2 * kernel/workqueue.c - generic async execution with shared worker pool
4 * Copyright (C) 2002 Ingo Molnar
6 * Derived from the taskqueue/keventd code by:
7 * David Woodhouse <dwmw2@infradead.org>
9 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
10 * Theodore Ts'o <tytso@mit.edu>
12 * Made to use alloc_percpu by Christoph Lameter.
14 * Copyright (C) 2010 SUSE Linux Products GmbH
15 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
17 * This is the generic async execution mechanism. Work items as are
18 * executed in process context. The worker pool is shared and
19 * automatically managed. There is one worker pool for each CPU and
20 * one extra for works which are better served by workers which are
21 * not bound to any specific CPU.
23 * Please read Documentation/workqueue.txt for details.
26 #include <linux/export.h>
27 #include <linux/kernel.h>
28 #include <linux/sched.h>
29 #include <linux/init.h>
30 #include <linux/signal.h>
31 #include <linux/completion.h>
32 #include <linux/workqueue.h>
33 #include <linux/slab.h>
34 #include <linux/cpu.h>
35 #include <linux/notifier.h>
36 #include <linux/kthread.h>
37 #include <linux/hardirq.h>
38 #include <linux/mempolicy.h>
39 #include <linux/freezer.h>
40 #include <linux/kallsyms.h>
41 #include <linux/debug_locks.h>
42 #include <linux/lockdep.h>
43 #include <linux/idr.h>
44 #include <linux/jhash.h>
45 #include <linux/hashtable.h>
46 #include <linux/rculist.h>
47 #include <linux/nodemask.h>
48 #include <linux/moduleparam.h>
50 #include "workqueue_internal.h"
56 * A bound pool is either associated or disassociated with its CPU.
57 * While associated (!DISASSOCIATED), all workers are bound to the
58 * CPU and none has %WORKER_UNBOUND set and concurrency management
61 * While DISASSOCIATED, the cpu may be offline and all workers have
62 * %WORKER_UNBOUND set and concurrency management disabled, and may
63 * be executing on any CPU. The pool behaves as an unbound one.
65 * Note that DISASSOCIATED should be flipped only while holding
66 * manager_mutex to avoid changing binding state while
67 * create_worker() is in progress.
69 POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
70 POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
71 POOL_FREEZING = 1 << 3, /* freeze in progress */
74 WORKER_STARTED = 1 << 0, /* started */
75 WORKER_DIE = 1 << 1, /* die die die */
76 WORKER_IDLE = 1 << 2, /* is idle */
77 WORKER_PREP = 1 << 3, /* preparing to run works */
78 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
79 WORKER_UNBOUND = 1 << 7, /* worker is unbound */
80 WORKER_REBOUND = 1 << 8, /* worker was rebound */
82 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE |
83 WORKER_UNBOUND | WORKER_REBOUND,
85 NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
87 UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
88 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
90 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
91 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
93 MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
94 /* call for help after 10ms
96 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
97 CREATE_COOLDOWN = HZ, /* time to breath after fail */
100 * Rescue workers are used only on emergencies and shared by
101 * all cpus. Give -20.
103 RESCUER_NICE_LEVEL = -20,
104 HIGHPRI_NICE_LEVEL = -20,
110 * Structure fields follow one of the following exclusion rules.
112 * I: Modifiable by initialization/destruction paths and read-only for
115 * P: Preemption protected. Disabling preemption is enough and should
116 * only be modified and accessed from the local cpu.
118 * L: pool->lock protected. Access with pool->lock held.
120 * X: During normal operation, modification requires pool->lock and should
121 * be done only from local cpu. Either disabling preemption on local
122 * cpu or grabbing pool->lock is enough for read access. If
123 * POOL_DISASSOCIATED is set, it's identical to L.
125 * MG: pool->manager_mutex and pool->lock protected. Writes require both
126 * locks. Reads can happen under either lock.
128 * PL: wq_pool_mutex protected.
130 * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
132 * WQ: wq->mutex protected.
134 * WR: wq->mutex protected for writes. Sched-RCU protected for reads.
136 * MD: wq_mayday_lock protected.
139 /* struct worker is defined in workqueue_internal.h */
142 spinlock_t lock; /* the pool lock */
143 int cpu; /* I: the associated cpu */
144 int node; /* I: the associated node ID */
145 int id; /* I: pool ID */
146 unsigned int flags; /* X: flags */
148 struct list_head worklist; /* L: list of pending works */
149 int nr_workers; /* L: total number of workers */
151 /* nr_idle includes the ones off idle_list for rebinding */
152 int nr_idle; /* L: currently idle ones */
154 struct list_head idle_list; /* X: list of idle workers */
155 struct timer_list idle_timer; /* L: worker idle timeout */
156 struct timer_list mayday_timer; /* L: SOS timer for workers */
158 /* a workers is either on busy_hash or idle_list, or the manager */
159 DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
160 /* L: hash of busy workers */
162 /* see manage_workers() for details on the two manager mutexes */
163 struct mutex manager_arb; /* manager arbitration */
164 struct mutex manager_mutex; /* manager exclusion */
165 struct idr worker_idr; /* MG: worker IDs and iteration */
167 struct workqueue_attrs *attrs; /* I: worker attributes */
168 struct hlist_node hash_node; /* PL: unbound_pool_hash node */
169 int refcnt; /* PL: refcnt for unbound pools */
172 * The current concurrency level. As it's likely to be accessed
173 * from other CPUs during try_to_wake_up(), put it in a separate
176 atomic_t nr_running ____cacheline_aligned_in_smp;
179 * Destruction of pool is sched-RCU protected to allow dereferences
180 * from get_work_pool().
183 } ____cacheline_aligned_in_smp;
186 * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
187 * of work_struct->data are used for flags and the remaining high bits
188 * point to the pwq; thus, pwqs need to be aligned at two's power of the
189 * number of flag bits.
191 struct pool_workqueue {
192 struct worker_pool *pool; /* I: the associated pool */
193 struct workqueue_struct *wq; /* I: the owning workqueue */
194 int work_color; /* L: current color */
195 int flush_color; /* L: flushing color */
196 int refcnt; /* L: reference count */
197 int nr_in_flight[WORK_NR_COLORS];
198 /* L: nr of in_flight works */
199 int nr_active; /* L: nr of active works */
200 int max_active; /* L: max active works */
201 struct list_head delayed_works; /* L: delayed works */
202 struct list_head pwqs_node; /* WR: node on wq->pwqs */
203 struct list_head mayday_node; /* MD: node on wq->maydays */
206 * Release of unbound pwq is punted to system_wq. See put_pwq()
207 * and pwq_unbound_release_workfn() for details. pool_workqueue
208 * itself is also sched-RCU protected so that the first pwq can be
209 * determined without grabbing wq->mutex.
211 struct work_struct unbound_release_work;
213 } __aligned(1 << WORK_STRUCT_FLAG_BITS);
216 * Structure used to wait for workqueue flush.
219 struct list_head list; /* WQ: list of flushers */
220 int flush_color; /* WQ: flush color waiting for */
221 struct completion done; /* flush completion */
227 * The externally visible workqueue. It relays the issued work items to
228 * the appropriate worker_pool through its pool_workqueues.
230 struct workqueue_struct {
231 struct list_head pwqs; /* WR: all pwqs of this wq */
232 struct list_head list; /* PL: list of all workqueues */
234 struct mutex mutex; /* protects this wq */
235 int work_color; /* WQ: current work color */
236 int flush_color; /* WQ: current flush color */
237 atomic_t nr_pwqs_to_flush; /* flush in progress */
238 struct wq_flusher *first_flusher; /* WQ: first flusher */
239 struct list_head flusher_queue; /* WQ: flush waiters */
240 struct list_head flusher_overflow; /* WQ: flush overflow list */
242 struct list_head maydays; /* MD: pwqs requesting rescue */
243 struct worker *rescuer; /* I: rescue worker */
245 int nr_drainers; /* WQ: drain in progress */
246 int saved_max_active; /* WQ: saved pwq max_active */
248 struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */
249 struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */
252 struct wq_device *wq_dev; /* I: for sysfs interface */
254 #ifdef CONFIG_LOCKDEP
255 struct lockdep_map lockdep_map;
257 char name[WQ_NAME_LEN]; /* I: workqueue name */
259 /* hot fields used during command issue, aligned to cacheline */
260 unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
261 struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */
262 struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */
265 static struct kmem_cache *pwq_cache;
267 static int wq_numa_tbl_len; /* highest possible NUMA node id + 1 */
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 static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
276 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
277 static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
279 static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
280 static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
282 static LIST_HEAD(workqueues); /* PL: list of all workqueues */
283 static bool workqueue_freezing; /* PL: have wqs started freezing? */
285 /* the per-cpu worker pools */
286 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
289 static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
291 /* PL: hash of all unbound pools keyed by pool->attrs */
292 static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
294 /* I: attributes used when instantiating standard unbound pools on demand */
295 static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
297 struct workqueue_struct *system_wq __read_mostly;
298 EXPORT_SYMBOL_GPL(system_wq);
299 struct workqueue_struct *system_highpri_wq __read_mostly;
300 EXPORT_SYMBOL_GPL(system_highpri_wq);
301 struct workqueue_struct *system_long_wq __read_mostly;
302 EXPORT_SYMBOL_GPL(system_long_wq);
303 struct workqueue_struct *system_unbound_wq __read_mostly;
304 EXPORT_SYMBOL_GPL(system_unbound_wq);
305 struct workqueue_struct *system_freezable_wq __read_mostly;
306 EXPORT_SYMBOL_GPL(system_freezable_wq);
308 static int worker_thread(void *__worker);
309 static void copy_workqueue_attrs(struct workqueue_attrs *to,
310 const struct workqueue_attrs *from);
312 #define CREATE_TRACE_POINTS
313 #include <trace/events/workqueue.h>
315 #define assert_rcu_or_pool_mutex() \
316 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
317 lockdep_is_held(&wq_pool_mutex), \
318 "sched RCU or wq_pool_mutex should be held")
320 #define assert_rcu_or_wq_mutex(wq) \
321 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
322 lockdep_is_held(&wq->mutex), \
323 "sched RCU or wq->mutex should be held")
325 #ifdef CONFIG_LOCKDEP
326 #define assert_manager_or_pool_lock(pool) \
327 WARN_ONCE(debug_locks && \
328 !lockdep_is_held(&(pool)->manager_mutex) && \
329 !lockdep_is_held(&(pool)->lock), \
330 "pool->manager_mutex or ->lock should be held")
332 #define assert_manager_or_pool_lock(pool) do { } while (0)
335 #define for_each_cpu_worker_pool(pool, cpu) \
336 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
337 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
341 * for_each_pool - iterate through all worker_pools in the system
342 * @pool: iteration cursor
343 * @pi: integer used for iteration
345 * This must be called either with wq_pool_mutex held or sched RCU read
346 * locked. If the pool needs to be used beyond the locking in effect, the
347 * caller is responsible for guaranteeing that the pool stays online.
349 * The if/else clause exists only for the lockdep assertion and can be
352 #define for_each_pool(pool, pi) \
353 idr_for_each_entry(&worker_pool_idr, pool, pi) \
354 if (({ assert_rcu_or_pool_mutex(); false; })) { } \
358 * for_each_pool_worker - iterate through all workers of a worker_pool
359 * @worker: iteration cursor
360 * @wi: integer used for iteration
361 * @pool: worker_pool to iterate workers of
363 * This must be called with either @pool->manager_mutex or ->lock held.
365 * The if/else clause exists only for the lockdep assertion and can be
368 #define for_each_pool_worker(worker, wi, pool) \
369 idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \
370 if (({ assert_manager_or_pool_lock((pool)); false; })) { } \
374 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
375 * @pwq: iteration cursor
376 * @wq: the target workqueue
378 * This must be called either with wq->mutex held or sched RCU read locked.
379 * If the pwq needs to be used beyond the locking in effect, the caller is
380 * responsible for guaranteeing that the pwq stays online.
382 * The if/else clause exists only for the lockdep assertion and can be
385 #define for_each_pwq(pwq, wq) \
386 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
387 if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
390 #ifdef CONFIG_DEBUG_OBJECTS_WORK
392 static struct debug_obj_descr work_debug_descr;
394 static void *work_debug_hint(void *addr)
396 return ((struct work_struct *) addr)->func;
400 * fixup_init is called when:
401 * - an active object is initialized
403 static int work_fixup_init(void *addr, enum debug_obj_state state)
405 struct work_struct *work = addr;
408 case ODEBUG_STATE_ACTIVE:
409 cancel_work_sync(work);
410 debug_object_init(work, &work_debug_descr);
418 * fixup_activate is called when:
419 * - an active object is activated
420 * - an unknown object is activated (might be a statically initialized object)
422 static int work_fixup_activate(void *addr, enum debug_obj_state state)
424 struct work_struct *work = addr;
428 case ODEBUG_STATE_NOTAVAILABLE:
430 * This is not really a fixup. The work struct was
431 * statically initialized. We just make sure that it
432 * is tracked in the object tracker.
434 if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
435 debug_object_init(work, &work_debug_descr);
436 debug_object_activate(work, &work_debug_descr);
442 case ODEBUG_STATE_ACTIVE:
451 * fixup_free is called when:
452 * - an active object is freed
454 static int work_fixup_free(void *addr, enum debug_obj_state state)
456 struct work_struct *work = addr;
459 case ODEBUG_STATE_ACTIVE:
460 cancel_work_sync(work);
461 debug_object_free(work, &work_debug_descr);
468 static struct debug_obj_descr work_debug_descr = {
469 .name = "work_struct",
470 .debug_hint = work_debug_hint,
471 .fixup_init = work_fixup_init,
472 .fixup_activate = work_fixup_activate,
473 .fixup_free = work_fixup_free,
476 static inline void debug_work_activate(struct work_struct *work)
478 debug_object_activate(work, &work_debug_descr);
481 static inline void debug_work_deactivate(struct work_struct *work)
483 debug_object_deactivate(work, &work_debug_descr);
486 void __init_work(struct work_struct *work, int onstack)
489 debug_object_init_on_stack(work, &work_debug_descr);
491 debug_object_init(work, &work_debug_descr);
493 EXPORT_SYMBOL_GPL(__init_work);
495 void destroy_work_on_stack(struct work_struct *work)
497 debug_object_free(work, &work_debug_descr);
499 EXPORT_SYMBOL_GPL(destroy_work_on_stack);
502 static inline void debug_work_activate(struct work_struct *work) { }
503 static inline void debug_work_deactivate(struct work_struct *work) { }
506 /* allocate ID and assign it to @pool */
507 static int worker_pool_assign_id(struct worker_pool *pool)
511 lockdep_assert_held(&wq_pool_mutex);
514 if (!idr_pre_get(&worker_pool_idr, GFP_KERNEL))
516 ret = idr_get_new(&worker_pool_idr, pool, &pool->id);
517 } while (ret == -EAGAIN);
523 * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
524 * @wq: the target workqueue
527 * This must be called either with pwq_lock held or sched RCU read locked.
528 * If the pwq needs to be used beyond the locking in effect, the caller is
529 * responsible for guaranteeing that the pwq stays online.
531 static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq,
534 assert_rcu_or_wq_mutex(wq);
535 return rcu_dereference_raw(wq->numa_pwq_tbl[node]);
538 static unsigned int work_color_to_flags(int color)
540 return color << WORK_STRUCT_COLOR_SHIFT;
543 static int get_work_color(struct work_struct *work)
545 return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
546 ((1 << WORK_STRUCT_COLOR_BITS) - 1);
549 static int work_next_color(int color)
551 return (color + 1) % WORK_NR_COLORS;
555 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
556 * contain the pointer to the queued pwq. Once execution starts, the flag
557 * is cleared and the high bits contain OFFQ flags and pool ID.
559 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
560 * and clear_work_data() can be used to set the pwq, pool or clear
561 * work->data. These functions should only be called while the work is
562 * owned - ie. while the PENDING bit is set.
564 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
565 * corresponding to a work. Pool is available once the work has been
566 * queued anywhere after initialization until it is sync canceled. pwq is
567 * available only while the work item is queued.
569 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
570 * canceled. While being canceled, a work item may have its PENDING set
571 * but stay off timer and worklist for arbitrarily long and nobody should
572 * try to steal the PENDING bit.
574 static inline void set_work_data(struct work_struct *work, unsigned long data,
577 WARN_ON_ONCE(!work_pending(work));
578 atomic_long_set(&work->data, data | flags | work_static(work));
581 static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq,
582 unsigned long extra_flags)
584 set_work_data(work, (unsigned long)pwq,
585 WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags);
588 static void set_work_pool_and_keep_pending(struct work_struct *work,
591 set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
592 WORK_STRUCT_PENDING);
595 static void set_work_pool_and_clear_pending(struct work_struct *work,
599 * The following wmb is paired with the implied mb in
600 * test_and_set_bit(PENDING) and ensures all updates to @work made
601 * here are visible to and precede any updates by the next PENDING
605 set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
608 static void clear_work_data(struct work_struct *work)
610 smp_wmb(); /* see set_work_pool_and_clear_pending() */
611 set_work_data(work, WORK_STRUCT_NO_POOL, 0);
614 static struct pool_workqueue *get_work_pwq(struct work_struct *work)
616 unsigned long data = atomic_long_read(&work->data);
618 if (data & WORK_STRUCT_PWQ)
619 return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
625 * get_work_pool - return the worker_pool a given work was associated with
626 * @work: the work item of interest
628 * Return the worker_pool @work was last associated with. %NULL if none.
630 * Pools are created and destroyed under wq_pool_mutex, and allows read
631 * access under sched-RCU read lock. As such, this function should be
632 * called under wq_pool_mutex or with preemption disabled.
634 * All fields of the returned pool are accessible as long as the above
635 * mentioned locking is in effect. If the returned pool needs to be used
636 * beyond the critical section, the caller is responsible for ensuring the
637 * returned pool is and stays online.
639 static struct worker_pool *get_work_pool(struct work_struct *work)
641 unsigned long data = atomic_long_read(&work->data);
644 assert_rcu_or_pool_mutex();
646 if (data & WORK_STRUCT_PWQ)
647 return ((struct pool_workqueue *)
648 (data & WORK_STRUCT_WQ_DATA_MASK))->pool;
650 pool_id = data >> WORK_OFFQ_POOL_SHIFT;
651 if (pool_id == WORK_OFFQ_POOL_NONE)
654 return idr_find(&worker_pool_idr, pool_id);
658 * get_work_pool_id - return the worker pool ID a given work is associated with
659 * @work: the work item of interest
661 * Return the worker_pool ID @work was last associated with.
662 * %WORK_OFFQ_POOL_NONE if none.
664 static int get_work_pool_id(struct work_struct *work)
666 unsigned long data = atomic_long_read(&work->data);
668 if (data & WORK_STRUCT_PWQ)
669 return ((struct pool_workqueue *)
670 (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
672 return data >> WORK_OFFQ_POOL_SHIFT;
675 static void mark_work_canceling(struct work_struct *work)
677 unsigned long pool_id = get_work_pool_id(work);
679 pool_id <<= WORK_OFFQ_POOL_SHIFT;
680 set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
683 static bool work_is_canceling(struct work_struct *work)
685 unsigned long data = atomic_long_read(&work->data);
687 return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
691 * Policy functions. These define the policies on how the global worker
692 * pools are managed. Unless noted otherwise, these functions assume that
693 * they're being called with pool->lock held.
696 static bool __need_more_worker(struct worker_pool *pool)
698 return !atomic_read(&pool->nr_running);
702 * Need to wake up a worker? Called from anything but currently
705 * Note that, because unbound workers never contribute to nr_running, this
706 * function will always return %true for unbound pools as long as the
707 * worklist isn't empty.
709 static bool need_more_worker(struct worker_pool *pool)
711 return !list_empty(&pool->worklist) && __need_more_worker(pool);
714 /* Can I start working? Called from busy but !running workers. */
715 static bool may_start_working(struct worker_pool *pool)
717 return pool->nr_idle;
720 /* Do I need to keep working? Called from currently running workers. */
721 static bool keep_working(struct worker_pool *pool)
723 return !list_empty(&pool->worklist) &&
724 atomic_read(&pool->nr_running) <= 1;
727 /* Do we need a new worker? Called from manager. */
728 static bool need_to_create_worker(struct worker_pool *pool)
730 return need_more_worker(pool) && !may_start_working(pool);
733 /* Do I need to be the manager? */
734 static bool need_to_manage_workers(struct worker_pool *pool)
736 return need_to_create_worker(pool) ||
737 (pool->flags & POOL_MANAGE_WORKERS);
740 /* Do we have too many workers and should some go away? */
741 static bool too_many_workers(struct worker_pool *pool)
743 bool managing = mutex_is_locked(&pool->manager_arb);
744 int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
745 int nr_busy = pool->nr_workers - nr_idle;
748 * nr_idle and idle_list may disagree if idle rebinding is in
749 * progress. Never return %true if idle_list is empty.
751 if (list_empty(&pool->idle_list))
754 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
761 /* Return the first worker. Safe with preemption disabled */
762 static struct worker *first_worker(struct worker_pool *pool)
764 if (unlikely(list_empty(&pool->idle_list)))
767 return list_first_entry(&pool->idle_list, struct worker, entry);
771 * wake_up_worker - wake up an idle worker
772 * @pool: worker pool to wake worker from
774 * Wake up the first idle worker of @pool.
777 * spin_lock_irq(pool->lock).
779 static void wake_up_worker(struct worker_pool *pool)
781 struct worker *worker = first_worker(pool);
784 wake_up_process(worker->task);
788 * wq_worker_waking_up - a worker is waking up
789 * @task: task waking up
790 * @cpu: CPU @task is waking up to
792 * This function is called during try_to_wake_up() when a worker is
796 * spin_lock_irq(rq->lock)
798 void wq_worker_waking_up(struct task_struct *task, int cpu)
800 struct worker *worker = kthread_data(task);
802 if (!(worker->flags & WORKER_NOT_RUNNING)) {
803 WARN_ON_ONCE(worker->pool->cpu != cpu);
804 atomic_inc(&worker->pool->nr_running);
809 * wq_worker_sleeping - a worker is going to sleep
810 * @task: task going to sleep
811 * @cpu: CPU in question, must be the current CPU number
813 * This function is called during schedule() when a busy worker is
814 * going to sleep. Worker on the same cpu can be woken up by
815 * returning pointer to its task.
818 * spin_lock_irq(rq->lock)
821 * Worker task on @cpu to wake up, %NULL if none.
823 struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu)
825 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
826 struct worker_pool *pool;
829 * Rescuers, which may not have all the fields set up like normal
830 * workers, also reach here, let's not access anything before
831 * checking NOT_RUNNING.
833 if (worker->flags & WORKER_NOT_RUNNING)
838 /* this can only happen on the local cpu */
839 if (WARN_ON_ONCE(cpu != raw_smp_processor_id()))
843 * The counterpart of the following dec_and_test, implied mb,
844 * worklist not empty test sequence is in insert_work().
845 * Please read comment there.
847 * NOT_RUNNING is clear. This means that we're bound to and
848 * running on the local cpu w/ rq lock held and preemption
849 * disabled, which in turn means that none else could be
850 * manipulating idle_list, so dereferencing idle_list without pool
853 if (atomic_dec_and_test(&pool->nr_running) &&
854 !list_empty(&pool->worklist))
855 to_wakeup = first_worker(pool);
856 return to_wakeup ? to_wakeup->task : NULL;
860 * worker_set_flags - set worker flags and adjust nr_running accordingly
862 * @flags: flags to set
863 * @wakeup: wakeup an idle worker if necessary
865 * Set @flags in @worker->flags and adjust nr_running accordingly. If
866 * nr_running becomes zero and @wakeup is %true, an idle worker is
870 * spin_lock_irq(pool->lock)
872 static inline void worker_set_flags(struct worker *worker, unsigned int flags,
875 struct worker_pool *pool = worker->pool;
877 WARN_ON_ONCE(worker->task != current);
880 * If transitioning into NOT_RUNNING, adjust nr_running and
881 * wake up an idle worker as necessary if requested by
884 if ((flags & WORKER_NOT_RUNNING) &&
885 !(worker->flags & WORKER_NOT_RUNNING)) {
887 if (atomic_dec_and_test(&pool->nr_running) &&
888 !list_empty(&pool->worklist))
889 wake_up_worker(pool);
891 atomic_dec(&pool->nr_running);
894 worker->flags |= flags;
898 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
900 * @flags: flags to clear
902 * Clear @flags in @worker->flags and adjust nr_running accordingly.
905 * spin_lock_irq(pool->lock)
907 static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
909 struct worker_pool *pool = worker->pool;
910 unsigned int oflags = worker->flags;
912 WARN_ON_ONCE(worker->task != current);
914 worker->flags &= ~flags;
917 * If transitioning out of NOT_RUNNING, increment nr_running. Note
918 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
919 * of multiple flags, not a single flag.
921 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
922 if (!(worker->flags & WORKER_NOT_RUNNING))
923 atomic_inc(&pool->nr_running);
927 * find_worker_executing_work - find worker which is executing a work
928 * @pool: pool of interest
929 * @work: work to find worker for
931 * Find a worker which is executing @work on @pool by searching
932 * @pool->busy_hash which is keyed by the address of @work. For a worker
933 * to match, its current execution should match the address of @work and
934 * its work function. This is to avoid unwanted dependency between
935 * unrelated work executions through a work item being recycled while still
938 * This is a bit tricky. A work item may be freed once its execution
939 * starts and nothing prevents the freed area from being recycled for
940 * another work item. If the same work item address ends up being reused
941 * before the original execution finishes, workqueue will identify the
942 * recycled work item as currently executing and make it wait until the
943 * current execution finishes, introducing an unwanted dependency.
945 * This function checks the work item address and work function to avoid
946 * false positives. Note that this isn't complete as one may construct a
947 * work function which can introduce dependency onto itself through a
948 * recycled work item. Well, if somebody wants to shoot oneself in the
949 * foot that badly, there's only so much we can do, and if such deadlock
950 * actually occurs, it should be easy to locate the culprit work function.
953 * spin_lock_irq(pool->lock).
956 * Pointer to worker which is executing @work if found, NULL
959 static struct worker *find_worker_executing_work(struct worker_pool *pool,
960 struct work_struct *work)
962 struct worker *worker;
964 hash_for_each_possible(pool->busy_hash, worker, hentry,
966 if (worker->current_work == work &&
967 worker->current_func == work->func)
974 * move_linked_works - move linked works to a list
975 * @work: start of series of works to be scheduled
976 * @head: target list to append @work to
977 * @nextp: out paramter for nested worklist walking
979 * Schedule linked works starting from @work to @head. Work series to
980 * be scheduled starts at @work and includes any consecutive work with
981 * WORK_STRUCT_LINKED set in its predecessor.
983 * If @nextp is not NULL, it's updated to point to the next work of
984 * the last scheduled work. This allows move_linked_works() to be
985 * nested inside outer list_for_each_entry_safe().
988 * spin_lock_irq(pool->lock).
990 static void move_linked_works(struct work_struct *work, struct list_head *head,
991 struct work_struct **nextp)
993 struct work_struct *n;
996 * Linked worklist will always end before the end of the list,
997 * use NULL for list head.
999 list_for_each_entry_safe_from(work, n, NULL, entry) {
1000 list_move_tail(&work->entry, head);
1001 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1006 * If we're already inside safe list traversal and have moved
1007 * multiple works to the scheduled queue, the next position
1008 * needs to be updated.
1015 * get_pwq - get an extra reference on the specified pool_workqueue
1016 * @pwq: pool_workqueue to get
1018 * Obtain an extra reference on @pwq. The caller should guarantee that
1019 * @pwq has positive refcnt and be holding the matching pool->lock.
1021 static void get_pwq(struct pool_workqueue *pwq)
1023 lockdep_assert_held(&pwq->pool->lock);
1024 WARN_ON_ONCE(pwq->refcnt <= 0);
1029 * put_pwq - put a pool_workqueue reference
1030 * @pwq: pool_workqueue to put
1032 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1033 * destruction. The caller should be holding the matching pool->lock.
1035 static void put_pwq(struct pool_workqueue *pwq)
1037 lockdep_assert_held(&pwq->pool->lock);
1038 if (likely(--pwq->refcnt))
1040 if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND)))
1043 * @pwq can't be released under pool->lock, bounce to
1044 * pwq_unbound_release_workfn(). This never recurses on the same
1045 * pool->lock as this path is taken only for unbound workqueues and
1046 * the release work item is scheduled on a per-cpu workqueue. To
1047 * avoid lockdep warning, unbound pool->locks are given lockdep
1048 * subclass of 1 in get_unbound_pool().
1050 schedule_work(&pwq->unbound_release_work);
1054 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1055 * @pwq: pool_workqueue to put (can be %NULL)
1057 * put_pwq() with locking. This function also allows %NULL @pwq.
1059 static void put_pwq_unlocked(struct pool_workqueue *pwq)
1063 * As both pwqs and pools are sched-RCU protected, the
1064 * following lock operations are safe.
1066 spin_lock_irq(&pwq->pool->lock);
1068 spin_unlock_irq(&pwq->pool->lock);
1072 static void pwq_activate_delayed_work(struct work_struct *work)
1074 struct pool_workqueue *pwq = get_work_pwq(work);
1076 trace_workqueue_activate_work(work);
1077 move_linked_works(work, &pwq->pool->worklist, NULL);
1078 __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
1082 static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
1084 struct work_struct *work = list_first_entry(&pwq->delayed_works,
1085 struct work_struct, entry);
1087 pwq_activate_delayed_work(work);
1091 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1092 * @pwq: pwq of interest
1093 * @color: color of work which left the queue
1095 * A work either has completed or is removed from pending queue,
1096 * decrement nr_in_flight of its pwq and handle workqueue flushing.
1099 * spin_lock_irq(pool->lock).
1101 static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
1103 /* uncolored work items don't participate in flushing or nr_active */
1104 if (color == WORK_NO_COLOR)
1107 pwq->nr_in_flight[color]--;
1110 if (!list_empty(&pwq->delayed_works)) {
1111 /* one down, submit a delayed one */
1112 if (pwq->nr_active < pwq->max_active)
1113 pwq_activate_first_delayed(pwq);
1116 /* is flush in progress and are we at the flushing tip? */
1117 if (likely(pwq->flush_color != color))
1120 /* are there still in-flight works? */
1121 if (pwq->nr_in_flight[color])
1124 /* this pwq is done, clear flush_color */
1125 pwq->flush_color = -1;
1128 * If this was the last pwq, wake up the first flusher. It
1129 * will handle the rest.
1131 if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
1132 complete(&pwq->wq->first_flusher->done);
1138 * try_to_grab_pending - steal work item from worklist and disable irq
1139 * @work: work item to steal
1140 * @is_dwork: @work is a delayed_work
1141 * @flags: place to store irq state
1143 * Try to grab PENDING bit of @work. This function can handle @work in any
1144 * stable state - idle, on timer or on worklist. Return values are
1146 * 1 if @work was pending and we successfully stole PENDING
1147 * 0 if @work was idle and we claimed PENDING
1148 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1149 * -ENOENT if someone else is canceling @work, this state may persist
1150 * for arbitrarily long
1152 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1153 * interrupted while holding PENDING and @work off queue, irq must be
1154 * disabled on entry. This, combined with delayed_work->timer being
1155 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1157 * On successful return, >= 0, irq is disabled and the caller is
1158 * responsible for releasing it using local_irq_restore(*@flags).
1160 * This function is safe to call from any context including IRQ handler.
1162 static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
1163 unsigned long *flags)
1165 struct worker_pool *pool;
1166 struct pool_workqueue *pwq;
1168 local_irq_save(*flags);
1170 /* try to steal the timer if it exists */
1172 struct delayed_work *dwork = to_delayed_work(work);
1175 * dwork->timer is irqsafe. If del_timer() fails, it's
1176 * guaranteed that the timer is not queued anywhere and not
1177 * running on the local CPU.
1179 if (likely(del_timer(&dwork->timer)))
1183 /* try to claim PENDING the normal way */
1184 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
1188 * The queueing is in progress, or it is already queued. Try to
1189 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1191 pool = get_work_pool(work);
1195 spin_lock(&pool->lock);
1197 * work->data is guaranteed to point to pwq only while the work
1198 * item is queued on pwq->wq, and both updating work->data to point
1199 * to pwq on queueing and to pool on dequeueing are done under
1200 * pwq->pool->lock. This in turn guarantees that, if work->data
1201 * points to pwq which is associated with a locked pool, the work
1202 * item is currently queued on that pool.
1204 pwq = get_work_pwq(work);
1205 if (pwq && pwq->pool == pool) {
1206 debug_work_deactivate(work);
1209 * A delayed work item cannot be grabbed directly because
1210 * it might have linked NO_COLOR work items which, if left
1211 * on the delayed_list, will confuse pwq->nr_active
1212 * management later on and cause stall. Make sure the work
1213 * item is activated before grabbing.
1215 if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
1216 pwq_activate_delayed_work(work);
1218 list_del_init(&work->entry);
1219 pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work));
1221 /* work->data points to pwq iff queued, point to pool */
1222 set_work_pool_and_keep_pending(work, pool->id);
1224 spin_unlock(&pool->lock);
1227 spin_unlock(&pool->lock);
1229 local_irq_restore(*flags);
1230 if (work_is_canceling(work))
1237 * insert_work - insert a work into a pool
1238 * @pwq: pwq @work belongs to
1239 * @work: work to insert
1240 * @head: insertion point
1241 * @extra_flags: extra WORK_STRUCT_* flags to set
1243 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1244 * work_struct flags.
1247 * spin_lock_irq(pool->lock).
1249 static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
1250 struct list_head *head, unsigned int extra_flags)
1252 struct worker_pool *pool = pwq->pool;
1254 /* we own @work, set data and link */
1255 set_work_pwq(work, pwq, extra_flags);
1256 list_add_tail(&work->entry, head);
1260 * Ensure either wq_worker_sleeping() sees the above
1261 * list_add_tail() or we see zero nr_running to avoid workers lying
1262 * around lazily while there are works to be processed.
1266 if (__need_more_worker(pool))
1267 wake_up_worker(pool);
1271 * Test whether @work is being queued from another work executing on the
1274 static bool is_chained_work(struct workqueue_struct *wq)
1276 struct worker *worker;
1278 worker = current_wq_worker();
1280 * Return %true iff I'm a worker execuing a work item on @wq. If
1281 * I'm @worker, it's safe to dereference it without locking.
1283 return worker && worker->current_pwq->wq == wq;
1286 static void __queue_work(int cpu, struct workqueue_struct *wq,
1287 struct work_struct *work)
1289 struct pool_workqueue *pwq;
1290 struct worker_pool *last_pool;
1291 struct list_head *worklist;
1292 unsigned int work_flags;
1293 unsigned int req_cpu = cpu;
1296 * While a work item is PENDING && off queue, a task trying to
1297 * steal the PENDING will busy-loop waiting for it to either get
1298 * queued or lose PENDING. Grabbing PENDING and queueing should
1299 * happen with IRQ disabled.
1301 WARN_ON_ONCE(!irqs_disabled());
1303 debug_work_activate(work);
1305 /* if dying, only works from the same workqueue are allowed */
1306 if (unlikely(wq->flags & __WQ_DRAINING) &&
1307 WARN_ON_ONCE(!is_chained_work(wq)))
1310 if (req_cpu == WORK_CPU_UNBOUND)
1311 cpu = raw_smp_processor_id();
1313 /* pwq which will be used unless @work is executing elsewhere */
1314 if (!(wq->flags & WQ_UNBOUND))
1315 pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
1317 pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
1320 * If @work was previously on a different pool, it might still be
1321 * running there, in which case the work needs to be queued on that
1322 * pool to guarantee non-reentrancy.
1324 last_pool = get_work_pool(work);
1325 if (last_pool && last_pool != pwq->pool) {
1326 struct worker *worker;
1328 spin_lock(&last_pool->lock);
1330 worker = find_worker_executing_work(last_pool, work);
1332 if (worker && worker->current_pwq->wq == wq) {
1333 pwq = worker->current_pwq;
1335 /* meh... not running there, queue here */
1336 spin_unlock(&last_pool->lock);
1337 spin_lock(&pwq->pool->lock);
1340 spin_lock(&pwq->pool->lock);
1344 * pwq is determined and locked. For unbound pools, we could have
1345 * raced with pwq release and it could already be dead. If its
1346 * refcnt is zero, repeat pwq selection. Note that pwqs never die
1347 * without another pwq replacing it in the numa_pwq_tbl or while
1348 * work items are executing on it, so the retrying is guaranteed to
1349 * make forward-progress.
1351 if (unlikely(!pwq->refcnt)) {
1352 if (wq->flags & WQ_UNBOUND) {
1353 spin_unlock(&pwq->pool->lock);
1358 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1362 /* pwq determined, queue */
1363 trace_workqueue_queue_work(req_cpu, pwq, work);
1365 if (WARN_ON(!list_empty(&work->entry))) {
1366 spin_unlock(&pwq->pool->lock);
1370 pwq->nr_in_flight[pwq->work_color]++;
1371 work_flags = work_color_to_flags(pwq->work_color);
1373 if (likely(pwq->nr_active < pwq->max_active)) {
1374 trace_workqueue_activate_work(work);
1376 worklist = &pwq->pool->worklist;
1378 work_flags |= WORK_STRUCT_DELAYED;
1379 worklist = &pwq->delayed_works;
1382 insert_work(pwq, work, worklist, work_flags);
1384 spin_unlock(&pwq->pool->lock);
1388 * queue_work_on - queue work on specific cpu
1389 * @cpu: CPU number to execute work on
1390 * @wq: workqueue to use
1391 * @work: work to queue
1393 * Returns %false if @work was already on a queue, %true otherwise.
1395 * We queue the work to a specific CPU, the caller must ensure it
1398 bool queue_work_on(int cpu, struct workqueue_struct *wq,
1399 struct work_struct *work)
1402 unsigned long flags;
1404 local_irq_save(flags);
1406 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1407 __queue_work(cpu, wq, work);
1411 local_irq_restore(flags);
1414 EXPORT_SYMBOL_GPL(queue_work_on);
1416 void delayed_work_timer_fn(unsigned long __data)
1418 struct delayed_work *dwork = (struct delayed_work *)__data;
1420 /* should have been called from irqsafe timer with irq already off */
1421 __queue_work(dwork->cpu, dwork->wq, &dwork->work);
1423 EXPORT_SYMBOL(delayed_work_timer_fn);
1425 static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
1426 struct delayed_work *dwork, unsigned long delay)
1428 struct timer_list *timer = &dwork->timer;
1429 struct work_struct *work = &dwork->work;
1431 WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
1432 timer->data != (unsigned long)dwork);
1433 WARN_ON_ONCE(timer_pending(timer));
1434 WARN_ON_ONCE(!list_empty(&work->entry));
1437 * If @delay is 0, queue @dwork->work immediately. This is for
1438 * both optimization and correctness. The earliest @timer can
1439 * expire is on the closest next tick and delayed_work users depend
1440 * on that there's no such delay when @delay is 0.
1443 __queue_work(cpu, wq, &dwork->work);
1447 timer_stats_timer_set_start_info(&dwork->timer);
1451 timer->expires = jiffies + delay;
1453 if (unlikely(cpu != WORK_CPU_UNBOUND))
1454 add_timer_on(timer, cpu);
1460 * queue_delayed_work_on - queue work on specific CPU after delay
1461 * @cpu: CPU number to execute work on
1462 * @wq: workqueue to use
1463 * @dwork: work to queue
1464 * @delay: number of jiffies to wait before queueing
1466 * Returns %false if @work was already on a queue, %true otherwise. If
1467 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1470 bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1471 struct delayed_work *dwork, unsigned long delay)
1473 struct work_struct *work = &dwork->work;
1475 unsigned long flags;
1477 /* read the comment in __queue_work() */
1478 local_irq_save(flags);
1480 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1481 __queue_delayed_work(cpu, wq, dwork, delay);
1485 local_irq_restore(flags);
1488 EXPORT_SYMBOL_GPL(queue_delayed_work_on);
1491 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1492 * @cpu: CPU number to execute work on
1493 * @wq: workqueue to use
1494 * @dwork: work to queue
1495 * @delay: number of jiffies to wait before queueing
1497 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1498 * modify @dwork's timer so that it expires after @delay. If @delay is
1499 * zero, @work is guaranteed to be scheduled immediately regardless of its
1502 * Returns %false if @dwork was idle and queued, %true if @dwork was
1503 * pending and its timer was modified.
1505 * This function is safe to call from any context including IRQ handler.
1506 * See try_to_grab_pending() for details.
1508 bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
1509 struct delayed_work *dwork, unsigned long delay)
1511 unsigned long flags;
1515 ret = try_to_grab_pending(&dwork->work, true, &flags);
1516 } while (unlikely(ret == -EAGAIN));
1518 if (likely(ret >= 0)) {
1519 __queue_delayed_work(cpu, wq, dwork, delay);
1520 local_irq_restore(flags);
1523 /* -ENOENT from try_to_grab_pending() becomes %true */
1526 EXPORT_SYMBOL_GPL(mod_delayed_work_on);
1529 * worker_enter_idle - enter idle state
1530 * @worker: worker which is entering idle state
1532 * @worker is entering idle state. Update stats and idle timer if
1536 * spin_lock_irq(pool->lock).
1538 static void worker_enter_idle(struct worker *worker)
1540 struct worker_pool *pool = worker->pool;
1542 if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) ||
1543 WARN_ON_ONCE(!list_empty(&worker->entry) &&
1544 (worker->hentry.next || worker->hentry.pprev)))
1547 /* can't use worker_set_flags(), also called from start_worker() */
1548 worker->flags |= WORKER_IDLE;
1550 worker->last_active = jiffies;
1552 /* idle_list is LIFO */
1553 list_add(&worker->entry, &pool->idle_list);
1555 if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
1556 mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
1559 * Sanity check nr_running. Because wq_unbind_fn() releases
1560 * pool->lock between setting %WORKER_UNBOUND and zapping
1561 * nr_running, the warning may trigger spuriously. Check iff
1562 * unbind is not in progress.
1564 WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
1565 pool->nr_workers == pool->nr_idle &&
1566 atomic_read(&pool->nr_running));
1570 * worker_leave_idle - leave idle state
1571 * @worker: worker which is leaving idle state
1573 * @worker is leaving idle state. Update stats.
1576 * spin_lock_irq(pool->lock).
1578 static void worker_leave_idle(struct worker *worker)
1580 struct worker_pool *pool = worker->pool;
1582 if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
1584 worker_clr_flags(worker, WORKER_IDLE);
1586 list_del_init(&worker->entry);
1590 * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it
1591 * @pool: target worker_pool
1593 * Bind %current to the cpu of @pool if it is associated and lock @pool.
1595 * Works which are scheduled while the cpu is online must at least be
1596 * scheduled to a worker which is bound to the cpu so that if they are
1597 * flushed from cpu callbacks while cpu is going down, they are
1598 * guaranteed to execute on the cpu.
1600 * This function is to be used by unbound workers and rescuers to bind
1601 * themselves to the target cpu and may race with cpu going down or
1602 * coming online. kthread_bind() can't be used because it may put the
1603 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1604 * verbatim as it's best effort and blocking and pool may be
1605 * [dis]associated in the meantime.
1607 * This function tries set_cpus_allowed() and locks pool and verifies the
1608 * binding against %POOL_DISASSOCIATED which is set during
1609 * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
1610 * enters idle state or fetches works without dropping lock, it can
1611 * guarantee the scheduling requirement described in the first paragraph.
1614 * Might sleep. Called without any lock but returns with pool->lock
1618 * %true if the associated pool is online (@worker is successfully
1619 * bound), %false if offline.
1621 static bool worker_maybe_bind_and_lock(struct worker_pool *pool)
1622 __acquires(&pool->lock)
1626 * The following call may fail, succeed or succeed
1627 * without actually migrating the task to the cpu if
1628 * it races with cpu hotunplug operation. Verify
1629 * against POOL_DISASSOCIATED.
1631 if (!(pool->flags & POOL_DISASSOCIATED))
1632 set_cpus_allowed_ptr(current, pool->attrs->cpumask);
1634 spin_lock_irq(&pool->lock);
1635 if (pool->flags & POOL_DISASSOCIATED)
1637 if (task_cpu(current) == pool->cpu &&
1638 cpumask_equal(¤t->cpus_allowed, pool->attrs->cpumask))
1640 spin_unlock_irq(&pool->lock);
1643 * We've raced with CPU hot[un]plug. Give it a breather
1644 * and retry migration. cond_resched() is required here;
1645 * otherwise, we might deadlock against cpu_stop trying to
1646 * bring down the CPU on non-preemptive kernel.
1653 static struct worker *alloc_worker(void)
1655 struct worker *worker;
1657 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
1659 INIT_LIST_HEAD(&worker->entry);
1660 INIT_LIST_HEAD(&worker->scheduled);
1661 /* on creation a worker is in !idle && prep state */
1662 worker->flags = WORKER_PREP;
1668 * create_worker - create a new workqueue worker
1669 * @pool: pool the new worker will belong to
1671 * Create a new worker which is bound to @pool. The returned worker
1672 * can be started by calling start_worker() or destroyed using
1676 * Might sleep. Does GFP_KERNEL allocations.
1679 * Pointer to the newly created worker.
1681 static struct worker *create_worker(struct worker_pool *pool)
1683 struct worker *worker = NULL;
1687 lockdep_assert_held(&pool->manager_mutex);
1690 * ID is needed to determine kthread name. Allocate ID first
1691 * without installing the pointer.
1693 idr_preload(GFP_KERNEL);
1694 spin_lock_irq(&pool->lock);
1696 id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_NOWAIT);
1698 spin_unlock_irq(&pool->lock);
1703 worker = alloc_worker();
1707 worker->pool = pool;
1711 snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
1712 pool->attrs->nice < 0 ? "H" : "");
1714 snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
1716 worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
1717 "kworker/%s", id_buf);
1718 if (IS_ERR(worker->task))
1722 * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1723 * online CPUs. It'll be re-applied when any of the CPUs come up.
1725 set_user_nice(worker->task, pool->attrs->nice);
1726 set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
1728 /* prevent userland from meddling with cpumask of workqueue workers */
1729 worker->task->flags |= PF_NO_SETAFFINITY;
1732 * The caller is responsible for ensuring %POOL_DISASSOCIATED
1733 * remains stable across this function. See the comments above the
1734 * flag definition for details.
1736 if (pool->flags & POOL_DISASSOCIATED)
1737 worker->flags |= WORKER_UNBOUND;
1739 /* successful, commit the pointer to idr */
1740 spin_lock_irq(&pool->lock);
1741 idr_replace(&pool->worker_idr, worker, worker->id);
1742 spin_unlock_irq(&pool->lock);
1748 spin_lock_irq(&pool->lock);
1749 idr_remove(&pool->worker_idr, id);
1750 spin_unlock_irq(&pool->lock);
1757 * start_worker - start a newly created worker
1758 * @worker: worker to start
1760 * Make the pool aware of @worker and start it.
1763 * spin_lock_irq(pool->lock).
1765 static void start_worker(struct worker *worker)
1767 worker->flags |= WORKER_STARTED;
1768 worker->pool->nr_workers++;
1769 worker_enter_idle(worker);
1770 wake_up_process(worker->task);
1774 * create_and_start_worker - create and start a worker for a pool
1775 * @pool: the target pool
1777 * Grab the managership of @pool and create and start a new worker for it.
1779 static int create_and_start_worker(struct worker_pool *pool)
1781 struct worker *worker;
1783 mutex_lock(&pool->manager_mutex);
1785 worker = create_worker(pool);
1787 spin_lock_irq(&pool->lock);
1788 start_worker(worker);
1789 spin_unlock_irq(&pool->lock);
1792 mutex_unlock(&pool->manager_mutex);
1794 return worker ? 0 : -ENOMEM;
1798 * destroy_worker - destroy a workqueue worker
1799 * @worker: worker to be destroyed
1801 * Destroy @worker and adjust @pool stats accordingly.
1804 * spin_lock_irq(pool->lock) which is released and regrabbed.
1806 static void destroy_worker(struct worker *worker)
1808 struct worker_pool *pool = worker->pool;
1810 lockdep_assert_held(&pool->manager_mutex);
1811 lockdep_assert_held(&pool->lock);
1813 /* sanity check frenzy */
1814 if (WARN_ON(worker->current_work) ||
1815 WARN_ON(!list_empty(&worker->scheduled)))
1818 if (worker->flags & WORKER_STARTED)
1820 if (worker->flags & WORKER_IDLE)
1823 list_del_init(&worker->entry);
1824 worker->flags |= WORKER_DIE;
1826 idr_remove(&pool->worker_idr, worker->id);
1828 spin_unlock_irq(&pool->lock);
1830 kthread_stop(worker->task);
1833 spin_lock_irq(&pool->lock);
1836 static void idle_worker_timeout(unsigned long __pool)
1838 struct worker_pool *pool = (void *)__pool;
1840 spin_lock_irq(&pool->lock);
1842 if (too_many_workers(pool)) {
1843 struct worker *worker;
1844 unsigned long expires;
1846 /* idle_list is kept in LIFO order, check the last one */
1847 worker = list_entry(pool->idle_list.prev, struct worker, entry);
1848 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1850 if (time_before(jiffies, expires))
1851 mod_timer(&pool->idle_timer, expires);
1853 /* it's been idle for too long, wake up manager */
1854 pool->flags |= POOL_MANAGE_WORKERS;
1855 wake_up_worker(pool);
1859 spin_unlock_irq(&pool->lock);
1862 static void send_mayday(struct work_struct *work)
1864 struct pool_workqueue *pwq = get_work_pwq(work);
1865 struct workqueue_struct *wq = pwq->wq;
1867 lockdep_assert_held(&wq_mayday_lock);
1872 /* mayday mayday mayday */
1873 if (list_empty(&pwq->mayday_node)) {
1874 list_add_tail(&pwq->mayday_node, &wq->maydays);
1875 wake_up_process(wq->rescuer->task);
1879 static void pool_mayday_timeout(unsigned long __pool)
1881 struct worker_pool *pool = (void *)__pool;
1882 struct work_struct *work;
1884 spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */
1885 spin_lock(&pool->lock);
1887 if (need_to_create_worker(pool)) {
1889 * We've been trying to create a new worker but
1890 * haven't been successful. We might be hitting an
1891 * allocation deadlock. Send distress signals to
1894 list_for_each_entry(work, &pool->worklist, entry)
1898 spin_unlock(&pool->lock);
1899 spin_unlock_irq(&wq_mayday_lock);
1901 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
1905 * maybe_create_worker - create a new worker if necessary
1906 * @pool: pool to create a new worker for
1908 * Create a new worker for @pool if necessary. @pool is guaranteed to
1909 * have at least one idle worker on return from this function. If
1910 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1911 * sent to all rescuers with works scheduled on @pool to resolve
1912 * possible allocation deadlock.
1914 * On return, need_to_create_worker() is guaranteed to be %false and
1915 * may_start_working() %true.
1918 * spin_lock_irq(pool->lock) which may be released and regrabbed
1919 * multiple times. Does GFP_KERNEL allocations. Called only from
1923 * %false if no action was taken and pool->lock stayed locked, %true
1926 static bool maybe_create_worker(struct worker_pool *pool)
1927 __releases(&pool->lock)
1928 __acquires(&pool->lock)
1930 if (!need_to_create_worker(pool))
1933 spin_unlock_irq(&pool->lock);
1935 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1936 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
1939 struct worker *worker;
1941 worker = create_worker(pool);
1943 del_timer_sync(&pool->mayday_timer);
1944 spin_lock_irq(&pool->lock);
1945 start_worker(worker);
1946 if (WARN_ON_ONCE(need_to_create_worker(pool)))
1951 if (!need_to_create_worker(pool))
1954 __set_current_state(TASK_INTERRUPTIBLE);
1955 schedule_timeout(CREATE_COOLDOWN);
1957 if (!need_to_create_worker(pool))
1961 del_timer_sync(&pool->mayday_timer);
1962 spin_lock_irq(&pool->lock);
1963 if (need_to_create_worker(pool))
1969 * maybe_destroy_worker - destroy workers which have been idle for a while
1970 * @pool: pool to destroy workers for
1972 * Destroy @pool workers which have been idle for longer than
1973 * IDLE_WORKER_TIMEOUT.
1976 * spin_lock_irq(pool->lock) which may be released and regrabbed
1977 * multiple times. Called only from manager.
1980 * %false if no action was taken and pool->lock stayed locked, %true
1983 static bool maybe_destroy_workers(struct worker_pool *pool)
1987 while (too_many_workers(pool)) {
1988 struct worker *worker;
1989 unsigned long expires;
1991 worker = list_entry(pool->idle_list.prev, struct worker, entry);
1992 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1994 if (time_before(jiffies, expires)) {
1995 mod_timer(&pool->idle_timer, expires);
1999 destroy_worker(worker);
2007 * manage_workers - manage worker pool
2010 * Assume the manager role and manage the worker pool @worker belongs
2011 * to. At any given time, there can be only zero or one manager per
2012 * pool. The exclusion is handled automatically by this function.
2014 * The caller can safely start processing works on false return. On
2015 * true return, it's guaranteed that need_to_create_worker() is false
2016 * and may_start_working() is true.
2019 * spin_lock_irq(pool->lock) which may be released and regrabbed
2020 * multiple times. Does GFP_KERNEL allocations.
2023 * spin_lock_irq(pool->lock) which may be released and regrabbed
2024 * multiple times. Does GFP_KERNEL allocations.
2026 static bool manage_workers(struct worker *worker)
2028 struct worker_pool *pool = worker->pool;
2032 * Managership is governed by two mutexes - manager_arb and
2033 * manager_mutex. manager_arb handles arbitration of manager role.
2034 * Anyone who successfully grabs manager_arb wins the arbitration
2035 * and becomes the manager. mutex_trylock() on pool->manager_arb
2036 * failure while holding pool->lock reliably indicates that someone
2037 * else is managing the pool and the worker which failed trylock
2038 * can proceed to executing work items. This means that anyone
2039 * grabbing manager_arb is responsible for actually performing
2040 * manager duties. If manager_arb is grabbed and released without
2041 * actual management, the pool may stall indefinitely.
2043 * manager_mutex is used for exclusion of actual management
2044 * operations. The holder of manager_mutex can be sure that none
2045 * of management operations, including creation and destruction of
2046 * workers, won't take place until the mutex is released. Because
2047 * manager_mutex doesn't interfere with manager role arbitration,
2048 * it is guaranteed that the pool's management, while may be
2049 * delayed, won't be disturbed by someone else grabbing
2052 if (!mutex_trylock(&pool->manager_arb))
2056 * With manager arbitration won, manager_mutex would be free in
2057 * most cases. trylock first without dropping @pool->lock.
2059 if (unlikely(!mutex_trylock(&pool->manager_mutex))) {
2060 spin_unlock_irq(&pool->lock);
2061 mutex_lock(&pool->manager_mutex);
2065 pool->flags &= ~POOL_MANAGE_WORKERS;
2068 * Destroy and then create so that may_start_working() is true
2071 ret |= maybe_destroy_workers(pool);
2072 ret |= maybe_create_worker(pool);
2074 mutex_unlock(&pool->manager_mutex);
2075 mutex_unlock(&pool->manager_arb);
2080 * process_one_work - process single work
2082 * @work: work to process
2084 * Process @work. This function contains all the logics necessary to
2085 * process a single work including synchronization against and
2086 * interaction with other workers on the same cpu, queueing and
2087 * flushing. As long as context requirement is met, any worker can
2088 * call this function to process a work.
2091 * spin_lock_irq(pool->lock) which is released and regrabbed.
2093 static void process_one_work(struct worker *worker, struct work_struct *work)
2094 __releases(&pool->lock)
2095 __acquires(&pool->lock)
2097 struct pool_workqueue *pwq = get_work_pwq(work);
2098 struct worker_pool *pool = worker->pool;
2099 bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
2101 struct worker *collision;
2102 #ifdef CONFIG_LOCKDEP
2104 * It is permissible to free the struct work_struct from
2105 * inside the function that is called from it, this we need to
2106 * take into account for lockdep too. To avoid bogus "held
2107 * lock freed" warnings as well as problems when looking into
2108 * work->lockdep_map, make a copy and use that here.
2110 struct lockdep_map lockdep_map;
2112 lockdep_copy_map(&lockdep_map, &work->lockdep_map);
2115 * Ensure we're on the correct CPU. DISASSOCIATED test is
2116 * necessary to avoid spurious warnings from rescuers servicing the
2117 * unbound or a disassociated pool.
2119 WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) &&
2120 !(pool->flags & POOL_DISASSOCIATED) &&
2121 raw_smp_processor_id() != pool->cpu);
2124 * A single work shouldn't be executed concurrently by
2125 * multiple workers on a single cpu. Check whether anyone is
2126 * already processing the work. If so, defer the work to the
2127 * currently executing one.
2129 collision = find_worker_executing_work(pool, work);
2130 if (unlikely(collision)) {
2131 move_linked_works(work, &collision->scheduled, NULL);
2135 /* claim and dequeue */
2136 debug_work_deactivate(work);
2137 hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
2138 worker->current_work = work;
2139 worker->current_func = work->func;
2140 worker->current_pwq = pwq;
2141 work_color = get_work_color(work);
2143 list_del_init(&work->entry);
2146 * CPU intensive works don't participate in concurrency
2147 * management. They're the scheduler's responsibility.
2149 if (unlikely(cpu_intensive))
2150 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
2153 * Unbound pool isn't concurrency managed and work items should be
2154 * executed ASAP. Wake up another worker if necessary.
2156 if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
2157 wake_up_worker(pool);
2160 * Record the last pool and clear PENDING which should be the last
2161 * update to @work. Also, do this inside @pool->lock so that
2162 * PENDING and queued state changes happen together while IRQ is
2165 set_work_pool_and_clear_pending(work, pool->id);
2167 spin_unlock_irq(&pool->lock);
2169 lock_map_acquire_read(&pwq->wq->lockdep_map);
2170 lock_map_acquire(&lockdep_map);
2171 trace_workqueue_execute_start(work);
2172 worker->current_func(work);
2174 * While we must be careful to not use "work" after this, the trace
2175 * point will only record its address.
2177 trace_workqueue_execute_end(work);
2178 lock_map_release(&lockdep_map);
2179 lock_map_release(&pwq->wq->lockdep_map);
2181 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
2182 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2183 " last function: %pf\n",
2184 current->comm, preempt_count(), task_pid_nr(current),
2185 worker->current_func);
2186 debug_show_held_locks(current);
2190 spin_lock_irq(&pool->lock);
2192 /* clear cpu intensive status */
2193 if (unlikely(cpu_intensive))
2194 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
2196 /* we're done with it, release */
2197 hash_del(&worker->hentry);
2198 worker->current_work = NULL;
2199 worker->current_func = NULL;
2200 worker->current_pwq = NULL;
2201 pwq_dec_nr_in_flight(pwq, work_color);
2205 * process_scheduled_works - process scheduled works
2208 * Process all scheduled works. Please note that the scheduled list
2209 * may change while processing a work, so this function repeatedly
2210 * fetches a work from the top and executes it.
2213 * spin_lock_irq(pool->lock) which may be released and regrabbed
2216 static void process_scheduled_works(struct worker *worker)
2218 while (!list_empty(&worker->scheduled)) {
2219 struct work_struct *work = list_first_entry(&worker->scheduled,
2220 struct work_struct, entry);
2221 process_one_work(worker, work);
2226 * worker_thread - the worker thread function
2229 * The worker thread function. All workers belong to a worker_pool -
2230 * either a per-cpu one or dynamic unbound one. These workers process all
2231 * work items regardless of their specific target workqueue. The only
2232 * exception is work items which belong to workqueues with a rescuer which
2233 * will be explained in rescuer_thread().
2235 static int worker_thread(void *__worker)
2237 struct worker *worker = __worker;
2238 struct worker_pool *pool = worker->pool;
2240 /* tell the scheduler that this is a workqueue worker */
2241 worker->task->flags |= PF_WQ_WORKER;
2243 spin_lock_irq(&pool->lock);
2245 /* am I supposed to die? */
2246 if (unlikely(worker->flags & WORKER_DIE)) {
2247 spin_unlock_irq(&pool->lock);
2248 WARN_ON_ONCE(!list_empty(&worker->entry));
2249 worker->task->flags &= ~PF_WQ_WORKER;
2253 worker_leave_idle(worker);
2255 /* no more worker necessary? */
2256 if (!need_more_worker(pool))
2259 /* do we need to manage? */
2260 if (unlikely(!may_start_working(pool)) && manage_workers(worker))
2264 * ->scheduled list can only be filled while a worker is
2265 * preparing to process a work or actually processing it.
2266 * Make sure nobody diddled with it while I was sleeping.
2268 WARN_ON_ONCE(!list_empty(&worker->scheduled));
2271 * Finish PREP stage. We're guaranteed to have at least one idle
2272 * worker or that someone else has already assumed the manager
2273 * role. This is where @worker starts participating in concurrency
2274 * management if applicable and concurrency management is restored
2275 * after being rebound. See rebind_workers() for details.
2277 worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND);
2280 struct work_struct *work =
2281 list_first_entry(&pool->worklist,
2282 struct work_struct, entry);
2284 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
2285 /* optimization path, not strictly necessary */
2286 process_one_work(worker, work);
2287 if (unlikely(!list_empty(&worker->scheduled)))
2288 process_scheduled_works(worker);
2290 move_linked_works(work, &worker->scheduled, NULL);
2291 process_scheduled_works(worker);
2293 } while (keep_working(pool));
2295 worker_set_flags(worker, WORKER_PREP, false);
2297 if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker))
2301 * pool->lock is held and there's no work to process and no need to
2302 * manage, sleep. Workers are woken up only while holding
2303 * pool->lock or from local cpu, so setting the current state
2304 * before releasing pool->lock is enough to prevent losing any
2307 worker_enter_idle(worker);
2308 __set_current_state(TASK_INTERRUPTIBLE);
2309 spin_unlock_irq(&pool->lock);
2315 * rescuer_thread - the rescuer thread function
2318 * Workqueue rescuer thread function. There's one rescuer for each
2319 * workqueue which has WQ_MEM_RECLAIM set.
2321 * Regular work processing on a pool may block trying to create a new
2322 * worker which uses GFP_KERNEL allocation which has slight chance of
2323 * developing into deadlock if some works currently on the same queue
2324 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2325 * the problem rescuer solves.
2327 * When such condition is possible, the pool summons rescuers of all
2328 * workqueues which have works queued on the pool and let them process
2329 * those works so that forward progress can be guaranteed.
2331 * This should happen rarely.
2333 static int rescuer_thread(void *__rescuer)
2335 struct worker *rescuer = __rescuer;
2336 struct workqueue_struct *wq = rescuer->rescue_wq;
2337 struct list_head *scheduled = &rescuer->scheduled;
2339 set_user_nice(current, RESCUER_NICE_LEVEL);
2342 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2343 * doesn't participate in concurrency management.
2345 rescuer->task->flags |= PF_WQ_WORKER;
2347 set_current_state(TASK_INTERRUPTIBLE);
2349 if (kthread_should_stop()) {
2350 __set_current_state(TASK_RUNNING);
2351 rescuer->task->flags &= ~PF_WQ_WORKER;
2355 /* see whether any pwq is asking for help */
2356 spin_lock_irq(&wq_mayday_lock);
2358 while (!list_empty(&wq->maydays)) {
2359 struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
2360 struct pool_workqueue, mayday_node);
2361 struct worker_pool *pool = pwq->pool;
2362 struct work_struct *work, *n;
2364 __set_current_state(TASK_RUNNING);
2365 list_del_init(&pwq->mayday_node);
2367 spin_unlock_irq(&wq_mayday_lock);
2369 /* migrate to the target cpu if possible */
2370 worker_maybe_bind_and_lock(pool);
2371 rescuer->pool = pool;
2374 * Slurp in all works issued via this workqueue and
2377 WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
2378 list_for_each_entry_safe(work, n, &pool->worklist, entry)
2379 if (get_work_pwq(work) == pwq)
2380 move_linked_works(work, scheduled, &n);
2382 process_scheduled_works(rescuer);
2385 * Leave this pool. If keep_working() is %true, notify a
2386 * regular worker; otherwise, we end up with 0 concurrency
2387 * and stalling the execution.
2389 if (keep_working(pool))
2390 wake_up_worker(pool);
2392 rescuer->pool = NULL;
2393 spin_unlock(&pool->lock);
2394 spin_lock(&wq_mayday_lock);
2397 spin_unlock_irq(&wq_mayday_lock);
2399 /* rescuers should never participate in concurrency management */
2400 WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
2406 struct work_struct work;
2407 struct completion done;
2410 static void wq_barrier_func(struct work_struct *work)
2412 struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
2413 complete(&barr->done);
2417 * insert_wq_barrier - insert a barrier work
2418 * @pwq: pwq to insert barrier into
2419 * @barr: wq_barrier to insert
2420 * @target: target work to attach @barr to
2421 * @worker: worker currently executing @target, NULL if @target is not executing
2423 * @barr is linked to @target such that @barr is completed only after
2424 * @target finishes execution. Please note that the ordering
2425 * guarantee is observed only with respect to @target and on the local
2428 * Currently, a queued barrier can't be canceled. This is because
2429 * try_to_grab_pending() can't determine whether the work to be
2430 * grabbed is at the head of the queue and thus can't clear LINKED
2431 * flag of the previous work while there must be a valid next work
2432 * after a work with LINKED flag set.
2434 * Note that when @worker is non-NULL, @target may be modified
2435 * underneath us, so we can't reliably determine pwq from @target.
2438 * spin_lock_irq(pool->lock).
2440 static void insert_wq_barrier(struct pool_workqueue *pwq,
2441 struct wq_barrier *barr,
2442 struct work_struct *target, struct worker *worker)
2444 struct list_head *head;
2445 unsigned int linked = 0;
2448 * debugobject calls are safe here even with pool->lock locked
2449 * as we know for sure that this will not trigger any of the
2450 * checks and call back into the fixup functions where we
2453 INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
2454 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
2455 init_completion(&barr->done);
2458 * If @target is currently being executed, schedule the
2459 * barrier to the worker; otherwise, put it after @target.
2462 head = worker->scheduled.next;
2464 unsigned long *bits = work_data_bits(target);
2466 head = target->entry.next;
2467 /* there can already be other linked works, inherit and set */
2468 linked = *bits & WORK_STRUCT_LINKED;
2469 __set_bit(WORK_STRUCT_LINKED_BIT, bits);
2472 debug_work_activate(&barr->work);
2473 insert_work(pwq, &barr->work, head,
2474 work_color_to_flags(WORK_NO_COLOR) | linked);
2478 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2479 * @wq: workqueue being flushed
2480 * @flush_color: new flush color, < 0 for no-op
2481 * @work_color: new work color, < 0 for no-op
2483 * Prepare pwqs for workqueue flushing.
2485 * If @flush_color is non-negative, flush_color on all pwqs should be
2486 * -1. If no pwq has in-flight commands at the specified color, all
2487 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2488 * has in flight commands, its pwq->flush_color is set to
2489 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2490 * wakeup logic is armed and %true is returned.
2492 * The caller should have initialized @wq->first_flusher prior to
2493 * calling this function with non-negative @flush_color. If
2494 * @flush_color is negative, no flush color update is done and %false
2497 * If @work_color is non-negative, all pwqs should have the same
2498 * work_color which is previous to @work_color and all will be
2499 * advanced to @work_color.
2502 * mutex_lock(wq->mutex).
2505 * %true if @flush_color >= 0 and there's something to flush. %false
2508 static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
2509 int flush_color, int work_color)
2512 struct pool_workqueue *pwq;
2514 if (flush_color >= 0) {
2515 WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
2516 atomic_set(&wq->nr_pwqs_to_flush, 1);
2519 for_each_pwq(pwq, wq) {
2520 struct worker_pool *pool = pwq->pool;
2522 spin_lock_irq(&pool->lock);
2524 if (flush_color >= 0) {
2525 WARN_ON_ONCE(pwq->flush_color != -1);
2527 if (pwq->nr_in_flight[flush_color]) {
2528 pwq->flush_color = flush_color;
2529 atomic_inc(&wq->nr_pwqs_to_flush);
2534 if (work_color >= 0) {
2535 WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
2536 pwq->work_color = work_color;
2539 spin_unlock_irq(&pool->lock);
2542 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
2543 complete(&wq->first_flusher->done);
2549 * flush_workqueue - ensure that any scheduled work has run to completion.
2550 * @wq: workqueue to flush
2552 * This function sleeps until all work items which were queued on entry
2553 * have finished execution, but it is not livelocked by new incoming ones.
2555 void flush_workqueue(struct workqueue_struct *wq)
2557 struct wq_flusher this_flusher = {
2558 .list = LIST_HEAD_INIT(this_flusher.list),
2560 .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
2564 lock_map_acquire(&wq->lockdep_map);
2565 lock_map_release(&wq->lockdep_map);
2567 mutex_lock(&wq->mutex);
2570 * Start-to-wait phase
2572 next_color = work_next_color(wq->work_color);
2574 if (next_color != wq->flush_color) {
2576 * Color space is not full. The current work_color
2577 * becomes our flush_color and work_color is advanced
2580 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
2581 this_flusher.flush_color = wq->work_color;
2582 wq->work_color = next_color;
2584 if (!wq->first_flusher) {
2585 /* no flush in progress, become the first flusher */
2586 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
2588 wq->first_flusher = &this_flusher;
2590 if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
2592 /* nothing to flush, done */
2593 wq->flush_color = next_color;
2594 wq->first_flusher = NULL;
2599 WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
2600 list_add_tail(&this_flusher.list, &wq->flusher_queue);
2601 flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
2605 * Oops, color space is full, wait on overflow queue.
2606 * The next flush completion will assign us
2607 * flush_color and transfer to flusher_queue.
2609 list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2612 mutex_unlock(&wq->mutex);
2614 wait_for_completion(&this_flusher.done);
2617 * Wake-up-and-cascade phase
2619 * First flushers are responsible for cascading flushes and
2620 * handling overflow. Non-first flushers can simply return.
2622 if (wq->first_flusher != &this_flusher)
2625 mutex_lock(&wq->mutex);
2627 /* we might have raced, check again with mutex held */
2628 if (wq->first_flusher != &this_flusher)
2631 wq->first_flusher = NULL;
2633 WARN_ON_ONCE(!list_empty(&this_flusher.list));
2634 WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
2637 struct wq_flusher *next, *tmp;
2639 /* complete all the flushers sharing the current flush color */
2640 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2641 if (next->flush_color != wq->flush_color)
2643 list_del_init(&next->list);
2644 complete(&next->done);
2647 WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
2648 wq->flush_color != work_next_color(wq->work_color));
2650 /* this flush_color is finished, advance by one */
2651 wq->flush_color = work_next_color(wq->flush_color);
2653 /* one color has been freed, handle overflow queue */
2654 if (!list_empty(&wq->flusher_overflow)) {
2656 * Assign the same color to all overflowed
2657 * flushers, advance work_color and append to
2658 * flusher_queue. This is the start-to-wait
2659 * phase for these overflowed flushers.
2661 list_for_each_entry(tmp, &wq->flusher_overflow, list)
2662 tmp->flush_color = wq->work_color;
2664 wq->work_color = work_next_color(wq->work_color);
2666 list_splice_tail_init(&wq->flusher_overflow,
2667 &wq->flusher_queue);
2668 flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
2671 if (list_empty(&wq->flusher_queue)) {
2672 WARN_ON_ONCE(wq->flush_color != wq->work_color);
2677 * Need to flush more colors. Make the next flusher
2678 * the new first flusher and arm pwqs.
2680 WARN_ON_ONCE(wq->flush_color == wq->work_color);
2681 WARN_ON_ONCE(wq->flush_color != next->flush_color);
2683 list_del_init(&next->list);
2684 wq->first_flusher = next;
2686 if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
2690 * Meh... this color is already done, clear first
2691 * flusher and repeat cascading.
2693 wq->first_flusher = NULL;
2697 mutex_unlock(&wq->mutex);
2699 EXPORT_SYMBOL_GPL(flush_workqueue);
2702 * drain_workqueue - drain a workqueue
2703 * @wq: workqueue to drain
2705 * Wait until the workqueue becomes empty. While draining is in progress,
2706 * only chain queueing is allowed. IOW, only currently pending or running
2707 * work items on @wq can queue further work items on it. @wq is flushed
2708 * repeatedly until it becomes empty. The number of flushing is detemined
2709 * by the depth of chaining and should be relatively short. Whine if it
2712 void drain_workqueue(struct workqueue_struct *wq)
2714 unsigned int flush_cnt = 0;
2715 struct pool_workqueue *pwq;
2718 * __queue_work() needs to test whether there are drainers, is much
2719 * hotter than drain_workqueue() and already looks at @wq->flags.
2720 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
2722 mutex_lock(&wq->mutex);
2723 if (!wq->nr_drainers++)
2724 wq->flags |= __WQ_DRAINING;
2725 mutex_unlock(&wq->mutex);
2727 flush_workqueue(wq);
2729 mutex_lock(&wq->mutex);
2731 for_each_pwq(pwq, wq) {
2734 spin_lock_irq(&pwq->pool->lock);
2735 drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
2736 spin_unlock_irq(&pwq->pool->lock);
2741 if (++flush_cnt == 10 ||
2742 (flush_cnt % 100 == 0 && flush_cnt <= 1000))
2743 pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
2744 wq->name, flush_cnt);
2746 mutex_unlock(&wq->mutex);
2750 if (!--wq->nr_drainers)
2751 wq->flags &= ~__WQ_DRAINING;
2752 mutex_unlock(&wq->mutex);
2754 EXPORT_SYMBOL_GPL(drain_workqueue);
2756 static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
2758 struct worker *worker = NULL;
2759 struct worker_pool *pool;
2760 struct pool_workqueue *pwq;
2764 local_irq_disable();
2765 pool = get_work_pool(work);
2771 spin_lock(&pool->lock);
2772 /* see the comment in try_to_grab_pending() with the same code */
2773 pwq = get_work_pwq(work);
2775 if (unlikely(pwq->pool != pool))
2778 worker = find_worker_executing_work(pool, work);
2781 pwq = worker->current_pwq;
2784 insert_wq_barrier(pwq, barr, work, worker);
2785 spin_unlock_irq(&pool->lock);
2788 * If @max_active is 1 or rescuer is in use, flushing another work
2789 * item on the same workqueue may lead to deadlock. Make sure the
2790 * flusher is not running on the same workqueue by verifying write
2793 if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)
2794 lock_map_acquire(&pwq->wq->lockdep_map);
2796 lock_map_acquire_read(&pwq->wq->lockdep_map);
2797 lock_map_release(&pwq->wq->lockdep_map);
2801 spin_unlock_irq(&pool->lock);
2806 * flush_work - wait for a work to finish executing the last queueing instance
2807 * @work: the work to flush
2809 * Wait until @work has finished execution. @work is guaranteed to be idle
2810 * on return if it hasn't been requeued since flush started.
2813 * %true if flush_work() waited for the work to finish execution,
2814 * %false if it was already idle.
2816 bool flush_work(struct work_struct *work)
2818 struct wq_barrier barr;
2820 lock_map_acquire(&work->lockdep_map);
2821 lock_map_release(&work->lockdep_map);
2823 if (start_flush_work(work, &barr)) {
2824 wait_for_completion(&barr.done);
2825 destroy_work_on_stack(&barr.work);
2831 EXPORT_SYMBOL_GPL(flush_work);
2833 static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
2835 unsigned long flags;
2839 ret = try_to_grab_pending(work, is_dwork, &flags);
2841 * If someone else is canceling, wait for the same event it
2842 * would be waiting for before retrying.
2844 if (unlikely(ret == -ENOENT))
2846 } while (unlikely(ret < 0));
2848 /* tell other tasks trying to grab @work to back off */
2849 mark_work_canceling(work);
2850 local_irq_restore(flags);
2853 clear_work_data(work);
2858 * cancel_work_sync - cancel a work and wait for it to finish
2859 * @work: the work to cancel
2861 * Cancel @work and wait for its execution to finish. This function
2862 * can be used even if the work re-queues itself or migrates to
2863 * another workqueue. On return from this function, @work is
2864 * guaranteed to be not pending or executing on any CPU.
2866 * cancel_work_sync(&delayed_work->work) must not be used for
2867 * delayed_work's. Use cancel_delayed_work_sync() instead.
2869 * The caller must ensure that the workqueue on which @work was last
2870 * queued can't be destroyed before this function returns.
2873 * %true if @work was pending, %false otherwise.
2875 bool cancel_work_sync(struct work_struct *work)
2877 return __cancel_work_timer(work, false);
2879 EXPORT_SYMBOL_GPL(cancel_work_sync);
2882 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2883 * @dwork: the delayed work to flush
2885 * Delayed timer is cancelled and the pending work is queued for
2886 * immediate execution. Like flush_work(), this function only
2887 * considers the last queueing instance of @dwork.
2890 * %true if flush_work() waited for the work to finish execution,
2891 * %false if it was already idle.
2893 bool flush_delayed_work(struct delayed_work *dwork)
2895 local_irq_disable();
2896 if (del_timer_sync(&dwork->timer))
2897 __queue_work(dwork->cpu, dwork->wq, &dwork->work);
2899 return flush_work(&dwork->work);
2901 EXPORT_SYMBOL(flush_delayed_work);
2904 * cancel_delayed_work - cancel a delayed work
2905 * @dwork: delayed_work to cancel
2907 * Kill off a pending delayed_work. Returns %true if @dwork was pending
2908 * and canceled; %false if wasn't pending. Note that the work callback
2909 * function may still be running on return, unless it returns %true and the
2910 * work doesn't re-arm itself. Explicitly flush or use
2911 * cancel_delayed_work_sync() to wait on it.
2913 * This function is safe to call from any context including IRQ handler.
2915 bool cancel_delayed_work(struct delayed_work *dwork)
2917 unsigned long flags;
2921 ret = try_to_grab_pending(&dwork->work, true, &flags);
2922 } while (unlikely(ret == -EAGAIN));
2924 if (unlikely(ret < 0))
2927 set_work_pool_and_clear_pending(&dwork->work,
2928 get_work_pool_id(&dwork->work));
2929 local_irq_restore(flags);
2932 EXPORT_SYMBOL(cancel_delayed_work);
2935 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2936 * @dwork: the delayed work cancel
2938 * This is cancel_work_sync() for delayed works.
2941 * %true if @dwork was pending, %false otherwise.
2943 bool cancel_delayed_work_sync(struct delayed_work *dwork)
2945 return __cancel_work_timer(&dwork->work, true);
2947 EXPORT_SYMBOL(cancel_delayed_work_sync);
2950 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2951 * @func: the function to call
2953 * schedule_on_each_cpu() executes @func on each online CPU using the
2954 * system workqueue and blocks until all CPUs have completed.
2955 * schedule_on_each_cpu() is very slow.
2958 * 0 on success, -errno on failure.
2960 int schedule_on_each_cpu(work_func_t func)
2963 struct work_struct __percpu *works;
2965 works = alloc_percpu(struct work_struct);
2971 for_each_online_cpu(cpu) {
2972 struct work_struct *work = per_cpu_ptr(works, cpu);
2974 INIT_WORK(work, func);
2975 schedule_work_on(cpu, work);
2978 for_each_online_cpu(cpu)
2979 flush_work(per_cpu_ptr(works, cpu));
2987 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2989 * Forces execution of the kernel-global workqueue and blocks until its
2992 * Think twice before calling this function! It's very easy to get into
2993 * trouble if you don't take great care. Either of the following situations
2994 * will lead to deadlock:
2996 * One of the work items currently on the workqueue needs to acquire
2997 * a lock held by your code or its caller.
2999 * Your code is running in the context of a work routine.
3001 * They will be detected by lockdep when they occur, but the first might not
3002 * occur very often. It depends on what work items are on the workqueue and
3003 * what locks they need, which you have no control over.
3005 * In most situations flushing the entire workqueue is overkill; you merely
3006 * need to know that a particular work item isn't queued and isn't running.
3007 * In such cases you should use cancel_delayed_work_sync() or
3008 * cancel_work_sync() instead.
3010 void flush_scheduled_work(void)
3012 flush_workqueue(system_wq);
3014 EXPORT_SYMBOL(flush_scheduled_work);
3017 * execute_in_process_context - reliably execute the routine with user context
3018 * @fn: the function to execute
3019 * @ew: guaranteed storage for the execute work structure (must
3020 * be available when the work executes)
3022 * Executes the function immediately if process context is available,
3023 * otherwise schedules the function for delayed execution.
3025 * Returns: 0 - function was executed
3026 * 1 - function was scheduled for execution
3028 int execute_in_process_context(work_func_t fn, struct execute_work *ew)
3030 if (!in_interrupt()) {
3035 INIT_WORK(&ew->work, fn);
3036 schedule_work(&ew->work);
3040 EXPORT_SYMBOL_GPL(execute_in_process_context);
3044 * Workqueues with WQ_SYSFS flag set is visible to userland via
3045 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
3046 * following attributes.
3048 * per_cpu RO bool : whether the workqueue is per-cpu or unbound
3049 * max_active RW int : maximum number of in-flight work items
3051 * Unbound workqueues have the following extra attributes.
3053 * id RO int : the associated pool ID
3054 * nice RW int : nice value of the workers
3055 * cpumask RW mask : bitmask of allowed CPUs for the workers
3058 struct workqueue_struct *wq;
3062 static struct workqueue_struct *dev_to_wq(struct device *dev)
3064 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
3069 static ssize_t wq_per_cpu_show(struct device *dev,
3070 struct device_attribute *attr, char *buf)
3072 struct workqueue_struct *wq = dev_to_wq(dev);
3074 return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
3077 static ssize_t wq_max_active_show(struct device *dev,
3078 struct device_attribute *attr, char *buf)
3080 struct workqueue_struct *wq = dev_to_wq(dev);
3082 return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
3085 static ssize_t wq_max_active_store(struct device *dev,
3086 struct device_attribute *attr,
3087 const char *buf, size_t count)
3089 struct workqueue_struct *wq = dev_to_wq(dev);
3092 if (sscanf(buf, "%d", &val) != 1 || val <= 0)
3095 workqueue_set_max_active(wq, val);
3099 static struct device_attribute wq_sysfs_attrs[] = {
3100 __ATTR(per_cpu, 0444, wq_per_cpu_show, NULL),
3101 __ATTR(max_active, 0644, wq_max_active_show, wq_max_active_store),
3105 static ssize_t wq_pool_ids_show(struct device *dev,
3106 struct device_attribute *attr, char *buf)
3108 struct workqueue_struct *wq = dev_to_wq(dev);
3109 const char *delim = "";
3110 int node, written = 0;
3112 rcu_read_lock_sched();
3113 for_each_node(node) {
3114 written += scnprintf(buf + written, PAGE_SIZE - written,
3115 "%s%d:%d", delim, node,
3116 unbound_pwq_by_node(wq, node)->pool->id);
3119 written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
3120 rcu_read_unlock_sched();
3125 static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr,
3128 struct workqueue_struct *wq = dev_to_wq(dev);
3131 mutex_lock(&wq->mutex);
3132 written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
3133 mutex_unlock(&wq->mutex);
3138 /* prepare workqueue_attrs for sysfs store operations */
3139 static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq)
3141 struct workqueue_attrs *attrs;
3143 attrs = alloc_workqueue_attrs(GFP_KERNEL);
3147 mutex_lock(&wq->mutex);
3148 copy_workqueue_attrs(attrs, wq->unbound_attrs);
3149 mutex_unlock(&wq->mutex);
3153 static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr,
3154 const char *buf, size_t count)
3156 struct workqueue_struct *wq = dev_to_wq(dev);
3157 struct workqueue_attrs *attrs;
3160 attrs = wq_sysfs_prep_attrs(wq);
3164 if (sscanf(buf, "%d", &attrs->nice) == 1 &&
3165 attrs->nice >= -20 && attrs->nice <= 19)
3166 ret = apply_workqueue_attrs(wq, attrs);
3170 free_workqueue_attrs(attrs);
3171 return ret ?: count;
3174 static ssize_t wq_cpumask_show(struct device *dev,
3175 struct device_attribute *attr, char *buf)
3177 struct workqueue_struct *wq = dev_to_wq(dev);
3180 mutex_lock(&wq->mutex);
3181 written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask);
3182 mutex_unlock(&wq->mutex);
3184 written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
3188 static ssize_t wq_cpumask_store(struct device *dev,
3189 struct device_attribute *attr,
3190 const char *buf, size_t count)
3192 struct workqueue_struct *wq = dev_to_wq(dev);
3193 struct workqueue_attrs *attrs;
3196 attrs = wq_sysfs_prep_attrs(wq);
3200 ret = cpumask_parse(buf, attrs->cpumask);
3202 ret = apply_workqueue_attrs(wq, attrs);
3204 free_workqueue_attrs(attrs);
3205 return ret ?: count;
3208 static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr,
3211 struct workqueue_struct *wq = dev_to_wq(dev);
3214 mutex_lock(&wq->mutex);
3215 written = scnprintf(buf, PAGE_SIZE, "%d\n",
3216 !wq->unbound_attrs->no_numa);
3217 mutex_unlock(&wq->mutex);
3222 static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr,
3223 const char *buf, size_t count)
3225 struct workqueue_struct *wq = dev_to_wq(dev);
3226 struct workqueue_attrs *attrs;
3229 attrs = wq_sysfs_prep_attrs(wq);
3234 if (sscanf(buf, "%d", &v) == 1) {
3235 attrs->no_numa = !v;
3236 ret = apply_workqueue_attrs(wq, attrs);
3239 free_workqueue_attrs(attrs);
3240 return ret ?: count;
3243 static struct device_attribute wq_sysfs_unbound_attrs[] = {
3244 __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL),
3245 __ATTR(nice, 0644, wq_nice_show, wq_nice_store),
3246 __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
3247 __ATTR(numa, 0644, wq_numa_show, wq_numa_store),
3251 static struct bus_type wq_subsys = {
3252 .name = "workqueue",
3253 .dev_attrs = wq_sysfs_attrs,
3256 static int __init wq_sysfs_init(void)
3258 return subsys_virtual_register(&wq_subsys, NULL);
3260 core_initcall(wq_sysfs_init);
3262 static void wq_device_release(struct device *dev)
3264 struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
3270 * workqueue_sysfs_register - make a workqueue visible in sysfs
3271 * @wq: the workqueue to register
3273 * Expose @wq in sysfs under /sys/bus/workqueue/devices.
3274 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
3275 * which is the preferred method.
3277 * Workqueue user should use this function directly iff it wants to apply
3278 * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
3279 * apply_workqueue_attrs() may race against userland updating the
3282 * Returns 0 on success, -errno on failure.
3284 int workqueue_sysfs_register(struct workqueue_struct *wq)
3286 struct wq_device *wq_dev;
3290 * Adjusting max_active or creating new pwqs by applyting
3291 * attributes breaks ordering guarantee. Disallow exposing ordered
3294 if (WARN_ON(wq->flags & __WQ_ORDERED))
3297 wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
3302 wq_dev->dev.bus = &wq_subsys;
3303 wq_dev->dev.init_name = wq->name;
3304 wq_dev->dev.release = wq_device_release;
3307 * unbound_attrs are created separately. Suppress uevent until
3308 * everything is ready.
3310 dev_set_uevent_suppress(&wq_dev->dev, true);
3312 ret = device_register(&wq_dev->dev);
3319 if (wq->flags & WQ_UNBOUND) {
3320 struct device_attribute *attr;
3322 for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
3323 ret = device_create_file(&wq_dev->dev, attr);
3325 device_unregister(&wq_dev->dev);
3332 kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
3337 * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
3338 * @wq: the workqueue to unregister
3340 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
3342 static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
3344 struct wq_device *wq_dev = wq->wq_dev;
3350 device_unregister(&wq_dev->dev);
3352 #else /* CONFIG_SYSFS */
3353 static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
3354 #endif /* CONFIG_SYSFS */
3357 * free_workqueue_attrs - free a workqueue_attrs
3358 * @attrs: workqueue_attrs to free
3360 * Undo alloc_workqueue_attrs().
3362 void free_workqueue_attrs(struct workqueue_attrs *attrs)
3365 free_cpumask_var(attrs->cpumask);
3371 * alloc_workqueue_attrs - allocate a workqueue_attrs
3372 * @gfp_mask: allocation mask to use
3374 * Allocate a new workqueue_attrs, initialize with default settings and
3375 * return it. Returns NULL on failure.
3377 struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask)
3379 struct workqueue_attrs *attrs;
3381 attrs = kzalloc(sizeof(*attrs), gfp_mask);
3384 if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask))
3387 cpumask_copy(attrs->cpumask, cpu_possible_mask);
3390 free_workqueue_attrs(attrs);
3394 static void copy_workqueue_attrs(struct workqueue_attrs *to,
3395 const struct workqueue_attrs *from)
3397 to->nice = from->nice;
3398 cpumask_copy(to->cpumask, from->cpumask);
3401 /* hash value of the content of @attr */
3402 static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
3406 hash = jhash_1word(attrs->nice, hash);
3407 hash = jhash(cpumask_bits(attrs->cpumask),
3408 BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
3412 /* content equality test */
3413 static bool wqattrs_equal(const struct workqueue_attrs *a,
3414 const struct workqueue_attrs *b)
3416 if (a->nice != b->nice)
3418 if (!cpumask_equal(a->cpumask, b->cpumask))
3424 * init_worker_pool - initialize a newly zalloc'd worker_pool
3425 * @pool: worker_pool to initialize
3427 * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
3428 * Returns 0 on success, -errno on failure. Even on failure, all fields
3429 * inside @pool proper are initialized and put_unbound_pool() can be called
3430 * on @pool safely to release it.
3432 static int init_worker_pool(struct worker_pool *pool)
3434 spin_lock_init(&pool->lock);
3437 pool->node = NUMA_NO_NODE;
3438 pool->flags |= POOL_DISASSOCIATED;
3439 INIT_LIST_HEAD(&pool->worklist);
3440 INIT_LIST_HEAD(&pool->idle_list);
3441 hash_init(pool->busy_hash);
3443 init_timer_deferrable(&pool->idle_timer);
3444 pool->idle_timer.function = idle_worker_timeout;
3445 pool->idle_timer.data = (unsigned long)pool;
3447 setup_timer(&pool->mayday_timer, pool_mayday_timeout,
3448 (unsigned long)pool);
3450 mutex_init(&pool->manager_arb);
3451 mutex_init(&pool->manager_mutex);
3452 idr_init(&pool->worker_idr);
3454 INIT_HLIST_NODE(&pool->hash_node);
3457 /* shouldn't fail above this point */
3458 pool->attrs = alloc_workqueue_attrs(GFP_KERNEL);
3464 static void rcu_free_pool(struct rcu_head *rcu)
3466 struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
3468 idr_destroy(&pool->worker_idr);
3469 free_workqueue_attrs(pool->attrs);
3474 * put_unbound_pool - put a worker_pool
3475 * @pool: worker_pool to put
3477 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
3478 * safe manner. get_unbound_pool() calls this function on its failure path
3479 * and this function should be able to release pools which went through,
3480 * successfully or not, init_worker_pool().
3482 * Should be called with wq_pool_mutex held.
3484 static void put_unbound_pool(struct worker_pool *pool)
3486 struct worker *worker;
3488 lockdep_assert_held(&wq_pool_mutex);
3494 if (WARN_ON(!(pool->flags & POOL_DISASSOCIATED)) ||
3495 WARN_ON(!list_empty(&pool->worklist)))
3498 /* release id and unhash */
3500 idr_remove(&worker_pool_idr, pool->id);
3501 hash_del(&pool->hash_node);
3504 * Become the manager and destroy all workers. Grabbing
3505 * manager_arb prevents @pool's workers from blocking on
3508 mutex_lock(&pool->manager_arb);
3509 mutex_lock(&pool->manager_mutex);
3510 spin_lock_irq(&pool->lock);
3512 while ((worker = first_worker(pool)))
3513 destroy_worker(worker);
3514 WARN_ON(pool->nr_workers || pool->nr_idle);
3516 spin_unlock_irq(&pool->lock);
3517 mutex_unlock(&pool->manager_mutex);
3518 mutex_unlock(&pool->manager_arb);
3520 /* shut down the timers */
3521 del_timer_sync(&pool->idle_timer);
3522 del_timer_sync(&pool->mayday_timer);
3524 /* sched-RCU protected to allow dereferences from get_work_pool() */
3525 call_rcu_sched(&pool->rcu, rcu_free_pool);
3529 * get_unbound_pool - get a worker_pool with the specified attributes
3530 * @attrs: the attributes of the worker_pool to get
3532 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3533 * reference count and return it. If there already is a matching
3534 * worker_pool, it will be used; otherwise, this function attempts to
3535 * create a new one. On failure, returns NULL.
3537 * Should be called with wq_pool_mutex held.
3539 static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs)
3541 u32 hash = wqattrs_hash(attrs);
3542 struct worker_pool *pool;
3545 lockdep_assert_held(&wq_pool_mutex);
3547 /* do we already have a matching pool? */
3548 hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
3549 if (wqattrs_equal(pool->attrs, attrs)) {
3555 /* nope, create a new one */
3556 pool = kzalloc(sizeof(*pool), GFP_KERNEL);
3557 if (!pool || init_worker_pool(pool) < 0)
3560 if (workqueue_freezing)
3561 pool->flags |= POOL_FREEZING;
3563 lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
3564 copy_workqueue_attrs(pool->attrs, attrs);
3566 /* if cpumask is contained inside a NUMA node, we belong to that node */
3567 if (wq_numa_enabled) {
3568 for_each_node(node) {
3569 if (cpumask_subset(pool->attrs->cpumask,
3570 wq_numa_possible_cpumask[node])) {
3577 if (worker_pool_assign_id(pool) < 0)
3580 /* create and start the initial worker */
3581 if (create_and_start_worker(pool) < 0)
3585 hash_add(unbound_pool_hash, &pool->hash_node, hash);
3590 put_unbound_pool(pool);
3594 static void rcu_free_pwq(struct rcu_head *rcu)
3596 kmem_cache_free(pwq_cache,
3597 container_of(rcu, struct pool_workqueue, rcu));
3601 * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3602 * and needs to be destroyed.
3604 static void pwq_unbound_release_workfn(struct work_struct *work)
3606 struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
3607 unbound_release_work);
3608 struct workqueue_struct *wq = pwq->wq;
3609 struct worker_pool *pool = pwq->pool;
3612 if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
3616 * Unlink @pwq. Synchronization against wq->mutex isn't strictly
3617 * necessary on release but do it anyway. It's easier to verify
3618 * and consistent with the linking path.
3620 mutex_lock(&wq->mutex);
3621 list_del_rcu(&pwq->pwqs_node);
3622 is_last = list_empty(&wq->pwqs);
3623 mutex_unlock(&wq->mutex);
3625 mutex_lock(&wq_pool_mutex);
3626 put_unbound_pool(pool);
3627 mutex_unlock(&wq_pool_mutex);
3629 call_rcu_sched(&pwq->rcu, rcu_free_pwq);
3632 * If we're the last pwq going away, @wq is already dead and no one
3633 * is gonna access it anymore. Free it.
3636 free_workqueue_attrs(wq->unbound_attrs);
3642 * pwq_adjust_max_active - update a pwq's max_active to the current setting
3643 * @pwq: target pool_workqueue
3645 * If @pwq isn't freezing, set @pwq->max_active to the associated
3646 * workqueue's saved_max_active and activate delayed work items
3647 * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
3649 static void pwq_adjust_max_active(struct pool_workqueue *pwq)
3651 struct workqueue_struct *wq = pwq->wq;
3652 bool freezable = wq->flags & WQ_FREEZABLE;
3654 /* for @wq->saved_max_active */
3655 lockdep_assert_held(&wq->mutex);
3657 /* fast exit for non-freezable wqs */
3658 if (!freezable && pwq->max_active == wq->saved_max_active)
3661 spin_lock_irq(&pwq->pool->lock);
3663 if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) {
3664 pwq->max_active = wq->saved_max_active;
3666 while (!list_empty(&pwq->delayed_works) &&
3667 pwq->nr_active < pwq->max_active)
3668 pwq_activate_first_delayed(pwq);
3671 * Need to kick a worker after thawed or an unbound wq's
3672 * max_active is bumped. It's a slow path. Do it always.
3674 wake_up_worker(pwq->pool);
3676 pwq->max_active = 0;
3679 spin_unlock_irq(&pwq->pool->lock);
3682 /* initialize newly alloced @pwq which is associated with @wq and @pool */
3683 static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq,
3684 struct worker_pool *pool)
3686 BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
3688 memset(pwq, 0, sizeof(*pwq));
3692 pwq->flush_color = -1;
3694 INIT_LIST_HEAD(&pwq->delayed_works);
3695 INIT_LIST_HEAD(&pwq->pwqs_node);
3696 INIT_LIST_HEAD(&pwq->mayday_node);
3697 INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
3700 /* sync @pwq with the current state of its associated wq and link it */
3701 static void link_pwq(struct pool_workqueue *pwq)
3703 struct workqueue_struct *wq = pwq->wq;
3705 lockdep_assert_held(&wq->mutex);
3707 /* may be called multiple times, ignore if already linked */
3708 if (!list_empty(&pwq->pwqs_node))
3712 * Set the matching work_color. This is synchronized with
3713 * wq->mutex to avoid confusing flush_workqueue().
3715 pwq->work_color = wq->work_color;
3717 /* sync max_active to the current setting */
3718 pwq_adjust_max_active(pwq);
3721 list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
3724 /* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3725 static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq,
3726 const struct workqueue_attrs *attrs)
3728 struct worker_pool *pool;
3729 struct pool_workqueue *pwq;
3731 lockdep_assert_held(&wq_pool_mutex);
3733 pool = get_unbound_pool(attrs);
3737 pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
3739 put_unbound_pool(pool);
3743 init_pwq(pwq, wq, pool);
3747 /* undo alloc_unbound_pwq(), used only in the error path */
3748 static void free_unbound_pwq(struct pool_workqueue *pwq)
3750 lockdep_assert_held(&wq_pool_mutex);
3753 put_unbound_pool(pwq->pool);
3759 * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node
3760 * @attrs: the wq_attrs of interest
3761 * @node: the target NUMA node
3762 * @cpu_going_down: if >= 0, the CPU to consider as offline
3763 * @cpumask: outarg, the resulting cpumask
3765 * Calculate the cpumask a workqueue with @attrs should use on @node. If
3766 * @cpu_going_down is >= 0, that cpu is considered offline during
3767 * calculation. The result is stored in @cpumask. This function returns
3768 * %true if the resulting @cpumask is different from @attrs->cpumask,
3771 * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3772 * enabled and @node has online CPUs requested by @attrs, the returned
3773 * cpumask is the intersection of the possible CPUs of @node and
3776 * The caller is responsible for ensuring that the cpumask of @node stays
3779 static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
3780 int cpu_going_down, cpumask_t *cpumask)
3782 if (!wq_numa_enabled || attrs->no_numa)
3785 /* does @node have any online CPUs @attrs wants? */
3786 cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask);
3787 if (cpu_going_down >= 0)
3788 cpumask_clear_cpu(cpu_going_down, cpumask);
3790 if (cpumask_empty(cpumask))
3793 /* yeap, return possible CPUs in @node that @attrs wants */
3794 cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
3795 return !cpumask_equal(cpumask, attrs->cpumask);
3798 cpumask_copy(cpumask, attrs->cpumask);
3802 /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3803 static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq,
3805 struct pool_workqueue *pwq)
3807 struct pool_workqueue *old_pwq;
3809 lockdep_assert_held(&wq->mutex);
3811 /* link_pwq() can handle duplicate calls */
3814 old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
3815 rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
3820 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
3821 * @wq: the target workqueue
3822 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
3824 * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
3825 * machines, this function maps a separate pwq to each NUMA node with
3826 * possibles CPUs in @attrs->cpumask so that work items are affine to the
3827 * NUMA node it was issued on. Older pwqs are released as in-flight work
3828 * items finish. Note that a work item which repeatedly requeues itself
3829 * back-to-back will stay on its current pwq.
3831 * Performs GFP_KERNEL allocations. Returns 0 on success and -errno on
3834 int apply_workqueue_attrs(struct workqueue_struct *wq,
3835 const struct workqueue_attrs *attrs)
3837 struct workqueue_attrs *new_attrs, *tmp_attrs;
3838 struct pool_workqueue **pwq_tbl, *dfl_pwq;
3841 /* only unbound workqueues can change attributes */
3842 if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
3845 /* creating multiple pwqs breaks ordering guarantee */
3846 if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
3849 pwq_tbl = kzalloc(wq_numa_tbl_len * sizeof(pwq_tbl[0]), GFP_KERNEL);
3850 new_attrs = alloc_workqueue_attrs(GFP_KERNEL);
3851 tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL);
3852 if (!pwq_tbl || !new_attrs || !tmp_attrs)
3855 /* make a copy of @attrs and sanitize it */
3856 copy_workqueue_attrs(new_attrs, attrs);
3857 cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
3860 * We may create multiple pwqs with differing cpumasks. Make a
3861 * copy of @new_attrs which will be modified and used to obtain
3864 copy_workqueue_attrs(tmp_attrs, new_attrs);
3867 * CPUs should stay stable across pwq creations and installations.
3868 * Pin CPUs, determine the target cpumask for each node and create
3873 mutex_lock(&wq_pool_mutex);
3876 * If something goes wrong during CPU up/down, we'll fall back to
3877 * the default pwq covering whole @attrs->cpumask. Always create
3878 * it even if we don't use it immediately.
3880 dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
3884 for_each_node(node) {
3885 if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) {
3886 pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
3891 pwq_tbl[node] = dfl_pwq;
3895 mutex_unlock(&wq_pool_mutex);
3897 /* all pwqs have been created successfully, let's install'em */
3898 mutex_lock(&wq->mutex);
3900 copy_workqueue_attrs(wq->unbound_attrs, new_attrs);
3902 /* save the previous pwq and install the new one */
3904 pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]);
3906 /* @dfl_pwq might not have been used, ensure it's linked */
3908 swap(wq->dfl_pwq, dfl_pwq);
3910 mutex_unlock(&wq->mutex);
3912 /* put the old pwqs */
3914 put_pwq_unlocked(pwq_tbl[node]);
3915 put_pwq_unlocked(dfl_pwq);
3921 free_workqueue_attrs(tmp_attrs);
3922 free_workqueue_attrs(new_attrs);
3927 free_unbound_pwq(dfl_pwq);
3929 if (pwq_tbl && pwq_tbl[node] != dfl_pwq)
3930 free_unbound_pwq(pwq_tbl[node]);
3931 mutex_unlock(&wq_pool_mutex);
3939 * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
3940 * @wq: the target workqueue
3941 * @cpu: the CPU coming up or going down
3942 * @online: whether @cpu is coming up or going down
3944 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
3945 * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
3948 * If NUMA affinity can't be adjusted due to memory allocation failure, it
3949 * falls back to @wq->dfl_pwq which may not be optimal but is always
3952 * Note that when the last allowed CPU of a NUMA node goes offline for a
3953 * workqueue with a cpumask spanning multiple nodes, the workers which were
3954 * already executing the work items for the workqueue will lose their CPU
3955 * affinity and may execute on any CPU. This is similar to how per-cpu
3956 * workqueues behave on CPU_DOWN. If a workqueue user wants strict
3957 * affinity, it's the user's responsibility to flush the work item from
3960 static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
3963 int node = cpu_to_node(cpu);
3964 int cpu_off = online ? -1 : cpu;
3965 struct pool_workqueue *old_pwq = NULL, *pwq;
3966 struct workqueue_attrs *target_attrs;
3969 lockdep_assert_held(&wq_pool_mutex);
3971 if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND))
3975 * We don't wanna alloc/free wq_attrs for each wq for each CPU.
3976 * Let's use a preallocated one. The following buf is protected by
3977 * CPU hotplug exclusion.
3979 target_attrs = wq_update_unbound_numa_attrs_buf;
3980 cpumask = target_attrs->cpumask;
3982 mutex_lock(&wq->mutex);
3983 if (wq->unbound_attrs->no_numa)
3986 copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
3987 pwq = unbound_pwq_by_node(wq, node);
3990 * Let's determine what needs to be done. If the target cpumask is
3991 * different from wq's, we need to compare it to @pwq's and create
3992 * a new one if they don't match. If the target cpumask equals
3993 * wq's, the default pwq should be used. If @pwq is already the
3994 * default one, nothing to do; otherwise, install the default one.
3996 if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) {
3997 if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
4000 if (pwq == wq->dfl_pwq)
4006 mutex_unlock(&wq->mutex);
4008 /* create a new pwq */
4009 pwq = alloc_unbound_pwq(wq, target_attrs);
4011 pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
4017 * Install the new pwq. As this function is called only from CPU
4018 * hotplug callbacks and applying a new attrs is wrapped with
4019 * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
4022 mutex_lock(&wq->mutex);
4023 old_pwq = numa_pwq_tbl_install(wq, node, pwq);
4027 spin_lock_irq(&wq->dfl_pwq->pool->lock);
4028 get_pwq(wq->dfl_pwq);
4029 spin_unlock_irq(&wq->dfl_pwq->pool->lock);
4030 old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
4032 mutex_unlock(&wq->mutex);
4033 put_pwq_unlocked(old_pwq);
4036 static int alloc_and_link_pwqs(struct workqueue_struct *wq)
4038 bool highpri = wq->flags & WQ_HIGHPRI;
4041 if (!(wq->flags & WQ_UNBOUND)) {
4042 wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
4046 for_each_possible_cpu(cpu) {
4047 struct pool_workqueue *pwq =
4048 per_cpu_ptr(wq->cpu_pwqs, cpu);
4049 struct worker_pool *cpu_pools =
4050 per_cpu(cpu_worker_pools, cpu);
4052 init_pwq(pwq, wq, &cpu_pools[highpri]);
4054 mutex_lock(&wq->mutex);
4056 mutex_unlock(&wq->mutex);
4060 return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
4064 static int wq_clamp_max_active(int max_active, unsigned int flags,
4067 int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
4069 if (max_active < 1 || max_active > lim)
4070 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
4071 max_active, name, 1, lim);
4073 return clamp_val(max_active, 1, lim);
4076 struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
4079 struct lock_class_key *key,
4080 const char *lock_name, ...)
4082 size_t tbl_size = 0;
4084 struct workqueue_struct *wq;
4085 struct pool_workqueue *pwq;
4087 /* allocate wq and format name */
4088 if (flags & WQ_UNBOUND)
4089 tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]);
4091 wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL);
4095 if (flags & WQ_UNBOUND) {
4096 wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL);
4097 if (!wq->unbound_attrs)
4101 va_start(args, lock_name);
4102 vsnprintf(wq->name, sizeof(wq->name), fmt, args);
4105 max_active = max_active ?: WQ_DFL_ACTIVE;
4106 max_active = wq_clamp_max_active(max_active, flags, wq->name);
4110 wq->saved_max_active = max_active;
4111 mutex_init(&wq->mutex);
4112 atomic_set(&wq->nr_pwqs_to_flush, 0);
4113 INIT_LIST_HEAD(&wq->pwqs);
4114 INIT_LIST_HEAD(&wq->flusher_queue);
4115 INIT_LIST_HEAD(&wq->flusher_overflow);
4116 INIT_LIST_HEAD(&wq->maydays);
4118 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
4119 INIT_LIST_HEAD(&wq->list);
4121 if (alloc_and_link_pwqs(wq) < 0)
4125 * Workqueues which may be used during memory reclaim should
4126 * have a rescuer to guarantee forward progress.
4128 if (flags & WQ_MEM_RECLAIM) {
4129 struct worker *rescuer;
4131 rescuer = alloc_worker();
4135 rescuer->rescue_wq = wq;
4136 rescuer->task = kthread_create(rescuer_thread, rescuer, "%s",
4138 if (IS_ERR(rescuer->task)) {
4143 wq->rescuer = rescuer;
4144 rescuer->task->flags |= PF_NO_SETAFFINITY;
4145 wake_up_process(rescuer->task);
4148 if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
4152 * wq_pool_mutex protects global freeze state and workqueues list.
4153 * Grab it, adjust max_active and add the new @wq to workqueues
4156 mutex_lock(&wq_pool_mutex);
4158 mutex_lock(&wq->mutex);
4159 for_each_pwq(pwq, wq)
4160 pwq_adjust_max_active(pwq);
4161 mutex_unlock(&wq->mutex);
4163 list_add(&wq->list, &workqueues);
4165 mutex_unlock(&wq_pool_mutex);
4170 free_workqueue_attrs(wq->unbound_attrs);
4174 destroy_workqueue(wq);
4177 EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
4180 * destroy_workqueue - safely terminate a workqueue
4181 * @wq: target workqueue
4183 * Safely destroy a workqueue. All work currently pending will be done first.
4185 void destroy_workqueue(struct workqueue_struct *wq)
4187 struct pool_workqueue *pwq;
4190 /* drain it before proceeding with destruction */
4191 drain_workqueue(wq);
4194 mutex_lock(&wq->mutex);
4195 for_each_pwq(pwq, wq) {
4198 for (i = 0; i < WORK_NR_COLORS; i++) {
4199 if (WARN_ON(pwq->nr_in_flight[i])) {
4200 mutex_unlock(&wq->mutex);
4205 if (WARN_ON(pwq->refcnt > 1) ||
4206 WARN_ON(pwq->nr_active) ||
4207 WARN_ON(!list_empty(&pwq->delayed_works))) {
4208 mutex_unlock(&wq->mutex);
4212 mutex_unlock(&wq->mutex);
4215 * wq list is used to freeze wq, remove from list after
4216 * flushing is complete in case freeze races us.
4218 mutex_lock(&wq_pool_mutex);
4219 list_del_init(&wq->list);
4220 mutex_unlock(&wq_pool_mutex);
4222 workqueue_sysfs_unregister(wq);
4225 kthread_stop(wq->rescuer->task);
4230 if (!(wq->flags & WQ_UNBOUND)) {
4232 * The base ref is never dropped on per-cpu pwqs. Directly
4233 * free the pwqs and wq.
4235 free_percpu(wq->cpu_pwqs);
4239 * We're the sole accessor of @wq at this point. Directly
4240 * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
4241 * @wq will be freed when the last pwq is released.
4243 for_each_node(node) {
4244 pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
4245 RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL);
4246 put_pwq_unlocked(pwq);
4250 * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
4251 * put. Don't access it afterwards.
4255 put_pwq_unlocked(pwq);
4258 EXPORT_SYMBOL_GPL(destroy_workqueue);
4261 * workqueue_set_max_active - adjust max_active of a workqueue
4262 * @wq: target workqueue
4263 * @max_active: new max_active value.
4265 * Set max_active of @wq to @max_active.
4268 * Don't call from IRQ context.
4270 void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
4272 struct pool_workqueue *pwq;
4274 /* disallow meddling with max_active for ordered workqueues */
4275 if (WARN_ON(wq->flags & __WQ_ORDERED))
4278 max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
4280 mutex_lock(&wq->mutex);
4282 wq->saved_max_active = max_active;
4284 for_each_pwq(pwq, wq)
4285 pwq_adjust_max_active(pwq);
4287 mutex_unlock(&wq->mutex);
4289 EXPORT_SYMBOL_GPL(workqueue_set_max_active);
4292 * current_is_workqueue_rescuer - is %current workqueue rescuer?
4294 * Determine whether %current is a workqueue rescuer. Can be used from
4295 * work functions to determine whether it's being run off the rescuer task.
4297 bool current_is_workqueue_rescuer(void)
4299 struct worker *worker = current_wq_worker();
4301 return worker && worker->rescue_wq;
4305 * workqueue_congested - test whether a workqueue is congested
4306 * @cpu: CPU in question
4307 * @wq: target workqueue
4309 * Test whether @wq's cpu workqueue for @cpu is congested. There is
4310 * no synchronization around this function and the test result is
4311 * unreliable and only useful as advisory hints or for debugging.
4314 * %true if congested, %false otherwise.
4316 bool workqueue_congested(int cpu, struct workqueue_struct *wq)
4318 struct pool_workqueue *pwq;
4321 rcu_read_lock_sched();
4323 if (!(wq->flags & WQ_UNBOUND))
4324 pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
4326 pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
4328 ret = !list_empty(&pwq->delayed_works);
4329 rcu_read_unlock_sched();
4333 EXPORT_SYMBOL_GPL(workqueue_congested);
4336 * work_busy - test whether a work is currently pending or running
4337 * @work: the work to be tested
4339 * Test whether @work is currently pending or running. There is no
4340 * synchronization around this function and the test result is
4341 * unreliable and only useful as advisory hints or for debugging.
4344 * OR'd bitmask of WORK_BUSY_* bits.
4346 unsigned int work_busy(struct work_struct *work)
4348 struct worker_pool *pool;
4349 unsigned long flags;
4350 unsigned int ret = 0;
4352 if (work_pending(work))
4353 ret |= WORK_BUSY_PENDING;
4355 local_irq_save(flags);
4356 pool = get_work_pool(work);
4358 spin_lock(&pool->lock);
4359 if (find_worker_executing_work(pool, work))
4360 ret |= WORK_BUSY_RUNNING;
4361 spin_unlock(&pool->lock);
4363 local_irq_restore(flags);
4367 EXPORT_SYMBOL_GPL(work_busy);
4372 * There are two challenges in supporting CPU hotplug. Firstly, there
4373 * are a lot of assumptions on strong associations among work, pwq and
4374 * pool which make migrating pending and scheduled works very
4375 * difficult to implement without impacting hot paths. Secondly,
4376 * worker pools serve mix of short, long and very long running works making
4377 * blocked draining impractical.
4379 * This is solved by allowing the pools to be disassociated from the CPU
4380 * running as an unbound one and allowing it to be reattached later if the
4381 * cpu comes back online.
4384 static void wq_unbind_fn(struct work_struct *work)
4386 int cpu = smp_processor_id();
4387 struct worker_pool *pool;
4388 struct worker *worker;
4391 for_each_cpu_worker_pool(pool, cpu) {
4392 WARN_ON_ONCE(cpu != smp_processor_id());
4394 mutex_lock(&pool->manager_mutex);
4395 spin_lock_irq(&pool->lock);
4398 * We've blocked all manager operations. Make all workers
4399 * unbound and set DISASSOCIATED. Before this, all workers
4400 * except for the ones which are still executing works from
4401 * before the last CPU down must be on the cpu. After
4402 * this, they may become diasporas.
4404 for_each_pool_worker(worker, wi, pool)
4405 worker->flags |= WORKER_UNBOUND;
4407 pool->flags |= POOL_DISASSOCIATED;
4409 spin_unlock_irq(&pool->lock);
4410 mutex_unlock(&pool->manager_mutex);
4414 * Call schedule() so that we cross rq->lock and thus can guarantee
4415 * sched callbacks see the %WORKER_UNBOUND flag. This is necessary
4416 * as scheduler callbacks may be invoked from other cpus.
4421 * Sched callbacks are disabled now. Zap nr_running. After this,
4422 * nr_running stays zero and need_more_worker() and keep_working()
4423 * are always true as long as the worklist is not empty. Pools on
4424 * @cpu now behave as unbound (in terms of concurrency management)
4425 * pools which are served by workers tied to the CPU.
4427 * On return from this function, the current worker would trigger
4428 * unbound chain execution of pending work items if other workers
4431 for_each_cpu_worker_pool(pool, cpu)
4432 atomic_set(&pool->nr_running, 0);
4436 * rebind_workers - rebind all workers of a pool to the associated CPU
4437 * @pool: pool of interest
4439 * @pool->cpu is coming online. Rebind all workers to the CPU.
4441 static void rebind_workers(struct worker_pool *pool)
4443 struct worker *worker;
4446 lockdep_assert_held(&pool->manager_mutex);
4449 * Restore CPU affinity of all workers. As all idle workers should
4450 * be on the run-queue of the associated CPU before any local
4451 * wake-ups for concurrency management happen, restore CPU affinty
4452 * of all workers first and then clear UNBOUND. As we're called
4453 * from CPU_ONLINE, the following shouldn't fail.
4455 for_each_pool_worker(worker, wi, pool)
4456 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4457 pool->attrs->cpumask) < 0);
4459 spin_lock_irq(&pool->lock);
4461 for_each_pool_worker(worker, wi, pool) {
4462 unsigned int worker_flags = worker->flags;
4465 * A bound idle worker should actually be on the runqueue
4466 * of the associated CPU for local wake-ups targeting it to
4467 * work. Kick all idle workers so that they migrate to the
4468 * associated CPU. Doing this in the same loop as
4469 * replacing UNBOUND with REBOUND is safe as no worker will
4470 * be bound before @pool->lock is released.
4472 if (worker_flags & WORKER_IDLE)
4473 wake_up_process(worker->task);
4476 * We want to clear UNBOUND but can't directly call
4477 * worker_clr_flags() or adjust nr_running. Atomically
4478 * replace UNBOUND with another NOT_RUNNING flag REBOUND.
4479 * @worker will clear REBOUND using worker_clr_flags() when
4480 * it initiates the next execution cycle thus restoring
4481 * concurrency management. Note that when or whether
4482 * @worker clears REBOUND doesn't affect correctness.
4484 * ACCESS_ONCE() is necessary because @worker->flags may be
4485 * tested without holding any lock in
4486 * wq_worker_waking_up(). Without it, NOT_RUNNING test may
4487 * fail incorrectly leading to premature concurrency
4488 * management operations.
4490 WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
4491 worker_flags |= WORKER_REBOUND;
4492 worker_flags &= ~WORKER_UNBOUND;
4493 ACCESS_ONCE(worker->flags) = worker_flags;
4496 spin_unlock_irq(&pool->lock);
4500 * restore_unbound_workers_cpumask - restore cpumask of unbound workers
4501 * @pool: unbound pool of interest
4502 * @cpu: the CPU which is coming up
4504 * An unbound pool may end up with a cpumask which doesn't have any online
4505 * CPUs. When a worker of such pool get scheduled, the scheduler resets
4506 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4507 * online CPU before, cpus_allowed of all its workers should be restored.
4509 static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
4511 static cpumask_t cpumask;
4512 struct worker *worker;
4515 lockdep_assert_held(&pool->manager_mutex);
4517 /* is @cpu allowed for @pool? */
4518 if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
4521 /* is @cpu the only online CPU? */
4522 cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
4523 if (cpumask_weight(&cpumask) != 1)
4526 /* as we're called from CPU_ONLINE, the following shouldn't fail */
4527 for_each_pool_worker(worker, wi, pool)
4528 WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4529 pool->attrs->cpumask) < 0);
4533 * Workqueues should be brought up before normal priority CPU notifiers.
4534 * This will be registered high priority CPU notifier.
4536 static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb,
4537 unsigned long action,
4540 int cpu = (unsigned long)hcpu;
4541 struct worker_pool *pool;
4542 struct workqueue_struct *wq;
4545 switch (action & ~CPU_TASKS_FROZEN) {
4546 case CPU_UP_PREPARE:
4547 for_each_cpu_worker_pool(pool, cpu) {
4548 if (pool->nr_workers)
4550 if (create_and_start_worker(pool) < 0)
4555 case CPU_DOWN_FAILED:
4557 mutex_lock(&wq_pool_mutex);
4559 for_each_pool(pool, pi) {
4560 mutex_lock(&pool->manager_mutex);
4562 if (pool->cpu == cpu) {
4563 spin_lock_irq(&pool->lock);
4564 pool->flags &= ~POOL_DISASSOCIATED;
4565 spin_unlock_irq(&pool->lock);
4567 rebind_workers(pool);
4568 } else if (pool->cpu < 0) {
4569 restore_unbound_workers_cpumask(pool, cpu);
4572 mutex_unlock(&pool->manager_mutex);
4575 /* update NUMA affinity of unbound workqueues */
4576 list_for_each_entry(wq, &workqueues, list)
4577 wq_update_unbound_numa(wq, cpu, true);
4579 mutex_unlock(&wq_pool_mutex);
4586 * Workqueues should be brought down after normal priority CPU notifiers.
4587 * This will be registered as low priority CPU notifier.
4589 static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb,
4590 unsigned long action,
4593 int cpu = (unsigned long)hcpu;
4594 struct work_struct unbind_work;
4595 struct workqueue_struct *wq;
4597 switch (action & ~CPU_TASKS_FROZEN) {
4598 case CPU_DOWN_PREPARE:
4599 /* unbinding per-cpu workers should happen on the local CPU */
4600 INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
4601 queue_work_on(cpu, system_highpri_wq, &unbind_work);
4603 /* update NUMA affinity of unbound workqueues */
4604 mutex_lock(&wq_pool_mutex);
4605 list_for_each_entry(wq, &workqueues, list)
4606 wq_update_unbound_numa(wq, cpu, false);
4607 mutex_unlock(&wq_pool_mutex);
4609 /* wait for per-cpu unbinding to finish */
4610 flush_work(&unbind_work);
4618 struct work_for_cpu {
4619 struct work_struct work;
4625 static void work_for_cpu_fn(struct work_struct *work)
4627 struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
4629 wfc->ret = wfc->fn(wfc->arg);
4633 * work_on_cpu - run a function in user context on a particular cpu
4634 * @cpu: the cpu to run on
4635 * @fn: the function to run
4636 * @arg: the function arg
4638 * This will return the value @fn returns.
4639 * It is up to the caller to ensure that the cpu doesn't go offline.
4640 * The caller must not hold any locks which would prevent @fn from completing.
4642 long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
4644 struct work_for_cpu wfc = { .fn = fn, .arg = arg };
4646 INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
4647 schedule_work_on(cpu, &wfc.work);
4648 flush_work(&wfc.work);
4651 EXPORT_SYMBOL_GPL(work_on_cpu);
4652 #endif /* CONFIG_SMP */
4654 #ifdef CONFIG_FREEZER
4657 * freeze_workqueues_begin - begin freezing workqueues
4659 * Start freezing workqueues. After this function returns, all freezable
4660 * workqueues will queue new works to their delayed_works list instead of
4664 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4666 void freeze_workqueues_begin(void)
4668 struct worker_pool *pool;
4669 struct workqueue_struct *wq;
4670 struct pool_workqueue *pwq;
4673 mutex_lock(&wq_pool_mutex);
4675 WARN_ON_ONCE(workqueue_freezing);
4676 workqueue_freezing = true;
4679 for_each_pool(pool, pi) {
4680 spin_lock_irq(&pool->lock);
4681 WARN_ON_ONCE(pool->flags & POOL_FREEZING);
4682 pool->flags |= POOL_FREEZING;
4683 spin_unlock_irq(&pool->lock);
4686 list_for_each_entry(wq, &workqueues, list) {
4687 mutex_lock(&wq->mutex);
4688 for_each_pwq(pwq, wq)
4689 pwq_adjust_max_active(pwq);
4690 mutex_unlock(&wq->mutex);
4693 mutex_unlock(&wq_pool_mutex);
4697 * freeze_workqueues_busy - are freezable workqueues still busy?
4699 * Check whether freezing is complete. This function must be called
4700 * between freeze_workqueues_begin() and thaw_workqueues().
4703 * Grabs and releases wq_pool_mutex.
4706 * %true if some freezable workqueues are still busy. %false if freezing
4709 bool freeze_workqueues_busy(void)
4712 struct workqueue_struct *wq;
4713 struct pool_workqueue *pwq;
4715 mutex_lock(&wq_pool_mutex);
4717 WARN_ON_ONCE(!workqueue_freezing);
4719 list_for_each_entry(wq, &workqueues, list) {
4720 if (!(wq->flags & WQ_FREEZABLE))
4723 * nr_active is monotonically decreasing. It's safe
4724 * to peek without lock.
4726 rcu_read_lock_sched();
4727 for_each_pwq(pwq, wq) {
4728 WARN_ON_ONCE(pwq->nr_active < 0);
4729 if (pwq->nr_active) {
4731 rcu_read_unlock_sched();
4735 rcu_read_unlock_sched();
4738 mutex_unlock(&wq_pool_mutex);
4743 * thaw_workqueues - thaw workqueues
4745 * Thaw workqueues. Normal queueing is restored and all collected
4746 * frozen works are transferred to their respective pool worklists.
4749 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4751 void thaw_workqueues(void)
4753 struct workqueue_struct *wq;
4754 struct pool_workqueue *pwq;
4755 struct worker_pool *pool;
4758 mutex_lock(&wq_pool_mutex);
4760 if (!workqueue_freezing)
4763 /* clear FREEZING */
4764 for_each_pool(pool, pi) {
4765 spin_lock_irq(&pool->lock);
4766 WARN_ON_ONCE(!(pool->flags & POOL_FREEZING));
4767 pool->flags &= ~POOL_FREEZING;
4768 spin_unlock_irq(&pool->lock);
4771 /* restore max_active and repopulate worklist */
4772 list_for_each_entry(wq, &workqueues, list) {
4773 mutex_lock(&wq->mutex);
4774 for_each_pwq(pwq, wq)
4775 pwq_adjust_max_active(pwq);
4776 mutex_unlock(&wq->mutex);
4779 workqueue_freezing = false;
4781 mutex_unlock(&wq_pool_mutex);
4783 #endif /* CONFIG_FREEZER */
4785 static void __init wq_numa_init(void)
4790 /* determine NUMA pwq table len - highest node id + 1 */
4792 wq_numa_tbl_len = max(wq_numa_tbl_len, node + 1);
4794 if (num_possible_nodes() <= 1)
4797 if (wq_disable_numa) {
4798 pr_info("workqueue: NUMA affinity support disabled\n");
4802 wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL);
4803 BUG_ON(!wq_update_unbound_numa_attrs_buf);
4806 * We want masks of possible CPUs of each node which isn't readily
4807 * available. Build one from cpu_to_node() which should have been
4808 * fully initialized by now.
4810 tbl = kzalloc(wq_numa_tbl_len * sizeof(tbl[0]), GFP_KERNEL);
4814 BUG_ON(!alloc_cpumask_var_node(&tbl[node], GFP_KERNEL, node));
4816 for_each_possible_cpu(cpu) {
4817 node = cpu_to_node(cpu);
4818 if (WARN_ON(node == NUMA_NO_NODE)) {
4819 pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
4820 /* happens iff arch is bonkers, let's just proceed */
4823 cpumask_set_cpu(cpu, tbl[node]);
4826 wq_numa_possible_cpumask = tbl;
4827 wq_numa_enabled = true;
4830 static int __init init_workqueues(void)
4832 int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
4835 /* make sure we have enough bits for OFFQ pool ID */
4836 BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) <
4837 WORK_CPU_END * NR_STD_WORKER_POOLS);
4839 WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
4841 pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
4843 cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
4844 hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
4848 /* initialize CPU pools */
4849 for_each_possible_cpu(cpu) {
4850 struct worker_pool *pool;
4853 for_each_cpu_worker_pool(pool, cpu) {
4854 BUG_ON(init_worker_pool(pool));
4856 cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
4857 pool->attrs->nice = std_nice[i++];
4858 pool->node = cpu_to_node(cpu);
4861 mutex_lock(&wq_pool_mutex);
4862 BUG_ON(worker_pool_assign_id(pool));
4863 mutex_unlock(&wq_pool_mutex);
4867 /* create the initial worker */
4868 for_each_online_cpu(cpu) {
4869 struct worker_pool *pool;
4871 for_each_cpu_worker_pool(pool, cpu) {
4872 pool->flags &= ~POOL_DISASSOCIATED;
4873 BUG_ON(create_and_start_worker(pool) < 0);
4877 /* create default unbound wq attrs */
4878 for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
4879 struct workqueue_attrs *attrs;
4881 BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL)));
4882 attrs->nice = std_nice[i];
4883 unbound_std_wq_attrs[i] = attrs;
4886 system_wq = alloc_workqueue("events", 0, 0);
4887 system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
4888 system_long_wq = alloc_workqueue("events_long", 0, 0);
4889 system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
4890 WQ_UNBOUND_MAX_ACTIVE);
4891 system_freezable_wq = alloc_workqueue("events_freezable",
4893 BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||
4894 !system_unbound_wq || !system_freezable_wq);
4897 early_initcall(init_workqueues);