist; /* L: list of pending works */
+ unsigned int cpu; /* I: the associated cpu */
+ unsigned int flags; /* L: GCWQ_* flags */
+
+ int nr_workers; /* L: total number of workers */
+ int nr_idle; /* L: currently idle ones */
- struct list_head worklist;
- wait_queue_head_t more_work;
- struct work_struct *current_work;
+ /* workers are chained either in the idle_list or busy_hash */
+ struct list_head idle_list; /* X: list of idle workers */
+ struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE];
+ /* L: hash of busy workers */
- struct workqueue_struct *wq;
- struct task_struct *thread;
+ struct timer_list idle_timer; /* L: worker idle timeout */
+ struct timer_list mayday_timer; /* L: SOS timer for dworkers */
+
+ struct ida worker_ida; /* L: for worker IDs */
+
+ struct task_struct *trustee; /* L: for gcwq shutdown */
+ unsigned int trustee_state; /* L: trustee state */
+ wait_queue_head_t trustee_wait; /* trustee wait */
+ struct worker *first_idle; /* L: first idle worker */
+} ____cacheline_aligned_in_smp;
+
+/*
+ * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
+ * work_struct->data are used for flags and thus cwqs need to be
+ * aligned at two's power of the number of flag bits.
+ */
+struct cpu_workqueue_struct {
+ struct global_cwq *gcwq; /* I: the associated gcwq */
+ struct workqueue_struct *wq; /* I: the owning workqueue */
+ int work_color; /* L: current color */
+ int flush_color; /* L: flushing color */
+ int nr_in_flight[WORK_NR_COLORS];
+ /* L: nr of in_flight works */
+ int nr_active; /* L: nr of active works */
+ int max_active; /* L: max active works */
+ struct list_head delayed_works; /* L: delayed works */
+};
+
+/*
+ * Structure used to wait for workqueue flush.
+ */
+struct wq_flusher {
+ struct list_head list; /* F: list of flushers */
+ int flush_color; /* F: flush color waiting for */
+ struct completion done; /* flush completion */
+};
- int run_depth; /* Detect run_workqueue() recursion depth */
-} ____cacheline_aligned;
+/*
+ * All cpumasks are assumed to be always set on UP and thus can't be
+ * used to determine whether there's something to be done.
+ */
+#ifdef CONFIG_SMP
+typedef cpumask_var_t mayday_mask_t;
+#define mayday_test_and_set_cpu(cpu, mask) \
+ cpumask_test_and_set_cpu((cpu), (mask))
+#define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
+#define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
+#define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
+#define free_mayday_mask(mask) free_cpumask_var((mask))
+#else
+typedef unsigned long mayday_mask_t;
+#define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
+#define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
+#define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
+#define alloc_mayday_mask(maskp, gfp) true
+#define free_mayday_mask(mask) do { } while (0)
+#endif
/*
* The externally visible workqueue abstraction is an array of
* per-CPU workqueues:
*/
struct workqueue_struct {
- struct cpu_workqueue_struct *cpu_wq;
- struct list_head list;
- const char *name;
- int singlethread;
- int freezeable; /* Freeze threads during suspend */
- int rt;
+ unsigned int flags; /* I: WQ_* flags */
+ union {
+ struct cpu_workqueue_struct __percpu *pcpu;
+ struct cpu_workqueue_struct *single;
+ unsigned long v;
+ } cpu_wq; /* I: cwq's */
+ struct list_head list; /* W: list of all workqueues */
+
+ struct mutex flush_mutex; /* protects wq flushing */
+ int work_color; /* F: current work color */
+ int flush_color; /* F: current flush color */
+ atomic_t nr_cwqs_to_flush; /* flush in progress */
+ struct wq_flusher *first_flusher; /* F: first flusher */
+ struct list_head flusher_queue; /* F: flush waiters */
+ struct list_head flusher_overflow; /* F: flush overflow list */
+
+ mayday_mask_t mayday_mask; /* cpus requesting rescue */
+ struct worker *rescuer; /* I: rescue worker */
+
+ int saved_max_active; /* W: saved cwq max_active */
+ const char *name; /* I: workqueue name */
#ifdef CONFIG_LOCKDEP
- struct lockdep_map lockdep_map;
+ struct lockdep_map lockdep_map;
#endif
};
-/* Serializes the accesses to the list of workqueues. */
-static DEFINE_SPINLOCK(workqueue_lock);
-static LIST_HEAD(workqueues);
+struct workqueue_struct *system_wq __read_mostly;
+struct workqueue_struct *system_long_wq __read_mostly;
+struct workqueue_struct *system_nrt_wq __read_mostly;
+struct workqueue_struct *system_unbound_wq __read_mostly;
+EXPORT_SYMBOL_GPL(system_wq);
+EXPORT_SYMBOL_GPL(system_long_wq);
+EXPORT_SYMBOL_GPL(system_nrt_wq);
+EXPORT_SYMBOL_GPL(system_unbound_wq);
-static int singlethread_cpu __read_mostly;
-static const struct cpumask *cpu_singlethread_map __read_mostly;
-/*
- * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD
- * flushes cwq->worklist. This means that flush_workqueue/wait_on_work
- * which comes in between can't use for_each_online_cpu(). We could
- * use cpu_possible_map, the cpumask below is more a documentation
- * than optimization.
- */
-static cpumask_var_t cpu_populated_map __read_mostly;
+#define CREATE_TRACE_POINTS
+#include <trace/events/workqueue.h>
+
+#define for_each_busy_worker(worker, i, pos, gcwq) \
+ for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
+ hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
-/* If it's single threaded, it isn't in the list of workqueues. */
-static inline int is_wq_single_threaded(struct workqueue_struct *wq)
+static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
+ unsigned int sw)
{
- return wq->singlethread;
+ if (cpu < nr_cpu_ids) {
+ if (sw & 1) {
+ cpu = cpumask_next(cpu, mask);
+ if (cpu < nr_cpu_ids)
+ return cpu;
+ }
+ if (sw & 2)
+ return WORK_CPU_UNBOUND;
+ }
+ return WORK_CPU_NONE;
}
-static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq)
+static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
+ struct workqueue_struct *wq)
{
- return is_wq_single_threaded(wq)
- ? cpu_singlethread_map : cpu_populated_map;
+ return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
}
-static
-struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
+/*
+ * CPU iterators
+ *
+ * An extra gcwq is defined for an invalid cpu number
+ * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
+ * specific CPU. The following iterators are similar to
+ * for_each_*_cpu() iterators but also considers the unbound gcwq.
+ *
+ * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
+ * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
+ * for_each_cwq_cpu() : possible CPUs for bound workqueues,
+ * WORK_CPU_UNBOUND for unbound workqueues
+ */
+#define for_each_gcwq_cpu(cpu) \
+ for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
+ (cpu) < WORK_CPU_NONE; \
+ (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
+
+#define for_each_online_gcwq_cpu(cpu) \
+ for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
+ (cpu) < WORK_CPU_NONE; \
+ (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
+
+#define for_each_cwq_cpu(cpu, wq) \
+ for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
+ (cpu) < WORK_CPU_NONE; \
+ (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
+
+#ifdef CONFIG_DEBUG_OBJECTS_WORK
+
+static struct debug_obj_descr work_debug_descr;
+
+/*
+ * fixup_init is called when:
+ * - an active object is initialized
+ */
+static int work_fixup_init(void *addr, enum debug_obj_state state)
{
- if (unlikely(is_wq_single_threaded(wq)))
- cpu = singlethread_cpu;
- return per_cpu_ptr(wq->cpu_wq, cpu);
+ struct work_struct *work = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ cancel_work_sync(work);
+ debug_object_init(work, &work_debug_descr);
+ return 1;
+ default:
+ return 0;
+ }
}
/*
- * Set the workqueue on which a work item is to be run
- * - Must *only* be called if the pending flag is set
+ * fixup_activate is called when:
+ * - an active object is activated
+ * - an unknown object is activated (might be a statically initialized object)
*/
-static inline void set_wq_data(struct work_struct *work,
- struct cpu_workqueue_struct *cwq)
+static int work_fixup_activate(void *addr, enum debug_obj_state state)
{
- unsigned long new;
+ struct work_struct *work = addr;
- BUG_ON(!work_pending(work));
+ switch (state) {
+
+ case ODEBUG_STATE_NOTAVAILABLE:
+ /*
+ * This is not really a fixup. The work struct was
+ * statically initialized. We just make sure that it
+ * is tracked in the object tracker.
+ */
+ if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
+ debug_object_init(work, &work_debug_descr);
+ debug_object_activate(work, &work_debug_descr);
+ return 0;
+ }
+ WARN_ON_ONCE(1);
+ return 0;
+
+ case ODEBUG_STATE_ACTIVE:
+ WARN_ON(1);
- new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING);
- new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work);
- atomic_long_set(&work->data, new);
+ default:
+ return 0;
+ }
}
-static inline
-struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
+/*
+ * fixup_free is called when:
+ * - an active object is freed
+ */
+static int work_fixup_free(void *addr, enum debug_obj_state state)
{
- return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);
+ struct work_struct *work = addr;
+
+ switch (state) {
+ case ODEBUG_STATE_ACTIVE:
+ cancel_work_sync(work);
+ debug_object_free(work, &work_debug_descr);
+ return 1;
+ default:
+ return 0;
+ }
}
-static void insert_work(struct cpu_workqueue_struct *cwq,
- struct work_struct *work, struct list_head *head)
+static struct debug_obj_descr work_debug_descr = {
+ .name = "work_struct",
+ .fixup_init = work_fixup_init,
+ .fixup_activate = work_fixup_activate,
+ .fixup_free = work_fixup_free,
+};
+
+static inline void debug_work_activate(struct work_struct *work)
{
- set_wq_data(work, cwq);
- /*
- * Ensure that we get the right work->data if we see the
- * result of list_add() below, see try_to_grab_pending().
- */
- smp_wmb();
- list_add_tail(&work->entry, head);
- wake_up(&cwq->more_work);
+ debug_object_activate(work, &work_debug_descr);
}
-static void __queue_work(struct cpu_workqueue_struct *cwq,
- struct work_struct *work)
+static inline void debug_work_deactivate(struct work_struct *work)
{
- unsigned long flags;
+ debug_object_deactivate(work, &work_debug_descr);
+}
- spin_lock_irqsave(&cwq->lock, flags);
- insert_work(cwq, work, &cwq->worklist);
- spin_unlock_irqrestore(&cwq->lock, flags);
+void __init_work(struct work_struct *work, int onstack)
+{
+ if (onstack)
+ debug_object_init_on_stack(work, &work_debug_descr);
+ else
+ debug_object_init(work, &work_debug_descr);
}
+EXPORT_SYMBOL_GPL(__init_work);
-/**
- * queue_work - queue work on a workqueue
- * @wq: workqueue to use
- * @work: work to queue
- *
- * Returns 0 if @work was already on a queue, non-zero otherwise.
- *
- * We queue the work to the CPU on which it was submitted, but if the CPU dies
- * it can be processed by another CPU.
- */
-int queue_work(struct workqueue_struct *wq, struct work_struct *work)
+void destroy_work_on_stack(struct work_struct *work)
{
- int ret;
+ debug_object_free(work, &work_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_work_on_stack);
- ret = queue_work_on(get_cpu(), wq, work);
- put_cpu();
+#else
+static inline void debug_work_activate(struct work_struct *work) { }
+static inline void debug_work_deactivate(struct work_struct *work) { }
+#endif
- return ret;
-}
-EXPORT_SYMBOL_GPL(queue_work);
+/* Serializes the accesses to the list of workqueues. */
+static DEFINE_SPINLOCK(workqueue_lock);
+static LIST_HEAD(workqueues);
+static bool workqueue_freezing; /* W: have wqs started freezing? */
-/**
- * queue_work_on - queue work on specific cpu
- * @cpu: CPU number to execute work on
- * @wq: workqueue to use
- * @work: work to queue
- *
- * Returns 0 if @work was already on a queue, non-zero otherwise.
- *
- * We queue the work to a specific CPU, the caller must ensure it
- * can't go away.
+/*
+ * The almighty global cpu workqueues. nr_running is the only field
+ * which is expected to be used frequently by other cpus via
+ * try_to_wake_up(). Put it in a separate cacheline.
*/
-int
-queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
+static DEFINE_PER_CPU(struct global_cwq, global_cwq);
+static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);
+
+/*
+ * Global cpu workqueue and nr_running counter for unbound gcwq. The
+ * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
+ * workers have WORKER_UNBOUND set.
+ */
+static struct global_cwq unbound_global_cwq;
+static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */
+
+static int worker_thread(void *__worker);
+
+static struct global_cwq *get_gcwq(unsigned int cpu)
{
- int ret = 0;
+ if (cpu != WORK_CPU_UNBOUND)
+ return &per_cpu(global_cwq, cpu);
+ else
+ return &unbound_global_cwq;
+}
- if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
- BUG_ON(!list_empty(&work->entry));
- __queue_work(wq_per_cpu(wq, cpu), work);
- ret = 1;
- }
- return ret;
+static atomic_t *get_gcwq_nr_running(unsigned int cpu)
+{
+ if (cpu != WORK_CPU_UNBOUND)
+ return &per_cpu(gcwq_nr_running, cpu);
+ else
+ return &unbound_gcwq_nr_running;
}
-EXPORT_SYMBOL_GPL(queue_work_on);
-static void delayed_work_timer_fn(unsigned long __data)
+static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
+ struct workqueue_struct *wq)
{
- struct delayed_work *dwork = (struct delayed_work *)__data;
- struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
- struct workqueue_struct *wq = cwq->wq;
+ if (!(wq->flags & WQ_UNBOUND)) {
+ if (likely(cpu < nr_cpu_ids)) {
+#ifdef CONFIG_SMP
+ return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
+#else
+ return wq->cpu_wq.single;
+#endif
+ }
+ } else if (likely(cpu == WORK_CPU_UNBOUND))
+ return wq->cpu_wq.single;
+ return NULL;
+}
- __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work);
+static unsigned int work_color_to_flags(int color)
+{
+ return color << WORK_STRUCT_COLOR_SHIFT;
}
-/**
- * queue_delayed_work - queue work on a workqueue after delay
- * @wq: workqueue to use
- * @dwork: delayable work to queue
- * @delay: number of jiffies to wait before queueing
- *
- * Returns 0 if @work was already on a queue, non-zero otherwise.
- */
-int queue_delayed_work(struct workqueue_struct *wq,
- struct delayed_work *dwork, unsigned long delay)
+static int get_work_color(struct work_struct *work)
{
- if (delay == 0)
- return queue_work(wq, &dwork->work);
+ return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
+ ((1 << WORK_STRUCT_COLOR_BITS) - 1);
+}
- return queue_delayed_work_on(-1, wq, dwork, delay);
+static int work_next_color(int color)
+{
+ return (color + 1) % WORK_NR_COLORS;
}
-EXPORT_SYMBOL_GPL(queue_delayed_work);
-/**
- * queue_delayed_work_on - queue work on specific CPU after delay
- * @cpu: CPU number to execute work on
- * @wq: workqueue to use
- * @dwork: work to queue
- * @delay: number of jiffies to wait before queueing
+/*
+ * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
+ * work is on queue. Once execution starts, WORK_STRUCT_CWQ is
+ * cleared and the work data contains the cpu number it was last on.
*
- * Returns 0 if @work was already on a queue, non-zero otherwise.
+ * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
+ * cwq, cpu or clear work->data. These functions should only be
+ * called while the work is owned - ie. while the PENDING bit is set.
+ *
+ * get_work_[g]cwq() can be used to obtain the gcwq or cwq
+ * corresponding to a work. gcwq is available once the work has been
+ * queued anywhere after initialization. cwq is available only from
+ * queueing until execution starts.
*/
-int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
- struct delayed_work *dwork, unsigned long delay)
+static inline void set_work_data(struct work_struct *work, unsigned long data,
+ unsigned long flags)
{
- int ret = 0;
- struct timer_list *timer = &dwork->timer;
- struct work_struct *work = &dwork->work;
-
- if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
- BUG_ON(timer_pending(timer));
- BUG_ON(!list_empty(&work->entry));
-
- timer_stats_timer_set_start_info(&dwork->timer);
-
- /* This stores cwq for the moment, for the timer_fn */
- set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id()));
- timer->expires = jiffies + delay;
- timer->data = (unsigned long)dwork;
- timer->function = delayed_work_timer_fn;
-
- if (unlikely(cpu >= 0))
- add_timer_on(timer, cpu);
- else
- add_timer(timer);
- ret = 1;
- }
- return ret;
+ BUG_ON(!work_pending(work));
+ atomic_long_set(&work->data, data | flags | work_static(work));
}
-EXPORT_SYMBOL_GPL(queue_delayed_work_on);
-static void run_workqueue(struct cpu_workqueue_struct *cwq)
+static void set_work_cwq(struct work_struct *work,
+ struct cpu_workqueue_struct *cwq,
+ unsigned long extra_flags)
{
- spin_lock_irq(&cwq->lock);
- cwq->run_depth++;
- if (cwq->run_depth > 3) {
- /* morton gets to eat his hat */
- printk("%s: recursion depth exceeded: %d\n",
- __func__, cwq->run_depth);
- dump_stack();
- }
- while (!list_empty(&cwq->worklist)) {
- struct work_struct *work = list_entry(cwq->worklist.next,
- struct work_struct, entry);
- work_func_t f = work->func;
-#ifdef CONFIG_LOCKDEP
- /*
- * It is permissible to free the struct work_struct
- * from inside the function that is called from it,
- * this we need to take into account for lockdep too.
- * To avoid bogus "held lock freed" warnings as well
- * as problems when looking into work->lockdep_map,
- * make a copy and use that here.
- */
- struct lockdep_map lockdep_map = work->lockdep_map;
-#endif
+ set_work_data(work, (unsigned long)cwq,
+ WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
+}
- cwq->current_work = work;
- list_del_init(cwq->worklist.next);
- spin_unlock_irq(&cwq->lock);
-
- BUG_ON(get_wq_data(work) != cwq);
- work_clear_pending(work);
- lock_map_acquire(&cwq->wq->lockdep_map);
- lock_map_acquire(&lockdep_map);
- f(work);
- lock_map_release(&lockdep_map);
- lock_map_release(&cwq->wq->lockdep_map);
-
- if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
- printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
- "%s/0x%08x/%d\n",
- current->comm, preempt_count(),
- task_pid_nr(current));
- printk(KERN_ERR " last function: ");
- print_symbol("%s\n", (unsigned long)f);
- debug_show_held_locks(current);
- dump_stack();
- }
+static void set_work_cpu(struct work_struct *work, unsigned int cpu)
+{
+ set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING);
+}
- spin_lock_irq(&cwq->lock);
- cwq->current_work = NULL;
- }
- cwq->run_depth--;
- spin_unlock_irq(&cwq->lock);
+static void clear_work_data(struct work_struct *work)
+{
+ set_work_data(work, WORK_STRUCT_NO_CPU, 0);
}
-static int worker_thread(void *__cwq)
+static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
{
- struct cpu_workqueue_struct *cwq = __cwq;
- DEFINE_WAIT(wait);
+ unsigned long data = atomic_long_read(&work->data);
- if (cwq->wq->freezeable)
- set_freezable();
+ if (data & WORK_STRUCT_CWQ)
+ return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
+ else
+ return NULL;
+}
- set_user_nice(current, -5);
+static struct global_cwq *get_work_gcwq(struct work_struct *work)
+{
+ unsigned long data = atomic_long_read(&work->data);
+ unsigned int cpu;
- for (;;) {
- prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
- if (!freezing(current) &&
- !kthread_should_stop() &&
- list_empty(&cwq->worklist))
- schedule();
- finish_wait(&cwq->more_work, &wait);
+ if (data & WORK_STRUCT_CWQ)
+ return ((struct cpu_workqueue_struct *)
+ (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq;
- try_to_freeze();
+ cpu = data >> WORK_STRUCT_FLAG_BITS;
+ if (cpu == WORK_CPU_NONE)
+ return NULL;
- if (kthread_should_stop())
- break;
+ BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND);
+ return get_gcwq(cpu);
+}
- run_workqueue(cwq);
- }
+/*
+ * Policy functions. These define the policies on how the global
+ * worker pool is managed. Unless noted otherwise, these functions
+ * assume that they're being called with gcwq->lock held.
+ */
- return 0;
+static bool __need_more_worker(struct global_cwq *gcwq)
+{
+ return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) ||
+ gcwq->flags & GCWQ_HIGHPRI_PENDING;
}
-struct wq_barrier {
- struct work_struct work;
- struct completion done;
-};
+/*
+ * Need to wake up a worker? Called from anything but currently
+ * running workers.
+ */
+static bool need_more_worker(struct global_cwq *gcwq)
+{
+ return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq);
+}
-static void wq_barrier_func(struct work_struct *work)
+/* Can I start working? Called from busy but !running workers. */
+static bool may_start_working(struct global_cwq *gcwq)
{
- struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
- complete(&barr->done);
+ return gcwq->nr_idle;
}
-static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
- struct wq_barrier *barr, struct list_head *head)
+/* Do I need to keep working? Called from currently running workers. */
+static bool keep_working(struct global_cwq *gcwq)
{
- INIT_WORK(&barr->work, wq_barrier_func);
- __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
+ atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
- init_completion(&barr->done);
+ return !list_empty(&gcwq->worklist) &&
+ (atomic_read(nr_running) <= 1 ||
+ gcwq->flags & GCWQ_HIGHPRI_PENDING);
+}
- insert_work(cwq, &barr->work, head);
+/* Do we need a new worker? Called from manager. */
+static bool need_to_create_worker(struct global_cwq *gcwq)
+{
+ return need_more_worker(gcwq) && !may_start_working(gcwq);
}
-static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
+/* Do I need to be the manager? */
+static bool need_to_manage_workers(struct global_cwq *gcwq)
{
- int active;
+ return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS;
+}
- if (cwq->thread == current) {
- /*
- * Probably keventd trying to flush its own queue. So simply run
- * it by hand rather than deadlocking.
- */
- run_workqueue(cwq);
- active = 1;
- } else {
- struct wq_barrier barr;
+/* Do we have too many workers and should some go away? */
+static bool too_many_workers(struct global_cwq *gcwq)
+{
+ bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS;
+ int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */
+ int nr_busy = gcwq->nr_workers - nr_idle;
- active = 0;
- spin_lock_irq(&cwq->lock);
- if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
- insert_wq_barrier(cwq, &barr, &cwq->worklist);
- active = 1;
- }
- spin_unlock_irq(&cwq->lock);
+ return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
+}
- if (active)
- wait_for_completion(&barr.done);
- }
+/*
+ * Wake up functions.
+ */
+
+/* Return the first worker. Safe with preemption disabled */
+static struct worker *first_worker(struct global_cwq *gcwq)
+{
+ if (unlikely(list_empty(&gcwq->idle_list)))
+ return NULL;
- return active;
+ return list_first_entry(&gcwq->idle_list, struct worker, entry);
}
/**
- * flush_workqueue - ensure that any scheduled work has run to completion.
- * @wq: workqueue to flush
+ * wake_up_worker - wake up an idle worker
+ * @gcwq: gcwq to wake worker for
*
- * Forces execution of the workqueue and blocks until its completion.
- * This is typically used in driver shutdown handlers.
- *
- * We sleep until all works which were queued on entry have been handled,
- * but we are not livelocked by new incoming ones.
+ * Wake up the first idle worker of @gcwq.
*
- * This function used to run the workqueues itself. Now we just wait for the
- * helper threads to do it.
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
*/
-void flush_workqueue(struct workqueue_struct *wq)
+static void wake_up_worker(struct global_cwq *gcwq)
{
- const struct cpumask *cpu_map = wq_cpu_map(wq);
- int cpu;
+ struct worker *worker = first_worker(gcwq);
- might_sleep();
- lock_map_acquire(&wq->lockdep_map);
- lock_map_release(&wq->lockdep_map);
- for_each_cpu_mask_nr(cpu, *cpu_map)
- flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
+ if (likely(worker))
+ wake_up_process(worker->task);
}
-EXPORT_SYMBOL_GPL(flush_workqueue);
/**
- * flush_work - block until a work_struct's callback has terminated
- * @work: the work which is to be flushed
+ * wq_worker_waking_up - a worker is waking up
+ * @task: task waking up
+ * @cpu: CPU @task is waking up to
*
- * Returns false if @work has already terminated.
+ * This function is called during try_to_wake_up() when a worker is
+ * being awoken.
*
- * It is expected that, prior to calling flush_work(), the caller has
- * arranged for the work to not be requeued, otherwise it doesn't make
- * sense to use this function.
+ * CONTEXT:
+ * spin_lock_irq(rq->lock)
*/
-int flush_work(struct work_struct *work)
+void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
+{
+ struct worker *worker = kthread_data(task);
+
+ if (likely(!(worker->flags & WORKER_NOT_RUNNING)))
+ atomic_inc(get_gcwq_nr_running(cpu));
+}
+
+/**
+ * wq_worker_sleeping - a worker is going to sleep
+ * @task: task going to sleep
+ * @cpu: CPU in question, must be the current CPU number
+ *
+ * This function is called during schedule() when a busy worker is
+ * going to sleep. Worker on the same cpu can be woken up by
+ * returning pointer to its task.
+ *
+ * CONTEXT:
+ * spin_lock_irq(rq->lock)
+ *
+ * RETURNS:
+ * Worker task on @cpu to wake up, %NULL if none.
+ */
+struct task_struct *wq_worker_sleeping(struct task_struct *task,
+ unsigned int cpu)
+{
+ struct worker *worker = kthread_data(task), *to_wakeup = NULL;
+ struct global_cwq *gcwq = get_gcwq(cpu);
+ atomic_t *nr_running = get_gcwq_nr_running(cpu);
+
+ if (unlikely(worker->flags & WORKER_NOT_RUNNING))
+ return NULL;
+
+ /* this can only happen on the local cpu */
+ BUG_ON(cpu != raw_smp_processor_id());
+
+ /*
+ * The counterpart of the following dec_and_test, implied mb,
+ * worklist not empty test sequence is in insert_work().
+ * Please read comment there.
+ *
+ * NOT_RUNNING is clear. This means that trustee is not in
+ * charge and we're running on the local cpu w/ rq lock held
+ * and preemption disabled, which in turn means that none else
+ * could be manipulating idle_list, so dereferencing idle_list
+ * without gcwq lock is safe.
+ */
+ if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist))
+ to_wakeup = first_worker(gcwq);
+ return to_wakeup ? to_wakeup->task : NULL;
+}
+
+/**
+ * worker_set_flags - set worker flags and adjust nr_running accordingly
+ * @worker: self
+ * @flags: flags to set
+ * @wakeup: wakeup an idle worker if necessary
+ *
+ * Set @flags in @worker->flags and adjust nr_running accordingly. If
+ * nr_running becomes zero and @wakeup is %true, an idle worker is
+ * woken up.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock)
+ */
+static inline void worker_set_flags(struct worker *worker, unsigned int flags,
+ bool wakeup)
+{
+ struct global_cwq *gcwq = worker->gcwq;
+
+ WARN_ON_ONCE(worker->task != current);
+
+ /*
+ * If transitioning into NOT_RUNNING, adjust nr_running and
+ * wake up an idle worker as necessary if requested by
+ * @wakeup.
+ */
+ if ((flags & WORKER_NOT_RUNNING) &&
+ !(worker->flags & WORKER_NOT_RUNNING)) {
+ atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
+
+ if (wakeup) {
+ if (atomic_dec_and_test(nr_running) &&
+ !list_empty(&gcwq->worklist))
+ wake_up_worker(gcwq);
+ } else
+ atomic_dec(nr_running);
+ }
+
+ worker->flags |= flags;
+}
+
+/**
+ * worker_clr_flags - clear worker flags and adjust nr_running accordingly
+ * @worker: self
+ * @flags: flags to clear
+ *
+ * Clear @flags in @worker->flags and adjust nr_running accordingly.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock)
+ */
+static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
+{
+ struct global_cwq *gcwq = worker->gcwq;
+ unsigned int oflags = worker->flags;
+
+ WARN_ON_ONCE(worker->task != current);
+
+ worker->flags &= ~flags;
+
+ /* if transitioning out of NOT_RUNNING, increment nr_running */
+ if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
+ if (!(worker->flags & WORKER_NOT_RUNNING))
+ atomic_inc(get_gcwq_nr_running(gcwq->cpu));
+}
+
+/**
+ * busy_worker_head - return the busy hash head for a work
+ * @gcwq: gcwq of interest
+ * @work: work to be hashed
+ *
+ * Return hash head of @gcwq for @work.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ *
+ * RETURNS:
+ * Pointer to the hash head.
+ */
+static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
+ struct work_struct *work)
+{
+ const int base_shift = ilog2(sizeof(struct work_struct));
+ unsigned long v = (unsigned long)work;
+
+ /* simple shift and fold hash, do we need something better? */
+ v >>= base_shift;
+ v += v >> BUSY_WORKER_HASH_ORDER;
+ v &= BUSY_WORKER_HASH_MASK;
+
+ return &gcwq->busy_hash[v];
+}
+
+/**
+ * __find_worker_executing_work - find worker which is executing a work
+ * @gcwq: gcwq of interest
+ * @bwh: hash head as returned by busy_worker_head()
+ * @work: work to find worker for
+ *
+ * Find a worker which is executing @work on @gcwq. @bwh should be
+ * the hash head obtained by calling busy_worker_head() with the same
+ * work.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ *
+ * RETURNS:
+ * Pointer to worker which is executing @work if found, NULL
+ * otherwise.
+ */
+static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,
+ struct hlist_head *bwh,
+ struct work_struct *work)
+{
+ struct worker *worker;
+ struct hlist_node *tmp;
+
+ hlist_for_each_entry(worker, tmp, bwh, hentry)
+ if (worker->current_work == work)
+ return worker;
+ return NULL;
+}
+
+/**
+ * find_worker_executing_work - find worker which is executing a work
+ * @gcwq: gcwq of interest
+ * @work: work to find worker for
+ *
+ * Find a worker which is executing @work on @gcwq. This function is
+ * identical to __find_worker_executing_work() except that this
+ * function calculates @bwh itself.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ *
+ * RETURNS:
+ * Pointer to worker which is executing @work if found, NULL
+ * otherwise.
+ */
+static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
+ struct work_struct *work)
+{
+ return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),
+ work);
+}
+
+/**
+ * gcwq_determine_ins_pos - find insertion position
+ * @gcwq: gcwq of interest
+ * @cwq: cwq a work is being queued for
+ *
+ * A work for @cwq is about to be queued on @gcwq, determine insertion
+ * position for the work. If @cwq is for HIGHPRI wq, the work is
+ * queued at the head of the queue but in FIFO order with respect to
+ * other HIGHPRI works; otherwise, at the end of the queue. This
+ * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that
+ * there are HIGHPRI works pending.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ *
+ * RETURNS:
+ * Pointer to inserstion position.
+ */
+static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq,
+ struct cpu_workqueue_struct *cwq)
+{
+ struct work_struct *twork;
+
+ if (likely(!(cwq->wq->flags & WQ_HIGHPRI)))
+ return &gcwq->worklist;
+
+ list_for_each_entry(twork, &gcwq->worklist, entry) {
+ struct cpu_workqueue_struct *tcwq = get_work_cwq(twork);
+
+ if (!(tcwq->wq->flags & WQ_HIGHPRI))
+ break;
+ }
+
+ gcwq->flags |= GCWQ_HIGHPRI_PENDING;
+ return &twork->entry;
+}
+
+/**
+ * insert_work - insert a work into gcwq
+ * @cwq: cwq @work belongs to
+ * @work: work to insert
+ * @head: insertion point
+ * @extra_flags: extra WORK_STRUCT_* flags to set
+ *
+ * Insert @work which belongs to @cwq into @gcwq after @head.
+ * @extra_flags is or'd to work_struct flags.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void insert_work(struct cpu_workqueue_struct *cwq,
+ struct work_struct *work, struct list_head *head,
+ unsigned int extra_flags)
+{
+ struct global_cwq *gcwq = cwq->gcwq;
+
+ /* we own @work, set data and link */
+ set_work_cwq(work, cwq, extra_flags);
+
+ /*
+ * Ensure that we get the right work->data if we see the
+ * result of list_add() below, see try_to_grab_pending().
+ */
+ smp_wmb();
+
+ list_add_tail(&work->entry, head);
+
+ /*
+ * Ensure either worker_sched_deactivated() sees the above
+ * list_add_tail() or we see zero nr_running to avoid workers
+ * lying around lazily while there are works to be processed.
+ */
+ smp_mb();
+
+ if (__need_more_worker(gcwq))
+ wake_up_worker(gcwq);
+}
+
+static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
+ struct work_struct *work)
+{
+ struct global_cwq *gcwq;
+ struct cpu_workqueue_struct *cwq;
+ struct list_head *worklist;
+ unsigned int work_flags;
+ unsigned long flags;
+
+ debug_work_activate(work);
+
+ if (WARN_ON_ONCE(wq->flags & WQ_DYING))
+ return;
+
+ /* determine gcwq to use */
+ if (!(wq->flags & WQ_UNBOUND)) {
+ struct global_cwq *last_gcwq;
+
+ if (unlikely(cpu == WORK_CPU_UNBOUND))
+ cpu = raw_smp_processor_id();
+
+ /*
+ * It's multi cpu. If @wq is non-reentrant and @work
+ * was previously on a different cpu, it might still
+ * be running there, in which case the work needs to
+ * be queued on that cpu to guarantee non-reentrance.
+ */
+ gcwq = get_gcwq(cpu);
+ if (wq->flags & WQ_NON_REENTRANT &&
+ (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) {
+ struct worker *worker;
+
+ spin_lock_irqsave(&last_gcwq->lock, flags);
+
+ worker = find_worker_executing_work(last_gcwq, work);
+
+ if (worker && worker->current_cwq->wq == wq)
+ gcwq = last_gcwq;
+ else {
+ /* meh... not running there, queue here */
+ spin_unlock_irqrestore(&last_gcwq->lock, flags);
+ spin_lock_irqsave(&gcwq->lock, flags);
+ }
+ } else
+ spin_lock_irqsave(&gcwq->lock, flags);
+ } else {
+ gcwq = get_gcwq(WORK_CPU_UNBOUND);
+ spin_lock_irqsave(&gcwq->lock, flags);
+ }
+
+ /* gcwq determined, get cwq and queue */
+ cwq = get_cwq(gcwq->cpu, wq);
+ trace_workqueue_queue_work(cpu, cwq, work);
+
+ BUG_ON(!list_empty(&work->entry));
+
+ cwq->nr_in_flight[cwq->work_color]++;
+ work_flags = work_color_to_flags(cwq->work_color);
+
+ if (likely(cwq->nr_active < cwq->max_active)) {
+ trace_workqueue_activate_work(work);
+ cwq->nr_active++;
+ worklist = gcwq_determine_ins_pos(gcwq, cwq);
+ } else {
+ work_flags |= WORK_STRUCT_DELAYED;
+ worklist = &cwq->delayed_works;
+ }
+
+ insert_work(cwq, work, worklist, work_flags);
+
+ spin_unlock_irqrestore(&gcwq->lock, flags);
+}
+
+/**
+ * queue_work - queue work on a workqueue
+ * @wq: workqueue to use
+ * @work: work to queue
+ *
+ * Returns 0 if @work was already on a queue, non-zero otherwise.
+ *
+ * We queue the work to the CPU on which it was submitted, but if the CPU dies
+ * it can be processed by another CPU.
+ */
+int queue_work(struct workqueue_struct *wq, struct work_struct *work)
+{
+ int ret;
+
+ ret = queue_work_on(get_cpu(), wq, work);
+ put_cpu();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(queue_work);
+
+/**
+ * queue_work_on - queue work on specific cpu
+ * @cpu: CPU number to execute work on
+ * @wq: workqueue to use
+ * @work: work to queue
+ *
+ * Returns 0 if @work was already on a queue, non-zero otherwise.
+ *
+ * We queue the work to a specific CPU, the caller must ensure it
+ * can't go away.
+ */
+int
+queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
+{
+ int ret = 0;
+
+ if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
+ __queue_work(cpu, wq, work);
+ ret = 1;
+ }
+ return ret;
+}
+EXPORT_SYMBOL_GPL(queue_work_on);
+
+static void delayed_work_timer_fn(unsigned long __data)
+{
+ struct delayed_work *dwork = (struct delayed_work *)__data;
+ struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
+
+ __queue_work(smp_processor_id(), cwq->wq, &dwork->work);
+}
+
+/**
+ * queue_delayed_work - queue work on a workqueue after delay
+ * @wq: workqueue to use
+ * @dwork: delayable work to queue
+ * @delay: number of jiffies to wait before queueing
+ *
+ * Returns 0 if @work was already on a queue, non-zero otherwise.
+ */
+int queue_delayed_work(struct workqueue_struct *wq,
+ struct delayed_work *dwork, unsigned long delay)
+{
+ if (delay == 0)
+ return queue_work(wq, &dwork->work);
+
+ return queue_delayed_work_on(-1, wq, dwork, delay);
+}
+EXPORT_SYMBOL_GPL(queue_delayed_work);
+
+/**
+ * queue_delayed_work_on - queue work on specific CPU after delay
+ * @cpu: CPU number to execute work on
+ * @wq: workqueue to use
+ * @dwork: work to queue
+ * @delay: number of jiffies to wait before queueing
+ *
+ * Returns 0 if @work was already on a queue, non-zero otherwise.
+ */
+int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
+ struct delayed_work *dwork, unsigned long delay)
+{
+ int ret = 0;
+ struct timer_list *timer = &dwork->timer;
+ struct work_struct *work = &dwork->work;
+
+ if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
+ unsigned int lcpu;
+
+ BUG_ON(timer_pending(timer));
+ BUG_ON(!list_empty(&work->entry));
+
+ timer_stats_timer_set_start_info(&dwork->timer);
+
+ /*
+ * This stores cwq for the moment, for the timer_fn.
+ * Note that the work's gcwq is preserved to allow
+ * reentrance detection for delayed works.
+ */
+ if (!(wq->flags & WQ_UNBOUND)) {
+ struct global_cwq *gcwq = get_work_gcwq(work);
+
+ if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND)
+ lcpu = gcwq->cpu;
+ else
+ lcpu = raw_smp_processor_id();
+ } else
+ lcpu = WORK_CPU_UNBOUND;
+
+ set_work_cwq(work, get_cwq(lcpu, wq), 0);
+
+ timer->expires = jiffies + delay;
+ timer->data = (unsigned long)dwork;
+ timer->function = delayed_work_timer_fn;
+
+ if (unlikely(cpu >= 0))
+ add_timer_on(timer, cpu);
+ else
+ add_timer(timer);
+ ret = 1;
+ }
+ return ret;
+}
+EXPORT_SYMBOL_GPL(queue_delayed_work_on);
+
+/**
+ * worker_enter_idle - enter idle state
+ * @worker: worker which is entering idle state
+ *
+ * @worker is entering idle state. Update stats and idle timer if
+ * necessary.
+ *
+ * LOCKING:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void worker_enter_idle(struct worker *worker)
+{
+ struct global_cwq *gcwq = worker->gcwq;
+
+ BUG_ON(worker->flags & WORKER_IDLE);
+ BUG_ON(!list_empty(&worker->entry) &&
+ (worker->hentry.next || worker->hentry.pprev));
+
+ /* can't use worker_set_flags(), also called from start_worker() */
+ worker->flags |= WORKER_IDLE;
+ gcwq->nr_idle++;
+ worker->last_active = jiffies;
+
+ /* idle_list is LIFO */
+ list_add(&worker->entry, &gcwq->idle_list);
+
+ if (likely(!(worker->flags & WORKER_ROGUE))) {
+ if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer))
+ mod_timer(&gcwq->idle_timer,
+ jiffies + IDLE_WORKER_TIMEOUT);
+ } else
+ wake_up_all(&gcwq->trustee_wait);
+
+ /* sanity check nr_running */
+ WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle &&
+ atomic_read(get_gcwq_nr_running(gcwq->cpu)));
+}
+
+/**
+ * worker_leave_idle - leave idle state
+ * @worker: worker which is leaving idle state
+ *
+ * @worker is leaving idle state. Update stats.
+ *
+ * LOCKING:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void worker_leave_idle(struct worker *worker)
+{
+ struct global_cwq *gcwq = worker->gcwq;
+
+ BUG_ON(!(worker->flags & WORKER_IDLE));
+ worker_clr_flags(worker, WORKER_IDLE);
+ gcwq->nr_idle--;
+ list_del_init(&worker->entry);
+}
+
+/**
+ * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
+ * @worker: self
+ *
+ * Works which are scheduled while the cpu is online must at least be
+ * scheduled to a worker which is bound to the cpu so that if they are
+ * flushed from cpu callbacks while cpu is going down, they are
+ * guaranteed to execute on the cpu.
+ *
+ * This function is to be used by rogue workers and rescuers to bind
+ * themselves to the target cpu and may race with cpu going down or
+ * coming online. kthread_bind() can't be used because it may put the
+ * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
+ * verbatim as it's best effort and blocking and gcwq may be
+ * [dis]associated in the meantime.
+ *
+ * This function tries set_cpus_allowed() and locks gcwq and verifies
+ * the binding against GCWQ_DISASSOCIATED which is set during
+ * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters
+ * idle state or fetches works without dropping lock, it can guarantee
+ * the scheduling requirement described in the first paragraph.
+ *
+ * CONTEXT:
+ * Might sleep. Called without any lock but returns with gcwq->lock
+ * held.
+ *
+ * RETURNS:
+ * %true if the associated gcwq is online (@worker is successfully
+ * bound), %false if offline.
+ */
+static bool worker_maybe_bind_and_lock(struct worker *worker)
+__acquires(&gcwq->lock)
+{
+ struct global_cwq *gcwq = worker->gcwq;
+ struct task_struct *task = worker->task;
+
+ while (true) {
+ /*
+ * The following call may fail, succeed or succeed
+ * without actually migrating the task to the cpu if
+ * it races with cpu hotunplug operation. Verify
+ * against GCWQ_DISASSOCIATED.
+ */
+ if (!(gcwq->flags & GCWQ_DISASSOCIATED))
+ set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
+
+ spin_lock_irq(&gcwq->lock);
+ if (gcwq->flags & GCWQ_DISASSOCIATED)
+ return false;
+ if (task_cpu(task) == gcwq->cpu &&
+ cpumask_equal(¤t->cpus_allowed,
+ get_cpu_mask(gcwq->cpu)))
+ return true;
+ spin_unlock_irq(&gcwq->lock);
+
+ /* CPU has come up inbetween, retry migration */
+ cpu_relax();
+ }
+}
+
+/*
+ * Function for worker->rebind_work used to rebind rogue busy workers
+ * to the associated cpu which is coming back online. This is
+ * scheduled by cpu up but can race with other cpu hotplug operations
+ * and may be executed twice without intervening cpu down.
+ */
+static void worker_rebind_fn(struct work_struct *work)
+{
+ struct worker *worker = container_of(work, struct worker, rebind_work);
+ struct global_cwq *gcwq = worker->gcwq;
+
+ if (worker_maybe_bind_and_lock(worker))
+ worker_clr_flags(worker, WORKER_REBIND);
+
+ spin_unlock_irq(&gcwq->lock);
+}
+
+static struct worker *alloc_worker(void)
+{
+ struct worker *worker;
+
+ worker = kzalloc(sizeof(*worker), GFP_KERNEL);
+ if (worker) {
+ INIT_LIST_HEAD(&worker->entry);
+ INIT_LIST_HEAD(&worker->scheduled);
+ INIT_WORK(&worker->rebind_work, worker_rebind_fn);
+ /* on creation a worker is in !idle && prep state */
+ worker->flags = WORKER_PREP;
+ }
+ return worker;
+}
+
+/**
+ * create_worker - create a new workqueue worker
+ * @gcwq: gcwq the new worker will belong to
+ * @bind: whether to set affinity to @cpu or not
+ *
+ * Create a new worker which is bound to @gcwq. The returned worker
+ * can be started by calling start_worker() or destroyed using
+ * destroy_worker().
+ *
+ * CONTEXT:
+ * Might sleep. Does GFP_KERNEL allocations.
+ *
+ * RETURNS:
+ * Pointer to the newly created worker.
+ */
+static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
+{
+ bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND;
+ struct worker *worker = NULL;
+ int id = -1;
+
+ spin_lock_irq(&gcwq->lock);
+ while (ida_get_new(&gcwq->worker_ida, &id)) {
+ spin_unlock_irq(&gcwq->lock);
+ if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL))
+ goto fail;
+ spin_lock_irq(&gcwq->lock);
+ }
+ spin_unlock_irq(&gcwq->lock);
+
+ worker = alloc_worker();
+ if (!worker)
+ goto fail;
+
+ worker->gcwq = gcwq;
+ worker->id = id;
+
+ if (!on_unbound_cpu)
+ worker->task = kthread_create(worker_thread, worker,
+ "kworker/%u:%d", gcwq->cpu, id);
+ else
+ worker->task = kthread_create(worker_thread, worker,
+ "kworker/u:%d", id);
+ if (IS_ERR(worker->task))
+ goto fail;
+
+ /*
+ * A rogue worker will become a regular one if CPU comes
+ * online later on. Make sure every worker has
+ * PF_THREAD_BOUND set.
+ */
+ if (bind && !on_unbound_cpu)
+ kthread_bind(worker->task, gcwq->cpu);
+ else {
+ worker->task->flags |= PF_THREAD_BOUND;
+ if (on_unbound_cpu)
+ worker->flags |= WORKER_UNBOUND;
+ }
+
+ return worker;
+fail:
+ if (id >= 0) {
+ spin_lock_irq(&gcwq->lock);
+ ida_remove(&gcwq->worker_ida, id);
+ spin_unlock_irq(&gcwq->lock);
+ }
+ kfree(worker);
+ return NULL;
+}
+
+/**
+ * start_worker - start a newly created worker
+ * @worker: worker to start
+ *
+ * Make the gcwq aware of @worker and start it.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void start_worker(struct worker *worker)
+{
+ worker->flags |= WORKER_STARTED;
+ worker->gcwq->nr_workers++;
+ worker_enter_idle(worker);
+ wake_up_process(worker->task);
+}
+
+/**
+ * destroy_worker - destroy a workqueue worker
+ * @worker: worker to be destroyed
+ *
+ * Destroy @worker and adjust @gcwq stats accordingly.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which is released and regrabbed.
+ */
+static void destroy_worker(struct worker *worker)
+{
+ struct global_cwq *gcwq = worker->gcwq;
+ int id = worker->id;
+
+ /* sanity check frenzy */
+ BUG_ON(worker->current_work);
+ BUG_ON(!list_empty(&worker->scheduled));
+
+ if (worker->flags & WORKER_STARTED)
+ gcwq->nr_workers--;
+ if (worker->flags & WORKER_IDLE)
+ gcwq->nr_idle--;
+
+ list_del_init(&worker->entry);
+ worker->flags |= WORKER_DIE;
+
+ spin_unlock_irq(&gcwq->lock);
+
+ kthread_stop(worker->task);
+ kfree(worker);
+
+ spin_lock_irq(&gcwq->lock);
+ ida_remove(&gcwq->worker_ida, id);
+}
+
+static void idle_worker_timeout(unsigned long __gcwq)
+{
+ struct global_cwq *gcwq = (void *)__gcwq;
+
+ spin_lock_irq(&gcwq->lock);
+
+ if (too_many_workers(gcwq)) {
+ struct worker *worker;
+ unsigned long expires;
+
+ /* idle_list is kept in LIFO order, check the last one */
+ worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
+ expires = worker->last_active + IDLE_WORKER_TIMEOUT;
+
+ if (time_before(jiffies, expires))
+ mod_timer(&gcwq->idle_timer, expires);
+ else {
+ /* it's been idle for too long, wake up manager */
+ gcwq->flags |= GCWQ_MANAGE_WORKERS;
+ wake_up_worker(gcwq);
+ }
+ }
+
+ spin_unlock_irq(&gcwq->lock);
+}
+
+static bool send_mayday(struct work_struct *work)
+{
+ struct cpu_workqueue_struct *cwq = get_work_cwq(work);
+ struct workqueue_struct *wq = cwq->wq;
+ unsigned int cpu;
+
+ if (!(wq->flags & WQ_RESCUER))
+ return false;
+
+ /* mayday mayday mayday */
+ cpu = cwq->gcwq->cpu;
+ /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
+ if (cpu == WORK_CPU_UNBOUND)
+ cpu = 0;
+ if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask))
+ wake_up_process(wq->rescuer->task);
+ return true;
+}
+
+static void gcwq_mayday_timeout(unsigned long __gcwq)
+{
+ struct global_cwq *gcwq = (void *)__gcwq;
+ struct work_struct *work;
+
+ spin_lock_irq(&gcwq->lock);
+
+ if (need_to_create_worker(gcwq)) {
+ /*
+ * We've been trying to create a new worker but
+ * haven't been successful. We might be hitting an
+ * allocation deadlock. Send distress signals to
+ * rescuers.
+ */
+ list_for_each_entry(work, &gcwq->worklist, entry)
+ send_mayday(work);
+ }
+
+ spin_unlock_irq(&gcwq->lock);
+
+ mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL);
+}
+
+/**
+ * maybe_create_worker - create a new worker if necessary
+ * @gcwq: gcwq to create a new worker for
+ *
+ * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to
+ * have at least one idle worker on return from this function. If
+ * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
+ * sent to all rescuers with works scheduled on @gcwq to resolve
+ * possible allocation deadlock.
+ *
+ * On return, need_to_create_worker() is guaranteed to be false and
+ * may_start_working() true.
+ *
+ * LOCKING:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times. Does GFP_KERNEL allocations. Called only from
+ * manager.
+ *
+ * RETURNS:
+ * false if no action was taken and gcwq->lock stayed locked, true
+ * otherwise.
+ */
+static bool maybe_create_worker(struct global_cwq *gcwq)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
+{
+ if (!need_to_create_worker(gcwq))
+ return false;
+restart:
+ spin_unlock_irq(&gcwq->lock);
+
+ /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
+ mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
+
+ while (true) {
+ struct worker *worker;
+
+ worker = create_worker(gcwq, true);
+ if (worker) {
+ del_timer_sync(&gcwq->mayday_timer);
+ spin_lock_irq(&gcwq->lock);
+ start_worker(worker);
+ BUG_ON(need_to_create_worker(gcwq));
+ return true;
+ }
+
+ if (!need_to_create_worker(gcwq))
+ break;
+
+ __set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(CREATE_COOLDOWN);
+
+ if (!need_to_create_worker(gcwq))
+ break;
+ }
+
+ del_timer_sync(&gcwq->mayday_timer);
+ spin_lock_irq(&gcwq->lock);
+ if (need_to_create_worker(gcwq))
+ goto restart;
+ return true;
+}
+
+/**
+ * maybe_destroy_worker - destroy workers which have been idle for a while
+ * @gcwq: gcwq to destroy workers for
+ *
+ * Destroy @gcwq workers which have been idle for longer than
+ * IDLE_WORKER_TIMEOUT.
+ *
+ * LOCKING:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times. Called only from manager.
+ *
+ * RETURNS:
+ * false if no action was taken and gcwq->lock stayed locked, true
+ * otherwise.
+ */
+static bool maybe_destroy_workers(struct global_cwq *gcwq)
+{
+ bool ret = false;
+
+ while (too_many_workers(gcwq)) {
+ struct worker *worker;
+ unsigned long expires;
+
+ worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
+ expires = worker->last_active + IDLE_WORKER_TIMEOUT;
+
+ if (time_before(jiffies, expires)) {
+ mod_timer(&gcwq->idle_timer, expires);
+ break;
+ }
+
+ destroy_worker(worker);
+ ret = true;
+ }
+
+ return ret;
+}
+
+/**
+ * manage_workers - manage worker pool
+ * @worker: self
+ *
+ * Assume the manager role and manage gcwq worker pool @worker belongs
+ * to. At any given time, there can be only zero or one manager per
+ * gcwq. The exclusion is handled automatically by this function.
+ *
+ * The caller can safely start processing works on false return. On
+ * true return, it's guaranteed that need_to_create_worker() is false
+ * and may_start_working() is true.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times. Does GFP_KERNEL allocations.
+ *
+ * RETURNS:
+ * false if no action was taken and gcwq->lock stayed locked, true if
+ * some action was taken.
+ */
+static bool manage_workers(struct worker *worker)
+{
+ struct global_cwq *gcwq = worker->gcwq;
+ bool ret = false;
+
+ if (gcwq->flags & GCWQ_MANAGING_WORKERS)
+ return ret;
+
+ gcwq->flags &= ~GCWQ_MANAGE_WORKERS;
+ gcwq->flags |= GCWQ_MANAGING_WORKERS;
+
+ /*
+ * Destroy and then create so that may_start_working() is true
+ * on return.
+ */
+ ret |= maybe_destroy_workers(gcwq);
+ ret |= maybe_create_worker(gcwq);
+
+ gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
+
+ /*
+ * The trustee might be waiting to take over the manager
+ * position, tell it we're done.
+ */
+ if (unlikely(gcwq->trustee))
+ wake_up_all(&gcwq->trustee_wait);
+
+ return ret;
+}
+
+/**
+ * move_linked_works - move linked works to a list
+ * @work: start of series of works to be scheduled
+ * @head: target list to append @work to
+ * @nextp: out paramter for nested worklist walking
+ *
+ * Schedule linked works starting from @work to @head. Work series to
+ * be scheduled starts at @work and includes any consecutive work with
+ * WORK_STRUCT_LINKED set in its predecessor.
+ *
+ * If @nextp is not NULL, it's updated to point to the next work of
+ * the last scheduled work. This allows move_linked_works() to be
+ * nested inside outer list_for_each_entry_safe().
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void move_linked_works(struct work_struct *work, struct list_head *head,
+ struct work_struct **nextp)
+{
+ struct work_struct *n;
+
+ /*
+ * Linked worklist will always end before the end of the list,
+ * use NULL for list head.
+ */
+ list_for_each_entry_safe_from(work, n, NULL, entry) {
+ list_move_tail(&work->entry, head);
+ if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
+ break;
+ }
+
+ /*
+ * If we're already inside safe list traversal and have moved
+ * multiple works to the scheduled queue, the next position
+ * needs to be updated.
+ */
+ if (nextp)
+ *nextp = n;
+}
+
+static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
+{
+ struct work_struct *work = list_first_entry(&cwq->delayed_works,
+ struct work_struct, entry);
+ struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
+
+ trace_workqueue_activate_work(work);
+ move_linked_works(work, pos, NULL);
+ __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
+ cwq->nr_active++;
+}
+
+/**
+ * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
+ * @cwq: cwq of interest
+ * @color: color of work which left the queue
+ * @delayed: for a delayed work
+ *
+ * A work either has completed or is removed from pending queue,
+ * decrement nr_in_flight of its cwq and handle workqueue flushing.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
+ bool delayed)
+{
+ /* ignore uncolored works */
+ if (color == WORK_NO_COLOR)
+ return;
+
+ cwq->nr_in_flight[color]--;
+
+ if (!delayed) {
+ cwq->nr_active--;
+ if (!list_empty(&cwq->delayed_works)) {
+ /* one down, submit a delayed one */
+ if (cwq->nr_active < cwq->max_active)
+ cwq_activate_first_delayed(cwq);
+ }
+ }
+
+ /* is flush in progress and are we at the flushing tip? */
+ if (likely(cwq->flush_color != color))
+ return;
+
+ /* are there still in-flight works? */
+ if (cwq->nr_in_flight[color])
+ return;
+
+ /* this cwq is done, clear flush_color */
+ cwq->flush_color = -1;
+
+ /*
+ * If this was the last cwq, wake up the first flusher. It
+ * will handle the rest.
+ */
+ if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
+ complete(&cwq->wq->first_flusher->done);
+}
+
+/**
+ * process_one_work - process single work
+ * @worker: self
+ * @work: work to process
+ *
+ * Process @work. This function contains all the logics necessary to
+ * process a single work including synchronization against and
+ * interaction with other workers on the same cpu, queueing and
+ * flushing. As long as context requirement is met, any worker can
+ * call this function to process a work.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which is released and regrabbed.
+ */
+static void process_one_work(struct worker *worker, struct work_struct *work)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
+{
+ struct cpu_workqueue_struct *cwq = get_work_cwq(work);
+ struct global_cwq *gcwq = cwq->gcwq;
+ struct hlist_head *bwh = busy_worker_head(gcwq, work);
+ bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
+ work_func_t f = work->func;
+ int work_color;
+ struct worker *collision;
+#ifdef CONFIG_LOCKDEP
+ /*
+ * It is permissible to free the struct work_struct from
+ * inside the function that is called from it, this we need to
+ * take into account for lockdep too. To avoid bogus "held
+ * lock freed" warnings as well as problems when looking into
+ * work->lockdep_map, make a copy and use that here.
+ */
+ struct lockdep_map lockdep_map = work->lockdep_map;
+#endif
+ /*
+ * A single work shouldn't be executed concurrently by
+ * multiple workers on a single cpu. Check whether anyone is
+ * already processing the work. If so, defer the work to the
+ * currently executing one.
+ */
+ collision = __find_worker_executing_work(gcwq, bwh, work);
+ if (unlikely(collision)) {
+ move_linked_works(work, &collision->scheduled, NULL);
+ return;
+ }
+
+ /* claim and process */
+ debug_work_deactivate(work);
+ hlist_add_head(&worker->hentry, bwh);
+ worker->current_work = work;
+ worker->current_cwq = cwq;
+ work_color = get_work_color(work);
+
+ /* record the current cpu number in the work data and dequeue */
+ set_work_cpu(work, gcwq->cpu);
+ list_del_init(&work->entry);
+
+ /*
+ * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI,
+ * wake up another worker; otherwise, clear HIGHPRI_PENDING.
+ */
+ if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) {
+ struct work_struct *nwork = list_first_entry(&gcwq->worklist,
+ struct work_struct, entry);
+
+ if (!list_empty(&gcwq->worklist) &&
+ get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI)
+ wake_up_worker(gcwq);
+ else
+ gcwq->flags &= ~GCWQ_HIGHPRI_PENDING;
+ }
+
+ /*
+ * CPU intensive works don't participate in concurrency
+ * management. They're the scheduler's responsibility.
+ */
+ if (unlikely(cpu_intensive))
+ worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
+
+ spin_unlock_irq(&gcwq->lock);
+
+ work_clear_pending(work);
+ lock_map_acquire(&cwq->wq->lockdep_map);
+ lock_map_acquire(&lockdep_map);
+ trace_workqueue_execute_start(work);
+ f(work);
+ /*
+ * While we must be careful to not use "work" after this, the trace
+ * point will only record its address.
+ */
+ trace_workqueue_execute_end(work);
+ lock_map_release(&lockdep_map);
+ lock_map_release(&cwq->wq->lockdep_map);
+
+ if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
+ printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
+ "%s/0x%08x/%d\n",
+ current->comm, preempt_count(), task_pid_nr(current));
+ printk(KERN_ERR " last function: ");
+ print_symbol("%s\n", (unsigned long)f);
+ debug_show_held_locks(current);
+ dump_stack();
+ }
+
+ spin_lock_irq(&gcwq->lock);
+
+ /* clear cpu intensive status */
+ if (unlikely(cpu_intensive))
+ worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
+
+ /* we're done with it, release */
+ hlist_del_init(&worker->hentry);
+ worker->current_work = NULL;
+ worker->current_cwq = NULL;
+ cwq_dec_nr_in_flight(cwq, work_color, false);
+}
+
+/**
+ * process_scheduled_works - process scheduled works
+ * @worker: self
+ *
+ * Process all scheduled works. Please note that the scheduled list
+ * may change while processing a work, so this function repeatedly
+ * fetches a work from the top and executes it.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times.
+ */
+static void process_scheduled_works(struct worker *worker)
+{
+ while (!list_empty(&worker->scheduled)) {
+ struct work_struct *work = list_first_entry(&worker->scheduled,
+ struct work_struct, entry);
+ process_one_work(worker, work);
+ }
+}
+
+/**
+ * worker_thread - the worker thread function
+ * @__worker: self
+ *
+ * The gcwq worker thread function. There's a single dynamic pool of
+ * these per each cpu. These workers process all works regardless of
+ * their specific target workqueue. The only exception is works which
+ * belong to workqueues with a rescuer which will be explained in
+ * rescuer_thread().
+ */
+static int worker_thread(void *__worker)
+{
+ struct worker *worker = __worker;
+ struct global_cwq *gcwq = worker->gcwq;
+
+ /* tell the scheduler that this is a workqueue worker */
+ worker->task->flags |= PF_WQ_WORKER;
+woke_up:
+ spin_lock_irq(&gcwq->lock);
+
+ /* DIE can be set only while we're idle, checking here is enough */
+ if (worker->flags & WORKER_DIE) {
+ spin_unlock_irq(&gcwq->lock);
+ worker->task->flags &= ~PF_WQ_WORKER;
+ return 0;
+ }
+
+ worker_leave_idle(worker);
+recheck:
+ /* no more worker necessary? */
+ if (!need_more_worker(gcwq))
+ goto sleep;
+
+ /* do we need to manage? */
+ if (unlikely(!may_start_working(gcwq)) && manage_workers(worker))
+ goto recheck;
+
+ /*
+ * ->scheduled list can only be filled while a worker is
+ * preparing to process a work or actually processing it.
+ * Make sure nobody diddled with it while I was sleeping.
+ */
+ BUG_ON(!list_empty(&worker->scheduled));
+
+ /*
+ * When control reaches this point, we're guaranteed to have
+ * at least one idle worker or that someone else has already
+ * assumed the manager role.
+ */
+ worker_clr_flags(worker, WORKER_PREP);
+
+ do {
+ struct work_struct *work =
+ list_first_entry(&gcwq->worklist,
+ struct work_struct, entry);
+
+ if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
+ /* optimization path, not strictly necessary */
+ process_one_work(worker, work);
+ if (unlikely(!list_empty(&worker->scheduled)))
+ process_scheduled_works(worker);
+ } else {
+ move_linked_works(work, &worker->scheduled, NULL);
+ process_scheduled_works(worker);
+ }
+ } while (keep_working(gcwq));
+
+ worker_set_flags(worker, WORKER_PREP, false);
+sleep:
+ if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker))
+ goto recheck;
+
+ /*
+ * gcwq->lock is held and there's no work to process and no
+ * need to manage, sleep. Workers are woken up only while
+ * holding gcwq->lock or from local cpu, so setting the
+ * current state before releasing gcwq->lock is enough to
+ * prevent losing any event.
+ */
+ worker_enter_idle(worker);
+ __set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock_irq(&gcwq->lock);
+ schedule();
+ goto woke_up;
+}
+
+/**
+ * rescuer_thread - the rescuer thread function
+ * @__wq: the associated workqueue
+ *
+ * Workqueue rescuer thread function. There's one rescuer for each
+ * workqueue which has WQ_RESCUER set.
+ *
+ * Regular work processing on a gcwq may block trying to create a new
+ * worker which uses GFP_KERNEL allocation which has slight chance of
+ * developing into deadlock if some works currently on the same queue
+ * need to be processed to satisfy the GFP_KERNEL allocation. This is
+ * the problem rescuer solves.
+ *
+ * When such condition is possible, the gcwq summons rescuers of all
+ * workqueues which have works queued on the gcwq and let them process
+ * those works so that forward progress can be guaranteed.
+ *
+ * This should happen rarely.
+ */
+static int rescuer_thread(void *__wq)
+{
+ struct workqueue_struct *wq = __wq;
+ struct worker *rescuer = wq->rescuer;
+ struct list_head *scheduled = &rescuer->scheduled;
+ bool is_unbound = wq->flags & WQ_UNBOUND;
+ unsigned int cpu;
+
+ set_user_nice(current, RESCUER_NICE_LEVEL);
+repeat:
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ if (kthread_should_stop())
+ return 0;
+
+ /*
+ * See whether any cpu is asking for help. Unbounded
+ * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
+ */
+ for_each_mayday_cpu(cpu, wq->mayday_mask) {
+ unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
+ struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
+ struct global_cwq *gcwq = cwq->gcwq;
+ struct work_struct *work, *n;
+
+ __set_current_state(TASK_RUNNING);
+ mayday_clear_cpu(cpu, wq->mayday_mask);
+
+ /* migrate to the target cpu if possible */
+ rescuer->gcwq = gcwq;
+ worker_maybe_bind_and_lock(rescuer);
+
+ /*
+ * Slurp in all works issued via this workqueue and
+ * process'em.
+ */
+ BUG_ON(!list_empty(&rescuer->scheduled));
+ list_for_each_entry_safe(work, n, &gcwq->worklist, entry)
+ if (get_work_cwq(work) == cwq)
+ move_linked_works(work, scheduled, &n);
+
+ process_scheduled_works(rescuer);
+ spin_unlock_irq(&gcwq->lock);
+ }
+
+ schedule();
+ goto repeat;
+}
+
+struct wq_barrier {
+ struct work_struct work;
+ struct completion done;
+};
+
+static void wq_barrier_func(struct work_struct *work)
+{
+ struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
+ complete(&barr->done);
+}
+
+/**
+ * insert_wq_barrier - insert a barrier work
+ * @cwq: cwq to insert barrier into
+ * @barr: wq_barrier to insert
+ * @target: target work to attach @barr to
+ * @worker: worker currently executing @target, NULL if @target is not executing
+ *
+ * @barr is linked to @target such that @barr is completed only after
+ * @target finishes execution. Please note that the ordering
+ * guarantee is observed only with respect to @target and on the local
+ * cpu.
+ *
+ * Currently, a queued barrier can't be canceled. This is because
+ * try_to_grab_pending() can't determine whether the work to be
+ * grabbed is at the head of the queue and thus can't clear LINKED
+ * flag of the previous work while there must be a valid next work
+ * after a work with LINKED flag set.
+ *
+ * Note that when @worker is non-NULL, @target may be modified
+ * underneath us, so we can't reliably determine cwq from @target.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock).
+ */
+static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
+ struct wq_barrier *barr,
+ struct work_struct *target, struct worker *worker)
+{
+ struct list_head *head;
+ unsigned int linked = 0;
+
+ /*
+ * debugobject calls are safe here even with gcwq->lock locked
+ * as we know for sure that this will not trigger any of the
+ * checks and call back into the fixup functions where we
+ * might deadlock.
+ */
+ INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
+ __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
+ init_completion(&barr->done);
+
+ /*
+ * If @target is currently being executed, schedule the
+ * barrier to the worker; otherwise, put it after @target.
+ */
+ if (worker)
+ head = worker->scheduled.next;
+ else {
+ unsigned long *bits = work_data_bits(target);
+
+ head = target->entry.next;
+ /* there can already be other linked works, inherit and set */
+ linked = *bits & WORK_STRUCT_LINKED;
+ __set_bit(WORK_STRUCT_LINKED_BIT, bits);
+ }
+
+ debug_work_activate(&barr->work);
+ insert_work(cwq, &barr->work, head,
+ work_color_to_flags(WORK_NO_COLOR) | linked);
+}
+
+/**
+ * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
+ * @wq: workqueue being flushed
+ * @flush_color: new flush color, < 0 for no-op
+ * @work_color: new work color, < 0 for no-op
+ *
+ * Prepare cwqs for workqueue flushing.
+ *
+ * If @flush_color is non-negative, flush_color on all cwqs should be
+ * -1. If no cwq has in-flight commands at the specified color, all
+ * cwq->flush_color's stay at -1 and %false is returned. If any cwq
+ * has in flight commands, its cwq->flush_color is set to
+ * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
+ * wakeup logic is armed and %true is returned.
+ *
+ * The caller should have initialized @wq->first_flusher prior to
+ * calling this function with non-negative @flush_color. If
+ * @flush_color is negative, no flush color update is done and %false
+ * is returned.
+ *
+ * If @work_color is non-negative, all cwqs should have the same
+ * work_color which is previous to @work_color and all will be
+ * advanced to @work_color.
+ *
+ * CONTEXT:
+ * mutex_lock(wq->flush_mutex).
+ *
+ * RETURNS:
+ * %true if @flush_color >= 0 and there's something to flush. %false
+ * otherwise.
+ */
+static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
+ int flush_color, int work_color)
+{
+ bool wait = false;
+ unsigned int cpu;
+
+ if (flush_color >= 0) {
+ BUG_ON(atomic_read(&wq->nr_cwqs_to_flush));
+ atomic_set(&wq->nr_cwqs_to_flush, 1);
+ }
+
+ for_each_cwq_cpu(cpu, wq) {
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+ struct global_cwq *gcwq = cwq->gcwq;
+
+ spin_lock_irq(&gcwq->lock);
+
+ if (flush_color >= 0) {
+ BUG_ON(cwq->flush_color != -1);
+
+ if (cwq->nr_in_flight[flush_color]) {
+ cwq->flush_color = flush_color;
+ atomic_inc(&wq->nr_cwqs_to_flush);
+ wait = true;
+ }
+ }
+
+ if (work_color >= 0) {
+ BUG_ON(work_color != work_next_color(cwq->work_color));
+ cwq->work_color = work_color;
+ }
+
+ spin_unlock_irq(&gcwq->lock);
+ }
+
+ if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush))
+ complete(&wq->first_flusher->done);
+
+ return wait;
+}
+
+/**
+ * flush_workqueue - ensure that any scheduled work has run to completion.
+ * @wq: workqueue to flush
+ *
+ * Forces execution of the workqueue and blocks until its completion.
+ * This is typically used in driver shutdown handlers.
+ *
+ * We sleep until all works which were queued on entry have been handled,
+ * but we are not livelocked by new incoming ones.
+ */
+void flush_workqueue(struct workqueue_struct *wq)
+{
+ struct wq_flusher this_flusher = {
+ .list = LIST_HEAD_INIT(this_flusher.list),
+ .flush_color = -1,
+ .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
+ };
+ int next_color;
+
+ lock_map_acquire(&wq->lockdep_map);
+ lock_map_release(&wq->lockdep_map);
+
+ mutex_lock(&wq->flush_mutex);
+
+ /*
+ * Start-to-wait phase
+ */
+ next_color = work_next_color(wq->work_color);
+
+ if (next_color != wq->flush_color) {
+ /*
+ * Color space is not full. The current work_color
+ * becomes our flush_color and work_color is advanced
+ * by one.
+ */
+ BUG_ON(!list_empty(&wq->flusher_overflow));
+ this_flusher.flush_color = wq->work_color;
+ wq->work_color = next_color;
+
+ if (!wq->first_flusher) {
+ /* no flush in progress, become the first flusher */
+ BUG_ON(wq->flush_color != this_flusher.flush_color);
+
+ wq->first_flusher = &this_flusher;
+
+ if (!flush_workqueue_prep_cwqs(wq, wq->flush_color,
+ wq->work_color)) {
+ /* nothing to flush, done */
+ wq->flush_color = next_color;
+ wq->first_flusher = NULL;
+ goto out_unlock;
+ }
+ } else {
+ /* wait in queue */
+ BUG_ON(wq->flush_color == this_flusher.flush_color);
+ list_add_tail(&this_flusher.list, &wq->flusher_queue);
+ flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
+ }
+ } else {
+ /*
+ * Oops, color space is full, wait on overflow queue.
+ * The next flush completion will assign us
+ * flush_color and transfer to flusher_queue.
+ */
+ list_add_tail(&this_flusher.list, &wq->flusher_overflow);
+ }
+
+ mutex_unlock(&wq->flush_mutex);
+
+ wait_for_completion(&this_flusher.done);
+
+ /*
+ * Wake-up-and-cascade phase
+ *
+ * First flushers are responsible for cascading flushes and
+ * handling overflow. Non-first flushers can simply return.
+ */
+ if (wq->first_flusher != &this_flusher)
+ return;
+
+ mutex_lock(&wq->flush_mutex);
+
+ /* we might have raced, check again with mutex held */
+ if (wq->first_flusher != &this_flusher)
+ goto out_unlock;
+
+ wq->first_flusher = NULL;
+
+ BUG_ON(!list_empty(&this_flusher.list));
+ BUG_ON(wq->flush_color != this_flusher.flush_color);
+
+ while (true) {
+ struct wq_flusher *next, *tmp;
+
+ /* complete all the flushers sharing the current flush color */
+ list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
+ if (next->flush_color != wq->flush_color)
+ break;
+ list_del_init(&next->list);
+ complete(&next->done);
+ }
+
+ BUG_ON(!list_empty(&wq->flusher_overflow) &&
+ wq->flush_color != work_next_color(wq->work_color));
+
+ /* this flush_color is finished, advance by one */
+ wq->flush_color = work_next_color(wq->flush_color);
+
+ /* one color has been freed, handle overflow queue */
+ if (!list_empty(&wq->flusher_overflow)) {
+ /*
+ * Assign the same color to all overflowed
+ * flushers, advance work_color and append to
+ * flusher_queue. This is the start-to-wait
+ * phase for these overflowed flushers.
+ */
+ list_for_each_entry(tmp, &wq->flusher_overflow, list)
+ tmp->flush_color = wq->work_color;
+
+ wq->work_color = work_next_color(wq->work_color);
+
+ list_splice_tail_init(&wq->flusher_overflow,
+ &wq->flusher_queue);
+ flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
+ }
+
+ if (list_empty(&wq->flusher_queue)) {
+ BUG_ON(wq->flush_color != wq->work_color);
+ break;
+ }
+
+ /*
+ * Need to flush more colors. Make the next flusher
+ * the new first flusher and arm cwqs.
+ */
+ BUG_ON(wq->flush_color == wq->work_color);
+ BUG_ON(wq->flush_color != next->flush_color);
+
+ list_del_init(&next->list);
+ wq->first_flusher = next;
+
+ if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1))
+ break;
+
+ /*
+ * Meh... this color is already done, clear first
+ * flusher and repeat cascading.
+ */
+ wq->first_flusher = NULL;
+ }
+
+out_unlock:
+ mutex_unlock(&wq->flush_mutex);
+}
+EXPORT_SYMBOL_GPL(flush_workqueue);
+
+static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
+ bool wait_executing)
+{
+ struct worker *worker = NULL;
+ struct global_cwq *gcwq;
+ struct cpu_workqueue_struct *cwq;
+
+ might_sleep();
+ gcwq = get_work_gcwq(work);
+ if (!gcwq)
+ return false;
+
+ spin_lock_irq(&gcwq->lock);
+ if (!list_empty(&work->entry)) {
+ /*
+ * See the comment near try_to_grab_pending()->smp_rmb().
+ * If it was re-queued to a different gcwq under us, we
+ * are not going to wait.
+ */
+ smp_rmb();
+ cwq = get_work_cwq(work);
+ if (unlikely(!cwq || gcwq != cwq->gcwq))
+ goto already_gone;
+ } else if (wait_executing) {
+ worker = find_worker_executing_work(gcwq, work);
+ if (!worker)
+ goto already_gone;
+ cwq = worker->current_cwq;
+ } else
+ goto already_gone;
+
+ insert_wq_barrier(cwq, barr, work, worker);
+ spin_unlock_irq(&gcwq->lock);
+
+ lock_map_acquire(&cwq->wq->lockdep_map);
+ lock_map_release(&cwq->wq->lockdep_map);
+ return true;
+already_gone:
+ spin_unlock_irq(&gcwq->lock);
+ return false;
+}
+
+/**
+ * flush_work - wait for a work to finish executing the last queueing instance
+ * @work: the work to flush
+ *
+ * Wait until @work has finished execution. This function considers
+ * only the last queueing instance of @work. If @work has been
+ * enqueued across different CPUs on a non-reentrant workqueue or on
+ * multiple workqueues, @work might still be executing on return on
+ * some of the CPUs from earlier queueing.
+ *
+ * If @work was queued only on a non-reentrant, ordered or unbound
+ * workqueue, @work is guaranteed to be idle on return if it hasn't
+ * been requeued since flush started.
+ *
+ * RETURNS:
+ * %true if flush_work() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_work(struct work_struct *work)
+{
+ struct wq_barrier barr;
+
+ if (start_flush_work(work, &barr, true)) {
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
+ return true;
+ } else
+ return false;
+}
+EXPORT_SYMBOL_GPL(flush_work);
+
+static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
{
- struct cpu_workqueue_struct *cwq;
- struct list_head *prev;
struct wq_barrier barr;
+ struct worker *worker;
+
+ spin_lock_irq(&gcwq->lock);
+
+ worker = find_worker_executing_work(gcwq, work);
+ if (unlikely(worker))
+ insert_wq_barrier(worker->current_cwq, &barr, work, worker);
+
+ spin_unlock_irq(&gcwq->lock);
+
+ if (unlikely(worker)) {
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
+ return true;
+ } else
+ return false;
+}
+
+static bool wait_on_work(struct work_struct *work)
+{
+ bool ret = false;
+ int cpu;
might_sleep();
- cwq = get_wq_data(work);
- if (!cwq)
- return 0;
- lock_map_acquire(&cwq->wq->lockdep_map);
- lock_map_release(&cwq->wq->lockdep_map);
+ lock_map_acquire(&work->lockdep_map);
+ lock_map_release(&work->lockdep_map);
- prev = NULL;
- spin_lock_irq(&cwq->lock);
- if (!list_empty(&work->entry)) {
- /*
- * See the comment near try_to_grab_pending()->smp_rmb().
- * If it was re-queued under us we are not going to wait.
- */
- smp_rmb();
- if (unlikely(cwq != get_wq_data(work)))
- goto out;
- prev = &work->entry;
- } else {
- if (cwq->current_work != work)
- goto out;
- prev = &cwq->worklist;
+ for_each_gcwq_cpu(cpu)
+ ret |= wait_on_cpu_work(get_gcwq(cpu), work);
+ return ret;
+}
+
+/**
+ * flush_work_sync - wait until a work has finished execution
+ * @work: the work to flush
+ *
+ * Wait until @work has finished execution. On return, it's
+ * guaranteed that all queueing instances of @work which happened
+ * before this function is called are finished. In other words, if
+ * @work hasn't been requeued since this function was called, @work is
+ * guaranteed to be idle on return.
+ *
+ * RETURNS:
+ * %true if flush_work_sync() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_work_sync(struct work_struct *work)
+{
+ struct wq_barrier barr;
+ bool pending, waited;
+
+ /* we'll wait for executions separately, queue barr only if pending */
+ pending = start_flush_work(work, &barr, false);
+
+ /* wait for executions to finish */
+ waited = wait_on_work(work);
+
+ /* wait for the pending one */
+ if (pending) {
+ wait_for_completion(&barr.done);
+ destroy_work_on_stack(&barr.work);
}
- insert_wq_barrier(cwq, &barr, prev->next);
-out:
- spin_unlock_irq(&cwq->lock);
- if (!prev)
- return 0;
- wait_for_completion(&barr.done);
- return 1;
+ return pending || waited;
}
-EXPORT_SYMBOL_GPL(flush_work);
+EXPORT_SYMBOL_GPL(flush_work_sync);
/*
* Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
*/
static int try_to_grab_pending(struct work_struct *work)
{
- struct cpu_workqueue_struct *cwq;
+ struct global_cwq *gcwq;
int ret = -1;
- if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work)))
+ if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
return 0;
/*
* The queueing is in progress, or it is already queued. Try to
* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
*/
-
- cwq = get_wq_data(work);
- if (!cwq)
+ gcwq = get_work_gcwq(work);
+ if (!gcwq)
return ret;
- spin_lock_irq(&cwq->lock);
+ spin_lock_irq(&gcwq->lock);
if (!list_empty(&work->entry)) {
/*
- * This work is queued, but perhaps we locked the wrong cwq.
+ * This work is queued, but perhaps we locked the wrong gcwq.
* In that case we must see the new value after rmb(), see
* insert_work()->wmb().
*/
smp_rmb();
- if (cwq == get_wq_data(work)) {
+ if (gcwq == get_work_gcwq(work)) {
+ debug_work_deactivate(work);
list_del_init(&work->entry);
+ cwq_dec_nr_in_flight(get_work_cwq(work),
+ get_work_color(work),
+ *work_data_bits(work) & WORK_STRUCT_DELAYED);
ret = 1;
}
}
- spin_unlock_irq(&cwq->lock);
+ spin_unlock_irq(&gcwq->lock);
return ret;
}
-static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
- struct work_struct *work)
-{
- struct wq_barrier barr;
- int running = 0;
-
- spin_lock_irq(&cwq->lock);
- if (unlikely(cwq->current_work == work)) {
- insert_wq_barrier(cwq, &barr, cwq->worklist.next);
- running = 1;
- }
- spin_unlock_irq(&cwq->lock);
-
- if (unlikely(running))
- wait_for_completion(&barr.done);
-}
-
-static void wait_on_work(struct work_struct *work)
-{
- struct cpu_workqueue_struct *cwq;
- struct workqueue_struct *wq;
- const struct cpumask *cpu_map;
- int cpu;
-
- might_sleep();
-
- lock_map_acquire(&work->lockdep_map);
- lock_map_release(&work->lockdep_map);
-
- cwq = get_wq_data(work);
- if (!cwq)
- return;
-
- wq = cwq->wq;
- cpu_map = wq_cpu_map(wq);
-
- for_each_cpu_mask_nr(cpu, *cpu_map)
- wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
-}
-
-static int __cancel_work_timer(struct work_struct *work,
+static bool __cancel_work_timer(struct work_struct *work,
struct timer_list* timer)
{
int ret;
wait_on_work(work);
} while (unlikely(ret < 0));
- work_clear_pending(work);
+ clear_work_data(work);
return ret;
}
/**
- * cancel_work_sync - block until a work_struct's callback has terminated
- * @work: the work which is to be flushed
+ * cancel_work_sync - cancel a work and wait for it to finish
+ * @work: the work to cancel
*
- * Returns true if @work was pending.
+ * Cancel @work and wait for its execution to finish. This function
+ * can be used even if the work re-queues itself or migrates to
+ * another workqueue. On return from this function, @work is
+ * guaranteed to be not pending or executing on any CPU.
*
- * cancel_work_sync() will cancel the work if it is queued. If the work's
- * callback appears to be running, cancel_work_sync() will block until it
- * has completed.
+ * cancel_work_sync(&delayed_work->work) must not be used for
+ * delayed_work's. Use cancel_delayed_work_sync() instead.
*
- * It is possible to use this function if the work re-queues itself. It can
- * cancel the work even if it migrates to another workqueue, however in that
- * case it only guarantees that work->func() has completed on the last queued
- * workqueue.
- *
- * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not
- * pending, otherwise it goes into a busy-wait loop until the timer expires.
- *
- * The caller must ensure that workqueue_struct on which this work was last
+ * The caller must ensure that the workqueue on which @work was last
* queued can't be destroyed before this function returns.
+ *
+ * RETURNS:
+ * %true if @work was pending, %false otherwise.
*/
-int cancel_work_sync(struct work_struct *work)
+bool cancel_work_sync(struct work_struct *work)
{
return __cancel_work_timer(work, NULL);
}
EXPORT_SYMBOL_GPL(cancel_work_sync);
/**
- * cancel_delayed_work_sync - reliably kill off a delayed work.
- * @dwork: the delayed work struct
+ * flush_delayed_work - wait for a dwork to finish executing the last queueing
+ * @dwork: the delayed work to flush
+ *
+ * Delayed timer is cancelled and the pending work is queued for
+ * immediate execution. Like flush_work(), this function only
+ * considers the last queueing instance of @dwork.
+ *
+ * RETURNS:
+ * %true if flush_work() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_delayed_work(struct delayed_work *dwork)
+{
+ if (del_timer_sync(&dwork->timer))
+ __queue_work(raw_smp_processor_id(),
+ get_work_cwq(&dwork->work)->wq, &dwork->work);
+ return flush_work(&dwork->work);
+}
+EXPORT_SYMBOL(flush_delayed_work);
+
+/**
+ * flush_delayed_work_sync - wait for a dwork to finish
+ * @dwork: the delayed work to flush
+ *
+ * Delayed timer is cancelled and the pending work is queued for
+ * execution immediately. Other than timer handling, its behavior
+ * is identical to flush_work_sync().
+ *
+ * RETURNS:
+ * %true if flush_work_sync() waited for the work to finish execution,
+ * %false if it was already idle.
+ */
+bool flush_delayed_work_sync(struct delayed_work *dwork)
+{
+ if (del_timer_sync(&dwork->timer))
+ __queue_work(raw_smp_processor_id(),
+ get_work_cwq(&dwork->work)->wq, &dwork->work);
+ return flush_work_sync(&dwork->work);
+}
+EXPORT_SYMBOL(flush_delayed_work_sync);
+
+/**
+ * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
+ * @dwork: the delayed work cancel
*
- * Returns true if @dwork was pending.
+ * This is cancel_work_sync() for delayed works.
*
- * It is possible to use this function if @dwork rearms itself via queue_work()
- * or queue_delayed_work(). See also the comment for cancel_work_sync().
+ * RETURNS:
+ * %true if @dwork was pending, %false otherwise.
*/
-int cancel_delayed_work_sync(struct delayed_work *dwork)
+bool cancel_delayed_work_sync(struct delayed_work *dwork)
{
return __cancel_work_timer(&dwork->work, &dwork->timer);
}
EXPORT_SYMBOL(cancel_delayed_work_sync);
-static struct workqueue_struct *keventd_wq __read_mostly;
-
/**
* schedule_work - put work task in global workqueue
* @work: job to be done
*
- * This puts a job in the kernel-global workqueue.
+ * Returns zero if @work was already on the kernel-global workqueue and
+ * non-zero otherwise.
+ *
+ * This puts a job in the kernel-global workqueue if it was not already
+ * queued and leaves it in the same position on the kernel-global
+ * workqueue otherwise.
*/
int schedule_work(struct work_struct *work)
{
- return queue_work(keventd_wq, work);
+ return queue_work(system_wq, work);
}
EXPORT_SYMBOL(schedule_work);
*/
int schedule_work_on(int cpu, struct work_struct *work)
{
- return queue_work_on(cpu, keventd_wq, work);
+ return queue_work_on(cpu, system_wq, work);
}
EXPORT_SYMBOL(schedule_work_on);
int schedule_delayed_work(struct delayed_work *dwork,
unsigned long delay)
{
- return queue_delayed_work(keventd_wq, dwork, delay);
+ return queue_delayed_work(system_wq, dwork, delay);
}
EXPORT_SYMBOL(schedule_delayed_work);
int schedule_delayed_work_on(int cpu,
struct delayed_work *dwork, unsigned long delay)
{
- return queue_delayed_work_on(cpu, keventd_wq, dwork, delay);
+ return queue_delayed_work_on(cpu, system_wq, dwork, delay);
}
EXPORT_SYMBOL(schedule_delayed_work_on);
/**
- * schedule_on_each_cpu - call a function on each online CPU from keventd
+ * schedule_on_each_cpu - execute a function synchronously on each online CPU
* @func: the function to call
*
- * Returns zero on success.
- * Returns -ve errno on failure.
- *
+ * schedule_on_each_cpu() executes @func on each online CPU using the
+ * system workqueue and blocks until all CPUs have completed.
* schedule_on_each_cpu() is very slow.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
*/
int schedule_on_each_cpu(work_func_t func)
{
int cpu;
- struct work_struct *works;
+ struct work_struct __percpu *works;
+
+ works = alloc_percpu(struct work_struct);
+ if (!works)
+ return -ENOMEM;
+
+ get_online_cpus();
+
+ for_each_online_cpu(cpu) {
+ struct work_struct *work = per_cpu_ptr(works, cpu);
+
+ INIT_WORK(work, func);
+ schedule_work_on(cpu, work);
+ }
+
+ for_each_online_cpu(cpu)
+ flush_work(per_cpu_ptr(works, cpu));
+
+ put_online_cpus();
+ free_percpu(works);
+ return 0;
+}
+
+/**
+ * flush_scheduled_work - ensure that any scheduled work has run to completion.
+ *
+ * Forces execution of the kernel-global workqueue and blocks until its
+ * completion.
+ *
+ * Think twice before calling this function! It's very easy to get into
+ * trouble if you don't take great care. Either of the following situations
+ * will lead to deadlock:
+ *
+ * One of the work items currently on the workqueue needs to acquire
+ * a lock held by your code or its caller.
+ *
+ * Your code is running in the context of a work routine.
+ *
+ * They will be detected by lockdep when they occur, but the first might not
+ * occur very often. It depends on what work items are on the workqueue and
+ * what locks they need, which you have no control over.
+ *
+ * In most situations flushing the entire workqueue is overkill; you merely
+ * need to know that a particular work item isn't queued and isn't running.
+ * In such cases you should use cancel_delayed_work_sync() or
+ * cancel_work_sync() instead.
+ */
+void flush_scheduled_work(void)
+{
+ flush_workqueue(system_wq);
+}
+EXPORT_SYMBOL(flush_scheduled_work);
+
+/**
+ * execute_in_process_context - reliably execute the routine with user context
+ * @fn: the function to execute
+ * @ew: guaranteed storage for the execute work structure (must
+ * be available when the work executes)
+ *
+ * Executes the function immediately if process context is available,
+ * otherwise schedules the function for delayed execution.
+ *
+ * Returns: 0 - function was executed
+ * 1 - function was scheduled for execution
+ */
+int execute_in_process_context(work_func_t fn, struct execute_work *ew)
+{
+ if (!in_interrupt()) {
+ fn(&ew->work);
+ return 0;
+ }
+
+ INIT_WORK(&ew->work, fn);
+ schedule_work(&ew->work);
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(execute_in_process_context);
+
+int keventd_up(void)
+{
+ return system_wq != NULL;
+}
+
+static int alloc_cwqs(struct workqueue_struct *wq)
+{
+ /*
+ * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
+ * Make sure that the alignment isn't lower than that of
+ * unsigned long long.
+ */
+ const size_t size = sizeof(struct cpu_workqueue_struct);
+ const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
+ __alignof__(unsigned long long));
+#ifdef CONFIG_SMP
+ bool percpu = !(wq->flags & WQ_UNBOUND);
+#else
+ bool percpu = false;
+#endif
+
+ if (percpu)
+ wq->cpu_wq.pcpu = __alloc_percpu(size, align);
+ else {
+ void *ptr;
+
+ /*
+ * Allocate enough room to align cwq and put an extra
+ * pointer at the end pointing back to the originally
+ * allocated pointer which will be used for free.
+ */
+ ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
+ if (ptr) {
+ wq->cpu_wq.single = PTR_ALIGN(ptr, align);
+ *(void **)(wq->cpu_wq.single + 1) = ptr;
+ }
+ }
+
+ /* just in case, make sure it's actually aligned
+ * - this is affected by PERCPU() alignment in vmlinux.lds.S
+ */
+ BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
+ return wq->cpu_wq.v ? 0 : -ENOMEM;
+}
+
+static void free_cwqs(struct workqueue_struct *wq)
+{
+#ifdef CONFIG_SMP
+ bool percpu = !(wq->flags & WQ_UNBOUND);
+#else
+ bool percpu = false;
+#endif
+
+ if (percpu)
+ free_percpu(wq->cpu_wq.pcpu);
+ else if (wq->cpu_wq.single) {
+ /* the pointer to free is stored right after the cwq */
+ kfree(*(void **)(wq->cpu_wq.single + 1));
+ }
+}
+
+static int wq_clamp_max_active(int max_active, unsigned int flags,
+ const char *name)
+{
+ int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
+
+ if (max_active < 1 || max_active > lim)
+ printk(KERN_WARNING "workqueue: max_active %d requested for %s "
+ "is out of range, clamping between %d and %d\n",
+ max_active, name, 1, lim);
+
+ return clamp_val(max_active, 1, lim);
+}
+
+struct workqueue_struct *__alloc_workqueue_key(const char *name,
+ unsigned int flags,
+ int max_active,
+ struct lock_class_key *key,
+ const char *lock_name)
+{
+ struct workqueue_struct *wq;
+ unsigned int cpu;
+
+ /*
+ * Workqueues which may be used during memory reclaim should
+ * have a rescuer to guarantee forward progress.
+ */
+ if (flags & WQ_MEM_RECLAIM)
+ flags |= WQ_RESCUER;
+
+ /*
+ * Unbound workqueues aren't concurrency managed and should be
+ * dispatched to workers immediately.
+ */
+ if (flags & WQ_UNBOUND)
+ flags |= WQ_HIGHPRI;
+
+ max_active = max_active ?: WQ_DFL_ACTIVE;
+ max_active = wq_clamp_max_active(max_active, flags, name);
+
+ wq = kzalloc(sizeof(*wq), GFP_KERNEL);
+ if (!wq)
+ goto err;
+
+ wq->flags = flags;
+ wq->saved_max_active = max_active;
+ mutex_init(&wq->flush_mutex);
+ atomic_set(&wq->nr_cwqs_to_flush, 0);
+ INIT_LIST_HEAD(&wq->flusher_queue);
+ INIT_LIST_HEAD(&wq->flusher_overflow);
+
+ wq->name = name;
+ lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
+ INIT_LIST_HEAD(&wq->list);
+
+ if (alloc_cwqs(wq) < 0)
+ goto err;
+
+ for_each_cwq_cpu(cpu, wq) {
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+ struct global_cwq *gcwq = get_gcwq(cpu);
+
+ BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
+ cwq->gcwq = gcwq;
+ cwq->wq = wq;
+ cwq->flush_color = -1;
+ cwq->max_active = max_active;
+ INIT_LIST_HEAD(&cwq->delayed_works);
+ }
+
+ if (flags & WQ_RESCUER) {
+ struct worker *rescuer;
+
+ if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL))
+ goto err;
+
+ wq->rescuer = rescuer = alloc_worker();
+ if (!rescuer)
+ goto err;
+
+ rescuer->task = kthread_create(rescuer_thread, wq, "%s", name);
+ if (IS_ERR(rescuer->task))
+ goto err;
+
+ rescuer->task->flags |= PF_THREAD_BOUND;
+ wake_up_process(rescuer->task);
+ }
+
+ /*
+ * workqueue_lock protects global freeze state and workqueues
+ * list. Grab it, set max_active accordingly and add the new
+ * workqueue to workqueues list.
+ */
+ spin_lock(&workqueue_lock);
+
+ if (workqueue_freezing && wq->flags & WQ_FREEZEABLE)
+ for_each_cwq_cpu(cpu, wq)
+ get_cwq(cpu, wq)->max_active = 0;
+
+ list_add(&wq->list, &workqueues);
+
+ spin_unlock(&workqueue_lock);
+
+ return wq;
+err:
+ if (wq) {
+ free_cwqs(wq);
+ free_mayday_mask(wq->mayday_mask);
+ kfree(wq->rescuer);
+ kfree(wq);
+ }
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
+
+/**
+ * destroy_workqueue - safely terminate a workqueue
+ * @wq: target workqueue
+ *
+ * Safely destroy a workqueue. All work currently pending will be done first.
+ */
+void destroy_workqueue(struct workqueue_struct *wq)
+{
+ unsigned int cpu;
+
+ wq->flags |= WQ_DYING;
+ flush_workqueue(wq);
+
+ /*
+ * wq list is used to freeze wq, remove from list after
+ * flushing is complete in case freeze races us.
+ */
+ spin_lock(&workqueue_lock);
+ list_del(&wq->list);
+ spin_unlock(&workqueue_lock);
+
+ /* sanity check */
+ for_each_cwq_cpu(cpu, wq) {
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+ int i;
+
+ for (i = 0; i < WORK_NR_COLORS; i++)
+ BUG_ON(cwq->nr_in_flight[i]);
+ BUG_ON(cwq->nr_active);
+ BUG_ON(!list_empty(&cwq->delayed_works));
+ }
+
+ if (wq->flags & WQ_RESCUER) {
+ kthread_stop(wq->rescuer->task);
+ free_mayday_mask(wq->mayday_mask);
+ kfree(wq->rescuer);
+ }
+
+ free_cwqs(wq);
+ kfree(wq);
+}
+EXPORT_SYMBOL_GPL(destroy_workqueue);
+
+/**
+ * workqueue_set_max_active - adjust max_active of a workqueue
+ * @wq: target workqueue
+ * @max_active: new max_active value.
+ *
+ * Set max_active of @wq to @max_active.
+ *
+ * CONTEXT:
+ * Don't call from IRQ context.
+ */
+void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
+{
+ unsigned int cpu;
+
+ max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
+
+ spin_lock(&workqueue_lock);
- works = alloc_percpu(struct work_struct);
- if (!works)
- return -ENOMEM;
+ wq->saved_max_active = max_active;
- get_online_cpus();
- for_each_online_cpu(cpu) {
- struct work_struct *work = per_cpu_ptr(works, cpu);
+ for_each_cwq_cpu(cpu, wq) {
+ struct global_cwq *gcwq = get_gcwq(cpu);
- INIT_WORK(work, func);
- schedule_work_on(cpu, work);
+ spin_lock_irq(&gcwq->lock);
+
+ if (!(wq->flags & WQ_FREEZEABLE) ||
+ !(gcwq->flags & GCWQ_FREEZING))
+ get_cwq(gcwq->cpu, wq)->max_active = max_active;
+
+ spin_unlock_irq(&gcwq->lock);
}
- for_each_online_cpu(cpu)
- flush_work(per_cpu_ptr(works, cpu));
- put_online_cpus();
- free_percpu(works);
- return 0;
-}
-void flush_scheduled_work(void)
-{
- flush_workqueue(keventd_wq);
+ spin_unlock(&workqueue_lock);
}
-EXPORT_SYMBOL(flush_scheduled_work);
+EXPORT_SYMBOL_GPL(workqueue_set_max_active);
/**
- * execute_in_process_context - reliably execute the routine with user context
- * @fn: the function to execute
- * @ew: guaranteed storage for the execute work structure (must
- * be available when the work executes)
+ * workqueue_congested - test whether a workqueue is congested
+ * @cpu: CPU in question
+ * @wq: target workqueue
*
- * Executes the function immediately if process context is available,
- * otherwise schedules the function for delayed execution.
+ * Test whether @wq's cpu workqueue for @cpu is congested. There is
+ * no synchronization around this function and the test result is
+ * unreliable and only useful as advisory hints or for debugging.
*
- * Returns: 0 - function was executed
- * 1 - function was scheduled for execution
+ * RETURNS:
+ * %true if congested, %false otherwise.
*/
-int execute_in_process_context(work_func_t fn, struct execute_work *ew)
+bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
{
- if (!in_interrupt()) {
- fn(&ew->work);
- return 0;
- }
-
- INIT_WORK(&ew->work, fn);
- schedule_work(&ew->work);
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
- return 1;
+ return !list_empty(&cwq->delayed_works);
}
-EXPORT_SYMBOL_GPL(execute_in_process_context);
+EXPORT_SYMBOL_GPL(workqueue_congested);
-int keventd_up(void)
+/**
+ * work_cpu - return the last known associated cpu for @work
+ * @work: the work of interest
+ *
+ * RETURNS:
+ * CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
+ */
+unsigned int work_cpu(struct work_struct *work)
{
- return keventd_wq != NULL;
+ struct global_cwq *gcwq = get_work_gcwq(work);
+
+ return gcwq ? gcwq->cpu : WORK_CPU_NONE;
}
+EXPORT_SYMBOL_GPL(work_cpu);
-int current_is_keventd(void)
+/**
+ * work_busy - test whether a work is currently pending or running
+ * @work: the work to be tested
+ *
+ * Test whether @work is currently pending or running. There is no
+ * synchronization around this function and the test result is
+ * unreliable and only useful as advisory hints or for debugging.
+ * Especially for reentrant wqs, the pending state might hide the
+ * running state.
+ *
+ * RETURNS:
+ * OR'd bitmask of WORK_BUSY_* bits.
+ */
+unsigned int work_busy(struct work_struct *work)
{
- struct cpu_workqueue_struct *cwq;
- int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */
- int ret = 0;
+ struct global_cwq *gcwq = get_work_gcwq(work);
+ unsigned long flags;
+ unsigned int ret = 0;
- BUG_ON(!keventd_wq);
+ if (!gcwq)
+ return false;
- cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu);
- if (current == cwq->thread)
- ret = 1;
+ spin_lock_irqsave(&gcwq->lock, flags);
- return ret;
+ if (work_pending(work))
+ ret |= WORK_BUSY_PENDING;
+ if (find_worker_executing_work(gcwq, work))
+ ret |= WORK_BUSY_RUNNING;
+ spin_unlock_irqrestore(&gcwq->lock, flags);
+
+ return ret;
}
+EXPORT_SYMBOL_GPL(work_busy);
-static struct cpu_workqueue_struct *
-init_cpu_workqueue(struct workqueue_struct *wq, int cpu)
-{
- struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
+/*
+ * CPU hotplug.
+ *
+ * There are two challenges in supporting CPU hotplug. Firstly, there
+ * are a lot of assumptions on strong associations among work, cwq and
+ * gcwq which make migrating pending and scheduled works very
+ * difficult to implement without impacting hot paths. Secondly,
+ * gcwqs serve mix of short, long and very long running works making
+ * blocked draining impractical.
+ *
+ * This is solved by allowing a gcwq to be detached from CPU, running
+ * it with unbound (rogue) workers and allowing it to be reattached
+ * later if the cpu comes back online. A separate thread is created
+ * to govern a gcwq in such state and is called the trustee of the
+ * gcwq.
+ *
+ * Trustee states and their descriptions.
+ *
+ * START Command state used on startup. On CPU_DOWN_PREPARE, a
+ * new trustee is started with this state.
+ *
+ * IN_CHARGE Once started, trustee will enter this state after
+ * assuming the manager role and making all existing
+ * workers rogue. DOWN_PREPARE waits for trustee to
+ * enter this state. After reaching IN_CHARGE, trustee
+ * tries to execute the pending worklist until it's empty
+ * and the state is set to BUTCHER, or the state is set
+ * to RELEASE.
+ *
+ * BUTCHER Command state which is set by the cpu callback after
+ * the cpu has went down. Once this state is set trustee
+ * knows that there will be no new works on the worklist
+ * and once the worklist is empty it can proceed to
+ * killing idle workers.
+ *
+ * RELEASE Command state which is set by the cpu callback if the
+ * cpu down has been canceled or it has come online
+ * again. After recognizing this state, trustee stops
+ * trying to drain or butcher and clears ROGUE, rebinds
+ * all remaining workers back to the cpu and releases
+ * manager role.
+ *
+ * DONE Trustee will enter this state after BUTCHER or RELEASE
+ * is complete.
+ *
+ * trustee CPU draining
+ * took over down complete
+ * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
+ * | | ^
+ * | CPU is back online v return workers |
+ * ----------------> RELEASE --------------
+ */
- cwq->wq = wq;
- spin_lock_init(&cwq->lock);
- INIT_LIST_HEAD(&cwq->worklist);
- init_waitqueue_head(&cwq->more_work);
+/**
+ * trustee_wait_event_timeout - timed event wait for trustee
+ * @cond: condition to wait for
+ * @timeout: timeout in jiffies
+ *
+ * wait_event_timeout() for trustee to use. Handles locking and
+ * checks for RELEASE request.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times. To be used by trustee.
+ *
+ * RETURNS:
+ * Positive indicating left time if @cond is satisfied, 0 if timed
+ * out, -1 if canceled.
+ */
+#define trustee_wait_event_timeout(cond, timeout) ({ \
+ long __ret = (timeout); \
+ while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \
+ __ret) { \
+ spin_unlock_irq(&gcwq->lock); \
+ __wait_event_timeout(gcwq->trustee_wait, (cond) || \
+ (gcwq->trustee_state == TRUSTEE_RELEASE), \
+ __ret); \
+ spin_lock_irq(&gcwq->lock); \
+ } \
+ gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \
+})
- return cwq;
-}
+/**
+ * trustee_wait_event - event wait for trustee
+ * @cond: condition to wait for
+ *
+ * wait_event() for trustee to use. Automatically handles locking and
+ * checks for CANCEL request.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times. To be used by trustee.
+ *
+ * RETURNS:
+ * 0 if @cond is satisfied, -1 if canceled.
+ */
+#define trustee_wait_event(cond) ({ \
+ long __ret1; \
+ __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
+ __ret1 < 0 ? -1 : 0; \
+})
-static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
+static int __cpuinit trustee_thread(void *__gcwq)
{
- struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
- struct workqueue_struct *wq = cwq->wq;
- const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d";
- struct task_struct *p;
+ struct global_cwq *gcwq = __gcwq;
+ struct worker *worker;
+ struct work_struct *work;
+ struct hlist_node *pos;
+ long rc;
+ int i;
- p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu);
+ BUG_ON(gcwq->cpu != smp_processor_id());
+
+ spin_lock_irq(&gcwq->lock);
/*
- * Nobody can add the work_struct to this cwq,
- * if (caller is __create_workqueue)
- * nobody should see this wq
- * else // caller is CPU_UP_PREPARE
- * cpu is not on cpu_online_map
- * so we can abort safely.
+ * Claim the manager position and make all workers rogue.
+ * Trustee must be bound to the target cpu and can't be
+ * cancelled.
*/
- if (IS_ERR(p))
- return PTR_ERR(p);
- if (cwq->wq->rt)
- sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m);
- cwq->thread = p;
+ BUG_ON(gcwq->cpu != smp_processor_id());
+ rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS));
+ BUG_ON(rc < 0);
- return 0;
-}
+ gcwq->flags |= GCWQ_MANAGING_WORKERS;
-static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
-{
- struct task_struct *p = cwq->thread;
+ list_for_each_entry(worker, &gcwq->idle_list, entry)
+ worker->flags |= WORKER_ROGUE;
- if (p != NULL) {
- if (cpu >= 0)
- kthread_bind(p, cpu);
- wake_up_process(p);
- }
-}
+ for_each_busy_worker(worker, i, pos, gcwq)
+ worker->flags |= WORKER_ROGUE;
-struct workqueue_struct *__create_workqueue_key(const char *name,
- int singlethread,
- int freezeable,
- int rt,
- struct lock_class_key *key,
- const char *lock_name)
-{
- struct workqueue_struct *wq;
- struct cpu_workqueue_struct *cwq;
- int err = 0, cpu;
+ /*
+ * Call schedule() so that we cross rq->lock and thus can
+ * guarantee sched callbacks see the rogue flag. This is
+ * necessary as scheduler callbacks may be invoked from other
+ * cpus.
+ */
+ spin_unlock_irq(&gcwq->lock);
+ schedule();
+ spin_lock_irq(&gcwq->lock);
- wq = kzalloc(sizeof(*wq), GFP_KERNEL);
- if (!wq)
- return NULL;
+ /*
+ * Sched callbacks are disabled now. Zap nr_running. After
+ * this, nr_running stays zero and need_more_worker() and
+ * keep_working() are always true as long as the worklist is
+ * not empty.
+ */
+ atomic_set(get_gcwq_nr_running(gcwq->cpu), 0);
- wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
- if (!wq->cpu_wq) {
- kfree(wq);
- return NULL;
- }
+ spin_unlock_irq(&gcwq->lock);
+ del_timer_sync(&gcwq->idle_timer);
+ spin_lock_irq(&gcwq->lock);
- wq->name = name;
- lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
- wq->singlethread = singlethread;
- wq->freezeable = freezeable;
- wq->rt = rt;
- INIT_LIST_HEAD(&wq->list);
+ /*
+ * We're now in charge. Notify and proceed to drain. We need
+ * to keep the gcwq running during the whole CPU down
+ * procedure as other cpu hotunplug callbacks may need to
+ * flush currently running tasks.
+ */
+ gcwq->trustee_state = TRUSTEE_IN_CHARGE;
+ wake_up_all(&gcwq->trustee_wait);
- if (singlethread) {
- cwq = init_cpu_workqueue(wq, singlethread_cpu);
- err = create_workqueue_thread(cwq, singlethread_cpu);
- start_workqueue_thread(cwq, -1);
- } else {
- cpu_maps_update_begin();
- /*
- * We must place this wq on list even if the code below fails.
- * cpu_down(cpu) can remove cpu from cpu_populated_map before
- * destroy_workqueue() takes the lock, in that case we leak
- * cwq[cpu]->thread.
- */
- spin_lock(&workqueue_lock);
- list_add(&wq->list, &workqueues);
- spin_unlock(&workqueue_lock);
- /*
- * We must initialize cwqs for each possible cpu even if we
- * are going to call destroy_workqueue() finally. Otherwise
- * cpu_up() can hit the uninitialized cwq once we drop the
- * lock.
- */
- for_each_possible_cpu(cpu) {
- cwq = init_cpu_workqueue(wq, cpu);
- if (err || !cpu_online(cpu))
- continue;
- err = create_workqueue_thread(cwq, cpu);
- start_workqueue_thread(cwq, cpu);
+ /*
+ * The original cpu is in the process of dying and may go away
+ * anytime now. When that happens, we and all workers would
+ * be migrated to other cpus. Try draining any left work. We
+ * want to get it over with ASAP - spam rescuers, wake up as
+ * many idlers as necessary and create new ones till the
+ * worklist is empty. Note that if the gcwq is frozen, there
+ * may be frozen works in freezeable cwqs. Don't declare
+ * completion while frozen.
+ */
+ while (gcwq->nr_workers != gcwq->nr_idle ||
+ gcwq->flags & GCWQ_FREEZING ||
+ gcwq->trustee_state == TRUSTEE_IN_CHARGE) {
+ int nr_works = 0;
+
+ list_for_each_entry(work, &gcwq->worklist, entry) {
+ send_mayday(work);
+ nr_works++;
+ }
+
+ list_for_each_entry(worker, &gcwq->idle_list, entry) {
+ if (!nr_works--)
+ break;
+ wake_up_process(worker->task);
}
- cpu_maps_update_done();
- }
- if (err) {
- destroy_workqueue(wq);
- wq = NULL;
+ if (need_to_create_worker(gcwq)) {
+ spin_unlock_irq(&gcwq->lock);
+ worker = create_worker(gcwq, false);
+ spin_lock_irq(&gcwq->lock);
+ if (worker) {
+ worker->flags |= WORKER_ROGUE;
+ start_worker(worker);
+ }
+ }
+
+ /* give a breather */
+ if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
+ break;
}
- return wq;
-}
-EXPORT_SYMBOL_GPL(__create_workqueue_key);
-static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq)
-{
/*
- * Our caller is either destroy_workqueue() or CPU_POST_DEAD,
- * cpu_add_remove_lock protects cwq->thread.
+ * Either all works have been scheduled and cpu is down, or
+ * cpu down has already been canceled. Wait for and butcher
+ * all workers till we're canceled.
*/
- if (cwq->thread == NULL)
- return;
-
- lock_map_acquire(&cwq->wq->lockdep_map);
- lock_map_release(&cwq->wq->lockdep_map);
+ do {
+ rc = trustee_wait_event(!list_empty(&gcwq->idle_list));
+ while (!list_empty(&gcwq->idle_list))
+ destroy_worker(list_first_entry(&gcwq->idle_list,
+ struct worker, entry));
+ } while (gcwq->nr_workers && rc >= 0);
- flush_cpu_workqueue(cwq);
/*
- * If the caller is CPU_POST_DEAD and cwq->worklist was not empty,
- * a concurrent flush_workqueue() can insert a barrier after us.
- * However, in that case run_workqueue() won't return and check
- * kthread_should_stop() until it flushes all work_struct's.
- * When ->worklist becomes empty it is safe to exit because no
- * more work_structs can be queued on this cwq: flush_workqueue
- * checks list_empty(), and a "normal" queue_work() can't use
- * a dead CPU.
+ * At this point, either draining has completed and no worker
+ * is left, or cpu down has been canceled or the cpu is being
+ * brought back up. There shouldn't be any idle one left.
+ * Tell the remaining busy ones to rebind once it finishes the
+ * currently scheduled works by scheduling the rebind_work.
*/
- kthread_stop(cwq->thread);
- cwq->thread = NULL;
+ WARN_ON(!list_empty(&gcwq->idle_list));
+
+ for_each_busy_worker(worker, i, pos, gcwq) {
+ struct work_struct *rebind_work = &worker->rebind_work;
+
+ /*
+ * Rebind_work may race with future cpu hotplug
+ * operations. Use a separate flag to mark that
+ * rebinding is scheduled.
+ */
+ worker->flags |= WORKER_REBIND;
+ worker->flags &= ~WORKER_ROGUE;
+
+ /* queue rebind_work, wq doesn't matter, use the default one */
+ if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
+ work_data_bits(rebind_work)))
+ continue;
+
+ debug_work_activate(rebind_work);
+ insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
+ worker->scheduled.next,
+ work_color_to_flags(WORK_NO_COLOR));
+ }
+
+ /* relinquish manager role */
+ gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
+
+ /* notify completion */
+ gcwq->trustee = NULL;
+ gcwq->trustee_state = TRUSTEE_DONE;
+ wake_up_all(&gcwq->trustee_wait);
+ spin_unlock_irq(&gcwq->lock);
+ return 0;
}
/**
- * destroy_workqueue - safely terminate a workqueue
- * @wq: target workqueue
+ * wait_trustee_state - wait for trustee to enter the specified state
+ * @gcwq: gcwq the trustee of interest belongs to
+ * @state: target state to wait for
*
- * Safely destroy a workqueue. All work currently pending will be done first.
+ * Wait for the trustee to reach @state. DONE is already matched.
+ *
+ * CONTEXT:
+ * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * multiple times. To be used by cpu_callback.
*/
-void destroy_workqueue(struct workqueue_struct *wq)
+static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
+__releases(&gcwq->lock)
+__acquires(&gcwq->lock)
{
- const struct cpumask *cpu_map = wq_cpu_map(wq);
- int cpu;
-
- cpu_maps_update_begin();
- spin_lock(&workqueue_lock);
- list_del(&wq->list);
- spin_unlock(&workqueue_lock);
-
- for_each_cpu_mask_nr(cpu, *cpu_map)
- cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu));
- cpu_maps_update_done();
-
- free_percpu(wq->cpu_wq);
- kfree(wq);
+ if (!(gcwq->trustee_state == state ||
+ gcwq->trustee_state == TRUSTEE_DONE)) {
+ spin_unlock_irq(&gcwq->lock);
+ __wait_event(gcwq->trustee_wait,
+ gcwq->trustee_state == state ||
+ gcwq->trustee_state == TRUSTEE_DONE);
+ spin_lock_irq(&gcwq->lock);
+ }
}
-EXPORT_SYMBOL_GPL(destroy_workqueue);
static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
- struct cpu_workqueue_struct *cwq;
- struct workqueue_struct *wq;
- int ret = NOTIFY_OK;
+ struct global_cwq *gcwq = get_gcwq(cpu);
+ struct task_struct *new_trustee = NULL;
+ struct worker *uninitialized_var(new_worker);
+ unsigned long flags;
action &= ~CPU_TASKS_FROZEN;
switch (action) {
+ case CPU_DOWN_PREPARE:
+ new_trustee = kthread_create(trustee_thread, gcwq,
+ "workqueue_trustee/%d\n", cpu);
+ if (IS_ERR(new_trustee))
+ return notifier_from_errno(PTR_ERR(new_trustee));
+ kthread_bind(new_trustee, cpu);
+ /* fall through */
case CPU_UP_PREPARE:
- cpumask_set_cpu(cpu, cpu_populated_map);
- }
-undo:
- list_for_each_entry(wq, &workqueues, list) {
- cwq = per_cpu_ptr(wq->cpu_wq, cpu);
-
- switch (action) {
- case CPU_UP_PREPARE:
- if (!create_workqueue_thread(cwq, cpu))
- break;
- printk(KERN_ERR "workqueue [%s] for %i failed\n",
- wq->name, cpu);
- action = CPU_UP_CANCELED;
- ret = NOTIFY_BAD;
- goto undo;
-
- case CPU_ONLINE:
- start_workqueue_thread(cwq, cpu);
- break;
-
- case CPU_UP_CANCELED:
- start_workqueue_thread(cwq, -1);
- case CPU_POST_DEAD:
- cleanup_workqueue_thread(cwq);
- break;
+ BUG_ON(gcwq->first_idle);
+ new_worker = create_worker(gcwq, false);
+ if (!new_worker) {
+ if (new_trustee)
+ kthread_stop(new_trustee);
+ return NOTIFY_BAD;
}
}
+ /* some are called w/ irq disabled, don't disturb irq status */
+ spin_lock_irqsave(&gcwq->lock, flags);
+
switch (action) {
- case CPU_UP_CANCELED:
+ case CPU_DOWN_PREPARE:
+ /* initialize trustee and tell it to acquire the gcwq */
+ BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE);
+ gcwq->trustee = new_trustee;
+ gcwq->trustee_state = TRUSTEE_START;
+ wake_up_process(gcwq->trustee);
+ wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);
+ /* fall through */
+ case CPU_UP_PREPARE:
+ BUG_ON(gcwq->first_idle);
+ gcwq->first_idle = new_worker;
+ break;
+
+ case CPU_DYING:
+ /*
+ * Before this, the trustee and all workers except for
+ * the ones which are still executing works from
+ * before the last CPU down must be on the cpu. After
+ * this, they'll all be diasporas.
+ */
+ gcwq->flags |= GCWQ_DISASSOCIATED;
+ break;
+
case CPU_POST_DEAD:
- cpumask_clear_cpu(cpu, cpu_populated_map);
+ gcwq->trustee_state = TRUSTEE_BUTCHER;
+ /* fall through */
+ case CPU_UP_CANCELED:
+ destroy_worker(gcwq->first_idle);
+ gcwq->first_idle = NULL;
+ break;
+
+ case CPU_DOWN_FAILED:
+ case CPU_ONLINE:
+ gcwq->flags &= ~GCWQ_DISASSOCIATED;
+ if (gcwq->trustee_state != TRUSTEE_DONE) {
+ gcwq->trustee_state = TRUSTEE_RELEASE;
+ wake_up_process(gcwq->trustee);
+ wait_trustee_state(gcwq, TRUSTEE_DONE);
+ }
+
+ /*
+ * Trustee is done and there might be no worker left.
+ * Put the first_idle in and request a real manager to
+ * take a look.
+ */
+ spin_unlock_irq(&gcwq->lock);
+ kthread_bind(gcwq->first_idle->task, cpu);
+ spin_lock_irq(&gcwq->lock);
+ gcwq->flags |= GCWQ_MANAGE_WORKERS;
+ start_worker(gcwq->first_idle);
+ gcwq->first_idle = NULL;
+ break;
}
- return ret;
+ spin_unlock_irqrestore(&gcwq->lock, flags);
+
+ return notifier_from_errno(0);
}
#ifdef CONFIG_SMP
-static struct workqueue_struct *work_on_cpu_wq __read_mostly;
struct work_for_cpu {
- struct work_struct work;
+ struct completion completion;
long (*fn)(void *);
void *arg;
long ret;
};
-static void do_work_for_cpu(struct work_struct *w)
+static int do_work_for_cpu(void *_wfc)
{
- struct work_for_cpu *wfc = container_of(w, struct work_for_cpu, work);
-
+ struct work_for_cpu *wfc = _wfc;
wfc->ret = wfc->fn(wfc->arg);
+ complete(&wfc->completion);
+ return 0;
}
/**
*
* This will return the value @fn returns.
* It is up to the caller to ensure that the cpu doesn't go offline.
+ * The caller must not hold any locks which would prevent @fn from completing.
*/
long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
{
- struct work_for_cpu wfc;
-
- INIT_WORK(&wfc.work, do_work_for_cpu);
- wfc.fn = fn;
- wfc.arg = arg;
- queue_work_on(cpu, work_on_cpu_wq, &wfc.work);
- flush_work(&wfc.work);
-
+ struct task_struct *sub_thread;
+ struct work_for_cpu wfc = {
+ .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
+ .fn = fn,
+ .arg = arg,
+ };
+
+ sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
+ if (IS_ERR(sub_thread))
+ return PTR_ERR(sub_thread);
+ kthread_bind(sub_thread, cpu);
+ wake_up_process(sub_thread);
+ wait_for_completion(&wfc.completion);
return wfc.ret;
}
EXPORT_SYMBOL_GPL(work_on_cpu);
#endif /* CONFIG_SMP */
-void __init init_workqueues(void)
+#ifdef CONFIG_FREEZER
+
+/**
+ * freeze_workqueues_begin - begin freezing workqueues
+ *
+ * Start freezing workqueues. After this function returns, all
+ * freezeable workqueues will queue new works to their frozen_works
+ * list instead of gcwq->worklist.
+ *
+ * CONTEXT:
+ * Grabs and releases workqueue_lock and gcwq->lock's.
+ */
+void freeze_workqueues_begin(void)
{
- alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL);
+ unsigned int cpu;
- cpumask_copy(cpu_populated_map, cpu_online_mask);
- singlethread_cpu = cpumask_first(cpu_possible_mask);
- cpu_singlethread_map = cpumask_of(singlethread_cpu);
- hotcpu_notifier(workqueue_cpu_callback, 0);
- keventd_wq = create_workqueue("events");
- BUG_ON(!keventd_wq);
-#ifdef CONFIG_SMP
- work_on_cpu_wq = create_workqueue("work_on_cpu");
- BUG_ON(!work_on_cpu_wq);
-#endif
+ spin_lock(&workqueue_lock);
+
+ BUG_ON(workqueue_freezing);
+ workqueue_freezing = true;
+
+ for_each_gcwq_cpu(cpu) {
+ struct global_cwq *gcwq = get_gcwq(cpu);
+ struct workqueue_struct *wq;
+
+ spin_lock_irq(&gcwq->lock);
+
+ BUG_ON(gcwq->flags & GCWQ_FREEZING);
+ gcwq->flags |= GCWQ_FREEZING;
+
+ list_for_each_entry(wq, &workqueues, list) {
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+
+ if (cwq && wq->flags & WQ_FREEZEABLE)
+ cwq->max_active = 0;
+ }
+
+ spin_unlock_irq(&gcwq->lock);
+ }
+
+ spin_unlock(&workqueue_lock);
+}
+
+/**
+ * freeze_workqueues_busy - are freezeable workqueues still busy?
+ *
+ * Check whether freezing is complete. This function must be called
+ * between freeze_workqueues_begin() and thaw_workqueues().
+ *
+ * CONTEXT:
+ * Grabs and releases workqueue_lock.
+ *
+ * RETURNS:
+ * %true if some freezeable workqueues are still busy. %false if
+ * freezing is complete.
+ */
+bool freeze_workqueues_busy(void)
+{
+ unsigned int cpu;
+ bool busy = false;
+
+ spin_lock(&workqueue_lock);
+
+ BUG_ON(!workqueue_freezing);
+
+ for_each_gcwq_cpu(cpu) {
+ struct workqueue_struct *wq;
+ /*
+ * nr_active is monotonically decreasing. It's safe
+ * to peek without lock.
+ */
+ list_for_each_entry(wq, &workqueues, list) {
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+
+ if (!cwq || !(wq->flags & WQ_FREEZEABLE))
+ continue;
+
+ BUG_ON(cwq->nr_active < 0);
+ if (cwq->nr_active) {
+ busy = true;
+ goto out_unlock;
+ }
+ }
+ }
+out_unlock:
+ spin_unlock(&workqueue_lock);
+ return busy;
+}
+
+/**
+ * thaw_workqueues - thaw workqueues
+ *
+ * Thaw workqueues. Normal queueing is restored and all collected
+ * frozen works are transferred to their respective gcwq worklists.
+ *
+ * CONTEXT:
+ * Grabs and releases workqueue_lock and gcwq->lock's.
+ */
+void thaw_workqueues(void)
+{
+ unsigned int cpu;
+
+ spin_lock(&workqueue_lock);
+
+ if (!workqueue_freezing)
+ goto out_unlock;
+
+ for_each_gcwq_cpu(cpu) {
+ struct global_cwq *gcwq = get_gcwq(cpu);
+ struct workqueue_struct *wq;
+
+ spin_lock_irq(&gcwq->lock);
+
+ BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
+ gcwq->flags &= ~GCWQ_FREEZING;
+
+ list_for_each_entry(wq, &workqueues, list) {
+ struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+
+ if (!cwq || !(wq->flags & WQ_FREEZEABLE))
+ continue;
+
+ /* restore max_active and repopulate worklist */
+ cwq->max_active = wq->saved_max_active;
+
+ while (!list_empty(&cwq->delayed_works) &&
+ cwq->nr_active < cwq->max_active)
+ cwq_activate_first_delayed(cwq);
+ }
+
+ wake_up_worker(gcwq);
+
+ spin_unlock_irq(&gcwq->lock);
+ }
+
+ workqueue_freezing = false;
+out_unlock:
+ spin_unlock(&workqueue_lock);
+}
+#endif /* CONFIG_FREEZER */
+
+static int __init init_workqueues(void)
+{
+ unsigned int cpu;
+ int i;
+
+ cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
+
+ /* initialize gcwqs */
+ for_each_gcwq_cpu(cpu) {
+ struct global_cwq *gcwq = get_gcwq(cpu);
+
+ spin_lock_init(&gcwq->lock);
+ INIT_LIST_HEAD(&gcwq->worklist);
+ gcwq->cpu = cpu;
+ gcwq->flags |= GCWQ_DISASSOCIATED;
+
+ INIT_LIST_HEAD(&gcwq->idle_list);
+ for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
+ INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
+
+ init_timer_deferrable(&gcwq->idle_timer);
+ gcwq->idle_timer.function = idle_worker_timeout;
+ gcwq->idle_timer.data = (unsigned long)gcwq;
+
+ setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout,
+ (unsigned long)gcwq);
+
+ ida_init(&gcwq->worker_ida);
+
+ gcwq->trustee_state = TRUSTEE_DONE;
+ init_waitqueue_head(&gcwq->trustee_wait);
+ }
+
+ /* create the initial worker */
+ for_each_online_gcwq_cpu(cpu) {
+ struct global_cwq *gcwq = get_gcwq(cpu);
+ struct worker *worker;
+
+ if (cpu != WORK_CPU_UNBOUND)
+ gcwq->flags &= ~GCWQ_DISASSOCIATED;
+ worker = create_worker(gcwq, true);
+ BUG_ON(!worker);
+ spin_lock_irq(&gcwq->lock);
+ start_worker(worker);
+ spin_unlock_irq(&gcwq->lock);
+ }
+
+ system_wq = alloc_workqueue("events", 0, 0);
+ system_long_wq = alloc_workqueue("events_long", 0, 0);
+ system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
+ system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
+ WQ_UNBOUND_MAX_ACTIVE);
+ BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);
+ return 0;
}
+early_initcall(init_workqueues);
Code Review / linux-2.6.git / blobdiff