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>
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/export.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>
44 #include <linux/jhash.h>
45 #include <linux/hashtable.h>
46 #include <linux/rculist.h>
47 #include <linux/nodemask.h>
48 #include <linux/moduleparam.h>
49 #include <linux/uaccess.h>
51 #include "workqueue_internal.h"
57 * A bound pool is either associated or disassociated with its CPU.
58 * While associated (!DISASSOCIATED), all workers are bound to the
59 * CPU and none has %WORKER_UNBOUND set and concurrency management
62 * While DISASSOCIATED, the cpu may be offline and all workers have
63 * %WORKER_UNBOUND set and concurrency management disabled, and may
64 * be executing on any CPU. The pool behaves as an unbound one.
66 * Note that DISASSOCIATED should be flipped only while holding
67 * manager_mutex to avoid changing binding state while
68 * create_worker() is in progress.
70 POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
71 POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
72 POOL_FREEZING = 1 << 3, /* freeze in progress */
75 WORKER_STARTED = 1 << 0, /* started */
76 WORKER_DIE = 1 << 1, /* die die die */
77 WORKER_IDLE = 1 << 2, /* is idle */
78 WORKER_PREP = 1 << 3, /* preparing to run works */
79 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
80 WORKER_UNBOUND = 1 << 7, /* worker is unbound */
81 WORKER_REBOUND = 1 << 8, /* worker was rebound */
83 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE |
84 WORKER_UNBOUND | WORKER_REBOUND,
86 NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
88 UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
89 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
91 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
92 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
94 MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
95 /* call for help after 10ms
97 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
98 CREATE_COOLDOWN = HZ, /* time to breath after fail */
101 * Rescue workers are used only on emergencies and shared by
102 * all cpus. Give -20.
104 RESCUER_NICE_LEVEL = -20,
105 HIGHPRI_NICE_LEVEL = -20,
111 * Structure fields follow one of the following exclusion rules.
113 * I: Modifiable by initialization/destruction paths and read-only for
116 * P: Preemption protected. Disabling preemption is enough and should
117 * only be modified and accessed from the local cpu.
119 * L: pool->lock protected. Access with pool->lock held.
121 * X: During normal operation, modification requires pool->lock and should
122 * be done only from local cpu. Either disabling preemption on local
123 * cpu or grabbing pool->lock is enough for read access. If
124 * POOL_DISASSOCIATED is set, it's identical to L.
126 * MG: pool->manager_mutex and pool->lock protected. Writes require both
127 * locks. Reads can happen under either lock.
129 * PL: wq_pool_mutex protected.
131 * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
133 * WQ: wq->mutex protected.
135 * WR: wq->mutex protected for writes. Sched-RCU protected for reads.
137 * MD: wq_mayday_lock protected.
140 /* struct worker is defined in workqueue_internal.h */
143 spinlock_t lock; /* the pool lock */
144 int cpu; /* I: the associated cpu */
145 int node; /* I: the associated node ID */
146 int id; /* I: pool ID */
147 unsigned int flags; /* X: flags */
149 struct list_head worklist; /* L: list of pending works */
150 int nr_workers; /* L: total number of workers */
152 /* nr_idle includes the ones off idle_list for rebinding */
153 int nr_idle; /* L: currently idle ones */
155 struct list_head idle_list; /* X: list of idle workers */
156 struct timer_list idle_timer; /* L: worker idle timeout */
157 struct timer_list mayday_timer; /* L: SOS timer for workers */
159 /* a workers is either on busy_hash or idle_list, or the manager */
160 DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
161 /* L: hash of busy workers */
163 /* see manage_workers() for details on the two manager mutexes */
164 struct mutex manager_arb; /* manager arbitration */
165 struct mutex manager_mutex; /* manager exclusion */
166 struct idr worker_idr; /* MG: worker IDs and iteration */
168 struct workqueue_attrs *attrs; /* I: worker attributes */
169 struct hlist_node hash_node; /* PL: unbound_pool_hash node */
170 int refcnt; /* PL: refcnt for unbound pools */
173 * The current concurrency level. As it's likely to be accessed
174 * from other CPUs during try_to_wake_up(), put it in a separate
177 atomic_t nr_running ____cacheline_aligned_in_smp;
180 * Destruction of pool is sched-RCU protected to allow dereferences
181 * from get_work_pool().
184 } ____cacheline_aligned_in_smp;
187 * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
188 * of work_struct->data are used for flags and the remaining high bits
189 * point to the pwq; thus, pwqs need to be aligned at two's power of the
190 * number of flag bits.
192 struct pool_workqueue {
193 struct worker_pool *pool; /* I: the associated pool */
194 struct workqueue_struct *wq; /* I: the owning workqueue */
195 int work_color; /* L: current color */
196 int flush_color; /* L: flushing color */
197 int refcnt; /* L: reference count */
198 int nr_in_flight[WORK_NR_COLORS];
199 /* L: nr of in_flight works */
200 int nr_active; /* L: nr of active works */
201 int max_active; /* L: max active works */
202 struct list_head delayed_works; /* L: delayed works */
203 struct list_head pwqs_node; /* WR: node on wq->pwqs */
204 struct list_head mayday_node; /* MD: node on wq->maydays */
207 * Release of unbound pwq is punted to system_wq. See put_pwq()
208 * and pwq_unbound_release_workfn() for details. pool_workqueue
209 * itself is also sched-RCU protected so that the first pwq can be
210 * determined without grabbing wq->mutex.
212 struct work_struct unbound_release_work;
214 } __aligned(1 << WORK_STRUCT_FLAG_BITS);
217 * Structure used to wait for workqueue flush.
220 struct list_head list; /* WQ: list of flushers */
221 int flush_color; /* WQ: flush color waiting for */
222 struct completion done; /* flush completion */
228 * The externally visible workqueue. It relays the issued work items to
229 * the appropriate worker_pool through its pool_workqueues.
231 struct workqueue_struct {
232 struct list_head pwqs; /* WR: all pwqs of this wq */
233 struct list_head list; /* PL: list of all workqueues */
235 struct mutex mutex; /* protects this wq */
236 int work_color; /* WQ: current work color */
237 int flush_color; /* WQ: current flush color */
238 atomic_t nr_pwqs_to_flush; /* flush in progress */
239 struct wq_flusher *first_flusher; /* WQ: first flusher */
240 struct list_head flusher_queue; /* WQ: flush waiters */
241 struct list_head flusher_overflow; /* WQ: flush overflow list */
243 struct list_head maydays; /* MD: pwqs requesting rescue */
244 struct worker *rescuer; /* I: rescue worker */
246 int nr_drainers; /* WQ: drain in progress */
247 int saved_max_active; /* WQ: saved pwq max_active */
249 struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */
250 struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */
253 struct wq_device *wq_dev; /* I: for sysfs interface */
255 #ifdef CONFIG_LOCKDEP
256 struct lockdep_map lockdep_map;
258 char name[WQ_NAME_LEN]; /* I: workqueue name */
260 /* hot fields used during command issue, aligned to cacheline */
261 unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
262 struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */
263 struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */
266 static struct kmem_cache *pwq_cache;
268 static int wq_numa_tbl_len; /* highest possible NUMA node id + 1 */
269 static cpumask_var_t *wq_numa_possible_cpumask;
270 /* possible CPUs of each node */
272 static bool wq_disable_numa;
273 module_param_named(disable_numa, wq_disable_numa, bool, 0444);
275 /* see the comment above the definition of WQ_POWER_EFFICIENT */
276 #ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
277 static bool wq_power_efficient = true;
279 static bool wq_power_efficient;
282 module_param_named(power_efficient, wq_power_efficient, bool, 0444);
284 static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
286 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
287 static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
289 static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
290 static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
292 static LIST_HEAD(workqueues); /* PL: list of all workqueues */
293 static bool workqueue_freezing; /* PL: have wqs started freezing? */
295 /* the per-cpu worker pools */
296 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
299 static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
301 /* PL: hash of all unbound pools keyed by pool->attrs */
302 static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
304 /* I: attributes used when instantiating standard unbound pools on demand */
305 static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
307 struct workqueue_struct *system_wq __read_mostly;
308 EXPORT_SYMBOL_GPL(system_wq);
309 struct workqueue_struct *system_highpri_wq __read_mostly;
310 EXPORT_SYMBOL_GPL(system_highpri_wq);
311 struct workqueue_struct *system_long_wq __read_mostly;
312 EXPORT_SYMBOL_GPL(system_long_wq);
313 struct workqueue_struct *system_unbound_wq __read_mostly;
314 EXPORT_SYMBOL_GPL(system_unbound_wq);
315 struct workqueue_struct *system_freezable_wq __read_mostly;
316 EXPORT_SYMBOL_GPL(system_freezable_wq);
318 static int worker_thread(void *__worker);
319 static void copy_workqueue_attrs(struct workqueue_attrs *to,
320 const struct workqueue_attrs *from);
322 #define CREATE_TRACE_POINTS
323 #include <trace/events/workqueue.h>
325 #define assert_rcu_or_pool_mutex() \
326 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
327 lockdep_is_held(&wq_pool_mutex), \
328 "sched RCU or wq_pool_mutex should be held")
330 #define assert_rcu_or_wq_mutex(wq) \
331 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
332 lockdep_is_held(&wq->mutex), \
333 "sched RCU or wq->mutex should be held")
335 #ifdef CONFIG_LOCKDEP
336 #define assert_manager_or_pool_lock(pool) \
337 WARN_ONCE(debug_locks && \
338 !lockdep_is_held(&(pool)->manager_mutex) && \
339 !lockdep_is_held(&(pool)->lock), \
340 "pool->manager_mutex or ->lock should be held")
342 #define assert_manager_or_pool_lock(pool) do { } while (0)
345 #define for_each_cpu_worker_pool(pool, cpu) \
346 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
347 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
351 * for_each_pool - iterate through all worker_pools in the system
352 * @pool: iteration cursor
353 * @pi: integer used for iteration
355 * This must be called either with wq_pool_mutex held or sched RCU read
356 * locked. If the pool needs to be used beyond the locking in effect, the
357 * caller is responsible for guaranteeing that the pool stays online.
359 * The if/else clause exists only for the lockdep assertion and can be
362 #define for_each_pool(pool, pi) \
363 idr_for_each_entry(&worker_pool_idr, pool, pi) \
364 if (({ assert_rcu_or_pool_mutex(); false; })) { } \
368 * for_each_pool_worker - iterate through all workers of a worker_pool
369 * @worker: iteration cursor
370 * @wi: integer used for iteration
371 * @pool: worker_pool to iterate workers of
373 * This must be called with either @pool->manager_mutex or ->lock held.
375 * The if/else clause exists only for the lockdep assertion and can be
378 #define for_each_pool_worker(worker, wi, pool) \
379 idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \
380 if (({ assert_manager_or_pool_lock((pool)); false; })) { } \
384 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
385 * @pwq: iteration cursor
386 * @wq: the target workqueue
388 * This must be called either with wq->mutex held or sched RCU read locked.
389 * If the pwq needs to be used beyond the locking in effect, the caller is
390 * responsible for guaranteeing that the pwq stays online.
392 * The if/else clause exists only for the lockdep assertion and can be
395 #define for_each_pwq(pwq, wq) \
396 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
397 if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
400 #ifdef CONFIG_DEBUG_OBJECTS_WORK
402 static struct debug_obj_descr work_debug_descr;
404 static void *work_debug_hint(void *addr)
406 return ((struct work_struct *) addr)->func;
410 * fixup_init is called when:
411 * - an active object is initialized
413 static int work_fixup_init(void *addr, enum debug_obj_state state)
415 struct work_struct *work = addr;
418 case ODEBUG_STATE_ACTIVE:
419 cancel_work_sync(work);
420 debug_object_init(work, &work_debug_descr);
428 * fixup_activate is called when:
429 * - an active object is activated
430 * - an unknown object is activated (might be a statically initialized object)
432 static int work_fixup_activate(void *addr, enum debug_obj_state state)
434 struct work_struct *work = addr;
438 case ODEBUG_STATE_NOTAVAILABLE:
440 * This is not really a fixup. The work struct was
441 * statically initialized. We just make sure that it
442 * is tracked in the object tracker.
444 if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
445 debug_object_init(work, &work_debug_descr);
446 debug_object_activate(work, &work_debug_descr);
452 case ODEBUG_STATE_ACTIVE:
461 * fixup_free is called when:
462 * - an active object is freed
464 static int work_fixup_free(void *addr, enum debug_obj_state state)
466 struct work_struct *work = addr;
469 case ODEBUG_STATE_ACTIVE:
470 cancel_work_sync(work);
471 debug_object_free(work, &work_debug_descr);
478 static struct debug_obj_descr work_debug_descr = {
479 .name = "work_struct",
480 .debug_hint = work_debug_hint,
481 .fixup_init = work_fixup_init,
482 .fixup_activate = work_fixup_activate,
483 .fixup_free = work_fixup_free,
486 static inline void debug_work_activate(struct work_struct *work)
488 debug_object_activate(work, &work_debug_descr);
491 static inline void debug_work_deactivate(struct work_struct *work)
493 debug_object_deactivate(work, &work_debug_descr);
496 void __init_work(struct work_struct *work, int onstack)
499 debug_object_init_on_stack(work, &work_debug_descr);
501 debug_object_init(work, &work_debug_descr);
503 EXPORT_SYMBOL_GPL(__init_work);
505 void destroy_work_on_stack(struct work_struct *work)
507 debug_object_free(work, &work_debug_descr);
509 EXPORT_SYMBOL_GPL(destroy_work_on_stack);
512 static inline void debug_work_activate(struct work_struct *work) { }
513 static inline void debug_work_deactivate(struct work_struct *work) { }
516 /* allocate ID and assign it to @pool */
517 static int worker_pool_assign_id(struct worker_pool *pool)
521 lockdep_assert_held(&wq_pool_mutex);
523 ret = idr_alloc(&worker_pool_idr, pool, 0, 0, GFP_KERNEL);
532 * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
533 * @wq: the target workqueue
536 * This must be called either with pwq_lock held or sched RCU read locked.
537 * If the pwq needs to be used beyond the locking in effect, the caller is
538 * responsible for guaranteeing that the pwq stays online.
540 static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq,
543 assert_rcu_or_wq_mutex(wq);
544 return rcu_dereference_raw(wq->numa_pwq_tbl[node]);
547 static unsigned int work_color_to_flags(int color)
549 return color << WORK_STRUCT_COLOR_SHIFT;
552 static int get_work_color(struct work_struct *work)
554 return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
555 ((1 << WORK_STRUCT_COLOR_BITS) - 1);
558 static int work_next_color(int color)
560 return (color + 1) % WORK_NR_COLORS;
564 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
565 * contain the pointer to the queued pwq. Once execution starts, the flag
566 * is cleared and the high bits contain OFFQ flags and pool ID.
568 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
569 * and clear_work_data() can be used to set the pwq, pool or clear
570 * work->data. These functions should only be called while the work is
571 * owned - ie. while the PENDING bit is set.
573 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
574 * corresponding to a work. Pool is available once the work has been
575 * queued anywhere after initialization until it is sync canceled. pwq is
576 * available only while the work item is queued.
578 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
579 * canceled. While being canceled, a work item may have its PENDING set
580 * but stay off timer and worklist for arbitrarily long and nobody should
581 * try to steal the PENDING bit.
583 static inline void set_work_data(struct work_struct *work, unsigned long data,
586 WARN_ON_ONCE(!work_pending(work));
587 atomic_long_set(&work->data, data | flags | work_static(work));
590 static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq,
591 unsigned long extra_flags)
593 set_work_data(work, (unsigned long)pwq,
594 WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags);
597 static void set_work_pool_and_keep_pending(struct work_struct *work,
600 set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
601 WORK_STRUCT_PENDING);
604 static void set_work_pool_and_clear_pending(struct work_struct *work,
608 * The following wmb is paired with the implied mb in
609 * test_and_set_bit(PENDING) and ensures all updates to @work made
610 * here are visible to and precede any updates by the next PENDING
614 set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
617 static void clear_work_data(struct work_struct *work)
619 smp_wmb(); /* see set_work_pool_and_clear_pending() */
620 set_work_data(work, WORK_STRUCT_NO_POOL, 0);
623 static struct pool_workqueue *get_work_pwq(struct work_struct *work)
625 unsigned long data = atomic_long_read(&work->data);
627 if (data & WORK_STRUCT_PWQ)
628 return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
634 * get_work_pool - return the worker_pool a given work was associated with
635 * @work: the work item of interest
637 * Return the worker_pool @work was last associated with. %NULL if none.
639 * Pools are created and destroyed under wq_pool_mutex, and allows read
640 * access under sched-RCU read lock. As such, this function should be
641 * called under wq_pool_mutex or with preemption disabled.
643 * All fields of the returned pool are accessible as long as the above
644 * mentioned locking is in effect. If the returned pool needs to be used
645 * beyond the critical section, the caller is responsible for ensuring the
646 * returned pool is and stays online.
648 static struct worker_pool *get_work_pool(struct work_struct *work)
650 unsigned long data = atomic_long_read(&work->data);
653 assert_rcu_or_pool_mutex();
655 if (data & WORK_STRUCT_PWQ)
656 return ((struct pool_workqueue *)
657 (data & WORK_STRUCT_WQ_DATA_MASK))->pool;
659 pool_id = data >> WORK_OFFQ_POOL_SHIFT;
660 if (pool_id == WORK_OFFQ_POOL_NONE)
663 return idr_find(&worker_pool_idr, pool_id);
667 * get_work_pool_id - return the worker pool ID a given work is associated with
668 * @work: the work item of interest
670 * Return the worker_pool ID @work was last associated with.
671 * %WORK_OFFQ_POOL_NONE if none.
673 static int get_work_pool_id(struct work_struct *work)
675 unsigned long data = atomic_long_read(&work->data);
677 if (data & WORK_STRUCT_PWQ)
678 return ((struct pool_workqueue *)
679 (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
681 return data >> WORK_OFFQ_POOL_SHIFT;
684 static void mark_work_canceling(struct work_struct *work)
686 unsigned long pool_id = get_work_pool_id(work);
688 pool_id <<= WORK_OFFQ_POOL_SHIFT;
689 set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
692 static bool work_is_canceling(struct work_struct *work)
694 unsigned long data = atomic_long_read(&work->data);
696 return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
700 * Policy functions. These define the policies on how the global worker
701 * pools are managed. Unless noted otherwise, these functions assume that
702 * they're being called with pool->lock held.
705 static bool __need_more_worker(struct worker_pool *pool)
707 return !atomic_read(&pool->nr_running);
711 * Need to wake up a worker? Called from anything but currently
714 * Note that, because unbound workers never contribute to nr_running, this
715 * function will always return %true for unbound pools as long as the
716 * worklist isn't empty.
718 static bool need_more_worker(struct worker_pool *pool)
720 return !list_empty(&pool->worklist) && __need_more_worker(pool);
723 /* Can I start working? Called from busy but !running workers. */
724 static bool may_start_working(struct worker_pool *pool)
726 return pool->nr_idle;
729 /* Do I need to keep working? Called from currently running workers. */
730 static bool keep_working(struct worker_pool *pool)
732 return !list_empty(&pool->worklist) &&
733 atomic_read(&pool->nr_running) <= 1;
736 /* Do we need a new worker? Called from manager. */
737 static bool need_to_create_worker(struct worker_pool *pool)
739 return need_more_worker(pool) && !may_start_working(pool);
742 /* Do I need to be the manager? */
743 static bool need_to_manage_workers(struct worker_pool *pool)
745 return need_to_create_worker(pool) ||
746 (pool->flags & POOL_MANAGE_WORKERS);
749 /* Do we have too many workers and should some go away? */
750 static bool too_many_workers(struct worker_pool *pool)
752 bool managing = mutex_is_locked(&pool->manager_arb);
753 int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
754 int nr_busy = pool->nr_workers - nr_idle;
757 * nr_idle and idle_list may disagree if idle rebinding is in
758 * progress. Never return %true if idle_list is empty.
760 if (list_empty(&pool->idle_list))
763 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
770 /* Return the first worker. Safe with preemption disabled */
771 static struct worker *first_worker(struct worker_pool *pool)
773 if (unlikely(list_empty(&pool->idle_list)))
776 return list_first_entry(&pool->idle_list, struct worker, entry);
780 * wake_up_worker - wake up an idle worker
781 * @pool: worker pool to wake worker from
783 * Wake up the first idle worker of @pool.
786 * spin_lock_irq(pool->lock).
788 static void wake_up_worker(struct worker_pool *pool)
790 struct worker *worker = first_worker(pool);
793 wake_up_process(worker->task);
797 * wq_worker_waking_up - a worker is waking up
798 * @task: task waking up
799 * @cpu: CPU @task is waking up to
801 * This function is called during try_to_wake_up() when a worker is
805 * spin_lock_irq(rq->lock)
807 void wq_worker_waking_up(struct task_struct *task, int cpu)
809 struct worker *worker = kthread_data(task);
811 if (!(worker->flags & WORKER_NOT_RUNNING)) {
812 WARN_ON_ONCE(worker->pool->cpu != cpu);
813 atomic_inc(&worker->pool->nr_running);
818 * wq_worker_sleeping - a worker is going to sleep
819 * @task: task going to sleep
820 * @cpu: CPU in question, must be the current CPU number
822 * This function is called during schedule() when a busy worker is
823 * going to sleep. Worker on the same cpu can be woken up by
824 * returning pointer to its task.
827 * spin_lock_irq(rq->lock)
830 * Worker task on @cpu to wake up, %NULL if none.
832 struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu)
834 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
835 struct worker_pool *pool;
838 * Rescuers, which may not have all the fields set up like normal
839 * workers, also reach here, let's not access anything before
840 * checking NOT_RUNNING.
842 if (worker->flags & WORKER_NOT_RUNNING)
847 /* this can only happen on the local cpu */
848 if (WARN_ON_ONCE(cpu != raw_smp_processor_id()))
852 * The counterpart of the following dec_and_test, implied mb,
853 * worklist not empty test sequence is in insert_work().
854 * Please read comment there.
856 * NOT_RUNNING is clear. This means that we're bound to and
857 * running on the local cpu w/ rq lock held and preemption
858 * disabled, which in turn means that none else could be
859 * manipulating idle_list, so dereferencing idle_list without pool
862 if (atomic_dec_and_test(&pool->nr_running) &&
863 !list_empty(&pool->worklist))
864 to_wakeup = first_worker(pool);
865 return to_wakeup ? to_wakeup->task : NULL;
869 * worker_set_flags - set worker flags and adjust nr_running accordingly
871 * @flags: flags to set
872 * @wakeup: wakeup an idle worker if necessary
874 * Set @flags in @worker->flags and adjust nr_running accordingly. If
875 * nr_running becomes zero and @wakeup is %true, an idle worker is
879 * spin_lock_irq(pool->lock)
881 static inline void worker_set_flags(struct worker *worker, unsigned int flags,
884 struct worker_pool *pool = worker->pool;
886 WARN_ON_ONCE(worker->task != current);
889 * If transitioning into NOT_RUNNING, adjust nr_running and
890 * wake up an idle worker as necessary if requested by
893 if ((flags & WORKER_NOT_RUNNING) &&
894 !(worker->flags & WORKER_NOT_RUNNING)) {
896 if (atomic_dec_and_test(&pool->nr_running) &&
897 !list_empty(&pool->worklist))
898 wake_up_worker(pool);
900 atomic_dec(&pool->nr_running);
903 worker->flags |= flags;
907 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
909 * @flags: flags to clear
911 * Clear @flags in @worker->flags and adjust nr_running accordingly.
914 * spin_lock_irq(pool->lock)
916 static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
918 struct worker_pool *pool = worker->pool;
919 unsigned int oflags = worker->flags;
921 WARN_ON_ONCE(worker->task != current);
923 worker->flags &= ~flags;
926 * If transitioning out of NOT_RUNNING, increment nr_running. Note
927 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
928 * of multiple flags, not a single flag.
930 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
931 if (!(worker->flags & WORKER_NOT_RUNNING))
932 atomic_inc(&pool->nr_running);
936 * find_worker_executing_work - find worker which is executing a work
937 * @pool: pool of interest
938 * @work: work to find worker for
940 * Find a worker which is executing @work on @pool by searching
941 * @pool->busy_hash which is keyed by the address of @work. For a worker
942 * to match, its current execution should match the address of @work and
943 * its work function. This is to avoid unwanted dependency between
944 * unrelated work executions through a work item being recycled while still
947 * This is a bit tricky. A work item may be freed once its execution
948 * starts and nothing prevents the freed area from being recycled for
949 * another work item. If the same work item address ends up being reused
950 * before the original execution finishes, workqueue will identify the
951 * recycled work item as currently executing and make it wait until the
952 * current execution finishes, introducing an unwanted dependency.
954 * This function checks the work item address and work function to avoid
955 * false positives. Note that this isn't complete as one may construct a
956 * work function which can introduce dependency onto itself through a
957 * recycled work item. Well, if somebody wants to shoot oneself in the
958 * foot that badly, there's only so much we can do, and if such deadlock
959 * actually occurs, it should be easy to locate the culprit work function.
962 * spin_lock_irq(pool->lock).
965 * Pointer to worker which is executing @work if found, NULL
968 static struct worker *find_worker_executing_work(struct worker_pool *pool,
969 struct work_struct *work)
971 struct worker *worker;
973 hash_for_each_possible(pool->busy_hash, worker, hentry,
975 if (worker->current_work == work &&
976 worker->current_func == work->func)
983 * move_linked_works - move linked works to a list
984 * @work: start of series of works to be scheduled
985 * @head: target list to append @work to
986 * @nextp: out paramter for nested worklist walking
988 * Schedule linked works starting from @work to @head. Work series to
989 * be scheduled starts at @work and includes any consecutive work with
990 * WORK_STRUCT_LINKED set in its predecessor.
992 * If @nextp is not NULL, it's updated to point to the next work of
993 * the last scheduled work. This allows move_linked_works() to be
994 * nested inside outer list_for_each_entry_safe().
997 * spin_lock_irq(pool->lock).
999 static void move_linked_works(struct work_struct *work, struct list_head *head,
1000 struct work_struct **nextp)
1002 struct work_struct *n;
1005 * Linked worklist will always end before the end of the list,
1006 * use NULL for list head.
1008 list_for_each_entry_safe_from(work, n, NULL, entry) {
1009 list_move_tail(&work->entry, head);
1010 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1015 * If we're already inside safe list traversal and have moved
1016 * multiple works to the scheduled queue, the next position
1017 * needs to be updated.
1024 * get_pwq - get an extra reference on the specified pool_workqueue
1025 * @pwq: pool_workqueue to get
1027 * Obtain an extra reference on @pwq. The caller should guarantee that
1028 * @pwq has positive refcnt and be holding the matching pool->lock.
1030 static void get_pwq(struct pool_workqueue *pwq)
1032 lockdep_assert_held(&pwq->pool->lock);
1033 WARN_ON_ONCE(pwq->refcnt <= 0);
1038 * put_pwq - put a pool_workqueue reference
1039 * @pwq: pool_workqueue to put
1041 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1042 * destruction. The caller should be holding the matching pool->lock.
1044 static void put_pwq(struct pool_workqueue *pwq)
1046 lockdep_assert_held(&pwq->pool->lock);
1047 if (likely(--pwq->refcnt))
1049 if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND)))
1052 * @pwq can't be released under pool->lock, bounce to
1053 * pwq_unbound_release_workfn(). This never recurses on the same
1054 * pool->lock as this path is taken only for unbound workqueues and
1055 * the release work item is scheduled on a per-cpu workqueue. To
1056 * avoid lockdep warning, unbound pool->locks are given lockdep
1057 * subclass of 1 in get_unbound_pool().
1059 schedule_work(&pwq->unbound_release_work);
1063 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1064 * @pwq: pool_workqueue to put (can be %NULL)
1066 * put_pwq() with locking. This function also allows %NULL @pwq.
1068 static void put_pwq_unlocked(struct pool_workqueue *pwq)
1072 * As both pwqs and pools are sched-RCU protected, the
1073 * following lock operations are safe.
1075 spin_lock_irq(&pwq->pool->lock);
1077 spin_unlock_irq(&pwq->pool->lock);
1081 static void pwq_activate_delayed_work(struct work_struct *work)
1083 struct pool_workqueue *pwq = get_work_pwq(work);
1085 trace_workqueue_activate_work(work);
1086 move_linked_works(work, &pwq->pool->worklist, NULL);
1087 __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
1091 static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
1093 struct work_struct *work = list_first_entry(&pwq->delayed_works,
1094 struct work_struct, entry);
1096 pwq_activate_delayed_work(work);
1100 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1101 * @pwq: pwq of interest
1102 * @color: color of work which left the queue
1104 * A work either has completed or is removed from pending queue,
1105 * decrement nr_in_flight of its pwq and handle workqueue flushing.
1108 * spin_lock_irq(pool->lock).
1110 static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
1112 /* uncolored work items don't participate in flushing or nr_active */
1113 if (color == WORK_NO_COLOR)
1116 pwq->nr_in_flight[color]--;
1119 if (!list_empty(&pwq->delayed_works)) {
1120 /* one down, submit a delayed one */
1121 if (pwq->nr_active < pwq->max_active)
1122 pwq_activate_first_delayed(pwq);
1125 /* is flush in progress and are we at the flushing tip? */
1126 if (likely(pwq->flush_color != color))
1129 /* are there still in-flight works? */
1130 if (pwq->nr_in_flight[color])
1133 /* this pwq is done, clear flush_color */
1134 pwq->flush_color = -1;
1137 * If this was the last pwq, wake up the first flusher. It
1138 * will handle the rest.
1140 if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
1141 complete(&pwq->wq->first_flusher->done);
1147 * try_to_grab_pending - steal work item from worklist and disable irq
1148 * @work: work item to steal
1149 * @is_dwork: @work is a delayed_work
1150 * @flags: place to store irq state
1152 * Try to grab PENDING bit of @work. This function can handle @work in any
1153 * stable state - idle, on timer or on worklist. Return values are
1155 * 1 if @work was pending and we successfully stole PENDING
1156 * 0 if @work was idle and we claimed PENDING
1157 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1158 * -ENOENT if someone else is canceling @work, this state may persist
1159 * for arbitrarily long
1161 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1162 * interrupted while holding PENDING and @work off queue, irq must be
1163 * disabled on entry. This, combined with delayed_work->timer being
1164 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1166 * On successful return, >= 0, irq is disabled and the caller is
1167 * responsible for releasing it using local_irq_restore(*@flags).
1169 * This function is safe to call from any context including IRQ handler.
1171 static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
1172 unsigned long *flags)
1174 struct worker_pool *pool;
1175 struct pool_workqueue *pwq;
1177 local_irq_save(*flags);
1179 /* try to steal the timer if it exists */
1181 struct delayed_work *dwork = to_delayed_work(work);
1184 * dwork->timer is irqsafe. If del_timer() fails, it's
1185 * guaranteed that the timer is not queued anywhere and not
1186 * running on the local CPU.
1188 if (likely(del_timer(&dwork->timer)))
1192 /* try to claim PENDING the normal way */
1193 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
1197 * The queueing is in progress, or it is already queued. Try to
1198 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1200 pool = get_work_pool(work);
1204 spin_lock(&pool->lock);
1206 * work->data is guaranteed to point to pwq only while the work
1207 * item is queued on pwq->wq, and both updating work->data to point
1208 * to pwq on queueing and to pool on dequeueing are done under
1209 * pwq->pool->lock. This in turn guarantees that, if work->data
1210 * points to pwq which is associated with a locked pool, the work
1211 * item is currently queued on that pool.
1213 pwq = get_work_pwq(work);
1214 if (pwq && pwq->pool == pool) {
1215 debug_work_deactivate(work);
1218 * A delayed work item cannot be grabbed directly because
1219 * it might have linked NO_COLOR work items which, if left
1220 * on the delayed_list, will confuse pwq->nr_active
1221 * management later on and cause stall. Make sure the work
1222 * item is activated before grabbing.
1224 if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
1225 pwq_activate_delayed_work(work);
1227 list_del_init(&work->entry);
1228 pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work));
1230 /* work->data points to pwq iff queued, point to pool */
1231 set_work_pool_and_keep_pending(work, pool->id);
1233 spin_unlock(&pool->lock);
1236 spin_unlock(&pool->lock);
1238 local_irq_restore(*flags);
1239 if (work_is_canceling(work))
1246 * insert_work - insert a work into a pool
1247 * @pwq: pwq @work belongs to
1248 * @work: work to insert
1249 * @head: insertion point
1250 * @extra_flags: extra WORK_STRUCT_* flags to set
1252 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1253 * work_struct flags.
1256 * spin_lock_irq(pool->lock).
1258 static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
1259 struct list_head *head, unsigned int extra_flags)
1261 struct worker_pool *pool = pwq->pool;
1263 /* we own @work, set data and link */
1264 set_work_pwq(work, pwq, extra_flags);
1265 list_add_tail(&work->entry, head);
1269 * Ensure either wq_worker_sleeping() sees the above
1270 * list_add_tail() or we see zero nr_running to avoid workers lying
1271 * around lazily while there are works to be processed.
1275 if (__need_more_worker(pool))
1276 wake_up_worker(pool);
1280 * Test whether @work is being queued from another work executing on the
1283 static bool is_chained_work(struct workqueue_struct *wq)
1285 struct worker *worker;
1287 worker = current_wq_worker();
1289 * Return %true iff I'm a worker execuing a work item on @wq. If
1290 * I'm @worker, it's safe to dereference it without locking.
1292 return worker && worker->current_pwq->wq == wq;
1295 static void __queue_work(int cpu, struct workqueue_struct *wq,
1296 struct work_struct *work)
1298 struct pool_workqueue *pwq;
1299 struct worker_pool *last_pool;
1300 struct list_head *worklist;
1301 unsigned int work_flags;
1302 unsigned int req_cpu = cpu;
1305 * While a work item is PENDING && off queue, a task trying to
1306 * steal the PENDING will busy-loop waiting for it to either get
1307 * queued or lose PENDING. Grabbing PENDING and queueing should
1308 * happen with IRQ disabled.
1310 WARN_ON_ONCE(!irqs_disabled());
1312 debug_work_activate(work);
1314 /* if dying, only works from the same workqueue are allowed */
1315 if (unlikely(wq->flags & __WQ_DRAINING) &&
1316 WARN_ON_ONCE(!is_chained_work(wq)))
1319 if (req_cpu == WORK_CPU_UNBOUND)
1320 cpu = raw_smp_processor_id();
1322 /* pwq which will be used unless @work is executing elsewhere */
1323 if (!(wq->flags & WQ_UNBOUND))
1324 pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
1326 pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
1329 * If @work was previously on a different pool, it might still be
1330 * running there, in which case the work needs to be queued on that
1331 * pool to guarantee non-reentrancy.
1333 last_pool = get_work_pool(work);
1334 if (last_pool && last_pool != pwq->pool) {
1335 struct worker *worker;
1337 spin_lock(&last_pool->lock);
1339 worker = find_worker_executing_work(last_pool, work);
1341 if (worker && worker->current_pwq->wq == wq) {
1342 pwq = worker->current_pwq;
1344 /* meh... not running there, queue here */
1345 spin_unlock(&last_pool->lock);
1346 spin_lock(&pwq->pool->lock);
1349 spin_lock(&pwq->pool->lock);
1353 * pwq is determined and locked. For unbound pools, we could have
1354 * raced with pwq release and it could already be dead. If its
1355 * refcnt is zero, repeat pwq selection. Note that pwqs never die
1356 * without another pwq replacing it in the numa_pwq_tbl or while
1357 * work items are executing on it, so the retrying is guaranteed to
1358 * make forward-progress.
1360 if (unlikely(!pwq->refcnt)) {
1361 if (wq->flags & WQ_UNBOUND) {
1362 spin_unlock(&pwq->pool->lock);
1367 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1371 /* pwq determined, queue */
1372 trace_workqueue_queue_work(req_cpu, pwq, work);
1374 if (WARN_ON(!list_empty(&work->entry))) {
1375 spin_unlock(&pwq->pool->lock);
1379 pwq->nr_in_flight[pwq->work_color]++;
1380 work_flags = work_color_to_flags(pwq->work_color);
1382 if (likely(pwq->nr_active < pwq->max_active)) {
1383 trace_workqueue_activate_work(work);
1385 worklist = &pwq->pool->worklist;
1387 work_flags |= WORK_STRUCT_DELAYED;
1388 worklist = &pwq->delayed_works;
1391 insert_work(pwq, work, worklist, work_flags);
1393 spin_unlock(&pwq->pool->lock);
1397 * queue_work_on - queue work on specific cpu
1398 * @cpu: CPU number to execute work on
1399 * @wq: workqueue to use
1400 * @work: work to queue
1402 * Returns %false if @work was already on a queue, %true otherwise.
1404 * We queue the work to a specific CPU, the caller must ensure it
1407 bool queue_work_on(int cpu, struct workqueue_struct *wq,
1408 struct work_struct *work)
1411 unsigned long flags;
1413 local_irq_save(flags);
1415 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1416 __queue_work(cpu, wq, work);
1420 local_irq_restore(flags);
1423 EXPORT_SYMBOL_GPL(queue_work_on);
1425 void delayed_work_timer_fn(unsigned long __data)
1427 struct delayed_work *dwork = (struct delayed_work *)__data;
1429 /* should have been called from irqsafe timer with irq already off */
1430 __queue_work(dwork->cpu, dwork->wq, &dwork->work);
1432 EXPORT_SYMBOL(delayed_work_timer_fn);
1434 static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
1435 struct delayed_work *dwork, unsigned long delay)
1437 struct timer_list *timer = &dwork->timer;
1438 struct work_struct *work = &dwork->work;
1440 WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
1441 timer->data != (unsigned long)dwork);
1442 WARN_ON_ONCE(timer_pending(timer));
1443 WARN_ON_ONCE(!list_empty(&work->entry));
1446 * If @delay is 0, queue @dwork->work immediately. This is for
1447 * both optimization and correctness. The earliest @timer can
1448 * expire is on the closest next tick and delayed_work users depend
1449 * on that there's no such delay when @delay is 0.
1452 __queue_work(cpu, wq, &dwork->work);
1456 timer_stats_timer_set_start_info(&dwork->timer);
1460 timer->expires = jiffies + delay;
1462 if (unlikely(cpu != WORK_CPU_UNBOUND))
1463 add_timer_on(timer, cpu);
1469 * queue_delayed_work_on - queue work on specific CPU after delay
1470 * @cpu: CPU number to execute work on
1471 * @wq: workqueue to use
1472 * @dwork: work to queue
1473 * @delay: number of jiffies to wait before queueing
1475 * Returns %false if @work was already on a queue, %true otherwise. If
1476 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1479 bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1480 struct delayed_work *dwork, unsigned long delay)
1482 struct work_struct *work = &dwork->work;
1484 unsigned long flags;
1486 /* read the comment in __queue_work() */
1487 local_irq_save(flags);
1489 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1490 __queue_delayed_work(cpu, wq, dwork, delay);
1494 local_irq_restore(flags);
1497 EXPORT_SYMBOL_GPL(queue_delayed_work_on);
1500 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1501 * @cpu: CPU number to execute work on
1502 * @wq: workqueue to use
1503 * @dwork: work to queue
1504 * @delay: number of jiffies to wait before queueing
1506 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1507 * modify @dwork's timer so that it expires after @delay. If @delay is
1508 * zero, @work is guaranteed to be scheduled immediately regardless of its
1511 * Returns %false if @dwork was idle and queued, %true if @dwork was
1512 * pending and its timer was modified.
1514 * This function is safe to call from any context including IRQ handler.
1515 * See try_to_grab_pending() for details.
1517 bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
1518 struct delayed_work *dwork, unsigned long delay)
1520 unsigned long flags;
1524 ret = try_to_grab_pending(&dwork->work, true, &flags);
1525 } while (unlikely(ret == -EAGAIN));
1527 if (likely(ret >= 0)) {
1528 __queue_delayed_work(cpu, wq, dwork, delay);
1529 local_irq_restore(flags);
1532 /* -ENOENT from try_to_grab_pending() becomes %true */
1535 EXPORT_SYMBOL_GPL(mod_delayed_work_on);
1538 * worker_enter_idle - enter idle state
1539 * @worker: worker which is entering idle state
1541 * @worker is entering idle state. Update stats and idle timer if
1545 * spin_lock_irq(pool->lock).
1547 static void worker_enter_idle(struct worker *worker)
1549 struct worker_pool *pool = worker->pool;
1551 if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
1552 WARN_ON_ONCE(!list_empty(&worker->entry) &&
1553 (worker->hentry.next || worker->hentry.pprev)))
1556 /* can't use worker_set_flags(), also called from start_worker() */
1557 worker->flags |= WORKER_IDLE;
1559 worker->last_active = jiffies;
1561 /* idle_list is LIFO */
1562 list_add(&worker->entry, &pool->idle_list);
1564 if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
1565 mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
1568 * Sanity check nr_running. Because wq_unbind_fn() releases
1569 * pool->lock between setting %WORKER_UNBOUND and zapping
1570 * nr_running, the warning may trigger spuriously. Check iff
1571 * unbind is not in progress.
1573 WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
1574 pool->nr_workers == pool->nr_idle &&
1575 atomic_read(&pool->nr_running));
1579 * worker_leave_idle - leave idle state
1580 * @worker: worker which is leaving idle state
1582 * @worker is leaving idle state. Update stats.
1585 * spin_lock_irq(pool->lock).
1587 static void worker_leave_idle(struct worker *worker)
1589 struct worker_pool *pool = worker->pool;
1591 if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
1593 worker_clr_flags(worker, WORKER_IDLE);
1595 list_del_init(&worker->entry);
1599 * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it
1600 * @pool: target worker_pool
1602 * Bind %current to the cpu of @pool if it is associated and lock @pool.
1604 * Works which are scheduled while the cpu is online must at least be
1605 * scheduled to a worker which is bound to the cpu so that if they are
1606 * flushed from cpu callbacks while cpu is going down, they are
1607 * guaranteed to execute on the cpu.
1609 * This function is to be used by unbound workers and rescuers to bind
1610 * themselves to the target cpu and may race with cpu going down or
1611 * coming online. kthread_bind() can't be used because it may put the
1612 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1613 * verbatim as it's best effort and blocking and pool may be
1614 * [dis]associated in the meantime.
1616 * This function tries set_cpus_allowed() and locks pool and verifies the
1617 * binding against %POOL_DISASSOCIATED which is set during
1618 * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
1619 * enters idle state or fetches works without dropping lock, it can
1620 * guarantee the scheduling requirement described in the first paragraph.
1623 * Might sleep. Called without any lock but returns with pool->lock
1627 * %true if the associated pool is online (@worker is successfully
1628 * bound), %false if offline.
1630 static bool worker_maybe_bind_and_lock(struct worker_pool *pool)
1631 __acquires(&pool->lock)
1635 * The following call may fail, succeed or succeed
1636 * without actually migrating the task to the cpu if
1637 * it races with cpu hotunplug operation. Verify
1638 * against POOL_DISASSOCIATED.
1640 if (!(pool->flags & POOL_DISASSOCIATED))
1641 set_cpus_allowed_ptr(current, pool->attrs->cpumask);
1643 spin_lock_irq(&pool->lock);
1644 if (pool->flags & POOL_DISASSOCIATED)
1646 if (task_cpu(current) == pool->cpu &&
1647 cpumask_equal(¤t->cpus_allowed, pool->attrs->cpumask))
1649 spin_unlock_irq(&pool->lock);
1652 * We've raced with CPU hot[un]plug. Give it a breather
1653 * and retry migration. cond_resched() is required here;
1654 * otherwise, we might deadlock against cpu_stop trying to
1655 * bring down the CPU on non-preemptive kernel.
1662 static struct worker *alloc_worker(void)
1664 struct worker *worker;
1666 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
1668 INIT_LIST_HEAD(&worker->entry);
1669 INIT_LIST_HEAD(&worker->scheduled);
1670 /* on creation a worker is in !idle && prep state */
1671 worker->flags = WORKER_PREP;
1677 * create_worker - create a new workqueue worker
1678 * @pool: pool the new worker will belong to
1680 * Create a new worker which is bound to @pool. The returned worker
1681 * can be started by calling start_worker() or destroyed using
1685 * Might sleep. Does GFP_KERNEL allocations.
1688 * Pointer to the newly created worker.
1690 static struct worker *create_worker(struct worker_pool *pool)
1692 struct worker *worker = NULL;
1696 lockdep_assert_held(&pool->manager_mutex);
1699 * ID is needed to determine kthread name. Allocate ID first
1700 * without installing the pointer.
1702 idr_preload(GFP_KERNEL);
1703 spin_lock_irq(&pool->lock);
1705 id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_NOWAIT);
1707 spin_unlock_irq(&pool->lock);
1712 worker = alloc_worker();
1716 worker->pool = pool;
1720 snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
1721 pool->attrs->nice < 0 ? "H" : "");
1723 snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
1725 worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
1726 "kworker/%s", id_buf);
1727 if (IS_ERR(worker->task))
1731 * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1732 * online CPUs. It'll be re-applied when any of the CPUs come up.
1734 set_user_nice(worker->task, pool->attrs->nice);
1735 set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
1737 /* prevent userland from meddling with cpumask of workqueue workers */
1738 worker->task->flags |= PF_NO_SETAFFINITY;
1741 * The caller is responsible for ensuring %POOL_DISASSOCIATED
1742 * remains stable across this function. See the comments above the
1743 * flag definition for details.
1745 if (pool->flags & POOL_DISASSOCIATED)
1746 worker->flags |= WORKER_UNBOUND;
1748 /* successful, commit the pointer to idr */
1749 spin_lock_irq(&pool->lock);
1750 idr_replace(&pool->worker_idr, worker, worker->id);
1751 spin_unlock_irq(&pool->lock);
1757 spin_lock_irq(&pool->lock);
1758 idr_remove(&pool->worker_idr, id);
1759 spin_unlock_irq(&pool->lock);
1766 * start_worker - start a newly created worker
1767 * @worker: worker to start
1769 * Make the pool aware of @worker and start it.
1772 * spin_lock_irq(pool->lock).
1774 static void start_worker(struct worker *worker)
1776 worker->flags |= WORKER_STARTED;
1777 worker->pool->nr_workers++;
1778 worker_enter_idle(worker);
1779 wake_up_process(worker->task);
1783 * create_and_start_worker - create and start a worker for a pool
1784 * @pool: the target pool
1786 * Grab the managership of @pool and create and start a new worker for it.
1788 static int create_and_start_worker(struct worker_pool *pool)
1790 struct worker *worker;
1792 mutex_lock(&pool->manager_mutex);
1794 worker = create_worker(pool);
1796 spin_lock_irq(&pool->lock);
1797 start_worker(worker);
1798 spin_unlock_irq(&pool->lock);
1801 mutex_unlock(&pool->manager_mutex);
1803 return worker ? 0 : -ENOMEM;
1807 * destroy_worker - destroy a workqueue worker
1808 * @worker: worker to be destroyed
1810 * Destroy @worker and adjust @pool stats accordingly.
1813 * spin_lock_irq(pool->lock) which is released and regrabbed.
1815 static void destroy_worker(struct worker *worker)
1817 struct worker_pool *pool = worker->pool;
1819 lockdep_assert_held(&pool->manager_mutex);
1820 lockdep_assert_held(&pool->lock);
1822 /* sanity check frenzy */
1823 if (WARN_ON(worker->current_work) ||
1824 WARN_ON(!list_empty(&worker->scheduled)))
1827 if (worker->flags & WORKER_STARTED)
1829 if (worker->flags & WORKER_IDLE)
1832 list_del_init(&worker->entry);
1833 worker->flags |= WORKER_DIE;
1835 idr_remove(&pool->worker_idr, worker->id);
1837 spin_unlock_irq(&pool->lock);
1839 kthread_stop(worker->task);
1842 spin_lock_irq(&pool->lock);
1845 static void idle_worker_timeout(unsigned long __pool)
1847 struct worker_pool *pool = (void *)__pool;
1849 spin_lock_irq(&pool->lock);
1851 if (too_many_workers(pool)) {
1852 struct worker *worker;
1853 unsigned long expires;
1855 /* idle_list is kept in LIFO order, check the last one */
1856 worker = list_entry(pool->idle_list.prev, struct worker, entry);
1857 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1859 if (time_before(jiffies, expires))
1860 mod_timer(&pool->idle_timer, expires);
1862 /* it's been idle for too long, wake up manager */
1863 pool->flags |= POOL_MANAGE_WORKERS;
1864 wake_up_worker(pool);
1868 spin_unlock_irq(&pool->lock);
1871 static void send_mayday(struct work_struct *work)
1873 struct pool_workqueue *pwq = get_work_pwq(work);
1874 struct workqueue_struct *wq = pwq->wq;
1876 lockdep_assert_held(&wq_mayday_lock);
1881 /* mayday mayday mayday */
1882 if (list_empty(&pwq->mayday_node)) {
1883 list_add_tail(&pwq->mayday_node, &wq->maydays);
1884 wake_up_process(wq->rescuer->task);
1888 static void pool_mayday_timeout(unsigned long __pool)
1890 struct worker_pool *pool = (void *)__pool;
1891 struct work_struct *work;
1893 spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */
1894 spin_lock(&pool->lock);
1896 if (need_to_create_worker(pool)) {
1898 * We've been trying to create a new worker but
1899 * haven't been successful. We might be hitting an
1900 * allocation deadlock. Send distress signals to
1903 list_for_each_entry(work, &pool->worklist, entry)
1907 spin_unlock(&pool->lock);
1908 spin_unlock_irq(&wq_mayday_lock);
1910 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
1914 * maybe_create_worker - create a new worker if necessary
1915 * @pool: pool to create a new worker for
1917 * Create a new worker for @pool if necessary. @pool is guaranteed to
1918 * have at least one idle worker on return from this function. If
1919 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1920 * sent to all rescuers with works scheduled on @pool to resolve
1921 * possible allocation deadlock.
1923 * On return, need_to_create_worker() is guaranteed to be %false and
1924 * may_start_working() %true.
1927 * spin_lock_irq(pool->lock) which may be released and regrabbed
1928 * multiple times. Does GFP_KERNEL allocations. Called only from
1932 * %false if no action was taken and pool->lock stayed locked, %true
1935 static bool maybe_create_worker(struct worker_pool *pool)
1936 __releases(&pool->lock)
1937 __acquires(&pool->lock)
1939 if (!need_to_create_worker(pool))
1942 spin_unlock_irq(&pool->lock);
1944 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1945 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
1948 struct worker *worker;
1950 worker = create_worker(pool);
1952 del_timer_sync(&pool->mayday_timer);
1953 spin_lock_irq(&pool->lock);
1954 start_worker(worker);
1955 if (WARN_ON_ONCE(need_to_create_worker(pool)))
1960 if (!need_to_create_worker(pool))
1963 __set_current_state(TASK_INTERRUPTIBLE);
1964 schedule_timeout(CREATE_COOLDOWN);
1966 if (!need_to_create_worker(pool))
1970 del_timer_sync(&pool->mayday_timer);
1971 spin_lock_irq(&pool->lock);
1972 if (need_to_create_worker(pool))
1978 * maybe_destroy_worker - destroy workers which have been idle for a while
1979 * @pool: pool to destroy workers for
1981 * Destroy @pool workers which have been idle for longer than
1982 * IDLE_WORKER_TIMEOUT.
1985 * spin_lock_irq(pool->lock) which may be released and regrabbed
1986 * multiple times. Called only from manager.
1989 * %false if no action was taken and pool->lock stayed locked, %true
1992 static bool maybe_destroy_workers(struct worker_pool *pool)
1996 while (too_many_workers(pool)) {
1997 struct worker *worker;
1998 unsigned long expires;
2000 worker = list_entry(pool->idle_list.prev, struct worker, entry);
2001 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
2003 if (time_before(jiffies, expires)) {
2004 mod_timer(&pool->idle_timer, expires);
2008 destroy_worker(worker);
2016 * manage_workers - manage worker pool
2019 * Assume the manager role and manage the worker pool @worker belongs
2020 * to. At any given time, there can be only zero or one manager per
2021 * pool. The exclusion is handled automatically by this function.
2023 * The caller can safely start processing works on false return. On
2024 * true return, it's guaranteed that need_to_create_worker() is false
2025 * and may_start_working() is true.
2028 * spin_lock_irq(pool->lock) which may be released and regrabbed
2029 * multiple times. Does GFP_KERNEL allocations.
2032 * spin_lock_irq(pool->lock) which may be released and regrabbed
2033 * multiple times. Does GFP_KERNEL allocations.
2035 static bool manage_workers(struct worker *worker)
2037 struct worker_pool *pool = worker->pool;
2041 * Managership is governed by two mutexes - manager_arb and
2042 * manager_mutex. manager_arb handles arbitration of manager role.
2043 * Anyone who successfully grabs manager_arb wins the arbitration
2044 * and becomes the manager. mutex_trylock() on pool->manager_arb
2045 * failure while holding pool->lock reliably indicates that someone
2046 * else is managing the pool and the worker which failed trylock
2047 * can proceed to executing work items. This means that anyone
2048 * grabbing manager_arb is responsible for actually performing
2049 * manager duties. If manager_arb is grabbed and released without
2050 * actual management, the pool may stall indefinitely.
2052 * manager_mutex is used for exclusion of actual management
2053 * operations. The holder of manager_mutex can be sure that none
2054 * of management operations, including creation and destruction of
2055 * workers, won't take place until the mutex is released. Because
2056 * manager_mutex doesn't interfere with manager role arbitration,
2057 * it is guaranteed that the pool's management, while may be
2058 * delayed, won't be disturbed by someone else grabbing
2061 if (!mutex_trylock(&pool->manager_arb))
2065 * With manager arbitration won, manager_mutex would be free in
2066 * most cases. trylock first without dropping @pool->lock.
2068 if (unlikely(!mutex_trylock(&pool->manager_mutex))) {
2069 spin_unlock_irq(&pool->lock);
2070 mutex_lock(&pool->manager_mutex);
2074 pool->flags &= ~POOL_MANAGE_WORKERS;
2077 * Destroy and then create so that may_start_working() is true
2080 ret |= maybe_destroy_workers(pool);
2081 ret |= maybe_create_worker(pool);
2083 mutex_unlock(&pool->manager_mutex);
2084 mutex_unlock(&pool->manager_arb);
2089 * process_one_work - process single work
2091 * @work: work to process
2093 * Process @work. This function contains all the logics necessary to
2094 * process a single work including synchronization against and
2095 * interaction with other workers on the same cpu, queueing and
2096 * flushing. As long as context requirement is met, any worker can
2097 * call this function to process a work.
2100 * spin_lock_irq(pool->lock) which is released and regrabbed.
2102 static void process_one_work(struct worker *worker, struct work_struct *work)
2103 __releases(&pool->lock)
2104 __acquires(&pool->lock)
2106 struct pool_workqueue *pwq = get_work_pwq(work);
2107 struct worker_pool *pool = worker->pool;
2108 bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
2110 struct worker *collision;
2111 #ifdef CONFIG_LOCKDEP
2113 * It is permissible to free the struct work_struct from
2114 * inside the function that is called from it, this we need to
2115 * take into account for lockdep too. To avoid bogus "held
2116 * lock freed" warnings as well as problems when looking into
2117 * work->lockdep_map, make a copy and use that here.
2119 struct lockdep_map lockdep_map;
2121 lockdep_copy_map(&lockdep_map, &work->lockdep_map);
2124 * Ensure we're on the correct CPU. DISASSOCIATED test is
2125 * necessary to avoid spurious warnings from rescuers servicing the
2126 * unbound or a disassociated pool.
2128 WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) &&
2129 !(pool->flags & POOL_DISASSOCIATED) &&
2130 raw_smp_processor_id() != pool->cpu);
2133 * A single work shouldn't be executed concurrently by
2134 * multiple workers on a single cpu. Check whether anyone is
2135 * already processing the work. If so, defer the work to the
2136 * currently executing one.
2138 collision = find_worker_executing_work(pool, work);
2139 if (unlikely(collision)) {
2140 move_linked_works(work, &collision->scheduled, NULL);
2144 /* claim and dequeue */
2145 debug_work_deactivate(work);
2146 hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
2147 worker->current_work = work;
2148 worker->current_func = work->func;
2149 worker->current_pwq = pwq;
2150 work_color = get_work_color(work);
2152 list_del_init(&work->entry);
2155 * CPU intensive works don't participate in concurrency
2156 * management. They're the scheduler's responsibility.
2158 if (unlikely(cpu_intensive))
2159 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
2162 * Unbound pool isn't concurrency managed and work items should be
2163 * executed ASAP. Wake up another worker if necessary.
2165 if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
2166 wake_up_worker(pool);
2169 * Record the last pool and clear PENDING which should be the last
2170 * update to @work. Also, do this inside @pool->lock so that
2171 * PENDING and queued state changes happen together while IRQ is
2174 set_work_pool_and_clear_pending(work, pool->id);
2176 spin_unlock_irq(&pool->lock);
2178 lock_map_acquire_read(&pwq->wq->lockdep_map);
2179 lock_map_acquire(&lockdep_map);
2180 trace_workqueue_execute_start(work);
2181 worker->current_func(work);
2183 * While we must be careful to not use "work" after this, the trace
2184 * point will only record its address.
2186 trace_workqueue_execute_end(work);
2187 lock_map_release(&lockdep_map);
2188 lock_map_release(&pwq->wq->lockdep_map);
2190 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
2191 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2192 " last function: %pf\n",
2193 current->comm, preempt_count(), task_pid_nr(current),
2194 worker->current_func);
2195 debug_show_held_locks(current);
2199 spin_lock_irq(&pool->lock);
2201 /* clear cpu intensive status */
2202 if (unlikely(cpu_intensive))
2203 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
2205 /* we're done with it, release */
2206 hash_del(&worker->hentry);
2207 worker->current_work = NULL;
2208 worker->current_func = NULL;
2209 worker->current_pwq = NULL;
2210 worker->desc_valid = false;
2211 pwq_dec_nr_in_flight(pwq, work_color);
2215 * process_scheduled_works - process scheduled works
2218 * Process all scheduled works. Please note that the scheduled list
2219 * may change while processing a work, so this function repeatedly
2220 * fetches a work from the top and executes it.
2223 * spin_lock_irq(pool->lock) which may be released and regrabbed
2226 static void process_scheduled_works(struct worker *worker)
2228 while (!list_empty(&worker->scheduled)) {
2229 struct work_struct *work = list_first_entry(&worker->scheduled,
2230 struct work_struct, entry);
2231 process_one_work(worker, work);
2236 * worker_thread - the worker thread function
2239 * The worker thread function. All workers belong to a worker_pool -
2240 * either a per-cpu one or dynamic unbound one. These workers process all
2241 * work items regardless of their specific target workqueue. The only
2242 * exception is work items which belong to workqueues with a rescuer which
2243 * will be explained in rescuer_thread().
2245 static int worker_thread(void *__worker)
2247 struct worker *worker = __worker;
2248 struct worker_pool *pool = worker->pool;
2250 /* tell the scheduler that this is a workqueue worker */
2251 worker->task->flags |= PF_WQ_WORKER;
2253 spin_lock_irq(&pool->lock);
2255 /* am I supposed to die? */
2256 if (unlikely(worker->flags & WORKER_DIE)) {
2257 spin_unlock_irq(&pool->lock);
2258 WARN_ON_ONCE(!list_empty(&worker->entry));
2259 worker->task->flags &= ~PF_WQ_WORKER;
2263 worker_leave_idle(worker);
2265 /* no more worker necessary? */
2266 if (!need_more_worker(pool))
2269 /* do we need to manage? */
2270 if (unlikely(!may_start_working(pool)) && manage_workers(worker))
2274 * ->scheduled list can only be filled while a worker is
2275 * preparing to process a work or actually processing it.
2276 * Make sure nobody diddled with it while I was sleeping.
2278 WARN_ON_ONCE(!list_empty(&worker->scheduled));
2281 * Finish PREP stage. We're guaranteed to have at least one idle
2282 * worker or that someone else has already assumed the manager
2283 * role. This is where @worker starts participating in concurrency
2284 * management if applicable and concurrency management is restored
2285 * after being rebound. See rebind_workers() for details.
2287 worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND);
2290 struct work_struct *work =
2291 list_first_entry(&pool->worklist,
2292 struct work_struct, entry);
2294 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
2295 /* optimization path, not strictly necessary */
2296 process_one_work(worker, work);
2297 if (unlikely(!list_empty(&worker->scheduled)))
2298 process_scheduled_works(worker);
2300 move_linked_works(work, &worker->scheduled, NULL);
2301 process_scheduled_works(worker);
2303 } while (keep_working(pool));
2305 worker_set_flags(worker, WORKER_PREP, false);
2307 if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker))
2311 * pool->lock is held and there's no work to process and no need to
2312 * manage, sleep. Workers are woken up only while holding
2313 * pool->lock or from local cpu, so setting the current state
2314 * before releasing pool->lock is enough to prevent losing any
2317 worker_enter_idle(worker);
2318 __set_current_state(TASK_INTERRUPTIBLE);
2319 spin_unlock_irq(&pool->lock);
2325 * rescuer_thread - the rescuer thread function
2328 * Workqueue rescuer thread function. There's one rescuer for each
2329 * workqueue which has WQ_MEM_RECLAIM set.
2331 * Regular work processing on a pool may block trying to create a new
2332 * worker which uses GFP_KERNEL allocation which has slight chance of
2333 * developing into deadlock if some works currently on the same queue
2334 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2335 * the problem rescuer solves.
2337 * When such condition is possible, the pool summons rescuers of all
2338 * workqueues which have works queued on the pool and let them process
2339 * those works so that forward progress can be guaranteed.
2341 * This should happen rarely.
2343 static int rescuer_thread(void *__rescuer)
2345 struct worker *rescuer = __rescuer;
2346 struct workqueue_struct *wq = rescuer->rescue_wq;
2347 struct list_head *scheduled = &rescuer->scheduled;
2349 set_user_nice(current, RESCUER_NICE_LEVEL);
2352 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2353 * doesn't participate in concurrency management.
2355 rescuer->task->flags |= PF_WQ_WORKER;
2357 set_current_state(TASK_INTERRUPTIBLE);
2359 if (kthread_should_stop()) {
2360 __set_current_state(TASK_RUNNING);
2361 rescuer->task->flags &= ~PF_WQ_WORKER;
2365 /* see whether any pwq is asking for help */
2366 spin_lock_irq(&wq_mayday_lock);
2368 while (!list_empty(&wq->maydays)) {
2369 struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
2370 struct pool_workqueue, mayday_node);
2371 struct worker_pool *pool = pwq->pool;
2372 struct work_struct *work, *n;
2374 __set_current_state(TASK_RUNNING);
2375 list_del_init(&pwq->mayday_node);
2377 spin_unlock_irq(&wq_mayday_lock);
2379 /* migrate to the target cpu if possible */
2380 worker_maybe_bind_and_lock(pool);
2381 rescuer->pool = pool;
2384 * Slurp in all works issued via this workqueue and
2387 WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
2388 list_for_each_entry_safe(work, n, &pool->worklist, entry)
2389 if (get_work_pwq(work) == pwq)
2390 move_linked_works(work, scheduled, &n);
2392 process_scheduled_works(rescuer);
2395 * Leave this pool. If keep_working() is %true, notify a
2396 * regular worker; otherwise, we end up with 0 concurrency
2397 * and stalling the execution.
2399 if (keep_working(pool))
2400 wake_up_worker(pool);
2402 rescuer->pool = NULL;
2403 spin_unlock(&pool->lock);
2404 spin_lock(&wq_mayday_lock);
2407 spin_unlock_irq(&wq_mayday_lock);
2409 /* rescuers should never participate in concurrency management */
2410 WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
2416 struct work_struct work;
2417 struct completion done;
2420 static void wq_barrier_func(struct work_struct *work)
2422 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
2423 complete(&barr->done);
2427 * insert_wq_barrier - insert a barrier work
2428 * @pwq: pwq to insert barrier into
2429 * @barr: wq_barrier to insert
2430 * @target: target work to attach @barr to
2431 * @worker: worker currently executing @target, NULL if @target is not executing
2433 * @barr is linked to @target such that @barr is completed only after
2434 * @target finishes execution. Please note that the ordering
2435 * guarantee is observed only with respect to @target and on the local
2438 * Currently, a queued barrier can't be canceled. This is because
2439 * try_to_grab_pending() can't determine whether the work to be
2440 * grabbed is at the head of the queue and thus can't clear LINKED
2441 * flag of the previous work while there must be a valid next work
2442 * after a work with LINKED flag set.
2444 * Note that when @worker is non-NULL, @target may be modified
2445 * underneath us, so we can't reliably determine pwq from @target.
2448 * spin_lock_irq(pool->lock).
2450 static void insert_wq_barrier(struct pool_workqueue *pwq,
2451 struct wq_barrier *barr,
2452 struct work_struct *target, struct worker *worker)
2454 struct list_head *head;
2455 unsigned int linked = 0;
2458 * debugobject calls are safe here even with pool->lock locked
2459 * as we know for sure that this will not trigger any of the
2460 * checks and call back into the fixup functions where we
2463 INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
2464 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
2465 init_completion(&barr->done);
2468 * If @target is currently being executed, schedule the
2469 * barrier to the worker; otherwise, put it after @target.
2472 head = worker->scheduled.next;
2474 unsigned long *bits = work_data_bits(target);
2476 head = target->entry.next;
2477 /* there can already be other linked works, inherit and set */
2478 linked = *bits & WORK_STRUCT_LINKED;
2479 __set_bit(WORK_STRUCT_LINKED_BIT, bits);
2482 debug_work_activate(&barr->work);
2483 insert_work(pwq, &barr->work, head,
2484 work_color_to_flags(WORK_NO_COLOR) | linked);
2488 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2489 * @wq: workqueue being flushed
2490 * @flush_color: new flush color, < 0 for no-op
2491 * @work_color: new work color, < 0 for no-op
2493 * Prepare pwqs for workqueue flushing.
2495 * If @flush_color is non-negative, flush_color on all pwqs should be
2496 * -1. If no pwq has in-flight commands at the specified color, all
2497 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2498 * has in flight commands, its pwq->flush_color is set to
2499 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2500 * wakeup logic is armed and %true is returned.
2502 * The caller should have initialized @wq->first_flusher prior to
2503 * calling this function with non-negative @flush_color. If
2504 * @flush_color is negative, no flush color update is done and %false
2507 * If @work_color is non-negative, all pwqs should have the same
2508 * work_color which is previous to @work_color and all will be
2509 * advanced to @work_color.
2512 * mutex_lock(wq->mutex).
2515 * %true if @flush_color >= 0 and there's something to flush. %false
2518 static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
2519 int flush_color, int work_color)
2522 struct pool_workqueue *pwq;
2524 if (flush_color >= 0) {
2525 WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
2526 atomic_set(&wq->nr_pwqs_to_flush, 1);
2529 for_each_pwq(pwq, wq) {
2530 struct worker_pool *pool = pwq->pool;
2532 spin_lock_irq(&pool->lock);
2534 if (flush_color >= 0) {
2535 WARN_ON_ONCE(pwq->flush_color != -1);
2537 if (pwq->nr_in_flight[flush_color]) {
2538 pwq->flush_color = flush_color;
2539 atomic_inc(&wq->nr_pwqs_to_flush);
2544 if (work_color >= 0) {
2545 WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
2546 pwq->work_color = work_color;
2549 spin_unlock_irq(&pool->lock);
2552 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
2553 complete(&wq->first_flusher->done);
2559 * flush_workqueue - ensure that any scheduled work has run to completion.
2560 * @wq: workqueue to flush
2562 * This function sleeps until all work items which were queued on entry
2563 * have finished execution, but it is not livelocked by new incoming ones.
2565 void flush_workqueue(struct workqueue_struct *wq)
2567 struct wq_flusher this_flusher = {
2568 .list = LIST_HEAD_INIT(this_flusher.list),
2570 .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
2574 lock_map_acquire(&wq->lockdep_map);
2575 lock_map_release(&wq->lockdep_map);
2577 mutex_lock(&wq->mutex);
2580 * Start-to-wait phase
2582 next_color = work_next_color(wq->work_color);
2584 if (next_color != wq->flush_color) {
2586 * Color space is not full. The current work_color
2587 * becomes our flush_color and work_color is advanced
2590 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
2591 this_flusher.flush_color = wq->work_color;
2592 wq->work_color = next_color;
2594 if (!wq->first_flusher) {
2595 /* no flush in progress, become the first flusher */
2596 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
2598 wq->first_flusher = &this_flusher;
2600 if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
2602 /* nothing to flush, done */
2603 wq->flush_color = next_color;
2604 wq->first_flusher = NULL;
2609 WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
2610 list_add_tail(&this_flusher.list, &wq->flusher_queue);
2611 flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
2615 * Oops, color space is full, wait on overflow queue.
2616 * The next flush completion will assign us
2617 * flush_color and transfer to flusher_queue.
2619 list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2622 mutex_unlock(&wq->mutex);
2624 wait_for_completion(&this_flusher.done);
2627 * Wake-up-and-cascade phase
2629 * First flushers are responsible for cascading flushes and
2630 * handling overflow. Non-first flushers can simply return.
2632 if (wq->first_flusher != &this_flusher)
2635 mutex_lock(&wq->mutex);
2637 /* we might have raced, check again with mutex held */
2638 if (wq->first_flusher != &this_flusher)
2641 wq->first_flusher = NULL;
2643 WARN_ON_ONCE(!list_empty(&this_flusher.list));
2644 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
2647 struct wq_flusher *next, *tmp;
2649 /* complete all the flushers sharing the current flush color */
2650 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2651 if (next->flush_color != wq->flush_color)
2653 list_del_init(&next->list);
2654 complete(&next->done);
2657 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
2658 wq->flush_color != work_next_color(wq->work_color));
2660 /* this flush_color is finished, advance by one */
2661 wq->flush_color = work_next_color(wq->flush_color);
2663 /* one color has been freed, handle overflow queue */
2664 if (!list_empty(&wq->flusher_overflow)) {
2666 * Assign the same color to all overflowed
2667 * flushers, advance work_color and append to
2668 * flusher_queue. This is the start-to-wait
2669 * phase for these overflowed flushers.
2671 list_for_each_entry(tmp, &wq->flusher_overflow, list)
2672 tmp->flush_color = wq->work_color;
2674 wq->work_color = work_next_color(wq->work_color);
2676 list_splice_tail_init(&wq->flusher_overflow,
2677 &wq->flusher_queue);
2678 flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
2681 if (list_empty(&wq->flusher_queue)) {
2682 WARN_ON_ONCE(wq->flush_color != wq->work_color);
2687 * Need to flush more colors. Make the next flusher
2688 * the new first flusher and arm pwqs.
2690 WARN_ON_ONCE(wq->flush_color == wq->work_color);
2691 WARN_ON_ONCE(wq->flush_color != next->flush_color);
2693 list_del_init(&next->list);
2694 wq->first_flusher = next;
2696 if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
2700 * Meh... this color is already done, clear first
2701 * flusher and repeat cascading.
2703 wq->first_flusher = NULL;
2707 mutex_unlock(&wq->mutex);
2709 EXPORT_SYMBOL_GPL(flush_workqueue);
2712 * drain_workqueue - drain a workqueue
2713 * @wq: workqueue to drain
2715 * Wait until the workqueue becomes empty. While draining is in progress,
2716 * only chain queueing is allowed. IOW, only currently pending or running
2717 * work items on @wq can queue further work items on it. @wq is flushed
2718 * repeatedly until it becomes empty. The number of flushing is detemined
2719 * by the depth of chaining and should be relatively short. Whine if it
2722 void drain_workqueue(struct workqueue_struct *wq)
2724 unsigned int flush_cnt = 0;
2725 struct pool_workqueue *pwq;
2728 * __queue_work() needs to test whether there are drainers, is much
2729 * hotter than drain_workqueue() and already looks at @wq->flags.
2730 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
2732 mutex_lock(&wq->mutex);
2733 if (!wq->nr_drainers++)
2734 wq->flags |= __WQ_DRAINING;
2735 mutex_unlock(&wq->mutex);
2737 flush_workqueue(wq);
2739 mutex_lock(&wq->mutex);
2741 for_each_pwq(pwq, wq) {
2744 spin_lock_irq(&pwq->pool->lock);
2745 drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
2746 spin_unlock_irq(&pwq->pool->lock);
2751 if (++flush_cnt == 10 ||
2752 (flush_cnt % 100 == 0 && flush_cnt <= 1000))
2753 pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
2754 wq->name, flush_cnt);
2756 mutex_unlock(&wq->mutex);
2760 if (!--wq->nr_drainers)
2761 wq->flags &= ~__WQ_DRAINING;
2762 mutex_unlock(&wq->mutex);
2764 EXPORT_SYMBOL_GPL(drain_workqueue);
2766 static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
2768 struct worker *worker = NULL;
2769 struct worker_pool *pool;
2770 struct pool_workqueue *pwq;
2774 local_irq_disable();
2775 pool = get_work_pool(work);
2781 spin_lock(&pool->lock);
2782 /* see the comment in try_to_grab_pending() with the same code */
2783 pwq = get_work_pwq(work);
2785 if (unlikely(pwq->pool != pool))
2788 worker = find_worker_executing_work(pool, work);
2791 pwq = worker->current_pwq;
2794 insert_wq_barrier(pwq, barr, work, worker);
2795 spin_unlock_irq(&pool->lock);
2798 * If @max_active is 1 or rescuer is in use, flushing another work
2799 * item on the same workqueue may lead to deadlock. Make sure the
2800 * flusher is not running on the same workqueue by verifying write
2803 if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)
2804 lock_map_acquire(&pwq->wq->lockdep_map);
2806 lock_map_acquire_read(&pwq->wq->lockdep_map);
2807 lock_map_release(&pwq->wq->lockdep_map);
2811 spin_unlock_irq(&pool->lock);
2816 * flush_work - wait for a work to finish executing the last queueing instance
2817 * @work: the work to flush
2819 * Wait until @work has finished execution. @work is guaranteed to be idle
2820 * on return if it hasn't been requeued since flush started.
2823 * %true if flush_work() waited for the work to finish execution,
2824 * %false if it was already idle.
2826 bool flush_work(struct work_struct *work)
2828 struct wq_barrier barr;
2830 lock_map_acquire(&work->lockdep_map);
2831 lock_map_release(&work->lockdep_map);
2833 if (start_flush_work(work, &barr)) {
2834 wait_for_completion(&barr.done);
2835 destroy_work_on_stack(&barr.work);
2841 EXPORT_SYMBOL_GPL(flush_work);
2843 static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
2845 unsigned long flags;
2849 ret = try_to_grab_pending(work, is_dwork, &flags);
2851 * If someone else is canceling, wait for the same event it
2852 * would be waiting for before retrying.
2854 if (unlikely(ret == -ENOENT))
2856 } while (unlikely(ret < 0));
2858 /* tell other tasks trying to grab @work to back off */
2859 mark_work_canceling(work);
2860 local_irq_restore(flags);
2863 clear_work_data(work);
2868 * cancel_work_sync - cancel a work and wait for it to finish
2869 * @work: the work to cancel
2871 * Cancel @work and wait for its execution to finish. This function
2872 * can be used even if the work re-queues itself or migrates to
2873 * another workqueue. On return from this function, @work is
2874 * guaranteed to be not pending or executing on any CPU.
2876 * cancel_work_sync(&delayed_work->work) must not be used for
2877 * delayed_work's. Use cancel_delayed_work_sync() instead.
2879 * The caller must ensure that the workqueue on which @work was last
2880 * queued can't be destroyed before this function returns.
2883 * %true if @work was pending, %false otherwise.
2885 bool cancel_work_sync(struct work_struct *work)
2887 return __cancel_work_timer(work, false);
2889 EXPORT_SYMBOL_GPL(cancel_work_sync);
2892 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2893 * @dwork: the delayed work to flush
2895 * Delayed timer is cancelled and the pending work is queued for
2896 * immediate execution. Like flush_work(), this function only
2897 * considers the last queueing instance of @dwork.
2900 * %true if flush_work() waited for the work to finish execution,
2901 * %false if it was already idle.
2903 bool flush_delayed_work(struct delayed_work *dwork)
2905 local_irq_disable();
2906 if (del_timer_sync(&dwork->timer))
2907 __queue_work(dwork->cpu, dwork->wq, &dwork->work);
2909 return flush_work(&dwork->work);
2911 EXPORT_SYMBOL(flush_delayed_work);
2914 * cancel_delayed_work - cancel a delayed work
2915 * @dwork: delayed_work to cancel
2917 * Kill off a pending delayed_work. Returns %true if @dwork was pending
2918 * and canceled; %false if wasn't pending. Note that the work callback
2919 * function may still be running on return, unless it returns %true and the
2920 * work doesn't re-arm itself. Explicitly flush or use
2921 * cancel_delayed_work_sync() to wait on it.
2923 * This function is safe to call from any context including IRQ handler.
2925 bool cancel_delayed_work(struct delayed_work *dwork)
2927 unsigned long flags;
2931 ret = try_to_grab_pending(&dwork->work, true, &flags);
2932 } while (unlikely(ret == -EAGAIN));
2934 if (unlikely(ret < 0))
2937 set_work_pool_and_clear_pending(&dwork->work,
2938 get_work_pool_id(&dwork->work));
2939 local_irq_restore(flags);
2942 EXPORT_SYMBOL(cancel_delayed_work);
2945 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2946 * @dwork: the delayed work cancel
2948 * This is cancel_work_sync() for delayed works.
2951 * %true if @dwork was pending, %false otherwise.
2953 bool cancel_delayed_work_sync(struct delayed_work *dwork)
2955 return __cancel_work_timer(&dwork->work, true);
2957 EXPORT_SYMBOL(cancel_delayed_work_sync);
2960 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2961 * @func: the function to call
2963 * schedule_on_each_cpu() executes @func on each online CPU using the
2964 * system workqueue and blocks until all CPUs have completed.
2965 * schedule_on_each_cpu() is very slow.
2968 * 0 on success, -errno on failure.
2970 int schedule_on_each_cpu(work_func_t func)
2973 struct work_struct __percpu *works;
2975 works = alloc_percpu(struct work_struct);
2981 for_each_online_cpu(cpu) {
2982 struct work_struct *work = per_cpu_ptr(works, cpu);
2984 INIT_WORK(work, func);
2985 schedule_work_on(cpu, work);
2988 for_each_online_cpu(cpu)
2989 flush_work(per_cpu_ptr(works, cpu));
2997 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2999 * Forces execution of the kernel-global workqueue and blocks until its
3002 * Think twice before calling this function! It's very easy to get into
3003 * trouble if you don't take great care. Either of the following situations
3004 * will lead to deadlock:
3006 * One of the work items currently on the workqueue needs to acquire
3007 * a lock held by your code or its caller.
3009 * Your code is running in the context of a work routine.
3011 * They will be detected by lockdep when they occur, but the first might not
3012 * occur very often. It depends on what work items are on the workqueue and
3013 * what locks they need, which you have no control over.
3015 * In most situations flushing the entire workqueue is overkill; you merely
3016 * need to know that a particular work item isn't queued and isn't running.
3017 * In such cases you should use cancel_delayed_work_sync() or
3018 * cancel_work_sync() instead.
3020 void flush_scheduled_work(void)
3022 flush_workqueue(system_wq);
3024 EXPORT_SYMBOL(flush_scheduled_work);
3027 * execute_in_process_context - reliably execute the routine with user context
3028 * @fn: the function to execute
3029 * @ew: guaranteed storage for the execute work structure (must
3030 * be available when the work executes)
3032 * Executes the function immediately if process context is available,
3033 * otherwise schedules the function for delayed execution.
3035 * Returns: 0 - function was executed
3036 * 1 - function was scheduled for execution
3038 int execute_in_process_context(work_func_t fn, struct execute_work *ew)
3040 if (!in_interrupt()) {
3045 INIT_WORK(&ew->work, fn);
3046 schedule_work(&ew->work);
3050 EXPORT_SYMBOL_GPL(execute_in_process_context);
3054 * Workqueues with WQ_SYSFS flag set is visible to userland via
3055 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
3056 * following attributes.
3058 * per_cpu RO bool : whether the workqueue is per-cpu or unbound
3059 * max_active RW int : maximum number of in-flight work items
3061 * Unbound workqueues have the following extra attributes.
3063 * id RO int : the associated pool ID
3064 * nice RW int : nice value of the workers
3065 * cpumask RW mask : bitmask of allowed CPUs for the workers
3068 struct workqueue_struct *wq;
3072 static struct workqueue_struct *dev_to_wq(struct device *dev)
3074 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
3079 static ssize_t wq_per_cpu_show(struct device *dev,
3080 struct device_attribute *attr, char *buf)
3082 struct workqueue_struct *wq = dev_to_wq(dev);
3084 return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
3087 static ssize_t wq_max_active_show(struct device *dev,
3088 struct device_attribute *attr, char *buf)
3090 struct workqueue_struct *wq = dev_to_wq(dev);
3092 return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
3095 static ssize_t wq_max_active_store(struct device *dev,
3096 struct device_attribute *attr,
3097 const char *buf, size_t count)
3099 struct workqueue_struct *wq = dev_to_wq(dev);
3102 if (sscanf(buf, "%d", &val) != 1 || val <= 0)
3105 workqueue_set_max_active(wq, val);
3109 static struct device_attribute wq_sysfs_attrs[] = {
3110 __ATTR(per_cpu, 0444, wq_per_cpu_show, NULL),
3111 __ATTR(max_active, 0644, wq_max_active_show, wq_max_active_store),
3115 static ssize_t wq_pool_ids_show(struct device *dev,
3116 struct device_attribute *attr, char *buf)
3118 struct workqueue_struct *wq = dev_to_wq(dev);
3119 const char *delim = "";
3120 int node, written = 0;
3122 rcu_read_lock_sched();
3123 for_each_node(node) {
3124 written += scnprintf(buf + written, PAGE_SIZE - written,
3125 "%s%d:%d", delim, node,
3126 unbound_pwq_by_node(wq, node)->pool->id);
3129 written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
3130 rcu_read_unlock_sched();
3135 static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr,
3138 struct workqueue_struct *wq = dev_to_wq(dev);
3141 mutex_lock(&wq->mutex);
3142 written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
3143 mutex_unlock(&wq->mutex);
3148 /* prepare workqueue_attrs for sysfs store operations */
3149 static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq)
3151 struct workqueue_attrs *attrs;
3153 attrs = alloc_workqueue_attrs(GFP_KERNEL);
3157 mutex_lock(&wq->mutex);
3158 copy_workqueue_attrs(attrs, wq->unbound_attrs);
3159 mutex_unlock(&wq->mutex);
3163 static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr,
3164 const char *buf, size_t count)
3166 struct workqueue_struct *wq = dev_to_wq(dev);
3167 struct workqueue_attrs *attrs;
3170 attrs = wq_sysfs_prep_attrs(wq);
3174 if (sscanf(buf, "%d", &attrs->nice) == 1 &&
3175 attrs->nice >= -20 && attrs->nice <= 19)
3176 ret = apply_workqueue_attrs(wq, attrs);
3180 free_workqueue_attrs(attrs);
3181 return ret ?: count;
3184 static ssize_t wq_cpumask_show(struct device *dev,
3185 struct device_attribute *attr, char *buf)
3187 struct workqueue_struct *wq = dev_to_wq(dev);
3190 mutex_lock(&wq->mutex);
3191 written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask);
3192 mutex_unlock(&wq->mutex);
3194 written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
3198 static ssize_t wq_cpumask_store(struct device *dev,
3199 struct device_attribute *attr,
3200 const char *buf, size_t count)
3202 struct workqueue_struct *wq = dev_to_wq(dev);
3203 struct workqueue_attrs *attrs;
3206 attrs = wq_sysfs_prep_attrs(wq);
3210 ret = cpumask_parse(buf, attrs->cpumask);
3212 ret = apply_workqueue_attrs(wq, attrs);
3214 free_workqueue_attrs(attrs);
3215 return ret ?: count;
3218 static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr,
3221 struct workqueue_struct *wq = dev_to_wq(dev);
3224 mutex_lock(&wq->mutex);
3225 written = scnprintf(buf, PAGE_SIZE, "%d\n",
3226 !wq->unbound_attrs->no_numa);
3227 mutex_unlock(&wq->mutex);
3232 static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr,
3233 const char *buf, size_t count)
3235 struct workqueue_struct *wq = dev_to_wq(dev);
3236 struct workqueue_attrs *attrs;
3239 attrs = wq_sysfs_prep_attrs(wq);
3244 if (sscanf(buf, "%d", &v) == 1) {
3245 attrs->no_numa = !v;
3246 ret = apply_workqueue_attrs(wq, attrs);
3249 free_workqueue_attrs(attrs);
3250 return ret ?: count;
3253 static struct device_attribute wq_sysfs_unbound_attrs[] = {
3254 __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL),
3255 __ATTR(nice, 0644, wq_nice_show, wq_nice_store),
3256 __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
3257 __ATTR(numa, 0644, wq_numa_show, wq_numa_store),
3261 static struct bus_type wq_subsys = {
3262 .name = "workqueue",
3263 .dev_attrs = wq_sysfs_attrs,
3266 static int __init wq_sysfs_init(void)
3268 return subsys_virtual_register(&wq_subsys, NULL);
3270 core_initcall(wq_sysfs_init);
3272 static void wq_device_release(struct device *dev)
3274 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
3280 * workqueue_sysfs_register - make a workqueue visible in sysfs
3281 * @wq: the workqueue to register
3283 * Expose @wq in sysfs under /sys/bus/workqueue/devices.
3284 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
3285 * which is the preferred method.
3287 * Workqueue user should use this function directly iff it wants to apply
3288 * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
3289 * apply_workqueue_attrs() may race against userland updating the
3292 * Returns 0 on success, -errno on failure.
3294 int workqueue_sysfs_register(struct workqueue_struct *wq)
3296 struct wq_device *wq_dev;
3300 * Adjusting max_active or creating new pwqs by applyting
3301 * attributes breaks ordering guarantee. Disallow exposing ordered
3304 if (WARN_ON(wq->flags & __WQ_ORDERED))
3307 wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
3312 wq_dev->dev.bus = &wq_subsys;
3313 wq_dev->dev.init_name = wq->name;
3314 wq_dev->dev.release = wq_device_release;
3317 * unbound_attrs are created separately. Suppress uevent until
3318 * everything is ready.
3320 dev_set_uevent_suppress(&wq_dev->dev, true);
3322 ret = device_register(&wq_dev->dev);
3329 if (wq->flags & WQ_UNBOUND) {
3330 struct device_attribute *attr;
3332 for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
3333 ret = device_create_file(&wq_dev->dev, attr);
3335 device_unregister(&wq_dev->dev);
3342 kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
3347 * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
3348 * @wq: the workqueue to unregister
3350 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
3352 static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
3354 struct wq_device *wq_dev = wq->wq_dev;
3360 device_unregister(&wq_dev->dev);
3362 #else /* CONFIG_SYSFS */
3363 static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
3364 #endif /* CONFIG_SYSFS */
3367 * free_workqueue_attrs - free a workqueue_attrs
3368 * @attrs: workqueue_attrs to free
3370 * Undo alloc_workqueue_attrs().
3372 void free_workqueue_attrs(struct workqueue_attrs *attrs)
3375 free_cpumask_var(attrs->cpumask);
3381 * alloc_workqueue_attrs - allocate a workqueue_attrs
3382 * @gfp_mask: allocation mask to use
3384 * Allocate a new workqueue_attrs, initialize with default settings and
3385 * return it. Returns NULL on failure.
3387 struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask)
3389 struct workqueue_attrs *attrs;
3391 attrs = kzalloc(sizeof(*attrs), gfp_mask);
3394 if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask))
3397 cpumask_copy(attrs->cpumask, cpu_possible_mask);
3400 free_workqueue_attrs(attrs);
3404 static void copy_workqueue_attrs(struct workqueue_attrs *to,
3405 const struct workqueue_attrs *from)
3407 to->nice = from->nice;
3408 cpumask_copy(to->cpumask, from->cpumask);
3411 /* hash value of the content of @attr */
3412 static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
3416 hash = jhash_1word(attrs->nice, hash);
3417 hash = jhash(cpumask_bits(attrs->cpumask),
3418 BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
3422 /* content equality test */
3423 static bool wqattrs_equal(const struct workqueue_attrs *a,
3424 const struct workqueue_attrs *b)
3426 if (a->nice != b->nice)
3428 if (!cpumask_equal(a->cpumask, b->cpumask))
3434 * init_worker_pool - initialize a newly zalloc'd worker_pool
3435 * @pool: worker_pool to initialize
3437 * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
3438 * Returns 0 on success, -errno on failure. Even on failure, all fields
3439 * inside @pool proper are initialized and put_unbound_pool() can be called
3440 * on @pool safely to release it.
3442 static int init_worker_pool(struct worker_pool *pool)
3444 spin_lock_init(&pool->lock);
3447 pool->node = NUMA_NO_NODE;
3448 pool->flags |= POOL_DISASSOCIATED;
3449 INIT_LIST_HEAD(&pool->worklist);
3450 INIT_LIST_HEAD(&pool->idle_list);
3451 hash_init(pool->busy_hash);
3453 init_timer_deferrable(&pool->idle_timer);
3454 pool->idle_timer.function = idle_worker_timeout;
3455 pool->idle_timer.data = (unsigned long)pool;
3457 setup_timer(&pool->mayday_timer, pool_mayday_timeout,
3458 (unsigned long)pool);
3460 mutex_init(&pool->manager_arb);
3461 mutex_init(&pool->manager_mutex);
3462 idr_init(&pool->worker_idr);
3464 INIT_HLIST_NODE(&pool->hash_node);
3467 /* shouldn't fail above this point */
3468 pool->attrs = alloc_workqueue_attrs(GFP_KERNEL);
3474 static void rcu_free_pool(struct rcu_head *rcu)
3476 struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
3478 idr_destroy(&pool->worker_idr);
3479 free_workqueue_attrs(pool->attrs);
3484 * put_unbound_pool - put a worker_pool
3485 * @pool: worker_pool to put
3487 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
3488 * safe manner. get_unbound_pool() calls this function on its failure path
3489 * and this function should be able to release pools which went through,
3490 * successfully or not, init_worker_pool().
3492 * Should be called with wq_pool_mutex held.
3494 static void put_unbound_pool(struct worker_pool *pool)
3496 struct worker *worker;
3498 lockdep_assert_held(&wq_pool_mutex);
3504 if (WARN_ON(!(pool->flags & POOL_DISASSOCIATED)) ||
3505 WARN_ON(!list_empty(&pool->worklist)))
3508 /* release id and unhash */
3510 idr_remove(&worker_pool_idr, pool->id);
3511 hash_del(&pool->hash_node);
3514 * Become the manager and destroy all workers. Grabbing
3515 * manager_arb prevents @pool's workers from blocking on
3518 mutex_lock(&pool->manager_arb);
3519 mutex_lock(&pool->manager_mutex);
3520 spin_lock_irq(&pool->lock);
3522 while ((worker = first_worker(pool)))
3523 destroy_worker(worker);
3524 WARN_ON(pool->nr_workers || pool->nr_idle);
3526 spin_unlock_irq(&pool->lock);
3527 mutex_unlock(&pool->manager_mutex);
3528 mutex_unlock(&pool->manager_arb);
3530 /* shut down the timers */
3531 del_timer_sync(&pool->idle_timer);
3532 del_timer_sync(&pool->mayday_timer);
3534 /* sched-RCU protected to allow dereferences from get_work_pool() */
3535 call_rcu_sched(&pool->rcu, rcu_free_pool);
3539 * get_unbound_pool - get a worker_pool with the specified attributes
3540 * @attrs: the attributes of the worker_pool to get
3542 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3543 * reference count and return it. If there already is a matching
3544 * worker_pool, it will be used; otherwise, this function attempts to
3545 * create a new one. On failure, returns NULL.
3547 * Should be called with wq_pool_mutex held.
3549 static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
3551 u32 hash = wqattrs_hash(attrs);
3552 struct worker_pool *pool;
3555 lockdep_assert_held(&wq_pool_mutex);
3557 /* do we already have a matching pool? */
3558 hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
3559 if (wqattrs_equal(pool->attrs, attrs)) {
3565 /* nope, create a new one */
3566 pool = kzalloc(sizeof(*pool), GFP_KERNEL);
3567 if (!pool || init_worker_pool(pool) < 0)
3570 if (workqueue_freezing)
3571 pool->flags |= POOL_FREEZING;
3573 lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
3574 copy_workqueue_attrs(pool->attrs, attrs);
3576 /* if cpumask is contained inside a NUMA node, we belong to that node */
3577 if (wq_numa_enabled) {
3578 for_each_node(node) {
3579 if (cpumask_subset(pool->attrs->cpumask,
3580 wq_numa_possible_cpumask[node])) {
3587 if (worker_pool_assign_id(pool) < 0)
3590 /* create and start the initial worker */
3591 if (create_and_start_worker(pool) < 0)
3595 hash_add(unbound_pool_hash, &pool->hash_node, hash);
3600 put_unbound_pool(pool);
3604 static void rcu_free_pwq(struct rcu_head *rcu)
3606 kmem_cache_free(pwq_cache,
3607 container_of(rcu, struct pool_workqueue, rcu));
3611 * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3612 * and needs to be destroyed.
3614 static void pwq_unbound_release_workfn(struct work_struct *work)
3616 struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
3617 unbound_release_work);
3618 struct workqueue_struct *wq = pwq->wq;
3619 struct worker_pool *pool = pwq->pool;
3622 if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
3626 * Unlink @pwq. Synchronization against wq->mutex isn't strictly
3627 * necessary on release but do it anyway. It's easier to verify
3628 * and consistent with the linking path.
3630 mutex_lock(&wq->mutex);
3631 list_del_rcu(&pwq->pwqs_node);
3632 is_last = list_empty(&wq->pwqs);
3633 mutex_unlock(&wq->mutex);
3635 mutex_lock(&wq_pool_mutex);
3636 put_unbound_pool(pool);
3637 mutex_unlock(&wq_pool_mutex);
3639 call_rcu_sched(&pwq->rcu, rcu_free_pwq);
3642 * If we're the last pwq going away, @wq is already dead and no one
3643 * is gonna access it anymore. Free it.
3646 free_workqueue_attrs(wq->unbound_attrs);
3652 * pwq_adjust_max_active - update a pwq's max_active to the current setting
3653 * @pwq: target pool_workqueue
3655 * If @pwq isn't freezing, set @pwq->max_active to the associated
3656 * workqueue's saved_max_active and activate delayed work items
3657 * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
3659 static void pwq_adjust_max_active(struct pool_workqueue *pwq)
3661 struct workqueue_struct *wq = pwq->wq;
3662 bool freezable = wq->flags & WQ_FREEZABLE;
3664 /* for @wq->saved_max_active */
3665 lockdep_assert_held(&wq->mutex);
3667 /* fast exit for non-freezable wqs */
3668 if (!freezable && pwq->max_active == wq->saved_max_active)
3671 spin_lock_irq(&pwq->pool->lock);
3673 if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) {
3674 pwq->max_active = wq->saved_max_active;
3676 while (!list_empty(&pwq->delayed_works) &&
3677 pwq->nr_active < pwq->max_active)
3678 pwq_activate_first_delayed(pwq);
3681 * Need to kick a worker after thawed or an unbound wq's
3682 * max_active is bumped. It's a slow path. Do it always.
3684 wake_up_worker(pwq->pool);
3686 pwq->max_active = 0;
3689 spin_unlock_irq(&pwq->pool->lock);
3692 /* initialize newly alloced @pwq which is associated with @wq and @pool */
3693 static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
3694 struct worker_pool *pool)
3696 BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
3698 memset(pwq, 0, sizeof(*pwq));
3702 pwq->flush_color = -1;
3704 INIT_LIST_HEAD(&pwq->delayed_works);
3705 INIT_LIST_HEAD(&pwq->pwqs_node);
3706 INIT_LIST_HEAD(&pwq->mayday_node);
3707 INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
3710 /* sync @pwq with the current state of its associated wq and link it */
3711 static void link_pwq(struct pool_workqueue *pwq)
3713 struct workqueue_struct *wq = pwq->wq;
3715 lockdep_assert_held(&wq->mutex);
3717 /* may be called multiple times, ignore if already linked */
3718 if (!list_empty(&pwq->pwqs_node))
3722 * Set the matching work_color. This is synchronized with
3723 * wq->mutex to avoid confusing flush_workqueue().
3725 pwq->work_color = wq->work_color;
3727 /* sync max_active to the current setting */
3728 pwq_adjust_max_active(pwq);
3731 list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
3734 /* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3735 static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq,
3736 const struct workqueue_attrs *attrs)
3738 struct worker_pool *pool;
3739 struct pool_workqueue *pwq;
3741 lockdep_assert_held(&wq_pool_mutex);
3743 pool = get_unbound_pool(attrs);
3747 pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
3749 put_unbound_pool(pool);
3753 init_pwq(pwq, wq, pool);
3757 /* undo alloc_unbound_pwq(), used only in the error path */
3758 static void free_unbound_pwq(struct pool_workqueue *pwq)
3760 lockdep_assert_held(&wq_pool_mutex);
3763 put_unbound_pool(pwq->pool);
3764 kmem_cache_free(pwq_cache, pwq);
3769 * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node
3770 * @attrs: the wq_attrs of interest
3771 * @node: the target NUMA node
3772 * @cpu_going_down: if >= 0, the CPU to consider as offline
3773 * @cpumask: outarg, the resulting cpumask
3775 * Calculate the cpumask a workqueue with @attrs should use on @node. If
3776 * @cpu_going_down is >= 0, that cpu is considered offline during
3777 * calculation. The result is stored in @cpumask. This function returns
3778 * %true if the resulting @cpumask is different from @attrs->cpumask,
3781 * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3782 * enabled and @node has online CPUs requested by @attrs, the returned
3783 * cpumask is the intersection of the possible CPUs of @node and
3786 * The caller is responsible for ensuring that the cpumask of @node stays
3789 static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
3790 int cpu_going_down, cpumask_t *cpumask)
3792 if (!wq_numa_enabled || attrs->no_numa)
3795 /* does @node have any online CPUs @attrs wants? */
3796 cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask);
3797 if (cpu_going_down >= 0)
3798 cpumask_clear_cpu(cpu_going_down, cpumask);
3800 if (cpumask_empty(cpumask))
3803 /* yeap, return possible CPUs in @node that @attrs wants */
3804 cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
3805 return !cpumask_equal(cpumask, attrs->cpumask);
3808 cpumask_copy(cpumask, attrs->cpumask);
3812 /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3813 static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
3815 struct pool_workqueue *pwq)
3817 struct pool_workqueue *old_pwq;
3819 lockdep_assert_held(&wq->mutex);
3821 /* link_pwq() can handle duplicate calls */
3824 old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
3825 rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
3830 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
3831 * @wq: the target workqueue
3832 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
3834 * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
3835 * machines, this function maps a separate pwq to each NUMA node with
3836 * possibles CPUs in @attrs->cpumask so that work items are affine to the
3837 * NUMA node it was issued on. Older pwqs are released as in-flight work
3838 * items finish. Note that a work item which repeatedly requeues itself
3839 * back-to-back will stay on its current pwq.
3841 * Performs GFP_KERNEL allocations. Returns 0 on success and -errno on
3844 int apply_workqueue_attrs(struct workqueue_struct *wq,
3845 const struct workqueue_attrs *attrs)
3847 struct workqueue_attrs *new_attrs, *tmp_attrs;
3848 struct pool_workqueue **pwq_tbl, *dfl_pwq;
3851 /* only unbound workqueues can change attributes */
3852 if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
3855 /* creating multiple pwqs breaks ordering guarantee */
3856 if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
3859 pwq_tbl = kzalloc(wq_numa_tbl_len * sizeof(pwq_tbl[0]), GFP_KERNEL);
3860 new_attrs = alloc_workqueue_attrs(GFP_KERNEL);
3861 tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL);
3862 if (!pwq_tbl || !new_attrs || !tmp_attrs)
3865 /* make a copy of @attrs and sanitize it */
3866 copy_workqueue_attrs(new_attrs, attrs);
3867 cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
3870 * We may create multiple pwqs with differing cpumasks. Make a
3871 * copy of @new_attrs which will be modified and used to obtain
3874 copy_workqueue_attrs(tmp_attrs, new_attrs);
3877 * CPUs should stay stable across pwq creations and installations.
3878 * Pin CPUs, determine the target cpumask for each node and create
3883 mutex_lock(&wq_pool_mutex);
3886 * If something goes wrong during CPU up/down, we'll fall back to
3887 * the default pwq covering whole @attrs->cpumask. Always create
3888 * it even if we don't use it immediately.
3890 dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
3894 for_each_node(node) {
3895 if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) {
3896 pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
3901 pwq_tbl[node] = dfl_pwq;
3905 mutex_unlock(&wq_pool_mutex);
3907 /* all pwqs have been created successfully, let's install'em */
3908 mutex_lock(&wq->mutex);
3910 copy_workqueue_attrs(wq->unbound_attrs, new_attrs);
3912 /* save the previous pwq and install the new one */
3914 pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]);
3916 /* @dfl_pwq might not have been used, ensure it's linked */
3918 swap(wq->dfl_pwq, dfl_pwq);
3920 mutex_unlock(&wq->mutex);
3922 /* put the old pwqs */
3924 put_pwq_unlocked(pwq_tbl[node]);
3925 put_pwq_unlocked(dfl_pwq);
3931 free_workqueue_attrs(tmp_attrs);
3932 free_workqueue_attrs(new_attrs);
3937 free_unbound_pwq(dfl_pwq);
3939 if (pwq_tbl && pwq_tbl[node] != dfl_pwq)
3940 free_unbound_pwq(pwq_tbl[node]);
3941 mutex_unlock(&wq_pool_mutex);
3949 * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
3950 * @wq: the target workqueue
3951 * @cpu: the CPU coming up or going down
3952 * @online: whether @cpu is coming up or going down
3954 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
3955 * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
3958 * If NUMA affinity can't be adjusted due to memory allocation failure, it
3959 * falls back to @wq->dfl_pwq which may not be optimal but is always
3962 * Note that when the last allowed CPU of a NUMA node goes offline for a
3963 * workqueue with a cpumask spanning multiple nodes, the workers which were
3964 * already executing the work items for the workqueue will lose their CPU
3965 * affinity and may execute on any CPU. This is similar to how per-cpu
3966 * workqueues behave on CPU_DOWN. If a workqueue user wants strict
3967 * affinity, it's the user's responsibility to flush the work item from
3970 static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
3973 int node = cpu_to_node(cpu);
3974 int cpu_off = online ? -1 : cpu;
3975 struct pool_workqueue *old_pwq = NULL, *pwq;
3976 struct workqueue_attrs *target_attrs;
3979 lockdep_assert_held(&wq_pool_mutex);
3981 if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND))
3985 * We don't wanna alloc/free wq_attrs for each wq for each CPU.
3986 * Let's use a preallocated one. The following buf is protected by
3987 * CPU hotplug exclusion.
3989 target_attrs = wq_update_unbound_numa_attrs_buf;
3990 cpumask = target_attrs->cpumask;
3992 mutex_lock(&wq->mutex);
3993 if (wq->unbound_attrs->no_numa)
3996 copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
3997 pwq = unbound_pwq_by_node(wq, node);
4000 * Let's determine what needs to be done. If the target cpumask is
4001 * different from wq's, we need to compare it to @pwq's and create
4002 * a new one if they don't match. If the target cpumask equals
4003 * wq's, the default pwq should be used. If @pwq is already the
4004 * default one, nothing to do; otherwise, install the default one.
4006 if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) {
4007 if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
4010 if (pwq == wq->dfl_pwq)
4016 mutex_unlock(&wq->mutex);
4018 /* create a new pwq */
4019 pwq = alloc_unbound_pwq(wq, target_attrs);
4021 pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
4027 * Install the new pwq. As this function is called only from CPU
4028 * hotplug callbacks and applying a new attrs is wrapped with
4029 * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
4032 mutex_lock(&wq->mutex);
4033 old_pwq = numa_pwq_tbl_install(wq, node, pwq);
4037 spin_lock_irq(&wq->dfl_pwq->pool->lock);
4038 get_pwq(wq->dfl_pwq);
4039 spin_unlock_irq(&wq->dfl_pwq->pool->lock);
4040 old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
4042 mutex_unlock(&wq->mutex);
4043 put_pwq_unlocked(old_pwq);
4046 static int alloc_and_link_pwqs(struct workqueue_struct *wq)
4048 bool highpri = wq->flags & WQ_HIGHPRI;
4051 if (!(wq->flags & WQ_UNBOUND)) {
4052 wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
4056 for_each_possible_cpu(cpu) {
4057 struct pool_workqueue *pwq =
4058 per_cpu_ptr(wq->cpu_pwqs, cpu);
4059 struct worker_pool *cpu_pools =
4060 per_cpu(cpu_worker_pools, cpu);
4062 init_pwq(pwq, wq, &cpu_pools[highpri]);
4064 mutex_lock(&wq->mutex);
4066 mutex_unlock(&wq->mutex);
4070 return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
4074 static int wq_clamp_max_active(int max_active, unsigned int flags,
4077 int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
4079 if (max_active < 1 || max_active > lim)
4080 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
4081 max_active, name, 1, lim);
4083 return clamp_val(max_active, 1, lim);
4086 struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
4089 struct lock_class_key *key,
4090 const char *lock_name, ...)
4092 size_t tbl_size = 0;
4094 struct workqueue_struct *wq;
4095 struct pool_workqueue *pwq;
4097 /* see the comment above the definition of WQ_POWER_EFFICIENT */
4098 if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
4099 flags |= WQ_UNBOUND;
4101 /* allocate wq and format name */
4102 if (flags & WQ_UNBOUND)
4103 tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]);
4105 wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL);
4109 if (flags & WQ_UNBOUND) {
4110 wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL);
4111 if (!wq->unbound_attrs)
4115 va_start(args, lock_name);
4116 vsnprintf(wq->name, sizeof(wq->name), fmt, args);
4119 max_active = max_active ?: WQ_DFL_ACTIVE;
4120 max_active = wq_clamp_max_active(max_active, flags, wq->name);
4124 wq->saved_max_active = max_active;
4125 mutex_init(&wq->mutex);
4126 atomic_set(&wq->nr_pwqs_to_flush, 0);
4127 INIT_LIST_HEAD(&wq->pwqs);
4128 INIT_LIST_HEAD(&wq->flusher_queue);
4129 INIT_LIST_HEAD(&wq->flusher_overflow);
4130 INIT_LIST_HEAD(&wq->maydays);
4132 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
4133 INIT_LIST_HEAD(&wq->list);
4135 if (alloc_and_link_pwqs(wq) < 0)
4139 * Workqueues which may be used during memory reclaim should
4140 * have a rescuer to guarantee forward progress.
4142 if (flags & WQ_MEM_RECLAIM) {
4143 struct worker *rescuer;
4145 rescuer = alloc_worker();
4149 rescuer->rescue_wq = wq;
4150 rescuer->task = kthread_create(rescuer_thread, rescuer, "%s",
4152 if (IS_ERR(rescuer->task)) {
4157 wq->rescuer = rescuer;
4158 rescuer->task->flags |= PF_NO_SETAFFINITY;
4159 wake_up_process(rescuer->task);
4162 if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
4166 * wq_pool_mutex protects global freeze state and workqueues list.
4167 * Grab it, adjust max_active and add the new @wq to workqueues
4170 mutex_lock(&wq_pool_mutex);
4172 mutex_lock(&wq->mutex);
4173 for_each_pwq(pwq, wq)
4174 pwq_adjust_max_active(pwq);
4175 mutex_unlock(&wq->mutex);
4177 list_add(&wq->list, &workqueues);
4179 mutex_unlock(&wq_pool_mutex);
4184 free_workqueue_attrs(wq->unbound_attrs);
4188 destroy_workqueue(wq);
4191 EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
4194 * destroy_workqueue - safely terminate a workqueue
4195 * @wq: target workqueue
4197 * Safely destroy a workqueue. All work currently pending will be done first.
4199 void destroy_workqueue(struct workqueue_struct *wq)
4201 struct pool_workqueue *pwq;
4204 /* drain it before proceeding with destruction */
4205 drain_workqueue(wq);
4208 mutex_lock(&wq->mutex);
4209 for_each_pwq(pwq, wq) {
4212 for (i = 0; i < WORK_NR_COLORS; i++) {
4213 if (WARN_ON(pwq->nr_in_flight[i])) {
4214 mutex_unlock(&wq->mutex);
4219 if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) ||
4220 WARN_ON(pwq->nr_active) ||
4221 WARN_ON(!list_empty(&pwq->delayed_works))) {
4222 mutex_unlock(&wq->mutex);
4226 mutex_unlock(&wq->mutex);
4229 * wq list is used to freeze wq, remove from list after
4230 * flushing is complete in case freeze races us.
4232 mutex_lock(&wq_pool_mutex);
4233 list_del_init(&wq->list);
4234 mutex_unlock(&wq_pool_mutex);
4236 workqueue_sysfs_unregister(wq);
4239 kthread_stop(wq->rescuer->task);
4244 if (!(wq->flags & WQ_UNBOUND)) {
4246 * The base ref is never dropped on per-cpu pwqs. Directly
4247 * free the pwqs and wq.
4249 free_percpu(wq->cpu_pwqs);
4253 * We're the sole accessor of @wq at this point. Directly
4254 * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
4255 * @wq will be freed when the last pwq is released.
4257 for_each_node(node) {
4258 pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
4259 RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL);
4260 put_pwq_unlocked(pwq);
4264 * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
4265 * put. Don't access it afterwards.
4269 put_pwq_unlocked(pwq);
4272 EXPORT_SYMBOL_GPL(destroy_workqueue);
4275 * workqueue_set_max_active - adjust max_active of a workqueue
4276 * @wq: target workqueue
4277 * @max_active: new max_active value.
4279 * Set max_active of @wq to @max_active.
4282 * Don't call from IRQ context.
4284 void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
4286 struct pool_workqueue *pwq;
4288 /* disallow meddling with max_active for ordered workqueues */
4289 if (WARN_ON(wq->flags & __WQ_ORDERED))
4292 max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
4294 mutex_lock(&wq->mutex);
4296 wq->saved_max_active = max_active;
4298 for_each_pwq(pwq, wq)
4299 pwq_adjust_max_active(pwq);
4301 mutex_unlock(&wq->mutex);
4303 EXPORT_SYMBOL_GPL(workqueue_set_max_active);
4306 * current_is_workqueue_rescuer - is %current workqueue rescuer?
4308 * Determine whether %current is a workqueue rescuer. Can be used from
4309 * work functions to determine whether it's being run off the rescuer task.
4311 bool current_is_workqueue_rescuer(void)
4313 struct worker *worker = current_wq_worker();
4315 return worker && worker->rescue_wq;
4319 * workqueue_congested - test whether a workqueue is congested
4320 * @cpu: CPU in question
4321 * @wq: target workqueue
4323 * Test whether @wq's cpu workqueue for @cpu is congested. There is
4324 * no synchronization around this function and the test result is
4325 * unreliable and only useful as advisory hints or for debugging.
4328 * %true if congested, %false otherwise.
4330 bool workqueue_congested(int cpu, struct workqueue_struct *wq)
4332 struct pool_workqueue *pwq;
4335 rcu_read_lock_sched();
4337 if (!(wq->flags & WQ_UNBOUND))
4338 pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
4340 pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
4342 ret = !list_empty(&pwq->delayed_works);
4343 rcu_read_unlock_sched();
4347 EXPORT_SYMBOL_GPL(workqueue_congested);
4350 * work_busy - test whether a work is currently pending or running
4351 * @work: the work to be tested
4353 * Test whether @work is currently pending or running. There is no
4354 * synchronization around this function and the test result is
4355 * unreliable and only useful as advisory hints or for debugging.
4358 * OR'd bitmask of WORK_BUSY_* bits.
4360 unsigned int work_busy(struct work_struct *work)
4362 struct worker_pool *pool;
4363 unsigned long flags;
4364 unsigned int ret = 0;
4366 if (work_pending(work))
4367 ret |= WORK_BUSY_PENDING;
4369 local_irq_save(flags);
4370 pool = get_work_pool(work);
4372 spin_lock(&pool->lock);
4373 if (find_worker_executing_work(pool, work))
4374 ret |= WORK_BUSY_RUNNING;
4375 spin_unlock(&pool->lock);
4377 local_irq_restore(flags);
4381 EXPORT_SYMBOL_GPL(work_busy);
4384 * set_worker_desc - set description for the current work item
4385 * @fmt: printf-style format string
4386 * @...: arguments for the format string
4388 * This function can be called by a running work function to describe what
4389 * the work item is about. If the worker task gets dumped, this
4390 * information will be printed out together to help debugging. The
4391 * description can be at most WORKER_DESC_LEN including the trailing '\0'.
4393 void set_worker_desc(const char *fmt, ...)
4395 struct worker *worker = current_wq_worker();
4399 va_start(args, fmt);
4400 vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
4402 worker->desc_valid = true;
4407 * print_worker_info - print out worker information and description
4408 * @log_lvl: the log level to use when printing
4409 * @task: target task
4411 * If @task is a worker and currently executing a work item, print out the
4412 * name of the workqueue being serviced and worker description set with
4413 * set_worker_desc() by the currently executing work item.
4415 * This function can be safely called on any task as long as the
4416 * task_struct itself is accessible. While safe, this function isn't
4417 * synchronized and may print out mixups or garbages of limited length.
4419 void print_worker_info(const char *log_lvl, struct task_struct *task)
4421 work_func_t *fn = NULL;
4422 char name[WQ_NAME_LEN] = { };
4423 char desc[WORKER_DESC_LEN] = { };
4424 struct pool_workqueue *pwq = NULL;
4425 struct workqueue_struct *wq = NULL;
4426 bool desc_valid = false;
4427 struct worker *worker;
4429 if (!(task->flags & PF_WQ_WORKER))
4433 * This function is called without any synchronization and @task
4434 * could be in any state. Be careful with dereferences.
4436 worker = probe_kthread_data(task);
4439 * Carefully copy the associated workqueue's workfn and name. Keep
4440 * the original last '\0' in case the original contains garbage.
4442 probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
4443 probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
4444 probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
4445 probe_kernel_read(name, wq->name, sizeof(name) - 1);
4447 /* copy worker description */
4448 probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid));
4450 probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
4452 if (fn || name[0] || desc[0]) {
4453 printk("%sWorkqueue: %s %pf", log_lvl, name, fn);
4455 pr_cont(" (%s)", desc);
4463 * There are two challenges in supporting CPU hotplug. Firstly, there
4464 * are a lot of assumptions on strong associations among work, pwq and
4465 * pool which make migrating pending and scheduled works very
4466 * difficult to implement without impacting hot paths. Secondly,
4467 * worker pools serve mix of short, long and very long running works making
4468 * blocked draining impractical.
4470 * This is solved by allowing the pools to be disassociated from the CPU
4471 * running as an unbound one and allowing it to be reattached later if the
4472 * cpu comes back online.
4475 static void wq_unbind_fn(struct work_struct *work)
4477 int cpu = smp_processor_id();
4478 struct worker_pool *pool;
4479 struct worker *worker;
4482 for_each_cpu_worker_pool(pool, cpu) {
4483 WARN_ON_ONCE(cpu != smp_processor_id());
4485 mutex_lock(&pool->manager_mutex);
4486 spin_lock_irq(&pool->lock);
4489 * We've blocked all manager operations. Make all workers
4490 * unbound and set DISASSOCIATED. Before this, all workers
4491 * except for the ones which are still executing works from
4492 * before the last CPU down must be on the cpu. After
4493 * this, they may become diasporas.
4495 for_each_pool_worker(worker, wi, pool)
4496 worker->flags |= WORKER_UNBOUND;
4498 pool->flags |= POOL_DISASSOCIATED;
4500 spin_unlock_irq(&pool->lock);
4501 mutex_unlock(&pool->manager_mutex);
4504 * Call schedule() so that we cross rq->lock and thus can
4505 * guarantee sched callbacks see the %WORKER_UNBOUND flag.
4506 * This is necessary as scheduler callbacks may be invoked
4512 * Sched callbacks are disabled now. Zap nr_running.
4513 * After this, nr_running stays zero and need_more_worker()
4514 * and keep_working() are always true as long as the
4515 * worklist is not empty. This pool now behaves as an
4516 * unbound (in terms of concurrency management) pool which
4517 * are served by workers tied to the pool.
4519 atomic_set(&pool->nr_running, 0);
4522 * With concurrency management just turned off, a busy
4523 * worker blocking could lead to lengthy stalls. Kick off
4524 * unbound chain execution of currently pending work items.
4526 spin_lock_irq(&pool->lock);
4527 wake_up_worker(pool);
4528 spin_unlock_irq(&pool->lock);
4533 * rebind_workers - rebind all workers of a pool to the associated CPU
4534 * @pool: pool of interest
4536 * @pool->cpu is coming online. Rebind all workers to the CPU.
4538 static void rebind_workers(struct worker_pool *pool)
4540 struct worker *worker;
4543 lockdep_assert_held(&pool->manager_mutex);
4546 * Restore CPU affinity of all workers. As all idle workers should
4547 * be on the run-queue of the associated CPU before any local
4548 * wake-ups for concurrency management happen, restore CPU affinty
4549 * of all workers first and then clear UNBOUND. As we're called
4550 * from CPU_ONLINE, the following shouldn't fail.
4552 for_each_pool_worker(worker, wi, pool)
4553 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4554 pool->attrs->cpumask) < 0);
4556 spin_lock_irq(&pool->lock);
4558 for_each_pool_worker(worker, wi, pool) {
4559 unsigned int worker_flags = worker->flags;
4562 * A bound idle worker should actually be on the runqueue
4563 * of the associated CPU for local wake-ups targeting it to
4564 * work. Kick all idle workers so that they migrate to the
4565 * associated CPU. Doing this in the same loop as
4566 * replacing UNBOUND with REBOUND is safe as no worker will
4567 * be bound before @pool->lock is released.
4569 if (worker_flags & WORKER_IDLE)
4570 wake_up_process(worker->task);
4573 * We want to clear UNBOUND but can't directly call
4574 * worker_clr_flags() or adjust nr_running. Atomically
4575 * replace UNBOUND with another NOT_RUNNING flag REBOUND.
4576 * @worker will clear REBOUND using worker_clr_flags() when
4577 * it initiates the next execution cycle thus restoring
4578 * concurrency management. Note that when or whether
4579 * @worker clears REBOUND doesn't affect correctness.
4581 * ACCESS_ONCE() is necessary because @worker->flags may be
4582 * tested without holding any lock in
4583 * wq_worker_waking_up(). Without it, NOT_RUNNING test may
4584 * fail incorrectly leading to premature concurrency
4585 * management operations.
4587 WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
4588 worker_flags |= WORKER_REBOUND;
4589 worker_flags &= ~WORKER_UNBOUND;
4590 ACCESS_ONCE(worker->flags) = worker_flags;
4593 spin_unlock_irq(&pool->lock);
4597 * restore_unbound_workers_cpumask - restore cpumask of unbound workers
4598 * @pool: unbound pool of interest
4599 * @cpu: the CPU which is coming up
4601 * An unbound pool may end up with a cpumask which doesn't have any online
4602 * CPUs. When a worker of such pool get scheduled, the scheduler resets
4603 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4604 * online CPU before, cpus_allowed of all its workers should be restored.
4606 static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
4608 static cpumask_t cpumask;
4609 struct worker *worker;
4612 lockdep_assert_held(&pool->manager_mutex);
4614 /* is @cpu allowed for @pool? */
4615 if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
4618 /* is @cpu the only online CPU? */
4619 cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
4620 if (cpumask_weight(&cpumask) != 1)
4623 /* as we're called from CPU_ONLINE, the following shouldn't fail */
4624 for_each_pool_worker(worker, wi, pool)
4625 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4626 pool->attrs->cpumask) < 0);
4630 * Workqueues should be brought up before normal priority CPU notifiers.
4631 * This will be registered high priority CPU notifier.
4633 static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb,
4634 unsigned long action,
4637 int cpu = (unsigned long)hcpu;
4638 struct worker_pool *pool;
4639 struct workqueue_struct *wq;
4642 switch (action & ~CPU_TASKS_FROZEN) {
4643 case CPU_UP_PREPARE:
4644 for_each_cpu_worker_pool(pool, cpu) {
4645 if (pool->nr_workers)
4647 if (create_and_start_worker(pool) < 0)
4652 case CPU_DOWN_FAILED:
4654 mutex_lock(&wq_pool_mutex);
4656 for_each_pool(pool, pi) {
4657 mutex_lock(&pool->manager_mutex);
4659 if (pool->cpu == cpu) {
4660 spin_lock_irq(&pool->lock);
4661 pool->flags &= ~POOL_DISASSOCIATED;
4662 spin_unlock_irq(&pool->lock);
4664 rebind_workers(pool);
4665 } else if (pool->cpu < 0) {
4666 restore_unbound_workers_cpumask(pool, cpu);
4669 mutex_unlock(&pool->manager_mutex);
4672 /* update NUMA affinity of unbound workqueues */
4673 list_for_each_entry(wq, &workqueues, list)
4674 wq_update_unbound_numa(wq, cpu, true);
4676 mutex_unlock(&wq_pool_mutex);
4683 * Workqueues should be brought down after normal priority CPU notifiers.
4684 * This will be registered as low priority CPU notifier.
4686 static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb,
4687 unsigned long action,
4690 int cpu = (unsigned long)hcpu;
4691 struct work_struct unbind_work;
4692 struct workqueue_struct *wq;
4694 switch (action & ~CPU_TASKS_FROZEN) {
4695 case CPU_DOWN_PREPARE:
4696 /* unbinding per-cpu workers should happen on the local CPU */
4697 INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
4698 queue_work_on(cpu, system_highpri_wq, &unbind_work);
4700 /* update NUMA affinity of unbound workqueues */
4701 mutex_lock(&wq_pool_mutex);
4702 list_for_each_entry(wq, &workqueues, list)
4703 wq_update_unbound_numa(wq, cpu, false);
4704 mutex_unlock(&wq_pool_mutex);
4706 /* wait for per-cpu unbinding to finish */
4707 flush_work(&unbind_work);
4715 struct work_for_cpu {
4716 struct work_struct work;
4722 static void work_for_cpu_fn(struct work_struct *work)
4724 struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
4726 wfc->ret = wfc->fn(wfc->arg);
4730 * work_on_cpu - run a function in user context on a particular cpu
4731 * @cpu: the cpu to run on
4732 * @fn: the function to run
4733 * @arg: the function arg
4735 * This will return the value @fn returns.
4736 * It is up to the caller to ensure that the cpu doesn't go offline.
4737 * The caller must not hold any locks which would prevent @fn from completing.
4739 long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
4741 struct work_for_cpu wfc = { .fn = fn, .arg = arg };
4743 INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
4744 schedule_work_on(cpu, &wfc.work);
4745 flush_work(&wfc.work);
4748 EXPORT_SYMBOL_GPL(work_on_cpu);
4749 #endif /* CONFIG_SMP */
4751 #ifdef CONFIG_FREEZER
4754 * freeze_workqueues_begin - begin freezing workqueues
4756 * Start freezing workqueues. After this function returns, all freezable
4757 * workqueues will queue new works to their delayed_works list instead of
4761 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4763 void freeze_workqueues_begin(void)
4765 struct worker_pool *pool;
4766 struct workqueue_struct *wq;
4767 struct pool_workqueue *pwq;
4770 mutex_lock(&wq_pool_mutex);
4772 WARN_ON_ONCE(workqueue_freezing);
4773 workqueue_freezing = true;
4776 for_each_pool(pool, pi) {
4777 spin_lock_irq(&pool->lock);
4778 WARN_ON_ONCE(pool->flags & POOL_FREEZING);
4779 pool->flags |= POOL_FREEZING;
4780 spin_unlock_irq(&pool->lock);
4783 list_for_each_entry(wq, &workqueues, list) {
4784 mutex_lock(&wq->mutex);
4785 for_each_pwq(pwq, wq)
4786 pwq_adjust_max_active(pwq);
4787 mutex_unlock(&wq->mutex);
4790 mutex_unlock(&wq_pool_mutex);
4794 * freeze_workqueues_busy - are freezable workqueues still busy?
4796 * Check whether freezing is complete. This function must be called
4797 * between freeze_workqueues_begin() and thaw_workqueues().
4800 * Grabs and releases wq_pool_mutex.
4803 * %true if some freezable workqueues are still busy. %false if freezing
4806 bool freeze_workqueues_busy(void)
4809 struct workqueue_struct *wq;
4810 struct pool_workqueue *pwq;
4812 mutex_lock(&wq_pool_mutex);
4814 WARN_ON_ONCE(!workqueue_freezing);
4816 list_for_each_entry(wq, &workqueues, list) {
4817 if (!(wq->flags & WQ_FREEZABLE))
4820 * nr_active is monotonically decreasing. It's safe
4821 * to peek without lock.
4823 rcu_read_lock_sched();
4824 for_each_pwq(pwq, wq) {
4825 WARN_ON_ONCE(pwq->nr_active < 0);
4826 if (pwq->nr_active) {
4828 rcu_read_unlock_sched();
4832 rcu_read_unlock_sched();
4835 mutex_unlock(&wq_pool_mutex);
4840 * thaw_workqueues - thaw workqueues
4842 * Thaw workqueues. Normal queueing is restored and all collected
4843 * frozen works are transferred to their respective pool worklists.
4846 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4848 void thaw_workqueues(void)
4850 struct workqueue_struct *wq;
4851 struct pool_workqueue *pwq;
4852 struct worker_pool *pool;
4855 mutex_lock(&wq_pool_mutex);
4857 if (!workqueue_freezing)
4860 /* clear FREEZING */
4861 for_each_pool(pool, pi) {
4862 spin_lock_irq(&pool->lock);
4863 WARN_ON_ONCE(!(pool->flags & POOL_FREEZING));
4864 pool->flags &= ~POOL_FREEZING;
4865 spin_unlock_irq(&pool->lock);
4868 /* restore max_active and repopulate worklist */
4869 list_for_each_entry(wq, &workqueues, list) {
4870 mutex_lock(&wq->mutex);
4871 for_each_pwq(pwq, wq)
4872 pwq_adjust_max_active(pwq);
4873 mutex_unlock(&wq->mutex);
4876 workqueue_freezing = false;
4878 mutex_unlock(&wq_pool_mutex);
4880 #endif /* CONFIG_FREEZER */
4882 static void __init wq_numa_init(void)
4887 /* determine NUMA pwq table len - highest node id + 1 */
4889 wq_numa_tbl_len = max(wq_numa_tbl_len, node + 1);
4891 if (num_possible_nodes() <= 1)
4894 if (wq_disable_numa) {
4895 pr_info("workqueue: NUMA affinity support disabled\n");
4899 wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL);
4900 BUG_ON(!wq_update_unbound_numa_attrs_buf);
4903 * We want masks of possible CPUs of each node which isn't readily
4904 * available. Build one from cpu_to_node() which should have been
4905 * fully initialized by now.
4907 tbl = kzalloc(wq_numa_tbl_len * sizeof(tbl[0]), GFP_KERNEL);
4911 BUG_ON(!alloc_cpumask_var_node(&tbl[node], GFP_KERNEL, node));
4913 for_each_possible_cpu(cpu) {
4914 node = cpu_to_node(cpu);
4915 if (WARN_ON(node == NUMA_NO_NODE)) {
4916 pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
4917 /* happens iff arch is bonkers, let's just proceed */
4920 cpumask_set_cpu(cpu, tbl[node]);
4923 wq_numa_possible_cpumask = tbl;
4924 wq_numa_enabled = true;
4927 static int __init init_workqueues(void)
4929 int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
4932 /* make sure we have enough bits for OFFQ pool ID */
4933 BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) <
4934 WORK_CPU_END * NR_STD_WORKER_POOLS);
4936 WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
4938 pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
4940 cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
4941 hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
4945 /* initialize CPU pools */
4946 for_each_possible_cpu(cpu) {
4947 struct worker_pool *pool;
4950 for_each_cpu_worker_pool(pool, cpu) {
4951 BUG_ON(init_worker_pool(pool));
4953 cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
4954 pool->attrs->nice = std_nice[i++];
4955 pool->node = cpu_to_node(cpu);
4958 mutex_lock(&wq_pool_mutex);
4959 BUG_ON(worker_pool_assign_id(pool));
4960 mutex_unlock(&wq_pool_mutex);
4964 /* create the initial worker */
4965 for_each_online_cpu(cpu) {
4966 struct worker_pool *pool;
4968 for_each_cpu_worker_pool(pool, cpu) {
4969 pool->flags &= ~POOL_DISASSOCIATED;
4970 BUG_ON(create_and_start_worker(pool) < 0);
4974 /* create default unbound wq attrs */
4975 for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
4976 struct workqueue_attrs *attrs;
4978 BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
4979 attrs->nice = std_nice[i];
4980 unbound_std_wq_attrs[i] = attrs;
4983 system_wq = alloc_workqueue("events", 0, 0);
4984 system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
4985 system_long_wq = alloc_workqueue("events_long", 0, 0);
4986 system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
4987 WQ_UNBOUND_MAX_ACTIVE);
4988 system_freezable_wq = alloc_workqueue("events_freezable",
4990 BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||
4991 !system_unbound_wq || !system_freezable_wq);
4994 early_initcall(init_workqueues);