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1 | /* |
2 | * kernel/workqueue.c - generic async execution with shared worker pool |
3 | * |
4 | * Copyright (C) 2002 Ingo Molnar |
5 | * |
6 | * Derived from the taskqueue/keventd code by: |
7 | * David Woodhouse <dwmw2@infradead.org> |
8 | * Andrew Morton |
9 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
10 | * Theodore Ts'o <tytso@mit.edu> |
11 | * |
12 | * Made to use alloc_percpu by Christoph Lameter. |
13 | * |
14 | * Copyright (C) 2010 SUSE Linux Products GmbH |
15 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> |
16 | * |
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. |
22 | * |
23 | * Please read Documentation/workqueue.txt for details. |
24 | */ |
25 | |
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/hashtable.h> |
45 | |
46 | #include "workqueue_internal.h" |
47 | |
48 | enum { |
49 | /* |
50 | * worker_pool flags |
51 | * |
52 | * A bound pool is either associated or disassociated with its CPU. |
53 | * While associated (!DISASSOCIATED), all workers are bound to the |
54 | * CPU and none has %WORKER_UNBOUND set and concurrency management |
55 | * is in effect. |
56 | * |
57 | * While DISASSOCIATED, the cpu may be offline and all workers have |
58 | * %WORKER_UNBOUND set and concurrency management disabled, and may |
59 | * be executing on any CPU. The pool behaves as an unbound one. |
60 | * |
61 | * Note that DISASSOCIATED can be flipped only while holding |
62 | * assoc_mutex to avoid changing binding state while |
63 | * create_worker() is in progress. |
64 | */ |
65 | POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ |
66 | POOL_MANAGING_WORKERS = 1 << 1, /* managing workers */ |
67 | POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
68 | POOL_FREEZING = 1 << 3, /* freeze in progress */ |
69 | |
70 | /* worker flags */ |
71 | WORKER_STARTED = 1 << 0, /* started */ |
72 | WORKER_DIE = 1 << 1, /* die die die */ |
73 | WORKER_IDLE = 1 << 2, /* is idle */ |
74 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
75 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
76 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
77 | |
78 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_UNBOUND | |
79 | WORKER_CPU_INTENSIVE, |
80 | |
81 | NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ |
82 | |
83 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
84 | |
85 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
86 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
87 | |
88 | MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, |
89 | /* call for help after 10ms |
90 | (min two ticks) */ |
91 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
92 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
93 | |
94 | /* |
95 | * Rescue workers are used only on emergencies and shared by |
96 | * all cpus. Give -20. |
97 | */ |
98 | RESCUER_NICE_LEVEL = -20, |
99 | HIGHPRI_NICE_LEVEL = -20, |
100 | }; |
101 | |
102 | /* |
103 | * Structure fields follow one of the following exclusion rules. |
104 | * |
105 | * I: Modifiable by initialization/destruction paths and read-only for |
106 | * everyone else. |
107 | * |
108 | * P: Preemption protected. Disabling preemption is enough and should |
109 | * only be modified and accessed from the local cpu. |
110 | * |
111 | * L: pool->lock protected. Access with pool->lock held. |
112 | * |
113 | * X: During normal operation, modification requires pool->lock and should |
114 | * be done only from local cpu. Either disabling preemption on local |
115 | * cpu or grabbing pool->lock is enough for read access. If |
116 | * POOL_DISASSOCIATED is set, it's identical to L. |
117 | * |
118 | * F: wq->flush_mutex protected. |
119 | * |
120 | * W: workqueue_lock protected. |
121 | */ |
122 | |
123 | /* struct worker is defined in workqueue_internal.h */ |
124 | |
125 | struct worker_pool { |
126 | spinlock_t lock; /* the pool lock */ |
127 | unsigned int cpu; /* I: the associated cpu */ |
128 | int id; /* I: pool ID */ |
129 | unsigned int flags; /* X: flags */ |
130 | |
131 | struct list_head worklist; /* L: list of pending works */ |
132 | int nr_workers; /* L: total number of workers */ |
133 | |
134 | /* nr_idle includes the ones off idle_list for rebinding */ |
135 | int nr_idle; /* L: currently idle ones */ |
136 | |
137 | struct list_head idle_list; /* X: list of idle workers */ |
138 | struct timer_list idle_timer; /* L: worker idle timeout */ |
139 | struct timer_list mayday_timer; /* L: SOS timer for workers */ |
140 | |
141 | /* workers are chained either in busy_hash or idle_list */ |
142 | DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); |
143 | /* L: hash of busy workers */ |
144 | |
145 | struct mutex assoc_mutex; /* protect POOL_DISASSOCIATED */ |
146 | struct ida worker_ida; /* L: for worker IDs */ |
147 | |
148 | /* |
149 | * The current concurrency level. As it's likely to be accessed |
150 | * from other CPUs during try_to_wake_up(), put it in a separate |
151 | * cacheline. |
152 | */ |
153 | atomic_t nr_running ____cacheline_aligned_in_smp; |
154 | } ____cacheline_aligned_in_smp; |
155 | |
156 | /* |
157 | * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS |
158 | * of work_struct->data are used for flags and the remaining high bits |
159 | * point to the pwq; thus, pwqs need to be aligned at two's power of the |
160 | * number of flag bits. |
161 | */ |
162 | struct pool_workqueue { |
163 | struct worker_pool *pool; /* I: the associated pool */ |
164 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
165 | int work_color; /* L: current color */ |
166 | int flush_color; /* L: flushing color */ |
167 | int nr_in_flight[WORK_NR_COLORS]; |
168 | /* L: nr of in_flight works */ |
169 | int nr_active; /* L: nr of active works */ |
170 | int max_active; /* L: max active works */ |
171 | struct list_head delayed_works; /* L: delayed works */ |
172 | }; |
173 | |
174 | /* |
175 | * Structure used to wait for workqueue flush. |
176 | */ |
177 | struct wq_flusher { |
178 | struct list_head list; /* F: list of flushers */ |
179 | int flush_color; /* F: flush color waiting for */ |
180 | struct completion done; /* flush completion */ |
181 | }; |
182 | |
183 | /* |
184 | * All cpumasks are assumed to be always set on UP and thus can't be |
185 | * used to determine whether there's something to be done. |
186 | */ |
187 | #ifdef CONFIG_SMP |
188 | typedef cpumask_var_t mayday_mask_t; |
189 | #define mayday_test_and_set_cpu(cpu, mask) \ |
190 | cpumask_test_and_set_cpu((cpu), (mask)) |
191 | #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) |
192 | #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) |
193 | #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) |
194 | #define free_mayday_mask(mask) free_cpumask_var((mask)) |
195 | #else |
196 | typedef unsigned long mayday_mask_t; |
197 | #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) |
198 | #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) |
199 | #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) |
200 | #define alloc_mayday_mask(maskp, gfp) true |
201 | #define free_mayday_mask(mask) do { } while (0) |
202 | #endif |
203 | |
204 | /* |
205 | * The externally visible workqueue abstraction is an array of |
206 | * per-CPU workqueues: |
207 | */ |
208 | struct workqueue_struct { |
209 | unsigned int flags; /* W: WQ_* flags */ |
210 | union { |
211 | struct pool_workqueue __percpu *pcpu; |
212 | struct pool_workqueue *single; |
213 | unsigned long v; |
214 | } pool_wq; /* I: pwq's */ |
215 | struct list_head list; /* W: list of all workqueues */ |
216 | |
217 | struct mutex flush_mutex; /* protects wq flushing */ |
218 | int work_color; /* F: current work color */ |
219 | int flush_color; /* F: current flush color */ |
220 | atomic_t nr_pwqs_to_flush; /* flush in progress */ |
221 | struct wq_flusher *first_flusher; /* F: first flusher */ |
222 | struct list_head flusher_queue; /* F: flush waiters */ |
223 | struct list_head flusher_overflow; /* F: flush overflow list */ |
224 | |
225 | mayday_mask_t mayday_mask; /* cpus requesting rescue */ |
226 | struct worker *rescuer; /* I: rescue worker */ |
227 | |
228 | int nr_drainers; /* W: drain in progress */ |
229 | int saved_max_active; /* W: saved pwq max_active */ |
230 | #ifdef CONFIG_LOCKDEP |
231 | struct lockdep_map lockdep_map; |
232 | #endif |
233 | char name[]; /* I: workqueue name */ |
234 | }; |
235 | |
236 | struct workqueue_struct *system_wq __read_mostly; |
237 | EXPORT_SYMBOL_GPL(system_wq); |
238 | struct workqueue_struct *system_highpri_wq __read_mostly; |
239 | EXPORT_SYMBOL_GPL(system_highpri_wq); |
240 | struct workqueue_struct *system_long_wq __read_mostly; |
241 | EXPORT_SYMBOL_GPL(system_long_wq); |
242 | struct workqueue_struct *system_unbound_wq __read_mostly; |
243 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
244 | struct workqueue_struct *system_freezable_wq __read_mostly; |
245 | EXPORT_SYMBOL_GPL(system_freezable_wq); |
246 | |
247 | #define CREATE_TRACE_POINTS |
248 | #include <trace/events/workqueue.h> |
249 | |
250 | #define for_each_std_worker_pool(pool, cpu) \ |
251 | for ((pool) = &std_worker_pools(cpu)[0]; \ |
252 | (pool) < &std_worker_pools(cpu)[NR_STD_WORKER_POOLS]; (pool)++) |
253 | |
254 | #define for_each_busy_worker(worker, i, pool) \ |
255 | hash_for_each(pool->busy_hash, i, worker, hentry) |
256 | |
257 | static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, |
258 | unsigned int sw) |
259 | { |
260 | if (cpu < nr_cpu_ids) { |
261 | if (sw & 1) { |
262 | cpu = cpumask_next(cpu, mask); |
263 | if (cpu < nr_cpu_ids) |
264 | return cpu; |
265 | } |
266 | if (sw & 2) |
267 | return WORK_CPU_UNBOUND; |
268 | } |
269 | return WORK_CPU_END; |
270 | } |
271 | |
272 | static inline int __next_pwq_cpu(int cpu, const struct cpumask *mask, |
273 | struct workqueue_struct *wq) |
274 | { |
275 | return __next_wq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); |
276 | } |
277 | |
278 | /* |
279 | * CPU iterators |
280 | * |
281 | * An extra cpu number is defined using an invalid cpu number |
282 | * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any |
283 | * specific CPU. The following iterators are similar to for_each_*_cpu() |
284 | * iterators but also considers the unbound CPU. |
285 | * |
286 | * for_each_wq_cpu() : possible CPUs + WORK_CPU_UNBOUND |
287 | * for_each_online_wq_cpu() : online CPUs + WORK_CPU_UNBOUND |
288 | * for_each_pwq_cpu() : possible CPUs for bound workqueues, |
289 | * WORK_CPU_UNBOUND for unbound workqueues |
290 | */ |
291 | #define for_each_wq_cpu(cpu) \ |
292 | for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, 3); \ |
293 | (cpu) < WORK_CPU_END; \ |
294 | (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, 3)) |
295 | |
296 | #define for_each_online_wq_cpu(cpu) \ |
297 | for ((cpu) = __next_wq_cpu(-1, cpu_online_mask, 3); \ |
298 | (cpu) < WORK_CPU_END; \ |
299 | (cpu) = __next_wq_cpu((cpu), cpu_online_mask, 3)) |
300 | |
301 | #define for_each_pwq_cpu(cpu, wq) \ |
302 | for ((cpu) = __next_pwq_cpu(-1, cpu_possible_mask, (wq)); \ |
303 | (cpu) < WORK_CPU_END; \ |
304 | (cpu) = __next_pwq_cpu((cpu), cpu_possible_mask, (wq))) |
305 | |
306 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
307 | |
308 | static struct debug_obj_descr work_debug_descr; |
309 | |
310 | static void *work_debug_hint(void *addr) |
311 | { |
312 | return ((struct work_struct *) addr)->func; |
313 | } |
314 | |
315 | /* |
316 | * fixup_init is called when: |
317 | * - an active object is initialized |
318 | */ |
319 | static int work_fixup_init(void *addr, enum debug_obj_state state) |
320 | { |
321 | struct work_struct *work = addr; |
322 | |
323 | switch (state) { |
324 | case ODEBUG_STATE_ACTIVE: |
325 | cancel_work_sync(work); |
326 | debug_object_init(work, &work_debug_descr); |
327 | return 1; |
328 | default: |
329 | return 0; |
330 | } |
331 | } |
332 | |
333 | /* |
334 | * fixup_activate is called when: |
335 | * - an active object is activated |
336 | * - an unknown object is activated (might be a statically initialized object) |
337 | */ |
338 | static int work_fixup_activate(void *addr, enum debug_obj_state state) |
339 | { |
340 | struct work_struct *work = addr; |
341 | |
342 | switch (state) { |
343 | |
344 | case ODEBUG_STATE_NOTAVAILABLE: |
345 | /* |
346 | * This is not really a fixup. The work struct was |
347 | * statically initialized. We just make sure that it |
348 | * is tracked in the object tracker. |
349 | */ |
350 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
351 | debug_object_init(work, &work_debug_descr); |
352 | debug_object_activate(work, &work_debug_descr); |
353 | return 0; |
354 | } |
355 | WARN_ON_ONCE(1); |
356 | return 0; |
357 | |
358 | case ODEBUG_STATE_ACTIVE: |
359 | WARN_ON(1); |
360 | |
361 | default: |
362 | return 0; |
363 | } |
364 | } |
365 | |
366 | /* |
367 | * fixup_free is called when: |
368 | * - an active object is freed |
369 | */ |
370 | static int work_fixup_free(void *addr, enum debug_obj_state state) |
371 | { |
372 | struct work_struct *work = addr; |
373 | |
374 | switch (state) { |
375 | case ODEBUG_STATE_ACTIVE: |
376 | cancel_work_sync(work); |
377 | debug_object_free(work, &work_debug_descr); |
378 | return 1; |
379 | default: |
380 | return 0; |
381 | } |
382 | } |
383 | |
384 | static struct debug_obj_descr work_debug_descr = { |
385 | .name = "work_struct", |
386 | .debug_hint = work_debug_hint, |
387 | .fixup_init = work_fixup_init, |
388 | .fixup_activate = work_fixup_activate, |
389 | .fixup_free = work_fixup_free, |
390 | }; |
391 | |
392 | static inline void debug_work_activate(struct work_struct *work) |
393 | { |
394 | debug_object_activate(work, &work_debug_descr); |
395 | } |
396 | |
397 | static inline void debug_work_deactivate(struct work_struct *work) |
398 | { |
399 | debug_object_deactivate(work, &work_debug_descr); |
400 | } |
401 | |
402 | void __init_work(struct work_struct *work, int onstack) |
403 | { |
404 | if (onstack) |
405 | debug_object_init_on_stack(work, &work_debug_descr); |
406 | else |
407 | debug_object_init(work, &work_debug_descr); |
408 | } |
409 | EXPORT_SYMBOL_GPL(__init_work); |
410 | |
411 | void destroy_work_on_stack(struct work_struct *work) |
412 | { |
413 | debug_object_free(work, &work_debug_descr); |
414 | } |
415 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
416 | |
417 | #else |
418 | static inline void debug_work_activate(struct work_struct *work) { } |
419 | static inline void debug_work_deactivate(struct work_struct *work) { } |
420 | #endif |
421 | |
422 | /* Serializes the accesses to the list of workqueues. */ |
423 | static DEFINE_SPINLOCK(workqueue_lock); |
424 | static LIST_HEAD(workqueues); |
425 | static bool workqueue_freezing; /* W: have wqs started freezing? */ |
426 | |
427 | /* |
428 | * The CPU and unbound standard worker pools. The unbound ones have |
429 | * POOL_DISASSOCIATED set, and their workers have WORKER_UNBOUND set. |
430 | */ |
431 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], |
432 | cpu_std_worker_pools); |
433 | static struct worker_pool unbound_std_worker_pools[NR_STD_WORKER_POOLS]; |
434 | |
435 | /* idr of all pools */ |
436 | static DEFINE_MUTEX(worker_pool_idr_mutex); |
437 | static DEFINE_IDR(worker_pool_idr); |
438 | |
439 | static int worker_thread(void *__worker); |
440 | |
441 | static struct worker_pool *std_worker_pools(int cpu) |
442 | { |
443 | if (cpu != WORK_CPU_UNBOUND) |
444 | return per_cpu(cpu_std_worker_pools, cpu); |
445 | else |
446 | return unbound_std_worker_pools; |
447 | } |
448 | |
449 | static int std_worker_pool_pri(struct worker_pool *pool) |
450 | { |
451 | return pool - std_worker_pools(pool->cpu); |
452 | } |
453 | |
454 | /* allocate ID and assign it to @pool */ |
455 | static int worker_pool_assign_id(struct worker_pool *pool) |
456 | { |
457 | int ret; |
458 | |
459 | mutex_lock(&worker_pool_idr_mutex); |
460 | ret = idr_alloc(&worker_pool_idr, pool, 0, 0, GFP_KERNEL); |
461 | if (ret >= 0) |
462 | pool->id = ret; |
463 | mutex_unlock(&worker_pool_idr_mutex); |
464 | |
465 | return ret < 0 ? ret : 0; |
466 | } |
467 | |
468 | /* |
469 | * Lookup worker_pool by id. The idr currently is built during boot and |
470 | * never modified. Don't worry about locking for now. |
471 | */ |
472 | static struct worker_pool *worker_pool_by_id(int pool_id) |
473 | { |
474 | return idr_find(&worker_pool_idr, pool_id); |
475 | } |
476 | |
477 | static struct worker_pool *get_std_worker_pool(int cpu, bool highpri) |
478 | { |
479 | struct worker_pool *pools = std_worker_pools(cpu); |
480 | |
481 | return &pools[highpri]; |
482 | } |
483 | |
484 | static struct pool_workqueue *get_pwq(unsigned int cpu, |
485 | struct workqueue_struct *wq) |
486 | { |
487 | if (!(wq->flags & WQ_UNBOUND)) { |
488 | if (likely(cpu < nr_cpu_ids)) |
489 | return per_cpu_ptr(wq->pool_wq.pcpu, cpu); |
490 | } else if (likely(cpu == WORK_CPU_UNBOUND)) |
491 | return wq->pool_wq.single; |
492 | return NULL; |
493 | } |
494 | |
495 | static unsigned int work_color_to_flags(int color) |
496 | { |
497 | return color << WORK_STRUCT_COLOR_SHIFT; |
498 | } |
499 | |
500 | static int get_work_color(struct work_struct *work) |
501 | { |
502 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & |
503 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
504 | } |
505 | |
506 | static int work_next_color(int color) |
507 | { |
508 | return (color + 1) % WORK_NR_COLORS; |
509 | } |
510 | |
511 | /* |
512 | * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data |
513 | * contain the pointer to the queued pwq. Once execution starts, the flag |
514 | * is cleared and the high bits contain OFFQ flags and pool ID. |
515 | * |
516 | * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() |
517 | * and clear_work_data() can be used to set the pwq, pool or clear |
518 | * work->data. These functions should only be called while the work is |
519 | * owned - ie. while the PENDING bit is set. |
520 | * |
521 | * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq |
522 | * corresponding to a work. Pool is available once the work has been |
523 | * queued anywhere after initialization until it is sync canceled. pwq is |
524 | * available only while the work item is queued. |
525 | * |
526 | * %WORK_OFFQ_CANCELING is used to mark a work item which is being |
527 | * canceled. While being canceled, a work item may have its PENDING set |
528 | * but stay off timer and worklist for arbitrarily long and nobody should |
529 | * try to steal the PENDING bit. |
530 | */ |
531 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
532 | unsigned long flags) |
533 | { |
534 | BUG_ON(!work_pending(work)); |
535 | atomic_long_set(&work->data, data | flags | work_static(work)); |
536 | } |
537 | |
538 | static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, |
539 | unsigned long extra_flags) |
540 | { |
541 | set_work_data(work, (unsigned long)pwq, |
542 | WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); |
543 | } |
544 | |
545 | static void set_work_pool_and_keep_pending(struct work_struct *work, |
546 | int pool_id) |
547 | { |
548 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, |
549 | WORK_STRUCT_PENDING); |
550 | } |
551 | |
552 | static void set_work_pool_and_clear_pending(struct work_struct *work, |
553 | int pool_id) |
554 | { |
555 | /* |
556 | * The following wmb is paired with the implied mb in |
557 | * test_and_set_bit(PENDING) and ensures all updates to @work made |
558 | * here are visible to and precede any updates by the next PENDING |
559 | * owner. |
560 | */ |
561 | smp_wmb(); |
562 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); |
563 | } |
564 | |
565 | static void clear_work_data(struct work_struct *work) |
566 | { |
567 | smp_wmb(); /* see set_work_pool_and_clear_pending() */ |
568 | set_work_data(work, WORK_STRUCT_NO_POOL, 0); |
569 | } |
570 | |
571 | static struct pool_workqueue *get_work_pwq(struct work_struct *work) |
572 | { |
573 | unsigned long data = atomic_long_read(&work->data); |
574 | |
575 | if (data & WORK_STRUCT_PWQ) |
576 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
577 | else |
578 | return NULL; |
579 | } |
580 | |
581 | /** |
582 | * get_work_pool - return the worker_pool a given work was associated with |
583 | * @work: the work item of interest |
584 | * |
585 | * Return the worker_pool @work was last associated with. %NULL if none. |
586 | */ |
587 | static struct worker_pool *get_work_pool(struct work_struct *work) |
588 | { |
589 | unsigned long data = atomic_long_read(&work->data); |
590 | struct worker_pool *pool; |
591 | int pool_id; |
592 | |
593 | if (data & WORK_STRUCT_PWQ) |
594 | return ((struct pool_workqueue *) |
595 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool; |
596 | |
597 | pool_id = data >> WORK_OFFQ_POOL_SHIFT; |
598 | if (pool_id == WORK_OFFQ_POOL_NONE) |
599 | return NULL; |
600 | |
601 | pool = worker_pool_by_id(pool_id); |
602 | WARN_ON_ONCE(!pool); |
603 | return pool; |
604 | } |
605 | |
606 | /** |
607 | * get_work_pool_id - return the worker pool ID a given work is associated with |
608 | * @work: the work item of interest |
609 | * |
610 | * Return the worker_pool ID @work was last associated with. |
611 | * %WORK_OFFQ_POOL_NONE if none. |
612 | */ |
613 | static int get_work_pool_id(struct work_struct *work) |
614 | { |
615 | unsigned long data = atomic_long_read(&work->data); |
616 | |
617 | if (data & WORK_STRUCT_PWQ) |
618 | return ((struct pool_workqueue *) |
619 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; |
620 | |
621 | return data >> WORK_OFFQ_POOL_SHIFT; |
622 | } |
623 | |
624 | static void mark_work_canceling(struct work_struct *work) |
625 | { |
626 | unsigned long pool_id = get_work_pool_id(work); |
627 | |
628 | pool_id <<= WORK_OFFQ_POOL_SHIFT; |
629 | set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); |
630 | } |
631 | |
632 | static bool work_is_canceling(struct work_struct *work) |
633 | { |
634 | unsigned long data = atomic_long_read(&work->data); |
635 | |
636 | return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); |
637 | } |
638 | |
639 | /* |
640 | * Policy functions. These define the policies on how the global worker |
641 | * pools are managed. Unless noted otherwise, these functions assume that |
642 | * they're being called with pool->lock held. |
643 | */ |
644 | |
645 | static bool __need_more_worker(struct worker_pool *pool) |
646 | { |
647 | return !atomic_read(&pool->nr_running); |
648 | } |
649 | |
650 | /* |
651 | * Need to wake up a worker? Called from anything but currently |
652 | * running workers. |
653 | * |
654 | * Note that, because unbound workers never contribute to nr_running, this |
655 | * function will always return %true for unbound pools as long as the |
656 | * worklist isn't empty. |
657 | */ |
658 | static bool need_more_worker(struct worker_pool *pool) |
659 | { |
660 | return !list_empty(&pool->worklist) && __need_more_worker(pool); |
661 | } |
662 | |
663 | /* Can I start working? Called from busy but !running workers. */ |
664 | static bool may_start_working(struct worker_pool *pool) |
665 | { |
666 | return pool->nr_idle; |
667 | } |
668 | |
669 | /* Do I need to keep working? Called from currently running workers. */ |
670 | static bool keep_working(struct worker_pool *pool) |
671 | { |
672 | return !list_empty(&pool->worklist) && |
673 | atomic_read(&pool->nr_running) <= 1; |
674 | } |
675 | |
676 | /* Do we need a new worker? Called from manager. */ |
677 | static bool need_to_create_worker(struct worker_pool *pool) |
678 | { |
679 | return need_more_worker(pool) && !may_start_working(pool); |
680 | } |
681 | |
682 | /* Do I need to be the manager? */ |
683 | static bool need_to_manage_workers(struct worker_pool *pool) |
684 | { |
685 | return need_to_create_worker(pool) || |
686 | (pool->flags & POOL_MANAGE_WORKERS); |
687 | } |
688 | |
689 | /* Do we have too many workers and should some go away? */ |
690 | static bool too_many_workers(struct worker_pool *pool) |
691 | { |
692 | bool managing = pool->flags & POOL_MANAGING_WORKERS; |
693 | int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ |
694 | int nr_busy = pool->nr_workers - nr_idle; |
695 | |
696 | /* |
697 | * nr_idle and idle_list may disagree if idle rebinding is in |
698 | * progress. Never return %true if idle_list is empty. |
699 | */ |
700 | if (list_empty(&pool->idle_list)) |
701 | return false; |
702 | |
703 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
704 | } |
705 | |
706 | /* |
707 | * Wake up functions. |
708 | */ |
709 | |
710 | /* Return the first worker. Safe with preemption disabled */ |
711 | static struct worker *first_worker(struct worker_pool *pool) |
712 | { |
713 | if (unlikely(list_empty(&pool->idle_list))) |
714 | return NULL; |
715 | |
716 | return list_first_entry(&pool->idle_list, struct worker, entry); |
717 | } |
718 | |
719 | /** |
720 | * wake_up_worker - wake up an idle worker |
721 | * @pool: worker pool to wake worker from |
722 | * |
723 | * Wake up the first idle worker of @pool. |
724 | * |
725 | * CONTEXT: |
726 | * spin_lock_irq(pool->lock). |
727 | */ |
728 | static void wake_up_worker(struct worker_pool *pool) |
729 | { |
730 | struct worker *worker = first_worker(pool); |
731 | |
732 | if (likely(worker)) |
733 | wake_up_process(worker->task); |
734 | } |
735 | |
736 | /** |
737 | * wq_worker_waking_up - a worker is waking up |
738 | * @task: task waking up |
739 | * @cpu: CPU @task is waking up to |
740 | * |
741 | * This function is called during try_to_wake_up() when a worker is |
742 | * being awoken. |
743 | * |
744 | * CONTEXT: |
745 | * spin_lock_irq(rq->lock) |
746 | */ |
747 | void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) |
748 | { |
749 | struct worker *worker = kthread_data(task); |
750 | |
751 | if (!(worker->flags & WORKER_NOT_RUNNING)) { |
752 | WARN_ON_ONCE(worker->pool->cpu != cpu); |
753 | atomic_inc(&worker->pool->nr_running); |
754 | } |
755 | } |
756 | |
757 | /** |
758 | * wq_worker_sleeping - a worker is going to sleep |
759 | * @task: task going to sleep |
760 | * @cpu: CPU in question, must be the current CPU number |
761 | * |
762 | * This function is called during schedule() when a busy worker is |
763 | * going to sleep. Worker on the same cpu can be woken up by |
764 | * returning pointer to its task. |
765 | * |
766 | * CONTEXT: |
767 | * spin_lock_irq(rq->lock) |
768 | * |
769 | * RETURNS: |
770 | * Worker task on @cpu to wake up, %NULL if none. |
771 | */ |
772 | struct task_struct *wq_worker_sleeping(struct task_struct *task, |
773 | unsigned int cpu) |
774 | { |
775 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; |
776 | struct worker_pool *pool; |
777 | |
778 | /* |
779 | * Rescuers, which may not have all the fields set up like normal |
780 | * workers, also reach here, let's not access anything before |
781 | * checking NOT_RUNNING. |
782 | */ |
783 | if (worker->flags & WORKER_NOT_RUNNING) |
784 | return NULL; |
785 | |
786 | pool = worker->pool; |
787 | |
788 | /* this can only happen on the local cpu */ |
789 | BUG_ON(cpu != raw_smp_processor_id()); |
790 | |
791 | /* |
792 | * The counterpart of the following dec_and_test, implied mb, |
793 | * worklist not empty test sequence is in insert_work(). |
794 | * Please read comment there. |
795 | * |
796 | * NOT_RUNNING is clear. This means that we're bound to and |
797 | * running on the local cpu w/ rq lock held and preemption |
798 | * disabled, which in turn means that none else could be |
799 | * manipulating idle_list, so dereferencing idle_list without pool |
800 | * lock is safe. |
801 | */ |
802 | if (atomic_dec_and_test(&pool->nr_running) && |
803 | !list_empty(&pool->worklist)) |
804 | to_wakeup = first_worker(pool); |
805 | return to_wakeup ? to_wakeup->task : NULL; |
806 | } |
807 | |
808 | /** |
809 | * worker_set_flags - set worker flags and adjust nr_running accordingly |
810 | * @worker: self |
811 | * @flags: flags to set |
812 | * @wakeup: wakeup an idle worker if necessary |
813 | * |
814 | * Set @flags in @worker->flags and adjust nr_running accordingly. If |
815 | * nr_running becomes zero and @wakeup is %true, an idle worker is |
816 | * woken up. |
817 | * |
818 | * CONTEXT: |
819 | * spin_lock_irq(pool->lock) |
820 | */ |
821 | static inline void worker_set_flags(struct worker *worker, unsigned int flags, |
822 | bool wakeup) |
823 | { |
824 | struct worker_pool *pool = worker->pool; |
825 | |
826 | WARN_ON_ONCE(worker->task != current); |
827 | |
828 | /* |
829 | * If transitioning into NOT_RUNNING, adjust nr_running and |
830 | * wake up an idle worker as necessary if requested by |
831 | * @wakeup. |
832 | */ |
833 | if ((flags & WORKER_NOT_RUNNING) && |
834 | !(worker->flags & WORKER_NOT_RUNNING)) { |
835 | if (wakeup) { |
836 | if (atomic_dec_and_test(&pool->nr_running) && |
837 | !list_empty(&pool->worklist)) |
838 | wake_up_worker(pool); |
839 | } else |
840 | atomic_dec(&pool->nr_running); |
841 | } |
842 | |
843 | worker->flags |= flags; |
844 | } |
845 | |
846 | /** |
847 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
848 | * @worker: self |
849 | * @flags: flags to clear |
850 | * |
851 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
852 | * |
853 | * CONTEXT: |
854 | * spin_lock_irq(pool->lock) |
855 | */ |
856 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
857 | { |
858 | struct worker_pool *pool = worker->pool; |
859 | unsigned int oflags = worker->flags; |
860 | |
861 | WARN_ON_ONCE(worker->task != current); |
862 | |
863 | worker->flags &= ~flags; |
864 | |
865 | /* |
866 | * If transitioning out of NOT_RUNNING, increment nr_running. Note |
867 | * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask |
868 | * of multiple flags, not a single flag. |
869 | */ |
870 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
871 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
872 | atomic_inc(&pool->nr_running); |
873 | } |
874 | |
875 | /** |
876 | * find_worker_executing_work - find worker which is executing a work |
877 | * @pool: pool of interest |
878 | * @work: work to find worker for |
879 | * |
880 | * Find a worker which is executing @work on @pool by searching |
881 | * @pool->busy_hash which is keyed by the address of @work. For a worker |
882 | * to match, its current execution should match the address of @work and |
883 | * its work function. This is to avoid unwanted dependency between |
884 | * unrelated work executions through a work item being recycled while still |
885 | * being executed. |
886 | * |
887 | * This is a bit tricky. A work item may be freed once its execution |
888 | * starts and nothing prevents the freed area from being recycled for |
889 | * another work item. If the same work item address ends up being reused |
890 | * before the original execution finishes, workqueue will identify the |
891 | * recycled work item as currently executing and make it wait until the |
892 | * current execution finishes, introducing an unwanted dependency. |
893 | * |
894 | * This function checks the work item address, work function and workqueue |
895 | * to avoid false positives. Note that this isn't complete as one may |
896 | * construct a work function which can introduce dependency onto itself |
897 | * through a recycled work item. Well, if somebody wants to shoot oneself |
898 | * in the foot that badly, there's only so much we can do, and if such |
899 | * deadlock actually occurs, it should be easy to locate the culprit work |
900 | * function. |
901 | * |
902 | * CONTEXT: |
903 | * spin_lock_irq(pool->lock). |
904 | * |
905 | * RETURNS: |
906 | * Pointer to worker which is executing @work if found, NULL |
907 | * otherwise. |
908 | */ |
909 | static struct worker *find_worker_executing_work(struct worker_pool *pool, |
910 | struct work_struct *work) |
911 | { |
912 | struct worker *worker; |
913 | |
914 | hash_for_each_possible(pool->busy_hash, worker, hentry, |
915 | (unsigned long)work) |
916 | if (worker->current_work == work && |
917 | worker->current_func == work->func) |
918 | return worker; |
919 | |
920 | return NULL; |
921 | } |
922 | |
923 | /** |
924 | * move_linked_works - move linked works to a list |
925 | * @work: start of series of works to be scheduled |
926 | * @head: target list to append @work to |
927 | * @nextp: out paramter for nested worklist walking |
928 | * |
929 | * Schedule linked works starting from @work to @head. Work series to |
930 | * be scheduled starts at @work and includes any consecutive work with |
931 | * WORK_STRUCT_LINKED set in its predecessor. |
932 | * |
933 | * If @nextp is not NULL, it's updated to point to the next work of |
934 | * the last scheduled work. This allows move_linked_works() to be |
935 | * nested inside outer list_for_each_entry_safe(). |
936 | * |
937 | * CONTEXT: |
938 | * spin_lock_irq(pool->lock). |
939 | */ |
940 | static void move_linked_works(struct work_struct *work, struct list_head *head, |
941 | struct work_struct **nextp) |
942 | { |
943 | struct work_struct *n; |
944 | |
945 | /* |
946 | * Linked worklist will always end before the end of the list, |
947 | * use NULL for list head. |
948 | */ |
949 | list_for_each_entry_safe_from(work, n, NULL, entry) { |
950 | list_move_tail(&work->entry, head); |
951 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
952 | break; |
953 | } |
954 | |
955 | /* |
956 | * If we're already inside safe list traversal and have moved |
957 | * multiple works to the scheduled queue, the next position |
958 | * needs to be updated. |
959 | */ |
960 | if (nextp) |
961 | *nextp = n; |
962 | } |
963 | |
964 | static void pwq_activate_delayed_work(struct work_struct *work) |
965 | { |
966 | struct pool_workqueue *pwq = get_work_pwq(work); |
967 | |
968 | trace_workqueue_activate_work(work); |
969 | move_linked_works(work, &pwq->pool->worklist, NULL); |
970 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); |
971 | pwq->nr_active++; |
972 | } |
973 | |
974 | static void pwq_activate_first_delayed(struct pool_workqueue *pwq) |
975 | { |
976 | struct work_struct *work = list_first_entry(&pwq->delayed_works, |
977 | struct work_struct, entry); |
978 | |
979 | pwq_activate_delayed_work(work); |
980 | } |
981 | |
982 | /** |
983 | * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight |
984 | * @pwq: pwq of interest |
985 | * @color: color of work which left the queue |
986 | * |
987 | * A work either has completed or is removed from pending queue, |
988 | * decrement nr_in_flight of its pwq and handle workqueue flushing. |
989 | * |
990 | * CONTEXT: |
991 | * spin_lock_irq(pool->lock). |
992 | */ |
993 | static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) |
994 | { |
995 | /* ignore uncolored works */ |
996 | if (color == WORK_NO_COLOR) |
997 | return; |
998 | |
999 | pwq->nr_in_flight[color]--; |
1000 | |
1001 | pwq->nr_active--; |
1002 | if (!list_empty(&pwq->delayed_works)) { |
1003 | /* one down, submit a delayed one */ |
1004 | if (pwq->nr_active < pwq->max_active) |
1005 | pwq_activate_first_delayed(pwq); |
1006 | } |
1007 | |
1008 | /* is flush in progress and are we at the flushing tip? */ |
1009 | if (likely(pwq->flush_color != color)) |
1010 | return; |
1011 | |
1012 | /* are there still in-flight works? */ |
1013 | if (pwq->nr_in_flight[color]) |
1014 | return; |
1015 | |
1016 | /* this pwq is done, clear flush_color */ |
1017 | pwq->flush_color = -1; |
1018 | |
1019 | /* |
1020 | * If this was the last pwq, wake up the first flusher. It |
1021 | * will handle the rest. |
1022 | */ |
1023 | if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) |
1024 | complete(&pwq->wq->first_flusher->done); |
1025 | } |
1026 | |
1027 | /** |
1028 | * try_to_grab_pending - steal work item from worklist and disable irq |
1029 | * @work: work item to steal |
1030 | * @is_dwork: @work is a delayed_work |
1031 | * @flags: place to store irq state |
1032 | * |
1033 | * Try to grab PENDING bit of @work. This function can handle @work in any |
1034 | * stable state - idle, on timer or on worklist. Return values are |
1035 | * |
1036 | * 1 if @work was pending and we successfully stole PENDING |
1037 | * 0 if @work was idle and we claimed PENDING |
1038 | * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry |
1039 | * -ENOENT if someone else is canceling @work, this state may persist |
1040 | * for arbitrarily long |
1041 | * |
1042 | * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting |
1043 | * interrupted while holding PENDING and @work off queue, irq must be |
1044 | * disabled on entry. This, combined with delayed_work->timer being |
1045 | * irqsafe, ensures that we return -EAGAIN for finite short period of time. |
1046 | * |
1047 | * On successful return, >= 0, irq is disabled and the caller is |
1048 | * responsible for releasing it using local_irq_restore(*@flags). |
1049 | * |
1050 | * This function is safe to call from any context including IRQ handler. |
1051 | */ |
1052 | static int try_to_grab_pending(struct work_struct *work, bool is_dwork, |
1053 | unsigned long *flags) |
1054 | { |
1055 | struct worker_pool *pool; |
1056 | struct pool_workqueue *pwq; |
1057 | |
1058 | local_irq_save(*flags); |
1059 | |
1060 | /* try to steal the timer if it exists */ |
1061 | if (is_dwork) { |
1062 | struct delayed_work *dwork = to_delayed_work(work); |
1063 | |
1064 | /* |
1065 | * dwork->timer is irqsafe. If del_timer() fails, it's |
1066 | * guaranteed that the timer is not queued anywhere and not |
1067 | * running on the local CPU. |
1068 | */ |
1069 | if (likely(del_timer(&dwork->timer))) |
1070 | return 1; |
1071 | } |
1072 | |
1073 | /* try to claim PENDING the normal way */ |
1074 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1075 | return 0; |
1076 | |
1077 | /* |
1078 | * The queueing is in progress, or it is already queued. Try to |
1079 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
1080 | */ |
1081 | pool = get_work_pool(work); |
1082 | if (!pool) |
1083 | goto fail; |
1084 | |
1085 | spin_lock(&pool->lock); |
1086 | /* |
1087 | * work->data is guaranteed to point to pwq only while the work |
1088 | * item is queued on pwq->wq, and both updating work->data to point |
1089 | * to pwq on queueing and to pool on dequeueing are done under |
1090 | * pwq->pool->lock. This in turn guarantees that, if work->data |
1091 | * points to pwq which is associated with a locked pool, the work |
1092 | * item is currently queued on that pool. |
1093 | */ |
1094 | pwq = get_work_pwq(work); |
1095 | if (pwq && pwq->pool == pool) { |
1096 | debug_work_deactivate(work); |
1097 | |
1098 | /* |
1099 | * A delayed work item cannot be grabbed directly because |
1100 | * it might have linked NO_COLOR work items which, if left |
1101 | * on the delayed_list, will confuse pwq->nr_active |
1102 | * management later on and cause stall. Make sure the work |
1103 | * item is activated before grabbing. |
1104 | */ |
1105 | if (*work_data_bits(work) & WORK_STRUCT_DELAYED) |
1106 | pwq_activate_delayed_work(work); |
1107 | |
1108 | list_del_init(&work->entry); |
1109 | pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work)); |
1110 | |
1111 | /* work->data points to pwq iff queued, point to pool */ |
1112 | set_work_pool_and_keep_pending(work, pool->id); |
1113 | |
1114 | spin_unlock(&pool->lock); |
1115 | return 1; |
1116 | } |
1117 | spin_unlock(&pool->lock); |
1118 | fail: |
1119 | local_irq_restore(*flags); |
1120 | if (work_is_canceling(work)) |
1121 | return -ENOENT; |
1122 | cpu_relax(); |
1123 | return -EAGAIN; |
1124 | } |
1125 | |
1126 | /** |
1127 | * insert_work - insert a work into a pool |
1128 | * @pwq: pwq @work belongs to |
1129 | * @work: work to insert |
1130 | * @head: insertion point |
1131 | * @extra_flags: extra WORK_STRUCT_* flags to set |
1132 | * |
1133 | * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to |
1134 | * work_struct flags. |
1135 | * |
1136 | * CONTEXT: |
1137 | * spin_lock_irq(pool->lock). |
1138 | */ |
1139 | static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, |
1140 | struct list_head *head, unsigned int extra_flags) |
1141 | { |
1142 | struct worker_pool *pool = pwq->pool; |
1143 | |
1144 | /* we own @work, set data and link */ |
1145 | set_work_pwq(work, pwq, extra_flags); |
1146 | list_add_tail(&work->entry, head); |
1147 | |
1148 | /* |
1149 | * Ensure either worker_sched_deactivated() sees the above |
1150 | * list_add_tail() or we see zero nr_running to avoid workers |
1151 | * lying around lazily while there are works to be processed. |
1152 | */ |
1153 | smp_mb(); |
1154 | |
1155 | if (__need_more_worker(pool)) |
1156 | wake_up_worker(pool); |
1157 | } |
1158 | |
1159 | /* |
1160 | * Test whether @work is being queued from another work executing on the |
1161 | * same workqueue. |
1162 | */ |
1163 | static bool is_chained_work(struct workqueue_struct *wq) |
1164 | { |
1165 | struct worker *worker; |
1166 | |
1167 | worker = current_wq_worker(); |
1168 | /* |
1169 | * Return %true iff I'm a worker execuing a work item on @wq. If |
1170 | * I'm @worker, it's safe to dereference it without locking. |
1171 | */ |
1172 | return worker && worker->current_pwq->wq == wq; |
1173 | } |
1174 | |
1175 | static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
1176 | struct work_struct *work) |
1177 | { |
1178 | struct pool_workqueue *pwq; |
1179 | struct list_head *worklist; |
1180 | unsigned int work_flags; |
1181 | unsigned int req_cpu = cpu; |
1182 | |
1183 | /* |
1184 | * While a work item is PENDING && off queue, a task trying to |
1185 | * steal the PENDING will busy-loop waiting for it to either get |
1186 | * queued or lose PENDING. Grabbing PENDING and queueing should |
1187 | * happen with IRQ disabled. |
1188 | */ |
1189 | WARN_ON_ONCE(!irqs_disabled()); |
1190 | |
1191 | debug_work_activate(work); |
1192 | |
1193 | /* if dying, only works from the same workqueue are allowed */ |
1194 | if (unlikely(wq->flags & WQ_DRAINING) && |
1195 | WARN_ON_ONCE(!is_chained_work(wq))) |
1196 | return; |
1197 | |
1198 | /* determine the pwq to use */ |
1199 | if (!(wq->flags & WQ_UNBOUND)) { |
1200 | struct worker_pool *last_pool; |
1201 | |
1202 | if (cpu == WORK_CPU_UNBOUND) |
1203 | cpu = raw_smp_processor_id(); |
1204 | |
1205 | /* |
1206 | * It's multi cpu. If @work was previously on a different |
1207 | * cpu, it might still be running there, in which case the |
1208 | * work needs to be queued on that cpu to guarantee |
1209 | * non-reentrancy. |
1210 | */ |
1211 | pwq = get_pwq(cpu, wq); |
1212 | last_pool = get_work_pool(work); |
1213 | |
1214 | if (last_pool && last_pool != pwq->pool) { |
1215 | struct worker *worker; |
1216 | |
1217 | spin_lock(&last_pool->lock); |
1218 | |
1219 | worker = find_worker_executing_work(last_pool, work); |
1220 | |
1221 | if (worker && worker->current_pwq->wq == wq) { |
1222 | pwq = get_pwq(last_pool->cpu, wq); |
1223 | } else { |
1224 | /* meh... not running there, queue here */ |
1225 | spin_unlock(&last_pool->lock); |
1226 | spin_lock(&pwq->pool->lock); |
1227 | } |
1228 | } else { |
1229 | spin_lock(&pwq->pool->lock); |
1230 | } |
1231 | } else { |
1232 | pwq = get_pwq(WORK_CPU_UNBOUND, wq); |
1233 | spin_lock(&pwq->pool->lock); |
1234 | } |
1235 | |
1236 | /* pwq determined, queue */ |
1237 | trace_workqueue_queue_work(req_cpu, pwq, work); |
1238 | |
1239 | if (WARN_ON(!list_empty(&work->entry))) { |
1240 | spin_unlock(&pwq->pool->lock); |
1241 | return; |
1242 | } |
1243 | |
1244 | pwq->nr_in_flight[pwq->work_color]++; |
1245 | work_flags = work_color_to_flags(pwq->work_color); |
1246 | |
1247 | if (likely(pwq->nr_active < pwq->max_active)) { |
1248 | trace_workqueue_activate_work(work); |
1249 | pwq->nr_active++; |
1250 | worklist = &pwq->pool->worklist; |
1251 | } else { |
1252 | work_flags |= WORK_STRUCT_DELAYED; |
1253 | worklist = &pwq->delayed_works; |
1254 | } |
1255 | |
1256 | insert_work(pwq, work, worklist, work_flags); |
1257 | |
1258 | spin_unlock(&pwq->pool->lock); |
1259 | } |
1260 | |
1261 | /** |
1262 | * queue_work_on - queue work on specific cpu |
1263 | * @cpu: CPU number to execute work on |
1264 | * @wq: workqueue to use |
1265 | * @work: work to queue |
1266 | * |
1267 | * Returns %false if @work was already on a queue, %true otherwise. |
1268 | * |
1269 | * We queue the work to a specific CPU, the caller must ensure it |
1270 | * can't go away. |
1271 | */ |
1272 | bool queue_work_on(int cpu, struct workqueue_struct *wq, |
1273 | struct work_struct *work) |
1274 | { |
1275 | bool ret = false; |
1276 | unsigned long flags; |
1277 | |
1278 | local_irq_save(flags); |
1279 | |
1280 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1281 | __queue_work(cpu, wq, work); |
1282 | ret = true; |
1283 | } |
1284 | |
1285 | local_irq_restore(flags); |
1286 | return ret; |
1287 | } |
1288 | EXPORT_SYMBOL_GPL(queue_work_on); |
1289 | |
1290 | /** |
1291 | * queue_work - queue work on a workqueue |
1292 | * @wq: workqueue to use |
1293 | * @work: work to queue |
1294 | * |
1295 | * Returns %false if @work was already on a queue, %true otherwise. |
1296 | * |
1297 | * We queue the work to the CPU on which it was submitted, but if the CPU dies |
1298 | * it can be processed by another CPU. |
1299 | */ |
1300 | bool queue_work(struct workqueue_struct *wq, struct work_struct *work) |
1301 | { |
1302 | return queue_work_on(WORK_CPU_UNBOUND, wq, work); |
1303 | } |
1304 | EXPORT_SYMBOL_GPL(queue_work); |
1305 | |
1306 | void delayed_work_timer_fn(unsigned long __data) |
1307 | { |
1308 | struct delayed_work *dwork = (struct delayed_work *)__data; |
1309 | |
1310 | /* should have been called from irqsafe timer with irq already off */ |
1311 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); |
1312 | } |
1313 | EXPORT_SYMBOL(delayed_work_timer_fn); |
1314 | |
1315 | static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, |
1316 | struct delayed_work *dwork, unsigned long delay) |
1317 | { |
1318 | struct timer_list *timer = &dwork->timer; |
1319 | struct work_struct *work = &dwork->work; |
1320 | |
1321 | WARN_ON_ONCE(timer->function != delayed_work_timer_fn || |
1322 | timer->data != (unsigned long)dwork); |
1323 | WARN_ON_ONCE(timer_pending(timer)); |
1324 | WARN_ON_ONCE(!list_empty(&work->entry)); |
1325 | |
1326 | /* |
1327 | * If @delay is 0, queue @dwork->work immediately. This is for |
1328 | * both optimization and correctness. The earliest @timer can |
1329 | * expire is on the closest next tick and delayed_work users depend |
1330 | * on that there's no such delay when @delay is 0. |
1331 | */ |
1332 | if (!delay) { |
1333 | __queue_work(cpu, wq, &dwork->work); |
1334 | return; |
1335 | } |
1336 | |
1337 | timer_stats_timer_set_start_info(&dwork->timer); |
1338 | |
1339 | dwork->wq = wq; |
1340 | dwork->cpu = cpu; |
1341 | timer->expires = jiffies + delay; |
1342 | |
1343 | if (unlikely(cpu != WORK_CPU_UNBOUND)) |
1344 | add_timer_on(timer, cpu); |
1345 | else |
1346 | add_timer(timer); |
1347 | } |
1348 | |
1349 | /** |
1350 | * queue_delayed_work_on - queue work on specific CPU after delay |
1351 | * @cpu: CPU number to execute work on |
1352 | * @wq: workqueue to use |
1353 | * @dwork: work to queue |
1354 | * @delay: number of jiffies to wait before queueing |
1355 | * |
1356 | * Returns %false if @work was already on a queue, %true otherwise. If |
1357 | * @delay is zero and @dwork is idle, it will be scheduled for immediate |
1358 | * execution. |
1359 | */ |
1360 | bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1361 | struct delayed_work *dwork, unsigned long delay) |
1362 | { |
1363 | struct work_struct *work = &dwork->work; |
1364 | bool ret = false; |
1365 | unsigned long flags; |
1366 | |
1367 | /* read the comment in __queue_work() */ |
1368 | local_irq_save(flags); |
1369 | |
1370 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1371 | __queue_delayed_work(cpu, wq, dwork, delay); |
1372 | ret = true; |
1373 | } |
1374 | |
1375 | local_irq_restore(flags); |
1376 | return ret; |
1377 | } |
1378 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
1379 | |
1380 | /** |
1381 | * queue_delayed_work - queue work on a workqueue after delay |
1382 | * @wq: workqueue to use |
1383 | * @dwork: delayable work to queue |
1384 | * @delay: number of jiffies to wait before queueing |
1385 | * |
1386 | * Equivalent to queue_delayed_work_on() but tries to use the local CPU. |
1387 | */ |
1388 | bool queue_delayed_work(struct workqueue_struct *wq, |
1389 | struct delayed_work *dwork, unsigned long delay) |
1390 | { |
1391 | return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); |
1392 | } |
1393 | EXPORT_SYMBOL_GPL(queue_delayed_work); |
1394 | |
1395 | /** |
1396 | * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU |
1397 | * @cpu: CPU number to execute work on |
1398 | * @wq: workqueue to use |
1399 | * @dwork: work to queue |
1400 | * @delay: number of jiffies to wait before queueing |
1401 | * |
1402 | * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, |
1403 | * modify @dwork's timer so that it expires after @delay. If @delay is |
1404 | * zero, @work is guaranteed to be scheduled immediately regardless of its |
1405 | * current state. |
1406 | * |
1407 | * Returns %false if @dwork was idle and queued, %true if @dwork was |
1408 | * pending and its timer was modified. |
1409 | * |
1410 | * This function is safe to call from any context including IRQ handler. |
1411 | * See try_to_grab_pending() for details. |
1412 | */ |
1413 | bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1414 | struct delayed_work *dwork, unsigned long delay) |
1415 | { |
1416 | unsigned long flags; |
1417 | int ret; |
1418 | |
1419 | do { |
1420 | ret = try_to_grab_pending(&dwork->work, true, &flags); |
1421 | } while (unlikely(ret == -EAGAIN)); |
1422 | |
1423 | if (likely(ret >= 0)) { |
1424 | __queue_delayed_work(cpu, wq, dwork, delay); |
1425 | local_irq_restore(flags); |
1426 | } |
1427 | |
1428 | /* -ENOENT from try_to_grab_pending() becomes %true */ |
1429 | return ret; |
1430 | } |
1431 | EXPORT_SYMBOL_GPL(mod_delayed_work_on); |
1432 | |
1433 | /** |
1434 | * mod_delayed_work - modify delay of or queue a delayed work |
1435 | * @wq: workqueue to use |
1436 | * @dwork: work to queue |
1437 | * @delay: number of jiffies to wait before queueing |
1438 | * |
1439 | * mod_delayed_work_on() on local CPU. |
1440 | */ |
1441 | bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork, |
1442 | unsigned long delay) |
1443 | { |
1444 | return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); |
1445 | } |
1446 | EXPORT_SYMBOL_GPL(mod_delayed_work); |
1447 | |
1448 | /** |
1449 | * worker_enter_idle - enter idle state |
1450 | * @worker: worker which is entering idle state |
1451 | * |
1452 | * @worker is entering idle state. Update stats and idle timer if |
1453 | * necessary. |
1454 | * |
1455 | * LOCKING: |
1456 | * spin_lock_irq(pool->lock). |
1457 | */ |
1458 | static void worker_enter_idle(struct worker *worker) |
1459 | { |
1460 | struct worker_pool *pool = worker->pool; |
1461 | |
1462 | BUG_ON(worker->flags & WORKER_IDLE); |
1463 | BUG_ON(!list_empty(&worker->entry) && |
1464 | (worker->hentry.next || worker->hentry.pprev)); |
1465 | |
1466 | /* can't use worker_set_flags(), also called from start_worker() */ |
1467 | worker->flags |= WORKER_IDLE; |
1468 | pool->nr_idle++; |
1469 | worker->last_active = jiffies; |
1470 | |
1471 | /* idle_list is LIFO */ |
1472 | list_add(&worker->entry, &pool->idle_list); |
1473 | |
1474 | if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) |
1475 | mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); |
1476 | |
1477 | /* |
1478 | * Sanity check nr_running. Because wq_unbind_fn() releases |
1479 | * pool->lock between setting %WORKER_UNBOUND and zapping |
1480 | * nr_running, the warning may trigger spuriously. Check iff |
1481 | * unbind is not in progress. |
1482 | */ |
1483 | WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && |
1484 | pool->nr_workers == pool->nr_idle && |
1485 | atomic_read(&pool->nr_running)); |
1486 | } |
1487 | |
1488 | /** |
1489 | * worker_leave_idle - leave idle state |
1490 | * @worker: worker which is leaving idle state |
1491 | * |
1492 | * @worker is leaving idle state. Update stats. |
1493 | * |
1494 | * LOCKING: |
1495 | * spin_lock_irq(pool->lock). |
1496 | */ |
1497 | static void worker_leave_idle(struct worker *worker) |
1498 | { |
1499 | struct worker_pool *pool = worker->pool; |
1500 | |
1501 | BUG_ON(!(worker->flags & WORKER_IDLE)); |
1502 | worker_clr_flags(worker, WORKER_IDLE); |
1503 | pool->nr_idle--; |
1504 | list_del_init(&worker->entry); |
1505 | } |
1506 | |
1507 | /** |
1508 | * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock pool |
1509 | * @worker: self |
1510 | * |
1511 | * Works which are scheduled while the cpu is online must at least be |
1512 | * scheduled to a worker which is bound to the cpu so that if they are |
1513 | * flushed from cpu callbacks while cpu is going down, they are |
1514 | * guaranteed to execute on the cpu. |
1515 | * |
1516 | * This function is to be used by rogue workers and rescuers to bind |
1517 | * themselves to the target cpu and may race with cpu going down or |
1518 | * coming online. kthread_bind() can't be used because it may put the |
1519 | * worker to already dead cpu and set_cpus_allowed_ptr() can't be used |
1520 | * verbatim as it's best effort and blocking and pool may be |
1521 | * [dis]associated in the meantime. |
1522 | * |
1523 | * This function tries set_cpus_allowed() and locks pool and verifies the |
1524 | * binding against %POOL_DISASSOCIATED which is set during |
1525 | * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker |
1526 | * enters idle state or fetches works without dropping lock, it can |
1527 | * guarantee the scheduling requirement described in the first paragraph. |
1528 | * |
1529 | * CONTEXT: |
1530 | * Might sleep. Called without any lock but returns with pool->lock |
1531 | * held. |
1532 | * |
1533 | * RETURNS: |
1534 | * %true if the associated pool is online (@worker is successfully |
1535 | * bound), %false if offline. |
1536 | */ |
1537 | static bool worker_maybe_bind_and_lock(struct worker *worker) |
1538 | __acquires(&pool->lock) |
1539 | { |
1540 | struct worker_pool *pool = worker->pool; |
1541 | struct task_struct *task = worker->task; |
1542 | |
1543 | while (true) { |
1544 | /* |
1545 | * The following call may fail, succeed or succeed |
1546 | * without actually migrating the task to the cpu if |
1547 | * it races with cpu hotunplug operation. Verify |
1548 | * against POOL_DISASSOCIATED. |
1549 | */ |
1550 | if (!(pool->flags & POOL_DISASSOCIATED)) |
1551 | set_cpus_allowed_ptr(task, get_cpu_mask(pool->cpu)); |
1552 | |
1553 | spin_lock_irq(&pool->lock); |
1554 | if (pool->flags & POOL_DISASSOCIATED) |
1555 | return false; |
1556 | if (task_cpu(task) == pool->cpu && |
1557 | cpumask_equal(¤t->cpus_allowed, |
1558 | get_cpu_mask(pool->cpu))) |
1559 | return true; |
1560 | spin_unlock_irq(&pool->lock); |
1561 | |
1562 | /* |
1563 | * We've raced with CPU hot[un]plug. Give it a breather |
1564 | * and retry migration. cond_resched() is required here; |
1565 | * otherwise, we might deadlock against cpu_stop trying to |
1566 | * bring down the CPU on non-preemptive kernel. |
1567 | */ |
1568 | cpu_relax(); |
1569 | cond_resched(); |
1570 | } |
1571 | } |
1572 | |
1573 | /* |
1574 | * Rebind an idle @worker to its CPU. worker_thread() will test |
1575 | * list_empty(@worker->entry) before leaving idle and call this function. |
1576 | */ |
1577 | static void idle_worker_rebind(struct worker *worker) |
1578 | { |
1579 | /* CPU may go down again inbetween, clear UNBOUND only on success */ |
1580 | if (worker_maybe_bind_and_lock(worker)) |
1581 | worker_clr_flags(worker, WORKER_UNBOUND); |
1582 | |
1583 | /* rebind complete, become available again */ |
1584 | list_add(&worker->entry, &worker->pool->idle_list); |
1585 | spin_unlock_irq(&worker->pool->lock); |
1586 | } |
1587 | |
1588 | /* |
1589 | * Function for @worker->rebind.work used to rebind unbound busy workers to |
1590 | * the associated cpu which is coming back online. This is scheduled by |
1591 | * cpu up but can race with other cpu hotplug operations and may be |
1592 | * executed twice without intervening cpu down. |
1593 | */ |
1594 | static void busy_worker_rebind_fn(struct work_struct *work) |
1595 | { |
1596 | struct worker *worker = container_of(work, struct worker, rebind_work); |
1597 | |
1598 | if (worker_maybe_bind_and_lock(worker)) |
1599 | worker_clr_flags(worker, WORKER_UNBOUND); |
1600 | |
1601 | spin_unlock_irq(&worker->pool->lock); |
1602 | } |
1603 | |
1604 | /** |
1605 | * rebind_workers - rebind all workers of a pool to the associated CPU |
1606 | * @pool: pool of interest |
1607 | * |
1608 | * @pool->cpu is coming online. Rebind all workers to the CPU. Rebinding |
1609 | * is different for idle and busy ones. |
1610 | * |
1611 | * Idle ones will be removed from the idle_list and woken up. They will |
1612 | * add themselves back after completing rebind. This ensures that the |
1613 | * idle_list doesn't contain any unbound workers when re-bound busy workers |
1614 | * try to perform local wake-ups for concurrency management. |
1615 | * |
1616 | * Busy workers can rebind after they finish their current work items. |
1617 | * Queueing the rebind work item at the head of the scheduled list is |
1618 | * enough. Note that nr_running will be properly bumped as busy workers |
1619 | * rebind. |
1620 | * |
1621 | * On return, all non-manager workers are scheduled for rebind - see |
1622 | * manage_workers() for the manager special case. Any idle worker |
1623 | * including the manager will not appear on @idle_list until rebind is |
1624 | * complete, making local wake-ups safe. |
1625 | */ |
1626 | static void rebind_workers(struct worker_pool *pool) |
1627 | { |
1628 | struct worker *worker, *n; |
1629 | int i; |
1630 | |
1631 | lockdep_assert_held(&pool->assoc_mutex); |
1632 | lockdep_assert_held(&pool->lock); |
1633 | |
1634 | /* dequeue and kick idle ones */ |
1635 | list_for_each_entry_safe(worker, n, &pool->idle_list, entry) { |
1636 | /* |
1637 | * idle workers should be off @pool->idle_list until rebind |
1638 | * is complete to avoid receiving premature local wake-ups. |
1639 | */ |
1640 | list_del_init(&worker->entry); |
1641 | |
1642 | /* |
1643 | * worker_thread() will see the above dequeuing and call |
1644 | * idle_worker_rebind(). |
1645 | */ |
1646 | wake_up_process(worker->task); |
1647 | } |
1648 | |
1649 | /* rebind busy workers */ |
1650 | for_each_busy_worker(worker, i, pool) { |
1651 | struct work_struct *rebind_work = &worker->rebind_work; |
1652 | struct workqueue_struct *wq; |
1653 | |
1654 | if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, |
1655 | work_data_bits(rebind_work))) |
1656 | continue; |
1657 | |
1658 | debug_work_activate(rebind_work); |
1659 | |
1660 | /* |
1661 | * wq doesn't really matter but let's keep @worker->pool |
1662 | * and @pwq->pool consistent for sanity. |
1663 | */ |
1664 | if (std_worker_pool_pri(worker->pool)) |
1665 | wq = system_highpri_wq; |
1666 | else |
1667 | wq = system_wq; |
1668 | |
1669 | insert_work(get_pwq(pool->cpu, wq), rebind_work, |
1670 | worker->scheduled.next, |
1671 | work_color_to_flags(WORK_NO_COLOR)); |
1672 | } |
1673 | } |
1674 | |
1675 | static struct worker *alloc_worker(void) |
1676 | { |
1677 | struct worker *worker; |
1678 | |
1679 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
1680 | if (worker) { |
1681 | INIT_LIST_HEAD(&worker->entry); |
1682 | INIT_LIST_HEAD(&worker->scheduled); |
1683 | INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn); |
1684 | /* on creation a worker is in !idle && prep state */ |
1685 | worker->flags = WORKER_PREP; |
1686 | } |
1687 | return worker; |
1688 | } |
1689 | |
1690 | /** |
1691 | * create_worker - create a new workqueue worker |
1692 | * @pool: pool the new worker will belong to |
1693 | * |
1694 | * Create a new worker which is bound to @pool. The returned worker |
1695 | * can be started by calling start_worker() or destroyed using |
1696 | * destroy_worker(). |
1697 | * |
1698 | * CONTEXT: |
1699 | * Might sleep. Does GFP_KERNEL allocations. |
1700 | * |
1701 | * RETURNS: |
1702 | * Pointer to the newly created worker. |
1703 | */ |
1704 | static struct worker *create_worker(struct worker_pool *pool) |
1705 | { |
1706 | const char *pri = std_worker_pool_pri(pool) ? "H" : ""; |
1707 | struct worker *worker = NULL; |
1708 | int id = -1; |
1709 | |
1710 | spin_lock_irq(&pool->lock); |
1711 | while (ida_get_new(&pool->worker_ida, &id)) { |
1712 | spin_unlock_irq(&pool->lock); |
1713 | if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL)) |
1714 | goto fail; |
1715 | spin_lock_irq(&pool->lock); |
1716 | } |
1717 | spin_unlock_irq(&pool->lock); |
1718 | |
1719 | worker = alloc_worker(); |
1720 | if (!worker) |
1721 | goto fail; |
1722 | |
1723 | worker->pool = pool; |
1724 | worker->id = id; |
1725 | |
1726 | if (pool->cpu != WORK_CPU_UNBOUND) |
1727 | worker->task = kthread_create_on_node(worker_thread, |
1728 | worker, cpu_to_node(pool->cpu), |
1729 | "kworker/%u:%d%s", pool->cpu, id, pri); |
1730 | else |
1731 | worker->task = kthread_create(worker_thread, worker, |
1732 | "kworker/u:%d%s", id, pri); |
1733 | if (IS_ERR(worker->task)) |
1734 | goto fail; |
1735 | |
1736 | if (std_worker_pool_pri(pool)) |
1737 | set_user_nice(worker->task, HIGHPRI_NICE_LEVEL); |
1738 | |
1739 | /* |
1740 | * Determine CPU binding of the new worker depending on |
1741 | * %POOL_DISASSOCIATED. The caller is responsible for ensuring the |
1742 | * flag remains stable across this function. See the comments |
1743 | * above the flag definition for details. |
1744 | * |
1745 | * As an unbound worker may later become a regular one if CPU comes |
1746 | * online, make sure every worker has %PF_THREAD_BOUND set. |
1747 | */ |
1748 | if (!(pool->flags & POOL_DISASSOCIATED)) { |
1749 | kthread_bind(worker->task, pool->cpu); |
1750 | } else { |
1751 | worker->task->flags |= PF_THREAD_BOUND; |
1752 | worker->flags |= WORKER_UNBOUND; |
1753 | } |
1754 | |
1755 | return worker; |
1756 | fail: |
1757 | if (id >= 0) { |
1758 | spin_lock_irq(&pool->lock); |
1759 | ida_remove(&pool->worker_ida, id); |
1760 | spin_unlock_irq(&pool->lock); |
1761 | } |
1762 | kfree(worker); |
1763 | return NULL; |
1764 | } |
1765 | |
1766 | /** |
1767 | * start_worker - start a newly created worker |
1768 | * @worker: worker to start |
1769 | * |
1770 | * Make the pool aware of @worker and start it. |
1771 | * |
1772 | * CONTEXT: |
1773 | * spin_lock_irq(pool->lock). |
1774 | */ |
1775 | static void start_worker(struct worker *worker) |
1776 | { |
1777 | worker->flags |= WORKER_STARTED; |
1778 | worker->pool->nr_workers++; |
1779 | worker_enter_idle(worker); |
1780 | wake_up_process(worker->task); |
1781 | } |
1782 | |
1783 | /** |
1784 | * destroy_worker - destroy a workqueue worker |
1785 | * @worker: worker to be destroyed |
1786 | * |
1787 | * Destroy @worker and adjust @pool stats accordingly. |
1788 | * |
1789 | * CONTEXT: |
1790 | * spin_lock_irq(pool->lock) which is released and regrabbed. |
1791 | */ |
1792 | static void destroy_worker(struct worker *worker) |
1793 | { |
1794 | struct worker_pool *pool = worker->pool; |
1795 | int id = worker->id; |
1796 | |
1797 | /* sanity check frenzy */ |
1798 | BUG_ON(worker->current_work); |
1799 | BUG_ON(!list_empty(&worker->scheduled)); |
1800 | |
1801 | if (worker->flags & WORKER_STARTED) |
1802 | pool->nr_workers--; |
1803 | if (worker->flags & WORKER_IDLE) |
1804 | pool->nr_idle--; |
1805 | |
1806 | list_del_init(&worker->entry); |
1807 | worker->flags |= WORKER_DIE; |
1808 | |
1809 | spin_unlock_irq(&pool->lock); |
1810 | |
1811 | kthread_stop(worker->task); |
1812 | kfree(worker); |
1813 | |
1814 | spin_lock_irq(&pool->lock); |
1815 | ida_remove(&pool->worker_ida, id); |
1816 | } |
1817 | |
1818 | static void idle_worker_timeout(unsigned long __pool) |
1819 | { |
1820 | struct worker_pool *pool = (void *)__pool; |
1821 | |
1822 | spin_lock_irq(&pool->lock); |
1823 | |
1824 | if (too_many_workers(pool)) { |
1825 | struct worker *worker; |
1826 | unsigned long expires; |
1827 | |
1828 | /* idle_list is kept in LIFO order, check the last one */ |
1829 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
1830 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1831 | |
1832 | if (time_before(jiffies, expires)) |
1833 | mod_timer(&pool->idle_timer, expires); |
1834 | else { |
1835 | /* it's been idle for too long, wake up manager */ |
1836 | pool->flags |= POOL_MANAGE_WORKERS; |
1837 | wake_up_worker(pool); |
1838 | } |
1839 | } |
1840 | |
1841 | spin_unlock_irq(&pool->lock); |
1842 | } |
1843 | |
1844 | static bool send_mayday(struct work_struct *work) |
1845 | { |
1846 | struct pool_workqueue *pwq = get_work_pwq(work); |
1847 | struct workqueue_struct *wq = pwq->wq; |
1848 | unsigned int cpu; |
1849 | |
1850 | if (!(wq->flags & WQ_RESCUER)) |
1851 | return false; |
1852 | |
1853 | /* mayday mayday mayday */ |
1854 | cpu = pwq->pool->cpu; |
1855 | /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ |
1856 | if (cpu == WORK_CPU_UNBOUND) |
1857 | cpu = 0; |
1858 | if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) |
1859 | wake_up_process(wq->rescuer->task); |
1860 | return true; |
1861 | } |
1862 | |
1863 | static void pool_mayday_timeout(unsigned long __pool) |
1864 | { |
1865 | struct worker_pool *pool = (void *)__pool; |
1866 | struct work_struct *work; |
1867 | |
1868 | spin_lock_irq(&pool->lock); |
1869 | |
1870 | if (need_to_create_worker(pool)) { |
1871 | /* |
1872 | * We've been trying to create a new worker but |
1873 | * haven't been successful. We might be hitting an |
1874 | * allocation deadlock. Send distress signals to |
1875 | * rescuers. |
1876 | */ |
1877 | list_for_each_entry(work, &pool->worklist, entry) |
1878 | send_mayday(work); |
1879 | } |
1880 | |
1881 | spin_unlock_irq(&pool->lock); |
1882 | |
1883 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); |
1884 | } |
1885 | |
1886 | /** |
1887 | * maybe_create_worker - create a new worker if necessary |
1888 | * @pool: pool to create a new worker for |
1889 | * |
1890 | * Create a new worker for @pool if necessary. @pool is guaranteed to |
1891 | * have at least one idle worker on return from this function. If |
1892 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
1893 | * sent to all rescuers with works scheduled on @pool to resolve |
1894 | * possible allocation deadlock. |
1895 | * |
1896 | * On return, need_to_create_worker() is guaranteed to be false and |
1897 | * may_start_working() true. |
1898 | * |
1899 | * LOCKING: |
1900 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
1901 | * multiple times. Does GFP_KERNEL allocations. Called only from |
1902 | * manager. |
1903 | * |
1904 | * RETURNS: |
1905 | * false if no action was taken and pool->lock stayed locked, true |
1906 | * otherwise. |
1907 | */ |
1908 | static bool maybe_create_worker(struct worker_pool *pool) |
1909 | __releases(&pool->lock) |
1910 | __acquires(&pool->lock) |
1911 | { |
1912 | if (!need_to_create_worker(pool)) |
1913 | return false; |
1914 | restart: |
1915 | spin_unlock_irq(&pool->lock); |
1916 | |
1917 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
1918 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
1919 | |
1920 | while (true) { |
1921 | struct worker *worker; |
1922 | |
1923 | worker = create_worker(pool); |
1924 | if (worker) { |
1925 | del_timer_sync(&pool->mayday_timer); |
1926 | spin_lock_irq(&pool->lock); |
1927 | start_worker(worker); |
1928 | BUG_ON(need_to_create_worker(pool)); |
1929 | return true; |
1930 | } |
1931 | |
1932 | if (!need_to_create_worker(pool)) |
1933 | break; |
1934 | |
1935 | __set_current_state(TASK_INTERRUPTIBLE); |
1936 | schedule_timeout(CREATE_COOLDOWN); |
1937 | |
1938 | if (!need_to_create_worker(pool)) |
1939 | break; |
1940 | } |
1941 | |
1942 | del_timer_sync(&pool->mayday_timer); |
1943 | spin_lock_irq(&pool->lock); |
1944 | if (need_to_create_worker(pool)) |
1945 | goto restart; |
1946 | return true; |
1947 | } |
1948 | |
1949 | /** |
1950 | * maybe_destroy_worker - destroy workers which have been idle for a while |
1951 | * @pool: pool to destroy workers for |
1952 | * |
1953 | * Destroy @pool workers which have been idle for longer than |
1954 | * IDLE_WORKER_TIMEOUT. |
1955 | * |
1956 | * LOCKING: |
1957 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
1958 | * multiple times. Called only from manager. |
1959 | * |
1960 | * RETURNS: |
1961 | * false if no action was taken and pool->lock stayed locked, true |
1962 | * otherwise. |
1963 | */ |
1964 | static bool maybe_destroy_workers(struct worker_pool *pool) |
1965 | { |
1966 | bool ret = false; |
1967 | |
1968 | while (too_many_workers(pool)) { |
1969 | struct worker *worker; |
1970 | unsigned long expires; |
1971 | |
1972 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
1973 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1974 | |
1975 | if (time_before(jiffies, expires)) { |
1976 | mod_timer(&pool->idle_timer, expires); |
1977 | break; |
1978 | } |
1979 | |
1980 | destroy_worker(worker); |
1981 | ret = true; |
1982 | } |
1983 | |
1984 | return ret; |
1985 | } |
1986 | |
1987 | /** |
1988 | * manage_workers - manage worker pool |
1989 | * @worker: self |
1990 | * |
1991 | * Assume the manager role and manage the worker pool @worker belongs |
1992 | * to. At any given time, there can be only zero or one manager per |
1993 | * pool. The exclusion is handled automatically by this function. |
1994 | * |
1995 | * The caller can safely start processing works on false return. On |
1996 | * true return, it's guaranteed that need_to_create_worker() is false |
1997 | * and may_start_working() is true. |
1998 | * |
1999 | * CONTEXT: |
2000 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
2001 | * multiple times. Does GFP_KERNEL allocations. |
2002 | * |
2003 | * RETURNS: |
2004 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
2005 | * multiple times. Does GFP_KERNEL allocations. |
2006 | */ |
2007 | static bool manage_workers(struct worker *worker) |
2008 | { |
2009 | struct worker_pool *pool = worker->pool; |
2010 | bool ret = false; |
2011 | |
2012 | if (pool->flags & POOL_MANAGING_WORKERS) |
2013 | return ret; |
2014 | |
2015 | pool->flags |= POOL_MANAGING_WORKERS; |
2016 | |
2017 | /* |
2018 | * To simplify both worker management and CPU hotplug, hold off |
2019 | * management while hotplug is in progress. CPU hotplug path can't |
2020 | * grab %POOL_MANAGING_WORKERS to achieve this because that can |
2021 | * lead to idle worker depletion (all become busy thinking someone |
2022 | * else is managing) which in turn can result in deadlock under |
2023 | * extreme circumstances. Use @pool->assoc_mutex to synchronize |
2024 | * manager against CPU hotplug. |
2025 | * |
2026 | * assoc_mutex would always be free unless CPU hotplug is in |
2027 | * progress. trylock first without dropping @pool->lock. |
2028 | */ |
2029 | if (unlikely(!mutex_trylock(&pool->assoc_mutex))) { |
2030 | spin_unlock_irq(&pool->lock); |
2031 | mutex_lock(&pool->assoc_mutex); |
2032 | /* |
2033 | * CPU hotplug could have happened while we were waiting |
2034 | * for assoc_mutex. Hotplug itself can't handle us |
2035 | * because manager isn't either on idle or busy list, and |
2036 | * @pool's state and ours could have deviated. |
2037 | * |
2038 | * As hotplug is now excluded via assoc_mutex, we can |
2039 | * simply try to bind. It will succeed or fail depending |
2040 | * on @pool's current state. Try it and adjust |
2041 | * %WORKER_UNBOUND accordingly. |
2042 | */ |
2043 | if (worker_maybe_bind_and_lock(worker)) |
2044 | worker->flags &= ~WORKER_UNBOUND; |
2045 | else |
2046 | worker->flags |= WORKER_UNBOUND; |
2047 | |
2048 | ret = true; |
2049 | } |
2050 | |
2051 | pool->flags &= ~POOL_MANAGE_WORKERS; |
2052 | |
2053 | /* |
2054 | * Destroy and then create so that may_start_working() is true |
2055 | * on return. |
2056 | */ |
2057 | ret |= maybe_destroy_workers(pool); |
2058 | ret |= maybe_create_worker(pool); |
2059 | |
2060 | pool->flags &= ~POOL_MANAGING_WORKERS; |
2061 | mutex_unlock(&pool->assoc_mutex); |
2062 | return ret; |
2063 | } |
2064 | |
2065 | /** |
2066 | * process_one_work - process single work |
2067 | * @worker: self |
2068 | * @work: work to process |
2069 | * |
2070 | * Process @work. This function contains all the logics necessary to |
2071 | * process a single work including synchronization against and |
2072 | * interaction with other workers on the same cpu, queueing and |
2073 | * flushing. As long as context requirement is met, any worker can |
2074 | * call this function to process a work. |
2075 | * |
2076 | * CONTEXT: |
2077 | * spin_lock_irq(pool->lock) which is released and regrabbed. |
2078 | */ |
2079 | static void process_one_work(struct worker *worker, struct work_struct *work) |
2080 | __releases(&pool->lock) |
2081 | __acquires(&pool->lock) |
2082 | { |
2083 | struct pool_workqueue *pwq = get_work_pwq(work); |
2084 | struct worker_pool *pool = worker->pool; |
2085 | bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; |
2086 | int work_color; |
2087 | struct worker *collision; |
2088 | #ifdef CONFIG_LOCKDEP |
2089 | /* |
2090 | * It is permissible to free the struct work_struct from |
2091 | * inside the function that is called from it, this we need to |
2092 | * take into account for lockdep too. To avoid bogus "held |
2093 | * lock freed" warnings as well as problems when looking into |
2094 | * work->lockdep_map, make a copy and use that here. |
2095 | */ |
2096 | struct lockdep_map lockdep_map; |
2097 | |
2098 | lockdep_copy_map(&lockdep_map, &work->lockdep_map); |
2099 | #endif |
2100 | /* |
2101 | * Ensure we're on the correct CPU. DISASSOCIATED test is |
2102 | * necessary to avoid spurious warnings from rescuers servicing the |
2103 | * unbound or a disassociated pool. |
2104 | */ |
2105 | WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && |
2106 | !(pool->flags & POOL_DISASSOCIATED) && |
2107 | raw_smp_processor_id() != pool->cpu); |
2108 | |
2109 | /* |
2110 | * A single work shouldn't be executed concurrently by |
2111 | * multiple workers on a single cpu. Check whether anyone is |
2112 | * already processing the work. If so, defer the work to the |
2113 | * currently executing one. |
2114 | */ |
2115 | collision = find_worker_executing_work(pool, work); |
2116 | if (unlikely(collision)) { |
2117 | move_linked_works(work, &collision->scheduled, NULL); |
2118 | return; |
2119 | } |
2120 | |
2121 | /* claim and dequeue */ |
2122 | debug_work_deactivate(work); |
2123 | hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); |
2124 | worker->current_work = work; |
2125 | worker->current_func = work->func; |
2126 | worker->current_pwq = pwq; |
2127 | work_color = get_work_color(work); |
2128 | |
2129 | list_del_init(&work->entry); |
2130 | |
2131 | /* |
2132 | * CPU intensive works don't participate in concurrency |
2133 | * management. They're the scheduler's responsibility. |
2134 | */ |
2135 | if (unlikely(cpu_intensive)) |
2136 | worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); |
2137 | |
2138 | /* |
2139 | * Unbound pool isn't concurrency managed and work items should be |
2140 | * executed ASAP. Wake up another worker if necessary. |
2141 | */ |
2142 | if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) |
2143 | wake_up_worker(pool); |
2144 | |
2145 | /* |
2146 | * Record the last pool and clear PENDING which should be the last |
2147 | * update to @work. Also, do this inside @pool->lock so that |
2148 | * PENDING and queued state changes happen together while IRQ is |
2149 | * disabled. |
2150 | */ |
2151 | set_work_pool_and_clear_pending(work, pool->id); |
2152 | |
2153 | spin_unlock_irq(&pool->lock); |
2154 | |
2155 | lock_map_acquire_read(&pwq->wq->lockdep_map); |
2156 | lock_map_acquire(&lockdep_map); |
2157 | trace_workqueue_execute_start(work); |
2158 | worker->current_func(work); |
2159 | /* |
2160 | * While we must be careful to not use "work" after this, the trace |
2161 | * point will only record its address. |
2162 | */ |
2163 | trace_workqueue_execute_end(work); |
2164 | lock_map_release(&lockdep_map); |
2165 | lock_map_release(&pwq->wq->lockdep_map); |
2166 | |
2167 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
2168 | pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" |
2169 | " last function: %pf\n", |
2170 | current->comm, preempt_count(), task_pid_nr(current), |
2171 | worker->current_func); |
2172 | debug_show_held_locks(current); |
2173 | dump_stack(); |
2174 | } |
2175 | |
2176 | spin_lock_irq(&pool->lock); |
2177 | |
2178 | /* clear cpu intensive status */ |
2179 | if (unlikely(cpu_intensive)) |
2180 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); |
2181 | |
2182 | /* we're done with it, release */ |
2183 | hash_del(&worker->hentry); |
2184 | worker->current_work = NULL; |
2185 | worker->current_func = NULL; |
2186 | worker->current_pwq = NULL; |
2187 | pwq_dec_nr_in_flight(pwq, work_color); |
2188 | } |
2189 | |
2190 | /** |
2191 | * process_scheduled_works - process scheduled works |
2192 | * @worker: self |
2193 | * |
2194 | * Process all scheduled works. Please note that the scheduled list |
2195 | * may change while processing a work, so this function repeatedly |
2196 | * fetches a work from the top and executes it. |
2197 | * |
2198 | * CONTEXT: |
2199 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
2200 | * multiple times. |
2201 | */ |
2202 | static void process_scheduled_works(struct worker *worker) |
2203 | { |
2204 | while (!list_empty(&worker->scheduled)) { |
2205 | struct work_struct *work = list_first_entry(&worker->scheduled, |
2206 | struct work_struct, entry); |
2207 | process_one_work(worker, work); |
2208 | } |
2209 | } |
2210 | |
2211 | /** |
2212 | * worker_thread - the worker thread function |
2213 | * @__worker: self |
2214 | * |
2215 | * The worker thread function. There are NR_CPU_WORKER_POOLS dynamic pools |
2216 | * of these per each cpu. These workers process all works regardless of |
2217 | * their specific target workqueue. The only exception is works which |
2218 | * belong to workqueues with a rescuer which will be explained in |
2219 | * rescuer_thread(). |
2220 | */ |
2221 | static int worker_thread(void *__worker) |
2222 | { |
2223 | struct worker *worker = __worker; |
2224 | struct worker_pool *pool = worker->pool; |
2225 | |
2226 | /* tell the scheduler that this is a workqueue worker */ |
2227 | worker->task->flags |= PF_WQ_WORKER; |
2228 | woke_up: |
2229 | spin_lock_irq(&pool->lock); |
2230 | |
2231 | /* we are off idle list if destruction or rebind is requested */ |
2232 | if (unlikely(list_empty(&worker->entry))) { |
2233 | spin_unlock_irq(&pool->lock); |
2234 | |
2235 | /* if DIE is set, destruction is requested */ |
2236 | if (worker->flags & WORKER_DIE) { |
2237 | worker->task->flags &= ~PF_WQ_WORKER; |
2238 | return 0; |
2239 | } |
2240 | |
2241 | /* otherwise, rebind */ |
2242 | idle_worker_rebind(worker); |
2243 | goto woke_up; |
2244 | } |
2245 | |
2246 | worker_leave_idle(worker); |
2247 | recheck: |
2248 | /* no more worker necessary? */ |
2249 | if (!need_more_worker(pool)) |
2250 | goto sleep; |
2251 | |
2252 | /* do we need to manage? */ |
2253 | if (unlikely(!may_start_working(pool)) && manage_workers(worker)) |
2254 | goto recheck; |
2255 | |
2256 | /* |
2257 | * ->scheduled list can only be filled while a worker is |
2258 | * preparing to process a work or actually processing it. |
2259 | * Make sure nobody diddled with it while I was sleeping. |
2260 | */ |
2261 | BUG_ON(!list_empty(&worker->scheduled)); |
2262 | |
2263 | /* |
2264 | * When control reaches this point, we're guaranteed to have |
2265 | * at least one idle worker or that someone else has already |
2266 | * assumed the manager role. |
2267 | */ |
2268 | worker_clr_flags(worker, WORKER_PREP); |
2269 | |
2270 | do { |
2271 | struct work_struct *work = |
2272 | list_first_entry(&pool->worklist, |
2273 | struct work_struct, entry); |
2274 | |
2275 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
2276 | /* optimization path, not strictly necessary */ |
2277 | process_one_work(worker, work); |
2278 | if (unlikely(!list_empty(&worker->scheduled))) |
2279 | process_scheduled_works(worker); |
2280 | } else { |
2281 | move_linked_works(work, &worker->scheduled, NULL); |
2282 | process_scheduled_works(worker); |
2283 | } |
2284 | } while (keep_working(pool)); |
2285 | |
2286 | worker_set_flags(worker, WORKER_PREP, false); |
2287 | sleep: |
2288 | if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) |
2289 | goto recheck; |
2290 | |
2291 | /* |
2292 | * pool->lock is held and there's no work to process and no need to |
2293 | * manage, sleep. Workers are woken up only while holding |
2294 | * pool->lock or from local cpu, so setting the current state |
2295 | * before releasing pool->lock is enough to prevent losing any |
2296 | * event. |
2297 | */ |
2298 | worker_enter_idle(worker); |
2299 | __set_current_state(TASK_INTERRUPTIBLE); |
2300 | spin_unlock_irq(&pool->lock); |
2301 | schedule(); |
2302 | goto woke_up; |
2303 | } |
2304 | |
2305 | /** |
2306 | * rescuer_thread - the rescuer thread function |
2307 | * @__rescuer: self |
2308 | * |
2309 | * Workqueue rescuer thread function. There's one rescuer for each |
2310 | * workqueue which has WQ_RESCUER set. |
2311 | * |
2312 | * Regular work processing on a pool may block trying to create a new |
2313 | * worker which uses GFP_KERNEL allocation which has slight chance of |
2314 | * developing into deadlock if some works currently on the same queue |
2315 | * need to be processed to satisfy the GFP_KERNEL allocation. This is |
2316 | * the problem rescuer solves. |
2317 | * |
2318 | * When such condition is possible, the pool summons rescuers of all |
2319 | * workqueues which have works queued on the pool and let them process |
2320 | * those works so that forward progress can be guaranteed. |
2321 | * |
2322 | * This should happen rarely. |
2323 | */ |
2324 | static int rescuer_thread(void *__rescuer) |
2325 | { |
2326 | struct worker *rescuer = __rescuer; |
2327 | struct workqueue_struct *wq = rescuer->rescue_wq; |
2328 | struct list_head *scheduled = &rescuer->scheduled; |
2329 | bool is_unbound = wq->flags & WQ_UNBOUND; |
2330 | unsigned int cpu; |
2331 | |
2332 | set_user_nice(current, RESCUER_NICE_LEVEL); |
2333 | |
2334 | /* |
2335 | * Mark rescuer as worker too. As WORKER_PREP is never cleared, it |
2336 | * doesn't participate in concurrency management. |
2337 | */ |
2338 | rescuer->task->flags |= PF_WQ_WORKER; |
2339 | repeat: |
2340 | set_current_state(TASK_INTERRUPTIBLE); |
2341 | |
2342 | if (kthread_should_stop()) { |
2343 | __set_current_state(TASK_RUNNING); |
2344 | rescuer->task->flags &= ~PF_WQ_WORKER; |
2345 | return 0; |
2346 | } |
2347 | |
2348 | /* |
2349 | * See whether any cpu is asking for help. Unbounded |
2350 | * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. |
2351 | */ |
2352 | for_each_mayday_cpu(cpu, wq->mayday_mask) { |
2353 | unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; |
2354 | struct pool_workqueue *pwq = get_pwq(tcpu, wq); |
2355 | struct worker_pool *pool = pwq->pool; |
2356 | struct work_struct *work, *n; |
2357 | |
2358 | __set_current_state(TASK_RUNNING); |
2359 | mayday_clear_cpu(cpu, wq->mayday_mask); |
2360 | |
2361 | /* migrate to the target cpu if possible */ |
2362 | rescuer->pool = pool; |
2363 | worker_maybe_bind_and_lock(rescuer); |
2364 | |
2365 | /* |
2366 | * Slurp in all works issued via this workqueue and |
2367 | * process'em. |
2368 | */ |
2369 | BUG_ON(!list_empty(&rescuer->scheduled)); |
2370 | list_for_each_entry_safe(work, n, &pool->worklist, entry) |
2371 | if (get_work_pwq(work) == pwq) |
2372 | move_linked_works(work, scheduled, &n); |
2373 | |
2374 | process_scheduled_works(rescuer); |
2375 | |
2376 | /* |
2377 | * Leave this pool. If keep_working() is %true, notify a |
2378 | * regular worker; otherwise, we end up with 0 concurrency |
2379 | * and stalling the execution. |
2380 | */ |
2381 | if (keep_working(pool)) |
2382 | wake_up_worker(pool); |
2383 | |
2384 | spin_unlock_irq(&pool->lock); |
2385 | } |
2386 | |
2387 | /* rescuers should never participate in concurrency management */ |
2388 | WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); |
2389 | schedule(); |
2390 | goto repeat; |
2391 | } |
2392 | |
2393 | struct wq_barrier { |
2394 | struct work_struct work; |
2395 | struct completion done; |
2396 | }; |
2397 | |
2398 | static void wq_barrier_func(struct work_struct *work) |
2399 | { |
2400 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
2401 | complete(&barr->done); |
2402 | } |
2403 | |
2404 | /** |
2405 | * insert_wq_barrier - insert a barrier work |
2406 | * @pwq: pwq to insert barrier into |
2407 | * @barr: wq_barrier to insert |
2408 | * @target: target work to attach @barr to |
2409 | * @worker: worker currently executing @target, NULL if @target is not executing |
2410 | * |
2411 | * @barr is linked to @target such that @barr is completed only after |
2412 | * @target finishes execution. Please note that the ordering |
2413 | * guarantee is observed only with respect to @target and on the local |
2414 | * cpu. |
2415 | * |
2416 | * Currently, a queued barrier can't be canceled. This is because |
2417 | * try_to_grab_pending() can't determine whether the work to be |
2418 | * grabbed is at the head of the queue and thus can't clear LINKED |
2419 | * flag of the previous work while there must be a valid next work |
2420 | * after a work with LINKED flag set. |
2421 | * |
2422 | * Note that when @worker is non-NULL, @target may be modified |
2423 | * underneath us, so we can't reliably determine pwq from @target. |
2424 | * |
2425 | * CONTEXT: |
2426 | * spin_lock_irq(pool->lock). |
2427 | */ |
2428 | static void insert_wq_barrier(struct pool_workqueue *pwq, |
2429 | struct wq_barrier *barr, |
2430 | struct work_struct *target, struct worker *worker) |
2431 | { |
2432 | struct list_head *head; |
2433 | unsigned int linked = 0; |
2434 | |
2435 | /* |
2436 | * debugobject calls are safe here even with pool->lock locked |
2437 | * as we know for sure that this will not trigger any of the |
2438 | * checks and call back into the fixup functions where we |
2439 | * might deadlock. |
2440 | */ |
2441 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
2442 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
2443 | init_completion(&barr->done); |
2444 | |
2445 | /* |
2446 | * If @target is currently being executed, schedule the |
2447 | * barrier to the worker; otherwise, put it after @target. |
2448 | */ |
2449 | if (worker) |
2450 | head = worker->scheduled.next; |
2451 | else { |
2452 | unsigned long *bits = work_data_bits(target); |
2453 | |
2454 | head = target->entry.next; |
2455 | /* there can already be other linked works, inherit and set */ |
2456 | linked = *bits & WORK_STRUCT_LINKED; |
2457 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
2458 | } |
2459 | |
2460 | debug_work_activate(&barr->work); |
2461 | insert_work(pwq, &barr->work, head, |
2462 | work_color_to_flags(WORK_NO_COLOR) | linked); |
2463 | } |
2464 | |
2465 | /** |
2466 | * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing |
2467 | * @wq: workqueue being flushed |
2468 | * @flush_color: new flush color, < 0 for no-op |
2469 | * @work_color: new work color, < 0 for no-op |
2470 | * |
2471 | * Prepare pwqs for workqueue flushing. |
2472 | * |
2473 | * If @flush_color is non-negative, flush_color on all pwqs should be |
2474 | * -1. If no pwq has in-flight commands at the specified color, all |
2475 | * pwq->flush_color's stay at -1 and %false is returned. If any pwq |
2476 | * has in flight commands, its pwq->flush_color is set to |
2477 | * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq |
2478 | * wakeup logic is armed and %true is returned. |
2479 | * |
2480 | * The caller should have initialized @wq->first_flusher prior to |
2481 | * calling this function with non-negative @flush_color. If |
2482 | * @flush_color is negative, no flush color update is done and %false |
2483 | * is returned. |
2484 | * |
2485 | * If @work_color is non-negative, all pwqs should have the same |
2486 | * work_color which is previous to @work_color and all will be |
2487 | * advanced to @work_color. |
2488 | * |
2489 | * CONTEXT: |
2490 | * mutex_lock(wq->flush_mutex). |
2491 | * |
2492 | * RETURNS: |
2493 | * %true if @flush_color >= 0 and there's something to flush. %false |
2494 | * otherwise. |
2495 | */ |
2496 | static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, |
2497 | int flush_color, int work_color) |
2498 | { |
2499 | bool wait = false; |
2500 | unsigned int cpu; |
2501 | |
2502 | if (flush_color >= 0) { |
2503 | BUG_ON(atomic_read(&wq->nr_pwqs_to_flush)); |
2504 | atomic_set(&wq->nr_pwqs_to_flush, 1); |
2505 | } |
2506 | |
2507 | for_each_pwq_cpu(cpu, wq) { |
2508 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
2509 | struct worker_pool *pool = pwq->pool; |
2510 | |
2511 | spin_lock_irq(&pool->lock); |
2512 | |
2513 | if (flush_color >= 0) { |
2514 | BUG_ON(pwq->flush_color != -1); |
2515 | |
2516 | if (pwq->nr_in_flight[flush_color]) { |
2517 | pwq->flush_color = flush_color; |
2518 | atomic_inc(&wq->nr_pwqs_to_flush); |
2519 | wait = true; |
2520 | } |
2521 | } |
2522 | |
2523 | if (work_color >= 0) { |
2524 | BUG_ON(work_color != work_next_color(pwq->work_color)); |
2525 | pwq->work_color = work_color; |
2526 | } |
2527 | |
2528 | spin_unlock_irq(&pool->lock); |
2529 | } |
2530 | |
2531 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) |
2532 | complete(&wq->first_flusher->done); |
2533 | |
2534 | return wait; |
2535 | } |
2536 | |
2537 | /** |
2538 | * flush_workqueue - ensure that any scheduled work has run to completion. |
2539 | * @wq: workqueue to flush |
2540 | * |
2541 | * Forces execution of the workqueue and blocks until its completion. |
2542 | * This is typically used in driver shutdown handlers. |
2543 | * |
2544 | * We sleep until all works which were queued on entry have been handled, |
2545 | * but we are not livelocked by new incoming ones. |
2546 | */ |
2547 | void flush_workqueue(struct workqueue_struct *wq) |
2548 | { |
2549 | struct wq_flusher this_flusher = { |
2550 | .list = LIST_HEAD_INIT(this_flusher.list), |
2551 | .flush_color = -1, |
2552 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), |
2553 | }; |
2554 | int next_color; |
2555 | |
2556 | lock_map_acquire(&wq->lockdep_map); |
2557 | lock_map_release(&wq->lockdep_map); |
2558 | |
2559 | mutex_lock(&wq->flush_mutex); |
2560 | |
2561 | /* |
2562 | * Start-to-wait phase |
2563 | */ |
2564 | next_color = work_next_color(wq->work_color); |
2565 | |
2566 | if (next_color != wq->flush_color) { |
2567 | /* |
2568 | * Color space is not full. The current work_color |
2569 | * becomes our flush_color and work_color is advanced |
2570 | * by one. |
2571 | */ |
2572 | BUG_ON(!list_empty(&wq->flusher_overflow)); |
2573 | this_flusher.flush_color = wq->work_color; |
2574 | wq->work_color = next_color; |
2575 | |
2576 | if (!wq->first_flusher) { |
2577 | /* no flush in progress, become the first flusher */ |
2578 | BUG_ON(wq->flush_color != this_flusher.flush_color); |
2579 | |
2580 | wq->first_flusher = &this_flusher; |
2581 | |
2582 | if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, |
2583 | wq->work_color)) { |
2584 | /* nothing to flush, done */ |
2585 | wq->flush_color = next_color; |
2586 | wq->first_flusher = NULL; |
2587 | goto out_unlock; |
2588 | } |
2589 | } else { |
2590 | /* wait in queue */ |
2591 | BUG_ON(wq->flush_color == this_flusher.flush_color); |
2592 | list_add_tail(&this_flusher.list, &wq->flusher_queue); |
2593 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
2594 | } |
2595 | } else { |
2596 | /* |
2597 | * Oops, color space is full, wait on overflow queue. |
2598 | * The next flush completion will assign us |
2599 | * flush_color and transfer to flusher_queue. |
2600 | */ |
2601 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
2602 | } |
2603 | |
2604 | mutex_unlock(&wq->flush_mutex); |
2605 | |
2606 | wait_for_completion(&this_flusher.done); |
2607 | |
2608 | /* |
2609 | * Wake-up-and-cascade phase |
2610 | * |
2611 | * First flushers are responsible for cascading flushes and |
2612 | * handling overflow. Non-first flushers can simply return. |
2613 | */ |
2614 | if (wq->first_flusher != &this_flusher) |
2615 | return; |
2616 | |
2617 | mutex_lock(&wq->flush_mutex); |
2618 | |
2619 | /* we might have raced, check again with mutex held */ |
2620 | if (wq->first_flusher != &this_flusher) |
2621 | goto out_unlock; |
2622 | |
2623 | wq->first_flusher = NULL; |
2624 | |
2625 | BUG_ON(!list_empty(&this_flusher.list)); |
2626 | BUG_ON(wq->flush_color != this_flusher.flush_color); |
2627 | |
2628 | while (true) { |
2629 | struct wq_flusher *next, *tmp; |
2630 | |
2631 | /* complete all the flushers sharing the current flush color */ |
2632 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
2633 | if (next->flush_color != wq->flush_color) |
2634 | break; |
2635 | list_del_init(&next->list); |
2636 | complete(&next->done); |
2637 | } |
2638 | |
2639 | BUG_ON(!list_empty(&wq->flusher_overflow) && |
2640 | wq->flush_color != work_next_color(wq->work_color)); |
2641 | |
2642 | /* this flush_color is finished, advance by one */ |
2643 | wq->flush_color = work_next_color(wq->flush_color); |
2644 | |
2645 | /* one color has been freed, handle overflow queue */ |
2646 | if (!list_empty(&wq->flusher_overflow)) { |
2647 | /* |
2648 | * Assign the same color to all overflowed |
2649 | * flushers, advance work_color and append to |
2650 | * flusher_queue. This is the start-to-wait |
2651 | * phase for these overflowed flushers. |
2652 | */ |
2653 | list_for_each_entry(tmp, &wq->flusher_overflow, list) |
2654 | tmp->flush_color = wq->work_color; |
2655 | |
2656 | wq->work_color = work_next_color(wq->work_color); |
2657 | |
2658 | list_splice_tail_init(&wq->flusher_overflow, |
2659 | &wq->flusher_queue); |
2660 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
2661 | } |
2662 | |
2663 | if (list_empty(&wq->flusher_queue)) { |
2664 | BUG_ON(wq->flush_color != wq->work_color); |
2665 | break; |
2666 | } |
2667 | |
2668 | /* |
2669 | * Need to flush more colors. Make the next flusher |
2670 | * the new first flusher and arm pwqs. |
2671 | */ |
2672 | BUG_ON(wq->flush_color == wq->work_color); |
2673 | BUG_ON(wq->flush_color != next->flush_color); |
2674 | |
2675 | list_del_init(&next->list); |
2676 | wq->first_flusher = next; |
2677 | |
2678 | if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) |
2679 | break; |
2680 | |
2681 | /* |
2682 | * Meh... this color is already done, clear first |
2683 | * flusher and repeat cascading. |
2684 | */ |
2685 | wq->first_flusher = NULL; |
2686 | } |
2687 | |
2688 | out_unlock: |
2689 | mutex_unlock(&wq->flush_mutex); |
2690 | } |
2691 | EXPORT_SYMBOL_GPL(flush_workqueue); |
2692 | |
2693 | /** |
2694 | * drain_workqueue - drain a workqueue |
2695 | * @wq: workqueue to drain |
2696 | * |
2697 | * Wait until the workqueue becomes empty. While draining is in progress, |
2698 | * only chain queueing is allowed. IOW, only currently pending or running |
2699 | * work items on @wq can queue further work items on it. @wq is flushed |
2700 | * repeatedly until it becomes empty. The number of flushing is detemined |
2701 | * by the depth of chaining and should be relatively short. Whine if it |
2702 | * takes too long. |
2703 | */ |
2704 | void drain_workqueue(struct workqueue_struct *wq) |
2705 | { |
2706 | unsigned int flush_cnt = 0; |
2707 | unsigned int cpu; |
2708 | |
2709 | /* |
2710 | * __queue_work() needs to test whether there are drainers, is much |
2711 | * hotter than drain_workqueue() and already looks at @wq->flags. |
2712 | * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. |
2713 | */ |
2714 | spin_lock(&workqueue_lock); |
2715 | if (!wq->nr_drainers++) |
2716 | wq->flags |= WQ_DRAINING; |
2717 | spin_unlock(&workqueue_lock); |
2718 | reflush: |
2719 | flush_workqueue(wq); |
2720 | |
2721 | for_each_pwq_cpu(cpu, wq) { |
2722 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
2723 | bool drained; |
2724 | |
2725 | spin_lock_irq(&pwq->pool->lock); |
2726 | drained = !pwq->nr_active && list_empty(&pwq->delayed_works); |
2727 | spin_unlock_irq(&pwq->pool->lock); |
2728 | |
2729 | if (drained) |
2730 | continue; |
2731 | |
2732 | if (++flush_cnt == 10 || |
2733 | (flush_cnt % 100 == 0 && flush_cnt <= 1000)) |
2734 | pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n", |
2735 | wq->name, flush_cnt); |
2736 | goto reflush; |
2737 | } |
2738 | |
2739 | spin_lock(&workqueue_lock); |
2740 | if (!--wq->nr_drainers) |
2741 | wq->flags &= ~WQ_DRAINING; |
2742 | spin_unlock(&workqueue_lock); |
2743 | } |
2744 | EXPORT_SYMBOL_GPL(drain_workqueue); |
2745 | |
2746 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) |
2747 | { |
2748 | struct worker *worker = NULL; |
2749 | struct worker_pool *pool; |
2750 | struct pool_workqueue *pwq; |
2751 | |
2752 | might_sleep(); |
2753 | pool = get_work_pool(work); |
2754 | if (!pool) |
2755 | return false; |
2756 | |
2757 | spin_lock_irq(&pool->lock); |
2758 | /* see the comment in try_to_grab_pending() with the same code */ |
2759 | pwq = get_work_pwq(work); |
2760 | if (pwq) { |
2761 | if (unlikely(pwq->pool != pool)) |
2762 | goto already_gone; |
2763 | } else { |
2764 | worker = find_worker_executing_work(pool, work); |
2765 | if (!worker) |
2766 | goto already_gone; |
2767 | pwq = worker->current_pwq; |
2768 | } |
2769 | |
2770 | insert_wq_barrier(pwq, barr, work, worker); |
2771 | spin_unlock_irq(&pool->lock); |
2772 | |
2773 | /* |
2774 | * If @max_active is 1 or rescuer is in use, flushing another work |
2775 | * item on the same workqueue may lead to deadlock. Make sure the |
2776 | * flusher is not running on the same workqueue by verifying write |
2777 | * access. |
2778 | */ |
2779 | if (pwq->wq->saved_max_active == 1 || pwq->wq->flags & WQ_RESCUER) |
2780 | lock_map_acquire(&pwq->wq->lockdep_map); |
2781 | else |
2782 | lock_map_acquire_read(&pwq->wq->lockdep_map); |
2783 | lock_map_release(&pwq->wq->lockdep_map); |
2784 | |
2785 | return true; |
2786 | already_gone: |
2787 | spin_unlock_irq(&pool->lock); |
2788 | return false; |
2789 | } |
2790 | |
2791 | /** |
2792 | * flush_work - wait for a work to finish executing the last queueing instance |
2793 | * @work: the work to flush |
2794 | * |
2795 | * Wait until @work has finished execution. @work is guaranteed to be idle |
2796 | * on return if it hasn't been requeued since flush started. |
2797 | * |
2798 | * RETURNS: |
2799 | * %true if flush_work() waited for the work to finish execution, |
2800 | * %false if it was already idle. |
2801 | */ |
2802 | bool flush_work(struct work_struct *work) |
2803 | { |
2804 | struct wq_barrier barr; |
2805 | |
2806 | lock_map_acquire(&work->lockdep_map); |
2807 | lock_map_release(&work->lockdep_map); |
2808 | |
2809 | if (start_flush_work(work, &barr)) { |
2810 | wait_for_completion(&barr.done); |
2811 | destroy_work_on_stack(&barr.work); |
2812 | return true; |
2813 | } else { |
2814 | return false; |
2815 | } |
2816 | } |
2817 | EXPORT_SYMBOL_GPL(flush_work); |
2818 | |
2819 | static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) |
2820 | { |
2821 | unsigned long flags; |
2822 | int ret; |
2823 | |
2824 | do { |
2825 | ret = try_to_grab_pending(work, is_dwork, &flags); |
2826 | /* |
2827 | * If someone else is canceling, wait for the same event it |
2828 | * would be waiting for before retrying. |
2829 | */ |
2830 | if (unlikely(ret == -ENOENT)) |
2831 | flush_work(work); |
2832 | } while (unlikely(ret < 0)); |
2833 | |
2834 | /* tell other tasks trying to grab @work to back off */ |
2835 | mark_work_canceling(work); |
2836 | local_irq_restore(flags); |
2837 | |
2838 | flush_work(work); |
2839 | clear_work_data(work); |
2840 | return ret; |
2841 | } |
2842 | |
2843 | /** |
2844 | * cancel_work_sync - cancel a work and wait for it to finish |
2845 | * @work: the work to cancel |
2846 | * |
2847 | * Cancel @work and wait for its execution to finish. This function |
2848 | * can be used even if the work re-queues itself or migrates to |
2849 | * another workqueue. On return from this function, @work is |
2850 | * guaranteed to be not pending or executing on any CPU. |
2851 | * |
2852 | * cancel_work_sync(&delayed_work->work) must not be used for |
2853 | * delayed_work's. Use cancel_delayed_work_sync() instead. |
2854 | * |
2855 | * The caller must ensure that the workqueue on which @work was last |
2856 | * queued can't be destroyed before this function returns. |
2857 | * |
2858 | * RETURNS: |
2859 | * %true if @work was pending, %false otherwise. |
2860 | */ |
2861 | bool cancel_work_sync(struct work_struct *work) |
2862 | { |
2863 | return __cancel_work_timer(work, false); |
2864 | } |
2865 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
2866 | |
2867 | /** |
2868 | * flush_delayed_work - wait for a dwork to finish executing the last queueing |
2869 | * @dwork: the delayed work to flush |
2870 | * |
2871 | * Delayed timer is cancelled and the pending work is queued for |
2872 | * immediate execution. Like flush_work(), this function only |
2873 | * considers the last queueing instance of @dwork. |
2874 | * |
2875 | * RETURNS: |
2876 | * %true if flush_work() waited for the work to finish execution, |
2877 | * %false if it was already idle. |
2878 | */ |
2879 | bool flush_delayed_work(struct delayed_work *dwork) |
2880 | { |
2881 | local_irq_disable(); |
2882 | if (del_timer_sync(&dwork->timer)) |
2883 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); |
2884 | local_irq_enable(); |
2885 | return flush_work(&dwork->work); |
2886 | } |
2887 | EXPORT_SYMBOL(flush_delayed_work); |
2888 | |
2889 | /** |
2890 | * cancel_delayed_work - cancel a delayed work |
2891 | * @dwork: delayed_work to cancel |
2892 | * |
2893 | * Kill off a pending delayed_work. Returns %true if @dwork was pending |
2894 | * and canceled; %false if wasn't pending. Note that the work callback |
2895 | * function may still be running on return, unless it returns %true and the |
2896 | * work doesn't re-arm itself. Explicitly flush or use |
2897 | * cancel_delayed_work_sync() to wait on it. |
2898 | * |
2899 | * This function is safe to call from any context including IRQ handler. |
2900 | */ |
2901 | bool cancel_delayed_work(struct delayed_work *dwork) |
2902 | { |
2903 | unsigned long flags; |
2904 | int ret; |
2905 | |
2906 | do { |
2907 | ret = try_to_grab_pending(&dwork->work, true, &flags); |
2908 | } while (unlikely(ret == -EAGAIN)); |
2909 | |
2910 | if (unlikely(ret < 0)) |
2911 | return false; |
2912 | |
2913 | set_work_pool_and_clear_pending(&dwork->work, |
2914 | get_work_pool_id(&dwork->work)); |
2915 | local_irq_restore(flags); |
2916 | return ret; |
2917 | } |
2918 | EXPORT_SYMBOL(cancel_delayed_work); |
2919 | |
2920 | /** |
2921 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish |
2922 | * @dwork: the delayed work cancel |
2923 | * |
2924 | * This is cancel_work_sync() for delayed works. |
2925 | * |
2926 | * RETURNS: |
2927 | * %true if @dwork was pending, %false otherwise. |
2928 | */ |
2929 | bool cancel_delayed_work_sync(struct delayed_work *dwork) |
2930 | { |
2931 | return __cancel_work_timer(&dwork->work, true); |
2932 | } |
2933 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
2934 | |
2935 | /** |
2936 | * schedule_work_on - put work task on a specific cpu |
2937 | * @cpu: cpu to put the work task on |
2938 | * @work: job to be done |
2939 | * |
2940 | * This puts a job on a specific cpu |
2941 | */ |
2942 | bool schedule_work_on(int cpu, struct work_struct *work) |
2943 | { |
2944 | return queue_work_on(cpu, system_wq, work); |
2945 | } |
2946 | EXPORT_SYMBOL(schedule_work_on); |
2947 | |
2948 | /** |
2949 | * schedule_work - put work task in global workqueue |
2950 | * @work: job to be done |
2951 | * |
2952 | * Returns %false if @work was already on the kernel-global workqueue and |
2953 | * %true otherwise. |
2954 | * |
2955 | * This puts a job in the kernel-global workqueue if it was not already |
2956 | * queued and leaves it in the same position on the kernel-global |
2957 | * workqueue otherwise. |
2958 | */ |
2959 | bool schedule_work(struct work_struct *work) |
2960 | { |
2961 | return queue_work(system_wq, work); |
2962 | } |
2963 | EXPORT_SYMBOL(schedule_work); |
2964 | |
2965 | /** |
2966 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay |
2967 | * @cpu: cpu to use |
2968 | * @dwork: job to be done |
2969 | * @delay: number of jiffies to wait |
2970 | * |
2971 | * After waiting for a given time this puts a job in the kernel-global |
2972 | * workqueue on the specified CPU. |
2973 | */ |
2974 | bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork, |
2975 | unsigned long delay) |
2976 | { |
2977 | return queue_delayed_work_on(cpu, system_wq, dwork, delay); |
2978 | } |
2979 | EXPORT_SYMBOL(schedule_delayed_work_on); |
2980 | |
2981 | /** |
2982 | * schedule_delayed_work - put work task in global workqueue after delay |
2983 | * @dwork: job to be done |
2984 | * @delay: number of jiffies to wait or 0 for immediate execution |
2985 | * |
2986 | * After waiting for a given time this puts a job in the kernel-global |
2987 | * workqueue. |
2988 | */ |
2989 | bool schedule_delayed_work(struct delayed_work *dwork, unsigned long delay) |
2990 | { |
2991 | return queue_delayed_work(system_wq, dwork, delay); |
2992 | } |
2993 | EXPORT_SYMBOL(schedule_delayed_work); |
2994 | |
2995 | /** |
2996 | * schedule_on_each_cpu - execute a function synchronously on each online CPU |
2997 | * @func: the function to call |
2998 | * |
2999 | * schedule_on_each_cpu() executes @func on each online CPU using the |
3000 | * system workqueue and blocks until all CPUs have completed. |
3001 | * schedule_on_each_cpu() is very slow. |
3002 | * |
3003 | * RETURNS: |
3004 | * 0 on success, -errno on failure. |
3005 | */ |
3006 | int schedule_on_each_cpu(work_func_t func) |
3007 | { |
3008 | int cpu; |
3009 | struct work_struct __percpu *works; |
3010 | |
3011 | works = alloc_percpu(struct work_struct); |
3012 | if (!works) |
3013 | return -ENOMEM; |
3014 | |
3015 | get_online_cpus(); |
3016 | |
3017 | for_each_online_cpu(cpu) { |
3018 | struct work_struct *work = per_cpu_ptr(works, cpu); |
3019 | |
3020 | INIT_WORK(work, func); |
3021 | schedule_work_on(cpu, work); |
3022 | } |
3023 | |
3024 | for_each_online_cpu(cpu) |
3025 | flush_work(per_cpu_ptr(works, cpu)); |
3026 | |
3027 | put_online_cpus(); |
3028 | free_percpu(works); |
3029 | return 0; |
3030 | } |
3031 | |
3032 | /** |
3033 | * flush_scheduled_work - ensure that any scheduled work has run to completion. |
3034 | * |
3035 | * Forces execution of the kernel-global workqueue and blocks until its |
3036 | * completion. |
3037 | * |
3038 | * Think twice before calling this function! It's very easy to get into |
3039 | * trouble if you don't take great care. Either of the following situations |
3040 | * will lead to deadlock: |
3041 | * |
3042 | * One of the work items currently on the workqueue needs to acquire |
3043 | * a lock held by your code or its caller. |
3044 | * |
3045 | * Your code is running in the context of a work routine. |
3046 | * |
3047 | * They will be detected by lockdep when they occur, but the first might not |
3048 | * occur very often. It depends on what work items are on the workqueue and |
3049 | * what locks they need, which you have no control over. |
3050 | * |
3051 | * In most situations flushing the entire workqueue is overkill; you merely |
3052 | * need to know that a particular work item isn't queued and isn't running. |
3053 | * In such cases you should use cancel_delayed_work_sync() or |
3054 | * cancel_work_sync() instead. |
3055 | */ |
3056 | void flush_scheduled_work(void) |
3057 | { |
3058 | flush_workqueue(system_wq); |
3059 | } |
3060 | EXPORT_SYMBOL(flush_scheduled_work); |
3061 | |
3062 | /** |
3063 | * execute_in_process_context - reliably execute the routine with user context |
3064 | * @fn: the function to execute |
3065 | * @ew: guaranteed storage for the execute work structure (must |
3066 | * be available when the work executes) |
3067 | * |
3068 | * Executes the function immediately if process context is available, |
3069 | * otherwise schedules the function for delayed execution. |
3070 | * |
3071 | * Returns: 0 - function was executed |
3072 | * 1 - function was scheduled for execution |
3073 | */ |
3074 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
3075 | { |
3076 | if (!in_interrupt()) { |
3077 | fn(&ew->work); |
3078 | return 0; |
3079 | } |
3080 | |
3081 | INIT_WORK(&ew->work, fn); |
3082 | schedule_work(&ew->work); |
3083 | |
3084 | return 1; |
3085 | } |
3086 | EXPORT_SYMBOL_GPL(execute_in_process_context); |
3087 | |
3088 | int keventd_up(void) |
3089 | { |
3090 | return system_wq != NULL; |
3091 | } |
3092 | |
3093 | static int alloc_pwqs(struct workqueue_struct *wq) |
3094 | { |
3095 | /* |
3096 | * pwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. |
3097 | * Make sure that the alignment isn't lower than that of |
3098 | * unsigned long long. |
3099 | */ |
3100 | const size_t size = sizeof(struct pool_workqueue); |
3101 | const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, |
3102 | __alignof__(unsigned long long)); |
3103 | |
3104 | if (!(wq->flags & WQ_UNBOUND)) |
3105 | wq->pool_wq.pcpu = __alloc_percpu(size, align); |
3106 | else { |
3107 | void *ptr; |
3108 | |
3109 | /* |
3110 | * Allocate enough room to align pwq and put an extra |
3111 | * pointer at the end pointing back to the originally |
3112 | * allocated pointer which will be used for free. |
3113 | */ |
3114 | ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); |
3115 | if (ptr) { |
3116 | wq->pool_wq.single = PTR_ALIGN(ptr, align); |
3117 | *(void **)(wq->pool_wq.single + 1) = ptr; |
3118 | } |
3119 | } |
3120 | |
3121 | /* just in case, make sure it's actually aligned */ |
3122 | BUG_ON(!IS_ALIGNED(wq->pool_wq.v, align)); |
3123 | return wq->pool_wq.v ? 0 : -ENOMEM; |
3124 | } |
3125 | |
3126 | static void free_pwqs(struct workqueue_struct *wq) |
3127 | { |
3128 | if (!(wq->flags & WQ_UNBOUND)) |
3129 | free_percpu(wq->pool_wq.pcpu); |
3130 | else if (wq->pool_wq.single) { |
3131 | /* the pointer to free is stored right after the pwq */ |
3132 | kfree(*(void **)(wq->pool_wq.single + 1)); |
3133 | } |
3134 | } |
3135 | |
3136 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
3137 | const char *name) |
3138 | { |
3139 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
3140 | |
3141 | if (max_active < 1 || max_active > lim) |
3142 | pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", |
3143 | max_active, name, 1, lim); |
3144 | |
3145 | return clamp_val(max_active, 1, lim); |
3146 | } |
3147 | |
3148 | struct workqueue_struct *__alloc_workqueue_key(const char *fmt, |
3149 | unsigned int flags, |
3150 | int max_active, |
3151 | struct lock_class_key *key, |
3152 | const char *lock_name, ...) |
3153 | { |
3154 | va_list args, args1; |
3155 | struct workqueue_struct *wq; |
3156 | unsigned int cpu; |
3157 | size_t namelen; |
3158 | |
3159 | /* determine namelen, allocate wq and format name */ |
3160 | va_start(args, lock_name); |
3161 | va_copy(args1, args); |
3162 | namelen = vsnprintf(NULL, 0, fmt, args) + 1; |
3163 | |
3164 | wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL); |
3165 | if (!wq) |
3166 | goto err; |
3167 | |
3168 | vsnprintf(wq->name, namelen, fmt, args1); |
3169 | va_end(args); |
3170 | va_end(args1); |
3171 | |
3172 | /* |
3173 | * Workqueues which may be used during memory reclaim should |
3174 | * have a rescuer to guarantee forward progress. |
3175 | */ |
3176 | if (flags & WQ_MEM_RECLAIM) |
3177 | flags |= WQ_RESCUER; |
3178 | |
3179 | max_active = max_active ?: WQ_DFL_ACTIVE; |
3180 | max_active = wq_clamp_max_active(max_active, flags, wq->name); |
3181 | |
3182 | /* init wq */ |
3183 | wq->flags = flags; |
3184 | wq->saved_max_active = max_active; |
3185 | mutex_init(&wq->flush_mutex); |
3186 | atomic_set(&wq->nr_pwqs_to_flush, 0); |
3187 | INIT_LIST_HEAD(&wq->flusher_queue); |
3188 | INIT_LIST_HEAD(&wq->flusher_overflow); |
3189 | |
3190 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
3191 | INIT_LIST_HEAD(&wq->list); |
3192 | |
3193 | if (alloc_pwqs(wq) < 0) |
3194 | goto err; |
3195 | |
3196 | for_each_pwq_cpu(cpu, wq) { |
3197 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
3198 | |
3199 | BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); |
3200 | pwq->pool = get_std_worker_pool(cpu, flags & WQ_HIGHPRI); |
3201 | pwq->wq = wq; |
3202 | pwq->flush_color = -1; |
3203 | pwq->max_active = max_active; |
3204 | INIT_LIST_HEAD(&pwq->delayed_works); |
3205 | } |
3206 | |
3207 | if (flags & WQ_RESCUER) { |
3208 | struct worker *rescuer; |
3209 | |
3210 | if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) |
3211 | goto err; |
3212 | |
3213 | wq->rescuer = rescuer = alloc_worker(); |
3214 | if (!rescuer) |
3215 | goto err; |
3216 | |
3217 | rescuer->rescue_wq = wq; |
3218 | rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", |
3219 | wq->name); |
3220 | if (IS_ERR(rescuer->task)) |
3221 | goto err; |
3222 | |
3223 | rescuer->task->flags |= PF_THREAD_BOUND; |
3224 | wake_up_process(rescuer->task); |
3225 | } |
3226 | |
3227 | /* |
3228 | * workqueue_lock protects global freeze state and workqueues |
3229 | * list. Grab it, set max_active accordingly and add the new |
3230 | * workqueue to workqueues list. |
3231 | */ |
3232 | spin_lock(&workqueue_lock); |
3233 | |
3234 | if (workqueue_freezing && wq->flags & WQ_FREEZABLE) |
3235 | for_each_pwq_cpu(cpu, wq) |
3236 | get_pwq(cpu, wq)->max_active = 0; |
3237 | |
3238 | list_add(&wq->list, &workqueues); |
3239 | |
3240 | spin_unlock(&workqueue_lock); |
3241 | |
3242 | return wq; |
3243 | err: |
3244 | if (wq) { |
3245 | free_pwqs(wq); |
3246 | free_mayday_mask(wq->mayday_mask); |
3247 | kfree(wq->rescuer); |
3248 | kfree(wq); |
3249 | } |
3250 | return NULL; |
3251 | } |
3252 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
3253 | |
3254 | /** |
3255 | * destroy_workqueue - safely terminate a workqueue |
3256 | * @wq: target workqueue |
3257 | * |
3258 | * Safely destroy a workqueue. All work currently pending will be done first. |
3259 | */ |
3260 | void destroy_workqueue(struct workqueue_struct *wq) |
3261 | { |
3262 | unsigned int cpu; |
3263 | |
3264 | /* drain it before proceeding with destruction */ |
3265 | drain_workqueue(wq); |
3266 | |
3267 | /* |
3268 | * wq list is used to freeze wq, remove from list after |
3269 | * flushing is complete in case freeze races us. |
3270 | */ |
3271 | spin_lock(&workqueue_lock); |
3272 | list_del(&wq->list); |
3273 | spin_unlock(&workqueue_lock); |
3274 | |
3275 | /* sanity check */ |
3276 | for_each_pwq_cpu(cpu, wq) { |
3277 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
3278 | int i; |
3279 | |
3280 | for (i = 0; i < WORK_NR_COLORS; i++) |
3281 | BUG_ON(pwq->nr_in_flight[i]); |
3282 | BUG_ON(pwq->nr_active); |
3283 | BUG_ON(!list_empty(&pwq->delayed_works)); |
3284 | } |
3285 | |
3286 | if (wq->flags & WQ_RESCUER) { |
3287 | kthread_stop(wq->rescuer->task); |
3288 | free_mayday_mask(wq->mayday_mask); |
3289 | kfree(wq->rescuer); |
3290 | } |
3291 | |
3292 | free_pwqs(wq); |
3293 | kfree(wq); |
3294 | } |
3295 | EXPORT_SYMBOL_GPL(destroy_workqueue); |
3296 | |
3297 | /** |
3298 | * pwq_set_max_active - adjust max_active of a pwq |
3299 | * @pwq: target pool_workqueue |
3300 | * @max_active: new max_active value. |
3301 | * |
3302 | * Set @pwq->max_active to @max_active and activate delayed works if |
3303 | * increased. |
3304 | * |
3305 | * CONTEXT: |
3306 | * spin_lock_irq(pool->lock). |
3307 | */ |
3308 | static void pwq_set_max_active(struct pool_workqueue *pwq, int max_active) |
3309 | { |
3310 | pwq->max_active = max_active; |
3311 | |
3312 | while (!list_empty(&pwq->delayed_works) && |
3313 | pwq->nr_active < pwq->max_active) |
3314 | pwq_activate_first_delayed(pwq); |
3315 | } |
3316 | |
3317 | /** |
3318 | * workqueue_set_max_active - adjust max_active of a workqueue |
3319 | * @wq: target workqueue |
3320 | * @max_active: new max_active value. |
3321 | * |
3322 | * Set max_active of @wq to @max_active. |
3323 | * |
3324 | * CONTEXT: |
3325 | * Don't call from IRQ context. |
3326 | */ |
3327 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
3328 | { |
3329 | unsigned int cpu; |
3330 | |
3331 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
3332 | |
3333 | spin_lock(&workqueue_lock); |
3334 | |
3335 | wq->saved_max_active = max_active; |
3336 | |
3337 | for_each_pwq_cpu(cpu, wq) { |
3338 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
3339 | struct worker_pool *pool = pwq->pool; |
3340 | |
3341 | spin_lock_irq(&pool->lock); |
3342 | |
3343 | if (!(wq->flags & WQ_FREEZABLE) || |
3344 | !(pool->flags & POOL_FREEZING)) |
3345 | pwq_set_max_active(pwq, max_active); |
3346 | |
3347 | spin_unlock_irq(&pool->lock); |
3348 | } |
3349 | |
3350 | spin_unlock(&workqueue_lock); |
3351 | } |
3352 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
3353 | |
3354 | /** |
3355 | * workqueue_congested - test whether a workqueue is congested |
3356 | * @cpu: CPU in question |
3357 | * @wq: target workqueue |
3358 | * |
3359 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
3360 | * no synchronization around this function and the test result is |
3361 | * unreliable and only useful as advisory hints or for debugging. |
3362 | * |
3363 | * RETURNS: |
3364 | * %true if congested, %false otherwise. |
3365 | */ |
3366 | bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) |
3367 | { |
3368 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
3369 | |
3370 | return !list_empty(&pwq->delayed_works); |
3371 | } |
3372 | EXPORT_SYMBOL_GPL(workqueue_congested); |
3373 | |
3374 | /** |
3375 | * work_busy - test whether a work is currently pending or running |
3376 | * @work: the work to be tested |
3377 | * |
3378 | * Test whether @work is currently pending or running. There is no |
3379 | * synchronization around this function and the test result is |
3380 | * unreliable and only useful as advisory hints or for debugging. |
3381 | * |
3382 | * RETURNS: |
3383 | * OR'd bitmask of WORK_BUSY_* bits. |
3384 | */ |
3385 | unsigned int work_busy(struct work_struct *work) |
3386 | { |
3387 | struct worker_pool *pool = get_work_pool(work); |
3388 | unsigned long flags; |
3389 | unsigned int ret = 0; |
3390 | |
3391 | if (work_pending(work)) |
3392 | ret |= WORK_BUSY_PENDING; |
3393 | |
3394 | if (pool) { |
3395 | spin_lock_irqsave(&pool->lock, flags); |
3396 | if (find_worker_executing_work(pool, work)) |
3397 | ret |= WORK_BUSY_RUNNING; |
3398 | spin_unlock_irqrestore(&pool->lock, flags); |
3399 | } |
3400 | |
3401 | return ret; |
3402 | } |
3403 | EXPORT_SYMBOL_GPL(work_busy); |
3404 | |
3405 | /* |
3406 | * CPU hotplug. |
3407 | * |
3408 | * There are two challenges in supporting CPU hotplug. Firstly, there |
3409 | * are a lot of assumptions on strong associations among work, pwq and |
3410 | * pool which make migrating pending and scheduled works very |
3411 | * difficult to implement without impacting hot paths. Secondly, |
3412 | * worker pools serve mix of short, long and very long running works making |
3413 | * blocked draining impractical. |
3414 | * |
3415 | * This is solved by allowing the pools to be disassociated from the CPU |
3416 | * running as an unbound one and allowing it to be reattached later if the |
3417 | * cpu comes back online. |
3418 | */ |
3419 | |
3420 | static void wq_unbind_fn(struct work_struct *work) |
3421 | { |
3422 | int cpu = smp_processor_id(); |
3423 | struct worker_pool *pool; |
3424 | struct worker *worker; |
3425 | int i; |
3426 | |
3427 | for_each_std_worker_pool(pool, cpu) { |
3428 | BUG_ON(cpu != smp_processor_id()); |
3429 | |
3430 | mutex_lock(&pool->assoc_mutex); |
3431 | spin_lock_irq(&pool->lock); |
3432 | |
3433 | /* |
3434 | * We've claimed all manager positions. Make all workers |
3435 | * unbound and set DISASSOCIATED. Before this, all workers |
3436 | * except for the ones which are still executing works from |
3437 | * before the last CPU down must be on the cpu. After |
3438 | * this, they may become diasporas. |
3439 | */ |
3440 | list_for_each_entry(worker, &pool->idle_list, entry) |
3441 | worker->flags |= WORKER_UNBOUND; |
3442 | |
3443 | for_each_busy_worker(worker, i, pool) |
3444 | worker->flags |= WORKER_UNBOUND; |
3445 | |
3446 | pool->flags |= POOL_DISASSOCIATED; |
3447 | |
3448 | spin_unlock_irq(&pool->lock); |
3449 | mutex_unlock(&pool->assoc_mutex); |
3450 | |
3451 | /* |
3452 | * Call schedule() so that we cross rq->lock and thus can |
3453 | * guarantee sched callbacks see the %WORKER_UNBOUND flag. |
3454 | * This is necessary as scheduler callbacks may be invoked |
3455 | * from other cpus. |
3456 | */ |
3457 | schedule(); |
3458 | |
3459 | /* |
3460 | * Sched callbacks are disabled now. Zap nr_running. |
3461 | * After this, nr_running stays zero and need_more_worker() |
3462 | * and keep_working() are always true as long as the |
3463 | * worklist is not empty. This pool now behaves as an |
3464 | * unbound (in terms of concurrency management) pool which |
3465 | * are served by workers tied to the pool. |
3466 | */ |
3467 | atomic_set(&pool->nr_running, 0); |
3468 | |
3469 | /* |
3470 | * With concurrency management just turned off, a busy |
3471 | * worker blocking could lead to lengthy stalls. Kick off |
3472 | * unbound chain execution of currently pending work items. |
3473 | */ |
3474 | spin_lock_irq(&pool->lock); |
3475 | wake_up_worker(pool); |
3476 | spin_unlock_irq(&pool->lock); |
3477 | } |
3478 | } |
3479 | |
3480 | /* |
3481 | * Workqueues should be brought up before normal priority CPU notifiers. |
3482 | * This will be registered high priority CPU notifier. |
3483 | */ |
3484 | static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb, |
3485 | unsigned long action, |
3486 | void *hcpu) |
3487 | { |
3488 | unsigned int cpu = (unsigned long)hcpu; |
3489 | struct worker_pool *pool; |
3490 | |
3491 | switch (action & ~CPU_TASKS_FROZEN) { |
3492 | case CPU_UP_PREPARE: |
3493 | for_each_std_worker_pool(pool, cpu) { |
3494 | struct worker *worker; |
3495 | |
3496 | if (pool->nr_workers) |
3497 | continue; |
3498 | |
3499 | worker = create_worker(pool); |
3500 | if (!worker) |
3501 | return NOTIFY_BAD; |
3502 | |
3503 | spin_lock_irq(&pool->lock); |
3504 | start_worker(worker); |
3505 | spin_unlock_irq(&pool->lock); |
3506 | } |
3507 | break; |
3508 | |
3509 | case CPU_DOWN_FAILED: |
3510 | case CPU_ONLINE: |
3511 | for_each_std_worker_pool(pool, cpu) { |
3512 | mutex_lock(&pool->assoc_mutex); |
3513 | spin_lock_irq(&pool->lock); |
3514 | |
3515 | pool->flags &= ~POOL_DISASSOCIATED; |
3516 | rebind_workers(pool); |
3517 | |
3518 | spin_unlock_irq(&pool->lock); |
3519 | mutex_unlock(&pool->assoc_mutex); |
3520 | } |
3521 | break; |
3522 | } |
3523 | return NOTIFY_OK; |
3524 | } |
3525 | |
3526 | /* |
3527 | * Workqueues should be brought down after normal priority CPU notifiers. |
3528 | * This will be registered as low priority CPU notifier. |
3529 | */ |
3530 | static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb, |
3531 | unsigned long action, |
3532 | void *hcpu) |
3533 | { |
3534 | unsigned int cpu = (unsigned long)hcpu; |
3535 | struct work_struct unbind_work; |
3536 | |
3537 | switch (action & ~CPU_TASKS_FROZEN) { |
3538 | case CPU_DOWN_PREPARE: |
3539 | /* unbinding should happen on the local CPU */ |
3540 | INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn); |
3541 | queue_work_on(cpu, system_highpri_wq, &unbind_work); |
3542 | flush_work(&unbind_work); |
3543 | break; |
3544 | } |
3545 | return NOTIFY_OK; |
3546 | } |
3547 | |
3548 | #ifdef CONFIG_SMP |
3549 | |
3550 | struct work_for_cpu { |
3551 | struct work_struct work; |
3552 | long (*fn)(void *); |
3553 | void *arg; |
3554 | long ret; |
3555 | }; |
3556 | |
3557 | static void work_for_cpu_fn(struct work_struct *work) |
3558 | { |
3559 | struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); |
3560 | |
3561 | wfc->ret = wfc->fn(wfc->arg); |
3562 | } |
3563 | |
3564 | /** |
3565 | * work_on_cpu - run a function in user context on a particular cpu |
3566 | * @cpu: the cpu to run on |
3567 | * @fn: the function to run |
3568 | * @arg: the function arg |
3569 | * |
3570 | * This will return the value @fn returns. |
3571 | * It is up to the caller to ensure that the cpu doesn't go offline. |
3572 | * The caller must not hold any locks which would prevent @fn from completing. |
3573 | */ |
3574 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) |
3575 | { |
3576 | struct work_for_cpu wfc = { .fn = fn, .arg = arg }; |
3577 | |
3578 | INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); |
3579 | schedule_work_on(cpu, &wfc.work); |
3580 | flush_work(&wfc.work); |
3581 | return wfc.ret; |
3582 | } |
3583 | EXPORT_SYMBOL_GPL(work_on_cpu); |
3584 | #endif /* CONFIG_SMP */ |
3585 | |
3586 | #ifdef CONFIG_FREEZER |
3587 | |
3588 | /** |
3589 | * freeze_workqueues_begin - begin freezing workqueues |
3590 | * |
3591 | * Start freezing workqueues. After this function returns, all freezable |
3592 | * workqueues will queue new works to their frozen_works list instead of |
3593 | * pool->worklist. |
3594 | * |
3595 | * CONTEXT: |
3596 | * Grabs and releases workqueue_lock and pool->lock's. |
3597 | */ |
3598 | void freeze_workqueues_begin(void) |
3599 | { |
3600 | unsigned int cpu; |
3601 | |
3602 | spin_lock(&workqueue_lock); |
3603 | |
3604 | BUG_ON(workqueue_freezing); |
3605 | workqueue_freezing = true; |
3606 | |
3607 | for_each_wq_cpu(cpu) { |
3608 | struct worker_pool *pool; |
3609 | struct workqueue_struct *wq; |
3610 | |
3611 | for_each_std_worker_pool(pool, cpu) { |
3612 | spin_lock_irq(&pool->lock); |
3613 | |
3614 | WARN_ON_ONCE(pool->flags & POOL_FREEZING); |
3615 | pool->flags |= POOL_FREEZING; |
3616 | |
3617 | list_for_each_entry(wq, &workqueues, list) { |
3618 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
3619 | |
3620 | if (pwq && pwq->pool == pool && |
3621 | (wq->flags & WQ_FREEZABLE)) |
3622 | pwq->max_active = 0; |
3623 | } |
3624 | |
3625 | spin_unlock_irq(&pool->lock); |
3626 | } |
3627 | } |
3628 | |
3629 | spin_unlock(&workqueue_lock); |
3630 | } |
3631 | |
3632 | /** |
3633 | * freeze_workqueues_busy - are freezable workqueues still busy? |
3634 | * |
3635 | * Check whether freezing is complete. This function must be called |
3636 | * between freeze_workqueues_begin() and thaw_workqueues(). |
3637 | * |
3638 | * CONTEXT: |
3639 | * Grabs and releases workqueue_lock. |
3640 | * |
3641 | * RETURNS: |
3642 | * %true if some freezable workqueues are still busy. %false if freezing |
3643 | * is complete. |
3644 | */ |
3645 | bool freeze_workqueues_busy(void) |
3646 | { |
3647 | unsigned int cpu; |
3648 | bool busy = false; |
3649 | |
3650 | spin_lock(&workqueue_lock); |
3651 | |
3652 | BUG_ON(!workqueue_freezing); |
3653 | |
3654 | for_each_wq_cpu(cpu) { |
3655 | struct workqueue_struct *wq; |
3656 | /* |
3657 | * nr_active is monotonically decreasing. It's safe |
3658 | * to peek without lock. |
3659 | */ |
3660 | list_for_each_entry(wq, &workqueues, list) { |
3661 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
3662 | |
3663 | if (!pwq || !(wq->flags & WQ_FREEZABLE)) |
3664 | continue; |
3665 | |
3666 | BUG_ON(pwq->nr_active < 0); |
3667 | if (pwq->nr_active) { |
3668 | busy = true; |
3669 | goto out_unlock; |
3670 | } |
3671 | } |
3672 | } |
3673 | out_unlock: |
3674 | spin_unlock(&workqueue_lock); |
3675 | return busy; |
3676 | } |
3677 | |
3678 | /** |
3679 | * thaw_workqueues - thaw workqueues |
3680 | * |
3681 | * Thaw workqueues. Normal queueing is restored and all collected |
3682 | * frozen works are transferred to their respective pool worklists. |
3683 | * |
3684 | * CONTEXT: |
3685 | * Grabs and releases workqueue_lock and pool->lock's. |
3686 | */ |
3687 | void thaw_workqueues(void) |
3688 | { |
3689 | unsigned int cpu; |
3690 | |
3691 | spin_lock(&workqueue_lock); |
3692 | |
3693 | if (!workqueue_freezing) |
3694 | goto out_unlock; |
3695 | |
3696 | for_each_wq_cpu(cpu) { |
3697 | struct worker_pool *pool; |
3698 | struct workqueue_struct *wq; |
3699 | |
3700 | for_each_std_worker_pool(pool, cpu) { |
3701 | spin_lock_irq(&pool->lock); |
3702 | |
3703 | WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); |
3704 | pool->flags &= ~POOL_FREEZING; |
3705 | |
3706 | list_for_each_entry(wq, &workqueues, list) { |
3707 | struct pool_workqueue *pwq = get_pwq(cpu, wq); |
3708 | |
3709 | if (!pwq || pwq->pool != pool || |
3710 | !(wq->flags & WQ_FREEZABLE)) |
3711 | continue; |
3712 | |
3713 | /* restore max_active and repopulate worklist */ |
3714 | pwq_set_max_active(pwq, wq->saved_max_active); |
3715 | } |
3716 | |
3717 | wake_up_worker(pool); |
3718 | |
3719 | spin_unlock_irq(&pool->lock); |
3720 | } |
3721 | } |
3722 | |
3723 | workqueue_freezing = false; |
3724 | out_unlock: |
3725 | spin_unlock(&workqueue_lock); |
3726 | } |
3727 | #endif /* CONFIG_FREEZER */ |
3728 | |
3729 | static int __init init_workqueues(void) |
3730 | { |
3731 | unsigned int cpu; |
3732 | |
3733 | /* make sure we have enough bits for OFFQ pool ID */ |
3734 | BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) < |
3735 | WORK_CPU_END * NR_STD_WORKER_POOLS); |
3736 | |
3737 | cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); |
3738 | hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); |
3739 | |
3740 | /* initialize CPU pools */ |
3741 | for_each_wq_cpu(cpu) { |
3742 | struct worker_pool *pool; |
3743 | |
3744 | for_each_std_worker_pool(pool, cpu) { |
3745 | spin_lock_init(&pool->lock); |
3746 | pool->cpu = cpu; |
3747 | pool->flags |= POOL_DISASSOCIATED; |
3748 | INIT_LIST_HEAD(&pool->worklist); |
3749 | INIT_LIST_HEAD(&pool->idle_list); |
3750 | hash_init(pool->busy_hash); |
3751 | |
3752 | init_timer_deferrable(&pool->idle_timer); |
3753 | pool->idle_timer.function = idle_worker_timeout; |
3754 | pool->idle_timer.data = (unsigned long)pool; |
3755 | |
3756 | setup_timer(&pool->mayday_timer, pool_mayday_timeout, |
3757 | (unsigned long)pool); |
3758 | |
3759 | mutex_init(&pool->assoc_mutex); |
3760 | ida_init(&pool->worker_ida); |
3761 | |
3762 | /* alloc pool ID */ |
3763 | BUG_ON(worker_pool_assign_id(pool)); |
3764 | } |
3765 | } |
3766 | |
3767 | /* create the initial worker */ |
3768 | for_each_online_wq_cpu(cpu) { |
3769 | struct worker_pool *pool; |
3770 | |
3771 | for_each_std_worker_pool(pool, cpu) { |
3772 | struct worker *worker; |
3773 | |
3774 | if (cpu != WORK_CPU_UNBOUND) |
3775 | pool->flags &= ~POOL_DISASSOCIATED; |
3776 | |
3777 | worker = create_worker(pool); |
3778 | BUG_ON(!worker); |
3779 | spin_lock_irq(&pool->lock); |
3780 | start_worker(worker); |
3781 | spin_unlock_irq(&pool->lock); |
3782 | } |
3783 | } |
3784 | |
3785 | system_wq = alloc_workqueue("events", 0, 0); |
3786 | system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); |
3787 | system_long_wq = alloc_workqueue("events_long", 0, 0); |
3788 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
3789 | WQ_UNBOUND_MAX_ACTIVE); |
3790 | system_freezable_wq = alloc_workqueue("events_freezable", |
3791 | WQ_FREEZABLE, 0); |
3792 | BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || |
3793 | !system_unbound_wq || !system_freezable_wq); |
3794 | return 0; |
3795 | } |
3796 | early_initcall(init_workqueues); |
3797 |
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