2 * linux/kernel/workqueue.c
4 * Generic mechanism for defining kernel helper threads for running
5 * arbitrary tasks in process context.
7 * Started by Ingo Molnar, Copyright (C) 2002
9 * Derived from the taskqueue/keventd code by:
11 * David Woodhouse <dwmw2@infradead.org>
13 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
14 * Theodore Ts'o <tytso@mit.edu>
16 * Made to use alloc_percpu by Christoph Lameter.
19 #include <linux/module.h>
20 #include <linux/kernel.h>
21 #include <linux/sched.h>
22 #include <linux/init.h>
23 #include <linux/signal.h>
24 #include <linux/completion.h>
25 #include <linux/workqueue.h>
26 #include <linux/slab.h>
27 #include <linux/cpu.h>
28 #include <linux/notifier.h>
29 #include <linux/kthread.h>
30 #include <linux/hardirq.h>
31 #include <linux/mempolicy.h>
32 #include <linux/freezer.h>
33 #include <linux/kallsyms.h>
34 #include <linux/debug_locks.h>
35 #include <linux/lockdep.h>
36 #include <linux/idr.h>
38 #include "workqueue_sched.h"
41 /* global_cwq flags */
42 GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
43 GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */
44 GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
45 GCWQ_FREEZING = 1 << 3, /* freeze in progress */
46 GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */
49 WORKER_STARTED = 1 << 0, /* started */
50 WORKER_DIE = 1 << 1, /* die die die */
51 WORKER_IDLE = 1 << 2, /* is idle */
52 WORKER_PREP = 1 << 3, /* preparing to run works */
53 WORKER_ROGUE = 1 << 4, /* not bound to any cpu */
54 WORKER_REBIND = 1 << 5, /* mom is home, come back */
55 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
57 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND |
60 /* gcwq->trustee_state */
61 TRUSTEE_START = 0, /* start */
62 TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */
63 TRUSTEE_BUTCHER = 2, /* butcher workers */
64 TRUSTEE_RELEASE = 3, /* release workers */
65 TRUSTEE_DONE = 4, /* trustee is done */
67 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
68 BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER,
69 BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1,
71 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
72 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
74 MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */
75 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
76 CREATE_COOLDOWN = HZ, /* time to breath after fail */
77 TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */
80 * Rescue workers are used only on emergencies and shared by
83 RESCUER_NICE_LEVEL = -20,
87 * Structure fields follow one of the following exclusion rules.
89 * I: Set during initialization and read-only afterwards.
91 * P: Preemption protected. Disabling preemption is enough and should
92 * only be modified and accessed from the local cpu.
94 * L: gcwq->lock protected. Access with gcwq->lock held.
96 * X: During normal operation, modification requires gcwq->lock and
97 * should be done only from local cpu. Either disabling preemption
98 * on local cpu or grabbing gcwq->lock is enough for read access.
99 * While trustee is in charge, it's identical to L.
101 * F: wq->flush_mutex protected.
103 * W: workqueue_lock protected.
109 * The poor guys doing the actual heavy lifting. All on-duty workers
110 * are either serving the manager role, on idle list or on busy hash.
113 /* on idle list while idle, on busy hash table while busy */
115 struct list_head entry; /* L: while idle */
116 struct hlist_node hentry; /* L: while busy */
119 struct work_struct *current_work; /* L: work being processed */
120 struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
121 struct list_head scheduled; /* L: scheduled works */
122 struct task_struct *task; /* I: worker task */
123 struct global_cwq *gcwq; /* I: the associated gcwq */
124 /* 64 bytes boundary on 64bit, 32 on 32bit */
125 unsigned long last_active; /* L: last active timestamp */
126 unsigned int flags; /* X: flags */
127 int id; /* I: worker id */
128 struct work_struct rebind_work; /* L: rebind worker to cpu */
132 * Global per-cpu workqueue. There's one and only one for each cpu
133 * and all works are queued and processed here regardless of their
137 spinlock_t lock; /* the gcwq lock */
138 struct list_head worklist; /* L: list of pending works */
139 unsigned int cpu; /* I: the associated cpu */
140 unsigned int flags; /* L: GCWQ_* flags */
142 int nr_workers; /* L: total number of workers */
143 int nr_idle; /* L: currently idle ones */
145 /* workers are chained either in the idle_list or busy_hash */
146 struct list_head idle_list; /* X: list of idle workers */
147 struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE];
148 /* L: hash of busy workers */
150 struct timer_list idle_timer; /* L: worker idle timeout */
151 struct timer_list mayday_timer; /* L: SOS timer for dworkers */
153 struct ida worker_ida; /* L: for worker IDs */
155 struct task_struct *trustee; /* L: for gcwq shutdown */
156 unsigned int trustee_state; /* L: trustee state */
157 wait_queue_head_t trustee_wait; /* trustee wait */
158 struct worker *first_idle; /* L: first idle worker */
159 } ____cacheline_aligned_in_smp;
162 * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
163 * work_struct->data are used for flags and thus cwqs need to be
164 * aligned at two's power of the number of flag bits.
166 struct cpu_workqueue_struct {
167 struct global_cwq *gcwq; /* I: the associated gcwq */
168 struct workqueue_struct *wq; /* I: the owning workqueue */
169 int work_color; /* L: current color */
170 int flush_color; /* L: flushing color */
171 int nr_in_flight[WORK_NR_COLORS];
172 /* L: nr of in_flight works */
173 int nr_active; /* L: nr of active works */
174 int max_active; /* L: max active works */
175 struct list_head delayed_works; /* L: delayed works */
179 * Structure used to wait for workqueue flush.
182 struct list_head list; /* F: list of flushers */
183 int flush_color; /* F: flush color waiting for */
184 struct completion done; /* flush completion */
188 * The externally visible workqueue abstraction is an array of
189 * per-CPU workqueues:
191 struct workqueue_struct {
192 unsigned int flags; /* I: WQ_* flags */
193 struct cpu_workqueue_struct *cpu_wq; /* I: cwq's */
194 struct list_head list; /* W: list of all workqueues */
196 struct mutex flush_mutex; /* protects wq flushing */
197 int work_color; /* F: current work color */
198 int flush_color; /* F: current flush color */
199 atomic_t nr_cwqs_to_flush; /* flush in progress */
200 struct wq_flusher *first_flusher; /* F: first flusher */
201 struct list_head flusher_queue; /* F: flush waiters */
202 struct list_head flusher_overflow; /* F: flush overflow list */
204 unsigned long single_cpu; /* cpu for single cpu wq */
206 cpumask_var_t mayday_mask; /* cpus requesting rescue */
207 struct worker *rescuer; /* I: rescue worker */
209 int saved_max_active; /* W: saved cwq max_active */
210 const char *name; /* I: workqueue name */
211 #ifdef CONFIG_LOCKDEP
212 struct lockdep_map lockdep_map;
216 struct workqueue_struct *system_wq __read_mostly;
217 struct workqueue_struct *system_long_wq __read_mostly;
218 struct workqueue_struct *system_nrt_wq __read_mostly;
219 EXPORT_SYMBOL_GPL(system_wq);
220 EXPORT_SYMBOL_GPL(system_long_wq);
221 EXPORT_SYMBOL_GPL(system_nrt_wq);
223 #define for_each_busy_worker(worker, i, pos, gcwq) \
224 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
225 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
227 #ifdef CONFIG_DEBUG_OBJECTS_WORK
229 static struct debug_obj_descr work_debug_descr;
232 * fixup_init is called when:
233 * - an active object is initialized
235 static int work_fixup_init(void *addr, enum debug_obj_state state)
237 struct work_struct *work = addr;
240 case ODEBUG_STATE_ACTIVE:
241 cancel_work_sync(work);
242 debug_object_init(work, &work_debug_descr);
250 * fixup_activate is called when:
251 * - an active object is activated
252 * - an unknown object is activated (might be a statically initialized object)
254 static int work_fixup_activate(void *addr, enum debug_obj_state state)
256 struct work_struct *work = addr;
260 case ODEBUG_STATE_NOTAVAILABLE:
262 * This is not really a fixup. The work struct was
263 * statically initialized. We just make sure that it
264 * is tracked in the object tracker.
266 if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
267 debug_object_init(work, &work_debug_descr);
268 debug_object_activate(work, &work_debug_descr);
274 case ODEBUG_STATE_ACTIVE:
283 * fixup_free is called when:
284 * - an active object is freed
286 static int work_fixup_free(void *addr, enum debug_obj_state state)
288 struct work_struct *work = addr;
291 case ODEBUG_STATE_ACTIVE:
292 cancel_work_sync(work);
293 debug_object_free(work, &work_debug_descr);
300 static struct debug_obj_descr work_debug_descr = {
301 .name = "work_struct",
302 .fixup_init = work_fixup_init,
303 .fixup_activate = work_fixup_activate,
304 .fixup_free = work_fixup_free,
307 static inline void debug_work_activate(struct work_struct *work)
309 debug_object_activate(work, &work_debug_descr);
312 static inline void debug_work_deactivate(struct work_struct *work)
314 debug_object_deactivate(work, &work_debug_descr);
317 void __init_work(struct work_struct *work, int onstack)
320 debug_object_init_on_stack(work, &work_debug_descr);
322 debug_object_init(work, &work_debug_descr);
324 EXPORT_SYMBOL_GPL(__init_work);
326 void destroy_work_on_stack(struct work_struct *work)
328 debug_object_free(work, &work_debug_descr);
330 EXPORT_SYMBOL_GPL(destroy_work_on_stack);
333 static inline void debug_work_activate(struct work_struct *work) { }
334 static inline void debug_work_deactivate(struct work_struct *work) { }
337 /* Serializes the accesses to the list of workqueues. */
338 static DEFINE_SPINLOCK(workqueue_lock);
339 static LIST_HEAD(workqueues);
340 static bool workqueue_freezing; /* W: have wqs started freezing? */
343 * The almighty global cpu workqueues. nr_running is the only field
344 * which is expected to be used frequently by other cpus via
345 * try_to_wake_up(). Put it in a separate cacheline.
347 static DEFINE_PER_CPU(struct global_cwq, global_cwq);
348 static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);
350 static int worker_thread(void *__worker);
352 static struct global_cwq *get_gcwq(unsigned int cpu)
354 return &per_cpu(global_cwq, cpu);
357 static atomic_t *get_gcwq_nr_running(unsigned int cpu)
359 return &per_cpu(gcwq_nr_running, cpu);
362 static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
363 struct workqueue_struct *wq)
365 return per_cpu_ptr(wq->cpu_wq, cpu);
368 static unsigned int work_color_to_flags(int color)
370 return color << WORK_STRUCT_COLOR_SHIFT;
373 static int get_work_color(struct work_struct *work)
375 return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
376 ((1 << WORK_STRUCT_COLOR_BITS) - 1);
379 static int work_next_color(int color)
381 return (color + 1) % WORK_NR_COLORS;
385 * Work data points to the cwq while a work is on queue. Once
386 * execution starts, it points to the cpu the work was last on. This
387 * can be distinguished by comparing the data value against
390 * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
391 * cwq, cpu or clear work->data. These functions should only be
392 * called while the work is owned - ie. while the PENDING bit is set.
394 * get_work_[g]cwq() can be used to obtain the gcwq or cwq
395 * corresponding to a work. gcwq is available once the work has been
396 * queued anywhere after initialization. cwq is available only from
397 * queueing until execution starts.
399 static inline void set_work_data(struct work_struct *work, unsigned long data,
402 BUG_ON(!work_pending(work));
403 atomic_long_set(&work->data, data | flags | work_static(work));
406 static void set_work_cwq(struct work_struct *work,
407 struct cpu_workqueue_struct *cwq,
408 unsigned long extra_flags)
410 set_work_data(work, (unsigned long)cwq,
411 WORK_STRUCT_PENDING | extra_flags);
414 static void set_work_cpu(struct work_struct *work, unsigned int cpu)
416 set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING);
419 static void clear_work_data(struct work_struct *work)
421 set_work_data(work, WORK_STRUCT_NO_CPU, 0);
424 static inline unsigned long get_work_data(struct work_struct *work)
426 return atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK;
429 static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
431 unsigned long data = get_work_data(work);
433 return data >= PAGE_OFFSET ? (void *)data : NULL;
436 static struct global_cwq *get_work_gcwq(struct work_struct *work)
438 unsigned long data = get_work_data(work);
441 if (data >= PAGE_OFFSET)
442 return ((struct cpu_workqueue_struct *)data)->gcwq;
444 cpu = data >> WORK_STRUCT_FLAG_BITS;
448 BUG_ON(cpu >= nr_cpu_ids);
449 return get_gcwq(cpu);
453 * Policy functions. These define the policies on how the global
454 * worker pool is managed. Unless noted otherwise, these functions
455 * assume that they're being called with gcwq->lock held.
458 static bool __need_more_worker(struct global_cwq *gcwq)
460 return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) ||
461 gcwq->flags & GCWQ_HIGHPRI_PENDING;
465 * Need to wake up a worker? Called from anything but currently
468 static bool need_more_worker(struct global_cwq *gcwq)
470 return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq);
473 /* Can I start working? Called from busy but !running workers. */
474 static bool may_start_working(struct global_cwq *gcwq)
476 return gcwq->nr_idle;
479 /* Do I need to keep working? Called from currently running workers. */
480 static bool keep_working(struct global_cwq *gcwq)
482 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
484 return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1;
487 /* Do we need a new worker? Called from manager. */
488 static bool need_to_create_worker(struct global_cwq *gcwq)
490 return need_more_worker(gcwq) && !may_start_working(gcwq);
493 /* Do I need to be the manager? */
494 static bool need_to_manage_workers(struct global_cwq *gcwq)
496 return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS;
499 /* Do we have too many workers and should some go away? */
500 static bool too_many_workers(struct global_cwq *gcwq)
502 bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS;
503 int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */
504 int nr_busy = gcwq->nr_workers - nr_idle;
506 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
513 /* Return the first worker. Safe with preemption disabled */
514 static struct worker *first_worker(struct global_cwq *gcwq)
516 if (unlikely(list_empty(&gcwq->idle_list)))
519 return list_first_entry(&gcwq->idle_list, struct worker, entry);
523 * wake_up_worker - wake up an idle worker
524 * @gcwq: gcwq to wake worker for
526 * Wake up the first idle worker of @gcwq.
529 * spin_lock_irq(gcwq->lock).
531 static void wake_up_worker(struct global_cwq *gcwq)
533 struct worker *worker = first_worker(gcwq);
536 wake_up_process(worker->task);
540 * wq_worker_waking_up - a worker is waking up
541 * @task: task waking up
542 * @cpu: CPU @task is waking up to
544 * This function is called during try_to_wake_up() when a worker is
548 * spin_lock_irq(rq->lock)
550 void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
552 struct worker *worker = kthread_data(task);
554 if (likely(!(worker->flags & WORKER_NOT_RUNNING)))
555 atomic_inc(get_gcwq_nr_running(cpu));
559 * wq_worker_sleeping - a worker is going to sleep
560 * @task: task going to sleep
561 * @cpu: CPU in question, must be the current CPU number
563 * This function is called during schedule() when a busy worker is
564 * going to sleep. Worker on the same cpu can be woken up by
565 * returning pointer to its task.
568 * spin_lock_irq(rq->lock)
571 * Worker task on @cpu to wake up, %NULL if none.
573 struct task_struct *wq_worker_sleeping(struct task_struct *task,
576 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
577 struct global_cwq *gcwq = get_gcwq(cpu);
578 atomic_t *nr_running = get_gcwq_nr_running(cpu);
580 if (unlikely(worker->flags & WORKER_NOT_RUNNING))
583 /* this can only happen on the local cpu */
584 BUG_ON(cpu != raw_smp_processor_id());
587 * The counterpart of the following dec_and_test, implied mb,
588 * worklist not empty test sequence is in insert_work().
589 * Please read comment there.
591 * NOT_RUNNING is clear. This means that trustee is not in
592 * charge and we're running on the local cpu w/ rq lock held
593 * and preemption disabled, which in turn means that none else
594 * could be manipulating idle_list, so dereferencing idle_list
595 * without gcwq lock is safe.
597 if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist))
598 to_wakeup = first_worker(gcwq);
599 return to_wakeup ? to_wakeup->task : NULL;
603 * worker_set_flags - set worker flags and adjust nr_running accordingly
605 * @flags: flags to set
606 * @wakeup: wakeup an idle worker if necessary
608 * Set @flags in @worker->flags and adjust nr_running accordingly. If
609 * nr_running becomes zero and @wakeup is %true, an idle worker is
613 * spin_lock_irq(gcwq->lock)
615 static inline void worker_set_flags(struct worker *worker, unsigned int flags,
618 struct global_cwq *gcwq = worker->gcwq;
620 WARN_ON_ONCE(worker->task != current);
623 * If transitioning into NOT_RUNNING, adjust nr_running and
624 * wake up an idle worker as necessary if requested by
627 if ((flags & WORKER_NOT_RUNNING) &&
628 !(worker->flags & WORKER_NOT_RUNNING)) {
629 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
632 if (atomic_dec_and_test(nr_running) &&
633 !list_empty(&gcwq->worklist))
634 wake_up_worker(gcwq);
636 atomic_dec(nr_running);
639 worker->flags |= flags;
643 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
645 * @flags: flags to clear
647 * Clear @flags in @worker->flags and adjust nr_running accordingly.
650 * spin_lock_irq(gcwq->lock)
652 static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
654 struct global_cwq *gcwq = worker->gcwq;
655 unsigned int oflags = worker->flags;
657 WARN_ON_ONCE(worker->task != current);
659 worker->flags &= ~flags;
661 /* if transitioning out of NOT_RUNNING, increment nr_running */
662 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
663 if (!(worker->flags & WORKER_NOT_RUNNING))
664 atomic_inc(get_gcwq_nr_running(gcwq->cpu));
668 * busy_worker_head - return the busy hash head for a work
669 * @gcwq: gcwq of interest
670 * @work: work to be hashed
672 * Return hash head of @gcwq for @work.
675 * spin_lock_irq(gcwq->lock).
678 * Pointer to the hash head.
680 static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
681 struct work_struct *work)
683 const int base_shift = ilog2(sizeof(struct work_struct));
684 unsigned long v = (unsigned long)work;
686 /* simple shift and fold hash, do we need something better? */
688 v += v >> BUSY_WORKER_HASH_ORDER;
689 v &= BUSY_WORKER_HASH_MASK;
691 return &gcwq->busy_hash[v];
695 * __find_worker_executing_work - find worker which is executing a work
696 * @gcwq: gcwq of interest
697 * @bwh: hash head as returned by busy_worker_head()
698 * @work: work to find worker for
700 * Find a worker which is executing @work on @gcwq. @bwh should be
701 * the hash head obtained by calling busy_worker_head() with the same
705 * spin_lock_irq(gcwq->lock).
708 * Pointer to worker which is executing @work if found, NULL
711 static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,
712 struct hlist_head *bwh,
713 struct work_struct *work)
715 struct worker *worker;
716 struct hlist_node *tmp;
718 hlist_for_each_entry(worker, tmp, bwh, hentry)
719 if (worker->current_work == work)
725 * find_worker_executing_work - find worker which is executing a work
726 * @gcwq: gcwq of interest
727 * @work: work to find worker for
729 * Find a worker which is executing @work on @gcwq. This function is
730 * identical to __find_worker_executing_work() except that this
731 * function calculates @bwh itself.
734 * spin_lock_irq(gcwq->lock).
737 * Pointer to worker which is executing @work if found, NULL
740 static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
741 struct work_struct *work)
743 return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),
748 * gcwq_determine_ins_pos - find insertion position
749 * @gcwq: gcwq of interest
750 * @cwq: cwq a work is being queued for
752 * A work for @cwq is about to be queued on @gcwq, determine insertion
753 * position for the work. If @cwq is for HIGHPRI wq, the work is
754 * queued at the head of the queue but in FIFO order with respect to
755 * other HIGHPRI works; otherwise, at the end of the queue. This
756 * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that
757 * there are HIGHPRI works pending.
760 * spin_lock_irq(gcwq->lock).
763 * Pointer to inserstion position.
765 static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq,
766 struct cpu_workqueue_struct *cwq)
768 struct work_struct *twork;
770 if (likely(!(cwq->wq->flags & WQ_HIGHPRI)))
771 return &gcwq->worklist;
773 list_for_each_entry(twork, &gcwq->worklist, entry) {
774 struct cpu_workqueue_struct *tcwq = get_work_cwq(twork);
776 if (!(tcwq->wq->flags & WQ_HIGHPRI))
780 gcwq->flags |= GCWQ_HIGHPRI_PENDING;
781 return &twork->entry;
785 * insert_work - insert a work into gcwq
786 * @cwq: cwq @work belongs to
787 * @work: work to insert
788 * @head: insertion point
789 * @extra_flags: extra WORK_STRUCT_* flags to set
791 * Insert @work which belongs to @cwq into @gcwq after @head.
792 * @extra_flags is or'd to work_struct flags.
795 * spin_lock_irq(gcwq->lock).
797 static void insert_work(struct cpu_workqueue_struct *cwq,
798 struct work_struct *work, struct list_head *head,
799 unsigned int extra_flags)
801 struct global_cwq *gcwq = cwq->gcwq;
803 /* we own @work, set data and link */
804 set_work_cwq(work, cwq, extra_flags);
807 * Ensure that we get the right work->data if we see the
808 * result of list_add() below, see try_to_grab_pending().
812 list_add_tail(&work->entry, head);
815 * Ensure either worker_sched_deactivated() sees the above
816 * list_add_tail() or we see zero nr_running to avoid workers
817 * lying around lazily while there are works to be processed.
821 if (__need_more_worker(gcwq))
822 wake_up_worker(gcwq);
826 * cwq_unbind_single_cpu - unbind cwq from single cpu workqueue processing
827 * @cwq: cwq to unbind
829 * Try to unbind @cwq from single cpu workqueue processing. If
830 * @cwq->wq is frozen, unbind is delayed till the workqueue is thawed.
833 * spin_lock_irq(gcwq->lock).
835 static void cwq_unbind_single_cpu(struct cpu_workqueue_struct *cwq)
837 struct workqueue_struct *wq = cwq->wq;
838 struct global_cwq *gcwq = cwq->gcwq;
840 BUG_ON(wq->single_cpu != gcwq->cpu);
842 * Unbind from workqueue if @cwq is not frozen. If frozen,
843 * thaw_workqueues() will either restart processing on this
844 * cpu or unbind if empty. This keeps works queued while
845 * frozen fully ordered and flushable.
847 if (likely(!(gcwq->flags & GCWQ_FREEZING))) {
848 smp_wmb(); /* paired with cmpxchg() in __queue_work() */
849 wq->single_cpu = NR_CPUS;
853 static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
854 struct work_struct *work)
856 struct global_cwq *gcwq;
857 struct cpu_workqueue_struct *cwq;
858 struct list_head *worklist;
862 debug_work_activate(work);
865 * Determine gcwq to use. SINGLE_CPU is inherently
866 * NON_REENTRANT, so test it first.
868 if (!(wq->flags & WQ_SINGLE_CPU)) {
869 struct global_cwq *last_gcwq;
872 * It's multi cpu. If @wq is non-reentrant and @work
873 * was previously on a different cpu, it might still
874 * be running there, in which case the work needs to
875 * be queued on that cpu to guarantee non-reentrance.
877 gcwq = get_gcwq(cpu);
878 if (wq->flags & WQ_NON_REENTRANT &&
879 (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) {
880 struct worker *worker;
882 spin_lock_irqsave(&last_gcwq->lock, flags);
884 worker = find_worker_executing_work(last_gcwq, work);
886 if (worker && worker->current_cwq->wq == wq)
889 /* meh... not running there, queue here */
890 spin_unlock_irqrestore(&last_gcwq->lock, flags);
891 spin_lock_irqsave(&gcwq->lock, flags);
894 spin_lock_irqsave(&gcwq->lock, flags);
896 unsigned int req_cpu = cpu;
899 * It's a bit more complex for single cpu workqueues.
900 * We first need to determine which cpu is going to be
901 * used. If no cpu is currently serving this
902 * workqueue, arbitrate using atomic accesses to
903 * wq->single_cpu; otherwise, use the current one.
906 cpu = wq->single_cpu;
907 arbitrate = cpu == NR_CPUS;
911 gcwq = get_gcwq(cpu);
912 spin_lock_irqsave(&gcwq->lock, flags);
915 * The following cmpxchg() is a full barrier paired
916 * with smp_wmb() in cwq_unbind_single_cpu() and
917 * guarantees that all changes to wq->st_* fields are
918 * visible on the new cpu after this point.
921 cmpxchg(&wq->single_cpu, NR_CPUS, cpu);
923 if (unlikely(wq->single_cpu != cpu)) {
924 spin_unlock_irqrestore(&gcwq->lock, flags);
929 /* gcwq determined, get cwq and queue */
930 cwq = get_cwq(gcwq->cpu, wq);
932 BUG_ON(!list_empty(&work->entry));
934 cwq->nr_in_flight[cwq->work_color]++;
936 if (likely(cwq->nr_active < cwq->max_active)) {
938 worklist = gcwq_determine_ins_pos(gcwq, cwq);
940 worklist = &cwq->delayed_works;
942 insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color));
944 spin_unlock_irqrestore(&gcwq->lock, flags);
948 * queue_work - queue work on a workqueue
949 * @wq: workqueue to use
950 * @work: work to queue
952 * Returns 0 if @work was already on a queue, non-zero otherwise.
954 * We queue the work to the CPU on which it was submitted, but if the CPU dies
955 * it can be processed by another CPU.
957 int queue_work(struct workqueue_struct *wq, struct work_struct *work)
961 ret = queue_work_on(get_cpu(), wq, work);
966 EXPORT_SYMBOL_GPL(queue_work);
969 * queue_work_on - queue work on specific cpu
970 * @cpu: CPU number to execute work on
971 * @wq: workqueue to use
972 * @work: work to queue
974 * Returns 0 if @work was already on a queue, non-zero otherwise.
976 * We queue the work to a specific CPU, the caller must ensure it
980 queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
984 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
985 __queue_work(cpu, wq, work);
990 EXPORT_SYMBOL_GPL(queue_work_on);
992 static void delayed_work_timer_fn(unsigned long __data)
994 struct delayed_work *dwork = (struct delayed_work *)__data;
995 struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
997 __queue_work(smp_processor_id(), cwq->wq, &dwork->work);
1001 * queue_delayed_work - queue work on a workqueue after delay
1002 * @wq: workqueue to use
1003 * @dwork: delayable work to queue
1004 * @delay: number of jiffies to wait before queueing
1006 * Returns 0 if @work was already on a queue, non-zero otherwise.
1008 int queue_delayed_work(struct workqueue_struct *wq,
1009 struct delayed_work *dwork, unsigned long delay)
1012 return queue_work(wq, &dwork->work);
1014 return queue_delayed_work_on(-1, wq, dwork, delay);
1016 EXPORT_SYMBOL_GPL(queue_delayed_work);
1019 * queue_delayed_work_on - queue work on specific CPU after delay
1020 * @cpu: CPU number to execute work on
1021 * @wq: workqueue to use
1022 * @dwork: work to queue
1023 * @delay: number of jiffies to wait before queueing
1025 * Returns 0 if @work was already on a queue, non-zero otherwise.
1027 int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1028 struct delayed_work *dwork, unsigned long delay)
1031 struct timer_list *timer = &dwork->timer;
1032 struct work_struct *work = &dwork->work;
1034 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1035 struct global_cwq *gcwq = get_work_gcwq(work);
1036 unsigned int lcpu = gcwq ? gcwq->cpu : raw_smp_processor_id();
1038 BUG_ON(timer_pending(timer));
1039 BUG_ON(!list_empty(&work->entry));
1041 timer_stats_timer_set_start_info(&dwork->timer);
1043 * This stores cwq for the moment, for the timer_fn.
1044 * Note that the work's gcwq is preserved to allow
1045 * reentrance detection for delayed works.
1047 set_work_cwq(work, get_cwq(lcpu, wq), 0);
1048 timer->expires = jiffies + delay;
1049 timer->data = (unsigned long)dwork;
1050 timer->function = delayed_work_timer_fn;
1052 if (unlikely(cpu >= 0))
1053 add_timer_on(timer, cpu);
1060 EXPORT_SYMBOL_GPL(queue_delayed_work_on);
1063 * worker_enter_idle - enter idle state
1064 * @worker: worker which is entering idle state
1066 * @worker is entering idle state. Update stats and idle timer if
1070 * spin_lock_irq(gcwq->lock).
1072 static void worker_enter_idle(struct worker *worker)
1074 struct global_cwq *gcwq = worker->gcwq;
1076 BUG_ON(worker->flags & WORKER_IDLE);
1077 BUG_ON(!list_empty(&worker->entry) &&
1078 (worker->hentry.next || worker->hentry.pprev));
1080 /* can't use worker_set_flags(), also called from start_worker() */
1081 worker->flags |= WORKER_IDLE;
1083 worker->last_active = jiffies;
1085 /* idle_list is LIFO */
1086 list_add(&worker->entry, &gcwq->idle_list);
1088 if (likely(!(worker->flags & WORKER_ROGUE))) {
1089 if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer))
1090 mod_timer(&gcwq->idle_timer,
1091 jiffies + IDLE_WORKER_TIMEOUT);
1093 wake_up_all(&gcwq->trustee_wait);
1095 /* sanity check nr_running */
1096 WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle &&
1097 atomic_read(get_gcwq_nr_running(gcwq->cpu)));
1101 * worker_leave_idle - leave idle state
1102 * @worker: worker which is leaving idle state
1104 * @worker is leaving idle state. Update stats.
1107 * spin_lock_irq(gcwq->lock).
1109 static void worker_leave_idle(struct worker *worker)
1111 struct global_cwq *gcwq = worker->gcwq;
1113 BUG_ON(!(worker->flags & WORKER_IDLE));
1114 worker_clr_flags(worker, WORKER_IDLE);
1116 list_del_init(&worker->entry);
1120 * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
1123 * Works which are scheduled while the cpu is online must at least be
1124 * scheduled to a worker which is bound to the cpu so that if they are
1125 * flushed from cpu callbacks while cpu is going down, they are
1126 * guaranteed to execute on the cpu.
1128 * This function is to be used by rogue workers and rescuers to bind
1129 * themselves to the target cpu and may race with cpu going down or
1130 * coming online. kthread_bind() can't be used because it may put the
1131 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1132 * verbatim as it's best effort and blocking and gcwq may be
1133 * [dis]associated in the meantime.
1135 * This function tries set_cpus_allowed() and locks gcwq and verifies
1136 * the binding against GCWQ_DISASSOCIATED which is set during
1137 * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters
1138 * idle state or fetches works without dropping lock, it can guarantee
1139 * the scheduling requirement described in the first paragraph.
1142 * Might sleep. Called without any lock but returns with gcwq->lock
1146 * %true if the associated gcwq is online (@worker is successfully
1147 * bound), %false if offline.
1149 static bool worker_maybe_bind_and_lock(struct worker *worker)
1151 struct global_cwq *gcwq = worker->gcwq;
1152 struct task_struct *task = worker->task;
1156 * The following call may fail, succeed or succeed
1157 * without actually migrating the task to the cpu if
1158 * it races with cpu hotunplug operation. Verify
1159 * against GCWQ_DISASSOCIATED.
1161 set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
1163 spin_lock_irq(&gcwq->lock);
1164 if (gcwq->flags & GCWQ_DISASSOCIATED)
1166 if (task_cpu(task) == gcwq->cpu &&
1167 cpumask_equal(¤t->cpus_allowed,
1168 get_cpu_mask(gcwq->cpu)))
1170 spin_unlock_irq(&gcwq->lock);
1172 /* CPU has come up inbetween, retry migration */
1178 * Function for worker->rebind_work used to rebind rogue busy workers
1179 * to the associated cpu which is coming back online. This is
1180 * scheduled by cpu up but can race with other cpu hotplug operations
1181 * and may be executed twice without intervening cpu down.
1183 static void worker_rebind_fn(struct work_struct *work)
1185 struct worker *worker = container_of(work, struct worker, rebind_work);
1186 struct global_cwq *gcwq = worker->gcwq;
1188 if (worker_maybe_bind_and_lock(worker))
1189 worker_clr_flags(worker, WORKER_REBIND);
1191 spin_unlock_irq(&gcwq->lock);
1194 static struct worker *alloc_worker(void)
1196 struct worker *worker;
1198 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
1200 INIT_LIST_HEAD(&worker->entry);
1201 INIT_LIST_HEAD(&worker->scheduled);
1202 INIT_WORK(&worker->rebind_work, worker_rebind_fn);
1203 /* on creation a worker is in !idle && prep state */
1204 worker->flags = WORKER_PREP;
1210 * create_worker - create a new workqueue worker
1211 * @gcwq: gcwq the new worker will belong to
1212 * @bind: whether to set affinity to @cpu or not
1214 * Create a new worker which is bound to @gcwq. The returned worker
1215 * can be started by calling start_worker() or destroyed using
1219 * Might sleep. Does GFP_KERNEL allocations.
1222 * Pointer to the newly created worker.
1224 static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
1227 struct worker *worker = NULL;
1229 spin_lock_irq(&gcwq->lock);
1230 while (ida_get_new(&gcwq->worker_ida, &id)) {
1231 spin_unlock_irq(&gcwq->lock);
1232 if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL))
1234 spin_lock_irq(&gcwq->lock);
1236 spin_unlock_irq(&gcwq->lock);
1238 worker = alloc_worker();
1242 worker->gcwq = gcwq;
1245 worker->task = kthread_create(worker_thread, worker, "kworker/%u:%d",
1247 if (IS_ERR(worker->task))
1251 * A rogue worker will become a regular one if CPU comes
1252 * online later on. Make sure every worker has
1253 * PF_THREAD_BOUND set.
1256 kthread_bind(worker->task, gcwq->cpu);
1258 worker->task->flags |= PF_THREAD_BOUND;
1263 spin_lock_irq(&gcwq->lock);
1264 ida_remove(&gcwq->worker_ida, id);
1265 spin_unlock_irq(&gcwq->lock);
1272 * start_worker - start a newly created worker
1273 * @worker: worker to start
1275 * Make the gcwq aware of @worker and start it.
1278 * spin_lock_irq(gcwq->lock).
1280 static void start_worker(struct worker *worker)
1282 worker->flags |= WORKER_STARTED;
1283 worker->gcwq->nr_workers++;
1284 worker_enter_idle(worker);
1285 wake_up_process(worker->task);
1289 * destroy_worker - destroy a workqueue worker
1290 * @worker: worker to be destroyed
1292 * Destroy @worker and adjust @gcwq stats accordingly.
1295 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1297 static void destroy_worker(struct worker *worker)
1299 struct global_cwq *gcwq = worker->gcwq;
1300 int id = worker->id;
1302 /* sanity check frenzy */
1303 BUG_ON(worker->current_work);
1304 BUG_ON(!list_empty(&worker->scheduled));
1306 if (worker->flags & WORKER_STARTED)
1308 if (worker->flags & WORKER_IDLE)
1311 list_del_init(&worker->entry);
1312 worker->flags |= WORKER_DIE;
1314 spin_unlock_irq(&gcwq->lock);
1316 kthread_stop(worker->task);
1319 spin_lock_irq(&gcwq->lock);
1320 ida_remove(&gcwq->worker_ida, id);
1323 static void idle_worker_timeout(unsigned long __gcwq)
1325 struct global_cwq *gcwq = (void *)__gcwq;
1327 spin_lock_irq(&gcwq->lock);
1329 if (too_many_workers(gcwq)) {
1330 struct worker *worker;
1331 unsigned long expires;
1333 /* idle_list is kept in LIFO order, check the last one */
1334 worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
1335 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1337 if (time_before(jiffies, expires))
1338 mod_timer(&gcwq->idle_timer, expires);
1340 /* it's been idle for too long, wake up manager */
1341 gcwq->flags |= GCWQ_MANAGE_WORKERS;
1342 wake_up_worker(gcwq);
1346 spin_unlock_irq(&gcwq->lock);
1349 static bool send_mayday(struct work_struct *work)
1351 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1352 struct workqueue_struct *wq = cwq->wq;
1354 if (!(wq->flags & WQ_RESCUER))
1357 /* mayday mayday mayday */
1358 if (!cpumask_test_and_set_cpu(cwq->gcwq->cpu, wq->mayday_mask))
1359 wake_up_process(wq->rescuer->task);
1363 static void gcwq_mayday_timeout(unsigned long __gcwq)
1365 struct global_cwq *gcwq = (void *)__gcwq;
1366 struct work_struct *work;
1368 spin_lock_irq(&gcwq->lock);
1370 if (need_to_create_worker(gcwq)) {
1372 * We've been trying to create a new worker but
1373 * haven't been successful. We might be hitting an
1374 * allocation deadlock. Send distress signals to
1377 list_for_each_entry(work, &gcwq->worklist, entry)
1381 spin_unlock_irq(&gcwq->lock);
1383 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL);
1387 * maybe_create_worker - create a new worker if necessary
1388 * @gcwq: gcwq to create a new worker for
1390 * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to
1391 * have at least one idle worker on return from this function. If
1392 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1393 * sent to all rescuers with works scheduled on @gcwq to resolve
1394 * possible allocation deadlock.
1396 * On return, need_to_create_worker() is guaranteed to be false and
1397 * may_start_working() true.
1400 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1401 * multiple times. Does GFP_KERNEL allocations. Called only from
1405 * false if no action was taken and gcwq->lock stayed locked, true
1408 static bool maybe_create_worker(struct global_cwq *gcwq)
1410 if (!need_to_create_worker(gcwq))
1413 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1414 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
1417 struct worker *worker;
1419 spin_unlock_irq(&gcwq->lock);
1421 worker = create_worker(gcwq, true);
1423 del_timer_sync(&gcwq->mayday_timer);
1424 spin_lock_irq(&gcwq->lock);
1425 start_worker(worker);
1426 BUG_ON(need_to_create_worker(gcwq));
1430 if (!need_to_create_worker(gcwq))
1433 spin_unlock_irq(&gcwq->lock);
1434 __set_current_state(TASK_INTERRUPTIBLE);
1435 schedule_timeout(CREATE_COOLDOWN);
1436 spin_lock_irq(&gcwq->lock);
1437 if (!need_to_create_worker(gcwq))
1441 spin_unlock_irq(&gcwq->lock);
1442 del_timer_sync(&gcwq->mayday_timer);
1443 spin_lock_irq(&gcwq->lock);
1444 if (need_to_create_worker(gcwq))
1450 * maybe_destroy_worker - destroy workers which have been idle for a while
1451 * @gcwq: gcwq to destroy workers for
1453 * Destroy @gcwq workers which have been idle for longer than
1454 * IDLE_WORKER_TIMEOUT.
1457 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1458 * multiple times. Called only from manager.
1461 * false if no action was taken and gcwq->lock stayed locked, true
1464 static bool maybe_destroy_workers(struct global_cwq *gcwq)
1468 while (too_many_workers(gcwq)) {
1469 struct worker *worker;
1470 unsigned long expires;
1472 worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
1473 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1475 if (time_before(jiffies, expires)) {
1476 mod_timer(&gcwq->idle_timer, expires);
1480 destroy_worker(worker);
1488 * manage_workers - manage worker pool
1491 * Assume the manager role and manage gcwq worker pool @worker belongs
1492 * to. At any given time, there can be only zero or one manager per
1493 * gcwq. The exclusion is handled automatically by this function.
1495 * The caller can safely start processing works on false return. On
1496 * true return, it's guaranteed that need_to_create_worker() is false
1497 * and may_start_working() is true.
1500 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1501 * multiple times. Does GFP_KERNEL allocations.
1504 * false if no action was taken and gcwq->lock stayed locked, true if
1505 * some action was taken.
1507 static bool manage_workers(struct worker *worker)
1509 struct global_cwq *gcwq = worker->gcwq;
1512 if (gcwq->flags & GCWQ_MANAGING_WORKERS)
1515 gcwq->flags &= ~GCWQ_MANAGE_WORKERS;
1516 gcwq->flags |= GCWQ_MANAGING_WORKERS;
1519 * Destroy and then create so that may_start_working() is true
1522 ret |= maybe_destroy_workers(gcwq);
1523 ret |= maybe_create_worker(gcwq);
1525 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
1528 * The trustee might be waiting to take over the manager
1529 * position, tell it we're done.
1531 if (unlikely(gcwq->trustee))
1532 wake_up_all(&gcwq->trustee_wait);
1538 * move_linked_works - move linked works to a list
1539 * @work: start of series of works to be scheduled
1540 * @head: target list to append @work to
1541 * @nextp: out paramter for nested worklist walking
1543 * Schedule linked works starting from @work to @head. Work series to
1544 * be scheduled starts at @work and includes any consecutive work with
1545 * WORK_STRUCT_LINKED set in its predecessor.
1547 * If @nextp is not NULL, it's updated to point to the next work of
1548 * the last scheduled work. This allows move_linked_works() to be
1549 * nested inside outer list_for_each_entry_safe().
1552 * spin_lock_irq(gcwq->lock).
1554 static void move_linked_works(struct work_struct *work, struct list_head *head,
1555 struct work_struct **nextp)
1557 struct work_struct *n;
1560 * Linked worklist will always end before the end of the list,
1561 * use NULL for list head.
1563 list_for_each_entry_safe_from(work, n, NULL, entry) {
1564 list_move_tail(&work->entry, head);
1565 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1570 * If we're already inside safe list traversal and have moved
1571 * multiple works to the scheduled queue, the next position
1572 * needs to be updated.
1578 static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
1580 struct work_struct *work = list_first_entry(&cwq->delayed_works,
1581 struct work_struct, entry);
1582 struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
1584 move_linked_works(work, pos, NULL);
1589 * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
1590 * @cwq: cwq of interest
1591 * @color: color of work which left the queue
1593 * A work either has completed or is removed from pending queue,
1594 * decrement nr_in_flight of its cwq and handle workqueue flushing.
1597 * spin_lock_irq(gcwq->lock).
1599 static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
1601 /* ignore uncolored works */
1602 if (color == WORK_NO_COLOR)
1605 cwq->nr_in_flight[color]--;
1608 if (!list_empty(&cwq->delayed_works)) {
1609 /* one down, submit a delayed one */
1610 if (cwq->nr_active < cwq->max_active)
1611 cwq_activate_first_delayed(cwq);
1612 } else if (!cwq->nr_active && cwq->wq->flags & WQ_SINGLE_CPU) {
1613 /* this was the last work, unbind from single cpu */
1614 cwq_unbind_single_cpu(cwq);
1617 /* is flush in progress and are we at the flushing tip? */
1618 if (likely(cwq->flush_color != color))
1621 /* are there still in-flight works? */
1622 if (cwq->nr_in_flight[color])
1625 /* this cwq is done, clear flush_color */
1626 cwq->flush_color = -1;
1629 * If this was the last cwq, wake up the first flusher. It
1630 * will handle the rest.
1632 if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
1633 complete(&cwq->wq->first_flusher->done);
1637 * process_one_work - process single work
1639 * @work: work to process
1641 * Process @work. This function contains all the logics necessary to
1642 * process a single work including synchronization against and
1643 * interaction with other workers on the same cpu, queueing and
1644 * flushing. As long as context requirement is met, any worker can
1645 * call this function to process a work.
1648 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1650 static void process_one_work(struct worker *worker, struct work_struct *work)
1652 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1653 struct global_cwq *gcwq = cwq->gcwq;
1654 struct hlist_head *bwh = busy_worker_head(gcwq, work);
1655 bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
1656 work_func_t f = work->func;
1658 struct worker *collision;
1659 #ifdef CONFIG_LOCKDEP
1661 * It is permissible to free the struct work_struct from
1662 * inside the function that is called from it, this we need to
1663 * take into account for lockdep too. To avoid bogus "held
1664 * lock freed" warnings as well as problems when looking into
1665 * work->lockdep_map, make a copy and use that here.
1667 struct lockdep_map lockdep_map = work->lockdep_map;
1670 * A single work shouldn't be executed concurrently by
1671 * multiple workers on a single cpu. Check whether anyone is
1672 * already processing the work. If so, defer the work to the
1673 * currently executing one.
1675 collision = __find_worker_executing_work(gcwq, bwh, work);
1676 if (unlikely(collision)) {
1677 move_linked_works(work, &collision->scheduled, NULL);
1681 /* claim and process */
1682 debug_work_deactivate(work);
1683 hlist_add_head(&worker->hentry, bwh);
1684 worker->current_work = work;
1685 worker->current_cwq = cwq;
1686 work_color = get_work_color(work);
1688 /* record the current cpu number in the work data and dequeue */
1689 set_work_cpu(work, gcwq->cpu);
1690 list_del_init(&work->entry);
1693 * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI,
1694 * wake up another worker; otherwise, clear HIGHPRI_PENDING.
1696 if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) {
1697 struct work_struct *nwork = list_first_entry(&gcwq->worklist,
1698 struct work_struct, entry);
1700 if (!list_empty(&gcwq->worklist) &&
1701 get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI)
1702 wake_up_worker(gcwq);
1704 gcwq->flags &= ~GCWQ_HIGHPRI_PENDING;
1708 * CPU intensive works don't participate in concurrency
1709 * management. They're the scheduler's responsibility.
1711 if (unlikely(cpu_intensive))
1712 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
1714 spin_unlock_irq(&gcwq->lock);
1716 work_clear_pending(work);
1717 lock_map_acquire(&cwq->wq->lockdep_map);
1718 lock_map_acquire(&lockdep_map);
1720 lock_map_release(&lockdep_map);
1721 lock_map_release(&cwq->wq->lockdep_map);
1723 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
1724 printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
1726 current->comm, preempt_count(), task_pid_nr(current));
1727 printk(KERN_ERR " last function: ");
1728 print_symbol("%s\n", (unsigned long)f);
1729 debug_show_held_locks(current);
1733 spin_lock_irq(&gcwq->lock);
1735 /* clear cpu intensive status */
1736 if (unlikely(cpu_intensive))
1737 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
1739 /* we're done with it, release */
1740 hlist_del_init(&worker->hentry);
1741 worker->current_work = NULL;
1742 worker->current_cwq = NULL;
1743 cwq_dec_nr_in_flight(cwq, work_color);
1747 * process_scheduled_works - process scheduled works
1750 * Process all scheduled works. Please note that the scheduled list
1751 * may change while processing a work, so this function repeatedly
1752 * fetches a work from the top and executes it.
1755 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1758 static void process_scheduled_works(struct worker *worker)
1760 while (!list_empty(&worker->scheduled)) {
1761 struct work_struct *work = list_first_entry(&worker->scheduled,
1762 struct work_struct, entry);
1763 process_one_work(worker, work);
1768 * worker_thread - the worker thread function
1771 * The gcwq worker thread function. There's a single dynamic pool of
1772 * these per each cpu. These workers process all works regardless of
1773 * their specific target workqueue. The only exception is works which
1774 * belong to workqueues with a rescuer which will be explained in
1777 static int worker_thread(void *__worker)
1779 struct worker *worker = __worker;
1780 struct global_cwq *gcwq = worker->gcwq;
1782 /* tell the scheduler that this is a workqueue worker */
1783 worker->task->flags |= PF_WQ_WORKER;
1785 spin_lock_irq(&gcwq->lock);
1787 /* DIE can be set only while we're idle, checking here is enough */
1788 if (worker->flags & WORKER_DIE) {
1789 spin_unlock_irq(&gcwq->lock);
1790 worker->task->flags &= ~PF_WQ_WORKER;
1794 worker_leave_idle(worker);
1796 /* no more worker necessary? */
1797 if (!need_more_worker(gcwq))
1800 /* do we need to manage? */
1801 if (unlikely(!may_start_working(gcwq)) && manage_workers(worker))
1805 * ->scheduled list can only be filled while a worker is
1806 * preparing to process a work or actually processing it.
1807 * Make sure nobody diddled with it while I was sleeping.
1809 BUG_ON(!list_empty(&worker->scheduled));
1812 * When control reaches this point, we're guaranteed to have
1813 * at least one idle worker or that someone else has already
1814 * assumed the manager role.
1816 worker_clr_flags(worker, WORKER_PREP);
1819 struct work_struct *work =
1820 list_first_entry(&gcwq->worklist,
1821 struct work_struct, entry);
1823 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
1824 /* optimization path, not strictly necessary */
1825 process_one_work(worker, work);
1826 if (unlikely(!list_empty(&worker->scheduled)))
1827 process_scheduled_works(worker);
1829 move_linked_works(work, &worker->scheduled, NULL);
1830 process_scheduled_works(worker);
1832 } while (keep_working(gcwq));
1834 worker_set_flags(worker, WORKER_PREP, false);
1836 if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker))
1840 * gcwq->lock is held and there's no work to process and no
1841 * need to manage, sleep. Workers are woken up only while
1842 * holding gcwq->lock or from local cpu, so setting the
1843 * current state before releasing gcwq->lock is enough to
1844 * prevent losing any event.
1846 worker_enter_idle(worker);
1847 __set_current_state(TASK_INTERRUPTIBLE);
1848 spin_unlock_irq(&gcwq->lock);
1854 * rescuer_thread - the rescuer thread function
1855 * @__wq: the associated workqueue
1857 * Workqueue rescuer thread function. There's one rescuer for each
1858 * workqueue which has WQ_RESCUER set.
1860 * Regular work processing on a gcwq may block trying to create a new
1861 * worker which uses GFP_KERNEL allocation which has slight chance of
1862 * developing into deadlock if some works currently on the same queue
1863 * need to be processed to satisfy the GFP_KERNEL allocation. This is
1864 * the problem rescuer solves.
1866 * When such condition is possible, the gcwq summons rescuers of all
1867 * workqueues which have works queued on the gcwq and let them process
1868 * those works so that forward progress can be guaranteed.
1870 * This should happen rarely.
1872 static int rescuer_thread(void *__wq)
1874 struct workqueue_struct *wq = __wq;
1875 struct worker *rescuer = wq->rescuer;
1876 struct list_head *scheduled = &rescuer->scheduled;
1879 set_user_nice(current, RESCUER_NICE_LEVEL);
1881 set_current_state(TASK_INTERRUPTIBLE);
1883 if (kthread_should_stop())
1886 for_each_cpu(cpu, wq->mayday_mask) {
1887 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
1888 struct global_cwq *gcwq = cwq->gcwq;
1889 struct work_struct *work, *n;
1891 __set_current_state(TASK_RUNNING);
1892 cpumask_clear_cpu(cpu, wq->mayday_mask);
1894 /* migrate to the target cpu if possible */
1895 rescuer->gcwq = gcwq;
1896 worker_maybe_bind_and_lock(rescuer);
1899 * Slurp in all works issued via this workqueue and
1902 BUG_ON(!list_empty(&rescuer->scheduled));
1903 list_for_each_entry_safe(work, n, &gcwq->worklist, entry)
1904 if (get_work_cwq(work) == cwq)
1905 move_linked_works(work, scheduled, &n);
1907 process_scheduled_works(rescuer);
1908 spin_unlock_irq(&gcwq->lock);
1916 struct work_struct work;
1917 struct completion done;
1920 static void wq_barrier_func(struct work_struct *work)
1922 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
1923 complete(&barr->done);
1927 * insert_wq_barrier - insert a barrier work
1928 * @cwq: cwq to insert barrier into
1929 * @barr: wq_barrier to insert
1930 * @target: target work to attach @barr to
1931 * @worker: worker currently executing @target, NULL if @target is not executing
1933 * @barr is linked to @target such that @barr is completed only after
1934 * @target finishes execution. Please note that the ordering
1935 * guarantee is observed only with respect to @target and on the local
1938 * Currently, a queued barrier can't be canceled. This is because
1939 * try_to_grab_pending() can't determine whether the work to be
1940 * grabbed is at the head of the queue and thus can't clear LINKED
1941 * flag of the previous work while there must be a valid next work
1942 * after a work with LINKED flag set.
1944 * Note that when @worker is non-NULL, @target may be modified
1945 * underneath us, so we can't reliably determine cwq from @target.
1948 * spin_lock_irq(gcwq->lock).
1950 static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
1951 struct wq_barrier *barr,
1952 struct work_struct *target, struct worker *worker)
1954 struct list_head *head;
1955 unsigned int linked = 0;
1958 * debugobject calls are safe here even with gcwq->lock locked
1959 * as we know for sure that this will not trigger any of the
1960 * checks and call back into the fixup functions where we
1963 INIT_WORK_ON_STACK(&barr->work, wq_barrier_func);
1964 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
1965 init_completion(&barr->done);
1968 * If @target is currently being executed, schedule the
1969 * barrier to the worker; otherwise, put it after @target.
1972 head = worker->scheduled.next;
1974 unsigned long *bits = work_data_bits(target);
1976 head = target->entry.next;
1977 /* there can already be other linked works, inherit and set */
1978 linked = *bits & WORK_STRUCT_LINKED;
1979 __set_bit(WORK_STRUCT_LINKED_BIT, bits);
1982 debug_work_activate(&barr->work);
1983 insert_work(cwq, &barr->work, head,
1984 work_color_to_flags(WORK_NO_COLOR) | linked);
1988 * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
1989 * @wq: workqueue being flushed
1990 * @flush_color: new flush color, < 0 for no-op
1991 * @work_color: new work color, < 0 for no-op
1993 * Prepare cwqs for workqueue flushing.
1995 * If @flush_color is non-negative, flush_color on all cwqs should be
1996 * -1. If no cwq has in-flight commands at the specified color, all
1997 * cwq->flush_color's stay at -1 and %false is returned. If any cwq
1998 * has in flight commands, its cwq->flush_color is set to
1999 * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
2000 * wakeup logic is armed and %true is returned.
2002 * The caller should have initialized @wq->first_flusher prior to
2003 * calling this function with non-negative @flush_color. If
2004 * @flush_color is negative, no flush color update is done and %false
2007 * If @work_color is non-negative, all cwqs should have the same
2008 * work_color which is previous to @work_color and all will be
2009 * advanced to @work_color.
2012 * mutex_lock(wq->flush_mutex).
2015 * %true if @flush_color >= 0 and there's something to flush. %false
2018 static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
2019 int flush_color, int work_color)
2024 if (flush_color >= 0) {
2025 BUG_ON(atomic_read(&wq->nr_cwqs_to_flush));
2026 atomic_set(&wq->nr_cwqs_to_flush, 1);
2029 for_each_possible_cpu(cpu) {
2030 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2031 struct global_cwq *gcwq = cwq->gcwq;
2033 spin_lock_irq(&gcwq->lock);
2035 if (flush_color >= 0) {
2036 BUG_ON(cwq->flush_color != -1);
2038 if (cwq->nr_in_flight[flush_color]) {
2039 cwq->flush_color = flush_color;
2040 atomic_inc(&wq->nr_cwqs_to_flush);
2045 if (work_color >= 0) {
2046 BUG_ON(work_color != work_next_color(cwq->work_color));
2047 cwq->work_color = work_color;
2050 spin_unlock_irq(&gcwq->lock);
2053 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush))
2054 complete(&wq->first_flusher->done);
2060 * flush_workqueue - ensure that any scheduled work has run to completion.
2061 * @wq: workqueue to flush
2063 * Forces execution of the workqueue and blocks until its completion.
2064 * This is typically used in driver shutdown handlers.
2066 * We sleep until all works which were queued on entry have been handled,
2067 * but we are not livelocked by new incoming ones.
2069 void flush_workqueue(struct workqueue_struct *wq)
2071 struct wq_flusher this_flusher = {
2072 .list = LIST_HEAD_INIT(this_flusher.list),
2074 .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
2078 lock_map_acquire(&wq->lockdep_map);
2079 lock_map_release(&wq->lockdep_map);
2081 mutex_lock(&wq->flush_mutex);
2084 * Start-to-wait phase
2086 next_color = work_next_color(wq->work_color);
2088 if (next_color != wq->flush_color) {
2090 * Color space is not full. The current work_color
2091 * becomes our flush_color and work_color is advanced
2094 BUG_ON(!list_empty(&wq->flusher_overflow));
2095 this_flusher.flush_color = wq->work_color;
2096 wq->work_color = next_color;
2098 if (!wq->first_flusher) {
2099 /* no flush in progress, become the first flusher */
2100 BUG_ON(wq->flush_color != this_flusher.flush_color);
2102 wq->first_flusher = &this_flusher;
2104 if (!flush_workqueue_prep_cwqs(wq, wq->flush_color,
2106 /* nothing to flush, done */
2107 wq->flush_color = next_color;
2108 wq->first_flusher = NULL;
2113 BUG_ON(wq->flush_color == this_flusher.flush_color);
2114 list_add_tail(&this_flusher.list, &wq->flusher_queue);
2115 flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
2119 * Oops, color space is full, wait on overflow queue.
2120 * The next flush completion will assign us
2121 * flush_color and transfer to flusher_queue.
2123 list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2126 mutex_unlock(&wq->flush_mutex);
2128 wait_for_completion(&this_flusher.done);
2131 * Wake-up-and-cascade phase
2133 * First flushers are responsible for cascading flushes and
2134 * handling overflow. Non-first flushers can simply return.
2136 if (wq->first_flusher != &this_flusher)
2139 mutex_lock(&wq->flush_mutex);
2141 /* we might have raced, check again with mutex held */
2142 if (wq->first_flusher != &this_flusher)
2145 wq->first_flusher = NULL;
2147 BUG_ON(!list_empty(&this_flusher.list));
2148 BUG_ON(wq->flush_color != this_flusher.flush_color);
2151 struct wq_flusher *next, *tmp;
2153 /* complete all the flushers sharing the current flush color */
2154 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2155 if (next->flush_color != wq->flush_color)
2157 list_del_init(&next->list);
2158 complete(&next->done);
2161 BUG_ON(!list_empty(&wq->flusher_overflow) &&
2162 wq->flush_color != work_next_color(wq->work_color));
2164 /* this flush_color is finished, advance by one */
2165 wq->flush_color = work_next_color(wq->flush_color);
2167 /* one color has been freed, handle overflow queue */
2168 if (!list_empty(&wq->flusher_overflow)) {
2170 * Assign the same color to all overflowed
2171 * flushers, advance work_color and append to
2172 * flusher_queue. This is the start-to-wait
2173 * phase for these overflowed flushers.
2175 list_for_each_entry(tmp, &wq->flusher_overflow, list)
2176 tmp->flush_color = wq->work_color;
2178 wq->work_color = work_next_color(wq->work_color);
2180 list_splice_tail_init(&wq->flusher_overflow,
2181 &wq->flusher_queue);
2182 flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
2185 if (list_empty(&wq->flusher_queue)) {
2186 BUG_ON(wq->flush_color != wq->work_color);
2191 * Need to flush more colors. Make the next flusher
2192 * the new first flusher and arm cwqs.
2194 BUG_ON(wq->flush_color == wq->work_color);
2195 BUG_ON(wq->flush_color != next->flush_color);
2197 list_del_init(&next->list);
2198 wq->first_flusher = next;
2200 if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1))
2204 * Meh... this color is already done, clear first
2205 * flusher and repeat cascading.
2207 wq->first_flusher = NULL;
2211 mutex_unlock(&wq->flush_mutex);
2213 EXPORT_SYMBOL_GPL(flush_workqueue);
2216 * flush_work - block until a work_struct's callback has terminated
2217 * @work: the work which is to be flushed
2219 * Returns false if @work has already terminated.
2221 * It is expected that, prior to calling flush_work(), the caller has
2222 * arranged for the work to not be requeued, otherwise it doesn't make
2223 * sense to use this function.
2225 int flush_work(struct work_struct *work)
2227 struct worker *worker = NULL;
2228 struct global_cwq *gcwq;
2229 struct cpu_workqueue_struct *cwq;
2230 struct wq_barrier barr;
2233 gcwq = get_work_gcwq(work);
2237 spin_lock_irq(&gcwq->lock);
2238 if (!list_empty(&work->entry)) {
2240 * See the comment near try_to_grab_pending()->smp_rmb().
2241 * If it was re-queued to a different gcwq under us, we
2242 * are not going to wait.
2245 cwq = get_work_cwq(work);
2246 if (unlikely(!cwq || gcwq != cwq->gcwq))
2249 worker = find_worker_executing_work(gcwq, work);
2252 cwq = worker->current_cwq;
2255 insert_wq_barrier(cwq, &barr, work, worker);
2256 spin_unlock_irq(&gcwq->lock);
2258 lock_map_acquire(&cwq->wq->lockdep_map);
2259 lock_map_release(&cwq->wq->lockdep_map);
2261 wait_for_completion(&barr.done);
2262 destroy_work_on_stack(&barr.work);
2265 spin_unlock_irq(&gcwq->lock);
2268 EXPORT_SYMBOL_GPL(flush_work);
2271 * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
2272 * so this work can't be re-armed in any way.
2274 static int try_to_grab_pending(struct work_struct *work)
2276 struct global_cwq *gcwq;
2279 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
2283 * The queueing is in progress, or it is already queued. Try to
2284 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
2286 gcwq = get_work_gcwq(work);
2290 spin_lock_irq(&gcwq->lock);
2291 if (!list_empty(&work->entry)) {
2293 * This work is queued, but perhaps we locked the wrong gcwq.
2294 * In that case we must see the new value after rmb(), see
2295 * insert_work()->wmb().
2298 if (gcwq == get_work_gcwq(work)) {
2299 debug_work_deactivate(work);
2300 list_del_init(&work->entry);
2301 cwq_dec_nr_in_flight(get_work_cwq(work),
2302 get_work_color(work));
2306 spin_unlock_irq(&gcwq->lock);
2311 static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
2313 struct wq_barrier barr;
2314 struct worker *worker;
2316 spin_lock_irq(&gcwq->lock);
2318 worker = find_worker_executing_work(gcwq, work);
2319 if (unlikely(worker))
2320 insert_wq_barrier(worker->current_cwq, &barr, work, worker);
2322 spin_unlock_irq(&gcwq->lock);
2324 if (unlikely(worker)) {
2325 wait_for_completion(&barr.done);
2326 destroy_work_on_stack(&barr.work);
2330 static void wait_on_work(struct work_struct *work)
2336 lock_map_acquire(&work->lockdep_map);
2337 lock_map_release(&work->lockdep_map);
2339 for_each_possible_cpu(cpu)
2340 wait_on_cpu_work(get_gcwq(cpu), work);
2343 static int __cancel_work_timer(struct work_struct *work,
2344 struct timer_list* timer)
2349 ret = (timer && likely(del_timer(timer)));
2351 ret = try_to_grab_pending(work);
2353 } while (unlikely(ret < 0));
2355 clear_work_data(work);
2360 * cancel_work_sync - block until a work_struct's callback has terminated
2361 * @work: the work which is to be flushed
2363 * Returns true if @work was pending.
2365 * cancel_work_sync() will cancel the work if it is queued. If the work's
2366 * callback appears to be running, cancel_work_sync() will block until it
2369 * It is possible to use this function if the work re-queues itself. It can
2370 * cancel the work even if it migrates to another workqueue, however in that
2371 * case it only guarantees that work->func() has completed on the last queued
2374 * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not
2375 * pending, otherwise it goes into a busy-wait loop until the timer expires.
2377 * The caller must ensure that workqueue_struct on which this work was last
2378 * queued can't be destroyed before this function returns.
2380 int cancel_work_sync(struct work_struct *work)
2382 return __cancel_work_timer(work, NULL);
2384 EXPORT_SYMBOL_GPL(cancel_work_sync);
2387 * cancel_delayed_work_sync - reliably kill off a delayed work.
2388 * @dwork: the delayed work struct
2390 * Returns true if @dwork was pending.
2392 * It is possible to use this function if @dwork rearms itself via queue_work()
2393 * or queue_delayed_work(). See also the comment for cancel_work_sync().
2395 int cancel_delayed_work_sync(struct delayed_work *dwork)
2397 return __cancel_work_timer(&dwork->work, &dwork->timer);
2399 EXPORT_SYMBOL(cancel_delayed_work_sync);
2402 * schedule_work - put work task in global workqueue
2403 * @work: job to be done
2405 * Returns zero if @work was already on the kernel-global workqueue and
2406 * non-zero otherwise.
2408 * This puts a job in the kernel-global workqueue if it was not already
2409 * queued and leaves it in the same position on the kernel-global
2410 * workqueue otherwise.
2412 int schedule_work(struct work_struct *work)
2414 return queue_work(system_wq, work);
2416 EXPORT_SYMBOL(schedule_work);
2419 * schedule_work_on - put work task on a specific cpu
2420 * @cpu: cpu to put the work task on
2421 * @work: job to be done
2423 * This puts a job on a specific cpu
2425 int schedule_work_on(int cpu, struct work_struct *work)
2427 return queue_work_on(cpu, system_wq, work);
2429 EXPORT_SYMBOL(schedule_work_on);
2432 * schedule_delayed_work - put work task in global workqueue after delay
2433 * @dwork: job to be done
2434 * @delay: number of jiffies to wait or 0 for immediate execution
2436 * After waiting for a given time this puts a job in the kernel-global
2439 int schedule_delayed_work(struct delayed_work *dwork,
2440 unsigned long delay)
2442 return queue_delayed_work(system_wq, dwork, delay);
2444 EXPORT_SYMBOL(schedule_delayed_work);
2447 * flush_delayed_work - block until a dwork_struct's callback has terminated
2448 * @dwork: the delayed work which is to be flushed
2450 * Any timeout is cancelled, and any pending work is run immediately.
2452 void flush_delayed_work(struct delayed_work *dwork)
2454 if (del_timer_sync(&dwork->timer)) {
2455 __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq,
2459 flush_work(&dwork->work);
2461 EXPORT_SYMBOL(flush_delayed_work);
2464 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
2466 * @dwork: job to be done
2467 * @delay: number of jiffies to wait
2469 * After waiting for a given time this puts a job in the kernel-global
2470 * workqueue on the specified CPU.
2472 int schedule_delayed_work_on(int cpu,
2473 struct delayed_work *dwork, unsigned long delay)
2475 return queue_delayed_work_on(cpu, system_wq, dwork, delay);
2477 EXPORT_SYMBOL(schedule_delayed_work_on);
2480 * schedule_on_each_cpu - call a function on each online CPU from keventd
2481 * @func: the function to call
2483 * Returns zero on success.
2484 * Returns -ve errno on failure.
2486 * schedule_on_each_cpu() is very slow.
2488 int schedule_on_each_cpu(work_func_t func)
2491 struct work_struct *works;
2493 works = alloc_percpu(struct work_struct);
2499 for_each_online_cpu(cpu) {
2500 struct work_struct *work = per_cpu_ptr(works, cpu);
2502 INIT_WORK(work, func);
2503 schedule_work_on(cpu, work);
2506 for_each_online_cpu(cpu)
2507 flush_work(per_cpu_ptr(works, cpu));
2515 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2517 * Forces execution of the kernel-global workqueue and blocks until its
2520 * Think twice before calling this function! It's very easy to get into
2521 * trouble if you don't take great care. Either of the following situations
2522 * will lead to deadlock:
2524 * One of the work items currently on the workqueue needs to acquire
2525 * a lock held by your code or its caller.
2527 * Your code is running in the context of a work routine.
2529 * They will be detected by lockdep when they occur, but the first might not
2530 * occur very often. It depends on what work items are on the workqueue and
2531 * what locks they need, which you have no control over.
2533 * In most situations flushing the entire workqueue is overkill; you merely
2534 * need to know that a particular work item isn't queued and isn't running.
2535 * In such cases you should use cancel_delayed_work_sync() or
2536 * cancel_work_sync() instead.
2538 void flush_scheduled_work(void)
2540 flush_workqueue(system_wq);
2542 EXPORT_SYMBOL(flush_scheduled_work);
2545 * execute_in_process_context - reliably execute the routine with user context
2546 * @fn: the function to execute
2547 * @ew: guaranteed storage for the execute work structure (must
2548 * be available when the work executes)
2550 * Executes the function immediately if process context is available,
2551 * otherwise schedules the function for delayed execution.
2553 * Returns: 0 - function was executed
2554 * 1 - function was scheduled for execution
2556 int execute_in_process_context(work_func_t fn, struct execute_work *ew)
2558 if (!in_interrupt()) {
2563 INIT_WORK(&ew->work, fn);
2564 schedule_work(&ew->work);
2568 EXPORT_SYMBOL_GPL(execute_in_process_context);
2570 int keventd_up(void)
2572 return system_wq != NULL;
2575 static struct cpu_workqueue_struct *alloc_cwqs(void)
2578 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
2579 * Make sure that the alignment isn't lower than that of
2580 * unsigned long long.
2582 const size_t size = sizeof(struct cpu_workqueue_struct);
2583 const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
2584 __alignof__(unsigned long long));
2585 struct cpu_workqueue_struct *cwqs;
2590 * On UP, percpu allocator doesn't honor alignment parameter
2591 * and simply uses arch-dependent default. Allocate enough
2592 * room to align cwq and put an extra pointer at the end
2593 * pointing back to the originally allocated pointer which
2594 * will be used for free.
2596 * FIXME: This really belongs to UP percpu code. Update UP
2597 * percpu code to honor alignment and remove this ugliness.
2599 ptr = __alloc_percpu(size + align + sizeof(void *), 1);
2600 cwqs = PTR_ALIGN(ptr, align);
2601 *(void **)per_cpu_ptr(cwqs + 1, 0) = ptr;
2603 /* On SMP, percpu allocator can do it itself */
2604 cwqs = __alloc_percpu(size, align);
2606 /* just in case, make sure it's actually aligned */
2607 BUG_ON(!IS_ALIGNED((unsigned long)cwqs, align));
2611 static void free_cwqs(struct cpu_workqueue_struct *cwqs)
2614 /* on UP, the pointer to free is stored right after the cwq */
2616 free_percpu(*(void **)per_cpu_ptr(cwqs + 1, 0));
2622 static int wq_clamp_max_active(int max_active, const char *name)
2624 if (max_active < 1 || max_active > WQ_MAX_ACTIVE)
2625 printk(KERN_WARNING "workqueue: max_active %d requested for %s "
2626 "is out of range, clamping between %d and %d\n",
2627 max_active, name, 1, WQ_MAX_ACTIVE);
2629 return clamp_val(max_active, 1, WQ_MAX_ACTIVE);
2632 struct workqueue_struct *__alloc_workqueue_key(const char *name,
2635 struct lock_class_key *key,
2636 const char *lock_name)
2638 struct workqueue_struct *wq;
2641 max_active = max_active ?: WQ_DFL_ACTIVE;
2642 max_active = wq_clamp_max_active(max_active, name);
2644 wq = kzalloc(sizeof(*wq), GFP_KERNEL);
2648 wq->cpu_wq = alloc_cwqs();
2653 wq->saved_max_active = max_active;
2654 mutex_init(&wq->flush_mutex);
2655 atomic_set(&wq->nr_cwqs_to_flush, 0);
2656 INIT_LIST_HEAD(&wq->flusher_queue);
2657 INIT_LIST_HEAD(&wq->flusher_overflow);
2658 wq->single_cpu = NR_CPUS;
2661 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
2662 INIT_LIST_HEAD(&wq->list);
2664 for_each_possible_cpu(cpu) {
2665 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2666 struct global_cwq *gcwq = get_gcwq(cpu);
2668 BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
2671 cwq->flush_color = -1;
2672 cwq->max_active = max_active;
2673 INIT_LIST_HEAD(&cwq->delayed_works);
2676 if (flags & WQ_RESCUER) {
2677 struct worker *rescuer;
2679 if (!alloc_cpumask_var(&wq->mayday_mask, GFP_KERNEL))
2682 wq->rescuer = rescuer = alloc_worker();
2686 rescuer->task = kthread_create(rescuer_thread, wq, "%s", name);
2687 if (IS_ERR(rescuer->task))
2690 wq->rescuer = rescuer;
2691 rescuer->task->flags |= PF_THREAD_BOUND;
2692 wake_up_process(rescuer->task);
2696 * workqueue_lock protects global freeze state and workqueues
2697 * list. Grab it, set max_active accordingly and add the new
2698 * workqueue to workqueues list.
2700 spin_lock(&workqueue_lock);
2702 if (workqueue_freezing && wq->flags & WQ_FREEZEABLE)
2703 for_each_possible_cpu(cpu)
2704 get_cwq(cpu, wq)->max_active = 0;
2706 list_add(&wq->list, &workqueues);
2708 spin_unlock(&workqueue_lock);
2713 free_cwqs(wq->cpu_wq);
2714 free_cpumask_var(wq->mayday_mask);
2720 EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
2723 * destroy_workqueue - safely terminate a workqueue
2724 * @wq: target workqueue
2726 * Safely destroy a workqueue. All work currently pending will be done first.
2728 void destroy_workqueue(struct workqueue_struct *wq)
2732 flush_workqueue(wq);
2735 * wq list is used to freeze wq, remove from list after
2736 * flushing is complete in case freeze races us.
2738 spin_lock(&workqueue_lock);
2739 list_del(&wq->list);
2740 spin_unlock(&workqueue_lock);
2743 for_each_possible_cpu(cpu) {
2744 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2747 for (i = 0; i < WORK_NR_COLORS; i++)
2748 BUG_ON(cwq->nr_in_flight[i]);
2749 BUG_ON(cwq->nr_active);
2750 BUG_ON(!list_empty(&cwq->delayed_works));
2753 if (wq->flags & WQ_RESCUER) {
2754 kthread_stop(wq->rescuer->task);
2755 free_cpumask_var(wq->mayday_mask);
2758 free_cwqs(wq->cpu_wq);
2761 EXPORT_SYMBOL_GPL(destroy_workqueue);
2764 * workqueue_set_max_active - adjust max_active of a workqueue
2765 * @wq: target workqueue
2766 * @max_active: new max_active value.
2768 * Set max_active of @wq to @max_active.
2771 * Don't call from IRQ context.
2773 void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
2777 max_active = wq_clamp_max_active(max_active, wq->name);
2779 spin_lock(&workqueue_lock);
2781 wq->saved_max_active = max_active;
2783 for_each_possible_cpu(cpu) {
2784 struct global_cwq *gcwq = get_gcwq(cpu);
2786 spin_lock_irq(&gcwq->lock);
2788 if (!(wq->flags & WQ_FREEZEABLE) ||
2789 !(gcwq->flags & GCWQ_FREEZING))
2790 get_cwq(gcwq->cpu, wq)->max_active = max_active;
2792 spin_unlock_irq(&gcwq->lock);
2795 spin_unlock(&workqueue_lock);
2797 EXPORT_SYMBOL_GPL(workqueue_set_max_active);
2800 * workqueue_congested - test whether a workqueue is congested
2801 * @cpu: CPU in question
2802 * @wq: target workqueue
2804 * Test whether @wq's cpu workqueue for @cpu is congested. There is
2805 * no synchronization around this function and the test result is
2806 * unreliable and only useful as advisory hints or for debugging.
2809 * %true if congested, %false otherwise.
2811 bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
2813 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2815 return !list_empty(&cwq->delayed_works);
2817 EXPORT_SYMBOL_GPL(workqueue_congested);
2820 * work_cpu - return the last known associated cpu for @work
2821 * @work: the work of interest
2824 * CPU number if @work was ever queued. NR_CPUS otherwise.
2826 unsigned int work_cpu(struct work_struct *work)
2828 struct global_cwq *gcwq = get_work_gcwq(work);
2830 return gcwq ? gcwq->cpu : NR_CPUS;
2832 EXPORT_SYMBOL_GPL(work_cpu);
2835 * work_busy - test whether a work is currently pending or running
2836 * @work: the work to be tested
2838 * Test whether @work is currently pending or running. There is no
2839 * synchronization around this function and the test result is
2840 * unreliable and only useful as advisory hints or for debugging.
2841 * Especially for reentrant wqs, the pending state might hide the
2845 * OR'd bitmask of WORK_BUSY_* bits.
2847 unsigned int work_busy(struct work_struct *work)
2849 struct global_cwq *gcwq = get_work_gcwq(work);
2850 unsigned long flags;
2851 unsigned int ret = 0;
2856 spin_lock_irqsave(&gcwq->lock, flags);
2858 if (work_pending(work))
2859 ret |= WORK_BUSY_PENDING;
2860 if (find_worker_executing_work(gcwq, work))
2861 ret |= WORK_BUSY_RUNNING;
2863 spin_unlock_irqrestore(&gcwq->lock, flags);
2867 EXPORT_SYMBOL_GPL(work_busy);
2872 * There are two challenges in supporting CPU hotplug. Firstly, there
2873 * are a lot of assumptions on strong associations among work, cwq and
2874 * gcwq which make migrating pending and scheduled works very
2875 * difficult to implement without impacting hot paths. Secondly,
2876 * gcwqs serve mix of short, long and very long running works making
2877 * blocked draining impractical.
2879 * This is solved by allowing a gcwq to be detached from CPU, running
2880 * it with unbound (rogue) workers and allowing it to be reattached
2881 * later if the cpu comes back online. A separate thread is created
2882 * to govern a gcwq in such state and is called the trustee of the
2885 * Trustee states and their descriptions.
2887 * START Command state used on startup. On CPU_DOWN_PREPARE, a
2888 * new trustee is started with this state.
2890 * IN_CHARGE Once started, trustee will enter this state after
2891 * assuming the manager role and making all existing
2892 * workers rogue. DOWN_PREPARE waits for trustee to
2893 * enter this state. After reaching IN_CHARGE, trustee
2894 * tries to execute the pending worklist until it's empty
2895 * and the state is set to BUTCHER, or the state is set
2898 * BUTCHER Command state which is set by the cpu callback after
2899 * the cpu has went down. Once this state is set trustee
2900 * knows that there will be no new works on the worklist
2901 * and once the worklist is empty it can proceed to
2902 * killing idle workers.
2904 * RELEASE Command state which is set by the cpu callback if the
2905 * cpu down has been canceled or it has come online
2906 * again. After recognizing this state, trustee stops
2907 * trying to drain or butcher and clears ROGUE, rebinds
2908 * all remaining workers back to the cpu and releases
2911 * DONE Trustee will enter this state after BUTCHER or RELEASE
2914 * trustee CPU draining
2915 * took over down complete
2916 * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
2918 * | CPU is back online v return workers |
2919 * ----------------> RELEASE --------------
2923 * trustee_wait_event_timeout - timed event wait for trustee
2924 * @cond: condition to wait for
2925 * @timeout: timeout in jiffies
2927 * wait_event_timeout() for trustee to use. Handles locking and
2928 * checks for RELEASE request.
2931 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
2932 * multiple times. To be used by trustee.
2935 * Positive indicating left time if @cond is satisfied, 0 if timed
2936 * out, -1 if canceled.
2938 #define trustee_wait_event_timeout(cond, timeout) ({ \
2939 long __ret = (timeout); \
2940 while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \
2942 spin_unlock_irq(&gcwq->lock); \
2943 __wait_event_timeout(gcwq->trustee_wait, (cond) || \
2944 (gcwq->trustee_state == TRUSTEE_RELEASE), \
2946 spin_lock_irq(&gcwq->lock); \
2948 gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \
2952 * trustee_wait_event - event wait for trustee
2953 * @cond: condition to wait for
2955 * wait_event() for trustee to use. Automatically handles locking and
2956 * checks for CANCEL request.
2959 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
2960 * multiple times. To be used by trustee.
2963 * 0 if @cond is satisfied, -1 if canceled.
2965 #define trustee_wait_event(cond) ({ \
2967 __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
2968 __ret1 < 0 ? -1 : 0; \
2971 static int __cpuinit trustee_thread(void *__gcwq)
2973 struct global_cwq *gcwq = __gcwq;
2974 struct worker *worker;
2975 struct work_struct *work;
2976 struct hlist_node *pos;
2980 BUG_ON(gcwq->cpu != smp_processor_id());
2982 spin_lock_irq(&gcwq->lock);
2984 * Claim the manager position and make all workers rogue.
2985 * Trustee must be bound to the target cpu and can't be
2988 BUG_ON(gcwq->cpu != smp_processor_id());
2989 rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS));
2992 gcwq->flags |= GCWQ_MANAGING_WORKERS;
2994 list_for_each_entry(worker, &gcwq->idle_list, entry)
2995 worker->flags |= WORKER_ROGUE;
2997 for_each_busy_worker(worker, i, pos, gcwq)
2998 worker->flags |= WORKER_ROGUE;
3001 * Call schedule() so that we cross rq->lock and thus can
3002 * guarantee sched callbacks see the rogue flag. This is
3003 * necessary as scheduler callbacks may be invoked from other
3006 spin_unlock_irq(&gcwq->lock);
3008 spin_lock_irq(&gcwq->lock);
3011 * Sched callbacks are disabled now. Zap nr_running. After
3012 * this, nr_running stays zero and need_more_worker() and
3013 * keep_working() are always true as long as the worklist is
3016 atomic_set(get_gcwq_nr_running(gcwq->cpu), 0);
3018 spin_unlock_irq(&gcwq->lock);
3019 del_timer_sync(&gcwq->idle_timer);
3020 spin_lock_irq(&gcwq->lock);
3023 * We're now in charge. Notify and proceed to drain. We need
3024 * to keep the gcwq running during the whole CPU down
3025 * procedure as other cpu hotunplug callbacks may need to
3026 * flush currently running tasks.
3028 gcwq->trustee_state = TRUSTEE_IN_CHARGE;
3029 wake_up_all(&gcwq->trustee_wait);
3032 * The original cpu is in the process of dying and may go away
3033 * anytime now. When that happens, we and all workers would
3034 * be migrated to other cpus. Try draining any left work. We
3035 * want to get it over with ASAP - spam rescuers, wake up as
3036 * many idlers as necessary and create new ones till the
3037 * worklist is empty. Note that if the gcwq is frozen, there
3038 * may be frozen works in freezeable cwqs. Don't declare
3039 * completion while frozen.
3041 while (gcwq->nr_workers != gcwq->nr_idle ||
3042 gcwq->flags & GCWQ_FREEZING ||
3043 gcwq->trustee_state == TRUSTEE_IN_CHARGE) {
3046 list_for_each_entry(work, &gcwq->worklist, entry) {
3051 list_for_each_entry(worker, &gcwq->idle_list, entry) {
3054 wake_up_process(worker->task);
3057 if (need_to_create_worker(gcwq)) {
3058 spin_unlock_irq(&gcwq->lock);
3059 worker = create_worker(gcwq, false);
3060 spin_lock_irq(&gcwq->lock);
3062 worker->flags |= WORKER_ROGUE;
3063 start_worker(worker);
3067 /* give a breather */
3068 if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
3073 * Either all works have been scheduled and cpu is down, or
3074 * cpu down has already been canceled. Wait for and butcher
3075 * all workers till we're canceled.
3078 rc = trustee_wait_event(!list_empty(&gcwq->idle_list));
3079 while (!list_empty(&gcwq->idle_list))
3080 destroy_worker(list_first_entry(&gcwq->idle_list,
3081 struct worker, entry));
3082 } while (gcwq->nr_workers && rc >= 0);
3085 * At this point, either draining has completed and no worker
3086 * is left, or cpu down has been canceled or the cpu is being
3087 * brought back up. There shouldn't be any idle one left.
3088 * Tell the remaining busy ones to rebind once it finishes the
3089 * currently scheduled works by scheduling the rebind_work.
3091 WARN_ON(!list_empty(&gcwq->idle_list));
3093 for_each_busy_worker(worker, i, pos, gcwq) {
3094 struct work_struct *rebind_work = &worker->rebind_work;
3097 * Rebind_work may race with future cpu hotplug
3098 * operations. Use a separate flag to mark that
3099 * rebinding is scheduled.
3101 worker->flags |= WORKER_REBIND;
3102 worker->flags &= ~WORKER_ROGUE;
3104 /* queue rebind_work, wq doesn't matter, use the default one */
3105 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
3106 work_data_bits(rebind_work)))
3109 debug_work_activate(rebind_work);
3110 insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
3111 worker->scheduled.next,
3112 work_color_to_flags(WORK_NO_COLOR));
3115 /* relinquish manager role */
3116 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
3118 /* notify completion */
3119 gcwq->trustee = NULL;
3120 gcwq->trustee_state = TRUSTEE_DONE;
3121 wake_up_all(&gcwq->trustee_wait);
3122 spin_unlock_irq(&gcwq->lock);
3127 * wait_trustee_state - wait for trustee to enter the specified state
3128 * @gcwq: gcwq the trustee of interest belongs to
3129 * @state: target state to wait for
3131 * Wait for the trustee to reach @state. DONE is already matched.
3134 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3135 * multiple times. To be used by cpu_callback.
3137 static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
3139 if (!(gcwq->trustee_state == state ||
3140 gcwq->trustee_state == TRUSTEE_DONE)) {
3141 spin_unlock_irq(&gcwq->lock);
3142 __wait_event(gcwq->trustee_wait,
3143 gcwq->trustee_state == state ||
3144 gcwq->trustee_state == TRUSTEE_DONE);
3145 spin_lock_irq(&gcwq->lock);
3149 static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
3150 unsigned long action,
3153 unsigned int cpu = (unsigned long)hcpu;
3154 struct global_cwq *gcwq = get_gcwq(cpu);
3155 struct task_struct *new_trustee = NULL;
3156 struct worker *uninitialized_var(new_worker);
3157 unsigned long flags;
3159 action &= ~CPU_TASKS_FROZEN;
3162 case CPU_DOWN_PREPARE:
3163 new_trustee = kthread_create(trustee_thread, gcwq,
3164 "workqueue_trustee/%d\n", cpu);
3165 if (IS_ERR(new_trustee))
3166 return notifier_from_errno(PTR_ERR(new_trustee));
3167 kthread_bind(new_trustee, cpu);
3169 case CPU_UP_PREPARE:
3170 BUG_ON(gcwq->first_idle);
3171 new_worker = create_worker(gcwq, false);
3174 kthread_stop(new_trustee);
3179 /* some are called w/ irq disabled, don't disturb irq status */
3180 spin_lock_irqsave(&gcwq->lock, flags);
3183 case CPU_DOWN_PREPARE:
3184 /* initialize trustee and tell it to acquire the gcwq */
3185 BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE);
3186 gcwq->trustee = new_trustee;
3187 gcwq->trustee_state = TRUSTEE_START;
3188 wake_up_process(gcwq->trustee);
3189 wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);
3191 case CPU_UP_PREPARE:
3192 BUG_ON(gcwq->first_idle);
3193 gcwq->first_idle = new_worker;
3198 * Before this, the trustee and all workers except for
3199 * the ones which are still executing works from
3200 * before the last CPU down must be on the cpu. After
3201 * this, they'll all be diasporas.
3203 gcwq->flags |= GCWQ_DISASSOCIATED;
3207 gcwq->trustee_state = TRUSTEE_BUTCHER;
3209 case CPU_UP_CANCELED:
3210 destroy_worker(gcwq->first_idle);
3211 gcwq->first_idle = NULL;
3214 case CPU_DOWN_FAILED:
3216 gcwq->flags &= ~GCWQ_DISASSOCIATED;
3217 if (gcwq->trustee_state != TRUSTEE_DONE) {
3218 gcwq->trustee_state = TRUSTEE_RELEASE;
3219 wake_up_process(gcwq->trustee);
3220 wait_trustee_state(gcwq, TRUSTEE_DONE);
3224 * Trustee is done and there might be no worker left.
3225 * Put the first_idle in and request a real manager to
3228 spin_unlock_irq(&gcwq->lock);
3229 kthread_bind(gcwq->first_idle->task, cpu);
3230 spin_lock_irq(&gcwq->lock);
3231 gcwq->flags |= GCWQ_MANAGE_WORKERS;
3232 start_worker(gcwq->first_idle);
3233 gcwq->first_idle = NULL;
3237 spin_unlock_irqrestore(&gcwq->lock, flags);
3239 return notifier_from_errno(0);
3244 struct work_for_cpu {
3245 struct completion completion;
3251 static int do_work_for_cpu(void *_wfc)
3253 struct work_for_cpu *wfc = _wfc;
3254 wfc->ret = wfc->fn(wfc->arg);
3255 complete(&wfc->completion);
3260 * work_on_cpu - run a function in user context on a particular cpu
3261 * @cpu: the cpu to run on
3262 * @fn: the function to run
3263 * @arg: the function arg
3265 * This will return the value @fn returns.
3266 * It is up to the caller to ensure that the cpu doesn't go offline.
3267 * The caller must not hold any locks which would prevent @fn from completing.
3269 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
3271 struct task_struct *sub_thread;
3272 struct work_for_cpu wfc = {
3273 .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
3278 sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
3279 if (IS_ERR(sub_thread))
3280 return PTR_ERR(sub_thread);
3281 kthread_bind(sub_thread, cpu);
3282 wake_up_process(sub_thread);
3283 wait_for_completion(&wfc.completion);
3286 EXPORT_SYMBOL_GPL(work_on_cpu);
3287 #endif /* CONFIG_SMP */
3289 #ifdef CONFIG_FREEZER
3292 * freeze_workqueues_begin - begin freezing workqueues
3294 * Start freezing workqueues. After this function returns, all
3295 * freezeable workqueues will queue new works to their frozen_works
3296 * list instead of gcwq->worklist.
3299 * Grabs and releases workqueue_lock and gcwq->lock's.
3301 void freeze_workqueues_begin(void)
3303 struct workqueue_struct *wq;
3306 spin_lock(&workqueue_lock);
3308 BUG_ON(workqueue_freezing);
3309 workqueue_freezing = true;
3311 for_each_possible_cpu(cpu) {
3312 struct global_cwq *gcwq = get_gcwq(cpu);
3314 spin_lock_irq(&gcwq->lock);
3316 BUG_ON(gcwq->flags & GCWQ_FREEZING);
3317 gcwq->flags |= GCWQ_FREEZING;
3319 list_for_each_entry(wq, &workqueues, list) {
3320 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3322 if (wq->flags & WQ_FREEZEABLE)
3323 cwq->max_active = 0;
3326 spin_unlock_irq(&gcwq->lock);
3329 spin_unlock(&workqueue_lock);
3333 * freeze_workqueues_busy - are freezeable workqueues still busy?
3335 * Check whether freezing is complete. This function must be called
3336 * between freeze_workqueues_begin() and thaw_workqueues().
3339 * Grabs and releases workqueue_lock.
3342 * %true if some freezeable workqueues are still busy. %false if
3343 * freezing is complete.
3345 bool freeze_workqueues_busy(void)
3347 struct workqueue_struct *wq;
3351 spin_lock(&workqueue_lock);
3353 BUG_ON(!workqueue_freezing);
3355 for_each_possible_cpu(cpu) {
3357 * nr_active is monotonically decreasing. It's safe
3358 * to peek without lock.
3360 list_for_each_entry(wq, &workqueues, list) {
3361 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3363 if (!(wq->flags & WQ_FREEZEABLE))
3366 BUG_ON(cwq->nr_active < 0);
3367 if (cwq->nr_active) {
3374 spin_unlock(&workqueue_lock);
3379 * thaw_workqueues - thaw workqueues
3381 * Thaw workqueues. Normal queueing is restored and all collected
3382 * frozen works are transferred to their respective gcwq worklists.
3385 * Grabs and releases workqueue_lock and gcwq->lock's.
3387 void thaw_workqueues(void)
3389 struct workqueue_struct *wq;
3392 spin_lock(&workqueue_lock);
3394 if (!workqueue_freezing)
3397 for_each_possible_cpu(cpu) {
3398 struct global_cwq *gcwq = get_gcwq(cpu);
3400 spin_lock_irq(&gcwq->lock);
3402 BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
3403 gcwq->flags &= ~GCWQ_FREEZING;
3405 list_for_each_entry(wq, &workqueues, list) {
3406 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3408 if (!(wq->flags & WQ_FREEZEABLE))
3411 /* restore max_active and repopulate worklist */
3412 cwq->max_active = wq->saved_max_active;
3414 while (!list_empty(&cwq->delayed_works) &&
3415 cwq->nr_active < cwq->max_active)
3416 cwq_activate_first_delayed(cwq);
3418 /* perform delayed unbind from single cpu if empty */
3419 if (wq->single_cpu == gcwq->cpu &&
3420 !cwq->nr_active && list_empty(&cwq->delayed_works))
3421 cwq_unbind_single_cpu(cwq);
3424 wake_up_worker(gcwq);
3426 spin_unlock_irq(&gcwq->lock);
3429 workqueue_freezing = false;
3431 spin_unlock(&workqueue_lock);
3433 #endif /* CONFIG_FREEZER */
3435 void __init init_workqueues(void)
3441 * The pointer part of work->data is either pointing to the
3442 * cwq or contains the cpu number the work ran last on. Make
3443 * sure cpu number won't overflow into kernel pointer area so
3444 * that they can be distinguished.
3446 BUILD_BUG_ON(NR_CPUS << WORK_STRUCT_FLAG_BITS >= PAGE_OFFSET);
3448 hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
3450 /* initialize gcwqs */
3451 for_each_possible_cpu(cpu) {
3452 struct global_cwq *gcwq = get_gcwq(cpu);
3454 spin_lock_init(&gcwq->lock);
3455 INIT_LIST_HEAD(&gcwq->worklist);
3458 INIT_LIST_HEAD(&gcwq->idle_list);
3459 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
3460 INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
3462 init_timer_deferrable(&gcwq->idle_timer);
3463 gcwq->idle_timer.function = idle_worker_timeout;
3464 gcwq->idle_timer.data = (unsigned long)gcwq;
3466 setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout,
3467 (unsigned long)gcwq);
3469 ida_init(&gcwq->worker_ida);
3471 gcwq->trustee_state = TRUSTEE_DONE;
3472 init_waitqueue_head(&gcwq->trustee_wait);
3475 /* create the initial worker */
3476 for_each_online_cpu(cpu) {
3477 struct global_cwq *gcwq = get_gcwq(cpu);
3478 struct worker *worker;
3480 worker = create_worker(gcwq, true);
3482 spin_lock_irq(&gcwq->lock);
3483 start_worker(worker);
3484 spin_unlock_irq(&gcwq->lock);
3487 system_wq = alloc_workqueue("events", 0, 0);
3488 system_long_wq = alloc_workqueue("events_long", 0, 0);
3489 system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
3490 BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);