intel-gtt: fold i81x-only dcache support into the generic driver
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / workqueue.c
blob90db1bd1a97852e4c547c43d840b2ca624c9a773
1 /*
2 * kernel/workqueue.c - generic async execution with shared worker pool
4 * Copyright (C) 2002 Ingo Molnar
6 * Derived from the taskqueue/keventd code by:
7 * David Woodhouse <dwmw2@infradead.org>
8 * Andrew Morton
9 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
10 * Theodore Ts'o <tytso@mit.edu>
12 * Made to use alloc_percpu by Christoph Lameter.
14 * Copyright (C) 2010 SUSE Linux Products GmbH
15 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
17 * This is the generic async execution mechanism. Work items as are
18 * executed in process context. The worker pool is shared and
19 * automatically managed. There is one worker pool for each CPU and
20 * one extra for works which are better served by workers which are
21 * not bound to any specific CPU.
23 * Please read Documentation/workqueue.txt for details.
26 #include <linux/module.h>
27 #include <linux/kernel.h>
28 #include <linux/sched.h>
29 #include <linux/init.h>
30 #include <linux/signal.h>
31 #include <linux/completion.h>
32 #include <linux/workqueue.h>
33 #include <linux/slab.h>
34 #include <linux/cpu.h>
35 #include <linux/notifier.h>
36 #include <linux/kthread.h>
37 #include <linux/hardirq.h>
38 #include <linux/mempolicy.h>
39 #include <linux/freezer.h>
40 #include <linux/kallsyms.h>
41 #include <linux/debug_locks.h>
42 #include <linux/lockdep.h>
43 #include <linux/idr.h>
45 #include "workqueue_sched.h"
47 enum {
48 /* global_cwq flags */
49 GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
50 GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */
51 GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
52 GCWQ_FREEZING = 1 << 3, /* freeze in progress */
53 GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */
55 /* worker flags */
56 WORKER_STARTED = 1 << 0, /* started */
57 WORKER_DIE = 1 << 1, /* die die die */
58 WORKER_IDLE = 1 << 2, /* is idle */
59 WORKER_PREP = 1 << 3, /* preparing to run works */
60 WORKER_ROGUE = 1 << 4, /* not bound to any cpu */
61 WORKER_REBIND = 1 << 5, /* mom is home, come back */
62 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
63 WORKER_UNBOUND = 1 << 7, /* worker is unbound */
65 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND |
66 WORKER_CPU_INTENSIVE | WORKER_UNBOUND,
68 /* gcwq->trustee_state */
69 TRUSTEE_START = 0, /* start */
70 TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */
71 TRUSTEE_BUTCHER = 2, /* butcher workers */
72 TRUSTEE_RELEASE = 3, /* release workers */
73 TRUSTEE_DONE = 4, /* trustee is done */
75 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
76 BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER,
77 BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1,
79 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
80 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
82 MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */
83 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
84 CREATE_COOLDOWN = HZ, /* time to breath after fail */
85 TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */
88 * Rescue workers are used only on emergencies and shared by
89 * all cpus. Give -20.
91 RESCUER_NICE_LEVEL = -20,
95 * Structure fields follow one of the following exclusion rules.
97 * I: Modifiable by initialization/destruction paths and read-only for
98 * everyone else.
100 * P: Preemption protected. Disabling preemption is enough and should
101 * only be modified and accessed from the local cpu.
103 * L: gcwq->lock protected. Access with gcwq->lock held.
105 * X: During normal operation, modification requires gcwq->lock and
106 * should be done only from local cpu. Either disabling preemption
107 * on local cpu or grabbing gcwq->lock is enough for read access.
108 * If GCWQ_DISASSOCIATED is set, it's identical to L.
110 * F: wq->flush_mutex protected.
112 * W: workqueue_lock protected.
115 struct global_cwq;
118 * The poor guys doing the actual heavy lifting. All on-duty workers
119 * are either serving the manager role, on idle list or on busy hash.
121 struct worker {
122 /* on idle list while idle, on busy hash table while busy */
123 union {
124 struct list_head entry; /* L: while idle */
125 struct hlist_node hentry; /* L: while busy */
128 struct work_struct *current_work; /* L: work being processed */
129 struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
130 struct list_head scheduled; /* L: scheduled works */
131 struct task_struct *task; /* I: worker task */
132 struct global_cwq *gcwq; /* I: the associated gcwq */
133 /* 64 bytes boundary on 64bit, 32 on 32bit */
134 unsigned long last_active; /* L: last active timestamp */
135 unsigned int flags; /* X: flags */
136 int id; /* I: worker id */
137 struct work_struct rebind_work; /* L: rebind worker to cpu */
141 * Global per-cpu workqueue. There's one and only one for each cpu
142 * and all works are queued and processed here regardless of their
143 * target workqueues.
145 struct global_cwq {
146 spinlock_t lock; /* the gcwq lock */
147 struct list_head worklist; /* L: list of pending works */
148 unsigned int cpu; /* I: the associated cpu */
149 unsigned int flags; /* L: GCWQ_* flags */
151 int nr_workers; /* L: total number of workers */
152 int nr_idle; /* L: currently idle ones */
154 /* workers are chained either in the idle_list or busy_hash */
155 struct list_head idle_list; /* X: list of idle workers */
156 struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE];
157 /* L: hash of busy workers */
159 struct timer_list idle_timer; /* L: worker idle timeout */
160 struct timer_list mayday_timer; /* L: SOS timer for dworkers */
162 struct ida worker_ida; /* L: for worker IDs */
164 struct task_struct *trustee; /* L: for gcwq shutdown */
165 unsigned int trustee_state; /* L: trustee state */
166 wait_queue_head_t trustee_wait; /* trustee wait */
167 struct worker *first_idle; /* L: first idle worker */
168 } ____cacheline_aligned_in_smp;
171 * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
172 * work_struct->data are used for flags and thus cwqs need to be
173 * aligned at two's power of the number of flag bits.
175 struct cpu_workqueue_struct {
176 struct global_cwq *gcwq; /* I: the associated gcwq */
177 struct workqueue_struct *wq; /* I: the owning workqueue */
178 int work_color; /* L: current color */
179 int flush_color; /* L: flushing color */
180 int nr_in_flight[WORK_NR_COLORS];
181 /* L: nr of in_flight works */
182 int nr_active; /* L: nr of active works */
183 int max_active; /* L: max active works */
184 struct list_head delayed_works; /* L: delayed works */
188 * Structure used to wait for workqueue flush.
190 struct wq_flusher {
191 struct list_head list; /* F: list of flushers */
192 int flush_color; /* F: flush color waiting for */
193 struct completion done; /* flush completion */
197 * All cpumasks are assumed to be always set on UP and thus can't be
198 * used to determine whether there's something to be done.
200 #ifdef CONFIG_SMP
201 typedef cpumask_var_t mayday_mask_t;
202 #define mayday_test_and_set_cpu(cpu, mask) \
203 cpumask_test_and_set_cpu((cpu), (mask))
204 #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
205 #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
206 #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
207 #define free_mayday_mask(mask) free_cpumask_var((mask))
208 #else
209 typedef unsigned long mayday_mask_t;
210 #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
211 #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
212 #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
213 #define alloc_mayday_mask(maskp, gfp) true
214 #define free_mayday_mask(mask) do { } while (0)
215 #endif
218 * The externally visible workqueue abstraction is an array of
219 * per-CPU workqueues:
221 struct workqueue_struct {
222 unsigned int flags; /* I: WQ_* flags */
223 union {
224 struct cpu_workqueue_struct __percpu *pcpu;
225 struct cpu_workqueue_struct *single;
226 unsigned long v;
227 } cpu_wq; /* I: cwq's */
228 struct list_head list; /* W: list of all workqueues */
230 struct mutex flush_mutex; /* protects wq flushing */
231 int work_color; /* F: current work color */
232 int flush_color; /* F: current flush color */
233 atomic_t nr_cwqs_to_flush; /* flush in progress */
234 struct wq_flusher *first_flusher; /* F: first flusher */
235 struct list_head flusher_queue; /* F: flush waiters */
236 struct list_head flusher_overflow; /* F: flush overflow list */
238 mayday_mask_t mayday_mask; /* cpus requesting rescue */
239 struct worker *rescuer; /* I: rescue worker */
241 int saved_max_active; /* W: saved cwq max_active */
242 const char *name; /* I: workqueue name */
243 #ifdef CONFIG_LOCKDEP
244 struct lockdep_map lockdep_map;
245 #endif
248 struct workqueue_struct *system_wq __read_mostly;
249 struct workqueue_struct *system_long_wq __read_mostly;
250 struct workqueue_struct *system_nrt_wq __read_mostly;
251 struct workqueue_struct *system_unbound_wq __read_mostly;
252 EXPORT_SYMBOL_GPL(system_wq);
253 EXPORT_SYMBOL_GPL(system_long_wq);
254 EXPORT_SYMBOL_GPL(system_nrt_wq);
255 EXPORT_SYMBOL_GPL(system_unbound_wq);
257 #define CREATE_TRACE_POINTS
258 #include <trace/events/workqueue.h>
260 #define for_each_busy_worker(worker, i, pos, gcwq) \
261 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
262 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
264 static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
265 unsigned int sw)
267 if (cpu < nr_cpu_ids) {
268 if (sw & 1) {
269 cpu = cpumask_next(cpu, mask);
270 if (cpu < nr_cpu_ids)
271 return cpu;
273 if (sw & 2)
274 return WORK_CPU_UNBOUND;
276 return WORK_CPU_NONE;
279 static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
280 struct workqueue_struct *wq)
282 return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
286 * CPU iterators
288 * An extra gcwq is defined for an invalid cpu number
289 * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
290 * specific CPU. The following iterators are similar to
291 * for_each_*_cpu() iterators but also considers the unbound gcwq.
293 * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
294 * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
295 * for_each_cwq_cpu() : possible CPUs for bound workqueues,
296 * WORK_CPU_UNBOUND for unbound workqueues
298 #define for_each_gcwq_cpu(cpu) \
299 for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
300 (cpu) < WORK_CPU_NONE; \
301 (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
303 #define for_each_online_gcwq_cpu(cpu) \
304 for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
305 (cpu) < WORK_CPU_NONE; \
306 (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
308 #define for_each_cwq_cpu(cpu, wq) \
309 for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
310 (cpu) < WORK_CPU_NONE; \
311 (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
313 #ifdef CONFIG_DEBUG_OBJECTS_WORK
315 static struct debug_obj_descr work_debug_descr;
318 * fixup_init is called when:
319 * - an active object is initialized
321 static int work_fixup_init(void *addr, enum debug_obj_state state)
323 struct work_struct *work = addr;
325 switch (state) {
326 case ODEBUG_STATE_ACTIVE:
327 cancel_work_sync(work);
328 debug_object_init(work, &work_debug_descr);
329 return 1;
330 default:
331 return 0;
336 * fixup_activate is called when:
337 * - an active object is activated
338 * - an unknown object is activated (might be a statically initialized object)
340 static int work_fixup_activate(void *addr, enum debug_obj_state state)
342 struct work_struct *work = addr;
344 switch (state) {
346 case ODEBUG_STATE_NOTAVAILABLE:
348 * This is not really a fixup. The work struct was
349 * statically initialized. We just make sure that it
350 * is tracked in the object tracker.
352 if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
353 debug_object_init(work, &work_debug_descr);
354 debug_object_activate(work, &work_debug_descr);
355 return 0;
357 WARN_ON_ONCE(1);
358 return 0;
360 case ODEBUG_STATE_ACTIVE:
361 WARN_ON(1);
363 default:
364 return 0;
369 * fixup_free is called when:
370 * - an active object is freed
372 static int work_fixup_free(void *addr, enum debug_obj_state state)
374 struct work_struct *work = addr;
376 switch (state) {
377 case ODEBUG_STATE_ACTIVE:
378 cancel_work_sync(work);
379 debug_object_free(work, &work_debug_descr);
380 return 1;
381 default:
382 return 0;
386 static struct debug_obj_descr work_debug_descr = {
387 .name = "work_struct",
388 .fixup_init = work_fixup_init,
389 .fixup_activate = work_fixup_activate,
390 .fixup_free = work_fixup_free,
393 static inline void debug_work_activate(struct work_struct *work)
395 debug_object_activate(work, &work_debug_descr);
398 static inline void debug_work_deactivate(struct work_struct *work)
400 debug_object_deactivate(work, &work_debug_descr);
403 void __init_work(struct work_struct *work, int onstack)
405 if (onstack)
406 debug_object_init_on_stack(work, &work_debug_descr);
407 else
408 debug_object_init(work, &work_debug_descr);
410 EXPORT_SYMBOL_GPL(__init_work);
412 void destroy_work_on_stack(struct work_struct *work)
414 debug_object_free(work, &work_debug_descr);
416 EXPORT_SYMBOL_GPL(destroy_work_on_stack);
418 #else
419 static inline void debug_work_activate(struct work_struct *work) { }
420 static inline void debug_work_deactivate(struct work_struct *work) { }
421 #endif
423 /* Serializes the accesses to the list of workqueues. */
424 static DEFINE_SPINLOCK(workqueue_lock);
425 static LIST_HEAD(workqueues);
426 static bool workqueue_freezing; /* W: have wqs started freezing? */
429 * The almighty global cpu workqueues. nr_running is the only field
430 * which is expected to be used frequently by other cpus via
431 * try_to_wake_up(). Put it in a separate cacheline.
433 static DEFINE_PER_CPU(struct global_cwq, global_cwq);
434 static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);
437 * Global cpu workqueue and nr_running counter for unbound gcwq. The
438 * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
439 * workers have WORKER_UNBOUND set.
441 static struct global_cwq unbound_global_cwq;
442 static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */
444 static int worker_thread(void *__worker);
446 static struct global_cwq *get_gcwq(unsigned int cpu)
448 if (cpu != WORK_CPU_UNBOUND)
449 return &per_cpu(global_cwq, cpu);
450 else
451 return &unbound_global_cwq;
454 static atomic_t *get_gcwq_nr_running(unsigned int cpu)
456 if (cpu != WORK_CPU_UNBOUND)
457 return &per_cpu(gcwq_nr_running, cpu);
458 else
459 return &unbound_gcwq_nr_running;
462 static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
463 struct workqueue_struct *wq)
465 if (!(wq->flags & WQ_UNBOUND)) {
466 if (likely(cpu < nr_cpu_ids)) {
467 #ifdef CONFIG_SMP
468 return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
469 #else
470 return wq->cpu_wq.single;
471 #endif
473 } else if (likely(cpu == WORK_CPU_UNBOUND))
474 return wq->cpu_wq.single;
475 return NULL;
478 static unsigned int work_color_to_flags(int color)
480 return color << WORK_STRUCT_COLOR_SHIFT;
483 static int get_work_color(struct work_struct *work)
485 return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
486 ((1 << WORK_STRUCT_COLOR_BITS) - 1);
489 static int work_next_color(int color)
491 return (color + 1) % WORK_NR_COLORS;
495 * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
496 * work is on queue. Once execution starts, WORK_STRUCT_CWQ is
497 * cleared and the work data contains the cpu number it was last on.
499 * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
500 * cwq, cpu or clear work->data. These functions should only be
501 * called while the work is owned - ie. while the PENDING bit is set.
503 * get_work_[g]cwq() can be used to obtain the gcwq or cwq
504 * corresponding to a work. gcwq is available once the work has been
505 * queued anywhere after initialization. cwq is available only from
506 * queueing until execution starts.
508 static inline void set_work_data(struct work_struct *work, unsigned long data,
509 unsigned long flags)
511 BUG_ON(!work_pending(work));
512 atomic_long_set(&work->data, data | flags | work_static(work));
515 static void set_work_cwq(struct work_struct *work,
516 struct cpu_workqueue_struct *cwq,
517 unsigned long extra_flags)
519 set_work_data(work, (unsigned long)cwq,
520 WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
523 static void set_work_cpu(struct work_struct *work, unsigned int cpu)
525 set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING);
528 static void clear_work_data(struct work_struct *work)
530 set_work_data(work, WORK_STRUCT_NO_CPU, 0);
533 static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
535 unsigned long data = atomic_long_read(&work->data);
537 if (data & WORK_STRUCT_CWQ)
538 return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
539 else
540 return NULL;
543 static struct global_cwq *get_work_gcwq(struct work_struct *work)
545 unsigned long data = atomic_long_read(&work->data);
546 unsigned int cpu;
548 if (data & WORK_STRUCT_CWQ)
549 return ((struct cpu_workqueue_struct *)
550 (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq;
552 cpu = data >> WORK_STRUCT_FLAG_BITS;
553 if (cpu == WORK_CPU_NONE)
554 return NULL;
556 BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND);
557 return get_gcwq(cpu);
561 * Policy functions. These define the policies on how the global
562 * worker pool is managed. Unless noted otherwise, these functions
563 * assume that they're being called with gcwq->lock held.
566 static bool __need_more_worker(struct global_cwq *gcwq)
568 return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) ||
569 gcwq->flags & GCWQ_HIGHPRI_PENDING;
573 * Need to wake up a worker? Called from anything but currently
574 * running workers.
576 static bool need_more_worker(struct global_cwq *gcwq)
578 return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq);
581 /* Can I start working? Called from busy but !running workers. */
582 static bool may_start_working(struct global_cwq *gcwq)
584 return gcwq->nr_idle;
587 /* Do I need to keep working? Called from currently running workers. */
588 static bool keep_working(struct global_cwq *gcwq)
590 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
592 return !list_empty(&gcwq->worklist) &&
593 (atomic_read(nr_running) <= 1 ||
594 gcwq->flags & GCWQ_HIGHPRI_PENDING);
597 /* Do we need a new worker? Called from manager. */
598 static bool need_to_create_worker(struct global_cwq *gcwq)
600 return need_more_worker(gcwq) && !may_start_working(gcwq);
603 /* Do I need to be the manager? */
604 static bool need_to_manage_workers(struct global_cwq *gcwq)
606 return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS;
609 /* Do we have too many workers and should some go away? */
610 static bool too_many_workers(struct global_cwq *gcwq)
612 bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS;
613 int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */
614 int nr_busy = gcwq->nr_workers - nr_idle;
616 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
620 * Wake up functions.
623 /* Return the first worker. Safe with preemption disabled */
624 static struct worker *first_worker(struct global_cwq *gcwq)
626 if (unlikely(list_empty(&gcwq->idle_list)))
627 return NULL;
629 return list_first_entry(&gcwq->idle_list, struct worker, entry);
633 * wake_up_worker - wake up an idle worker
634 * @gcwq: gcwq to wake worker for
636 * Wake up the first idle worker of @gcwq.
638 * CONTEXT:
639 * spin_lock_irq(gcwq->lock).
641 static void wake_up_worker(struct global_cwq *gcwq)
643 struct worker *worker = first_worker(gcwq);
645 if (likely(worker))
646 wake_up_process(worker->task);
650 * wq_worker_waking_up - a worker is waking up
651 * @task: task waking up
652 * @cpu: CPU @task is waking up to
654 * This function is called during try_to_wake_up() when a worker is
655 * being awoken.
657 * CONTEXT:
658 * spin_lock_irq(rq->lock)
660 void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
662 struct worker *worker = kthread_data(task);
664 if (likely(!(worker->flags & WORKER_NOT_RUNNING)))
665 atomic_inc(get_gcwq_nr_running(cpu));
669 * wq_worker_sleeping - a worker is going to sleep
670 * @task: task going to sleep
671 * @cpu: CPU in question, must be the current CPU number
673 * This function is called during schedule() when a busy worker is
674 * going to sleep. Worker on the same cpu can be woken up by
675 * returning pointer to its task.
677 * CONTEXT:
678 * spin_lock_irq(rq->lock)
680 * RETURNS:
681 * Worker task on @cpu to wake up, %NULL if none.
683 struct task_struct *wq_worker_sleeping(struct task_struct *task,
684 unsigned int cpu)
686 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
687 struct global_cwq *gcwq = get_gcwq(cpu);
688 atomic_t *nr_running = get_gcwq_nr_running(cpu);
690 if (unlikely(worker->flags & WORKER_NOT_RUNNING))
691 return NULL;
693 /* this can only happen on the local cpu */
694 BUG_ON(cpu != raw_smp_processor_id());
697 * The counterpart of the following dec_and_test, implied mb,
698 * worklist not empty test sequence is in insert_work().
699 * Please read comment there.
701 * NOT_RUNNING is clear. This means that trustee is not in
702 * charge and we're running on the local cpu w/ rq lock held
703 * and preemption disabled, which in turn means that none else
704 * could be manipulating idle_list, so dereferencing idle_list
705 * without gcwq lock is safe.
707 if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist))
708 to_wakeup = first_worker(gcwq);
709 return to_wakeup ? to_wakeup->task : NULL;
713 * worker_set_flags - set worker flags and adjust nr_running accordingly
714 * @worker: self
715 * @flags: flags to set
716 * @wakeup: wakeup an idle worker if necessary
718 * Set @flags in @worker->flags and adjust nr_running accordingly. If
719 * nr_running becomes zero and @wakeup is %true, an idle worker is
720 * woken up.
722 * CONTEXT:
723 * spin_lock_irq(gcwq->lock)
725 static inline void worker_set_flags(struct worker *worker, unsigned int flags,
726 bool wakeup)
728 struct global_cwq *gcwq = worker->gcwq;
730 WARN_ON_ONCE(worker->task != current);
733 * If transitioning into NOT_RUNNING, adjust nr_running and
734 * wake up an idle worker as necessary if requested by
735 * @wakeup.
737 if ((flags & WORKER_NOT_RUNNING) &&
738 !(worker->flags & WORKER_NOT_RUNNING)) {
739 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
741 if (wakeup) {
742 if (atomic_dec_and_test(nr_running) &&
743 !list_empty(&gcwq->worklist))
744 wake_up_worker(gcwq);
745 } else
746 atomic_dec(nr_running);
749 worker->flags |= flags;
753 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
754 * @worker: self
755 * @flags: flags to clear
757 * Clear @flags in @worker->flags and adjust nr_running accordingly.
759 * CONTEXT:
760 * spin_lock_irq(gcwq->lock)
762 static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
764 struct global_cwq *gcwq = worker->gcwq;
765 unsigned int oflags = worker->flags;
767 WARN_ON_ONCE(worker->task != current);
769 worker->flags &= ~flags;
771 /* if transitioning out of NOT_RUNNING, increment nr_running */
772 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
773 if (!(worker->flags & WORKER_NOT_RUNNING))
774 atomic_inc(get_gcwq_nr_running(gcwq->cpu));
778 * busy_worker_head - return the busy hash head for a work
779 * @gcwq: gcwq of interest
780 * @work: work to be hashed
782 * Return hash head of @gcwq for @work.
784 * CONTEXT:
785 * spin_lock_irq(gcwq->lock).
787 * RETURNS:
788 * Pointer to the hash head.
790 static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
791 struct work_struct *work)
793 const int base_shift = ilog2(sizeof(struct work_struct));
794 unsigned long v = (unsigned long)work;
796 /* simple shift and fold hash, do we need something better? */
797 v >>= base_shift;
798 v += v >> BUSY_WORKER_HASH_ORDER;
799 v &= BUSY_WORKER_HASH_MASK;
801 return &gcwq->busy_hash[v];
805 * __find_worker_executing_work - find worker which is executing a work
806 * @gcwq: gcwq of interest
807 * @bwh: hash head as returned by busy_worker_head()
808 * @work: work to find worker for
810 * Find a worker which is executing @work on @gcwq. @bwh should be
811 * the hash head obtained by calling busy_worker_head() with the same
812 * work.
814 * CONTEXT:
815 * spin_lock_irq(gcwq->lock).
817 * RETURNS:
818 * Pointer to worker which is executing @work if found, NULL
819 * otherwise.
821 static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,
822 struct hlist_head *bwh,
823 struct work_struct *work)
825 struct worker *worker;
826 struct hlist_node *tmp;
828 hlist_for_each_entry(worker, tmp, bwh, hentry)
829 if (worker->current_work == work)
830 return worker;
831 return NULL;
835 * find_worker_executing_work - find worker which is executing a work
836 * @gcwq: gcwq of interest
837 * @work: work to find worker for
839 * Find a worker which is executing @work on @gcwq. This function is
840 * identical to __find_worker_executing_work() except that this
841 * function calculates @bwh itself.
843 * CONTEXT:
844 * spin_lock_irq(gcwq->lock).
846 * RETURNS:
847 * Pointer to worker which is executing @work if found, NULL
848 * otherwise.
850 static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
851 struct work_struct *work)
853 return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),
854 work);
858 * gcwq_determine_ins_pos - find insertion position
859 * @gcwq: gcwq of interest
860 * @cwq: cwq a work is being queued for
862 * A work for @cwq is about to be queued on @gcwq, determine insertion
863 * position for the work. If @cwq is for HIGHPRI wq, the work is
864 * queued at the head of the queue but in FIFO order with respect to
865 * other HIGHPRI works; otherwise, at the end of the queue. This
866 * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that
867 * there are HIGHPRI works pending.
869 * CONTEXT:
870 * spin_lock_irq(gcwq->lock).
872 * RETURNS:
873 * Pointer to inserstion position.
875 static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq,
876 struct cpu_workqueue_struct *cwq)
878 struct work_struct *twork;
880 if (likely(!(cwq->wq->flags & WQ_HIGHPRI)))
881 return &gcwq->worklist;
883 list_for_each_entry(twork, &gcwq->worklist, entry) {
884 struct cpu_workqueue_struct *tcwq = get_work_cwq(twork);
886 if (!(tcwq->wq->flags & WQ_HIGHPRI))
887 break;
890 gcwq->flags |= GCWQ_HIGHPRI_PENDING;
891 return &twork->entry;
895 * insert_work - insert a work into gcwq
896 * @cwq: cwq @work belongs to
897 * @work: work to insert
898 * @head: insertion point
899 * @extra_flags: extra WORK_STRUCT_* flags to set
901 * Insert @work which belongs to @cwq into @gcwq after @head.
902 * @extra_flags is or'd to work_struct flags.
904 * CONTEXT:
905 * spin_lock_irq(gcwq->lock).
907 static void insert_work(struct cpu_workqueue_struct *cwq,
908 struct work_struct *work, struct list_head *head,
909 unsigned int extra_flags)
911 struct global_cwq *gcwq = cwq->gcwq;
913 /* we own @work, set data and link */
914 set_work_cwq(work, cwq, extra_flags);
917 * Ensure that we get the right work->data if we see the
918 * result of list_add() below, see try_to_grab_pending().
920 smp_wmb();
922 list_add_tail(&work->entry, head);
925 * Ensure either worker_sched_deactivated() sees the above
926 * list_add_tail() or we see zero nr_running to avoid workers
927 * lying around lazily while there are works to be processed.
929 smp_mb();
931 if (__need_more_worker(gcwq))
932 wake_up_worker(gcwq);
935 static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
936 struct work_struct *work)
938 struct global_cwq *gcwq;
939 struct cpu_workqueue_struct *cwq;
940 struct list_head *worklist;
941 unsigned int work_flags;
942 unsigned long flags;
944 debug_work_activate(work);
946 if (WARN_ON_ONCE(wq->flags & WQ_DYING))
947 return;
949 /* determine gcwq to use */
950 if (!(wq->flags & WQ_UNBOUND)) {
951 struct global_cwq *last_gcwq;
953 if (unlikely(cpu == WORK_CPU_UNBOUND))
954 cpu = raw_smp_processor_id();
957 * It's multi cpu. If @wq is non-reentrant and @work
958 * was previously on a different cpu, it might still
959 * be running there, in which case the work needs to
960 * be queued on that cpu to guarantee non-reentrance.
962 gcwq = get_gcwq(cpu);
963 if (wq->flags & WQ_NON_REENTRANT &&
964 (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) {
965 struct worker *worker;
967 spin_lock_irqsave(&last_gcwq->lock, flags);
969 worker = find_worker_executing_work(last_gcwq, work);
971 if (worker && worker->current_cwq->wq == wq)
972 gcwq = last_gcwq;
973 else {
974 /* meh... not running there, queue here */
975 spin_unlock_irqrestore(&last_gcwq->lock, flags);
976 spin_lock_irqsave(&gcwq->lock, flags);
978 } else
979 spin_lock_irqsave(&gcwq->lock, flags);
980 } else {
981 gcwq = get_gcwq(WORK_CPU_UNBOUND);
982 spin_lock_irqsave(&gcwq->lock, flags);
985 /* gcwq determined, get cwq and queue */
986 cwq = get_cwq(gcwq->cpu, wq);
987 trace_workqueue_queue_work(cpu, cwq, work);
989 BUG_ON(!list_empty(&work->entry));
991 cwq->nr_in_flight[cwq->work_color]++;
992 work_flags = work_color_to_flags(cwq->work_color);
994 if (likely(cwq->nr_active < cwq->max_active)) {
995 trace_workqueue_activate_work(work);
996 cwq->nr_active++;
997 worklist = gcwq_determine_ins_pos(gcwq, cwq);
998 } else {
999 work_flags |= WORK_STRUCT_DELAYED;
1000 worklist = &cwq->delayed_works;
1003 insert_work(cwq, work, worklist, work_flags);
1005 spin_unlock_irqrestore(&gcwq->lock, flags);
1009 * queue_work - queue work on a workqueue
1010 * @wq: workqueue to use
1011 * @work: work to queue
1013 * Returns 0 if @work was already on a queue, non-zero otherwise.
1015 * We queue the work to the CPU on which it was submitted, but if the CPU dies
1016 * it can be processed by another CPU.
1018 int queue_work(struct workqueue_struct *wq, struct work_struct *work)
1020 int ret;
1022 ret = queue_work_on(get_cpu(), wq, work);
1023 put_cpu();
1025 return ret;
1027 EXPORT_SYMBOL_GPL(queue_work);
1030 * queue_work_on - queue work on specific cpu
1031 * @cpu: CPU number to execute work on
1032 * @wq: workqueue to use
1033 * @work: work to queue
1035 * Returns 0 if @work was already on a queue, non-zero otherwise.
1037 * We queue the work to a specific CPU, the caller must ensure it
1038 * can't go away.
1041 queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
1043 int ret = 0;
1045 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1046 __queue_work(cpu, wq, work);
1047 ret = 1;
1049 return ret;
1051 EXPORT_SYMBOL_GPL(queue_work_on);
1053 static void delayed_work_timer_fn(unsigned long __data)
1055 struct delayed_work *dwork = (struct delayed_work *)__data;
1056 struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
1058 __queue_work(smp_processor_id(), cwq->wq, &dwork->work);
1062 * queue_delayed_work - queue work on a workqueue after delay
1063 * @wq: workqueue to use
1064 * @dwork: delayable work to queue
1065 * @delay: number of jiffies to wait before queueing
1067 * Returns 0 if @work was already on a queue, non-zero otherwise.
1069 int queue_delayed_work(struct workqueue_struct *wq,
1070 struct delayed_work *dwork, unsigned long delay)
1072 if (delay == 0)
1073 return queue_work(wq, &dwork->work);
1075 return queue_delayed_work_on(-1, wq, dwork, delay);
1077 EXPORT_SYMBOL_GPL(queue_delayed_work);
1080 * queue_delayed_work_on - queue work on specific CPU after delay
1081 * @cpu: CPU number to execute work on
1082 * @wq: workqueue to use
1083 * @dwork: work to queue
1084 * @delay: number of jiffies to wait before queueing
1086 * Returns 0 if @work was already on a queue, non-zero otherwise.
1088 int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1089 struct delayed_work *dwork, unsigned long delay)
1091 int ret = 0;
1092 struct timer_list *timer = &dwork->timer;
1093 struct work_struct *work = &dwork->work;
1095 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1096 unsigned int lcpu;
1098 BUG_ON(timer_pending(timer));
1099 BUG_ON(!list_empty(&work->entry));
1101 timer_stats_timer_set_start_info(&dwork->timer);
1104 * This stores cwq for the moment, for the timer_fn.
1105 * Note that the work's gcwq is preserved to allow
1106 * reentrance detection for delayed works.
1108 if (!(wq->flags & WQ_UNBOUND)) {
1109 struct global_cwq *gcwq = get_work_gcwq(work);
1111 if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND)
1112 lcpu = gcwq->cpu;
1113 else
1114 lcpu = raw_smp_processor_id();
1115 } else
1116 lcpu = WORK_CPU_UNBOUND;
1118 set_work_cwq(work, get_cwq(lcpu, wq), 0);
1120 timer->expires = jiffies + delay;
1121 timer->data = (unsigned long)dwork;
1122 timer->function = delayed_work_timer_fn;
1124 if (unlikely(cpu >= 0))
1125 add_timer_on(timer, cpu);
1126 else
1127 add_timer(timer);
1128 ret = 1;
1130 return ret;
1132 EXPORT_SYMBOL_GPL(queue_delayed_work_on);
1135 * worker_enter_idle - enter idle state
1136 * @worker: worker which is entering idle state
1138 * @worker is entering idle state. Update stats and idle timer if
1139 * necessary.
1141 * LOCKING:
1142 * spin_lock_irq(gcwq->lock).
1144 static void worker_enter_idle(struct worker *worker)
1146 struct global_cwq *gcwq = worker->gcwq;
1148 BUG_ON(worker->flags & WORKER_IDLE);
1149 BUG_ON(!list_empty(&worker->entry) &&
1150 (worker->hentry.next || worker->hentry.pprev));
1152 /* can't use worker_set_flags(), also called from start_worker() */
1153 worker->flags |= WORKER_IDLE;
1154 gcwq->nr_idle++;
1155 worker->last_active = jiffies;
1157 /* idle_list is LIFO */
1158 list_add(&worker->entry, &gcwq->idle_list);
1160 if (likely(!(worker->flags & WORKER_ROGUE))) {
1161 if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer))
1162 mod_timer(&gcwq->idle_timer,
1163 jiffies + IDLE_WORKER_TIMEOUT);
1164 } else
1165 wake_up_all(&gcwq->trustee_wait);
1167 /* sanity check nr_running */
1168 WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle &&
1169 atomic_read(get_gcwq_nr_running(gcwq->cpu)));
1173 * worker_leave_idle - leave idle state
1174 * @worker: worker which is leaving idle state
1176 * @worker is leaving idle state. Update stats.
1178 * LOCKING:
1179 * spin_lock_irq(gcwq->lock).
1181 static void worker_leave_idle(struct worker *worker)
1183 struct global_cwq *gcwq = worker->gcwq;
1185 BUG_ON(!(worker->flags & WORKER_IDLE));
1186 worker_clr_flags(worker, WORKER_IDLE);
1187 gcwq->nr_idle--;
1188 list_del_init(&worker->entry);
1192 * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
1193 * @worker: self
1195 * Works which are scheduled while the cpu is online must at least be
1196 * scheduled to a worker which is bound to the cpu so that if they are
1197 * flushed from cpu callbacks while cpu is going down, they are
1198 * guaranteed to execute on the cpu.
1200 * This function is to be used by rogue workers and rescuers to bind
1201 * themselves to the target cpu and may race with cpu going down or
1202 * coming online. kthread_bind() can't be used because it may put the
1203 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1204 * verbatim as it's best effort and blocking and gcwq may be
1205 * [dis]associated in the meantime.
1207 * This function tries set_cpus_allowed() and locks gcwq and verifies
1208 * the binding against GCWQ_DISASSOCIATED which is set during
1209 * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters
1210 * idle state or fetches works without dropping lock, it can guarantee
1211 * the scheduling requirement described in the first paragraph.
1213 * CONTEXT:
1214 * Might sleep. Called without any lock but returns with gcwq->lock
1215 * held.
1217 * RETURNS:
1218 * %true if the associated gcwq is online (@worker is successfully
1219 * bound), %false if offline.
1221 static bool worker_maybe_bind_and_lock(struct worker *worker)
1222 __acquires(&gcwq->lock)
1224 struct global_cwq *gcwq = worker->gcwq;
1225 struct task_struct *task = worker->task;
1227 while (true) {
1229 * The following call may fail, succeed or succeed
1230 * without actually migrating the task to the cpu if
1231 * it races with cpu hotunplug operation. Verify
1232 * against GCWQ_DISASSOCIATED.
1234 if (!(gcwq->flags & GCWQ_DISASSOCIATED))
1235 set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
1237 spin_lock_irq(&gcwq->lock);
1238 if (gcwq->flags & GCWQ_DISASSOCIATED)
1239 return false;
1240 if (task_cpu(task) == gcwq->cpu &&
1241 cpumask_equal(&current->cpus_allowed,
1242 get_cpu_mask(gcwq->cpu)))
1243 return true;
1244 spin_unlock_irq(&gcwq->lock);
1246 /* CPU has come up inbetween, retry migration */
1247 cpu_relax();
1252 * Function for worker->rebind_work used to rebind rogue busy workers
1253 * to the associated cpu which is coming back online. This is
1254 * scheduled by cpu up but can race with other cpu hotplug operations
1255 * and may be executed twice without intervening cpu down.
1257 static void worker_rebind_fn(struct work_struct *work)
1259 struct worker *worker = container_of(work, struct worker, rebind_work);
1260 struct global_cwq *gcwq = worker->gcwq;
1262 if (worker_maybe_bind_and_lock(worker))
1263 worker_clr_flags(worker, WORKER_REBIND);
1265 spin_unlock_irq(&gcwq->lock);
1268 static struct worker *alloc_worker(void)
1270 struct worker *worker;
1272 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
1273 if (worker) {
1274 INIT_LIST_HEAD(&worker->entry);
1275 INIT_LIST_HEAD(&worker->scheduled);
1276 INIT_WORK(&worker->rebind_work, worker_rebind_fn);
1277 /* on creation a worker is in !idle && prep state */
1278 worker->flags = WORKER_PREP;
1280 return worker;
1284 * create_worker - create a new workqueue worker
1285 * @gcwq: gcwq the new worker will belong to
1286 * @bind: whether to set affinity to @cpu or not
1288 * Create a new worker which is bound to @gcwq. The returned worker
1289 * can be started by calling start_worker() or destroyed using
1290 * destroy_worker().
1292 * CONTEXT:
1293 * Might sleep. Does GFP_KERNEL allocations.
1295 * RETURNS:
1296 * Pointer to the newly created worker.
1298 static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
1300 bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND;
1301 struct worker *worker = NULL;
1302 int id = -1;
1304 spin_lock_irq(&gcwq->lock);
1305 while (ida_get_new(&gcwq->worker_ida, &id)) {
1306 spin_unlock_irq(&gcwq->lock);
1307 if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL))
1308 goto fail;
1309 spin_lock_irq(&gcwq->lock);
1311 spin_unlock_irq(&gcwq->lock);
1313 worker = alloc_worker();
1314 if (!worker)
1315 goto fail;
1317 worker->gcwq = gcwq;
1318 worker->id = id;
1320 if (!on_unbound_cpu)
1321 worker->task = kthread_create(worker_thread, worker,
1322 "kworker/%u:%d", gcwq->cpu, id);
1323 else
1324 worker->task = kthread_create(worker_thread, worker,
1325 "kworker/u:%d", id);
1326 if (IS_ERR(worker->task))
1327 goto fail;
1330 * A rogue worker will become a regular one if CPU comes
1331 * online later on. Make sure every worker has
1332 * PF_THREAD_BOUND set.
1334 if (bind && !on_unbound_cpu)
1335 kthread_bind(worker->task, gcwq->cpu);
1336 else {
1337 worker->task->flags |= PF_THREAD_BOUND;
1338 if (on_unbound_cpu)
1339 worker->flags |= WORKER_UNBOUND;
1342 return worker;
1343 fail:
1344 if (id >= 0) {
1345 spin_lock_irq(&gcwq->lock);
1346 ida_remove(&gcwq->worker_ida, id);
1347 spin_unlock_irq(&gcwq->lock);
1349 kfree(worker);
1350 return NULL;
1354 * start_worker - start a newly created worker
1355 * @worker: worker to start
1357 * Make the gcwq aware of @worker and start it.
1359 * CONTEXT:
1360 * spin_lock_irq(gcwq->lock).
1362 static void start_worker(struct worker *worker)
1364 worker->flags |= WORKER_STARTED;
1365 worker->gcwq->nr_workers++;
1366 worker_enter_idle(worker);
1367 wake_up_process(worker->task);
1371 * destroy_worker - destroy a workqueue worker
1372 * @worker: worker to be destroyed
1374 * Destroy @worker and adjust @gcwq stats accordingly.
1376 * CONTEXT:
1377 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1379 static void destroy_worker(struct worker *worker)
1381 struct global_cwq *gcwq = worker->gcwq;
1382 int id = worker->id;
1384 /* sanity check frenzy */
1385 BUG_ON(worker->current_work);
1386 BUG_ON(!list_empty(&worker->scheduled));
1388 if (worker->flags & WORKER_STARTED)
1389 gcwq->nr_workers--;
1390 if (worker->flags & WORKER_IDLE)
1391 gcwq->nr_idle--;
1393 list_del_init(&worker->entry);
1394 worker->flags |= WORKER_DIE;
1396 spin_unlock_irq(&gcwq->lock);
1398 kthread_stop(worker->task);
1399 kfree(worker);
1401 spin_lock_irq(&gcwq->lock);
1402 ida_remove(&gcwq->worker_ida, id);
1405 static void idle_worker_timeout(unsigned long __gcwq)
1407 struct global_cwq *gcwq = (void *)__gcwq;
1409 spin_lock_irq(&gcwq->lock);
1411 if (too_many_workers(gcwq)) {
1412 struct worker *worker;
1413 unsigned long expires;
1415 /* idle_list is kept in LIFO order, check the last one */
1416 worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
1417 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1419 if (time_before(jiffies, expires))
1420 mod_timer(&gcwq->idle_timer, expires);
1421 else {
1422 /* it's been idle for too long, wake up manager */
1423 gcwq->flags |= GCWQ_MANAGE_WORKERS;
1424 wake_up_worker(gcwq);
1428 spin_unlock_irq(&gcwq->lock);
1431 static bool send_mayday(struct work_struct *work)
1433 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1434 struct workqueue_struct *wq = cwq->wq;
1435 unsigned int cpu;
1437 if (!(wq->flags & WQ_RESCUER))
1438 return false;
1440 /* mayday mayday mayday */
1441 cpu = cwq->gcwq->cpu;
1442 /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
1443 if (cpu == WORK_CPU_UNBOUND)
1444 cpu = 0;
1445 if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask))
1446 wake_up_process(wq->rescuer->task);
1447 return true;
1450 static void gcwq_mayday_timeout(unsigned long __gcwq)
1452 struct global_cwq *gcwq = (void *)__gcwq;
1453 struct work_struct *work;
1455 spin_lock_irq(&gcwq->lock);
1457 if (need_to_create_worker(gcwq)) {
1459 * We've been trying to create a new worker but
1460 * haven't been successful. We might be hitting an
1461 * allocation deadlock. Send distress signals to
1462 * rescuers.
1464 list_for_each_entry(work, &gcwq->worklist, entry)
1465 send_mayday(work);
1468 spin_unlock_irq(&gcwq->lock);
1470 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL);
1474 * maybe_create_worker - create a new worker if necessary
1475 * @gcwq: gcwq to create a new worker for
1477 * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to
1478 * have at least one idle worker on return from this function. If
1479 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1480 * sent to all rescuers with works scheduled on @gcwq to resolve
1481 * possible allocation deadlock.
1483 * On return, need_to_create_worker() is guaranteed to be false and
1484 * may_start_working() true.
1486 * LOCKING:
1487 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1488 * multiple times. Does GFP_KERNEL allocations. Called only from
1489 * manager.
1491 * RETURNS:
1492 * false if no action was taken and gcwq->lock stayed locked, true
1493 * otherwise.
1495 static bool maybe_create_worker(struct global_cwq *gcwq)
1496 __releases(&gcwq->lock)
1497 __acquires(&gcwq->lock)
1499 if (!need_to_create_worker(gcwq))
1500 return false;
1501 restart:
1502 spin_unlock_irq(&gcwq->lock);
1504 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1505 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
1507 while (true) {
1508 struct worker *worker;
1510 worker = create_worker(gcwq, true);
1511 if (worker) {
1512 del_timer_sync(&gcwq->mayday_timer);
1513 spin_lock_irq(&gcwq->lock);
1514 start_worker(worker);
1515 BUG_ON(need_to_create_worker(gcwq));
1516 return true;
1519 if (!need_to_create_worker(gcwq))
1520 break;
1522 __set_current_state(TASK_INTERRUPTIBLE);
1523 schedule_timeout(CREATE_COOLDOWN);
1525 if (!need_to_create_worker(gcwq))
1526 break;
1529 del_timer_sync(&gcwq->mayday_timer);
1530 spin_lock_irq(&gcwq->lock);
1531 if (need_to_create_worker(gcwq))
1532 goto restart;
1533 return true;
1537 * maybe_destroy_worker - destroy workers which have been idle for a while
1538 * @gcwq: gcwq to destroy workers for
1540 * Destroy @gcwq workers which have been idle for longer than
1541 * IDLE_WORKER_TIMEOUT.
1543 * LOCKING:
1544 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1545 * multiple times. Called only from manager.
1547 * RETURNS:
1548 * false if no action was taken and gcwq->lock stayed locked, true
1549 * otherwise.
1551 static bool maybe_destroy_workers(struct global_cwq *gcwq)
1553 bool ret = false;
1555 while (too_many_workers(gcwq)) {
1556 struct worker *worker;
1557 unsigned long expires;
1559 worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
1560 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1562 if (time_before(jiffies, expires)) {
1563 mod_timer(&gcwq->idle_timer, expires);
1564 break;
1567 destroy_worker(worker);
1568 ret = true;
1571 return ret;
1575 * manage_workers - manage worker pool
1576 * @worker: self
1578 * Assume the manager role and manage gcwq worker pool @worker belongs
1579 * to. At any given time, there can be only zero or one manager per
1580 * gcwq. The exclusion is handled automatically by this function.
1582 * The caller can safely start processing works on false return. On
1583 * true return, it's guaranteed that need_to_create_worker() is false
1584 * and may_start_working() is true.
1586 * CONTEXT:
1587 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1588 * multiple times. Does GFP_KERNEL allocations.
1590 * RETURNS:
1591 * false if no action was taken and gcwq->lock stayed locked, true if
1592 * some action was taken.
1594 static bool manage_workers(struct worker *worker)
1596 struct global_cwq *gcwq = worker->gcwq;
1597 bool ret = false;
1599 if (gcwq->flags & GCWQ_MANAGING_WORKERS)
1600 return ret;
1602 gcwq->flags &= ~GCWQ_MANAGE_WORKERS;
1603 gcwq->flags |= GCWQ_MANAGING_WORKERS;
1606 * Destroy and then create so that may_start_working() is true
1607 * on return.
1609 ret |= maybe_destroy_workers(gcwq);
1610 ret |= maybe_create_worker(gcwq);
1612 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
1615 * The trustee might be waiting to take over the manager
1616 * position, tell it we're done.
1618 if (unlikely(gcwq->trustee))
1619 wake_up_all(&gcwq->trustee_wait);
1621 return ret;
1625 * move_linked_works - move linked works to a list
1626 * @work: start of series of works to be scheduled
1627 * @head: target list to append @work to
1628 * @nextp: out paramter for nested worklist walking
1630 * Schedule linked works starting from @work to @head. Work series to
1631 * be scheduled starts at @work and includes any consecutive work with
1632 * WORK_STRUCT_LINKED set in its predecessor.
1634 * If @nextp is not NULL, it's updated to point to the next work of
1635 * the last scheduled work. This allows move_linked_works() to be
1636 * nested inside outer list_for_each_entry_safe().
1638 * CONTEXT:
1639 * spin_lock_irq(gcwq->lock).
1641 static void move_linked_works(struct work_struct *work, struct list_head *head,
1642 struct work_struct **nextp)
1644 struct work_struct *n;
1647 * Linked worklist will always end before the end of the list,
1648 * use NULL for list head.
1650 list_for_each_entry_safe_from(work, n, NULL, entry) {
1651 list_move_tail(&work->entry, head);
1652 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1653 break;
1657 * If we're already inside safe list traversal and have moved
1658 * multiple works to the scheduled queue, the next position
1659 * needs to be updated.
1661 if (nextp)
1662 *nextp = n;
1665 static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
1667 struct work_struct *work = list_first_entry(&cwq->delayed_works,
1668 struct work_struct, entry);
1669 struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
1671 trace_workqueue_activate_work(work);
1672 move_linked_works(work, pos, NULL);
1673 __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
1674 cwq->nr_active++;
1678 * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
1679 * @cwq: cwq of interest
1680 * @color: color of work which left the queue
1681 * @delayed: for a delayed work
1683 * A work either has completed or is removed from pending queue,
1684 * decrement nr_in_flight of its cwq and handle workqueue flushing.
1686 * CONTEXT:
1687 * spin_lock_irq(gcwq->lock).
1689 static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
1690 bool delayed)
1692 /* ignore uncolored works */
1693 if (color == WORK_NO_COLOR)
1694 return;
1696 cwq->nr_in_flight[color]--;
1698 if (!delayed) {
1699 cwq->nr_active--;
1700 if (!list_empty(&cwq->delayed_works)) {
1701 /* one down, submit a delayed one */
1702 if (cwq->nr_active < cwq->max_active)
1703 cwq_activate_first_delayed(cwq);
1707 /* is flush in progress and are we at the flushing tip? */
1708 if (likely(cwq->flush_color != color))
1709 return;
1711 /* are there still in-flight works? */
1712 if (cwq->nr_in_flight[color])
1713 return;
1715 /* this cwq is done, clear flush_color */
1716 cwq->flush_color = -1;
1719 * If this was the last cwq, wake up the first flusher. It
1720 * will handle the rest.
1722 if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
1723 complete(&cwq->wq->first_flusher->done);
1727 * process_one_work - process single work
1728 * @worker: self
1729 * @work: work to process
1731 * Process @work. This function contains all the logics necessary to
1732 * process a single work including synchronization against and
1733 * interaction with other workers on the same cpu, queueing and
1734 * flushing. As long as context requirement is met, any worker can
1735 * call this function to process a work.
1737 * CONTEXT:
1738 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1740 static void process_one_work(struct worker *worker, struct work_struct *work)
1741 __releases(&gcwq->lock)
1742 __acquires(&gcwq->lock)
1744 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1745 struct global_cwq *gcwq = cwq->gcwq;
1746 struct hlist_head *bwh = busy_worker_head(gcwq, work);
1747 bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
1748 work_func_t f = work->func;
1749 int work_color;
1750 struct worker *collision;
1751 #ifdef CONFIG_LOCKDEP
1753 * It is permissible to free the struct work_struct from
1754 * inside the function that is called from it, this we need to
1755 * take into account for lockdep too. To avoid bogus "held
1756 * lock freed" warnings as well as problems when looking into
1757 * work->lockdep_map, make a copy and use that here.
1759 struct lockdep_map lockdep_map = work->lockdep_map;
1760 #endif
1762 * A single work shouldn't be executed concurrently by
1763 * multiple workers on a single cpu. Check whether anyone is
1764 * already processing the work. If so, defer the work to the
1765 * currently executing one.
1767 collision = __find_worker_executing_work(gcwq, bwh, work);
1768 if (unlikely(collision)) {
1769 move_linked_works(work, &collision->scheduled, NULL);
1770 return;
1773 /* claim and process */
1774 debug_work_deactivate(work);
1775 hlist_add_head(&worker->hentry, bwh);
1776 worker->current_work = work;
1777 worker->current_cwq = cwq;
1778 work_color = get_work_color(work);
1780 /* record the current cpu number in the work data and dequeue */
1781 set_work_cpu(work, gcwq->cpu);
1782 list_del_init(&work->entry);
1785 * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI,
1786 * wake up another worker; otherwise, clear HIGHPRI_PENDING.
1788 if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) {
1789 struct work_struct *nwork = list_first_entry(&gcwq->worklist,
1790 struct work_struct, entry);
1792 if (!list_empty(&gcwq->worklist) &&
1793 get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI)
1794 wake_up_worker(gcwq);
1795 else
1796 gcwq->flags &= ~GCWQ_HIGHPRI_PENDING;
1800 * CPU intensive works don't participate in concurrency
1801 * management. They're the scheduler's responsibility.
1803 if (unlikely(cpu_intensive))
1804 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
1806 spin_unlock_irq(&gcwq->lock);
1808 work_clear_pending(work);
1809 lock_map_acquire(&cwq->wq->lockdep_map);
1810 lock_map_acquire(&lockdep_map);
1811 trace_workqueue_execute_start(work);
1812 f(work);
1814 * While we must be careful to not use "work" after this, the trace
1815 * point will only record its address.
1817 trace_workqueue_execute_end(work);
1818 lock_map_release(&lockdep_map);
1819 lock_map_release(&cwq->wq->lockdep_map);
1821 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
1822 printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
1823 "%s/0x%08x/%d\n",
1824 current->comm, preempt_count(), task_pid_nr(current));
1825 printk(KERN_ERR " last function: ");
1826 print_symbol("%s\n", (unsigned long)f);
1827 debug_show_held_locks(current);
1828 dump_stack();
1831 spin_lock_irq(&gcwq->lock);
1833 /* clear cpu intensive status */
1834 if (unlikely(cpu_intensive))
1835 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
1837 /* we're done with it, release */
1838 hlist_del_init(&worker->hentry);
1839 worker->current_work = NULL;
1840 worker->current_cwq = NULL;
1841 cwq_dec_nr_in_flight(cwq, work_color, false);
1845 * process_scheduled_works - process scheduled works
1846 * @worker: self
1848 * Process all scheduled works. Please note that the scheduled list
1849 * may change while processing a work, so this function repeatedly
1850 * fetches a work from the top and executes it.
1852 * CONTEXT:
1853 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1854 * multiple times.
1856 static void process_scheduled_works(struct worker *worker)
1858 while (!list_empty(&worker->scheduled)) {
1859 struct work_struct *work = list_first_entry(&worker->scheduled,
1860 struct work_struct, entry);
1861 process_one_work(worker, work);
1866 * worker_thread - the worker thread function
1867 * @__worker: self
1869 * The gcwq worker thread function. There's a single dynamic pool of
1870 * these per each cpu. These workers process all works regardless of
1871 * their specific target workqueue. The only exception is works which
1872 * belong to workqueues with a rescuer which will be explained in
1873 * rescuer_thread().
1875 static int worker_thread(void *__worker)
1877 struct worker *worker = __worker;
1878 struct global_cwq *gcwq = worker->gcwq;
1880 /* tell the scheduler that this is a workqueue worker */
1881 worker->task->flags |= PF_WQ_WORKER;
1882 woke_up:
1883 spin_lock_irq(&gcwq->lock);
1885 /* DIE can be set only while we're idle, checking here is enough */
1886 if (worker->flags & WORKER_DIE) {
1887 spin_unlock_irq(&gcwq->lock);
1888 worker->task->flags &= ~PF_WQ_WORKER;
1889 return 0;
1892 worker_leave_idle(worker);
1893 recheck:
1894 /* no more worker necessary? */
1895 if (!need_more_worker(gcwq))
1896 goto sleep;
1898 /* do we need to manage? */
1899 if (unlikely(!may_start_working(gcwq)) && manage_workers(worker))
1900 goto recheck;
1903 * ->scheduled list can only be filled while a worker is
1904 * preparing to process a work or actually processing it.
1905 * Make sure nobody diddled with it while I was sleeping.
1907 BUG_ON(!list_empty(&worker->scheduled));
1910 * When control reaches this point, we're guaranteed to have
1911 * at least one idle worker or that someone else has already
1912 * assumed the manager role.
1914 worker_clr_flags(worker, WORKER_PREP);
1916 do {
1917 struct work_struct *work =
1918 list_first_entry(&gcwq->worklist,
1919 struct work_struct, entry);
1921 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
1922 /* optimization path, not strictly necessary */
1923 process_one_work(worker, work);
1924 if (unlikely(!list_empty(&worker->scheduled)))
1925 process_scheduled_works(worker);
1926 } else {
1927 move_linked_works(work, &worker->scheduled, NULL);
1928 process_scheduled_works(worker);
1930 } while (keep_working(gcwq));
1932 worker_set_flags(worker, WORKER_PREP, false);
1933 sleep:
1934 if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker))
1935 goto recheck;
1938 * gcwq->lock is held and there's no work to process and no
1939 * need to manage, sleep. Workers are woken up only while
1940 * holding gcwq->lock or from local cpu, so setting the
1941 * current state before releasing gcwq->lock is enough to
1942 * prevent losing any event.
1944 worker_enter_idle(worker);
1945 __set_current_state(TASK_INTERRUPTIBLE);
1946 spin_unlock_irq(&gcwq->lock);
1947 schedule();
1948 goto woke_up;
1952 * rescuer_thread - the rescuer thread function
1953 * @__wq: the associated workqueue
1955 * Workqueue rescuer thread function. There's one rescuer for each
1956 * workqueue which has WQ_RESCUER set.
1958 * Regular work processing on a gcwq may block trying to create a new
1959 * worker which uses GFP_KERNEL allocation which has slight chance of
1960 * developing into deadlock if some works currently on the same queue
1961 * need to be processed to satisfy the GFP_KERNEL allocation. This is
1962 * the problem rescuer solves.
1964 * When such condition is possible, the gcwq summons rescuers of all
1965 * workqueues which have works queued on the gcwq and let them process
1966 * those works so that forward progress can be guaranteed.
1968 * This should happen rarely.
1970 static int rescuer_thread(void *__wq)
1972 struct workqueue_struct *wq = __wq;
1973 struct worker *rescuer = wq->rescuer;
1974 struct list_head *scheduled = &rescuer->scheduled;
1975 bool is_unbound = wq->flags & WQ_UNBOUND;
1976 unsigned int cpu;
1978 set_user_nice(current, RESCUER_NICE_LEVEL);
1979 repeat:
1980 set_current_state(TASK_INTERRUPTIBLE);
1982 if (kthread_should_stop())
1983 return 0;
1986 * See whether any cpu is asking for help. Unbounded
1987 * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
1989 for_each_mayday_cpu(cpu, wq->mayday_mask) {
1990 unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
1991 struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
1992 struct global_cwq *gcwq = cwq->gcwq;
1993 struct work_struct *work, *n;
1995 __set_current_state(TASK_RUNNING);
1996 mayday_clear_cpu(cpu, wq->mayday_mask);
1998 /* migrate to the target cpu if possible */
1999 rescuer->gcwq = gcwq;
2000 worker_maybe_bind_and_lock(rescuer);
2003 * Slurp in all works issued via this workqueue and
2004 * process'em.
2006 BUG_ON(!list_empty(&rescuer->scheduled));
2007 list_for_each_entry_safe(work, n, &gcwq->worklist, entry)
2008 if (get_work_cwq(work) == cwq)
2009 move_linked_works(work, scheduled, &n);
2011 process_scheduled_works(rescuer);
2012 spin_unlock_irq(&gcwq->lock);
2015 schedule();
2016 goto repeat;
2019 struct wq_barrier {
2020 struct work_struct work;
2021 struct completion done;
2024 static void wq_barrier_func(struct work_struct *work)
2026 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
2027 complete(&barr->done);
2031 * insert_wq_barrier - insert a barrier work
2032 * @cwq: cwq to insert barrier into
2033 * @barr: wq_barrier to insert
2034 * @target: target work to attach @barr to
2035 * @worker: worker currently executing @target, NULL if @target is not executing
2037 * @barr is linked to @target such that @barr is completed only after
2038 * @target finishes execution. Please note that the ordering
2039 * guarantee is observed only with respect to @target and on the local
2040 * cpu.
2042 * Currently, a queued barrier can't be canceled. This is because
2043 * try_to_grab_pending() can't determine whether the work to be
2044 * grabbed is at the head of the queue and thus can't clear LINKED
2045 * flag of the previous work while there must be a valid next work
2046 * after a work with LINKED flag set.
2048 * Note that when @worker is non-NULL, @target may be modified
2049 * underneath us, so we can't reliably determine cwq from @target.
2051 * CONTEXT:
2052 * spin_lock_irq(gcwq->lock).
2054 static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
2055 struct wq_barrier *barr,
2056 struct work_struct *target, struct worker *worker)
2058 struct list_head *head;
2059 unsigned int linked = 0;
2062 * debugobject calls are safe here even with gcwq->lock locked
2063 * as we know for sure that this will not trigger any of the
2064 * checks and call back into the fixup functions where we
2065 * might deadlock.
2067 INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
2068 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
2069 init_completion(&barr->done);
2072 * If @target is currently being executed, schedule the
2073 * barrier to the worker; otherwise, put it after @target.
2075 if (worker)
2076 head = worker->scheduled.next;
2077 else {
2078 unsigned long *bits = work_data_bits(target);
2080 head = target->entry.next;
2081 /* there can already be other linked works, inherit and set */
2082 linked = *bits & WORK_STRUCT_LINKED;
2083 __set_bit(WORK_STRUCT_LINKED_BIT, bits);
2086 debug_work_activate(&barr->work);
2087 insert_work(cwq, &barr->work, head,
2088 work_color_to_flags(WORK_NO_COLOR) | linked);
2092 * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
2093 * @wq: workqueue being flushed
2094 * @flush_color: new flush color, < 0 for no-op
2095 * @work_color: new work color, < 0 for no-op
2097 * Prepare cwqs for workqueue flushing.
2099 * If @flush_color is non-negative, flush_color on all cwqs should be
2100 * -1. If no cwq has in-flight commands at the specified color, all
2101 * cwq->flush_color's stay at -1 and %false is returned. If any cwq
2102 * has in flight commands, its cwq->flush_color is set to
2103 * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
2104 * wakeup logic is armed and %true is returned.
2106 * The caller should have initialized @wq->first_flusher prior to
2107 * calling this function with non-negative @flush_color. If
2108 * @flush_color is negative, no flush color update is done and %false
2109 * is returned.
2111 * If @work_color is non-negative, all cwqs should have the same
2112 * work_color which is previous to @work_color and all will be
2113 * advanced to @work_color.
2115 * CONTEXT:
2116 * mutex_lock(wq->flush_mutex).
2118 * RETURNS:
2119 * %true if @flush_color >= 0 and there's something to flush. %false
2120 * otherwise.
2122 static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
2123 int flush_color, int work_color)
2125 bool wait = false;
2126 unsigned int cpu;
2128 if (flush_color >= 0) {
2129 BUG_ON(atomic_read(&wq->nr_cwqs_to_flush));
2130 atomic_set(&wq->nr_cwqs_to_flush, 1);
2133 for_each_cwq_cpu(cpu, wq) {
2134 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2135 struct global_cwq *gcwq = cwq->gcwq;
2137 spin_lock_irq(&gcwq->lock);
2139 if (flush_color >= 0) {
2140 BUG_ON(cwq->flush_color != -1);
2142 if (cwq->nr_in_flight[flush_color]) {
2143 cwq->flush_color = flush_color;
2144 atomic_inc(&wq->nr_cwqs_to_flush);
2145 wait = true;
2149 if (work_color >= 0) {
2150 BUG_ON(work_color != work_next_color(cwq->work_color));
2151 cwq->work_color = work_color;
2154 spin_unlock_irq(&gcwq->lock);
2157 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush))
2158 complete(&wq->first_flusher->done);
2160 return wait;
2164 * flush_workqueue - ensure that any scheduled work has run to completion.
2165 * @wq: workqueue to flush
2167 * Forces execution of the workqueue and blocks until its completion.
2168 * This is typically used in driver shutdown handlers.
2170 * We sleep until all works which were queued on entry have been handled,
2171 * but we are not livelocked by new incoming ones.
2173 void flush_workqueue(struct workqueue_struct *wq)
2175 struct wq_flusher this_flusher = {
2176 .list = LIST_HEAD_INIT(this_flusher.list),
2177 .flush_color = -1,
2178 .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
2180 int next_color;
2182 lock_map_acquire(&wq->lockdep_map);
2183 lock_map_release(&wq->lockdep_map);
2185 mutex_lock(&wq->flush_mutex);
2188 * Start-to-wait phase
2190 next_color = work_next_color(wq->work_color);
2192 if (next_color != wq->flush_color) {
2194 * Color space is not full. The current work_color
2195 * becomes our flush_color and work_color is advanced
2196 * by one.
2198 BUG_ON(!list_empty(&wq->flusher_overflow));
2199 this_flusher.flush_color = wq->work_color;
2200 wq->work_color = next_color;
2202 if (!wq->first_flusher) {
2203 /* no flush in progress, become the first flusher */
2204 BUG_ON(wq->flush_color != this_flusher.flush_color);
2206 wq->first_flusher = &this_flusher;
2208 if (!flush_workqueue_prep_cwqs(wq, wq->flush_color,
2209 wq->work_color)) {
2210 /* nothing to flush, done */
2211 wq->flush_color = next_color;
2212 wq->first_flusher = NULL;
2213 goto out_unlock;
2215 } else {
2216 /* wait in queue */
2217 BUG_ON(wq->flush_color == this_flusher.flush_color);
2218 list_add_tail(&this_flusher.list, &wq->flusher_queue);
2219 flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
2221 } else {
2223 * Oops, color space is full, wait on overflow queue.
2224 * The next flush completion will assign us
2225 * flush_color and transfer to flusher_queue.
2227 list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2230 mutex_unlock(&wq->flush_mutex);
2232 wait_for_completion(&this_flusher.done);
2235 * Wake-up-and-cascade phase
2237 * First flushers are responsible for cascading flushes and
2238 * handling overflow. Non-first flushers can simply return.
2240 if (wq->first_flusher != &this_flusher)
2241 return;
2243 mutex_lock(&wq->flush_mutex);
2245 /* we might have raced, check again with mutex held */
2246 if (wq->first_flusher != &this_flusher)
2247 goto out_unlock;
2249 wq->first_flusher = NULL;
2251 BUG_ON(!list_empty(&this_flusher.list));
2252 BUG_ON(wq->flush_color != this_flusher.flush_color);
2254 while (true) {
2255 struct wq_flusher *next, *tmp;
2257 /* complete all the flushers sharing the current flush color */
2258 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2259 if (next->flush_color != wq->flush_color)
2260 break;
2261 list_del_init(&next->list);
2262 complete(&next->done);
2265 BUG_ON(!list_empty(&wq->flusher_overflow) &&
2266 wq->flush_color != work_next_color(wq->work_color));
2268 /* this flush_color is finished, advance by one */
2269 wq->flush_color = work_next_color(wq->flush_color);
2271 /* one color has been freed, handle overflow queue */
2272 if (!list_empty(&wq->flusher_overflow)) {
2274 * Assign the same color to all overflowed
2275 * flushers, advance work_color and append to
2276 * flusher_queue. This is the start-to-wait
2277 * phase for these overflowed flushers.
2279 list_for_each_entry(tmp, &wq->flusher_overflow, list)
2280 tmp->flush_color = wq->work_color;
2282 wq->work_color = work_next_color(wq->work_color);
2284 list_splice_tail_init(&wq->flusher_overflow,
2285 &wq->flusher_queue);
2286 flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
2289 if (list_empty(&wq->flusher_queue)) {
2290 BUG_ON(wq->flush_color != wq->work_color);
2291 break;
2295 * Need to flush more colors. Make the next flusher
2296 * the new first flusher and arm cwqs.
2298 BUG_ON(wq->flush_color == wq->work_color);
2299 BUG_ON(wq->flush_color != next->flush_color);
2301 list_del_init(&next->list);
2302 wq->first_flusher = next;
2304 if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1))
2305 break;
2308 * Meh... this color is already done, clear first
2309 * flusher and repeat cascading.
2311 wq->first_flusher = NULL;
2314 out_unlock:
2315 mutex_unlock(&wq->flush_mutex);
2317 EXPORT_SYMBOL_GPL(flush_workqueue);
2319 static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
2320 bool wait_executing)
2322 struct worker *worker = NULL;
2323 struct global_cwq *gcwq;
2324 struct cpu_workqueue_struct *cwq;
2326 might_sleep();
2327 gcwq = get_work_gcwq(work);
2328 if (!gcwq)
2329 return false;
2331 spin_lock_irq(&gcwq->lock);
2332 if (!list_empty(&work->entry)) {
2334 * See the comment near try_to_grab_pending()->smp_rmb().
2335 * If it was re-queued to a different gcwq under us, we
2336 * are not going to wait.
2338 smp_rmb();
2339 cwq = get_work_cwq(work);
2340 if (unlikely(!cwq || gcwq != cwq->gcwq))
2341 goto already_gone;
2342 } else if (wait_executing) {
2343 worker = find_worker_executing_work(gcwq, work);
2344 if (!worker)
2345 goto already_gone;
2346 cwq = worker->current_cwq;
2347 } else
2348 goto already_gone;
2350 insert_wq_barrier(cwq, barr, work, worker);
2351 spin_unlock_irq(&gcwq->lock);
2353 lock_map_acquire(&cwq->wq->lockdep_map);
2354 lock_map_release(&cwq->wq->lockdep_map);
2355 return true;
2356 already_gone:
2357 spin_unlock_irq(&gcwq->lock);
2358 return false;
2362 * flush_work - wait for a work to finish executing the last queueing instance
2363 * @work: the work to flush
2365 * Wait until @work has finished execution. This function considers
2366 * only the last queueing instance of @work. If @work has been
2367 * enqueued across different CPUs on a non-reentrant workqueue or on
2368 * multiple workqueues, @work might still be executing on return on
2369 * some of the CPUs from earlier queueing.
2371 * If @work was queued only on a non-reentrant, ordered or unbound
2372 * workqueue, @work is guaranteed to be idle on return if it hasn't
2373 * been requeued since flush started.
2375 * RETURNS:
2376 * %true if flush_work() waited for the work to finish execution,
2377 * %false if it was already idle.
2379 bool flush_work(struct work_struct *work)
2381 struct wq_barrier barr;
2383 if (start_flush_work(work, &barr, true)) {
2384 wait_for_completion(&barr.done);
2385 destroy_work_on_stack(&barr.work);
2386 return true;
2387 } else
2388 return false;
2390 EXPORT_SYMBOL_GPL(flush_work);
2392 static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
2394 struct wq_barrier barr;
2395 struct worker *worker;
2397 spin_lock_irq(&gcwq->lock);
2399 worker = find_worker_executing_work(gcwq, work);
2400 if (unlikely(worker))
2401 insert_wq_barrier(worker->current_cwq, &barr, work, worker);
2403 spin_unlock_irq(&gcwq->lock);
2405 if (unlikely(worker)) {
2406 wait_for_completion(&barr.done);
2407 destroy_work_on_stack(&barr.work);
2408 return true;
2409 } else
2410 return false;
2413 static bool wait_on_work(struct work_struct *work)
2415 bool ret = false;
2416 int cpu;
2418 might_sleep();
2420 lock_map_acquire(&work->lockdep_map);
2421 lock_map_release(&work->lockdep_map);
2423 for_each_gcwq_cpu(cpu)
2424 ret |= wait_on_cpu_work(get_gcwq(cpu), work);
2425 return ret;
2429 * flush_work_sync - wait until a work has finished execution
2430 * @work: the work to flush
2432 * Wait until @work has finished execution. On return, it's
2433 * guaranteed that all queueing instances of @work which happened
2434 * before this function is called are finished. In other words, if
2435 * @work hasn't been requeued since this function was called, @work is
2436 * guaranteed to be idle on return.
2438 * RETURNS:
2439 * %true if flush_work_sync() waited for the work to finish execution,
2440 * %false if it was already idle.
2442 bool flush_work_sync(struct work_struct *work)
2444 struct wq_barrier barr;
2445 bool pending, waited;
2447 /* we'll wait for executions separately, queue barr only if pending */
2448 pending = start_flush_work(work, &barr, false);
2450 /* wait for executions to finish */
2451 waited = wait_on_work(work);
2453 /* wait for the pending one */
2454 if (pending) {
2455 wait_for_completion(&barr.done);
2456 destroy_work_on_stack(&barr.work);
2459 return pending || waited;
2461 EXPORT_SYMBOL_GPL(flush_work_sync);
2464 * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
2465 * so this work can't be re-armed in any way.
2467 static int try_to_grab_pending(struct work_struct *work)
2469 struct global_cwq *gcwq;
2470 int ret = -1;
2472 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
2473 return 0;
2476 * The queueing is in progress, or it is already queued. Try to
2477 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
2479 gcwq = get_work_gcwq(work);
2480 if (!gcwq)
2481 return ret;
2483 spin_lock_irq(&gcwq->lock);
2484 if (!list_empty(&work->entry)) {
2486 * This work is queued, but perhaps we locked the wrong gcwq.
2487 * In that case we must see the new value after rmb(), see
2488 * insert_work()->wmb().
2490 smp_rmb();
2491 if (gcwq == get_work_gcwq(work)) {
2492 debug_work_deactivate(work);
2493 list_del_init(&work->entry);
2494 cwq_dec_nr_in_flight(get_work_cwq(work),
2495 get_work_color(work),
2496 *work_data_bits(work) & WORK_STRUCT_DELAYED);
2497 ret = 1;
2500 spin_unlock_irq(&gcwq->lock);
2502 return ret;
2505 static bool __cancel_work_timer(struct work_struct *work,
2506 struct timer_list* timer)
2508 int ret;
2510 do {
2511 ret = (timer && likely(del_timer(timer)));
2512 if (!ret)
2513 ret = try_to_grab_pending(work);
2514 wait_on_work(work);
2515 } while (unlikely(ret < 0));
2517 clear_work_data(work);
2518 return ret;
2522 * cancel_work_sync - cancel a work and wait for it to finish
2523 * @work: the work to cancel
2525 * Cancel @work and wait for its execution to finish. This function
2526 * can be used even if the work re-queues itself or migrates to
2527 * another workqueue. On return from this function, @work is
2528 * guaranteed to be not pending or executing on any CPU.
2530 * cancel_work_sync(&delayed_work->work) must not be used for
2531 * delayed_work's. Use cancel_delayed_work_sync() instead.
2533 * The caller must ensure that the workqueue on which @work was last
2534 * queued can't be destroyed before this function returns.
2536 * RETURNS:
2537 * %true if @work was pending, %false otherwise.
2539 bool cancel_work_sync(struct work_struct *work)
2541 return __cancel_work_timer(work, NULL);
2543 EXPORT_SYMBOL_GPL(cancel_work_sync);
2546 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2547 * @dwork: the delayed work to flush
2549 * Delayed timer is cancelled and the pending work is queued for
2550 * immediate execution. Like flush_work(), this function only
2551 * considers the last queueing instance of @dwork.
2553 * RETURNS:
2554 * %true if flush_work() waited for the work to finish execution,
2555 * %false if it was already idle.
2557 bool flush_delayed_work(struct delayed_work *dwork)
2559 if (del_timer_sync(&dwork->timer))
2560 __queue_work(raw_smp_processor_id(),
2561 get_work_cwq(&dwork->work)->wq, &dwork->work);
2562 return flush_work(&dwork->work);
2564 EXPORT_SYMBOL(flush_delayed_work);
2567 * flush_delayed_work_sync - wait for a dwork to finish
2568 * @dwork: the delayed work to flush
2570 * Delayed timer is cancelled and the pending work is queued for
2571 * execution immediately. Other than timer handling, its behavior
2572 * is identical to flush_work_sync().
2574 * RETURNS:
2575 * %true if flush_work_sync() waited for the work to finish execution,
2576 * %false if it was already idle.
2578 bool flush_delayed_work_sync(struct delayed_work *dwork)
2580 if (del_timer_sync(&dwork->timer))
2581 __queue_work(raw_smp_processor_id(),
2582 get_work_cwq(&dwork->work)->wq, &dwork->work);
2583 return flush_work_sync(&dwork->work);
2585 EXPORT_SYMBOL(flush_delayed_work_sync);
2588 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2589 * @dwork: the delayed work cancel
2591 * This is cancel_work_sync() for delayed works.
2593 * RETURNS:
2594 * %true if @dwork was pending, %false otherwise.
2596 bool cancel_delayed_work_sync(struct delayed_work *dwork)
2598 return __cancel_work_timer(&dwork->work, &dwork->timer);
2600 EXPORT_SYMBOL(cancel_delayed_work_sync);
2603 * schedule_work - put work task in global workqueue
2604 * @work: job to be done
2606 * Returns zero if @work was already on the kernel-global workqueue and
2607 * non-zero otherwise.
2609 * This puts a job in the kernel-global workqueue if it was not already
2610 * queued and leaves it in the same position on the kernel-global
2611 * workqueue otherwise.
2613 int schedule_work(struct work_struct *work)
2615 return queue_work(system_wq, work);
2617 EXPORT_SYMBOL(schedule_work);
2620 * schedule_work_on - put work task on a specific cpu
2621 * @cpu: cpu to put the work task on
2622 * @work: job to be done
2624 * This puts a job on a specific cpu
2626 int schedule_work_on(int cpu, struct work_struct *work)
2628 return queue_work_on(cpu, system_wq, work);
2630 EXPORT_SYMBOL(schedule_work_on);
2633 * schedule_delayed_work - put work task in global workqueue after delay
2634 * @dwork: job to be done
2635 * @delay: number of jiffies to wait or 0 for immediate execution
2637 * After waiting for a given time this puts a job in the kernel-global
2638 * workqueue.
2640 int schedule_delayed_work(struct delayed_work *dwork,
2641 unsigned long delay)
2643 return queue_delayed_work(system_wq, dwork, delay);
2645 EXPORT_SYMBOL(schedule_delayed_work);
2648 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
2649 * @cpu: cpu to use
2650 * @dwork: job to be done
2651 * @delay: number of jiffies to wait
2653 * After waiting for a given time this puts a job in the kernel-global
2654 * workqueue on the specified CPU.
2656 int schedule_delayed_work_on(int cpu,
2657 struct delayed_work *dwork, unsigned long delay)
2659 return queue_delayed_work_on(cpu, system_wq, dwork, delay);
2661 EXPORT_SYMBOL(schedule_delayed_work_on);
2664 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2665 * @func: the function to call
2667 * schedule_on_each_cpu() executes @func on each online CPU using the
2668 * system workqueue and blocks until all CPUs have completed.
2669 * schedule_on_each_cpu() is very slow.
2671 * RETURNS:
2672 * 0 on success, -errno on failure.
2674 int schedule_on_each_cpu(work_func_t func)
2676 int cpu;
2677 struct work_struct __percpu *works;
2679 works = alloc_percpu(struct work_struct);
2680 if (!works)
2681 return -ENOMEM;
2683 get_online_cpus();
2685 for_each_online_cpu(cpu) {
2686 struct work_struct *work = per_cpu_ptr(works, cpu);
2688 INIT_WORK(work, func);
2689 schedule_work_on(cpu, work);
2692 for_each_online_cpu(cpu)
2693 flush_work(per_cpu_ptr(works, cpu));
2695 put_online_cpus();
2696 free_percpu(works);
2697 return 0;
2701 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2703 * Forces execution of the kernel-global workqueue and blocks until its
2704 * completion.
2706 * Think twice before calling this function! It's very easy to get into
2707 * trouble if you don't take great care. Either of the following situations
2708 * will lead to deadlock:
2710 * One of the work items currently on the workqueue needs to acquire
2711 * a lock held by your code or its caller.
2713 * Your code is running in the context of a work routine.
2715 * They will be detected by lockdep when they occur, but the first might not
2716 * occur very often. It depends on what work items are on the workqueue and
2717 * what locks they need, which you have no control over.
2719 * In most situations flushing the entire workqueue is overkill; you merely
2720 * need to know that a particular work item isn't queued and isn't running.
2721 * In such cases you should use cancel_delayed_work_sync() or
2722 * cancel_work_sync() instead.
2724 void flush_scheduled_work(void)
2726 flush_workqueue(system_wq);
2728 EXPORT_SYMBOL(flush_scheduled_work);
2731 * execute_in_process_context - reliably execute the routine with user context
2732 * @fn: the function to execute
2733 * @ew: guaranteed storage for the execute work structure (must
2734 * be available when the work executes)
2736 * Executes the function immediately if process context is available,
2737 * otherwise schedules the function for delayed execution.
2739 * Returns: 0 - function was executed
2740 * 1 - function was scheduled for execution
2742 int execute_in_process_context(work_func_t fn, struct execute_work *ew)
2744 if (!in_interrupt()) {
2745 fn(&ew->work);
2746 return 0;
2749 INIT_WORK(&ew->work, fn);
2750 schedule_work(&ew->work);
2752 return 1;
2754 EXPORT_SYMBOL_GPL(execute_in_process_context);
2756 int keventd_up(void)
2758 return system_wq != NULL;
2761 static int alloc_cwqs(struct workqueue_struct *wq)
2764 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
2765 * Make sure that the alignment isn't lower than that of
2766 * unsigned long long.
2768 const size_t size = sizeof(struct cpu_workqueue_struct);
2769 const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
2770 __alignof__(unsigned long long));
2771 #ifdef CONFIG_SMP
2772 bool percpu = !(wq->flags & WQ_UNBOUND);
2773 #else
2774 bool percpu = false;
2775 #endif
2777 if (percpu)
2778 wq->cpu_wq.pcpu = __alloc_percpu(size, align);
2779 else {
2780 void *ptr;
2783 * Allocate enough room to align cwq and put an extra
2784 * pointer at the end pointing back to the originally
2785 * allocated pointer which will be used for free.
2787 ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
2788 if (ptr) {
2789 wq->cpu_wq.single = PTR_ALIGN(ptr, align);
2790 *(void **)(wq->cpu_wq.single + 1) = ptr;
2794 /* just in case, make sure it's actually aligned
2795 * - this is affected by PERCPU() alignment in vmlinux.lds.S
2797 BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
2798 return wq->cpu_wq.v ? 0 : -ENOMEM;
2801 static void free_cwqs(struct workqueue_struct *wq)
2803 #ifdef CONFIG_SMP
2804 bool percpu = !(wq->flags & WQ_UNBOUND);
2805 #else
2806 bool percpu = false;
2807 #endif
2809 if (percpu)
2810 free_percpu(wq->cpu_wq.pcpu);
2811 else if (wq->cpu_wq.single) {
2812 /* the pointer to free is stored right after the cwq */
2813 kfree(*(void **)(wq->cpu_wq.single + 1));
2817 static int wq_clamp_max_active(int max_active, unsigned int flags,
2818 const char *name)
2820 int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
2822 if (max_active < 1 || max_active > lim)
2823 printk(KERN_WARNING "workqueue: max_active %d requested for %s "
2824 "is out of range, clamping between %d and %d\n",
2825 max_active, name, 1, lim);
2827 return clamp_val(max_active, 1, lim);
2830 struct workqueue_struct *__alloc_workqueue_key(const char *name,
2831 unsigned int flags,
2832 int max_active,
2833 struct lock_class_key *key,
2834 const char *lock_name)
2836 struct workqueue_struct *wq;
2837 unsigned int cpu;
2840 * Workqueues which may be used during memory reclaim should
2841 * have a rescuer to guarantee forward progress.
2843 if (flags & WQ_MEM_RECLAIM)
2844 flags |= WQ_RESCUER;
2847 * Unbound workqueues aren't concurrency managed and should be
2848 * dispatched to workers immediately.
2850 if (flags & WQ_UNBOUND)
2851 flags |= WQ_HIGHPRI;
2853 max_active = max_active ?: WQ_DFL_ACTIVE;
2854 max_active = wq_clamp_max_active(max_active, flags, name);
2856 wq = kzalloc(sizeof(*wq), GFP_KERNEL);
2857 if (!wq)
2858 goto err;
2860 wq->flags = flags;
2861 wq->saved_max_active = max_active;
2862 mutex_init(&wq->flush_mutex);
2863 atomic_set(&wq->nr_cwqs_to_flush, 0);
2864 INIT_LIST_HEAD(&wq->flusher_queue);
2865 INIT_LIST_HEAD(&wq->flusher_overflow);
2867 wq->name = name;
2868 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
2869 INIT_LIST_HEAD(&wq->list);
2871 if (alloc_cwqs(wq) < 0)
2872 goto err;
2874 for_each_cwq_cpu(cpu, wq) {
2875 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2876 struct global_cwq *gcwq = get_gcwq(cpu);
2878 BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
2879 cwq->gcwq = gcwq;
2880 cwq->wq = wq;
2881 cwq->flush_color = -1;
2882 cwq->max_active = max_active;
2883 INIT_LIST_HEAD(&cwq->delayed_works);
2886 if (flags & WQ_RESCUER) {
2887 struct worker *rescuer;
2889 if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL))
2890 goto err;
2892 wq->rescuer = rescuer = alloc_worker();
2893 if (!rescuer)
2894 goto err;
2896 rescuer->task = kthread_create(rescuer_thread, wq, "%s", name);
2897 if (IS_ERR(rescuer->task))
2898 goto err;
2900 rescuer->task->flags |= PF_THREAD_BOUND;
2901 wake_up_process(rescuer->task);
2905 * workqueue_lock protects global freeze state and workqueues
2906 * list. Grab it, set max_active accordingly and add the new
2907 * workqueue to workqueues list.
2909 spin_lock(&workqueue_lock);
2911 if (workqueue_freezing && wq->flags & WQ_FREEZEABLE)
2912 for_each_cwq_cpu(cpu, wq)
2913 get_cwq(cpu, wq)->max_active = 0;
2915 list_add(&wq->list, &workqueues);
2917 spin_unlock(&workqueue_lock);
2919 return wq;
2920 err:
2921 if (wq) {
2922 free_cwqs(wq);
2923 free_mayday_mask(wq->mayday_mask);
2924 kfree(wq->rescuer);
2925 kfree(wq);
2927 return NULL;
2929 EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
2932 * destroy_workqueue - safely terminate a workqueue
2933 * @wq: target workqueue
2935 * Safely destroy a workqueue. All work currently pending will be done first.
2937 void destroy_workqueue(struct workqueue_struct *wq)
2939 unsigned int cpu;
2941 wq->flags |= WQ_DYING;
2942 flush_workqueue(wq);
2945 * wq list is used to freeze wq, remove from list after
2946 * flushing is complete in case freeze races us.
2948 spin_lock(&workqueue_lock);
2949 list_del(&wq->list);
2950 spin_unlock(&workqueue_lock);
2952 /* sanity check */
2953 for_each_cwq_cpu(cpu, wq) {
2954 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2955 int i;
2957 for (i = 0; i < WORK_NR_COLORS; i++)
2958 BUG_ON(cwq->nr_in_flight[i]);
2959 BUG_ON(cwq->nr_active);
2960 BUG_ON(!list_empty(&cwq->delayed_works));
2963 if (wq->flags & WQ_RESCUER) {
2964 kthread_stop(wq->rescuer->task);
2965 free_mayday_mask(wq->mayday_mask);
2966 kfree(wq->rescuer);
2969 free_cwqs(wq);
2970 kfree(wq);
2972 EXPORT_SYMBOL_GPL(destroy_workqueue);
2975 * workqueue_set_max_active - adjust max_active of a workqueue
2976 * @wq: target workqueue
2977 * @max_active: new max_active value.
2979 * Set max_active of @wq to @max_active.
2981 * CONTEXT:
2982 * Don't call from IRQ context.
2984 void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
2986 unsigned int cpu;
2988 max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
2990 spin_lock(&workqueue_lock);
2992 wq->saved_max_active = max_active;
2994 for_each_cwq_cpu(cpu, wq) {
2995 struct global_cwq *gcwq = get_gcwq(cpu);
2997 spin_lock_irq(&gcwq->lock);
2999 if (!(wq->flags & WQ_FREEZEABLE) ||
3000 !(gcwq->flags & GCWQ_FREEZING))
3001 get_cwq(gcwq->cpu, wq)->max_active = max_active;
3003 spin_unlock_irq(&gcwq->lock);
3006 spin_unlock(&workqueue_lock);
3008 EXPORT_SYMBOL_GPL(workqueue_set_max_active);
3011 * workqueue_congested - test whether a workqueue is congested
3012 * @cpu: CPU in question
3013 * @wq: target workqueue
3015 * Test whether @wq's cpu workqueue for @cpu is congested. There is
3016 * no synchronization around this function and the test result is
3017 * unreliable and only useful as advisory hints or for debugging.
3019 * RETURNS:
3020 * %true if congested, %false otherwise.
3022 bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
3024 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3026 return !list_empty(&cwq->delayed_works);
3028 EXPORT_SYMBOL_GPL(workqueue_congested);
3031 * work_cpu - return the last known associated cpu for @work
3032 * @work: the work of interest
3034 * RETURNS:
3035 * CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
3037 unsigned int work_cpu(struct work_struct *work)
3039 struct global_cwq *gcwq = get_work_gcwq(work);
3041 return gcwq ? gcwq->cpu : WORK_CPU_NONE;
3043 EXPORT_SYMBOL_GPL(work_cpu);
3046 * work_busy - test whether a work is currently pending or running
3047 * @work: the work to be tested
3049 * Test whether @work is currently pending or running. There is no
3050 * synchronization around this function and the test result is
3051 * unreliable and only useful as advisory hints or for debugging.
3052 * Especially for reentrant wqs, the pending state might hide the
3053 * running state.
3055 * RETURNS:
3056 * OR'd bitmask of WORK_BUSY_* bits.
3058 unsigned int work_busy(struct work_struct *work)
3060 struct global_cwq *gcwq = get_work_gcwq(work);
3061 unsigned long flags;
3062 unsigned int ret = 0;
3064 if (!gcwq)
3065 return false;
3067 spin_lock_irqsave(&gcwq->lock, flags);
3069 if (work_pending(work))
3070 ret |= WORK_BUSY_PENDING;
3071 if (find_worker_executing_work(gcwq, work))
3072 ret |= WORK_BUSY_RUNNING;
3074 spin_unlock_irqrestore(&gcwq->lock, flags);
3076 return ret;
3078 EXPORT_SYMBOL_GPL(work_busy);
3081 * CPU hotplug.
3083 * There are two challenges in supporting CPU hotplug. Firstly, there
3084 * are a lot of assumptions on strong associations among work, cwq and
3085 * gcwq which make migrating pending and scheduled works very
3086 * difficult to implement without impacting hot paths. Secondly,
3087 * gcwqs serve mix of short, long and very long running works making
3088 * blocked draining impractical.
3090 * This is solved by allowing a gcwq to be detached from CPU, running
3091 * it with unbound (rogue) workers and allowing it to be reattached
3092 * later if the cpu comes back online. A separate thread is created
3093 * to govern a gcwq in such state and is called the trustee of the
3094 * gcwq.
3096 * Trustee states and their descriptions.
3098 * START Command state used on startup. On CPU_DOWN_PREPARE, a
3099 * new trustee is started with this state.
3101 * IN_CHARGE Once started, trustee will enter this state after
3102 * assuming the manager role and making all existing
3103 * workers rogue. DOWN_PREPARE waits for trustee to
3104 * enter this state. After reaching IN_CHARGE, trustee
3105 * tries to execute the pending worklist until it's empty
3106 * and the state is set to BUTCHER, or the state is set
3107 * to RELEASE.
3109 * BUTCHER Command state which is set by the cpu callback after
3110 * the cpu has went down. Once this state is set trustee
3111 * knows that there will be no new works on the worklist
3112 * and once the worklist is empty it can proceed to
3113 * killing idle workers.
3115 * RELEASE Command state which is set by the cpu callback if the
3116 * cpu down has been canceled or it has come online
3117 * again. After recognizing this state, trustee stops
3118 * trying to drain or butcher and clears ROGUE, rebinds
3119 * all remaining workers back to the cpu and releases
3120 * manager role.
3122 * DONE Trustee will enter this state after BUTCHER or RELEASE
3123 * is complete.
3125 * trustee CPU draining
3126 * took over down complete
3127 * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
3128 * | | ^
3129 * | CPU is back online v return workers |
3130 * ----------------> RELEASE --------------
3134 * trustee_wait_event_timeout - timed event wait for trustee
3135 * @cond: condition to wait for
3136 * @timeout: timeout in jiffies
3138 * wait_event_timeout() for trustee to use. Handles locking and
3139 * checks for RELEASE request.
3141 * CONTEXT:
3142 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3143 * multiple times. To be used by trustee.
3145 * RETURNS:
3146 * Positive indicating left time if @cond is satisfied, 0 if timed
3147 * out, -1 if canceled.
3149 #define trustee_wait_event_timeout(cond, timeout) ({ \
3150 long __ret = (timeout); \
3151 while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \
3152 __ret) { \
3153 spin_unlock_irq(&gcwq->lock); \
3154 __wait_event_timeout(gcwq->trustee_wait, (cond) || \
3155 (gcwq->trustee_state == TRUSTEE_RELEASE), \
3156 __ret); \
3157 spin_lock_irq(&gcwq->lock); \
3159 gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \
3163 * trustee_wait_event - event wait for trustee
3164 * @cond: condition to wait for
3166 * wait_event() for trustee to use. Automatically handles locking and
3167 * checks for CANCEL request.
3169 * CONTEXT:
3170 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3171 * multiple times. To be used by trustee.
3173 * RETURNS:
3174 * 0 if @cond is satisfied, -1 if canceled.
3176 #define trustee_wait_event(cond) ({ \
3177 long __ret1; \
3178 __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
3179 __ret1 < 0 ? -1 : 0; \
3182 static int __cpuinit trustee_thread(void *__gcwq)
3184 struct global_cwq *gcwq = __gcwq;
3185 struct worker *worker;
3186 struct work_struct *work;
3187 struct hlist_node *pos;
3188 long rc;
3189 int i;
3191 BUG_ON(gcwq->cpu != smp_processor_id());
3193 spin_lock_irq(&gcwq->lock);
3195 * Claim the manager position and make all workers rogue.
3196 * Trustee must be bound to the target cpu and can't be
3197 * cancelled.
3199 BUG_ON(gcwq->cpu != smp_processor_id());
3200 rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS));
3201 BUG_ON(rc < 0);
3203 gcwq->flags |= GCWQ_MANAGING_WORKERS;
3205 list_for_each_entry(worker, &gcwq->idle_list, entry)
3206 worker->flags |= WORKER_ROGUE;
3208 for_each_busy_worker(worker, i, pos, gcwq)
3209 worker->flags |= WORKER_ROGUE;
3212 * Call schedule() so that we cross rq->lock and thus can
3213 * guarantee sched callbacks see the rogue flag. This is
3214 * necessary as scheduler callbacks may be invoked from other
3215 * cpus.
3217 spin_unlock_irq(&gcwq->lock);
3218 schedule();
3219 spin_lock_irq(&gcwq->lock);
3222 * Sched callbacks are disabled now. Zap nr_running. After
3223 * this, nr_running stays zero and need_more_worker() and
3224 * keep_working() are always true as long as the worklist is
3225 * not empty.
3227 atomic_set(get_gcwq_nr_running(gcwq->cpu), 0);
3229 spin_unlock_irq(&gcwq->lock);
3230 del_timer_sync(&gcwq->idle_timer);
3231 spin_lock_irq(&gcwq->lock);
3234 * We're now in charge. Notify and proceed to drain. We need
3235 * to keep the gcwq running during the whole CPU down
3236 * procedure as other cpu hotunplug callbacks may need to
3237 * flush currently running tasks.
3239 gcwq->trustee_state = TRUSTEE_IN_CHARGE;
3240 wake_up_all(&gcwq->trustee_wait);
3243 * The original cpu is in the process of dying and may go away
3244 * anytime now. When that happens, we and all workers would
3245 * be migrated to other cpus. Try draining any left work. We
3246 * want to get it over with ASAP - spam rescuers, wake up as
3247 * many idlers as necessary and create new ones till the
3248 * worklist is empty. Note that if the gcwq is frozen, there
3249 * may be frozen works in freezeable cwqs. Don't declare
3250 * completion while frozen.
3252 while (gcwq->nr_workers != gcwq->nr_idle ||
3253 gcwq->flags & GCWQ_FREEZING ||
3254 gcwq->trustee_state == TRUSTEE_IN_CHARGE) {
3255 int nr_works = 0;
3257 list_for_each_entry(work, &gcwq->worklist, entry) {
3258 send_mayday(work);
3259 nr_works++;
3262 list_for_each_entry(worker, &gcwq->idle_list, entry) {
3263 if (!nr_works--)
3264 break;
3265 wake_up_process(worker->task);
3268 if (need_to_create_worker(gcwq)) {
3269 spin_unlock_irq(&gcwq->lock);
3270 worker = create_worker(gcwq, false);
3271 spin_lock_irq(&gcwq->lock);
3272 if (worker) {
3273 worker->flags |= WORKER_ROGUE;
3274 start_worker(worker);
3278 /* give a breather */
3279 if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
3280 break;
3284 * Either all works have been scheduled and cpu is down, or
3285 * cpu down has already been canceled. Wait for and butcher
3286 * all workers till we're canceled.
3288 do {
3289 rc = trustee_wait_event(!list_empty(&gcwq->idle_list));
3290 while (!list_empty(&gcwq->idle_list))
3291 destroy_worker(list_first_entry(&gcwq->idle_list,
3292 struct worker, entry));
3293 } while (gcwq->nr_workers && rc >= 0);
3296 * At this point, either draining has completed and no worker
3297 * is left, or cpu down has been canceled or the cpu is being
3298 * brought back up. There shouldn't be any idle one left.
3299 * Tell the remaining busy ones to rebind once it finishes the
3300 * currently scheduled works by scheduling the rebind_work.
3302 WARN_ON(!list_empty(&gcwq->idle_list));
3304 for_each_busy_worker(worker, i, pos, gcwq) {
3305 struct work_struct *rebind_work = &worker->rebind_work;
3308 * Rebind_work may race with future cpu hotplug
3309 * operations. Use a separate flag to mark that
3310 * rebinding is scheduled.
3312 worker->flags |= WORKER_REBIND;
3313 worker->flags &= ~WORKER_ROGUE;
3315 /* queue rebind_work, wq doesn't matter, use the default one */
3316 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
3317 work_data_bits(rebind_work)))
3318 continue;
3320 debug_work_activate(rebind_work);
3321 insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
3322 worker->scheduled.next,
3323 work_color_to_flags(WORK_NO_COLOR));
3326 /* relinquish manager role */
3327 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
3329 /* notify completion */
3330 gcwq->trustee = NULL;
3331 gcwq->trustee_state = TRUSTEE_DONE;
3332 wake_up_all(&gcwq->trustee_wait);
3333 spin_unlock_irq(&gcwq->lock);
3334 return 0;
3338 * wait_trustee_state - wait for trustee to enter the specified state
3339 * @gcwq: gcwq the trustee of interest belongs to
3340 * @state: target state to wait for
3342 * Wait for the trustee to reach @state. DONE is already matched.
3344 * CONTEXT:
3345 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3346 * multiple times. To be used by cpu_callback.
3348 static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
3349 __releases(&gcwq->lock)
3350 __acquires(&gcwq->lock)
3352 if (!(gcwq->trustee_state == state ||
3353 gcwq->trustee_state == TRUSTEE_DONE)) {
3354 spin_unlock_irq(&gcwq->lock);
3355 __wait_event(gcwq->trustee_wait,
3356 gcwq->trustee_state == state ||
3357 gcwq->trustee_state == TRUSTEE_DONE);
3358 spin_lock_irq(&gcwq->lock);
3362 static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
3363 unsigned long action,
3364 void *hcpu)
3366 unsigned int cpu = (unsigned long)hcpu;
3367 struct global_cwq *gcwq = get_gcwq(cpu);
3368 struct task_struct *new_trustee = NULL;
3369 struct worker *uninitialized_var(new_worker);
3370 unsigned long flags;
3372 action &= ~CPU_TASKS_FROZEN;
3374 switch (action) {
3375 case CPU_DOWN_PREPARE:
3376 new_trustee = kthread_create(trustee_thread, gcwq,
3377 "workqueue_trustee/%d\n", cpu);
3378 if (IS_ERR(new_trustee))
3379 return notifier_from_errno(PTR_ERR(new_trustee));
3380 kthread_bind(new_trustee, cpu);
3381 /* fall through */
3382 case CPU_UP_PREPARE:
3383 BUG_ON(gcwq->first_idle);
3384 new_worker = create_worker(gcwq, false);
3385 if (!new_worker) {
3386 if (new_trustee)
3387 kthread_stop(new_trustee);
3388 return NOTIFY_BAD;
3392 /* some are called w/ irq disabled, don't disturb irq status */
3393 spin_lock_irqsave(&gcwq->lock, flags);
3395 switch (action) {
3396 case CPU_DOWN_PREPARE:
3397 /* initialize trustee and tell it to acquire the gcwq */
3398 BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE);
3399 gcwq->trustee = new_trustee;
3400 gcwq->trustee_state = TRUSTEE_START;
3401 wake_up_process(gcwq->trustee);
3402 wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);
3403 /* fall through */
3404 case CPU_UP_PREPARE:
3405 BUG_ON(gcwq->first_idle);
3406 gcwq->first_idle = new_worker;
3407 break;
3409 case CPU_DYING:
3411 * Before this, the trustee and all workers except for
3412 * the ones which are still executing works from
3413 * before the last CPU down must be on the cpu. After
3414 * this, they'll all be diasporas.
3416 gcwq->flags |= GCWQ_DISASSOCIATED;
3417 break;
3419 case CPU_POST_DEAD:
3420 gcwq->trustee_state = TRUSTEE_BUTCHER;
3421 /* fall through */
3422 case CPU_UP_CANCELED:
3423 destroy_worker(gcwq->first_idle);
3424 gcwq->first_idle = NULL;
3425 break;
3427 case CPU_DOWN_FAILED:
3428 case CPU_ONLINE:
3429 gcwq->flags &= ~GCWQ_DISASSOCIATED;
3430 if (gcwq->trustee_state != TRUSTEE_DONE) {
3431 gcwq->trustee_state = TRUSTEE_RELEASE;
3432 wake_up_process(gcwq->trustee);
3433 wait_trustee_state(gcwq, TRUSTEE_DONE);
3437 * Trustee is done and there might be no worker left.
3438 * Put the first_idle in and request a real manager to
3439 * take a look.
3441 spin_unlock_irq(&gcwq->lock);
3442 kthread_bind(gcwq->first_idle->task, cpu);
3443 spin_lock_irq(&gcwq->lock);
3444 gcwq->flags |= GCWQ_MANAGE_WORKERS;
3445 start_worker(gcwq->first_idle);
3446 gcwq->first_idle = NULL;
3447 break;
3450 spin_unlock_irqrestore(&gcwq->lock, flags);
3452 return notifier_from_errno(0);
3455 #ifdef CONFIG_SMP
3457 struct work_for_cpu {
3458 struct completion completion;
3459 long (*fn)(void *);
3460 void *arg;
3461 long ret;
3464 static int do_work_for_cpu(void *_wfc)
3466 struct work_for_cpu *wfc = _wfc;
3467 wfc->ret = wfc->fn(wfc->arg);
3468 complete(&wfc->completion);
3469 return 0;
3473 * work_on_cpu - run a function in user context on a particular cpu
3474 * @cpu: the cpu to run on
3475 * @fn: the function to run
3476 * @arg: the function arg
3478 * This will return the value @fn returns.
3479 * It is up to the caller to ensure that the cpu doesn't go offline.
3480 * The caller must not hold any locks which would prevent @fn from completing.
3482 long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
3484 struct task_struct *sub_thread;
3485 struct work_for_cpu wfc = {
3486 .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
3487 .fn = fn,
3488 .arg = arg,
3491 sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
3492 if (IS_ERR(sub_thread))
3493 return PTR_ERR(sub_thread);
3494 kthread_bind(sub_thread, cpu);
3495 wake_up_process(sub_thread);
3496 wait_for_completion(&wfc.completion);
3497 return wfc.ret;
3499 EXPORT_SYMBOL_GPL(work_on_cpu);
3500 #endif /* CONFIG_SMP */
3502 #ifdef CONFIG_FREEZER
3505 * freeze_workqueues_begin - begin freezing workqueues
3507 * Start freezing workqueues. After this function returns, all
3508 * freezeable workqueues will queue new works to their frozen_works
3509 * list instead of gcwq->worklist.
3511 * CONTEXT:
3512 * Grabs and releases workqueue_lock and gcwq->lock's.
3514 void freeze_workqueues_begin(void)
3516 unsigned int cpu;
3518 spin_lock(&workqueue_lock);
3520 BUG_ON(workqueue_freezing);
3521 workqueue_freezing = true;
3523 for_each_gcwq_cpu(cpu) {
3524 struct global_cwq *gcwq = get_gcwq(cpu);
3525 struct workqueue_struct *wq;
3527 spin_lock_irq(&gcwq->lock);
3529 BUG_ON(gcwq->flags & GCWQ_FREEZING);
3530 gcwq->flags |= GCWQ_FREEZING;
3532 list_for_each_entry(wq, &workqueues, list) {
3533 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3535 if (cwq && wq->flags & WQ_FREEZEABLE)
3536 cwq->max_active = 0;
3539 spin_unlock_irq(&gcwq->lock);
3542 spin_unlock(&workqueue_lock);
3546 * freeze_workqueues_busy - are freezeable workqueues still busy?
3548 * Check whether freezing is complete. This function must be called
3549 * between freeze_workqueues_begin() and thaw_workqueues().
3551 * CONTEXT:
3552 * Grabs and releases workqueue_lock.
3554 * RETURNS:
3555 * %true if some freezeable workqueues are still busy. %false if
3556 * freezing is complete.
3558 bool freeze_workqueues_busy(void)
3560 unsigned int cpu;
3561 bool busy = false;
3563 spin_lock(&workqueue_lock);
3565 BUG_ON(!workqueue_freezing);
3567 for_each_gcwq_cpu(cpu) {
3568 struct workqueue_struct *wq;
3570 * nr_active is monotonically decreasing. It's safe
3571 * to peek without lock.
3573 list_for_each_entry(wq, &workqueues, list) {
3574 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3576 if (!cwq || !(wq->flags & WQ_FREEZEABLE))
3577 continue;
3579 BUG_ON(cwq->nr_active < 0);
3580 if (cwq->nr_active) {
3581 busy = true;
3582 goto out_unlock;
3586 out_unlock:
3587 spin_unlock(&workqueue_lock);
3588 return busy;
3592 * thaw_workqueues - thaw workqueues
3594 * Thaw workqueues. Normal queueing is restored and all collected
3595 * frozen works are transferred to their respective gcwq worklists.
3597 * CONTEXT:
3598 * Grabs and releases workqueue_lock and gcwq->lock's.
3600 void thaw_workqueues(void)
3602 unsigned int cpu;
3604 spin_lock(&workqueue_lock);
3606 if (!workqueue_freezing)
3607 goto out_unlock;
3609 for_each_gcwq_cpu(cpu) {
3610 struct global_cwq *gcwq = get_gcwq(cpu);
3611 struct workqueue_struct *wq;
3613 spin_lock_irq(&gcwq->lock);
3615 BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
3616 gcwq->flags &= ~GCWQ_FREEZING;
3618 list_for_each_entry(wq, &workqueues, list) {
3619 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3621 if (!cwq || !(wq->flags & WQ_FREEZEABLE))
3622 continue;
3624 /* restore max_active and repopulate worklist */
3625 cwq->max_active = wq->saved_max_active;
3627 while (!list_empty(&cwq->delayed_works) &&
3628 cwq->nr_active < cwq->max_active)
3629 cwq_activate_first_delayed(cwq);
3632 wake_up_worker(gcwq);
3634 spin_unlock_irq(&gcwq->lock);
3637 workqueue_freezing = false;
3638 out_unlock:
3639 spin_unlock(&workqueue_lock);
3641 #endif /* CONFIG_FREEZER */
3643 static int __init init_workqueues(void)
3645 unsigned int cpu;
3646 int i;
3648 cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
3650 /* initialize gcwqs */
3651 for_each_gcwq_cpu(cpu) {
3652 struct global_cwq *gcwq = get_gcwq(cpu);
3654 spin_lock_init(&gcwq->lock);
3655 INIT_LIST_HEAD(&gcwq->worklist);
3656 gcwq->cpu = cpu;
3657 gcwq->flags |= GCWQ_DISASSOCIATED;
3659 INIT_LIST_HEAD(&gcwq->idle_list);
3660 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
3661 INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
3663 init_timer_deferrable(&gcwq->idle_timer);
3664 gcwq->idle_timer.function = idle_worker_timeout;
3665 gcwq->idle_timer.data = (unsigned long)gcwq;
3667 setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout,
3668 (unsigned long)gcwq);
3670 ida_init(&gcwq->worker_ida);
3672 gcwq->trustee_state = TRUSTEE_DONE;
3673 init_waitqueue_head(&gcwq->trustee_wait);
3676 /* create the initial worker */
3677 for_each_online_gcwq_cpu(cpu) {
3678 struct global_cwq *gcwq = get_gcwq(cpu);
3679 struct worker *worker;
3681 if (cpu != WORK_CPU_UNBOUND)
3682 gcwq->flags &= ~GCWQ_DISASSOCIATED;
3683 worker = create_worker(gcwq, true);
3684 BUG_ON(!worker);
3685 spin_lock_irq(&gcwq->lock);
3686 start_worker(worker);
3687 spin_unlock_irq(&gcwq->lock);
3690 system_wq = alloc_workqueue("events", 0, 0);
3691 system_long_wq = alloc_workqueue("events_long", 0, 0);
3692 system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
3693 system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
3694 WQ_UNBOUND_MAX_ACTIVE);
3695 BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);
3696 return 0;
3698 early_initcall(init_workqueues);