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 are two worker pools for each CPU (one for
20 * normal work items and the other for high priority ones) and some extra
21 * pools for workqueues which are not bound to any specific CPU - the
22 * number of these backing pools is dynamic.
24 * Please read Documentation/workqueue.txt for details.
27 #include <linux/export.h>
28 #include <linux/kernel.h>
29 #include <linux/sched.h>
30 #include <linux/init.h>
31 #include <linux/signal.h>
32 #include <linux/completion.h>
33 #include <linux/workqueue.h>
34 #include <linux/slab.h>
35 #include <linux/cpu.h>
36 #include <linux/notifier.h>
37 #include <linux/kthread.h>
38 #include <linux/hardirq.h>
39 #include <linux/mempolicy.h>
40 #include <linux/freezer.h>
41 #include <linux/kallsyms.h>
42 #include <linux/debug_locks.h>
43 #include <linux/lockdep.h>
44 #include <linux/idr.h>
45 #include <linux/jhash.h>
46 #include <linux/hashtable.h>
47 #include <linux/rculist.h>
48 #include <linux/nodemask.h>
49 #include <linux/moduleparam.h>
50 #include <linux/uaccess.h>
52 #include "workqueue_internal.h"
58 * A bound pool is either associated or disassociated with its CPU.
59 * While associated (!DISASSOCIATED), all workers are bound to the
60 * CPU and none has %WORKER_UNBOUND set and concurrency management
63 * While DISASSOCIATED, the cpu may be offline and all workers have
64 * %WORKER_UNBOUND set and concurrency management disabled, and may
65 * be executing on any CPU. The pool behaves as an unbound one.
67 * Note that DISASSOCIATED should be flipped only while holding
68 * attach_mutex to avoid changing binding state while
69 * worker_attach_to_pool() is in progress.
71 POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
74 WORKER_DIE = 1 << 1, /* die die die */
75 WORKER_IDLE = 1 << 2, /* is idle */
76 WORKER_PREP = 1 << 3, /* preparing to run works */
77 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
78 WORKER_UNBOUND = 1 << 7, /* worker is unbound */
79 WORKER_REBOUND = 1 << 8, /* worker was rebound */
81 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE |
82 WORKER_UNBOUND | WORKER_REBOUND,
84 NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
86 UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
87 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
89 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
90 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
92 MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
93 /* call for help after 10ms
95 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
96 CREATE_COOLDOWN = HZ, /* time to breath after fail */
99 * Rescue workers are used only on emergencies and shared by
100 * all cpus. Give MIN_NICE.
102 RESCUER_NICE_LEVEL = MIN_NICE,
103 HIGHPRI_NICE_LEVEL = MIN_NICE,
109 * Structure fields follow one of the following exclusion rules.
111 * I: Modifiable by initialization/destruction paths and read-only for
114 * P: Preemption protected. Disabling preemption is enough and should
115 * only be modified and accessed from the local cpu.
117 * L: pool->lock protected. Access with pool->lock held.
119 * X: During normal operation, modification requires pool->lock and should
120 * be done only from local cpu. Either disabling preemption on local
121 * cpu or grabbing pool->lock is enough for read access. If
122 * POOL_DISASSOCIATED is set, it's identical to L.
124 * A: pool->attach_mutex protected.
126 * PL: wq_pool_mutex protected.
128 * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
130 * WQ: wq->mutex protected.
132 * WR: wq->mutex protected for writes. Sched-RCU protected for reads.
134 * MD: wq_mayday_lock protected.
137 /* struct worker is defined in workqueue_internal.h */
140 spinlock_t lock; /* the pool lock */
141 int cpu; /* I: the associated cpu */
142 int node; /* I: the associated node ID */
143 int id; /* I: pool ID */
144 unsigned int flags; /* X: flags */
146 struct list_head worklist; /* L: list of pending works */
147 int nr_workers; /* L: total number of workers */
149 /* nr_idle includes the ones off idle_list for rebinding */
150 int nr_idle; /* L: currently idle ones */
152 struct list_head idle_list; /* X: list of idle workers */
153 struct timer_list idle_timer; /* L: worker idle timeout */
154 struct timer_list mayday_timer; /* L: SOS timer for workers */
156 /* a workers is either on busy_hash or idle_list, or the manager */
157 DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
158 /* L: hash of busy workers */
160 /* see manage_workers() for details on the two manager mutexes */
161 struct mutex manager_arb; /* manager arbitration */
162 struct mutex attach_mutex; /* attach/detach exclusion */
163 struct list_head workers; /* A: attached workers */
164 struct completion *detach_completion; /* all workers detached */
166 struct ida worker_ida; /* worker IDs for task name */
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 cpumask_var_t *wq_numa_possible_cpumask;
269 /* possible CPUs of each node */
271 static bool wq_disable_numa;
272 module_param_named(disable_numa, wq_disable_numa, bool, 0444);
274 /* see the comment above the definition of WQ_POWER_EFFICIENT */
275 #ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
276 static bool wq_power_efficient = true;
278 static bool wq_power_efficient;
281 module_param_named(power_efficient, wq_power_efficient, bool, 0444);
283 static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
285 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
286 static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
288 static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
289 static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
291 static LIST_HEAD(workqueues); /* PL: list of all workqueues */
292 static bool workqueue_freezing; /* PL: have wqs started freezing? */
294 /* the per-cpu worker pools */
295 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
298 static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
300 /* PL: hash of all unbound pools keyed by pool->attrs */
301 static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
303 /* I: attributes used when instantiating standard unbound pools on demand */
304 static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
306 /* I: attributes used when instantiating ordered pools on demand */
307 static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
309 struct workqueue_struct *system_wq __read_mostly;
310 EXPORT_SYMBOL(system_wq);
311 struct workqueue_struct *system_highpri_wq __read_mostly;
312 EXPORT_SYMBOL_GPL(system_highpri_wq);
313 struct workqueue_struct *system_long_wq __read_mostly;
314 EXPORT_SYMBOL_GPL(system_long_wq);
315 struct workqueue_struct *system_unbound_wq __read_mostly;
316 EXPORT_SYMBOL_GPL(system_unbound_wq);
317 struct workqueue_struct *system_freezable_wq __read_mostly;
318 EXPORT_SYMBOL_GPL(system_freezable_wq);
319 struct workqueue_struct *system_power_efficient_wq __read_mostly;
320 EXPORT_SYMBOL_GPL(system_power_efficient_wq);
321 struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly;
322 EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq);
324 static int worker_thread(void *__worker);
325 static void copy_workqueue_attrs(struct workqueue_attrs *to,
326 const struct workqueue_attrs *from);
328 #define CREATE_TRACE_POINTS
329 #include <trace/events/workqueue.h>
331 #define assert_rcu_or_pool_mutex() \
332 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
333 lockdep_is_held(&wq_pool_mutex), \
334 "sched RCU or wq_pool_mutex should be held")
336 #define assert_rcu_or_wq_mutex(wq) \
337 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
338 lockdep_is_held(&wq->mutex), \
339 "sched RCU or wq->mutex should be held")
341 #define for_each_cpu_worker_pool(pool, cpu) \
342 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
343 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
347 * for_each_pool - iterate through all worker_pools in the system
348 * @pool: iteration cursor
349 * @pi: integer used for iteration
351 * This must be called either with wq_pool_mutex held or sched RCU read
352 * locked. If the pool needs to be used beyond the locking in effect, the
353 * caller is responsible for guaranteeing that the pool stays online.
355 * The if/else clause exists only for the lockdep assertion and can be
358 #define for_each_pool(pool, pi) \
359 idr_for_each_entry(&worker_pool_idr, pool, pi) \
360 if (({ assert_rcu_or_pool_mutex(); false; })) { } \
364 * for_each_pool_worker - iterate through all workers of a worker_pool
365 * @worker: iteration cursor
366 * @pool: worker_pool to iterate workers of
368 * This must be called with @pool->attach_mutex.
370 * The if/else clause exists only for the lockdep assertion and can be
373 #define for_each_pool_worker(worker, pool) \
374 list_for_each_entry((worker), &(pool)->workers, node) \
375 if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \
379 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
380 * @pwq: iteration cursor
381 * @wq: the target workqueue
383 * This must be called either with wq->mutex held or sched RCU read locked.
384 * If the pwq needs to be used beyond the locking in effect, the caller is
385 * responsible for guaranteeing that the pwq stays online.
387 * The if/else clause exists only for the lockdep assertion and can be
390 #define for_each_pwq(pwq, wq) \
391 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
392 if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
395 #ifdef CONFIG_DEBUG_OBJECTS_WORK
397 static struct debug_obj_descr work_debug_descr;
399 static void *work_debug_hint(void *addr)
401 return ((struct work_struct *) addr)->func;
405 * fixup_init is called when:
406 * - an active object is initialized
408 static int work_fixup_init(void *addr, enum debug_obj_state state)
410 struct work_struct *work = addr;
413 case ODEBUG_STATE_ACTIVE:
414 cancel_work_sync(work);
415 debug_object_init(work, &work_debug_descr);
423 * fixup_activate is called when:
424 * - an active object is activated
425 * - an unknown object is activated (might be a statically initialized object)
427 static int work_fixup_activate(void *addr, enum debug_obj_state state)
429 struct work_struct *work = addr;
433 case ODEBUG_STATE_NOTAVAILABLE:
435 * This is not really a fixup. The work struct was
436 * statically initialized. We just make sure that it
437 * is tracked in the object tracker.
439 if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
440 debug_object_init(work, &work_debug_descr);
441 debug_object_activate(work, &work_debug_descr);
447 case ODEBUG_STATE_ACTIVE:
456 * fixup_free is called when:
457 * - an active object is freed
459 static int work_fixup_free(void *addr, enum debug_obj_state state)
461 struct work_struct *work = addr;
464 case ODEBUG_STATE_ACTIVE:
465 cancel_work_sync(work);
466 debug_object_free(work, &work_debug_descr);
473 static struct debug_obj_descr work_debug_descr = {
474 .name = "work_struct",
475 .debug_hint = work_debug_hint,
476 .fixup_init = work_fixup_init,
477 .fixup_activate = work_fixup_activate,
478 .fixup_free = work_fixup_free,
481 static inline void debug_work_activate(struct work_struct *work)
483 debug_object_activate(work, &work_debug_descr);
486 static inline void debug_work_deactivate(struct work_struct *work)
488 debug_object_deactivate(work, &work_debug_descr);
491 void __init_work(struct work_struct *work, int onstack)
494 debug_object_init_on_stack(work, &work_debug_descr);
496 debug_object_init(work, &work_debug_descr);
498 EXPORT_SYMBOL_GPL(__init_work);
500 void destroy_work_on_stack(struct work_struct *work)
502 debug_object_free(work, &work_debug_descr);
504 EXPORT_SYMBOL_GPL(destroy_work_on_stack);
506 void destroy_delayed_work_on_stack(struct delayed_work *work)
508 destroy_timer_on_stack(&work->timer);
509 debug_object_free(&work->work, &work_debug_descr);
511 EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack);
514 static inline void debug_work_activate(struct work_struct *work) { }
515 static inline void debug_work_deactivate(struct work_struct *work) { }
519 * worker_pool_assign_id - allocate ID and assing it to @pool
520 * @pool: the pool pointer of interest
522 * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
523 * successfully, -errno on failure.
525 static int worker_pool_assign_id(struct worker_pool *pool)
529 lockdep_assert_held(&wq_pool_mutex);
531 ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE,
541 * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
542 * @wq: the target workqueue
545 * This must be called either with pwq_lock held or sched RCU read locked.
546 * If the pwq needs to be used beyond the locking in effect, the caller is
547 * responsible for guaranteeing that the pwq stays online.
549 * Return: The unbound pool_workqueue for @node.
551 static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq,
554 assert_rcu_or_wq_mutex(wq);
555 return rcu_dereference_raw(wq->numa_pwq_tbl[node]);
558 static unsigned int work_color_to_flags(int color)
560 return color << WORK_STRUCT_COLOR_SHIFT;
563 static int get_work_color(struct work_struct *work)
565 return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
566 ((1 << WORK_STRUCT_COLOR_BITS) - 1);
569 static int work_next_color(int color)
571 return (color + 1) % WORK_NR_COLORS;
575 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
576 * contain the pointer to the queued pwq. Once execution starts, the flag
577 * is cleared and the high bits contain OFFQ flags and pool ID.
579 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
580 * and clear_work_data() can be used to set the pwq, pool or clear
581 * work->data. These functions should only be called while the work is
582 * owned - ie. while the PENDING bit is set.
584 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
585 * corresponding to a work. Pool is available once the work has been
586 * queued anywhere after initialization until it is sync canceled. pwq is
587 * available only while the work item is queued.
589 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
590 * canceled. While being canceled, a work item may have its PENDING set
591 * but stay off timer and worklist for arbitrarily long and nobody should
592 * try to steal the PENDING bit.
594 static inline void set_work_data(struct work_struct *work, unsigned long data,
597 WARN_ON_ONCE(!work_pending(work));
598 atomic_long_set(&work->data, data | flags | work_static(work));
601 static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq,
602 unsigned long extra_flags)
604 set_work_data(work, (unsigned long)pwq,
605 WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags);
608 static void set_work_pool_and_keep_pending(struct work_struct *work,
611 set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
612 WORK_STRUCT_PENDING);
615 static void set_work_pool_and_clear_pending(struct work_struct *work,
619 * The following wmb is paired with the implied mb in
620 * test_and_set_bit(PENDING) and ensures all updates to @work made
621 * here are visible to and precede any updates by the next PENDING
625 set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
628 static void clear_work_data(struct work_struct *work)
630 smp_wmb(); /* see set_work_pool_and_clear_pending() */
631 set_work_data(work, WORK_STRUCT_NO_POOL, 0);
634 static struct pool_workqueue *get_work_pwq(struct work_struct *work)
636 unsigned long data = atomic_long_read(&work->data);
638 if (data & WORK_STRUCT_PWQ)
639 return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
645 * get_work_pool - return the worker_pool a given work was associated with
646 * @work: the work item of interest
648 * Pools are created and destroyed under wq_pool_mutex, and allows read
649 * access under sched-RCU read lock. As such, this function should be
650 * called under wq_pool_mutex or with preemption disabled.
652 * All fields of the returned pool are accessible as long as the above
653 * mentioned locking is in effect. If the returned pool needs to be used
654 * beyond the critical section, the caller is responsible for ensuring the
655 * returned pool is and stays online.
657 * Return: The worker_pool @work was last associated with. %NULL if none.
659 static struct worker_pool *get_work_pool(struct work_struct *work)
661 unsigned long data = atomic_long_read(&work->data);
664 assert_rcu_or_pool_mutex();
666 if (data & WORK_STRUCT_PWQ)
667 return ((struct pool_workqueue *)
668 (data & WORK_STRUCT_WQ_DATA_MASK))->pool;
670 pool_id = data >> WORK_OFFQ_POOL_SHIFT;
671 if (pool_id == WORK_OFFQ_POOL_NONE)
674 return idr_find(&worker_pool_idr, pool_id);
678 * get_work_pool_id - return the worker pool ID a given work is associated with
679 * @work: the work item of interest
681 * Return: The worker_pool ID @work was last associated with.
682 * %WORK_OFFQ_POOL_NONE if none.
684 static int get_work_pool_id(struct work_struct *work)
686 unsigned long data = atomic_long_read(&work->data);
688 if (data & WORK_STRUCT_PWQ)
689 return ((struct pool_workqueue *)
690 (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
692 return data >> WORK_OFFQ_POOL_SHIFT;
695 static void mark_work_canceling(struct work_struct *work)
697 unsigned long pool_id = get_work_pool_id(work);
699 pool_id <<= WORK_OFFQ_POOL_SHIFT;
700 set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
703 static bool work_is_canceling(struct work_struct *work)
705 unsigned long data = atomic_long_read(&work->data);
707 return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
711 * Policy functions. These define the policies on how the global worker
712 * pools are managed. Unless noted otherwise, these functions assume that
713 * they're being called with pool->lock held.
716 static bool __need_more_worker(struct worker_pool *pool)
718 return !atomic_read(&pool->nr_running);
722 * Need to wake up a worker? Called from anything but currently
725 * Note that, because unbound workers never contribute to nr_running, this
726 * function will always return %true for unbound pools as long as the
727 * worklist isn't empty.
729 static bool need_more_worker(struct worker_pool *pool)
731 return !list_empty(&pool->worklist) && __need_more_worker(pool);
734 /* Can I start working? Called from busy but !running workers. */
735 static bool may_start_working(struct worker_pool *pool)
737 return pool->nr_idle;
740 /* Do I need to keep working? Called from currently running workers. */
741 static bool keep_working(struct worker_pool *pool)
743 return !list_empty(&pool->worklist) &&
744 atomic_read(&pool->nr_running) <= 1;
747 /* Do we need a new worker? Called from manager. */
748 static bool need_to_create_worker(struct worker_pool *pool)
750 return need_more_worker(pool) && !may_start_working(pool);
753 /* Do we have too many workers and should some go away? */
754 static bool too_many_workers(struct worker_pool *pool)
756 bool managing = mutex_is_locked(&pool->manager_arb);
757 int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
758 int nr_busy = pool->nr_workers - nr_idle;
760 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
767 /* Return the first idle worker. Safe with preemption disabled */
768 static struct worker *first_idle_worker(struct worker_pool *pool)
770 if (unlikely(list_empty(&pool->idle_list)))
773 return list_first_entry(&pool->idle_list, struct worker, entry);
777 * wake_up_worker - wake up an idle worker
778 * @pool: worker pool to wake worker from
780 * Wake up the first idle worker of @pool.
783 * spin_lock_irq(pool->lock).
785 static void wake_up_worker(struct worker_pool *pool)
787 struct worker *worker = first_idle_worker(pool);
790 wake_up_process(worker->task);
794 * wq_worker_waking_up - a worker is waking up
795 * @task: task waking up
796 * @cpu: CPU @task is waking up to
798 * This function is called during try_to_wake_up() when a worker is
802 * spin_lock_irq(rq->lock)
804 void wq_worker_waking_up(struct task_struct *task, int cpu)
806 struct worker *worker = kthread_data(task);
808 if (!(worker->flags & WORKER_NOT_RUNNING)) {
809 WARN_ON_ONCE(worker->pool->cpu != cpu);
810 atomic_inc(&worker->pool->nr_running);
815 * wq_worker_sleeping - a worker is going to sleep
816 * @task: task going to sleep
817 * @cpu: CPU in question, must be the current CPU number
819 * This function is called during schedule() when a busy worker is
820 * going to sleep. Worker on the same cpu can be woken up by
821 * returning pointer to its task.
824 * spin_lock_irq(rq->lock)
827 * Worker task on @cpu to wake up, %NULL if none.
829 struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu)
831 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
832 struct worker_pool *pool;
835 * Rescuers, which may not have all the fields set up like normal
836 * workers, also reach here, let's not access anything before
837 * checking NOT_RUNNING.
839 if (worker->flags & WORKER_NOT_RUNNING)
844 /* this can only happen on the local cpu */
845 if (WARN_ON_ONCE(cpu != raw_smp_processor_id() || pool->cpu != cpu))
849 * The counterpart of the following dec_and_test, implied mb,
850 * worklist not empty test sequence is in insert_work().
851 * Please read comment there.
853 * NOT_RUNNING is clear. This means that we're bound to and
854 * running on the local cpu w/ rq lock held and preemption
855 * disabled, which in turn means that none else could be
856 * manipulating idle_list, so dereferencing idle_list without pool
859 if (atomic_dec_and_test(&pool->nr_running) &&
860 !list_empty(&pool->worklist))
861 to_wakeup = first_idle_worker(pool);
862 return to_wakeup ? to_wakeup->task : NULL;
866 * worker_set_flags - set worker flags and adjust nr_running accordingly
868 * @flags: flags to set
870 * Set @flags in @worker->flags and adjust nr_running accordingly.
873 * spin_lock_irq(pool->lock)
875 static inline void worker_set_flags(struct worker *worker, unsigned int flags)
877 struct worker_pool *pool = worker->pool;
879 WARN_ON_ONCE(worker->task != current);
881 /* If transitioning into NOT_RUNNING, adjust nr_running. */
882 if ((flags & WORKER_NOT_RUNNING) &&
883 !(worker->flags & WORKER_NOT_RUNNING)) {
884 atomic_dec(&pool->nr_running);
887 worker->flags |= flags;
891 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
893 * @flags: flags to clear
895 * Clear @flags in @worker->flags and adjust nr_running accordingly.
898 * spin_lock_irq(pool->lock)
900 static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
902 struct worker_pool *pool = worker->pool;
903 unsigned int oflags = worker->flags;
905 WARN_ON_ONCE(worker->task != current);
907 worker->flags &= ~flags;
910 * If transitioning out of NOT_RUNNING, increment nr_running. Note
911 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
912 * of multiple flags, not a single flag.
914 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
915 if (!(worker->flags & WORKER_NOT_RUNNING))
916 atomic_inc(&pool->nr_running);
920 * find_worker_executing_work - find worker which is executing a work
921 * @pool: pool of interest
922 * @work: work to find worker for
924 * Find a worker which is executing @work on @pool by searching
925 * @pool->busy_hash which is keyed by the address of @work. For a worker
926 * to match, its current execution should match the address of @work and
927 * its work function. This is to avoid unwanted dependency between
928 * unrelated work executions through a work item being recycled while still
931 * This is a bit tricky. A work item may be freed once its execution
932 * starts and nothing prevents the freed area from being recycled for
933 * another work item. If the same work item address ends up being reused
934 * before the original execution finishes, workqueue will identify the
935 * recycled work item as currently executing and make it wait until the
936 * current execution finishes, introducing an unwanted dependency.
938 * This function checks the work item address and work function to avoid
939 * false positives. Note that this isn't complete as one may construct a
940 * work function which can introduce dependency onto itself through a
941 * recycled work item. Well, if somebody wants to shoot oneself in the
942 * foot that badly, there's only so much we can do, and if such deadlock
943 * actually occurs, it should be easy to locate the culprit work function.
946 * spin_lock_irq(pool->lock).
949 * Pointer to worker which is executing @work if found, %NULL
952 static struct worker *find_worker_executing_work(struct worker_pool *pool,
953 struct work_struct *work)
955 struct worker *worker;
957 hash_for_each_possible(pool->busy_hash, worker, hentry,
959 if (worker->current_work == work &&
960 worker->current_func == work->func)
967 * move_linked_works - move linked works to a list
968 * @work: start of series of works to be scheduled
969 * @head: target list to append @work to
970 * @nextp: out paramter for nested worklist walking
972 * Schedule linked works starting from @work to @head. Work series to
973 * be scheduled starts at @work and includes any consecutive work with
974 * WORK_STRUCT_LINKED set in its predecessor.
976 * If @nextp is not NULL, it's updated to point to the next work of
977 * the last scheduled work. This allows move_linked_works() to be
978 * nested inside outer list_for_each_entry_safe().
981 * spin_lock_irq(pool->lock).
983 static void move_linked_works(struct work_struct *work, struct list_head *head,
984 struct work_struct **nextp)
986 struct work_struct *n;
989 * Linked worklist will always end before the end of the list,
990 * use NULL for list head.
992 list_for_each_entry_safe_from(work, n, NULL, entry) {
993 list_move_tail(&work->entry, head);
994 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
999 * If we're already inside safe list traversal and have moved
1000 * multiple works to the scheduled queue, the next position
1001 * needs to be updated.
1008 * get_pwq - get an extra reference on the specified pool_workqueue
1009 * @pwq: pool_workqueue to get
1011 * Obtain an extra reference on @pwq. The caller should guarantee that
1012 * @pwq has positive refcnt and be holding the matching pool->lock.
1014 static void get_pwq(struct pool_workqueue *pwq)
1016 lockdep_assert_held(&pwq->pool->lock);
1017 WARN_ON_ONCE(pwq->refcnt <= 0);
1022 * put_pwq - put a pool_workqueue reference
1023 * @pwq: pool_workqueue to put
1025 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1026 * destruction. The caller should be holding the matching pool->lock.
1028 static void put_pwq(struct pool_workqueue *pwq)
1030 lockdep_assert_held(&pwq->pool->lock);
1031 if (likely(--pwq->refcnt))
1033 if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND)))
1036 * @pwq can't be released under pool->lock, bounce to
1037 * pwq_unbound_release_workfn(). This never recurses on the same
1038 * pool->lock as this path is taken only for unbound workqueues and
1039 * the release work item is scheduled on a per-cpu workqueue. To
1040 * avoid lockdep warning, unbound pool->locks are given lockdep
1041 * subclass of 1 in get_unbound_pool().
1043 schedule_work(&pwq->unbound_release_work);
1047 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1048 * @pwq: pool_workqueue to put (can be %NULL)
1050 * put_pwq() with locking. This function also allows %NULL @pwq.
1052 static void put_pwq_unlocked(struct pool_workqueue *pwq)
1056 * As both pwqs and pools are sched-RCU protected, the
1057 * following lock operations are safe.
1059 spin_lock_irq(&pwq->pool->lock);
1061 spin_unlock_irq(&pwq->pool->lock);
1065 static void pwq_activate_delayed_work(struct work_struct *work)
1067 struct pool_workqueue *pwq = get_work_pwq(work);
1069 trace_workqueue_activate_work(work);
1070 move_linked_works(work, &pwq->pool->worklist, NULL);
1071 __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
1075 static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
1077 struct work_struct *work = list_first_entry(&pwq->delayed_works,
1078 struct work_struct, entry);
1080 pwq_activate_delayed_work(work);
1084 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1085 * @pwq: pwq of interest
1086 * @color: color of work which left the queue
1088 * A work either has completed or is removed from pending queue,
1089 * decrement nr_in_flight of its pwq and handle workqueue flushing.
1092 * spin_lock_irq(pool->lock).
1094 static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
1096 /* uncolored work items don't participate in flushing or nr_active */
1097 if (color == WORK_NO_COLOR)
1100 pwq->nr_in_flight[color]--;
1103 if (!list_empty(&pwq->delayed_works)) {
1104 /* one down, submit a delayed one */
1105 if (pwq->nr_active < pwq->max_active)
1106 pwq_activate_first_delayed(pwq);
1109 /* is flush in progress and are we at the flushing tip? */
1110 if (likely(pwq->flush_color != color))
1113 /* are there still in-flight works? */
1114 if (pwq->nr_in_flight[color])
1117 /* this pwq is done, clear flush_color */
1118 pwq->flush_color = -1;
1121 * If this was the last pwq, wake up the first flusher. It
1122 * will handle the rest.
1124 if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
1125 complete(&pwq->wq->first_flusher->done);
1131 * try_to_grab_pending - steal work item from worklist and disable irq
1132 * @work: work item to steal
1133 * @is_dwork: @work is a delayed_work
1134 * @flags: place to store irq state
1136 * Try to grab PENDING bit of @work. This function can handle @work in any
1137 * stable state - idle, on timer or on worklist.
1140 * 1 if @work was pending and we successfully stole PENDING
1141 * 0 if @work was idle and we claimed PENDING
1142 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1143 * -ENOENT if someone else is canceling @work, this state may persist
1144 * for arbitrarily long
1147 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1148 * interrupted while holding PENDING and @work off queue, irq must be
1149 * disabled on entry. This, combined with delayed_work->timer being
1150 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1152 * On successful return, >= 0, irq is disabled and the caller is
1153 * responsible for releasing it using local_irq_restore(*@flags).
1155 * This function is safe to call from any context including IRQ handler.
1157 static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
1158 unsigned long *flags)
1160 struct worker_pool *pool;
1161 struct pool_workqueue *pwq;
1163 local_irq_save(*flags);
1165 /* try to steal the timer if it exists */
1167 struct delayed_work *dwork = to_delayed_work(work);
1170 * dwork->timer is irqsafe. If del_timer() fails, it's
1171 * guaranteed that the timer is not queued anywhere and not
1172 * running on the local CPU.
1174 if (likely(del_timer(&dwork->timer)))
1178 /* try to claim PENDING the normal way */
1179 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
1183 * The queueing is in progress, or it is already queued. Try to
1184 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1186 pool = get_work_pool(work);
1190 spin_lock(&pool->lock);
1192 * work->data is guaranteed to point to pwq only while the work
1193 * item is queued on pwq->wq, and both updating work->data to point
1194 * to pwq on queueing and to pool on dequeueing are done under
1195 * pwq->pool->lock. This in turn guarantees that, if work->data
1196 * points to pwq which is associated with a locked pool, the work
1197 * item is currently queued on that pool.
1199 pwq = get_work_pwq(work);
1200 if (pwq && pwq->pool == pool) {
1201 debug_work_deactivate(work);
1204 * A delayed work item cannot be grabbed directly because
1205 * it might have linked NO_COLOR work items which, if left
1206 * on the delayed_list, will confuse pwq->nr_active
1207 * management later on and cause stall. Make sure the work
1208 * item is activated before grabbing.
1210 if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
1211 pwq_activate_delayed_work(work);
1213 list_del_init(&work->entry);
1214 pwq_dec_nr_in_flight(pwq, get_work_color(work));
1216 /* work->data points to pwq iff queued, point to pool */
1217 set_work_pool_and_keep_pending(work, pool->id);
1219 spin_unlock(&pool->lock);
1222 spin_unlock(&pool->lock);
1224 local_irq_restore(*flags);
1225 if (work_is_canceling(work))
1232 * insert_work - insert a work into a pool
1233 * @pwq: pwq @work belongs to
1234 * @work: work to insert
1235 * @head: insertion point
1236 * @extra_flags: extra WORK_STRUCT_* flags to set
1238 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1239 * work_struct flags.
1242 * spin_lock_irq(pool->lock).
1244 static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
1245 struct list_head *head, unsigned int extra_flags)
1247 struct worker_pool *pool = pwq->pool;
1249 /* we own @work, set data and link */
1250 set_work_pwq(work, pwq, extra_flags);
1251 list_add_tail(&work->entry, head);
1255 * Ensure either wq_worker_sleeping() sees the above
1256 * list_add_tail() or we see zero nr_running to avoid workers lying
1257 * around lazily while there are works to be processed.
1261 if (__need_more_worker(pool))
1262 wake_up_worker(pool);
1266 * Test whether @work is being queued from another work executing on the
1269 static bool is_chained_work(struct workqueue_struct *wq)
1271 struct worker *worker;
1273 worker = current_wq_worker();
1275 * Return %true iff I'm a worker execuing a work item on @wq. If
1276 * I'm @worker, it's safe to dereference it without locking.
1278 return worker && worker->current_pwq->wq == wq;
1281 static void __queue_work(int cpu, struct workqueue_struct *wq,
1282 struct work_struct *work)
1284 struct pool_workqueue *pwq;
1285 struct worker_pool *last_pool;
1286 struct list_head *worklist;
1287 unsigned int work_flags;
1288 unsigned int req_cpu = cpu;
1291 * While a work item is PENDING && off queue, a task trying to
1292 * steal the PENDING will busy-loop waiting for it to either get
1293 * queued or lose PENDING. Grabbing PENDING and queueing should
1294 * happen with IRQ disabled.
1296 WARN_ON_ONCE(!irqs_disabled());
1298 debug_work_activate(work);
1300 /* if draining, only works from the same workqueue are allowed */
1301 if (unlikely(wq->flags & __WQ_DRAINING) &&
1302 WARN_ON_ONCE(!is_chained_work(wq)))
1305 if (req_cpu == WORK_CPU_UNBOUND)
1306 cpu = raw_smp_processor_id();
1308 /* pwq which will be used unless @work is executing elsewhere */
1309 if (!(wq->flags & WQ_UNBOUND))
1310 pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
1312 pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
1315 * If @work was previously on a different pool, it might still be
1316 * running there, in which case the work needs to be queued on that
1317 * pool to guarantee non-reentrancy.
1319 last_pool = get_work_pool(work);
1320 if (last_pool && last_pool != pwq->pool) {
1321 struct worker *worker;
1323 spin_lock(&last_pool->lock);
1325 worker = find_worker_executing_work(last_pool, work);
1327 if (worker && worker->current_pwq->wq == wq) {
1328 pwq = worker->current_pwq;
1330 /* meh... not running there, queue here */
1331 spin_unlock(&last_pool->lock);
1332 spin_lock(&pwq->pool->lock);
1335 spin_lock(&pwq->pool->lock);
1339 * pwq is determined and locked. For unbound pools, we could have
1340 * raced with pwq release and it could already be dead. If its
1341 * refcnt is zero, repeat pwq selection. Note that pwqs never die
1342 * without another pwq replacing it in the numa_pwq_tbl or while
1343 * work items are executing on it, so the retrying is guaranteed to
1344 * make forward-progress.
1346 if (unlikely(!pwq->refcnt)) {
1347 if (wq->flags & WQ_UNBOUND) {
1348 spin_unlock(&pwq->pool->lock);
1353 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1357 /* pwq determined, queue */
1358 trace_workqueue_queue_work(req_cpu, pwq, work);
1360 if (WARN_ON(!list_empty(&work->entry))) {
1361 spin_unlock(&pwq->pool->lock);
1365 pwq->nr_in_flight[pwq->work_color]++;
1366 work_flags = work_color_to_flags(pwq->work_color);
1368 if (likely(pwq->nr_active < pwq->max_active)) {
1369 trace_workqueue_activate_work(work);
1371 worklist = &pwq->pool->worklist;
1373 work_flags |= WORK_STRUCT_DELAYED;
1374 worklist = &pwq->delayed_works;
1377 insert_work(pwq, work, worklist, work_flags);
1379 spin_unlock(&pwq->pool->lock);
1383 * queue_work_on - queue work on specific cpu
1384 * @cpu: CPU number to execute work on
1385 * @wq: workqueue to use
1386 * @work: work to queue
1388 * We queue the work to a specific CPU, the caller must ensure it
1391 * Return: %false if @work was already on a queue, %true otherwise.
1393 bool queue_work_on(int cpu, struct workqueue_struct *wq,
1394 struct work_struct *work)
1397 unsigned long flags;
1399 local_irq_save(flags);
1401 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1402 __queue_work(cpu, wq, work);
1406 local_irq_restore(flags);
1409 EXPORT_SYMBOL(queue_work_on);
1411 void delayed_work_timer_fn(unsigned long __data)
1413 struct delayed_work *dwork = (struct delayed_work *)__data;
1415 /* should have been called from irqsafe timer with irq already off */
1416 __queue_work(dwork->cpu, dwork->wq, &dwork->work);
1418 EXPORT_SYMBOL(delayed_work_timer_fn);
1420 static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
1421 struct delayed_work *dwork, unsigned long delay)
1423 struct timer_list *timer = &dwork->timer;
1424 struct work_struct *work = &dwork->work;
1426 WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
1427 timer->data != (unsigned long)dwork);
1428 WARN_ON_ONCE(timer_pending(timer));
1429 WARN_ON_ONCE(!list_empty(&work->entry));
1432 * If @delay is 0, queue @dwork->work immediately. This is for
1433 * both optimization and correctness. The earliest @timer can
1434 * expire is on the closest next tick and delayed_work users depend
1435 * on that there's no such delay when @delay is 0.
1438 __queue_work(cpu, wq, &dwork->work);
1442 timer_stats_timer_set_start_info(&dwork->timer);
1446 timer->expires = jiffies + delay;
1448 if (unlikely(cpu != WORK_CPU_UNBOUND))
1449 add_timer_on(timer, cpu);
1455 * queue_delayed_work_on - queue work on specific CPU after delay
1456 * @cpu: CPU number to execute work on
1457 * @wq: workqueue to use
1458 * @dwork: work to queue
1459 * @delay: number of jiffies to wait before queueing
1461 * Return: %false if @work was already on a queue, %true otherwise. If
1462 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1465 bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1466 struct delayed_work *dwork, unsigned long delay)
1468 struct work_struct *work = &dwork->work;
1470 unsigned long flags;
1472 /* read the comment in __queue_work() */
1473 local_irq_save(flags);
1475 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1476 __queue_delayed_work(cpu, wq, dwork, delay);
1480 local_irq_restore(flags);
1483 EXPORT_SYMBOL(queue_delayed_work_on);
1486 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1487 * @cpu: CPU number to execute work on
1488 * @wq: workqueue to use
1489 * @dwork: work to queue
1490 * @delay: number of jiffies to wait before queueing
1492 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1493 * modify @dwork's timer so that it expires after @delay. If @delay is
1494 * zero, @work is guaranteed to be scheduled immediately regardless of its
1497 * Return: %false if @dwork was idle and queued, %true if @dwork was
1498 * pending and its timer was modified.
1500 * This function is safe to call from any context including IRQ handler.
1501 * See try_to_grab_pending() for details.
1503 bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
1504 struct delayed_work *dwork, unsigned long delay)
1506 unsigned long flags;
1510 ret = try_to_grab_pending(&dwork->work, true, &flags);
1511 } while (unlikely(ret == -EAGAIN));
1513 if (likely(ret >= 0)) {
1514 __queue_delayed_work(cpu, wq, dwork, delay);
1515 local_irq_restore(flags);
1518 /* -ENOENT from try_to_grab_pending() becomes %true */
1521 EXPORT_SYMBOL_GPL(mod_delayed_work_on);
1524 * worker_enter_idle - enter idle state
1525 * @worker: worker which is entering idle state
1527 * @worker is entering idle state. Update stats and idle timer if
1531 * spin_lock_irq(pool->lock).
1533 static void worker_enter_idle(struct worker *worker)
1535 struct worker_pool *pool = worker->pool;
1537 if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
1538 WARN_ON_ONCE(!list_empty(&worker->entry) &&
1539 (worker->hentry.next || worker->hentry.pprev)))
1542 /* can't use worker_set_flags(), also called from create_worker() */
1543 worker->flags |= WORKER_IDLE;
1545 worker->last_active = jiffies;
1547 /* idle_list is LIFO */
1548 list_add(&worker->entry, &pool->idle_list);
1550 if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
1551 mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
1554 * Sanity check nr_running. Because wq_unbind_fn() releases
1555 * pool->lock between setting %WORKER_UNBOUND and zapping
1556 * nr_running, the warning may trigger spuriously. Check iff
1557 * unbind is not in progress.
1559 WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
1560 pool->nr_workers == pool->nr_idle &&
1561 atomic_read(&pool->nr_running));
1565 * worker_leave_idle - leave idle state
1566 * @worker: worker which is leaving idle state
1568 * @worker is leaving idle state. Update stats.
1571 * spin_lock_irq(pool->lock).
1573 static void worker_leave_idle(struct worker *worker)
1575 struct worker_pool *pool = worker->pool;
1577 if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
1579 worker_clr_flags(worker, WORKER_IDLE);
1581 list_del_init(&worker->entry);
1584 static struct worker *alloc_worker(int node)
1586 struct worker *worker;
1588 worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node);
1590 INIT_LIST_HEAD(&worker->entry);
1591 INIT_LIST_HEAD(&worker->scheduled);
1592 INIT_LIST_HEAD(&worker->node);
1593 /* on creation a worker is in !idle && prep state */
1594 worker->flags = WORKER_PREP;
1600 * worker_attach_to_pool() - attach a worker to a pool
1601 * @worker: worker to be attached
1602 * @pool: the target pool
1604 * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
1605 * cpu-binding of @worker are kept coordinated with the pool across
1608 static void worker_attach_to_pool(struct worker *worker,
1609 struct worker_pool *pool)
1611 mutex_lock(&pool->attach_mutex);
1614 * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1615 * online CPUs. It'll be re-applied when any of the CPUs come up.
1617 set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
1620 * The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
1621 * stable across this function. See the comments above the
1622 * flag definition for details.
1624 if (pool->flags & POOL_DISASSOCIATED)
1625 worker->flags |= WORKER_UNBOUND;
1627 list_add_tail(&worker->node, &pool->workers);
1629 mutex_unlock(&pool->attach_mutex);
1633 * worker_detach_from_pool() - detach a worker from its pool
1634 * @worker: worker which is attached to its pool
1635 * @pool: the pool @worker is attached to
1637 * Undo the attaching which had been done in worker_attach_to_pool(). The
1638 * caller worker shouldn't access to the pool after detached except it has
1639 * other reference to the pool.
1641 static void worker_detach_from_pool(struct worker *worker,
1642 struct worker_pool *pool)
1644 struct completion *detach_completion = NULL;
1646 mutex_lock(&pool->attach_mutex);
1647 list_del(&worker->node);
1648 if (list_empty(&pool->workers))
1649 detach_completion = pool->detach_completion;
1650 mutex_unlock(&pool->attach_mutex);
1652 /* clear leftover flags without pool->lock after it is detached */
1653 worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND);
1655 if (detach_completion)
1656 complete(detach_completion);
1660 * create_worker - create a new workqueue worker
1661 * @pool: pool the new worker will belong to
1663 * Create and start a new worker which is attached to @pool.
1666 * Might sleep. Does GFP_KERNEL allocations.
1669 * Pointer to the newly created worker.
1671 static struct worker *create_worker(struct worker_pool *pool)
1673 struct worker *worker = NULL;
1677 /* ID is needed to determine kthread name */
1678 id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);
1682 worker = alloc_worker(pool->node);
1686 worker->pool = pool;
1690 snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
1691 pool->attrs->nice < 0 ? "H" : "");
1693 snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
1695 worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
1696 "kworker/%s", id_buf);
1697 if (IS_ERR(worker->task))
1700 set_user_nice(worker->task, pool->attrs->nice);
1702 /* prevent userland from meddling with cpumask of workqueue workers */
1703 worker->task->flags |= PF_NO_SETAFFINITY;
1705 /* successful, attach the worker to the pool */
1706 worker_attach_to_pool(worker, pool);
1708 /* start the newly created worker */
1709 spin_lock_irq(&pool->lock);
1710 worker->pool->nr_workers++;
1711 worker_enter_idle(worker);
1712 wake_up_process(worker->task);
1713 spin_unlock_irq(&pool->lock);
1719 ida_simple_remove(&pool->worker_ida, id);
1725 * destroy_worker - destroy a workqueue worker
1726 * @worker: worker to be destroyed
1728 * Destroy @worker and adjust @pool stats accordingly. The worker should
1732 * spin_lock_irq(pool->lock).
1734 static void destroy_worker(struct worker *worker)
1736 struct worker_pool *pool = worker->pool;
1738 lockdep_assert_held(&pool->lock);
1740 /* sanity check frenzy */
1741 if (WARN_ON(worker->current_work) ||
1742 WARN_ON(!list_empty(&worker->scheduled)) ||
1743 WARN_ON(!(worker->flags & WORKER_IDLE)))
1749 list_del_init(&worker->entry);
1750 worker->flags |= WORKER_DIE;
1751 wake_up_process(worker->task);
1754 static void idle_worker_timeout(unsigned long __pool)
1756 struct worker_pool *pool = (void *)__pool;
1758 spin_lock_irq(&pool->lock);
1760 while (too_many_workers(pool)) {
1761 struct worker *worker;
1762 unsigned long expires;
1764 /* idle_list is kept in LIFO order, check the last one */
1765 worker = list_entry(pool->idle_list.prev, struct worker, entry);
1766 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1768 if (time_before(jiffies, expires)) {
1769 mod_timer(&pool->idle_timer, expires);
1773 destroy_worker(worker);
1776 spin_unlock_irq(&pool->lock);
1779 static void send_mayday(struct work_struct *work)
1781 struct pool_workqueue *pwq = get_work_pwq(work);
1782 struct workqueue_struct *wq = pwq->wq;
1784 lockdep_assert_held(&wq_mayday_lock);
1789 /* mayday mayday mayday */
1790 if (list_empty(&pwq->mayday_node)) {
1792 * If @pwq is for an unbound wq, its base ref may be put at
1793 * any time due to an attribute change. Pin @pwq until the
1794 * rescuer is done with it.
1797 list_add_tail(&pwq->mayday_node, &wq->maydays);
1798 wake_up_process(wq->rescuer->task);
1802 static void pool_mayday_timeout(unsigned long __pool)
1804 struct worker_pool *pool = (void *)__pool;
1805 struct work_struct *work;
1807 spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */
1808 spin_lock(&pool->lock);
1810 if (need_to_create_worker(pool)) {
1812 * We've been trying to create a new worker but
1813 * haven't been successful. We might be hitting an
1814 * allocation deadlock. Send distress signals to
1817 list_for_each_entry(work, &pool->worklist, entry)
1821 spin_unlock(&pool->lock);
1822 spin_unlock_irq(&wq_mayday_lock);
1824 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
1828 * maybe_create_worker - create a new worker if necessary
1829 * @pool: pool to create a new worker for
1831 * Create a new worker for @pool if necessary. @pool is guaranteed to
1832 * have at least one idle worker on return from this function. If
1833 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1834 * sent to all rescuers with works scheduled on @pool to resolve
1835 * possible allocation deadlock.
1837 * On return, need_to_create_worker() is guaranteed to be %false and
1838 * may_start_working() %true.
1841 * spin_lock_irq(pool->lock) which may be released and regrabbed
1842 * multiple times. Does GFP_KERNEL allocations. Called only from
1846 * %false if no action was taken and pool->lock stayed locked, %true
1849 static bool maybe_create_worker(struct worker_pool *pool)
1850 __releases(&pool->lock)
1851 __acquires(&pool->lock)
1853 if (!need_to_create_worker(pool))
1856 spin_unlock_irq(&pool->lock);
1858 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1859 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
1862 if (create_worker(pool) || !need_to_create_worker(pool))
1865 schedule_timeout_interruptible(CREATE_COOLDOWN);
1867 if (!need_to_create_worker(pool))
1871 del_timer_sync(&pool->mayday_timer);
1872 spin_lock_irq(&pool->lock);
1874 * This is necessary even after a new worker was just successfully
1875 * created as @pool->lock was dropped and the new worker might have
1876 * already become busy.
1878 if (need_to_create_worker(pool))
1884 * manage_workers - manage worker pool
1887 * Assume the manager role and manage the worker pool @worker belongs
1888 * to. At any given time, there can be only zero or one manager per
1889 * pool. The exclusion is handled automatically by this function.
1891 * The caller can safely start processing works on false return. On
1892 * true return, it's guaranteed that need_to_create_worker() is false
1893 * and may_start_working() is true.
1896 * spin_lock_irq(pool->lock) which may be released and regrabbed
1897 * multiple times. Does GFP_KERNEL allocations.
1900 * %false if the pool don't need management and the caller can safely start
1901 * processing works, %true indicates that the function released pool->lock
1902 * and reacquired it to perform some management function and that the
1903 * conditions that the caller verified while holding the lock before
1904 * calling the function might no longer be true.
1906 static bool manage_workers(struct worker *worker)
1908 struct worker_pool *pool = worker->pool;
1912 * Anyone who successfully grabs manager_arb wins the arbitration
1913 * and becomes the manager. mutex_trylock() on pool->manager_arb
1914 * failure while holding pool->lock reliably indicates that someone
1915 * else is managing the pool and the worker which failed trylock
1916 * can proceed to executing work items. This means that anyone
1917 * grabbing manager_arb is responsible for actually performing
1918 * manager duties. If manager_arb is grabbed and released without
1919 * actual management, the pool may stall indefinitely.
1921 if (!mutex_trylock(&pool->manager_arb))
1924 ret |= maybe_create_worker(pool);
1926 mutex_unlock(&pool->manager_arb);
1931 * process_one_work - process single work
1933 * @work: work to process
1935 * Process @work. This function contains all the logics necessary to
1936 * process a single work including synchronization against and
1937 * interaction with other workers on the same cpu, queueing and
1938 * flushing. As long as context requirement is met, any worker can
1939 * call this function to process a work.
1942 * spin_lock_irq(pool->lock) which is released and regrabbed.
1944 static void process_one_work(struct worker *worker, struct work_struct *work)
1945 __releases(&pool->lock)
1946 __acquires(&pool->lock)
1948 struct pool_workqueue *pwq = get_work_pwq(work);
1949 struct worker_pool *pool = worker->pool;
1950 bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
1952 struct worker *collision;
1953 #ifdef CONFIG_LOCKDEP
1955 * It is permissible to free the struct work_struct from
1956 * inside the function that is called from it, this we need to
1957 * take into account for lockdep too. To avoid bogus "held
1958 * lock freed" warnings as well as problems when looking into
1959 * work->lockdep_map, make a copy and use that here.
1961 struct lockdep_map lockdep_map;
1963 lockdep_copy_map(&lockdep_map, &work->lockdep_map);
1965 /* ensure we're on the correct CPU */
1966 WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
1967 raw_smp_processor_id() != pool->cpu);
1970 * A single work shouldn't be executed concurrently by
1971 * multiple workers on a single cpu. Check whether anyone is
1972 * already processing the work. If so, defer the work to the
1973 * currently executing one.
1975 collision = find_worker_executing_work(pool, work);
1976 if (unlikely(collision)) {
1977 move_linked_works(work, &collision->scheduled, NULL);
1981 /* claim and dequeue */
1982 debug_work_deactivate(work);
1983 hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
1984 worker->current_work = work;
1985 worker->current_func = work->func;
1986 worker->current_pwq = pwq;
1987 work_color = get_work_color(work);
1989 list_del_init(&work->entry);
1992 * CPU intensive works don't participate in concurrency management.
1993 * They're the scheduler's responsibility. This takes @worker out
1994 * of concurrency management and the next code block will chain
1995 * execution of the pending work items.
1997 if (unlikely(cpu_intensive))
1998 worker_set_flags(worker, WORKER_CPU_INTENSIVE);
2001 * Wake up another worker if necessary. The condition is always
2002 * false for normal per-cpu workers since nr_running would always
2003 * be >= 1 at this point. This is used to chain execution of the
2004 * pending work items for WORKER_NOT_RUNNING workers such as the
2005 * UNBOUND and CPU_INTENSIVE ones.
2007 if (need_more_worker(pool))
2008 wake_up_worker(pool);
2011 * Record the last pool and clear PENDING which should be the last
2012 * update to @work. Also, do this inside @pool->lock so that
2013 * PENDING and queued state changes happen together while IRQ is
2016 set_work_pool_and_clear_pending(work, pool->id);
2018 spin_unlock_irq(&pool->lock);
2020 lock_map_acquire_read(&pwq->wq->lockdep_map);
2021 lock_map_acquire(&lockdep_map);
2022 trace_workqueue_execute_start(work);
2023 worker->current_func(work);
2025 * While we must be careful to not use "work" after this, the trace
2026 * point will only record its address.
2028 trace_workqueue_execute_end(work);
2029 lock_map_release(&lockdep_map);
2030 lock_map_release(&pwq->wq->lockdep_map);
2032 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
2033 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2034 " last function: %pf\n",
2035 current->comm, preempt_count(), task_pid_nr(current),
2036 worker->current_func);
2037 debug_show_held_locks(current);
2042 * The following prevents a kworker from hogging CPU on !PREEMPT
2043 * kernels, where a requeueing work item waiting for something to
2044 * happen could deadlock with stop_machine as such work item could
2045 * indefinitely requeue itself while all other CPUs are trapped in
2050 spin_lock_irq(&pool->lock);
2052 /* clear cpu intensive status */
2053 if (unlikely(cpu_intensive))
2054 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
2056 /* we're done with it, release */
2057 hash_del(&worker->hentry);
2058 worker->current_work = NULL;
2059 worker->current_func = NULL;
2060 worker->current_pwq = NULL;
2061 worker->desc_valid = false;
2062 pwq_dec_nr_in_flight(pwq, work_color);
2066 * process_scheduled_works - process scheduled works
2069 * Process all scheduled works. Please note that the scheduled list
2070 * may change while processing a work, so this function repeatedly
2071 * fetches a work from the top and executes it.
2074 * spin_lock_irq(pool->lock) which may be released and regrabbed
2077 static void process_scheduled_works(struct worker *worker)
2079 while (!list_empty(&worker->scheduled)) {
2080 struct work_struct *work = list_first_entry(&worker->scheduled,
2081 struct work_struct, entry);
2082 process_one_work(worker, work);
2087 * worker_thread - the worker thread function
2090 * The worker thread function. All workers belong to a worker_pool -
2091 * either a per-cpu one or dynamic unbound one. These workers process all
2092 * work items regardless of their specific target workqueue. The only
2093 * exception is work items which belong to workqueues with a rescuer which
2094 * will be explained in rescuer_thread().
2098 static int worker_thread(void *__worker)
2100 struct worker *worker = __worker;
2101 struct worker_pool *pool = worker->pool;
2103 /* tell the scheduler that this is a workqueue worker */
2104 worker->task->flags |= PF_WQ_WORKER;
2106 spin_lock_irq(&pool->lock);
2108 /* am I supposed to die? */
2109 if (unlikely(worker->flags & WORKER_DIE)) {
2110 spin_unlock_irq(&pool->lock);
2111 WARN_ON_ONCE(!list_empty(&worker->entry));
2112 worker->task->flags &= ~PF_WQ_WORKER;
2114 set_task_comm(worker->task, "kworker/dying");
2115 ida_simple_remove(&pool->worker_ida, worker->id);
2116 worker_detach_from_pool(worker, pool);
2121 worker_leave_idle(worker);
2123 /* no more worker necessary? */
2124 if (!need_more_worker(pool))
2127 /* do we need to manage? */
2128 if (unlikely(!may_start_working(pool)) && manage_workers(worker))
2132 * ->scheduled list can only be filled while a worker is
2133 * preparing to process a work or actually processing it.
2134 * Make sure nobody diddled with it while I was sleeping.
2136 WARN_ON_ONCE(!list_empty(&worker->scheduled));
2139 * Finish PREP stage. We're guaranteed to have at least one idle
2140 * worker or that someone else has already assumed the manager
2141 * role. This is where @worker starts participating in concurrency
2142 * management if applicable and concurrency management is restored
2143 * after being rebound. See rebind_workers() for details.
2145 worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND);
2148 struct work_struct *work =
2149 list_first_entry(&pool->worklist,
2150 struct work_struct, entry);
2152 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
2153 /* optimization path, not strictly necessary */
2154 process_one_work(worker, work);
2155 if (unlikely(!list_empty(&worker->scheduled)))
2156 process_scheduled_works(worker);
2158 move_linked_works(work, &worker->scheduled, NULL);
2159 process_scheduled_works(worker);
2161 } while (keep_working(pool));
2163 worker_set_flags(worker, WORKER_PREP);
2166 * pool->lock is held and there's no work to process and no need to
2167 * manage, sleep. Workers are woken up only while holding
2168 * pool->lock or from local cpu, so setting the current state
2169 * before releasing pool->lock is enough to prevent losing any
2172 worker_enter_idle(worker);
2173 __set_current_state(TASK_INTERRUPTIBLE);
2174 spin_unlock_irq(&pool->lock);
2180 * rescuer_thread - the rescuer thread function
2183 * Workqueue rescuer thread function. There's one rescuer for each
2184 * workqueue which has WQ_MEM_RECLAIM set.
2186 * Regular work processing on a pool may block trying to create a new
2187 * worker which uses GFP_KERNEL allocation which has slight chance of
2188 * developing into deadlock if some works currently on the same queue
2189 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2190 * the problem rescuer solves.
2192 * When such condition is possible, the pool summons rescuers of all
2193 * workqueues which have works queued on the pool and let them process
2194 * those works so that forward progress can be guaranteed.
2196 * This should happen rarely.
2200 static int rescuer_thread(void *__rescuer)
2202 struct worker *rescuer = __rescuer;
2203 struct workqueue_struct *wq = rescuer->rescue_wq;
2204 struct list_head *scheduled = &rescuer->scheduled;
2207 set_user_nice(current, RESCUER_NICE_LEVEL);
2210 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2211 * doesn't participate in concurrency management.
2213 rescuer->task->flags |= PF_WQ_WORKER;
2215 set_current_state(TASK_INTERRUPTIBLE);
2218 * By the time the rescuer is requested to stop, the workqueue
2219 * shouldn't have any work pending, but @wq->maydays may still have
2220 * pwq(s) queued. This can happen by non-rescuer workers consuming
2221 * all the work items before the rescuer got to them. Go through
2222 * @wq->maydays processing before acting on should_stop so that the
2223 * list is always empty on exit.
2225 should_stop = kthread_should_stop();
2227 /* see whether any pwq is asking for help */
2228 spin_lock_irq(&wq_mayday_lock);
2230 while (!list_empty(&wq->maydays)) {
2231 struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
2232 struct pool_workqueue, mayday_node);
2233 struct worker_pool *pool = pwq->pool;
2234 struct work_struct *work, *n;
2236 __set_current_state(TASK_RUNNING);
2237 list_del_init(&pwq->mayday_node);
2239 spin_unlock_irq(&wq_mayday_lock);
2241 worker_attach_to_pool(rescuer, pool);
2243 spin_lock_irq(&pool->lock);
2244 rescuer->pool = pool;
2247 * Slurp in all works issued via this workqueue and
2250 WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
2251 list_for_each_entry_safe(work, n, &pool->worklist, entry)
2252 if (get_work_pwq(work) == pwq)
2253 move_linked_works(work, scheduled, &n);
2255 process_scheduled_works(rescuer);
2258 * Put the reference grabbed by send_mayday(). @pool won't
2259 * go away while we're still attached to it.
2264 * Leave this pool. If need_more_worker() is %true, notify a
2265 * regular worker; otherwise, we end up with 0 concurrency
2266 * and stalling the execution.
2268 if (need_more_worker(pool))
2269 wake_up_worker(pool);
2271 rescuer->pool = NULL;
2272 spin_unlock_irq(&pool->lock);
2274 worker_detach_from_pool(rescuer, pool);
2276 spin_lock_irq(&wq_mayday_lock);
2279 spin_unlock_irq(&wq_mayday_lock);
2282 __set_current_state(TASK_RUNNING);
2283 rescuer->task->flags &= ~PF_WQ_WORKER;
2287 /* rescuers should never participate in concurrency management */
2288 WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
2294 struct work_struct work;
2295 struct completion done;
2298 static void wq_barrier_func(struct work_struct *work)
2300 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
2301 complete(&barr->done);
2305 * insert_wq_barrier - insert a barrier work
2306 * @pwq: pwq to insert barrier into
2307 * @barr: wq_barrier to insert
2308 * @target: target work to attach @barr to
2309 * @worker: worker currently executing @target, NULL if @target is not executing
2311 * @barr is linked to @target such that @barr is completed only after
2312 * @target finishes execution. Please note that the ordering
2313 * guarantee is observed only with respect to @target and on the local
2316 * Currently, a queued barrier can't be canceled. This is because
2317 * try_to_grab_pending() can't determine whether the work to be
2318 * grabbed is at the head of the queue and thus can't clear LINKED
2319 * flag of the previous work while there must be a valid next work
2320 * after a work with LINKED flag set.
2322 * Note that when @worker is non-NULL, @target may be modified
2323 * underneath us, so we can't reliably determine pwq from @target.
2326 * spin_lock_irq(pool->lock).
2328 static void insert_wq_barrier(struct pool_workqueue *pwq,
2329 struct wq_barrier *barr,
2330 struct work_struct *target, struct worker *worker)
2332 struct list_head *head;
2333 unsigned int linked = 0;
2336 * debugobject calls are safe here even with pool->lock locked
2337 * as we know for sure that this will not trigger any of the
2338 * checks and call back into the fixup functions where we
2341 INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
2342 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
2343 init_completion(&barr->done);
2346 * If @target is currently being executed, schedule the
2347 * barrier to the worker; otherwise, put it after @target.
2350 head = worker->scheduled.next;
2352 unsigned long *bits = work_data_bits(target);
2354 head = target->entry.next;
2355 /* there can already be other linked works, inherit and set */
2356 linked = *bits & WORK_STRUCT_LINKED;
2357 __set_bit(WORK_STRUCT_LINKED_BIT, bits);
2360 debug_work_activate(&barr->work);
2361 insert_work(pwq, &barr->work, head,
2362 work_color_to_flags(WORK_NO_COLOR) | linked);
2366 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2367 * @wq: workqueue being flushed
2368 * @flush_color: new flush color, < 0 for no-op
2369 * @work_color: new work color, < 0 for no-op
2371 * Prepare pwqs for workqueue flushing.
2373 * If @flush_color is non-negative, flush_color on all pwqs should be
2374 * -1. If no pwq has in-flight commands at the specified color, all
2375 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2376 * has in flight commands, its pwq->flush_color is set to
2377 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2378 * wakeup logic is armed and %true is returned.
2380 * The caller should have initialized @wq->first_flusher prior to
2381 * calling this function with non-negative @flush_color. If
2382 * @flush_color is negative, no flush color update is done and %false
2385 * If @work_color is non-negative, all pwqs should have the same
2386 * work_color which is previous to @work_color and all will be
2387 * advanced to @work_color.
2390 * mutex_lock(wq->mutex).
2393 * %true if @flush_color >= 0 and there's something to flush. %false
2396 static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
2397 int flush_color, int work_color)
2400 struct pool_workqueue *pwq;
2402 if (flush_color >= 0) {
2403 WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
2404 atomic_set(&wq->nr_pwqs_to_flush, 1);
2407 for_each_pwq(pwq, wq) {
2408 struct worker_pool *pool = pwq->pool;
2410 spin_lock_irq(&pool->lock);
2412 if (flush_color >= 0) {
2413 WARN_ON_ONCE(pwq->flush_color != -1);
2415 if (pwq->nr_in_flight[flush_color]) {
2416 pwq->flush_color = flush_color;
2417 atomic_inc(&wq->nr_pwqs_to_flush);
2422 if (work_color >= 0) {
2423 WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
2424 pwq->work_color = work_color;
2427 spin_unlock_irq(&pool->lock);
2430 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
2431 complete(&wq->first_flusher->done);
2437 * flush_workqueue - ensure that any scheduled work has run to completion.
2438 * @wq: workqueue to flush
2440 * This function sleeps until all work items which were queued on entry
2441 * have finished execution, but it is not livelocked by new incoming ones.
2443 void flush_workqueue(struct workqueue_struct *wq)
2445 struct wq_flusher this_flusher = {
2446 .list = LIST_HEAD_INIT(this_flusher.list),
2448 .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
2452 lock_map_acquire(&wq->lockdep_map);
2453 lock_map_release(&wq->lockdep_map);
2455 mutex_lock(&wq->mutex);
2458 * Start-to-wait phase
2460 next_color = work_next_color(wq->work_color);
2462 if (next_color != wq->flush_color) {
2464 * Color space is not full. The current work_color
2465 * becomes our flush_color and work_color is advanced
2468 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
2469 this_flusher.flush_color = wq->work_color;
2470 wq->work_color = next_color;
2472 if (!wq->first_flusher) {
2473 /* no flush in progress, become the first flusher */
2474 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
2476 wq->first_flusher = &this_flusher;
2478 if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
2480 /* nothing to flush, done */
2481 wq->flush_color = next_color;
2482 wq->first_flusher = NULL;
2487 WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
2488 list_add_tail(&this_flusher.list, &wq->flusher_queue);
2489 flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
2493 * Oops, color space is full, wait on overflow queue.
2494 * The next flush completion will assign us
2495 * flush_color and transfer to flusher_queue.
2497 list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2500 mutex_unlock(&wq->mutex);
2502 wait_for_completion(&this_flusher.done);
2505 * Wake-up-and-cascade phase
2507 * First flushers are responsible for cascading flushes and
2508 * handling overflow. Non-first flushers can simply return.
2510 if (wq->first_flusher != &this_flusher)
2513 mutex_lock(&wq->mutex);
2515 /* we might have raced, check again with mutex held */
2516 if (wq->first_flusher != &this_flusher)
2519 wq->first_flusher = NULL;
2521 WARN_ON_ONCE(!list_empty(&this_flusher.list));
2522 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
2525 struct wq_flusher *next, *tmp;
2527 /* complete all the flushers sharing the current flush color */
2528 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2529 if (next->flush_color != wq->flush_color)
2531 list_del_init(&next->list);
2532 complete(&next->done);
2535 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
2536 wq->flush_color != work_next_color(wq->work_color));
2538 /* this flush_color is finished, advance by one */
2539 wq->flush_color = work_next_color(wq->flush_color);
2541 /* one color has been freed, handle overflow queue */
2542 if (!list_empty(&wq->flusher_overflow)) {
2544 * Assign the same color to all overflowed
2545 * flushers, advance work_color and append to
2546 * flusher_queue. This is the start-to-wait
2547 * phase for these overflowed flushers.
2549 list_for_each_entry(tmp, &wq->flusher_overflow, list)
2550 tmp->flush_color = wq->work_color;
2552 wq->work_color = work_next_color(wq->work_color);
2554 list_splice_tail_init(&wq->flusher_overflow,
2555 &wq->flusher_queue);
2556 flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
2559 if (list_empty(&wq->flusher_queue)) {
2560 WARN_ON_ONCE(wq->flush_color != wq->work_color);
2565 * Need to flush more colors. Make the next flusher
2566 * the new first flusher and arm pwqs.
2568 WARN_ON_ONCE(wq->flush_color == wq->work_color);
2569 WARN_ON_ONCE(wq->flush_color != next->flush_color);
2571 list_del_init(&next->list);
2572 wq->first_flusher = next;
2574 if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
2578 * Meh... this color is already done, clear first
2579 * flusher and repeat cascading.
2581 wq->first_flusher = NULL;
2585 mutex_unlock(&wq->mutex);
2587 EXPORT_SYMBOL_GPL(flush_workqueue);
2590 * drain_workqueue - drain a workqueue
2591 * @wq: workqueue to drain
2593 * Wait until the workqueue becomes empty. While draining is in progress,
2594 * only chain queueing is allowed. IOW, only currently pending or running
2595 * work items on @wq can queue further work items on it. @wq is flushed
2596 * repeatedly until it becomes empty. The number of flushing is detemined
2597 * by the depth of chaining and should be relatively short. Whine if it
2600 void drain_workqueue(struct workqueue_struct *wq)
2602 unsigned int flush_cnt = 0;
2603 struct pool_workqueue *pwq;
2606 * __queue_work() needs to test whether there are drainers, is much
2607 * hotter than drain_workqueue() and already looks at @wq->flags.
2608 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
2610 mutex_lock(&wq->mutex);
2611 if (!wq->nr_drainers++)
2612 wq->flags |= __WQ_DRAINING;
2613 mutex_unlock(&wq->mutex);
2615 flush_workqueue(wq);
2617 mutex_lock(&wq->mutex);
2619 for_each_pwq(pwq, wq) {
2622 spin_lock_irq(&pwq->pool->lock);
2623 drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
2624 spin_unlock_irq(&pwq->pool->lock);
2629 if (++flush_cnt == 10 ||
2630 (flush_cnt % 100 == 0 && flush_cnt <= 1000))
2631 pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
2632 wq->name, flush_cnt);
2634 mutex_unlock(&wq->mutex);
2638 if (!--wq->nr_drainers)
2639 wq->flags &= ~__WQ_DRAINING;
2640 mutex_unlock(&wq->mutex);
2642 EXPORT_SYMBOL_GPL(drain_workqueue);
2644 static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
2646 struct worker *worker = NULL;
2647 struct worker_pool *pool;
2648 struct pool_workqueue *pwq;
2652 local_irq_disable();
2653 pool = get_work_pool(work);
2659 spin_lock(&pool->lock);
2660 /* see the comment in try_to_grab_pending() with the same code */
2661 pwq = get_work_pwq(work);
2663 if (unlikely(pwq->pool != pool))
2666 worker = find_worker_executing_work(pool, work);
2669 pwq = worker->current_pwq;
2672 insert_wq_barrier(pwq, barr, work, worker);
2673 spin_unlock_irq(&pool->lock);
2676 * If @max_active is 1 or rescuer is in use, flushing another work
2677 * item on the same workqueue may lead to deadlock. Make sure the
2678 * flusher is not running on the same workqueue by verifying write
2681 if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)
2682 lock_map_acquire(&pwq->wq->lockdep_map);
2684 lock_map_acquire_read(&pwq->wq->lockdep_map);
2685 lock_map_release(&pwq->wq->lockdep_map);
2689 spin_unlock_irq(&pool->lock);
2694 * flush_work - wait for a work to finish executing the last queueing instance
2695 * @work: the work to flush
2697 * Wait until @work has finished execution. @work is guaranteed to be idle
2698 * on return if it hasn't been requeued since flush started.
2701 * %true if flush_work() waited for the work to finish execution,
2702 * %false if it was already idle.
2704 bool flush_work(struct work_struct *work)
2706 struct wq_barrier barr;
2708 lock_map_acquire(&work->lockdep_map);
2709 lock_map_release(&work->lockdep_map);
2711 if (start_flush_work(work, &barr)) {
2712 wait_for_completion(&barr.done);
2713 destroy_work_on_stack(&barr.work);
2719 EXPORT_SYMBOL_GPL(flush_work);
2721 static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
2723 unsigned long flags;
2727 ret = try_to_grab_pending(work, is_dwork, &flags);
2729 * If someone else is canceling, wait for the same event it
2730 * would be waiting for before retrying.
2732 if (unlikely(ret == -ENOENT))
2734 } while (unlikely(ret < 0));
2736 /* tell other tasks trying to grab @work to back off */
2737 mark_work_canceling(work);
2738 local_irq_restore(flags);
2741 clear_work_data(work);
2746 * cancel_work_sync - cancel a work and wait for it to finish
2747 * @work: the work to cancel
2749 * Cancel @work and wait for its execution to finish. This function
2750 * can be used even if the work re-queues itself or migrates to
2751 * another workqueue. On return from this function, @work is
2752 * guaranteed to be not pending or executing on any CPU.
2754 * cancel_work_sync(&delayed_work->work) must not be used for
2755 * delayed_work's. Use cancel_delayed_work_sync() instead.
2757 * The caller must ensure that the workqueue on which @work was last
2758 * queued can't be destroyed before this function returns.
2761 * %true if @work was pending, %false otherwise.
2763 bool cancel_work_sync(struct work_struct *work)
2765 return __cancel_work_timer(work, false);
2767 EXPORT_SYMBOL_GPL(cancel_work_sync);
2770 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2771 * @dwork: the delayed work to flush
2773 * Delayed timer is cancelled and the pending work is queued for
2774 * immediate execution. Like flush_work(), this function only
2775 * considers the last queueing instance of @dwork.
2778 * %true if flush_work() waited for the work to finish execution,
2779 * %false if it was already idle.
2781 bool flush_delayed_work(struct delayed_work *dwork)
2783 local_irq_disable();
2784 if (del_timer_sync(&dwork->timer))
2785 __queue_work(dwork->cpu, dwork->wq, &dwork->work);
2787 return flush_work(&dwork->work);
2789 EXPORT_SYMBOL(flush_delayed_work);
2792 * cancel_delayed_work - cancel a delayed work
2793 * @dwork: delayed_work to cancel
2795 * Kill off a pending delayed_work.
2797 * Return: %true if @dwork was pending and canceled; %false if it wasn't
2801 * The work callback function may still be running on return, unless
2802 * it returns %true and the work doesn't re-arm itself. Explicitly flush or
2803 * use cancel_delayed_work_sync() to wait on it.
2805 * This function is safe to call from any context including IRQ handler.
2807 bool cancel_delayed_work(struct delayed_work *dwork)
2809 unsigned long flags;
2813 ret = try_to_grab_pending(&dwork->work, true, &flags);
2814 } while (unlikely(ret == -EAGAIN));
2816 if (unlikely(ret < 0))
2819 set_work_pool_and_clear_pending(&dwork->work,
2820 get_work_pool_id(&dwork->work));
2821 local_irq_restore(flags);
2824 EXPORT_SYMBOL(cancel_delayed_work);
2827 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2828 * @dwork: the delayed work cancel
2830 * This is cancel_work_sync() for delayed works.
2833 * %true if @dwork was pending, %false otherwise.
2835 bool cancel_delayed_work_sync(struct delayed_work *dwork)
2837 return __cancel_work_timer(&dwork->work, true);
2839 EXPORT_SYMBOL(cancel_delayed_work_sync);
2842 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2843 * @func: the function to call
2845 * schedule_on_each_cpu() executes @func on each online CPU using the
2846 * system workqueue and blocks until all CPUs have completed.
2847 * schedule_on_each_cpu() is very slow.
2850 * 0 on success, -errno on failure.
2852 int schedule_on_each_cpu(work_func_t func)
2855 struct work_struct __percpu *works;
2857 works = alloc_percpu(struct work_struct);
2863 for_each_online_cpu(cpu) {
2864 struct work_struct *work = per_cpu_ptr(works, cpu);
2866 INIT_WORK(work, func);
2867 schedule_work_on(cpu, work);
2870 for_each_online_cpu(cpu)
2871 flush_work(per_cpu_ptr(works, cpu));
2879 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2881 * Forces execution of the kernel-global workqueue and blocks until its
2884 * Think twice before calling this function! It's very easy to get into
2885 * trouble if you don't take great care. Either of the following situations
2886 * will lead to deadlock:
2888 * One of the work items currently on the workqueue needs to acquire
2889 * a lock held by your code or its caller.
2891 * Your code is running in the context of a work routine.
2893 * They will be detected by lockdep when they occur, but the first might not
2894 * occur very often. It depends on what work items are on the workqueue and
2895 * what locks they need, which you have no control over.
2897 * In most situations flushing the entire workqueue is overkill; you merely
2898 * need to know that a particular work item isn't queued and isn't running.
2899 * In such cases you should use cancel_delayed_work_sync() or
2900 * cancel_work_sync() instead.
2902 void flush_scheduled_work(void)
2904 flush_workqueue(system_wq);
2906 EXPORT_SYMBOL(flush_scheduled_work);
2909 * execute_in_process_context - reliably execute the routine with user context
2910 * @fn: the function to execute
2911 * @ew: guaranteed storage for the execute work structure (must
2912 * be available when the work executes)
2914 * Executes the function immediately if process context is available,
2915 * otherwise schedules the function for delayed execution.
2917 * Return: 0 - function was executed
2918 * 1 - function was scheduled for execution
2920 int execute_in_process_context(work_func_t fn, struct execute_work *ew)
2922 if (!in_interrupt()) {
2927 INIT_WORK(&ew->work, fn);
2928 schedule_work(&ew->work);
2932 EXPORT_SYMBOL_GPL(execute_in_process_context);
2936 * Workqueues with WQ_SYSFS flag set is visible to userland via
2937 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
2938 * following attributes.
2940 * per_cpu RO bool : whether the workqueue is per-cpu or unbound
2941 * max_active RW int : maximum number of in-flight work items
2943 * Unbound workqueues have the following extra attributes.
2945 * id RO int : the associated pool ID
2946 * nice RW int : nice value of the workers
2947 * cpumask RW mask : bitmask of allowed CPUs for the workers
2950 struct workqueue_struct *wq;
2954 static struct workqueue_struct *dev_to_wq(struct device *dev)
2956 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
2961 static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr,
2964 struct workqueue_struct *wq = dev_to_wq(dev);
2966 return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
2968 static DEVICE_ATTR_RO(per_cpu);
2970 static ssize_t max_active_show(struct device *dev,
2971 struct device_attribute *attr, char *buf)
2973 struct workqueue_struct *wq = dev_to_wq(dev);
2975 return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
2978 static ssize_t max_active_store(struct device *dev,
2979 struct device_attribute *attr, const char *buf,
2982 struct workqueue_struct *wq = dev_to_wq(dev);
2985 if (sscanf(buf, "%d", &val) != 1 || val <= 0)
2988 workqueue_set_max_active(wq, val);
2991 static DEVICE_ATTR_RW(max_active);
2993 static struct attribute *wq_sysfs_attrs[] = {
2994 &dev_attr_per_cpu.attr,
2995 &dev_attr_max_active.attr,
2998 ATTRIBUTE_GROUPS(wq_sysfs);
3000 static ssize_t wq_pool_ids_show(struct device *dev,
3001 struct device_attribute *attr, char *buf)
3003 struct workqueue_struct *wq = dev_to_wq(dev);
3004 const char *delim = "";
3005 int node, written = 0;
3007 rcu_read_lock_sched();
3008 for_each_node(node) {
3009 written += scnprintf(buf + written, PAGE_SIZE - written,
3010 "%s%d:%d", delim, node,
3011 unbound_pwq_by_node(wq, node)->pool->id);
3014 written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
3015 rcu_read_unlock_sched();
3020 static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr,
3023 struct workqueue_struct *wq = dev_to_wq(dev);
3026 mutex_lock(&wq->mutex);
3027 written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
3028 mutex_unlock(&wq->mutex);
3033 /* prepare workqueue_attrs for sysfs store operations */
3034 static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq)
3036 struct workqueue_attrs *attrs;
3038 attrs = alloc_workqueue_attrs(GFP_KERNEL);
3042 mutex_lock(&wq->mutex);
3043 copy_workqueue_attrs(attrs, wq->unbound_attrs);
3044 mutex_unlock(&wq->mutex);
3048 static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr,
3049 const char *buf, size_t count)
3051 struct workqueue_struct *wq = dev_to_wq(dev);
3052 struct workqueue_attrs *attrs;
3055 attrs = wq_sysfs_prep_attrs(wq);
3059 if (sscanf(buf, "%d", &attrs->nice) == 1 &&
3060 attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)
3061 ret = apply_workqueue_attrs(wq, attrs);
3065 free_workqueue_attrs(attrs);
3066 return ret ?: count;
3069 static ssize_t wq_cpumask_show(struct device *dev,
3070 struct device_attribute *attr, char *buf)
3072 struct workqueue_struct *wq = dev_to_wq(dev);
3075 mutex_lock(&wq->mutex);
3076 written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask);
3077 mutex_unlock(&wq->mutex);
3079 written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
3083 static ssize_t wq_cpumask_store(struct device *dev,
3084 struct device_attribute *attr,
3085 const char *buf, size_t count)
3087 struct workqueue_struct *wq = dev_to_wq(dev);
3088 struct workqueue_attrs *attrs;
3091 attrs = wq_sysfs_prep_attrs(wq);
3095 ret = cpumask_parse(buf, attrs->cpumask);
3097 ret = apply_workqueue_attrs(wq, attrs);
3099 free_workqueue_attrs(attrs);
3100 return ret ?: count;
3103 static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr,
3106 struct workqueue_struct *wq = dev_to_wq(dev);
3109 mutex_lock(&wq->mutex);
3110 written = scnprintf(buf, PAGE_SIZE, "%d\n",
3111 !wq->unbound_attrs->no_numa);
3112 mutex_unlock(&wq->mutex);
3117 static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr,
3118 const char *buf, size_t count)
3120 struct workqueue_struct *wq = dev_to_wq(dev);
3121 struct workqueue_attrs *attrs;
3124 attrs = wq_sysfs_prep_attrs(wq);
3129 if (sscanf(buf, "%d", &v) == 1) {
3130 attrs->no_numa = !v;
3131 ret = apply_workqueue_attrs(wq, attrs);
3134 free_workqueue_attrs(attrs);
3135 return ret ?: count;
3138 static struct device_attribute wq_sysfs_unbound_attrs[] = {
3139 __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL),
3140 __ATTR(nice, 0644, wq_nice_show, wq_nice_store),
3141 __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
3142 __ATTR(numa, 0644, wq_numa_show, wq_numa_store),
3146 static struct bus_type wq_subsys = {
3147 .name = "workqueue",
3148 .dev_groups = wq_sysfs_groups,
3151 static int __init wq_sysfs_init(void)
3153 return subsys_virtual_register(&wq_subsys, NULL);
3155 core_initcall(wq_sysfs_init);
3157 static void wq_device_release(struct device *dev)
3159 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
3165 * workqueue_sysfs_register - make a workqueue visible in sysfs
3166 * @wq: the workqueue to register
3168 * Expose @wq in sysfs under /sys/bus/workqueue/devices.
3169 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
3170 * which is the preferred method.
3172 * Workqueue user should use this function directly iff it wants to apply
3173 * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
3174 * apply_workqueue_attrs() may race against userland updating the
3177 * Return: 0 on success, -errno on failure.
3179 int workqueue_sysfs_register(struct workqueue_struct *wq)
3181 struct wq_device *wq_dev;
3185 * Adjusting max_active or creating new pwqs by applyting
3186 * attributes breaks ordering guarantee. Disallow exposing ordered
3189 if (WARN_ON(wq->flags & __WQ_ORDERED))
3192 wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
3197 wq_dev->dev.bus = &wq_subsys;
3198 wq_dev->dev.init_name = wq->name;
3199 wq_dev->dev.release = wq_device_release;
3202 * unbound_attrs are created separately. Suppress uevent until
3203 * everything is ready.
3205 dev_set_uevent_suppress(&wq_dev->dev, true);
3207 ret = device_register(&wq_dev->dev);
3214 if (wq->flags & WQ_UNBOUND) {
3215 struct device_attribute *attr;
3217 for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
3218 ret = device_create_file(&wq_dev->dev, attr);
3220 device_unregister(&wq_dev->dev);
3227 dev_set_uevent_suppress(&wq_dev->dev, false);
3228 kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
3233 * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
3234 * @wq: the workqueue to unregister
3236 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
3238 static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
3240 struct wq_device *wq_dev = wq->wq_dev;
3246 device_unregister(&wq_dev->dev);
3248 #else /* CONFIG_SYSFS */
3249 static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
3250 #endif /* CONFIG_SYSFS */
3253 * free_workqueue_attrs - free a workqueue_attrs
3254 * @attrs: workqueue_attrs to free
3256 * Undo alloc_workqueue_attrs().
3258 void free_workqueue_attrs(struct workqueue_attrs *attrs)
3261 free_cpumask_var(attrs->cpumask);
3267 * alloc_workqueue_attrs - allocate a workqueue_attrs
3268 * @gfp_mask: allocation mask to use
3270 * Allocate a new workqueue_attrs, initialize with default settings and
3273 * Return: The allocated new workqueue_attr on success. %NULL on failure.
3275 struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask)
3277 struct workqueue_attrs *attrs;
3279 attrs = kzalloc(sizeof(*attrs), gfp_mask);
3282 if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask))
3285 cpumask_copy(attrs->cpumask, cpu_possible_mask);
3288 free_workqueue_attrs(attrs);
3292 static void copy_workqueue_attrs(struct workqueue_attrs *to,
3293 const struct workqueue_attrs *from)
3295 to->nice = from->nice;
3296 cpumask_copy(to->cpumask, from->cpumask);
3298 * Unlike hash and equality test, this function doesn't ignore
3299 * ->no_numa as it is used for both pool and wq attrs. Instead,
3300 * get_unbound_pool() explicitly clears ->no_numa after copying.
3302 to->no_numa = from->no_numa;
3305 /* hash value of the content of @attr */
3306 static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
3310 hash = jhash_1word(attrs->nice, hash);
3311 hash = jhash(cpumask_bits(attrs->cpumask),
3312 BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
3316 /* content equality test */
3317 static bool wqattrs_equal(const struct workqueue_attrs *a,
3318 const struct workqueue_attrs *b)
3320 if (a->nice != b->nice)
3322 if (!cpumask_equal(a->cpumask, b->cpumask))
3328 * init_worker_pool - initialize a newly zalloc'd worker_pool
3329 * @pool: worker_pool to initialize
3331 * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
3333 * Return: 0 on success, -errno on failure. Even on failure, all fields
3334 * inside @pool proper are initialized and put_unbound_pool() can be called
3335 * on @pool safely to release it.
3337 static int init_worker_pool(struct worker_pool *pool)
3339 spin_lock_init(&pool->lock);
3342 pool->node = NUMA_NO_NODE;
3343 pool->flags |= POOL_DISASSOCIATED;
3344 INIT_LIST_HEAD(&pool->worklist);
3345 INIT_LIST_HEAD(&pool->idle_list);
3346 hash_init(pool->busy_hash);
3348 init_timer_deferrable(&pool->idle_timer);
3349 pool->idle_timer.function = idle_worker_timeout;
3350 pool->idle_timer.data = (unsigned long)pool;
3352 setup_timer(&pool->mayday_timer, pool_mayday_timeout,
3353 (unsigned long)pool);
3355 mutex_init(&pool->manager_arb);
3356 mutex_init(&pool->attach_mutex);
3357 INIT_LIST_HEAD(&pool->workers);
3359 ida_init(&pool->worker_ida);
3360 INIT_HLIST_NODE(&pool->hash_node);
3363 /* shouldn't fail above this point */
3364 pool->attrs = alloc_workqueue_attrs(GFP_KERNEL);
3370 static void rcu_free_pool(struct rcu_head *rcu)
3372 struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
3374 ida_destroy(&pool->worker_ida);
3375 free_workqueue_attrs(pool->attrs);
3380 * put_unbound_pool - put a worker_pool
3381 * @pool: worker_pool to put
3383 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
3384 * safe manner. get_unbound_pool() calls this function on its failure path
3385 * and this function should be able to release pools which went through,
3386 * successfully or not, init_worker_pool().
3388 * Should be called with wq_pool_mutex held.
3390 static void put_unbound_pool(struct worker_pool *pool)
3392 DECLARE_COMPLETION_ONSTACK(detach_completion);
3393 struct worker *worker;
3395 lockdep_assert_held(&wq_pool_mutex);
3401 if (WARN_ON(!(pool->cpu < 0)) ||
3402 WARN_ON(!list_empty(&pool->worklist)))
3405 /* release id and unhash */
3407 idr_remove(&worker_pool_idr, pool->id);
3408 hash_del(&pool->hash_node);
3411 * Become the manager and destroy all workers. Grabbing
3412 * manager_arb prevents @pool's workers from blocking on
3415 mutex_lock(&pool->manager_arb);
3417 spin_lock_irq(&pool->lock);
3418 while ((worker = first_idle_worker(pool)))
3419 destroy_worker(worker);
3420 WARN_ON(pool->nr_workers || pool->nr_idle);
3421 spin_unlock_irq(&pool->lock);
3423 mutex_lock(&pool->attach_mutex);
3424 if (!list_empty(&pool->workers))
3425 pool->detach_completion = &detach_completion;
3426 mutex_unlock(&pool->attach_mutex);
3428 if (pool->detach_completion)
3429 wait_for_completion(pool->detach_completion);
3431 mutex_unlock(&pool->manager_arb);
3433 /* shut down the timers */
3434 del_timer_sync(&pool->idle_timer);
3435 del_timer_sync(&pool->mayday_timer);
3437 /* sched-RCU protected to allow dereferences from get_work_pool() */
3438 call_rcu_sched(&pool->rcu, rcu_free_pool);
3442 * get_unbound_pool - get a worker_pool with the specified attributes
3443 * @attrs: the attributes of the worker_pool to get
3445 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3446 * reference count and return it. If there already is a matching
3447 * worker_pool, it will be used; otherwise, this function attempts to
3450 * Should be called with wq_pool_mutex held.
3452 * Return: On success, a worker_pool with the same attributes as @attrs.
3453 * On failure, %NULL.
3455 static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
3457 u32 hash = wqattrs_hash(attrs);
3458 struct worker_pool *pool;
3461 lockdep_assert_held(&wq_pool_mutex);
3463 /* do we already have a matching pool? */
3464 hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
3465 if (wqattrs_equal(pool->attrs, attrs)) {
3471 /* nope, create a new one */
3472 pool = kzalloc(sizeof(*pool), GFP_KERNEL);
3473 if (!pool || init_worker_pool(pool) < 0)
3476 lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
3477 copy_workqueue_attrs(pool->attrs, attrs);
3480 * no_numa isn't a worker_pool attribute, always clear it. See
3481 * 'struct workqueue_attrs' comments for detail.
3483 pool->attrs->no_numa = false;
3485 /* if cpumask is contained inside a NUMA node, we belong to that node */
3486 if (wq_numa_enabled) {
3487 for_each_node(node) {
3488 if (cpumask_subset(pool->attrs->cpumask,
3489 wq_numa_possible_cpumask[node])) {
3496 if (worker_pool_assign_id(pool) < 0)
3499 /* create and start the initial worker */
3500 if (!create_worker(pool))
3504 hash_add(unbound_pool_hash, &pool->hash_node, hash);
3509 put_unbound_pool(pool);
3513 static void rcu_free_pwq(struct rcu_head *rcu)
3515 kmem_cache_free(pwq_cache,
3516 container_of(rcu, struct pool_workqueue, rcu));
3520 * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3521 * and needs to be destroyed.
3523 static void pwq_unbound_release_workfn(struct work_struct *work)
3525 struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
3526 unbound_release_work);
3527 struct workqueue_struct *wq = pwq->wq;
3528 struct worker_pool *pool = pwq->pool;
3531 if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
3534 mutex_lock(&wq->mutex);
3535 list_del_rcu(&pwq->pwqs_node);
3536 is_last = list_empty(&wq->pwqs);
3537 mutex_unlock(&wq->mutex);
3539 mutex_lock(&wq_pool_mutex);
3540 put_unbound_pool(pool);
3541 mutex_unlock(&wq_pool_mutex);
3543 call_rcu_sched(&pwq->rcu, rcu_free_pwq);
3546 * If we're the last pwq going away, @wq is already dead and no one
3547 * is gonna access it anymore. Free it.
3550 free_workqueue_attrs(wq->unbound_attrs);
3556 * pwq_adjust_max_active - update a pwq's max_active to the current setting
3557 * @pwq: target pool_workqueue
3559 * If @pwq isn't freezing, set @pwq->max_active to the associated
3560 * workqueue's saved_max_active and activate delayed work items
3561 * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
3563 static void pwq_adjust_max_active(struct pool_workqueue *pwq)
3565 struct workqueue_struct *wq = pwq->wq;
3566 bool freezable = wq->flags & WQ_FREEZABLE;
3568 /* for @wq->saved_max_active */
3569 lockdep_assert_held(&wq->mutex);
3571 /* fast exit for non-freezable wqs */
3572 if (!freezable && pwq->max_active == wq->saved_max_active)
3575 spin_lock_irq(&pwq->pool->lock);
3578 * During [un]freezing, the caller is responsible for ensuring that
3579 * this function is called at least once after @workqueue_freezing
3580 * is updated and visible.
3582 if (!freezable || !workqueue_freezing) {
3583 pwq->max_active = wq->saved_max_active;
3585 while (!list_empty(&pwq->delayed_works) &&
3586 pwq->nr_active < pwq->max_active)
3587 pwq_activate_first_delayed(pwq);
3590 * Need to kick a worker after thawed or an unbound wq's
3591 * max_active is bumped. It's a slow path. Do it always.
3593 wake_up_worker(pwq->pool);
3595 pwq->max_active = 0;
3598 spin_unlock_irq(&pwq->pool->lock);
3601 /* initialize newly alloced @pwq which is associated with @wq and @pool */
3602 static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
3603 struct worker_pool *pool)
3605 BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
3607 memset(pwq, 0, sizeof(*pwq));
3611 pwq->flush_color = -1;
3613 INIT_LIST_HEAD(&pwq->delayed_works);
3614 INIT_LIST_HEAD(&pwq->pwqs_node);
3615 INIT_LIST_HEAD(&pwq->mayday_node);
3616 INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
3619 /* sync @pwq with the current state of its associated wq and link it */
3620 static void link_pwq(struct pool_workqueue *pwq)
3622 struct workqueue_struct *wq = pwq->wq;
3624 lockdep_assert_held(&wq->mutex);
3626 /* may be called multiple times, ignore if already linked */
3627 if (!list_empty(&pwq->pwqs_node))
3630 /* set the matching work_color */
3631 pwq->work_color = wq->work_color;
3633 /* sync max_active to the current setting */
3634 pwq_adjust_max_active(pwq);
3637 list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
3640 /* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3641 static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq,
3642 const struct workqueue_attrs *attrs)
3644 struct worker_pool *pool;
3645 struct pool_workqueue *pwq;
3647 lockdep_assert_held(&wq_pool_mutex);
3649 pool = get_unbound_pool(attrs);
3653 pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
3655 put_unbound_pool(pool);
3659 init_pwq(pwq, wq, pool);
3663 /* undo alloc_unbound_pwq(), used only in the error path */
3664 static void free_unbound_pwq(struct pool_workqueue *pwq)
3666 lockdep_assert_held(&wq_pool_mutex);
3669 put_unbound_pool(pwq->pool);
3670 kmem_cache_free(pwq_cache, pwq);
3675 * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node
3676 * @attrs: the wq_attrs of interest
3677 * @node: the target NUMA node
3678 * @cpu_going_down: if >= 0, the CPU to consider as offline
3679 * @cpumask: outarg, the resulting cpumask
3681 * Calculate the cpumask a workqueue with @attrs should use on @node. If
3682 * @cpu_going_down is >= 0, that cpu is considered offline during
3683 * calculation. The result is stored in @cpumask.
3685 * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3686 * enabled and @node has online CPUs requested by @attrs, the returned
3687 * cpumask is the intersection of the possible CPUs of @node and
3690 * The caller is responsible for ensuring that the cpumask of @node stays
3693 * Return: %true if the resulting @cpumask is different from @attrs->cpumask,
3696 static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
3697 int cpu_going_down, cpumask_t *cpumask)
3699 if (!wq_numa_enabled || attrs->no_numa)
3702 /* does @node have any online CPUs @attrs wants? */
3703 cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask);
3704 if (cpu_going_down >= 0)
3705 cpumask_clear_cpu(cpu_going_down, cpumask);
3707 if (cpumask_empty(cpumask))
3710 /* yeap, return possible CPUs in @node that @attrs wants */
3711 cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
3712 return !cpumask_equal(cpumask, attrs->cpumask);
3715 cpumask_copy(cpumask, attrs->cpumask);
3719 /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3720 static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
3722 struct pool_workqueue *pwq)
3724 struct pool_workqueue *old_pwq;
3726 lockdep_assert_held(&wq->mutex);
3728 /* link_pwq() can handle duplicate calls */
3731 old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
3732 rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
3737 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
3738 * @wq: the target workqueue
3739 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
3741 * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
3742 * machines, this function maps a separate pwq to each NUMA node with
3743 * possibles CPUs in @attrs->cpumask so that work items are affine to the
3744 * NUMA node it was issued on. Older pwqs are released as in-flight work
3745 * items finish. Note that a work item which repeatedly requeues itself
3746 * back-to-back will stay on its current pwq.
3748 * Performs GFP_KERNEL allocations.
3750 * Return: 0 on success and -errno on failure.
3752 int apply_workqueue_attrs(struct workqueue_struct *wq,
3753 const struct workqueue_attrs *attrs)
3755 struct workqueue_attrs *new_attrs, *tmp_attrs;
3756 struct pool_workqueue **pwq_tbl, *dfl_pwq;
3759 /* only unbound workqueues can change attributes */
3760 if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
3763 /* creating multiple pwqs breaks ordering guarantee */
3764 if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
3767 pwq_tbl = kzalloc(nr_node_ids * sizeof(pwq_tbl[0]), GFP_KERNEL);
3768 new_attrs = alloc_workqueue_attrs(GFP_KERNEL);
3769 tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL);
3770 if (!pwq_tbl || !new_attrs || !tmp_attrs)
3773 /* make a copy of @attrs and sanitize it */
3774 copy_workqueue_attrs(new_attrs, attrs);
3775 cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
3778 * We may create multiple pwqs with differing cpumasks. Make a
3779 * copy of @new_attrs which will be modified and used to obtain
3782 copy_workqueue_attrs(tmp_attrs, new_attrs);
3785 * CPUs should stay stable across pwq creations and installations.
3786 * Pin CPUs, determine the target cpumask for each node and create
3791 mutex_lock(&wq_pool_mutex);
3794 * If something goes wrong during CPU up/down, we'll fall back to
3795 * the default pwq covering whole @attrs->cpumask. Always create
3796 * it even if we don't use it immediately.
3798 dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
3802 for_each_node(node) {
3803 if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) {
3804 pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
3809 pwq_tbl[node] = dfl_pwq;
3813 mutex_unlock(&wq_pool_mutex);
3815 /* all pwqs have been created successfully, let's install'em */
3816 mutex_lock(&wq->mutex);
3818 copy_workqueue_attrs(wq->unbound_attrs, new_attrs);
3820 /* save the previous pwq and install the new one */
3822 pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]);
3824 /* @dfl_pwq might not have been used, ensure it's linked */
3826 swap(wq->dfl_pwq, dfl_pwq);
3828 mutex_unlock(&wq->mutex);
3830 /* put the old pwqs */
3832 put_pwq_unlocked(pwq_tbl[node]);
3833 put_pwq_unlocked(dfl_pwq);
3839 free_workqueue_attrs(tmp_attrs);
3840 free_workqueue_attrs(new_attrs);
3845 free_unbound_pwq(dfl_pwq);
3847 if (pwq_tbl && pwq_tbl[node] != dfl_pwq)
3848 free_unbound_pwq(pwq_tbl[node]);
3849 mutex_unlock(&wq_pool_mutex);
3857 * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
3858 * @wq: the target workqueue
3859 * @cpu: the CPU coming up or going down
3860 * @online: whether @cpu is coming up or going down
3862 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
3863 * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
3866 * If NUMA affinity can't be adjusted due to memory allocation failure, it
3867 * falls back to @wq->dfl_pwq which may not be optimal but is always
3870 * Note that when the last allowed CPU of a NUMA node goes offline for a
3871 * workqueue with a cpumask spanning multiple nodes, the workers which were
3872 * already executing the work items for the workqueue will lose their CPU
3873 * affinity and may execute on any CPU. This is similar to how per-cpu
3874 * workqueues behave on CPU_DOWN. If a workqueue user wants strict
3875 * affinity, it's the user's responsibility to flush the work item from
3878 static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
3881 int node = cpu_to_node(cpu);
3882 int cpu_off = online ? -1 : cpu;
3883 struct pool_workqueue *old_pwq = NULL, *pwq;
3884 struct workqueue_attrs *target_attrs;
3887 lockdep_assert_held(&wq_pool_mutex);
3889 if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND))
3893 * We don't wanna alloc/free wq_attrs for each wq for each CPU.
3894 * Let's use a preallocated one. The following buf is protected by
3895 * CPU hotplug exclusion.
3897 target_attrs = wq_update_unbound_numa_attrs_buf;
3898 cpumask = target_attrs->cpumask;
3900 mutex_lock(&wq->mutex);
3901 if (wq->unbound_attrs->no_numa)
3904 copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
3905 pwq = unbound_pwq_by_node(wq, node);
3908 * Let's determine what needs to be done. If the target cpumask is
3909 * different from wq's, we need to compare it to @pwq's and create
3910 * a new one if they don't match. If the target cpumask equals
3911 * wq's, the default pwq should be used.
3913 if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) {
3914 if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
3920 mutex_unlock(&wq->mutex);
3922 /* create a new pwq */
3923 pwq = alloc_unbound_pwq(wq, target_attrs);
3925 pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
3927 mutex_lock(&wq->mutex);
3932 * Install the new pwq. As this function is called only from CPU
3933 * hotplug callbacks and applying a new attrs is wrapped with
3934 * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
3937 mutex_lock(&wq->mutex);
3938 old_pwq = numa_pwq_tbl_install(wq, node, pwq);
3942 spin_lock_irq(&wq->dfl_pwq->pool->lock);
3943 get_pwq(wq->dfl_pwq);
3944 spin_unlock_irq(&wq->dfl_pwq->pool->lock);
3945 old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
3947 mutex_unlock(&wq->mutex);
3948 put_pwq_unlocked(old_pwq);
3951 static int alloc_and_link_pwqs(struct workqueue_struct *wq)
3953 bool highpri = wq->flags & WQ_HIGHPRI;
3956 if (!(wq->flags & WQ_UNBOUND)) {
3957 wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
3961 for_each_possible_cpu(cpu) {
3962 struct pool_workqueue *pwq =
3963 per_cpu_ptr(wq->cpu_pwqs, cpu);
3964 struct worker_pool *cpu_pools =
3965 per_cpu(cpu_worker_pools, cpu);
3967 init_pwq(pwq, wq, &cpu_pools[highpri]);
3969 mutex_lock(&wq->mutex);
3971 mutex_unlock(&wq->mutex);
3974 } else if (wq->flags & __WQ_ORDERED) {
3975 ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
3976 /* there should only be single pwq for ordering guarantee */
3977 WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node ||
3978 wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
3979 "ordering guarantee broken for workqueue %s\n", wq->name);
3982 return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
3986 static int wq_clamp_max_active(int max_active, unsigned int flags,
3989 int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
3991 if (max_active < 1 || max_active > lim)
3992 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
3993 max_active, name, 1, lim);
3995 return clamp_val(max_active, 1, lim);
3998 struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
4001 struct lock_class_key *key,
4002 const char *lock_name, ...)
4004 size_t tbl_size = 0;
4006 struct workqueue_struct *wq;
4007 struct pool_workqueue *pwq;
4009 /* see the comment above the definition of WQ_POWER_EFFICIENT */
4010 if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
4011 flags |= WQ_UNBOUND;
4013 /* allocate wq and format name */
4014 if (flags & WQ_UNBOUND)
4015 tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]);
4017 wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL);
4021 if (flags & WQ_UNBOUND) {
4022 wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL);
4023 if (!wq->unbound_attrs)
4027 va_start(args, lock_name);
4028 vsnprintf(wq->name, sizeof(wq->name), fmt, args);
4031 max_active = max_active ?: WQ_DFL_ACTIVE;
4032 max_active = wq_clamp_max_active(max_active, flags, wq->name);
4036 wq->saved_max_active = max_active;
4037 mutex_init(&wq->mutex);
4038 atomic_set(&wq->nr_pwqs_to_flush, 0);
4039 INIT_LIST_HEAD(&wq->pwqs);
4040 INIT_LIST_HEAD(&wq->flusher_queue);
4041 INIT_LIST_HEAD(&wq->flusher_overflow);
4042 INIT_LIST_HEAD(&wq->maydays);
4044 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
4045 INIT_LIST_HEAD(&wq->list);
4047 if (alloc_and_link_pwqs(wq) < 0)
4051 * Workqueues which may be used during memory reclaim should
4052 * have a rescuer to guarantee forward progress.
4054 if (flags & WQ_MEM_RECLAIM) {
4055 struct worker *rescuer;
4057 rescuer = alloc_worker(NUMA_NO_NODE);
4061 rescuer->rescue_wq = wq;
4062 rescuer->task = kthread_create(rescuer_thread, rescuer, "%s",
4064 if (IS_ERR(rescuer->task)) {
4069 wq->rescuer = rescuer;
4070 rescuer->task->flags |= PF_NO_SETAFFINITY;
4071 wake_up_process(rescuer->task);
4074 if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
4078 * wq_pool_mutex protects global freeze state and workqueues list.
4079 * Grab it, adjust max_active and add the new @wq to workqueues
4082 mutex_lock(&wq_pool_mutex);
4084 mutex_lock(&wq->mutex);
4085 for_each_pwq(pwq, wq)
4086 pwq_adjust_max_active(pwq);
4087 mutex_unlock(&wq->mutex);
4089 list_add(&wq->list, &workqueues);
4091 mutex_unlock(&wq_pool_mutex);
4096 free_workqueue_attrs(wq->unbound_attrs);
4100 destroy_workqueue(wq);
4103 EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
4106 * destroy_workqueue - safely terminate a workqueue
4107 * @wq: target workqueue
4109 * Safely destroy a workqueue. All work currently pending will be done first.
4111 void destroy_workqueue(struct workqueue_struct *wq)
4113 struct pool_workqueue *pwq;
4116 /* drain it before proceeding with destruction */
4117 drain_workqueue(wq);
4120 mutex_lock(&wq->mutex);
4121 for_each_pwq(pwq, wq) {
4124 for (i = 0; i < WORK_NR_COLORS; i++) {
4125 if (WARN_ON(pwq->nr_in_flight[i])) {
4126 mutex_unlock(&wq->mutex);
4131 if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) ||
4132 WARN_ON(pwq->nr_active) ||
4133 WARN_ON(!list_empty(&pwq->delayed_works))) {
4134 mutex_unlock(&wq->mutex);
4138 mutex_unlock(&wq->mutex);
4141 * wq list is used to freeze wq, remove from list after
4142 * flushing is complete in case freeze races us.
4144 mutex_lock(&wq_pool_mutex);
4145 list_del_init(&wq->list);
4146 mutex_unlock(&wq_pool_mutex);
4148 workqueue_sysfs_unregister(wq);
4151 kthread_stop(wq->rescuer->task);
4156 if (!(wq->flags & WQ_UNBOUND)) {
4158 * The base ref is never dropped on per-cpu pwqs. Directly
4159 * free the pwqs and wq.
4161 free_percpu(wq->cpu_pwqs);
4165 * We're the sole accessor of @wq at this point. Directly
4166 * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
4167 * @wq will be freed when the last pwq is released.
4169 for_each_node(node) {
4170 pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
4171 RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL);
4172 put_pwq_unlocked(pwq);
4176 * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
4177 * put. Don't access it afterwards.
4181 put_pwq_unlocked(pwq);
4184 EXPORT_SYMBOL_GPL(destroy_workqueue);
4187 * workqueue_set_max_active - adjust max_active of a workqueue
4188 * @wq: target workqueue
4189 * @max_active: new max_active value.
4191 * Set max_active of @wq to @max_active.
4194 * Don't call from IRQ context.
4196 void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
4198 struct pool_workqueue *pwq;
4200 /* disallow meddling with max_active for ordered workqueues */
4201 if (WARN_ON(wq->flags & __WQ_ORDERED))
4204 max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
4206 mutex_lock(&wq->mutex);
4208 wq->saved_max_active = max_active;
4210 for_each_pwq(pwq, wq)
4211 pwq_adjust_max_active(pwq);
4213 mutex_unlock(&wq->mutex);
4215 EXPORT_SYMBOL_GPL(workqueue_set_max_active);
4218 * current_is_workqueue_rescuer - is %current workqueue rescuer?
4220 * Determine whether %current is a workqueue rescuer. Can be used from
4221 * work functions to determine whether it's being run off the rescuer task.
4223 * Return: %true if %current is a workqueue rescuer. %false otherwise.
4225 bool current_is_workqueue_rescuer(void)
4227 struct worker *worker = current_wq_worker();
4229 return worker && worker->rescue_wq;
4233 * workqueue_congested - test whether a workqueue is congested
4234 * @cpu: CPU in question
4235 * @wq: target workqueue
4237 * Test whether @wq's cpu workqueue for @cpu is congested. There is
4238 * no synchronization around this function and the test result is
4239 * unreliable and only useful as advisory hints or for debugging.
4241 * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
4242 * Note that both per-cpu and unbound workqueues may be associated with
4243 * multiple pool_workqueues which have separate congested states. A
4244 * workqueue being congested on one CPU doesn't mean the workqueue is also
4245 * contested on other CPUs / NUMA nodes.
4248 * %true if congested, %false otherwise.
4250 bool workqueue_congested(int cpu, struct workqueue_struct *wq)
4252 struct pool_workqueue *pwq;
4255 rcu_read_lock_sched();
4257 if (cpu == WORK_CPU_UNBOUND)
4258 cpu = smp_processor_id();
4260 if (!(wq->flags & WQ_UNBOUND))
4261 pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
4263 pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
4265 ret = !list_empty(&pwq->delayed_works);
4266 rcu_read_unlock_sched();
4270 EXPORT_SYMBOL_GPL(workqueue_congested);
4273 * work_busy - test whether a work is currently pending or running
4274 * @work: the work to be tested
4276 * Test whether @work is currently pending or running. There is no
4277 * synchronization around this function and the test result is
4278 * unreliable and only useful as advisory hints or for debugging.
4281 * OR'd bitmask of WORK_BUSY_* bits.
4283 unsigned int work_busy(struct work_struct *work)
4285 struct worker_pool *pool;
4286 unsigned long flags;
4287 unsigned int ret = 0;
4289 if (work_pending(work))
4290 ret |= WORK_BUSY_PENDING;
4292 local_irq_save(flags);
4293 pool = get_work_pool(work);
4295 spin_lock(&pool->lock);
4296 if (find_worker_executing_work(pool, work))
4297 ret |= WORK_BUSY_RUNNING;
4298 spin_unlock(&pool->lock);
4300 local_irq_restore(flags);
4304 EXPORT_SYMBOL_GPL(work_busy);
4307 * set_worker_desc - set description for the current work item
4308 * @fmt: printf-style format string
4309 * @...: arguments for the format string
4311 * This function can be called by a running work function to describe what
4312 * the work item is about. If the worker task gets dumped, this
4313 * information will be printed out together to help debugging. The
4314 * description can be at most WORKER_DESC_LEN including the trailing '\0'.
4316 void set_worker_desc(const char *fmt, ...)
4318 struct worker *worker = current_wq_worker();
4322 va_start(args, fmt);
4323 vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
4325 worker->desc_valid = true;
4330 * print_worker_info - print out worker information and description
4331 * @log_lvl: the log level to use when printing
4332 * @task: target task
4334 * If @task is a worker and currently executing a work item, print out the
4335 * name of the workqueue being serviced and worker description set with
4336 * set_worker_desc() by the currently executing work item.
4338 * This function can be safely called on any task as long as the
4339 * task_struct itself is accessible. While safe, this function isn't
4340 * synchronized and may print out mixups or garbages of limited length.
4342 void print_worker_info(const char *log_lvl, struct task_struct *task)
4344 work_func_t *fn = NULL;
4345 char name[WQ_NAME_LEN] = { };
4346 char desc[WORKER_DESC_LEN] = { };
4347 struct pool_workqueue *pwq = NULL;
4348 struct workqueue_struct *wq = NULL;
4349 bool desc_valid = false;
4350 struct worker *worker;
4352 if (!(task->flags & PF_WQ_WORKER))
4356 * This function is called without any synchronization and @task
4357 * could be in any state. Be careful with dereferences.
4359 worker = probe_kthread_data(task);
4362 * Carefully copy the associated workqueue's workfn and name. Keep
4363 * the original last '\0' in case the original contains garbage.
4365 probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
4366 probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
4367 probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
4368 probe_kernel_read(name, wq->name, sizeof(name) - 1);
4370 /* copy worker description */
4371 probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid));
4373 probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
4375 if (fn || name[0] || desc[0]) {
4376 printk("%sWorkqueue: %s %pf", log_lvl, name, fn);
4378 pr_cont(" (%s)", desc);
4386 * There are two challenges in supporting CPU hotplug. Firstly, there
4387 * are a lot of assumptions on strong associations among work, pwq and
4388 * pool which make migrating pending and scheduled works very
4389 * difficult to implement without impacting hot paths. Secondly,
4390 * worker pools serve mix of short, long and very long running works making
4391 * blocked draining impractical.
4393 * This is solved by allowing the pools to be disassociated from the CPU
4394 * running as an unbound one and allowing it to be reattached later if the
4395 * cpu comes back online.
4398 static void wq_unbind_fn(struct work_struct *work)
4400 int cpu = smp_processor_id();
4401 struct worker_pool *pool;
4402 struct worker *worker;
4404 for_each_cpu_worker_pool(pool, cpu) {
4405 mutex_lock(&pool->attach_mutex);
4406 spin_lock_irq(&pool->lock);
4409 * We've blocked all attach/detach operations. Make all workers
4410 * unbound and set DISASSOCIATED. Before this, all workers
4411 * except for the ones which are still executing works from
4412 * before the last CPU down must be on the cpu. After
4413 * this, they may become diasporas.
4415 for_each_pool_worker(worker, pool)
4416 worker->flags |= WORKER_UNBOUND;
4418 pool->flags |= POOL_DISASSOCIATED;
4420 spin_unlock_irq(&pool->lock);
4421 mutex_unlock(&pool->attach_mutex);
4424 * Call schedule() so that we cross rq->lock and thus can
4425 * guarantee sched callbacks see the %WORKER_UNBOUND flag.
4426 * This is necessary as scheduler callbacks may be invoked
4432 * Sched callbacks are disabled now. Zap nr_running.
4433 * After this, nr_running stays zero and need_more_worker()
4434 * and keep_working() are always true as long as the
4435 * worklist is not empty. This pool now behaves as an
4436 * unbound (in terms of concurrency management) pool which
4437 * are served by workers tied to the pool.
4439 atomic_set(&pool->nr_running, 0);
4442 * With concurrency management just turned off, a busy
4443 * worker blocking could lead to lengthy stalls. Kick off
4444 * unbound chain execution of currently pending work items.
4446 spin_lock_irq(&pool->lock);
4447 wake_up_worker(pool);
4448 spin_unlock_irq(&pool->lock);
4453 * rebind_workers - rebind all workers of a pool to the associated CPU
4454 * @pool: pool of interest
4456 * @pool->cpu is coming online. Rebind all workers to the CPU.
4458 static void rebind_workers(struct worker_pool *pool)
4460 struct worker *worker;
4462 lockdep_assert_held(&pool->attach_mutex);
4465 * Restore CPU affinity of all workers. As all idle workers should
4466 * be on the run-queue of the associated CPU before any local
4467 * wake-ups for concurrency management happen, restore CPU affinty
4468 * of all workers first and then clear UNBOUND. As we're called
4469 * from CPU_ONLINE, the following shouldn't fail.
4471 for_each_pool_worker(worker, pool)
4472 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4473 pool->attrs->cpumask) < 0);
4475 spin_lock_irq(&pool->lock);
4476 pool->flags &= ~POOL_DISASSOCIATED;
4478 for_each_pool_worker(worker, pool) {
4479 unsigned int worker_flags = worker->flags;
4482 * A bound idle worker should actually be on the runqueue
4483 * of the associated CPU for local wake-ups targeting it to
4484 * work. Kick all idle workers so that they migrate to the
4485 * associated CPU. Doing this in the same loop as
4486 * replacing UNBOUND with REBOUND is safe as no worker will
4487 * be bound before @pool->lock is released.
4489 if (worker_flags & WORKER_IDLE)
4490 wake_up_process(worker->task);
4493 * We want to clear UNBOUND but can't directly call
4494 * worker_clr_flags() or adjust nr_running. Atomically
4495 * replace UNBOUND with another NOT_RUNNING flag REBOUND.
4496 * @worker will clear REBOUND using worker_clr_flags() when
4497 * it initiates the next execution cycle thus restoring
4498 * concurrency management. Note that when or whether
4499 * @worker clears REBOUND doesn't affect correctness.
4501 * ACCESS_ONCE() is necessary because @worker->flags may be
4502 * tested without holding any lock in
4503 * wq_worker_waking_up(). Without it, NOT_RUNNING test may
4504 * fail incorrectly leading to premature concurrency
4505 * management operations.
4507 WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
4508 worker_flags |= WORKER_REBOUND;
4509 worker_flags &= ~WORKER_UNBOUND;
4510 ACCESS_ONCE(worker->flags) = worker_flags;
4513 spin_unlock_irq(&pool->lock);
4517 * restore_unbound_workers_cpumask - restore cpumask of unbound workers
4518 * @pool: unbound pool of interest
4519 * @cpu: the CPU which is coming up
4521 * An unbound pool may end up with a cpumask which doesn't have any online
4522 * CPUs. When a worker of such pool get scheduled, the scheduler resets
4523 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4524 * online CPU before, cpus_allowed of all its workers should be restored.
4526 static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
4528 static cpumask_t cpumask;
4529 struct worker *worker;
4531 lockdep_assert_held(&pool->attach_mutex);
4533 /* is @cpu allowed for @pool? */
4534 if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
4537 /* is @cpu the only online CPU? */
4538 cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
4539 if (cpumask_weight(&cpumask) != 1)
4542 /* as we're called from CPU_ONLINE, the following shouldn't fail */
4543 for_each_pool_worker(worker, pool)
4544 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4545 pool->attrs->cpumask) < 0);
4549 * Workqueues should be brought up before normal priority CPU notifiers.
4550 * This will be registered high priority CPU notifier.
4552 static int workqueue_cpu_up_callback(struct notifier_block *nfb,
4553 unsigned long action,
4556 int cpu = (unsigned long)hcpu;
4557 struct worker_pool *pool;
4558 struct workqueue_struct *wq;
4561 switch (action & ~CPU_TASKS_FROZEN) {
4562 case CPU_UP_PREPARE:
4563 for_each_cpu_worker_pool(pool, cpu) {
4564 if (pool->nr_workers)
4566 if (!create_worker(pool))
4571 case CPU_DOWN_FAILED:
4573 mutex_lock(&wq_pool_mutex);
4575 for_each_pool(pool, pi) {
4576 mutex_lock(&pool->attach_mutex);
4578 if (pool->cpu == cpu)
4579 rebind_workers(pool);
4580 else if (pool->cpu < 0)
4581 restore_unbound_workers_cpumask(pool, cpu);
4583 mutex_unlock(&pool->attach_mutex);
4586 /* update NUMA affinity of unbound workqueues */
4587 list_for_each_entry(wq, &workqueues, list)
4588 wq_update_unbound_numa(wq, cpu, true);
4590 mutex_unlock(&wq_pool_mutex);
4597 * Workqueues should be brought down after normal priority CPU notifiers.
4598 * This will be registered as low priority CPU notifier.
4600 static int workqueue_cpu_down_callback(struct notifier_block *nfb,
4601 unsigned long action,
4604 int cpu = (unsigned long)hcpu;
4605 struct work_struct unbind_work;
4606 struct workqueue_struct *wq;
4608 switch (action & ~CPU_TASKS_FROZEN) {
4609 case CPU_DOWN_PREPARE:
4610 /* unbinding per-cpu workers should happen on the local CPU */
4611 INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
4612 queue_work_on(cpu, system_highpri_wq, &unbind_work);
4614 /* update NUMA affinity of unbound workqueues */
4615 mutex_lock(&wq_pool_mutex);
4616 list_for_each_entry(wq, &workqueues, list)
4617 wq_update_unbound_numa(wq, cpu, false);
4618 mutex_unlock(&wq_pool_mutex);
4620 /* wait for per-cpu unbinding to finish */
4621 flush_work(&unbind_work);
4622 destroy_work_on_stack(&unbind_work);
4630 struct work_for_cpu {
4631 struct work_struct work;
4637 static void work_for_cpu_fn(struct work_struct *work)
4639 struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
4641 wfc->ret = wfc->fn(wfc->arg);
4645 * work_on_cpu - run a function in user context on a particular cpu
4646 * @cpu: the cpu to run on
4647 * @fn: the function to run
4648 * @arg: the function arg
4650 * It is up to the caller to ensure that the cpu doesn't go offline.
4651 * The caller must not hold any locks which would prevent @fn from completing.
4653 * Return: The value @fn returns.
4655 long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
4657 struct work_for_cpu wfc = { .fn = fn, .arg = arg };
4659 INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
4660 schedule_work_on(cpu, &wfc.work);
4661 flush_work(&wfc.work);
4662 destroy_work_on_stack(&wfc.work);
4665 EXPORT_SYMBOL_GPL(work_on_cpu);
4666 #endif /* CONFIG_SMP */
4668 #ifdef CONFIG_FREEZER
4671 * freeze_workqueues_begin - begin freezing workqueues
4673 * Start freezing workqueues. After this function returns, all freezable
4674 * workqueues will queue new works to their delayed_works list instead of
4678 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4680 void freeze_workqueues_begin(void)
4682 struct workqueue_struct *wq;
4683 struct pool_workqueue *pwq;
4685 mutex_lock(&wq_pool_mutex);
4687 WARN_ON_ONCE(workqueue_freezing);
4688 workqueue_freezing = true;
4690 list_for_each_entry(wq, &workqueues, list) {
4691 mutex_lock(&wq->mutex);
4692 for_each_pwq(pwq, wq)
4693 pwq_adjust_max_active(pwq);
4694 mutex_unlock(&wq->mutex);
4697 mutex_unlock(&wq_pool_mutex);
4701 * freeze_workqueues_busy - are freezable workqueues still busy?
4703 * Check whether freezing is complete. This function must be called
4704 * between freeze_workqueues_begin() and thaw_workqueues().
4707 * Grabs and releases wq_pool_mutex.
4710 * %true if some freezable workqueues are still busy. %false if freezing
4713 bool freeze_workqueues_busy(void)
4716 struct workqueue_struct *wq;
4717 struct pool_workqueue *pwq;
4719 mutex_lock(&wq_pool_mutex);
4721 WARN_ON_ONCE(!workqueue_freezing);
4723 list_for_each_entry(wq, &workqueues, list) {
4724 if (!(wq->flags & WQ_FREEZABLE))
4727 * nr_active is monotonically decreasing. It's safe
4728 * to peek without lock.
4730 rcu_read_lock_sched();
4731 for_each_pwq(pwq, wq) {
4732 WARN_ON_ONCE(pwq->nr_active < 0);
4733 if (pwq->nr_active) {
4735 rcu_read_unlock_sched();
4739 rcu_read_unlock_sched();
4742 mutex_unlock(&wq_pool_mutex);
4747 * thaw_workqueues - thaw workqueues
4749 * Thaw workqueues. Normal queueing is restored and all collected
4750 * frozen works are transferred to their respective pool worklists.
4753 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4755 void thaw_workqueues(void)
4757 struct workqueue_struct *wq;
4758 struct pool_workqueue *pwq;
4760 mutex_lock(&wq_pool_mutex);
4762 if (!workqueue_freezing)
4765 workqueue_freezing = false;
4767 /* restore max_active and repopulate worklist */
4768 list_for_each_entry(wq, &workqueues, list) {
4769 mutex_lock(&wq->mutex);
4770 for_each_pwq(pwq, wq)
4771 pwq_adjust_max_active(pwq);
4772 mutex_unlock(&wq->mutex);
4776 mutex_unlock(&wq_pool_mutex);
4778 #endif /* CONFIG_FREEZER */
4780 static void __init wq_numa_init(void)
4785 if (num_possible_nodes() <= 1)
4788 if (wq_disable_numa) {
4789 pr_info("workqueue: NUMA affinity support disabled\n");
4793 wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL);
4794 BUG_ON(!wq_update_unbound_numa_attrs_buf);
4797 * We want masks of possible CPUs of each node which isn't readily
4798 * available. Build one from cpu_to_node() which should have been
4799 * fully initialized by now.
4801 tbl = kzalloc(nr_node_ids * sizeof(tbl[0]), GFP_KERNEL);
4805 BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL,
4806 node_online(node) ? node : NUMA_NO_NODE));
4808 for_each_possible_cpu(cpu) {
4809 node = cpu_to_node(cpu);
4810 if (WARN_ON(node == NUMA_NO_NODE)) {
4811 pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
4812 /* happens iff arch is bonkers, let's just proceed */
4815 cpumask_set_cpu(cpu, tbl[node]);
4818 wq_numa_possible_cpumask = tbl;
4819 wq_numa_enabled = true;
4822 static int __init init_workqueues(void)
4824 int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
4827 WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
4829 pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
4831 cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
4832 hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
4836 /* initialize CPU pools */
4837 for_each_possible_cpu(cpu) {
4838 struct worker_pool *pool;
4841 for_each_cpu_worker_pool(pool, cpu) {
4842 BUG_ON(init_worker_pool(pool));
4844 cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
4845 pool->attrs->nice = std_nice[i++];
4846 pool->node = cpu_to_node(cpu);
4849 mutex_lock(&wq_pool_mutex);
4850 BUG_ON(worker_pool_assign_id(pool));
4851 mutex_unlock(&wq_pool_mutex);
4855 /* create the initial worker */
4856 for_each_online_cpu(cpu) {
4857 struct worker_pool *pool;
4859 for_each_cpu_worker_pool(pool, cpu) {
4860 pool->flags &= ~POOL_DISASSOCIATED;
4861 BUG_ON(!create_worker(pool));
4865 /* create default unbound and ordered wq attrs */
4866 for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
4867 struct workqueue_attrs *attrs;
4869 BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
4870 attrs->nice = std_nice[i];
4871 unbound_std_wq_attrs[i] = attrs;
4874 * An ordered wq should have only one pwq as ordering is
4875 * guaranteed by max_active which is enforced by pwqs.
4876 * Turn off NUMA so that dfl_pwq is used for all nodes.
4878 BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
4879 attrs->nice = std_nice[i];
4880 attrs->no_numa = true;
4881 ordered_wq_attrs[i] = attrs;
4884 system_wq = alloc_workqueue("events", 0, 0);
4885 system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
4886 system_long_wq = alloc_workqueue("events_long", 0, 0);
4887 system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
4888 WQ_UNBOUND_MAX_ACTIVE);
4889 system_freezable_wq = alloc_workqueue("events_freezable",
4891 system_power_efficient_wq = alloc_workqueue("events_power_efficient",
4892 WQ_POWER_EFFICIENT, 0);
4893 system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient",
4894 WQ_FREEZABLE | WQ_POWER_EFFICIENT,
4896 BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||
4897 !system_unbound_wq || !system_freezable_wq ||
4898 !system_power_efficient_wq ||
4899 !system_freezable_power_efficient_wq);
4902 early_initcall(init_workqueues);