2 * kernel/workqueue.c - generic async execution with shared worker pool
4 * Copyright (C) 2002 Ingo Molnar
6 * Derived from the taskqueue/keventd code by:
7 * David Woodhouse <dwmw2@infradead.org>
9 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
10 * Theodore Ts'o <tytso@mit.edu>
12 * Made to use alloc_percpu by Christoph Lameter.
14 * Copyright (C) 2010 SUSE Linux Products GmbH
15 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
17 * This is the generic async execution mechanism. Work items as are
18 * executed in process context. The worker pool is shared and
19 * automatically managed. There is one worker pool for each CPU and
20 * one extra for works which are better served by workers which are
21 * not bound to any specific CPU.
23 * Please read Documentation/workqueue.txt for details.
26 #include <linux/export.h>
27 #include <linux/kernel.h>
28 #include <linux/sched.h>
29 #include <linux/init.h>
30 #include <linux/signal.h>
31 #include <linux/completion.h>
32 #include <linux/workqueue.h>
33 #include <linux/slab.h>
34 #include <linux/cpu.h>
35 #include <linux/notifier.h>
36 #include <linux/kthread.h>
37 #include <linux/hardirq.h>
38 #include <linux/mempolicy.h>
39 #include <linux/freezer.h>
40 #include <linux/kallsyms.h>
41 #include <linux/debug_locks.h>
42 #include <linux/lockdep.h>
43 #include <linux/idr.h>
44 #include <linux/jhash.h>
45 #include <linux/hashtable.h>
46 #include <linux/rculist.h>
47 #include <linux/nodemask.h>
48 #include <linux/moduleparam.h>
49 #include <linux/uaccess.h>
51 #include "workqueue_internal.h"
57 * A bound pool is either associated or disassociated with its CPU.
58 * While associated (!DISASSOCIATED), all workers are bound to the
59 * CPU and none has %WORKER_UNBOUND set and concurrency management
62 * While DISASSOCIATED, the cpu may be offline and all workers have
63 * %WORKER_UNBOUND set and concurrency management disabled, and may
64 * be executing on any CPU. The pool behaves as an unbound one.
66 * Note that DISASSOCIATED should be flipped only while holding
67 * manager_mutex to avoid changing binding state while
68 * create_worker() is in progress.
70 POOL_MANAGE_WORKERS
= 1 << 0, /* need to manage workers */
71 POOL_DISASSOCIATED
= 1 << 2, /* cpu can't serve workers */
72 POOL_FREEZING
= 1 << 3, /* freeze in progress */
75 WORKER_STARTED
= 1 << 0, /* started */
76 WORKER_DIE
= 1 << 1, /* die die die */
77 WORKER_IDLE
= 1 << 2, /* is idle */
78 WORKER_PREP
= 1 << 3, /* preparing to run works */
79 WORKER_CPU_INTENSIVE
= 1 << 6, /* cpu intensive */
80 WORKER_UNBOUND
= 1 << 7, /* worker is unbound */
81 WORKER_REBOUND
= 1 << 8, /* worker was rebound */
83 WORKER_NOT_RUNNING
= WORKER_PREP
| WORKER_CPU_INTENSIVE
|
84 WORKER_UNBOUND
| WORKER_REBOUND
,
86 NR_STD_WORKER_POOLS
= 2, /* # standard pools per cpu */
88 UNBOUND_POOL_HASH_ORDER
= 6, /* hashed by pool->attrs */
89 BUSY_WORKER_HASH_ORDER
= 6, /* 64 pointers */
91 MAX_IDLE_WORKERS_RATIO
= 4, /* 1/4 of busy can be idle */
92 IDLE_WORKER_TIMEOUT
= 300 * HZ
, /* keep idle ones for 5 mins */
94 MAYDAY_INITIAL_TIMEOUT
= HZ
/ 100 >= 2 ? HZ
/ 100 : 2,
95 /* call for help after 10ms
97 MAYDAY_INTERVAL
= HZ
/ 10, /* and then every 100ms */
98 CREATE_COOLDOWN
= HZ
, /* time to breath after fail */
101 * Rescue workers are used only on emergencies and shared by
102 * all cpus. Give -20.
104 RESCUER_NICE_LEVEL
= -20,
105 HIGHPRI_NICE_LEVEL
= -20,
111 * Structure fields follow one of the following exclusion rules.
113 * I: Modifiable by initialization/destruction paths and read-only for
116 * P: Preemption protected. Disabling preemption is enough and should
117 * only be modified and accessed from the local cpu.
119 * L: pool->lock protected. Access with pool->lock held.
121 * X: During normal operation, modification requires pool->lock and should
122 * be done only from local cpu. Either disabling preemption on local
123 * cpu or grabbing pool->lock is enough for read access. If
124 * POOL_DISASSOCIATED is set, it's identical to L.
126 * MG: pool->manager_mutex and pool->lock protected. Writes require both
127 * locks. Reads can happen under either lock.
129 * PL: wq_pool_mutex protected.
131 * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
133 * WQ: wq->mutex protected.
135 * WR: wq->mutex protected for writes. Sched-RCU protected for reads.
137 * MD: wq_mayday_lock protected.
140 /* struct worker is defined in workqueue_internal.h */
143 spinlock_t lock
; /* the pool lock */
144 int cpu
; /* I: the associated cpu */
145 int node
; /* I: the associated node ID */
146 int id
; /* I: pool ID */
147 unsigned int flags
; /* X: flags */
149 struct list_head worklist
; /* L: list of pending works */
150 int nr_workers
; /* L: total number of workers */
152 /* nr_idle includes the ones off idle_list for rebinding */
153 int nr_idle
; /* L: currently idle ones */
155 struct list_head idle_list
; /* X: list of idle workers */
156 struct timer_list idle_timer
; /* L: worker idle timeout */
157 struct timer_list mayday_timer
; /* L: SOS timer for workers */
159 /* a workers is either on busy_hash or idle_list, or the manager */
160 DECLARE_HASHTABLE(busy_hash
, BUSY_WORKER_HASH_ORDER
);
161 /* L: hash of busy workers */
163 /* see manage_workers() for details on the two manager mutexes */
164 struct mutex manager_arb
; /* manager arbitration */
165 struct mutex manager_mutex
; /* manager exclusion */
166 struct idr worker_idr
; /* MG: worker IDs and iteration */
168 struct workqueue_attrs
*attrs
; /* I: worker attributes */
169 struct hlist_node hash_node
; /* PL: unbound_pool_hash node */
170 int refcnt
; /* PL: refcnt for unbound pools */
173 * The current concurrency level. As it's likely to be accessed
174 * from other CPUs during try_to_wake_up(), put it in a separate
177 atomic_t nr_running ____cacheline_aligned_in_smp
;
180 * Destruction of pool is sched-RCU protected to allow dereferences
181 * from get_work_pool().
184 } ____cacheline_aligned_in_smp
;
187 * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
188 * of work_struct->data are used for flags and the remaining high bits
189 * point to the pwq; thus, pwqs need to be aligned at two's power of the
190 * number of flag bits.
192 struct pool_workqueue
{
193 struct worker_pool
*pool
; /* I: the associated pool */
194 struct workqueue_struct
*wq
; /* I: the owning workqueue */
195 int work_color
; /* L: current color */
196 int flush_color
; /* L: flushing color */
197 int refcnt
; /* L: reference count */
198 int nr_in_flight
[WORK_NR_COLORS
];
199 /* L: nr of in_flight works */
200 int nr_active
; /* L: nr of active works */
201 int max_active
; /* L: max active works */
202 struct list_head delayed_works
; /* L: delayed works */
203 struct list_head pwqs_node
; /* WR: node on wq->pwqs */
204 struct list_head mayday_node
; /* MD: node on wq->maydays */
207 * Release of unbound pwq is punted to system_wq. See put_pwq()
208 * and pwq_unbound_release_workfn() for details. pool_workqueue
209 * itself is also sched-RCU protected so that the first pwq can be
210 * determined without grabbing wq->mutex.
212 struct work_struct unbound_release_work
;
214 } __aligned(1 << WORK_STRUCT_FLAG_BITS
);
217 * Structure used to wait for workqueue flush.
220 struct list_head list
; /* WQ: list of flushers */
221 int flush_color
; /* WQ: flush color waiting for */
222 struct completion done
; /* flush completion */
228 * The externally visible workqueue. It relays the issued work items to
229 * the appropriate worker_pool through its pool_workqueues.
231 struct workqueue_struct
{
232 struct list_head pwqs
; /* WR: all pwqs of this wq */
233 struct list_head list
; /* PL: list of all workqueues */
235 struct mutex mutex
; /* protects this wq */
236 int work_color
; /* WQ: current work color */
237 int flush_color
; /* WQ: current flush color */
238 atomic_t nr_pwqs_to_flush
; /* flush in progress */
239 struct wq_flusher
*first_flusher
; /* WQ: first flusher */
240 struct list_head flusher_queue
; /* WQ: flush waiters */
241 struct list_head flusher_overflow
; /* WQ: flush overflow list */
243 struct list_head maydays
; /* MD: pwqs requesting rescue */
244 struct worker
*rescuer
; /* I: rescue worker */
246 int nr_drainers
; /* WQ: drain in progress */
247 int saved_max_active
; /* WQ: saved pwq max_active */
249 struct workqueue_attrs
*unbound_attrs
; /* WQ: only for unbound wqs */
250 struct pool_workqueue
*dfl_pwq
; /* WQ: only for unbound wqs */
253 struct wq_device
*wq_dev
; /* I: for sysfs interface */
255 #ifdef CONFIG_LOCKDEP
256 struct lockdep_map lockdep_map
;
258 char name
[WQ_NAME_LEN
]; /* I: workqueue name */
260 /* hot fields used during command issue, aligned to cacheline */
261 unsigned int flags ____cacheline_aligned
; /* WQ: WQ_* flags */
262 struct pool_workqueue __percpu
*cpu_pwqs
; /* I: per-cpu pwqs */
263 struct pool_workqueue __rcu
*numa_pwq_tbl
[]; /* FR: unbound pwqs indexed by node */
266 static struct kmem_cache
*pwq_cache
;
268 static int wq_numa_tbl_len
; /* highest possible NUMA node id + 1 */
269 static cpumask_var_t
*wq_numa_possible_cpumask
;
270 /* possible CPUs of each node */
272 static bool wq_disable_numa
;
273 module_param_named(disable_numa
, wq_disable_numa
, bool, 0444);
275 static bool wq_numa_enabled
; /* unbound NUMA affinity enabled */
277 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
278 static struct workqueue_attrs
*wq_update_unbound_numa_attrs_buf
;
280 static DEFINE_MUTEX(wq_pool_mutex
); /* protects pools and workqueues list */
281 static DEFINE_SPINLOCK(wq_mayday_lock
); /* protects wq->maydays list */
283 static LIST_HEAD(workqueues
); /* PL: list of all workqueues */
284 static bool workqueue_freezing
; /* PL: have wqs started freezing? */
286 /* the per-cpu worker pools */
287 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool
[NR_STD_WORKER_POOLS
],
290 static DEFINE_IDR(worker_pool_idr
); /* PR: idr of all pools */
292 /* PL: hash of all unbound pools keyed by pool->attrs */
293 static DEFINE_HASHTABLE(unbound_pool_hash
, UNBOUND_POOL_HASH_ORDER
);
295 /* I: attributes used when instantiating standard unbound pools on demand */
296 static struct workqueue_attrs
*unbound_std_wq_attrs
[NR_STD_WORKER_POOLS
];
298 /* I: attributes used when instantiating ordered pools on demand */
299 static struct workqueue_attrs
*ordered_wq_attrs
[NR_STD_WORKER_POOLS
];
301 struct workqueue_struct
*system_wq __read_mostly
;
302 EXPORT_SYMBOL(system_wq
);
303 struct workqueue_struct
*system_highpri_wq __read_mostly
;
304 EXPORT_SYMBOL_GPL(system_highpri_wq
);
305 struct workqueue_struct
*system_long_wq __read_mostly
;
306 EXPORT_SYMBOL_GPL(system_long_wq
);
307 struct workqueue_struct
*system_unbound_wq __read_mostly
;
308 EXPORT_SYMBOL_GPL(system_unbound_wq
);
309 struct workqueue_struct
*system_freezable_wq __read_mostly
;
310 EXPORT_SYMBOL_GPL(system_freezable_wq
);
312 static int worker_thread(void *__worker
);
313 static void copy_workqueue_attrs(struct workqueue_attrs
*to
,
314 const struct workqueue_attrs
*from
);
316 #define CREATE_TRACE_POINTS
317 #include <trace/events/workqueue.h>
319 #define assert_rcu_or_pool_mutex() \
320 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
321 lockdep_is_held(&wq_pool_mutex), \
322 "sched RCU or wq_pool_mutex should be held")
324 #define assert_rcu_or_wq_mutex(wq) \
325 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
326 lockdep_is_held(&wq->mutex), \
327 "sched RCU or wq->mutex should be held")
329 #ifdef CONFIG_LOCKDEP
330 #define assert_manager_or_pool_lock(pool) \
331 WARN_ONCE(debug_locks && \
332 !lockdep_is_held(&(pool)->manager_mutex) && \
333 !lockdep_is_held(&(pool)->lock), \
334 "pool->manager_mutex or ->lock should be held")
336 #define assert_manager_or_pool_lock(pool) do { } while (0)
339 #define for_each_cpu_worker_pool(pool, cpu) \
340 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
341 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
345 * for_each_pool - iterate through all worker_pools in the system
346 * @pool: iteration cursor
347 * @pi: integer used for iteration
349 * This must be called either with wq_pool_mutex held or sched RCU read
350 * locked. If the pool needs to be used beyond the locking in effect, the
351 * caller is responsible for guaranteeing that the pool stays online.
353 * The if/else clause exists only for the lockdep assertion and can be
356 #define for_each_pool(pool, pi) \
357 idr_for_each_entry(&worker_pool_idr, pool, pi) \
358 if (({ assert_rcu_or_pool_mutex(); false; })) { } \
362 * for_each_pool_worker - iterate through all workers of a worker_pool
363 * @worker: iteration cursor
364 * @wi: integer used for iteration
365 * @pool: worker_pool to iterate workers of
367 * This must be called with either @pool->manager_mutex or ->lock held.
369 * The if/else clause exists only for the lockdep assertion and can be
372 #define for_each_pool_worker(worker, wi, pool) \
373 idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \
374 if (({ assert_manager_or_pool_lock((pool)); false; })) { } \
378 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
379 * @pwq: iteration cursor
380 * @wq: the target workqueue
382 * This must be called either with wq->mutex held or sched RCU read locked.
383 * If the pwq needs to be used beyond the locking in effect, the caller is
384 * responsible for guaranteeing that the pwq stays online.
386 * The if/else clause exists only for the lockdep assertion and can be
389 #define for_each_pwq(pwq, wq) \
390 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
391 if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
394 #ifdef CONFIG_DEBUG_OBJECTS_WORK
396 static struct debug_obj_descr work_debug_descr
;
398 static void *work_debug_hint(void *addr
)
400 return ((struct work_struct
*) addr
)->func
;
404 * fixup_init is called when:
405 * - an active object is initialized
407 static int work_fixup_init(void *addr
, enum debug_obj_state state
)
409 struct work_struct
*work
= addr
;
412 case ODEBUG_STATE_ACTIVE
:
413 cancel_work_sync(work
);
414 debug_object_init(work
, &work_debug_descr
);
422 * fixup_activate is called when:
423 * - an active object is activated
424 * - an unknown object is activated (might be a statically initialized object)
426 static int work_fixup_activate(void *addr
, enum debug_obj_state state
)
428 struct work_struct
*work
= addr
;
432 case ODEBUG_STATE_NOTAVAILABLE
:
434 * This is not really a fixup. The work struct was
435 * statically initialized. We just make sure that it
436 * is tracked in the object tracker.
438 if (test_bit(WORK_STRUCT_STATIC_BIT
, work_data_bits(work
))) {
439 debug_object_init(work
, &work_debug_descr
);
440 debug_object_activate(work
, &work_debug_descr
);
446 case ODEBUG_STATE_ACTIVE
:
455 * fixup_free is called when:
456 * - an active object is freed
458 static int work_fixup_free(void *addr
, enum debug_obj_state state
)
460 struct work_struct
*work
= addr
;
463 case ODEBUG_STATE_ACTIVE
:
464 cancel_work_sync(work
);
465 debug_object_free(work
, &work_debug_descr
);
472 static struct debug_obj_descr work_debug_descr
= {
473 .name
= "work_struct",
474 .debug_hint
= work_debug_hint
,
475 .fixup_init
= work_fixup_init
,
476 .fixup_activate
= work_fixup_activate
,
477 .fixup_free
= work_fixup_free
,
480 static inline void debug_work_activate(struct work_struct
*work
)
482 debug_object_activate(work
, &work_debug_descr
);
485 static inline void debug_work_deactivate(struct work_struct
*work
)
487 debug_object_deactivate(work
, &work_debug_descr
);
490 void __init_work(struct work_struct
*work
, int onstack
)
493 debug_object_init_on_stack(work
, &work_debug_descr
);
495 debug_object_init(work
, &work_debug_descr
);
497 EXPORT_SYMBOL_GPL(__init_work
);
499 void destroy_work_on_stack(struct work_struct
*work
)
501 debug_object_free(work
, &work_debug_descr
);
503 EXPORT_SYMBOL_GPL(destroy_work_on_stack
);
506 static inline void debug_work_activate(struct work_struct
*work
) { }
507 static inline void debug_work_deactivate(struct work_struct
*work
) { }
510 /* allocate ID and assign it to @pool */
511 static int worker_pool_assign_id(struct worker_pool
*pool
)
515 lockdep_assert_held(&wq_pool_mutex
);
517 ret
= idr_alloc(&worker_pool_idr
, pool
, 0, 0, GFP_KERNEL
);
526 * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
527 * @wq: the target workqueue
530 * This must be called either with pwq_lock held or sched RCU read locked.
531 * If the pwq needs to be used beyond the locking in effect, the caller is
532 * responsible for guaranteeing that the pwq stays online.
534 static struct pool_workqueue
*unbound_pwq_by_node(struct workqueue_struct
*wq
,
537 assert_rcu_or_wq_mutex(wq
);
538 return rcu_dereference_raw(wq
->numa_pwq_tbl
[node
]);
541 static unsigned int work_color_to_flags(int color
)
543 return color
<< WORK_STRUCT_COLOR_SHIFT
;
546 static int get_work_color(struct work_struct
*work
)
548 return (*work_data_bits(work
) >> WORK_STRUCT_COLOR_SHIFT
) &
549 ((1 << WORK_STRUCT_COLOR_BITS
) - 1);
552 static int work_next_color(int color
)
554 return (color
+ 1) % WORK_NR_COLORS
;
558 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
559 * contain the pointer to the queued pwq. Once execution starts, the flag
560 * is cleared and the high bits contain OFFQ flags and pool ID.
562 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
563 * and clear_work_data() can be used to set the pwq, pool or clear
564 * work->data. These functions should only be called while the work is
565 * owned - ie. while the PENDING bit is set.
567 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
568 * corresponding to a work. Pool is available once the work has been
569 * queued anywhere after initialization until it is sync canceled. pwq is
570 * available only while the work item is queued.
572 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
573 * canceled. While being canceled, a work item may have its PENDING set
574 * but stay off timer and worklist for arbitrarily long and nobody should
575 * try to steal the PENDING bit.
577 static inline void set_work_data(struct work_struct
*work
, unsigned long data
,
580 WARN_ON_ONCE(!work_pending(work
));
581 atomic_long_set(&work
->data
, data
| flags
| work_static(work
));
584 static void set_work_pwq(struct work_struct
*work
, struct pool_workqueue
*pwq
,
585 unsigned long extra_flags
)
587 set_work_data(work
, (unsigned long)pwq
,
588 WORK_STRUCT_PENDING
| WORK_STRUCT_PWQ
| extra_flags
);
591 static void set_work_pool_and_keep_pending(struct work_struct
*work
,
594 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
,
595 WORK_STRUCT_PENDING
);
598 static void set_work_pool_and_clear_pending(struct work_struct
*work
,
602 * The following wmb is paired with the implied mb in
603 * test_and_set_bit(PENDING) and ensures all updates to @work made
604 * here are visible to and precede any updates by the next PENDING
608 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
, 0);
610 * The following mb guarantees that previous clear of a PENDING bit
611 * will not be reordered with any speculative LOADS or STORES from
612 * work->current_func, which is executed afterwards. This possible
613 * reordering can lead to a missed execution on attempt to qeueue
614 * the same @work. E.g. consider this case:
617 * ---------------------------- --------------------------------
619 * 1 STORE event_indicated
620 * 2 queue_work_on() {
621 * 3 test_and_set_bit(PENDING)
622 * 4 } set_..._and_clear_pending() {
623 * 5 set_work_data() # clear bit
625 * 7 work->current_func() {
626 * 8 LOAD event_indicated
629 * Without an explicit full barrier speculative LOAD on line 8 can
630 * be executed before CPU#0 does STORE on line 1. If that happens,
631 * CPU#0 observes the PENDING bit is still set and new execution of
632 * a @work is not queued in a hope, that CPU#1 will eventually
633 * finish the queued @work. Meanwhile CPU#1 does not see
634 * event_indicated is set, because speculative LOAD was executed
635 * before actual STORE.
640 static void clear_work_data(struct work_struct
*work
)
642 smp_wmb(); /* see set_work_pool_and_clear_pending() */
643 set_work_data(work
, WORK_STRUCT_NO_POOL
, 0);
646 static struct pool_workqueue
*get_work_pwq(struct work_struct
*work
)
648 unsigned long data
= atomic_long_read(&work
->data
);
650 if (data
& WORK_STRUCT_PWQ
)
651 return (void *)(data
& WORK_STRUCT_WQ_DATA_MASK
);
657 * get_work_pool - return the worker_pool a given work was associated with
658 * @work: the work item of interest
660 * Return the worker_pool @work was last associated with. %NULL if none.
662 * Pools are created and destroyed under wq_pool_mutex, and allows read
663 * access under sched-RCU read lock. As such, this function should be
664 * called under wq_pool_mutex or with preemption disabled.
666 * All fields of the returned pool are accessible as long as the above
667 * mentioned locking is in effect. If the returned pool needs to be used
668 * beyond the critical section, the caller is responsible for ensuring the
669 * returned pool is and stays online.
671 static struct worker_pool
*get_work_pool(struct work_struct
*work
)
673 unsigned long data
= atomic_long_read(&work
->data
);
676 assert_rcu_or_pool_mutex();
678 if (data
& WORK_STRUCT_PWQ
)
679 return ((struct pool_workqueue
*)
680 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
;
682 pool_id
= data
>> WORK_OFFQ_POOL_SHIFT
;
683 if (pool_id
== WORK_OFFQ_POOL_NONE
)
686 return idr_find(&worker_pool_idr
, pool_id
);
690 * get_work_pool_id - return the worker pool ID a given work is associated with
691 * @work: the work item of interest
693 * Return the worker_pool ID @work was last associated with.
694 * %WORK_OFFQ_POOL_NONE if none.
696 static int get_work_pool_id(struct work_struct
*work
)
698 unsigned long data
= atomic_long_read(&work
->data
);
700 if (data
& WORK_STRUCT_PWQ
)
701 return ((struct pool_workqueue
*)
702 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
->id
;
704 return data
>> WORK_OFFQ_POOL_SHIFT
;
707 static void mark_work_canceling(struct work_struct
*work
)
709 unsigned long pool_id
= get_work_pool_id(work
);
711 pool_id
<<= WORK_OFFQ_POOL_SHIFT
;
712 set_work_data(work
, pool_id
| WORK_OFFQ_CANCELING
, WORK_STRUCT_PENDING
);
715 static bool work_is_canceling(struct work_struct
*work
)
717 unsigned long data
= atomic_long_read(&work
->data
);
719 return !(data
& WORK_STRUCT_PWQ
) && (data
& WORK_OFFQ_CANCELING
);
723 * Policy functions. These define the policies on how the global worker
724 * pools are managed. Unless noted otherwise, these functions assume that
725 * they're being called with pool->lock held.
728 static bool __need_more_worker(struct worker_pool
*pool
)
730 return !atomic_read(&pool
->nr_running
);
734 * Need to wake up a worker? Called from anything but currently
737 * Note that, because unbound workers never contribute to nr_running, this
738 * function will always return %true for unbound pools as long as the
739 * worklist isn't empty.
741 static bool need_more_worker(struct worker_pool
*pool
)
743 return !list_empty(&pool
->worklist
) && __need_more_worker(pool
);
746 /* Can I start working? Called from busy but !running workers. */
747 static bool may_start_working(struct worker_pool
*pool
)
749 return pool
->nr_idle
;
752 /* Do I need to keep working? Called from currently running workers. */
753 static bool keep_working(struct worker_pool
*pool
)
755 return !list_empty(&pool
->worklist
) &&
756 atomic_read(&pool
->nr_running
) <= 1;
759 /* Do we need a new worker? Called from manager. */
760 static bool need_to_create_worker(struct worker_pool
*pool
)
762 return need_more_worker(pool
) && !may_start_working(pool
);
765 /* Do I need to be the manager? */
766 static bool need_to_manage_workers(struct worker_pool
*pool
)
768 return need_to_create_worker(pool
) ||
769 (pool
->flags
& POOL_MANAGE_WORKERS
);
772 /* Do we have too many workers and should some go away? */
773 static bool too_many_workers(struct worker_pool
*pool
)
775 bool managing
= mutex_is_locked(&pool
->manager_arb
);
776 int nr_idle
= pool
->nr_idle
+ managing
; /* manager is considered idle */
777 int nr_busy
= pool
->nr_workers
- nr_idle
;
780 * nr_idle and idle_list may disagree if idle rebinding is in
781 * progress. Never return %true if idle_list is empty.
783 if (list_empty(&pool
->idle_list
))
786 return nr_idle
> 2 && (nr_idle
- 2) * MAX_IDLE_WORKERS_RATIO
>= nr_busy
;
793 /* Return the first worker. Safe with preemption disabled */
794 static struct worker
*first_worker(struct worker_pool
*pool
)
796 if (unlikely(list_empty(&pool
->idle_list
)))
799 return list_first_entry(&pool
->idle_list
, struct worker
, entry
);
803 * wake_up_worker - wake up an idle worker
804 * @pool: worker pool to wake worker from
806 * Wake up the first idle worker of @pool.
809 * spin_lock_irq(pool->lock).
811 static void wake_up_worker(struct worker_pool
*pool
)
813 struct worker
*worker
= first_worker(pool
);
816 wake_up_process(worker
->task
);
820 * wq_worker_waking_up - a worker is waking up
821 * @task: task waking up
822 * @cpu: CPU @task is waking up to
824 * This function is called during try_to_wake_up() when a worker is
828 * spin_lock_irq(rq->lock)
830 void wq_worker_waking_up(struct task_struct
*task
, int cpu
)
832 struct worker
*worker
= kthread_data(task
);
834 if (!(worker
->flags
& WORKER_NOT_RUNNING
)) {
835 WARN_ON_ONCE(worker
->pool
->cpu
!= cpu
);
836 atomic_inc(&worker
->pool
->nr_running
);
841 * wq_worker_sleeping - a worker is going to sleep
842 * @task: task going to sleep
843 * @cpu: CPU in question, must be the current CPU number
845 * This function is called during schedule() when a busy worker is
846 * going to sleep. Worker on the same cpu can be woken up by
847 * returning pointer to its task.
850 * spin_lock_irq(rq->lock)
853 * Worker task on @cpu to wake up, %NULL if none.
855 struct task_struct
*wq_worker_sleeping(struct task_struct
*task
, int cpu
)
857 struct worker
*worker
= kthread_data(task
), *to_wakeup
= NULL
;
858 struct worker_pool
*pool
;
861 * Rescuers, which may not have all the fields set up like normal
862 * workers, also reach here, let's not access anything before
863 * checking NOT_RUNNING.
865 if (worker
->flags
& WORKER_NOT_RUNNING
)
870 /* this can only happen on the local cpu */
871 if (WARN_ON_ONCE(cpu
!= raw_smp_processor_id()))
875 * The counterpart of the following dec_and_test, implied mb,
876 * worklist not empty test sequence is in insert_work().
877 * Please read comment there.
879 * NOT_RUNNING is clear. This means that we're bound to and
880 * running on the local cpu w/ rq lock held and preemption
881 * disabled, which in turn means that none else could be
882 * manipulating idle_list, so dereferencing idle_list without pool
885 if (atomic_dec_and_test(&pool
->nr_running
) &&
886 !list_empty(&pool
->worklist
))
887 to_wakeup
= first_worker(pool
);
888 return to_wakeup
? to_wakeup
->task
: NULL
;
892 * worker_set_flags - set worker flags and adjust nr_running accordingly
894 * @flags: flags to set
895 * @wakeup: wakeup an idle worker if necessary
897 * Set @flags in @worker->flags and adjust nr_running accordingly. If
898 * nr_running becomes zero and @wakeup is %true, an idle worker is
902 * spin_lock_irq(pool->lock)
904 static inline void worker_set_flags(struct worker
*worker
, unsigned int flags
,
907 struct worker_pool
*pool
= worker
->pool
;
909 WARN_ON_ONCE(worker
->task
!= current
);
912 * If transitioning into NOT_RUNNING, adjust nr_running and
913 * wake up an idle worker as necessary if requested by
916 if ((flags
& WORKER_NOT_RUNNING
) &&
917 !(worker
->flags
& WORKER_NOT_RUNNING
)) {
919 if (atomic_dec_and_test(&pool
->nr_running
) &&
920 !list_empty(&pool
->worklist
))
921 wake_up_worker(pool
);
923 atomic_dec(&pool
->nr_running
);
926 worker
->flags
|= flags
;
930 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
932 * @flags: flags to clear
934 * Clear @flags in @worker->flags and adjust nr_running accordingly.
937 * spin_lock_irq(pool->lock)
939 static inline void worker_clr_flags(struct worker
*worker
, unsigned int flags
)
941 struct worker_pool
*pool
= worker
->pool
;
942 unsigned int oflags
= worker
->flags
;
944 WARN_ON_ONCE(worker
->task
!= current
);
946 worker
->flags
&= ~flags
;
949 * If transitioning out of NOT_RUNNING, increment nr_running. Note
950 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
951 * of multiple flags, not a single flag.
953 if ((flags
& WORKER_NOT_RUNNING
) && (oflags
& WORKER_NOT_RUNNING
))
954 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
955 atomic_inc(&pool
->nr_running
);
959 * find_worker_executing_work - find worker which is executing a work
960 * @pool: pool of interest
961 * @work: work to find worker for
963 * Find a worker which is executing @work on @pool by searching
964 * @pool->busy_hash which is keyed by the address of @work. For a worker
965 * to match, its current execution should match the address of @work and
966 * its work function. This is to avoid unwanted dependency between
967 * unrelated work executions through a work item being recycled while still
970 * This is a bit tricky. A work item may be freed once its execution
971 * starts and nothing prevents the freed area from being recycled for
972 * another work item. If the same work item address ends up being reused
973 * before the original execution finishes, workqueue will identify the
974 * recycled work item as currently executing and make it wait until the
975 * current execution finishes, introducing an unwanted dependency.
977 * This function checks the work item address and work function to avoid
978 * false positives. Note that this isn't complete as one may construct a
979 * work function which can introduce dependency onto itself through a
980 * recycled work item. Well, if somebody wants to shoot oneself in the
981 * foot that badly, there's only so much we can do, and if such deadlock
982 * actually occurs, it should be easy to locate the culprit work function.
985 * spin_lock_irq(pool->lock).
988 * Pointer to worker which is executing @work if found, NULL
991 static struct worker
*find_worker_executing_work(struct worker_pool
*pool
,
992 struct work_struct
*work
)
994 struct worker
*worker
;
996 hash_for_each_possible(pool
->busy_hash
, worker
, hentry
,
998 if (worker
->current_work
== work
&&
999 worker
->current_func
== work
->func
)
1006 * move_linked_works - move linked works to a list
1007 * @work: start of series of works to be scheduled
1008 * @head: target list to append @work to
1009 * @nextp: out paramter for nested worklist walking
1011 * Schedule linked works starting from @work to @head. Work series to
1012 * be scheduled starts at @work and includes any consecutive work with
1013 * WORK_STRUCT_LINKED set in its predecessor.
1015 * If @nextp is not NULL, it's updated to point to the next work of
1016 * the last scheduled work. This allows move_linked_works() to be
1017 * nested inside outer list_for_each_entry_safe().
1020 * spin_lock_irq(pool->lock).
1022 static void move_linked_works(struct work_struct
*work
, struct list_head
*head
,
1023 struct work_struct
**nextp
)
1025 struct work_struct
*n
;
1028 * Linked worklist will always end before the end of the list,
1029 * use NULL for list head.
1031 list_for_each_entry_safe_from(work
, n
, NULL
, entry
) {
1032 list_move_tail(&work
->entry
, head
);
1033 if (!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))
1038 * If we're already inside safe list traversal and have moved
1039 * multiple works to the scheduled queue, the next position
1040 * needs to be updated.
1047 * get_pwq - get an extra reference on the specified pool_workqueue
1048 * @pwq: pool_workqueue to get
1050 * Obtain an extra reference on @pwq. The caller should guarantee that
1051 * @pwq has positive refcnt and be holding the matching pool->lock.
1053 static void get_pwq(struct pool_workqueue
*pwq
)
1055 lockdep_assert_held(&pwq
->pool
->lock
);
1056 WARN_ON_ONCE(pwq
->refcnt
<= 0);
1061 * put_pwq - put a pool_workqueue reference
1062 * @pwq: pool_workqueue to put
1064 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1065 * destruction. The caller should be holding the matching pool->lock.
1067 static void put_pwq(struct pool_workqueue
*pwq
)
1069 lockdep_assert_held(&pwq
->pool
->lock
);
1070 if (likely(--pwq
->refcnt
))
1072 if (WARN_ON_ONCE(!(pwq
->wq
->flags
& WQ_UNBOUND
)))
1075 * @pwq can't be released under pool->lock, bounce to
1076 * pwq_unbound_release_workfn(). This never recurses on the same
1077 * pool->lock as this path is taken only for unbound workqueues and
1078 * the release work item is scheduled on a per-cpu workqueue. To
1079 * avoid lockdep warning, unbound pool->locks are given lockdep
1080 * subclass of 1 in get_unbound_pool().
1082 schedule_work(&pwq
->unbound_release_work
);
1086 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1087 * @pwq: pool_workqueue to put (can be %NULL)
1089 * put_pwq() with locking. This function also allows %NULL @pwq.
1091 static void put_pwq_unlocked(struct pool_workqueue
*pwq
)
1095 * As both pwqs and pools are sched-RCU protected, the
1096 * following lock operations are safe.
1098 spin_lock_irq(&pwq
->pool
->lock
);
1100 spin_unlock_irq(&pwq
->pool
->lock
);
1104 static void pwq_activate_delayed_work(struct work_struct
*work
)
1106 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1108 trace_workqueue_activate_work(work
);
1109 move_linked_works(work
, &pwq
->pool
->worklist
, NULL
);
1110 __clear_bit(WORK_STRUCT_DELAYED_BIT
, work_data_bits(work
));
1114 static void pwq_activate_first_delayed(struct pool_workqueue
*pwq
)
1116 struct work_struct
*work
= list_first_entry(&pwq
->delayed_works
,
1117 struct work_struct
, entry
);
1119 pwq_activate_delayed_work(work
);
1123 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1124 * @pwq: pwq of interest
1125 * @color: color of work which left the queue
1127 * A work either has completed or is removed from pending queue,
1128 * decrement nr_in_flight of its pwq and handle workqueue flushing.
1131 * spin_lock_irq(pool->lock).
1133 static void pwq_dec_nr_in_flight(struct pool_workqueue
*pwq
, int color
)
1135 /* uncolored work items don't participate in flushing or nr_active */
1136 if (color
== WORK_NO_COLOR
)
1139 pwq
->nr_in_flight
[color
]--;
1142 if (!list_empty(&pwq
->delayed_works
)) {
1143 /* one down, submit a delayed one */
1144 if (pwq
->nr_active
< pwq
->max_active
)
1145 pwq_activate_first_delayed(pwq
);
1148 /* is flush in progress and are we at the flushing tip? */
1149 if (likely(pwq
->flush_color
!= color
))
1152 /* are there still in-flight works? */
1153 if (pwq
->nr_in_flight
[color
])
1156 /* this pwq is done, clear flush_color */
1157 pwq
->flush_color
= -1;
1160 * If this was the last pwq, wake up the first flusher. It
1161 * will handle the rest.
1163 if (atomic_dec_and_test(&pwq
->wq
->nr_pwqs_to_flush
))
1164 complete(&pwq
->wq
->first_flusher
->done
);
1170 * try_to_grab_pending - steal work item from worklist and disable irq
1171 * @work: work item to steal
1172 * @is_dwork: @work is a delayed_work
1173 * @flags: place to store irq state
1175 * Try to grab PENDING bit of @work. This function can handle @work in any
1176 * stable state - idle, on timer or on worklist. Return values are
1178 * 1 if @work was pending and we successfully stole PENDING
1179 * 0 if @work was idle and we claimed PENDING
1180 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1181 * -ENOENT if someone else is canceling @work, this state may persist
1182 * for arbitrarily long
1184 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1185 * interrupted while holding PENDING and @work off queue, irq must be
1186 * disabled on entry. This, combined with delayed_work->timer being
1187 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1189 * On successful return, >= 0, irq is disabled and the caller is
1190 * responsible for releasing it using local_irq_restore(*@flags).
1192 * This function is safe to call from any context including IRQ handler.
1194 static int try_to_grab_pending(struct work_struct
*work
, bool is_dwork
,
1195 unsigned long *flags
)
1197 struct worker_pool
*pool
;
1198 struct pool_workqueue
*pwq
;
1200 local_irq_save(*flags
);
1202 /* try to steal the timer if it exists */
1204 struct delayed_work
*dwork
= to_delayed_work(work
);
1207 * dwork->timer is irqsafe. If del_timer() fails, it's
1208 * guaranteed that the timer is not queued anywhere and not
1209 * running on the local CPU.
1211 if (likely(del_timer(&dwork
->timer
)))
1215 /* try to claim PENDING the normal way */
1216 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
)))
1220 * The queueing is in progress, or it is already queued. Try to
1221 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1223 pool
= get_work_pool(work
);
1227 spin_lock(&pool
->lock
);
1229 * work->data is guaranteed to point to pwq only while the work
1230 * item is queued on pwq->wq, and both updating work->data to point
1231 * to pwq on queueing and to pool on dequeueing are done under
1232 * pwq->pool->lock. This in turn guarantees that, if work->data
1233 * points to pwq which is associated with a locked pool, the work
1234 * item is currently queued on that pool.
1236 pwq
= get_work_pwq(work
);
1237 if (pwq
&& pwq
->pool
== pool
) {
1238 debug_work_deactivate(work
);
1241 * A delayed work item cannot be grabbed directly because
1242 * it might have linked NO_COLOR work items which, if left
1243 * on the delayed_list, will confuse pwq->nr_active
1244 * management later on and cause stall. Make sure the work
1245 * item is activated before grabbing.
1247 if (*work_data_bits(work
) & WORK_STRUCT_DELAYED
)
1248 pwq_activate_delayed_work(work
);
1250 list_del_init(&work
->entry
);
1251 pwq_dec_nr_in_flight(get_work_pwq(work
), get_work_color(work
));
1253 /* work->data points to pwq iff queued, point to pool */
1254 set_work_pool_and_keep_pending(work
, pool
->id
);
1256 spin_unlock(&pool
->lock
);
1259 spin_unlock(&pool
->lock
);
1261 local_irq_restore(*flags
);
1262 if (work_is_canceling(work
))
1269 * insert_work - insert a work into a pool
1270 * @pwq: pwq @work belongs to
1271 * @work: work to insert
1272 * @head: insertion point
1273 * @extra_flags: extra WORK_STRUCT_* flags to set
1275 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1276 * work_struct flags.
1279 * spin_lock_irq(pool->lock).
1281 static void insert_work(struct pool_workqueue
*pwq
, struct work_struct
*work
,
1282 struct list_head
*head
, unsigned int extra_flags
)
1284 struct worker_pool
*pool
= pwq
->pool
;
1286 /* we own @work, set data and link */
1287 set_work_pwq(work
, pwq
, extra_flags
);
1288 list_add_tail(&work
->entry
, head
);
1292 * Ensure either wq_worker_sleeping() sees the above
1293 * list_add_tail() or we see zero nr_running to avoid workers lying
1294 * around lazily while there are works to be processed.
1298 if (__need_more_worker(pool
))
1299 wake_up_worker(pool
);
1303 * Test whether @work is being queued from another work executing on the
1306 static bool is_chained_work(struct workqueue_struct
*wq
)
1308 struct worker
*worker
;
1310 worker
= current_wq_worker();
1312 * Return %true iff I'm a worker execuing a work item on @wq. If
1313 * I'm @worker, it's safe to dereference it without locking.
1315 return worker
&& worker
->current_pwq
->wq
== wq
;
1318 static void __queue_work(int cpu
, struct workqueue_struct
*wq
,
1319 struct work_struct
*work
)
1321 struct pool_workqueue
*pwq
;
1322 struct worker_pool
*last_pool
;
1323 struct list_head
*worklist
;
1324 unsigned int work_flags
;
1325 unsigned int req_cpu
= cpu
;
1328 * While a work item is PENDING && off queue, a task trying to
1329 * steal the PENDING will busy-loop waiting for it to either get
1330 * queued or lose PENDING. Grabbing PENDING and queueing should
1331 * happen with IRQ disabled.
1333 WARN_ON_ONCE(!irqs_disabled());
1335 debug_work_activate(work
);
1337 /* if dying, only works from the same workqueue are allowed */
1338 if (unlikely(wq
->flags
& __WQ_DRAINING
) &&
1339 WARN_ON_ONCE(!is_chained_work(wq
)))
1342 if (req_cpu
== WORK_CPU_UNBOUND
)
1343 cpu
= raw_smp_processor_id();
1345 /* pwq which will be used unless @work is executing elsewhere */
1346 if (!(wq
->flags
& WQ_UNBOUND
))
1347 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
1349 pwq
= unbound_pwq_by_node(wq
, cpu_to_node(cpu
));
1352 * If @work was previously on a different pool, it might still be
1353 * running there, in which case the work needs to be queued on that
1354 * pool to guarantee non-reentrancy.
1356 last_pool
= get_work_pool(work
);
1357 if (last_pool
&& last_pool
!= pwq
->pool
) {
1358 struct worker
*worker
;
1360 spin_lock(&last_pool
->lock
);
1362 worker
= find_worker_executing_work(last_pool
, work
);
1364 if (worker
&& worker
->current_pwq
->wq
== wq
) {
1365 pwq
= worker
->current_pwq
;
1367 /* meh... not running there, queue here */
1368 spin_unlock(&last_pool
->lock
);
1369 spin_lock(&pwq
->pool
->lock
);
1372 spin_lock(&pwq
->pool
->lock
);
1376 * pwq is determined and locked. For unbound pools, we could have
1377 * raced with pwq release and it could already be dead. If its
1378 * refcnt is zero, repeat pwq selection. Note that pwqs never die
1379 * without another pwq replacing it in the numa_pwq_tbl or while
1380 * work items are executing on it, so the retrying is guaranteed to
1381 * make forward-progress.
1383 if (unlikely(!pwq
->refcnt
)) {
1384 if (wq
->flags
& WQ_UNBOUND
) {
1385 spin_unlock(&pwq
->pool
->lock
);
1390 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1394 /* pwq determined, queue */
1395 trace_workqueue_queue_work(req_cpu
, pwq
, work
);
1397 if (WARN_ON(!list_empty(&work
->entry
))) {
1398 spin_unlock(&pwq
->pool
->lock
);
1402 pwq
->nr_in_flight
[pwq
->work_color
]++;
1403 work_flags
= work_color_to_flags(pwq
->work_color
);
1405 if (likely(pwq
->nr_active
< pwq
->max_active
)) {
1406 trace_workqueue_activate_work(work
);
1408 worklist
= &pwq
->pool
->worklist
;
1410 work_flags
|= WORK_STRUCT_DELAYED
;
1411 worklist
= &pwq
->delayed_works
;
1414 insert_work(pwq
, work
, worklist
, work_flags
);
1416 spin_unlock(&pwq
->pool
->lock
);
1420 * queue_work_on - queue work on specific cpu
1421 * @cpu: CPU number to execute work on
1422 * @wq: workqueue to use
1423 * @work: work to queue
1425 * Returns %false if @work was already on a queue, %true otherwise.
1427 * We queue the work to a specific CPU, the caller must ensure it
1430 bool queue_work_on(int cpu
, struct workqueue_struct
*wq
,
1431 struct work_struct
*work
)
1434 unsigned long flags
;
1436 local_irq_save(flags
);
1438 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1439 __queue_work(cpu
, wq
, work
);
1443 local_irq_restore(flags
);
1446 EXPORT_SYMBOL(queue_work_on
);
1448 void delayed_work_timer_fn(unsigned long __data
)
1450 struct delayed_work
*dwork
= (struct delayed_work
*)__data
;
1452 /* should have been called from irqsafe timer with irq already off */
1453 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
1455 EXPORT_SYMBOL(delayed_work_timer_fn
);
1457 static void __queue_delayed_work(int cpu
, struct workqueue_struct
*wq
,
1458 struct delayed_work
*dwork
, unsigned long delay
)
1460 struct timer_list
*timer
= &dwork
->timer
;
1461 struct work_struct
*work
= &dwork
->work
;
1463 WARN_ON_ONCE(timer
->function
!= delayed_work_timer_fn
||
1464 timer
->data
!= (unsigned long)dwork
);
1465 WARN_ON_ONCE(timer_pending(timer
));
1466 WARN_ON_ONCE(!list_empty(&work
->entry
));
1469 * If @delay is 0, queue @dwork->work immediately. This is for
1470 * both optimization and correctness. The earliest @timer can
1471 * expire is on the closest next tick and delayed_work users depend
1472 * on that there's no such delay when @delay is 0.
1475 __queue_work(cpu
, wq
, &dwork
->work
);
1479 timer_stats_timer_set_start_info(&dwork
->timer
);
1483 timer
->expires
= jiffies
+ delay
;
1485 if (unlikely(cpu
!= WORK_CPU_UNBOUND
))
1486 add_timer_on(timer
, cpu
);
1492 * queue_delayed_work_on - queue work on specific CPU after delay
1493 * @cpu: CPU number to execute work on
1494 * @wq: workqueue to use
1495 * @dwork: work to queue
1496 * @delay: number of jiffies to wait before queueing
1498 * Returns %false if @work was already on a queue, %true otherwise. If
1499 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1502 bool queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1503 struct delayed_work
*dwork
, unsigned long delay
)
1505 struct work_struct
*work
= &dwork
->work
;
1507 unsigned long flags
;
1509 /* read the comment in __queue_work() */
1510 local_irq_save(flags
);
1512 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1513 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1517 local_irq_restore(flags
);
1520 EXPORT_SYMBOL(queue_delayed_work_on
);
1523 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1524 * @cpu: CPU number to execute work on
1525 * @wq: workqueue to use
1526 * @dwork: work to queue
1527 * @delay: number of jiffies to wait before queueing
1529 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1530 * modify @dwork's timer so that it expires after @delay. If @delay is
1531 * zero, @work is guaranteed to be scheduled immediately regardless of its
1534 * Returns %false if @dwork was idle and queued, %true if @dwork was
1535 * pending and its timer was modified.
1537 * This function is safe to call from any context including IRQ handler.
1538 * See try_to_grab_pending() for details.
1540 bool mod_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1541 struct delayed_work
*dwork
, unsigned long delay
)
1543 unsigned long flags
;
1547 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
1548 } while (unlikely(ret
== -EAGAIN
));
1550 if (likely(ret
>= 0)) {
1551 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1552 local_irq_restore(flags
);
1555 /* -ENOENT from try_to_grab_pending() becomes %true */
1558 EXPORT_SYMBOL_GPL(mod_delayed_work_on
);
1561 * worker_enter_idle - enter idle state
1562 * @worker: worker which is entering idle state
1564 * @worker is entering idle state. Update stats and idle timer if
1568 * spin_lock_irq(pool->lock).
1570 static void worker_enter_idle(struct worker
*worker
)
1572 struct worker_pool
*pool
= worker
->pool
;
1574 if (WARN_ON_ONCE(worker
->flags
& WORKER_IDLE
) ||
1575 WARN_ON_ONCE(!list_empty(&worker
->entry
) &&
1576 (worker
->hentry
.next
|| worker
->hentry
.pprev
)))
1579 /* can't use worker_set_flags(), also called from start_worker() */
1580 worker
->flags
|= WORKER_IDLE
;
1582 worker
->last_active
= jiffies
;
1584 /* idle_list is LIFO */
1585 list_add(&worker
->entry
, &pool
->idle_list
);
1587 if (too_many_workers(pool
) && !timer_pending(&pool
->idle_timer
))
1588 mod_timer(&pool
->idle_timer
, jiffies
+ IDLE_WORKER_TIMEOUT
);
1591 * Sanity check nr_running. Because wq_unbind_fn() releases
1592 * pool->lock between setting %WORKER_UNBOUND and zapping
1593 * nr_running, the warning may trigger spuriously. Check iff
1594 * unbind is not in progress.
1596 WARN_ON_ONCE(!(pool
->flags
& POOL_DISASSOCIATED
) &&
1597 pool
->nr_workers
== pool
->nr_idle
&&
1598 atomic_read(&pool
->nr_running
));
1602 * worker_leave_idle - leave idle state
1603 * @worker: worker which is leaving idle state
1605 * @worker is leaving idle state. Update stats.
1608 * spin_lock_irq(pool->lock).
1610 static void worker_leave_idle(struct worker
*worker
)
1612 struct worker_pool
*pool
= worker
->pool
;
1614 if (WARN_ON_ONCE(!(worker
->flags
& WORKER_IDLE
)))
1616 worker_clr_flags(worker
, WORKER_IDLE
);
1618 list_del_init(&worker
->entry
);
1622 * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it
1623 * @pool: target worker_pool
1625 * Bind %current to the cpu of @pool if it is associated and lock @pool.
1627 * Works which are scheduled while the cpu is online must at least be
1628 * scheduled to a worker which is bound to the cpu so that if they are
1629 * flushed from cpu callbacks while cpu is going down, they are
1630 * guaranteed to execute on the cpu.
1632 * This function is to be used by unbound workers and rescuers to bind
1633 * themselves to the target cpu and may race with cpu going down or
1634 * coming online. kthread_bind() can't be used because it may put the
1635 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1636 * verbatim as it's best effort and blocking and pool may be
1637 * [dis]associated in the meantime.
1639 * This function tries set_cpus_allowed() and locks pool and verifies the
1640 * binding against %POOL_DISASSOCIATED which is set during
1641 * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
1642 * enters idle state or fetches works without dropping lock, it can
1643 * guarantee the scheduling requirement described in the first paragraph.
1646 * Might sleep. Called without any lock but returns with pool->lock
1650 * %true if the associated pool is online (@worker is successfully
1651 * bound), %false if offline.
1653 static bool worker_maybe_bind_and_lock(struct worker_pool
*pool
)
1654 __acquires(&pool
->lock
)
1658 * The following call may fail, succeed or succeed
1659 * without actually migrating the task to the cpu if
1660 * it races with cpu hotunplug operation. Verify
1661 * against POOL_DISASSOCIATED.
1663 if (!(pool
->flags
& POOL_DISASSOCIATED
))
1664 set_cpus_allowed_ptr(current
, pool
->attrs
->cpumask
);
1666 spin_lock_irq(&pool
->lock
);
1667 if (pool
->flags
& POOL_DISASSOCIATED
)
1669 if (task_cpu(current
) == pool
->cpu
&&
1670 cpumask_equal(¤t
->cpus_allowed
, pool
->attrs
->cpumask
))
1672 spin_unlock_irq(&pool
->lock
);
1675 * We've raced with CPU hot[un]plug. Give it a breather
1676 * and retry migration. cond_resched() is required here;
1677 * otherwise, we might deadlock against cpu_stop trying to
1678 * bring down the CPU on non-preemptive kernel.
1685 static struct worker
*alloc_worker(void)
1687 struct worker
*worker
;
1689 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
1691 INIT_LIST_HEAD(&worker
->entry
);
1692 INIT_LIST_HEAD(&worker
->scheduled
);
1693 /* on creation a worker is in !idle && prep state */
1694 worker
->flags
= WORKER_PREP
;
1700 * create_worker - create a new workqueue worker
1701 * @pool: pool the new worker will belong to
1703 * Create a new worker which is bound to @pool. The returned worker
1704 * can be started by calling start_worker() or destroyed using
1708 * Might sleep. Does GFP_KERNEL allocations.
1711 * Pointer to the newly created worker.
1713 static struct worker
*create_worker(struct worker_pool
*pool
)
1715 struct worker
*worker
= NULL
;
1719 lockdep_assert_held(&pool
->manager_mutex
);
1722 * ID is needed to determine kthread name. Allocate ID first
1723 * without installing the pointer.
1725 idr_preload(GFP_KERNEL
);
1726 spin_lock_irq(&pool
->lock
);
1728 id
= idr_alloc(&pool
->worker_idr
, NULL
, 0, 0, GFP_NOWAIT
);
1730 spin_unlock_irq(&pool
->lock
);
1735 worker
= alloc_worker();
1739 worker
->pool
= pool
;
1743 snprintf(id_buf
, sizeof(id_buf
), "%d:%d%s", pool
->cpu
, id
,
1744 pool
->attrs
->nice
< 0 ? "H" : "");
1746 snprintf(id_buf
, sizeof(id_buf
), "u%d:%d", pool
->id
, id
);
1748 worker
->task
= kthread_create_on_node(worker_thread
, worker
, pool
->node
,
1749 "kworker/%s", id_buf
);
1750 if (IS_ERR(worker
->task
))
1754 * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1755 * online CPUs. It'll be re-applied when any of the CPUs come up.
1757 set_user_nice(worker
->task
, pool
->attrs
->nice
);
1758 set_cpus_allowed_ptr(worker
->task
, pool
->attrs
->cpumask
);
1760 /* prevent userland from meddling with cpumask of workqueue workers */
1761 worker
->task
->flags
|= PF_NO_SETAFFINITY
;
1764 * The caller is responsible for ensuring %POOL_DISASSOCIATED
1765 * remains stable across this function. See the comments above the
1766 * flag definition for details.
1768 if (pool
->flags
& POOL_DISASSOCIATED
)
1769 worker
->flags
|= WORKER_UNBOUND
;
1771 /* successful, commit the pointer to idr */
1772 spin_lock_irq(&pool
->lock
);
1773 idr_replace(&pool
->worker_idr
, worker
, worker
->id
);
1774 spin_unlock_irq(&pool
->lock
);
1780 spin_lock_irq(&pool
->lock
);
1781 idr_remove(&pool
->worker_idr
, id
);
1782 spin_unlock_irq(&pool
->lock
);
1789 * start_worker - start a newly created worker
1790 * @worker: worker to start
1792 * Make the pool aware of @worker and start it.
1795 * spin_lock_irq(pool->lock).
1797 static void start_worker(struct worker
*worker
)
1799 worker
->flags
|= WORKER_STARTED
;
1800 worker
->pool
->nr_workers
++;
1801 worker_enter_idle(worker
);
1802 wake_up_process(worker
->task
);
1806 * create_and_start_worker - create and start a worker for a pool
1807 * @pool: the target pool
1809 * Grab the managership of @pool and create and start a new worker for it.
1811 static int create_and_start_worker(struct worker_pool
*pool
)
1813 struct worker
*worker
;
1815 mutex_lock(&pool
->manager_mutex
);
1817 worker
= create_worker(pool
);
1819 spin_lock_irq(&pool
->lock
);
1820 start_worker(worker
);
1821 spin_unlock_irq(&pool
->lock
);
1824 mutex_unlock(&pool
->manager_mutex
);
1826 return worker
? 0 : -ENOMEM
;
1830 * destroy_worker - destroy a workqueue worker
1831 * @worker: worker to be destroyed
1833 * Destroy @worker and adjust @pool stats accordingly.
1836 * spin_lock_irq(pool->lock) which is released and regrabbed.
1838 static void destroy_worker(struct worker
*worker
)
1840 struct worker_pool
*pool
= worker
->pool
;
1842 lockdep_assert_held(&pool
->manager_mutex
);
1843 lockdep_assert_held(&pool
->lock
);
1845 /* sanity check frenzy */
1846 if (WARN_ON(worker
->current_work
) ||
1847 WARN_ON(!list_empty(&worker
->scheduled
)))
1850 if (worker
->flags
& WORKER_STARTED
)
1852 if (worker
->flags
& WORKER_IDLE
)
1856 * Once WORKER_DIE is set, the kworker may destroy itself at any
1857 * point. Pin to ensure the task stays until we're done with it.
1859 get_task_struct(worker
->task
);
1861 list_del_init(&worker
->entry
);
1862 worker
->flags
|= WORKER_DIE
;
1864 idr_remove(&pool
->worker_idr
, worker
->id
);
1866 spin_unlock_irq(&pool
->lock
);
1868 kthread_stop(worker
->task
);
1869 put_task_struct(worker
->task
);
1872 spin_lock_irq(&pool
->lock
);
1875 static void idle_worker_timeout(unsigned long __pool
)
1877 struct worker_pool
*pool
= (void *)__pool
;
1879 spin_lock_irq(&pool
->lock
);
1881 if (too_many_workers(pool
)) {
1882 struct worker
*worker
;
1883 unsigned long expires
;
1885 /* idle_list is kept in LIFO order, check the last one */
1886 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1887 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1889 if (time_before(jiffies
, expires
))
1890 mod_timer(&pool
->idle_timer
, expires
);
1892 /* it's been idle for too long, wake up manager */
1893 pool
->flags
|= POOL_MANAGE_WORKERS
;
1894 wake_up_worker(pool
);
1898 spin_unlock_irq(&pool
->lock
);
1901 static void send_mayday(struct work_struct
*work
)
1903 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1904 struct workqueue_struct
*wq
= pwq
->wq
;
1906 lockdep_assert_held(&wq_mayday_lock
);
1911 /* mayday mayday mayday */
1912 if (list_empty(&pwq
->mayday_node
)) {
1914 * If @pwq is for an unbound wq, its base ref may be put at
1915 * any time due to an attribute change. Pin @pwq until the
1916 * rescuer is done with it.
1919 list_add_tail(&pwq
->mayday_node
, &wq
->maydays
);
1920 wake_up_process(wq
->rescuer
->task
);
1924 static void pool_mayday_timeout(unsigned long __pool
)
1926 struct worker_pool
*pool
= (void *)__pool
;
1927 struct work_struct
*work
;
1929 spin_lock_irq(&wq_mayday_lock
); /* for wq->maydays */
1930 spin_lock(&pool
->lock
);
1932 if (need_to_create_worker(pool
)) {
1934 * We've been trying to create a new worker but
1935 * haven't been successful. We might be hitting an
1936 * allocation deadlock. Send distress signals to
1939 list_for_each_entry(work
, &pool
->worklist
, entry
)
1943 spin_unlock(&pool
->lock
);
1944 spin_unlock_irq(&wq_mayday_lock
);
1946 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INTERVAL
);
1950 * maybe_create_worker - create a new worker if necessary
1951 * @pool: pool to create a new worker for
1953 * Create a new worker for @pool if necessary. @pool is guaranteed to
1954 * have at least one idle worker on return from this function. If
1955 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1956 * sent to all rescuers with works scheduled on @pool to resolve
1957 * possible allocation deadlock.
1959 * On return, need_to_create_worker() is guaranteed to be %false and
1960 * may_start_working() %true.
1963 * spin_lock_irq(pool->lock) which may be released and regrabbed
1964 * multiple times. Does GFP_KERNEL allocations. Called only from
1967 static void maybe_create_worker(struct worker_pool
*pool
)
1968 __releases(&pool
->lock
)
1969 __acquires(&pool
->lock
)
1971 if (!need_to_create_worker(pool
))
1974 spin_unlock_irq(&pool
->lock
);
1976 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1977 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INITIAL_TIMEOUT
);
1980 struct worker
*worker
;
1982 worker
= create_worker(pool
);
1984 del_timer_sync(&pool
->mayday_timer
);
1985 spin_lock_irq(&pool
->lock
);
1986 start_worker(worker
);
1987 if (WARN_ON_ONCE(need_to_create_worker(pool
)))
1992 if (!need_to_create_worker(pool
))
1995 __set_current_state(TASK_INTERRUPTIBLE
);
1996 schedule_timeout(CREATE_COOLDOWN
);
1998 if (!need_to_create_worker(pool
))
2002 del_timer_sync(&pool
->mayday_timer
);
2003 spin_lock_irq(&pool
->lock
);
2004 if (need_to_create_worker(pool
))
2010 * maybe_destroy_worker - destroy workers which have been idle for a while
2011 * @pool: pool to destroy workers for
2013 * Destroy @pool workers which have been idle for longer than
2014 * IDLE_WORKER_TIMEOUT.
2017 * spin_lock_irq(pool->lock) which may be released and regrabbed
2018 * multiple times. Called only from manager.
2020 static void maybe_destroy_workers(struct worker_pool
*pool
)
2022 while (too_many_workers(pool
)) {
2023 struct worker
*worker
;
2024 unsigned long expires
;
2026 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
2027 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
2029 if (time_before(jiffies
, expires
)) {
2030 mod_timer(&pool
->idle_timer
, expires
);
2034 destroy_worker(worker
);
2039 * manage_workers - manage worker pool
2042 * Assume the manager role and manage the worker pool @worker belongs
2043 * to. At any given time, there can be only zero or one manager per
2044 * pool. The exclusion is handled automatically by this function.
2046 * The caller can safely start processing works on false return. On
2047 * true return, it's guaranteed that need_to_create_worker() is false
2048 * and may_start_working() is true.
2051 * spin_lock_irq(pool->lock) which may be released and regrabbed
2052 * multiple times. Does GFP_KERNEL allocations.
2055 * %false if the pool doesn't need management and the caller can safely
2056 * start processing works, %true if management function was performed and
2057 * the conditions that the caller verified before calling the function may
2058 * no longer be true.
2060 static bool manage_workers(struct worker
*worker
)
2062 struct worker_pool
*pool
= worker
->pool
;
2065 * Managership is governed by two mutexes - manager_arb and
2066 * manager_mutex. manager_arb handles arbitration of manager role.
2067 * Anyone who successfully grabs manager_arb wins the arbitration
2068 * and becomes the manager. mutex_trylock() on pool->manager_arb
2069 * failure while holding pool->lock reliably indicates that someone
2070 * else is managing the pool and the worker which failed trylock
2071 * can proceed to executing work items. This means that anyone
2072 * grabbing manager_arb is responsible for actually performing
2073 * manager duties. If manager_arb is grabbed and released without
2074 * actual management, the pool may stall indefinitely.
2076 * manager_mutex is used for exclusion of actual management
2077 * operations. The holder of manager_mutex can be sure that none
2078 * of management operations, including creation and destruction of
2079 * workers, won't take place until the mutex is released. Because
2080 * manager_mutex doesn't interfere with manager role arbitration,
2081 * it is guaranteed that the pool's management, while may be
2082 * delayed, won't be disturbed by someone else grabbing
2085 if (!mutex_trylock(&pool
->manager_arb
))
2089 * With manager arbitration won, manager_mutex would be free in
2090 * most cases. trylock first without dropping @pool->lock.
2092 if (unlikely(!mutex_trylock(&pool
->manager_mutex
))) {
2093 spin_unlock_irq(&pool
->lock
);
2094 mutex_lock(&pool
->manager_mutex
);
2095 spin_lock_irq(&pool
->lock
);
2098 pool
->flags
&= ~POOL_MANAGE_WORKERS
;
2101 * Destroy and then create so that may_start_working() is true
2104 maybe_destroy_workers(pool
);
2105 maybe_create_worker(pool
);
2107 mutex_unlock(&pool
->manager_mutex
);
2108 mutex_unlock(&pool
->manager_arb
);
2113 * process_one_work - process single work
2115 * @work: work to process
2117 * Process @work. This function contains all the logics necessary to
2118 * process a single work including synchronization against and
2119 * interaction with other workers on the same cpu, queueing and
2120 * flushing. As long as context requirement is met, any worker can
2121 * call this function to process a work.
2124 * spin_lock_irq(pool->lock) which is released and regrabbed.
2126 static void process_one_work(struct worker
*worker
, struct work_struct
*work
)
2127 __releases(&pool
->lock
)
2128 __acquires(&pool
->lock
)
2130 struct pool_workqueue
*pwq
= get_work_pwq(work
);
2131 struct worker_pool
*pool
= worker
->pool
;
2132 bool cpu_intensive
= pwq
->wq
->flags
& WQ_CPU_INTENSIVE
;
2134 struct worker
*collision
;
2135 #ifdef CONFIG_LOCKDEP
2137 * It is permissible to free the struct work_struct from
2138 * inside the function that is called from it, this we need to
2139 * take into account for lockdep too. To avoid bogus "held
2140 * lock freed" warnings as well as problems when looking into
2141 * work->lockdep_map, make a copy and use that here.
2143 struct lockdep_map lockdep_map
;
2145 lockdep_copy_map(&lockdep_map
, &work
->lockdep_map
);
2148 * Ensure we're on the correct CPU. DISASSOCIATED test is
2149 * necessary to avoid spurious warnings from rescuers servicing the
2150 * unbound or a disassociated pool.
2152 WARN_ON_ONCE(!(worker
->flags
& WORKER_UNBOUND
) &&
2153 !(pool
->flags
& POOL_DISASSOCIATED
) &&
2154 raw_smp_processor_id() != pool
->cpu
);
2157 * A single work shouldn't be executed concurrently by
2158 * multiple workers on a single cpu. Check whether anyone is
2159 * already processing the work. If so, defer the work to the
2160 * currently executing one.
2162 collision
= find_worker_executing_work(pool
, work
);
2163 if (unlikely(collision
)) {
2164 move_linked_works(work
, &collision
->scheduled
, NULL
);
2168 /* claim and dequeue */
2169 debug_work_deactivate(work
);
2170 hash_add(pool
->busy_hash
, &worker
->hentry
, (unsigned long)work
);
2171 worker
->current_work
= work
;
2172 worker
->current_func
= work
->func
;
2173 worker
->current_pwq
= pwq
;
2174 work_color
= get_work_color(work
);
2176 list_del_init(&work
->entry
);
2179 * CPU intensive works don't participate in concurrency
2180 * management. They're the scheduler's responsibility.
2182 if (unlikely(cpu_intensive
))
2183 worker_set_flags(worker
, WORKER_CPU_INTENSIVE
, true);
2186 * Unbound pool isn't concurrency managed and work items should be
2187 * executed ASAP. Wake up another worker if necessary.
2189 if ((worker
->flags
& WORKER_UNBOUND
) && need_more_worker(pool
))
2190 wake_up_worker(pool
);
2193 * Record the last pool and clear PENDING which should be the last
2194 * update to @work. Also, do this inside @pool->lock so that
2195 * PENDING and queued state changes happen together while IRQ is
2198 set_work_pool_and_clear_pending(work
, pool
->id
);
2200 spin_unlock_irq(&pool
->lock
);
2202 lock_map_acquire_read(&pwq
->wq
->lockdep_map
);
2203 lock_map_acquire(&lockdep_map
);
2204 trace_workqueue_execute_start(work
);
2205 worker
->current_func(work
);
2207 * While we must be careful to not use "work" after this, the trace
2208 * point will only record its address.
2210 trace_workqueue_execute_end(work
);
2211 lock_map_release(&lockdep_map
);
2212 lock_map_release(&pwq
->wq
->lockdep_map
);
2214 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
2215 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2216 " last function: %pf\n",
2217 current
->comm
, preempt_count(), task_pid_nr(current
),
2218 worker
->current_func
);
2219 debug_show_held_locks(current
);
2224 * The following prevents a kworker from hogging CPU on !PREEMPT
2225 * kernels, where a requeueing work item waiting for something to
2226 * happen could deadlock with stop_machine as such work item could
2227 * indefinitely requeue itself while all other CPUs are trapped in
2232 spin_lock_irq(&pool
->lock
);
2234 /* clear cpu intensive status */
2235 if (unlikely(cpu_intensive
))
2236 worker_clr_flags(worker
, WORKER_CPU_INTENSIVE
);
2238 /* we're done with it, release */
2239 hash_del(&worker
->hentry
);
2240 worker
->current_work
= NULL
;
2241 worker
->current_func
= NULL
;
2242 worker
->current_pwq
= NULL
;
2243 worker
->desc_valid
= false;
2244 pwq_dec_nr_in_flight(pwq
, work_color
);
2248 * process_scheduled_works - process scheduled works
2251 * Process all scheduled works. Please note that the scheduled list
2252 * may change while processing a work, so this function repeatedly
2253 * fetches a work from the top and executes it.
2256 * spin_lock_irq(pool->lock) which may be released and regrabbed
2259 static void process_scheduled_works(struct worker
*worker
)
2261 while (!list_empty(&worker
->scheduled
)) {
2262 struct work_struct
*work
= list_first_entry(&worker
->scheduled
,
2263 struct work_struct
, entry
);
2264 process_one_work(worker
, work
);
2269 * worker_thread - the worker thread function
2272 * The worker thread function. All workers belong to a worker_pool -
2273 * either a per-cpu one or dynamic unbound one. These workers process all
2274 * work items regardless of their specific target workqueue. The only
2275 * exception is work items which belong to workqueues with a rescuer which
2276 * will be explained in rescuer_thread().
2278 static int worker_thread(void *__worker
)
2280 struct worker
*worker
= __worker
;
2281 struct worker_pool
*pool
= worker
->pool
;
2283 /* tell the scheduler that this is a workqueue worker */
2284 worker
->task
->flags
|= PF_WQ_WORKER
;
2286 spin_lock_irq(&pool
->lock
);
2288 /* am I supposed to die? */
2289 if (unlikely(worker
->flags
& WORKER_DIE
)) {
2290 spin_unlock_irq(&pool
->lock
);
2291 WARN_ON_ONCE(!list_empty(&worker
->entry
));
2292 worker
->task
->flags
&= ~PF_WQ_WORKER
;
2296 worker_leave_idle(worker
);
2298 /* no more worker necessary? */
2299 if (!need_more_worker(pool
))
2302 /* do we need to manage? */
2303 if (unlikely(!may_start_working(pool
)) && manage_workers(worker
))
2307 * ->scheduled list can only be filled while a worker is
2308 * preparing to process a work or actually processing it.
2309 * Make sure nobody diddled with it while I was sleeping.
2311 WARN_ON_ONCE(!list_empty(&worker
->scheduled
));
2314 * Finish PREP stage. We're guaranteed to have at least one idle
2315 * worker or that someone else has already assumed the manager
2316 * role. This is where @worker starts participating in concurrency
2317 * management if applicable and concurrency management is restored
2318 * after being rebound. See rebind_workers() for details.
2320 worker_clr_flags(worker
, WORKER_PREP
| WORKER_REBOUND
);
2323 struct work_struct
*work
=
2324 list_first_entry(&pool
->worklist
,
2325 struct work_struct
, entry
);
2327 if (likely(!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))) {
2328 /* optimization path, not strictly necessary */
2329 process_one_work(worker
, work
);
2330 if (unlikely(!list_empty(&worker
->scheduled
)))
2331 process_scheduled_works(worker
);
2333 move_linked_works(work
, &worker
->scheduled
, NULL
);
2334 process_scheduled_works(worker
);
2336 } while (keep_working(pool
));
2338 worker_set_flags(worker
, WORKER_PREP
, false);
2340 if (unlikely(need_to_manage_workers(pool
)) && manage_workers(worker
))
2344 * pool->lock is held and there's no work to process and no need to
2345 * manage, sleep. Workers are woken up only while holding
2346 * pool->lock or from local cpu, so setting the current state
2347 * before releasing pool->lock is enough to prevent losing any
2350 worker_enter_idle(worker
);
2351 __set_current_state(TASK_INTERRUPTIBLE
);
2352 spin_unlock_irq(&pool
->lock
);
2358 * rescuer_thread - the rescuer thread function
2361 * Workqueue rescuer thread function. There's one rescuer for each
2362 * workqueue which has WQ_MEM_RECLAIM set.
2364 * Regular work processing on a pool may block trying to create a new
2365 * worker which uses GFP_KERNEL allocation which has slight chance of
2366 * developing into deadlock if some works currently on the same queue
2367 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2368 * the problem rescuer solves.
2370 * When such condition is possible, the pool summons rescuers of all
2371 * workqueues which have works queued on the pool and let them process
2372 * those works so that forward progress can be guaranteed.
2374 * This should happen rarely.
2376 static int rescuer_thread(void *__rescuer
)
2378 struct worker
*rescuer
= __rescuer
;
2379 struct workqueue_struct
*wq
= rescuer
->rescue_wq
;
2380 struct list_head
*scheduled
= &rescuer
->scheduled
;
2383 set_user_nice(current
, RESCUER_NICE_LEVEL
);
2386 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2387 * doesn't participate in concurrency management.
2389 rescuer
->task
->flags
|= PF_WQ_WORKER
;
2391 set_current_state(TASK_INTERRUPTIBLE
);
2394 * By the time the rescuer is requested to stop, the workqueue
2395 * shouldn't have any work pending, but @wq->maydays may still have
2396 * pwq(s) queued. This can happen by non-rescuer workers consuming
2397 * all the work items before the rescuer got to them. Go through
2398 * @wq->maydays processing before acting on should_stop so that the
2399 * list is always empty on exit.
2401 should_stop
= kthread_should_stop();
2403 /* see whether any pwq is asking for help */
2404 spin_lock_irq(&wq_mayday_lock
);
2406 while (!list_empty(&wq
->maydays
)) {
2407 struct pool_workqueue
*pwq
= list_first_entry(&wq
->maydays
,
2408 struct pool_workqueue
, mayday_node
);
2409 struct worker_pool
*pool
= pwq
->pool
;
2410 struct work_struct
*work
, *n
;
2412 __set_current_state(TASK_RUNNING
);
2413 list_del_init(&pwq
->mayday_node
);
2415 spin_unlock_irq(&wq_mayday_lock
);
2417 /* migrate to the target cpu if possible */
2418 worker_maybe_bind_and_lock(pool
);
2419 rescuer
->pool
= pool
;
2422 * Slurp in all works issued via this workqueue and
2425 WARN_ON_ONCE(!list_empty(&rescuer
->scheduled
));
2426 list_for_each_entry_safe(work
, n
, &pool
->worklist
, entry
)
2427 if (get_work_pwq(work
) == pwq
)
2428 move_linked_works(work
, scheduled
, &n
);
2430 process_scheduled_works(rescuer
);
2433 * Put the reference grabbed by send_mayday(). @pool won't
2434 * go away while we're holding its lock.
2439 * Leave this pool. If keep_working() is %true, notify a
2440 * regular worker; otherwise, we end up with 0 concurrency
2441 * and stalling the execution.
2443 if (keep_working(pool
))
2444 wake_up_worker(pool
);
2446 rescuer
->pool
= NULL
;
2447 spin_unlock(&pool
->lock
);
2448 spin_lock(&wq_mayday_lock
);
2451 spin_unlock_irq(&wq_mayday_lock
);
2454 __set_current_state(TASK_RUNNING
);
2455 rescuer
->task
->flags
&= ~PF_WQ_WORKER
;
2459 /* rescuers should never participate in concurrency management */
2460 WARN_ON_ONCE(!(rescuer
->flags
& WORKER_NOT_RUNNING
));
2466 struct work_struct work
;
2467 struct completion done
;
2470 static void wq_barrier_func(struct work_struct
*work
)
2472 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
2473 complete(&barr
->done
);
2477 * insert_wq_barrier - insert a barrier work
2478 * @pwq: pwq to insert barrier into
2479 * @barr: wq_barrier to insert
2480 * @target: target work to attach @barr to
2481 * @worker: worker currently executing @target, NULL if @target is not executing
2483 * @barr is linked to @target such that @barr is completed only after
2484 * @target finishes execution. Please note that the ordering
2485 * guarantee is observed only with respect to @target and on the local
2488 * Currently, a queued barrier can't be canceled. This is because
2489 * try_to_grab_pending() can't determine whether the work to be
2490 * grabbed is at the head of the queue and thus can't clear LINKED
2491 * flag of the previous work while there must be a valid next work
2492 * after a work with LINKED flag set.
2494 * Note that when @worker is non-NULL, @target may be modified
2495 * underneath us, so we can't reliably determine pwq from @target.
2498 * spin_lock_irq(pool->lock).
2500 static void insert_wq_barrier(struct pool_workqueue
*pwq
,
2501 struct wq_barrier
*barr
,
2502 struct work_struct
*target
, struct worker
*worker
)
2504 struct list_head
*head
;
2505 unsigned int linked
= 0;
2508 * debugobject calls are safe here even with pool->lock locked
2509 * as we know for sure that this will not trigger any of the
2510 * checks and call back into the fixup functions where we
2513 INIT_WORK_ONSTACK(&barr
->work
, wq_barrier_func
);
2514 __set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(&barr
->work
));
2515 init_completion(&barr
->done
);
2518 * If @target is currently being executed, schedule the
2519 * barrier to the worker; otherwise, put it after @target.
2522 head
= worker
->scheduled
.next
;
2524 unsigned long *bits
= work_data_bits(target
);
2526 head
= target
->entry
.next
;
2527 /* there can already be other linked works, inherit and set */
2528 linked
= *bits
& WORK_STRUCT_LINKED
;
2529 __set_bit(WORK_STRUCT_LINKED_BIT
, bits
);
2532 debug_work_activate(&barr
->work
);
2533 insert_work(pwq
, &barr
->work
, head
,
2534 work_color_to_flags(WORK_NO_COLOR
) | linked
);
2538 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2539 * @wq: workqueue being flushed
2540 * @flush_color: new flush color, < 0 for no-op
2541 * @work_color: new work color, < 0 for no-op
2543 * Prepare pwqs for workqueue flushing.
2545 * If @flush_color is non-negative, flush_color on all pwqs should be
2546 * -1. If no pwq has in-flight commands at the specified color, all
2547 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2548 * has in flight commands, its pwq->flush_color is set to
2549 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2550 * wakeup logic is armed and %true is returned.
2552 * The caller should have initialized @wq->first_flusher prior to
2553 * calling this function with non-negative @flush_color. If
2554 * @flush_color is negative, no flush color update is done and %false
2557 * If @work_color is non-negative, all pwqs should have the same
2558 * work_color which is previous to @work_color and all will be
2559 * advanced to @work_color.
2562 * mutex_lock(wq->mutex).
2565 * %true if @flush_color >= 0 and there's something to flush. %false
2568 static bool flush_workqueue_prep_pwqs(struct workqueue_struct
*wq
,
2569 int flush_color
, int work_color
)
2572 struct pool_workqueue
*pwq
;
2574 if (flush_color
>= 0) {
2575 WARN_ON_ONCE(atomic_read(&wq
->nr_pwqs_to_flush
));
2576 atomic_set(&wq
->nr_pwqs_to_flush
, 1);
2579 for_each_pwq(pwq
, wq
) {
2580 struct worker_pool
*pool
= pwq
->pool
;
2582 spin_lock_irq(&pool
->lock
);
2584 if (flush_color
>= 0) {
2585 WARN_ON_ONCE(pwq
->flush_color
!= -1);
2587 if (pwq
->nr_in_flight
[flush_color
]) {
2588 pwq
->flush_color
= flush_color
;
2589 atomic_inc(&wq
->nr_pwqs_to_flush
);
2594 if (work_color
>= 0) {
2595 WARN_ON_ONCE(work_color
!= work_next_color(pwq
->work_color
));
2596 pwq
->work_color
= work_color
;
2599 spin_unlock_irq(&pool
->lock
);
2602 if (flush_color
>= 0 && atomic_dec_and_test(&wq
->nr_pwqs_to_flush
))
2603 complete(&wq
->first_flusher
->done
);
2609 * flush_workqueue - ensure that any scheduled work has run to completion.
2610 * @wq: workqueue to flush
2612 * This function sleeps until all work items which were queued on entry
2613 * have finished execution, but it is not livelocked by new incoming ones.
2615 void flush_workqueue(struct workqueue_struct
*wq
)
2617 struct wq_flusher this_flusher
= {
2618 .list
= LIST_HEAD_INIT(this_flusher
.list
),
2620 .done
= COMPLETION_INITIALIZER_ONSTACK(this_flusher
.done
),
2624 lock_map_acquire(&wq
->lockdep_map
);
2625 lock_map_release(&wq
->lockdep_map
);
2627 mutex_lock(&wq
->mutex
);
2630 * Start-to-wait phase
2632 next_color
= work_next_color(wq
->work_color
);
2634 if (next_color
!= wq
->flush_color
) {
2636 * Color space is not full. The current work_color
2637 * becomes our flush_color and work_color is advanced
2640 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
));
2641 this_flusher
.flush_color
= wq
->work_color
;
2642 wq
->work_color
= next_color
;
2644 if (!wq
->first_flusher
) {
2645 /* no flush in progress, become the first flusher */
2646 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2648 wq
->first_flusher
= &this_flusher
;
2650 if (!flush_workqueue_prep_pwqs(wq
, wq
->flush_color
,
2652 /* nothing to flush, done */
2653 wq
->flush_color
= next_color
;
2654 wq
->first_flusher
= NULL
;
2659 WARN_ON_ONCE(wq
->flush_color
== this_flusher
.flush_color
);
2660 list_add_tail(&this_flusher
.list
, &wq
->flusher_queue
);
2661 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2665 * Oops, color space is full, wait on overflow queue.
2666 * The next flush completion will assign us
2667 * flush_color and transfer to flusher_queue.
2669 list_add_tail(&this_flusher
.list
, &wq
->flusher_overflow
);
2672 mutex_unlock(&wq
->mutex
);
2674 wait_for_completion(&this_flusher
.done
);
2677 * Wake-up-and-cascade phase
2679 * First flushers are responsible for cascading flushes and
2680 * handling overflow. Non-first flushers can simply return.
2682 if (wq
->first_flusher
!= &this_flusher
)
2685 mutex_lock(&wq
->mutex
);
2687 /* we might have raced, check again with mutex held */
2688 if (wq
->first_flusher
!= &this_flusher
)
2691 wq
->first_flusher
= NULL
;
2693 WARN_ON_ONCE(!list_empty(&this_flusher
.list
));
2694 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2697 struct wq_flusher
*next
, *tmp
;
2699 /* complete all the flushers sharing the current flush color */
2700 list_for_each_entry_safe(next
, tmp
, &wq
->flusher_queue
, list
) {
2701 if (next
->flush_color
!= wq
->flush_color
)
2703 list_del_init(&next
->list
);
2704 complete(&next
->done
);
2707 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
) &&
2708 wq
->flush_color
!= work_next_color(wq
->work_color
));
2710 /* this flush_color is finished, advance by one */
2711 wq
->flush_color
= work_next_color(wq
->flush_color
);
2713 /* one color has been freed, handle overflow queue */
2714 if (!list_empty(&wq
->flusher_overflow
)) {
2716 * Assign the same color to all overflowed
2717 * flushers, advance work_color and append to
2718 * flusher_queue. This is the start-to-wait
2719 * phase for these overflowed flushers.
2721 list_for_each_entry(tmp
, &wq
->flusher_overflow
, list
)
2722 tmp
->flush_color
= wq
->work_color
;
2724 wq
->work_color
= work_next_color(wq
->work_color
);
2726 list_splice_tail_init(&wq
->flusher_overflow
,
2727 &wq
->flusher_queue
);
2728 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2731 if (list_empty(&wq
->flusher_queue
)) {
2732 WARN_ON_ONCE(wq
->flush_color
!= wq
->work_color
);
2737 * Need to flush more colors. Make the next flusher
2738 * the new first flusher and arm pwqs.
2740 WARN_ON_ONCE(wq
->flush_color
== wq
->work_color
);
2741 WARN_ON_ONCE(wq
->flush_color
!= next
->flush_color
);
2743 list_del_init(&next
->list
);
2744 wq
->first_flusher
= next
;
2746 if (flush_workqueue_prep_pwqs(wq
, wq
->flush_color
, -1))
2750 * Meh... this color is already done, clear first
2751 * flusher and repeat cascading.
2753 wq
->first_flusher
= NULL
;
2757 mutex_unlock(&wq
->mutex
);
2759 EXPORT_SYMBOL_GPL(flush_workqueue
);
2762 * drain_workqueue - drain a workqueue
2763 * @wq: workqueue to drain
2765 * Wait until the workqueue becomes empty. While draining is in progress,
2766 * only chain queueing is allowed. IOW, only currently pending or running
2767 * work items on @wq can queue further work items on it. @wq is flushed
2768 * repeatedly until it becomes empty. The number of flushing is detemined
2769 * by the depth of chaining and should be relatively short. Whine if it
2772 void drain_workqueue(struct workqueue_struct
*wq
)
2774 unsigned int flush_cnt
= 0;
2775 struct pool_workqueue
*pwq
;
2778 * __queue_work() needs to test whether there are drainers, is much
2779 * hotter than drain_workqueue() and already looks at @wq->flags.
2780 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
2782 mutex_lock(&wq
->mutex
);
2783 if (!wq
->nr_drainers
++)
2784 wq
->flags
|= __WQ_DRAINING
;
2785 mutex_unlock(&wq
->mutex
);
2787 flush_workqueue(wq
);
2789 mutex_lock(&wq
->mutex
);
2791 for_each_pwq(pwq
, wq
) {
2794 spin_lock_irq(&pwq
->pool
->lock
);
2795 drained
= !pwq
->nr_active
&& list_empty(&pwq
->delayed_works
);
2796 spin_unlock_irq(&pwq
->pool
->lock
);
2801 if (++flush_cnt
== 10 ||
2802 (flush_cnt
% 100 == 0 && flush_cnt
<= 1000))
2803 pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
2804 wq
->name
, flush_cnt
);
2806 mutex_unlock(&wq
->mutex
);
2810 if (!--wq
->nr_drainers
)
2811 wq
->flags
&= ~__WQ_DRAINING
;
2812 mutex_unlock(&wq
->mutex
);
2814 EXPORT_SYMBOL_GPL(drain_workqueue
);
2816 static bool start_flush_work(struct work_struct
*work
, struct wq_barrier
*barr
)
2818 struct worker
*worker
= NULL
;
2819 struct worker_pool
*pool
;
2820 struct pool_workqueue
*pwq
;
2824 local_irq_disable();
2825 pool
= get_work_pool(work
);
2831 spin_lock(&pool
->lock
);
2832 /* see the comment in try_to_grab_pending() with the same code */
2833 pwq
= get_work_pwq(work
);
2835 if (unlikely(pwq
->pool
!= pool
))
2838 worker
= find_worker_executing_work(pool
, work
);
2841 pwq
= worker
->current_pwq
;
2844 insert_wq_barrier(pwq
, barr
, work
, worker
);
2845 spin_unlock_irq(&pool
->lock
);
2848 * If @max_active is 1 or rescuer is in use, flushing another work
2849 * item on the same workqueue may lead to deadlock. Make sure the
2850 * flusher is not running on the same workqueue by verifying write
2853 if (pwq
->wq
->saved_max_active
== 1 || pwq
->wq
->rescuer
)
2854 lock_map_acquire(&pwq
->wq
->lockdep_map
);
2856 lock_map_acquire_read(&pwq
->wq
->lockdep_map
);
2857 lock_map_release(&pwq
->wq
->lockdep_map
);
2861 spin_unlock_irq(&pool
->lock
);
2866 * flush_work - wait for a work to finish executing the last queueing instance
2867 * @work: the work to flush
2869 * Wait until @work has finished execution. @work is guaranteed to be idle
2870 * on return if it hasn't been requeued since flush started.
2873 * %true if flush_work() waited for the work to finish execution,
2874 * %false if it was already idle.
2876 bool flush_work(struct work_struct
*work
)
2878 struct wq_barrier barr
;
2880 lock_map_acquire(&work
->lockdep_map
);
2881 lock_map_release(&work
->lockdep_map
);
2883 if (start_flush_work(work
, &barr
)) {
2884 wait_for_completion(&barr
.done
);
2885 destroy_work_on_stack(&barr
.work
);
2891 EXPORT_SYMBOL_GPL(flush_work
);
2895 struct work_struct
*work
;
2898 static int cwt_wakefn(wait_queue_t
*wait
, unsigned mode
, int sync
, void *key
)
2900 struct cwt_wait
*cwait
= container_of(wait
, struct cwt_wait
, wait
);
2902 if (cwait
->work
!= key
)
2904 return autoremove_wake_function(wait
, mode
, sync
, key
);
2907 static bool __cancel_work_timer(struct work_struct
*work
, bool is_dwork
)
2909 static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq
);
2910 unsigned long flags
;
2914 ret
= try_to_grab_pending(work
, is_dwork
, &flags
);
2916 * If someone else is already canceling, wait for it to
2917 * finish. flush_work() doesn't work for PREEMPT_NONE
2918 * because we may get scheduled between @work's completion
2919 * and the other canceling task resuming and clearing
2920 * CANCELING - flush_work() will return false immediately
2921 * as @work is no longer busy, try_to_grab_pending() will
2922 * return -ENOENT as @work is still being canceled and the
2923 * other canceling task won't be able to clear CANCELING as
2924 * we're hogging the CPU.
2926 * Let's wait for completion using a waitqueue. As this
2927 * may lead to the thundering herd problem, use a custom
2928 * wake function which matches @work along with exclusive
2931 if (unlikely(ret
== -ENOENT
)) {
2932 struct cwt_wait cwait
;
2934 init_wait(&cwait
.wait
);
2935 cwait
.wait
.func
= cwt_wakefn
;
2938 prepare_to_wait_exclusive(&cancel_waitq
, &cwait
.wait
,
2939 TASK_UNINTERRUPTIBLE
);
2940 if (work_is_canceling(work
))
2942 finish_wait(&cancel_waitq
, &cwait
.wait
);
2944 } while (unlikely(ret
< 0));
2946 /* tell other tasks trying to grab @work to back off */
2947 mark_work_canceling(work
);
2948 local_irq_restore(flags
);
2951 clear_work_data(work
);
2954 * Paired with prepare_to_wait() above so that either
2955 * waitqueue_active() is visible here or !work_is_canceling() is
2959 if (waitqueue_active(&cancel_waitq
))
2960 __wake_up(&cancel_waitq
, TASK_NORMAL
, 1, work
);
2966 * cancel_work_sync - cancel a work and wait for it to finish
2967 * @work: the work to cancel
2969 * Cancel @work and wait for its execution to finish. This function
2970 * can be used even if the work re-queues itself or migrates to
2971 * another workqueue. On return from this function, @work is
2972 * guaranteed to be not pending or executing on any CPU.
2974 * cancel_work_sync(&delayed_work->work) must not be used for
2975 * delayed_work's. Use cancel_delayed_work_sync() instead.
2977 * The caller must ensure that the workqueue on which @work was last
2978 * queued can't be destroyed before this function returns.
2981 * %true if @work was pending, %false otherwise.
2983 bool cancel_work_sync(struct work_struct
*work
)
2985 return __cancel_work_timer(work
, false);
2987 EXPORT_SYMBOL_GPL(cancel_work_sync
);
2990 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2991 * @dwork: the delayed work to flush
2993 * Delayed timer is cancelled and the pending work is queued for
2994 * immediate execution. Like flush_work(), this function only
2995 * considers the last queueing instance of @dwork.
2998 * %true if flush_work() waited for the work to finish execution,
2999 * %false if it was already idle.
3001 bool flush_delayed_work(struct delayed_work
*dwork
)
3003 local_irq_disable();
3004 if (del_timer_sync(&dwork
->timer
))
3005 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
3007 return flush_work(&dwork
->work
);
3009 EXPORT_SYMBOL(flush_delayed_work
);
3012 * cancel_delayed_work - cancel a delayed work
3013 * @dwork: delayed_work to cancel
3015 * Kill off a pending delayed_work. Returns %true if @dwork was pending
3016 * and canceled; %false if wasn't pending. Note that the work callback
3017 * function may still be running on return, unless it returns %true and the
3018 * work doesn't re-arm itself. Explicitly flush or use
3019 * cancel_delayed_work_sync() to wait on it.
3021 * This function is safe to call from any context including IRQ handler.
3023 bool cancel_delayed_work(struct delayed_work
*dwork
)
3025 unsigned long flags
;
3029 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
3030 } while (unlikely(ret
== -EAGAIN
));
3032 if (unlikely(ret
< 0))
3035 set_work_pool_and_clear_pending(&dwork
->work
,
3036 get_work_pool_id(&dwork
->work
));
3037 local_irq_restore(flags
);
3040 EXPORT_SYMBOL(cancel_delayed_work
);
3043 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
3044 * @dwork: the delayed work cancel
3046 * This is cancel_work_sync() for delayed works.
3049 * %true if @dwork was pending, %false otherwise.
3051 bool cancel_delayed_work_sync(struct delayed_work
*dwork
)
3053 return __cancel_work_timer(&dwork
->work
, true);
3055 EXPORT_SYMBOL(cancel_delayed_work_sync
);
3058 * schedule_on_each_cpu - execute a function synchronously on each online CPU
3059 * @func: the function to call
3061 * schedule_on_each_cpu() executes @func on each online CPU using the
3062 * system workqueue and blocks until all CPUs have completed.
3063 * schedule_on_each_cpu() is very slow.
3066 * 0 on success, -errno on failure.
3068 int schedule_on_each_cpu(work_func_t func
)
3071 struct work_struct __percpu
*works
;
3073 works
= alloc_percpu(struct work_struct
);
3079 for_each_online_cpu(cpu
) {
3080 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
3082 INIT_WORK(work
, func
);
3083 schedule_work_on(cpu
, work
);
3086 for_each_online_cpu(cpu
)
3087 flush_work(per_cpu_ptr(works
, cpu
));
3095 * flush_scheduled_work - ensure that any scheduled work has run to completion.
3097 * Forces execution of the kernel-global workqueue and blocks until its
3100 * Think twice before calling this function! It's very easy to get into
3101 * trouble if you don't take great care. Either of the following situations
3102 * will lead to deadlock:
3104 * One of the work items currently on the workqueue needs to acquire
3105 * a lock held by your code or its caller.
3107 * Your code is running in the context of a work routine.
3109 * They will be detected by lockdep when they occur, but the first might not
3110 * occur very often. It depends on what work items are on the workqueue and
3111 * what locks they need, which you have no control over.
3113 * In most situations flushing the entire workqueue is overkill; you merely
3114 * need to know that a particular work item isn't queued and isn't running.
3115 * In such cases you should use cancel_delayed_work_sync() or
3116 * cancel_work_sync() instead.
3118 void flush_scheduled_work(void)
3120 flush_workqueue(system_wq
);
3122 EXPORT_SYMBOL(flush_scheduled_work
);
3125 * execute_in_process_context - reliably execute the routine with user context
3126 * @fn: the function to execute
3127 * @ew: guaranteed storage for the execute work structure (must
3128 * be available when the work executes)
3130 * Executes the function immediately if process context is available,
3131 * otherwise schedules the function for delayed execution.
3133 * Returns: 0 - function was executed
3134 * 1 - function was scheduled for execution
3136 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
3138 if (!in_interrupt()) {
3143 INIT_WORK(&ew
->work
, fn
);
3144 schedule_work(&ew
->work
);
3148 EXPORT_SYMBOL_GPL(execute_in_process_context
);
3152 * Workqueues with WQ_SYSFS flag set is visible to userland via
3153 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
3154 * following attributes.
3156 * per_cpu RO bool : whether the workqueue is per-cpu or unbound
3157 * max_active RW int : maximum number of in-flight work items
3159 * Unbound workqueues have the following extra attributes.
3161 * id RO int : the associated pool ID
3162 * nice RW int : nice value of the workers
3163 * cpumask RW mask : bitmask of allowed CPUs for the workers
3166 struct workqueue_struct
*wq
;
3170 static struct workqueue_struct
*dev_to_wq(struct device
*dev
)
3172 struct wq_device
*wq_dev
= container_of(dev
, struct wq_device
, dev
);
3177 static ssize_t
wq_per_cpu_show(struct device
*dev
,
3178 struct device_attribute
*attr
, char *buf
)
3180 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3182 return scnprintf(buf
, PAGE_SIZE
, "%d\n", (bool)!(wq
->flags
& WQ_UNBOUND
));
3185 static ssize_t
wq_max_active_show(struct device
*dev
,
3186 struct device_attribute
*attr
, char *buf
)
3188 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3190 return scnprintf(buf
, PAGE_SIZE
, "%d\n", wq
->saved_max_active
);
3193 static ssize_t
wq_max_active_store(struct device
*dev
,
3194 struct device_attribute
*attr
,
3195 const char *buf
, size_t count
)
3197 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3200 if (sscanf(buf
, "%d", &val
) != 1 || val
<= 0)
3203 workqueue_set_max_active(wq
, val
);
3207 static struct device_attribute wq_sysfs_attrs
[] = {
3208 __ATTR(per_cpu
, 0444, wq_per_cpu_show
, NULL
),
3209 __ATTR(max_active
, 0644, wq_max_active_show
, wq_max_active_store
),
3213 static ssize_t
wq_pool_ids_show(struct device
*dev
,
3214 struct device_attribute
*attr
, char *buf
)
3216 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3217 const char *delim
= "";
3218 int node
, written
= 0;
3220 rcu_read_lock_sched();
3221 for_each_node(node
) {
3222 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
,
3223 "%s%d:%d", delim
, node
,
3224 unbound_pwq_by_node(wq
, node
)->pool
->id
);
3227 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
, "\n");
3228 rcu_read_unlock_sched();
3233 static ssize_t
wq_nice_show(struct device
*dev
, struct device_attribute
*attr
,
3236 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3239 mutex_lock(&wq
->mutex
);
3240 written
= scnprintf(buf
, PAGE_SIZE
, "%d\n", wq
->unbound_attrs
->nice
);
3241 mutex_unlock(&wq
->mutex
);
3246 /* prepare workqueue_attrs for sysfs store operations */
3247 static struct workqueue_attrs
*wq_sysfs_prep_attrs(struct workqueue_struct
*wq
)
3249 struct workqueue_attrs
*attrs
;
3251 attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3255 mutex_lock(&wq
->mutex
);
3256 copy_workqueue_attrs(attrs
, wq
->unbound_attrs
);
3257 mutex_unlock(&wq
->mutex
);
3261 static ssize_t
wq_nice_store(struct device
*dev
, struct device_attribute
*attr
,
3262 const char *buf
, size_t count
)
3264 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3265 struct workqueue_attrs
*attrs
;
3268 attrs
= wq_sysfs_prep_attrs(wq
);
3272 if (sscanf(buf
, "%d", &attrs
->nice
) == 1 &&
3273 attrs
->nice
>= -20 && attrs
->nice
<= 19)
3274 ret
= apply_workqueue_attrs(wq
, attrs
);
3278 free_workqueue_attrs(attrs
);
3279 return ret
?: count
;
3282 static ssize_t
wq_cpumask_show(struct device
*dev
,
3283 struct device_attribute
*attr
, char *buf
)
3285 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3288 mutex_lock(&wq
->mutex
);
3289 written
= cpumask_scnprintf(buf
, PAGE_SIZE
, wq
->unbound_attrs
->cpumask
);
3290 mutex_unlock(&wq
->mutex
);
3292 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
, "\n");
3296 static ssize_t
wq_cpumask_store(struct device
*dev
,
3297 struct device_attribute
*attr
,
3298 const char *buf
, size_t count
)
3300 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3301 struct workqueue_attrs
*attrs
;
3304 attrs
= wq_sysfs_prep_attrs(wq
);
3308 ret
= cpumask_parse(buf
, attrs
->cpumask
);
3310 ret
= apply_workqueue_attrs(wq
, attrs
);
3312 free_workqueue_attrs(attrs
);
3313 return ret
?: count
;
3316 static ssize_t
wq_numa_show(struct device
*dev
, struct device_attribute
*attr
,
3319 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3322 mutex_lock(&wq
->mutex
);
3323 written
= scnprintf(buf
, PAGE_SIZE
, "%d\n",
3324 !wq
->unbound_attrs
->no_numa
);
3325 mutex_unlock(&wq
->mutex
);
3330 static ssize_t
wq_numa_store(struct device
*dev
, struct device_attribute
*attr
,
3331 const char *buf
, size_t count
)
3333 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3334 struct workqueue_attrs
*attrs
;
3337 attrs
= wq_sysfs_prep_attrs(wq
);
3342 if (sscanf(buf
, "%d", &v
) == 1) {
3343 attrs
->no_numa
= !v
;
3344 ret
= apply_workqueue_attrs(wq
, attrs
);
3347 free_workqueue_attrs(attrs
);
3348 return ret
?: count
;
3351 static struct device_attribute wq_sysfs_unbound_attrs
[] = {
3352 __ATTR(pool_ids
, 0444, wq_pool_ids_show
, NULL
),
3353 __ATTR(nice
, 0644, wq_nice_show
, wq_nice_store
),
3354 __ATTR(cpumask
, 0644, wq_cpumask_show
, wq_cpumask_store
),
3355 __ATTR(numa
, 0644, wq_numa_show
, wq_numa_store
),
3359 static struct bus_type wq_subsys
= {
3360 .name
= "workqueue",
3361 .dev_attrs
= wq_sysfs_attrs
,
3364 static int __init
wq_sysfs_init(void)
3366 return subsys_virtual_register(&wq_subsys
, NULL
);
3368 core_initcall(wq_sysfs_init
);
3370 static void wq_device_release(struct device
*dev
)
3372 struct wq_device
*wq_dev
= container_of(dev
, struct wq_device
, dev
);
3378 * workqueue_sysfs_register - make a workqueue visible in sysfs
3379 * @wq: the workqueue to register
3381 * Expose @wq in sysfs under /sys/bus/workqueue/devices.
3382 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
3383 * which is the preferred method.
3385 * Workqueue user should use this function directly iff it wants to apply
3386 * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
3387 * apply_workqueue_attrs() may race against userland updating the
3390 * Returns 0 on success, -errno on failure.
3392 int workqueue_sysfs_register(struct workqueue_struct
*wq
)
3394 struct wq_device
*wq_dev
;
3398 * Adjusting max_active or creating new pwqs by applyting
3399 * attributes breaks ordering guarantee. Disallow exposing ordered
3402 if (WARN_ON(wq
->flags
& __WQ_ORDERED_EXPLICIT
))
3405 wq
->wq_dev
= wq_dev
= kzalloc(sizeof(*wq_dev
), GFP_KERNEL
);
3410 wq_dev
->dev
.bus
= &wq_subsys
;
3411 wq_dev
->dev
.init_name
= wq
->name
;
3412 wq_dev
->dev
.release
= wq_device_release
;
3415 * unbound_attrs are created separately. Suppress uevent until
3416 * everything is ready.
3418 dev_set_uevent_suppress(&wq_dev
->dev
, true);
3420 ret
= device_register(&wq_dev
->dev
);
3427 if (wq
->flags
& WQ_UNBOUND
) {
3428 struct device_attribute
*attr
;
3430 for (attr
= wq_sysfs_unbound_attrs
; attr
->attr
.name
; attr
++) {
3431 ret
= device_create_file(&wq_dev
->dev
, attr
);
3433 device_unregister(&wq_dev
->dev
);
3440 dev_set_uevent_suppress(&wq_dev
->dev
, false);
3441 kobject_uevent(&wq_dev
->dev
.kobj
, KOBJ_ADD
);
3446 * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
3447 * @wq: the workqueue to unregister
3449 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
3451 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
)
3453 struct wq_device
*wq_dev
= wq
->wq_dev
;
3459 device_unregister(&wq_dev
->dev
);
3461 #else /* CONFIG_SYSFS */
3462 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
) { }
3463 #endif /* CONFIG_SYSFS */
3466 * free_workqueue_attrs - free a workqueue_attrs
3467 * @attrs: workqueue_attrs to free
3469 * Undo alloc_workqueue_attrs().
3471 void free_workqueue_attrs(struct workqueue_attrs
*attrs
)
3474 free_cpumask_var(attrs
->cpumask
);
3480 * alloc_workqueue_attrs - allocate a workqueue_attrs
3481 * @gfp_mask: allocation mask to use
3483 * Allocate a new workqueue_attrs, initialize with default settings and
3484 * return it. Returns NULL on failure.
3486 struct workqueue_attrs
*alloc_workqueue_attrs(gfp_t gfp_mask
)
3488 struct workqueue_attrs
*attrs
;
3490 attrs
= kzalloc(sizeof(*attrs
), gfp_mask
);
3493 if (!alloc_cpumask_var(&attrs
->cpumask
, gfp_mask
))
3496 cpumask_copy(attrs
->cpumask
, cpu_possible_mask
);
3499 free_workqueue_attrs(attrs
);
3503 static void copy_workqueue_attrs(struct workqueue_attrs
*to
,
3504 const struct workqueue_attrs
*from
)
3506 to
->nice
= from
->nice
;
3507 cpumask_copy(to
->cpumask
, from
->cpumask
);
3509 * Unlike hash and equality test, this function doesn't ignore
3510 * ->no_numa as it is used for both pool and wq attrs. Instead,
3511 * get_unbound_pool() explicitly clears ->no_numa after copying.
3513 to
->no_numa
= from
->no_numa
;
3516 /* hash value of the content of @attr */
3517 static u32
wqattrs_hash(const struct workqueue_attrs
*attrs
)
3521 hash
= jhash_1word(attrs
->nice
, hash
);
3522 hash
= jhash(cpumask_bits(attrs
->cpumask
),
3523 BITS_TO_LONGS(nr_cpumask_bits
) * sizeof(long), hash
);
3527 /* content equality test */
3528 static bool wqattrs_equal(const struct workqueue_attrs
*a
,
3529 const struct workqueue_attrs
*b
)
3531 if (a
->nice
!= b
->nice
)
3533 if (!cpumask_equal(a
->cpumask
, b
->cpumask
))
3539 * init_worker_pool - initialize a newly zalloc'd worker_pool
3540 * @pool: worker_pool to initialize
3542 * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
3543 * Returns 0 on success, -errno on failure. Even on failure, all fields
3544 * inside @pool proper are initialized and put_unbound_pool() can be called
3545 * on @pool safely to release it.
3547 static int init_worker_pool(struct worker_pool
*pool
)
3549 spin_lock_init(&pool
->lock
);
3552 pool
->node
= NUMA_NO_NODE
;
3553 pool
->flags
|= POOL_DISASSOCIATED
;
3554 INIT_LIST_HEAD(&pool
->worklist
);
3555 INIT_LIST_HEAD(&pool
->idle_list
);
3556 hash_init(pool
->busy_hash
);
3558 init_timer_deferrable(&pool
->idle_timer
);
3559 pool
->idle_timer
.function
= idle_worker_timeout
;
3560 pool
->idle_timer
.data
= (unsigned long)pool
;
3562 setup_timer(&pool
->mayday_timer
, pool_mayday_timeout
,
3563 (unsigned long)pool
);
3565 mutex_init(&pool
->manager_arb
);
3566 mutex_init(&pool
->manager_mutex
);
3567 idr_init(&pool
->worker_idr
);
3569 INIT_HLIST_NODE(&pool
->hash_node
);
3572 /* shouldn't fail above this point */
3573 pool
->attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3579 static void rcu_free_pool(struct rcu_head
*rcu
)
3581 struct worker_pool
*pool
= container_of(rcu
, struct worker_pool
, rcu
);
3583 idr_destroy(&pool
->worker_idr
);
3584 free_workqueue_attrs(pool
->attrs
);
3589 * put_unbound_pool - put a worker_pool
3590 * @pool: worker_pool to put
3592 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
3593 * safe manner. get_unbound_pool() calls this function on its failure path
3594 * and this function should be able to release pools which went through,
3595 * successfully or not, init_worker_pool().
3597 * Should be called with wq_pool_mutex held.
3599 static void put_unbound_pool(struct worker_pool
*pool
)
3601 struct worker
*worker
;
3603 lockdep_assert_held(&wq_pool_mutex
);
3609 if (WARN_ON(!(pool
->flags
& POOL_DISASSOCIATED
)) ||
3610 WARN_ON(!list_empty(&pool
->worklist
)))
3613 /* release id and unhash */
3615 idr_remove(&worker_pool_idr
, pool
->id
);
3616 hash_del(&pool
->hash_node
);
3619 * Become the manager and destroy all workers. Grabbing
3620 * manager_arb prevents @pool's workers from blocking on
3623 mutex_lock(&pool
->manager_arb
);
3624 mutex_lock(&pool
->manager_mutex
);
3625 spin_lock_irq(&pool
->lock
);
3627 while ((worker
= first_worker(pool
)))
3628 destroy_worker(worker
);
3629 WARN_ON(pool
->nr_workers
|| pool
->nr_idle
);
3631 spin_unlock_irq(&pool
->lock
);
3632 mutex_unlock(&pool
->manager_mutex
);
3633 mutex_unlock(&pool
->manager_arb
);
3635 /* shut down the timers */
3636 del_timer_sync(&pool
->idle_timer
);
3637 del_timer_sync(&pool
->mayday_timer
);
3639 /* sched-RCU protected to allow dereferences from get_work_pool() */
3640 call_rcu_sched(&pool
->rcu
, rcu_free_pool
);
3644 * get_unbound_pool - get a worker_pool with the specified attributes
3645 * @attrs: the attributes of the worker_pool to get
3647 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3648 * reference count and return it. If there already is a matching
3649 * worker_pool, it will be used; otherwise, this function attempts to
3650 * create a new one. On failure, returns NULL.
3652 * Should be called with wq_pool_mutex held.
3654 static struct worker_pool
*get_unbound_pool(const struct workqueue_attrs
*attrs
)
3656 u32 hash
= wqattrs_hash(attrs
);
3657 struct worker_pool
*pool
;
3660 lockdep_assert_held(&wq_pool_mutex
);
3662 /* do we already have a matching pool? */
3663 hash_for_each_possible(unbound_pool_hash
, pool
, hash_node
, hash
) {
3664 if (wqattrs_equal(pool
->attrs
, attrs
)) {
3670 /* nope, create a new one */
3671 pool
= kzalloc(sizeof(*pool
), GFP_KERNEL
);
3672 if (!pool
|| init_worker_pool(pool
) < 0)
3675 if (workqueue_freezing
)
3676 pool
->flags
|= POOL_FREEZING
;
3678 lockdep_set_subclass(&pool
->lock
, 1); /* see put_pwq() */
3679 copy_workqueue_attrs(pool
->attrs
, attrs
);
3682 * no_numa isn't a worker_pool attribute, always clear it. See
3683 * 'struct workqueue_attrs' comments for detail.
3685 pool
->attrs
->no_numa
= false;
3687 /* if cpumask is contained inside a NUMA node, we belong to that node */
3688 if (wq_numa_enabled
) {
3689 for_each_node(node
) {
3690 if (cpumask_subset(pool
->attrs
->cpumask
,
3691 wq_numa_possible_cpumask
[node
])) {
3698 if (worker_pool_assign_id(pool
) < 0)
3701 /* create and start the initial worker */
3702 if (create_and_start_worker(pool
) < 0)
3706 hash_add(unbound_pool_hash
, &pool
->hash_node
, hash
);
3711 put_unbound_pool(pool
);
3715 static void rcu_free_pwq(struct rcu_head
*rcu
)
3717 kmem_cache_free(pwq_cache
,
3718 container_of(rcu
, struct pool_workqueue
, rcu
));
3722 * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3723 * and needs to be destroyed.
3725 static void pwq_unbound_release_workfn(struct work_struct
*work
)
3727 struct pool_workqueue
*pwq
= container_of(work
, struct pool_workqueue
,
3728 unbound_release_work
);
3729 struct workqueue_struct
*wq
= pwq
->wq
;
3730 struct worker_pool
*pool
= pwq
->pool
;
3733 if (WARN_ON_ONCE(!(wq
->flags
& WQ_UNBOUND
)))
3737 * Unlink @pwq. Synchronization against wq->mutex isn't strictly
3738 * necessary on release but do it anyway. It's easier to verify
3739 * and consistent with the linking path.
3741 mutex_lock(&wq
->mutex
);
3742 list_del_rcu(&pwq
->pwqs_node
);
3743 is_last
= list_empty(&wq
->pwqs
);
3744 mutex_unlock(&wq
->mutex
);
3746 mutex_lock(&wq_pool_mutex
);
3747 put_unbound_pool(pool
);
3748 mutex_unlock(&wq_pool_mutex
);
3750 call_rcu_sched(&pwq
->rcu
, rcu_free_pwq
);
3753 * If we're the last pwq going away, @wq is already dead and no one
3754 * is gonna access it anymore. Free it.
3757 free_workqueue_attrs(wq
->unbound_attrs
);
3763 * pwq_adjust_max_active - update a pwq's max_active to the current setting
3764 * @pwq: target pool_workqueue
3766 * If @pwq isn't freezing, set @pwq->max_active to the associated
3767 * workqueue's saved_max_active and activate delayed work items
3768 * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
3770 static void pwq_adjust_max_active(struct pool_workqueue
*pwq
)
3772 struct workqueue_struct
*wq
= pwq
->wq
;
3773 bool freezable
= wq
->flags
& WQ_FREEZABLE
;
3775 /* for @wq->saved_max_active */
3776 lockdep_assert_held(&wq
->mutex
);
3778 /* fast exit for non-freezable wqs */
3779 if (!freezable
&& pwq
->max_active
== wq
->saved_max_active
)
3782 spin_lock_irq(&pwq
->pool
->lock
);
3784 if (!freezable
|| !(pwq
->pool
->flags
& POOL_FREEZING
)) {
3785 pwq
->max_active
= wq
->saved_max_active
;
3787 while (!list_empty(&pwq
->delayed_works
) &&
3788 pwq
->nr_active
< pwq
->max_active
)
3789 pwq_activate_first_delayed(pwq
);
3792 * Need to kick a worker after thawed or an unbound wq's
3793 * max_active is bumped. It's a slow path. Do it always.
3795 wake_up_worker(pwq
->pool
);
3797 pwq
->max_active
= 0;
3800 spin_unlock_irq(&pwq
->pool
->lock
);
3803 /* initialize newly alloced @pwq which is associated with @wq and @pool */
3804 static void init_pwq(struct pool_workqueue
*pwq
, struct workqueue_struct
*wq
,
3805 struct worker_pool
*pool
)
3807 BUG_ON((unsigned long)pwq
& WORK_STRUCT_FLAG_MASK
);
3809 memset(pwq
, 0, sizeof(*pwq
));
3813 pwq
->flush_color
= -1;
3815 INIT_LIST_HEAD(&pwq
->delayed_works
);
3816 INIT_LIST_HEAD(&pwq
->pwqs_node
);
3817 INIT_LIST_HEAD(&pwq
->mayday_node
);
3818 INIT_WORK(&pwq
->unbound_release_work
, pwq_unbound_release_workfn
);
3821 /* sync @pwq with the current state of its associated wq and link it */
3822 static void link_pwq(struct pool_workqueue
*pwq
)
3824 struct workqueue_struct
*wq
= pwq
->wq
;
3826 lockdep_assert_held(&wq
->mutex
);
3828 /* may be called multiple times, ignore if already linked */
3829 if (!list_empty(&pwq
->pwqs_node
))
3833 * Set the matching work_color. This is synchronized with
3834 * wq->mutex to avoid confusing flush_workqueue().
3836 pwq
->work_color
= wq
->work_color
;
3838 /* sync max_active to the current setting */
3839 pwq_adjust_max_active(pwq
);
3842 list_add_rcu(&pwq
->pwqs_node
, &wq
->pwqs
);
3845 /* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3846 static struct pool_workqueue
*alloc_unbound_pwq(struct workqueue_struct
*wq
,
3847 const struct workqueue_attrs
*attrs
)
3849 struct worker_pool
*pool
;
3850 struct pool_workqueue
*pwq
;
3852 lockdep_assert_held(&wq_pool_mutex
);
3854 pool
= get_unbound_pool(attrs
);
3858 pwq
= kmem_cache_alloc_node(pwq_cache
, GFP_KERNEL
, pool
->node
);
3860 put_unbound_pool(pool
);
3864 init_pwq(pwq
, wq
, pool
);
3868 /* undo alloc_unbound_pwq(), used only in the error path */
3869 static void free_unbound_pwq(struct pool_workqueue
*pwq
)
3871 lockdep_assert_held(&wq_pool_mutex
);
3874 put_unbound_pool(pwq
->pool
);
3875 kmem_cache_free(pwq_cache
, pwq
);
3880 * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node
3881 * @attrs: the wq_attrs of interest
3882 * @node: the target NUMA node
3883 * @cpu_going_down: if >= 0, the CPU to consider as offline
3884 * @cpumask: outarg, the resulting cpumask
3886 * Calculate the cpumask a workqueue with @attrs should use on @node. If
3887 * @cpu_going_down is >= 0, that cpu is considered offline during
3888 * calculation. The result is stored in @cpumask. This function returns
3889 * %true if the resulting @cpumask is different from @attrs->cpumask,
3892 * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3893 * enabled and @node has online CPUs requested by @attrs, the returned
3894 * cpumask is the intersection of the possible CPUs of @node and
3897 * The caller is responsible for ensuring that the cpumask of @node stays
3900 static bool wq_calc_node_cpumask(const struct workqueue_attrs
*attrs
, int node
,
3901 int cpu_going_down
, cpumask_t
*cpumask
)
3903 if (!wq_numa_enabled
|| attrs
->no_numa
)
3906 /* does @node have any online CPUs @attrs wants? */
3907 cpumask_and(cpumask
, cpumask_of_node(node
), attrs
->cpumask
);
3908 if (cpu_going_down
>= 0)
3909 cpumask_clear_cpu(cpu_going_down
, cpumask
);
3911 if (cpumask_empty(cpumask
))
3914 /* yeap, return possible CPUs in @node that @attrs wants */
3915 cpumask_and(cpumask
, attrs
->cpumask
, wq_numa_possible_cpumask
[node
]);
3916 return !cpumask_equal(cpumask
, attrs
->cpumask
);
3919 cpumask_copy(cpumask
, attrs
->cpumask
);
3923 /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3924 static struct pool_workqueue
*numa_pwq_tbl_install(struct workqueue_struct
*wq
,
3926 struct pool_workqueue
*pwq
)
3928 struct pool_workqueue
*old_pwq
;
3930 lockdep_assert_held(&wq
->mutex
);
3932 /* link_pwq() can handle duplicate calls */
3935 old_pwq
= rcu_access_pointer(wq
->numa_pwq_tbl
[node
]);
3936 rcu_assign_pointer(wq
->numa_pwq_tbl
[node
], pwq
);
3941 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
3942 * @wq: the target workqueue
3943 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
3945 * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
3946 * machines, this function maps a separate pwq to each NUMA node with
3947 * possibles CPUs in @attrs->cpumask so that work items are affine to the
3948 * NUMA node it was issued on. Older pwqs are released as in-flight work
3949 * items finish. Note that a work item which repeatedly requeues itself
3950 * back-to-back will stay on its current pwq.
3952 * Performs GFP_KERNEL allocations. Returns 0 on success and -errno on
3955 int apply_workqueue_attrs(struct workqueue_struct
*wq
,
3956 const struct workqueue_attrs
*attrs
)
3958 struct workqueue_attrs
*new_attrs
, *tmp_attrs
;
3959 struct pool_workqueue
**pwq_tbl
, *dfl_pwq
;
3962 /* only unbound workqueues can change attributes */
3963 if (WARN_ON(!(wq
->flags
& WQ_UNBOUND
)))
3966 /* creating multiple pwqs breaks ordering guarantee */
3967 if (!list_empty(&wq
->pwqs
)) {
3968 if (WARN_ON(wq
->flags
& __WQ_ORDERED_EXPLICIT
))
3971 wq
->flags
&= ~__WQ_ORDERED
;
3974 pwq_tbl
= kzalloc(wq_numa_tbl_len
* sizeof(pwq_tbl
[0]), GFP_KERNEL
);
3975 new_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3976 tmp_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3977 if (!pwq_tbl
|| !new_attrs
|| !tmp_attrs
)
3980 /* make a copy of @attrs and sanitize it */
3981 copy_workqueue_attrs(new_attrs
, attrs
);
3982 cpumask_and(new_attrs
->cpumask
, new_attrs
->cpumask
, cpu_possible_mask
);
3985 * We may create multiple pwqs with differing cpumasks. Make a
3986 * copy of @new_attrs which will be modified and used to obtain
3989 copy_workqueue_attrs(tmp_attrs
, new_attrs
);
3992 * CPUs should stay stable across pwq creations and installations.
3993 * Pin CPUs, determine the target cpumask for each node and create
3998 mutex_lock(&wq_pool_mutex
);
4001 * If something goes wrong during CPU up/down, we'll fall back to
4002 * the default pwq covering whole @attrs->cpumask. Always create
4003 * it even if we don't use it immediately.
4005 dfl_pwq
= alloc_unbound_pwq(wq
, new_attrs
);
4009 for_each_node(node
) {
4010 if (wq_calc_node_cpumask(attrs
, node
, -1, tmp_attrs
->cpumask
)) {
4011 pwq_tbl
[node
] = alloc_unbound_pwq(wq
, tmp_attrs
);
4016 pwq_tbl
[node
] = dfl_pwq
;
4020 mutex_unlock(&wq_pool_mutex
);
4022 /* all pwqs have been created successfully, let's install'em */
4023 mutex_lock(&wq
->mutex
);
4025 copy_workqueue_attrs(wq
->unbound_attrs
, new_attrs
);
4027 /* save the previous pwq and install the new one */
4029 pwq_tbl
[node
] = numa_pwq_tbl_install(wq
, node
, pwq_tbl
[node
]);
4031 /* @dfl_pwq might not have been used, ensure it's linked */
4033 swap(wq
->dfl_pwq
, dfl_pwq
);
4035 mutex_unlock(&wq
->mutex
);
4037 /* put the old pwqs */
4039 put_pwq_unlocked(pwq_tbl
[node
]);
4040 put_pwq_unlocked(dfl_pwq
);
4046 free_workqueue_attrs(tmp_attrs
);
4047 free_workqueue_attrs(new_attrs
);
4052 free_unbound_pwq(dfl_pwq
);
4054 if (pwq_tbl
&& pwq_tbl
[node
] != dfl_pwq
)
4055 free_unbound_pwq(pwq_tbl
[node
]);
4056 mutex_unlock(&wq_pool_mutex
);
4064 * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
4065 * @wq: the target workqueue
4066 * @cpu: the CPU coming up or going down
4067 * @online: whether @cpu is coming up or going down
4069 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
4070 * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
4073 * If NUMA affinity can't be adjusted due to memory allocation failure, it
4074 * falls back to @wq->dfl_pwq which may not be optimal but is always
4077 * Note that when the last allowed CPU of a NUMA node goes offline for a
4078 * workqueue with a cpumask spanning multiple nodes, the workers which were
4079 * already executing the work items for the workqueue will lose their CPU
4080 * affinity and may execute on any CPU. This is similar to how per-cpu
4081 * workqueues behave on CPU_DOWN. If a workqueue user wants strict
4082 * affinity, it's the user's responsibility to flush the work item from
4085 static void wq_update_unbound_numa(struct workqueue_struct
*wq
, int cpu
,
4088 int node
= cpu_to_node(cpu
);
4089 int cpu_off
= online
? -1 : cpu
;
4090 struct pool_workqueue
*old_pwq
= NULL
, *pwq
;
4091 struct workqueue_attrs
*target_attrs
;
4094 lockdep_assert_held(&wq_pool_mutex
);
4096 if (!wq_numa_enabled
|| !(wq
->flags
& WQ_UNBOUND
))
4100 * We don't wanna alloc/free wq_attrs for each wq for each CPU.
4101 * Let's use a preallocated one. The following buf is protected by
4102 * CPU hotplug exclusion.
4104 target_attrs
= wq_update_unbound_numa_attrs_buf
;
4105 cpumask
= target_attrs
->cpumask
;
4107 mutex_lock(&wq
->mutex
);
4108 if (wq
->unbound_attrs
->no_numa
)
4111 copy_workqueue_attrs(target_attrs
, wq
->unbound_attrs
);
4112 pwq
= unbound_pwq_by_node(wq
, node
);
4115 * Let's determine what needs to be done. If the target cpumask is
4116 * different from wq's, we need to compare it to @pwq's and create
4117 * a new one if they don't match. If the target cpumask equals
4118 * wq's, the default pwq should be used. If @pwq is already the
4119 * default one, nothing to do; otherwise, install the default one.
4121 if (wq_calc_node_cpumask(wq
->unbound_attrs
, node
, cpu_off
, cpumask
)) {
4122 if (cpumask_equal(cpumask
, pwq
->pool
->attrs
->cpumask
))
4125 if (pwq
== wq
->dfl_pwq
)
4131 mutex_unlock(&wq
->mutex
);
4133 /* create a new pwq */
4134 pwq
= alloc_unbound_pwq(wq
, target_attrs
);
4136 pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
4138 mutex_lock(&wq
->mutex
);
4143 * Install the new pwq. As this function is called only from CPU
4144 * hotplug callbacks and applying a new attrs is wrapped with
4145 * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
4148 mutex_lock(&wq
->mutex
);
4149 old_pwq
= numa_pwq_tbl_install(wq
, node
, pwq
);
4153 spin_lock_irq(&wq
->dfl_pwq
->pool
->lock
);
4154 get_pwq(wq
->dfl_pwq
);
4155 spin_unlock_irq(&wq
->dfl_pwq
->pool
->lock
);
4156 old_pwq
= numa_pwq_tbl_install(wq
, node
, wq
->dfl_pwq
);
4158 mutex_unlock(&wq
->mutex
);
4159 put_pwq_unlocked(old_pwq
);
4162 static int alloc_and_link_pwqs(struct workqueue_struct
*wq
)
4164 bool highpri
= wq
->flags
& WQ_HIGHPRI
;
4167 if (!(wq
->flags
& WQ_UNBOUND
)) {
4168 wq
->cpu_pwqs
= alloc_percpu(struct pool_workqueue
);
4172 for_each_possible_cpu(cpu
) {
4173 struct pool_workqueue
*pwq
=
4174 per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
4175 struct worker_pool
*cpu_pools
=
4176 per_cpu(cpu_worker_pools
, cpu
);
4178 init_pwq(pwq
, wq
, &cpu_pools
[highpri
]);
4180 mutex_lock(&wq
->mutex
);
4182 mutex_unlock(&wq
->mutex
);
4185 } else if (wq
->flags
& __WQ_ORDERED
) {
4186 ret
= apply_workqueue_attrs(wq
, ordered_wq_attrs
[highpri
]);
4187 /* there should only be single pwq for ordering guarantee */
4188 WARN(!ret
&& (wq
->pwqs
.next
!= &wq
->dfl_pwq
->pwqs_node
||
4189 wq
->pwqs
.prev
!= &wq
->dfl_pwq
->pwqs_node
),
4190 "ordering guarantee broken for workqueue %s\n", wq
->name
);
4193 return apply_workqueue_attrs(wq
, unbound_std_wq_attrs
[highpri
]);
4197 static int wq_clamp_max_active(int max_active
, unsigned int flags
,
4200 int lim
= flags
& WQ_UNBOUND
? WQ_UNBOUND_MAX_ACTIVE
: WQ_MAX_ACTIVE
;
4202 if (max_active
< 1 || max_active
> lim
)
4203 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
4204 max_active
, name
, 1, lim
);
4206 return clamp_val(max_active
, 1, lim
);
4209 struct workqueue_struct
*__alloc_workqueue_key(const char *fmt
,
4212 struct lock_class_key
*key
,
4213 const char *lock_name
, ...)
4215 size_t tbl_size
= 0;
4217 struct workqueue_struct
*wq
;
4218 struct pool_workqueue
*pwq
;
4221 * Unbound && max_active == 1 used to imply ordered, which is no
4222 * longer the case on NUMA machines due to per-node pools. While
4223 * alloc_ordered_workqueue() is the right way to create an ordered
4224 * workqueue, keep the previous behavior to avoid subtle breakages
4227 if ((flags
& WQ_UNBOUND
) && max_active
== 1)
4228 flags
|= __WQ_ORDERED
;
4230 /* allocate wq and format name */
4231 if (flags
& WQ_UNBOUND
)
4232 tbl_size
= wq_numa_tbl_len
* sizeof(wq
->numa_pwq_tbl
[0]);
4234 wq
= kzalloc(sizeof(*wq
) + tbl_size
, GFP_KERNEL
);
4238 if (flags
& WQ_UNBOUND
) {
4239 wq
->unbound_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
4240 if (!wq
->unbound_attrs
)
4244 va_start(args
, lock_name
);
4245 vsnprintf(wq
->name
, sizeof(wq
->name
), fmt
, args
);
4248 max_active
= max_active
?: WQ_DFL_ACTIVE
;
4249 max_active
= wq_clamp_max_active(max_active
, flags
, wq
->name
);
4253 wq
->saved_max_active
= max_active
;
4254 mutex_init(&wq
->mutex
);
4255 atomic_set(&wq
->nr_pwqs_to_flush
, 0);
4256 INIT_LIST_HEAD(&wq
->pwqs
);
4257 INIT_LIST_HEAD(&wq
->flusher_queue
);
4258 INIT_LIST_HEAD(&wq
->flusher_overflow
);
4259 INIT_LIST_HEAD(&wq
->maydays
);
4261 lockdep_init_map(&wq
->lockdep_map
, lock_name
, key
, 0);
4262 INIT_LIST_HEAD(&wq
->list
);
4264 if (alloc_and_link_pwqs(wq
) < 0)
4268 * Workqueues which may be used during memory reclaim should
4269 * have a rescuer to guarantee forward progress.
4271 if (flags
& WQ_MEM_RECLAIM
) {
4272 struct worker
*rescuer
;
4274 rescuer
= alloc_worker();
4278 rescuer
->rescue_wq
= wq
;
4279 rescuer
->task
= kthread_create(rescuer_thread
, rescuer
, "%s",
4281 if (IS_ERR(rescuer
->task
)) {
4286 wq
->rescuer
= rescuer
;
4287 rescuer
->task
->flags
|= PF_NO_SETAFFINITY
;
4288 wake_up_process(rescuer
->task
);
4291 if ((wq
->flags
& WQ_SYSFS
) && workqueue_sysfs_register(wq
))
4295 * wq_pool_mutex protects global freeze state and workqueues list.
4296 * Grab it, adjust max_active and add the new @wq to workqueues
4299 mutex_lock(&wq_pool_mutex
);
4301 mutex_lock(&wq
->mutex
);
4302 for_each_pwq(pwq
, wq
)
4303 pwq_adjust_max_active(pwq
);
4304 mutex_unlock(&wq
->mutex
);
4306 list_add(&wq
->list
, &workqueues
);
4308 mutex_unlock(&wq_pool_mutex
);
4313 free_workqueue_attrs(wq
->unbound_attrs
);
4317 destroy_workqueue(wq
);
4320 EXPORT_SYMBOL_GPL(__alloc_workqueue_key
);
4323 * destroy_workqueue - safely terminate a workqueue
4324 * @wq: target workqueue
4326 * Safely destroy a workqueue. All work currently pending will be done first.
4328 void destroy_workqueue(struct workqueue_struct
*wq
)
4330 struct pool_workqueue
*pwq
;
4333 /* drain it before proceeding with destruction */
4334 drain_workqueue(wq
);
4337 mutex_lock(&wq
->mutex
);
4338 for_each_pwq(pwq
, wq
) {
4341 for (i
= 0; i
< WORK_NR_COLORS
; i
++) {
4342 if (WARN_ON(pwq
->nr_in_flight
[i
])) {
4343 mutex_unlock(&wq
->mutex
);
4348 if (WARN_ON((pwq
!= wq
->dfl_pwq
) && (pwq
->refcnt
> 1)) ||
4349 WARN_ON(pwq
->nr_active
) ||
4350 WARN_ON(!list_empty(&pwq
->delayed_works
))) {
4351 mutex_unlock(&wq
->mutex
);
4355 mutex_unlock(&wq
->mutex
);
4358 * wq list is used to freeze wq, remove from list after
4359 * flushing is complete in case freeze races us.
4361 mutex_lock(&wq_pool_mutex
);
4362 list_del_init(&wq
->list
);
4363 mutex_unlock(&wq_pool_mutex
);
4365 workqueue_sysfs_unregister(wq
);
4368 kthread_stop(wq
->rescuer
->task
);
4373 if (!(wq
->flags
& WQ_UNBOUND
)) {
4375 * The base ref is never dropped on per-cpu pwqs. Directly
4376 * free the pwqs and wq.
4378 free_percpu(wq
->cpu_pwqs
);
4382 * We're the sole accessor of @wq at this point. Directly
4383 * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
4384 * @wq will be freed when the last pwq is released.
4386 for_each_node(node
) {
4387 pwq
= rcu_access_pointer(wq
->numa_pwq_tbl
[node
]);
4388 RCU_INIT_POINTER(wq
->numa_pwq_tbl
[node
], NULL
);
4389 put_pwq_unlocked(pwq
);
4393 * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
4394 * put. Don't access it afterwards.
4398 put_pwq_unlocked(pwq
);
4401 EXPORT_SYMBOL_GPL(destroy_workqueue
);
4404 * workqueue_set_max_active - adjust max_active of a workqueue
4405 * @wq: target workqueue
4406 * @max_active: new max_active value.
4408 * Set max_active of @wq to @max_active.
4411 * Don't call from IRQ context.
4413 void workqueue_set_max_active(struct workqueue_struct
*wq
, int max_active
)
4415 struct pool_workqueue
*pwq
;
4417 /* disallow meddling with max_active for ordered workqueues */
4418 if (WARN_ON(wq
->flags
& __WQ_ORDERED_EXPLICIT
))
4421 max_active
= wq_clamp_max_active(max_active
, wq
->flags
, wq
->name
);
4423 mutex_lock(&wq
->mutex
);
4425 wq
->flags
&= ~__WQ_ORDERED
;
4426 wq
->saved_max_active
= max_active
;
4428 for_each_pwq(pwq
, wq
)
4429 pwq_adjust_max_active(pwq
);
4431 mutex_unlock(&wq
->mutex
);
4433 EXPORT_SYMBOL_GPL(workqueue_set_max_active
);
4436 * current_is_workqueue_rescuer - is %current workqueue rescuer?
4438 * Determine whether %current is a workqueue rescuer. Can be used from
4439 * work functions to determine whether it's being run off the rescuer task.
4441 bool current_is_workqueue_rescuer(void)
4443 struct worker
*worker
= current_wq_worker();
4445 return worker
&& worker
->rescue_wq
;
4449 * workqueue_congested - test whether a workqueue is congested
4450 * @cpu: CPU in question
4451 * @wq: target workqueue
4453 * Test whether @wq's cpu workqueue for @cpu is congested. There is
4454 * no synchronization around this function and the test result is
4455 * unreliable and only useful as advisory hints or for debugging.
4457 * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
4458 * Note that both per-cpu and unbound workqueues may be associated with
4459 * multiple pool_workqueues which have separate congested states. A
4460 * workqueue being congested on one CPU doesn't mean the workqueue is also
4461 * contested on other CPUs / NUMA nodes.
4464 * %true if congested, %false otherwise.
4466 bool workqueue_congested(int cpu
, struct workqueue_struct
*wq
)
4468 struct pool_workqueue
*pwq
;
4471 rcu_read_lock_sched();
4473 if (cpu
== WORK_CPU_UNBOUND
)
4474 cpu
= smp_processor_id();
4476 if (!(wq
->flags
& WQ_UNBOUND
))
4477 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
4479 pwq
= unbound_pwq_by_node(wq
, cpu_to_node(cpu
));
4481 ret
= !list_empty(&pwq
->delayed_works
);
4482 rcu_read_unlock_sched();
4486 EXPORT_SYMBOL_GPL(workqueue_congested
);
4489 * work_busy - test whether a work is currently pending or running
4490 * @work: the work to be tested
4492 * Test whether @work is currently pending or running. There is no
4493 * synchronization around this function and the test result is
4494 * unreliable and only useful as advisory hints or for debugging.
4497 * OR'd bitmask of WORK_BUSY_* bits.
4499 unsigned int work_busy(struct work_struct
*work
)
4501 struct worker_pool
*pool
;
4502 unsigned long flags
;
4503 unsigned int ret
= 0;
4505 if (work_pending(work
))
4506 ret
|= WORK_BUSY_PENDING
;
4508 local_irq_save(flags
);
4509 pool
= get_work_pool(work
);
4511 spin_lock(&pool
->lock
);
4512 if (find_worker_executing_work(pool
, work
))
4513 ret
|= WORK_BUSY_RUNNING
;
4514 spin_unlock(&pool
->lock
);
4516 local_irq_restore(flags
);
4520 EXPORT_SYMBOL_GPL(work_busy
);
4523 * set_worker_desc - set description for the current work item
4524 * @fmt: printf-style format string
4525 * @...: arguments for the format string
4527 * This function can be called by a running work function to describe what
4528 * the work item is about. If the worker task gets dumped, this
4529 * information will be printed out together to help debugging. The
4530 * description can be at most WORKER_DESC_LEN including the trailing '\0'.
4532 void set_worker_desc(const char *fmt
, ...)
4534 struct worker
*worker
= current_wq_worker();
4538 va_start(args
, fmt
);
4539 vsnprintf(worker
->desc
, sizeof(worker
->desc
), fmt
, args
);
4541 worker
->desc_valid
= true;
4546 * print_worker_info - print out worker information and description
4547 * @log_lvl: the log level to use when printing
4548 * @task: target task
4550 * If @task is a worker and currently executing a work item, print out the
4551 * name of the workqueue being serviced and worker description set with
4552 * set_worker_desc() by the currently executing work item.
4554 * This function can be safely called on any task as long as the
4555 * task_struct itself is accessible. While safe, this function isn't
4556 * synchronized and may print out mixups or garbages of limited length.
4558 void print_worker_info(const char *log_lvl
, struct task_struct
*task
)
4560 work_func_t
*fn
= NULL
;
4561 char name
[WQ_NAME_LEN
] = { };
4562 char desc
[WORKER_DESC_LEN
] = { };
4563 struct pool_workqueue
*pwq
= NULL
;
4564 struct workqueue_struct
*wq
= NULL
;
4565 bool desc_valid
= false;
4566 struct worker
*worker
;
4568 if (!(task
->flags
& PF_WQ_WORKER
))
4572 * This function is called without any synchronization and @task
4573 * could be in any state. Be careful with dereferences.
4575 worker
= probe_kthread_data(task
);
4578 * Carefully copy the associated workqueue's workfn and name. Keep
4579 * the original last '\0' in case the original contains garbage.
4581 probe_kernel_read(&fn
, &worker
->current_func
, sizeof(fn
));
4582 probe_kernel_read(&pwq
, &worker
->current_pwq
, sizeof(pwq
));
4583 probe_kernel_read(&wq
, &pwq
->wq
, sizeof(wq
));
4584 probe_kernel_read(name
, wq
->name
, sizeof(name
) - 1);
4586 /* copy worker description */
4587 probe_kernel_read(&desc_valid
, &worker
->desc_valid
, sizeof(desc_valid
));
4589 probe_kernel_read(desc
, worker
->desc
, sizeof(desc
) - 1);
4591 if (fn
|| name
[0] || desc
[0]) {
4592 printk("%sWorkqueue: %s %pf", log_lvl
, name
, fn
);
4594 pr_cont(" (%s)", desc
);
4602 * There are two challenges in supporting CPU hotplug. Firstly, there
4603 * are a lot of assumptions on strong associations among work, pwq and
4604 * pool which make migrating pending and scheduled works very
4605 * difficult to implement without impacting hot paths. Secondly,
4606 * worker pools serve mix of short, long and very long running works making
4607 * blocked draining impractical.
4609 * This is solved by allowing the pools to be disassociated from the CPU
4610 * running as an unbound one and allowing it to be reattached later if the
4611 * cpu comes back online.
4614 static void wq_unbind_fn(struct work_struct
*work
)
4616 int cpu
= smp_processor_id();
4617 struct worker_pool
*pool
;
4618 struct worker
*worker
;
4621 for_each_cpu_worker_pool(pool
, cpu
) {
4622 WARN_ON_ONCE(cpu
!= smp_processor_id());
4624 mutex_lock(&pool
->manager_mutex
);
4625 spin_lock_irq(&pool
->lock
);
4628 * We've blocked all manager operations. Make all workers
4629 * unbound and set DISASSOCIATED. Before this, all workers
4630 * except for the ones which are still executing works from
4631 * before the last CPU down must be on the cpu. After
4632 * this, they may become diasporas.
4634 for_each_pool_worker(worker
, wi
, pool
)
4635 worker
->flags
|= WORKER_UNBOUND
;
4637 pool
->flags
|= POOL_DISASSOCIATED
;
4639 spin_unlock_irq(&pool
->lock
);
4640 mutex_unlock(&pool
->manager_mutex
);
4643 * Call schedule() so that we cross rq->lock and thus can
4644 * guarantee sched callbacks see the %WORKER_UNBOUND flag.
4645 * This is necessary as scheduler callbacks may be invoked
4651 * Sched callbacks are disabled now. Zap nr_running.
4652 * After this, nr_running stays zero and need_more_worker()
4653 * and keep_working() are always true as long as the
4654 * worklist is not empty. This pool now behaves as an
4655 * unbound (in terms of concurrency management) pool which
4656 * are served by workers tied to the pool.
4658 atomic_set(&pool
->nr_running
, 0);
4661 * With concurrency management just turned off, a busy
4662 * worker blocking could lead to lengthy stalls. Kick off
4663 * unbound chain execution of currently pending work items.
4665 spin_lock_irq(&pool
->lock
);
4666 wake_up_worker(pool
);
4667 spin_unlock_irq(&pool
->lock
);
4672 * rebind_workers - rebind all workers of a pool to the associated CPU
4673 * @pool: pool of interest
4675 * @pool->cpu is coming online. Rebind all workers to the CPU.
4677 static void rebind_workers(struct worker_pool
*pool
)
4679 struct worker
*worker
;
4682 lockdep_assert_held(&pool
->manager_mutex
);
4685 * Restore CPU affinity of all workers. As all idle workers should
4686 * be on the run-queue of the associated CPU before any local
4687 * wake-ups for concurrency management happen, restore CPU affinty
4688 * of all workers first and then clear UNBOUND. As we're called
4689 * from CPU_ONLINE, the following shouldn't fail.
4691 for_each_pool_worker(worker
, wi
, pool
)
4692 WARN_ON_ONCE(set_cpus_allowed_ptr(worker
->task
,
4693 pool
->attrs
->cpumask
) < 0);
4695 spin_lock_irq(&pool
->lock
);
4697 for_each_pool_worker(worker
, wi
, pool
) {
4698 unsigned int worker_flags
= worker
->flags
;
4701 * A bound idle worker should actually be on the runqueue
4702 * of the associated CPU for local wake-ups targeting it to
4703 * work. Kick all idle workers so that they migrate to the
4704 * associated CPU. Doing this in the same loop as
4705 * replacing UNBOUND with REBOUND is safe as no worker will
4706 * be bound before @pool->lock is released.
4708 if (worker_flags
& WORKER_IDLE
)
4709 wake_up_process(worker
->task
);
4712 * We want to clear UNBOUND but can't directly call
4713 * worker_clr_flags() or adjust nr_running. Atomically
4714 * replace UNBOUND with another NOT_RUNNING flag REBOUND.
4715 * @worker will clear REBOUND using worker_clr_flags() when
4716 * it initiates the next execution cycle thus restoring
4717 * concurrency management. Note that when or whether
4718 * @worker clears REBOUND doesn't affect correctness.
4720 * ACCESS_ONCE() is necessary because @worker->flags may be
4721 * tested without holding any lock in
4722 * wq_worker_waking_up(). Without it, NOT_RUNNING test may
4723 * fail incorrectly leading to premature concurrency
4724 * management operations.
4726 WARN_ON_ONCE(!(worker_flags
& WORKER_UNBOUND
));
4727 worker_flags
|= WORKER_REBOUND
;
4728 worker_flags
&= ~WORKER_UNBOUND
;
4729 ACCESS_ONCE(worker
->flags
) = worker_flags
;
4732 spin_unlock_irq(&pool
->lock
);
4736 * restore_unbound_workers_cpumask - restore cpumask of unbound workers
4737 * @pool: unbound pool of interest
4738 * @cpu: the CPU which is coming up
4740 * An unbound pool may end up with a cpumask which doesn't have any online
4741 * CPUs. When a worker of such pool get scheduled, the scheduler resets
4742 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4743 * online CPU before, cpus_allowed of all its workers should be restored.
4745 static void restore_unbound_workers_cpumask(struct worker_pool
*pool
, int cpu
)
4747 static cpumask_t cpumask
;
4748 struct worker
*worker
;
4751 lockdep_assert_held(&pool
->manager_mutex
);
4753 /* is @cpu allowed for @pool? */
4754 if (!cpumask_test_cpu(cpu
, pool
->attrs
->cpumask
))
4757 /* is @cpu the only online CPU? */
4758 cpumask_and(&cpumask
, pool
->attrs
->cpumask
, cpu_online_mask
);
4759 if (cpumask_weight(&cpumask
) != 1)
4762 /* as we're called from CPU_ONLINE, the following shouldn't fail */
4763 for_each_pool_worker(worker
, wi
, pool
)
4764 WARN_ON_ONCE(set_cpus_allowed_ptr(worker
->task
,
4765 pool
->attrs
->cpumask
) < 0);
4769 * Workqueues should be brought up before normal priority CPU notifiers.
4770 * This will be registered high priority CPU notifier.
4772 static int __cpuinit
workqueue_cpu_up_callback(struct notifier_block
*nfb
,
4773 unsigned long action
,
4776 int cpu
= (unsigned long)hcpu
;
4777 struct worker_pool
*pool
;
4778 struct workqueue_struct
*wq
;
4781 switch (action
& ~CPU_TASKS_FROZEN
) {
4782 case CPU_UP_PREPARE
:
4783 for_each_cpu_worker_pool(pool
, cpu
) {
4784 if (pool
->nr_workers
)
4786 if (create_and_start_worker(pool
) < 0)
4791 case CPU_DOWN_FAILED
:
4793 mutex_lock(&wq_pool_mutex
);
4795 for_each_pool(pool
, pi
) {
4796 mutex_lock(&pool
->manager_mutex
);
4798 if (pool
->cpu
== cpu
) {
4799 spin_lock_irq(&pool
->lock
);
4800 pool
->flags
&= ~POOL_DISASSOCIATED
;
4801 spin_unlock_irq(&pool
->lock
);
4803 rebind_workers(pool
);
4804 } else if (pool
->cpu
< 0) {
4805 restore_unbound_workers_cpumask(pool
, cpu
);
4808 mutex_unlock(&pool
->manager_mutex
);
4811 /* update NUMA affinity of unbound workqueues */
4812 list_for_each_entry(wq
, &workqueues
, list
)
4813 wq_update_unbound_numa(wq
, cpu
, true);
4815 mutex_unlock(&wq_pool_mutex
);
4822 * Workqueues should be brought down after normal priority CPU notifiers.
4823 * This will be registered as low priority CPU notifier.
4825 static int __cpuinit
workqueue_cpu_down_callback(struct notifier_block
*nfb
,
4826 unsigned long action
,
4829 int cpu
= (unsigned long)hcpu
;
4830 struct work_struct unbind_work
;
4831 struct workqueue_struct
*wq
;
4833 switch (action
& ~CPU_TASKS_FROZEN
) {
4834 case CPU_DOWN_PREPARE
:
4835 /* unbinding per-cpu workers should happen on the local CPU */
4836 INIT_WORK_ONSTACK(&unbind_work
, wq_unbind_fn
);
4837 queue_work_on(cpu
, system_highpri_wq
, &unbind_work
);
4839 /* update NUMA affinity of unbound workqueues */
4840 mutex_lock(&wq_pool_mutex
);
4841 list_for_each_entry(wq
, &workqueues
, list
)
4842 wq_update_unbound_numa(wq
, cpu
, false);
4843 mutex_unlock(&wq_pool_mutex
);
4845 /* wait for per-cpu unbinding to finish */
4846 flush_work(&unbind_work
);
4854 struct work_for_cpu
{
4855 struct work_struct work
;
4861 static void work_for_cpu_fn(struct work_struct
*work
)
4863 struct work_for_cpu
*wfc
= container_of(work
, struct work_for_cpu
, work
);
4865 wfc
->ret
= wfc
->fn(wfc
->arg
);
4869 * work_on_cpu - run a function in user context on a particular cpu
4870 * @cpu: the cpu to run on
4871 * @fn: the function to run
4872 * @arg: the function arg
4874 * This will return the value @fn returns.
4875 * It is up to the caller to ensure that the cpu doesn't go offline.
4876 * The caller must not hold any locks which would prevent @fn from completing.
4878 long work_on_cpu(int cpu
, long (*fn
)(void *), void *arg
)
4880 struct work_for_cpu wfc
= { .fn
= fn
, .arg
= arg
};
4882 INIT_WORK_ONSTACK(&wfc
.work
, work_for_cpu_fn
);
4883 schedule_work_on(cpu
, &wfc
.work
);
4884 flush_work(&wfc
.work
);
4887 EXPORT_SYMBOL_GPL(work_on_cpu
);
4888 #endif /* CONFIG_SMP */
4890 #ifdef CONFIG_FREEZER
4893 * freeze_workqueues_begin - begin freezing workqueues
4895 * Start freezing workqueues. After this function returns, all freezable
4896 * workqueues will queue new works to their delayed_works list instead of
4900 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4902 void freeze_workqueues_begin(void)
4904 struct worker_pool
*pool
;
4905 struct workqueue_struct
*wq
;
4906 struct pool_workqueue
*pwq
;
4909 mutex_lock(&wq_pool_mutex
);
4911 WARN_ON_ONCE(workqueue_freezing
);
4912 workqueue_freezing
= true;
4915 for_each_pool(pool
, pi
) {
4916 spin_lock_irq(&pool
->lock
);
4917 WARN_ON_ONCE(pool
->flags
& POOL_FREEZING
);
4918 pool
->flags
|= POOL_FREEZING
;
4919 spin_unlock_irq(&pool
->lock
);
4922 list_for_each_entry(wq
, &workqueues
, list
) {
4923 mutex_lock(&wq
->mutex
);
4924 for_each_pwq(pwq
, wq
)
4925 pwq_adjust_max_active(pwq
);
4926 mutex_unlock(&wq
->mutex
);
4929 mutex_unlock(&wq_pool_mutex
);
4933 * freeze_workqueues_busy - are freezable workqueues still busy?
4935 * Check whether freezing is complete. This function must be called
4936 * between freeze_workqueues_begin() and thaw_workqueues().
4939 * Grabs and releases wq_pool_mutex.
4942 * %true if some freezable workqueues are still busy. %false if freezing
4945 bool freeze_workqueues_busy(void)
4948 struct workqueue_struct
*wq
;
4949 struct pool_workqueue
*pwq
;
4951 mutex_lock(&wq_pool_mutex
);
4953 WARN_ON_ONCE(!workqueue_freezing
);
4955 list_for_each_entry(wq
, &workqueues
, list
) {
4956 if (!(wq
->flags
& WQ_FREEZABLE
))
4959 * nr_active is monotonically decreasing. It's safe
4960 * to peek without lock.
4962 rcu_read_lock_sched();
4963 for_each_pwq(pwq
, wq
) {
4964 WARN_ON_ONCE(pwq
->nr_active
< 0);
4965 if (pwq
->nr_active
) {
4967 rcu_read_unlock_sched();
4971 rcu_read_unlock_sched();
4974 mutex_unlock(&wq_pool_mutex
);
4979 * thaw_workqueues - thaw workqueues
4981 * Thaw workqueues. Normal queueing is restored and all collected
4982 * frozen works are transferred to their respective pool worklists.
4985 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4987 void thaw_workqueues(void)
4989 struct workqueue_struct
*wq
;
4990 struct pool_workqueue
*pwq
;
4991 struct worker_pool
*pool
;
4994 mutex_lock(&wq_pool_mutex
);
4996 if (!workqueue_freezing
)
4999 /* clear FREEZING */
5000 for_each_pool(pool
, pi
) {
5001 spin_lock_irq(&pool
->lock
);
5002 WARN_ON_ONCE(!(pool
->flags
& POOL_FREEZING
));
5003 pool
->flags
&= ~POOL_FREEZING
;
5004 spin_unlock_irq(&pool
->lock
);
5007 /* restore max_active and repopulate worklist */
5008 list_for_each_entry(wq
, &workqueues
, list
) {
5009 mutex_lock(&wq
->mutex
);
5010 for_each_pwq(pwq
, wq
)
5011 pwq_adjust_max_active(pwq
);
5012 mutex_unlock(&wq
->mutex
);
5015 workqueue_freezing
= false;
5017 mutex_unlock(&wq_pool_mutex
);
5019 #endif /* CONFIG_FREEZER */
5021 static void __init
wq_numa_init(void)
5026 /* determine NUMA pwq table len - highest node id + 1 */
5028 wq_numa_tbl_len
= max(wq_numa_tbl_len
, node
+ 1);
5030 if (num_possible_nodes() <= 1)
5033 if (wq_disable_numa
) {
5034 pr_info("workqueue: NUMA affinity support disabled\n");
5038 wq_update_unbound_numa_attrs_buf
= alloc_workqueue_attrs(GFP_KERNEL
);
5039 BUG_ON(!wq_update_unbound_numa_attrs_buf
);
5042 * We want masks of possible CPUs of each node which isn't readily
5043 * available. Build one from cpu_to_node() which should have been
5044 * fully initialized by now.
5046 tbl
= kzalloc(wq_numa_tbl_len
* sizeof(tbl
[0]), GFP_KERNEL
);
5050 BUG_ON(!zalloc_cpumask_var_node(&tbl
[node
], GFP_KERNEL
,
5051 node_online(node
) ? node
: NUMA_NO_NODE
));
5053 for_each_possible_cpu(cpu
) {
5054 node
= cpu_to_node(cpu
);
5055 if (WARN_ON(node
== NUMA_NO_NODE
)) {
5056 pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu
);
5057 /* happens iff arch is bonkers, let's just proceed */
5060 cpumask_set_cpu(cpu
, tbl
[node
]);
5063 wq_numa_possible_cpumask
= tbl
;
5064 wq_numa_enabled
= true;
5067 static int __init
init_workqueues(void)
5069 int std_nice
[NR_STD_WORKER_POOLS
] = { 0, HIGHPRI_NICE_LEVEL
};
5072 /* make sure we have enough bits for OFFQ pool ID */
5073 BUILD_BUG_ON((1LU << (BITS_PER_LONG
- WORK_OFFQ_POOL_SHIFT
)) <
5074 WORK_CPU_END
* NR_STD_WORKER_POOLS
);
5076 WARN_ON(__alignof__(struct pool_workqueue
) < __alignof__(long long));
5078 pwq_cache
= KMEM_CACHE(pool_workqueue
, SLAB_PANIC
);
5080 cpu_notifier(workqueue_cpu_up_callback
, CPU_PRI_WORKQUEUE_UP
);
5081 hotcpu_notifier(workqueue_cpu_down_callback
, CPU_PRI_WORKQUEUE_DOWN
);
5085 /* initialize CPU pools */
5086 for_each_possible_cpu(cpu
) {
5087 struct worker_pool
*pool
;
5090 for_each_cpu_worker_pool(pool
, cpu
) {
5091 BUG_ON(init_worker_pool(pool
));
5093 cpumask_copy(pool
->attrs
->cpumask
, cpumask_of(cpu
));
5094 pool
->attrs
->nice
= std_nice
[i
++];
5095 pool
->node
= cpu_to_node(cpu
);
5098 mutex_lock(&wq_pool_mutex
);
5099 BUG_ON(worker_pool_assign_id(pool
));
5100 mutex_unlock(&wq_pool_mutex
);
5104 /* create the initial worker */
5105 for_each_online_cpu(cpu
) {
5106 struct worker_pool
*pool
;
5108 for_each_cpu_worker_pool(pool
, cpu
) {
5109 pool
->flags
&= ~POOL_DISASSOCIATED
;
5110 BUG_ON(create_and_start_worker(pool
) < 0);
5114 /* create default unbound and ordered wq attrs */
5115 for (i
= 0; i
< NR_STD_WORKER_POOLS
; i
++) {
5116 struct workqueue_attrs
*attrs
;
5118 BUG_ON(!(attrs
= alloc_workqueue_attrs(GFP_KERNEL
)));
5119 attrs
->nice
= std_nice
[i
];
5120 unbound_std_wq_attrs
[i
] = attrs
;
5123 * An ordered wq should have only one pwq as ordering is
5124 * guaranteed by max_active which is enforced by pwqs.
5125 * Turn off NUMA so that dfl_pwq is used for all nodes.
5127 BUG_ON(!(attrs
= alloc_workqueue_attrs(GFP_KERNEL
)));
5128 attrs
->nice
= std_nice
[i
];
5129 attrs
->no_numa
= true;
5130 ordered_wq_attrs
[i
] = attrs
;
5133 system_wq
= alloc_workqueue("events", 0, 0);
5134 system_highpri_wq
= alloc_workqueue("events_highpri", WQ_HIGHPRI
, 0);
5135 system_long_wq
= alloc_workqueue("events_long", 0, 0);
5136 system_unbound_wq
= alloc_workqueue("events_unbound", WQ_UNBOUND
,
5137 WQ_UNBOUND_MAX_ACTIVE
);
5138 system_freezable_wq
= alloc_workqueue("events_freezable",
5140 BUG_ON(!system_wq
|| !system_highpri_wq
|| !system_long_wq
||
5141 !system_unbound_wq
|| !system_freezable_wq
);
5144 early_initcall(init_workqueues
);