Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
c54fce6e | 2 | * kernel/workqueue.c - generic async execution with shared worker pool |
1da177e4 | 3 | * |
c54fce6e | 4 | * Copyright (C) 2002 Ingo Molnar |
1da177e4 | 5 | * |
c54fce6e TH |
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> | |
1da177e4 | 11 | * |
c54fce6e | 12 | * Made to use alloc_percpu by Christoph Lameter. |
1da177e4 | 13 | * |
c54fce6e TH |
14 | * Copyright (C) 2010 SUSE Linux Products GmbH |
15 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> | |
89ada679 | 16 | * |
c54fce6e TH |
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. | |
1da177e4 LT |
24 | */ |
25 | ||
9984de1a | 26 | #include <linux/export.h> |
1da177e4 LT |
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> | |
1fa44eca | 37 | #include <linux/hardirq.h> |
46934023 | 38 | #include <linux/mempolicy.h> |
341a5958 | 39 | #include <linux/freezer.h> |
d5abe669 PZ |
40 | #include <linux/kallsyms.h> |
41 | #include <linux/debug_locks.h> | |
4e6045f1 | 42 | #include <linux/lockdep.h> |
c34056a3 | 43 | #include <linux/idr.h> |
e22bee78 TH |
44 | |
45 | #include "workqueue_sched.h" | |
1da177e4 | 46 | |
c8e55f36 | 47 | enum { |
bc2ae0f5 TH |
48 | /* |
49 | * global_cwq flags | |
50 | * | |
51 | * A bound gcwq is either associated or disassociated with its CPU. | |
52 | * While associated (!DISASSOCIATED), all workers are bound to the | |
53 | * CPU and none has %WORKER_UNBOUND set and concurrency management | |
54 | * is in effect. | |
55 | * | |
56 | * While DISASSOCIATED, the cpu may be offline and all workers have | |
57 | * %WORKER_UNBOUND set and concurrency management disabled, and may | |
58 | * be executing on any CPU. The gcwq behaves as an unbound one. | |
59 | * | |
60 | * Note that DISASSOCIATED can be flipped only while holding | |
b2eb83d1 | 61 | * assoc_mutex of all pools on the gcwq to avoid changing binding |
bc2ae0f5 TH |
62 | * state while create_worker() is in progress. |
63 | */ | |
11ebea50 TH |
64 | GCWQ_DISASSOCIATED = 1 << 0, /* cpu can't serve workers */ |
65 | GCWQ_FREEZING = 1 << 1, /* freeze in progress */ | |
66 | ||
67 | /* pool flags */ | |
68 | POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ | |
552a37e9 | 69 | POOL_MANAGING_WORKERS = 1 << 1, /* managing workers */ |
db7bccf4 | 70 | |
c8e55f36 TH |
71 | /* worker flags */ |
72 | WORKER_STARTED = 1 << 0, /* started */ | |
73 | WORKER_DIE = 1 << 1, /* die die die */ | |
74 | WORKER_IDLE = 1 << 2, /* is idle */ | |
e22bee78 | 75 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
fb0e7beb | 76 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
f3421797 | 77 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
e22bee78 | 78 | |
5f7dabfd | 79 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_UNBOUND | |
403c821d | 80 | WORKER_CPU_INTENSIVE, |
db7bccf4 | 81 | |
3270476a | 82 | NR_WORKER_POOLS = 2, /* # worker pools per gcwq */ |
4ce62e9e | 83 | |
c8e55f36 TH |
84 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
85 | BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, | |
86 | BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, | |
db7bccf4 | 87 | |
e22bee78 TH |
88 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
89 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ | |
90 | ||
3233cdbd TH |
91 | MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, |
92 | /* call for help after 10ms | |
93 | (min two ticks) */ | |
e22bee78 TH |
94 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
95 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ | |
e22bee78 TH |
96 | |
97 | /* | |
98 | * Rescue workers are used only on emergencies and shared by | |
99 | * all cpus. Give -20. | |
100 | */ | |
101 | RESCUER_NICE_LEVEL = -20, | |
3270476a | 102 | HIGHPRI_NICE_LEVEL = -20, |
c8e55f36 | 103 | }; |
1da177e4 LT |
104 | |
105 | /* | |
4690c4ab TH |
106 | * Structure fields follow one of the following exclusion rules. |
107 | * | |
e41e704b TH |
108 | * I: Modifiable by initialization/destruction paths and read-only for |
109 | * everyone else. | |
4690c4ab | 110 | * |
e22bee78 TH |
111 | * P: Preemption protected. Disabling preemption is enough and should |
112 | * only be modified and accessed from the local cpu. | |
113 | * | |
8b03ae3c | 114 | * L: gcwq->lock protected. Access with gcwq->lock held. |
4690c4ab | 115 | * |
e22bee78 TH |
116 | * X: During normal operation, modification requires gcwq->lock and |
117 | * should be done only from local cpu. Either disabling preemption | |
118 | * on local cpu or grabbing gcwq->lock is enough for read access. | |
f3421797 | 119 | * If GCWQ_DISASSOCIATED is set, it's identical to L. |
e22bee78 | 120 | * |
73f53c4a TH |
121 | * F: wq->flush_mutex protected. |
122 | * | |
4690c4ab | 123 | * W: workqueue_lock protected. |
1da177e4 | 124 | */ |
1da177e4 | 125 | |
8b03ae3c | 126 | struct global_cwq; |
bd7bdd43 | 127 | struct worker_pool; |
1da177e4 | 128 | |
e22bee78 TH |
129 | /* |
130 | * The poor guys doing the actual heavy lifting. All on-duty workers | |
131 | * are either serving the manager role, on idle list or on busy hash. | |
132 | */ | |
c34056a3 | 133 | struct worker { |
c8e55f36 TH |
134 | /* on idle list while idle, on busy hash table while busy */ |
135 | union { | |
136 | struct list_head entry; /* L: while idle */ | |
137 | struct hlist_node hentry; /* L: while busy */ | |
138 | }; | |
1da177e4 | 139 | |
c34056a3 | 140 | struct work_struct *current_work; /* L: work being processed */ |
8cca0eea | 141 | struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ |
affee4b2 | 142 | struct list_head scheduled; /* L: scheduled works */ |
c34056a3 | 143 | struct task_struct *task; /* I: worker task */ |
bd7bdd43 | 144 | struct worker_pool *pool; /* I: the associated pool */ |
e22bee78 TH |
145 | /* 64 bytes boundary on 64bit, 32 on 32bit */ |
146 | unsigned long last_active; /* L: last active timestamp */ | |
147 | unsigned int flags; /* X: flags */ | |
c34056a3 | 148 | int id; /* I: worker id */ |
25511a47 TH |
149 | |
150 | /* for rebinding worker to CPU */ | |
25511a47 | 151 | struct work_struct rebind_work; /* L: for busy worker */ |
c34056a3 TH |
152 | }; |
153 | ||
bd7bdd43 TH |
154 | struct worker_pool { |
155 | struct global_cwq *gcwq; /* I: the owning gcwq */ | |
11ebea50 | 156 | unsigned int flags; /* X: flags */ |
bd7bdd43 TH |
157 | |
158 | struct list_head worklist; /* L: list of pending works */ | |
159 | int nr_workers; /* L: total number of workers */ | |
ea1abd61 LJ |
160 | |
161 | /* nr_idle includes the ones off idle_list for rebinding */ | |
bd7bdd43 TH |
162 | int nr_idle; /* L: currently idle ones */ |
163 | ||
164 | struct list_head idle_list; /* X: list of idle workers */ | |
165 | struct timer_list idle_timer; /* L: worker idle timeout */ | |
166 | struct timer_list mayday_timer; /* L: SOS timer for workers */ | |
167 | ||
b2eb83d1 | 168 | struct mutex assoc_mutex; /* protect GCWQ_DISASSOCIATED */ |
bd7bdd43 | 169 | struct ida worker_ida; /* L: for worker IDs */ |
bd7bdd43 TH |
170 | }; |
171 | ||
8b03ae3c | 172 | /* |
e22bee78 TH |
173 | * Global per-cpu workqueue. There's one and only one for each cpu |
174 | * and all works are queued and processed here regardless of their | |
175 | * target workqueues. | |
8b03ae3c TH |
176 | */ |
177 | struct global_cwq { | |
178 | spinlock_t lock; /* the gcwq lock */ | |
179 | unsigned int cpu; /* I: the associated cpu */ | |
db7bccf4 | 180 | unsigned int flags; /* L: GCWQ_* flags */ |
c8e55f36 | 181 | |
bd7bdd43 | 182 | /* workers are chained either in busy_hash or pool idle_list */ |
c8e55f36 TH |
183 | struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; |
184 | /* L: hash of busy workers */ | |
185 | ||
330dad5b JK |
186 | struct worker_pool pools[NR_WORKER_POOLS]; |
187 | /* normal and highpri pools */ | |
8b03ae3c TH |
188 | } ____cacheline_aligned_in_smp; |
189 | ||
1da177e4 | 190 | /* |
502ca9d8 | 191 | * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of |
0f900049 TH |
192 | * work_struct->data are used for flags and thus cwqs need to be |
193 | * aligned at two's power of the number of flag bits. | |
1da177e4 LT |
194 | */ |
195 | struct cpu_workqueue_struct { | |
bd7bdd43 | 196 | struct worker_pool *pool; /* I: the associated pool */ |
4690c4ab | 197 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
73f53c4a TH |
198 | int work_color; /* L: current color */ |
199 | int flush_color; /* L: flushing color */ | |
200 | int nr_in_flight[WORK_NR_COLORS]; | |
201 | /* L: nr of in_flight works */ | |
1e19ffc6 | 202 | int nr_active; /* L: nr of active works */ |
a0a1a5fd | 203 | int max_active; /* L: max active works */ |
1e19ffc6 | 204 | struct list_head delayed_works; /* L: delayed works */ |
0f900049 | 205 | }; |
1da177e4 | 206 | |
73f53c4a TH |
207 | /* |
208 | * Structure used to wait for workqueue flush. | |
209 | */ | |
210 | struct wq_flusher { | |
211 | struct list_head list; /* F: list of flushers */ | |
212 | int flush_color; /* F: flush color waiting for */ | |
213 | struct completion done; /* flush completion */ | |
214 | }; | |
215 | ||
f2e005aa TH |
216 | /* |
217 | * All cpumasks are assumed to be always set on UP and thus can't be | |
218 | * used to determine whether there's something to be done. | |
219 | */ | |
220 | #ifdef CONFIG_SMP | |
221 | typedef cpumask_var_t mayday_mask_t; | |
222 | #define mayday_test_and_set_cpu(cpu, mask) \ | |
223 | cpumask_test_and_set_cpu((cpu), (mask)) | |
224 | #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) | |
225 | #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) | |
9c37547a | 226 | #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) |
f2e005aa TH |
227 | #define free_mayday_mask(mask) free_cpumask_var((mask)) |
228 | #else | |
229 | typedef unsigned long mayday_mask_t; | |
230 | #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) | |
231 | #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) | |
232 | #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) | |
233 | #define alloc_mayday_mask(maskp, gfp) true | |
234 | #define free_mayday_mask(mask) do { } while (0) | |
235 | #endif | |
1da177e4 LT |
236 | |
237 | /* | |
238 | * The externally visible workqueue abstraction is an array of | |
239 | * per-CPU workqueues: | |
240 | */ | |
241 | struct workqueue_struct { | |
9c5a2ba7 | 242 | unsigned int flags; /* W: WQ_* flags */ |
bdbc5dd7 TH |
243 | union { |
244 | struct cpu_workqueue_struct __percpu *pcpu; | |
245 | struct cpu_workqueue_struct *single; | |
246 | unsigned long v; | |
247 | } cpu_wq; /* I: cwq's */ | |
4690c4ab | 248 | struct list_head list; /* W: list of all workqueues */ |
73f53c4a TH |
249 | |
250 | struct mutex flush_mutex; /* protects wq flushing */ | |
251 | int work_color; /* F: current work color */ | |
252 | int flush_color; /* F: current flush color */ | |
253 | atomic_t nr_cwqs_to_flush; /* flush in progress */ | |
254 | struct wq_flusher *first_flusher; /* F: first flusher */ | |
255 | struct list_head flusher_queue; /* F: flush waiters */ | |
256 | struct list_head flusher_overflow; /* F: flush overflow list */ | |
257 | ||
f2e005aa | 258 | mayday_mask_t mayday_mask; /* cpus requesting rescue */ |
e22bee78 TH |
259 | struct worker *rescuer; /* I: rescue worker */ |
260 | ||
9c5a2ba7 | 261 | int nr_drainers; /* W: drain in progress */ |
dcd989cb | 262 | int saved_max_active; /* W: saved cwq max_active */ |
4e6045f1 | 263 | #ifdef CONFIG_LOCKDEP |
4690c4ab | 264 | struct lockdep_map lockdep_map; |
4e6045f1 | 265 | #endif |
b196be89 | 266 | char name[]; /* I: workqueue name */ |
1da177e4 LT |
267 | }; |
268 | ||
d320c038 | 269 | struct workqueue_struct *system_wq __read_mostly; |
d320c038 | 270 | EXPORT_SYMBOL_GPL(system_wq); |
044c782c | 271 | struct workqueue_struct *system_highpri_wq __read_mostly; |
1aabe902 | 272 | EXPORT_SYMBOL_GPL(system_highpri_wq); |
044c782c | 273 | struct workqueue_struct *system_long_wq __read_mostly; |
d320c038 | 274 | EXPORT_SYMBOL_GPL(system_long_wq); |
044c782c | 275 | struct workqueue_struct *system_unbound_wq __read_mostly; |
f3421797 | 276 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
044c782c | 277 | struct workqueue_struct *system_freezable_wq __read_mostly; |
24d51add | 278 | EXPORT_SYMBOL_GPL(system_freezable_wq); |
d320c038 | 279 | |
97bd2347 TH |
280 | #define CREATE_TRACE_POINTS |
281 | #include <trace/events/workqueue.h> | |
282 | ||
4ce62e9e | 283 | #define for_each_worker_pool(pool, gcwq) \ |
3270476a TH |
284 | for ((pool) = &(gcwq)->pools[0]; \ |
285 | (pool) < &(gcwq)->pools[NR_WORKER_POOLS]; (pool)++) | |
4ce62e9e | 286 | |
db7bccf4 TH |
287 | #define for_each_busy_worker(worker, i, pos, gcwq) \ |
288 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ | |
289 | hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) | |
290 | ||
f3421797 TH |
291 | static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, |
292 | unsigned int sw) | |
293 | { | |
294 | if (cpu < nr_cpu_ids) { | |
295 | if (sw & 1) { | |
296 | cpu = cpumask_next(cpu, mask); | |
297 | if (cpu < nr_cpu_ids) | |
298 | return cpu; | |
299 | } | |
300 | if (sw & 2) | |
301 | return WORK_CPU_UNBOUND; | |
302 | } | |
303 | return WORK_CPU_NONE; | |
304 | } | |
305 | ||
306 | static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, | |
307 | struct workqueue_struct *wq) | |
308 | { | |
309 | return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); | |
310 | } | |
311 | ||
09884951 TH |
312 | /* |
313 | * CPU iterators | |
314 | * | |
315 | * An extra gcwq is defined for an invalid cpu number | |
316 | * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any | |
317 | * specific CPU. The following iterators are similar to | |
318 | * for_each_*_cpu() iterators but also considers the unbound gcwq. | |
319 | * | |
320 | * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND | |
321 | * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND | |
322 | * for_each_cwq_cpu() : possible CPUs for bound workqueues, | |
323 | * WORK_CPU_UNBOUND for unbound workqueues | |
324 | */ | |
f3421797 TH |
325 | #define for_each_gcwq_cpu(cpu) \ |
326 | for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ | |
327 | (cpu) < WORK_CPU_NONE; \ | |
328 | (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) | |
329 | ||
330 | #define for_each_online_gcwq_cpu(cpu) \ | |
331 | for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ | |
332 | (cpu) < WORK_CPU_NONE; \ | |
333 | (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) | |
334 | ||
335 | #define for_each_cwq_cpu(cpu, wq) \ | |
336 | for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ | |
337 | (cpu) < WORK_CPU_NONE; \ | |
338 | (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) | |
339 | ||
dc186ad7 TG |
340 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
341 | ||
342 | static struct debug_obj_descr work_debug_descr; | |
343 | ||
99777288 SG |
344 | static void *work_debug_hint(void *addr) |
345 | { | |
346 | return ((struct work_struct *) addr)->func; | |
347 | } | |
348 | ||
dc186ad7 TG |
349 | /* |
350 | * fixup_init is called when: | |
351 | * - an active object is initialized | |
352 | */ | |
353 | static int work_fixup_init(void *addr, enum debug_obj_state state) | |
354 | { | |
355 | struct work_struct *work = addr; | |
356 | ||
357 | switch (state) { | |
358 | case ODEBUG_STATE_ACTIVE: | |
359 | cancel_work_sync(work); | |
360 | debug_object_init(work, &work_debug_descr); | |
361 | return 1; | |
362 | default: | |
363 | return 0; | |
364 | } | |
365 | } | |
366 | ||
367 | /* | |
368 | * fixup_activate is called when: | |
369 | * - an active object is activated | |
370 | * - an unknown object is activated (might be a statically initialized object) | |
371 | */ | |
372 | static int work_fixup_activate(void *addr, enum debug_obj_state state) | |
373 | { | |
374 | struct work_struct *work = addr; | |
375 | ||
376 | switch (state) { | |
377 | ||
378 | case ODEBUG_STATE_NOTAVAILABLE: | |
379 | /* | |
380 | * This is not really a fixup. The work struct was | |
381 | * statically initialized. We just make sure that it | |
382 | * is tracked in the object tracker. | |
383 | */ | |
22df02bb | 384 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
dc186ad7 TG |
385 | debug_object_init(work, &work_debug_descr); |
386 | debug_object_activate(work, &work_debug_descr); | |
387 | return 0; | |
388 | } | |
389 | WARN_ON_ONCE(1); | |
390 | return 0; | |
391 | ||
392 | case ODEBUG_STATE_ACTIVE: | |
393 | WARN_ON(1); | |
394 | ||
395 | default: | |
396 | return 0; | |
397 | } | |
398 | } | |
399 | ||
400 | /* | |
401 | * fixup_free is called when: | |
402 | * - an active object is freed | |
403 | */ | |
404 | static int work_fixup_free(void *addr, enum debug_obj_state state) | |
405 | { | |
406 | struct work_struct *work = addr; | |
407 | ||
408 | switch (state) { | |
409 | case ODEBUG_STATE_ACTIVE: | |
410 | cancel_work_sync(work); | |
411 | debug_object_free(work, &work_debug_descr); | |
412 | return 1; | |
413 | default: | |
414 | return 0; | |
415 | } | |
416 | } | |
417 | ||
418 | static struct debug_obj_descr work_debug_descr = { | |
419 | .name = "work_struct", | |
99777288 | 420 | .debug_hint = work_debug_hint, |
dc186ad7 TG |
421 | .fixup_init = work_fixup_init, |
422 | .fixup_activate = work_fixup_activate, | |
423 | .fixup_free = work_fixup_free, | |
424 | }; | |
425 | ||
426 | static inline void debug_work_activate(struct work_struct *work) | |
427 | { | |
428 | debug_object_activate(work, &work_debug_descr); | |
429 | } | |
430 | ||
431 | static inline void debug_work_deactivate(struct work_struct *work) | |
432 | { | |
433 | debug_object_deactivate(work, &work_debug_descr); | |
434 | } | |
435 | ||
436 | void __init_work(struct work_struct *work, int onstack) | |
437 | { | |
438 | if (onstack) | |
439 | debug_object_init_on_stack(work, &work_debug_descr); | |
440 | else | |
441 | debug_object_init(work, &work_debug_descr); | |
442 | } | |
443 | EXPORT_SYMBOL_GPL(__init_work); | |
444 | ||
445 | void destroy_work_on_stack(struct work_struct *work) | |
446 | { | |
447 | debug_object_free(work, &work_debug_descr); | |
448 | } | |
449 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); | |
450 | ||
451 | #else | |
452 | static inline void debug_work_activate(struct work_struct *work) { } | |
453 | static inline void debug_work_deactivate(struct work_struct *work) { } | |
454 | #endif | |
455 | ||
95402b38 GS |
456 | /* Serializes the accesses to the list of workqueues. */ |
457 | static DEFINE_SPINLOCK(workqueue_lock); | |
1da177e4 | 458 | static LIST_HEAD(workqueues); |
a0a1a5fd | 459 | static bool workqueue_freezing; /* W: have wqs started freezing? */ |
c34056a3 | 460 | |
e22bee78 TH |
461 | /* |
462 | * The almighty global cpu workqueues. nr_running is the only field | |
463 | * which is expected to be used frequently by other cpus via | |
464 | * try_to_wake_up(). Put it in a separate cacheline. | |
465 | */ | |
8b03ae3c | 466 | static DEFINE_PER_CPU(struct global_cwq, global_cwq); |
4ce62e9e | 467 | static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_WORKER_POOLS]); |
8b03ae3c | 468 | |
f3421797 TH |
469 | /* |
470 | * Global cpu workqueue and nr_running counter for unbound gcwq. The | |
471 | * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its | |
472 | * workers have WORKER_UNBOUND set. | |
473 | */ | |
474 | static struct global_cwq unbound_global_cwq; | |
4ce62e9e TH |
475 | static atomic_t unbound_pool_nr_running[NR_WORKER_POOLS] = { |
476 | [0 ... NR_WORKER_POOLS - 1] = ATOMIC_INIT(0), /* always 0 */ | |
477 | }; | |
f3421797 | 478 | |
c34056a3 | 479 | static int worker_thread(void *__worker); |
1da177e4 | 480 | |
3270476a TH |
481 | static int worker_pool_pri(struct worker_pool *pool) |
482 | { | |
483 | return pool - pool->gcwq->pools; | |
484 | } | |
485 | ||
8b03ae3c TH |
486 | static struct global_cwq *get_gcwq(unsigned int cpu) |
487 | { | |
f3421797 TH |
488 | if (cpu != WORK_CPU_UNBOUND) |
489 | return &per_cpu(global_cwq, cpu); | |
490 | else | |
491 | return &unbound_global_cwq; | |
8b03ae3c TH |
492 | } |
493 | ||
63d95a91 | 494 | static atomic_t *get_pool_nr_running(struct worker_pool *pool) |
e22bee78 | 495 | { |
63d95a91 | 496 | int cpu = pool->gcwq->cpu; |
3270476a | 497 | int idx = worker_pool_pri(pool); |
63d95a91 | 498 | |
f3421797 | 499 | if (cpu != WORK_CPU_UNBOUND) |
4ce62e9e | 500 | return &per_cpu(pool_nr_running, cpu)[idx]; |
f3421797 | 501 | else |
4ce62e9e | 502 | return &unbound_pool_nr_running[idx]; |
e22bee78 TH |
503 | } |
504 | ||
1537663f TH |
505 | static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
506 | struct workqueue_struct *wq) | |
b1f4ec17 | 507 | { |
f3421797 | 508 | if (!(wq->flags & WQ_UNBOUND)) { |
e06ffa1e | 509 | if (likely(cpu < nr_cpu_ids)) |
f3421797 | 510 | return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); |
f3421797 TH |
511 | } else if (likely(cpu == WORK_CPU_UNBOUND)) |
512 | return wq->cpu_wq.single; | |
513 | return NULL; | |
b1f4ec17 ON |
514 | } |
515 | ||
73f53c4a TH |
516 | static unsigned int work_color_to_flags(int color) |
517 | { | |
518 | return color << WORK_STRUCT_COLOR_SHIFT; | |
519 | } | |
520 | ||
521 | static int get_work_color(struct work_struct *work) | |
522 | { | |
523 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & | |
524 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); | |
525 | } | |
526 | ||
527 | static int work_next_color(int color) | |
528 | { | |
529 | return (color + 1) % WORK_NR_COLORS; | |
530 | } | |
1da177e4 | 531 | |
14441960 | 532 | /* |
b5490077 TH |
533 | * While queued, %WORK_STRUCT_CWQ is set and non flag bits of a work's data |
534 | * contain the pointer to the queued cwq. Once execution starts, the flag | |
535 | * is cleared and the high bits contain OFFQ flags and CPU number. | |
7a22ad75 | 536 | * |
bbb68dfa TH |
537 | * set_work_cwq(), set_work_cpu_and_clear_pending(), mark_work_canceling() |
538 | * and clear_work_data() can be used to set the cwq, cpu or clear | |
539 | * work->data. These functions should only be called while the work is | |
540 | * owned - ie. while the PENDING bit is set. | |
7a22ad75 | 541 | * |
bbb68dfa TH |
542 | * get_work_[g]cwq() can be used to obtain the gcwq or cwq corresponding to |
543 | * a work. gcwq is available once the work has been queued anywhere after | |
544 | * initialization until it is sync canceled. cwq is available only while | |
545 | * the work item is queued. | |
7a22ad75 | 546 | * |
bbb68dfa TH |
547 | * %WORK_OFFQ_CANCELING is used to mark a work item which is being |
548 | * canceled. While being canceled, a work item may have its PENDING set | |
549 | * but stay off timer and worklist for arbitrarily long and nobody should | |
550 | * try to steal the PENDING bit. | |
14441960 | 551 | */ |
7a22ad75 TH |
552 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
553 | unsigned long flags) | |
365970a1 | 554 | { |
4594bf15 | 555 | BUG_ON(!work_pending(work)); |
7a22ad75 TH |
556 | atomic_long_set(&work->data, data | flags | work_static(work)); |
557 | } | |
365970a1 | 558 | |
7a22ad75 TH |
559 | static void set_work_cwq(struct work_struct *work, |
560 | struct cpu_workqueue_struct *cwq, | |
561 | unsigned long extra_flags) | |
562 | { | |
563 | set_work_data(work, (unsigned long)cwq, | |
e120153d | 564 | WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); |
365970a1 DH |
565 | } |
566 | ||
8930caba TH |
567 | static void set_work_cpu_and_clear_pending(struct work_struct *work, |
568 | unsigned int cpu) | |
7a22ad75 | 569 | { |
23657bb1 TH |
570 | /* |
571 | * The following wmb is paired with the implied mb in | |
572 | * test_and_set_bit(PENDING) and ensures all updates to @work made | |
573 | * here are visible to and precede any updates by the next PENDING | |
574 | * owner. | |
575 | */ | |
576 | smp_wmb(); | |
b5490077 | 577 | set_work_data(work, (unsigned long)cpu << WORK_OFFQ_CPU_SHIFT, 0); |
7a22ad75 | 578 | } |
f756d5e2 | 579 | |
7a22ad75 | 580 | static void clear_work_data(struct work_struct *work) |
1da177e4 | 581 | { |
23657bb1 | 582 | smp_wmb(); /* see set_work_cpu_and_clear_pending() */ |
7a22ad75 | 583 | set_work_data(work, WORK_STRUCT_NO_CPU, 0); |
1da177e4 LT |
584 | } |
585 | ||
7a22ad75 | 586 | static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) |
b1f4ec17 | 587 | { |
e120153d | 588 | unsigned long data = atomic_long_read(&work->data); |
7a22ad75 | 589 | |
e120153d TH |
590 | if (data & WORK_STRUCT_CWQ) |
591 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); | |
592 | else | |
593 | return NULL; | |
4d707b9f ON |
594 | } |
595 | ||
7a22ad75 | 596 | static struct global_cwq *get_work_gcwq(struct work_struct *work) |
365970a1 | 597 | { |
e120153d | 598 | unsigned long data = atomic_long_read(&work->data); |
7a22ad75 TH |
599 | unsigned int cpu; |
600 | ||
e120153d TH |
601 | if (data & WORK_STRUCT_CWQ) |
602 | return ((struct cpu_workqueue_struct *) | |
bd7bdd43 | 603 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq; |
7a22ad75 | 604 | |
b5490077 | 605 | cpu = data >> WORK_OFFQ_CPU_SHIFT; |
bdbc5dd7 | 606 | if (cpu == WORK_CPU_NONE) |
7a22ad75 TH |
607 | return NULL; |
608 | ||
f3421797 | 609 | BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); |
7a22ad75 | 610 | return get_gcwq(cpu); |
b1f4ec17 ON |
611 | } |
612 | ||
bbb68dfa TH |
613 | static void mark_work_canceling(struct work_struct *work) |
614 | { | |
615 | struct global_cwq *gcwq = get_work_gcwq(work); | |
616 | unsigned long cpu = gcwq ? gcwq->cpu : WORK_CPU_NONE; | |
617 | ||
618 | set_work_data(work, (cpu << WORK_OFFQ_CPU_SHIFT) | WORK_OFFQ_CANCELING, | |
619 | WORK_STRUCT_PENDING); | |
620 | } | |
621 | ||
622 | static bool work_is_canceling(struct work_struct *work) | |
623 | { | |
624 | unsigned long data = atomic_long_read(&work->data); | |
625 | ||
626 | return !(data & WORK_STRUCT_CWQ) && (data & WORK_OFFQ_CANCELING); | |
627 | } | |
628 | ||
e22bee78 | 629 | /* |
3270476a TH |
630 | * Policy functions. These define the policies on how the global worker |
631 | * pools are managed. Unless noted otherwise, these functions assume that | |
632 | * they're being called with gcwq->lock held. | |
e22bee78 TH |
633 | */ |
634 | ||
63d95a91 | 635 | static bool __need_more_worker(struct worker_pool *pool) |
a848e3b6 | 636 | { |
3270476a | 637 | return !atomic_read(get_pool_nr_running(pool)); |
a848e3b6 ON |
638 | } |
639 | ||
4594bf15 | 640 | /* |
e22bee78 TH |
641 | * Need to wake up a worker? Called from anything but currently |
642 | * running workers. | |
974271c4 TH |
643 | * |
644 | * Note that, because unbound workers never contribute to nr_running, this | |
645 | * function will always return %true for unbound gcwq as long as the | |
646 | * worklist isn't empty. | |
4594bf15 | 647 | */ |
63d95a91 | 648 | static bool need_more_worker(struct worker_pool *pool) |
365970a1 | 649 | { |
63d95a91 | 650 | return !list_empty(&pool->worklist) && __need_more_worker(pool); |
e22bee78 | 651 | } |
4594bf15 | 652 | |
e22bee78 | 653 | /* Can I start working? Called from busy but !running workers. */ |
63d95a91 | 654 | static bool may_start_working(struct worker_pool *pool) |
e22bee78 | 655 | { |
63d95a91 | 656 | return pool->nr_idle; |
e22bee78 TH |
657 | } |
658 | ||
659 | /* Do I need to keep working? Called from currently running workers. */ | |
63d95a91 | 660 | static bool keep_working(struct worker_pool *pool) |
e22bee78 | 661 | { |
63d95a91 | 662 | atomic_t *nr_running = get_pool_nr_running(pool); |
e22bee78 | 663 | |
3270476a | 664 | return !list_empty(&pool->worklist) && atomic_read(nr_running) <= 1; |
e22bee78 TH |
665 | } |
666 | ||
667 | /* Do we need a new worker? Called from manager. */ | |
63d95a91 | 668 | static bool need_to_create_worker(struct worker_pool *pool) |
e22bee78 | 669 | { |
63d95a91 | 670 | return need_more_worker(pool) && !may_start_working(pool); |
e22bee78 | 671 | } |
365970a1 | 672 | |
e22bee78 | 673 | /* Do I need to be the manager? */ |
63d95a91 | 674 | static bool need_to_manage_workers(struct worker_pool *pool) |
e22bee78 | 675 | { |
63d95a91 | 676 | return need_to_create_worker(pool) || |
11ebea50 | 677 | (pool->flags & POOL_MANAGE_WORKERS); |
e22bee78 TH |
678 | } |
679 | ||
680 | /* Do we have too many workers and should some go away? */ | |
63d95a91 | 681 | static bool too_many_workers(struct worker_pool *pool) |
e22bee78 | 682 | { |
552a37e9 | 683 | bool managing = pool->flags & POOL_MANAGING_WORKERS; |
63d95a91 TH |
684 | int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ |
685 | int nr_busy = pool->nr_workers - nr_idle; | |
e22bee78 | 686 | |
ea1abd61 LJ |
687 | /* |
688 | * nr_idle and idle_list may disagree if idle rebinding is in | |
689 | * progress. Never return %true if idle_list is empty. | |
690 | */ | |
691 | if (list_empty(&pool->idle_list)) | |
692 | return false; | |
693 | ||
e22bee78 | 694 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
365970a1 DH |
695 | } |
696 | ||
4d707b9f | 697 | /* |
e22bee78 TH |
698 | * Wake up functions. |
699 | */ | |
700 | ||
7e11629d | 701 | /* Return the first worker. Safe with preemption disabled */ |
63d95a91 | 702 | static struct worker *first_worker(struct worker_pool *pool) |
7e11629d | 703 | { |
63d95a91 | 704 | if (unlikely(list_empty(&pool->idle_list))) |
7e11629d TH |
705 | return NULL; |
706 | ||
63d95a91 | 707 | return list_first_entry(&pool->idle_list, struct worker, entry); |
7e11629d TH |
708 | } |
709 | ||
710 | /** | |
711 | * wake_up_worker - wake up an idle worker | |
63d95a91 | 712 | * @pool: worker pool to wake worker from |
7e11629d | 713 | * |
63d95a91 | 714 | * Wake up the first idle worker of @pool. |
7e11629d TH |
715 | * |
716 | * CONTEXT: | |
717 | * spin_lock_irq(gcwq->lock). | |
718 | */ | |
63d95a91 | 719 | static void wake_up_worker(struct worker_pool *pool) |
7e11629d | 720 | { |
63d95a91 | 721 | struct worker *worker = first_worker(pool); |
7e11629d TH |
722 | |
723 | if (likely(worker)) | |
724 | wake_up_process(worker->task); | |
725 | } | |
726 | ||
d302f017 | 727 | /** |
e22bee78 TH |
728 | * wq_worker_waking_up - a worker is waking up |
729 | * @task: task waking up | |
730 | * @cpu: CPU @task is waking up to | |
731 | * | |
732 | * This function is called during try_to_wake_up() when a worker is | |
733 | * being awoken. | |
734 | * | |
735 | * CONTEXT: | |
736 | * spin_lock_irq(rq->lock) | |
737 | */ | |
738 | void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) | |
739 | { | |
740 | struct worker *worker = kthread_data(task); | |
741 | ||
36576000 JK |
742 | if (!(worker->flags & WORKER_NOT_RUNNING)) { |
743 | WARN_ON_ONCE(worker->pool->gcwq->cpu != cpu); | |
63d95a91 | 744 | atomic_inc(get_pool_nr_running(worker->pool)); |
36576000 | 745 | } |
e22bee78 TH |
746 | } |
747 | ||
748 | /** | |
749 | * wq_worker_sleeping - a worker is going to sleep | |
750 | * @task: task going to sleep | |
751 | * @cpu: CPU in question, must be the current CPU number | |
752 | * | |
753 | * This function is called during schedule() when a busy worker is | |
754 | * going to sleep. Worker on the same cpu can be woken up by | |
755 | * returning pointer to its task. | |
756 | * | |
757 | * CONTEXT: | |
758 | * spin_lock_irq(rq->lock) | |
759 | * | |
760 | * RETURNS: | |
761 | * Worker task on @cpu to wake up, %NULL if none. | |
762 | */ | |
763 | struct task_struct *wq_worker_sleeping(struct task_struct *task, | |
764 | unsigned int cpu) | |
765 | { | |
766 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; | |
bd7bdd43 | 767 | struct worker_pool *pool = worker->pool; |
63d95a91 | 768 | atomic_t *nr_running = get_pool_nr_running(pool); |
e22bee78 | 769 | |
2d64672e | 770 | if (worker->flags & WORKER_NOT_RUNNING) |
e22bee78 TH |
771 | return NULL; |
772 | ||
773 | /* this can only happen on the local cpu */ | |
774 | BUG_ON(cpu != raw_smp_processor_id()); | |
775 | ||
776 | /* | |
777 | * The counterpart of the following dec_and_test, implied mb, | |
778 | * worklist not empty test sequence is in insert_work(). | |
779 | * Please read comment there. | |
780 | * | |
628c78e7 TH |
781 | * NOT_RUNNING is clear. This means that we're bound to and |
782 | * running on the local cpu w/ rq lock held and preemption | |
783 | * disabled, which in turn means that none else could be | |
784 | * manipulating idle_list, so dereferencing idle_list without gcwq | |
785 | * lock is safe. | |
e22bee78 | 786 | */ |
bd7bdd43 | 787 | if (atomic_dec_and_test(nr_running) && !list_empty(&pool->worklist)) |
63d95a91 | 788 | to_wakeup = first_worker(pool); |
e22bee78 TH |
789 | return to_wakeup ? to_wakeup->task : NULL; |
790 | } | |
791 | ||
792 | /** | |
793 | * worker_set_flags - set worker flags and adjust nr_running accordingly | |
cb444766 | 794 | * @worker: self |
d302f017 TH |
795 | * @flags: flags to set |
796 | * @wakeup: wakeup an idle worker if necessary | |
797 | * | |
e22bee78 TH |
798 | * Set @flags in @worker->flags and adjust nr_running accordingly. If |
799 | * nr_running becomes zero and @wakeup is %true, an idle worker is | |
800 | * woken up. | |
d302f017 | 801 | * |
cb444766 TH |
802 | * CONTEXT: |
803 | * spin_lock_irq(gcwq->lock) | |
d302f017 TH |
804 | */ |
805 | static inline void worker_set_flags(struct worker *worker, unsigned int flags, | |
806 | bool wakeup) | |
807 | { | |
bd7bdd43 | 808 | struct worker_pool *pool = worker->pool; |
e22bee78 | 809 | |
cb444766 TH |
810 | WARN_ON_ONCE(worker->task != current); |
811 | ||
e22bee78 TH |
812 | /* |
813 | * If transitioning into NOT_RUNNING, adjust nr_running and | |
814 | * wake up an idle worker as necessary if requested by | |
815 | * @wakeup. | |
816 | */ | |
817 | if ((flags & WORKER_NOT_RUNNING) && | |
818 | !(worker->flags & WORKER_NOT_RUNNING)) { | |
63d95a91 | 819 | atomic_t *nr_running = get_pool_nr_running(pool); |
e22bee78 TH |
820 | |
821 | if (wakeup) { | |
822 | if (atomic_dec_and_test(nr_running) && | |
bd7bdd43 | 823 | !list_empty(&pool->worklist)) |
63d95a91 | 824 | wake_up_worker(pool); |
e22bee78 TH |
825 | } else |
826 | atomic_dec(nr_running); | |
827 | } | |
828 | ||
d302f017 TH |
829 | worker->flags |= flags; |
830 | } | |
831 | ||
832 | /** | |
e22bee78 | 833 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
cb444766 | 834 | * @worker: self |
d302f017 TH |
835 | * @flags: flags to clear |
836 | * | |
e22bee78 | 837 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
d302f017 | 838 | * |
cb444766 TH |
839 | * CONTEXT: |
840 | * spin_lock_irq(gcwq->lock) | |
d302f017 TH |
841 | */ |
842 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) | |
843 | { | |
63d95a91 | 844 | struct worker_pool *pool = worker->pool; |
e22bee78 TH |
845 | unsigned int oflags = worker->flags; |
846 | ||
cb444766 TH |
847 | WARN_ON_ONCE(worker->task != current); |
848 | ||
d302f017 | 849 | worker->flags &= ~flags; |
e22bee78 | 850 | |
42c025f3 TH |
851 | /* |
852 | * If transitioning out of NOT_RUNNING, increment nr_running. Note | |
853 | * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask | |
854 | * of multiple flags, not a single flag. | |
855 | */ | |
e22bee78 TH |
856 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
857 | if (!(worker->flags & WORKER_NOT_RUNNING)) | |
63d95a91 | 858 | atomic_inc(get_pool_nr_running(pool)); |
d302f017 TH |
859 | } |
860 | ||
c8e55f36 TH |
861 | /** |
862 | * busy_worker_head - return the busy hash head for a work | |
863 | * @gcwq: gcwq of interest | |
864 | * @work: work to be hashed | |
865 | * | |
866 | * Return hash head of @gcwq for @work. | |
867 | * | |
868 | * CONTEXT: | |
869 | * spin_lock_irq(gcwq->lock). | |
870 | * | |
871 | * RETURNS: | |
872 | * Pointer to the hash head. | |
873 | */ | |
874 | static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, | |
875 | struct work_struct *work) | |
876 | { | |
877 | const int base_shift = ilog2(sizeof(struct work_struct)); | |
878 | unsigned long v = (unsigned long)work; | |
879 | ||
880 | /* simple shift and fold hash, do we need something better? */ | |
881 | v >>= base_shift; | |
882 | v += v >> BUSY_WORKER_HASH_ORDER; | |
883 | v &= BUSY_WORKER_HASH_MASK; | |
884 | ||
885 | return &gcwq->busy_hash[v]; | |
886 | } | |
887 | ||
8cca0eea TH |
888 | /** |
889 | * __find_worker_executing_work - find worker which is executing a work | |
890 | * @gcwq: gcwq of interest | |
891 | * @bwh: hash head as returned by busy_worker_head() | |
892 | * @work: work to find worker for | |
893 | * | |
894 | * Find a worker which is executing @work on @gcwq. @bwh should be | |
895 | * the hash head obtained by calling busy_worker_head() with the same | |
896 | * work. | |
897 | * | |
898 | * CONTEXT: | |
899 | * spin_lock_irq(gcwq->lock). | |
900 | * | |
901 | * RETURNS: | |
902 | * Pointer to worker which is executing @work if found, NULL | |
903 | * otherwise. | |
904 | */ | |
905 | static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, | |
906 | struct hlist_head *bwh, | |
907 | struct work_struct *work) | |
908 | { | |
909 | struct worker *worker; | |
910 | struct hlist_node *tmp; | |
911 | ||
912 | hlist_for_each_entry(worker, tmp, bwh, hentry) | |
913 | if (worker->current_work == work) | |
914 | return worker; | |
915 | return NULL; | |
916 | } | |
917 | ||
918 | /** | |
919 | * find_worker_executing_work - find worker which is executing a work | |
920 | * @gcwq: gcwq of interest | |
921 | * @work: work to find worker for | |
922 | * | |
923 | * Find a worker which is executing @work on @gcwq. This function is | |
924 | * identical to __find_worker_executing_work() except that this | |
925 | * function calculates @bwh itself. | |
926 | * | |
927 | * CONTEXT: | |
928 | * spin_lock_irq(gcwq->lock). | |
929 | * | |
930 | * RETURNS: | |
931 | * Pointer to worker which is executing @work if found, NULL | |
932 | * otherwise. | |
4d707b9f | 933 | */ |
8cca0eea TH |
934 | static struct worker *find_worker_executing_work(struct global_cwq *gcwq, |
935 | struct work_struct *work) | |
4d707b9f | 936 | { |
8cca0eea TH |
937 | return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), |
938 | work); | |
4d707b9f ON |
939 | } |
940 | ||
bf4ede01 TH |
941 | /** |
942 | * move_linked_works - move linked works to a list | |
943 | * @work: start of series of works to be scheduled | |
944 | * @head: target list to append @work to | |
945 | * @nextp: out paramter for nested worklist walking | |
946 | * | |
947 | * Schedule linked works starting from @work to @head. Work series to | |
948 | * be scheduled starts at @work and includes any consecutive work with | |
949 | * WORK_STRUCT_LINKED set in its predecessor. | |
950 | * | |
951 | * If @nextp is not NULL, it's updated to point to the next work of | |
952 | * the last scheduled work. This allows move_linked_works() to be | |
953 | * nested inside outer list_for_each_entry_safe(). | |
954 | * | |
955 | * CONTEXT: | |
956 | * spin_lock_irq(gcwq->lock). | |
957 | */ | |
958 | static void move_linked_works(struct work_struct *work, struct list_head *head, | |
959 | struct work_struct **nextp) | |
960 | { | |
961 | struct work_struct *n; | |
962 | ||
963 | /* | |
964 | * Linked worklist will always end before the end of the list, | |
965 | * use NULL for list head. | |
966 | */ | |
967 | list_for_each_entry_safe_from(work, n, NULL, entry) { | |
968 | list_move_tail(&work->entry, head); | |
969 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) | |
970 | break; | |
971 | } | |
972 | ||
973 | /* | |
974 | * If we're already inside safe list traversal and have moved | |
975 | * multiple works to the scheduled queue, the next position | |
976 | * needs to be updated. | |
977 | */ | |
978 | if (nextp) | |
979 | *nextp = n; | |
980 | } | |
981 | ||
3aa62497 | 982 | static void cwq_activate_delayed_work(struct work_struct *work) |
bf4ede01 | 983 | { |
3aa62497 | 984 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
bf4ede01 TH |
985 | |
986 | trace_workqueue_activate_work(work); | |
987 | move_linked_works(work, &cwq->pool->worklist, NULL); | |
988 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); | |
989 | cwq->nr_active++; | |
990 | } | |
991 | ||
3aa62497 LJ |
992 | static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) |
993 | { | |
994 | struct work_struct *work = list_first_entry(&cwq->delayed_works, | |
995 | struct work_struct, entry); | |
996 | ||
997 | cwq_activate_delayed_work(work); | |
998 | } | |
999 | ||
bf4ede01 TH |
1000 | /** |
1001 | * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight | |
1002 | * @cwq: cwq of interest | |
1003 | * @color: color of work which left the queue | |
bf4ede01 TH |
1004 | * |
1005 | * A work either has completed or is removed from pending queue, | |
1006 | * decrement nr_in_flight of its cwq and handle workqueue flushing. | |
1007 | * | |
1008 | * CONTEXT: | |
1009 | * spin_lock_irq(gcwq->lock). | |
1010 | */ | |
b3f9f405 | 1011 | static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) |
bf4ede01 TH |
1012 | { |
1013 | /* ignore uncolored works */ | |
1014 | if (color == WORK_NO_COLOR) | |
1015 | return; | |
1016 | ||
1017 | cwq->nr_in_flight[color]--; | |
1018 | ||
b3f9f405 LJ |
1019 | cwq->nr_active--; |
1020 | if (!list_empty(&cwq->delayed_works)) { | |
1021 | /* one down, submit a delayed one */ | |
1022 | if (cwq->nr_active < cwq->max_active) | |
1023 | cwq_activate_first_delayed(cwq); | |
bf4ede01 TH |
1024 | } |
1025 | ||
1026 | /* is flush in progress and are we at the flushing tip? */ | |
1027 | if (likely(cwq->flush_color != color)) | |
1028 | return; | |
1029 | ||
1030 | /* are there still in-flight works? */ | |
1031 | if (cwq->nr_in_flight[color]) | |
1032 | return; | |
1033 | ||
1034 | /* this cwq is done, clear flush_color */ | |
1035 | cwq->flush_color = -1; | |
1036 | ||
1037 | /* | |
1038 | * If this was the last cwq, wake up the first flusher. It | |
1039 | * will handle the rest. | |
1040 | */ | |
1041 | if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) | |
1042 | complete(&cwq->wq->first_flusher->done); | |
1043 | } | |
1044 | ||
36e227d2 | 1045 | /** |
bbb68dfa | 1046 | * try_to_grab_pending - steal work item from worklist and disable irq |
36e227d2 TH |
1047 | * @work: work item to steal |
1048 | * @is_dwork: @work is a delayed_work | |
bbb68dfa | 1049 | * @flags: place to store irq state |
36e227d2 TH |
1050 | * |
1051 | * Try to grab PENDING bit of @work. This function can handle @work in any | |
1052 | * stable state - idle, on timer or on worklist. Return values are | |
1053 | * | |
1054 | * 1 if @work was pending and we successfully stole PENDING | |
1055 | * 0 if @work was idle and we claimed PENDING | |
1056 | * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry | |
bbb68dfa TH |
1057 | * -ENOENT if someone else is canceling @work, this state may persist |
1058 | * for arbitrarily long | |
36e227d2 | 1059 | * |
bbb68dfa | 1060 | * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting |
e0aecdd8 TH |
1061 | * interrupted while holding PENDING and @work off queue, irq must be |
1062 | * disabled on entry. This, combined with delayed_work->timer being | |
1063 | * irqsafe, ensures that we return -EAGAIN for finite short period of time. | |
bbb68dfa TH |
1064 | * |
1065 | * On successful return, >= 0, irq is disabled and the caller is | |
1066 | * responsible for releasing it using local_irq_restore(*@flags). | |
1067 | * | |
e0aecdd8 | 1068 | * This function is safe to call from any context including IRQ handler. |
bf4ede01 | 1069 | */ |
bbb68dfa TH |
1070 | static int try_to_grab_pending(struct work_struct *work, bool is_dwork, |
1071 | unsigned long *flags) | |
bf4ede01 TH |
1072 | { |
1073 | struct global_cwq *gcwq; | |
bf4ede01 | 1074 | |
bbb68dfa TH |
1075 | local_irq_save(*flags); |
1076 | ||
36e227d2 TH |
1077 | /* try to steal the timer if it exists */ |
1078 | if (is_dwork) { | |
1079 | struct delayed_work *dwork = to_delayed_work(work); | |
1080 | ||
e0aecdd8 TH |
1081 | /* |
1082 | * dwork->timer is irqsafe. If del_timer() fails, it's | |
1083 | * guaranteed that the timer is not queued anywhere and not | |
1084 | * running on the local CPU. | |
1085 | */ | |
36e227d2 TH |
1086 | if (likely(del_timer(&dwork->timer))) |
1087 | return 1; | |
1088 | } | |
1089 | ||
1090 | /* try to claim PENDING the normal way */ | |
bf4ede01 TH |
1091 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1092 | return 0; | |
1093 | ||
1094 | /* | |
1095 | * The queueing is in progress, or it is already queued. Try to | |
1096 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. | |
1097 | */ | |
1098 | gcwq = get_work_gcwq(work); | |
1099 | if (!gcwq) | |
bbb68dfa | 1100 | goto fail; |
bf4ede01 | 1101 | |
bbb68dfa | 1102 | spin_lock(&gcwq->lock); |
bf4ede01 TH |
1103 | if (!list_empty(&work->entry)) { |
1104 | /* | |
1105 | * This work is queued, but perhaps we locked the wrong gcwq. | |
1106 | * In that case we must see the new value after rmb(), see | |
1107 | * insert_work()->wmb(). | |
1108 | */ | |
1109 | smp_rmb(); | |
1110 | if (gcwq == get_work_gcwq(work)) { | |
1111 | debug_work_deactivate(work); | |
3aa62497 LJ |
1112 | |
1113 | /* | |
1114 | * A delayed work item cannot be grabbed directly | |
1115 | * because it might have linked NO_COLOR work items | |
1116 | * which, if left on the delayed_list, will confuse | |
1117 | * cwq->nr_active management later on and cause | |
1118 | * stall. Make sure the work item is activated | |
1119 | * before grabbing. | |
1120 | */ | |
1121 | if (*work_data_bits(work) & WORK_STRUCT_DELAYED) | |
1122 | cwq_activate_delayed_work(work); | |
1123 | ||
bf4ede01 TH |
1124 | list_del_init(&work->entry); |
1125 | cwq_dec_nr_in_flight(get_work_cwq(work), | |
b3f9f405 | 1126 | get_work_color(work)); |
36e227d2 | 1127 | |
bbb68dfa | 1128 | spin_unlock(&gcwq->lock); |
36e227d2 | 1129 | return 1; |
bf4ede01 TH |
1130 | } |
1131 | } | |
bbb68dfa TH |
1132 | spin_unlock(&gcwq->lock); |
1133 | fail: | |
1134 | local_irq_restore(*flags); | |
1135 | if (work_is_canceling(work)) | |
1136 | return -ENOENT; | |
1137 | cpu_relax(); | |
36e227d2 | 1138 | return -EAGAIN; |
bf4ede01 TH |
1139 | } |
1140 | ||
4690c4ab | 1141 | /** |
7e11629d | 1142 | * insert_work - insert a work into gcwq |
4690c4ab TH |
1143 | * @cwq: cwq @work belongs to |
1144 | * @work: work to insert | |
1145 | * @head: insertion point | |
1146 | * @extra_flags: extra WORK_STRUCT_* flags to set | |
1147 | * | |
7e11629d TH |
1148 | * Insert @work which belongs to @cwq into @gcwq after @head. |
1149 | * @extra_flags is or'd to work_struct flags. | |
4690c4ab TH |
1150 | * |
1151 | * CONTEXT: | |
8b03ae3c | 1152 | * spin_lock_irq(gcwq->lock). |
4690c4ab | 1153 | */ |
b89deed3 | 1154 | static void insert_work(struct cpu_workqueue_struct *cwq, |
4690c4ab TH |
1155 | struct work_struct *work, struct list_head *head, |
1156 | unsigned int extra_flags) | |
b89deed3 | 1157 | { |
63d95a91 | 1158 | struct worker_pool *pool = cwq->pool; |
e22bee78 | 1159 | |
4690c4ab | 1160 | /* we own @work, set data and link */ |
7a22ad75 | 1161 | set_work_cwq(work, cwq, extra_flags); |
e1d8aa9f | 1162 | |
6e84d644 ON |
1163 | /* |
1164 | * Ensure that we get the right work->data if we see the | |
1165 | * result of list_add() below, see try_to_grab_pending(). | |
1166 | */ | |
1167 | smp_wmb(); | |
4690c4ab | 1168 | |
1a4d9b0a | 1169 | list_add_tail(&work->entry, head); |
e22bee78 TH |
1170 | |
1171 | /* | |
1172 | * Ensure either worker_sched_deactivated() sees the above | |
1173 | * list_add_tail() or we see zero nr_running to avoid workers | |
1174 | * lying around lazily while there are works to be processed. | |
1175 | */ | |
1176 | smp_mb(); | |
1177 | ||
63d95a91 TH |
1178 | if (__need_more_worker(pool)) |
1179 | wake_up_worker(pool); | |
b89deed3 ON |
1180 | } |
1181 | ||
c8efcc25 TH |
1182 | /* |
1183 | * Test whether @work is being queued from another work executing on the | |
1184 | * same workqueue. This is rather expensive and should only be used from | |
1185 | * cold paths. | |
1186 | */ | |
1187 | static bool is_chained_work(struct workqueue_struct *wq) | |
1188 | { | |
1189 | unsigned long flags; | |
1190 | unsigned int cpu; | |
1191 | ||
1192 | for_each_gcwq_cpu(cpu) { | |
1193 | struct global_cwq *gcwq = get_gcwq(cpu); | |
1194 | struct worker *worker; | |
1195 | struct hlist_node *pos; | |
1196 | int i; | |
1197 | ||
1198 | spin_lock_irqsave(&gcwq->lock, flags); | |
1199 | for_each_busy_worker(worker, i, pos, gcwq) { | |
1200 | if (worker->task != current) | |
1201 | continue; | |
1202 | spin_unlock_irqrestore(&gcwq->lock, flags); | |
1203 | /* | |
1204 | * I'm @worker, no locking necessary. See if @work | |
1205 | * is headed to the same workqueue. | |
1206 | */ | |
1207 | return worker->current_cwq->wq == wq; | |
1208 | } | |
1209 | spin_unlock_irqrestore(&gcwq->lock, flags); | |
1210 | } | |
1211 | return false; | |
1212 | } | |
1213 | ||
4690c4ab | 1214 | static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
1da177e4 LT |
1215 | struct work_struct *work) |
1216 | { | |
502ca9d8 TH |
1217 | struct global_cwq *gcwq; |
1218 | struct cpu_workqueue_struct *cwq; | |
1e19ffc6 | 1219 | struct list_head *worklist; |
8a2e8e5d | 1220 | unsigned int work_flags; |
b75cac93 | 1221 | unsigned int req_cpu = cpu; |
8930caba TH |
1222 | |
1223 | /* | |
1224 | * While a work item is PENDING && off queue, a task trying to | |
1225 | * steal the PENDING will busy-loop waiting for it to either get | |
1226 | * queued or lose PENDING. Grabbing PENDING and queueing should | |
1227 | * happen with IRQ disabled. | |
1228 | */ | |
1229 | WARN_ON_ONCE(!irqs_disabled()); | |
1da177e4 | 1230 | |
dc186ad7 | 1231 | debug_work_activate(work); |
1e19ffc6 | 1232 | |
c8efcc25 | 1233 | /* if dying, only works from the same workqueue are allowed */ |
9c5a2ba7 | 1234 | if (unlikely(wq->flags & WQ_DRAINING) && |
c8efcc25 | 1235 | WARN_ON_ONCE(!is_chained_work(wq))) |
e41e704b TH |
1236 | return; |
1237 | ||
c7fc77f7 TH |
1238 | /* determine gcwq to use */ |
1239 | if (!(wq->flags & WQ_UNBOUND)) { | |
18aa9eff TH |
1240 | struct global_cwq *last_gcwq; |
1241 | ||
57469821 | 1242 | if (cpu == WORK_CPU_UNBOUND) |
c7fc77f7 TH |
1243 | cpu = raw_smp_processor_id(); |
1244 | ||
18aa9eff | 1245 | /* |
dbf2576e TH |
1246 | * It's multi cpu. If @work was previously on a different |
1247 | * cpu, it might still be running there, in which case the | |
1248 | * work needs to be queued on that cpu to guarantee | |
1249 | * non-reentrancy. | |
18aa9eff | 1250 | */ |
502ca9d8 | 1251 | gcwq = get_gcwq(cpu); |
dbf2576e TH |
1252 | last_gcwq = get_work_gcwq(work); |
1253 | ||
1254 | if (last_gcwq && last_gcwq != gcwq) { | |
18aa9eff TH |
1255 | struct worker *worker; |
1256 | ||
8930caba | 1257 | spin_lock(&last_gcwq->lock); |
18aa9eff TH |
1258 | |
1259 | worker = find_worker_executing_work(last_gcwq, work); | |
1260 | ||
1261 | if (worker && worker->current_cwq->wq == wq) | |
1262 | gcwq = last_gcwq; | |
1263 | else { | |
1264 | /* meh... not running there, queue here */ | |
8930caba TH |
1265 | spin_unlock(&last_gcwq->lock); |
1266 | spin_lock(&gcwq->lock); | |
18aa9eff | 1267 | } |
8930caba TH |
1268 | } else { |
1269 | spin_lock(&gcwq->lock); | |
1270 | } | |
f3421797 TH |
1271 | } else { |
1272 | gcwq = get_gcwq(WORK_CPU_UNBOUND); | |
8930caba | 1273 | spin_lock(&gcwq->lock); |
502ca9d8 TH |
1274 | } |
1275 | ||
1276 | /* gcwq determined, get cwq and queue */ | |
1277 | cwq = get_cwq(gcwq->cpu, wq); | |
b75cac93 | 1278 | trace_workqueue_queue_work(req_cpu, cwq, work); |
502ca9d8 | 1279 | |
f5b2552b | 1280 | if (WARN_ON(!list_empty(&work->entry))) { |
8930caba | 1281 | spin_unlock(&gcwq->lock); |
f5b2552b DC |
1282 | return; |
1283 | } | |
1e19ffc6 | 1284 | |
73f53c4a | 1285 | cwq->nr_in_flight[cwq->work_color]++; |
8a2e8e5d | 1286 | work_flags = work_color_to_flags(cwq->work_color); |
1e19ffc6 TH |
1287 | |
1288 | if (likely(cwq->nr_active < cwq->max_active)) { | |
cdadf009 | 1289 | trace_workqueue_activate_work(work); |
1e19ffc6 | 1290 | cwq->nr_active++; |
3270476a | 1291 | worklist = &cwq->pool->worklist; |
8a2e8e5d TH |
1292 | } else { |
1293 | work_flags |= WORK_STRUCT_DELAYED; | |
1e19ffc6 | 1294 | worklist = &cwq->delayed_works; |
8a2e8e5d | 1295 | } |
1e19ffc6 | 1296 | |
8a2e8e5d | 1297 | insert_work(cwq, work, worklist, work_flags); |
1e19ffc6 | 1298 | |
8930caba | 1299 | spin_unlock(&gcwq->lock); |
1da177e4 LT |
1300 | } |
1301 | ||
0fcb78c2 | 1302 | /** |
c1a220e7 ZR |
1303 | * queue_work_on - queue work on specific cpu |
1304 | * @cpu: CPU number to execute work on | |
0fcb78c2 REB |
1305 | * @wq: workqueue to use |
1306 | * @work: work to queue | |
1307 | * | |
d4283e93 | 1308 | * Returns %false if @work was already on a queue, %true otherwise. |
1da177e4 | 1309 | * |
c1a220e7 ZR |
1310 | * We queue the work to a specific CPU, the caller must ensure it |
1311 | * can't go away. | |
1da177e4 | 1312 | */ |
d4283e93 TH |
1313 | bool queue_work_on(int cpu, struct workqueue_struct *wq, |
1314 | struct work_struct *work) | |
1da177e4 | 1315 | { |
d4283e93 | 1316 | bool ret = false; |
8930caba | 1317 | unsigned long flags; |
ef1ca236 | 1318 | |
8930caba | 1319 | local_irq_save(flags); |
c1a220e7 | 1320 | |
22df02bb | 1321 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
4690c4ab | 1322 | __queue_work(cpu, wq, work); |
d4283e93 | 1323 | ret = true; |
c1a220e7 | 1324 | } |
ef1ca236 | 1325 | |
8930caba | 1326 | local_irq_restore(flags); |
1da177e4 LT |
1327 | return ret; |
1328 | } | |
c1a220e7 | 1329 | EXPORT_SYMBOL_GPL(queue_work_on); |
1da177e4 | 1330 | |
c1a220e7 | 1331 | /** |
0a13c00e | 1332 | * queue_work - queue work on a workqueue |
c1a220e7 ZR |
1333 | * @wq: workqueue to use |
1334 | * @work: work to queue | |
1335 | * | |
d4283e93 | 1336 | * Returns %false if @work was already on a queue, %true otherwise. |
c1a220e7 | 1337 | * |
0a13c00e TH |
1338 | * We queue the work to the CPU on which it was submitted, but if the CPU dies |
1339 | * it can be processed by another CPU. | |
c1a220e7 | 1340 | */ |
d4283e93 | 1341 | bool queue_work(struct workqueue_struct *wq, struct work_struct *work) |
c1a220e7 | 1342 | { |
57469821 | 1343 | return queue_work_on(WORK_CPU_UNBOUND, wq, work); |
c1a220e7 | 1344 | } |
0a13c00e | 1345 | EXPORT_SYMBOL_GPL(queue_work); |
c1a220e7 | 1346 | |
d8e794df | 1347 | void delayed_work_timer_fn(unsigned long __data) |
1da177e4 | 1348 | { |
52bad64d | 1349 | struct delayed_work *dwork = (struct delayed_work *)__data; |
7a22ad75 | 1350 | struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); |
1da177e4 | 1351 | |
e0aecdd8 | 1352 | /* should have been called from irqsafe timer with irq already off */ |
1265057f | 1353 | __queue_work(dwork->cpu, cwq->wq, &dwork->work); |
1da177e4 | 1354 | } |
d8e794df | 1355 | EXPORT_SYMBOL_GPL(delayed_work_timer_fn); |
1da177e4 | 1356 | |
7beb2edf TH |
1357 | static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, |
1358 | struct delayed_work *dwork, unsigned long delay) | |
1da177e4 | 1359 | { |
7beb2edf TH |
1360 | struct timer_list *timer = &dwork->timer; |
1361 | struct work_struct *work = &dwork->work; | |
1362 | unsigned int lcpu; | |
1363 | ||
1364 | WARN_ON_ONCE(timer->function != delayed_work_timer_fn || | |
1365 | timer->data != (unsigned long)dwork); | |
fc4b514f TH |
1366 | WARN_ON_ONCE(timer_pending(timer)); |
1367 | WARN_ON_ONCE(!list_empty(&work->entry)); | |
7beb2edf | 1368 | |
8852aac2 TH |
1369 | /* |
1370 | * If @delay is 0, queue @dwork->work immediately. This is for | |
1371 | * both optimization and correctness. The earliest @timer can | |
1372 | * expire is on the closest next tick and delayed_work users depend | |
1373 | * on that there's no such delay when @delay is 0. | |
1374 | */ | |
1375 | if (!delay) { | |
1376 | __queue_work(cpu, wq, &dwork->work); | |
1377 | return; | |
1378 | } | |
1379 | ||
7beb2edf | 1380 | timer_stats_timer_set_start_info(&dwork->timer); |
1da177e4 | 1381 | |
7beb2edf TH |
1382 | /* |
1383 | * This stores cwq for the moment, for the timer_fn. Note that the | |
1384 | * work's gcwq is preserved to allow reentrance detection for | |
1385 | * delayed works. | |
1386 | */ | |
1387 | if (!(wq->flags & WQ_UNBOUND)) { | |
1388 | struct global_cwq *gcwq = get_work_gcwq(work); | |
1389 | ||
e42986de JK |
1390 | /* |
1391 | * If we cannot get the last gcwq from @work directly, | |
1392 | * select the last CPU such that it avoids unnecessarily | |
1393 | * triggering non-reentrancy check in __queue_work(). | |
1394 | */ | |
1395 | lcpu = cpu; | |
1396 | if (gcwq) | |
7beb2edf | 1397 | lcpu = gcwq->cpu; |
e42986de | 1398 | if (lcpu == WORK_CPU_UNBOUND) |
7beb2edf TH |
1399 | lcpu = raw_smp_processor_id(); |
1400 | } else { | |
1401 | lcpu = WORK_CPU_UNBOUND; | |
1402 | } | |
1403 | ||
1404 | set_work_cwq(work, get_cwq(lcpu, wq), 0); | |
1405 | ||
1265057f | 1406 | dwork->cpu = cpu; |
7beb2edf TH |
1407 | timer->expires = jiffies + delay; |
1408 | ||
1409 | if (unlikely(cpu != WORK_CPU_UNBOUND)) | |
1410 | add_timer_on(timer, cpu); | |
1411 | else | |
1412 | add_timer(timer); | |
1da177e4 LT |
1413 | } |
1414 | ||
0fcb78c2 REB |
1415 | /** |
1416 | * queue_delayed_work_on - queue work on specific CPU after delay | |
1417 | * @cpu: CPU number to execute work on | |
1418 | * @wq: workqueue to use | |
af9997e4 | 1419 | * @dwork: work to queue |
0fcb78c2 REB |
1420 | * @delay: number of jiffies to wait before queueing |
1421 | * | |
715f1300 TH |
1422 | * Returns %false if @work was already on a queue, %true otherwise. If |
1423 | * @delay is zero and @dwork is idle, it will be scheduled for immediate | |
1424 | * execution. | |
0fcb78c2 | 1425 | */ |
d4283e93 TH |
1426 | bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1427 | struct delayed_work *dwork, unsigned long delay) | |
7a6bc1cd | 1428 | { |
52bad64d | 1429 | struct work_struct *work = &dwork->work; |
d4283e93 | 1430 | bool ret = false; |
8930caba | 1431 | unsigned long flags; |
7a6bc1cd | 1432 | |
8930caba TH |
1433 | /* read the comment in __queue_work() */ |
1434 | local_irq_save(flags); | |
7a6bc1cd | 1435 | |
22df02bb | 1436 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
7beb2edf | 1437 | __queue_delayed_work(cpu, wq, dwork, delay); |
d4283e93 | 1438 | ret = true; |
7a6bc1cd | 1439 | } |
8a3e77cc | 1440 | |
8930caba | 1441 | local_irq_restore(flags); |
7a6bc1cd VP |
1442 | return ret; |
1443 | } | |
ae90dd5d | 1444 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
c7fc77f7 | 1445 | |
0a13c00e TH |
1446 | /** |
1447 | * queue_delayed_work - queue work on a workqueue after delay | |
1448 | * @wq: workqueue to use | |
1449 | * @dwork: delayable work to queue | |
1450 | * @delay: number of jiffies to wait before queueing | |
1451 | * | |
715f1300 | 1452 | * Equivalent to queue_delayed_work_on() but tries to use the local CPU. |
0a13c00e | 1453 | */ |
d4283e93 | 1454 | bool queue_delayed_work(struct workqueue_struct *wq, |
0a13c00e TH |
1455 | struct delayed_work *dwork, unsigned long delay) |
1456 | { | |
57469821 | 1457 | return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); |
0a13c00e TH |
1458 | } |
1459 | EXPORT_SYMBOL_GPL(queue_delayed_work); | |
c7fc77f7 | 1460 | |
8376fe22 TH |
1461 | /** |
1462 | * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU | |
1463 | * @cpu: CPU number to execute work on | |
1464 | * @wq: workqueue to use | |
1465 | * @dwork: work to queue | |
1466 | * @delay: number of jiffies to wait before queueing | |
1467 | * | |
1468 | * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, | |
1469 | * modify @dwork's timer so that it expires after @delay. If @delay is | |
1470 | * zero, @work is guaranteed to be scheduled immediately regardless of its | |
1471 | * current state. | |
1472 | * | |
1473 | * Returns %false if @dwork was idle and queued, %true if @dwork was | |
1474 | * pending and its timer was modified. | |
1475 | * | |
e0aecdd8 | 1476 | * This function is safe to call from any context including IRQ handler. |
8376fe22 TH |
1477 | * See try_to_grab_pending() for details. |
1478 | */ | |
1479 | bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, | |
1480 | struct delayed_work *dwork, unsigned long delay) | |
1481 | { | |
1482 | unsigned long flags; | |
1483 | int ret; | |
c7fc77f7 | 1484 | |
8376fe22 TH |
1485 | do { |
1486 | ret = try_to_grab_pending(&dwork->work, true, &flags); | |
1487 | } while (unlikely(ret == -EAGAIN)); | |
63bc0362 | 1488 | |
8376fe22 TH |
1489 | if (likely(ret >= 0)) { |
1490 | __queue_delayed_work(cpu, wq, dwork, delay); | |
1491 | local_irq_restore(flags); | |
7a6bc1cd | 1492 | } |
8376fe22 TH |
1493 | |
1494 | /* -ENOENT from try_to_grab_pending() becomes %true */ | |
7a6bc1cd VP |
1495 | return ret; |
1496 | } | |
8376fe22 TH |
1497 | EXPORT_SYMBOL_GPL(mod_delayed_work_on); |
1498 | ||
1499 | /** | |
1500 | * mod_delayed_work - modify delay of or queue a delayed work | |
1501 | * @wq: workqueue to use | |
1502 | * @dwork: work to queue | |
1503 | * @delay: number of jiffies to wait before queueing | |
1504 | * | |
1505 | * mod_delayed_work_on() on local CPU. | |
1506 | */ | |
1507 | bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork, | |
1508 | unsigned long delay) | |
1509 | { | |
1510 | return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); | |
1511 | } | |
1512 | EXPORT_SYMBOL_GPL(mod_delayed_work); | |
1da177e4 | 1513 | |
c8e55f36 TH |
1514 | /** |
1515 | * worker_enter_idle - enter idle state | |
1516 | * @worker: worker which is entering idle state | |
1517 | * | |
1518 | * @worker is entering idle state. Update stats and idle timer if | |
1519 | * necessary. | |
1520 | * | |
1521 | * LOCKING: | |
1522 | * spin_lock_irq(gcwq->lock). | |
1523 | */ | |
1524 | static void worker_enter_idle(struct worker *worker) | |
1da177e4 | 1525 | { |
bd7bdd43 TH |
1526 | struct worker_pool *pool = worker->pool; |
1527 | struct global_cwq *gcwq = pool->gcwq; | |
c8e55f36 TH |
1528 | |
1529 | BUG_ON(worker->flags & WORKER_IDLE); | |
1530 | BUG_ON(!list_empty(&worker->entry) && | |
1531 | (worker->hentry.next || worker->hentry.pprev)); | |
1532 | ||
cb444766 TH |
1533 | /* can't use worker_set_flags(), also called from start_worker() */ |
1534 | worker->flags |= WORKER_IDLE; | |
bd7bdd43 | 1535 | pool->nr_idle++; |
e22bee78 | 1536 | worker->last_active = jiffies; |
c8e55f36 TH |
1537 | |
1538 | /* idle_list is LIFO */ | |
bd7bdd43 | 1539 | list_add(&worker->entry, &pool->idle_list); |
db7bccf4 | 1540 | |
628c78e7 TH |
1541 | if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) |
1542 | mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); | |
cb444766 | 1543 | |
544ecf31 | 1544 | /* |
628c78e7 TH |
1545 | * Sanity check nr_running. Because gcwq_unbind_fn() releases |
1546 | * gcwq->lock between setting %WORKER_UNBOUND and zapping | |
1547 | * nr_running, the warning may trigger spuriously. Check iff | |
1548 | * unbind is not in progress. | |
544ecf31 | 1549 | */ |
628c78e7 | 1550 | WARN_ON_ONCE(!(gcwq->flags & GCWQ_DISASSOCIATED) && |
bd7bdd43 | 1551 | pool->nr_workers == pool->nr_idle && |
63d95a91 | 1552 | atomic_read(get_pool_nr_running(pool))); |
c8e55f36 TH |
1553 | } |
1554 | ||
1555 | /** | |
1556 | * worker_leave_idle - leave idle state | |
1557 | * @worker: worker which is leaving idle state | |
1558 | * | |
1559 | * @worker is leaving idle state. Update stats. | |
1560 | * | |
1561 | * LOCKING: | |
1562 | * spin_lock_irq(gcwq->lock). | |
1563 | */ | |
1564 | static void worker_leave_idle(struct worker *worker) | |
1565 | { | |
bd7bdd43 | 1566 | struct worker_pool *pool = worker->pool; |
c8e55f36 TH |
1567 | |
1568 | BUG_ON(!(worker->flags & WORKER_IDLE)); | |
d302f017 | 1569 | worker_clr_flags(worker, WORKER_IDLE); |
bd7bdd43 | 1570 | pool->nr_idle--; |
c8e55f36 TH |
1571 | list_del_init(&worker->entry); |
1572 | } | |
1573 | ||
e22bee78 TH |
1574 | /** |
1575 | * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq | |
1576 | * @worker: self | |
1577 | * | |
1578 | * Works which are scheduled while the cpu is online must at least be | |
1579 | * scheduled to a worker which is bound to the cpu so that if they are | |
1580 | * flushed from cpu callbacks while cpu is going down, they are | |
1581 | * guaranteed to execute on the cpu. | |
1582 | * | |
1583 | * This function is to be used by rogue workers and rescuers to bind | |
1584 | * themselves to the target cpu and may race with cpu going down or | |
1585 | * coming online. kthread_bind() can't be used because it may put the | |
1586 | * worker to already dead cpu and set_cpus_allowed_ptr() can't be used | |
1587 | * verbatim as it's best effort and blocking and gcwq may be | |
1588 | * [dis]associated in the meantime. | |
1589 | * | |
f2d5a0ee TH |
1590 | * This function tries set_cpus_allowed() and locks gcwq and verifies the |
1591 | * binding against %GCWQ_DISASSOCIATED which is set during | |
1592 | * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker | |
1593 | * enters idle state or fetches works without dropping lock, it can | |
1594 | * guarantee the scheduling requirement described in the first paragraph. | |
e22bee78 TH |
1595 | * |
1596 | * CONTEXT: | |
1597 | * Might sleep. Called without any lock but returns with gcwq->lock | |
1598 | * held. | |
1599 | * | |
1600 | * RETURNS: | |
1601 | * %true if the associated gcwq is online (@worker is successfully | |
1602 | * bound), %false if offline. | |
1603 | */ | |
1604 | static bool worker_maybe_bind_and_lock(struct worker *worker) | |
972fa1c5 | 1605 | __acquires(&gcwq->lock) |
e22bee78 | 1606 | { |
bd7bdd43 | 1607 | struct global_cwq *gcwq = worker->pool->gcwq; |
e22bee78 TH |
1608 | struct task_struct *task = worker->task; |
1609 | ||
1610 | while (true) { | |
4e6045f1 | 1611 | /* |
e22bee78 TH |
1612 | * The following call may fail, succeed or succeed |
1613 | * without actually migrating the task to the cpu if | |
1614 | * it races with cpu hotunplug operation. Verify | |
1615 | * against GCWQ_DISASSOCIATED. | |
4e6045f1 | 1616 | */ |
f3421797 TH |
1617 | if (!(gcwq->flags & GCWQ_DISASSOCIATED)) |
1618 | set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); | |
e22bee78 TH |
1619 | |
1620 | spin_lock_irq(&gcwq->lock); | |
1621 | if (gcwq->flags & GCWQ_DISASSOCIATED) | |
1622 | return false; | |
1623 | if (task_cpu(task) == gcwq->cpu && | |
1624 | cpumask_equal(¤t->cpus_allowed, | |
1625 | get_cpu_mask(gcwq->cpu))) | |
1626 | return true; | |
1627 | spin_unlock_irq(&gcwq->lock); | |
1628 | ||
5035b20f TH |
1629 | /* |
1630 | * We've raced with CPU hot[un]plug. Give it a breather | |
1631 | * and retry migration. cond_resched() is required here; | |
1632 | * otherwise, we might deadlock against cpu_stop trying to | |
1633 | * bring down the CPU on non-preemptive kernel. | |
1634 | */ | |
e22bee78 | 1635 | cpu_relax(); |
5035b20f | 1636 | cond_resched(); |
e22bee78 TH |
1637 | } |
1638 | } | |
1639 | ||
25511a47 | 1640 | /* |
ea1abd61 | 1641 | * Rebind an idle @worker to its CPU. worker_thread() will test |
5f7dabfd | 1642 | * list_empty(@worker->entry) before leaving idle and call this function. |
25511a47 TH |
1643 | */ |
1644 | static void idle_worker_rebind(struct worker *worker) | |
1645 | { | |
1646 | struct global_cwq *gcwq = worker->pool->gcwq; | |
1647 | ||
5f7dabfd LJ |
1648 | /* CPU may go down again inbetween, clear UNBOUND only on success */ |
1649 | if (worker_maybe_bind_and_lock(worker)) | |
1650 | worker_clr_flags(worker, WORKER_UNBOUND); | |
25511a47 | 1651 | |
ea1abd61 LJ |
1652 | /* rebind complete, become available again */ |
1653 | list_add(&worker->entry, &worker->pool->idle_list); | |
1654 | spin_unlock_irq(&gcwq->lock); | |
25511a47 TH |
1655 | } |
1656 | ||
e22bee78 | 1657 | /* |
25511a47 | 1658 | * Function for @worker->rebind.work used to rebind unbound busy workers to |
403c821d TH |
1659 | * the associated cpu which is coming back online. This is scheduled by |
1660 | * cpu up but can race with other cpu hotplug operations and may be | |
1661 | * executed twice without intervening cpu down. | |
e22bee78 | 1662 | */ |
25511a47 | 1663 | static void busy_worker_rebind_fn(struct work_struct *work) |
e22bee78 TH |
1664 | { |
1665 | struct worker *worker = container_of(work, struct worker, rebind_work); | |
bd7bdd43 | 1666 | struct global_cwq *gcwq = worker->pool->gcwq; |
e22bee78 | 1667 | |
eab6d828 LJ |
1668 | if (worker_maybe_bind_and_lock(worker)) |
1669 | worker_clr_flags(worker, WORKER_UNBOUND); | |
e22bee78 TH |
1670 | |
1671 | spin_unlock_irq(&gcwq->lock); | |
1672 | } | |
1673 | ||
25511a47 TH |
1674 | /** |
1675 | * rebind_workers - rebind all workers of a gcwq to the associated CPU | |
1676 | * @gcwq: gcwq of interest | |
1677 | * | |
1678 | * @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding | |
1679 | * is different for idle and busy ones. | |
1680 | * | |
ea1abd61 LJ |
1681 | * Idle ones will be removed from the idle_list and woken up. They will |
1682 | * add themselves back after completing rebind. This ensures that the | |
1683 | * idle_list doesn't contain any unbound workers when re-bound busy workers | |
1684 | * try to perform local wake-ups for concurrency management. | |
25511a47 | 1685 | * |
ea1abd61 LJ |
1686 | * Busy workers can rebind after they finish their current work items. |
1687 | * Queueing the rebind work item at the head of the scheduled list is | |
1688 | * enough. Note that nr_running will be properly bumped as busy workers | |
1689 | * rebind. | |
25511a47 | 1690 | * |
ea1abd61 LJ |
1691 | * On return, all non-manager workers are scheduled for rebind - see |
1692 | * manage_workers() for the manager special case. Any idle worker | |
1693 | * including the manager will not appear on @idle_list until rebind is | |
1694 | * complete, making local wake-ups safe. | |
25511a47 TH |
1695 | */ |
1696 | static void rebind_workers(struct global_cwq *gcwq) | |
25511a47 | 1697 | { |
25511a47 | 1698 | struct worker_pool *pool; |
ea1abd61 | 1699 | struct worker *worker, *n; |
25511a47 TH |
1700 | struct hlist_node *pos; |
1701 | int i; | |
1702 | ||
1703 | lockdep_assert_held(&gcwq->lock); | |
1704 | ||
1705 | for_each_worker_pool(pool, gcwq) | |
b2eb83d1 | 1706 | lockdep_assert_held(&pool->assoc_mutex); |
25511a47 | 1707 | |
5f7dabfd | 1708 | /* dequeue and kick idle ones */ |
25511a47 | 1709 | for_each_worker_pool(pool, gcwq) { |
ea1abd61 | 1710 | list_for_each_entry_safe(worker, n, &pool->idle_list, entry) { |
ea1abd61 LJ |
1711 | /* |
1712 | * idle workers should be off @pool->idle_list | |
1713 | * until rebind is complete to avoid receiving | |
1714 | * premature local wake-ups. | |
1715 | */ | |
1716 | list_del_init(&worker->entry); | |
25511a47 | 1717 | |
5f7dabfd LJ |
1718 | /* |
1719 | * worker_thread() will see the above dequeuing | |
1720 | * and call idle_worker_rebind(). | |
1721 | */ | |
25511a47 TH |
1722 | wake_up_process(worker->task); |
1723 | } | |
1724 | } | |
1725 | ||
ea1abd61 | 1726 | /* rebind busy workers */ |
25511a47 TH |
1727 | for_each_busy_worker(worker, i, pos, gcwq) { |
1728 | struct work_struct *rebind_work = &worker->rebind_work; | |
e2b6a6d5 | 1729 | struct workqueue_struct *wq; |
25511a47 TH |
1730 | |
1731 | if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, | |
1732 | work_data_bits(rebind_work))) | |
1733 | continue; | |
1734 | ||
25511a47 | 1735 | debug_work_activate(rebind_work); |
90beca5d | 1736 | |
e2b6a6d5 JK |
1737 | /* |
1738 | * wq doesn't really matter but let's keep @worker->pool | |
1739 | * and @cwq->pool consistent for sanity. | |
1740 | */ | |
1741 | if (worker_pool_pri(worker->pool)) | |
1742 | wq = system_highpri_wq; | |
1743 | else | |
1744 | wq = system_wq; | |
ec58815a | 1745 | |
e2b6a6d5 JK |
1746 | insert_work(get_cwq(gcwq->cpu, wq), rebind_work, |
1747 | worker->scheduled.next, | |
1748 | work_color_to_flags(WORK_NO_COLOR)); | |
ec58815a | 1749 | } |
25511a47 TH |
1750 | } |
1751 | ||
c34056a3 TH |
1752 | static struct worker *alloc_worker(void) |
1753 | { | |
1754 | struct worker *worker; | |
1755 | ||
1756 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
c8e55f36 TH |
1757 | if (worker) { |
1758 | INIT_LIST_HEAD(&worker->entry); | |
affee4b2 | 1759 | INIT_LIST_HEAD(&worker->scheduled); |
25511a47 | 1760 | INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn); |
e22bee78 TH |
1761 | /* on creation a worker is in !idle && prep state */ |
1762 | worker->flags = WORKER_PREP; | |
c8e55f36 | 1763 | } |
c34056a3 TH |
1764 | return worker; |
1765 | } | |
1766 | ||
1767 | /** | |
1768 | * create_worker - create a new workqueue worker | |
63d95a91 | 1769 | * @pool: pool the new worker will belong to |
c34056a3 | 1770 | * |
63d95a91 | 1771 | * Create a new worker which is bound to @pool. The returned worker |
c34056a3 TH |
1772 | * can be started by calling start_worker() or destroyed using |
1773 | * destroy_worker(). | |
1774 | * | |
1775 | * CONTEXT: | |
1776 | * Might sleep. Does GFP_KERNEL allocations. | |
1777 | * | |
1778 | * RETURNS: | |
1779 | * Pointer to the newly created worker. | |
1780 | */ | |
bc2ae0f5 | 1781 | static struct worker *create_worker(struct worker_pool *pool) |
c34056a3 | 1782 | { |
63d95a91 | 1783 | struct global_cwq *gcwq = pool->gcwq; |
3270476a | 1784 | const char *pri = worker_pool_pri(pool) ? "H" : ""; |
c34056a3 | 1785 | struct worker *worker = NULL; |
f3421797 | 1786 | int id = -1; |
c34056a3 | 1787 | |
8b03ae3c | 1788 | spin_lock_irq(&gcwq->lock); |
bd7bdd43 | 1789 | while (ida_get_new(&pool->worker_ida, &id)) { |
8b03ae3c | 1790 | spin_unlock_irq(&gcwq->lock); |
bd7bdd43 | 1791 | if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL)) |
c34056a3 | 1792 | goto fail; |
8b03ae3c | 1793 | spin_lock_irq(&gcwq->lock); |
c34056a3 | 1794 | } |
8b03ae3c | 1795 | spin_unlock_irq(&gcwq->lock); |
c34056a3 TH |
1796 | |
1797 | worker = alloc_worker(); | |
1798 | if (!worker) | |
1799 | goto fail; | |
1800 | ||
bd7bdd43 | 1801 | worker->pool = pool; |
c34056a3 TH |
1802 | worker->id = id; |
1803 | ||
bc2ae0f5 | 1804 | if (gcwq->cpu != WORK_CPU_UNBOUND) |
94dcf29a | 1805 | worker->task = kthread_create_on_node(worker_thread, |
3270476a TH |
1806 | worker, cpu_to_node(gcwq->cpu), |
1807 | "kworker/%u:%d%s", gcwq->cpu, id, pri); | |
f3421797 TH |
1808 | else |
1809 | worker->task = kthread_create(worker_thread, worker, | |
3270476a | 1810 | "kworker/u:%d%s", id, pri); |
c34056a3 TH |
1811 | if (IS_ERR(worker->task)) |
1812 | goto fail; | |
1813 | ||
3270476a TH |
1814 | if (worker_pool_pri(pool)) |
1815 | set_user_nice(worker->task, HIGHPRI_NICE_LEVEL); | |
1816 | ||
db7bccf4 | 1817 | /* |
bc2ae0f5 TH |
1818 | * Determine CPU binding of the new worker depending on |
1819 | * %GCWQ_DISASSOCIATED. The caller is responsible for ensuring the | |
1820 | * flag remains stable across this function. See the comments | |
1821 | * above the flag definition for details. | |
1822 | * | |
1823 | * As an unbound worker may later become a regular one if CPU comes | |
1824 | * online, make sure every worker has %PF_THREAD_BOUND set. | |
db7bccf4 | 1825 | */ |
bc2ae0f5 | 1826 | if (!(gcwq->flags & GCWQ_DISASSOCIATED)) { |
8b03ae3c | 1827 | kthread_bind(worker->task, gcwq->cpu); |
bc2ae0f5 | 1828 | } else { |
db7bccf4 | 1829 | worker->task->flags |= PF_THREAD_BOUND; |
bc2ae0f5 | 1830 | worker->flags |= WORKER_UNBOUND; |
f3421797 | 1831 | } |
c34056a3 TH |
1832 | |
1833 | return worker; | |
1834 | fail: | |
1835 | if (id >= 0) { | |
8b03ae3c | 1836 | spin_lock_irq(&gcwq->lock); |
bd7bdd43 | 1837 | ida_remove(&pool->worker_ida, id); |
8b03ae3c | 1838 | spin_unlock_irq(&gcwq->lock); |
c34056a3 TH |
1839 | } |
1840 | kfree(worker); | |
1841 | return NULL; | |
1842 | } | |
1843 | ||
1844 | /** | |
1845 | * start_worker - start a newly created worker | |
1846 | * @worker: worker to start | |
1847 | * | |
c8e55f36 | 1848 | * Make the gcwq aware of @worker and start it. |
c34056a3 TH |
1849 | * |
1850 | * CONTEXT: | |
8b03ae3c | 1851 | * spin_lock_irq(gcwq->lock). |
c34056a3 TH |
1852 | */ |
1853 | static void start_worker(struct worker *worker) | |
1854 | { | |
cb444766 | 1855 | worker->flags |= WORKER_STARTED; |
bd7bdd43 | 1856 | worker->pool->nr_workers++; |
c8e55f36 | 1857 | worker_enter_idle(worker); |
c34056a3 TH |
1858 | wake_up_process(worker->task); |
1859 | } | |
1860 | ||
1861 | /** | |
1862 | * destroy_worker - destroy a workqueue worker | |
1863 | * @worker: worker to be destroyed | |
1864 | * | |
c8e55f36 TH |
1865 | * Destroy @worker and adjust @gcwq stats accordingly. |
1866 | * | |
1867 | * CONTEXT: | |
1868 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. | |
c34056a3 TH |
1869 | */ |
1870 | static void destroy_worker(struct worker *worker) | |
1871 | { | |
bd7bdd43 TH |
1872 | struct worker_pool *pool = worker->pool; |
1873 | struct global_cwq *gcwq = pool->gcwq; | |
c34056a3 TH |
1874 | int id = worker->id; |
1875 | ||
1876 | /* sanity check frenzy */ | |
1877 | BUG_ON(worker->current_work); | |
affee4b2 | 1878 | BUG_ON(!list_empty(&worker->scheduled)); |
c34056a3 | 1879 | |
c8e55f36 | 1880 | if (worker->flags & WORKER_STARTED) |
bd7bdd43 | 1881 | pool->nr_workers--; |
c8e55f36 | 1882 | if (worker->flags & WORKER_IDLE) |
bd7bdd43 | 1883 | pool->nr_idle--; |
c8e55f36 TH |
1884 | |
1885 | list_del_init(&worker->entry); | |
cb444766 | 1886 | worker->flags |= WORKER_DIE; |
c8e55f36 TH |
1887 | |
1888 | spin_unlock_irq(&gcwq->lock); | |
1889 | ||
c34056a3 TH |
1890 | kthread_stop(worker->task); |
1891 | kfree(worker); | |
1892 | ||
8b03ae3c | 1893 | spin_lock_irq(&gcwq->lock); |
bd7bdd43 | 1894 | ida_remove(&pool->worker_ida, id); |
c34056a3 TH |
1895 | } |
1896 | ||
63d95a91 | 1897 | static void idle_worker_timeout(unsigned long __pool) |
e22bee78 | 1898 | { |
63d95a91 TH |
1899 | struct worker_pool *pool = (void *)__pool; |
1900 | struct global_cwq *gcwq = pool->gcwq; | |
e22bee78 TH |
1901 | |
1902 | spin_lock_irq(&gcwq->lock); | |
1903 | ||
63d95a91 | 1904 | if (too_many_workers(pool)) { |
e22bee78 TH |
1905 | struct worker *worker; |
1906 | unsigned long expires; | |
1907 | ||
1908 | /* idle_list is kept in LIFO order, check the last one */ | |
63d95a91 | 1909 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
e22bee78 TH |
1910 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1911 | ||
1912 | if (time_before(jiffies, expires)) | |
63d95a91 | 1913 | mod_timer(&pool->idle_timer, expires); |
e22bee78 TH |
1914 | else { |
1915 | /* it's been idle for too long, wake up manager */ | |
11ebea50 | 1916 | pool->flags |= POOL_MANAGE_WORKERS; |
63d95a91 | 1917 | wake_up_worker(pool); |
d5abe669 | 1918 | } |
e22bee78 TH |
1919 | } |
1920 | ||
1921 | spin_unlock_irq(&gcwq->lock); | |
1922 | } | |
d5abe669 | 1923 | |
e22bee78 TH |
1924 | static bool send_mayday(struct work_struct *work) |
1925 | { | |
1926 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); | |
1927 | struct workqueue_struct *wq = cwq->wq; | |
f3421797 | 1928 | unsigned int cpu; |
e22bee78 TH |
1929 | |
1930 | if (!(wq->flags & WQ_RESCUER)) | |
1931 | return false; | |
1932 | ||
1933 | /* mayday mayday mayday */ | |
bd7bdd43 | 1934 | cpu = cwq->pool->gcwq->cpu; |
f3421797 TH |
1935 | /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ |
1936 | if (cpu == WORK_CPU_UNBOUND) | |
1937 | cpu = 0; | |
f2e005aa | 1938 | if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) |
e22bee78 TH |
1939 | wake_up_process(wq->rescuer->task); |
1940 | return true; | |
1941 | } | |
1942 | ||
63d95a91 | 1943 | static void gcwq_mayday_timeout(unsigned long __pool) |
e22bee78 | 1944 | { |
63d95a91 TH |
1945 | struct worker_pool *pool = (void *)__pool; |
1946 | struct global_cwq *gcwq = pool->gcwq; | |
e22bee78 TH |
1947 | struct work_struct *work; |
1948 | ||
1949 | spin_lock_irq(&gcwq->lock); | |
1950 | ||
63d95a91 | 1951 | if (need_to_create_worker(pool)) { |
e22bee78 TH |
1952 | /* |
1953 | * We've been trying to create a new worker but | |
1954 | * haven't been successful. We might be hitting an | |
1955 | * allocation deadlock. Send distress signals to | |
1956 | * rescuers. | |
1957 | */ | |
63d95a91 | 1958 | list_for_each_entry(work, &pool->worklist, entry) |
e22bee78 | 1959 | send_mayday(work); |
1da177e4 | 1960 | } |
e22bee78 TH |
1961 | |
1962 | spin_unlock_irq(&gcwq->lock); | |
1963 | ||
63d95a91 | 1964 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); |
1da177e4 LT |
1965 | } |
1966 | ||
e22bee78 TH |
1967 | /** |
1968 | * maybe_create_worker - create a new worker if necessary | |
63d95a91 | 1969 | * @pool: pool to create a new worker for |
e22bee78 | 1970 | * |
63d95a91 | 1971 | * Create a new worker for @pool if necessary. @pool is guaranteed to |
e22bee78 TH |
1972 | * have at least one idle worker on return from this function. If |
1973 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is | |
63d95a91 | 1974 | * sent to all rescuers with works scheduled on @pool to resolve |
e22bee78 TH |
1975 | * possible allocation deadlock. |
1976 | * | |
1977 | * On return, need_to_create_worker() is guaranteed to be false and | |
1978 | * may_start_working() true. | |
1979 | * | |
1980 | * LOCKING: | |
1981 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
1982 | * multiple times. Does GFP_KERNEL allocations. Called only from | |
1983 | * manager. | |
1984 | * | |
1985 | * RETURNS: | |
1986 | * false if no action was taken and gcwq->lock stayed locked, true | |
1987 | * otherwise. | |
1988 | */ | |
63d95a91 | 1989 | static bool maybe_create_worker(struct worker_pool *pool) |
06bd6ebf NK |
1990 | __releases(&gcwq->lock) |
1991 | __acquires(&gcwq->lock) | |
1da177e4 | 1992 | { |
63d95a91 TH |
1993 | struct global_cwq *gcwq = pool->gcwq; |
1994 | ||
1995 | if (!need_to_create_worker(pool)) | |
e22bee78 TH |
1996 | return false; |
1997 | restart: | |
9f9c2364 TH |
1998 | spin_unlock_irq(&gcwq->lock); |
1999 | ||
e22bee78 | 2000 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
63d95a91 | 2001 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
e22bee78 TH |
2002 | |
2003 | while (true) { | |
2004 | struct worker *worker; | |
2005 | ||
bc2ae0f5 | 2006 | worker = create_worker(pool); |
e22bee78 | 2007 | if (worker) { |
63d95a91 | 2008 | del_timer_sync(&pool->mayday_timer); |
e22bee78 TH |
2009 | spin_lock_irq(&gcwq->lock); |
2010 | start_worker(worker); | |
63d95a91 | 2011 | BUG_ON(need_to_create_worker(pool)); |
e22bee78 TH |
2012 | return true; |
2013 | } | |
2014 | ||
63d95a91 | 2015 | if (!need_to_create_worker(pool)) |
e22bee78 | 2016 | break; |
1da177e4 | 2017 | |
e22bee78 TH |
2018 | __set_current_state(TASK_INTERRUPTIBLE); |
2019 | schedule_timeout(CREATE_COOLDOWN); | |
9f9c2364 | 2020 | |
63d95a91 | 2021 | if (!need_to_create_worker(pool)) |
e22bee78 TH |
2022 | break; |
2023 | } | |
2024 | ||
63d95a91 | 2025 | del_timer_sync(&pool->mayday_timer); |
e22bee78 | 2026 | spin_lock_irq(&gcwq->lock); |
63d95a91 | 2027 | if (need_to_create_worker(pool)) |
e22bee78 TH |
2028 | goto restart; |
2029 | return true; | |
2030 | } | |
2031 | ||
2032 | /** | |
2033 | * maybe_destroy_worker - destroy workers which have been idle for a while | |
63d95a91 | 2034 | * @pool: pool to destroy workers for |
e22bee78 | 2035 | * |
63d95a91 | 2036 | * Destroy @pool workers which have been idle for longer than |
e22bee78 TH |
2037 | * IDLE_WORKER_TIMEOUT. |
2038 | * | |
2039 | * LOCKING: | |
2040 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
2041 | * multiple times. Called only from manager. | |
2042 | * | |
2043 | * RETURNS: | |
2044 | * false if no action was taken and gcwq->lock stayed locked, true | |
2045 | * otherwise. | |
2046 | */ | |
63d95a91 | 2047 | static bool maybe_destroy_workers(struct worker_pool *pool) |
e22bee78 TH |
2048 | { |
2049 | bool ret = false; | |
1da177e4 | 2050 | |
63d95a91 | 2051 | while (too_many_workers(pool)) { |
e22bee78 TH |
2052 | struct worker *worker; |
2053 | unsigned long expires; | |
3af24433 | 2054 | |
63d95a91 | 2055 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
e22bee78 | 2056 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
85f4186a | 2057 | |
e22bee78 | 2058 | if (time_before(jiffies, expires)) { |
63d95a91 | 2059 | mod_timer(&pool->idle_timer, expires); |
3af24433 | 2060 | break; |
e22bee78 | 2061 | } |
1da177e4 | 2062 | |
e22bee78 TH |
2063 | destroy_worker(worker); |
2064 | ret = true; | |
1da177e4 | 2065 | } |
1e19ffc6 | 2066 | |
e22bee78 | 2067 | return ret; |
1e19ffc6 TH |
2068 | } |
2069 | ||
73f53c4a | 2070 | /** |
e22bee78 TH |
2071 | * manage_workers - manage worker pool |
2072 | * @worker: self | |
73f53c4a | 2073 | * |
e22bee78 TH |
2074 | * Assume the manager role and manage gcwq worker pool @worker belongs |
2075 | * to. At any given time, there can be only zero or one manager per | |
2076 | * gcwq. The exclusion is handled automatically by this function. | |
2077 | * | |
2078 | * The caller can safely start processing works on false return. On | |
2079 | * true return, it's guaranteed that need_to_create_worker() is false | |
2080 | * and may_start_working() is true. | |
73f53c4a TH |
2081 | * |
2082 | * CONTEXT: | |
e22bee78 TH |
2083 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
2084 | * multiple times. Does GFP_KERNEL allocations. | |
2085 | * | |
2086 | * RETURNS: | |
2087 | * false if no action was taken and gcwq->lock stayed locked, true if | |
2088 | * some action was taken. | |
73f53c4a | 2089 | */ |
e22bee78 | 2090 | static bool manage_workers(struct worker *worker) |
73f53c4a | 2091 | { |
63d95a91 | 2092 | struct worker_pool *pool = worker->pool; |
e22bee78 | 2093 | bool ret = false; |
73f53c4a | 2094 | |
ee378aa4 | 2095 | if (pool->flags & POOL_MANAGING_WORKERS) |
e22bee78 | 2096 | return ret; |
1e19ffc6 | 2097 | |
552a37e9 | 2098 | pool->flags |= POOL_MANAGING_WORKERS; |
73f53c4a | 2099 | |
ee378aa4 LJ |
2100 | /* |
2101 | * To simplify both worker management and CPU hotplug, hold off | |
2102 | * management while hotplug is in progress. CPU hotplug path can't | |
2103 | * grab %POOL_MANAGING_WORKERS to achieve this because that can | |
2104 | * lead to idle worker depletion (all become busy thinking someone | |
2105 | * else is managing) which in turn can result in deadlock under | |
b2eb83d1 | 2106 | * extreme circumstances. Use @pool->assoc_mutex to synchronize |
ee378aa4 LJ |
2107 | * manager against CPU hotplug. |
2108 | * | |
b2eb83d1 | 2109 | * assoc_mutex would always be free unless CPU hotplug is in |
ee378aa4 LJ |
2110 | * progress. trylock first without dropping @gcwq->lock. |
2111 | */ | |
b2eb83d1 | 2112 | if (unlikely(!mutex_trylock(&pool->assoc_mutex))) { |
ee378aa4 | 2113 | spin_unlock_irq(&pool->gcwq->lock); |
b2eb83d1 | 2114 | mutex_lock(&pool->assoc_mutex); |
ee378aa4 LJ |
2115 | /* |
2116 | * CPU hotplug could have happened while we were waiting | |
b2eb83d1 | 2117 | * for assoc_mutex. Hotplug itself can't handle us |
ee378aa4 LJ |
2118 | * because manager isn't either on idle or busy list, and |
2119 | * @gcwq's state and ours could have deviated. | |
2120 | * | |
b2eb83d1 | 2121 | * As hotplug is now excluded via assoc_mutex, we can |
ee378aa4 LJ |
2122 | * simply try to bind. It will succeed or fail depending |
2123 | * on @gcwq's current state. Try it and adjust | |
2124 | * %WORKER_UNBOUND accordingly. | |
2125 | */ | |
2126 | if (worker_maybe_bind_and_lock(worker)) | |
2127 | worker->flags &= ~WORKER_UNBOUND; | |
2128 | else | |
2129 | worker->flags |= WORKER_UNBOUND; | |
73f53c4a | 2130 | |
ee378aa4 LJ |
2131 | ret = true; |
2132 | } | |
73f53c4a | 2133 | |
11ebea50 | 2134 | pool->flags &= ~POOL_MANAGE_WORKERS; |
73f53c4a TH |
2135 | |
2136 | /* | |
e22bee78 TH |
2137 | * Destroy and then create so that may_start_working() is true |
2138 | * on return. | |
73f53c4a | 2139 | */ |
63d95a91 TH |
2140 | ret |= maybe_destroy_workers(pool); |
2141 | ret |= maybe_create_worker(pool); | |
e22bee78 | 2142 | |
552a37e9 | 2143 | pool->flags &= ~POOL_MANAGING_WORKERS; |
b2eb83d1 | 2144 | mutex_unlock(&pool->assoc_mutex); |
e22bee78 | 2145 | return ret; |
73f53c4a TH |
2146 | } |
2147 | ||
a62428c0 TH |
2148 | /** |
2149 | * process_one_work - process single work | |
c34056a3 | 2150 | * @worker: self |
a62428c0 TH |
2151 | * @work: work to process |
2152 | * | |
2153 | * Process @work. This function contains all the logics necessary to | |
2154 | * process a single work including synchronization against and | |
2155 | * interaction with other workers on the same cpu, queueing and | |
2156 | * flushing. As long as context requirement is met, any worker can | |
2157 | * call this function to process a work. | |
2158 | * | |
2159 | * CONTEXT: | |
8b03ae3c | 2160 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
a62428c0 | 2161 | */ |
c34056a3 | 2162 | static void process_one_work(struct worker *worker, struct work_struct *work) |
06bd6ebf NK |
2163 | __releases(&gcwq->lock) |
2164 | __acquires(&gcwq->lock) | |
a62428c0 | 2165 | { |
7e11629d | 2166 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
bd7bdd43 TH |
2167 | struct worker_pool *pool = worker->pool; |
2168 | struct global_cwq *gcwq = pool->gcwq; | |
c8e55f36 | 2169 | struct hlist_head *bwh = busy_worker_head(gcwq, work); |
fb0e7beb | 2170 | bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; |
a62428c0 | 2171 | work_func_t f = work->func; |
73f53c4a | 2172 | int work_color; |
7e11629d | 2173 | struct worker *collision; |
a62428c0 TH |
2174 | #ifdef CONFIG_LOCKDEP |
2175 | /* | |
2176 | * It is permissible to free the struct work_struct from | |
2177 | * inside the function that is called from it, this we need to | |
2178 | * take into account for lockdep too. To avoid bogus "held | |
2179 | * lock freed" warnings as well as problems when looking into | |
2180 | * work->lockdep_map, make a copy and use that here. | |
2181 | */ | |
4d82a1de PZ |
2182 | struct lockdep_map lockdep_map; |
2183 | ||
2184 | lockdep_copy_map(&lockdep_map, &work->lockdep_map); | |
a62428c0 | 2185 | #endif |
6fec10a1 TH |
2186 | /* |
2187 | * Ensure we're on the correct CPU. DISASSOCIATED test is | |
2188 | * necessary to avoid spurious warnings from rescuers servicing the | |
2189 | * unbound or a disassociated gcwq. | |
2190 | */ | |
5f7dabfd | 2191 | WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && |
6fec10a1 | 2192 | !(gcwq->flags & GCWQ_DISASSOCIATED) && |
25511a47 TH |
2193 | raw_smp_processor_id() != gcwq->cpu); |
2194 | ||
7e11629d TH |
2195 | /* |
2196 | * A single work shouldn't be executed concurrently by | |
2197 | * multiple workers on a single cpu. Check whether anyone is | |
2198 | * already processing the work. If so, defer the work to the | |
2199 | * currently executing one. | |
2200 | */ | |
2201 | collision = __find_worker_executing_work(gcwq, bwh, work); | |
2202 | if (unlikely(collision)) { | |
2203 | move_linked_works(work, &collision->scheduled, NULL); | |
2204 | return; | |
2205 | } | |
2206 | ||
8930caba | 2207 | /* claim and dequeue */ |
a62428c0 | 2208 | debug_work_deactivate(work); |
c8e55f36 | 2209 | hlist_add_head(&worker->hentry, bwh); |
c34056a3 | 2210 | worker->current_work = work; |
8cca0eea | 2211 | worker->current_cwq = cwq; |
73f53c4a | 2212 | work_color = get_work_color(work); |
7a22ad75 | 2213 | |
a62428c0 TH |
2214 | list_del_init(&work->entry); |
2215 | ||
fb0e7beb TH |
2216 | /* |
2217 | * CPU intensive works don't participate in concurrency | |
2218 | * management. They're the scheduler's responsibility. | |
2219 | */ | |
2220 | if (unlikely(cpu_intensive)) | |
2221 | worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); | |
2222 | ||
974271c4 TH |
2223 | /* |
2224 | * Unbound gcwq isn't concurrency managed and work items should be | |
2225 | * executed ASAP. Wake up another worker if necessary. | |
2226 | */ | |
63d95a91 TH |
2227 | if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) |
2228 | wake_up_worker(pool); | |
974271c4 | 2229 | |
8930caba | 2230 | /* |
23657bb1 TH |
2231 | * Record the last CPU and clear PENDING which should be the last |
2232 | * update to @work. Also, do this inside @gcwq->lock so that | |
2233 | * PENDING and queued state changes happen together while IRQ is | |
2234 | * disabled. | |
8930caba | 2235 | */ |
8930caba | 2236 | set_work_cpu_and_clear_pending(work, gcwq->cpu); |
a62428c0 | 2237 | |
8b03ae3c | 2238 | spin_unlock_irq(&gcwq->lock); |
a62428c0 | 2239 | |
e159489b | 2240 | lock_map_acquire_read(&cwq->wq->lockdep_map); |
a62428c0 | 2241 | lock_map_acquire(&lockdep_map); |
e36c886a | 2242 | trace_workqueue_execute_start(work); |
a62428c0 | 2243 | f(work); |
e36c886a AV |
2244 | /* |
2245 | * While we must be careful to not use "work" after this, the trace | |
2246 | * point will only record its address. | |
2247 | */ | |
2248 | trace_workqueue_execute_end(work); | |
a62428c0 TH |
2249 | lock_map_release(&lockdep_map); |
2250 | lock_map_release(&cwq->wq->lockdep_map); | |
2251 | ||
2252 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { | |
044c782c VI |
2253 | pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" |
2254 | " last function: %pf\n", | |
2255 | current->comm, preempt_count(), task_pid_nr(current), f); | |
a62428c0 TH |
2256 | debug_show_held_locks(current); |
2257 | dump_stack(); | |
2258 | } | |
2259 | ||
8b03ae3c | 2260 | spin_lock_irq(&gcwq->lock); |
a62428c0 | 2261 | |
fb0e7beb TH |
2262 | /* clear cpu intensive status */ |
2263 | if (unlikely(cpu_intensive)) | |
2264 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); | |
2265 | ||
a62428c0 | 2266 | /* we're done with it, release */ |
c8e55f36 | 2267 | hlist_del_init(&worker->hentry); |
c34056a3 | 2268 | worker->current_work = NULL; |
8cca0eea | 2269 | worker->current_cwq = NULL; |
b3f9f405 | 2270 | cwq_dec_nr_in_flight(cwq, work_color); |
a62428c0 TH |
2271 | } |
2272 | ||
affee4b2 TH |
2273 | /** |
2274 | * process_scheduled_works - process scheduled works | |
2275 | * @worker: self | |
2276 | * | |
2277 | * Process all scheduled works. Please note that the scheduled list | |
2278 | * may change while processing a work, so this function repeatedly | |
2279 | * fetches a work from the top and executes it. | |
2280 | * | |
2281 | * CONTEXT: | |
8b03ae3c | 2282 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
affee4b2 TH |
2283 | * multiple times. |
2284 | */ | |
2285 | static void process_scheduled_works(struct worker *worker) | |
1da177e4 | 2286 | { |
affee4b2 TH |
2287 | while (!list_empty(&worker->scheduled)) { |
2288 | struct work_struct *work = list_first_entry(&worker->scheduled, | |
1da177e4 | 2289 | struct work_struct, entry); |
c34056a3 | 2290 | process_one_work(worker, work); |
1da177e4 | 2291 | } |
1da177e4 LT |
2292 | } |
2293 | ||
4690c4ab TH |
2294 | /** |
2295 | * worker_thread - the worker thread function | |
c34056a3 | 2296 | * @__worker: self |
4690c4ab | 2297 | * |
e22bee78 TH |
2298 | * The gcwq worker thread function. There's a single dynamic pool of |
2299 | * these per each cpu. These workers process all works regardless of | |
2300 | * their specific target workqueue. The only exception is works which | |
2301 | * belong to workqueues with a rescuer which will be explained in | |
2302 | * rescuer_thread(). | |
4690c4ab | 2303 | */ |
c34056a3 | 2304 | static int worker_thread(void *__worker) |
1da177e4 | 2305 | { |
c34056a3 | 2306 | struct worker *worker = __worker; |
bd7bdd43 TH |
2307 | struct worker_pool *pool = worker->pool; |
2308 | struct global_cwq *gcwq = pool->gcwq; | |
1da177e4 | 2309 | |
e22bee78 TH |
2310 | /* tell the scheduler that this is a workqueue worker */ |
2311 | worker->task->flags |= PF_WQ_WORKER; | |
c8e55f36 | 2312 | woke_up: |
c8e55f36 | 2313 | spin_lock_irq(&gcwq->lock); |
1da177e4 | 2314 | |
5f7dabfd LJ |
2315 | /* we are off idle list if destruction or rebind is requested */ |
2316 | if (unlikely(list_empty(&worker->entry))) { | |
c8e55f36 | 2317 | spin_unlock_irq(&gcwq->lock); |
25511a47 | 2318 | |
5f7dabfd | 2319 | /* if DIE is set, destruction is requested */ |
25511a47 TH |
2320 | if (worker->flags & WORKER_DIE) { |
2321 | worker->task->flags &= ~PF_WQ_WORKER; | |
2322 | return 0; | |
2323 | } | |
2324 | ||
5f7dabfd | 2325 | /* otherwise, rebind */ |
25511a47 TH |
2326 | idle_worker_rebind(worker); |
2327 | goto woke_up; | |
c8e55f36 | 2328 | } |
affee4b2 | 2329 | |
c8e55f36 | 2330 | worker_leave_idle(worker); |
db7bccf4 | 2331 | recheck: |
e22bee78 | 2332 | /* no more worker necessary? */ |
63d95a91 | 2333 | if (!need_more_worker(pool)) |
e22bee78 TH |
2334 | goto sleep; |
2335 | ||
2336 | /* do we need to manage? */ | |
63d95a91 | 2337 | if (unlikely(!may_start_working(pool)) && manage_workers(worker)) |
e22bee78 TH |
2338 | goto recheck; |
2339 | ||
c8e55f36 TH |
2340 | /* |
2341 | * ->scheduled list can only be filled while a worker is | |
2342 | * preparing to process a work or actually processing it. | |
2343 | * Make sure nobody diddled with it while I was sleeping. | |
2344 | */ | |
2345 | BUG_ON(!list_empty(&worker->scheduled)); | |
2346 | ||
e22bee78 TH |
2347 | /* |
2348 | * When control reaches this point, we're guaranteed to have | |
2349 | * at least one idle worker or that someone else has already | |
2350 | * assumed the manager role. | |
2351 | */ | |
2352 | worker_clr_flags(worker, WORKER_PREP); | |
2353 | ||
2354 | do { | |
c8e55f36 | 2355 | struct work_struct *work = |
bd7bdd43 | 2356 | list_first_entry(&pool->worklist, |
c8e55f36 TH |
2357 | struct work_struct, entry); |
2358 | ||
2359 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { | |
2360 | /* optimization path, not strictly necessary */ | |
2361 | process_one_work(worker, work); | |
2362 | if (unlikely(!list_empty(&worker->scheduled))) | |
affee4b2 | 2363 | process_scheduled_works(worker); |
c8e55f36 TH |
2364 | } else { |
2365 | move_linked_works(work, &worker->scheduled, NULL); | |
2366 | process_scheduled_works(worker); | |
affee4b2 | 2367 | } |
63d95a91 | 2368 | } while (keep_working(pool)); |
e22bee78 TH |
2369 | |
2370 | worker_set_flags(worker, WORKER_PREP, false); | |
d313dd85 | 2371 | sleep: |
63d95a91 | 2372 | if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) |
e22bee78 | 2373 | goto recheck; |
d313dd85 | 2374 | |
c8e55f36 | 2375 | /* |
e22bee78 TH |
2376 | * gcwq->lock is held and there's no work to process and no |
2377 | * need to manage, sleep. Workers are woken up only while | |
2378 | * holding gcwq->lock or from local cpu, so setting the | |
2379 | * current state before releasing gcwq->lock is enough to | |
2380 | * prevent losing any event. | |
c8e55f36 TH |
2381 | */ |
2382 | worker_enter_idle(worker); | |
2383 | __set_current_state(TASK_INTERRUPTIBLE); | |
2384 | spin_unlock_irq(&gcwq->lock); | |
2385 | schedule(); | |
2386 | goto woke_up; | |
1da177e4 LT |
2387 | } |
2388 | ||
e22bee78 TH |
2389 | /** |
2390 | * rescuer_thread - the rescuer thread function | |
2391 | * @__wq: the associated workqueue | |
2392 | * | |
2393 | * Workqueue rescuer thread function. There's one rescuer for each | |
2394 | * workqueue which has WQ_RESCUER set. | |
2395 | * | |
2396 | * Regular work processing on a gcwq may block trying to create a new | |
2397 | * worker which uses GFP_KERNEL allocation which has slight chance of | |
2398 | * developing into deadlock if some works currently on the same queue | |
2399 | * need to be processed to satisfy the GFP_KERNEL allocation. This is | |
2400 | * the problem rescuer solves. | |
2401 | * | |
2402 | * When such condition is possible, the gcwq summons rescuers of all | |
2403 | * workqueues which have works queued on the gcwq and let them process | |
2404 | * those works so that forward progress can be guaranteed. | |
2405 | * | |
2406 | * This should happen rarely. | |
2407 | */ | |
2408 | static int rescuer_thread(void *__wq) | |
2409 | { | |
2410 | struct workqueue_struct *wq = __wq; | |
2411 | struct worker *rescuer = wq->rescuer; | |
2412 | struct list_head *scheduled = &rescuer->scheduled; | |
f3421797 | 2413 | bool is_unbound = wq->flags & WQ_UNBOUND; |
e22bee78 TH |
2414 | unsigned int cpu; |
2415 | ||
2416 | set_user_nice(current, RESCUER_NICE_LEVEL); | |
2417 | repeat: | |
2418 | set_current_state(TASK_INTERRUPTIBLE); | |
2419 | ||
412d32e6 MG |
2420 | if (kthread_should_stop()) { |
2421 | __set_current_state(TASK_RUNNING); | |
e22bee78 | 2422 | return 0; |
412d32e6 | 2423 | } |
e22bee78 | 2424 | |
f3421797 TH |
2425 | /* |
2426 | * See whether any cpu is asking for help. Unbounded | |
2427 | * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. | |
2428 | */ | |
f2e005aa | 2429 | for_each_mayday_cpu(cpu, wq->mayday_mask) { |
f3421797 TH |
2430 | unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; |
2431 | struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); | |
bd7bdd43 TH |
2432 | struct worker_pool *pool = cwq->pool; |
2433 | struct global_cwq *gcwq = pool->gcwq; | |
e22bee78 TH |
2434 | struct work_struct *work, *n; |
2435 | ||
2436 | __set_current_state(TASK_RUNNING); | |
f2e005aa | 2437 | mayday_clear_cpu(cpu, wq->mayday_mask); |
e22bee78 TH |
2438 | |
2439 | /* migrate to the target cpu if possible */ | |
bd7bdd43 | 2440 | rescuer->pool = pool; |
e22bee78 TH |
2441 | worker_maybe_bind_and_lock(rescuer); |
2442 | ||
2443 | /* | |
2444 | * Slurp in all works issued via this workqueue and | |
2445 | * process'em. | |
2446 | */ | |
2447 | BUG_ON(!list_empty(&rescuer->scheduled)); | |
bd7bdd43 | 2448 | list_for_each_entry_safe(work, n, &pool->worklist, entry) |
e22bee78 TH |
2449 | if (get_work_cwq(work) == cwq) |
2450 | move_linked_works(work, scheduled, &n); | |
2451 | ||
2452 | process_scheduled_works(rescuer); | |
7576958a TH |
2453 | |
2454 | /* | |
2455 | * Leave this gcwq. If keep_working() is %true, notify a | |
2456 | * regular worker; otherwise, we end up with 0 concurrency | |
2457 | * and stalling the execution. | |
2458 | */ | |
63d95a91 TH |
2459 | if (keep_working(pool)) |
2460 | wake_up_worker(pool); | |
7576958a | 2461 | |
e22bee78 TH |
2462 | spin_unlock_irq(&gcwq->lock); |
2463 | } | |
2464 | ||
2465 | schedule(); | |
2466 | goto repeat; | |
1da177e4 LT |
2467 | } |
2468 | ||
fc2e4d70 ON |
2469 | struct wq_barrier { |
2470 | struct work_struct work; | |
2471 | struct completion done; | |
2472 | }; | |
2473 | ||
2474 | static void wq_barrier_func(struct work_struct *work) | |
2475 | { | |
2476 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); | |
2477 | complete(&barr->done); | |
2478 | } | |
2479 | ||
4690c4ab TH |
2480 | /** |
2481 | * insert_wq_barrier - insert a barrier work | |
2482 | * @cwq: cwq to insert barrier into | |
2483 | * @barr: wq_barrier to insert | |
affee4b2 TH |
2484 | * @target: target work to attach @barr to |
2485 | * @worker: worker currently executing @target, NULL if @target is not executing | |
4690c4ab | 2486 | * |
affee4b2 TH |
2487 | * @barr is linked to @target such that @barr is completed only after |
2488 | * @target finishes execution. Please note that the ordering | |
2489 | * guarantee is observed only with respect to @target and on the local | |
2490 | * cpu. | |
2491 | * | |
2492 | * Currently, a queued barrier can't be canceled. This is because | |
2493 | * try_to_grab_pending() can't determine whether the work to be | |
2494 | * grabbed is at the head of the queue and thus can't clear LINKED | |
2495 | * flag of the previous work while there must be a valid next work | |
2496 | * after a work with LINKED flag set. | |
2497 | * | |
2498 | * Note that when @worker is non-NULL, @target may be modified | |
2499 | * underneath us, so we can't reliably determine cwq from @target. | |
4690c4ab TH |
2500 | * |
2501 | * CONTEXT: | |
8b03ae3c | 2502 | * spin_lock_irq(gcwq->lock). |
4690c4ab | 2503 | */ |
83c22520 | 2504 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
affee4b2 TH |
2505 | struct wq_barrier *barr, |
2506 | struct work_struct *target, struct worker *worker) | |
fc2e4d70 | 2507 | { |
affee4b2 TH |
2508 | struct list_head *head; |
2509 | unsigned int linked = 0; | |
2510 | ||
dc186ad7 | 2511 | /* |
8b03ae3c | 2512 | * debugobject calls are safe here even with gcwq->lock locked |
dc186ad7 TG |
2513 | * as we know for sure that this will not trigger any of the |
2514 | * checks and call back into the fixup functions where we | |
2515 | * might deadlock. | |
2516 | */ | |
ca1cab37 | 2517 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
22df02bb | 2518 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
fc2e4d70 | 2519 | init_completion(&barr->done); |
83c22520 | 2520 | |
affee4b2 TH |
2521 | /* |
2522 | * If @target is currently being executed, schedule the | |
2523 | * barrier to the worker; otherwise, put it after @target. | |
2524 | */ | |
2525 | if (worker) | |
2526 | head = worker->scheduled.next; | |
2527 | else { | |
2528 | unsigned long *bits = work_data_bits(target); | |
2529 | ||
2530 | head = target->entry.next; | |
2531 | /* there can already be other linked works, inherit and set */ | |
2532 | linked = *bits & WORK_STRUCT_LINKED; | |
2533 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); | |
2534 | } | |
2535 | ||
dc186ad7 | 2536 | debug_work_activate(&barr->work); |
affee4b2 TH |
2537 | insert_work(cwq, &barr->work, head, |
2538 | work_color_to_flags(WORK_NO_COLOR) | linked); | |
fc2e4d70 ON |
2539 | } |
2540 | ||
73f53c4a TH |
2541 | /** |
2542 | * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing | |
2543 | * @wq: workqueue being flushed | |
2544 | * @flush_color: new flush color, < 0 for no-op | |
2545 | * @work_color: new work color, < 0 for no-op | |
2546 | * | |
2547 | * Prepare cwqs for workqueue flushing. | |
2548 | * | |
2549 | * If @flush_color is non-negative, flush_color on all cwqs should be | |
2550 | * -1. If no cwq has in-flight commands at the specified color, all | |
2551 | * cwq->flush_color's stay at -1 and %false is returned. If any cwq | |
2552 | * has in flight commands, its cwq->flush_color is set to | |
2553 | * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq | |
2554 | * wakeup logic is armed and %true is returned. | |
2555 | * | |
2556 | * The caller should have initialized @wq->first_flusher prior to | |
2557 | * calling this function with non-negative @flush_color. If | |
2558 | * @flush_color is negative, no flush color update is done and %false | |
2559 | * is returned. | |
2560 | * | |
2561 | * If @work_color is non-negative, all cwqs should have the same | |
2562 | * work_color which is previous to @work_color and all will be | |
2563 | * advanced to @work_color. | |
2564 | * | |
2565 | * CONTEXT: | |
2566 | * mutex_lock(wq->flush_mutex). | |
2567 | * | |
2568 | * RETURNS: | |
2569 | * %true if @flush_color >= 0 and there's something to flush. %false | |
2570 | * otherwise. | |
2571 | */ | |
2572 | static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, | |
2573 | int flush_color, int work_color) | |
1da177e4 | 2574 | { |
73f53c4a TH |
2575 | bool wait = false; |
2576 | unsigned int cpu; | |
1da177e4 | 2577 | |
73f53c4a TH |
2578 | if (flush_color >= 0) { |
2579 | BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); | |
2580 | atomic_set(&wq->nr_cwqs_to_flush, 1); | |
1da177e4 | 2581 | } |
2355b70f | 2582 | |
f3421797 | 2583 | for_each_cwq_cpu(cpu, wq) { |
73f53c4a | 2584 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
bd7bdd43 | 2585 | struct global_cwq *gcwq = cwq->pool->gcwq; |
fc2e4d70 | 2586 | |
8b03ae3c | 2587 | spin_lock_irq(&gcwq->lock); |
83c22520 | 2588 | |
73f53c4a TH |
2589 | if (flush_color >= 0) { |
2590 | BUG_ON(cwq->flush_color != -1); | |
fc2e4d70 | 2591 | |
73f53c4a TH |
2592 | if (cwq->nr_in_flight[flush_color]) { |
2593 | cwq->flush_color = flush_color; | |
2594 | atomic_inc(&wq->nr_cwqs_to_flush); | |
2595 | wait = true; | |
2596 | } | |
2597 | } | |
1da177e4 | 2598 | |
73f53c4a TH |
2599 | if (work_color >= 0) { |
2600 | BUG_ON(work_color != work_next_color(cwq->work_color)); | |
2601 | cwq->work_color = work_color; | |
2602 | } | |
1da177e4 | 2603 | |
8b03ae3c | 2604 | spin_unlock_irq(&gcwq->lock); |
1da177e4 | 2605 | } |
2355b70f | 2606 | |
73f53c4a TH |
2607 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) |
2608 | complete(&wq->first_flusher->done); | |
14441960 | 2609 | |
73f53c4a | 2610 | return wait; |
1da177e4 LT |
2611 | } |
2612 | ||
0fcb78c2 | 2613 | /** |
1da177e4 | 2614 | * flush_workqueue - ensure that any scheduled work has run to completion. |
0fcb78c2 | 2615 | * @wq: workqueue to flush |
1da177e4 LT |
2616 | * |
2617 | * Forces execution of the workqueue and blocks until its completion. | |
2618 | * This is typically used in driver shutdown handlers. | |
2619 | * | |
fc2e4d70 ON |
2620 | * We sleep until all works which were queued on entry have been handled, |
2621 | * but we are not livelocked by new incoming ones. | |
1da177e4 | 2622 | */ |
7ad5b3a5 | 2623 | void flush_workqueue(struct workqueue_struct *wq) |
1da177e4 | 2624 | { |
73f53c4a TH |
2625 | struct wq_flusher this_flusher = { |
2626 | .list = LIST_HEAD_INIT(this_flusher.list), | |
2627 | .flush_color = -1, | |
2628 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), | |
2629 | }; | |
2630 | int next_color; | |
1da177e4 | 2631 | |
3295f0ef IM |
2632 | lock_map_acquire(&wq->lockdep_map); |
2633 | lock_map_release(&wq->lockdep_map); | |
73f53c4a TH |
2634 | |
2635 | mutex_lock(&wq->flush_mutex); | |
2636 | ||
2637 | /* | |
2638 | * Start-to-wait phase | |
2639 | */ | |
2640 | next_color = work_next_color(wq->work_color); | |
2641 | ||
2642 | if (next_color != wq->flush_color) { | |
2643 | /* | |
2644 | * Color space is not full. The current work_color | |
2645 | * becomes our flush_color and work_color is advanced | |
2646 | * by one. | |
2647 | */ | |
2648 | BUG_ON(!list_empty(&wq->flusher_overflow)); | |
2649 | this_flusher.flush_color = wq->work_color; | |
2650 | wq->work_color = next_color; | |
2651 | ||
2652 | if (!wq->first_flusher) { | |
2653 | /* no flush in progress, become the first flusher */ | |
2654 | BUG_ON(wq->flush_color != this_flusher.flush_color); | |
2655 | ||
2656 | wq->first_flusher = &this_flusher; | |
2657 | ||
2658 | if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, | |
2659 | wq->work_color)) { | |
2660 | /* nothing to flush, done */ | |
2661 | wq->flush_color = next_color; | |
2662 | wq->first_flusher = NULL; | |
2663 | goto out_unlock; | |
2664 | } | |
2665 | } else { | |
2666 | /* wait in queue */ | |
2667 | BUG_ON(wq->flush_color == this_flusher.flush_color); | |
2668 | list_add_tail(&this_flusher.list, &wq->flusher_queue); | |
2669 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); | |
2670 | } | |
2671 | } else { | |
2672 | /* | |
2673 | * Oops, color space is full, wait on overflow queue. | |
2674 | * The next flush completion will assign us | |
2675 | * flush_color and transfer to flusher_queue. | |
2676 | */ | |
2677 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); | |
2678 | } | |
2679 | ||
2680 | mutex_unlock(&wq->flush_mutex); | |
2681 | ||
2682 | wait_for_completion(&this_flusher.done); | |
2683 | ||
2684 | /* | |
2685 | * Wake-up-and-cascade phase | |
2686 | * | |
2687 | * First flushers are responsible for cascading flushes and | |
2688 | * handling overflow. Non-first flushers can simply return. | |
2689 | */ | |
2690 | if (wq->first_flusher != &this_flusher) | |
2691 | return; | |
2692 | ||
2693 | mutex_lock(&wq->flush_mutex); | |
2694 | ||
4ce48b37 TH |
2695 | /* we might have raced, check again with mutex held */ |
2696 | if (wq->first_flusher != &this_flusher) | |
2697 | goto out_unlock; | |
2698 | ||
73f53c4a TH |
2699 | wq->first_flusher = NULL; |
2700 | ||
2701 | BUG_ON(!list_empty(&this_flusher.list)); | |
2702 | BUG_ON(wq->flush_color != this_flusher.flush_color); | |
2703 | ||
2704 | while (true) { | |
2705 | struct wq_flusher *next, *tmp; | |
2706 | ||
2707 | /* complete all the flushers sharing the current flush color */ | |
2708 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { | |
2709 | if (next->flush_color != wq->flush_color) | |
2710 | break; | |
2711 | list_del_init(&next->list); | |
2712 | complete(&next->done); | |
2713 | } | |
2714 | ||
2715 | BUG_ON(!list_empty(&wq->flusher_overflow) && | |
2716 | wq->flush_color != work_next_color(wq->work_color)); | |
2717 | ||
2718 | /* this flush_color is finished, advance by one */ | |
2719 | wq->flush_color = work_next_color(wq->flush_color); | |
2720 | ||
2721 | /* one color has been freed, handle overflow queue */ | |
2722 | if (!list_empty(&wq->flusher_overflow)) { | |
2723 | /* | |
2724 | * Assign the same color to all overflowed | |
2725 | * flushers, advance work_color and append to | |
2726 | * flusher_queue. This is the start-to-wait | |
2727 | * phase for these overflowed flushers. | |
2728 | */ | |
2729 | list_for_each_entry(tmp, &wq->flusher_overflow, list) | |
2730 | tmp->flush_color = wq->work_color; | |
2731 | ||
2732 | wq->work_color = work_next_color(wq->work_color); | |
2733 | ||
2734 | list_splice_tail_init(&wq->flusher_overflow, | |
2735 | &wq->flusher_queue); | |
2736 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); | |
2737 | } | |
2738 | ||
2739 | if (list_empty(&wq->flusher_queue)) { | |
2740 | BUG_ON(wq->flush_color != wq->work_color); | |
2741 | break; | |
2742 | } | |
2743 | ||
2744 | /* | |
2745 | * Need to flush more colors. Make the next flusher | |
2746 | * the new first flusher and arm cwqs. | |
2747 | */ | |
2748 | BUG_ON(wq->flush_color == wq->work_color); | |
2749 | BUG_ON(wq->flush_color != next->flush_color); | |
2750 | ||
2751 | list_del_init(&next->list); | |
2752 | wq->first_flusher = next; | |
2753 | ||
2754 | if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) | |
2755 | break; | |
2756 | ||
2757 | /* | |
2758 | * Meh... this color is already done, clear first | |
2759 | * flusher and repeat cascading. | |
2760 | */ | |
2761 | wq->first_flusher = NULL; | |
2762 | } | |
2763 | ||
2764 | out_unlock: | |
2765 | mutex_unlock(&wq->flush_mutex); | |
1da177e4 | 2766 | } |
ae90dd5d | 2767 | EXPORT_SYMBOL_GPL(flush_workqueue); |
1da177e4 | 2768 | |
9c5a2ba7 TH |
2769 | /** |
2770 | * drain_workqueue - drain a workqueue | |
2771 | * @wq: workqueue to drain | |
2772 | * | |
2773 | * Wait until the workqueue becomes empty. While draining is in progress, | |
2774 | * only chain queueing is allowed. IOW, only currently pending or running | |
2775 | * work items on @wq can queue further work items on it. @wq is flushed | |
2776 | * repeatedly until it becomes empty. The number of flushing is detemined | |
2777 | * by the depth of chaining and should be relatively short. Whine if it | |
2778 | * takes too long. | |
2779 | */ | |
2780 | void drain_workqueue(struct workqueue_struct *wq) | |
2781 | { | |
2782 | unsigned int flush_cnt = 0; | |
2783 | unsigned int cpu; | |
2784 | ||
2785 | /* | |
2786 | * __queue_work() needs to test whether there are drainers, is much | |
2787 | * hotter than drain_workqueue() and already looks at @wq->flags. | |
2788 | * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. | |
2789 | */ | |
2790 | spin_lock(&workqueue_lock); | |
2791 | if (!wq->nr_drainers++) | |
2792 | wq->flags |= WQ_DRAINING; | |
2793 | spin_unlock(&workqueue_lock); | |
2794 | reflush: | |
2795 | flush_workqueue(wq); | |
2796 | ||
2797 | for_each_cwq_cpu(cpu, wq) { | |
2798 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
fa2563e4 | 2799 | bool drained; |
9c5a2ba7 | 2800 | |
bd7bdd43 | 2801 | spin_lock_irq(&cwq->pool->gcwq->lock); |
fa2563e4 | 2802 | drained = !cwq->nr_active && list_empty(&cwq->delayed_works); |
bd7bdd43 | 2803 | spin_unlock_irq(&cwq->pool->gcwq->lock); |
fa2563e4 TT |
2804 | |
2805 | if (drained) | |
9c5a2ba7 TH |
2806 | continue; |
2807 | ||
2808 | if (++flush_cnt == 10 || | |
2809 | (flush_cnt % 100 == 0 && flush_cnt <= 1000)) | |
044c782c VI |
2810 | pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n", |
2811 | wq->name, flush_cnt); | |
9c5a2ba7 TH |
2812 | goto reflush; |
2813 | } | |
2814 | ||
2815 | spin_lock(&workqueue_lock); | |
2816 | if (!--wq->nr_drainers) | |
2817 | wq->flags &= ~WQ_DRAINING; | |
2818 | spin_unlock(&workqueue_lock); | |
2819 | } | |
2820 | EXPORT_SYMBOL_GPL(drain_workqueue); | |
2821 | ||
606a5020 | 2822 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) |
db700897 | 2823 | { |
affee4b2 | 2824 | struct worker *worker = NULL; |
8b03ae3c | 2825 | struct global_cwq *gcwq; |
db700897 | 2826 | struct cpu_workqueue_struct *cwq; |
db700897 ON |
2827 | |
2828 | might_sleep(); | |
7a22ad75 TH |
2829 | gcwq = get_work_gcwq(work); |
2830 | if (!gcwq) | |
baf59022 | 2831 | return false; |
db700897 | 2832 | |
8b03ae3c | 2833 | spin_lock_irq(&gcwq->lock); |
db700897 ON |
2834 | if (!list_empty(&work->entry)) { |
2835 | /* | |
2836 | * See the comment near try_to_grab_pending()->smp_rmb(). | |
7a22ad75 TH |
2837 | * If it was re-queued to a different gcwq under us, we |
2838 | * are not going to wait. | |
db700897 ON |
2839 | */ |
2840 | smp_rmb(); | |
7a22ad75 | 2841 | cwq = get_work_cwq(work); |
bd7bdd43 | 2842 | if (unlikely(!cwq || gcwq != cwq->pool->gcwq)) |
4690c4ab | 2843 | goto already_gone; |
606a5020 | 2844 | } else { |
7a22ad75 | 2845 | worker = find_worker_executing_work(gcwq, work); |
affee4b2 | 2846 | if (!worker) |
4690c4ab | 2847 | goto already_gone; |
7a22ad75 | 2848 | cwq = worker->current_cwq; |
606a5020 | 2849 | } |
db700897 | 2850 | |
baf59022 | 2851 | insert_wq_barrier(cwq, barr, work, worker); |
8b03ae3c | 2852 | spin_unlock_irq(&gcwq->lock); |
7a22ad75 | 2853 | |
e159489b TH |
2854 | /* |
2855 | * If @max_active is 1 or rescuer is in use, flushing another work | |
2856 | * item on the same workqueue may lead to deadlock. Make sure the | |
2857 | * flusher is not running on the same workqueue by verifying write | |
2858 | * access. | |
2859 | */ | |
2860 | if (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER) | |
2861 | lock_map_acquire(&cwq->wq->lockdep_map); | |
2862 | else | |
2863 | lock_map_acquire_read(&cwq->wq->lockdep_map); | |
7a22ad75 | 2864 | lock_map_release(&cwq->wq->lockdep_map); |
e159489b | 2865 | |
401a8d04 | 2866 | return true; |
4690c4ab | 2867 | already_gone: |
8b03ae3c | 2868 | spin_unlock_irq(&gcwq->lock); |
401a8d04 | 2869 | return false; |
db700897 | 2870 | } |
baf59022 TH |
2871 | |
2872 | /** | |
2873 | * flush_work - wait for a work to finish executing the last queueing instance | |
2874 | * @work: the work to flush | |
2875 | * | |
606a5020 TH |
2876 | * Wait until @work has finished execution. @work is guaranteed to be idle |
2877 | * on return if it hasn't been requeued since flush started. | |
baf59022 TH |
2878 | * |
2879 | * RETURNS: | |
2880 | * %true if flush_work() waited for the work to finish execution, | |
2881 | * %false if it was already idle. | |
2882 | */ | |
2883 | bool flush_work(struct work_struct *work) | |
2884 | { | |
2885 | struct wq_barrier barr; | |
2886 | ||
0976dfc1 SB |
2887 | lock_map_acquire(&work->lockdep_map); |
2888 | lock_map_release(&work->lockdep_map); | |
2889 | ||
606a5020 | 2890 | if (start_flush_work(work, &barr)) { |
401a8d04 TH |
2891 | wait_for_completion(&barr.done); |
2892 | destroy_work_on_stack(&barr.work); | |
2893 | return true; | |
606a5020 | 2894 | } else { |
401a8d04 | 2895 | return false; |
6e84d644 | 2896 | } |
6e84d644 | 2897 | } |
606a5020 | 2898 | EXPORT_SYMBOL_GPL(flush_work); |
6e84d644 | 2899 | |
36e227d2 | 2900 | static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) |
1f1f642e | 2901 | { |
bbb68dfa | 2902 | unsigned long flags; |
1f1f642e ON |
2903 | int ret; |
2904 | ||
2905 | do { | |
bbb68dfa TH |
2906 | ret = try_to_grab_pending(work, is_dwork, &flags); |
2907 | /* | |
2908 | * If someone else is canceling, wait for the same event it | |
2909 | * would be waiting for before retrying. | |
2910 | */ | |
2911 | if (unlikely(ret == -ENOENT)) | |
606a5020 | 2912 | flush_work(work); |
1f1f642e ON |
2913 | } while (unlikely(ret < 0)); |
2914 | ||
bbb68dfa TH |
2915 | /* tell other tasks trying to grab @work to back off */ |
2916 | mark_work_canceling(work); | |
2917 | local_irq_restore(flags); | |
2918 | ||
606a5020 | 2919 | flush_work(work); |
7a22ad75 | 2920 | clear_work_data(work); |
1f1f642e ON |
2921 | return ret; |
2922 | } | |
2923 | ||
6e84d644 | 2924 | /** |
401a8d04 TH |
2925 | * cancel_work_sync - cancel a work and wait for it to finish |
2926 | * @work: the work to cancel | |
6e84d644 | 2927 | * |
401a8d04 TH |
2928 | * Cancel @work and wait for its execution to finish. This function |
2929 | * can be used even if the work re-queues itself or migrates to | |
2930 | * another workqueue. On return from this function, @work is | |
2931 | * guaranteed to be not pending or executing on any CPU. | |
1f1f642e | 2932 | * |
401a8d04 TH |
2933 | * cancel_work_sync(&delayed_work->work) must not be used for |
2934 | * delayed_work's. Use cancel_delayed_work_sync() instead. | |
6e84d644 | 2935 | * |
401a8d04 | 2936 | * The caller must ensure that the workqueue on which @work was last |
6e84d644 | 2937 | * queued can't be destroyed before this function returns. |
401a8d04 TH |
2938 | * |
2939 | * RETURNS: | |
2940 | * %true if @work was pending, %false otherwise. | |
6e84d644 | 2941 | */ |
401a8d04 | 2942 | bool cancel_work_sync(struct work_struct *work) |
6e84d644 | 2943 | { |
36e227d2 | 2944 | return __cancel_work_timer(work, false); |
b89deed3 | 2945 | } |
28e53bdd | 2946 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
b89deed3 | 2947 | |
6e84d644 | 2948 | /** |
401a8d04 TH |
2949 | * flush_delayed_work - wait for a dwork to finish executing the last queueing |
2950 | * @dwork: the delayed work to flush | |
6e84d644 | 2951 | * |
401a8d04 TH |
2952 | * Delayed timer is cancelled and the pending work is queued for |
2953 | * immediate execution. Like flush_work(), this function only | |
2954 | * considers the last queueing instance of @dwork. | |
1f1f642e | 2955 | * |
401a8d04 TH |
2956 | * RETURNS: |
2957 | * %true if flush_work() waited for the work to finish execution, | |
2958 | * %false if it was already idle. | |
6e84d644 | 2959 | */ |
401a8d04 TH |
2960 | bool flush_delayed_work(struct delayed_work *dwork) |
2961 | { | |
8930caba | 2962 | local_irq_disable(); |
401a8d04 | 2963 | if (del_timer_sync(&dwork->timer)) |
1265057f | 2964 | __queue_work(dwork->cpu, |
401a8d04 | 2965 | get_work_cwq(&dwork->work)->wq, &dwork->work); |
8930caba | 2966 | local_irq_enable(); |
401a8d04 TH |
2967 | return flush_work(&dwork->work); |
2968 | } | |
2969 | EXPORT_SYMBOL(flush_delayed_work); | |
2970 | ||
09383498 | 2971 | /** |
57b30ae7 TH |
2972 | * cancel_delayed_work - cancel a delayed work |
2973 | * @dwork: delayed_work to cancel | |
09383498 | 2974 | * |
57b30ae7 TH |
2975 | * Kill off a pending delayed_work. Returns %true if @dwork was pending |
2976 | * and canceled; %false if wasn't pending. Note that the work callback | |
2977 | * function may still be running on return, unless it returns %true and the | |
2978 | * work doesn't re-arm itself. Explicitly flush or use | |
2979 | * cancel_delayed_work_sync() to wait on it. | |
09383498 | 2980 | * |
57b30ae7 | 2981 | * This function is safe to call from any context including IRQ handler. |
09383498 | 2982 | */ |
57b30ae7 | 2983 | bool cancel_delayed_work(struct delayed_work *dwork) |
09383498 | 2984 | { |
57b30ae7 TH |
2985 | unsigned long flags; |
2986 | int ret; | |
2987 | ||
2988 | do { | |
2989 | ret = try_to_grab_pending(&dwork->work, true, &flags); | |
2990 | } while (unlikely(ret == -EAGAIN)); | |
2991 | ||
2992 | if (unlikely(ret < 0)) | |
2993 | return false; | |
2994 | ||
2995 | set_work_cpu_and_clear_pending(&dwork->work, work_cpu(&dwork->work)); | |
2996 | local_irq_restore(flags); | |
c0158ca6 | 2997 | return ret; |
09383498 | 2998 | } |
57b30ae7 | 2999 | EXPORT_SYMBOL(cancel_delayed_work); |
09383498 | 3000 | |
401a8d04 TH |
3001 | /** |
3002 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish | |
3003 | * @dwork: the delayed work cancel | |
3004 | * | |
3005 | * This is cancel_work_sync() for delayed works. | |
3006 | * | |
3007 | * RETURNS: | |
3008 | * %true if @dwork was pending, %false otherwise. | |
3009 | */ | |
3010 | bool cancel_delayed_work_sync(struct delayed_work *dwork) | |
6e84d644 | 3011 | { |
36e227d2 | 3012 | return __cancel_work_timer(&dwork->work, true); |
6e84d644 | 3013 | } |
f5a421a4 | 3014 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
1da177e4 | 3015 | |
0fcb78c2 | 3016 | /** |
c1a220e7 ZR |
3017 | * schedule_work_on - put work task on a specific cpu |
3018 | * @cpu: cpu to put the work task on | |
3019 | * @work: job to be done | |
3020 | * | |
3021 | * This puts a job on a specific cpu | |
3022 | */ | |
d4283e93 | 3023 | bool schedule_work_on(int cpu, struct work_struct *work) |
c1a220e7 | 3024 | { |
d320c038 | 3025 | return queue_work_on(cpu, system_wq, work); |
c1a220e7 ZR |
3026 | } |
3027 | EXPORT_SYMBOL(schedule_work_on); | |
3028 | ||
0fcb78c2 | 3029 | /** |
0fcb78c2 REB |
3030 | * schedule_work - put work task in global workqueue |
3031 | * @work: job to be done | |
0fcb78c2 | 3032 | * |
d4283e93 TH |
3033 | * Returns %false if @work was already on the kernel-global workqueue and |
3034 | * %true otherwise. | |
5b0f437d BVA |
3035 | * |
3036 | * This puts a job in the kernel-global workqueue if it was not already | |
3037 | * queued and leaves it in the same position on the kernel-global | |
3038 | * workqueue otherwise. | |
0fcb78c2 | 3039 | */ |
d4283e93 | 3040 | bool schedule_work(struct work_struct *work) |
1da177e4 | 3041 | { |
d320c038 | 3042 | return queue_work(system_wq, work); |
1da177e4 | 3043 | } |
ae90dd5d | 3044 | EXPORT_SYMBOL(schedule_work); |
1da177e4 | 3045 | |
0fcb78c2 REB |
3046 | /** |
3047 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay | |
3048 | * @cpu: cpu to use | |
52bad64d | 3049 | * @dwork: job to be done |
0fcb78c2 REB |
3050 | * @delay: number of jiffies to wait |
3051 | * | |
3052 | * After waiting for a given time this puts a job in the kernel-global | |
3053 | * workqueue on the specified CPU. | |
3054 | */ | |
d4283e93 TH |
3055 | bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork, |
3056 | unsigned long delay) | |
1da177e4 | 3057 | { |
d320c038 | 3058 | return queue_delayed_work_on(cpu, system_wq, dwork, delay); |
1da177e4 | 3059 | } |
ae90dd5d | 3060 | EXPORT_SYMBOL(schedule_delayed_work_on); |
1da177e4 | 3061 | |
0fcb78c2 REB |
3062 | /** |
3063 | * schedule_delayed_work - put work task in global workqueue after delay | |
52bad64d DH |
3064 | * @dwork: job to be done |
3065 | * @delay: number of jiffies to wait or 0 for immediate execution | |
0fcb78c2 REB |
3066 | * |
3067 | * After waiting for a given time this puts a job in the kernel-global | |
3068 | * workqueue. | |
3069 | */ | |
d4283e93 | 3070 | bool schedule_delayed_work(struct delayed_work *dwork, unsigned long delay) |
1da177e4 | 3071 | { |
d320c038 | 3072 | return queue_delayed_work(system_wq, dwork, delay); |
1da177e4 | 3073 | } |
ae90dd5d | 3074 | EXPORT_SYMBOL(schedule_delayed_work); |
1da177e4 | 3075 | |
b6136773 | 3076 | /** |
31ddd871 | 3077 | * schedule_on_each_cpu - execute a function synchronously on each online CPU |
b6136773 | 3078 | * @func: the function to call |
b6136773 | 3079 | * |
31ddd871 TH |
3080 | * schedule_on_each_cpu() executes @func on each online CPU using the |
3081 | * system workqueue and blocks until all CPUs have completed. | |
b6136773 | 3082 | * schedule_on_each_cpu() is very slow. |
31ddd871 TH |
3083 | * |
3084 | * RETURNS: | |
3085 | * 0 on success, -errno on failure. | |
b6136773 | 3086 | */ |
65f27f38 | 3087 | int schedule_on_each_cpu(work_func_t func) |
15316ba8 CL |
3088 | { |
3089 | int cpu; | |
38f51568 | 3090 | struct work_struct __percpu *works; |
15316ba8 | 3091 | |
b6136773 AM |
3092 | works = alloc_percpu(struct work_struct); |
3093 | if (!works) | |
15316ba8 | 3094 | return -ENOMEM; |
b6136773 | 3095 | |
93981800 TH |
3096 | get_online_cpus(); |
3097 | ||
15316ba8 | 3098 | for_each_online_cpu(cpu) { |
9bfb1839 IM |
3099 | struct work_struct *work = per_cpu_ptr(works, cpu); |
3100 | ||
3101 | INIT_WORK(work, func); | |
b71ab8c2 | 3102 | schedule_work_on(cpu, work); |
65a64464 | 3103 | } |
93981800 TH |
3104 | |
3105 | for_each_online_cpu(cpu) | |
3106 | flush_work(per_cpu_ptr(works, cpu)); | |
3107 | ||
95402b38 | 3108 | put_online_cpus(); |
b6136773 | 3109 | free_percpu(works); |
15316ba8 CL |
3110 | return 0; |
3111 | } | |
3112 | ||
eef6a7d5 AS |
3113 | /** |
3114 | * flush_scheduled_work - ensure that any scheduled work has run to completion. | |
3115 | * | |
3116 | * Forces execution of the kernel-global workqueue and blocks until its | |
3117 | * completion. | |
3118 | * | |
3119 | * Think twice before calling this function! It's very easy to get into | |
3120 | * trouble if you don't take great care. Either of the following situations | |
3121 | * will lead to deadlock: | |
3122 | * | |
3123 | * One of the work items currently on the workqueue needs to acquire | |
3124 | * a lock held by your code or its caller. | |
3125 | * | |
3126 | * Your code is running in the context of a work routine. | |
3127 | * | |
3128 | * They will be detected by lockdep when they occur, but the first might not | |
3129 | * occur very often. It depends on what work items are on the workqueue and | |
3130 | * what locks they need, which you have no control over. | |
3131 | * | |
3132 | * In most situations flushing the entire workqueue is overkill; you merely | |
3133 | * need to know that a particular work item isn't queued and isn't running. | |
3134 | * In such cases you should use cancel_delayed_work_sync() or | |
3135 | * cancel_work_sync() instead. | |
3136 | */ | |
1da177e4 LT |
3137 | void flush_scheduled_work(void) |
3138 | { | |
d320c038 | 3139 | flush_workqueue(system_wq); |
1da177e4 | 3140 | } |
ae90dd5d | 3141 | EXPORT_SYMBOL(flush_scheduled_work); |
1da177e4 | 3142 | |
1fa44eca JB |
3143 | /** |
3144 | * execute_in_process_context - reliably execute the routine with user context | |
3145 | * @fn: the function to execute | |
1fa44eca JB |
3146 | * @ew: guaranteed storage for the execute work structure (must |
3147 | * be available when the work executes) | |
3148 | * | |
3149 | * Executes the function immediately if process context is available, | |
3150 | * otherwise schedules the function for delayed execution. | |
3151 | * | |
3152 | * Returns: 0 - function was executed | |
3153 | * 1 - function was scheduled for execution | |
3154 | */ | |
65f27f38 | 3155 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
1fa44eca JB |
3156 | { |
3157 | if (!in_interrupt()) { | |
65f27f38 | 3158 | fn(&ew->work); |
1fa44eca JB |
3159 | return 0; |
3160 | } | |
3161 | ||
65f27f38 | 3162 | INIT_WORK(&ew->work, fn); |
1fa44eca JB |
3163 | schedule_work(&ew->work); |
3164 | ||
3165 | return 1; | |
3166 | } | |
3167 | EXPORT_SYMBOL_GPL(execute_in_process_context); | |
3168 | ||
1da177e4 LT |
3169 | int keventd_up(void) |
3170 | { | |
d320c038 | 3171 | return system_wq != NULL; |
1da177e4 LT |
3172 | } |
3173 | ||
bdbc5dd7 | 3174 | static int alloc_cwqs(struct workqueue_struct *wq) |
0f900049 | 3175 | { |
65a64464 | 3176 | /* |
0f900049 TH |
3177 | * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. |
3178 | * Make sure that the alignment isn't lower than that of | |
3179 | * unsigned long long. | |
65a64464 | 3180 | */ |
0f900049 TH |
3181 | const size_t size = sizeof(struct cpu_workqueue_struct); |
3182 | const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, | |
3183 | __alignof__(unsigned long long)); | |
65a64464 | 3184 | |
e06ffa1e | 3185 | if (!(wq->flags & WQ_UNBOUND)) |
f3421797 | 3186 | wq->cpu_wq.pcpu = __alloc_percpu(size, align); |
931ac77e | 3187 | else { |
f3421797 TH |
3188 | void *ptr; |
3189 | ||
3190 | /* | |
3191 | * Allocate enough room to align cwq and put an extra | |
3192 | * pointer at the end pointing back to the originally | |
3193 | * allocated pointer which will be used for free. | |
3194 | */ | |
3195 | ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); | |
3196 | if (ptr) { | |
3197 | wq->cpu_wq.single = PTR_ALIGN(ptr, align); | |
3198 | *(void **)(wq->cpu_wq.single + 1) = ptr; | |
3199 | } | |
bdbc5dd7 | 3200 | } |
f3421797 | 3201 | |
0415b00d | 3202 | /* just in case, make sure it's actually aligned */ |
bdbc5dd7 TH |
3203 | BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); |
3204 | return wq->cpu_wq.v ? 0 : -ENOMEM; | |
0f900049 TH |
3205 | } |
3206 | ||
bdbc5dd7 | 3207 | static void free_cwqs(struct workqueue_struct *wq) |
0f900049 | 3208 | { |
e06ffa1e | 3209 | if (!(wq->flags & WQ_UNBOUND)) |
f3421797 TH |
3210 | free_percpu(wq->cpu_wq.pcpu); |
3211 | else if (wq->cpu_wq.single) { | |
3212 | /* the pointer to free is stored right after the cwq */ | |
bdbc5dd7 | 3213 | kfree(*(void **)(wq->cpu_wq.single + 1)); |
f3421797 | 3214 | } |
0f900049 TH |
3215 | } |
3216 | ||
f3421797 TH |
3217 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
3218 | const char *name) | |
b71ab8c2 | 3219 | { |
f3421797 TH |
3220 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
3221 | ||
3222 | if (max_active < 1 || max_active > lim) | |
044c782c VI |
3223 | pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", |
3224 | max_active, name, 1, lim); | |
b71ab8c2 | 3225 | |
f3421797 | 3226 | return clamp_val(max_active, 1, lim); |
b71ab8c2 TH |
3227 | } |
3228 | ||
b196be89 | 3229 | struct workqueue_struct *__alloc_workqueue_key(const char *fmt, |
d320c038 TH |
3230 | unsigned int flags, |
3231 | int max_active, | |
3232 | struct lock_class_key *key, | |
b196be89 | 3233 | const char *lock_name, ...) |
1da177e4 | 3234 | { |
b196be89 | 3235 | va_list args, args1; |
1da177e4 | 3236 | struct workqueue_struct *wq; |
c34056a3 | 3237 | unsigned int cpu; |
b196be89 TH |
3238 | size_t namelen; |
3239 | ||
3240 | /* determine namelen, allocate wq and format name */ | |
3241 | va_start(args, lock_name); | |
3242 | va_copy(args1, args); | |
3243 | namelen = vsnprintf(NULL, 0, fmt, args) + 1; | |
3244 | ||
3245 | wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL); | |
3246 | if (!wq) | |
3247 | goto err; | |
3248 | ||
3249 | vsnprintf(wq->name, namelen, fmt, args1); | |
3250 | va_end(args); | |
3251 | va_end(args1); | |
1da177e4 | 3252 | |
6370a6ad TH |
3253 | /* |
3254 | * Workqueues which may be used during memory reclaim should | |
3255 | * have a rescuer to guarantee forward progress. | |
3256 | */ | |
3257 | if (flags & WQ_MEM_RECLAIM) | |
3258 | flags |= WQ_RESCUER; | |
3259 | ||
d320c038 | 3260 | max_active = max_active ?: WQ_DFL_ACTIVE; |
b196be89 | 3261 | max_active = wq_clamp_max_active(max_active, flags, wq->name); |
3af24433 | 3262 | |
b196be89 | 3263 | /* init wq */ |
97e37d7b | 3264 | wq->flags = flags; |
a0a1a5fd | 3265 | wq->saved_max_active = max_active; |
73f53c4a TH |
3266 | mutex_init(&wq->flush_mutex); |
3267 | atomic_set(&wq->nr_cwqs_to_flush, 0); | |
3268 | INIT_LIST_HEAD(&wq->flusher_queue); | |
3269 | INIT_LIST_HEAD(&wq->flusher_overflow); | |
502ca9d8 | 3270 | |
eb13ba87 | 3271 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
cce1a165 | 3272 | INIT_LIST_HEAD(&wq->list); |
3af24433 | 3273 | |
bdbc5dd7 TH |
3274 | if (alloc_cwqs(wq) < 0) |
3275 | goto err; | |
3276 | ||
f3421797 | 3277 | for_each_cwq_cpu(cpu, wq) { |
1537663f | 3278 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
8b03ae3c | 3279 | struct global_cwq *gcwq = get_gcwq(cpu); |
3270476a | 3280 | int pool_idx = (bool)(flags & WQ_HIGHPRI); |
1537663f | 3281 | |
0f900049 | 3282 | BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); |
3270476a | 3283 | cwq->pool = &gcwq->pools[pool_idx]; |
c34056a3 | 3284 | cwq->wq = wq; |
73f53c4a | 3285 | cwq->flush_color = -1; |
1e19ffc6 | 3286 | cwq->max_active = max_active; |
1e19ffc6 | 3287 | INIT_LIST_HEAD(&cwq->delayed_works); |
e22bee78 | 3288 | } |
1537663f | 3289 | |
e22bee78 TH |
3290 | if (flags & WQ_RESCUER) { |
3291 | struct worker *rescuer; | |
3292 | ||
f2e005aa | 3293 | if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) |
e22bee78 TH |
3294 | goto err; |
3295 | ||
3296 | wq->rescuer = rescuer = alloc_worker(); | |
3297 | if (!rescuer) | |
3298 | goto err; | |
3299 | ||
b196be89 TH |
3300 | rescuer->task = kthread_create(rescuer_thread, wq, "%s", |
3301 | wq->name); | |
e22bee78 TH |
3302 | if (IS_ERR(rescuer->task)) |
3303 | goto err; | |
3304 | ||
e22bee78 TH |
3305 | rescuer->task->flags |= PF_THREAD_BOUND; |
3306 | wake_up_process(rescuer->task); | |
3af24433 ON |
3307 | } |
3308 | ||
a0a1a5fd TH |
3309 | /* |
3310 | * workqueue_lock protects global freeze state and workqueues | |
3311 | * list. Grab it, set max_active accordingly and add the new | |
3312 | * workqueue to workqueues list. | |
3313 | */ | |
1537663f | 3314 | spin_lock(&workqueue_lock); |
a0a1a5fd | 3315 | |
58a69cb4 | 3316 | if (workqueue_freezing && wq->flags & WQ_FREEZABLE) |
f3421797 | 3317 | for_each_cwq_cpu(cpu, wq) |
a0a1a5fd TH |
3318 | get_cwq(cpu, wq)->max_active = 0; |
3319 | ||
1537663f | 3320 | list_add(&wq->list, &workqueues); |
a0a1a5fd | 3321 | |
1537663f TH |
3322 | spin_unlock(&workqueue_lock); |
3323 | ||
3af24433 | 3324 | return wq; |
4690c4ab TH |
3325 | err: |
3326 | if (wq) { | |
bdbc5dd7 | 3327 | free_cwqs(wq); |
f2e005aa | 3328 | free_mayday_mask(wq->mayday_mask); |
e22bee78 | 3329 | kfree(wq->rescuer); |
4690c4ab TH |
3330 | kfree(wq); |
3331 | } | |
3332 | return NULL; | |
3af24433 | 3333 | } |
d320c038 | 3334 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
1da177e4 | 3335 | |
3af24433 ON |
3336 | /** |
3337 | * destroy_workqueue - safely terminate a workqueue | |
3338 | * @wq: target workqueue | |
3339 | * | |
3340 | * Safely destroy a workqueue. All work currently pending will be done first. | |
3341 | */ | |
3342 | void destroy_workqueue(struct workqueue_struct *wq) | |
3343 | { | |
c8e55f36 | 3344 | unsigned int cpu; |
3af24433 | 3345 | |
9c5a2ba7 TH |
3346 | /* drain it before proceeding with destruction */ |
3347 | drain_workqueue(wq); | |
c8efcc25 | 3348 | |
a0a1a5fd TH |
3349 | /* |
3350 | * wq list is used to freeze wq, remove from list after | |
3351 | * flushing is complete in case freeze races us. | |
3352 | */ | |
95402b38 | 3353 | spin_lock(&workqueue_lock); |
b1f4ec17 | 3354 | list_del(&wq->list); |
95402b38 | 3355 | spin_unlock(&workqueue_lock); |
3af24433 | 3356 | |
e22bee78 | 3357 | /* sanity check */ |
f3421797 | 3358 | for_each_cwq_cpu(cpu, wq) { |
73f53c4a TH |
3359 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3360 | int i; | |
3361 | ||
73f53c4a TH |
3362 | for (i = 0; i < WORK_NR_COLORS; i++) |
3363 | BUG_ON(cwq->nr_in_flight[i]); | |
1e19ffc6 TH |
3364 | BUG_ON(cwq->nr_active); |
3365 | BUG_ON(!list_empty(&cwq->delayed_works)); | |
73f53c4a | 3366 | } |
9b41ea72 | 3367 | |
e22bee78 TH |
3368 | if (wq->flags & WQ_RESCUER) { |
3369 | kthread_stop(wq->rescuer->task); | |
f2e005aa | 3370 | free_mayday_mask(wq->mayday_mask); |
8d9df9f0 | 3371 | kfree(wq->rescuer); |
e22bee78 TH |
3372 | } |
3373 | ||
bdbc5dd7 | 3374 | free_cwqs(wq); |
3af24433 ON |
3375 | kfree(wq); |
3376 | } | |
3377 | EXPORT_SYMBOL_GPL(destroy_workqueue); | |
3378 | ||
9f4bd4cd LJ |
3379 | /** |
3380 | * cwq_set_max_active - adjust max_active of a cwq | |
3381 | * @cwq: target cpu_workqueue_struct | |
3382 | * @max_active: new max_active value. | |
3383 | * | |
3384 | * Set @cwq->max_active to @max_active and activate delayed works if | |
3385 | * increased. | |
3386 | * | |
3387 | * CONTEXT: | |
3388 | * spin_lock_irq(gcwq->lock). | |
3389 | */ | |
3390 | static void cwq_set_max_active(struct cpu_workqueue_struct *cwq, int max_active) | |
3391 | { | |
3392 | cwq->max_active = max_active; | |
3393 | ||
3394 | while (!list_empty(&cwq->delayed_works) && | |
3395 | cwq->nr_active < cwq->max_active) | |
3396 | cwq_activate_first_delayed(cwq); | |
3397 | } | |
3398 | ||
dcd989cb TH |
3399 | /** |
3400 | * workqueue_set_max_active - adjust max_active of a workqueue | |
3401 | * @wq: target workqueue | |
3402 | * @max_active: new max_active value. | |
3403 | * | |
3404 | * Set max_active of @wq to @max_active. | |
3405 | * | |
3406 | * CONTEXT: | |
3407 | * Don't call from IRQ context. | |
3408 | */ | |
3409 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) | |
3410 | { | |
3411 | unsigned int cpu; | |
3412 | ||
f3421797 | 3413 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
dcd989cb TH |
3414 | |
3415 | spin_lock(&workqueue_lock); | |
3416 | ||
3417 | wq->saved_max_active = max_active; | |
3418 | ||
f3421797 | 3419 | for_each_cwq_cpu(cpu, wq) { |
dcd989cb TH |
3420 | struct global_cwq *gcwq = get_gcwq(cpu); |
3421 | ||
3422 | spin_lock_irq(&gcwq->lock); | |
3423 | ||
58a69cb4 | 3424 | if (!(wq->flags & WQ_FREEZABLE) || |
dcd989cb | 3425 | !(gcwq->flags & GCWQ_FREEZING)) |
70369b11 | 3426 | cwq_set_max_active(get_cwq(gcwq->cpu, wq), max_active); |
9bfb1839 | 3427 | |
dcd989cb | 3428 | spin_unlock_irq(&gcwq->lock); |
65a64464 | 3429 | } |
93981800 | 3430 | |
dcd989cb | 3431 | spin_unlock(&workqueue_lock); |
15316ba8 | 3432 | } |
dcd989cb | 3433 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
15316ba8 | 3434 | |
eef6a7d5 | 3435 | /** |
dcd989cb TH |
3436 | * workqueue_congested - test whether a workqueue is congested |
3437 | * @cpu: CPU in question | |
3438 | * @wq: target workqueue | |
eef6a7d5 | 3439 | * |
dcd989cb TH |
3440 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
3441 | * no synchronization around this function and the test result is | |
3442 | * unreliable and only useful as advisory hints or for debugging. | |
eef6a7d5 | 3443 | * |
dcd989cb TH |
3444 | * RETURNS: |
3445 | * %true if congested, %false otherwise. | |
eef6a7d5 | 3446 | */ |
dcd989cb | 3447 | bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) |
1da177e4 | 3448 | { |
dcd989cb TH |
3449 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3450 | ||
3451 | return !list_empty(&cwq->delayed_works); | |
1da177e4 | 3452 | } |
dcd989cb | 3453 | EXPORT_SYMBOL_GPL(workqueue_congested); |
1da177e4 | 3454 | |
1fa44eca | 3455 | /** |
dcd989cb TH |
3456 | * work_cpu - return the last known associated cpu for @work |
3457 | * @work: the work of interest | |
1fa44eca | 3458 | * |
dcd989cb | 3459 | * RETURNS: |
bdbc5dd7 | 3460 | * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. |
1fa44eca | 3461 | */ |
dcd989cb | 3462 | unsigned int work_cpu(struct work_struct *work) |
1fa44eca | 3463 | { |
dcd989cb | 3464 | struct global_cwq *gcwq = get_work_gcwq(work); |
1fa44eca | 3465 | |
bdbc5dd7 | 3466 | return gcwq ? gcwq->cpu : WORK_CPU_NONE; |
1fa44eca | 3467 | } |
dcd989cb | 3468 | EXPORT_SYMBOL_GPL(work_cpu); |
1fa44eca | 3469 | |
dcd989cb TH |
3470 | /** |
3471 | * work_busy - test whether a work is currently pending or running | |
3472 | * @work: the work to be tested | |
3473 | * | |
3474 | * Test whether @work is currently pending or running. There is no | |
3475 | * synchronization around this function and the test result is | |
3476 | * unreliable and only useful as advisory hints or for debugging. | |
3477 | * Especially for reentrant wqs, the pending state might hide the | |
3478 | * running state. | |
3479 | * | |
3480 | * RETURNS: | |
3481 | * OR'd bitmask of WORK_BUSY_* bits. | |
3482 | */ | |
3483 | unsigned int work_busy(struct work_struct *work) | |
1da177e4 | 3484 | { |
dcd989cb TH |
3485 | struct global_cwq *gcwq = get_work_gcwq(work); |
3486 | unsigned long flags; | |
3487 | unsigned int ret = 0; | |
1da177e4 | 3488 | |
dcd989cb | 3489 | if (!gcwq) |
999767be | 3490 | return 0; |
1da177e4 | 3491 | |
dcd989cb | 3492 | spin_lock_irqsave(&gcwq->lock, flags); |
1da177e4 | 3493 | |
dcd989cb TH |
3494 | if (work_pending(work)) |
3495 | ret |= WORK_BUSY_PENDING; | |
3496 | if (find_worker_executing_work(gcwq, work)) | |
3497 | ret |= WORK_BUSY_RUNNING; | |
1da177e4 | 3498 | |
dcd989cb | 3499 | spin_unlock_irqrestore(&gcwq->lock, flags); |
1da177e4 | 3500 | |
dcd989cb | 3501 | return ret; |
1da177e4 | 3502 | } |
dcd989cb | 3503 | EXPORT_SYMBOL_GPL(work_busy); |
1da177e4 | 3504 | |
db7bccf4 TH |
3505 | /* |
3506 | * CPU hotplug. | |
3507 | * | |
e22bee78 TH |
3508 | * There are two challenges in supporting CPU hotplug. Firstly, there |
3509 | * are a lot of assumptions on strong associations among work, cwq and | |
3510 | * gcwq which make migrating pending and scheduled works very | |
3511 | * difficult to implement without impacting hot paths. Secondly, | |
3512 | * gcwqs serve mix of short, long and very long running works making | |
3513 | * blocked draining impractical. | |
3514 | * | |
628c78e7 TH |
3515 | * This is solved by allowing a gcwq to be disassociated from the CPU |
3516 | * running as an unbound one and allowing it to be reattached later if the | |
3517 | * cpu comes back online. | |
db7bccf4 | 3518 | */ |
1da177e4 | 3519 | |
60373152 | 3520 | /* claim manager positions of all pools */ |
b2eb83d1 | 3521 | static void gcwq_claim_assoc_and_lock(struct global_cwq *gcwq) |
60373152 TH |
3522 | { |
3523 | struct worker_pool *pool; | |
3524 | ||
3525 | for_each_worker_pool(pool, gcwq) | |
b2eb83d1 | 3526 | mutex_lock_nested(&pool->assoc_mutex, pool - gcwq->pools); |
8db25e78 | 3527 | spin_lock_irq(&gcwq->lock); |
60373152 TH |
3528 | } |
3529 | ||
3530 | /* release manager positions */ | |
b2eb83d1 | 3531 | static void gcwq_release_assoc_and_unlock(struct global_cwq *gcwq) |
60373152 TH |
3532 | { |
3533 | struct worker_pool *pool; | |
3534 | ||
8db25e78 | 3535 | spin_unlock_irq(&gcwq->lock); |
60373152 | 3536 | for_each_worker_pool(pool, gcwq) |
b2eb83d1 | 3537 | mutex_unlock(&pool->assoc_mutex); |
60373152 TH |
3538 | } |
3539 | ||
628c78e7 | 3540 | static void gcwq_unbind_fn(struct work_struct *work) |
3af24433 | 3541 | { |
628c78e7 | 3542 | struct global_cwq *gcwq = get_gcwq(smp_processor_id()); |
4ce62e9e | 3543 | struct worker_pool *pool; |
db7bccf4 TH |
3544 | struct worker *worker; |
3545 | struct hlist_node *pos; | |
3546 | int i; | |
3af24433 | 3547 | |
db7bccf4 TH |
3548 | BUG_ON(gcwq->cpu != smp_processor_id()); |
3549 | ||
b2eb83d1 | 3550 | gcwq_claim_assoc_and_lock(gcwq); |
3af24433 | 3551 | |
f2d5a0ee TH |
3552 | /* |
3553 | * We've claimed all manager positions. Make all workers unbound | |
3554 | * and set DISASSOCIATED. Before this, all workers except for the | |
3555 | * ones which are still executing works from before the last CPU | |
3556 | * down must be on the cpu. After this, they may become diasporas. | |
3557 | */ | |
60373152 | 3558 | for_each_worker_pool(pool, gcwq) |
4ce62e9e | 3559 | list_for_each_entry(worker, &pool->idle_list, entry) |
403c821d | 3560 | worker->flags |= WORKER_UNBOUND; |
3af24433 | 3561 | |
db7bccf4 | 3562 | for_each_busy_worker(worker, i, pos, gcwq) |
403c821d | 3563 | worker->flags |= WORKER_UNBOUND; |
06ba38a9 | 3564 | |
f2d5a0ee TH |
3565 | gcwq->flags |= GCWQ_DISASSOCIATED; |
3566 | ||
b2eb83d1 | 3567 | gcwq_release_assoc_and_unlock(gcwq); |
628c78e7 | 3568 | |
e22bee78 | 3569 | /* |
403c821d | 3570 | * Call schedule() so that we cross rq->lock and thus can guarantee |
628c78e7 TH |
3571 | * sched callbacks see the %WORKER_UNBOUND flag. This is necessary |
3572 | * as scheduler callbacks may be invoked from other cpus. | |
e22bee78 | 3573 | */ |
e22bee78 | 3574 | schedule(); |
06ba38a9 | 3575 | |
e22bee78 | 3576 | /* |
628c78e7 TH |
3577 | * Sched callbacks are disabled now. Zap nr_running. After this, |
3578 | * nr_running stays zero and need_more_worker() and keep_working() | |
3579 | * are always true as long as the worklist is not empty. @gcwq now | |
3580 | * behaves as unbound (in terms of concurrency management) gcwq | |
3581 | * which is served by workers tied to the CPU. | |
3582 | * | |
3583 | * On return from this function, the current worker would trigger | |
3584 | * unbound chain execution of pending work items if other workers | |
3585 | * didn't already. | |
e22bee78 | 3586 | */ |
4ce62e9e TH |
3587 | for_each_worker_pool(pool, gcwq) |
3588 | atomic_set(get_pool_nr_running(pool), 0); | |
3af24433 | 3589 | } |
3af24433 | 3590 | |
8db25e78 TH |
3591 | /* |
3592 | * Workqueues should be brought up before normal priority CPU notifiers. | |
3593 | * This will be registered high priority CPU notifier. | |
3594 | */ | |
9fdf9b73 | 3595 | static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb, |
8db25e78 TH |
3596 | unsigned long action, |
3597 | void *hcpu) | |
3af24433 ON |
3598 | { |
3599 | unsigned int cpu = (unsigned long)hcpu; | |
db7bccf4 | 3600 | struct global_cwq *gcwq = get_gcwq(cpu); |
4ce62e9e | 3601 | struct worker_pool *pool; |
3ce63377 | 3602 | |
8db25e78 | 3603 | switch (action & ~CPU_TASKS_FROZEN) { |
3af24433 | 3604 | case CPU_UP_PREPARE: |
4ce62e9e | 3605 | for_each_worker_pool(pool, gcwq) { |
3ce63377 TH |
3606 | struct worker *worker; |
3607 | ||
3608 | if (pool->nr_workers) | |
3609 | continue; | |
3610 | ||
3611 | worker = create_worker(pool); | |
3612 | if (!worker) | |
3613 | return NOTIFY_BAD; | |
3614 | ||
3615 | spin_lock_irq(&gcwq->lock); | |
3616 | start_worker(worker); | |
3617 | spin_unlock_irq(&gcwq->lock); | |
3af24433 | 3618 | } |
8db25e78 | 3619 | break; |
3af24433 | 3620 | |
db7bccf4 TH |
3621 | case CPU_DOWN_FAILED: |
3622 | case CPU_ONLINE: | |
b2eb83d1 | 3623 | gcwq_claim_assoc_and_lock(gcwq); |
bc2ae0f5 | 3624 | gcwq->flags &= ~GCWQ_DISASSOCIATED; |
25511a47 | 3625 | rebind_workers(gcwq); |
b2eb83d1 | 3626 | gcwq_release_assoc_and_unlock(gcwq); |
db7bccf4 | 3627 | break; |
00dfcaf7 | 3628 | } |
65758202 TH |
3629 | return NOTIFY_OK; |
3630 | } | |
3631 | ||
3632 | /* | |
3633 | * Workqueues should be brought down after normal priority CPU notifiers. | |
3634 | * This will be registered as low priority CPU notifier. | |
3635 | */ | |
9fdf9b73 | 3636 | static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb, |
65758202 TH |
3637 | unsigned long action, |
3638 | void *hcpu) | |
3639 | { | |
8db25e78 TH |
3640 | unsigned int cpu = (unsigned long)hcpu; |
3641 | struct work_struct unbind_work; | |
3642 | ||
65758202 TH |
3643 | switch (action & ~CPU_TASKS_FROZEN) { |
3644 | case CPU_DOWN_PREPARE: | |
8db25e78 TH |
3645 | /* unbinding should happen on the local CPU */ |
3646 | INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn); | |
7635d2fd | 3647 | queue_work_on(cpu, system_highpri_wq, &unbind_work); |
8db25e78 TH |
3648 | flush_work(&unbind_work); |
3649 | break; | |
65758202 TH |
3650 | } |
3651 | return NOTIFY_OK; | |
3652 | } | |
3653 | ||
2d3854a3 | 3654 | #ifdef CONFIG_SMP |
8ccad40d | 3655 | |
2d3854a3 | 3656 | struct work_for_cpu { |
ed48ece2 | 3657 | struct work_struct work; |
2d3854a3 RR |
3658 | long (*fn)(void *); |
3659 | void *arg; | |
3660 | long ret; | |
3661 | }; | |
3662 | ||
ed48ece2 | 3663 | static void work_for_cpu_fn(struct work_struct *work) |
2d3854a3 | 3664 | { |
ed48ece2 TH |
3665 | struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); |
3666 | ||
2d3854a3 RR |
3667 | wfc->ret = wfc->fn(wfc->arg); |
3668 | } | |
3669 | ||
3670 | /** | |
3671 | * work_on_cpu - run a function in user context on a particular cpu | |
3672 | * @cpu: the cpu to run on | |
3673 | * @fn: the function to run | |
3674 | * @arg: the function arg | |
3675 | * | |
31ad9081 RR |
3676 | * This will return the value @fn returns. |
3677 | * It is up to the caller to ensure that the cpu doesn't go offline. | |
6b44003e | 3678 | * The caller must not hold any locks which would prevent @fn from completing. |
2d3854a3 RR |
3679 | */ |
3680 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) | |
3681 | { | |
ed48ece2 | 3682 | struct work_for_cpu wfc = { .fn = fn, .arg = arg }; |
6b44003e | 3683 | |
ed48ece2 TH |
3684 | INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); |
3685 | schedule_work_on(cpu, &wfc.work); | |
3686 | flush_work(&wfc.work); | |
2d3854a3 RR |
3687 | return wfc.ret; |
3688 | } | |
3689 | EXPORT_SYMBOL_GPL(work_on_cpu); | |
3690 | #endif /* CONFIG_SMP */ | |
3691 | ||
a0a1a5fd TH |
3692 | #ifdef CONFIG_FREEZER |
3693 | ||
3694 | /** | |
3695 | * freeze_workqueues_begin - begin freezing workqueues | |
3696 | * | |
58a69cb4 TH |
3697 | * Start freezing workqueues. After this function returns, all freezable |
3698 | * workqueues will queue new works to their frozen_works list instead of | |
3699 | * gcwq->worklist. | |
a0a1a5fd TH |
3700 | * |
3701 | * CONTEXT: | |
8b03ae3c | 3702 | * Grabs and releases workqueue_lock and gcwq->lock's. |
a0a1a5fd TH |
3703 | */ |
3704 | void freeze_workqueues_begin(void) | |
3705 | { | |
a0a1a5fd TH |
3706 | unsigned int cpu; |
3707 | ||
3708 | spin_lock(&workqueue_lock); | |
3709 | ||
3710 | BUG_ON(workqueue_freezing); | |
3711 | workqueue_freezing = true; | |
3712 | ||
f3421797 | 3713 | for_each_gcwq_cpu(cpu) { |
8b03ae3c | 3714 | struct global_cwq *gcwq = get_gcwq(cpu); |
bdbc5dd7 | 3715 | struct workqueue_struct *wq; |
8b03ae3c TH |
3716 | |
3717 | spin_lock_irq(&gcwq->lock); | |
3718 | ||
db7bccf4 TH |
3719 | BUG_ON(gcwq->flags & GCWQ_FREEZING); |
3720 | gcwq->flags |= GCWQ_FREEZING; | |
3721 | ||
a0a1a5fd TH |
3722 | list_for_each_entry(wq, &workqueues, list) { |
3723 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
3724 | ||
58a69cb4 | 3725 | if (cwq && wq->flags & WQ_FREEZABLE) |
a0a1a5fd | 3726 | cwq->max_active = 0; |
a0a1a5fd | 3727 | } |
8b03ae3c TH |
3728 | |
3729 | spin_unlock_irq(&gcwq->lock); | |
a0a1a5fd TH |
3730 | } |
3731 | ||
3732 | spin_unlock(&workqueue_lock); | |
3733 | } | |
3734 | ||
3735 | /** | |
58a69cb4 | 3736 | * freeze_workqueues_busy - are freezable workqueues still busy? |
a0a1a5fd TH |
3737 | * |
3738 | * Check whether freezing is complete. This function must be called | |
3739 | * between freeze_workqueues_begin() and thaw_workqueues(). | |
3740 | * | |
3741 | * CONTEXT: | |
3742 | * Grabs and releases workqueue_lock. | |
3743 | * | |
3744 | * RETURNS: | |
58a69cb4 TH |
3745 | * %true if some freezable workqueues are still busy. %false if freezing |
3746 | * is complete. | |
a0a1a5fd TH |
3747 | */ |
3748 | bool freeze_workqueues_busy(void) | |
3749 | { | |
a0a1a5fd TH |
3750 | unsigned int cpu; |
3751 | bool busy = false; | |
3752 | ||
3753 | spin_lock(&workqueue_lock); | |
3754 | ||
3755 | BUG_ON(!workqueue_freezing); | |
3756 | ||
f3421797 | 3757 | for_each_gcwq_cpu(cpu) { |
bdbc5dd7 | 3758 | struct workqueue_struct *wq; |
a0a1a5fd TH |
3759 | /* |
3760 | * nr_active is monotonically decreasing. It's safe | |
3761 | * to peek without lock. | |
3762 | */ | |
3763 | list_for_each_entry(wq, &workqueues, list) { | |
3764 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
3765 | ||
58a69cb4 | 3766 | if (!cwq || !(wq->flags & WQ_FREEZABLE)) |
a0a1a5fd TH |
3767 | continue; |
3768 | ||
3769 | BUG_ON(cwq->nr_active < 0); | |
3770 | if (cwq->nr_active) { | |
3771 | busy = true; | |
3772 | goto out_unlock; | |
3773 | } | |
3774 | } | |
3775 | } | |
3776 | out_unlock: | |
3777 | spin_unlock(&workqueue_lock); | |
3778 | return busy; | |
3779 | } | |
3780 | ||
3781 | /** | |
3782 | * thaw_workqueues - thaw workqueues | |
3783 | * | |
3784 | * Thaw workqueues. Normal queueing is restored and all collected | |
7e11629d | 3785 | * frozen works are transferred to their respective gcwq worklists. |
a0a1a5fd TH |
3786 | * |
3787 | * CONTEXT: | |
8b03ae3c | 3788 | * Grabs and releases workqueue_lock and gcwq->lock's. |
a0a1a5fd TH |
3789 | */ |
3790 | void thaw_workqueues(void) | |
3791 | { | |
a0a1a5fd TH |
3792 | unsigned int cpu; |
3793 | ||
3794 | spin_lock(&workqueue_lock); | |
3795 | ||
3796 | if (!workqueue_freezing) | |
3797 | goto out_unlock; | |
3798 | ||
f3421797 | 3799 | for_each_gcwq_cpu(cpu) { |
8b03ae3c | 3800 | struct global_cwq *gcwq = get_gcwq(cpu); |
4ce62e9e | 3801 | struct worker_pool *pool; |
bdbc5dd7 | 3802 | struct workqueue_struct *wq; |
8b03ae3c TH |
3803 | |
3804 | spin_lock_irq(&gcwq->lock); | |
3805 | ||
db7bccf4 TH |
3806 | BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); |
3807 | gcwq->flags &= ~GCWQ_FREEZING; | |
3808 | ||
a0a1a5fd TH |
3809 | list_for_each_entry(wq, &workqueues, list) { |
3810 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
3811 | ||
58a69cb4 | 3812 | if (!cwq || !(wq->flags & WQ_FREEZABLE)) |
a0a1a5fd TH |
3813 | continue; |
3814 | ||
a0a1a5fd | 3815 | /* restore max_active and repopulate worklist */ |
9f4bd4cd | 3816 | cwq_set_max_active(cwq, wq->saved_max_active); |
a0a1a5fd | 3817 | } |
8b03ae3c | 3818 | |
4ce62e9e TH |
3819 | for_each_worker_pool(pool, gcwq) |
3820 | wake_up_worker(pool); | |
e22bee78 | 3821 | |
8b03ae3c | 3822 | spin_unlock_irq(&gcwq->lock); |
a0a1a5fd TH |
3823 | } |
3824 | ||
3825 | workqueue_freezing = false; | |
3826 | out_unlock: | |
3827 | spin_unlock(&workqueue_lock); | |
3828 | } | |
3829 | #endif /* CONFIG_FREEZER */ | |
3830 | ||
6ee0578b | 3831 | static int __init init_workqueues(void) |
1da177e4 | 3832 | { |
c34056a3 | 3833 | unsigned int cpu; |
c8e55f36 | 3834 | int i; |
c34056a3 | 3835 | |
b5490077 TH |
3836 | /* make sure we have enough bits for OFFQ CPU number */ |
3837 | BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_CPU_SHIFT)) < | |
3838 | WORK_CPU_LAST); | |
3839 | ||
65758202 | 3840 | cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); |
a5b4e57d | 3841 | hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); |
8b03ae3c TH |
3842 | |
3843 | /* initialize gcwqs */ | |
f3421797 | 3844 | for_each_gcwq_cpu(cpu) { |
8b03ae3c | 3845 | struct global_cwq *gcwq = get_gcwq(cpu); |
4ce62e9e | 3846 | struct worker_pool *pool; |
8b03ae3c TH |
3847 | |
3848 | spin_lock_init(&gcwq->lock); | |
3849 | gcwq->cpu = cpu; | |
477a3c33 | 3850 | gcwq->flags |= GCWQ_DISASSOCIATED; |
8b03ae3c | 3851 | |
c8e55f36 TH |
3852 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) |
3853 | INIT_HLIST_HEAD(&gcwq->busy_hash[i]); | |
3854 | ||
4ce62e9e TH |
3855 | for_each_worker_pool(pool, gcwq) { |
3856 | pool->gcwq = gcwq; | |
3857 | INIT_LIST_HEAD(&pool->worklist); | |
3858 | INIT_LIST_HEAD(&pool->idle_list); | |
e7577c50 | 3859 | |
4ce62e9e TH |
3860 | init_timer_deferrable(&pool->idle_timer); |
3861 | pool->idle_timer.function = idle_worker_timeout; | |
3862 | pool->idle_timer.data = (unsigned long)pool; | |
e22bee78 | 3863 | |
4ce62e9e TH |
3864 | setup_timer(&pool->mayday_timer, gcwq_mayday_timeout, |
3865 | (unsigned long)pool); | |
3866 | ||
b2eb83d1 | 3867 | mutex_init(&pool->assoc_mutex); |
4ce62e9e TH |
3868 | ida_init(&pool->worker_ida); |
3869 | } | |
8b03ae3c TH |
3870 | } |
3871 | ||
e22bee78 | 3872 | /* create the initial worker */ |
f3421797 | 3873 | for_each_online_gcwq_cpu(cpu) { |
e22bee78 | 3874 | struct global_cwq *gcwq = get_gcwq(cpu); |
4ce62e9e | 3875 | struct worker_pool *pool; |
e22bee78 | 3876 | |
477a3c33 TH |
3877 | if (cpu != WORK_CPU_UNBOUND) |
3878 | gcwq->flags &= ~GCWQ_DISASSOCIATED; | |
4ce62e9e TH |
3879 | |
3880 | for_each_worker_pool(pool, gcwq) { | |
3881 | struct worker *worker; | |
3882 | ||
bc2ae0f5 | 3883 | worker = create_worker(pool); |
4ce62e9e TH |
3884 | BUG_ON(!worker); |
3885 | spin_lock_irq(&gcwq->lock); | |
3886 | start_worker(worker); | |
3887 | spin_unlock_irq(&gcwq->lock); | |
3888 | } | |
e22bee78 TH |
3889 | } |
3890 | ||
d320c038 | 3891 | system_wq = alloc_workqueue("events", 0, 0); |
1aabe902 | 3892 | system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); |
d320c038 | 3893 | system_long_wq = alloc_workqueue("events_long", 0, 0); |
f3421797 TH |
3894 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
3895 | WQ_UNBOUND_MAX_ACTIVE); | |
24d51add TH |
3896 | system_freezable_wq = alloc_workqueue("events_freezable", |
3897 | WQ_FREEZABLE, 0); | |
1aabe902 | 3898 | BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || |
ae930e0f | 3899 | !system_unbound_wq || !system_freezable_wq); |
6ee0578b | 3900 | return 0; |
1da177e4 | 3901 | } |
6ee0578b | 3902 | early_initcall(init_workqueues); |