2 * kernel/workqueue.c - generic async execution with shared worker pool
4 * Copyright (C) 2002 Ingo Molnar
6 * Derived from the taskqueue/keventd code by:
7 * David Woodhouse <dwmw2@infradead.org>
9 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
10 * Theodore Ts'o <tytso@mit.edu>
12 * Made to use alloc_percpu by Christoph Lameter.
14 * Copyright (C) 2010 SUSE Linux Products GmbH
15 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
17 * This is the generic async execution mechanism. Work items as are
18 * executed in process context. The worker pool is shared and
19 * automatically managed. There are two worker pools for each CPU (one for
20 * normal work items and the other for high priority ones) and some extra
21 * pools for workqueues which are not bound to any specific CPU - the
22 * number of these backing pools is dynamic.
24 * Please read Documentation/core-api/workqueue.rst for details.
27 #include <linux/export.h>
28 #include <linux/kernel.h>
29 #include <linux/sched.h>
30 #include <linux/init.h>
31 #include <linux/signal.h>
32 #include <linux/completion.h>
33 #include <linux/workqueue.h>
34 #include <linux/slab.h>
35 #include <linux/cpu.h>
36 #include <linux/notifier.h>
37 #include <linux/kthread.h>
38 #include <linux/hardirq.h>
39 #include <linux/mempolicy.h>
40 #include <linux/freezer.h>
41 #include <linux/debug_locks.h>
42 #include <linux/lockdep.h>
43 #include <linux/idr.h>
44 #include <linux/jhash.h>
45 #include <linux/hashtable.h>
46 #include <linux/rculist.h>
47 #include <linux/nodemask.h>
48 #include <linux/moduleparam.h>
49 #include <linux/uaccess.h>
50 #include <linux/sched/isolation.h>
51 #include <linux/nmi.h>
53 #include "workqueue_internal.h"
59 * A bound pool is either associated or disassociated with its CPU.
60 * While associated (!DISASSOCIATED), all workers are bound to the
61 * CPU and none has %WORKER_UNBOUND set and concurrency management
64 * While DISASSOCIATED, the cpu may be offline and all workers have
65 * %WORKER_UNBOUND set and concurrency management disabled, and may
66 * be executing on any CPU. The pool behaves as an unbound one.
68 * Note that DISASSOCIATED should be flipped only while holding
69 * attach_mutex to avoid changing binding state while
70 * worker_attach_to_pool() is in progress.
72 POOL_MANAGER_ACTIVE
= 1 << 0, /* being managed */
73 POOL_DISASSOCIATED
= 1 << 2, /* cpu can't serve workers */
76 WORKER_DIE
= 1 << 1, /* die die die */
77 WORKER_IDLE
= 1 << 2, /* is idle */
78 WORKER_PREP
= 1 << 3, /* preparing to run works */
79 WORKER_CPU_INTENSIVE
= 1 << 6, /* cpu intensive */
80 WORKER_UNBOUND
= 1 << 7, /* worker is unbound */
81 WORKER_REBOUND
= 1 << 8, /* worker was rebound */
83 WORKER_NOT_RUNNING
= WORKER_PREP
| WORKER_CPU_INTENSIVE
|
84 WORKER_UNBOUND
| WORKER_REBOUND
,
86 NR_STD_WORKER_POOLS
= 2, /* # standard pools per cpu */
88 UNBOUND_POOL_HASH_ORDER
= 6, /* hashed by pool->attrs */
89 BUSY_WORKER_HASH_ORDER
= 6, /* 64 pointers */
91 MAX_IDLE_WORKERS_RATIO
= 4, /* 1/4 of busy can be idle */
92 IDLE_WORKER_TIMEOUT
= 300 * HZ
, /* keep idle ones for 5 mins */
94 MAYDAY_INITIAL_TIMEOUT
= HZ
/ 100 >= 2 ? HZ
/ 100 : 2,
95 /* call for help after 10ms
97 MAYDAY_INTERVAL
= HZ
/ 10, /* and then every 100ms */
98 CREATE_COOLDOWN
= HZ
, /* time to breath after fail */
101 * Rescue workers are used only on emergencies and shared by
102 * all cpus. Give MIN_NICE.
104 RESCUER_NICE_LEVEL
= MIN_NICE
,
105 HIGHPRI_NICE_LEVEL
= MIN_NICE
,
111 * Structure fields follow one of the following exclusion rules.
113 * I: Modifiable by initialization/destruction paths and read-only for
116 * P: Preemption protected. Disabling preemption is enough and should
117 * only be modified and accessed from the local cpu.
119 * L: pool->lock protected. Access with pool->lock held.
121 * X: During normal operation, modification requires pool->lock and should
122 * be done only from local cpu. Either disabling preemption on local
123 * cpu or grabbing pool->lock is enough for read access. If
124 * POOL_DISASSOCIATED is set, it's identical to L.
126 * A: pool->attach_mutex protected.
128 * PL: wq_pool_mutex protected.
130 * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
132 * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads.
134 * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or
135 * sched-RCU for reads.
137 * WQ: wq->mutex protected.
139 * WR: wq->mutex protected for writes. Sched-RCU protected for reads.
141 * MD: wq_mayday_lock protected.
144 /* struct worker is defined in workqueue_internal.h */
147 spinlock_t lock
; /* the pool lock */
148 int cpu
; /* I: the associated cpu */
149 int node
; /* I: the associated node ID */
150 int id
; /* I: pool ID */
151 unsigned int flags
; /* X: flags */
153 unsigned long watchdog_ts
; /* L: watchdog timestamp */
155 struct list_head worklist
; /* L: list of pending works */
156 int nr_workers
; /* L: total number of workers */
158 /* nr_idle includes the ones off idle_list for rebinding */
159 int nr_idle
; /* L: currently idle ones */
161 struct list_head idle_list
; /* X: list of idle workers */
162 struct timer_list idle_timer
; /* L: worker idle timeout */
163 struct timer_list mayday_timer
; /* L: SOS timer for workers */
165 /* a workers is either on busy_hash or idle_list, or the manager */
166 DECLARE_HASHTABLE(busy_hash
, BUSY_WORKER_HASH_ORDER
);
167 /* L: hash of busy workers */
169 /* see manage_workers() for details on the two manager mutexes */
170 struct worker
*manager
; /* L: purely informational */
171 struct mutex attach_mutex
; /* attach/detach exclusion */
172 struct list_head workers
; /* A: attached workers */
173 struct completion
*detach_completion
; /* all workers detached */
175 struct ida worker_ida
; /* worker IDs for task name */
177 struct workqueue_attrs
*attrs
; /* I: worker attributes */
178 struct hlist_node hash_node
; /* PL: unbound_pool_hash node */
179 int refcnt
; /* PL: refcnt for unbound pools */
182 * The current concurrency level. As it's likely to be accessed
183 * from other CPUs during try_to_wake_up(), put it in a separate
186 atomic_t nr_running ____cacheline_aligned_in_smp
;
189 * Destruction of pool is sched-RCU protected to allow dereferences
190 * from get_work_pool().
193 } ____cacheline_aligned_in_smp
;
196 * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
197 * of work_struct->data are used for flags and the remaining high bits
198 * point to the pwq; thus, pwqs need to be aligned at two's power of the
199 * number of flag bits.
201 struct pool_workqueue
{
202 struct worker_pool
*pool
; /* I: the associated pool */
203 struct workqueue_struct
*wq
; /* I: the owning workqueue */
204 int work_color
; /* L: current color */
205 int flush_color
; /* L: flushing color */
206 int refcnt
; /* L: reference count */
207 int nr_in_flight
[WORK_NR_COLORS
];
208 /* L: nr of in_flight works */
209 int nr_active
; /* L: nr of active works */
210 int max_active
; /* L: max active works */
211 struct list_head delayed_works
; /* L: delayed works */
212 struct list_head pwqs_node
; /* WR: node on wq->pwqs */
213 struct list_head mayday_node
; /* MD: node on wq->maydays */
216 * Release of unbound pwq is punted to system_wq. See put_pwq()
217 * and pwq_unbound_release_workfn() for details. pool_workqueue
218 * itself is also sched-RCU protected so that the first pwq can be
219 * determined without grabbing wq->mutex.
221 struct work_struct unbound_release_work
;
223 } __aligned(1 << WORK_STRUCT_FLAG_BITS
);
226 * Structure used to wait for workqueue flush.
229 struct list_head list
; /* WQ: list of flushers */
230 int flush_color
; /* WQ: flush color waiting for */
231 struct completion done
; /* flush completion */
237 * The externally visible workqueue. It relays the issued work items to
238 * the appropriate worker_pool through its pool_workqueues.
240 struct workqueue_struct
{
241 struct list_head pwqs
; /* WR: all pwqs of this wq */
242 struct list_head list
; /* PR: list of all workqueues */
244 struct mutex mutex
; /* protects this wq */
245 int work_color
; /* WQ: current work color */
246 int flush_color
; /* WQ: current flush color */
247 atomic_t nr_pwqs_to_flush
; /* flush in progress */
248 struct wq_flusher
*first_flusher
; /* WQ: first flusher */
249 struct list_head flusher_queue
; /* WQ: flush waiters */
250 struct list_head flusher_overflow
; /* WQ: flush overflow list */
252 struct list_head maydays
; /* MD: pwqs requesting rescue */
253 struct worker
*rescuer
; /* I: rescue worker */
255 int nr_drainers
; /* WQ: drain in progress */
256 int saved_max_active
; /* WQ: saved pwq max_active */
258 struct workqueue_attrs
*unbound_attrs
; /* PW: only for unbound wqs */
259 struct pool_workqueue
*dfl_pwq
; /* PW: only for unbound wqs */
262 struct wq_device
*wq_dev
; /* I: for sysfs interface */
264 #ifdef CONFIG_LOCKDEP
265 struct lockdep_map lockdep_map
;
267 char name
[WQ_NAME_LEN
]; /* I: workqueue name */
270 * Destruction of workqueue_struct is sched-RCU protected to allow
271 * walking the workqueues list without grabbing wq_pool_mutex.
272 * This is used to dump all workqueues from sysrq.
276 /* hot fields used during command issue, aligned to cacheline */
277 unsigned int flags ____cacheline_aligned
; /* WQ: WQ_* flags */
278 struct pool_workqueue __percpu
*cpu_pwqs
; /* I: per-cpu pwqs */
279 struct pool_workqueue __rcu
*numa_pwq_tbl
[]; /* PWR: unbound pwqs indexed by node */
282 static struct kmem_cache
*pwq_cache
;
284 static cpumask_var_t
*wq_numa_possible_cpumask
;
285 /* possible CPUs of each node */
287 static bool wq_disable_numa
;
288 module_param_named(disable_numa
, wq_disable_numa
, bool, 0444);
290 /* see the comment above the definition of WQ_POWER_EFFICIENT */
291 static bool wq_power_efficient
= IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT
);
292 module_param_named(power_efficient
, wq_power_efficient
, bool, 0444);
294 static bool wq_online
; /* can kworkers be created yet? */
296 static bool wq_numa_enabled
; /* unbound NUMA affinity enabled */
298 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
299 static struct workqueue_attrs
*wq_update_unbound_numa_attrs_buf
;
301 static DEFINE_MUTEX(wq_pool_mutex
); /* protects pools and workqueues list */
302 static DEFINE_SPINLOCK(wq_mayday_lock
); /* protects wq->maydays list */
303 static DECLARE_WAIT_QUEUE_HEAD(wq_manager_wait
); /* wait for manager to go away */
305 static LIST_HEAD(workqueues
); /* PR: list of all workqueues */
306 static bool workqueue_freezing
; /* PL: have wqs started freezing? */
308 /* PL: allowable cpus for unbound wqs and work items */
309 static cpumask_var_t wq_unbound_cpumask
;
311 /* CPU where unbound work was last round robin scheduled from this CPU */
312 static DEFINE_PER_CPU(int, wq_rr_cpu_last
);
315 * Local execution of unbound work items is no longer guaranteed. The
316 * following always forces round-robin CPU selection on unbound work items
317 * to uncover usages which depend on it.
319 #ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU
320 static bool wq_debug_force_rr_cpu
= true;
322 static bool wq_debug_force_rr_cpu
= false;
324 module_param_named(debug_force_rr_cpu
, wq_debug_force_rr_cpu
, bool, 0644);
326 /* the per-cpu worker pools */
327 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool
[NR_STD_WORKER_POOLS
], cpu_worker_pools
);
329 static DEFINE_IDR(worker_pool_idr
); /* PR: idr of all pools */
331 /* PL: hash of all unbound pools keyed by pool->attrs */
332 static DEFINE_HASHTABLE(unbound_pool_hash
, UNBOUND_POOL_HASH_ORDER
);
334 /* I: attributes used when instantiating standard unbound pools on demand */
335 static struct workqueue_attrs
*unbound_std_wq_attrs
[NR_STD_WORKER_POOLS
];
337 /* I: attributes used when instantiating ordered pools on demand */
338 static struct workqueue_attrs
*ordered_wq_attrs
[NR_STD_WORKER_POOLS
];
340 struct workqueue_struct
*system_wq __read_mostly
;
341 EXPORT_SYMBOL(system_wq
);
342 struct workqueue_struct
*system_highpri_wq __read_mostly
;
343 EXPORT_SYMBOL_GPL(system_highpri_wq
);
344 struct workqueue_struct
*system_long_wq __read_mostly
;
345 EXPORT_SYMBOL_GPL(system_long_wq
);
346 struct workqueue_struct
*system_unbound_wq __read_mostly
;
347 EXPORT_SYMBOL_GPL(system_unbound_wq
);
348 struct workqueue_struct
*system_freezable_wq __read_mostly
;
349 EXPORT_SYMBOL_GPL(system_freezable_wq
);
350 struct workqueue_struct
*system_power_efficient_wq __read_mostly
;
351 EXPORT_SYMBOL_GPL(system_power_efficient_wq
);
352 struct workqueue_struct
*system_freezable_power_efficient_wq __read_mostly
;
353 EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq
);
355 static int worker_thread(void *__worker
);
356 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
);
358 #define CREATE_TRACE_POINTS
359 #include <trace/events/workqueue.h>
361 #define assert_rcu_or_pool_mutex() \
362 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held() && \
363 !lockdep_is_held(&wq_pool_mutex), \
364 "sched RCU or wq_pool_mutex should be held")
366 #define assert_rcu_or_wq_mutex(wq) \
367 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held() && \
368 !lockdep_is_held(&wq->mutex), \
369 "sched RCU or wq->mutex should be held")
371 #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \
372 RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held() && \
373 !lockdep_is_held(&wq->mutex) && \
374 !lockdep_is_held(&wq_pool_mutex), \
375 "sched RCU, wq->mutex or wq_pool_mutex should be held")
377 #define for_each_cpu_worker_pool(pool, cpu) \
378 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
379 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
383 * for_each_pool - iterate through all worker_pools in the system
384 * @pool: iteration cursor
385 * @pi: integer used for iteration
387 * This must be called either with wq_pool_mutex held or sched RCU read
388 * locked. If the pool needs to be used beyond the locking in effect, the
389 * caller is responsible for guaranteeing that the pool stays online.
391 * The if/else clause exists only for the lockdep assertion and can be
394 #define for_each_pool(pool, pi) \
395 idr_for_each_entry(&worker_pool_idr, pool, pi) \
396 if (({ assert_rcu_or_pool_mutex(); false; })) { } \
400 * for_each_pool_worker - iterate through all workers of a worker_pool
401 * @worker: iteration cursor
402 * @pool: worker_pool to iterate workers of
404 * This must be called with @pool->attach_mutex.
406 * The if/else clause exists only for the lockdep assertion and can be
409 #define for_each_pool_worker(worker, pool) \
410 list_for_each_entry((worker), &(pool)->workers, node) \
411 if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \
415 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
416 * @pwq: iteration cursor
417 * @wq: the target workqueue
419 * This must be called either with wq->mutex held or sched RCU read locked.
420 * If the pwq needs to be used beyond the locking in effect, the caller is
421 * responsible for guaranteeing that the pwq stays online.
423 * The if/else clause exists only for the lockdep assertion and can be
426 #define for_each_pwq(pwq, wq) \
427 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
428 if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
431 #ifdef CONFIG_DEBUG_OBJECTS_WORK
433 static struct debug_obj_descr work_debug_descr
;
435 static void *work_debug_hint(void *addr
)
437 return ((struct work_struct
*) addr
)->func
;
440 static bool work_is_static_object(void *addr
)
442 struct work_struct
*work
= addr
;
444 return test_bit(WORK_STRUCT_STATIC_BIT
, work_data_bits(work
));
448 * fixup_init is called when:
449 * - an active object is initialized
451 static bool work_fixup_init(void *addr
, enum debug_obj_state state
)
453 struct work_struct
*work
= addr
;
456 case ODEBUG_STATE_ACTIVE
:
457 cancel_work_sync(work
);
458 debug_object_init(work
, &work_debug_descr
);
466 * fixup_free is called when:
467 * - an active object is freed
469 static bool work_fixup_free(void *addr
, enum debug_obj_state state
)
471 struct work_struct
*work
= addr
;
474 case ODEBUG_STATE_ACTIVE
:
475 cancel_work_sync(work
);
476 debug_object_free(work
, &work_debug_descr
);
483 static struct debug_obj_descr work_debug_descr
= {
484 .name
= "work_struct",
485 .debug_hint
= work_debug_hint
,
486 .is_static_object
= work_is_static_object
,
487 .fixup_init
= work_fixup_init
,
488 .fixup_free
= work_fixup_free
,
491 static inline void debug_work_activate(struct work_struct
*work
)
493 debug_object_activate(work
, &work_debug_descr
);
496 static inline void debug_work_deactivate(struct work_struct
*work
)
498 debug_object_deactivate(work
, &work_debug_descr
);
501 void __init_work(struct work_struct
*work
, int onstack
)
504 debug_object_init_on_stack(work
, &work_debug_descr
);
506 debug_object_init(work
, &work_debug_descr
);
508 EXPORT_SYMBOL_GPL(__init_work
);
510 void destroy_work_on_stack(struct work_struct
*work
)
512 debug_object_free(work
, &work_debug_descr
);
514 EXPORT_SYMBOL_GPL(destroy_work_on_stack
);
516 void destroy_delayed_work_on_stack(struct delayed_work
*work
)
518 destroy_timer_on_stack(&work
->timer
);
519 debug_object_free(&work
->work
, &work_debug_descr
);
521 EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack
);
524 static inline void debug_work_activate(struct work_struct
*work
) { }
525 static inline void debug_work_deactivate(struct work_struct
*work
) { }
529 * worker_pool_assign_id - allocate ID and assing it to @pool
530 * @pool: the pool pointer of interest
532 * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
533 * successfully, -errno on failure.
535 static int worker_pool_assign_id(struct worker_pool
*pool
)
539 lockdep_assert_held(&wq_pool_mutex
);
541 ret
= idr_alloc(&worker_pool_idr
, pool
, 0, WORK_OFFQ_POOL_NONE
,
551 * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
552 * @wq: the target workqueue
555 * This must be called with any of wq_pool_mutex, wq->mutex or sched RCU
557 * If the pwq needs to be used beyond the locking in effect, the caller is
558 * responsible for guaranteeing that the pwq stays online.
560 * Return: The unbound pool_workqueue for @node.
562 static struct pool_workqueue
*unbound_pwq_by_node(struct workqueue_struct
*wq
,
565 assert_rcu_or_wq_mutex_or_pool_mutex(wq
);
568 * XXX: @node can be NUMA_NO_NODE if CPU goes offline while a
569 * delayed item is pending. The plan is to keep CPU -> NODE
570 * mapping valid and stable across CPU on/offlines. Once that
571 * happens, this workaround can be removed.
573 if (unlikely(node
== NUMA_NO_NODE
))
576 return rcu_dereference_raw(wq
->numa_pwq_tbl
[node
]);
579 static unsigned int work_color_to_flags(int color
)
581 return color
<< WORK_STRUCT_COLOR_SHIFT
;
584 static int get_work_color(struct work_struct
*work
)
586 return (*work_data_bits(work
) >> WORK_STRUCT_COLOR_SHIFT
) &
587 ((1 << WORK_STRUCT_COLOR_BITS
) - 1);
590 static int work_next_color(int color
)
592 return (color
+ 1) % WORK_NR_COLORS
;
596 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
597 * contain the pointer to the queued pwq. Once execution starts, the flag
598 * is cleared and the high bits contain OFFQ flags and pool ID.
600 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
601 * and clear_work_data() can be used to set the pwq, pool or clear
602 * work->data. These functions should only be called while the work is
603 * owned - ie. while the PENDING bit is set.
605 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
606 * corresponding to a work. Pool is available once the work has been
607 * queued anywhere after initialization until it is sync canceled. pwq is
608 * available only while the work item is queued.
610 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
611 * canceled. While being canceled, a work item may have its PENDING set
612 * but stay off timer and worklist for arbitrarily long and nobody should
613 * try to steal the PENDING bit.
615 static inline void set_work_data(struct work_struct
*work
, unsigned long data
,
618 WARN_ON_ONCE(!work_pending(work
));
619 atomic_long_set(&work
->data
, data
| flags
| work_static(work
));
622 static void set_work_pwq(struct work_struct
*work
, struct pool_workqueue
*pwq
,
623 unsigned long extra_flags
)
625 set_work_data(work
, (unsigned long)pwq
,
626 WORK_STRUCT_PENDING
| WORK_STRUCT_PWQ
| extra_flags
);
629 static void set_work_pool_and_keep_pending(struct work_struct
*work
,
632 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
,
633 WORK_STRUCT_PENDING
);
636 static void set_work_pool_and_clear_pending(struct work_struct
*work
,
640 * The following wmb is paired with the implied mb in
641 * test_and_set_bit(PENDING) and ensures all updates to @work made
642 * here are visible to and precede any updates by the next PENDING
646 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
, 0);
648 * The following mb guarantees that previous clear of a PENDING bit
649 * will not be reordered with any speculative LOADS or STORES from
650 * work->current_func, which is executed afterwards. This possible
651 * reordering can lead to a missed execution on attempt to qeueue
652 * the same @work. E.g. consider this case:
655 * ---------------------------- --------------------------------
657 * 1 STORE event_indicated
658 * 2 queue_work_on() {
659 * 3 test_and_set_bit(PENDING)
660 * 4 } set_..._and_clear_pending() {
661 * 5 set_work_data() # clear bit
663 * 7 work->current_func() {
664 * 8 LOAD event_indicated
667 * Without an explicit full barrier speculative LOAD on line 8 can
668 * be executed before CPU#0 does STORE on line 1. If that happens,
669 * CPU#0 observes the PENDING bit is still set and new execution of
670 * a @work is not queued in a hope, that CPU#1 will eventually
671 * finish the queued @work. Meanwhile CPU#1 does not see
672 * event_indicated is set, because speculative LOAD was executed
673 * before actual STORE.
678 static void clear_work_data(struct work_struct
*work
)
680 smp_wmb(); /* see set_work_pool_and_clear_pending() */
681 set_work_data(work
, WORK_STRUCT_NO_POOL
, 0);
684 static struct pool_workqueue
*get_work_pwq(struct work_struct
*work
)
686 unsigned long data
= atomic_long_read(&work
->data
);
688 if (data
& WORK_STRUCT_PWQ
)
689 return (void *)(data
& WORK_STRUCT_WQ_DATA_MASK
);
695 * get_work_pool - return the worker_pool a given work was associated with
696 * @work: the work item of interest
698 * Pools are created and destroyed under wq_pool_mutex, and allows read
699 * access under sched-RCU read lock. As such, this function should be
700 * called under wq_pool_mutex or with preemption disabled.
702 * All fields of the returned pool are accessible as long as the above
703 * mentioned locking is in effect. If the returned pool needs to be used
704 * beyond the critical section, the caller is responsible for ensuring the
705 * returned pool is and stays online.
707 * Return: The worker_pool @work was last associated with. %NULL if none.
709 static struct worker_pool
*get_work_pool(struct work_struct
*work
)
711 unsigned long data
= atomic_long_read(&work
->data
);
714 assert_rcu_or_pool_mutex();
716 if (data
& WORK_STRUCT_PWQ
)
717 return ((struct pool_workqueue
*)
718 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
;
720 pool_id
= data
>> WORK_OFFQ_POOL_SHIFT
;
721 if (pool_id
== WORK_OFFQ_POOL_NONE
)
724 return idr_find(&worker_pool_idr
, pool_id
);
728 * get_work_pool_id - return the worker pool ID a given work is associated with
729 * @work: the work item of interest
731 * Return: The worker_pool ID @work was last associated with.
732 * %WORK_OFFQ_POOL_NONE if none.
734 static int get_work_pool_id(struct work_struct
*work
)
736 unsigned long data
= atomic_long_read(&work
->data
);
738 if (data
& WORK_STRUCT_PWQ
)
739 return ((struct pool_workqueue
*)
740 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
->id
;
742 return data
>> WORK_OFFQ_POOL_SHIFT
;
745 static void mark_work_canceling(struct work_struct
*work
)
747 unsigned long pool_id
= get_work_pool_id(work
);
749 pool_id
<<= WORK_OFFQ_POOL_SHIFT
;
750 set_work_data(work
, pool_id
| WORK_OFFQ_CANCELING
, WORK_STRUCT_PENDING
);
753 static bool work_is_canceling(struct work_struct
*work
)
755 unsigned long data
= atomic_long_read(&work
->data
);
757 return !(data
& WORK_STRUCT_PWQ
) && (data
& WORK_OFFQ_CANCELING
);
761 * Policy functions. These define the policies on how the global worker
762 * pools are managed. Unless noted otherwise, these functions assume that
763 * they're being called with pool->lock held.
766 static bool __need_more_worker(struct worker_pool
*pool
)
768 return !atomic_read(&pool
->nr_running
);
772 * Need to wake up a worker? Called from anything but currently
775 * Note that, because unbound workers never contribute to nr_running, this
776 * function will always return %true for unbound pools as long as the
777 * worklist isn't empty.
779 static bool need_more_worker(struct worker_pool
*pool
)
781 return !list_empty(&pool
->worklist
) && __need_more_worker(pool
);
784 /* Can I start working? Called from busy but !running workers. */
785 static bool may_start_working(struct worker_pool
*pool
)
787 return pool
->nr_idle
;
790 /* Do I need to keep working? Called from currently running workers. */
791 static bool keep_working(struct worker_pool
*pool
)
793 return !list_empty(&pool
->worklist
) &&
794 atomic_read(&pool
->nr_running
) <= 1;
797 /* Do we need a new worker? Called from manager. */
798 static bool need_to_create_worker(struct worker_pool
*pool
)
800 return need_more_worker(pool
) && !may_start_working(pool
);
803 /* Do we have too many workers and should some go away? */
804 static bool too_many_workers(struct worker_pool
*pool
)
806 bool managing
= pool
->flags
& POOL_MANAGER_ACTIVE
;
807 int nr_idle
= pool
->nr_idle
+ managing
; /* manager is considered idle */
808 int nr_busy
= pool
->nr_workers
- nr_idle
;
810 return nr_idle
> 2 && (nr_idle
- 2) * MAX_IDLE_WORKERS_RATIO
>= nr_busy
;
817 /* Return the first idle worker. Safe with preemption disabled */
818 static struct worker
*first_idle_worker(struct worker_pool
*pool
)
820 if (unlikely(list_empty(&pool
->idle_list
)))
823 return list_first_entry(&pool
->idle_list
, struct worker
, entry
);
827 * wake_up_worker - wake up an idle worker
828 * @pool: worker pool to wake worker from
830 * Wake up the first idle worker of @pool.
833 * spin_lock_irq(pool->lock).
835 static void wake_up_worker(struct worker_pool
*pool
)
837 struct worker
*worker
= first_idle_worker(pool
);
840 wake_up_process(worker
->task
);
844 * wq_worker_waking_up - a worker is waking up
845 * @task: task waking up
846 * @cpu: CPU @task is waking up to
848 * This function is called during try_to_wake_up() when a worker is
852 * spin_lock_irq(rq->lock)
854 void wq_worker_waking_up(struct task_struct
*task
, int cpu
)
856 struct worker
*worker
= kthread_data(task
);
858 if (!(worker
->flags
& WORKER_NOT_RUNNING
)) {
859 WARN_ON_ONCE(worker
->pool
->cpu
!= cpu
);
860 atomic_inc(&worker
->pool
->nr_running
);
865 * wq_worker_sleeping - a worker is going to sleep
866 * @task: task going to sleep
868 * This function is called during schedule() when a busy worker is
869 * going to sleep. Worker on the same cpu can be woken up by
870 * returning pointer to its task.
873 * spin_lock_irq(rq->lock)
876 * Worker task on @cpu to wake up, %NULL if none.
878 struct task_struct
*wq_worker_sleeping(struct task_struct
*task
)
880 struct worker
*worker
= kthread_data(task
), *to_wakeup
= NULL
;
881 struct worker_pool
*pool
;
884 * Rescuers, which may not have all the fields set up like normal
885 * workers, also reach here, let's not access anything before
886 * checking NOT_RUNNING.
888 if (worker
->flags
& WORKER_NOT_RUNNING
)
893 /* this can only happen on the local cpu */
894 if (WARN_ON_ONCE(pool
->cpu
!= raw_smp_processor_id()))
898 * The counterpart of the following dec_and_test, implied mb,
899 * worklist not empty test sequence is in insert_work().
900 * Please read comment there.
902 * NOT_RUNNING is clear. This means that we're bound to and
903 * running on the local cpu w/ rq lock held and preemption
904 * disabled, which in turn means that none else could be
905 * manipulating idle_list, so dereferencing idle_list without pool
908 if (atomic_dec_and_test(&pool
->nr_running
) &&
909 !list_empty(&pool
->worklist
))
910 to_wakeup
= first_idle_worker(pool
);
911 return to_wakeup
? to_wakeup
->task
: NULL
;
915 * worker_set_flags - set worker flags and adjust nr_running accordingly
917 * @flags: flags to set
919 * Set @flags in @worker->flags and adjust nr_running accordingly.
922 * spin_lock_irq(pool->lock)
924 static inline void worker_set_flags(struct worker
*worker
, unsigned int flags
)
926 struct worker_pool
*pool
= worker
->pool
;
928 WARN_ON_ONCE(worker
->task
!= current
);
930 /* If transitioning into NOT_RUNNING, adjust nr_running. */
931 if ((flags
& WORKER_NOT_RUNNING
) &&
932 !(worker
->flags
& WORKER_NOT_RUNNING
)) {
933 atomic_dec(&pool
->nr_running
);
936 worker
->flags
|= flags
;
940 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
942 * @flags: flags to clear
944 * Clear @flags in @worker->flags and adjust nr_running accordingly.
947 * spin_lock_irq(pool->lock)
949 static inline void worker_clr_flags(struct worker
*worker
, unsigned int flags
)
951 struct worker_pool
*pool
= worker
->pool
;
952 unsigned int oflags
= worker
->flags
;
954 WARN_ON_ONCE(worker
->task
!= current
);
956 worker
->flags
&= ~flags
;
959 * If transitioning out of NOT_RUNNING, increment nr_running. Note
960 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
961 * of multiple flags, not a single flag.
963 if ((flags
& WORKER_NOT_RUNNING
) && (oflags
& WORKER_NOT_RUNNING
))
964 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
965 atomic_inc(&pool
->nr_running
);
969 * find_worker_executing_work - find worker which is executing a work
970 * @pool: pool of interest
971 * @work: work to find worker for
973 * Find a worker which is executing @work on @pool by searching
974 * @pool->busy_hash which is keyed by the address of @work. For a worker
975 * to match, its current execution should match the address of @work and
976 * its work function. This is to avoid unwanted dependency between
977 * unrelated work executions through a work item being recycled while still
980 * This is a bit tricky. A work item may be freed once its execution
981 * starts and nothing prevents the freed area from being recycled for
982 * another work item. If the same work item address ends up being reused
983 * before the original execution finishes, workqueue will identify the
984 * recycled work item as currently executing and make it wait until the
985 * current execution finishes, introducing an unwanted dependency.
987 * This function checks the work item address and work function to avoid
988 * false positives. Note that this isn't complete as one may construct a
989 * work function which can introduce dependency onto itself through a
990 * recycled work item. Well, if somebody wants to shoot oneself in the
991 * foot that badly, there's only so much we can do, and if such deadlock
992 * actually occurs, it should be easy to locate the culprit work function.
995 * spin_lock_irq(pool->lock).
998 * Pointer to worker which is executing @work if found, %NULL
1001 static struct worker
*find_worker_executing_work(struct worker_pool
*pool
,
1002 struct work_struct
*work
)
1004 struct worker
*worker
;
1006 hash_for_each_possible(pool
->busy_hash
, worker
, hentry
,
1007 (unsigned long)work
)
1008 if (worker
->current_work
== work
&&
1009 worker
->current_func
== work
->func
)
1016 * move_linked_works - move linked works to a list
1017 * @work: start of series of works to be scheduled
1018 * @head: target list to append @work to
1019 * @nextp: out parameter for nested worklist walking
1021 * Schedule linked works starting from @work to @head. Work series to
1022 * be scheduled starts at @work and includes any consecutive work with
1023 * WORK_STRUCT_LINKED set in its predecessor.
1025 * If @nextp is not NULL, it's updated to point to the next work of
1026 * the last scheduled work. This allows move_linked_works() to be
1027 * nested inside outer list_for_each_entry_safe().
1030 * spin_lock_irq(pool->lock).
1032 static void move_linked_works(struct work_struct
*work
, struct list_head
*head
,
1033 struct work_struct
**nextp
)
1035 struct work_struct
*n
;
1038 * Linked worklist will always end before the end of the list,
1039 * use NULL for list head.
1041 list_for_each_entry_safe_from(work
, n
, NULL
, entry
) {
1042 list_move_tail(&work
->entry
, head
);
1043 if (!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))
1048 * If we're already inside safe list traversal and have moved
1049 * multiple works to the scheduled queue, the next position
1050 * needs to be updated.
1057 * get_pwq - get an extra reference on the specified pool_workqueue
1058 * @pwq: pool_workqueue to get
1060 * Obtain an extra reference on @pwq. The caller should guarantee that
1061 * @pwq has positive refcnt and be holding the matching pool->lock.
1063 static void get_pwq(struct pool_workqueue
*pwq
)
1065 lockdep_assert_held(&pwq
->pool
->lock
);
1066 WARN_ON_ONCE(pwq
->refcnt
<= 0);
1071 * put_pwq - put a pool_workqueue reference
1072 * @pwq: pool_workqueue to put
1074 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1075 * destruction. The caller should be holding the matching pool->lock.
1077 static void put_pwq(struct pool_workqueue
*pwq
)
1079 lockdep_assert_held(&pwq
->pool
->lock
);
1080 if (likely(--pwq
->refcnt
))
1082 if (WARN_ON_ONCE(!(pwq
->wq
->flags
& WQ_UNBOUND
)))
1085 * @pwq can't be released under pool->lock, bounce to
1086 * pwq_unbound_release_workfn(). This never recurses on the same
1087 * pool->lock as this path is taken only for unbound workqueues and
1088 * the release work item is scheduled on a per-cpu workqueue. To
1089 * avoid lockdep warning, unbound pool->locks are given lockdep
1090 * subclass of 1 in get_unbound_pool().
1092 schedule_work(&pwq
->unbound_release_work
);
1096 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1097 * @pwq: pool_workqueue to put (can be %NULL)
1099 * put_pwq() with locking. This function also allows %NULL @pwq.
1101 static void put_pwq_unlocked(struct pool_workqueue
*pwq
)
1105 * As both pwqs and pools are sched-RCU protected, the
1106 * following lock operations are safe.
1108 spin_lock_irq(&pwq
->pool
->lock
);
1110 spin_unlock_irq(&pwq
->pool
->lock
);
1114 static void pwq_activate_delayed_work(struct work_struct
*work
)
1116 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1118 trace_workqueue_activate_work(work
);
1119 if (list_empty(&pwq
->pool
->worklist
))
1120 pwq
->pool
->watchdog_ts
= jiffies
;
1121 move_linked_works(work
, &pwq
->pool
->worklist
, NULL
);
1122 __clear_bit(WORK_STRUCT_DELAYED_BIT
, work_data_bits(work
));
1126 static void pwq_activate_first_delayed(struct pool_workqueue
*pwq
)
1128 struct work_struct
*work
= list_first_entry(&pwq
->delayed_works
,
1129 struct work_struct
, entry
);
1131 pwq_activate_delayed_work(work
);
1135 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1136 * @pwq: pwq of interest
1137 * @color: color of work which left the queue
1139 * A work either has completed or is removed from pending queue,
1140 * decrement nr_in_flight of its pwq and handle workqueue flushing.
1143 * spin_lock_irq(pool->lock).
1145 static void pwq_dec_nr_in_flight(struct pool_workqueue
*pwq
, int color
)
1147 /* uncolored work items don't participate in flushing or nr_active */
1148 if (color
== WORK_NO_COLOR
)
1151 pwq
->nr_in_flight
[color
]--;
1154 if (!list_empty(&pwq
->delayed_works
)) {
1155 /* one down, submit a delayed one */
1156 if (pwq
->nr_active
< pwq
->max_active
)
1157 pwq_activate_first_delayed(pwq
);
1160 /* is flush in progress and are we at the flushing tip? */
1161 if (likely(pwq
->flush_color
!= color
))
1164 /* are there still in-flight works? */
1165 if (pwq
->nr_in_flight
[color
])
1168 /* this pwq is done, clear flush_color */
1169 pwq
->flush_color
= -1;
1172 * If this was the last pwq, wake up the first flusher. It
1173 * will handle the rest.
1175 if (atomic_dec_and_test(&pwq
->wq
->nr_pwqs_to_flush
))
1176 complete(&pwq
->wq
->first_flusher
->done
);
1182 * try_to_grab_pending - steal work item from worklist and disable irq
1183 * @work: work item to steal
1184 * @is_dwork: @work is a delayed_work
1185 * @flags: place to store irq state
1187 * Try to grab PENDING bit of @work. This function can handle @work in any
1188 * stable state - idle, on timer or on worklist.
1191 * 1 if @work was pending and we successfully stole PENDING
1192 * 0 if @work was idle and we claimed PENDING
1193 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1194 * -ENOENT if someone else is canceling @work, this state may persist
1195 * for arbitrarily long
1198 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1199 * interrupted while holding PENDING and @work off queue, irq must be
1200 * disabled on entry. This, combined with delayed_work->timer being
1201 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1203 * On successful return, >= 0, irq is disabled and the caller is
1204 * responsible for releasing it using local_irq_restore(*@flags).
1206 * This function is safe to call from any context including IRQ handler.
1208 static int try_to_grab_pending(struct work_struct
*work
, bool is_dwork
,
1209 unsigned long *flags
)
1211 struct worker_pool
*pool
;
1212 struct pool_workqueue
*pwq
;
1214 local_irq_save(*flags
);
1216 /* try to steal the timer if it exists */
1218 struct delayed_work
*dwork
= to_delayed_work(work
);
1221 * dwork->timer is irqsafe. If del_timer() fails, it's
1222 * guaranteed that the timer is not queued anywhere and not
1223 * running on the local CPU.
1225 if (likely(del_timer(&dwork
->timer
)))
1229 /* try to claim PENDING the normal way */
1230 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
)))
1234 * The queueing is in progress, or it is already queued. Try to
1235 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1237 pool
= get_work_pool(work
);
1241 spin_lock(&pool
->lock
);
1243 * work->data is guaranteed to point to pwq only while the work
1244 * item is queued on pwq->wq, and both updating work->data to point
1245 * to pwq on queueing and to pool on dequeueing are done under
1246 * pwq->pool->lock. This in turn guarantees that, if work->data
1247 * points to pwq which is associated with a locked pool, the work
1248 * item is currently queued on that pool.
1250 pwq
= get_work_pwq(work
);
1251 if (pwq
&& pwq
->pool
== pool
) {
1252 debug_work_deactivate(work
);
1255 * A delayed work item cannot be grabbed directly because
1256 * it might have linked NO_COLOR work items which, if left
1257 * on the delayed_list, will confuse pwq->nr_active
1258 * management later on and cause stall. Make sure the work
1259 * item is activated before grabbing.
1261 if (*work_data_bits(work
) & WORK_STRUCT_DELAYED
)
1262 pwq_activate_delayed_work(work
);
1264 list_del_init(&work
->entry
);
1265 pwq_dec_nr_in_flight(pwq
, get_work_color(work
));
1267 /* work->data points to pwq iff queued, point to pool */
1268 set_work_pool_and_keep_pending(work
, pool
->id
);
1270 spin_unlock(&pool
->lock
);
1273 spin_unlock(&pool
->lock
);
1275 local_irq_restore(*flags
);
1276 if (work_is_canceling(work
))
1283 * insert_work - insert a work into a pool
1284 * @pwq: pwq @work belongs to
1285 * @work: work to insert
1286 * @head: insertion point
1287 * @extra_flags: extra WORK_STRUCT_* flags to set
1289 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1290 * work_struct flags.
1293 * spin_lock_irq(pool->lock).
1295 static void insert_work(struct pool_workqueue
*pwq
, struct work_struct
*work
,
1296 struct list_head
*head
, unsigned int extra_flags
)
1298 struct worker_pool
*pool
= pwq
->pool
;
1300 /* we own @work, set data and link */
1301 set_work_pwq(work
, pwq
, extra_flags
);
1302 list_add_tail(&work
->entry
, head
);
1306 * Ensure either wq_worker_sleeping() sees the above
1307 * list_add_tail() or we see zero nr_running to avoid workers lying
1308 * around lazily while there are works to be processed.
1312 if (__need_more_worker(pool
))
1313 wake_up_worker(pool
);
1317 * Test whether @work is being queued from another work executing on the
1320 static bool is_chained_work(struct workqueue_struct
*wq
)
1322 struct worker
*worker
;
1324 worker
= current_wq_worker();
1326 * Return %true iff I'm a worker execuing a work item on @wq. If
1327 * I'm @worker, it's safe to dereference it without locking.
1329 return worker
&& worker
->current_pwq
->wq
== wq
;
1333 * When queueing an unbound work item to a wq, prefer local CPU if allowed
1334 * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to
1335 * avoid perturbing sensitive tasks.
1337 static int wq_select_unbound_cpu(int cpu
)
1339 static bool printed_dbg_warning
;
1342 if (likely(!wq_debug_force_rr_cpu
)) {
1343 if (cpumask_test_cpu(cpu
, wq_unbound_cpumask
))
1345 } else if (!printed_dbg_warning
) {
1346 pr_warn("workqueue: round-robin CPU selection forced, expect performance impact\n");
1347 printed_dbg_warning
= true;
1350 if (cpumask_empty(wq_unbound_cpumask
))
1353 new_cpu
= __this_cpu_read(wq_rr_cpu_last
);
1354 new_cpu
= cpumask_next_and(new_cpu
, wq_unbound_cpumask
, cpu_online_mask
);
1355 if (unlikely(new_cpu
>= nr_cpu_ids
)) {
1356 new_cpu
= cpumask_first_and(wq_unbound_cpumask
, cpu_online_mask
);
1357 if (unlikely(new_cpu
>= nr_cpu_ids
))
1360 __this_cpu_write(wq_rr_cpu_last
, new_cpu
);
1365 static void __queue_work(int cpu
, struct workqueue_struct
*wq
,
1366 struct work_struct
*work
)
1368 struct pool_workqueue
*pwq
;
1369 struct worker_pool
*last_pool
;
1370 struct list_head
*worklist
;
1371 unsigned int work_flags
;
1372 unsigned int req_cpu
= cpu
;
1375 * While a work item is PENDING && off queue, a task trying to
1376 * steal the PENDING will busy-loop waiting for it to either get
1377 * queued or lose PENDING. Grabbing PENDING and queueing should
1378 * happen with IRQ disabled.
1380 lockdep_assert_irqs_disabled();
1382 debug_work_activate(work
);
1384 /* if draining, only works from the same workqueue are allowed */
1385 if (unlikely(wq
->flags
& __WQ_DRAINING
) &&
1386 WARN_ON_ONCE(!is_chained_work(wq
)))
1389 if (req_cpu
== WORK_CPU_UNBOUND
)
1390 cpu
= wq_select_unbound_cpu(raw_smp_processor_id());
1392 /* pwq which will be used unless @work is executing elsewhere */
1393 if (!(wq
->flags
& WQ_UNBOUND
))
1394 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
1396 pwq
= unbound_pwq_by_node(wq
, cpu_to_node(cpu
));
1399 * If @work was previously on a different pool, it might still be
1400 * running there, in which case the work needs to be queued on that
1401 * pool to guarantee non-reentrancy.
1403 last_pool
= get_work_pool(work
);
1404 if (last_pool
&& last_pool
!= pwq
->pool
) {
1405 struct worker
*worker
;
1407 spin_lock(&last_pool
->lock
);
1409 worker
= find_worker_executing_work(last_pool
, work
);
1411 if (worker
&& worker
->current_pwq
->wq
== wq
) {
1412 pwq
= worker
->current_pwq
;
1414 /* meh... not running there, queue here */
1415 spin_unlock(&last_pool
->lock
);
1416 spin_lock(&pwq
->pool
->lock
);
1419 spin_lock(&pwq
->pool
->lock
);
1423 * pwq is determined and locked. For unbound pools, we could have
1424 * raced with pwq release and it could already be dead. If its
1425 * refcnt is zero, repeat pwq selection. Note that pwqs never die
1426 * without another pwq replacing it in the numa_pwq_tbl or while
1427 * work items are executing on it, so the retrying is guaranteed to
1428 * make forward-progress.
1430 if (unlikely(!pwq
->refcnt
)) {
1431 if (wq
->flags
& WQ_UNBOUND
) {
1432 spin_unlock(&pwq
->pool
->lock
);
1437 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1441 /* pwq determined, queue */
1442 trace_workqueue_queue_work(req_cpu
, pwq
, work
);
1444 if (WARN_ON(!list_empty(&work
->entry
))) {
1445 spin_unlock(&pwq
->pool
->lock
);
1449 pwq
->nr_in_flight
[pwq
->work_color
]++;
1450 work_flags
= work_color_to_flags(pwq
->work_color
);
1452 if (likely(pwq
->nr_active
< pwq
->max_active
)) {
1453 trace_workqueue_activate_work(work
);
1455 worklist
= &pwq
->pool
->worklist
;
1456 if (list_empty(worklist
))
1457 pwq
->pool
->watchdog_ts
= jiffies
;
1459 work_flags
|= WORK_STRUCT_DELAYED
;
1460 worklist
= &pwq
->delayed_works
;
1463 insert_work(pwq
, work
, worklist
, work_flags
);
1465 spin_unlock(&pwq
->pool
->lock
);
1469 * queue_work_on - queue work on specific cpu
1470 * @cpu: CPU number to execute work on
1471 * @wq: workqueue to use
1472 * @work: work to queue
1474 * We queue the work to a specific CPU, the caller must ensure it
1477 * Return: %false if @work was already on a queue, %true otherwise.
1479 bool queue_work_on(int cpu
, struct workqueue_struct
*wq
,
1480 struct work_struct
*work
)
1483 unsigned long flags
;
1485 local_irq_save(flags
);
1487 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1488 __queue_work(cpu
, wq
, work
);
1492 local_irq_restore(flags
);
1495 EXPORT_SYMBOL(queue_work_on
);
1497 void delayed_work_timer_fn(struct timer_list
*t
)
1499 struct delayed_work
*dwork
= from_timer(dwork
, t
, timer
);
1501 /* should have been called from irqsafe timer with irq already off */
1502 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
1504 EXPORT_SYMBOL(delayed_work_timer_fn
);
1506 static void __queue_delayed_work(int cpu
, struct workqueue_struct
*wq
,
1507 struct delayed_work
*dwork
, unsigned long delay
)
1509 struct timer_list
*timer
= &dwork
->timer
;
1510 struct work_struct
*work
= &dwork
->work
;
1513 WARN_ON_ONCE(timer
->function
!= delayed_work_timer_fn
);
1514 WARN_ON_ONCE(timer_pending(timer
));
1515 WARN_ON_ONCE(!list_empty(&work
->entry
));
1518 * If @delay is 0, queue @dwork->work immediately. This is for
1519 * both optimization and correctness. The earliest @timer can
1520 * expire is on the closest next tick and delayed_work users depend
1521 * on that there's no such delay when @delay is 0.
1524 __queue_work(cpu
, wq
, &dwork
->work
);
1530 timer
->expires
= jiffies
+ delay
;
1532 if (unlikely(cpu
!= WORK_CPU_UNBOUND
))
1533 add_timer_on(timer
, cpu
);
1539 * queue_delayed_work_on - queue work on specific CPU after delay
1540 * @cpu: CPU number to execute work on
1541 * @wq: workqueue to use
1542 * @dwork: work to queue
1543 * @delay: number of jiffies to wait before queueing
1545 * Return: %false if @work was already on a queue, %true otherwise. If
1546 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1549 bool queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1550 struct delayed_work
*dwork
, unsigned long delay
)
1552 struct work_struct
*work
= &dwork
->work
;
1554 unsigned long flags
;
1556 /* read the comment in __queue_work() */
1557 local_irq_save(flags
);
1559 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1560 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1564 local_irq_restore(flags
);
1567 EXPORT_SYMBOL(queue_delayed_work_on
);
1570 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1571 * @cpu: CPU number to execute work on
1572 * @wq: workqueue to use
1573 * @dwork: work to queue
1574 * @delay: number of jiffies to wait before queueing
1576 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1577 * modify @dwork's timer so that it expires after @delay. If @delay is
1578 * zero, @work is guaranteed to be scheduled immediately regardless of its
1581 * Return: %false if @dwork was idle and queued, %true if @dwork was
1582 * pending and its timer was modified.
1584 * This function is safe to call from any context including IRQ handler.
1585 * See try_to_grab_pending() for details.
1587 bool mod_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1588 struct delayed_work
*dwork
, unsigned long delay
)
1590 unsigned long flags
;
1594 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
1595 } while (unlikely(ret
== -EAGAIN
));
1597 if (likely(ret
>= 0)) {
1598 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1599 local_irq_restore(flags
);
1602 /* -ENOENT from try_to_grab_pending() becomes %true */
1605 EXPORT_SYMBOL_GPL(mod_delayed_work_on
);
1608 * worker_enter_idle - enter idle state
1609 * @worker: worker which is entering idle state
1611 * @worker is entering idle state. Update stats and idle timer if
1615 * spin_lock_irq(pool->lock).
1617 static void worker_enter_idle(struct worker
*worker
)
1619 struct worker_pool
*pool
= worker
->pool
;
1621 if (WARN_ON_ONCE(worker
->flags
& WORKER_IDLE
) ||
1622 WARN_ON_ONCE(!list_empty(&worker
->entry
) &&
1623 (worker
->hentry
.next
|| worker
->hentry
.pprev
)))
1626 /* can't use worker_set_flags(), also called from create_worker() */
1627 worker
->flags
|= WORKER_IDLE
;
1629 worker
->last_active
= jiffies
;
1631 /* idle_list is LIFO */
1632 list_add(&worker
->entry
, &pool
->idle_list
);
1634 if (too_many_workers(pool
) && !timer_pending(&pool
->idle_timer
))
1635 mod_timer(&pool
->idle_timer
, jiffies
+ IDLE_WORKER_TIMEOUT
);
1638 * Sanity check nr_running. Because unbind_workers() releases
1639 * pool->lock between setting %WORKER_UNBOUND and zapping
1640 * nr_running, the warning may trigger spuriously. Check iff
1641 * unbind is not in progress.
1643 WARN_ON_ONCE(!(pool
->flags
& POOL_DISASSOCIATED
) &&
1644 pool
->nr_workers
== pool
->nr_idle
&&
1645 atomic_read(&pool
->nr_running
));
1649 * worker_leave_idle - leave idle state
1650 * @worker: worker which is leaving idle state
1652 * @worker is leaving idle state. Update stats.
1655 * spin_lock_irq(pool->lock).
1657 static void worker_leave_idle(struct worker
*worker
)
1659 struct worker_pool
*pool
= worker
->pool
;
1661 if (WARN_ON_ONCE(!(worker
->flags
& WORKER_IDLE
)))
1663 worker_clr_flags(worker
, WORKER_IDLE
);
1665 list_del_init(&worker
->entry
);
1668 static struct worker
*alloc_worker(int node
)
1670 struct worker
*worker
;
1672 worker
= kzalloc_node(sizeof(*worker
), GFP_KERNEL
, node
);
1674 INIT_LIST_HEAD(&worker
->entry
);
1675 INIT_LIST_HEAD(&worker
->scheduled
);
1676 INIT_LIST_HEAD(&worker
->node
);
1677 /* on creation a worker is in !idle && prep state */
1678 worker
->flags
= WORKER_PREP
;
1684 * worker_attach_to_pool() - attach a worker to a pool
1685 * @worker: worker to be attached
1686 * @pool: the target pool
1688 * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
1689 * cpu-binding of @worker are kept coordinated with the pool across
1692 static void worker_attach_to_pool(struct worker
*worker
,
1693 struct worker_pool
*pool
)
1695 mutex_lock(&pool
->attach_mutex
);
1698 * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1699 * online CPUs. It'll be re-applied when any of the CPUs come up.
1701 set_cpus_allowed_ptr(worker
->task
, pool
->attrs
->cpumask
);
1704 * The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
1705 * stable across this function. See the comments above the
1706 * flag definition for details.
1708 if (pool
->flags
& POOL_DISASSOCIATED
)
1709 worker
->flags
|= WORKER_UNBOUND
;
1711 list_add_tail(&worker
->node
, &pool
->workers
);
1713 mutex_unlock(&pool
->attach_mutex
);
1717 * worker_detach_from_pool() - detach a worker from its pool
1718 * @worker: worker which is attached to its pool
1719 * @pool: the pool @worker is attached to
1721 * Undo the attaching which had been done in worker_attach_to_pool(). The
1722 * caller worker shouldn't access to the pool after detached except it has
1723 * other reference to the pool.
1725 static void worker_detach_from_pool(struct worker
*worker
,
1726 struct worker_pool
*pool
)
1728 struct completion
*detach_completion
= NULL
;
1730 mutex_lock(&pool
->attach_mutex
);
1731 list_del(&worker
->node
);
1732 if (list_empty(&pool
->workers
))
1733 detach_completion
= pool
->detach_completion
;
1734 mutex_unlock(&pool
->attach_mutex
);
1736 /* clear leftover flags without pool->lock after it is detached */
1737 worker
->flags
&= ~(WORKER_UNBOUND
| WORKER_REBOUND
);
1739 if (detach_completion
)
1740 complete(detach_completion
);
1744 * create_worker - create a new workqueue worker
1745 * @pool: pool the new worker will belong to
1747 * Create and start a new worker which is attached to @pool.
1750 * Might sleep. Does GFP_KERNEL allocations.
1753 * Pointer to the newly created worker.
1755 static struct worker
*create_worker(struct worker_pool
*pool
)
1757 struct worker
*worker
= NULL
;
1761 /* ID is needed to determine kthread name */
1762 id
= ida_simple_get(&pool
->worker_ida
, 0, 0, GFP_KERNEL
);
1766 worker
= alloc_worker(pool
->node
);
1770 worker
->pool
= pool
;
1774 snprintf(id_buf
, sizeof(id_buf
), "%d:%d%s", pool
->cpu
, id
,
1775 pool
->attrs
->nice
< 0 ? "H" : "");
1777 snprintf(id_buf
, sizeof(id_buf
), "u%d:%d", pool
->id
, id
);
1779 worker
->task
= kthread_create_on_node(worker_thread
, worker
, pool
->node
,
1780 "kworker/%s", id_buf
);
1781 if (IS_ERR(worker
->task
))
1784 set_user_nice(worker
->task
, pool
->attrs
->nice
);
1785 kthread_bind_mask(worker
->task
, pool
->attrs
->cpumask
);
1787 /* successful, attach the worker to the pool */
1788 worker_attach_to_pool(worker
, pool
);
1790 /* start the newly created worker */
1791 spin_lock_irq(&pool
->lock
);
1792 worker
->pool
->nr_workers
++;
1793 worker_enter_idle(worker
);
1794 wake_up_process(worker
->task
);
1795 spin_unlock_irq(&pool
->lock
);
1801 ida_simple_remove(&pool
->worker_ida
, id
);
1807 * destroy_worker - destroy a workqueue worker
1808 * @worker: worker to be destroyed
1810 * Destroy @worker and adjust @pool stats accordingly. The worker should
1814 * spin_lock_irq(pool->lock).
1816 static void destroy_worker(struct worker
*worker
)
1818 struct worker_pool
*pool
= worker
->pool
;
1820 lockdep_assert_held(&pool
->lock
);
1822 /* sanity check frenzy */
1823 if (WARN_ON(worker
->current_work
) ||
1824 WARN_ON(!list_empty(&worker
->scheduled
)) ||
1825 WARN_ON(!(worker
->flags
& WORKER_IDLE
)))
1831 list_del_init(&worker
->entry
);
1832 worker
->flags
|= WORKER_DIE
;
1833 wake_up_process(worker
->task
);
1836 static void idle_worker_timeout(struct timer_list
*t
)
1838 struct worker_pool
*pool
= from_timer(pool
, t
, idle_timer
);
1840 spin_lock_irq(&pool
->lock
);
1842 while (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
);
1855 destroy_worker(worker
);
1858 spin_unlock_irq(&pool
->lock
);
1861 static void send_mayday(struct work_struct
*work
)
1863 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1864 struct workqueue_struct
*wq
= pwq
->wq
;
1866 lockdep_assert_held(&wq_mayday_lock
);
1871 /* mayday mayday mayday */
1872 if (list_empty(&pwq
->mayday_node
)) {
1874 * If @pwq is for an unbound wq, its base ref may be put at
1875 * any time due to an attribute change. Pin @pwq until the
1876 * rescuer is done with it.
1879 list_add_tail(&pwq
->mayday_node
, &wq
->maydays
);
1880 wake_up_process(wq
->rescuer
->task
);
1884 static void pool_mayday_timeout(struct timer_list
*t
)
1886 struct worker_pool
*pool
= from_timer(pool
, t
, mayday_timer
);
1887 struct work_struct
*work
;
1889 spin_lock_irq(&pool
->lock
);
1890 spin_lock(&wq_mayday_lock
); /* for wq->maydays */
1892 if (need_to_create_worker(pool
)) {
1894 * We've been trying to create a new worker but
1895 * haven't been successful. We might be hitting an
1896 * allocation deadlock. Send distress signals to
1899 list_for_each_entry(work
, &pool
->worklist
, entry
)
1903 spin_unlock(&wq_mayday_lock
);
1904 spin_unlock_irq(&pool
->lock
);
1906 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INTERVAL
);
1910 * maybe_create_worker - create a new worker if necessary
1911 * @pool: pool to create a new worker for
1913 * Create a new worker for @pool if necessary. @pool is guaranteed to
1914 * have at least one idle worker on return from this function. If
1915 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1916 * sent to all rescuers with works scheduled on @pool to resolve
1917 * possible allocation deadlock.
1919 * On return, need_to_create_worker() is guaranteed to be %false and
1920 * may_start_working() %true.
1923 * spin_lock_irq(pool->lock) which may be released and regrabbed
1924 * multiple times. Does GFP_KERNEL allocations. Called only from
1927 static void maybe_create_worker(struct worker_pool
*pool
)
1928 __releases(&pool
->lock
)
1929 __acquires(&pool
->lock
)
1932 spin_unlock_irq(&pool
->lock
);
1934 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1935 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INITIAL_TIMEOUT
);
1938 if (create_worker(pool
) || !need_to_create_worker(pool
))
1941 schedule_timeout_interruptible(CREATE_COOLDOWN
);
1943 if (!need_to_create_worker(pool
))
1947 del_timer_sync(&pool
->mayday_timer
);
1948 spin_lock_irq(&pool
->lock
);
1950 * This is necessary even after a new worker was just successfully
1951 * created as @pool->lock was dropped and the new worker might have
1952 * already become busy.
1954 if (need_to_create_worker(pool
))
1959 * manage_workers - manage worker pool
1962 * Assume the manager role and manage the worker pool @worker belongs
1963 * to. At any given time, there can be only zero or one manager per
1964 * pool. The exclusion is handled automatically by this function.
1966 * The caller can safely start processing works on false return. On
1967 * true return, it's guaranteed that need_to_create_worker() is false
1968 * and may_start_working() is true.
1971 * spin_lock_irq(pool->lock) which may be released and regrabbed
1972 * multiple times. Does GFP_KERNEL allocations.
1975 * %false if the pool doesn't need management and the caller can safely
1976 * start processing works, %true if management function was performed and
1977 * the conditions that the caller verified before calling the function may
1978 * no longer be true.
1980 static bool manage_workers(struct worker
*worker
)
1982 struct worker_pool
*pool
= worker
->pool
;
1984 if (pool
->flags
& POOL_MANAGER_ACTIVE
)
1987 pool
->flags
|= POOL_MANAGER_ACTIVE
;
1988 pool
->manager
= worker
;
1990 maybe_create_worker(pool
);
1992 pool
->manager
= NULL
;
1993 pool
->flags
&= ~POOL_MANAGER_ACTIVE
;
1994 wake_up(&wq_manager_wait
);
1999 * process_one_work - process single work
2001 * @work: work to process
2003 * Process @work. This function contains all the logics necessary to
2004 * process a single work including synchronization against and
2005 * interaction with other workers on the same cpu, queueing and
2006 * flushing. As long as context requirement is met, any worker can
2007 * call this function to process a work.
2010 * spin_lock_irq(pool->lock) which is released and regrabbed.
2012 static void process_one_work(struct worker
*worker
, struct work_struct
*work
)
2013 __releases(&pool
->lock
)
2014 __acquires(&pool
->lock
)
2016 struct pool_workqueue
*pwq
= get_work_pwq(work
);
2017 struct worker_pool
*pool
= worker
->pool
;
2018 bool cpu_intensive
= pwq
->wq
->flags
& WQ_CPU_INTENSIVE
;
2020 struct worker
*collision
;
2021 #ifdef CONFIG_LOCKDEP
2023 * It is permissible to free the struct work_struct from
2024 * inside the function that is called from it, this we need to
2025 * take into account for lockdep too. To avoid bogus "held
2026 * lock freed" warnings as well as problems when looking into
2027 * work->lockdep_map, make a copy and use that here.
2029 struct lockdep_map lockdep_map
;
2031 lockdep_copy_map(&lockdep_map
, &work
->lockdep_map
);
2033 /* ensure we're on the correct CPU */
2034 WARN_ON_ONCE(!(pool
->flags
& POOL_DISASSOCIATED
) &&
2035 raw_smp_processor_id() != pool
->cpu
);
2038 * A single work shouldn't be executed concurrently by
2039 * multiple workers on a single cpu. Check whether anyone is
2040 * already processing the work. If so, defer the work to the
2041 * currently executing one.
2043 collision
= find_worker_executing_work(pool
, work
);
2044 if (unlikely(collision
)) {
2045 move_linked_works(work
, &collision
->scheduled
, NULL
);
2049 /* claim and dequeue */
2050 debug_work_deactivate(work
);
2051 hash_add(pool
->busy_hash
, &worker
->hentry
, (unsigned long)work
);
2052 worker
->current_work
= work
;
2053 worker
->current_func
= work
->func
;
2054 worker
->current_pwq
= pwq
;
2055 work_color
= get_work_color(work
);
2057 list_del_init(&work
->entry
);
2060 * CPU intensive works don't participate in concurrency management.
2061 * They're the scheduler's responsibility. This takes @worker out
2062 * of concurrency management and the next code block will chain
2063 * execution of the pending work items.
2065 if (unlikely(cpu_intensive
))
2066 worker_set_flags(worker
, WORKER_CPU_INTENSIVE
);
2069 * Wake up another worker if necessary. The condition is always
2070 * false for normal per-cpu workers since nr_running would always
2071 * be >= 1 at this point. This is used to chain execution of the
2072 * pending work items for WORKER_NOT_RUNNING workers such as the
2073 * UNBOUND and CPU_INTENSIVE ones.
2075 if (need_more_worker(pool
))
2076 wake_up_worker(pool
);
2079 * Record the last pool and clear PENDING which should be the last
2080 * update to @work. Also, do this inside @pool->lock so that
2081 * PENDING and queued state changes happen together while IRQ is
2084 set_work_pool_and_clear_pending(work
, pool
->id
);
2086 spin_unlock_irq(&pool
->lock
);
2088 lock_map_acquire(&pwq
->wq
->lockdep_map
);
2089 lock_map_acquire(&lockdep_map
);
2091 * Strictly speaking we should mark the invariant state without holding
2092 * any locks, that is, before these two lock_map_acquire()'s.
2094 * However, that would result in:
2101 * Which would create W1->C->W1 dependencies, even though there is no
2102 * actual deadlock possible. There are two solutions, using a
2103 * read-recursive acquire on the work(queue) 'locks', but this will then
2104 * hit the lockdep limitation on recursive locks, or simply discard
2107 * AFAICT there is no possible deadlock scenario between the
2108 * flush_work() and complete() primitives (except for single-threaded
2109 * workqueues), so hiding them isn't a problem.
2111 lockdep_invariant_state(true);
2112 trace_workqueue_execute_start(work
);
2113 worker
->current_func(work
);
2115 * While we must be careful to not use "work" after this, the trace
2116 * point will only record its address.
2118 trace_workqueue_execute_end(work
);
2119 lock_map_release(&lockdep_map
);
2120 lock_map_release(&pwq
->wq
->lockdep_map
);
2122 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
2123 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2124 " last function: %pf\n",
2125 current
->comm
, preempt_count(), task_pid_nr(current
),
2126 worker
->current_func
);
2127 debug_show_held_locks(current
);
2132 * The following prevents a kworker from hogging CPU on !PREEMPT
2133 * kernels, where a requeueing work item waiting for something to
2134 * happen could deadlock with stop_machine as such work item could
2135 * indefinitely requeue itself while all other CPUs are trapped in
2136 * stop_machine. At the same time, report a quiescent RCU state so
2137 * the same condition doesn't freeze RCU.
2141 spin_lock_irq(&pool
->lock
);
2143 /* clear cpu intensive status */
2144 if (unlikely(cpu_intensive
))
2145 worker_clr_flags(worker
, WORKER_CPU_INTENSIVE
);
2147 /* we're done with it, release */
2148 hash_del(&worker
->hentry
);
2149 worker
->current_work
= NULL
;
2150 worker
->current_func
= NULL
;
2151 worker
->current_pwq
= NULL
;
2152 worker
->desc_valid
= false;
2153 pwq_dec_nr_in_flight(pwq
, work_color
);
2157 * process_scheduled_works - process scheduled works
2160 * Process all scheduled works. Please note that the scheduled list
2161 * may change while processing a work, so this function repeatedly
2162 * fetches a work from the top and executes it.
2165 * spin_lock_irq(pool->lock) which may be released and regrabbed
2168 static void process_scheduled_works(struct worker
*worker
)
2170 while (!list_empty(&worker
->scheduled
)) {
2171 struct work_struct
*work
= list_first_entry(&worker
->scheduled
,
2172 struct work_struct
, entry
);
2173 process_one_work(worker
, work
);
2178 * worker_thread - the worker thread function
2181 * The worker thread function. All workers belong to a worker_pool -
2182 * either a per-cpu one or dynamic unbound one. These workers process all
2183 * work items regardless of their specific target workqueue. The only
2184 * exception is work items which belong to workqueues with a rescuer which
2185 * will be explained in rescuer_thread().
2189 static int worker_thread(void *__worker
)
2191 struct worker
*worker
= __worker
;
2192 struct worker_pool
*pool
= worker
->pool
;
2194 /* tell the scheduler that this is a workqueue worker */
2195 worker
->task
->flags
|= PF_WQ_WORKER
;
2197 spin_lock_irq(&pool
->lock
);
2199 /* am I supposed to die? */
2200 if (unlikely(worker
->flags
& WORKER_DIE
)) {
2201 spin_unlock_irq(&pool
->lock
);
2202 WARN_ON_ONCE(!list_empty(&worker
->entry
));
2203 worker
->task
->flags
&= ~PF_WQ_WORKER
;
2205 set_task_comm(worker
->task
, "kworker/dying");
2206 ida_simple_remove(&pool
->worker_ida
, worker
->id
);
2207 worker_detach_from_pool(worker
, pool
);
2212 worker_leave_idle(worker
);
2214 /* no more worker necessary? */
2215 if (!need_more_worker(pool
))
2218 /* do we need to manage? */
2219 if (unlikely(!may_start_working(pool
)) && manage_workers(worker
))
2223 * ->scheduled list can only be filled while a worker is
2224 * preparing to process a work or actually processing it.
2225 * Make sure nobody diddled with it while I was sleeping.
2227 WARN_ON_ONCE(!list_empty(&worker
->scheduled
));
2230 * Finish PREP stage. We're guaranteed to have at least one idle
2231 * worker or that someone else has already assumed the manager
2232 * role. This is where @worker starts participating in concurrency
2233 * management if applicable and concurrency management is restored
2234 * after being rebound. See rebind_workers() for details.
2236 worker_clr_flags(worker
, WORKER_PREP
| WORKER_REBOUND
);
2239 struct work_struct
*work
=
2240 list_first_entry(&pool
->worklist
,
2241 struct work_struct
, entry
);
2243 pool
->watchdog_ts
= jiffies
;
2245 if (likely(!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))) {
2246 /* optimization path, not strictly necessary */
2247 process_one_work(worker
, work
);
2248 if (unlikely(!list_empty(&worker
->scheduled
)))
2249 process_scheduled_works(worker
);
2251 move_linked_works(work
, &worker
->scheduled
, NULL
);
2252 process_scheduled_works(worker
);
2254 } while (keep_working(pool
));
2256 worker_set_flags(worker
, WORKER_PREP
);
2259 * pool->lock is held and there's no work to process and no need to
2260 * manage, sleep. Workers are woken up only while holding
2261 * pool->lock or from local cpu, so setting the current state
2262 * before releasing pool->lock is enough to prevent losing any
2265 worker_enter_idle(worker
);
2266 __set_current_state(TASK_IDLE
);
2267 spin_unlock_irq(&pool
->lock
);
2273 * rescuer_thread - the rescuer thread function
2276 * Workqueue rescuer thread function. There's one rescuer for each
2277 * workqueue which has WQ_MEM_RECLAIM set.
2279 * Regular work processing on a pool may block trying to create a new
2280 * worker which uses GFP_KERNEL allocation which has slight chance of
2281 * developing into deadlock if some works currently on the same queue
2282 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2283 * the problem rescuer solves.
2285 * When such condition is possible, the pool summons rescuers of all
2286 * workqueues which have works queued on the pool and let them process
2287 * those works so that forward progress can be guaranteed.
2289 * This should happen rarely.
2293 static int rescuer_thread(void *__rescuer
)
2295 struct worker
*rescuer
= __rescuer
;
2296 struct workqueue_struct
*wq
= rescuer
->rescue_wq
;
2297 struct list_head
*scheduled
= &rescuer
->scheduled
;
2300 set_user_nice(current
, RESCUER_NICE_LEVEL
);
2303 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2304 * doesn't participate in concurrency management.
2306 rescuer
->task
->flags
|= PF_WQ_WORKER
;
2308 set_current_state(TASK_IDLE
);
2311 * By the time the rescuer is requested to stop, the workqueue
2312 * shouldn't have any work pending, but @wq->maydays may still have
2313 * pwq(s) queued. This can happen by non-rescuer workers consuming
2314 * all the work items before the rescuer got to them. Go through
2315 * @wq->maydays processing before acting on should_stop so that the
2316 * list is always empty on exit.
2318 should_stop
= kthread_should_stop();
2320 /* see whether any pwq is asking for help */
2321 spin_lock_irq(&wq_mayday_lock
);
2323 while (!list_empty(&wq
->maydays
)) {
2324 struct pool_workqueue
*pwq
= list_first_entry(&wq
->maydays
,
2325 struct pool_workqueue
, mayday_node
);
2326 struct worker_pool
*pool
= pwq
->pool
;
2327 struct work_struct
*work
, *n
;
2330 __set_current_state(TASK_RUNNING
);
2331 list_del_init(&pwq
->mayday_node
);
2333 spin_unlock_irq(&wq_mayday_lock
);
2335 worker_attach_to_pool(rescuer
, pool
);
2337 spin_lock_irq(&pool
->lock
);
2338 rescuer
->pool
= pool
;
2341 * Slurp in all works issued via this workqueue and
2344 WARN_ON_ONCE(!list_empty(scheduled
));
2345 list_for_each_entry_safe(work
, n
, &pool
->worklist
, entry
) {
2346 if (get_work_pwq(work
) == pwq
) {
2348 pool
->watchdog_ts
= jiffies
;
2349 move_linked_works(work
, scheduled
, &n
);
2354 if (!list_empty(scheduled
)) {
2355 process_scheduled_works(rescuer
);
2358 * The above execution of rescued work items could
2359 * have created more to rescue through
2360 * pwq_activate_first_delayed() or chained
2361 * queueing. Let's put @pwq back on mayday list so
2362 * that such back-to-back work items, which may be
2363 * being used to relieve memory pressure, don't
2364 * incur MAYDAY_INTERVAL delay inbetween.
2366 if (need_to_create_worker(pool
)) {
2367 spin_lock(&wq_mayday_lock
);
2369 list_move_tail(&pwq
->mayday_node
, &wq
->maydays
);
2370 spin_unlock(&wq_mayday_lock
);
2375 * Put the reference grabbed by send_mayday(). @pool won't
2376 * go away while we're still attached to it.
2381 * Leave this pool. If need_more_worker() is %true, notify a
2382 * regular worker; otherwise, we end up with 0 concurrency
2383 * and stalling the execution.
2385 if (need_more_worker(pool
))
2386 wake_up_worker(pool
);
2388 rescuer
->pool
= NULL
;
2389 spin_unlock_irq(&pool
->lock
);
2391 worker_detach_from_pool(rescuer
, pool
);
2393 spin_lock_irq(&wq_mayday_lock
);
2396 spin_unlock_irq(&wq_mayday_lock
);
2399 __set_current_state(TASK_RUNNING
);
2400 rescuer
->task
->flags
&= ~PF_WQ_WORKER
;
2404 /* rescuers should never participate in concurrency management */
2405 WARN_ON_ONCE(!(rescuer
->flags
& WORKER_NOT_RUNNING
));
2411 * check_flush_dependency - check for flush dependency sanity
2412 * @target_wq: workqueue being flushed
2413 * @target_work: work item being flushed (NULL for workqueue flushes)
2415 * %current is trying to flush the whole @target_wq or @target_work on it.
2416 * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not
2417 * reclaiming memory or running on a workqueue which doesn't have
2418 * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to
2421 static void check_flush_dependency(struct workqueue_struct
*target_wq
,
2422 struct work_struct
*target_work
)
2424 work_func_t target_func
= target_work
? target_work
->func
: NULL
;
2425 struct worker
*worker
;
2427 if (target_wq
->flags
& WQ_MEM_RECLAIM
)
2430 worker
= current_wq_worker();
2432 WARN_ONCE(current
->flags
& PF_MEMALLOC
,
2433 "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%pf",
2434 current
->pid
, current
->comm
, target_wq
->name
, target_func
);
2435 WARN_ONCE(worker
&& ((worker
->current_pwq
->wq
->flags
&
2436 (WQ_MEM_RECLAIM
| __WQ_LEGACY
)) == WQ_MEM_RECLAIM
),
2437 "workqueue: WQ_MEM_RECLAIM %s:%pf is flushing !WQ_MEM_RECLAIM %s:%pf",
2438 worker
->current_pwq
->wq
->name
, worker
->current_func
,
2439 target_wq
->name
, target_func
);
2443 struct work_struct work
;
2444 struct completion done
;
2445 struct task_struct
*task
; /* purely informational */
2448 static void wq_barrier_func(struct work_struct
*work
)
2450 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
2451 complete(&barr
->done
);
2455 * insert_wq_barrier - insert a barrier work
2456 * @pwq: pwq to insert barrier into
2457 * @barr: wq_barrier to insert
2458 * @target: target work to attach @barr to
2459 * @worker: worker currently executing @target, NULL if @target is not executing
2461 * @barr is linked to @target such that @barr is completed only after
2462 * @target finishes execution. Please note that the ordering
2463 * guarantee is observed only with respect to @target and on the local
2466 * Currently, a queued barrier can't be canceled. This is because
2467 * try_to_grab_pending() can't determine whether the work to be
2468 * grabbed is at the head of the queue and thus can't clear LINKED
2469 * flag of the previous work while there must be a valid next work
2470 * after a work with LINKED flag set.
2472 * Note that when @worker is non-NULL, @target may be modified
2473 * underneath us, so we can't reliably determine pwq from @target.
2476 * spin_lock_irq(pool->lock).
2478 static void insert_wq_barrier(struct pool_workqueue
*pwq
,
2479 struct wq_barrier
*barr
,
2480 struct work_struct
*target
, struct worker
*worker
)
2482 struct list_head
*head
;
2483 unsigned int linked
= 0;
2486 * debugobject calls are safe here even with pool->lock locked
2487 * as we know for sure that this will not trigger any of the
2488 * checks and call back into the fixup functions where we
2491 INIT_WORK_ONSTACK(&barr
->work
, wq_barrier_func
);
2492 __set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(&barr
->work
));
2494 init_completion_map(&barr
->done
, &target
->lockdep_map
);
2496 barr
->task
= current
;
2499 * If @target is currently being executed, schedule the
2500 * barrier to the worker; otherwise, put it after @target.
2503 head
= worker
->scheduled
.next
;
2505 unsigned long *bits
= work_data_bits(target
);
2507 head
= target
->entry
.next
;
2508 /* there can already be other linked works, inherit and set */
2509 linked
= *bits
& WORK_STRUCT_LINKED
;
2510 __set_bit(WORK_STRUCT_LINKED_BIT
, bits
);
2513 debug_work_activate(&barr
->work
);
2514 insert_work(pwq
, &barr
->work
, head
,
2515 work_color_to_flags(WORK_NO_COLOR
) | linked
);
2519 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2520 * @wq: workqueue being flushed
2521 * @flush_color: new flush color, < 0 for no-op
2522 * @work_color: new work color, < 0 for no-op
2524 * Prepare pwqs for workqueue flushing.
2526 * If @flush_color is non-negative, flush_color on all pwqs should be
2527 * -1. If no pwq has in-flight commands at the specified color, all
2528 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2529 * has in flight commands, its pwq->flush_color is set to
2530 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2531 * wakeup logic is armed and %true is returned.
2533 * The caller should have initialized @wq->first_flusher prior to
2534 * calling this function with non-negative @flush_color. If
2535 * @flush_color is negative, no flush color update is done and %false
2538 * If @work_color is non-negative, all pwqs should have the same
2539 * work_color which is previous to @work_color and all will be
2540 * advanced to @work_color.
2543 * mutex_lock(wq->mutex).
2546 * %true if @flush_color >= 0 and there's something to flush. %false
2549 static bool flush_workqueue_prep_pwqs(struct workqueue_struct
*wq
,
2550 int flush_color
, int work_color
)
2553 struct pool_workqueue
*pwq
;
2555 if (flush_color
>= 0) {
2556 WARN_ON_ONCE(atomic_read(&wq
->nr_pwqs_to_flush
));
2557 atomic_set(&wq
->nr_pwqs_to_flush
, 1);
2560 for_each_pwq(pwq
, wq
) {
2561 struct worker_pool
*pool
= pwq
->pool
;
2563 spin_lock_irq(&pool
->lock
);
2565 if (flush_color
>= 0) {
2566 WARN_ON_ONCE(pwq
->flush_color
!= -1);
2568 if (pwq
->nr_in_flight
[flush_color
]) {
2569 pwq
->flush_color
= flush_color
;
2570 atomic_inc(&wq
->nr_pwqs_to_flush
);
2575 if (work_color
>= 0) {
2576 WARN_ON_ONCE(work_color
!= work_next_color(pwq
->work_color
));
2577 pwq
->work_color
= work_color
;
2580 spin_unlock_irq(&pool
->lock
);
2583 if (flush_color
>= 0 && atomic_dec_and_test(&wq
->nr_pwqs_to_flush
))
2584 complete(&wq
->first_flusher
->done
);
2590 * flush_workqueue - ensure that any scheduled work has run to completion.
2591 * @wq: workqueue to flush
2593 * This function sleeps until all work items which were queued on entry
2594 * have finished execution, but it is not livelocked by new incoming ones.
2596 void flush_workqueue(struct workqueue_struct
*wq
)
2598 struct wq_flusher this_flusher
= {
2599 .list
= LIST_HEAD_INIT(this_flusher
.list
),
2601 .done
= COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher
.done
, wq
->lockdep_map
),
2605 if (WARN_ON(!wq_online
))
2608 mutex_lock(&wq
->mutex
);
2611 * Start-to-wait phase
2613 next_color
= work_next_color(wq
->work_color
);
2615 if (next_color
!= wq
->flush_color
) {
2617 * Color space is not full. The current work_color
2618 * becomes our flush_color and work_color is advanced
2621 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
));
2622 this_flusher
.flush_color
= wq
->work_color
;
2623 wq
->work_color
= next_color
;
2625 if (!wq
->first_flusher
) {
2626 /* no flush in progress, become the first flusher */
2627 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2629 wq
->first_flusher
= &this_flusher
;
2631 if (!flush_workqueue_prep_pwqs(wq
, wq
->flush_color
,
2633 /* nothing to flush, done */
2634 wq
->flush_color
= next_color
;
2635 wq
->first_flusher
= NULL
;
2640 WARN_ON_ONCE(wq
->flush_color
== this_flusher
.flush_color
);
2641 list_add_tail(&this_flusher
.list
, &wq
->flusher_queue
);
2642 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2646 * Oops, color space is full, wait on overflow queue.
2647 * The next flush completion will assign us
2648 * flush_color and transfer to flusher_queue.
2650 list_add_tail(&this_flusher
.list
, &wq
->flusher_overflow
);
2653 check_flush_dependency(wq
, NULL
);
2655 mutex_unlock(&wq
->mutex
);
2657 wait_for_completion(&this_flusher
.done
);
2660 * Wake-up-and-cascade phase
2662 * First flushers are responsible for cascading flushes and
2663 * handling overflow. Non-first flushers can simply return.
2665 if (wq
->first_flusher
!= &this_flusher
)
2668 mutex_lock(&wq
->mutex
);
2670 /* we might have raced, check again with mutex held */
2671 if (wq
->first_flusher
!= &this_flusher
)
2674 wq
->first_flusher
= NULL
;
2676 WARN_ON_ONCE(!list_empty(&this_flusher
.list
));
2677 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2680 struct wq_flusher
*next
, *tmp
;
2682 /* complete all the flushers sharing the current flush color */
2683 list_for_each_entry_safe(next
, tmp
, &wq
->flusher_queue
, list
) {
2684 if (next
->flush_color
!= wq
->flush_color
)
2686 list_del_init(&next
->list
);
2687 complete(&next
->done
);
2690 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
) &&
2691 wq
->flush_color
!= work_next_color(wq
->work_color
));
2693 /* this flush_color is finished, advance by one */
2694 wq
->flush_color
= work_next_color(wq
->flush_color
);
2696 /* one color has been freed, handle overflow queue */
2697 if (!list_empty(&wq
->flusher_overflow
)) {
2699 * Assign the same color to all overflowed
2700 * flushers, advance work_color and append to
2701 * flusher_queue. This is the start-to-wait
2702 * phase for these overflowed flushers.
2704 list_for_each_entry(tmp
, &wq
->flusher_overflow
, list
)
2705 tmp
->flush_color
= wq
->work_color
;
2707 wq
->work_color
= work_next_color(wq
->work_color
);
2709 list_splice_tail_init(&wq
->flusher_overflow
,
2710 &wq
->flusher_queue
);
2711 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2714 if (list_empty(&wq
->flusher_queue
)) {
2715 WARN_ON_ONCE(wq
->flush_color
!= wq
->work_color
);
2720 * Need to flush more colors. Make the next flusher
2721 * the new first flusher and arm pwqs.
2723 WARN_ON_ONCE(wq
->flush_color
== wq
->work_color
);
2724 WARN_ON_ONCE(wq
->flush_color
!= next
->flush_color
);
2726 list_del_init(&next
->list
);
2727 wq
->first_flusher
= next
;
2729 if (flush_workqueue_prep_pwqs(wq
, wq
->flush_color
, -1))
2733 * Meh... this color is already done, clear first
2734 * flusher and repeat cascading.
2736 wq
->first_flusher
= NULL
;
2740 mutex_unlock(&wq
->mutex
);
2742 EXPORT_SYMBOL(flush_workqueue
);
2745 * drain_workqueue - drain a workqueue
2746 * @wq: workqueue to drain
2748 * Wait until the workqueue becomes empty. While draining is in progress,
2749 * only chain queueing is allowed. IOW, only currently pending or running
2750 * work items on @wq can queue further work items on it. @wq is flushed
2751 * repeatedly until it becomes empty. The number of flushing is determined
2752 * by the depth of chaining and should be relatively short. Whine if it
2755 void drain_workqueue(struct workqueue_struct
*wq
)
2757 unsigned int flush_cnt
= 0;
2758 struct pool_workqueue
*pwq
;
2761 * __queue_work() needs to test whether there are drainers, is much
2762 * hotter than drain_workqueue() and already looks at @wq->flags.
2763 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
2765 mutex_lock(&wq
->mutex
);
2766 if (!wq
->nr_drainers
++)
2767 wq
->flags
|= __WQ_DRAINING
;
2768 mutex_unlock(&wq
->mutex
);
2770 flush_workqueue(wq
);
2772 mutex_lock(&wq
->mutex
);
2774 for_each_pwq(pwq
, wq
) {
2777 spin_lock_irq(&pwq
->pool
->lock
);
2778 drained
= !pwq
->nr_active
&& list_empty(&pwq
->delayed_works
);
2779 spin_unlock_irq(&pwq
->pool
->lock
);
2784 if (++flush_cnt
== 10 ||
2785 (flush_cnt
% 100 == 0 && flush_cnt
<= 1000))
2786 pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
2787 wq
->name
, flush_cnt
);
2789 mutex_unlock(&wq
->mutex
);
2793 if (!--wq
->nr_drainers
)
2794 wq
->flags
&= ~__WQ_DRAINING
;
2795 mutex_unlock(&wq
->mutex
);
2797 EXPORT_SYMBOL_GPL(drain_workqueue
);
2799 static bool start_flush_work(struct work_struct
*work
, struct wq_barrier
*barr
)
2801 struct worker
*worker
= NULL
;
2802 struct worker_pool
*pool
;
2803 struct pool_workqueue
*pwq
;
2807 local_irq_disable();
2808 pool
= get_work_pool(work
);
2814 spin_lock(&pool
->lock
);
2815 /* see the comment in try_to_grab_pending() with the same code */
2816 pwq
= get_work_pwq(work
);
2818 if (unlikely(pwq
->pool
!= pool
))
2821 worker
= find_worker_executing_work(pool
, work
);
2824 pwq
= worker
->current_pwq
;
2827 check_flush_dependency(pwq
->wq
, work
);
2829 insert_wq_barrier(pwq
, barr
, work
, worker
);
2830 spin_unlock_irq(&pool
->lock
);
2833 * Force a lock recursion deadlock when using flush_work() inside a
2834 * single-threaded or rescuer equipped workqueue.
2836 * For single threaded workqueues the deadlock happens when the work
2837 * is after the work issuing the flush_work(). For rescuer equipped
2838 * workqueues the deadlock happens when the rescuer stalls, blocking
2841 if (pwq
->wq
->saved_max_active
== 1 || pwq
->wq
->rescuer
) {
2842 lock_map_acquire(&pwq
->wq
->lockdep_map
);
2843 lock_map_release(&pwq
->wq
->lockdep_map
);
2848 spin_unlock_irq(&pool
->lock
);
2853 * flush_work - wait for a work to finish executing the last queueing instance
2854 * @work: the work to flush
2856 * Wait until @work has finished execution. @work is guaranteed to be idle
2857 * on return if it hasn't been requeued since flush started.
2860 * %true if flush_work() waited for the work to finish execution,
2861 * %false if it was already idle.
2863 bool flush_work(struct work_struct
*work
)
2865 struct wq_barrier barr
;
2867 if (WARN_ON(!wq_online
))
2870 if (start_flush_work(work
, &barr
)) {
2871 wait_for_completion(&barr
.done
);
2872 destroy_work_on_stack(&barr
.work
);
2878 EXPORT_SYMBOL_GPL(flush_work
);
2881 wait_queue_entry_t wait
;
2882 struct work_struct
*work
;
2885 static int cwt_wakefn(wait_queue_entry_t
*wait
, unsigned mode
, int sync
, void *key
)
2887 struct cwt_wait
*cwait
= container_of(wait
, struct cwt_wait
, wait
);
2889 if (cwait
->work
!= key
)
2891 return autoremove_wake_function(wait
, mode
, sync
, key
);
2894 static bool __cancel_work_timer(struct work_struct
*work
, bool is_dwork
)
2896 static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq
);
2897 unsigned long flags
;
2901 ret
= try_to_grab_pending(work
, is_dwork
, &flags
);
2903 * If someone else is already canceling, wait for it to
2904 * finish. flush_work() doesn't work for PREEMPT_NONE
2905 * because we may get scheduled between @work's completion
2906 * and the other canceling task resuming and clearing
2907 * CANCELING - flush_work() will return false immediately
2908 * as @work is no longer busy, try_to_grab_pending() will
2909 * return -ENOENT as @work is still being canceled and the
2910 * other canceling task won't be able to clear CANCELING as
2911 * we're hogging the CPU.
2913 * Let's wait for completion using a waitqueue. As this
2914 * may lead to the thundering herd problem, use a custom
2915 * wake function which matches @work along with exclusive
2918 if (unlikely(ret
== -ENOENT
)) {
2919 struct cwt_wait cwait
;
2921 init_wait(&cwait
.wait
);
2922 cwait
.wait
.func
= cwt_wakefn
;
2925 prepare_to_wait_exclusive(&cancel_waitq
, &cwait
.wait
,
2926 TASK_UNINTERRUPTIBLE
);
2927 if (work_is_canceling(work
))
2929 finish_wait(&cancel_waitq
, &cwait
.wait
);
2931 } while (unlikely(ret
< 0));
2933 /* tell other tasks trying to grab @work to back off */
2934 mark_work_canceling(work
);
2935 local_irq_restore(flags
);
2938 * This allows canceling during early boot. We know that @work
2944 clear_work_data(work
);
2947 * Paired with prepare_to_wait() above so that either
2948 * waitqueue_active() is visible here or !work_is_canceling() is
2952 if (waitqueue_active(&cancel_waitq
))
2953 __wake_up(&cancel_waitq
, TASK_NORMAL
, 1, work
);
2959 * cancel_work_sync - cancel a work and wait for it to finish
2960 * @work: the work to cancel
2962 * Cancel @work and wait for its execution to finish. This function
2963 * can be used even if the work re-queues itself or migrates to
2964 * another workqueue. On return from this function, @work is
2965 * guaranteed to be not pending or executing on any CPU.
2967 * cancel_work_sync(&delayed_work->work) must not be used for
2968 * delayed_work's. Use cancel_delayed_work_sync() instead.
2970 * The caller must ensure that the workqueue on which @work was last
2971 * queued can't be destroyed before this function returns.
2974 * %true if @work was pending, %false otherwise.
2976 bool cancel_work_sync(struct work_struct
*work
)
2978 return __cancel_work_timer(work
, false);
2980 EXPORT_SYMBOL_GPL(cancel_work_sync
);
2983 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2984 * @dwork: the delayed work to flush
2986 * Delayed timer is cancelled and the pending work is queued for
2987 * immediate execution. Like flush_work(), this function only
2988 * considers the last queueing instance of @dwork.
2991 * %true if flush_work() waited for the work to finish execution,
2992 * %false if it was already idle.
2994 bool flush_delayed_work(struct delayed_work
*dwork
)
2996 local_irq_disable();
2997 if (del_timer_sync(&dwork
->timer
))
2998 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
3000 return flush_work(&dwork
->work
);
3002 EXPORT_SYMBOL(flush_delayed_work
);
3004 static bool __cancel_work(struct work_struct
*work
, bool is_dwork
)
3006 unsigned long flags
;
3010 ret
= try_to_grab_pending(work
, is_dwork
, &flags
);
3011 } while (unlikely(ret
== -EAGAIN
));
3013 if (unlikely(ret
< 0))
3016 set_work_pool_and_clear_pending(work
, get_work_pool_id(work
));
3017 local_irq_restore(flags
);
3022 * See cancel_delayed_work()
3024 bool cancel_work(struct work_struct
*work
)
3026 return __cancel_work(work
, false);
3030 * cancel_delayed_work - cancel a delayed work
3031 * @dwork: delayed_work to cancel
3033 * Kill off a pending delayed_work.
3035 * Return: %true if @dwork was pending and canceled; %false if it wasn't
3039 * The work callback function may still be running on return, unless
3040 * it returns %true and the work doesn't re-arm itself. Explicitly flush or
3041 * use cancel_delayed_work_sync() to wait on it.
3043 * This function is safe to call from any context including IRQ handler.
3045 bool cancel_delayed_work(struct delayed_work
*dwork
)
3047 return __cancel_work(&dwork
->work
, true);
3049 EXPORT_SYMBOL(cancel_delayed_work
);
3052 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
3053 * @dwork: the delayed work cancel
3055 * This is cancel_work_sync() for delayed works.
3058 * %true if @dwork was pending, %false otherwise.
3060 bool cancel_delayed_work_sync(struct delayed_work
*dwork
)
3062 return __cancel_work_timer(&dwork
->work
, true);
3064 EXPORT_SYMBOL(cancel_delayed_work_sync
);
3067 * schedule_on_each_cpu - execute a function synchronously on each online CPU
3068 * @func: the function to call
3070 * schedule_on_each_cpu() executes @func on each online CPU using the
3071 * system workqueue and blocks until all CPUs have completed.
3072 * schedule_on_each_cpu() is very slow.
3075 * 0 on success, -errno on failure.
3077 int schedule_on_each_cpu(work_func_t func
)
3080 struct work_struct __percpu
*works
;
3082 works
= alloc_percpu(struct work_struct
);
3088 for_each_online_cpu(cpu
) {
3089 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
3091 INIT_WORK(work
, func
);
3092 schedule_work_on(cpu
, work
);
3095 for_each_online_cpu(cpu
)
3096 flush_work(per_cpu_ptr(works
, cpu
));
3104 * execute_in_process_context - reliably execute the routine with user context
3105 * @fn: the function to execute
3106 * @ew: guaranteed storage for the execute work structure (must
3107 * be available when the work executes)
3109 * Executes the function immediately if process context is available,
3110 * otherwise schedules the function for delayed execution.
3112 * Return: 0 - function was executed
3113 * 1 - function was scheduled for execution
3115 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
3117 if (!in_interrupt()) {
3122 INIT_WORK(&ew
->work
, fn
);
3123 schedule_work(&ew
->work
);
3127 EXPORT_SYMBOL_GPL(execute_in_process_context
);
3130 * free_workqueue_attrs - free a workqueue_attrs
3131 * @attrs: workqueue_attrs to free
3133 * Undo alloc_workqueue_attrs().
3135 void free_workqueue_attrs(struct workqueue_attrs
*attrs
)
3138 free_cpumask_var(attrs
->cpumask
);
3144 * alloc_workqueue_attrs - allocate a workqueue_attrs
3145 * @gfp_mask: allocation mask to use
3147 * Allocate a new workqueue_attrs, initialize with default settings and
3150 * Return: The allocated new workqueue_attr on success. %NULL on failure.
3152 struct workqueue_attrs
*alloc_workqueue_attrs(gfp_t gfp_mask
)
3154 struct workqueue_attrs
*attrs
;
3156 attrs
= kzalloc(sizeof(*attrs
), gfp_mask
);
3159 if (!alloc_cpumask_var(&attrs
->cpumask
, gfp_mask
))
3162 cpumask_copy(attrs
->cpumask
, cpu_possible_mask
);
3165 free_workqueue_attrs(attrs
);
3169 static void copy_workqueue_attrs(struct workqueue_attrs
*to
,
3170 const struct workqueue_attrs
*from
)
3172 to
->nice
= from
->nice
;
3173 cpumask_copy(to
->cpumask
, from
->cpumask
);
3175 * Unlike hash and equality test, this function doesn't ignore
3176 * ->no_numa as it is used for both pool and wq attrs. Instead,
3177 * get_unbound_pool() explicitly clears ->no_numa after copying.
3179 to
->no_numa
= from
->no_numa
;
3182 /* hash value of the content of @attr */
3183 static u32
wqattrs_hash(const struct workqueue_attrs
*attrs
)
3187 hash
= jhash_1word(attrs
->nice
, hash
);
3188 hash
= jhash(cpumask_bits(attrs
->cpumask
),
3189 BITS_TO_LONGS(nr_cpumask_bits
) * sizeof(long), hash
);
3193 /* content equality test */
3194 static bool wqattrs_equal(const struct workqueue_attrs
*a
,
3195 const struct workqueue_attrs
*b
)
3197 if (a
->nice
!= b
->nice
)
3199 if (!cpumask_equal(a
->cpumask
, b
->cpumask
))
3205 * init_worker_pool - initialize a newly zalloc'd worker_pool
3206 * @pool: worker_pool to initialize
3208 * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs.
3210 * Return: 0 on success, -errno on failure. Even on failure, all fields
3211 * inside @pool proper are initialized and put_unbound_pool() can be called
3212 * on @pool safely to release it.
3214 static int init_worker_pool(struct worker_pool
*pool
)
3216 spin_lock_init(&pool
->lock
);
3219 pool
->node
= NUMA_NO_NODE
;
3220 pool
->flags
|= POOL_DISASSOCIATED
;
3221 pool
->watchdog_ts
= jiffies
;
3222 INIT_LIST_HEAD(&pool
->worklist
);
3223 INIT_LIST_HEAD(&pool
->idle_list
);
3224 hash_init(pool
->busy_hash
);
3226 timer_setup(&pool
->idle_timer
, idle_worker_timeout
, TIMER_DEFERRABLE
);
3228 timer_setup(&pool
->mayday_timer
, pool_mayday_timeout
, 0);
3230 mutex_init(&pool
->attach_mutex
);
3231 INIT_LIST_HEAD(&pool
->workers
);
3233 ida_init(&pool
->worker_ida
);
3234 INIT_HLIST_NODE(&pool
->hash_node
);
3237 /* shouldn't fail above this point */
3238 pool
->attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3244 static void rcu_free_wq(struct rcu_head
*rcu
)
3246 struct workqueue_struct
*wq
=
3247 container_of(rcu
, struct workqueue_struct
, rcu
);
3249 if (!(wq
->flags
& WQ_UNBOUND
))
3250 free_percpu(wq
->cpu_pwqs
);
3252 free_workqueue_attrs(wq
->unbound_attrs
);
3258 static void rcu_free_pool(struct rcu_head
*rcu
)
3260 struct worker_pool
*pool
= container_of(rcu
, struct worker_pool
, rcu
);
3262 ida_destroy(&pool
->worker_ida
);
3263 free_workqueue_attrs(pool
->attrs
);
3268 * put_unbound_pool - put a worker_pool
3269 * @pool: worker_pool to put
3271 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
3272 * safe manner. get_unbound_pool() calls this function on its failure path
3273 * and this function should be able to release pools which went through,
3274 * successfully or not, init_worker_pool().
3276 * Should be called with wq_pool_mutex held.
3278 static void put_unbound_pool(struct worker_pool
*pool
)
3280 DECLARE_COMPLETION_ONSTACK(detach_completion
);
3281 struct worker
*worker
;
3283 lockdep_assert_held(&wq_pool_mutex
);
3289 if (WARN_ON(!(pool
->cpu
< 0)) ||
3290 WARN_ON(!list_empty(&pool
->worklist
)))
3293 /* release id and unhash */
3295 idr_remove(&worker_pool_idr
, pool
->id
);
3296 hash_del(&pool
->hash_node
);
3299 * Become the manager and destroy all workers. This prevents
3300 * @pool's workers from blocking on attach_mutex. We're the last
3301 * manager and @pool gets freed with the flag set.
3303 spin_lock_irq(&pool
->lock
);
3304 wait_event_lock_irq(wq_manager_wait
,
3305 !(pool
->flags
& POOL_MANAGER_ACTIVE
), pool
->lock
);
3306 pool
->flags
|= POOL_MANAGER_ACTIVE
;
3308 while ((worker
= first_idle_worker(pool
)))
3309 destroy_worker(worker
);
3310 WARN_ON(pool
->nr_workers
|| pool
->nr_idle
);
3311 spin_unlock_irq(&pool
->lock
);
3313 mutex_lock(&pool
->attach_mutex
);
3314 if (!list_empty(&pool
->workers
))
3315 pool
->detach_completion
= &detach_completion
;
3316 mutex_unlock(&pool
->attach_mutex
);
3318 if (pool
->detach_completion
)
3319 wait_for_completion(pool
->detach_completion
);
3321 /* shut down the timers */
3322 del_timer_sync(&pool
->idle_timer
);
3323 del_timer_sync(&pool
->mayday_timer
);
3325 /* sched-RCU protected to allow dereferences from get_work_pool() */
3326 call_rcu_sched(&pool
->rcu
, rcu_free_pool
);
3330 * get_unbound_pool - get a worker_pool with the specified attributes
3331 * @attrs: the attributes of the worker_pool to get
3333 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3334 * reference count and return it. If there already is a matching
3335 * worker_pool, it will be used; otherwise, this function attempts to
3338 * Should be called with wq_pool_mutex held.
3340 * Return: On success, a worker_pool with the same attributes as @attrs.
3341 * On failure, %NULL.
3343 static struct worker_pool
*get_unbound_pool(const struct workqueue_attrs
*attrs
)
3345 u32 hash
= wqattrs_hash(attrs
);
3346 struct worker_pool
*pool
;
3348 int target_node
= NUMA_NO_NODE
;
3350 lockdep_assert_held(&wq_pool_mutex
);
3352 /* do we already have a matching pool? */
3353 hash_for_each_possible(unbound_pool_hash
, pool
, hash_node
, hash
) {
3354 if (wqattrs_equal(pool
->attrs
, attrs
)) {
3360 /* if cpumask is contained inside a NUMA node, we belong to that node */
3361 if (wq_numa_enabled
) {
3362 for_each_node(node
) {
3363 if (cpumask_subset(attrs
->cpumask
,
3364 wq_numa_possible_cpumask
[node
])) {
3371 /* nope, create a new one */
3372 pool
= kzalloc_node(sizeof(*pool
), GFP_KERNEL
, target_node
);
3373 if (!pool
|| init_worker_pool(pool
) < 0)
3376 lockdep_set_subclass(&pool
->lock
, 1); /* see put_pwq() */
3377 copy_workqueue_attrs(pool
->attrs
, attrs
);
3378 pool
->node
= target_node
;
3381 * no_numa isn't a worker_pool attribute, always clear it. See
3382 * 'struct workqueue_attrs' comments for detail.
3384 pool
->attrs
->no_numa
= false;
3386 if (worker_pool_assign_id(pool
) < 0)
3389 /* create and start the initial worker */
3390 if (wq_online
&& !create_worker(pool
))
3394 hash_add(unbound_pool_hash
, &pool
->hash_node
, hash
);
3399 put_unbound_pool(pool
);
3403 static void rcu_free_pwq(struct rcu_head
*rcu
)
3405 kmem_cache_free(pwq_cache
,
3406 container_of(rcu
, struct pool_workqueue
, rcu
));
3410 * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3411 * and needs to be destroyed.
3413 static void pwq_unbound_release_workfn(struct work_struct
*work
)
3415 struct pool_workqueue
*pwq
= container_of(work
, struct pool_workqueue
,
3416 unbound_release_work
);
3417 struct workqueue_struct
*wq
= pwq
->wq
;
3418 struct worker_pool
*pool
= pwq
->pool
;
3421 if (WARN_ON_ONCE(!(wq
->flags
& WQ_UNBOUND
)))
3424 mutex_lock(&wq
->mutex
);
3425 list_del_rcu(&pwq
->pwqs_node
);
3426 is_last
= list_empty(&wq
->pwqs
);
3427 mutex_unlock(&wq
->mutex
);
3429 mutex_lock(&wq_pool_mutex
);
3430 put_unbound_pool(pool
);
3431 mutex_unlock(&wq_pool_mutex
);
3433 call_rcu_sched(&pwq
->rcu
, rcu_free_pwq
);
3436 * If we're the last pwq going away, @wq is already dead and no one
3437 * is gonna access it anymore. Schedule RCU free.
3440 call_rcu_sched(&wq
->rcu
, rcu_free_wq
);
3444 * pwq_adjust_max_active - update a pwq's max_active to the current setting
3445 * @pwq: target pool_workqueue
3447 * If @pwq isn't freezing, set @pwq->max_active to the associated
3448 * workqueue's saved_max_active and activate delayed work items
3449 * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
3451 static void pwq_adjust_max_active(struct pool_workqueue
*pwq
)
3453 struct workqueue_struct
*wq
= pwq
->wq
;
3454 bool freezable
= wq
->flags
& WQ_FREEZABLE
;
3455 unsigned long flags
;
3457 /* for @wq->saved_max_active */
3458 lockdep_assert_held(&wq
->mutex
);
3460 /* fast exit for non-freezable wqs */
3461 if (!freezable
&& pwq
->max_active
== wq
->saved_max_active
)
3464 /* this function can be called during early boot w/ irq disabled */
3465 spin_lock_irqsave(&pwq
->pool
->lock
, flags
);
3468 * During [un]freezing, the caller is responsible for ensuring that
3469 * this function is called at least once after @workqueue_freezing
3470 * is updated and visible.
3472 if (!freezable
|| !workqueue_freezing
) {
3473 pwq
->max_active
= wq
->saved_max_active
;
3475 while (!list_empty(&pwq
->delayed_works
) &&
3476 pwq
->nr_active
< pwq
->max_active
)
3477 pwq_activate_first_delayed(pwq
);
3480 * Need to kick a worker after thawed or an unbound wq's
3481 * max_active is bumped. It's a slow path. Do it always.
3483 wake_up_worker(pwq
->pool
);
3485 pwq
->max_active
= 0;
3488 spin_unlock_irqrestore(&pwq
->pool
->lock
, flags
);
3491 /* initialize newly alloced @pwq which is associated with @wq and @pool */
3492 static void init_pwq(struct pool_workqueue
*pwq
, struct workqueue_struct
*wq
,
3493 struct worker_pool
*pool
)
3495 BUG_ON((unsigned long)pwq
& WORK_STRUCT_FLAG_MASK
);
3497 memset(pwq
, 0, sizeof(*pwq
));
3501 pwq
->flush_color
= -1;
3503 INIT_LIST_HEAD(&pwq
->delayed_works
);
3504 INIT_LIST_HEAD(&pwq
->pwqs_node
);
3505 INIT_LIST_HEAD(&pwq
->mayday_node
);
3506 INIT_WORK(&pwq
->unbound_release_work
, pwq_unbound_release_workfn
);
3509 /* sync @pwq with the current state of its associated wq and link it */
3510 static void link_pwq(struct pool_workqueue
*pwq
)
3512 struct workqueue_struct
*wq
= pwq
->wq
;
3514 lockdep_assert_held(&wq
->mutex
);
3516 /* may be called multiple times, ignore if already linked */
3517 if (!list_empty(&pwq
->pwqs_node
))
3520 /* set the matching work_color */
3521 pwq
->work_color
= wq
->work_color
;
3523 /* sync max_active to the current setting */
3524 pwq_adjust_max_active(pwq
);
3527 list_add_rcu(&pwq
->pwqs_node
, &wq
->pwqs
);
3530 /* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3531 static struct pool_workqueue
*alloc_unbound_pwq(struct workqueue_struct
*wq
,
3532 const struct workqueue_attrs
*attrs
)
3534 struct worker_pool
*pool
;
3535 struct pool_workqueue
*pwq
;
3537 lockdep_assert_held(&wq_pool_mutex
);
3539 pool
= get_unbound_pool(attrs
);
3543 pwq
= kmem_cache_alloc_node(pwq_cache
, GFP_KERNEL
, pool
->node
);
3545 put_unbound_pool(pool
);
3549 init_pwq(pwq
, wq
, pool
);
3554 * wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node
3555 * @attrs: the wq_attrs of the default pwq of the target workqueue
3556 * @node: the target NUMA node
3557 * @cpu_going_down: if >= 0, the CPU to consider as offline
3558 * @cpumask: outarg, the resulting cpumask
3560 * Calculate the cpumask a workqueue with @attrs should use on @node. If
3561 * @cpu_going_down is >= 0, that cpu is considered offline during
3562 * calculation. The result is stored in @cpumask.
3564 * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3565 * enabled and @node has online CPUs requested by @attrs, the returned
3566 * cpumask is the intersection of the possible CPUs of @node and
3569 * The caller is responsible for ensuring that the cpumask of @node stays
3572 * Return: %true if the resulting @cpumask is different from @attrs->cpumask,
3575 static bool wq_calc_node_cpumask(const struct workqueue_attrs
*attrs
, int node
,
3576 int cpu_going_down
, cpumask_t
*cpumask
)
3578 if (!wq_numa_enabled
|| attrs
->no_numa
)
3581 /* does @node have any online CPUs @attrs wants? */
3582 cpumask_and(cpumask
, cpumask_of_node(node
), attrs
->cpumask
);
3583 if (cpu_going_down
>= 0)
3584 cpumask_clear_cpu(cpu_going_down
, cpumask
);
3586 if (cpumask_empty(cpumask
))
3589 /* yeap, return possible CPUs in @node that @attrs wants */
3590 cpumask_and(cpumask
, attrs
->cpumask
, wq_numa_possible_cpumask
[node
]);
3592 if (cpumask_empty(cpumask
)) {
3593 pr_warn_once("WARNING: workqueue cpumask: online intersect > "
3594 "possible intersect\n");
3598 return !cpumask_equal(cpumask
, attrs
->cpumask
);
3601 cpumask_copy(cpumask
, attrs
->cpumask
);
3605 /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3606 static struct pool_workqueue
*numa_pwq_tbl_install(struct workqueue_struct
*wq
,
3608 struct pool_workqueue
*pwq
)
3610 struct pool_workqueue
*old_pwq
;
3612 lockdep_assert_held(&wq_pool_mutex
);
3613 lockdep_assert_held(&wq
->mutex
);
3615 /* link_pwq() can handle duplicate calls */
3618 old_pwq
= rcu_access_pointer(wq
->numa_pwq_tbl
[node
]);
3619 rcu_assign_pointer(wq
->numa_pwq_tbl
[node
], pwq
);
3623 /* context to store the prepared attrs & pwqs before applying */
3624 struct apply_wqattrs_ctx
{
3625 struct workqueue_struct
*wq
; /* target workqueue */
3626 struct workqueue_attrs
*attrs
; /* attrs to apply */
3627 struct list_head list
; /* queued for batching commit */
3628 struct pool_workqueue
*dfl_pwq
;
3629 struct pool_workqueue
*pwq_tbl
[];
3632 /* free the resources after success or abort */
3633 static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx
*ctx
)
3639 put_pwq_unlocked(ctx
->pwq_tbl
[node
]);
3640 put_pwq_unlocked(ctx
->dfl_pwq
);
3642 free_workqueue_attrs(ctx
->attrs
);
3648 /* allocate the attrs and pwqs for later installation */
3649 static struct apply_wqattrs_ctx
*
3650 apply_wqattrs_prepare(struct workqueue_struct
*wq
,
3651 const struct workqueue_attrs
*attrs
)
3653 struct apply_wqattrs_ctx
*ctx
;
3654 struct workqueue_attrs
*new_attrs
, *tmp_attrs
;
3657 lockdep_assert_held(&wq_pool_mutex
);
3659 ctx
= kzalloc(sizeof(*ctx
) + nr_node_ids
* sizeof(ctx
->pwq_tbl
[0]),
3662 new_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3663 tmp_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3664 if (!ctx
|| !new_attrs
|| !tmp_attrs
)
3668 * Calculate the attrs of the default pwq.
3669 * If the user configured cpumask doesn't overlap with the
3670 * wq_unbound_cpumask, we fallback to the wq_unbound_cpumask.
3672 copy_workqueue_attrs(new_attrs
, attrs
);
3673 cpumask_and(new_attrs
->cpumask
, new_attrs
->cpumask
, wq_unbound_cpumask
);
3674 if (unlikely(cpumask_empty(new_attrs
->cpumask
)))
3675 cpumask_copy(new_attrs
->cpumask
, wq_unbound_cpumask
);
3678 * We may create multiple pwqs with differing cpumasks. Make a
3679 * copy of @new_attrs which will be modified and used to obtain
3682 copy_workqueue_attrs(tmp_attrs
, new_attrs
);
3685 * If something goes wrong during CPU up/down, we'll fall back to
3686 * the default pwq covering whole @attrs->cpumask. Always create
3687 * it even if we don't use it immediately.
3689 ctx
->dfl_pwq
= alloc_unbound_pwq(wq
, new_attrs
);
3693 for_each_node(node
) {
3694 if (wq_calc_node_cpumask(new_attrs
, node
, -1, tmp_attrs
->cpumask
)) {
3695 ctx
->pwq_tbl
[node
] = alloc_unbound_pwq(wq
, tmp_attrs
);
3696 if (!ctx
->pwq_tbl
[node
])
3699 ctx
->dfl_pwq
->refcnt
++;
3700 ctx
->pwq_tbl
[node
] = ctx
->dfl_pwq
;
3704 /* save the user configured attrs and sanitize it. */
3705 copy_workqueue_attrs(new_attrs
, attrs
);
3706 cpumask_and(new_attrs
->cpumask
, new_attrs
->cpumask
, cpu_possible_mask
);
3707 ctx
->attrs
= new_attrs
;
3710 free_workqueue_attrs(tmp_attrs
);
3714 free_workqueue_attrs(tmp_attrs
);
3715 free_workqueue_attrs(new_attrs
);
3716 apply_wqattrs_cleanup(ctx
);
3720 /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */
3721 static void apply_wqattrs_commit(struct apply_wqattrs_ctx
*ctx
)
3725 /* all pwqs have been created successfully, let's install'em */
3726 mutex_lock(&ctx
->wq
->mutex
);
3728 copy_workqueue_attrs(ctx
->wq
->unbound_attrs
, ctx
->attrs
);
3730 /* save the previous pwq and install the new one */
3732 ctx
->pwq_tbl
[node
] = numa_pwq_tbl_install(ctx
->wq
, node
,
3733 ctx
->pwq_tbl
[node
]);
3735 /* @dfl_pwq might not have been used, ensure it's linked */
3736 link_pwq(ctx
->dfl_pwq
);
3737 swap(ctx
->wq
->dfl_pwq
, ctx
->dfl_pwq
);
3739 mutex_unlock(&ctx
->wq
->mutex
);
3742 static void apply_wqattrs_lock(void)
3744 /* CPUs should stay stable across pwq creations and installations */
3746 mutex_lock(&wq_pool_mutex
);
3749 static void apply_wqattrs_unlock(void)
3751 mutex_unlock(&wq_pool_mutex
);
3755 static int apply_workqueue_attrs_locked(struct workqueue_struct
*wq
,
3756 const struct workqueue_attrs
*attrs
)
3758 struct apply_wqattrs_ctx
*ctx
;
3760 /* only unbound workqueues can change attributes */
3761 if (WARN_ON(!(wq
->flags
& WQ_UNBOUND
)))
3764 /* creating multiple pwqs breaks ordering guarantee */
3765 if (!list_empty(&wq
->pwqs
)) {
3766 if (WARN_ON(wq
->flags
& __WQ_ORDERED_EXPLICIT
))
3769 wq
->flags
&= ~__WQ_ORDERED
;
3772 ctx
= apply_wqattrs_prepare(wq
, attrs
);
3776 /* the ctx has been prepared successfully, let's commit it */
3777 apply_wqattrs_commit(ctx
);
3778 apply_wqattrs_cleanup(ctx
);
3784 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
3785 * @wq: the target workqueue
3786 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
3788 * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
3789 * machines, this function maps a separate pwq to each NUMA node with
3790 * possibles CPUs in @attrs->cpumask so that work items are affine to the
3791 * NUMA node it was issued on. Older pwqs are released as in-flight work
3792 * items finish. Note that a work item which repeatedly requeues itself
3793 * back-to-back will stay on its current pwq.
3795 * Performs GFP_KERNEL allocations.
3797 * Return: 0 on success and -errno on failure.
3799 int apply_workqueue_attrs(struct workqueue_struct
*wq
,
3800 const struct workqueue_attrs
*attrs
)
3804 apply_wqattrs_lock();
3805 ret
= apply_workqueue_attrs_locked(wq
, attrs
);
3806 apply_wqattrs_unlock();
3810 EXPORT_SYMBOL_GPL(apply_workqueue_attrs
);
3813 * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
3814 * @wq: the target workqueue
3815 * @cpu: the CPU coming up or going down
3816 * @online: whether @cpu is coming up or going down
3818 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
3819 * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
3822 * If NUMA affinity can't be adjusted due to memory allocation failure, it
3823 * falls back to @wq->dfl_pwq which may not be optimal but is always
3826 * Note that when the last allowed CPU of a NUMA node goes offline for a
3827 * workqueue with a cpumask spanning multiple nodes, the workers which were
3828 * already executing the work items for the workqueue will lose their CPU
3829 * affinity and may execute on any CPU. This is similar to how per-cpu
3830 * workqueues behave on CPU_DOWN. If a workqueue user wants strict
3831 * affinity, it's the user's responsibility to flush the work item from
3834 static void wq_update_unbound_numa(struct workqueue_struct
*wq
, int cpu
,
3837 int node
= cpu_to_node(cpu
);
3838 int cpu_off
= online
? -1 : cpu
;
3839 struct pool_workqueue
*old_pwq
= NULL
, *pwq
;
3840 struct workqueue_attrs
*target_attrs
;
3843 lockdep_assert_held(&wq_pool_mutex
);
3845 if (!wq_numa_enabled
|| !(wq
->flags
& WQ_UNBOUND
) ||
3846 wq
->unbound_attrs
->no_numa
)
3850 * We don't wanna alloc/free wq_attrs for each wq for each CPU.
3851 * Let's use a preallocated one. The following buf is protected by
3852 * CPU hotplug exclusion.
3854 target_attrs
= wq_update_unbound_numa_attrs_buf
;
3855 cpumask
= target_attrs
->cpumask
;
3857 copy_workqueue_attrs(target_attrs
, wq
->unbound_attrs
);
3858 pwq
= unbound_pwq_by_node(wq
, node
);
3861 * Let's determine what needs to be done. If the target cpumask is
3862 * different from the default pwq's, we need to compare it to @pwq's
3863 * and create a new one if they don't match. If the target cpumask
3864 * equals the default pwq's, the default pwq should be used.
3866 if (wq_calc_node_cpumask(wq
->dfl_pwq
->pool
->attrs
, node
, cpu_off
, cpumask
)) {
3867 if (cpumask_equal(cpumask
, pwq
->pool
->attrs
->cpumask
))
3873 /* create a new pwq */
3874 pwq
= alloc_unbound_pwq(wq
, target_attrs
);
3876 pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
3881 /* Install the new pwq. */
3882 mutex_lock(&wq
->mutex
);
3883 old_pwq
= numa_pwq_tbl_install(wq
, node
, pwq
);
3887 mutex_lock(&wq
->mutex
);
3888 spin_lock_irq(&wq
->dfl_pwq
->pool
->lock
);
3889 get_pwq(wq
->dfl_pwq
);
3890 spin_unlock_irq(&wq
->dfl_pwq
->pool
->lock
);
3891 old_pwq
= numa_pwq_tbl_install(wq
, node
, wq
->dfl_pwq
);
3893 mutex_unlock(&wq
->mutex
);
3894 put_pwq_unlocked(old_pwq
);
3897 static int alloc_and_link_pwqs(struct workqueue_struct
*wq
)
3899 bool highpri
= wq
->flags
& WQ_HIGHPRI
;
3902 if (!(wq
->flags
& WQ_UNBOUND
)) {
3903 wq
->cpu_pwqs
= alloc_percpu(struct pool_workqueue
);
3907 for_each_possible_cpu(cpu
) {
3908 struct pool_workqueue
*pwq
=
3909 per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
3910 struct worker_pool
*cpu_pools
=
3911 per_cpu(cpu_worker_pools
, cpu
);
3913 init_pwq(pwq
, wq
, &cpu_pools
[highpri
]);
3915 mutex_lock(&wq
->mutex
);
3917 mutex_unlock(&wq
->mutex
);
3920 } else if (wq
->flags
& __WQ_ORDERED
) {
3921 ret
= apply_workqueue_attrs(wq
, ordered_wq_attrs
[highpri
]);
3922 /* there should only be single pwq for ordering guarantee */
3923 WARN(!ret
&& (wq
->pwqs
.next
!= &wq
->dfl_pwq
->pwqs_node
||
3924 wq
->pwqs
.prev
!= &wq
->dfl_pwq
->pwqs_node
),
3925 "ordering guarantee broken for workqueue %s\n", wq
->name
);
3928 return apply_workqueue_attrs(wq
, unbound_std_wq_attrs
[highpri
]);
3932 static int wq_clamp_max_active(int max_active
, unsigned int flags
,
3935 int lim
= flags
& WQ_UNBOUND
? WQ_UNBOUND_MAX_ACTIVE
: WQ_MAX_ACTIVE
;
3937 if (max_active
< 1 || max_active
> lim
)
3938 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
3939 max_active
, name
, 1, lim
);
3941 return clamp_val(max_active
, 1, lim
);
3945 * Workqueues which may be used during memory reclaim should have a rescuer
3946 * to guarantee forward progress.
3948 static int init_rescuer(struct workqueue_struct
*wq
)
3950 struct worker
*rescuer
;
3953 if (!(wq
->flags
& WQ_MEM_RECLAIM
))
3956 rescuer
= alloc_worker(NUMA_NO_NODE
);
3960 rescuer
->rescue_wq
= wq
;
3961 rescuer
->task
= kthread_create(rescuer_thread
, rescuer
, "%s", wq
->name
);
3962 ret
= PTR_ERR_OR_ZERO(rescuer
->task
);
3968 wq
->rescuer
= rescuer
;
3969 kthread_bind_mask(rescuer
->task
, cpu_possible_mask
);
3970 wake_up_process(rescuer
->task
);
3975 struct workqueue_struct
*__alloc_workqueue_key(const char *fmt
,
3978 struct lock_class_key
*key
,
3979 const char *lock_name
, ...)
3981 size_t tbl_size
= 0;
3983 struct workqueue_struct
*wq
;
3984 struct pool_workqueue
*pwq
;
3987 * Unbound && max_active == 1 used to imply ordered, which is no
3988 * longer the case on NUMA machines due to per-node pools. While
3989 * alloc_ordered_workqueue() is the right way to create an ordered
3990 * workqueue, keep the previous behavior to avoid subtle breakages
3993 if ((flags
& WQ_UNBOUND
) && max_active
== 1)
3994 flags
|= __WQ_ORDERED
;
3996 /* see the comment above the definition of WQ_POWER_EFFICIENT */
3997 if ((flags
& WQ_POWER_EFFICIENT
) && wq_power_efficient
)
3998 flags
|= WQ_UNBOUND
;
4000 /* allocate wq and format name */
4001 if (flags
& WQ_UNBOUND
)
4002 tbl_size
= nr_node_ids
* sizeof(wq
->numa_pwq_tbl
[0]);
4004 wq
= kzalloc(sizeof(*wq
) + tbl_size
, GFP_KERNEL
);
4008 if (flags
& WQ_UNBOUND
) {
4009 wq
->unbound_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
4010 if (!wq
->unbound_attrs
)
4014 va_start(args
, lock_name
);
4015 vsnprintf(wq
->name
, sizeof(wq
->name
), fmt
, args
);
4018 max_active
= max_active
?: WQ_DFL_ACTIVE
;
4019 max_active
= wq_clamp_max_active(max_active
, flags
, wq
->name
);
4023 wq
->saved_max_active
= max_active
;
4024 mutex_init(&wq
->mutex
);
4025 atomic_set(&wq
->nr_pwqs_to_flush
, 0);
4026 INIT_LIST_HEAD(&wq
->pwqs
);
4027 INIT_LIST_HEAD(&wq
->flusher_queue
);
4028 INIT_LIST_HEAD(&wq
->flusher_overflow
);
4029 INIT_LIST_HEAD(&wq
->maydays
);
4031 lockdep_init_map(&wq
->lockdep_map
, lock_name
, key
, 0);
4032 INIT_LIST_HEAD(&wq
->list
);
4034 if (alloc_and_link_pwqs(wq
) < 0)
4037 if (wq_online
&& init_rescuer(wq
) < 0)
4040 if ((wq
->flags
& WQ_SYSFS
) && workqueue_sysfs_register(wq
))
4044 * wq_pool_mutex protects global freeze state and workqueues list.
4045 * Grab it, adjust max_active and add the new @wq to workqueues
4048 mutex_lock(&wq_pool_mutex
);
4050 mutex_lock(&wq
->mutex
);
4051 for_each_pwq(pwq
, wq
)
4052 pwq_adjust_max_active(pwq
);
4053 mutex_unlock(&wq
->mutex
);
4055 list_add_tail_rcu(&wq
->list
, &workqueues
);
4057 mutex_unlock(&wq_pool_mutex
);
4062 free_workqueue_attrs(wq
->unbound_attrs
);
4066 destroy_workqueue(wq
);
4069 EXPORT_SYMBOL_GPL(__alloc_workqueue_key
);
4072 * destroy_workqueue - safely terminate a workqueue
4073 * @wq: target workqueue
4075 * Safely destroy a workqueue. All work currently pending will be done first.
4077 void destroy_workqueue(struct workqueue_struct
*wq
)
4079 struct pool_workqueue
*pwq
;
4082 /* drain it before proceeding with destruction */
4083 drain_workqueue(wq
);
4086 mutex_lock(&wq
->mutex
);
4087 for_each_pwq(pwq
, wq
) {
4090 for (i
= 0; i
< WORK_NR_COLORS
; i
++) {
4091 if (WARN_ON(pwq
->nr_in_flight
[i
])) {
4092 mutex_unlock(&wq
->mutex
);
4093 show_workqueue_state();
4098 if (WARN_ON((pwq
!= wq
->dfl_pwq
) && (pwq
->refcnt
> 1)) ||
4099 WARN_ON(pwq
->nr_active
) ||
4100 WARN_ON(!list_empty(&pwq
->delayed_works
))) {
4101 mutex_unlock(&wq
->mutex
);
4102 show_workqueue_state();
4106 mutex_unlock(&wq
->mutex
);
4109 * wq list is used to freeze wq, remove from list after
4110 * flushing is complete in case freeze races us.
4112 mutex_lock(&wq_pool_mutex
);
4113 list_del_rcu(&wq
->list
);
4114 mutex_unlock(&wq_pool_mutex
);
4116 workqueue_sysfs_unregister(wq
);
4119 kthread_stop(wq
->rescuer
->task
);
4121 if (!(wq
->flags
& WQ_UNBOUND
)) {
4123 * The base ref is never dropped on per-cpu pwqs. Directly
4124 * schedule RCU free.
4126 call_rcu_sched(&wq
->rcu
, rcu_free_wq
);
4129 * We're the sole accessor of @wq at this point. Directly
4130 * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
4131 * @wq will be freed when the last pwq is released.
4133 for_each_node(node
) {
4134 pwq
= rcu_access_pointer(wq
->numa_pwq_tbl
[node
]);
4135 RCU_INIT_POINTER(wq
->numa_pwq_tbl
[node
], NULL
);
4136 put_pwq_unlocked(pwq
);
4140 * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
4141 * put. Don't access it afterwards.
4145 put_pwq_unlocked(pwq
);
4148 EXPORT_SYMBOL_GPL(destroy_workqueue
);
4151 * workqueue_set_max_active - adjust max_active of a workqueue
4152 * @wq: target workqueue
4153 * @max_active: new max_active value.
4155 * Set max_active of @wq to @max_active.
4158 * Don't call from IRQ context.
4160 void workqueue_set_max_active(struct workqueue_struct
*wq
, int max_active
)
4162 struct pool_workqueue
*pwq
;
4164 /* disallow meddling with max_active for ordered workqueues */
4165 if (WARN_ON(wq
->flags
& __WQ_ORDERED_EXPLICIT
))
4168 max_active
= wq_clamp_max_active(max_active
, wq
->flags
, wq
->name
);
4170 mutex_lock(&wq
->mutex
);
4172 wq
->flags
&= ~__WQ_ORDERED
;
4173 wq
->saved_max_active
= max_active
;
4175 for_each_pwq(pwq
, wq
)
4176 pwq_adjust_max_active(pwq
);
4178 mutex_unlock(&wq
->mutex
);
4180 EXPORT_SYMBOL_GPL(workqueue_set_max_active
);
4183 * current_work - retrieve %current task's work struct
4185 * Determine if %current task is a workqueue worker and what it's working on.
4186 * Useful to find out the context that the %current task is running in.
4188 * Return: work struct if %current task is a workqueue worker, %NULL otherwise.
4190 struct work_struct
*current_work(void)
4192 struct worker
*worker
= current_wq_worker();
4194 return worker
? worker
->current_work
: NULL
;
4196 EXPORT_SYMBOL(current_work
);
4199 * current_is_workqueue_rescuer - is %current workqueue rescuer?
4201 * Determine whether %current is a workqueue rescuer. Can be used from
4202 * work functions to determine whether it's being run off the rescuer task.
4204 * Return: %true if %current is a workqueue rescuer. %false otherwise.
4206 bool current_is_workqueue_rescuer(void)
4208 struct worker
*worker
= current_wq_worker();
4210 return worker
&& worker
->rescue_wq
;
4214 * workqueue_congested - test whether a workqueue is congested
4215 * @cpu: CPU in question
4216 * @wq: target workqueue
4218 * Test whether @wq's cpu workqueue for @cpu is congested. There is
4219 * no synchronization around this function and the test result is
4220 * unreliable and only useful as advisory hints or for debugging.
4222 * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
4223 * Note that both per-cpu and unbound workqueues may be associated with
4224 * multiple pool_workqueues which have separate congested states. A
4225 * workqueue being congested on one CPU doesn't mean the workqueue is also
4226 * contested on other CPUs / NUMA nodes.
4229 * %true if congested, %false otherwise.
4231 bool workqueue_congested(int cpu
, struct workqueue_struct
*wq
)
4233 struct pool_workqueue
*pwq
;
4236 rcu_read_lock_sched();
4238 if (cpu
== WORK_CPU_UNBOUND
)
4239 cpu
= smp_processor_id();
4241 if (!(wq
->flags
& WQ_UNBOUND
))
4242 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
4244 pwq
= unbound_pwq_by_node(wq
, cpu_to_node(cpu
));
4246 ret
= !list_empty(&pwq
->delayed_works
);
4247 rcu_read_unlock_sched();
4251 EXPORT_SYMBOL_GPL(workqueue_congested
);
4254 * work_busy - test whether a work is currently pending or running
4255 * @work: the work to be tested
4257 * Test whether @work is currently pending or running. There is no
4258 * synchronization around this function and the test result is
4259 * unreliable and only useful as advisory hints or for debugging.
4262 * OR'd bitmask of WORK_BUSY_* bits.
4264 unsigned int work_busy(struct work_struct
*work
)
4266 struct worker_pool
*pool
;
4267 unsigned long flags
;
4268 unsigned int ret
= 0;
4270 if (work_pending(work
))
4271 ret
|= WORK_BUSY_PENDING
;
4273 local_irq_save(flags
);
4274 pool
= get_work_pool(work
);
4276 spin_lock(&pool
->lock
);
4277 if (find_worker_executing_work(pool
, work
))
4278 ret
|= WORK_BUSY_RUNNING
;
4279 spin_unlock(&pool
->lock
);
4281 local_irq_restore(flags
);
4285 EXPORT_SYMBOL_GPL(work_busy
);
4288 * set_worker_desc - set description for the current work item
4289 * @fmt: printf-style format string
4290 * @...: arguments for the format string
4292 * This function can be called by a running work function to describe what
4293 * the work item is about. If the worker task gets dumped, this
4294 * information will be printed out together to help debugging. The
4295 * description can be at most WORKER_DESC_LEN including the trailing '\0'.
4297 void set_worker_desc(const char *fmt
, ...)
4299 struct worker
*worker
= current_wq_worker();
4303 va_start(args
, fmt
);
4304 vsnprintf(worker
->desc
, sizeof(worker
->desc
), fmt
, args
);
4306 worker
->desc_valid
= true;
4311 * print_worker_info - print out worker information and description
4312 * @log_lvl: the log level to use when printing
4313 * @task: target task
4315 * If @task is a worker and currently executing a work item, print out the
4316 * name of the workqueue being serviced and worker description set with
4317 * set_worker_desc() by the currently executing work item.
4319 * This function can be safely called on any task as long as the
4320 * task_struct itself is accessible. While safe, this function isn't
4321 * synchronized and may print out mixups or garbages of limited length.
4323 void print_worker_info(const char *log_lvl
, struct task_struct
*task
)
4325 work_func_t
*fn
= NULL
;
4326 char name
[WQ_NAME_LEN
] = { };
4327 char desc
[WORKER_DESC_LEN
] = { };
4328 struct pool_workqueue
*pwq
= NULL
;
4329 struct workqueue_struct
*wq
= NULL
;
4330 bool desc_valid
= false;
4331 struct worker
*worker
;
4333 if (!(task
->flags
& PF_WQ_WORKER
))
4337 * This function is called without any synchronization and @task
4338 * could be in any state. Be careful with dereferences.
4340 worker
= kthread_probe_data(task
);
4343 * Carefully copy the associated workqueue's workfn and name. Keep
4344 * the original last '\0' in case the original contains garbage.
4346 probe_kernel_read(&fn
, &worker
->current_func
, sizeof(fn
));
4347 probe_kernel_read(&pwq
, &worker
->current_pwq
, sizeof(pwq
));
4348 probe_kernel_read(&wq
, &pwq
->wq
, sizeof(wq
));
4349 probe_kernel_read(name
, wq
->name
, sizeof(name
) - 1);
4351 /* copy worker description */
4352 probe_kernel_read(&desc_valid
, &worker
->desc_valid
, sizeof(desc_valid
));
4354 probe_kernel_read(desc
, worker
->desc
, sizeof(desc
) - 1);
4356 if (fn
|| name
[0] || desc
[0]) {
4357 printk("%sWorkqueue: %s %pf", log_lvl
, name
, fn
);
4359 pr_cont(" (%s)", desc
);
4364 static void pr_cont_pool_info(struct worker_pool
*pool
)
4366 pr_cont(" cpus=%*pbl", nr_cpumask_bits
, pool
->attrs
->cpumask
);
4367 if (pool
->node
!= NUMA_NO_NODE
)
4368 pr_cont(" node=%d", pool
->node
);
4369 pr_cont(" flags=0x%x nice=%d", pool
->flags
, pool
->attrs
->nice
);
4372 static void pr_cont_work(bool comma
, struct work_struct
*work
)
4374 if (work
->func
== wq_barrier_func
) {
4375 struct wq_barrier
*barr
;
4377 barr
= container_of(work
, struct wq_barrier
, work
);
4379 pr_cont("%s BAR(%d)", comma
? "," : "",
4380 task_pid_nr(barr
->task
));
4382 pr_cont("%s %pf", comma
? "," : "", work
->func
);
4386 static void show_pwq(struct pool_workqueue
*pwq
)
4388 struct worker_pool
*pool
= pwq
->pool
;
4389 struct work_struct
*work
;
4390 struct worker
*worker
;
4391 bool has_in_flight
= false, has_pending
= false;
4394 pr_info(" pwq %d:", pool
->id
);
4395 pr_cont_pool_info(pool
);
4397 pr_cont(" active=%d/%d%s\n", pwq
->nr_active
, pwq
->max_active
,
4398 !list_empty(&pwq
->mayday_node
) ? " MAYDAY" : "");
4400 hash_for_each(pool
->busy_hash
, bkt
, worker
, hentry
) {
4401 if (worker
->current_pwq
== pwq
) {
4402 has_in_flight
= true;
4406 if (has_in_flight
) {
4409 pr_info(" in-flight:");
4410 hash_for_each(pool
->busy_hash
, bkt
, worker
, hentry
) {
4411 if (worker
->current_pwq
!= pwq
)
4414 pr_cont("%s %d%s:%pf", comma
? "," : "",
4415 task_pid_nr(worker
->task
),
4416 worker
== pwq
->wq
->rescuer
? "(RESCUER)" : "",
4417 worker
->current_func
);
4418 list_for_each_entry(work
, &worker
->scheduled
, entry
)
4419 pr_cont_work(false, work
);
4425 list_for_each_entry(work
, &pool
->worklist
, entry
) {
4426 if (get_work_pwq(work
) == pwq
) {
4434 pr_info(" pending:");
4435 list_for_each_entry(work
, &pool
->worklist
, entry
) {
4436 if (get_work_pwq(work
) != pwq
)
4439 pr_cont_work(comma
, work
);
4440 comma
= !(*work_data_bits(work
) & WORK_STRUCT_LINKED
);
4445 if (!list_empty(&pwq
->delayed_works
)) {
4448 pr_info(" delayed:");
4449 list_for_each_entry(work
, &pwq
->delayed_works
, entry
) {
4450 pr_cont_work(comma
, work
);
4451 comma
= !(*work_data_bits(work
) & WORK_STRUCT_LINKED
);
4458 * show_workqueue_state - dump workqueue state
4460 * Called from a sysrq handler or try_to_freeze_tasks() and prints out
4461 * all busy workqueues and pools.
4463 void show_workqueue_state(void)
4465 struct workqueue_struct
*wq
;
4466 struct worker_pool
*pool
;
4467 unsigned long flags
;
4470 rcu_read_lock_sched();
4472 pr_info("Showing busy workqueues and worker pools:\n");
4474 list_for_each_entry_rcu(wq
, &workqueues
, list
) {
4475 struct pool_workqueue
*pwq
;
4478 for_each_pwq(pwq
, wq
) {
4479 if (pwq
->nr_active
|| !list_empty(&pwq
->delayed_works
)) {
4487 pr_info("workqueue %s: flags=0x%x\n", wq
->name
, wq
->flags
);
4489 for_each_pwq(pwq
, wq
) {
4490 spin_lock_irqsave(&pwq
->pool
->lock
, flags
);
4491 if (pwq
->nr_active
|| !list_empty(&pwq
->delayed_works
))
4493 spin_unlock_irqrestore(&pwq
->pool
->lock
, flags
);
4495 * We could be printing a lot from atomic context, e.g.
4496 * sysrq-t -> show_workqueue_state(). Avoid triggering
4499 touch_nmi_watchdog();
4503 for_each_pool(pool
, pi
) {
4504 struct worker
*worker
;
4507 spin_lock_irqsave(&pool
->lock
, flags
);
4508 if (pool
->nr_workers
== pool
->nr_idle
)
4511 pr_info("pool %d:", pool
->id
);
4512 pr_cont_pool_info(pool
);
4513 pr_cont(" hung=%us workers=%d",
4514 jiffies_to_msecs(jiffies
- pool
->watchdog_ts
) / 1000,
4517 pr_cont(" manager: %d",
4518 task_pid_nr(pool
->manager
->task
));
4519 list_for_each_entry(worker
, &pool
->idle_list
, entry
) {
4520 pr_cont(" %s%d", first
? "idle: " : "",
4521 task_pid_nr(worker
->task
));
4526 spin_unlock_irqrestore(&pool
->lock
, flags
);
4528 * We could be printing a lot from atomic context, e.g.
4529 * sysrq-t -> show_workqueue_state(). Avoid triggering
4532 touch_nmi_watchdog();
4535 rcu_read_unlock_sched();
4541 * There are two challenges in supporting CPU hotplug. Firstly, there
4542 * are a lot of assumptions on strong associations among work, pwq and
4543 * pool which make migrating pending and scheduled works very
4544 * difficult to implement without impacting hot paths. Secondly,
4545 * worker pools serve mix of short, long and very long running works making
4546 * blocked draining impractical.
4548 * This is solved by allowing the pools to be disassociated from the CPU
4549 * running as an unbound one and allowing it to be reattached later if the
4550 * cpu comes back online.
4553 static void unbind_workers(int cpu
)
4555 struct worker_pool
*pool
;
4556 struct worker
*worker
;
4558 for_each_cpu_worker_pool(pool
, cpu
) {
4559 mutex_lock(&pool
->attach_mutex
);
4560 spin_lock_irq(&pool
->lock
);
4563 * We've blocked all attach/detach operations. Make all workers
4564 * unbound and set DISASSOCIATED. Before this, all workers
4565 * except for the ones which are still executing works from
4566 * before the last CPU down must be on the cpu. After
4567 * this, they may become diasporas.
4569 for_each_pool_worker(worker
, pool
)
4570 worker
->flags
|= WORKER_UNBOUND
;
4572 pool
->flags
|= POOL_DISASSOCIATED
;
4574 spin_unlock_irq(&pool
->lock
);
4575 mutex_unlock(&pool
->attach_mutex
);
4578 * Call schedule() so that we cross rq->lock and thus can
4579 * guarantee sched callbacks see the %WORKER_UNBOUND flag.
4580 * This is necessary as scheduler callbacks may be invoked
4586 * Sched callbacks are disabled now. Zap nr_running.
4587 * After this, nr_running stays zero and need_more_worker()
4588 * and keep_working() are always true as long as the
4589 * worklist is not empty. This pool now behaves as an
4590 * unbound (in terms of concurrency management) pool which
4591 * are served by workers tied to the pool.
4593 atomic_set(&pool
->nr_running
, 0);
4596 * With concurrency management just turned off, a busy
4597 * worker blocking could lead to lengthy stalls. Kick off
4598 * unbound chain execution of currently pending work items.
4600 spin_lock_irq(&pool
->lock
);
4601 wake_up_worker(pool
);
4602 spin_unlock_irq(&pool
->lock
);
4607 * rebind_workers - rebind all workers of a pool to the associated CPU
4608 * @pool: pool of interest
4610 * @pool->cpu is coming online. Rebind all workers to the CPU.
4612 static void rebind_workers(struct worker_pool
*pool
)
4614 struct worker
*worker
;
4616 lockdep_assert_held(&pool
->attach_mutex
);
4619 * Restore CPU affinity of all workers. As all idle workers should
4620 * be on the run-queue of the associated CPU before any local
4621 * wake-ups for concurrency management happen, restore CPU affinity
4622 * of all workers first and then clear UNBOUND. As we're called
4623 * from CPU_ONLINE, the following shouldn't fail.
4625 for_each_pool_worker(worker
, pool
)
4626 WARN_ON_ONCE(set_cpus_allowed_ptr(worker
->task
,
4627 pool
->attrs
->cpumask
) < 0);
4629 spin_lock_irq(&pool
->lock
);
4631 pool
->flags
&= ~POOL_DISASSOCIATED
;
4633 for_each_pool_worker(worker
, pool
) {
4634 unsigned int worker_flags
= worker
->flags
;
4637 * A bound idle worker should actually be on the runqueue
4638 * of the associated CPU for local wake-ups targeting it to
4639 * work. Kick all idle workers so that they migrate to the
4640 * associated CPU. Doing this in the same loop as
4641 * replacing UNBOUND with REBOUND is safe as no worker will
4642 * be bound before @pool->lock is released.
4644 if (worker_flags
& WORKER_IDLE
)
4645 wake_up_process(worker
->task
);
4648 * We want to clear UNBOUND but can't directly call
4649 * worker_clr_flags() or adjust nr_running. Atomically
4650 * replace UNBOUND with another NOT_RUNNING flag REBOUND.
4651 * @worker will clear REBOUND using worker_clr_flags() when
4652 * it initiates the next execution cycle thus restoring
4653 * concurrency management. Note that when or whether
4654 * @worker clears REBOUND doesn't affect correctness.
4656 * WRITE_ONCE() is necessary because @worker->flags may be
4657 * tested without holding any lock in
4658 * wq_worker_waking_up(). Without it, NOT_RUNNING test may
4659 * fail incorrectly leading to premature concurrency
4660 * management operations.
4662 WARN_ON_ONCE(!(worker_flags
& WORKER_UNBOUND
));
4663 worker_flags
|= WORKER_REBOUND
;
4664 worker_flags
&= ~WORKER_UNBOUND
;
4665 WRITE_ONCE(worker
->flags
, worker_flags
);
4668 spin_unlock_irq(&pool
->lock
);
4672 * restore_unbound_workers_cpumask - restore cpumask of unbound workers
4673 * @pool: unbound pool of interest
4674 * @cpu: the CPU which is coming up
4676 * An unbound pool may end up with a cpumask which doesn't have any online
4677 * CPUs. When a worker of such pool get scheduled, the scheduler resets
4678 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4679 * online CPU before, cpus_allowed of all its workers should be restored.
4681 static void restore_unbound_workers_cpumask(struct worker_pool
*pool
, int cpu
)
4683 static cpumask_t cpumask
;
4684 struct worker
*worker
;
4686 lockdep_assert_held(&pool
->attach_mutex
);
4688 /* is @cpu allowed for @pool? */
4689 if (!cpumask_test_cpu(cpu
, pool
->attrs
->cpumask
))
4692 cpumask_and(&cpumask
, pool
->attrs
->cpumask
, cpu_online_mask
);
4694 /* as we're called from CPU_ONLINE, the following shouldn't fail */
4695 for_each_pool_worker(worker
, pool
)
4696 WARN_ON_ONCE(set_cpus_allowed_ptr(worker
->task
, &cpumask
) < 0);
4699 int workqueue_prepare_cpu(unsigned int cpu
)
4701 struct worker_pool
*pool
;
4703 for_each_cpu_worker_pool(pool
, cpu
) {
4704 if (pool
->nr_workers
)
4706 if (!create_worker(pool
))
4712 int workqueue_online_cpu(unsigned int cpu
)
4714 struct worker_pool
*pool
;
4715 struct workqueue_struct
*wq
;
4718 mutex_lock(&wq_pool_mutex
);
4720 for_each_pool(pool
, pi
) {
4721 mutex_lock(&pool
->attach_mutex
);
4723 if (pool
->cpu
== cpu
)
4724 rebind_workers(pool
);
4725 else if (pool
->cpu
< 0)
4726 restore_unbound_workers_cpumask(pool
, cpu
);
4728 mutex_unlock(&pool
->attach_mutex
);
4731 /* update NUMA affinity of unbound workqueues */
4732 list_for_each_entry(wq
, &workqueues
, list
)
4733 wq_update_unbound_numa(wq
, cpu
, true);
4735 mutex_unlock(&wq_pool_mutex
);
4739 int workqueue_offline_cpu(unsigned int cpu
)
4741 struct workqueue_struct
*wq
;
4743 /* unbinding per-cpu workers should happen on the local CPU */
4744 if (WARN_ON(cpu
!= smp_processor_id()))
4747 unbind_workers(cpu
);
4749 /* update NUMA affinity of unbound workqueues */
4750 mutex_lock(&wq_pool_mutex
);
4751 list_for_each_entry(wq
, &workqueues
, list
)
4752 wq_update_unbound_numa(wq
, cpu
, false);
4753 mutex_unlock(&wq_pool_mutex
);
4760 struct work_for_cpu
{
4761 struct work_struct work
;
4767 static void work_for_cpu_fn(struct work_struct
*work
)
4769 struct work_for_cpu
*wfc
= container_of(work
, struct work_for_cpu
, work
);
4771 wfc
->ret
= wfc
->fn(wfc
->arg
);
4775 * work_on_cpu - run a function in thread context on a particular cpu
4776 * @cpu: the cpu to run on
4777 * @fn: the function to run
4778 * @arg: the function arg
4780 * It is up to the caller to ensure that the cpu doesn't go offline.
4781 * The caller must not hold any locks which would prevent @fn from completing.
4783 * Return: The value @fn returns.
4785 long work_on_cpu(int cpu
, long (*fn
)(void *), void *arg
)
4787 struct work_for_cpu wfc
= { .fn
= fn
, .arg
= arg
};
4789 INIT_WORK_ONSTACK(&wfc
.work
, work_for_cpu_fn
);
4790 schedule_work_on(cpu
, &wfc
.work
);
4791 flush_work(&wfc
.work
);
4792 destroy_work_on_stack(&wfc
.work
);
4795 EXPORT_SYMBOL_GPL(work_on_cpu
);
4798 * work_on_cpu_safe - run a function in thread context on a particular cpu
4799 * @cpu: the cpu to run on
4800 * @fn: the function to run
4801 * @arg: the function argument
4803 * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold
4804 * any locks which would prevent @fn from completing.
4806 * Return: The value @fn returns.
4808 long work_on_cpu_safe(int cpu
, long (*fn
)(void *), void *arg
)
4813 if (cpu_online(cpu
))
4814 ret
= work_on_cpu(cpu
, fn
, arg
);
4818 EXPORT_SYMBOL_GPL(work_on_cpu_safe
);
4819 #endif /* CONFIG_SMP */
4821 #ifdef CONFIG_FREEZER
4824 * freeze_workqueues_begin - begin freezing workqueues
4826 * Start freezing workqueues. After this function returns, all freezable
4827 * workqueues will queue new works to their delayed_works list instead of
4831 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4833 void freeze_workqueues_begin(void)
4835 struct workqueue_struct
*wq
;
4836 struct pool_workqueue
*pwq
;
4838 mutex_lock(&wq_pool_mutex
);
4840 WARN_ON_ONCE(workqueue_freezing
);
4841 workqueue_freezing
= true;
4843 list_for_each_entry(wq
, &workqueues
, list
) {
4844 mutex_lock(&wq
->mutex
);
4845 for_each_pwq(pwq
, wq
)
4846 pwq_adjust_max_active(pwq
);
4847 mutex_unlock(&wq
->mutex
);
4850 mutex_unlock(&wq_pool_mutex
);
4854 * freeze_workqueues_busy - are freezable workqueues still busy?
4856 * Check whether freezing is complete. This function must be called
4857 * between freeze_workqueues_begin() and thaw_workqueues().
4860 * Grabs and releases wq_pool_mutex.
4863 * %true if some freezable workqueues are still busy. %false if freezing
4866 bool freeze_workqueues_busy(void)
4869 struct workqueue_struct
*wq
;
4870 struct pool_workqueue
*pwq
;
4872 mutex_lock(&wq_pool_mutex
);
4874 WARN_ON_ONCE(!workqueue_freezing
);
4876 list_for_each_entry(wq
, &workqueues
, list
) {
4877 if (!(wq
->flags
& WQ_FREEZABLE
))
4880 * nr_active is monotonically decreasing. It's safe
4881 * to peek without lock.
4883 rcu_read_lock_sched();
4884 for_each_pwq(pwq
, wq
) {
4885 WARN_ON_ONCE(pwq
->nr_active
< 0);
4886 if (pwq
->nr_active
) {
4888 rcu_read_unlock_sched();
4892 rcu_read_unlock_sched();
4895 mutex_unlock(&wq_pool_mutex
);
4900 * thaw_workqueues - thaw workqueues
4902 * Thaw workqueues. Normal queueing is restored and all collected
4903 * frozen works are transferred to their respective pool worklists.
4906 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4908 void thaw_workqueues(void)
4910 struct workqueue_struct
*wq
;
4911 struct pool_workqueue
*pwq
;
4913 mutex_lock(&wq_pool_mutex
);
4915 if (!workqueue_freezing
)
4918 workqueue_freezing
= false;
4920 /* restore max_active and repopulate worklist */
4921 list_for_each_entry(wq
, &workqueues
, list
) {
4922 mutex_lock(&wq
->mutex
);
4923 for_each_pwq(pwq
, wq
)
4924 pwq_adjust_max_active(pwq
);
4925 mutex_unlock(&wq
->mutex
);
4929 mutex_unlock(&wq_pool_mutex
);
4931 #endif /* CONFIG_FREEZER */
4933 static int workqueue_apply_unbound_cpumask(void)
4937 struct workqueue_struct
*wq
;
4938 struct apply_wqattrs_ctx
*ctx
, *n
;
4940 lockdep_assert_held(&wq_pool_mutex
);
4942 list_for_each_entry(wq
, &workqueues
, list
) {
4943 if (!(wq
->flags
& WQ_UNBOUND
))
4945 /* creating multiple pwqs breaks ordering guarantee */
4946 if (wq
->flags
& __WQ_ORDERED
)
4949 ctx
= apply_wqattrs_prepare(wq
, wq
->unbound_attrs
);
4955 list_add_tail(&ctx
->list
, &ctxs
);
4958 list_for_each_entry_safe(ctx
, n
, &ctxs
, list
) {
4960 apply_wqattrs_commit(ctx
);
4961 apply_wqattrs_cleanup(ctx
);
4968 * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask
4969 * @cpumask: the cpumask to set
4971 * The low-level workqueues cpumask is a global cpumask that limits
4972 * the affinity of all unbound workqueues. This function check the @cpumask
4973 * and apply it to all unbound workqueues and updates all pwqs of them.
4975 * Retun: 0 - Success
4976 * -EINVAL - Invalid @cpumask
4977 * -ENOMEM - Failed to allocate memory for attrs or pwqs.
4979 int workqueue_set_unbound_cpumask(cpumask_var_t cpumask
)
4982 cpumask_var_t saved_cpumask
;
4984 if (!zalloc_cpumask_var(&saved_cpumask
, GFP_KERNEL
))
4988 * Not excluding isolated cpus on purpose.
4989 * If the user wishes to include them, we allow that.
4991 cpumask_and(cpumask
, cpumask
, cpu_possible_mask
);
4992 if (!cpumask_empty(cpumask
)) {
4993 apply_wqattrs_lock();
4995 /* save the old wq_unbound_cpumask. */
4996 cpumask_copy(saved_cpumask
, wq_unbound_cpumask
);
4998 /* update wq_unbound_cpumask at first and apply it to wqs. */
4999 cpumask_copy(wq_unbound_cpumask
, cpumask
);
5000 ret
= workqueue_apply_unbound_cpumask();
5002 /* restore the wq_unbound_cpumask when failed. */
5004 cpumask_copy(wq_unbound_cpumask
, saved_cpumask
);
5006 apply_wqattrs_unlock();
5009 free_cpumask_var(saved_cpumask
);
5015 * Workqueues with WQ_SYSFS flag set is visible to userland via
5016 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
5017 * following attributes.
5019 * per_cpu RO bool : whether the workqueue is per-cpu or unbound
5020 * max_active RW int : maximum number of in-flight work items
5022 * Unbound workqueues have the following extra attributes.
5024 * pool_ids RO int : the associated pool IDs for each node
5025 * nice RW int : nice value of the workers
5026 * cpumask RW mask : bitmask of allowed CPUs for the workers
5027 * numa RW bool : whether enable NUMA affinity
5030 struct workqueue_struct
*wq
;
5034 static struct workqueue_struct
*dev_to_wq(struct device
*dev
)
5036 struct wq_device
*wq_dev
= container_of(dev
, struct wq_device
, dev
);
5041 static ssize_t
per_cpu_show(struct device
*dev
, struct device_attribute
*attr
,
5044 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5046 return scnprintf(buf
, PAGE_SIZE
, "%d\n", (bool)!(wq
->flags
& WQ_UNBOUND
));
5048 static DEVICE_ATTR_RO(per_cpu
);
5050 static ssize_t
max_active_show(struct device
*dev
,
5051 struct device_attribute
*attr
, char *buf
)
5053 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5055 return scnprintf(buf
, PAGE_SIZE
, "%d\n", wq
->saved_max_active
);
5058 static ssize_t
max_active_store(struct device
*dev
,
5059 struct device_attribute
*attr
, const char *buf
,
5062 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5065 if (sscanf(buf
, "%d", &val
) != 1 || val
<= 0)
5068 workqueue_set_max_active(wq
, val
);
5071 static DEVICE_ATTR_RW(max_active
);
5073 static struct attribute
*wq_sysfs_attrs
[] = {
5074 &dev_attr_per_cpu
.attr
,
5075 &dev_attr_max_active
.attr
,
5078 ATTRIBUTE_GROUPS(wq_sysfs
);
5080 static ssize_t
wq_pool_ids_show(struct device
*dev
,
5081 struct device_attribute
*attr
, char *buf
)
5083 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5084 const char *delim
= "";
5085 int node
, written
= 0;
5087 rcu_read_lock_sched();
5088 for_each_node(node
) {
5089 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
,
5090 "%s%d:%d", delim
, node
,
5091 unbound_pwq_by_node(wq
, node
)->pool
->id
);
5094 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
, "\n");
5095 rcu_read_unlock_sched();
5100 static ssize_t
wq_nice_show(struct device
*dev
, struct device_attribute
*attr
,
5103 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5106 mutex_lock(&wq
->mutex
);
5107 written
= scnprintf(buf
, PAGE_SIZE
, "%d\n", wq
->unbound_attrs
->nice
);
5108 mutex_unlock(&wq
->mutex
);
5113 /* prepare workqueue_attrs for sysfs store operations */
5114 static struct workqueue_attrs
*wq_sysfs_prep_attrs(struct workqueue_struct
*wq
)
5116 struct workqueue_attrs
*attrs
;
5118 lockdep_assert_held(&wq_pool_mutex
);
5120 attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
5124 copy_workqueue_attrs(attrs
, wq
->unbound_attrs
);
5128 static ssize_t
wq_nice_store(struct device
*dev
, struct device_attribute
*attr
,
5129 const char *buf
, size_t count
)
5131 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5132 struct workqueue_attrs
*attrs
;
5135 apply_wqattrs_lock();
5137 attrs
= wq_sysfs_prep_attrs(wq
);
5141 if (sscanf(buf
, "%d", &attrs
->nice
) == 1 &&
5142 attrs
->nice
>= MIN_NICE
&& attrs
->nice
<= MAX_NICE
)
5143 ret
= apply_workqueue_attrs_locked(wq
, attrs
);
5148 apply_wqattrs_unlock();
5149 free_workqueue_attrs(attrs
);
5150 return ret
?: count
;
5153 static ssize_t
wq_cpumask_show(struct device
*dev
,
5154 struct device_attribute
*attr
, char *buf
)
5156 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5159 mutex_lock(&wq
->mutex
);
5160 written
= scnprintf(buf
, PAGE_SIZE
, "%*pb\n",
5161 cpumask_pr_args(wq
->unbound_attrs
->cpumask
));
5162 mutex_unlock(&wq
->mutex
);
5166 static ssize_t
wq_cpumask_store(struct device
*dev
,
5167 struct device_attribute
*attr
,
5168 const char *buf
, size_t count
)
5170 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5171 struct workqueue_attrs
*attrs
;
5174 apply_wqattrs_lock();
5176 attrs
= wq_sysfs_prep_attrs(wq
);
5180 ret
= cpumask_parse(buf
, attrs
->cpumask
);
5182 ret
= apply_workqueue_attrs_locked(wq
, attrs
);
5185 apply_wqattrs_unlock();
5186 free_workqueue_attrs(attrs
);
5187 return ret
?: count
;
5190 static ssize_t
wq_numa_show(struct device
*dev
, struct device_attribute
*attr
,
5193 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5196 mutex_lock(&wq
->mutex
);
5197 written
= scnprintf(buf
, PAGE_SIZE
, "%d\n",
5198 !wq
->unbound_attrs
->no_numa
);
5199 mutex_unlock(&wq
->mutex
);
5204 static ssize_t
wq_numa_store(struct device
*dev
, struct device_attribute
*attr
,
5205 const char *buf
, size_t count
)
5207 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5208 struct workqueue_attrs
*attrs
;
5209 int v
, ret
= -ENOMEM
;
5211 apply_wqattrs_lock();
5213 attrs
= wq_sysfs_prep_attrs(wq
);
5218 if (sscanf(buf
, "%d", &v
) == 1) {
5219 attrs
->no_numa
= !v
;
5220 ret
= apply_workqueue_attrs_locked(wq
, attrs
);
5224 apply_wqattrs_unlock();
5225 free_workqueue_attrs(attrs
);
5226 return ret
?: count
;
5229 static struct device_attribute wq_sysfs_unbound_attrs
[] = {
5230 __ATTR(pool_ids
, 0444, wq_pool_ids_show
, NULL
),
5231 __ATTR(nice
, 0644, wq_nice_show
, wq_nice_store
),
5232 __ATTR(cpumask
, 0644, wq_cpumask_show
, wq_cpumask_store
),
5233 __ATTR(numa
, 0644, wq_numa_show
, wq_numa_store
),
5237 static struct bus_type wq_subsys
= {
5238 .name
= "workqueue",
5239 .dev_groups
= wq_sysfs_groups
,
5242 static ssize_t
wq_unbound_cpumask_show(struct device
*dev
,
5243 struct device_attribute
*attr
, char *buf
)
5247 mutex_lock(&wq_pool_mutex
);
5248 written
= scnprintf(buf
, PAGE_SIZE
, "%*pb\n",
5249 cpumask_pr_args(wq_unbound_cpumask
));
5250 mutex_unlock(&wq_pool_mutex
);
5255 static ssize_t
wq_unbound_cpumask_store(struct device
*dev
,
5256 struct device_attribute
*attr
, const char *buf
, size_t count
)
5258 cpumask_var_t cpumask
;
5261 if (!zalloc_cpumask_var(&cpumask
, GFP_KERNEL
))
5264 ret
= cpumask_parse(buf
, cpumask
);
5266 ret
= workqueue_set_unbound_cpumask(cpumask
);
5268 free_cpumask_var(cpumask
);
5269 return ret
? ret
: count
;
5272 static struct device_attribute wq_sysfs_cpumask_attr
=
5273 __ATTR(cpumask
, 0644, wq_unbound_cpumask_show
,
5274 wq_unbound_cpumask_store
);
5276 static int __init
wq_sysfs_init(void)
5280 err
= subsys_virtual_register(&wq_subsys
, NULL
);
5284 return device_create_file(wq_subsys
.dev_root
, &wq_sysfs_cpumask_attr
);
5286 core_initcall(wq_sysfs_init
);
5288 static void wq_device_release(struct device
*dev
)
5290 struct wq_device
*wq_dev
= container_of(dev
, struct wq_device
, dev
);
5296 * workqueue_sysfs_register - make a workqueue visible in sysfs
5297 * @wq: the workqueue to register
5299 * Expose @wq in sysfs under /sys/bus/workqueue/devices.
5300 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
5301 * which is the preferred method.
5303 * Workqueue user should use this function directly iff it wants to apply
5304 * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
5305 * apply_workqueue_attrs() may race against userland updating the
5308 * Return: 0 on success, -errno on failure.
5310 int workqueue_sysfs_register(struct workqueue_struct
*wq
)
5312 struct wq_device
*wq_dev
;
5316 * Adjusting max_active or creating new pwqs by applying
5317 * attributes breaks ordering guarantee. Disallow exposing ordered
5320 if (WARN_ON(wq
->flags
& __WQ_ORDERED_EXPLICIT
))
5323 wq
->wq_dev
= wq_dev
= kzalloc(sizeof(*wq_dev
), GFP_KERNEL
);
5328 wq_dev
->dev
.bus
= &wq_subsys
;
5329 wq_dev
->dev
.release
= wq_device_release
;
5330 dev_set_name(&wq_dev
->dev
, "%s", wq
->name
);
5333 * unbound_attrs are created separately. Suppress uevent until
5334 * everything is ready.
5336 dev_set_uevent_suppress(&wq_dev
->dev
, true);
5338 ret
= device_register(&wq_dev
->dev
);
5345 if (wq
->flags
& WQ_UNBOUND
) {
5346 struct device_attribute
*attr
;
5348 for (attr
= wq_sysfs_unbound_attrs
; attr
->attr
.name
; attr
++) {
5349 ret
= device_create_file(&wq_dev
->dev
, attr
);
5351 device_unregister(&wq_dev
->dev
);
5358 dev_set_uevent_suppress(&wq_dev
->dev
, false);
5359 kobject_uevent(&wq_dev
->dev
.kobj
, KOBJ_ADD
);
5364 * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
5365 * @wq: the workqueue to unregister
5367 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
5369 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
)
5371 struct wq_device
*wq_dev
= wq
->wq_dev
;
5377 device_unregister(&wq_dev
->dev
);
5379 #else /* CONFIG_SYSFS */
5380 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
) { }
5381 #endif /* CONFIG_SYSFS */
5384 * Workqueue watchdog.
5386 * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal
5387 * flush dependency, a concurrency managed work item which stays RUNNING
5388 * indefinitely. Workqueue stalls can be very difficult to debug as the
5389 * usual warning mechanisms don't trigger and internal workqueue state is
5392 * Workqueue watchdog monitors all worker pools periodically and dumps
5393 * state if some pools failed to make forward progress for a while where
5394 * forward progress is defined as the first item on ->worklist changing.
5396 * This mechanism is controlled through the kernel parameter
5397 * "workqueue.watchdog_thresh" which can be updated at runtime through the
5398 * corresponding sysfs parameter file.
5400 #ifdef CONFIG_WQ_WATCHDOG
5402 static unsigned long wq_watchdog_thresh
= 30;
5403 static struct timer_list wq_watchdog_timer
;
5405 static unsigned long wq_watchdog_touched
= INITIAL_JIFFIES
;
5406 static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu
) = INITIAL_JIFFIES
;
5408 static void wq_watchdog_reset_touched(void)
5412 wq_watchdog_touched
= jiffies
;
5413 for_each_possible_cpu(cpu
)
5414 per_cpu(wq_watchdog_touched_cpu
, cpu
) = jiffies
;
5417 static void wq_watchdog_timer_fn(struct timer_list
*unused
)
5419 unsigned long thresh
= READ_ONCE(wq_watchdog_thresh
) * HZ
;
5420 bool lockup_detected
= false;
5421 struct worker_pool
*pool
;
5429 for_each_pool(pool
, pi
) {
5430 unsigned long pool_ts
, touched
, ts
;
5432 if (list_empty(&pool
->worklist
))
5435 /* get the latest of pool and touched timestamps */
5436 pool_ts
= READ_ONCE(pool
->watchdog_ts
);
5437 touched
= READ_ONCE(wq_watchdog_touched
);
5439 if (time_after(pool_ts
, touched
))
5444 if (pool
->cpu
>= 0) {
5445 unsigned long cpu_touched
=
5446 READ_ONCE(per_cpu(wq_watchdog_touched_cpu
,
5448 if (time_after(cpu_touched
, ts
))
5453 if (time_after(jiffies
, ts
+ thresh
)) {
5454 lockup_detected
= true;
5455 pr_emerg("BUG: workqueue lockup - pool");
5456 pr_cont_pool_info(pool
);
5457 pr_cont(" stuck for %us!\n",
5458 jiffies_to_msecs(jiffies
- pool_ts
) / 1000);
5464 if (lockup_detected
)
5465 show_workqueue_state();
5467 wq_watchdog_reset_touched();
5468 mod_timer(&wq_watchdog_timer
, jiffies
+ thresh
);
5471 void wq_watchdog_touch(int cpu
)
5474 per_cpu(wq_watchdog_touched_cpu
, cpu
) = jiffies
;
5476 wq_watchdog_touched
= jiffies
;
5479 static void wq_watchdog_set_thresh(unsigned long thresh
)
5481 wq_watchdog_thresh
= 0;
5482 del_timer_sync(&wq_watchdog_timer
);
5485 wq_watchdog_thresh
= thresh
;
5486 wq_watchdog_reset_touched();
5487 mod_timer(&wq_watchdog_timer
, jiffies
+ thresh
* HZ
);
5491 static int wq_watchdog_param_set_thresh(const char *val
,
5492 const struct kernel_param
*kp
)
5494 unsigned long thresh
;
5497 ret
= kstrtoul(val
, 0, &thresh
);
5502 wq_watchdog_set_thresh(thresh
);
5504 wq_watchdog_thresh
= thresh
;
5509 static const struct kernel_param_ops wq_watchdog_thresh_ops
= {
5510 .set
= wq_watchdog_param_set_thresh
,
5511 .get
= param_get_ulong
,
5514 module_param_cb(watchdog_thresh
, &wq_watchdog_thresh_ops
, &wq_watchdog_thresh
,
5517 static void wq_watchdog_init(void)
5519 timer_setup(&wq_watchdog_timer
, wq_watchdog_timer_fn
, TIMER_DEFERRABLE
);
5520 wq_watchdog_set_thresh(wq_watchdog_thresh
);
5523 #else /* CONFIG_WQ_WATCHDOG */
5525 static inline void wq_watchdog_init(void) { }
5527 #endif /* CONFIG_WQ_WATCHDOG */
5529 static void __init
wq_numa_init(void)
5534 if (num_possible_nodes() <= 1)
5537 if (wq_disable_numa
) {
5538 pr_info("workqueue: NUMA affinity support disabled\n");
5542 wq_update_unbound_numa_attrs_buf
= alloc_workqueue_attrs(GFP_KERNEL
);
5543 BUG_ON(!wq_update_unbound_numa_attrs_buf
);
5546 * We want masks of possible CPUs of each node which isn't readily
5547 * available. Build one from cpu_to_node() which should have been
5548 * fully initialized by now.
5550 tbl
= kzalloc(nr_node_ids
* sizeof(tbl
[0]), GFP_KERNEL
);
5554 BUG_ON(!zalloc_cpumask_var_node(&tbl
[node
], GFP_KERNEL
,
5555 node_online(node
) ? node
: NUMA_NO_NODE
));
5557 for_each_possible_cpu(cpu
) {
5558 node
= cpu_to_node(cpu
);
5559 if (WARN_ON(node
== NUMA_NO_NODE
)) {
5560 pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu
);
5561 /* happens iff arch is bonkers, let's just proceed */
5564 cpumask_set_cpu(cpu
, tbl
[node
]);
5567 wq_numa_possible_cpumask
= tbl
;
5568 wq_numa_enabled
= true;
5572 * workqueue_init_early - early init for workqueue subsystem
5574 * This is the first half of two-staged workqueue subsystem initialization
5575 * and invoked as soon as the bare basics - memory allocation, cpumasks and
5576 * idr are up. It sets up all the data structures and system workqueues
5577 * and allows early boot code to create workqueues and queue/cancel work
5578 * items. Actual work item execution starts only after kthreads can be
5579 * created and scheduled right before early initcalls.
5581 int __init
workqueue_init_early(void)
5583 int std_nice
[NR_STD_WORKER_POOLS
] = { 0, HIGHPRI_NICE_LEVEL
};
5586 WARN_ON(__alignof__(struct pool_workqueue
) < __alignof__(long long));
5588 BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask
, GFP_KERNEL
));
5589 cpumask_copy(wq_unbound_cpumask
, housekeeping_cpumask(HK_FLAG_DOMAIN
));
5591 pwq_cache
= KMEM_CACHE(pool_workqueue
, SLAB_PANIC
);
5593 /* initialize CPU pools */
5594 for_each_possible_cpu(cpu
) {
5595 struct worker_pool
*pool
;
5598 for_each_cpu_worker_pool(pool
, cpu
) {
5599 BUG_ON(init_worker_pool(pool
));
5601 cpumask_copy(pool
->attrs
->cpumask
, cpumask_of(cpu
));
5602 pool
->attrs
->nice
= std_nice
[i
++];
5603 pool
->node
= cpu_to_node(cpu
);
5606 mutex_lock(&wq_pool_mutex
);
5607 BUG_ON(worker_pool_assign_id(pool
));
5608 mutex_unlock(&wq_pool_mutex
);
5612 /* create default unbound and ordered wq attrs */
5613 for (i
= 0; i
< NR_STD_WORKER_POOLS
; i
++) {
5614 struct workqueue_attrs
*attrs
;
5616 BUG_ON(!(attrs
= alloc_workqueue_attrs(GFP_KERNEL
)));
5617 attrs
->nice
= std_nice
[i
];
5618 unbound_std_wq_attrs
[i
] = attrs
;
5621 * An ordered wq should have only one pwq as ordering is
5622 * guaranteed by max_active which is enforced by pwqs.
5623 * Turn off NUMA so that dfl_pwq is used for all nodes.
5625 BUG_ON(!(attrs
= alloc_workqueue_attrs(GFP_KERNEL
)));
5626 attrs
->nice
= std_nice
[i
];
5627 attrs
->no_numa
= true;
5628 ordered_wq_attrs
[i
] = attrs
;
5631 system_wq
= alloc_workqueue("events", 0, 0);
5632 system_highpri_wq
= alloc_workqueue("events_highpri", WQ_HIGHPRI
, 0);
5633 system_long_wq
= alloc_workqueue("events_long", 0, 0);
5634 system_unbound_wq
= alloc_workqueue("events_unbound", WQ_UNBOUND
,
5635 WQ_UNBOUND_MAX_ACTIVE
);
5636 system_freezable_wq
= alloc_workqueue("events_freezable",
5638 system_power_efficient_wq
= alloc_workqueue("events_power_efficient",
5639 WQ_POWER_EFFICIENT
, 0);
5640 system_freezable_power_efficient_wq
= alloc_workqueue("events_freezable_power_efficient",
5641 WQ_FREEZABLE
| WQ_POWER_EFFICIENT
,
5643 BUG_ON(!system_wq
|| !system_highpri_wq
|| !system_long_wq
||
5644 !system_unbound_wq
|| !system_freezable_wq
||
5645 !system_power_efficient_wq
||
5646 !system_freezable_power_efficient_wq
);
5652 * workqueue_init - bring workqueue subsystem fully online
5654 * This is the latter half of two-staged workqueue subsystem initialization
5655 * and invoked as soon as kthreads can be created and scheduled.
5656 * Workqueues have been created and work items queued on them, but there
5657 * are no kworkers executing the work items yet. Populate the worker pools
5658 * with the initial workers and enable future kworker creations.
5660 int __init
workqueue_init(void)
5662 struct workqueue_struct
*wq
;
5663 struct worker_pool
*pool
;
5667 * It'd be simpler to initialize NUMA in workqueue_init_early() but
5668 * CPU to node mapping may not be available that early on some
5669 * archs such as power and arm64. As per-cpu pools created
5670 * previously could be missing node hint and unbound pools NUMA
5671 * affinity, fix them up.
5673 * Also, while iterating workqueues, create rescuers if requested.
5677 mutex_lock(&wq_pool_mutex
);
5679 for_each_possible_cpu(cpu
) {
5680 for_each_cpu_worker_pool(pool
, cpu
) {
5681 pool
->node
= cpu_to_node(cpu
);
5685 list_for_each_entry(wq
, &workqueues
, list
) {
5686 wq_update_unbound_numa(wq
, smp_processor_id(), true);
5687 WARN(init_rescuer(wq
),
5688 "workqueue: failed to create early rescuer for %s",
5692 mutex_unlock(&wq_pool_mutex
);
5694 /* create the initial workers */
5695 for_each_online_cpu(cpu
) {
5696 for_each_cpu_worker_pool(pool
, cpu
) {
5697 pool
->flags
&= ~POOL_DISASSOCIATED
;
5698 BUG_ON(!create_worker(pool
));
5702 hash_for_each(unbound_pool_hash
, bkt
, pool
, hash_node
)
5703 BUG_ON(!create_worker(pool
));