Root/
1 | /* |
2 | * kernel/workqueue.c - generic async execution with shared worker pool |
3 | * |
4 | * Copyright (C) 2002 Ingo Molnar |
5 | * |
6 | * Derived from the taskqueue/keventd code by: |
7 | * David Woodhouse <dwmw2@infradead.org> |
8 | * Andrew Morton |
9 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
10 | * Theodore Ts'o <tytso@mit.edu> |
11 | * |
12 | * Made to use alloc_percpu by Christoph Lameter. |
13 | * |
14 | * Copyright (C) 2010 SUSE Linux Products GmbH |
15 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> |
16 | * |
17 | * This is the generic async execution mechanism. Work items as are |
18 | * executed in process context. The worker pool is shared and |
19 | * automatically managed. There is one worker pool for each CPU and |
20 | * one extra for works which are better served by workers which are |
21 | * not bound to any specific CPU. |
22 | * |
23 | * Please read Documentation/workqueue.txt for details. |
24 | */ |
25 | |
26 | #include <linux/module.h> |
27 | #include <linux/kernel.h> |
28 | #include <linux/sched.h> |
29 | #include <linux/init.h> |
30 | #include <linux/signal.h> |
31 | #include <linux/completion.h> |
32 | #include <linux/workqueue.h> |
33 | #include <linux/slab.h> |
34 | #include <linux/cpu.h> |
35 | #include <linux/notifier.h> |
36 | #include <linux/kthread.h> |
37 | #include <linux/hardirq.h> |
38 | #include <linux/mempolicy.h> |
39 | #include <linux/freezer.h> |
40 | #include <linux/kallsyms.h> |
41 | #include <linux/debug_locks.h> |
42 | #include <linux/lockdep.h> |
43 | #include <linux/idr.h> |
44 | |
45 | #include "workqueue_sched.h" |
46 | |
47 | enum { |
48 | /* global_cwq flags */ |
49 | GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ |
50 | GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */ |
51 | GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
52 | GCWQ_FREEZING = 1 << 3, /* freeze in progress */ |
53 | GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */ |
54 | |
55 | /* worker flags */ |
56 | WORKER_STARTED = 1 << 0, /* started */ |
57 | WORKER_DIE = 1 << 1, /* die die die */ |
58 | WORKER_IDLE = 1 << 2, /* is idle */ |
59 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
60 | WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ |
61 | WORKER_REBIND = 1 << 5, /* mom is home, come back */ |
62 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
63 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
64 | |
65 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | |
66 | WORKER_CPU_INTENSIVE | WORKER_UNBOUND, |
67 | |
68 | /* gcwq->trustee_state */ |
69 | TRUSTEE_START = 0, /* start */ |
70 | TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ |
71 | TRUSTEE_BUTCHER = 2, /* butcher workers */ |
72 | TRUSTEE_RELEASE = 3, /* release workers */ |
73 | TRUSTEE_DONE = 4, /* trustee is done */ |
74 | |
75 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
76 | BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, |
77 | BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, |
78 | |
79 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
80 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
81 | |
82 | MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */ |
83 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
84 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
85 | TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ |
86 | |
87 | /* |
88 | * Rescue workers are used only on emergencies and shared by |
89 | * all cpus. Give -20. |
90 | */ |
91 | RESCUER_NICE_LEVEL = -20, |
92 | }; |
93 | |
94 | /* |
95 | * Structure fields follow one of the following exclusion rules. |
96 | * |
97 | * I: Modifiable by initialization/destruction paths and read-only for |
98 | * everyone else. |
99 | * |
100 | * P: Preemption protected. Disabling preemption is enough and should |
101 | * only be modified and accessed from the local cpu. |
102 | * |
103 | * L: gcwq->lock protected. Access with gcwq->lock held. |
104 | * |
105 | * X: During normal operation, modification requires gcwq->lock and |
106 | * should be done only from local cpu. Either disabling preemption |
107 | * on local cpu or grabbing gcwq->lock is enough for read access. |
108 | * If GCWQ_DISASSOCIATED is set, it's identical to L. |
109 | * |
110 | * F: wq->flush_mutex protected. |
111 | * |
112 | * W: workqueue_lock protected. |
113 | */ |
114 | |
115 | struct global_cwq; |
116 | |
117 | /* |
118 | * The poor guys doing the actual heavy lifting. All on-duty workers |
119 | * are either serving the manager role, on idle list or on busy hash. |
120 | */ |
121 | struct worker { |
122 | /* on idle list while idle, on busy hash table while busy */ |
123 | union { |
124 | struct list_head entry; /* L: while idle */ |
125 | struct hlist_node hentry; /* L: while busy */ |
126 | }; |
127 | |
128 | struct work_struct *current_work; /* L: work being processed */ |
129 | struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ |
130 | struct list_head scheduled; /* L: scheduled works */ |
131 | struct task_struct *task; /* I: worker task */ |
132 | struct global_cwq *gcwq; /* I: the associated gcwq */ |
133 | /* 64 bytes boundary on 64bit, 32 on 32bit */ |
134 | unsigned long last_active; /* L: last active timestamp */ |
135 | unsigned int flags; /* X: flags */ |
136 | int id; /* I: worker id */ |
137 | struct work_struct rebind_work; /* L: rebind worker to cpu */ |
138 | }; |
139 | |
140 | /* |
141 | * Global per-cpu workqueue. There's one and only one for each cpu |
142 | * and all works are queued and processed here regardless of their |
143 | * target workqueues. |
144 | */ |
145 | struct global_cwq { |
146 | spinlock_t lock; /* the gcwq lock */ |
147 | struct list_head worklist; /* L: list of pending works */ |
148 | unsigned int cpu; /* I: the associated cpu */ |
149 | unsigned int flags; /* L: GCWQ_* flags */ |
150 | |
151 | int nr_workers; /* L: total number of workers */ |
152 | int nr_idle; /* L: currently idle ones */ |
153 | |
154 | /* workers are chained either in the idle_list or busy_hash */ |
155 | struct list_head idle_list; /* X: list of idle workers */ |
156 | struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; |
157 | /* L: hash of busy workers */ |
158 | |
159 | struct timer_list idle_timer; /* L: worker idle timeout */ |
160 | struct timer_list mayday_timer; /* L: SOS timer for dworkers */ |
161 | |
162 | struct ida worker_ida; /* L: for worker IDs */ |
163 | |
164 | struct task_struct *trustee; /* L: for gcwq shutdown */ |
165 | unsigned int trustee_state; /* L: trustee state */ |
166 | wait_queue_head_t trustee_wait; /* trustee wait */ |
167 | struct worker *first_idle; /* L: first idle worker */ |
168 | } ____cacheline_aligned_in_smp; |
169 | |
170 | /* |
171 | * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of |
172 | * work_struct->data are used for flags and thus cwqs need to be |
173 | * aligned at two's power of the number of flag bits. |
174 | */ |
175 | struct cpu_workqueue_struct { |
176 | struct global_cwq *gcwq; /* I: the associated gcwq */ |
177 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
178 | int work_color; /* L: current color */ |
179 | int flush_color; /* L: flushing color */ |
180 | int nr_in_flight[WORK_NR_COLORS]; |
181 | /* L: nr of in_flight works */ |
182 | int nr_active; /* L: nr of active works */ |
183 | int max_active; /* L: max active works */ |
184 | struct list_head delayed_works; /* L: delayed works */ |
185 | }; |
186 | |
187 | /* |
188 | * Structure used to wait for workqueue flush. |
189 | */ |
190 | struct wq_flusher { |
191 | struct list_head list; /* F: list of flushers */ |
192 | int flush_color; /* F: flush color waiting for */ |
193 | struct completion done; /* flush completion */ |
194 | }; |
195 | |
196 | /* |
197 | * All cpumasks are assumed to be always set on UP and thus can't be |
198 | * used to determine whether there's something to be done. |
199 | */ |
200 | #ifdef CONFIG_SMP |
201 | typedef cpumask_var_t mayday_mask_t; |
202 | #define mayday_test_and_set_cpu(cpu, mask) \ |
203 | cpumask_test_and_set_cpu((cpu), (mask)) |
204 | #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) |
205 | #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) |
206 | #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) |
207 | #define free_mayday_mask(mask) free_cpumask_var((mask)) |
208 | #else |
209 | typedef unsigned long mayday_mask_t; |
210 | #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) |
211 | #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) |
212 | #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) |
213 | #define alloc_mayday_mask(maskp, gfp) true |
214 | #define free_mayday_mask(mask) do { } while (0) |
215 | #endif |
216 | |
217 | /* |
218 | * The externally visible workqueue abstraction is an array of |
219 | * per-CPU workqueues: |
220 | */ |
221 | struct workqueue_struct { |
222 | unsigned int flags; /* I: WQ_* flags */ |
223 | union { |
224 | struct cpu_workqueue_struct __percpu *pcpu; |
225 | struct cpu_workqueue_struct *single; |
226 | unsigned long v; |
227 | } cpu_wq; /* I: cwq's */ |
228 | struct list_head list; /* W: list of all workqueues */ |
229 | |
230 | struct mutex flush_mutex; /* protects wq flushing */ |
231 | int work_color; /* F: current work color */ |
232 | int flush_color; /* F: current flush color */ |
233 | atomic_t nr_cwqs_to_flush; /* flush in progress */ |
234 | struct wq_flusher *first_flusher; /* F: first flusher */ |
235 | struct list_head flusher_queue; /* F: flush waiters */ |
236 | struct list_head flusher_overflow; /* F: flush overflow list */ |
237 | |
238 | mayday_mask_t mayday_mask; /* cpus requesting rescue */ |
239 | struct worker *rescuer; /* I: rescue worker */ |
240 | |
241 | int saved_max_active; /* W: saved cwq max_active */ |
242 | const char *name; /* I: workqueue name */ |
243 | #ifdef CONFIG_LOCKDEP |
244 | struct lockdep_map lockdep_map; |
245 | #endif |
246 | }; |
247 | |
248 | struct workqueue_struct *system_wq __read_mostly; |
249 | struct workqueue_struct *system_long_wq __read_mostly; |
250 | struct workqueue_struct *system_nrt_wq __read_mostly; |
251 | struct workqueue_struct *system_unbound_wq __read_mostly; |
252 | EXPORT_SYMBOL_GPL(system_wq); |
253 | EXPORT_SYMBOL_GPL(system_long_wq); |
254 | EXPORT_SYMBOL_GPL(system_nrt_wq); |
255 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
256 | |
257 | #define CREATE_TRACE_POINTS |
258 | #include <trace/events/workqueue.h> |
259 | |
260 | #define for_each_busy_worker(worker, i, pos, gcwq) \ |
261 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ |
262 | hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) |
263 | |
264 | static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, |
265 | unsigned int sw) |
266 | { |
267 | if (cpu < nr_cpu_ids) { |
268 | if (sw & 1) { |
269 | cpu = cpumask_next(cpu, mask); |
270 | if (cpu < nr_cpu_ids) |
271 | return cpu; |
272 | } |
273 | if (sw & 2) |
274 | return WORK_CPU_UNBOUND; |
275 | } |
276 | return WORK_CPU_NONE; |
277 | } |
278 | |
279 | static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, |
280 | struct workqueue_struct *wq) |
281 | { |
282 | return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); |
283 | } |
284 | |
285 | /* |
286 | * CPU iterators |
287 | * |
288 | * An extra gcwq is defined for an invalid cpu number |
289 | * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any |
290 | * specific CPU. The following iterators are similar to |
291 | * for_each_*_cpu() iterators but also considers the unbound gcwq. |
292 | * |
293 | * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND |
294 | * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND |
295 | * for_each_cwq_cpu() : possible CPUs for bound workqueues, |
296 | * WORK_CPU_UNBOUND for unbound workqueues |
297 | */ |
298 | #define for_each_gcwq_cpu(cpu) \ |
299 | for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ |
300 | (cpu) < WORK_CPU_NONE; \ |
301 | (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) |
302 | |
303 | #define for_each_online_gcwq_cpu(cpu) \ |
304 | for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ |
305 | (cpu) < WORK_CPU_NONE; \ |
306 | (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) |
307 | |
308 | #define for_each_cwq_cpu(cpu, wq) \ |
309 | for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ |
310 | (cpu) < WORK_CPU_NONE; \ |
311 | (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) |
312 | |
313 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
314 | |
315 | static struct debug_obj_descr work_debug_descr; |
316 | |
317 | /* |
318 | * fixup_init is called when: |
319 | * - an active object is initialized |
320 | */ |
321 | static int work_fixup_init(void *addr, enum debug_obj_state state) |
322 | { |
323 | struct work_struct *work = addr; |
324 | |
325 | switch (state) { |
326 | case ODEBUG_STATE_ACTIVE: |
327 | cancel_work_sync(work); |
328 | debug_object_init(work, &work_debug_descr); |
329 | return 1; |
330 | default: |
331 | return 0; |
332 | } |
333 | } |
334 | |
335 | /* |
336 | * fixup_activate is called when: |
337 | * - an active object is activated |
338 | * - an unknown object is activated (might be a statically initialized object) |
339 | */ |
340 | static int work_fixup_activate(void *addr, enum debug_obj_state state) |
341 | { |
342 | struct work_struct *work = addr; |
343 | |
344 | switch (state) { |
345 | |
346 | case ODEBUG_STATE_NOTAVAILABLE: |
347 | /* |
348 | * This is not really a fixup. The work struct was |
349 | * statically initialized. We just make sure that it |
350 | * is tracked in the object tracker. |
351 | */ |
352 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
353 | debug_object_init(work, &work_debug_descr); |
354 | debug_object_activate(work, &work_debug_descr); |
355 | return 0; |
356 | } |
357 | WARN_ON_ONCE(1); |
358 | return 0; |
359 | |
360 | case ODEBUG_STATE_ACTIVE: |
361 | WARN_ON(1); |
362 | |
363 | default: |
364 | return 0; |
365 | } |
366 | } |
367 | |
368 | /* |
369 | * fixup_free is called when: |
370 | * - an active object is freed |
371 | */ |
372 | static int work_fixup_free(void *addr, enum debug_obj_state state) |
373 | { |
374 | struct work_struct *work = addr; |
375 | |
376 | switch (state) { |
377 | case ODEBUG_STATE_ACTIVE: |
378 | cancel_work_sync(work); |
379 | debug_object_free(work, &work_debug_descr); |
380 | return 1; |
381 | default: |
382 | return 0; |
383 | } |
384 | } |
385 | |
386 | static struct debug_obj_descr work_debug_descr = { |
387 | .name = "work_struct", |
388 | .fixup_init = work_fixup_init, |
389 | .fixup_activate = work_fixup_activate, |
390 | .fixup_free = work_fixup_free, |
391 | }; |
392 | |
393 | static inline void debug_work_activate(struct work_struct *work) |
394 | { |
395 | debug_object_activate(work, &work_debug_descr); |
396 | } |
397 | |
398 | static inline void debug_work_deactivate(struct work_struct *work) |
399 | { |
400 | debug_object_deactivate(work, &work_debug_descr); |
401 | } |
402 | |
403 | void __init_work(struct work_struct *work, int onstack) |
404 | { |
405 | if (onstack) |
406 | debug_object_init_on_stack(work, &work_debug_descr); |
407 | else |
408 | debug_object_init(work, &work_debug_descr); |
409 | } |
410 | EXPORT_SYMBOL_GPL(__init_work); |
411 | |
412 | void destroy_work_on_stack(struct work_struct *work) |
413 | { |
414 | debug_object_free(work, &work_debug_descr); |
415 | } |
416 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
417 | |
418 | #else |
419 | static inline void debug_work_activate(struct work_struct *work) { } |
420 | static inline void debug_work_deactivate(struct work_struct *work) { } |
421 | #endif |
422 | |
423 | /* Serializes the accesses to the list of workqueues. */ |
424 | static DEFINE_SPINLOCK(workqueue_lock); |
425 | static LIST_HEAD(workqueues); |
426 | static bool workqueue_freezing; /* W: have wqs started freezing? */ |
427 | |
428 | /* |
429 | * The almighty global cpu workqueues. nr_running is the only field |
430 | * which is expected to be used frequently by other cpus via |
431 | * try_to_wake_up(). Put it in a separate cacheline. |
432 | */ |
433 | static DEFINE_PER_CPU(struct global_cwq, global_cwq); |
434 | static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); |
435 | |
436 | /* |
437 | * Global cpu workqueue and nr_running counter for unbound gcwq. The |
438 | * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its |
439 | * workers have WORKER_UNBOUND set. |
440 | */ |
441 | static struct global_cwq unbound_global_cwq; |
442 | static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ |
443 | |
444 | static int worker_thread(void *__worker); |
445 | |
446 | static struct global_cwq *get_gcwq(unsigned int cpu) |
447 | { |
448 | if (cpu != WORK_CPU_UNBOUND) |
449 | return &per_cpu(global_cwq, cpu); |
450 | else |
451 | return &unbound_global_cwq; |
452 | } |
453 | |
454 | static atomic_t *get_gcwq_nr_running(unsigned int cpu) |
455 | { |
456 | if (cpu != WORK_CPU_UNBOUND) |
457 | return &per_cpu(gcwq_nr_running, cpu); |
458 | else |
459 | return &unbound_gcwq_nr_running; |
460 | } |
461 | |
462 | static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
463 | struct workqueue_struct *wq) |
464 | { |
465 | if (!(wq->flags & WQ_UNBOUND)) { |
466 | if (likely(cpu < nr_cpu_ids)) { |
467 | #ifdef CONFIG_SMP |
468 | return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); |
469 | #else |
470 | return wq->cpu_wq.single; |
471 | #endif |
472 | } |
473 | } else if (likely(cpu == WORK_CPU_UNBOUND)) |
474 | return wq->cpu_wq.single; |
475 | return NULL; |
476 | } |
477 | |
478 | static unsigned int work_color_to_flags(int color) |
479 | { |
480 | return color << WORK_STRUCT_COLOR_SHIFT; |
481 | } |
482 | |
483 | static int get_work_color(struct work_struct *work) |
484 | { |
485 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & |
486 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
487 | } |
488 | |
489 | static int work_next_color(int color) |
490 | { |
491 | return (color + 1) % WORK_NR_COLORS; |
492 | } |
493 | |
494 | /* |
495 | * A work's data points to the cwq with WORK_STRUCT_CWQ set while the |
496 | * work is on queue. Once execution starts, WORK_STRUCT_CWQ is |
497 | * cleared and the work data contains the cpu number it was last on. |
498 | * |
499 | * set_work_{cwq|cpu}() and clear_work_data() can be used to set the |
500 | * cwq, cpu or clear work->data. These functions should only be |
501 | * called while the work is owned - ie. while the PENDING bit is set. |
502 | * |
503 | * get_work_[g]cwq() can be used to obtain the gcwq or cwq |
504 | * corresponding to a work. gcwq is available once the work has been |
505 | * queued anywhere after initialization. cwq is available only from |
506 | * queueing until execution starts. |
507 | */ |
508 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
509 | unsigned long flags) |
510 | { |
511 | BUG_ON(!work_pending(work)); |
512 | atomic_long_set(&work->data, data | flags | work_static(work)); |
513 | } |
514 | |
515 | static void set_work_cwq(struct work_struct *work, |
516 | struct cpu_workqueue_struct *cwq, |
517 | unsigned long extra_flags) |
518 | { |
519 | set_work_data(work, (unsigned long)cwq, |
520 | WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); |
521 | } |
522 | |
523 | static void set_work_cpu(struct work_struct *work, unsigned int cpu) |
524 | { |
525 | set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); |
526 | } |
527 | |
528 | static void clear_work_data(struct work_struct *work) |
529 | { |
530 | set_work_data(work, WORK_STRUCT_NO_CPU, 0); |
531 | } |
532 | |
533 | static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) |
534 | { |
535 | unsigned long data = atomic_long_read(&work->data); |
536 | |
537 | if (data & WORK_STRUCT_CWQ) |
538 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
539 | else |
540 | return NULL; |
541 | } |
542 | |
543 | static struct global_cwq *get_work_gcwq(struct work_struct *work) |
544 | { |
545 | unsigned long data = atomic_long_read(&work->data); |
546 | unsigned int cpu; |
547 | |
548 | if (data & WORK_STRUCT_CWQ) |
549 | return ((struct cpu_workqueue_struct *) |
550 | (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; |
551 | |
552 | cpu = data >> WORK_STRUCT_FLAG_BITS; |
553 | if (cpu == WORK_CPU_NONE) |
554 | return NULL; |
555 | |
556 | BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); |
557 | return get_gcwq(cpu); |
558 | } |
559 | |
560 | /* |
561 | * Policy functions. These define the policies on how the global |
562 | * worker pool is managed. Unless noted otherwise, these functions |
563 | * assume that they're being called with gcwq->lock held. |
564 | */ |
565 | |
566 | static bool __need_more_worker(struct global_cwq *gcwq) |
567 | { |
568 | return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || |
569 | gcwq->flags & GCWQ_HIGHPRI_PENDING; |
570 | } |
571 | |
572 | /* |
573 | * Need to wake up a worker? Called from anything but currently |
574 | * running workers. |
575 | */ |
576 | static bool need_more_worker(struct global_cwq *gcwq) |
577 | { |
578 | return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); |
579 | } |
580 | |
581 | /* Can I start working? Called from busy but !running workers. */ |
582 | static bool may_start_working(struct global_cwq *gcwq) |
583 | { |
584 | return gcwq->nr_idle; |
585 | } |
586 | |
587 | /* Do I need to keep working? Called from currently running workers. */ |
588 | static bool keep_working(struct global_cwq *gcwq) |
589 | { |
590 | atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); |
591 | |
592 | return !list_empty(&gcwq->worklist) && |
593 | (atomic_read(nr_running) <= 1 || |
594 | gcwq->flags & GCWQ_HIGHPRI_PENDING); |
595 | } |
596 | |
597 | /* Do we need a new worker? Called from manager. */ |
598 | static bool need_to_create_worker(struct global_cwq *gcwq) |
599 | { |
600 | return need_more_worker(gcwq) && !may_start_working(gcwq); |
601 | } |
602 | |
603 | /* Do I need to be the manager? */ |
604 | static bool need_to_manage_workers(struct global_cwq *gcwq) |
605 | { |
606 | return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; |
607 | } |
608 | |
609 | /* Do we have too many workers and should some go away? */ |
610 | static bool too_many_workers(struct global_cwq *gcwq) |
611 | { |
612 | bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; |
613 | int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ |
614 | int nr_busy = gcwq->nr_workers - nr_idle; |
615 | |
616 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
617 | } |
618 | |
619 | /* |
620 | * Wake up functions. |
621 | */ |
622 | |
623 | /* Return the first worker. Safe with preemption disabled */ |
624 | static struct worker *first_worker(struct global_cwq *gcwq) |
625 | { |
626 | if (unlikely(list_empty(&gcwq->idle_list))) |
627 | return NULL; |
628 | |
629 | return list_first_entry(&gcwq->idle_list, struct worker, entry); |
630 | } |
631 | |
632 | /** |
633 | * wake_up_worker - wake up an idle worker |
634 | * @gcwq: gcwq to wake worker for |
635 | * |
636 | * Wake up the first idle worker of @gcwq. |
637 | * |
638 | * CONTEXT: |
639 | * spin_lock_irq(gcwq->lock). |
640 | */ |
641 | static void wake_up_worker(struct global_cwq *gcwq) |
642 | { |
643 | struct worker *worker = first_worker(gcwq); |
644 | |
645 | if (likely(worker)) |
646 | wake_up_process(worker->task); |
647 | } |
648 | |
649 | /** |
650 | * wq_worker_waking_up - a worker is waking up |
651 | * @task: task waking up |
652 | * @cpu: CPU @task is waking up to |
653 | * |
654 | * This function is called during try_to_wake_up() when a worker is |
655 | * being awoken. |
656 | * |
657 | * CONTEXT: |
658 | * spin_lock_irq(rq->lock) |
659 | */ |
660 | void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) |
661 | { |
662 | struct worker *worker = kthread_data(task); |
663 | |
664 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
665 | atomic_inc(get_gcwq_nr_running(cpu)); |
666 | } |
667 | |
668 | /** |
669 | * wq_worker_sleeping - a worker is going to sleep |
670 | * @task: task going to sleep |
671 | * @cpu: CPU in question, must be the current CPU number |
672 | * |
673 | * This function is called during schedule() when a busy worker is |
674 | * going to sleep. Worker on the same cpu can be woken up by |
675 | * returning pointer to its task. |
676 | * |
677 | * CONTEXT: |
678 | * spin_lock_irq(rq->lock) |
679 | * |
680 | * RETURNS: |
681 | * Worker task on @cpu to wake up, %NULL if none. |
682 | */ |
683 | struct task_struct *wq_worker_sleeping(struct task_struct *task, |
684 | unsigned int cpu) |
685 | { |
686 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; |
687 | struct global_cwq *gcwq = get_gcwq(cpu); |
688 | atomic_t *nr_running = get_gcwq_nr_running(cpu); |
689 | |
690 | if (worker->flags & WORKER_NOT_RUNNING) |
691 | return NULL; |
692 | |
693 | /* this can only happen on the local cpu */ |
694 | BUG_ON(cpu != raw_smp_processor_id()); |
695 | |
696 | /* |
697 | * The counterpart of the following dec_and_test, implied mb, |
698 | * worklist not empty test sequence is in insert_work(). |
699 | * Please read comment there. |
700 | * |
701 | * NOT_RUNNING is clear. This means that trustee is not in |
702 | * charge and we're running on the local cpu w/ rq lock held |
703 | * and preemption disabled, which in turn means that none else |
704 | * could be manipulating idle_list, so dereferencing idle_list |
705 | * without gcwq lock is safe. |
706 | */ |
707 | if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) |
708 | to_wakeup = first_worker(gcwq); |
709 | return to_wakeup ? to_wakeup->task : NULL; |
710 | } |
711 | |
712 | /** |
713 | * worker_set_flags - set worker flags and adjust nr_running accordingly |
714 | * @worker: self |
715 | * @flags: flags to set |
716 | * @wakeup: wakeup an idle worker if necessary |
717 | * |
718 | * Set @flags in @worker->flags and adjust nr_running accordingly. If |
719 | * nr_running becomes zero and @wakeup is %true, an idle worker is |
720 | * woken up. |
721 | * |
722 | * CONTEXT: |
723 | * spin_lock_irq(gcwq->lock) |
724 | */ |
725 | static inline void worker_set_flags(struct worker *worker, unsigned int flags, |
726 | bool wakeup) |
727 | { |
728 | struct global_cwq *gcwq = worker->gcwq; |
729 | |
730 | WARN_ON_ONCE(worker->task != current); |
731 | |
732 | /* |
733 | * If transitioning into NOT_RUNNING, adjust nr_running and |
734 | * wake up an idle worker as necessary if requested by |
735 | * @wakeup. |
736 | */ |
737 | if ((flags & WORKER_NOT_RUNNING) && |
738 | !(worker->flags & WORKER_NOT_RUNNING)) { |
739 | atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); |
740 | |
741 | if (wakeup) { |
742 | if (atomic_dec_and_test(nr_running) && |
743 | !list_empty(&gcwq->worklist)) |
744 | wake_up_worker(gcwq); |
745 | } else |
746 | atomic_dec(nr_running); |
747 | } |
748 | |
749 | worker->flags |= flags; |
750 | } |
751 | |
752 | /** |
753 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
754 | * @worker: self |
755 | * @flags: flags to clear |
756 | * |
757 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
758 | * |
759 | * CONTEXT: |
760 | * spin_lock_irq(gcwq->lock) |
761 | */ |
762 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
763 | { |
764 | struct global_cwq *gcwq = worker->gcwq; |
765 | unsigned int oflags = worker->flags; |
766 | |
767 | WARN_ON_ONCE(worker->task != current); |
768 | |
769 | worker->flags &= ~flags; |
770 | |
771 | /* if transitioning out of NOT_RUNNING, increment nr_running */ |
772 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
773 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
774 | atomic_inc(get_gcwq_nr_running(gcwq->cpu)); |
775 | } |
776 | |
777 | /** |
778 | * busy_worker_head - return the busy hash head for a work |
779 | * @gcwq: gcwq of interest |
780 | * @work: work to be hashed |
781 | * |
782 | * Return hash head of @gcwq for @work. |
783 | * |
784 | * CONTEXT: |
785 | * spin_lock_irq(gcwq->lock). |
786 | * |
787 | * RETURNS: |
788 | * Pointer to the hash head. |
789 | */ |
790 | static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, |
791 | struct work_struct *work) |
792 | { |
793 | const int base_shift = ilog2(sizeof(struct work_struct)); |
794 | unsigned long v = (unsigned long)work; |
795 | |
796 | /* simple shift and fold hash, do we need something better? */ |
797 | v >>= base_shift; |
798 | v += v >> BUSY_WORKER_HASH_ORDER; |
799 | v &= BUSY_WORKER_HASH_MASK; |
800 | |
801 | return &gcwq->busy_hash[v]; |
802 | } |
803 | |
804 | /** |
805 | * __find_worker_executing_work - find worker which is executing a work |
806 | * @gcwq: gcwq of interest |
807 | * @bwh: hash head as returned by busy_worker_head() |
808 | * @work: work to find worker for |
809 | * |
810 | * Find a worker which is executing @work on @gcwq. @bwh should be |
811 | * the hash head obtained by calling busy_worker_head() with the same |
812 | * work. |
813 | * |
814 | * CONTEXT: |
815 | * spin_lock_irq(gcwq->lock). |
816 | * |
817 | * RETURNS: |
818 | * Pointer to worker which is executing @work if found, NULL |
819 | * otherwise. |
820 | */ |
821 | static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, |
822 | struct hlist_head *bwh, |
823 | struct work_struct *work) |
824 | { |
825 | struct worker *worker; |
826 | struct hlist_node *tmp; |
827 | |
828 | hlist_for_each_entry(worker, tmp, bwh, hentry) |
829 | if (worker->current_work == work) |
830 | return worker; |
831 | return NULL; |
832 | } |
833 | |
834 | /** |
835 | * find_worker_executing_work - find worker which is executing a work |
836 | * @gcwq: gcwq of interest |
837 | * @work: work to find worker for |
838 | * |
839 | * Find a worker which is executing @work on @gcwq. This function is |
840 | * identical to __find_worker_executing_work() except that this |
841 | * function calculates @bwh itself. |
842 | * |
843 | * CONTEXT: |
844 | * spin_lock_irq(gcwq->lock). |
845 | * |
846 | * RETURNS: |
847 | * Pointer to worker which is executing @work if found, NULL |
848 | * otherwise. |
849 | */ |
850 | static struct worker *find_worker_executing_work(struct global_cwq *gcwq, |
851 | struct work_struct *work) |
852 | { |
853 | return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), |
854 | work); |
855 | } |
856 | |
857 | /** |
858 | * gcwq_determine_ins_pos - find insertion position |
859 | * @gcwq: gcwq of interest |
860 | * @cwq: cwq a work is being queued for |
861 | * |
862 | * A work for @cwq is about to be queued on @gcwq, determine insertion |
863 | * position for the work. If @cwq is for HIGHPRI wq, the work is |
864 | * queued at the head of the queue but in FIFO order with respect to |
865 | * other HIGHPRI works; otherwise, at the end of the queue. This |
866 | * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that |
867 | * there are HIGHPRI works pending. |
868 | * |
869 | * CONTEXT: |
870 | * spin_lock_irq(gcwq->lock). |
871 | * |
872 | * RETURNS: |
873 | * Pointer to inserstion position. |
874 | */ |
875 | static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, |
876 | struct cpu_workqueue_struct *cwq) |
877 | { |
878 | struct work_struct *twork; |
879 | |
880 | if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) |
881 | return &gcwq->worklist; |
882 | |
883 | list_for_each_entry(twork, &gcwq->worklist, entry) { |
884 | struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); |
885 | |
886 | if (!(tcwq->wq->flags & WQ_HIGHPRI)) |
887 | break; |
888 | } |
889 | |
890 | gcwq->flags |= GCWQ_HIGHPRI_PENDING; |
891 | return &twork->entry; |
892 | } |
893 | |
894 | /** |
895 | * insert_work - insert a work into gcwq |
896 | * @cwq: cwq @work belongs to |
897 | * @work: work to insert |
898 | * @head: insertion point |
899 | * @extra_flags: extra WORK_STRUCT_* flags to set |
900 | * |
901 | * Insert @work which belongs to @cwq into @gcwq after @head. |
902 | * @extra_flags is or'd to work_struct flags. |
903 | * |
904 | * CONTEXT: |
905 | * spin_lock_irq(gcwq->lock). |
906 | */ |
907 | static void insert_work(struct cpu_workqueue_struct *cwq, |
908 | struct work_struct *work, struct list_head *head, |
909 | unsigned int extra_flags) |
910 | { |
911 | struct global_cwq *gcwq = cwq->gcwq; |
912 | |
913 | /* we own @work, set data and link */ |
914 | set_work_cwq(work, cwq, extra_flags); |
915 | |
916 | /* |
917 | * Ensure that we get the right work->data if we see the |
918 | * result of list_add() below, see try_to_grab_pending(). |
919 | */ |
920 | smp_wmb(); |
921 | |
922 | list_add_tail(&work->entry, head); |
923 | |
924 | /* |
925 | * Ensure either worker_sched_deactivated() sees the above |
926 | * list_add_tail() or we see zero nr_running to avoid workers |
927 | * lying around lazily while there are works to be processed. |
928 | */ |
929 | smp_mb(); |
930 | |
931 | if (__need_more_worker(gcwq)) |
932 | wake_up_worker(gcwq); |
933 | } |
934 | |
935 | static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
936 | struct work_struct *work) |
937 | { |
938 | struct global_cwq *gcwq; |
939 | struct cpu_workqueue_struct *cwq; |
940 | struct list_head *worklist; |
941 | unsigned int work_flags; |
942 | unsigned long flags; |
943 | |
944 | debug_work_activate(work); |
945 | |
946 | if (WARN_ON_ONCE(wq->flags & WQ_DYING)) |
947 | return; |
948 | |
949 | /* determine gcwq to use */ |
950 | if (!(wq->flags & WQ_UNBOUND)) { |
951 | struct global_cwq *last_gcwq; |
952 | |
953 | if (unlikely(cpu == WORK_CPU_UNBOUND)) |
954 | cpu = raw_smp_processor_id(); |
955 | |
956 | /* |
957 | * It's multi cpu. If @wq is non-reentrant and @work |
958 | * was previously on a different cpu, it might still |
959 | * be running there, in which case the work needs to |
960 | * be queued on that cpu to guarantee non-reentrance. |
961 | */ |
962 | gcwq = get_gcwq(cpu); |
963 | if (wq->flags & WQ_NON_REENTRANT && |
964 | (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { |
965 | struct worker *worker; |
966 | |
967 | spin_lock_irqsave(&last_gcwq->lock, flags); |
968 | |
969 | worker = find_worker_executing_work(last_gcwq, work); |
970 | |
971 | if (worker && worker->current_cwq->wq == wq) |
972 | gcwq = last_gcwq; |
973 | else { |
974 | /* meh... not running there, queue here */ |
975 | spin_unlock_irqrestore(&last_gcwq->lock, flags); |
976 | spin_lock_irqsave(&gcwq->lock, flags); |
977 | } |
978 | } else |
979 | spin_lock_irqsave(&gcwq->lock, flags); |
980 | } else { |
981 | gcwq = get_gcwq(WORK_CPU_UNBOUND); |
982 | spin_lock_irqsave(&gcwq->lock, flags); |
983 | } |
984 | |
985 | /* gcwq determined, get cwq and queue */ |
986 | cwq = get_cwq(gcwq->cpu, wq); |
987 | trace_workqueue_queue_work(cpu, cwq, work); |
988 | |
989 | BUG_ON(!list_empty(&work->entry)); |
990 | |
991 | cwq->nr_in_flight[cwq->work_color]++; |
992 | work_flags = work_color_to_flags(cwq->work_color); |
993 | |
994 | if (likely(cwq->nr_active < cwq->max_active)) { |
995 | trace_workqueue_activate_work(work); |
996 | cwq->nr_active++; |
997 | worklist = gcwq_determine_ins_pos(gcwq, cwq); |
998 | } else { |
999 | work_flags |= WORK_STRUCT_DELAYED; |
1000 | worklist = &cwq->delayed_works; |
1001 | } |
1002 | |
1003 | insert_work(cwq, work, worklist, work_flags); |
1004 | |
1005 | spin_unlock_irqrestore(&gcwq->lock, flags); |
1006 | } |
1007 | |
1008 | /** |
1009 | * queue_work - queue work on a workqueue |
1010 | * @wq: workqueue to use |
1011 | * @work: work to queue |
1012 | * |
1013 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1014 | * |
1015 | * We queue the work to the CPU on which it was submitted, but if the CPU dies |
1016 | * it can be processed by another CPU. |
1017 | */ |
1018 | int queue_work(struct workqueue_struct *wq, struct work_struct *work) |
1019 | { |
1020 | int ret; |
1021 | |
1022 | ret = queue_work_on(get_cpu(), wq, work); |
1023 | put_cpu(); |
1024 | |
1025 | return ret; |
1026 | } |
1027 | EXPORT_SYMBOL_GPL(queue_work); |
1028 | |
1029 | /** |
1030 | * queue_work_on - queue work on specific cpu |
1031 | * @cpu: CPU number to execute work on |
1032 | * @wq: workqueue to use |
1033 | * @work: work to queue |
1034 | * |
1035 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1036 | * |
1037 | * We queue the work to a specific CPU, the caller must ensure it |
1038 | * can't go away. |
1039 | */ |
1040 | int |
1041 | queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) |
1042 | { |
1043 | int ret = 0; |
1044 | |
1045 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1046 | __queue_work(cpu, wq, work); |
1047 | ret = 1; |
1048 | } |
1049 | return ret; |
1050 | } |
1051 | EXPORT_SYMBOL_GPL(queue_work_on); |
1052 | |
1053 | static void delayed_work_timer_fn(unsigned long __data) |
1054 | { |
1055 | struct delayed_work *dwork = (struct delayed_work *)__data; |
1056 | struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); |
1057 | |
1058 | __queue_work(smp_processor_id(), cwq->wq, &dwork->work); |
1059 | } |
1060 | |
1061 | /** |
1062 | * queue_delayed_work - queue work on a workqueue after delay |
1063 | * @wq: workqueue to use |
1064 | * @dwork: delayable work to queue |
1065 | * @delay: number of jiffies to wait before queueing |
1066 | * |
1067 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1068 | */ |
1069 | int queue_delayed_work(struct workqueue_struct *wq, |
1070 | struct delayed_work *dwork, unsigned long delay) |
1071 | { |
1072 | if (delay == 0) |
1073 | return queue_work(wq, &dwork->work); |
1074 | |
1075 | return queue_delayed_work_on(-1, wq, dwork, delay); |
1076 | } |
1077 | EXPORT_SYMBOL_GPL(queue_delayed_work); |
1078 | |
1079 | /** |
1080 | * queue_delayed_work_on - queue work on specific CPU after delay |
1081 | * @cpu: CPU number to execute work on |
1082 | * @wq: workqueue to use |
1083 | * @dwork: work to queue |
1084 | * @delay: number of jiffies to wait before queueing |
1085 | * |
1086 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1087 | */ |
1088 | int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1089 | struct delayed_work *dwork, unsigned long delay) |
1090 | { |
1091 | int ret = 0; |
1092 | struct timer_list *timer = &dwork->timer; |
1093 | struct work_struct *work = &dwork->work; |
1094 | |
1095 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1096 | unsigned int lcpu; |
1097 | |
1098 | BUG_ON(timer_pending(timer)); |
1099 | BUG_ON(!list_empty(&work->entry)); |
1100 | |
1101 | timer_stats_timer_set_start_info(&dwork->timer); |
1102 | |
1103 | /* |
1104 | * This stores cwq for the moment, for the timer_fn. |
1105 | * Note that the work's gcwq is preserved to allow |
1106 | * reentrance detection for delayed works. |
1107 | */ |
1108 | if (!(wq->flags & WQ_UNBOUND)) { |
1109 | struct global_cwq *gcwq = get_work_gcwq(work); |
1110 | |
1111 | if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) |
1112 | lcpu = gcwq->cpu; |
1113 | else |
1114 | lcpu = raw_smp_processor_id(); |
1115 | } else |
1116 | lcpu = WORK_CPU_UNBOUND; |
1117 | |
1118 | set_work_cwq(work, get_cwq(lcpu, wq), 0); |
1119 | |
1120 | timer->expires = jiffies + delay; |
1121 | timer->data = (unsigned long)dwork; |
1122 | timer->function = delayed_work_timer_fn; |
1123 | |
1124 | if (unlikely(cpu >= 0)) |
1125 | add_timer_on(timer, cpu); |
1126 | else |
1127 | add_timer(timer); |
1128 | ret = 1; |
1129 | } |
1130 | return ret; |
1131 | } |
1132 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
1133 | |
1134 | /** |
1135 | * worker_enter_idle - enter idle state |
1136 | * @worker: worker which is entering idle state |
1137 | * |
1138 | * @worker is entering idle state. Update stats and idle timer if |
1139 | * necessary. |
1140 | * |
1141 | * LOCKING: |
1142 | * spin_lock_irq(gcwq->lock). |
1143 | */ |
1144 | static void worker_enter_idle(struct worker *worker) |
1145 | { |
1146 | struct global_cwq *gcwq = worker->gcwq; |
1147 | |
1148 | BUG_ON(worker->flags & WORKER_IDLE); |
1149 | BUG_ON(!list_empty(&worker->entry) && |
1150 | (worker->hentry.next || worker->hentry.pprev)); |
1151 | |
1152 | /* can't use worker_set_flags(), also called from start_worker() */ |
1153 | worker->flags |= WORKER_IDLE; |
1154 | gcwq->nr_idle++; |
1155 | worker->last_active = jiffies; |
1156 | |
1157 | /* idle_list is LIFO */ |
1158 | list_add(&worker->entry, &gcwq->idle_list); |
1159 | |
1160 | if (likely(!(worker->flags & WORKER_ROGUE))) { |
1161 | if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) |
1162 | mod_timer(&gcwq->idle_timer, |
1163 | jiffies + IDLE_WORKER_TIMEOUT); |
1164 | } else |
1165 | wake_up_all(&gcwq->trustee_wait); |
1166 | |
1167 | /* sanity check nr_running */ |
1168 | WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && |
1169 | atomic_read(get_gcwq_nr_running(gcwq->cpu))); |
1170 | } |
1171 | |
1172 | /** |
1173 | * worker_leave_idle - leave idle state |
1174 | * @worker: worker which is leaving idle state |
1175 | * |
1176 | * @worker is leaving idle state. Update stats. |
1177 | * |
1178 | * LOCKING: |
1179 | * spin_lock_irq(gcwq->lock). |
1180 | */ |
1181 | static void worker_leave_idle(struct worker *worker) |
1182 | { |
1183 | struct global_cwq *gcwq = worker->gcwq; |
1184 | |
1185 | BUG_ON(!(worker->flags & WORKER_IDLE)); |
1186 | worker_clr_flags(worker, WORKER_IDLE); |
1187 | gcwq->nr_idle--; |
1188 | list_del_init(&worker->entry); |
1189 | } |
1190 | |
1191 | /** |
1192 | * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq |
1193 | * @worker: self |
1194 | * |
1195 | * Works which are scheduled while the cpu is online must at least be |
1196 | * scheduled to a worker which is bound to the cpu so that if they are |
1197 | * flushed from cpu callbacks while cpu is going down, they are |
1198 | * guaranteed to execute on the cpu. |
1199 | * |
1200 | * This function is to be used by rogue workers and rescuers to bind |
1201 | * themselves to the target cpu and may race with cpu going down or |
1202 | * coming online. kthread_bind() can't be used because it may put the |
1203 | * worker to already dead cpu and set_cpus_allowed_ptr() can't be used |
1204 | * verbatim as it's best effort and blocking and gcwq may be |
1205 | * [dis]associated in the meantime. |
1206 | * |
1207 | * This function tries set_cpus_allowed() and locks gcwq and verifies |
1208 | * the binding against GCWQ_DISASSOCIATED which is set during |
1209 | * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters |
1210 | * idle state or fetches works without dropping lock, it can guarantee |
1211 | * the scheduling requirement described in the first paragraph. |
1212 | * |
1213 | * CONTEXT: |
1214 | * Might sleep. Called without any lock but returns with gcwq->lock |
1215 | * held. |
1216 | * |
1217 | * RETURNS: |
1218 | * %true if the associated gcwq is online (@worker is successfully |
1219 | * bound), %false if offline. |
1220 | */ |
1221 | static bool worker_maybe_bind_and_lock(struct worker *worker) |
1222 | __acquires(&gcwq->lock) |
1223 | { |
1224 | struct global_cwq *gcwq = worker->gcwq; |
1225 | struct task_struct *task = worker->task; |
1226 | |
1227 | while (true) { |
1228 | /* |
1229 | * The following call may fail, succeed or succeed |
1230 | * without actually migrating the task to the cpu if |
1231 | * it races with cpu hotunplug operation. Verify |
1232 | * against GCWQ_DISASSOCIATED. |
1233 | */ |
1234 | if (!(gcwq->flags & GCWQ_DISASSOCIATED)) |
1235 | set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); |
1236 | |
1237 | spin_lock_irq(&gcwq->lock); |
1238 | if (gcwq->flags & GCWQ_DISASSOCIATED) |
1239 | return false; |
1240 | if (task_cpu(task) == gcwq->cpu && |
1241 | cpumask_equal(¤t->cpus_allowed, |
1242 | get_cpu_mask(gcwq->cpu))) |
1243 | return true; |
1244 | spin_unlock_irq(&gcwq->lock); |
1245 | |
1246 | /* CPU has come up inbetween, retry migration */ |
1247 | cpu_relax(); |
1248 | } |
1249 | } |
1250 | |
1251 | /* |
1252 | * Function for worker->rebind_work used to rebind rogue busy workers |
1253 | * to the associated cpu which is coming back online. This is |
1254 | * scheduled by cpu up but can race with other cpu hotplug operations |
1255 | * and may be executed twice without intervening cpu down. |
1256 | */ |
1257 | static void worker_rebind_fn(struct work_struct *work) |
1258 | { |
1259 | struct worker *worker = container_of(work, struct worker, rebind_work); |
1260 | struct global_cwq *gcwq = worker->gcwq; |
1261 | |
1262 | if (worker_maybe_bind_and_lock(worker)) |
1263 | worker_clr_flags(worker, WORKER_REBIND); |
1264 | |
1265 | spin_unlock_irq(&gcwq->lock); |
1266 | } |
1267 | |
1268 | static struct worker *alloc_worker(void) |
1269 | { |
1270 | struct worker *worker; |
1271 | |
1272 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
1273 | if (worker) { |
1274 | INIT_LIST_HEAD(&worker->entry); |
1275 | INIT_LIST_HEAD(&worker->scheduled); |
1276 | INIT_WORK(&worker->rebind_work, worker_rebind_fn); |
1277 | /* on creation a worker is in !idle && prep state */ |
1278 | worker->flags = WORKER_PREP; |
1279 | } |
1280 | return worker; |
1281 | } |
1282 | |
1283 | /** |
1284 | * create_worker - create a new workqueue worker |
1285 | * @gcwq: gcwq the new worker will belong to |
1286 | * @bind: whether to set affinity to @cpu or not |
1287 | * |
1288 | * Create a new worker which is bound to @gcwq. The returned worker |
1289 | * can be started by calling start_worker() or destroyed using |
1290 | * destroy_worker(). |
1291 | * |
1292 | * CONTEXT: |
1293 | * Might sleep. Does GFP_KERNEL allocations. |
1294 | * |
1295 | * RETURNS: |
1296 | * Pointer to the newly created worker. |
1297 | */ |
1298 | static struct worker *create_worker(struct global_cwq *gcwq, bool bind) |
1299 | { |
1300 | bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; |
1301 | struct worker *worker = NULL; |
1302 | int id = -1; |
1303 | |
1304 | spin_lock_irq(&gcwq->lock); |
1305 | while (ida_get_new(&gcwq->worker_ida, &id)) { |
1306 | spin_unlock_irq(&gcwq->lock); |
1307 | if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) |
1308 | goto fail; |
1309 | spin_lock_irq(&gcwq->lock); |
1310 | } |
1311 | spin_unlock_irq(&gcwq->lock); |
1312 | |
1313 | worker = alloc_worker(); |
1314 | if (!worker) |
1315 | goto fail; |
1316 | |
1317 | worker->gcwq = gcwq; |
1318 | worker->id = id; |
1319 | |
1320 | if (!on_unbound_cpu) |
1321 | worker->task = kthread_create(worker_thread, worker, |
1322 | "kworker/%u:%d", gcwq->cpu, id); |
1323 | else |
1324 | worker->task = kthread_create(worker_thread, worker, |
1325 | "kworker/u:%d", id); |
1326 | if (IS_ERR(worker->task)) |
1327 | goto fail; |
1328 | |
1329 | /* |
1330 | * A rogue worker will become a regular one if CPU comes |
1331 | * online later on. Make sure every worker has |
1332 | * PF_THREAD_BOUND set. |
1333 | */ |
1334 | if (bind && !on_unbound_cpu) |
1335 | kthread_bind(worker->task, gcwq->cpu); |
1336 | else { |
1337 | worker->task->flags |= PF_THREAD_BOUND; |
1338 | if (on_unbound_cpu) |
1339 | worker->flags |= WORKER_UNBOUND; |
1340 | } |
1341 | |
1342 | return worker; |
1343 | fail: |
1344 | if (id >= 0) { |
1345 | spin_lock_irq(&gcwq->lock); |
1346 | ida_remove(&gcwq->worker_ida, id); |
1347 | spin_unlock_irq(&gcwq->lock); |
1348 | } |
1349 | kfree(worker); |
1350 | return NULL; |
1351 | } |
1352 | |
1353 | /** |
1354 | * start_worker - start a newly created worker |
1355 | * @worker: worker to start |
1356 | * |
1357 | * Make the gcwq aware of @worker and start it. |
1358 | * |
1359 | * CONTEXT: |
1360 | * spin_lock_irq(gcwq->lock). |
1361 | */ |
1362 | static void start_worker(struct worker *worker) |
1363 | { |
1364 | worker->flags |= WORKER_STARTED; |
1365 | worker->gcwq->nr_workers++; |
1366 | worker_enter_idle(worker); |
1367 | wake_up_process(worker->task); |
1368 | } |
1369 | |
1370 | /** |
1371 | * destroy_worker - destroy a workqueue worker |
1372 | * @worker: worker to be destroyed |
1373 | * |
1374 | * Destroy @worker and adjust @gcwq stats accordingly. |
1375 | * |
1376 | * CONTEXT: |
1377 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
1378 | */ |
1379 | static void destroy_worker(struct worker *worker) |
1380 | { |
1381 | struct global_cwq *gcwq = worker->gcwq; |
1382 | int id = worker->id; |
1383 | |
1384 | /* sanity check frenzy */ |
1385 | BUG_ON(worker->current_work); |
1386 | BUG_ON(!list_empty(&worker->scheduled)); |
1387 | |
1388 | if (worker->flags & WORKER_STARTED) |
1389 | gcwq->nr_workers--; |
1390 | if (worker->flags & WORKER_IDLE) |
1391 | gcwq->nr_idle--; |
1392 | |
1393 | list_del_init(&worker->entry); |
1394 | worker->flags |= WORKER_DIE; |
1395 | |
1396 | spin_unlock_irq(&gcwq->lock); |
1397 | |
1398 | kthread_stop(worker->task); |
1399 | kfree(worker); |
1400 | |
1401 | spin_lock_irq(&gcwq->lock); |
1402 | ida_remove(&gcwq->worker_ida, id); |
1403 | } |
1404 | |
1405 | static void idle_worker_timeout(unsigned long __gcwq) |
1406 | { |
1407 | struct global_cwq *gcwq = (void *)__gcwq; |
1408 | |
1409 | spin_lock_irq(&gcwq->lock); |
1410 | |
1411 | if (too_many_workers(gcwq)) { |
1412 | struct worker *worker; |
1413 | unsigned long expires; |
1414 | |
1415 | /* idle_list is kept in LIFO order, check the last one */ |
1416 | worker = list_entry(gcwq->idle_list.prev, struct worker, entry); |
1417 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1418 | |
1419 | if (time_before(jiffies, expires)) |
1420 | mod_timer(&gcwq->idle_timer, expires); |
1421 | else { |
1422 | /* it's been idle for too long, wake up manager */ |
1423 | gcwq->flags |= GCWQ_MANAGE_WORKERS; |
1424 | wake_up_worker(gcwq); |
1425 | } |
1426 | } |
1427 | |
1428 | spin_unlock_irq(&gcwq->lock); |
1429 | } |
1430 | |
1431 | static bool send_mayday(struct work_struct *work) |
1432 | { |
1433 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
1434 | struct workqueue_struct *wq = cwq->wq; |
1435 | unsigned int cpu; |
1436 | |
1437 | if (!(wq->flags & WQ_RESCUER)) |
1438 | return false; |
1439 | |
1440 | /* mayday mayday mayday */ |
1441 | cpu = cwq->gcwq->cpu; |
1442 | /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ |
1443 | if (cpu == WORK_CPU_UNBOUND) |
1444 | cpu = 0; |
1445 | if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) |
1446 | wake_up_process(wq->rescuer->task); |
1447 | return true; |
1448 | } |
1449 | |
1450 | static void gcwq_mayday_timeout(unsigned long __gcwq) |
1451 | { |
1452 | struct global_cwq *gcwq = (void *)__gcwq; |
1453 | struct work_struct *work; |
1454 | |
1455 | spin_lock_irq(&gcwq->lock); |
1456 | |
1457 | if (need_to_create_worker(gcwq)) { |
1458 | /* |
1459 | * We've been trying to create a new worker but |
1460 | * haven't been successful. We might be hitting an |
1461 | * allocation deadlock. Send distress signals to |
1462 | * rescuers. |
1463 | */ |
1464 | list_for_each_entry(work, &gcwq->worklist, entry) |
1465 | send_mayday(work); |
1466 | } |
1467 | |
1468 | spin_unlock_irq(&gcwq->lock); |
1469 | |
1470 | mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); |
1471 | } |
1472 | |
1473 | /** |
1474 | * maybe_create_worker - create a new worker if necessary |
1475 | * @gcwq: gcwq to create a new worker for |
1476 | * |
1477 | * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to |
1478 | * have at least one idle worker on return from this function. If |
1479 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
1480 | * sent to all rescuers with works scheduled on @gcwq to resolve |
1481 | * possible allocation deadlock. |
1482 | * |
1483 | * On return, need_to_create_worker() is guaranteed to be false and |
1484 | * may_start_working() true. |
1485 | * |
1486 | * LOCKING: |
1487 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1488 | * multiple times. Does GFP_KERNEL allocations. Called only from |
1489 | * manager. |
1490 | * |
1491 | * RETURNS: |
1492 | * false if no action was taken and gcwq->lock stayed locked, true |
1493 | * otherwise. |
1494 | */ |
1495 | static bool maybe_create_worker(struct global_cwq *gcwq) |
1496 | __releases(&gcwq->lock) |
1497 | __acquires(&gcwq->lock) |
1498 | { |
1499 | if (!need_to_create_worker(gcwq)) |
1500 | return false; |
1501 | restart: |
1502 | spin_unlock_irq(&gcwq->lock); |
1503 | |
1504 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
1505 | mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
1506 | |
1507 | while (true) { |
1508 | struct worker *worker; |
1509 | |
1510 | worker = create_worker(gcwq, true); |
1511 | if (worker) { |
1512 | del_timer_sync(&gcwq->mayday_timer); |
1513 | spin_lock_irq(&gcwq->lock); |
1514 | start_worker(worker); |
1515 | BUG_ON(need_to_create_worker(gcwq)); |
1516 | return true; |
1517 | } |
1518 | |
1519 | if (!need_to_create_worker(gcwq)) |
1520 | break; |
1521 | |
1522 | __set_current_state(TASK_INTERRUPTIBLE); |
1523 | schedule_timeout(CREATE_COOLDOWN); |
1524 | |
1525 | if (!need_to_create_worker(gcwq)) |
1526 | break; |
1527 | } |
1528 | |
1529 | del_timer_sync(&gcwq->mayday_timer); |
1530 | spin_lock_irq(&gcwq->lock); |
1531 | if (need_to_create_worker(gcwq)) |
1532 | goto restart; |
1533 | return true; |
1534 | } |
1535 | |
1536 | /** |
1537 | * maybe_destroy_worker - destroy workers which have been idle for a while |
1538 | * @gcwq: gcwq to destroy workers for |
1539 | * |
1540 | * Destroy @gcwq workers which have been idle for longer than |
1541 | * IDLE_WORKER_TIMEOUT. |
1542 | * |
1543 | * LOCKING: |
1544 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1545 | * multiple times. Called only from manager. |
1546 | * |
1547 | * RETURNS: |
1548 | * false if no action was taken and gcwq->lock stayed locked, true |
1549 | * otherwise. |
1550 | */ |
1551 | static bool maybe_destroy_workers(struct global_cwq *gcwq) |
1552 | { |
1553 | bool ret = false; |
1554 | |
1555 | while (too_many_workers(gcwq)) { |
1556 | struct worker *worker; |
1557 | unsigned long expires; |
1558 | |
1559 | worker = list_entry(gcwq->idle_list.prev, struct worker, entry); |
1560 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1561 | |
1562 | if (time_before(jiffies, expires)) { |
1563 | mod_timer(&gcwq->idle_timer, expires); |
1564 | break; |
1565 | } |
1566 | |
1567 | destroy_worker(worker); |
1568 | ret = true; |
1569 | } |
1570 | |
1571 | return ret; |
1572 | } |
1573 | |
1574 | /** |
1575 | * manage_workers - manage worker pool |
1576 | * @worker: self |
1577 | * |
1578 | * Assume the manager role and manage gcwq worker pool @worker belongs |
1579 | * to. At any given time, there can be only zero or one manager per |
1580 | * gcwq. The exclusion is handled automatically by this function. |
1581 | * |
1582 | * The caller can safely start processing works on false return. On |
1583 | * true return, it's guaranteed that need_to_create_worker() is false |
1584 | * and may_start_working() is true. |
1585 | * |
1586 | * CONTEXT: |
1587 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1588 | * multiple times. Does GFP_KERNEL allocations. |
1589 | * |
1590 | * RETURNS: |
1591 | * false if no action was taken and gcwq->lock stayed locked, true if |
1592 | * some action was taken. |
1593 | */ |
1594 | static bool manage_workers(struct worker *worker) |
1595 | { |
1596 | struct global_cwq *gcwq = worker->gcwq; |
1597 | bool ret = false; |
1598 | |
1599 | if (gcwq->flags & GCWQ_MANAGING_WORKERS) |
1600 | return ret; |
1601 | |
1602 | gcwq->flags &= ~GCWQ_MANAGE_WORKERS; |
1603 | gcwq->flags |= GCWQ_MANAGING_WORKERS; |
1604 | |
1605 | /* |
1606 | * Destroy and then create so that may_start_working() is true |
1607 | * on return. |
1608 | */ |
1609 | ret |= maybe_destroy_workers(gcwq); |
1610 | ret |= maybe_create_worker(gcwq); |
1611 | |
1612 | gcwq->flags &= ~GCWQ_MANAGING_WORKERS; |
1613 | |
1614 | /* |
1615 | * The trustee might be waiting to take over the manager |
1616 | * position, tell it we're done. |
1617 | */ |
1618 | if (unlikely(gcwq->trustee)) |
1619 | wake_up_all(&gcwq->trustee_wait); |
1620 | |
1621 | return ret; |
1622 | } |
1623 | |
1624 | /** |
1625 | * move_linked_works - move linked works to a list |
1626 | * @work: start of series of works to be scheduled |
1627 | * @head: target list to append @work to |
1628 | * @nextp: out paramter for nested worklist walking |
1629 | * |
1630 | * Schedule linked works starting from @work to @head. Work series to |
1631 | * be scheduled starts at @work and includes any consecutive work with |
1632 | * WORK_STRUCT_LINKED set in its predecessor. |
1633 | * |
1634 | * If @nextp is not NULL, it's updated to point to the next work of |
1635 | * the last scheduled work. This allows move_linked_works() to be |
1636 | * nested inside outer list_for_each_entry_safe(). |
1637 | * |
1638 | * CONTEXT: |
1639 | * spin_lock_irq(gcwq->lock). |
1640 | */ |
1641 | static void move_linked_works(struct work_struct *work, struct list_head *head, |
1642 | struct work_struct **nextp) |
1643 | { |
1644 | struct work_struct *n; |
1645 | |
1646 | /* |
1647 | * Linked worklist will always end before the end of the list, |
1648 | * use NULL for list head. |
1649 | */ |
1650 | list_for_each_entry_safe_from(work, n, NULL, entry) { |
1651 | list_move_tail(&work->entry, head); |
1652 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
1653 | break; |
1654 | } |
1655 | |
1656 | /* |
1657 | * If we're already inside safe list traversal and have moved |
1658 | * multiple works to the scheduled queue, the next position |
1659 | * needs to be updated. |
1660 | */ |
1661 | if (nextp) |
1662 | *nextp = n; |
1663 | } |
1664 | |
1665 | static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) |
1666 | { |
1667 | struct work_struct *work = list_first_entry(&cwq->delayed_works, |
1668 | struct work_struct, entry); |
1669 | struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); |
1670 | |
1671 | trace_workqueue_activate_work(work); |
1672 | move_linked_works(work, pos, NULL); |
1673 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); |
1674 | cwq->nr_active++; |
1675 | } |
1676 | |
1677 | /** |
1678 | * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight |
1679 | * @cwq: cwq of interest |
1680 | * @color: color of work which left the queue |
1681 | * @delayed: for a delayed work |
1682 | * |
1683 | * A work either has completed or is removed from pending queue, |
1684 | * decrement nr_in_flight of its cwq and handle workqueue flushing. |
1685 | * |
1686 | * CONTEXT: |
1687 | * spin_lock_irq(gcwq->lock). |
1688 | */ |
1689 | static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, |
1690 | bool delayed) |
1691 | { |
1692 | /* ignore uncolored works */ |
1693 | if (color == WORK_NO_COLOR) |
1694 | return; |
1695 | |
1696 | cwq->nr_in_flight[color]--; |
1697 | |
1698 | if (!delayed) { |
1699 | cwq->nr_active--; |
1700 | if (!list_empty(&cwq->delayed_works)) { |
1701 | /* one down, submit a delayed one */ |
1702 | if (cwq->nr_active < cwq->max_active) |
1703 | cwq_activate_first_delayed(cwq); |
1704 | } |
1705 | } |
1706 | |
1707 | /* is flush in progress and are we at the flushing tip? */ |
1708 | if (likely(cwq->flush_color != color)) |
1709 | return; |
1710 | |
1711 | /* are there still in-flight works? */ |
1712 | if (cwq->nr_in_flight[color]) |
1713 | return; |
1714 | |
1715 | /* this cwq is done, clear flush_color */ |
1716 | cwq->flush_color = -1; |
1717 | |
1718 | /* |
1719 | * If this was the last cwq, wake up the first flusher. It |
1720 | * will handle the rest. |
1721 | */ |
1722 | if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) |
1723 | complete(&cwq->wq->first_flusher->done); |
1724 | } |
1725 | |
1726 | /** |
1727 | * process_one_work - process single work |
1728 | * @worker: self |
1729 | * @work: work to process |
1730 | * |
1731 | * Process @work. This function contains all the logics necessary to |
1732 | * process a single work including synchronization against and |
1733 | * interaction with other workers on the same cpu, queueing and |
1734 | * flushing. As long as context requirement is met, any worker can |
1735 | * call this function to process a work. |
1736 | * |
1737 | * CONTEXT: |
1738 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
1739 | */ |
1740 | static void process_one_work(struct worker *worker, struct work_struct *work) |
1741 | __releases(&gcwq->lock) |
1742 | __acquires(&gcwq->lock) |
1743 | { |
1744 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
1745 | struct global_cwq *gcwq = cwq->gcwq; |
1746 | struct hlist_head *bwh = busy_worker_head(gcwq, work); |
1747 | bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; |
1748 | work_func_t f = work->func; |
1749 | int work_color; |
1750 | struct worker *collision; |
1751 | #ifdef CONFIG_LOCKDEP |
1752 | /* |
1753 | * It is permissible to free the struct work_struct from |
1754 | * inside the function that is called from it, this we need to |
1755 | * take into account for lockdep too. To avoid bogus "held |
1756 | * lock freed" warnings as well as problems when looking into |
1757 | * work->lockdep_map, make a copy and use that here. |
1758 | */ |
1759 | struct lockdep_map lockdep_map = work->lockdep_map; |
1760 | #endif |
1761 | /* |
1762 | * A single work shouldn't be executed concurrently by |
1763 | * multiple workers on a single cpu. Check whether anyone is |
1764 | * already processing the work. If so, defer the work to the |
1765 | * currently executing one. |
1766 | */ |
1767 | collision = __find_worker_executing_work(gcwq, bwh, work); |
1768 | if (unlikely(collision)) { |
1769 | move_linked_works(work, &collision->scheduled, NULL); |
1770 | return; |
1771 | } |
1772 | |
1773 | /* claim and process */ |
1774 | debug_work_deactivate(work); |
1775 | hlist_add_head(&worker->hentry, bwh); |
1776 | worker->current_work = work; |
1777 | worker->current_cwq = cwq; |
1778 | work_color = get_work_color(work); |
1779 | |
1780 | /* record the current cpu number in the work data and dequeue */ |
1781 | set_work_cpu(work, gcwq->cpu); |
1782 | list_del_init(&work->entry); |
1783 | |
1784 | /* |
1785 | * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, |
1786 | * wake up another worker; otherwise, clear HIGHPRI_PENDING. |
1787 | */ |
1788 | if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { |
1789 | struct work_struct *nwork = list_first_entry(&gcwq->worklist, |
1790 | struct work_struct, entry); |
1791 | |
1792 | if (!list_empty(&gcwq->worklist) && |
1793 | get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) |
1794 | wake_up_worker(gcwq); |
1795 | else |
1796 | gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; |
1797 | } |
1798 | |
1799 | /* |
1800 | * CPU intensive works don't participate in concurrency |
1801 | * management. They're the scheduler's responsibility. |
1802 | */ |
1803 | if (unlikely(cpu_intensive)) |
1804 | worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); |
1805 | |
1806 | spin_unlock_irq(&gcwq->lock); |
1807 | |
1808 | work_clear_pending(work); |
1809 | lock_map_acquire(&cwq->wq->lockdep_map); |
1810 | lock_map_acquire(&lockdep_map); |
1811 | trace_workqueue_execute_start(work); |
1812 | f(work); |
1813 | /* |
1814 | * While we must be careful to not use "work" after this, the trace |
1815 | * point will only record its address. |
1816 | */ |
1817 | trace_workqueue_execute_end(work); |
1818 | lock_map_release(&lockdep_map); |
1819 | lock_map_release(&cwq->wq->lockdep_map); |
1820 | |
1821 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
1822 | printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " |
1823 | "%s/0x%08x/%d\n", |
1824 | current->comm, preempt_count(), task_pid_nr(current)); |
1825 | printk(KERN_ERR " last function: "); |
1826 | print_symbol("%s\n", (unsigned long)f); |
1827 | debug_show_held_locks(current); |
1828 | dump_stack(); |
1829 | } |
1830 | |
1831 | spin_lock_irq(&gcwq->lock); |
1832 | |
1833 | /* clear cpu intensive status */ |
1834 | if (unlikely(cpu_intensive)) |
1835 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); |
1836 | |
1837 | /* we're done with it, release */ |
1838 | hlist_del_init(&worker->hentry); |
1839 | worker->current_work = NULL; |
1840 | worker->current_cwq = NULL; |
1841 | cwq_dec_nr_in_flight(cwq, work_color, false); |
1842 | } |
1843 | |
1844 | /** |
1845 | * process_scheduled_works - process scheduled works |
1846 | * @worker: self |
1847 | * |
1848 | * Process all scheduled works. Please note that the scheduled list |
1849 | * may change while processing a work, so this function repeatedly |
1850 | * fetches a work from the top and executes it. |
1851 | * |
1852 | * CONTEXT: |
1853 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1854 | * multiple times. |
1855 | */ |
1856 | static void process_scheduled_works(struct worker *worker) |
1857 | { |
1858 | while (!list_empty(&worker->scheduled)) { |
1859 | struct work_struct *work = list_first_entry(&worker->scheduled, |
1860 | struct work_struct, entry); |
1861 | process_one_work(worker, work); |
1862 | } |
1863 | } |
1864 | |
1865 | /** |
1866 | * worker_thread - the worker thread function |
1867 | * @__worker: self |
1868 | * |
1869 | * The gcwq worker thread function. There's a single dynamic pool of |
1870 | * these per each cpu. These workers process all works regardless of |
1871 | * their specific target workqueue. The only exception is works which |
1872 | * belong to workqueues with a rescuer which will be explained in |
1873 | * rescuer_thread(). |
1874 | */ |
1875 | static int worker_thread(void *__worker) |
1876 | { |
1877 | struct worker *worker = __worker; |
1878 | struct global_cwq *gcwq = worker->gcwq; |
1879 | |
1880 | /* tell the scheduler that this is a workqueue worker */ |
1881 | worker->task->flags |= PF_WQ_WORKER; |
1882 | woke_up: |
1883 | spin_lock_irq(&gcwq->lock); |
1884 | |
1885 | /* DIE can be set only while we're idle, checking here is enough */ |
1886 | if (worker->flags & WORKER_DIE) { |
1887 | spin_unlock_irq(&gcwq->lock); |
1888 | worker->task->flags &= ~PF_WQ_WORKER; |
1889 | return 0; |
1890 | } |
1891 | |
1892 | worker_leave_idle(worker); |
1893 | recheck: |
1894 | /* no more worker necessary? */ |
1895 | if (!need_more_worker(gcwq)) |
1896 | goto sleep; |
1897 | |
1898 | /* do we need to manage? */ |
1899 | if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) |
1900 | goto recheck; |
1901 | |
1902 | /* |
1903 | * ->scheduled list can only be filled while a worker is |
1904 | * preparing to process a work or actually processing it. |
1905 | * Make sure nobody diddled with it while I was sleeping. |
1906 | */ |
1907 | BUG_ON(!list_empty(&worker->scheduled)); |
1908 | |
1909 | /* |
1910 | * When control reaches this point, we're guaranteed to have |
1911 | * at least one idle worker or that someone else has already |
1912 | * assumed the manager role. |
1913 | */ |
1914 | worker_clr_flags(worker, WORKER_PREP); |
1915 | |
1916 | do { |
1917 | struct work_struct *work = |
1918 | list_first_entry(&gcwq->worklist, |
1919 | struct work_struct, entry); |
1920 | |
1921 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
1922 | /* optimization path, not strictly necessary */ |
1923 | process_one_work(worker, work); |
1924 | if (unlikely(!list_empty(&worker->scheduled))) |
1925 | process_scheduled_works(worker); |
1926 | } else { |
1927 | move_linked_works(work, &worker->scheduled, NULL); |
1928 | process_scheduled_works(worker); |
1929 | } |
1930 | } while (keep_working(gcwq)); |
1931 | |
1932 | worker_set_flags(worker, WORKER_PREP, false); |
1933 | sleep: |
1934 | if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) |
1935 | goto recheck; |
1936 | |
1937 | /* |
1938 | * gcwq->lock is held and there's no work to process and no |
1939 | * need to manage, sleep. Workers are woken up only while |
1940 | * holding gcwq->lock or from local cpu, so setting the |
1941 | * current state before releasing gcwq->lock is enough to |
1942 | * prevent losing any event. |
1943 | */ |
1944 | worker_enter_idle(worker); |
1945 | __set_current_state(TASK_INTERRUPTIBLE); |
1946 | spin_unlock_irq(&gcwq->lock); |
1947 | schedule(); |
1948 | goto woke_up; |
1949 | } |
1950 | |
1951 | /** |
1952 | * rescuer_thread - the rescuer thread function |
1953 | * @__wq: the associated workqueue |
1954 | * |
1955 | * Workqueue rescuer thread function. There's one rescuer for each |
1956 | * workqueue which has WQ_RESCUER set. |
1957 | * |
1958 | * Regular work processing on a gcwq may block trying to create a new |
1959 | * worker which uses GFP_KERNEL allocation which has slight chance of |
1960 | * developing into deadlock if some works currently on the same queue |
1961 | * need to be processed to satisfy the GFP_KERNEL allocation. This is |
1962 | * the problem rescuer solves. |
1963 | * |
1964 | * When such condition is possible, the gcwq summons rescuers of all |
1965 | * workqueues which have works queued on the gcwq and let them process |
1966 | * those works so that forward progress can be guaranteed. |
1967 | * |
1968 | * This should happen rarely. |
1969 | */ |
1970 | static int rescuer_thread(void *__wq) |
1971 | { |
1972 | struct workqueue_struct *wq = __wq; |
1973 | struct worker *rescuer = wq->rescuer; |
1974 | struct list_head *scheduled = &rescuer->scheduled; |
1975 | bool is_unbound = wq->flags & WQ_UNBOUND; |
1976 | unsigned int cpu; |
1977 | |
1978 | set_user_nice(current, RESCUER_NICE_LEVEL); |
1979 | repeat: |
1980 | set_current_state(TASK_INTERRUPTIBLE); |
1981 | |
1982 | if (kthread_should_stop()) |
1983 | return 0; |
1984 | |
1985 | /* |
1986 | * See whether any cpu is asking for help. Unbounded |
1987 | * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. |
1988 | */ |
1989 | for_each_mayday_cpu(cpu, wq->mayday_mask) { |
1990 | unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; |
1991 | struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); |
1992 | struct global_cwq *gcwq = cwq->gcwq; |
1993 | struct work_struct *work, *n; |
1994 | |
1995 | __set_current_state(TASK_RUNNING); |
1996 | mayday_clear_cpu(cpu, wq->mayday_mask); |
1997 | |
1998 | /* migrate to the target cpu if possible */ |
1999 | rescuer->gcwq = gcwq; |
2000 | worker_maybe_bind_and_lock(rescuer); |
2001 | |
2002 | /* |
2003 | * Slurp in all works issued via this workqueue and |
2004 | * process'em. |
2005 | */ |
2006 | BUG_ON(!list_empty(&rescuer->scheduled)); |
2007 | list_for_each_entry_safe(work, n, &gcwq->worklist, entry) |
2008 | if (get_work_cwq(work) == cwq) |
2009 | move_linked_works(work, scheduled, &n); |
2010 | |
2011 | process_scheduled_works(rescuer); |
2012 | spin_unlock_irq(&gcwq->lock); |
2013 | } |
2014 | |
2015 | schedule(); |
2016 | goto repeat; |
2017 | } |
2018 | |
2019 | struct wq_barrier { |
2020 | struct work_struct work; |
2021 | struct completion done; |
2022 | }; |
2023 | |
2024 | static void wq_barrier_func(struct work_struct *work) |
2025 | { |
2026 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
2027 | complete(&barr->done); |
2028 | } |
2029 | |
2030 | /** |
2031 | * insert_wq_barrier - insert a barrier work |
2032 | * @cwq: cwq to insert barrier into |
2033 | * @barr: wq_barrier to insert |
2034 | * @target: target work to attach @barr to |
2035 | * @worker: worker currently executing @target, NULL if @target is not executing |
2036 | * |
2037 | * @barr is linked to @target such that @barr is completed only after |
2038 | * @target finishes execution. Please note that the ordering |
2039 | * guarantee is observed only with respect to @target and on the local |
2040 | * cpu. |
2041 | * |
2042 | * Currently, a queued barrier can't be canceled. This is because |
2043 | * try_to_grab_pending() can't determine whether the work to be |
2044 | * grabbed is at the head of the queue and thus can't clear LINKED |
2045 | * flag of the previous work while there must be a valid next work |
2046 | * after a work with LINKED flag set. |
2047 | * |
2048 | * Note that when @worker is non-NULL, @target may be modified |
2049 | * underneath us, so we can't reliably determine cwq from @target. |
2050 | * |
2051 | * CONTEXT: |
2052 | * spin_lock_irq(gcwq->lock). |
2053 | */ |
2054 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
2055 | struct wq_barrier *barr, |
2056 | struct work_struct *target, struct worker *worker) |
2057 | { |
2058 | struct list_head *head; |
2059 | unsigned int linked = 0; |
2060 | |
2061 | /* |
2062 | * debugobject calls are safe here even with gcwq->lock locked |
2063 | * as we know for sure that this will not trigger any of the |
2064 | * checks and call back into the fixup functions where we |
2065 | * might deadlock. |
2066 | */ |
2067 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
2068 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
2069 | init_completion(&barr->done); |
2070 | |
2071 | /* |
2072 | * If @target is currently being executed, schedule the |
2073 | * barrier to the worker; otherwise, put it after @target. |
2074 | */ |
2075 | if (worker) |
2076 | head = worker->scheduled.next; |
2077 | else { |
2078 | unsigned long *bits = work_data_bits(target); |
2079 | |
2080 | head = target->entry.next; |
2081 | /* there can already be other linked works, inherit and set */ |
2082 | linked = *bits & WORK_STRUCT_LINKED; |
2083 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
2084 | } |
2085 | |
2086 | debug_work_activate(&barr->work); |
2087 | insert_work(cwq, &barr->work, head, |
2088 | work_color_to_flags(WORK_NO_COLOR) | linked); |
2089 | } |
2090 | |
2091 | /** |
2092 | * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing |
2093 | * @wq: workqueue being flushed |
2094 | * @flush_color: new flush color, < 0 for no-op |
2095 | * @work_color: new work color, < 0 for no-op |
2096 | * |
2097 | * Prepare cwqs for workqueue flushing. |
2098 | * |
2099 | * If @flush_color is non-negative, flush_color on all cwqs should be |
2100 | * -1. If no cwq has in-flight commands at the specified color, all |
2101 | * cwq->flush_color's stay at -1 and %false is returned. If any cwq |
2102 | * has in flight commands, its cwq->flush_color is set to |
2103 | * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq |
2104 | * wakeup logic is armed and %true is returned. |
2105 | * |
2106 | * The caller should have initialized @wq->first_flusher prior to |
2107 | * calling this function with non-negative @flush_color. If |
2108 | * @flush_color is negative, no flush color update is done and %false |
2109 | * is returned. |
2110 | * |
2111 | * If @work_color is non-negative, all cwqs should have the same |
2112 | * work_color which is previous to @work_color and all will be |
2113 | * advanced to @work_color. |
2114 | * |
2115 | * CONTEXT: |
2116 | * mutex_lock(wq->flush_mutex). |
2117 | * |
2118 | * RETURNS: |
2119 | * %true if @flush_color >= 0 and there's something to flush. %false |
2120 | * otherwise. |
2121 | */ |
2122 | static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, |
2123 | int flush_color, int work_color) |
2124 | { |
2125 | bool wait = false; |
2126 | unsigned int cpu; |
2127 | |
2128 | if (flush_color >= 0) { |
2129 | BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); |
2130 | atomic_set(&wq->nr_cwqs_to_flush, 1); |
2131 | } |
2132 | |
2133 | for_each_cwq_cpu(cpu, wq) { |
2134 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2135 | struct global_cwq *gcwq = cwq->gcwq; |
2136 | |
2137 | spin_lock_irq(&gcwq->lock); |
2138 | |
2139 | if (flush_color >= 0) { |
2140 | BUG_ON(cwq->flush_color != -1); |
2141 | |
2142 | if (cwq->nr_in_flight[flush_color]) { |
2143 | cwq->flush_color = flush_color; |
2144 | atomic_inc(&wq->nr_cwqs_to_flush); |
2145 | wait = true; |
2146 | } |
2147 | } |
2148 | |
2149 | if (work_color >= 0) { |
2150 | BUG_ON(work_color != work_next_color(cwq->work_color)); |
2151 | cwq->work_color = work_color; |
2152 | } |
2153 | |
2154 | spin_unlock_irq(&gcwq->lock); |
2155 | } |
2156 | |
2157 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) |
2158 | complete(&wq->first_flusher->done); |
2159 | |
2160 | return wait; |
2161 | } |
2162 | |
2163 | /** |
2164 | * flush_workqueue - ensure that any scheduled work has run to completion. |
2165 | * @wq: workqueue to flush |
2166 | * |
2167 | * Forces execution of the workqueue and blocks until its completion. |
2168 | * This is typically used in driver shutdown handlers. |
2169 | * |
2170 | * We sleep until all works which were queued on entry have been handled, |
2171 | * but we are not livelocked by new incoming ones. |
2172 | */ |
2173 | void flush_workqueue(struct workqueue_struct *wq) |
2174 | { |
2175 | struct wq_flusher this_flusher = { |
2176 | .list = LIST_HEAD_INIT(this_flusher.list), |
2177 | .flush_color = -1, |
2178 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), |
2179 | }; |
2180 | int next_color; |
2181 | |
2182 | lock_map_acquire(&wq->lockdep_map); |
2183 | lock_map_release(&wq->lockdep_map); |
2184 | |
2185 | mutex_lock(&wq->flush_mutex); |
2186 | |
2187 | /* |
2188 | * Start-to-wait phase |
2189 | */ |
2190 | next_color = work_next_color(wq->work_color); |
2191 | |
2192 | if (next_color != wq->flush_color) { |
2193 | /* |
2194 | * Color space is not full. The current work_color |
2195 | * becomes our flush_color and work_color is advanced |
2196 | * by one. |
2197 | */ |
2198 | BUG_ON(!list_empty(&wq->flusher_overflow)); |
2199 | this_flusher.flush_color = wq->work_color; |
2200 | wq->work_color = next_color; |
2201 | |
2202 | if (!wq->first_flusher) { |
2203 | /* no flush in progress, become the first flusher */ |
2204 | BUG_ON(wq->flush_color != this_flusher.flush_color); |
2205 | |
2206 | wq->first_flusher = &this_flusher; |
2207 | |
2208 | if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, |
2209 | wq->work_color)) { |
2210 | /* nothing to flush, done */ |
2211 | wq->flush_color = next_color; |
2212 | wq->first_flusher = NULL; |
2213 | goto out_unlock; |
2214 | } |
2215 | } else { |
2216 | /* wait in queue */ |
2217 | BUG_ON(wq->flush_color == this_flusher.flush_color); |
2218 | list_add_tail(&this_flusher.list, &wq->flusher_queue); |
2219 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
2220 | } |
2221 | } else { |
2222 | /* |
2223 | * Oops, color space is full, wait on overflow queue. |
2224 | * The next flush completion will assign us |
2225 | * flush_color and transfer to flusher_queue. |
2226 | */ |
2227 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
2228 | } |
2229 | |
2230 | mutex_unlock(&wq->flush_mutex); |
2231 | |
2232 | wait_for_completion(&this_flusher.done); |
2233 | |
2234 | /* |
2235 | * Wake-up-and-cascade phase |
2236 | * |
2237 | * First flushers are responsible for cascading flushes and |
2238 | * handling overflow. Non-first flushers can simply return. |
2239 | */ |
2240 | if (wq->first_flusher != &this_flusher) |
2241 | return; |
2242 | |
2243 | mutex_lock(&wq->flush_mutex); |
2244 | |
2245 | /* we might have raced, check again with mutex held */ |
2246 | if (wq->first_flusher != &this_flusher) |
2247 | goto out_unlock; |
2248 | |
2249 | wq->first_flusher = NULL; |
2250 | |
2251 | BUG_ON(!list_empty(&this_flusher.list)); |
2252 | BUG_ON(wq->flush_color != this_flusher.flush_color); |
2253 | |
2254 | while (true) { |
2255 | struct wq_flusher *next, *tmp; |
2256 | |
2257 | /* complete all the flushers sharing the current flush color */ |
2258 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
2259 | if (next->flush_color != wq->flush_color) |
2260 | break; |
2261 | list_del_init(&next->list); |
2262 | complete(&next->done); |
2263 | } |
2264 | |
2265 | BUG_ON(!list_empty(&wq->flusher_overflow) && |
2266 | wq->flush_color != work_next_color(wq->work_color)); |
2267 | |
2268 | /* this flush_color is finished, advance by one */ |
2269 | wq->flush_color = work_next_color(wq->flush_color); |
2270 | |
2271 | /* one color has been freed, handle overflow queue */ |
2272 | if (!list_empty(&wq->flusher_overflow)) { |
2273 | /* |
2274 | * Assign the same color to all overflowed |
2275 | * flushers, advance work_color and append to |
2276 | * flusher_queue. This is the start-to-wait |
2277 | * phase for these overflowed flushers. |
2278 | */ |
2279 | list_for_each_entry(tmp, &wq->flusher_overflow, list) |
2280 | tmp->flush_color = wq->work_color; |
2281 | |
2282 | wq->work_color = work_next_color(wq->work_color); |
2283 | |
2284 | list_splice_tail_init(&wq->flusher_overflow, |
2285 | &wq->flusher_queue); |
2286 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
2287 | } |
2288 | |
2289 | if (list_empty(&wq->flusher_queue)) { |
2290 | BUG_ON(wq->flush_color != wq->work_color); |
2291 | break; |
2292 | } |
2293 | |
2294 | /* |
2295 | * Need to flush more colors. Make the next flusher |
2296 | * the new first flusher and arm cwqs. |
2297 | */ |
2298 | BUG_ON(wq->flush_color == wq->work_color); |
2299 | BUG_ON(wq->flush_color != next->flush_color); |
2300 | |
2301 | list_del_init(&next->list); |
2302 | wq->first_flusher = next; |
2303 | |
2304 | if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) |
2305 | break; |
2306 | |
2307 | /* |
2308 | * Meh... this color is already done, clear first |
2309 | * flusher and repeat cascading. |
2310 | */ |
2311 | wq->first_flusher = NULL; |
2312 | } |
2313 | |
2314 | out_unlock: |
2315 | mutex_unlock(&wq->flush_mutex); |
2316 | } |
2317 | EXPORT_SYMBOL_GPL(flush_workqueue); |
2318 | |
2319 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, |
2320 | bool wait_executing) |
2321 | { |
2322 | struct worker *worker = NULL; |
2323 | struct global_cwq *gcwq; |
2324 | struct cpu_workqueue_struct *cwq; |
2325 | |
2326 | might_sleep(); |
2327 | gcwq = get_work_gcwq(work); |
2328 | if (!gcwq) |
2329 | return false; |
2330 | |
2331 | spin_lock_irq(&gcwq->lock); |
2332 | if (!list_empty(&work->entry)) { |
2333 | /* |
2334 | * See the comment near try_to_grab_pending()->smp_rmb(). |
2335 | * If it was re-queued to a different gcwq under us, we |
2336 | * are not going to wait. |
2337 | */ |
2338 | smp_rmb(); |
2339 | cwq = get_work_cwq(work); |
2340 | if (unlikely(!cwq || gcwq != cwq->gcwq)) |
2341 | goto already_gone; |
2342 | } else if (wait_executing) { |
2343 | worker = find_worker_executing_work(gcwq, work); |
2344 | if (!worker) |
2345 | goto already_gone; |
2346 | cwq = worker->current_cwq; |
2347 | } else |
2348 | goto already_gone; |
2349 | |
2350 | insert_wq_barrier(cwq, barr, work, worker); |
2351 | spin_unlock_irq(&gcwq->lock); |
2352 | |
2353 | lock_map_acquire(&cwq->wq->lockdep_map); |
2354 | lock_map_release(&cwq->wq->lockdep_map); |
2355 | return true; |
2356 | already_gone: |
2357 | spin_unlock_irq(&gcwq->lock); |
2358 | return false; |
2359 | } |
2360 | |
2361 | /** |
2362 | * flush_work - wait for a work to finish executing the last queueing instance |
2363 | * @work: the work to flush |
2364 | * |
2365 | * Wait until @work has finished execution. This function considers |
2366 | * only the last queueing instance of @work. If @work has been |
2367 | * enqueued across different CPUs on a non-reentrant workqueue or on |
2368 | * multiple workqueues, @work might still be executing on return on |
2369 | * some of the CPUs from earlier queueing. |
2370 | * |
2371 | * If @work was queued only on a non-reentrant, ordered or unbound |
2372 | * workqueue, @work is guaranteed to be idle on return if it hasn't |
2373 | * been requeued since flush started. |
2374 | * |
2375 | * RETURNS: |
2376 | * %true if flush_work() waited for the work to finish execution, |
2377 | * %false if it was already idle. |
2378 | */ |
2379 | bool flush_work(struct work_struct *work) |
2380 | { |
2381 | struct wq_barrier barr; |
2382 | |
2383 | if (start_flush_work(work, &barr, true)) { |
2384 | wait_for_completion(&barr.done); |
2385 | destroy_work_on_stack(&barr.work); |
2386 | return true; |
2387 | } else |
2388 | return false; |
2389 | } |
2390 | EXPORT_SYMBOL_GPL(flush_work); |
2391 | |
2392 | static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) |
2393 | { |
2394 | struct wq_barrier barr; |
2395 | struct worker *worker; |
2396 | |
2397 | spin_lock_irq(&gcwq->lock); |
2398 | |
2399 | worker = find_worker_executing_work(gcwq, work); |
2400 | if (unlikely(worker)) |
2401 | insert_wq_barrier(worker->current_cwq, &barr, work, worker); |
2402 | |
2403 | spin_unlock_irq(&gcwq->lock); |
2404 | |
2405 | if (unlikely(worker)) { |
2406 | wait_for_completion(&barr.done); |
2407 | destroy_work_on_stack(&barr.work); |
2408 | return true; |
2409 | } else |
2410 | return false; |
2411 | } |
2412 | |
2413 | static bool wait_on_work(struct work_struct *work) |
2414 | { |
2415 | bool ret = false; |
2416 | int cpu; |
2417 | |
2418 | might_sleep(); |
2419 | |
2420 | lock_map_acquire(&work->lockdep_map); |
2421 | lock_map_release(&work->lockdep_map); |
2422 | |
2423 | for_each_gcwq_cpu(cpu) |
2424 | ret |= wait_on_cpu_work(get_gcwq(cpu), work); |
2425 | return ret; |
2426 | } |
2427 | |
2428 | /** |
2429 | * flush_work_sync - wait until a work has finished execution |
2430 | * @work: the work to flush |
2431 | * |
2432 | * Wait until @work has finished execution. On return, it's |
2433 | * guaranteed that all queueing instances of @work which happened |
2434 | * before this function is called are finished. In other words, if |
2435 | * @work hasn't been requeued since this function was called, @work is |
2436 | * guaranteed to be idle on return. |
2437 | * |
2438 | * RETURNS: |
2439 | * %true if flush_work_sync() waited for the work to finish execution, |
2440 | * %false if it was already idle. |
2441 | */ |
2442 | bool flush_work_sync(struct work_struct *work) |
2443 | { |
2444 | struct wq_barrier barr; |
2445 | bool pending, waited; |
2446 | |
2447 | /* we'll wait for executions separately, queue barr only if pending */ |
2448 | pending = start_flush_work(work, &barr, false); |
2449 | |
2450 | /* wait for executions to finish */ |
2451 | waited = wait_on_work(work); |
2452 | |
2453 | /* wait for the pending one */ |
2454 | if (pending) { |
2455 | wait_for_completion(&barr.done); |
2456 | destroy_work_on_stack(&barr.work); |
2457 | } |
2458 | |
2459 | return pending || waited; |
2460 | } |
2461 | EXPORT_SYMBOL_GPL(flush_work_sync); |
2462 | |
2463 | /* |
2464 | * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, |
2465 | * so this work can't be re-armed in any way. |
2466 | */ |
2467 | static int try_to_grab_pending(struct work_struct *work) |
2468 | { |
2469 | struct global_cwq *gcwq; |
2470 | int ret = -1; |
2471 | |
2472 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
2473 | return 0; |
2474 | |
2475 | /* |
2476 | * The queueing is in progress, or it is already queued. Try to |
2477 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
2478 | */ |
2479 | gcwq = get_work_gcwq(work); |
2480 | if (!gcwq) |
2481 | return ret; |
2482 | |
2483 | spin_lock_irq(&gcwq->lock); |
2484 | if (!list_empty(&work->entry)) { |
2485 | /* |
2486 | * This work is queued, but perhaps we locked the wrong gcwq. |
2487 | * In that case we must see the new value after rmb(), see |
2488 | * insert_work()->wmb(). |
2489 | */ |
2490 | smp_rmb(); |
2491 | if (gcwq == get_work_gcwq(work)) { |
2492 | debug_work_deactivate(work); |
2493 | list_del_init(&work->entry); |
2494 | cwq_dec_nr_in_flight(get_work_cwq(work), |
2495 | get_work_color(work), |
2496 | *work_data_bits(work) & WORK_STRUCT_DELAYED); |
2497 | ret = 1; |
2498 | } |
2499 | } |
2500 | spin_unlock_irq(&gcwq->lock); |
2501 | |
2502 | return ret; |
2503 | } |
2504 | |
2505 | static bool __cancel_work_timer(struct work_struct *work, |
2506 | struct timer_list* timer) |
2507 | { |
2508 | int ret; |
2509 | |
2510 | do { |
2511 | ret = (timer && likely(del_timer(timer))); |
2512 | if (!ret) |
2513 | ret = try_to_grab_pending(work); |
2514 | wait_on_work(work); |
2515 | } while (unlikely(ret < 0)); |
2516 | |
2517 | clear_work_data(work); |
2518 | return ret; |
2519 | } |
2520 | |
2521 | /** |
2522 | * cancel_work_sync - cancel a work and wait for it to finish |
2523 | * @work: the work to cancel |
2524 | * |
2525 | * Cancel @work and wait for its execution to finish. This function |
2526 | * can be used even if the work re-queues itself or migrates to |
2527 | * another workqueue. On return from this function, @work is |
2528 | * guaranteed to be not pending or executing on any CPU. |
2529 | * |
2530 | * cancel_work_sync(&delayed_work->work) must not be used for |
2531 | * delayed_work's. Use cancel_delayed_work_sync() instead. |
2532 | * |
2533 | * The caller must ensure that the workqueue on which @work was last |
2534 | * queued can't be destroyed before this function returns. |
2535 | * |
2536 | * RETURNS: |
2537 | * %true if @work was pending, %false otherwise. |
2538 | */ |
2539 | bool cancel_work_sync(struct work_struct *work) |
2540 | { |
2541 | return __cancel_work_timer(work, NULL); |
2542 | } |
2543 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
2544 | |
2545 | /** |
2546 | * flush_delayed_work - wait for a dwork to finish executing the last queueing |
2547 | * @dwork: the delayed work to flush |
2548 | * |
2549 | * Delayed timer is cancelled and the pending work is queued for |
2550 | * immediate execution. Like flush_work(), this function only |
2551 | * considers the last queueing instance of @dwork. |
2552 | * |
2553 | * RETURNS: |
2554 | * %true if flush_work() waited for the work to finish execution, |
2555 | * %false if it was already idle. |
2556 | */ |
2557 | bool flush_delayed_work(struct delayed_work *dwork) |
2558 | { |
2559 | if (del_timer_sync(&dwork->timer)) |
2560 | __queue_work(raw_smp_processor_id(), |
2561 | get_work_cwq(&dwork->work)->wq, &dwork->work); |
2562 | return flush_work(&dwork->work); |
2563 | } |
2564 | EXPORT_SYMBOL(flush_delayed_work); |
2565 | |
2566 | /** |
2567 | * flush_delayed_work_sync - wait for a dwork to finish |
2568 | * @dwork: the delayed work to flush |
2569 | * |
2570 | * Delayed timer is cancelled and the pending work is queued for |
2571 | * execution immediately. Other than timer handling, its behavior |
2572 | * is identical to flush_work_sync(). |
2573 | * |
2574 | * RETURNS: |
2575 | * %true if flush_work_sync() waited for the work to finish execution, |
2576 | * %false if it was already idle. |
2577 | */ |
2578 | bool flush_delayed_work_sync(struct delayed_work *dwork) |
2579 | { |
2580 | if (del_timer_sync(&dwork->timer)) |
2581 | __queue_work(raw_smp_processor_id(), |
2582 | get_work_cwq(&dwork->work)->wq, &dwork->work); |
2583 | return flush_work_sync(&dwork->work); |
2584 | } |
2585 | EXPORT_SYMBOL(flush_delayed_work_sync); |
2586 | |
2587 | /** |
2588 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish |
2589 | * @dwork: the delayed work cancel |
2590 | * |
2591 | * This is cancel_work_sync() for delayed works. |
2592 | * |
2593 | * RETURNS: |
2594 | * %true if @dwork was pending, %false otherwise. |
2595 | */ |
2596 | bool cancel_delayed_work_sync(struct delayed_work *dwork) |
2597 | { |
2598 | return __cancel_work_timer(&dwork->work, &dwork->timer); |
2599 | } |
2600 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
2601 | |
2602 | /** |
2603 | * schedule_work - put work task in global workqueue |
2604 | * @work: job to be done |
2605 | * |
2606 | * Returns zero if @work was already on the kernel-global workqueue and |
2607 | * non-zero otherwise. |
2608 | * |
2609 | * This puts a job in the kernel-global workqueue if it was not already |
2610 | * queued and leaves it in the same position on the kernel-global |
2611 | * workqueue otherwise. |
2612 | */ |
2613 | int schedule_work(struct work_struct *work) |
2614 | { |
2615 | return queue_work(system_wq, work); |
2616 | } |
2617 | EXPORT_SYMBOL(schedule_work); |
2618 | |
2619 | /* |
2620 | * schedule_work_on - put work task on a specific cpu |
2621 | * @cpu: cpu to put the work task on |
2622 | * @work: job to be done |
2623 | * |
2624 | * This puts a job on a specific cpu |
2625 | */ |
2626 | int schedule_work_on(int cpu, struct work_struct *work) |
2627 | { |
2628 | return queue_work_on(cpu, system_wq, work); |
2629 | } |
2630 | EXPORT_SYMBOL(schedule_work_on); |
2631 | |
2632 | /** |
2633 | * schedule_delayed_work - put work task in global workqueue after delay |
2634 | * @dwork: job to be done |
2635 | * @delay: number of jiffies to wait or 0 for immediate execution |
2636 | * |
2637 | * After waiting for a given time this puts a job in the kernel-global |
2638 | * workqueue. |
2639 | */ |
2640 | int schedule_delayed_work(struct delayed_work *dwork, |
2641 | unsigned long delay) |
2642 | { |
2643 | return queue_delayed_work(system_wq, dwork, delay); |
2644 | } |
2645 | EXPORT_SYMBOL(schedule_delayed_work); |
2646 | |
2647 | /** |
2648 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay |
2649 | * @cpu: cpu to use |
2650 | * @dwork: job to be done |
2651 | * @delay: number of jiffies to wait |
2652 | * |
2653 | * After waiting for a given time this puts a job in the kernel-global |
2654 | * workqueue on the specified CPU. |
2655 | */ |
2656 | int schedule_delayed_work_on(int cpu, |
2657 | struct delayed_work *dwork, unsigned long delay) |
2658 | { |
2659 | return queue_delayed_work_on(cpu, system_wq, dwork, delay); |
2660 | } |
2661 | EXPORT_SYMBOL(schedule_delayed_work_on); |
2662 | |
2663 | /** |
2664 | * schedule_on_each_cpu - execute a function synchronously on each online CPU |
2665 | * @func: the function to call |
2666 | * |
2667 | * schedule_on_each_cpu() executes @func on each online CPU using the |
2668 | * system workqueue and blocks until all CPUs have completed. |
2669 | * schedule_on_each_cpu() is very slow. |
2670 | * |
2671 | * RETURNS: |
2672 | * 0 on success, -errno on failure. |
2673 | */ |
2674 | int schedule_on_each_cpu(work_func_t func) |
2675 | { |
2676 | int cpu; |
2677 | struct work_struct __percpu *works; |
2678 | |
2679 | works = alloc_percpu(struct work_struct); |
2680 | if (!works) |
2681 | return -ENOMEM; |
2682 | |
2683 | get_online_cpus(); |
2684 | |
2685 | for_each_online_cpu(cpu) { |
2686 | struct work_struct *work = per_cpu_ptr(works, cpu); |
2687 | |
2688 | INIT_WORK(work, func); |
2689 | schedule_work_on(cpu, work); |
2690 | } |
2691 | |
2692 | for_each_online_cpu(cpu) |
2693 | flush_work(per_cpu_ptr(works, cpu)); |
2694 | |
2695 | put_online_cpus(); |
2696 | free_percpu(works); |
2697 | return 0; |
2698 | } |
2699 | |
2700 | /** |
2701 | * flush_scheduled_work - ensure that any scheduled work has run to completion. |
2702 | * |
2703 | * Forces execution of the kernel-global workqueue and blocks until its |
2704 | * completion. |
2705 | * |
2706 | * Think twice before calling this function! It's very easy to get into |
2707 | * trouble if you don't take great care. Either of the following situations |
2708 | * will lead to deadlock: |
2709 | * |
2710 | * One of the work items currently on the workqueue needs to acquire |
2711 | * a lock held by your code or its caller. |
2712 | * |
2713 | * Your code is running in the context of a work routine. |
2714 | * |
2715 | * They will be detected by lockdep when they occur, but the first might not |
2716 | * occur very often. It depends on what work items are on the workqueue and |
2717 | * what locks they need, which you have no control over. |
2718 | * |
2719 | * In most situations flushing the entire workqueue is overkill; you merely |
2720 | * need to know that a particular work item isn't queued and isn't running. |
2721 | * In such cases you should use cancel_delayed_work_sync() or |
2722 | * cancel_work_sync() instead. |
2723 | */ |
2724 | void flush_scheduled_work(void) |
2725 | { |
2726 | flush_workqueue(system_wq); |
2727 | } |
2728 | EXPORT_SYMBOL(flush_scheduled_work); |
2729 | |
2730 | /** |
2731 | * execute_in_process_context - reliably execute the routine with user context |
2732 | * @fn: the function to execute |
2733 | * @ew: guaranteed storage for the execute work structure (must |
2734 | * be available when the work executes) |
2735 | * |
2736 | * Executes the function immediately if process context is available, |
2737 | * otherwise schedules the function for delayed execution. |
2738 | * |
2739 | * Returns: 0 - function was executed |
2740 | * 1 - function was scheduled for execution |
2741 | */ |
2742 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
2743 | { |
2744 | if (!in_interrupt()) { |
2745 | fn(&ew->work); |
2746 | return 0; |
2747 | } |
2748 | |
2749 | INIT_WORK(&ew->work, fn); |
2750 | schedule_work(&ew->work); |
2751 | |
2752 | return 1; |
2753 | } |
2754 | EXPORT_SYMBOL_GPL(execute_in_process_context); |
2755 | |
2756 | int keventd_up(void) |
2757 | { |
2758 | return system_wq != NULL; |
2759 | } |
2760 | |
2761 | static int alloc_cwqs(struct workqueue_struct *wq) |
2762 | { |
2763 | /* |
2764 | * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. |
2765 | * Make sure that the alignment isn't lower than that of |
2766 | * unsigned long long. |
2767 | */ |
2768 | const size_t size = sizeof(struct cpu_workqueue_struct); |
2769 | const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, |
2770 | __alignof__(unsigned long long)); |
2771 | #ifdef CONFIG_SMP |
2772 | bool percpu = !(wq->flags & WQ_UNBOUND); |
2773 | #else |
2774 | bool percpu = false; |
2775 | #endif |
2776 | |
2777 | if (percpu) |
2778 | wq->cpu_wq.pcpu = __alloc_percpu(size, align); |
2779 | else { |
2780 | void *ptr; |
2781 | |
2782 | /* |
2783 | * Allocate enough room to align cwq and put an extra |
2784 | * pointer at the end pointing back to the originally |
2785 | * allocated pointer which will be used for free. |
2786 | */ |
2787 | ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); |
2788 | if (ptr) { |
2789 | wq->cpu_wq.single = PTR_ALIGN(ptr, align); |
2790 | *(void **)(wq->cpu_wq.single + 1) = ptr; |
2791 | } |
2792 | } |
2793 | |
2794 | /* just in case, make sure it's actually aligned |
2795 | * - this is affected by PERCPU() alignment in vmlinux.lds.S |
2796 | */ |
2797 | BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); |
2798 | return wq->cpu_wq.v ? 0 : -ENOMEM; |
2799 | } |
2800 | |
2801 | static void free_cwqs(struct workqueue_struct *wq) |
2802 | { |
2803 | #ifdef CONFIG_SMP |
2804 | bool percpu = !(wq->flags & WQ_UNBOUND); |
2805 | #else |
2806 | bool percpu = false; |
2807 | #endif |
2808 | |
2809 | if (percpu) |
2810 | free_percpu(wq->cpu_wq.pcpu); |
2811 | else if (wq->cpu_wq.single) { |
2812 | /* the pointer to free is stored right after the cwq */ |
2813 | kfree(*(void **)(wq->cpu_wq.single + 1)); |
2814 | } |
2815 | } |
2816 | |
2817 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
2818 | const char *name) |
2819 | { |
2820 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
2821 | |
2822 | if (max_active < 1 || max_active > lim) |
2823 | printk(KERN_WARNING "workqueue: max_active %d requested for %s " |
2824 | "is out of range, clamping between %d and %d\n", |
2825 | max_active, name, 1, lim); |
2826 | |
2827 | return clamp_val(max_active, 1, lim); |
2828 | } |
2829 | |
2830 | struct workqueue_struct *__alloc_workqueue_key(const char *name, |
2831 | unsigned int flags, |
2832 | int max_active, |
2833 | struct lock_class_key *key, |
2834 | const char *lock_name) |
2835 | { |
2836 | struct workqueue_struct *wq; |
2837 | unsigned int cpu; |
2838 | |
2839 | /* |
2840 | * Workqueues which may be used during memory reclaim should |
2841 | * have a rescuer to guarantee forward progress. |
2842 | */ |
2843 | if (flags & WQ_MEM_RECLAIM) |
2844 | flags |= WQ_RESCUER; |
2845 | |
2846 | /* |
2847 | * Unbound workqueues aren't concurrency managed and should be |
2848 | * dispatched to workers immediately. |
2849 | */ |
2850 | if (flags & WQ_UNBOUND) |
2851 | flags |= WQ_HIGHPRI; |
2852 | |
2853 | max_active = max_active ?: WQ_DFL_ACTIVE; |
2854 | max_active = wq_clamp_max_active(max_active, flags, name); |
2855 | |
2856 | wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
2857 | if (!wq) |
2858 | goto err; |
2859 | |
2860 | wq->flags = flags; |
2861 | wq->saved_max_active = max_active; |
2862 | mutex_init(&wq->flush_mutex); |
2863 | atomic_set(&wq->nr_cwqs_to_flush, 0); |
2864 | INIT_LIST_HEAD(&wq->flusher_queue); |
2865 | INIT_LIST_HEAD(&wq->flusher_overflow); |
2866 | |
2867 | wq->name = name; |
2868 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
2869 | INIT_LIST_HEAD(&wq->list); |
2870 | |
2871 | if (alloc_cwqs(wq) < 0) |
2872 | goto err; |
2873 | |
2874 | for_each_cwq_cpu(cpu, wq) { |
2875 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2876 | struct global_cwq *gcwq = get_gcwq(cpu); |
2877 | |
2878 | BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); |
2879 | cwq->gcwq = gcwq; |
2880 | cwq->wq = wq; |
2881 | cwq->flush_color = -1; |
2882 | cwq->max_active = max_active; |
2883 | INIT_LIST_HEAD(&cwq->delayed_works); |
2884 | } |
2885 | |
2886 | if (flags & WQ_RESCUER) { |
2887 | struct worker *rescuer; |
2888 | |
2889 | if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) |
2890 | goto err; |
2891 | |
2892 | wq->rescuer = rescuer = alloc_worker(); |
2893 | if (!rescuer) |
2894 | goto err; |
2895 | |
2896 | rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); |
2897 | if (IS_ERR(rescuer->task)) |
2898 | goto err; |
2899 | |
2900 | rescuer->task->flags |= PF_THREAD_BOUND; |
2901 | wake_up_process(rescuer->task); |
2902 | } |
2903 | |
2904 | /* |
2905 | * workqueue_lock protects global freeze state and workqueues |
2906 | * list. Grab it, set max_active accordingly and add the new |
2907 | * workqueue to workqueues list. |
2908 | */ |
2909 | spin_lock(&workqueue_lock); |
2910 | |
2911 | if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) |
2912 | for_each_cwq_cpu(cpu, wq) |
2913 | get_cwq(cpu, wq)->max_active = 0; |
2914 | |
2915 | list_add(&wq->list, &workqueues); |
2916 | |
2917 | spin_unlock(&workqueue_lock); |
2918 | |
2919 | return wq; |
2920 | err: |
2921 | if (wq) { |
2922 | free_cwqs(wq); |
2923 | free_mayday_mask(wq->mayday_mask); |
2924 | kfree(wq->rescuer); |
2925 | kfree(wq); |
2926 | } |
2927 | return NULL; |
2928 | } |
2929 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
2930 | |
2931 | /** |
2932 | * destroy_workqueue - safely terminate a workqueue |
2933 | * @wq: target workqueue |
2934 | * |
2935 | * Safely destroy a workqueue. All work currently pending will be done first. |
2936 | */ |
2937 | void destroy_workqueue(struct workqueue_struct *wq) |
2938 | { |
2939 | unsigned int cpu; |
2940 | |
2941 | wq->flags |= WQ_DYING; |
2942 | flush_workqueue(wq); |
2943 | |
2944 | /* |
2945 | * wq list is used to freeze wq, remove from list after |
2946 | * flushing is complete in case freeze races us. |
2947 | */ |
2948 | spin_lock(&workqueue_lock); |
2949 | list_del(&wq->list); |
2950 | spin_unlock(&workqueue_lock); |
2951 | |
2952 | /* sanity check */ |
2953 | for_each_cwq_cpu(cpu, wq) { |
2954 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2955 | int i; |
2956 | |
2957 | for (i = 0; i < WORK_NR_COLORS; i++) |
2958 | BUG_ON(cwq->nr_in_flight[i]); |
2959 | BUG_ON(cwq->nr_active); |
2960 | BUG_ON(!list_empty(&cwq->delayed_works)); |
2961 | } |
2962 | |
2963 | if (wq->flags & WQ_RESCUER) { |
2964 | kthread_stop(wq->rescuer->task); |
2965 | free_mayday_mask(wq->mayday_mask); |
2966 | kfree(wq->rescuer); |
2967 | } |
2968 | |
2969 | free_cwqs(wq); |
2970 | kfree(wq); |
2971 | } |
2972 | EXPORT_SYMBOL_GPL(destroy_workqueue); |
2973 | |
2974 | /** |
2975 | * workqueue_set_max_active - adjust max_active of a workqueue |
2976 | * @wq: target workqueue |
2977 | * @max_active: new max_active value. |
2978 | * |
2979 | * Set max_active of @wq to @max_active. |
2980 | * |
2981 | * CONTEXT: |
2982 | * Don't call from IRQ context. |
2983 | */ |
2984 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
2985 | { |
2986 | unsigned int cpu; |
2987 | |
2988 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
2989 | |
2990 | spin_lock(&workqueue_lock); |
2991 | |
2992 | wq->saved_max_active = max_active; |
2993 | |
2994 | for_each_cwq_cpu(cpu, wq) { |
2995 | struct global_cwq *gcwq = get_gcwq(cpu); |
2996 | |
2997 | spin_lock_irq(&gcwq->lock); |
2998 | |
2999 | if (!(wq->flags & WQ_FREEZEABLE) || |
3000 | !(gcwq->flags & GCWQ_FREEZING)) |
3001 | get_cwq(gcwq->cpu, wq)->max_active = max_active; |
3002 | |
3003 | spin_unlock_irq(&gcwq->lock); |
3004 | } |
3005 | |
3006 | spin_unlock(&workqueue_lock); |
3007 | } |
3008 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
3009 | |
3010 | /** |
3011 | * workqueue_congested - test whether a workqueue is congested |
3012 | * @cpu: CPU in question |
3013 | * @wq: target workqueue |
3014 | * |
3015 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
3016 | * no synchronization around this function and the test result is |
3017 | * unreliable and only useful as advisory hints or for debugging. |
3018 | * |
3019 | * RETURNS: |
3020 | * %true if congested, %false otherwise. |
3021 | */ |
3022 | bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) |
3023 | { |
3024 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3025 | |
3026 | return !list_empty(&cwq->delayed_works); |
3027 | } |
3028 | EXPORT_SYMBOL_GPL(workqueue_congested); |
3029 | |
3030 | /** |
3031 | * work_cpu - return the last known associated cpu for @work |
3032 | * @work: the work of interest |
3033 | * |
3034 | * RETURNS: |
3035 | * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. |
3036 | */ |
3037 | unsigned int work_cpu(struct work_struct *work) |
3038 | { |
3039 | struct global_cwq *gcwq = get_work_gcwq(work); |
3040 | |
3041 | return gcwq ? gcwq->cpu : WORK_CPU_NONE; |
3042 | } |
3043 | EXPORT_SYMBOL_GPL(work_cpu); |
3044 | |
3045 | /** |
3046 | * work_busy - test whether a work is currently pending or running |
3047 | * @work: the work to be tested |
3048 | * |
3049 | * Test whether @work is currently pending or running. There is no |
3050 | * synchronization around this function and the test result is |
3051 | * unreliable and only useful as advisory hints or for debugging. |
3052 | * Especially for reentrant wqs, the pending state might hide the |
3053 | * running state. |
3054 | * |
3055 | * RETURNS: |
3056 | * OR'd bitmask of WORK_BUSY_* bits. |
3057 | */ |
3058 | unsigned int work_busy(struct work_struct *work) |
3059 | { |
3060 | struct global_cwq *gcwq = get_work_gcwq(work); |
3061 | unsigned long flags; |
3062 | unsigned int ret = 0; |
3063 | |
3064 | if (!gcwq) |
3065 | return false; |
3066 | |
3067 | spin_lock_irqsave(&gcwq->lock, flags); |
3068 | |
3069 | if (work_pending(work)) |
3070 | ret |= WORK_BUSY_PENDING; |
3071 | if (find_worker_executing_work(gcwq, work)) |
3072 | ret |= WORK_BUSY_RUNNING; |
3073 | |
3074 | spin_unlock_irqrestore(&gcwq->lock, flags); |
3075 | |
3076 | return ret; |
3077 | } |
3078 | EXPORT_SYMBOL_GPL(work_busy); |
3079 | |
3080 | /* |
3081 | * CPU hotplug. |
3082 | * |
3083 | * There are two challenges in supporting CPU hotplug. Firstly, there |
3084 | * are a lot of assumptions on strong associations among work, cwq and |
3085 | * gcwq which make migrating pending and scheduled works very |
3086 | * difficult to implement without impacting hot paths. Secondly, |
3087 | * gcwqs serve mix of short, long and very long running works making |
3088 | * blocked draining impractical. |
3089 | * |
3090 | * This is solved by allowing a gcwq to be detached from CPU, running |
3091 | * it with unbound (rogue) workers and allowing it to be reattached |
3092 | * later if the cpu comes back online. A separate thread is created |
3093 | * to govern a gcwq in such state and is called the trustee of the |
3094 | * gcwq. |
3095 | * |
3096 | * Trustee states and their descriptions. |
3097 | * |
3098 | * START Command state used on startup. On CPU_DOWN_PREPARE, a |
3099 | * new trustee is started with this state. |
3100 | * |
3101 | * IN_CHARGE Once started, trustee will enter this state after |
3102 | * assuming the manager role and making all existing |
3103 | * workers rogue. DOWN_PREPARE waits for trustee to |
3104 | * enter this state. After reaching IN_CHARGE, trustee |
3105 | * tries to execute the pending worklist until it's empty |
3106 | * and the state is set to BUTCHER, or the state is set |
3107 | * to RELEASE. |
3108 | * |
3109 | * BUTCHER Command state which is set by the cpu callback after |
3110 | * the cpu has went down. Once this state is set trustee |
3111 | * knows that there will be no new works on the worklist |
3112 | * and once the worklist is empty it can proceed to |
3113 | * killing idle workers. |
3114 | * |
3115 | * RELEASE Command state which is set by the cpu callback if the |
3116 | * cpu down has been canceled or it has come online |
3117 | * again. After recognizing this state, trustee stops |
3118 | * trying to drain or butcher and clears ROGUE, rebinds |
3119 | * all remaining workers back to the cpu and releases |
3120 | * manager role. |
3121 | * |
3122 | * DONE Trustee will enter this state after BUTCHER or RELEASE |
3123 | * is complete. |
3124 | * |
3125 | * trustee CPU draining |
3126 | * took over down complete |
3127 | * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE |
3128 | * | | ^ |
3129 | * | CPU is back online v return workers | |
3130 | * ----------------> RELEASE -------------- |
3131 | */ |
3132 | |
3133 | /** |
3134 | * trustee_wait_event_timeout - timed event wait for trustee |
3135 | * @cond: condition to wait for |
3136 | * @timeout: timeout in jiffies |
3137 | * |
3138 | * wait_event_timeout() for trustee to use. Handles locking and |
3139 | * checks for RELEASE request. |
3140 | * |
3141 | * CONTEXT: |
3142 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
3143 | * multiple times. To be used by trustee. |
3144 | * |
3145 | * RETURNS: |
3146 | * Positive indicating left time if @cond is satisfied, 0 if timed |
3147 | * out, -1 if canceled. |
3148 | */ |
3149 | #define trustee_wait_event_timeout(cond, timeout) ({ \ |
3150 | long __ret = (timeout); \ |
3151 | while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ |
3152 | __ret) { \ |
3153 | spin_unlock_irq(&gcwq->lock); \ |
3154 | __wait_event_timeout(gcwq->trustee_wait, (cond) || \ |
3155 | (gcwq->trustee_state == TRUSTEE_RELEASE), \ |
3156 | __ret); \ |
3157 | spin_lock_irq(&gcwq->lock); \ |
3158 | } \ |
3159 | gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ |
3160 | }) |
3161 | |
3162 | /** |
3163 | * trustee_wait_event - event wait for trustee |
3164 | * @cond: condition to wait for |
3165 | * |
3166 | * wait_event() for trustee to use. Automatically handles locking and |
3167 | * checks for CANCEL request. |
3168 | * |
3169 | * CONTEXT: |
3170 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
3171 | * multiple times. To be used by trustee. |
3172 | * |
3173 | * RETURNS: |
3174 | * 0 if @cond is satisfied, -1 if canceled. |
3175 | */ |
3176 | #define trustee_wait_event(cond) ({ \ |
3177 | long __ret1; \ |
3178 | __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ |
3179 | __ret1 < 0 ? -1 : 0; \ |
3180 | }) |
3181 | |
3182 | static int __cpuinit trustee_thread(void *__gcwq) |
3183 | { |
3184 | struct global_cwq *gcwq = __gcwq; |
3185 | struct worker *worker; |
3186 | struct work_struct *work; |
3187 | struct hlist_node *pos; |
3188 | long rc; |
3189 | int i; |
3190 | |
3191 | BUG_ON(gcwq->cpu != smp_processor_id()); |
3192 | |
3193 | spin_lock_irq(&gcwq->lock); |
3194 | /* |
3195 | * Claim the manager position and make all workers rogue. |
3196 | * Trustee must be bound to the target cpu and can't be |
3197 | * cancelled. |
3198 | */ |
3199 | BUG_ON(gcwq->cpu != smp_processor_id()); |
3200 | rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); |
3201 | BUG_ON(rc < 0); |
3202 | |
3203 | gcwq->flags |= GCWQ_MANAGING_WORKERS; |
3204 | |
3205 | list_for_each_entry(worker, &gcwq->idle_list, entry) |
3206 | worker->flags |= WORKER_ROGUE; |
3207 | |
3208 | for_each_busy_worker(worker, i, pos, gcwq) |
3209 | worker->flags |= WORKER_ROGUE; |
3210 | |
3211 | /* |
3212 | * Call schedule() so that we cross rq->lock and thus can |
3213 | * guarantee sched callbacks see the rogue flag. This is |
3214 | * necessary as scheduler callbacks may be invoked from other |
3215 | * cpus. |
3216 | */ |
3217 | spin_unlock_irq(&gcwq->lock); |
3218 | schedule(); |
3219 | spin_lock_irq(&gcwq->lock); |
3220 | |
3221 | /* |
3222 | * Sched callbacks are disabled now. Zap nr_running. After |
3223 | * this, nr_running stays zero and need_more_worker() and |
3224 | * keep_working() are always true as long as the worklist is |
3225 | * not empty. |
3226 | */ |
3227 | atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); |
3228 | |
3229 | spin_unlock_irq(&gcwq->lock); |
3230 | del_timer_sync(&gcwq->idle_timer); |
3231 | spin_lock_irq(&gcwq->lock); |
3232 | |
3233 | /* |
3234 | * We're now in charge. Notify and proceed to drain. We need |
3235 | * to keep the gcwq running during the whole CPU down |
3236 | * procedure as other cpu hotunplug callbacks may need to |
3237 | * flush currently running tasks. |
3238 | */ |
3239 | gcwq->trustee_state = TRUSTEE_IN_CHARGE; |
3240 | wake_up_all(&gcwq->trustee_wait); |
3241 | |
3242 | /* |
3243 | * The original cpu is in the process of dying and may go away |
3244 | * anytime now. When that happens, we and all workers would |
3245 | * be migrated to other cpus. Try draining any left work. We |
3246 | * want to get it over with ASAP - spam rescuers, wake up as |
3247 | * many idlers as necessary and create new ones till the |
3248 | * worklist is empty. Note that if the gcwq is frozen, there |
3249 | * may be frozen works in freezeable cwqs. Don't declare |
3250 | * completion while frozen. |
3251 | */ |
3252 | while (gcwq->nr_workers != gcwq->nr_idle || |
3253 | gcwq->flags & GCWQ_FREEZING || |
3254 | gcwq->trustee_state == TRUSTEE_IN_CHARGE) { |
3255 | int nr_works = 0; |
3256 | |
3257 | list_for_each_entry(work, &gcwq->worklist, entry) { |
3258 | send_mayday(work); |
3259 | nr_works++; |
3260 | } |
3261 | |
3262 | list_for_each_entry(worker, &gcwq->idle_list, entry) { |
3263 | if (!nr_works--) |
3264 | break; |
3265 | wake_up_process(worker->task); |
3266 | } |
3267 | |
3268 | if (need_to_create_worker(gcwq)) { |
3269 | spin_unlock_irq(&gcwq->lock); |
3270 | worker = create_worker(gcwq, false); |
3271 | spin_lock_irq(&gcwq->lock); |
3272 | if (worker) { |
3273 | worker->flags |= WORKER_ROGUE; |
3274 | start_worker(worker); |
3275 | } |
3276 | } |
3277 | |
3278 | /* give a breather */ |
3279 | if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) |
3280 | break; |
3281 | } |
3282 | |
3283 | /* |
3284 | * Either all works have been scheduled and cpu is down, or |
3285 | * cpu down has already been canceled. Wait for and butcher |
3286 | * all workers till we're canceled. |
3287 | */ |
3288 | do { |
3289 | rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); |
3290 | while (!list_empty(&gcwq->idle_list)) |
3291 | destroy_worker(list_first_entry(&gcwq->idle_list, |
3292 | struct worker, entry)); |
3293 | } while (gcwq->nr_workers && rc >= 0); |
3294 | |
3295 | /* |
3296 | * At this point, either draining has completed and no worker |
3297 | * is left, or cpu down has been canceled or the cpu is being |
3298 | * brought back up. There shouldn't be any idle one left. |
3299 | * Tell the remaining busy ones to rebind once it finishes the |
3300 | * currently scheduled works by scheduling the rebind_work. |
3301 | */ |
3302 | WARN_ON(!list_empty(&gcwq->idle_list)); |
3303 | |
3304 | for_each_busy_worker(worker, i, pos, gcwq) { |
3305 | struct work_struct *rebind_work = &worker->rebind_work; |
3306 | |
3307 | /* |
3308 | * Rebind_work may race with future cpu hotplug |
3309 | * operations. Use a separate flag to mark that |
3310 | * rebinding is scheduled. |
3311 | */ |
3312 | worker->flags |= WORKER_REBIND; |
3313 | worker->flags &= ~WORKER_ROGUE; |
3314 | |
3315 | /* queue rebind_work, wq doesn't matter, use the default one */ |
3316 | if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, |
3317 | work_data_bits(rebind_work))) |
3318 | continue; |
3319 | |
3320 | debug_work_activate(rebind_work); |
3321 | insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, |
3322 | worker->scheduled.next, |
3323 | work_color_to_flags(WORK_NO_COLOR)); |
3324 | } |
3325 | |
3326 | /* relinquish manager role */ |
3327 | gcwq->flags &= ~GCWQ_MANAGING_WORKERS; |
3328 | |
3329 | /* notify completion */ |
3330 | gcwq->trustee = NULL; |
3331 | gcwq->trustee_state = TRUSTEE_DONE; |
3332 | wake_up_all(&gcwq->trustee_wait); |
3333 | spin_unlock_irq(&gcwq->lock); |
3334 | return 0; |
3335 | } |
3336 | |
3337 | /** |
3338 | * wait_trustee_state - wait for trustee to enter the specified state |
3339 | * @gcwq: gcwq the trustee of interest belongs to |
3340 | * @state: target state to wait for |
3341 | * |
3342 | * Wait for the trustee to reach @state. DONE is already matched. |
3343 | * |
3344 | * CONTEXT: |
3345 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
3346 | * multiple times. To be used by cpu_callback. |
3347 | */ |
3348 | static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) |
3349 | __releases(&gcwq->lock) |
3350 | __acquires(&gcwq->lock) |
3351 | { |
3352 | if (!(gcwq->trustee_state == state || |
3353 | gcwq->trustee_state == TRUSTEE_DONE)) { |
3354 | spin_unlock_irq(&gcwq->lock); |
3355 | __wait_event(gcwq->trustee_wait, |
3356 | gcwq->trustee_state == state || |
3357 | gcwq->trustee_state == TRUSTEE_DONE); |
3358 | spin_lock_irq(&gcwq->lock); |
3359 | } |
3360 | } |
3361 | |
3362 | static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, |
3363 | unsigned long action, |
3364 | void *hcpu) |
3365 | { |
3366 | unsigned int cpu = (unsigned long)hcpu; |
3367 | struct global_cwq *gcwq = get_gcwq(cpu); |
3368 | struct task_struct *new_trustee = NULL; |
3369 | struct worker *uninitialized_var(new_worker); |
3370 | unsigned long flags; |
3371 | |
3372 | action &= ~CPU_TASKS_FROZEN; |
3373 | |
3374 | switch (action) { |
3375 | case CPU_DOWN_PREPARE: |
3376 | new_trustee = kthread_create(trustee_thread, gcwq, |
3377 | "workqueue_trustee/%d\n", cpu); |
3378 | if (IS_ERR(new_trustee)) |
3379 | return notifier_from_errno(PTR_ERR(new_trustee)); |
3380 | kthread_bind(new_trustee, cpu); |
3381 | /* fall through */ |
3382 | case CPU_UP_PREPARE: |
3383 | BUG_ON(gcwq->first_idle); |
3384 | new_worker = create_worker(gcwq, false); |
3385 | if (!new_worker) { |
3386 | if (new_trustee) |
3387 | kthread_stop(new_trustee); |
3388 | return NOTIFY_BAD; |
3389 | } |
3390 | } |
3391 | |
3392 | /* some are called w/ irq disabled, don't disturb irq status */ |
3393 | spin_lock_irqsave(&gcwq->lock, flags); |
3394 | |
3395 | switch (action) { |
3396 | case CPU_DOWN_PREPARE: |
3397 | /* initialize trustee and tell it to acquire the gcwq */ |
3398 | BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); |
3399 | gcwq->trustee = new_trustee; |
3400 | gcwq->trustee_state = TRUSTEE_START; |
3401 | wake_up_process(gcwq->trustee); |
3402 | wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); |
3403 | /* fall through */ |
3404 | case CPU_UP_PREPARE: |
3405 | BUG_ON(gcwq->first_idle); |
3406 | gcwq->first_idle = new_worker; |
3407 | break; |
3408 | |
3409 | case CPU_DYING: |
3410 | /* |
3411 | * Before this, the trustee and all workers except for |
3412 | * the ones which are still executing works from |
3413 | * before the last CPU down must be on the cpu. After |
3414 | * this, they'll all be diasporas. |
3415 | */ |
3416 | gcwq->flags |= GCWQ_DISASSOCIATED; |
3417 | break; |
3418 | |
3419 | case CPU_POST_DEAD: |
3420 | gcwq->trustee_state = TRUSTEE_BUTCHER; |
3421 | /* fall through */ |
3422 | case CPU_UP_CANCELED: |
3423 | destroy_worker(gcwq->first_idle); |
3424 | gcwq->first_idle = NULL; |
3425 | break; |
3426 | |
3427 | case CPU_DOWN_FAILED: |
3428 | case CPU_ONLINE: |
3429 | gcwq->flags &= ~GCWQ_DISASSOCIATED; |
3430 | if (gcwq->trustee_state != TRUSTEE_DONE) { |
3431 | gcwq->trustee_state = TRUSTEE_RELEASE; |
3432 | wake_up_process(gcwq->trustee); |
3433 | wait_trustee_state(gcwq, TRUSTEE_DONE); |
3434 | } |
3435 | |
3436 | /* |
3437 | * Trustee is done and there might be no worker left. |
3438 | * Put the first_idle in and request a real manager to |
3439 | * take a look. |
3440 | */ |
3441 | spin_unlock_irq(&gcwq->lock); |
3442 | kthread_bind(gcwq->first_idle->task, cpu); |
3443 | spin_lock_irq(&gcwq->lock); |
3444 | gcwq->flags |= GCWQ_MANAGE_WORKERS; |
3445 | start_worker(gcwq->first_idle); |
3446 | gcwq->first_idle = NULL; |
3447 | break; |
3448 | } |
3449 | |
3450 | spin_unlock_irqrestore(&gcwq->lock, flags); |
3451 | |
3452 | return notifier_from_errno(0); |
3453 | } |
3454 | |
3455 | #ifdef CONFIG_SMP |
3456 | |
3457 | struct work_for_cpu { |
3458 | struct completion completion; |
3459 | long (*fn)(void *); |
3460 | void *arg; |
3461 | long ret; |
3462 | }; |
3463 | |
3464 | static int do_work_for_cpu(void *_wfc) |
3465 | { |
3466 | struct work_for_cpu *wfc = _wfc; |
3467 | wfc->ret = wfc->fn(wfc->arg); |
3468 | complete(&wfc->completion); |
3469 | return 0; |
3470 | } |
3471 | |
3472 | /** |
3473 | * work_on_cpu - run a function in user context on a particular cpu |
3474 | * @cpu: the cpu to run on |
3475 | * @fn: the function to run |
3476 | * @arg: the function arg |
3477 | * |
3478 | * This will return the value @fn returns. |
3479 | * It is up to the caller to ensure that the cpu doesn't go offline. |
3480 | * The caller must not hold any locks which would prevent @fn from completing. |
3481 | */ |
3482 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) |
3483 | { |
3484 | struct task_struct *sub_thread; |
3485 | struct work_for_cpu wfc = { |
3486 | .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), |
3487 | .fn = fn, |
3488 | .arg = arg, |
3489 | }; |
3490 | |
3491 | sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); |
3492 | if (IS_ERR(sub_thread)) |
3493 | return PTR_ERR(sub_thread); |
3494 | kthread_bind(sub_thread, cpu); |
3495 | wake_up_process(sub_thread); |
3496 | wait_for_completion(&wfc.completion); |
3497 | return wfc.ret; |
3498 | } |
3499 | EXPORT_SYMBOL_GPL(work_on_cpu); |
3500 | #endif /* CONFIG_SMP */ |
3501 | |
3502 | #ifdef CONFIG_FREEZER |
3503 | |
3504 | /** |
3505 | * freeze_workqueues_begin - begin freezing workqueues |
3506 | * |
3507 | * Start freezing workqueues. After this function returns, all |
3508 | * freezeable workqueues will queue new works to their frozen_works |
3509 | * list instead of gcwq->worklist. |
3510 | * |
3511 | * CONTEXT: |
3512 | * Grabs and releases workqueue_lock and gcwq->lock's. |
3513 | */ |
3514 | void freeze_workqueues_begin(void) |
3515 | { |
3516 | unsigned int cpu; |
3517 | |
3518 | spin_lock(&workqueue_lock); |
3519 | |
3520 | BUG_ON(workqueue_freezing); |
3521 | workqueue_freezing = true; |
3522 | |
3523 | for_each_gcwq_cpu(cpu) { |
3524 | struct global_cwq *gcwq = get_gcwq(cpu); |
3525 | struct workqueue_struct *wq; |
3526 | |
3527 | spin_lock_irq(&gcwq->lock); |
3528 | |
3529 | BUG_ON(gcwq->flags & GCWQ_FREEZING); |
3530 | gcwq->flags |= GCWQ_FREEZING; |
3531 | |
3532 | list_for_each_entry(wq, &workqueues, list) { |
3533 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3534 | |
3535 | if (cwq && wq->flags & WQ_FREEZEABLE) |
3536 | cwq->max_active = 0; |
3537 | } |
3538 | |
3539 | spin_unlock_irq(&gcwq->lock); |
3540 | } |
3541 | |
3542 | spin_unlock(&workqueue_lock); |
3543 | } |
3544 | |
3545 | /** |
3546 | * freeze_workqueues_busy - are freezeable workqueues still busy? |
3547 | * |
3548 | * Check whether freezing is complete. This function must be called |
3549 | * between freeze_workqueues_begin() and thaw_workqueues(). |
3550 | * |
3551 | * CONTEXT: |
3552 | * Grabs and releases workqueue_lock. |
3553 | * |
3554 | * RETURNS: |
3555 | * %true if some freezeable workqueues are still busy. %false if |
3556 | * freezing is complete. |
3557 | */ |
3558 | bool freeze_workqueues_busy(void) |
3559 | { |
3560 | unsigned int cpu; |
3561 | bool busy = false; |
3562 | |
3563 | spin_lock(&workqueue_lock); |
3564 | |
3565 | BUG_ON(!workqueue_freezing); |
3566 | |
3567 | for_each_gcwq_cpu(cpu) { |
3568 | struct workqueue_struct *wq; |
3569 | /* |
3570 | * nr_active is monotonically decreasing. It's safe |
3571 | * to peek without lock. |
3572 | */ |
3573 | list_for_each_entry(wq, &workqueues, list) { |
3574 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3575 | |
3576 | if (!cwq || !(wq->flags & WQ_FREEZEABLE)) |
3577 | continue; |
3578 | |
3579 | BUG_ON(cwq->nr_active < 0); |
3580 | if (cwq->nr_active) { |
3581 | busy = true; |
3582 | goto out_unlock; |
3583 | } |
3584 | } |
3585 | } |
3586 | out_unlock: |
3587 | spin_unlock(&workqueue_lock); |
3588 | return busy; |
3589 | } |
3590 | |
3591 | /** |
3592 | * thaw_workqueues - thaw workqueues |
3593 | * |
3594 | * Thaw workqueues. Normal queueing is restored and all collected |
3595 | * frozen works are transferred to their respective gcwq worklists. |
3596 | * |
3597 | * CONTEXT: |
3598 | * Grabs and releases workqueue_lock and gcwq->lock's. |
3599 | */ |
3600 | void thaw_workqueues(void) |
3601 | { |
3602 | unsigned int cpu; |
3603 | |
3604 | spin_lock(&workqueue_lock); |
3605 | |
3606 | if (!workqueue_freezing) |
3607 | goto out_unlock; |
3608 | |
3609 | for_each_gcwq_cpu(cpu) { |
3610 | struct global_cwq *gcwq = get_gcwq(cpu); |
3611 | struct workqueue_struct *wq; |
3612 | |
3613 | spin_lock_irq(&gcwq->lock); |
3614 | |
3615 | BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); |
3616 | gcwq->flags &= ~GCWQ_FREEZING; |
3617 | |
3618 | list_for_each_entry(wq, &workqueues, list) { |
3619 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3620 | |
3621 | if (!cwq || !(wq->flags & WQ_FREEZEABLE)) |
3622 | continue; |
3623 | |
3624 | /* restore max_active and repopulate worklist */ |
3625 | cwq->max_active = wq->saved_max_active; |
3626 | |
3627 | while (!list_empty(&cwq->delayed_works) && |
3628 | cwq->nr_active < cwq->max_active) |
3629 | cwq_activate_first_delayed(cwq); |
3630 | } |
3631 | |
3632 | wake_up_worker(gcwq); |
3633 | |
3634 | spin_unlock_irq(&gcwq->lock); |
3635 | } |
3636 | |
3637 | workqueue_freezing = false; |
3638 | out_unlock: |
3639 | spin_unlock(&workqueue_lock); |
3640 | } |
3641 | #endif /* CONFIG_FREEZER */ |
3642 | |
3643 | static int __init init_workqueues(void) |
3644 | { |
3645 | unsigned int cpu; |
3646 | int i; |
3647 | |
3648 | cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); |
3649 | |
3650 | /* initialize gcwqs */ |
3651 | for_each_gcwq_cpu(cpu) { |
3652 | struct global_cwq *gcwq = get_gcwq(cpu); |
3653 | |
3654 | spin_lock_init(&gcwq->lock); |
3655 | INIT_LIST_HEAD(&gcwq->worklist); |
3656 | gcwq->cpu = cpu; |
3657 | gcwq->flags |= GCWQ_DISASSOCIATED; |
3658 | |
3659 | INIT_LIST_HEAD(&gcwq->idle_list); |
3660 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) |
3661 | INIT_HLIST_HEAD(&gcwq->busy_hash[i]); |
3662 | |
3663 | init_timer_deferrable(&gcwq->idle_timer); |
3664 | gcwq->idle_timer.function = idle_worker_timeout; |
3665 | gcwq->idle_timer.data = (unsigned long)gcwq; |
3666 | |
3667 | setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, |
3668 | (unsigned long)gcwq); |
3669 | |
3670 | ida_init(&gcwq->worker_ida); |
3671 | |
3672 | gcwq->trustee_state = TRUSTEE_DONE; |
3673 | init_waitqueue_head(&gcwq->trustee_wait); |
3674 | } |
3675 | |
3676 | /* create the initial worker */ |
3677 | for_each_online_gcwq_cpu(cpu) { |
3678 | struct global_cwq *gcwq = get_gcwq(cpu); |
3679 | struct worker *worker; |
3680 | |
3681 | if (cpu != WORK_CPU_UNBOUND) |
3682 | gcwq->flags &= ~GCWQ_DISASSOCIATED; |
3683 | worker = create_worker(gcwq, true); |
3684 | BUG_ON(!worker); |
3685 | spin_lock_irq(&gcwq->lock); |
3686 | start_worker(worker); |
3687 | spin_unlock_irq(&gcwq->lock); |
3688 | } |
3689 | |
3690 | system_wq = alloc_workqueue("events", 0, 0); |
3691 | system_long_wq = alloc_workqueue("events_long", 0, 0); |
3692 | system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); |
3693 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
3694 | WQ_UNBOUND_MAX_ACTIVE); |
3695 | BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq || |
3696 | !system_unbound_wq); |
3697 | return 0; |
3698 | } |
3699 | early_initcall(init_workqueues); |
3700 |
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