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1da177e4 LT |
1 | /* |
2 | * linux/kernel/workqueue.c | |
3 | * | |
4 | * Generic mechanism for defining kernel helper threads for running | |
5 | * arbitrary tasks in process context. | |
6 | * | |
7 | * Started by Ingo Molnar, Copyright (C) 2002 | |
8 | * | |
9 | * Derived from the taskqueue/keventd code by: | |
10 | * | |
11 | * David Woodhouse <dwmw2@infradead.org> | |
e1f8e874 | 12 | * Andrew Morton |
1da177e4 LT |
13 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
14 | * Theodore Ts'o <tytso@mit.edu> | |
89ada679 | 15 | * |
cde53535 | 16 | * Made to use alloc_percpu by Christoph Lameter. |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/module.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/sched.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/signal.h> | |
24 | #include <linux/completion.h> | |
25 | #include <linux/workqueue.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/cpu.h> | |
28 | #include <linux/notifier.h> | |
29 | #include <linux/kthread.h> | |
1fa44eca | 30 | #include <linux/hardirq.h> |
46934023 | 31 | #include <linux/mempolicy.h> |
341a5958 | 32 | #include <linux/freezer.h> |
d5abe669 PZ |
33 | #include <linux/kallsyms.h> |
34 | #include <linux/debug_locks.h> | |
4e6045f1 | 35 | #include <linux/lockdep.h> |
c34056a3 | 36 | #include <linux/idr.h> |
1da177e4 | 37 | |
c8e55f36 | 38 | enum { |
db7bccf4 TH |
39 | /* global_cwq flags */ |
40 | GCWQ_FREEZING = 1 << 3, /* freeze in progress */ | |
41 | ||
c8e55f36 TH |
42 | /* worker flags */ |
43 | WORKER_STARTED = 1 << 0, /* started */ | |
44 | WORKER_DIE = 1 << 1, /* die die die */ | |
45 | WORKER_IDLE = 1 << 2, /* is idle */ | |
db7bccf4 TH |
46 | WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ |
47 | ||
48 | /* gcwq->trustee_state */ | |
49 | TRUSTEE_START = 0, /* start */ | |
50 | TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ | |
51 | TRUSTEE_BUTCHER = 2, /* butcher workers */ | |
52 | TRUSTEE_RELEASE = 3, /* release workers */ | |
53 | TRUSTEE_DONE = 4, /* trustee is done */ | |
c8e55f36 TH |
54 | |
55 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ | |
56 | BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, | |
57 | BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, | |
db7bccf4 TH |
58 | |
59 | TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ | |
c8e55f36 TH |
60 | }; |
61 | ||
4690c4ab TH |
62 | /* |
63 | * Structure fields follow one of the following exclusion rules. | |
64 | * | |
65 | * I: Set during initialization and read-only afterwards. | |
66 | * | |
8b03ae3c | 67 | * L: gcwq->lock protected. Access with gcwq->lock held. |
4690c4ab | 68 | * |
73f53c4a TH |
69 | * F: wq->flush_mutex protected. |
70 | * | |
4690c4ab TH |
71 | * W: workqueue_lock protected. |
72 | */ | |
73 | ||
8b03ae3c | 74 | struct global_cwq; |
c34056a3 TH |
75 | struct cpu_workqueue_struct; |
76 | ||
77 | struct worker { | |
c8e55f36 TH |
78 | /* on idle list while idle, on busy hash table while busy */ |
79 | union { | |
80 | struct list_head entry; /* L: while idle */ | |
81 | struct hlist_node hentry; /* L: while busy */ | |
82 | }; | |
83 | ||
c34056a3 | 84 | struct work_struct *current_work; /* L: work being processed */ |
8cca0eea | 85 | struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ |
affee4b2 | 86 | struct list_head scheduled; /* L: scheduled works */ |
c34056a3 | 87 | struct task_struct *task; /* I: worker task */ |
8b03ae3c | 88 | struct global_cwq *gcwq; /* I: the associated gcwq */ |
c34056a3 | 89 | struct cpu_workqueue_struct *cwq; /* I: the associated cwq */ |
c8e55f36 | 90 | unsigned int flags; /* L: flags */ |
c34056a3 TH |
91 | int id; /* I: worker id */ |
92 | }; | |
93 | ||
8b03ae3c TH |
94 | /* |
95 | * Global per-cpu workqueue. | |
96 | */ | |
97 | struct global_cwq { | |
98 | spinlock_t lock; /* the gcwq lock */ | |
99 | unsigned int cpu; /* I: the associated cpu */ | |
db7bccf4 | 100 | unsigned int flags; /* L: GCWQ_* flags */ |
c8e55f36 TH |
101 | |
102 | int nr_workers; /* L: total number of workers */ | |
103 | int nr_idle; /* L: currently idle ones */ | |
104 | ||
105 | /* workers are chained either in the idle_list or busy_hash */ | |
106 | struct list_head idle_list; /* L: list of idle workers */ | |
107 | struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; | |
108 | /* L: hash of busy workers */ | |
109 | ||
8b03ae3c | 110 | struct ida worker_ida; /* L: for worker IDs */ |
db7bccf4 TH |
111 | |
112 | struct task_struct *trustee; /* L: for gcwq shutdown */ | |
113 | unsigned int trustee_state; /* L: trustee state */ | |
114 | wait_queue_head_t trustee_wait; /* trustee wait */ | |
8b03ae3c TH |
115 | } ____cacheline_aligned_in_smp; |
116 | ||
1da177e4 | 117 | /* |
502ca9d8 | 118 | * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of |
0f900049 TH |
119 | * work_struct->data are used for flags and thus cwqs need to be |
120 | * aligned at two's power of the number of flag bits. | |
1da177e4 LT |
121 | */ |
122 | struct cpu_workqueue_struct { | |
8b03ae3c | 123 | struct global_cwq *gcwq; /* I: the associated gcwq */ |
1da177e4 | 124 | struct list_head worklist; |
c34056a3 | 125 | struct worker *worker; |
4690c4ab | 126 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
73f53c4a TH |
127 | int work_color; /* L: current color */ |
128 | int flush_color; /* L: flushing color */ | |
129 | int nr_in_flight[WORK_NR_COLORS]; | |
130 | /* L: nr of in_flight works */ | |
1e19ffc6 | 131 | int nr_active; /* L: nr of active works */ |
a0a1a5fd | 132 | int max_active; /* L: max active works */ |
1e19ffc6 | 133 | struct list_head delayed_works; /* L: delayed works */ |
0f900049 | 134 | }; |
1da177e4 | 135 | |
73f53c4a TH |
136 | /* |
137 | * Structure used to wait for workqueue flush. | |
138 | */ | |
139 | struct wq_flusher { | |
140 | struct list_head list; /* F: list of flushers */ | |
141 | int flush_color; /* F: flush color waiting for */ | |
142 | struct completion done; /* flush completion */ | |
143 | }; | |
144 | ||
1da177e4 LT |
145 | /* |
146 | * The externally visible workqueue abstraction is an array of | |
147 | * per-CPU workqueues: | |
148 | */ | |
149 | struct workqueue_struct { | |
97e37d7b | 150 | unsigned int flags; /* I: WQ_* flags */ |
4690c4ab TH |
151 | struct cpu_workqueue_struct *cpu_wq; /* I: cwq's */ |
152 | struct list_head list; /* W: list of all workqueues */ | |
73f53c4a TH |
153 | |
154 | struct mutex flush_mutex; /* protects wq flushing */ | |
155 | int work_color; /* F: current work color */ | |
156 | int flush_color; /* F: current flush color */ | |
157 | atomic_t nr_cwqs_to_flush; /* flush in progress */ | |
158 | struct wq_flusher *first_flusher; /* F: first flusher */ | |
159 | struct list_head flusher_queue; /* F: flush waiters */ | |
160 | struct list_head flusher_overflow; /* F: flush overflow list */ | |
161 | ||
502ca9d8 TH |
162 | unsigned long single_cpu; /* cpu for single cpu wq */ |
163 | ||
a0a1a5fd | 164 | int saved_max_active; /* I: saved cwq max_active */ |
4690c4ab | 165 | const char *name; /* I: workqueue name */ |
4e6045f1 | 166 | #ifdef CONFIG_LOCKDEP |
4690c4ab | 167 | struct lockdep_map lockdep_map; |
4e6045f1 | 168 | #endif |
1da177e4 LT |
169 | }; |
170 | ||
db7bccf4 TH |
171 | #define for_each_busy_worker(worker, i, pos, gcwq) \ |
172 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ | |
173 | hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) | |
174 | ||
dc186ad7 TG |
175 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
176 | ||
177 | static struct debug_obj_descr work_debug_descr; | |
178 | ||
179 | /* | |
180 | * fixup_init is called when: | |
181 | * - an active object is initialized | |
182 | */ | |
183 | static int work_fixup_init(void *addr, enum debug_obj_state state) | |
184 | { | |
185 | struct work_struct *work = addr; | |
186 | ||
187 | switch (state) { | |
188 | case ODEBUG_STATE_ACTIVE: | |
189 | cancel_work_sync(work); | |
190 | debug_object_init(work, &work_debug_descr); | |
191 | return 1; | |
192 | default: | |
193 | return 0; | |
194 | } | |
195 | } | |
196 | ||
197 | /* | |
198 | * fixup_activate is called when: | |
199 | * - an active object is activated | |
200 | * - an unknown object is activated (might be a statically initialized object) | |
201 | */ | |
202 | static int work_fixup_activate(void *addr, enum debug_obj_state state) | |
203 | { | |
204 | struct work_struct *work = addr; | |
205 | ||
206 | switch (state) { | |
207 | ||
208 | case ODEBUG_STATE_NOTAVAILABLE: | |
209 | /* | |
210 | * This is not really a fixup. The work struct was | |
211 | * statically initialized. We just make sure that it | |
212 | * is tracked in the object tracker. | |
213 | */ | |
22df02bb | 214 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
dc186ad7 TG |
215 | debug_object_init(work, &work_debug_descr); |
216 | debug_object_activate(work, &work_debug_descr); | |
217 | return 0; | |
218 | } | |
219 | WARN_ON_ONCE(1); | |
220 | return 0; | |
221 | ||
222 | case ODEBUG_STATE_ACTIVE: | |
223 | WARN_ON(1); | |
224 | ||
225 | default: | |
226 | return 0; | |
227 | } | |
228 | } | |
229 | ||
230 | /* | |
231 | * fixup_free is called when: | |
232 | * - an active object is freed | |
233 | */ | |
234 | static int work_fixup_free(void *addr, enum debug_obj_state state) | |
235 | { | |
236 | struct work_struct *work = addr; | |
237 | ||
238 | switch (state) { | |
239 | case ODEBUG_STATE_ACTIVE: | |
240 | cancel_work_sync(work); | |
241 | debug_object_free(work, &work_debug_descr); | |
242 | return 1; | |
243 | default: | |
244 | return 0; | |
245 | } | |
246 | } | |
247 | ||
248 | static struct debug_obj_descr work_debug_descr = { | |
249 | .name = "work_struct", | |
250 | .fixup_init = work_fixup_init, | |
251 | .fixup_activate = work_fixup_activate, | |
252 | .fixup_free = work_fixup_free, | |
253 | }; | |
254 | ||
255 | static inline void debug_work_activate(struct work_struct *work) | |
256 | { | |
257 | debug_object_activate(work, &work_debug_descr); | |
258 | } | |
259 | ||
260 | static inline void debug_work_deactivate(struct work_struct *work) | |
261 | { | |
262 | debug_object_deactivate(work, &work_debug_descr); | |
263 | } | |
264 | ||
265 | void __init_work(struct work_struct *work, int onstack) | |
266 | { | |
267 | if (onstack) | |
268 | debug_object_init_on_stack(work, &work_debug_descr); | |
269 | else | |
270 | debug_object_init(work, &work_debug_descr); | |
271 | } | |
272 | EXPORT_SYMBOL_GPL(__init_work); | |
273 | ||
274 | void destroy_work_on_stack(struct work_struct *work) | |
275 | { | |
276 | debug_object_free(work, &work_debug_descr); | |
277 | } | |
278 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); | |
279 | ||
280 | #else | |
281 | static inline void debug_work_activate(struct work_struct *work) { } | |
282 | static inline void debug_work_deactivate(struct work_struct *work) { } | |
283 | #endif | |
284 | ||
95402b38 GS |
285 | /* Serializes the accesses to the list of workqueues. */ |
286 | static DEFINE_SPINLOCK(workqueue_lock); | |
1da177e4 | 287 | static LIST_HEAD(workqueues); |
a0a1a5fd | 288 | static bool workqueue_freezing; /* W: have wqs started freezing? */ |
c34056a3 | 289 | |
8b03ae3c TH |
290 | static DEFINE_PER_CPU(struct global_cwq, global_cwq); |
291 | ||
c34056a3 | 292 | static int worker_thread(void *__worker); |
1da177e4 | 293 | |
8b03ae3c TH |
294 | static struct global_cwq *get_gcwq(unsigned int cpu) |
295 | { | |
296 | return &per_cpu(global_cwq, cpu); | |
297 | } | |
298 | ||
1537663f TH |
299 | static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
300 | struct workqueue_struct *wq) | |
b1f4ec17 | 301 | { |
1537663f | 302 | return per_cpu_ptr(wq->cpu_wq, cpu); |
b1f4ec17 ON |
303 | } |
304 | ||
73f53c4a TH |
305 | static unsigned int work_color_to_flags(int color) |
306 | { | |
307 | return color << WORK_STRUCT_COLOR_SHIFT; | |
308 | } | |
309 | ||
310 | static int get_work_color(struct work_struct *work) | |
311 | { | |
312 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & | |
313 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); | |
314 | } | |
315 | ||
316 | static int work_next_color(int color) | |
317 | { | |
318 | return (color + 1) % WORK_NR_COLORS; | |
319 | } | |
320 | ||
4594bf15 | 321 | /* |
7a22ad75 TH |
322 | * Work data points to the cwq while a work is on queue. Once |
323 | * execution starts, it points to the cpu the work was last on. This | |
324 | * can be distinguished by comparing the data value against | |
325 | * PAGE_OFFSET. | |
326 | * | |
327 | * set_work_{cwq|cpu}() and clear_work_data() can be used to set the | |
328 | * cwq, cpu or clear work->data. These functions should only be | |
329 | * called while the work is owned - ie. while the PENDING bit is set. | |
330 | * | |
331 | * get_work_[g]cwq() can be used to obtain the gcwq or cwq | |
332 | * corresponding to a work. gcwq is available once the work has been | |
333 | * queued anywhere after initialization. cwq is available only from | |
334 | * queueing until execution starts. | |
4594bf15 | 335 | */ |
7a22ad75 TH |
336 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
337 | unsigned long flags) | |
365970a1 | 338 | { |
4594bf15 | 339 | BUG_ON(!work_pending(work)); |
7a22ad75 TH |
340 | atomic_long_set(&work->data, data | flags | work_static(work)); |
341 | } | |
365970a1 | 342 | |
7a22ad75 TH |
343 | static void set_work_cwq(struct work_struct *work, |
344 | struct cpu_workqueue_struct *cwq, | |
345 | unsigned long extra_flags) | |
346 | { | |
347 | set_work_data(work, (unsigned long)cwq, | |
348 | WORK_STRUCT_PENDING | extra_flags); | |
365970a1 DH |
349 | } |
350 | ||
7a22ad75 TH |
351 | static void set_work_cpu(struct work_struct *work, unsigned int cpu) |
352 | { | |
353 | set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); | |
354 | } | |
355 | ||
356 | static void clear_work_data(struct work_struct *work) | |
357 | { | |
358 | set_work_data(work, WORK_STRUCT_NO_CPU, 0); | |
359 | } | |
360 | ||
361 | static inline unsigned long get_work_data(struct work_struct *work) | |
362 | { | |
363 | return atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK; | |
364 | } | |
365 | ||
366 | static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) | |
4d707b9f | 367 | { |
7a22ad75 TH |
368 | unsigned long data = get_work_data(work); |
369 | ||
370 | return data >= PAGE_OFFSET ? (void *)data : NULL; | |
4d707b9f ON |
371 | } |
372 | ||
7a22ad75 | 373 | static struct global_cwq *get_work_gcwq(struct work_struct *work) |
365970a1 | 374 | { |
7a22ad75 TH |
375 | unsigned long data = get_work_data(work); |
376 | unsigned int cpu; | |
377 | ||
378 | if (data >= PAGE_OFFSET) | |
379 | return ((struct cpu_workqueue_struct *)data)->gcwq; | |
380 | ||
381 | cpu = data >> WORK_STRUCT_FLAG_BITS; | |
382 | if (cpu == NR_CPUS) | |
383 | return NULL; | |
384 | ||
385 | BUG_ON(cpu >= num_possible_cpus()); | |
386 | return get_gcwq(cpu); | |
365970a1 DH |
387 | } |
388 | ||
c8e55f36 TH |
389 | /** |
390 | * busy_worker_head - return the busy hash head for a work | |
391 | * @gcwq: gcwq of interest | |
392 | * @work: work to be hashed | |
393 | * | |
394 | * Return hash head of @gcwq for @work. | |
395 | * | |
396 | * CONTEXT: | |
397 | * spin_lock_irq(gcwq->lock). | |
398 | * | |
399 | * RETURNS: | |
400 | * Pointer to the hash head. | |
401 | */ | |
402 | static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, | |
403 | struct work_struct *work) | |
404 | { | |
405 | const int base_shift = ilog2(sizeof(struct work_struct)); | |
406 | unsigned long v = (unsigned long)work; | |
407 | ||
408 | /* simple shift and fold hash, do we need something better? */ | |
409 | v >>= base_shift; | |
410 | v += v >> BUSY_WORKER_HASH_ORDER; | |
411 | v &= BUSY_WORKER_HASH_MASK; | |
412 | ||
413 | return &gcwq->busy_hash[v]; | |
414 | } | |
415 | ||
8cca0eea TH |
416 | /** |
417 | * __find_worker_executing_work - find worker which is executing a work | |
418 | * @gcwq: gcwq of interest | |
419 | * @bwh: hash head as returned by busy_worker_head() | |
420 | * @work: work to find worker for | |
421 | * | |
422 | * Find a worker which is executing @work on @gcwq. @bwh should be | |
423 | * the hash head obtained by calling busy_worker_head() with the same | |
424 | * work. | |
425 | * | |
426 | * CONTEXT: | |
427 | * spin_lock_irq(gcwq->lock). | |
428 | * | |
429 | * RETURNS: | |
430 | * Pointer to worker which is executing @work if found, NULL | |
431 | * otherwise. | |
432 | */ | |
433 | static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, | |
434 | struct hlist_head *bwh, | |
435 | struct work_struct *work) | |
436 | { | |
437 | struct worker *worker; | |
438 | struct hlist_node *tmp; | |
439 | ||
440 | hlist_for_each_entry(worker, tmp, bwh, hentry) | |
441 | if (worker->current_work == work) | |
442 | return worker; | |
443 | return NULL; | |
444 | } | |
445 | ||
446 | /** | |
447 | * find_worker_executing_work - find worker which is executing a work | |
448 | * @gcwq: gcwq of interest | |
449 | * @work: work to find worker for | |
450 | * | |
451 | * Find a worker which is executing @work on @gcwq. This function is | |
452 | * identical to __find_worker_executing_work() except that this | |
453 | * function calculates @bwh itself. | |
454 | * | |
455 | * CONTEXT: | |
456 | * spin_lock_irq(gcwq->lock). | |
457 | * | |
458 | * RETURNS: | |
459 | * Pointer to worker which is executing @work if found, NULL | |
460 | * otherwise. | |
461 | */ | |
462 | static struct worker *find_worker_executing_work(struct global_cwq *gcwq, | |
463 | struct work_struct *work) | |
464 | { | |
465 | return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), | |
466 | work); | |
467 | } | |
468 | ||
4690c4ab TH |
469 | /** |
470 | * insert_work - insert a work into cwq | |
471 | * @cwq: cwq @work belongs to | |
472 | * @work: work to insert | |
473 | * @head: insertion point | |
474 | * @extra_flags: extra WORK_STRUCT_* flags to set | |
475 | * | |
476 | * Insert @work into @cwq after @head. | |
477 | * | |
478 | * CONTEXT: | |
8b03ae3c | 479 | * spin_lock_irq(gcwq->lock). |
4690c4ab | 480 | */ |
b89deed3 | 481 | static void insert_work(struct cpu_workqueue_struct *cwq, |
4690c4ab TH |
482 | struct work_struct *work, struct list_head *head, |
483 | unsigned int extra_flags) | |
b89deed3 | 484 | { |
4690c4ab | 485 | /* we own @work, set data and link */ |
7a22ad75 | 486 | set_work_cwq(work, cwq, extra_flags); |
4690c4ab | 487 | |
6e84d644 ON |
488 | /* |
489 | * Ensure that we get the right work->data if we see the | |
490 | * result of list_add() below, see try_to_grab_pending(). | |
491 | */ | |
492 | smp_wmb(); | |
4690c4ab | 493 | |
1a4d9b0a | 494 | list_add_tail(&work->entry, head); |
c8e55f36 | 495 | wake_up_process(cwq->worker->task); |
b89deed3 ON |
496 | } |
497 | ||
502ca9d8 TH |
498 | /** |
499 | * cwq_unbind_single_cpu - unbind cwq from single cpu workqueue processing | |
500 | * @cwq: cwq to unbind | |
501 | * | |
502 | * Try to unbind @cwq from single cpu workqueue processing. If | |
503 | * @cwq->wq is frozen, unbind is delayed till the workqueue is thawed. | |
504 | * | |
505 | * CONTEXT: | |
506 | * spin_lock_irq(gcwq->lock). | |
507 | */ | |
508 | static void cwq_unbind_single_cpu(struct cpu_workqueue_struct *cwq) | |
509 | { | |
510 | struct workqueue_struct *wq = cwq->wq; | |
511 | struct global_cwq *gcwq = cwq->gcwq; | |
512 | ||
513 | BUG_ON(wq->single_cpu != gcwq->cpu); | |
514 | /* | |
515 | * Unbind from workqueue if @cwq is not frozen. If frozen, | |
516 | * thaw_workqueues() will either restart processing on this | |
517 | * cpu or unbind if empty. This keeps works queued while | |
518 | * frozen fully ordered and flushable. | |
519 | */ | |
520 | if (likely(!(gcwq->flags & GCWQ_FREEZING))) { | |
521 | smp_wmb(); /* paired with cmpxchg() in __queue_work() */ | |
522 | wq->single_cpu = NR_CPUS; | |
523 | } | |
524 | } | |
525 | ||
4690c4ab | 526 | static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
1da177e4 LT |
527 | struct work_struct *work) |
528 | { | |
502ca9d8 TH |
529 | struct global_cwq *gcwq; |
530 | struct cpu_workqueue_struct *cwq; | |
1e19ffc6 | 531 | struct list_head *worklist; |
1da177e4 | 532 | unsigned long flags; |
502ca9d8 | 533 | bool arbitrate; |
1da177e4 | 534 | |
dc186ad7 | 535 | debug_work_activate(work); |
1e19ffc6 | 536 | |
502ca9d8 TH |
537 | /* determine gcwq to use */ |
538 | if (!(wq->flags & WQ_SINGLE_CPU)) { | |
539 | /* just use the requested cpu for multicpu workqueues */ | |
540 | gcwq = get_gcwq(cpu); | |
541 | spin_lock_irqsave(&gcwq->lock, flags); | |
542 | } else { | |
543 | unsigned int req_cpu = cpu; | |
544 | ||
545 | /* | |
546 | * It's a bit more complex for single cpu workqueues. | |
547 | * We first need to determine which cpu is going to be | |
548 | * used. If no cpu is currently serving this | |
549 | * workqueue, arbitrate using atomic accesses to | |
550 | * wq->single_cpu; otherwise, use the current one. | |
551 | */ | |
552 | retry: | |
553 | cpu = wq->single_cpu; | |
554 | arbitrate = cpu == NR_CPUS; | |
555 | if (arbitrate) | |
556 | cpu = req_cpu; | |
557 | ||
558 | gcwq = get_gcwq(cpu); | |
559 | spin_lock_irqsave(&gcwq->lock, flags); | |
560 | ||
561 | /* | |
562 | * The following cmpxchg() is a full barrier paired | |
563 | * with smp_wmb() in cwq_unbind_single_cpu() and | |
564 | * guarantees that all changes to wq->st_* fields are | |
565 | * visible on the new cpu after this point. | |
566 | */ | |
567 | if (arbitrate) | |
568 | cmpxchg(&wq->single_cpu, NR_CPUS, cpu); | |
569 | ||
570 | if (unlikely(wq->single_cpu != cpu)) { | |
571 | spin_unlock_irqrestore(&gcwq->lock, flags); | |
572 | goto retry; | |
573 | } | |
574 | } | |
575 | ||
576 | /* gcwq determined, get cwq and queue */ | |
577 | cwq = get_cwq(gcwq->cpu, wq); | |
578 | ||
4690c4ab | 579 | BUG_ON(!list_empty(&work->entry)); |
1e19ffc6 | 580 | |
73f53c4a | 581 | cwq->nr_in_flight[cwq->work_color]++; |
1e19ffc6 TH |
582 | |
583 | if (likely(cwq->nr_active < cwq->max_active)) { | |
584 | cwq->nr_active++; | |
585 | worklist = &cwq->worklist; | |
586 | } else | |
587 | worklist = &cwq->delayed_works; | |
588 | ||
589 | insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color)); | |
590 | ||
8b03ae3c | 591 | spin_unlock_irqrestore(&gcwq->lock, flags); |
1da177e4 LT |
592 | } |
593 | ||
0fcb78c2 REB |
594 | /** |
595 | * queue_work - queue work on a workqueue | |
596 | * @wq: workqueue to use | |
597 | * @work: work to queue | |
598 | * | |
057647fc | 599 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1da177e4 | 600 | * |
00dfcaf7 ON |
601 | * We queue the work to the CPU on which it was submitted, but if the CPU dies |
602 | * it can be processed by another CPU. | |
1da177e4 | 603 | */ |
7ad5b3a5 | 604 | int queue_work(struct workqueue_struct *wq, struct work_struct *work) |
1da177e4 | 605 | { |
ef1ca236 ON |
606 | int ret; |
607 | ||
608 | ret = queue_work_on(get_cpu(), wq, work); | |
609 | put_cpu(); | |
610 | ||
1da177e4 LT |
611 | return ret; |
612 | } | |
ae90dd5d | 613 | EXPORT_SYMBOL_GPL(queue_work); |
1da177e4 | 614 | |
c1a220e7 ZR |
615 | /** |
616 | * queue_work_on - queue work on specific cpu | |
617 | * @cpu: CPU number to execute work on | |
618 | * @wq: workqueue to use | |
619 | * @work: work to queue | |
620 | * | |
621 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
622 | * | |
623 | * We queue the work to a specific CPU, the caller must ensure it | |
624 | * can't go away. | |
625 | */ | |
626 | int | |
627 | queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) | |
628 | { | |
629 | int ret = 0; | |
630 | ||
22df02bb | 631 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
4690c4ab | 632 | __queue_work(cpu, wq, work); |
c1a220e7 ZR |
633 | ret = 1; |
634 | } | |
635 | return ret; | |
636 | } | |
637 | EXPORT_SYMBOL_GPL(queue_work_on); | |
638 | ||
6d141c3f | 639 | static void delayed_work_timer_fn(unsigned long __data) |
1da177e4 | 640 | { |
52bad64d | 641 | struct delayed_work *dwork = (struct delayed_work *)__data; |
7a22ad75 | 642 | struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); |
1da177e4 | 643 | |
4690c4ab | 644 | __queue_work(smp_processor_id(), cwq->wq, &dwork->work); |
1da177e4 LT |
645 | } |
646 | ||
0fcb78c2 REB |
647 | /** |
648 | * queue_delayed_work - queue work on a workqueue after delay | |
649 | * @wq: workqueue to use | |
af9997e4 | 650 | * @dwork: delayable work to queue |
0fcb78c2 REB |
651 | * @delay: number of jiffies to wait before queueing |
652 | * | |
057647fc | 653 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
0fcb78c2 | 654 | */ |
7ad5b3a5 | 655 | int queue_delayed_work(struct workqueue_struct *wq, |
52bad64d | 656 | struct delayed_work *dwork, unsigned long delay) |
1da177e4 | 657 | { |
52bad64d | 658 | if (delay == 0) |
63bc0362 | 659 | return queue_work(wq, &dwork->work); |
1da177e4 | 660 | |
63bc0362 | 661 | return queue_delayed_work_on(-1, wq, dwork, delay); |
1da177e4 | 662 | } |
ae90dd5d | 663 | EXPORT_SYMBOL_GPL(queue_delayed_work); |
1da177e4 | 664 | |
0fcb78c2 REB |
665 | /** |
666 | * queue_delayed_work_on - queue work on specific CPU after delay | |
667 | * @cpu: CPU number to execute work on | |
668 | * @wq: workqueue to use | |
af9997e4 | 669 | * @dwork: work to queue |
0fcb78c2 REB |
670 | * @delay: number of jiffies to wait before queueing |
671 | * | |
057647fc | 672 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
0fcb78c2 | 673 | */ |
7a6bc1cd | 674 | int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
52bad64d | 675 | struct delayed_work *dwork, unsigned long delay) |
7a6bc1cd VP |
676 | { |
677 | int ret = 0; | |
52bad64d DH |
678 | struct timer_list *timer = &dwork->timer; |
679 | struct work_struct *work = &dwork->work; | |
7a6bc1cd | 680 | |
22df02bb | 681 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
7a22ad75 TH |
682 | struct global_cwq *gcwq = get_work_gcwq(work); |
683 | unsigned int lcpu = gcwq ? gcwq->cpu : raw_smp_processor_id(); | |
684 | ||
7a6bc1cd VP |
685 | BUG_ON(timer_pending(timer)); |
686 | BUG_ON(!list_empty(&work->entry)); | |
687 | ||
8a3e77cc | 688 | timer_stats_timer_set_start_info(&dwork->timer); |
7a22ad75 TH |
689 | /* |
690 | * This stores cwq for the moment, for the timer_fn. | |
691 | * Note that the work's gcwq is preserved to allow | |
692 | * reentrance detection for delayed works. | |
693 | */ | |
694 | set_work_cwq(work, get_cwq(lcpu, wq), 0); | |
7a6bc1cd | 695 | timer->expires = jiffies + delay; |
52bad64d | 696 | timer->data = (unsigned long)dwork; |
7a6bc1cd | 697 | timer->function = delayed_work_timer_fn; |
63bc0362 ON |
698 | |
699 | if (unlikely(cpu >= 0)) | |
700 | add_timer_on(timer, cpu); | |
701 | else | |
702 | add_timer(timer); | |
7a6bc1cd VP |
703 | ret = 1; |
704 | } | |
705 | return ret; | |
706 | } | |
ae90dd5d | 707 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
1da177e4 | 708 | |
c8e55f36 TH |
709 | /** |
710 | * worker_enter_idle - enter idle state | |
711 | * @worker: worker which is entering idle state | |
712 | * | |
713 | * @worker is entering idle state. Update stats and idle timer if | |
714 | * necessary. | |
715 | * | |
716 | * LOCKING: | |
717 | * spin_lock_irq(gcwq->lock). | |
718 | */ | |
719 | static void worker_enter_idle(struct worker *worker) | |
720 | { | |
721 | struct global_cwq *gcwq = worker->gcwq; | |
722 | ||
723 | BUG_ON(worker->flags & WORKER_IDLE); | |
724 | BUG_ON(!list_empty(&worker->entry) && | |
725 | (worker->hentry.next || worker->hentry.pprev)); | |
726 | ||
727 | worker->flags |= WORKER_IDLE; | |
728 | gcwq->nr_idle++; | |
729 | ||
730 | /* idle_list is LIFO */ | |
731 | list_add(&worker->entry, &gcwq->idle_list); | |
db7bccf4 TH |
732 | |
733 | if (unlikely(worker->flags & WORKER_ROGUE)) | |
734 | wake_up_all(&gcwq->trustee_wait); | |
c8e55f36 TH |
735 | } |
736 | ||
737 | /** | |
738 | * worker_leave_idle - leave idle state | |
739 | * @worker: worker which is leaving idle state | |
740 | * | |
741 | * @worker is leaving idle state. Update stats. | |
742 | * | |
743 | * LOCKING: | |
744 | * spin_lock_irq(gcwq->lock). | |
745 | */ | |
746 | static void worker_leave_idle(struct worker *worker) | |
747 | { | |
748 | struct global_cwq *gcwq = worker->gcwq; | |
749 | ||
750 | BUG_ON(!(worker->flags & WORKER_IDLE)); | |
751 | worker->flags &= ~WORKER_IDLE; | |
752 | gcwq->nr_idle--; | |
753 | list_del_init(&worker->entry); | |
754 | } | |
755 | ||
c34056a3 TH |
756 | static struct worker *alloc_worker(void) |
757 | { | |
758 | struct worker *worker; | |
759 | ||
760 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
c8e55f36 TH |
761 | if (worker) { |
762 | INIT_LIST_HEAD(&worker->entry); | |
affee4b2 | 763 | INIT_LIST_HEAD(&worker->scheduled); |
c8e55f36 | 764 | } |
c34056a3 TH |
765 | return worker; |
766 | } | |
767 | ||
768 | /** | |
769 | * create_worker - create a new workqueue worker | |
770 | * @cwq: cwq the new worker will belong to | |
771 | * @bind: whether to set affinity to @cpu or not | |
772 | * | |
773 | * Create a new worker which is bound to @cwq. The returned worker | |
774 | * can be started by calling start_worker() or destroyed using | |
775 | * destroy_worker(). | |
776 | * | |
777 | * CONTEXT: | |
778 | * Might sleep. Does GFP_KERNEL allocations. | |
779 | * | |
780 | * RETURNS: | |
781 | * Pointer to the newly created worker. | |
782 | */ | |
783 | static struct worker *create_worker(struct cpu_workqueue_struct *cwq, bool bind) | |
784 | { | |
8b03ae3c | 785 | struct global_cwq *gcwq = cwq->gcwq; |
c34056a3 TH |
786 | int id = -1; |
787 | struct worker *worker = NULL; | |
788 | ||
8b03ae3c TH |
789 | spin_lock_irq(&gcwq->lock); |
790 | while (ida_get_new(&gcwq->worker_ida, &id)) { | |
791 | spin_unlock_irq(&gcwq->lock); | |
792 | if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) | |
c34056a3 | 793 | goto fail; |
8b03ae3c | 794 | spin_lock_irq(&gcwq->lock); |
c34056a3 | 795 | } |
8b03ae3c | 796 | spin_unlock_irq(&gcwq->lock); |
c34056a3 TH |
797 | |
798 | worker = alloc_worker(); | |
799 | if (!worker) | |
800 | goto fail; | |
801 | ||
8b03ae3c | 802 | worker->gcwq = gcwq; |
c34056a3 TH |
803 | worker->cwq = cwq; |
804 | worker->id = id; | |
805 | ||
806 | worker->task = kthread_create(worker_thread, worker, "kworker/%u:%d", | |
8b03ae3c | 807 | gcwq->cpu, id); |
c34056a3 TH |
808 | if (IS_ERR(worker->task)) |
809 | goto fail; | |
810 | ||
db7bccf4 TH |
811 | /* |
812 | * A rogue worker will become a regular one if CPU comes | |
813 | * online later on. Make sure every worker has | |
814 | * PF_THREAD_BOUND set. | |
815 | */ | |
c34056a3 | 816 | if (bind) |
8b03ae3c | 817 | kthread_bind(worker->task, gcwq->cpu); |
db7bccf4 TH |
818 | else |
819 | worker->task->flags |= PF_THREAD_BOUND; | |
c34056a3 TH |
820 | |
821 | return worker; | |
822 | fail: | |
823 | if (id >= 0) { | |
8b03ae3c TH |
824 | spin_lock_irq(&gcwq->lock); |
825 | ida_remove(&gcwq->worker_ida, id); | |
826 | spin_unlock_irq(&gcwq->lock); | |
c34056a3 TH |
827 | } |
828 | kfree(worker); | |
829 | return NULL; | |
830 | } | |
831 | ||
832 | /** | |
833 | * start_worker - start a newly created worker | |
834 | * @worker: worker to start | |
835 | * | |
c8e55f36 | 836 | * Make the gcwq aware of @worker and start it. |
c34056a3 TH |
837 | * |
838 | * CONTEXT: | |
8b03ae3c | 839 | * spin_lock_irq(gcwq->lock). |
c34056a3 TH |
840 | */ |
841 | static void start_worker(struct worker *worker) | |
842 | { | |
c8e55f36 TH |
843 | worker->flags |= WORKER_STARTED; |
844 | worker->gcwq->nr_workers++; | |
845 | worker_enter_idle(worker); | |
c34056a3 TH |
846 | wake_up_process(worker->task); |
847 | } | |
848 | ||
849 | /** | |
850 | * destroy_worker - destroy a workqueue worker | |
851 | * @worker: worker to be destroyed | |
852 | * | |
c8e55f36 TH |
853 | * Destroy @worker and adjust @gcwq stats accordingly. |
854 | * | |
855 | * CONTEXT: | |
856 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. | |
c34056a3 TH |
857 | */ |
858 | static void destroy_worker(struct worker *worker) | |
859 | { | |
8b03ae3c | 860 | struct global_cwq *gcwq = worker->gcwq; |
c34056a3 TH |
861 | int id = worker->id; |
862 | ||
863 | /* sanity check frenzy */ | |
864 | BUG_ON(worker->current_work); | |
affee4b2 | 865 | BUG_ON(!list_empty(&worker->scheduled)); |
c34056a3 | 866 | |
c8e55f36 TH |
867 | if (worker->flags & WORKER_STARTED) |
868 | gcwq->nr_workers--; | |
869 | if (worker->flags & WORKER_IDLE) | |
870 | gcwq->nr_idle--; | |
871 | ||
872 | list_del_init(&worker->entry); | |
873 | worker->flags |= WORKER_DIE; | |
874 | ||
875 | spin_unlock_irq(&gcwq->lock); | |
876 | ||
c34056a3 TH |
877 | kthread_stop(worker->task); |
878 | kfree(worker); | |
879 | ||
8b03ae3c TH |
880 | spin_lock_irq(&gcwq->lock); |
881 | ida_remove(&gcwq->worker_ida, id); | |
c34056a3 TH |
882 | } |
883 | ||
affee4b2 TH |
884 | /** |
885 | * move_linked_works - move linked works to a list | |
886 | * @work: start of series of works to be scheduled | |
887 | * @head: target list to append @work to | |
888 | * @nextp: out paramter for nested worklist walking | |
889 | * | |
890 | * Schedule linked works starting from @work to @head. Work series to | |
891 | * be scheduled starts at @work and includes any consecutive work with | |
892 | * WORK_STRUCT_LINKED set in its predecessor. | |
893 | * | |
894 | * If @nextp is not NULL, it's updated to point to the next work of | |
895 | * the last scheduled work. This allows move_linked_works() to be | |
896 | * nested inside outer list_for_each_entry_safe(). | |
897 | * | |
898 | * CONTEXT: | |
8b03ae3c | 899 | * spin_lock_irq(gcwq->lock). |
affee4b2 TH |
900 | */ |
901 | static void move_linked_works(struct work_struct *work, struct list_head *head, | |
902 | struct work_struct **nextp) | |
903 | { | |
904 | struct work_struct *n; | |
905 | ||
906 | /* | |
907 | * Linked worklist will always end before the end of the list, | |
908 | * use NULL for list head. | |
909 | */ | |
910 | list_for_each_entry_safe_from(work, n, NULL, entry) { | |
911 | list_move_tail(&work->entry, head); | |
912 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) | |
913 | break; | |
914 | } | |
915 | ||
916 | /* | |
917 | * If we're already inside safe list traversal and have moved | |
918 | * multiple works to the scheduled queue, the next position | |
919 | * needs to be updated. | |
920 | */ | |
921 | if (nextp) | |
922 | *nextp = n; | |
923 | } | |
924 | ||
1e19ffc6 TH |
925 | static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) |
926 | { | |
927 | struct work_struct *work = list_first_entry(&cwq->delayed_works, | |
928 | struct work_struct, entry); | |
929 | ||
930 | move_linked_works(work, &cwq->worklist, NULL); | |
931 | cwq->nr_active++; | |
932 | } | |
933 | ||
73f53c4a TH |
934 | /** |
935 | * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight | |
936 | * @cwq: cwq of interest | |
937 | * @color: color of work which left the queue | |
938 | * | |
939 | * A work either has completed or is removed from pending queue, | |
940 | * decrement nr_in_flight of its cwq and handle workqueue flushing. | |
941 | * | |
942 | * CONTEXT: | |
8b03ae3c | 943 | * spin_lock_irq(gcwq->lock). |
73f53c4a TH |
944 | */ |
945 | static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) | |
946 | { | |
947 | /* ignore uncolored works */ | |
948 | if (color == WORK_NO_COLOR) | |
949 | return; | |
950 | ||
951 | cwq->nr_in_flight[color]--; | |
1e19ffc6 TH |
952 | cwq->nr_active--; |
953 | ||
502ca9d8 TH |
954 | if (!list_empty(&cwq->delayed_works)) { |
955 | /* one down, submit a delayed one */ | |
956 | if (cwq->nr_active < cwq->max_active) | |
957 | cwq_activate_first_delayed(cwq); | |
958 | } else if (!cwq->nr_active && cwq->wq->flags & WQ_SINGLE_CPU) { | |
959 | /* this was the last work, unbind from single cpu */ | |
960 | cwq_unbind_single_cpu(cwq); | |
961 | } | |
73f53c4a TH |
962 | |
963 | /* is flush in progress and are we at the flushing tip? */ | |
964 | if (likely(cwq->flush_color != color)) | |
965 | return; | |
966 | ||
967 | /* are there still in-flight works? */ | |
968 | if (cwq->nr_in_flight[color]) | |
969 | return; | |
970 | ||
971 | /* this cwq is done, clear flush_color */ | |
972 | cwq->flush_color = -1; | |
973 | ||
974 | /* | |
975 | * If this was the last cwq, wake up the first flusher. It | |
976 | * will handle the rest. | |
977 | */ | |
978 | if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) | |
979 | complete(&cwq->wq->first_flusher->done); | |
980 | } | |
981 | ||
a62428c0 TH |
982 | /** |
983 | * process_one_work - process single work | |
c34056a3 | 984 | * @worker: self |
a62428c0 TH |
985 | * @work: work to process |
986 | * | |
987 | * Process @work. This function contains all the logics necessary to | |
988 | * process a single work including synchronization against and | |
989 | * interaction with other workers on the same cpu, queueing and | |
990 | * flushing. As long as context requirement is met, any worker can | |
991 | * call this function to process a work. | |
992 | * | |
993 | * CONTEXT: | |
8b03ae3c | 994 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
a62428c0 | 995 | */ |
c34056a3 | 996 | static void process_one_work(struct worker *worker, struct work_struct *work) |
a62428c0 | 997 | { |
c34056a3 | 998 | struct cpu_workqueue_struct *cwq = worker->cwq; |
8b03ae3c | 999 | struct global_cwq *gcwq = cwq->gcwq; |
c8e55f36 | 1000 | struct hlist_head *bwh = busy_worker_head(gcwq, work); |
a62428c0 | 1001 | work_func_t f = work->func; |
73f53c4a | 1002 | int work_color; |
a62428c0 TH |
1003 | #ifdef CONFIG_LOCKDEP |
1004 | /* | |
1005 | * It is permissible to free the struct work_struct from | |
1006 | * inside the function that is called from it, this we need to | |
1007 | * take into account for lockdep too. To avoid bogus "held | |
1008 | * lock freed" warnings as well as problems when looking into | |
1009 | * work->lockdep_map, make a copy and use that here. | |
1010 | */ | |
1011 | struct lockdep_map lockdep_map = work->lockdep_map; | |
1012 | #endif | |
1013 | /* claim and process */ | |
a62428c0 | 1014 | debug_work_deactivate(work); |
c8e55f36 | 1015 | hlist_add_head(&worker->hentry, bwh); |
c34056a3 | 1016 | worker->current_work = work; |
8cca0eea | 1017 | worker->current_cwq = cwq; |
73f53c4a | 1018 | work_color = get_work_color(work); |
7a22ad75 TH |
1019 | |
1020 | BUG_ON(get_work_cwq(work) != cwq); | |
1021 | /* record the current cpu number in the work data and dequeue */ | |
1022 | set_work_cpu(work, gcwq->cpu); | |
a62428c0 TH |
1023 | list_del_init(&work->entry); |
1024 | ||
8b03ae3c | 1025 | spin_unlock_irq(&gcwq->lock); |
a62428c0 | 1026 | |
a62428c0 TH |
1027 | work_clear_pending(work); |
1028 | lock_map_acquire(&cwq->wq->lockdep_map); | |
1029 | lock_map_acquire(&lockdep_map); | |
1030 | f(work); | |
1031 | lock_map_release(&lockdep_map); | |
1032 | lock_map_release(&cwq->wq->lockdep_map); | |
1033 | ||
1034 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { | |
1035 | printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " | |
1036 | "%s/0x%08x/%d\n", | |
1037 | current->comm, preempt_count(), task_pid_nr(current)); | |
1038 | printk(KERN_ERR " last function: "); | |
1039 | print_symbol("%s\n", (unsigned long)f); | |
1040 | debug_show_held_locks(current); | |
1041 | dump_stack(); | |
1042 | } | |
1043 | ||
8b03ae3c | 1044 | spin_lock_irq(&gcwq->lock); |
a62428c0 TH |
1045 | |
1046 | /* we're done with it, release */ | |
c8e55f36 | 1047 | hlist_del_init(&worker->hentry); |
c34056a3 | 1048 | worker->current_work = NULL; |
8cca0eea | 1049 | worker->current_cwq = NULL; |
73f53c4a | 1050 | cwq_dec_nr_in_flight(cwq, work_color); |
a62428c0 TH |
1051 | } |
1052 | ||
affee4b2 TH |
1053 | /** |
1054 | * process_scheduled_works - process scheduled works | |
1055 | * @worker: self | |
1056 | * | |
1057 | * Process all scheduled works. Please note that the scheduled list | |
1058 | * may change while processing a work, so this function repeatedly | |
1059 | * fetches a work from the top and executes it. | |
1060 | * | |
1061 | * CONTEXT: | |
8b03ae3c | 1062 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
affee4b2 TH |
1063 | * multiple times. |
1064 | */ | |
1065 | static void process_scheduled_works(struct worker *worker) | |
1da177e4 | 1066 | { |
affee4b2 TH |
1067 | while (!list_empty(&worker->scheduled)) { |
1068 | struct work_struct *work = list_first_entry(&worker->scheduled, | |
1da177e4 | 1069 | struct work_struct, entry); |
c34056a3 | 1070 | process_one_work(worker, work); |
1da177e4 | 1071 | } |
1da177e4 LT |
1072 | } |
1073 | ||
4690c4ab TH |
1074 | /** |
1075 | * worker_thread - the worker thread function | |
c34056a3 | 1076 | * @__worker: self |
4690c4ab TH |
1077 | * |
1078 | * The cwq worker thread function. | |
1079 | */ | |
c34056a3 | 1080 | static int worker_thread(void *__worker) |
1da177e4 | 1081 | { |
c34056a3 | 1082 | struct worker *worker = __worker; |
8b03ae3c | 1083 | struct global_cwq *gcwq = worker->gcwq; |
c34056a3 | 1084 | struct cpu_workqueue_struct *cwq = worker->cwq; |
1da177e4 | 1085 | |
c8e55f36 | 1086 | woke_up: |
c8e55f36 | 1087 | spin_lock_irq(&gcwq->lock); |
1da177e4 | 1088 | |
c8e55f36 TH |
1089 | /* DIE can be set only while we're idle, checking here is enough */ |
1090 | if (worker->flags & WORKER_DIE) { | |
1091 | spin_unlock_irq(&gcwq->lock); | |
1092 | return 0; | |
1093 | } | |
affee4b2 | 1094 | |
c8e55f36 | 1095 | worker_leave_idle(worker); |
db7bccf4 | 1096 | recheck: |
c8e55f36 TH |
1097 | /* |
1098 | * ->scheduled list can only be filled while a worker is | |
1099 | * preparing to process a work or actually processing it. | |
1100 | * Make sure nobody diddled with it while I was sleeping. | |
1101 | */ | |
1102 | BUG_ON(!list_empty(&worker->scheduled)); | |
1103 | ||
1104 | while (!list_empty(&cwq->worklist)) { | |
1105 | struct work_struct *work = | |
1106 | list_first_entry(&cwq->worklist, | |
1107 | struct work_struct, entry); | |
1108 | ||
db7bccf4 TH |
1109 | /* |
1110 | * The following is a rather inefficient way to close | |
1111 | * race window against cpu hotplug operations. Will | |
1112 | * be replaced soon. | |
1113 | */ | |
1114 | if (unlikely(!(worker->flags & WORKER_ROGUE) && | |
1115 | !cpumask_equal(&worker->task->cpus_allowed, | |
1116 | get_cpu_mask(gcwq->cpu)))) { | |
1117 | spin_unlock_irq(&gcwq->lock); | |
1118 | set_cpus_allowed_ptr(worker->task, | |
1119 | get_cpu_mask(gcwq->cpu)); | |
1120 | cpu_relax(); | |
1121 | spin_lock_irq(&gcwq->lock); | |
1122 | goto recheck; | |
1123 | } | |
1124 | ||
c8e55f36 TH |
1125 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
1126 | /* optimization path, not strictly necessary */ | |
1127 | process_one_work(worker, work); | |
1128 | if (unlikely(!list_empty(&worker->scheduled))) | |
affee4b2 | 1129 | process_scheduled_works(worker); |
c8e55f36 TH |
1130 | } else { |
1131 | move_linked_works(work, &worker->scheduled, NULL); | |
1132 | process_scheduled_works(worker); | |
affee4b2 | 1133 | } |
1da177e4 | 1134 | } |
3af24433 | 1135 | |
c8e55f36 TH |
1136 | /* |
1137 | * gcwq->lock is held and there's no work to process, sleep. | |
1138 | * Workers are woken up only while holding gcwq->lock, so | |
1139 | * setting the current state before releasing gcwq->lock is | |
1140 | * enough to prevent losing any event. | |
1141 | */ | |
1142 | worker_enter_idle(worker); | |
1143 | __set_current_state(TASK_INTERRUPTIBLE); | |
1144 | spin_unlock_irq(&gcwq->lock); | |
1145 | schedule(); | |
1146 | goto woke_up; | |
1da177e4 LT |
1147 | } |
1148 | ||
fc2e4d70 ON |
1149 | struct wq_barrier { |
1150 | struct work_struct work; | |
1151 | struct completion done; | |
1152 | }; | |
1153 | ||
1154 | static void wq_barrier_func(struct work_struct *work) | |
1155 | { | |
1156 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); | |
1157 | complete(&barr->done); | |
1158 | } | |
1159 | ||
4690c4ab TH |
1160 | /** |
1161 | * insert_wq_barrier - insert a barrier work | |
1162 | * @cwq: cwq to insert barrier into | |
1163 | * @barr: wq_barrier to insert | |
affee4b2 TH |
1164 | * @target: target work to attach @barr to |
1165 | * @worker: worker currently executing @target, NULL if @target is not executing | |
4690c4ab | 1166 | * |
affee4b2 TH |
1167 | * @barr is linked to @target such that @barr is completed only after |
1168 | * @target finishes execution. Please note that the ordering | |
1169 | * guarantee is observed only with respect to @target and on the local | |
1170 | * cpu. | |
1171 | * | |
1172 | * Currently, a queued barrier can't be canceled. This is because | |
1173 | * try_to_grab_pending() can't determine whether the work to be | |
1174 | * grabbed is at the head of the queue and thus can't clear LINKED | |
1175 | * flag of the previous work while there must be a valid next work | |
1176 | * after a work with LINKED flag set. | |
1177 | * | |
1178 | * Note that when @worker is non-NULL, @target may be modified | |
1179 | * underneath us, so we can't reliably determine cwq from @target. | |
4690c4ab TH |
1180 | * |
1181 | * CONTEXT: | |
8b03ae3c | 1182 | * spin_lock_irq(gcwq->lock). |
4690c4ab | 1183 | */ |
83c22520 | 1184 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
affee4b2 TH |
1185 | struct wq_barrier *barr, |
1186 | struct work_struct *target, struct worker *worker) | |
fc2e4d70 | 1187 | { |
affee4b2 TH |
1188 | struct list_head *head; |
1189 | unsigned int linked = 0; | |
1190 | ||
dc186ad7 | 1191 | /* |
8b03ae3c | 1192 | * debugobject calls are safe here even with gcwq->lock locked |
dc186ad7 TG |
1193 | * as we know for sure that this will not trigger any of the |
1194 | * checks and call back into the fixup functions where we | |
1195 | * might deadlock. | |
1196 | */ | |
1197 | INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); | |
22df02bb | 1198 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
fc2e4d70 | 1199 | init_completion(&barr->done); |
83c22520 | 1200 | |
affee4b2 TH |
1201 | /* |
1202 | * If @target is currently being executed, schedule the | |
1203 | * barrier to the worker; otherwise, put it after @target. | |
1204 | */ | |
1205 | if (worker) | |
1206 | head = worker->scheduled.next; | |
1207 | else { | |
1208 | unsigned long *bits = work_data_bits(target); | |
1209 | ||
1210 | head = target->entry.next; | |
1211 | /* there can already be other linked works, inherit and set */ | |
1212 | linked = *bits & WORK_STRUCT_LINKED; | |
1213 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); | |
1214 | } | |
1215 | ||
dc186ad7 | 1216 | debug_work_activate(&barr->work); |
affee4b2 TH |
1217 | insert_work(cwq, &barr->work, head, |
1218 | work_color_to_flags(WORK_NO_COLOR) | linked); | |
fc2e4d70 ON |
1219 | } |
1220 | ||
73f53c4a TH |
1221 | /** |
1222 | * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing | |
1223 | * @wq: workqueue being flushed | |
1224 | * @flush_color: new flush color, < 0 for no-op | |
1225 | * @work_color: new work color, < 0 for no-op | |
1226 | * | |
1227 | * Prepare cwqs for workqueue flushing. | |
1228 | * | |
1229 | * If @flush_color is non-negative, flush_color on all cwqs should be | |
1230 | * -1. If no cwq has in-flight commands at the specified color, all | |
1231 | * cwq->flush_color's stay at -1 and %false is returned. If any cwq | |
1232 | * has in flight commands, its cwq->flush_color is set to | |
1233 | * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq | |
1234 | * wakeup logic is armed and %true is returned. | |
1235 | * | |
1236 | * The caller should have initialized @wq->first_flusher prior to | |
1237 | * calling this function with non-negative @flush_color. If | |
1238 | * @flush_color is negative, no flush color update is done and %false | |
1239 | * is returned. | |
1240 | * | |
1241 | * If @work_color is non-negative, all cwqs should have the same | |
1242 | * work_color which is previous to @work_color and all will be | |
1243 | * advanced to @work_color. | |
1244 | * | |
1245 | * CONTEXT: | |
1246 | * mutex_lock(wq->flush_mutex). | |
1247 | * | |
1248 | * RETURNS: | |
1249 | * %true if @flush_color >= 0 and there's something to flush. %false | |
1250 | * otherwise. | |
1251 | */ | |
1252 | static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, | |
1253 | int flush_color, int work_color) | |
1da177e4 | 1254 | { |
73f53c4a TH |
1255 | bool wait = false; |
1256 | unsigned int cpu; | |
1da177e4 | 1257 | |
73f53c4a TH |
1258 | if (flush_color >= 0) { |
1259 | BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); | |
1260 | atomic_set(&wq->nr_cwqs_to_flush, 1); | |
1da177e4 | 1261 | } |
2355b70f | 1262 | |
73f53c4a TH |
1263 | for_each_possible_cpu(cpu) { |
1264 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
8b03ae3c | 1265 | struct global_cwq *gcwq = cwq->gcwq; |
73f53c4a | 1266 | |
8b03ae3c | 1267 | spin_lock_irq(&gcwq->lock); |
73f53c4a TH |
1268 | |
1269 | if (flush_color >= 0) { | |
1270 | BUG_ON(cwq->flush_color != -1); | |
1271 | ||
1272 | if (cwq->nr_in_flight[flush_color]) { | |
1273 | cwq->flush_color = flush_color; | |
1274 | atomic_inc(&wq->nr_cwqs_to_flush); | |
1275 | wait = true; | |
1276 | } | |
1277 | } | |
1278 | ||
1279 | if (work_color >= 0) { | |
1280 | BUG_ON(work_color != work_next_color(cwq->work_color)); | |
1281 | cwq->work_color = work_color; | |
1282 | } | |
1283 | ||
8b03ae3c | 1284 | spin_unlock_irq(&gcwq->lock); |
dc186ad7 | 1285 | } |
14441960 | 1286 | |
73f53c4a TH |
1287 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) |
1288 | complete(&wq->first_flusher->done); | |
1289 | ||
1290 | return wait; | |
1da177e4 LT |
1291 | } |
1292 | ||
0fcb78c2 | 1293 | /** |
1da177e4 | 1294 | * flush_workqueue - ensure that any scheduled work has run to completion. |
0fcb78c2 | 1295 | * @wq: workqueue to flush |
1da177e4 LT |
1296 | * |
1297 | * Forces execution of the workqueue and blocks until its completion. | |
1298 | * This is typically used in driver shutdown handlers. | |
1299 | * | |
fc2e4d70 ON |
1300 | * We sleep until all works which were queued on entry have been handled, |
1301 | * but we are not livelocked by new incoming ones. | |
1da177e4 | 1302 | */ |
7ad5b3a5 | 1303 | void flush_workqueue(struct workqueue_struct *wq) |
1da177e4 | 1304 | { |
73f53c4a TH |
1305 | struct wq_flusher this_flusher = { |
1306 | .list = LIST_HEAD_INIT(this_flusher.list), | |
1307 | .flush_color = -1, | |
1308 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), | |
1309 | }; | |
1310 | int next_color; | |
1da177e4 | 1311 | |
3295f0ef IM |
1312 | lock_map_acquire(&wq->lockdep_map); |
1313 | lock_map_release(&wq->lockdep_map); | |
73f53c4a TH |
1314 | |
1315 | mutex_lock(&wq->flush_mutex); | |
1316 | ||
1317 | /* | |
1318 | * Start-to-wait phase | |
1319 | */ | |
1320 | next_color = work_next_color(wq->work_color); | |
1321 | ||
1322 | if (next_color != wq->flush_color) { | |
1323 | /* | |
1324 | * Color space is not full. The current work_color | |
1325 | * becomes our flush_color and work_color is advanced | |
1326 | * by one. | |
1327 | */ | |
1328 | BUG_ON(!list_empty(&wq->flusher_overflow)); | |
1329 | this_flusher.flush_color = wq->work_color; | |
1330 | wq->work_color = next_color; | |
1331 | ||
1332 | if (!wq->first_flusher) { | |
1333 | /* no flush in progress, become the first flusher */ | |
1334 | BUG_ON(wq->flush_color != this_flusher.flush_color); | |
1335 | ||
1336 | wq->first_flusher = &this_flusher; | |
1337 | ||
1338 | if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, | |
1339 | wq->work_color)) { | |
1340 | /* nothing to flush, done */ | |
1341 | wq->flush_color = next_color; | |
1342 | wq->first_flusher = NULL; | |
1343 | goto out_unlock; | |
1344 | } | |
1345 | } else { | |
1346 | /* wait in queue */ | |
1347 | BUG_ON(wq->flush_color == this_flusher.flush_color); | |
1348 | list_add_tail(&this_flusher.list, &wq->flusher_queue); | |
1349 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); | |
1350 | } | |
1351 | } else { | |
1352 | /* | |
1353 | * Oops, color space is full, wait on overflow queue. | |
1354 | * The next flush completion will assign us | |
1355 | * flush_color and transfer to flusher_queue. | |
1356 | */ | |
1357 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); | |
1358 | } | |
1359 | ||
1360 | mutex_unlock(&wq->flush_mutex); | |
1361 | ||
1362 | wait_for_completion(&this_flusher.done); | |
1363 | ||
1364 | /* | |
1365 | * Wake-up-and-cascade phase | |
1366 | * | |
1367 | * First flushers are responsible for cascading flushes and | |
1368 | * handling overflow. Non-first flushers can simply return. | |
1369 | */ | |
1370 | if (wq->first_flusher != &this_flusher) | |
1371 | return; | |
1372 | ||
1373 | mutex_lock(&wq->flush_mutex); | |
1374 | ||
1375 | wq->first_flusher = NULL; | |
1376 | ||
1377 | BUG_ON(!list_empty(&this_flusher.list)); | |
1378 | BUG_ON(wq->flush_color != this_flusher.flush_color); | |
1379 | ||
1380 | while (true) { | |
1381 | struct wq_flusher *next, *tmp; | |
1382 | ||
1383 | /* complete all the flushers sharing the current flush color */ | |
1384 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { | |
1385 | if (next->flush_color != wq->flush_color) | |
1386 | break; | |
1387 | list_del_init(&next->list); | |
1388 | complete(&next->done); | |
1389 | } | |
1390 | ||
1391 | BUG_ON(!list_empty(&wq->flusher_overflow) && | |
1392 | wq->flush_color != work_next_color(wq->work_color)); | |
1393 | ||
1394 | /* this flush_color is finished, advance by one */ | |
1395 | wq->flush_color = work_next_color(wq->flush_color); | |
1396 | ||
1397 | /* one color has been freed, handle overflow queue */ | |
1398 | if (!list_empty(&wq->flusher_overflow)) { | |
1399 | /* | |
1400 | * Assign the same color to all overflowed | |
1401 | * flushers, advance work_color and append to | |
1402 | * flusher_queue. This is the start-to-wait | |
1403 | * phase for these overflowed flushers. | |
1404 | */ | |
1405 | list_for_each_entry(tmp, &wq->flusher_overflow, list) | |
1406 | tmp->flush_color = wq->work_color; | |
1407 | ||
1408 | wq->work_color = work_next_color(wq->work_color); | |
1409 | ||
1410 | list_splice_tail_init(&wq->flusher_overflow, | |
1411 | &wq->flusher_queue); | |
1412 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); | |
1413 | } | |
1414 | ||
1415 | if (list_empty(&wq->flusher_queue)) { | |
1416 | BUG_ON(wq->flush_color != wq->work_color); | |
1417 | break; | |
1418 | } | |
1419 | ||
1420 | /* | |
1421 | * Need to flush more colors. Make the next flusher | |
1422 | * the new first flusher and arm cwqs. | |
1423 | */ | |
1424 | BUG_ON(wq->flush_color == wq->work_color); | |
1425 | BUG_ON(wq->flush_color != next->flush_color); | |
1426 | ||
1427 | list_del_init(&next->list); | |
1428 | wq->first_flusher = next; | |
1429 | ||
1430 | if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) | |
1431 | break; | |
1432 | ||
1433 | /* | |
1434 | * Meh... this color is already done, clear first | |
1435 | * flusher and repeat cascading. | |
1436 | */ | |
1437 | wq->first_flusher = NULL; | |
1438 | } | |
1439 | ||
1440 | out_unlock: | |
1441 | mutex_unlock(&wq->flush_mutex); | |
1da177e4 | 1442 | } |
ae90dd5d | 1443 | EXPORT_SYMBOL_GPL(flush_workqueue); |
1da177e4 | 1444 | |
db700897 ON |
1445 | /** |
1446 | * flush_work - block until a work_struct's callback has terminated | |
1447 | * @work: the work which is to be flushed | |
1448 | * | |
a67da70d ON |
1449 | * Returns false if @work has already terminated. |
1450 | * | |
db700897 ON |
1451 | * It is expected that, prior to calling flush_work(), the caller has |
1452 | * arranged for the work to not be requeued, otherwise it doesn't make | |
1453 | * sense to use this function. | |
1454 | */ | |
1455 | int flush_work(struct work_struct *work) | |
1456 | { | |
affee4b2 | 1457 | struct worker *worker = NULL; |
8b03ae3c | 1458 | struct global_cwq *gcwq; |
7a22ad75 | 1459 | struct cpu_workqueue_struct *cwq; |
db700897 ON |
1460 | struct wq_barrier barr; |
1461 | ||
1462 | might_sleep(); | |
7a22ad75 TH |
1463 | gcwq = get_work_gcwq(work); |
1464 | if (!gcwq) | |
db700897 | 1465 | return 0; |
a67da70d | 1466 | |
8b03ae3c | 1467 | spin_lock_irq(&gcwq->lock); |
db700897 ON |
1468 | if (!list_empty(&work->entry)) { |
1469 | /* | |
1470 | * See the comment near try_to_grab_pending()->smp_rmb(). | |
7a22ad75 TH |
1471 | * If it was re-queued to a different gcwq under us, we |
1472 | * are not going to wait. | |
db700897 ON |
1473 | */ |
1474 | smp_rmb(); | |
7a22ad75 TH |
1475 | cwq = get_work_cwq(work); |
1476 | if (unlikely(!cwq || gcwq != cwq->gcwq)) | |
4690c4ab | 1477 | goto already_gone; |
db700897 | 1478 | } else { |
7a22ad75 | 1479 | worker = find_worker_executing_work(gcwq, work); |
affee4b2 | 1480 | if (!worker) |
4690c4ab | 1481 | goto already_gone; |
7a22ad75 | 1482 | cwq = worker->current_cwq; |
db700897 | 1483 | } |
db700897 | 1484 | |
affee4b2 | 1485 | insert_wq_barrier(cwq, &barr, work, worker); |
8b03ae3c | 1486 | spin_unlock_irq(&gcwq->lock); |
7a22ad75 TH |
1487 | |
1488 | lock_map_acquire(&cwq->wq->lockdep_map); | |
1489 | lock_map_release(&cwq->wq->lockdep_map); | |
1490 | ||
db700897 | 1491 | wait_for_completion(&barr.done); |
dc186ad7 | 1492 | destroy_work_on_stack(&barr.work); |
db700897 | 1493 | return 1; |
4690c4ab | 1494 | already_gone: |
8b03ae3c | 1495 | spin_unlock_irq(&gcwq->lock); |
4690c4ab | 1496 | return 0; |
db700897 ON |
1497 | } |
1498 | EXPORT_SYMBOL_GPL(flush_work); | |
1499 | ||
6e84d644 | 1500 | /* |
1f1f642e | 1501 | * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, |
6e84d644 ON |
1502 | * so this work can't be re-armed in any way. |
1503 | */ | |
1504 | static int try_to_grab_pending(struct work_struct *work) | |
1505 | { | |
8b03ae3c | 1506 | struct global_cwq *gcwq; |
1f1f642e | 1507 | int ret = -1; |
6e84d644 | 1508 | |
22df02bb | 1509 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1f1f642e | 1510 | return 0; |
6e84d644 ON |
1511 | |
1512 | /* | |
1513 | * The queueing is in progress, or it is already queued. Try to | |
1514 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. | |
1515 | */ | |
7a22ad75 TH |
1516 | gcwq = get_work_gcwq(work); |
1517 | if (!gcwq) | |
6e84d644 ON |
1518 | return ret; |
1519 | ||
8b03ae3c | 1520 | spin_lock_irq(&gcwq->lock); |
6e84d644 ON |
1521 | if (!list_empty(&work->entry)) { |
1522 | /* | |
7a22ad75 | 1523 | * This work is queued, but perhaps we locked the wrong gcwq. |
6e84d644 ON |
1524 | * In that case we must see the new value after rmb(), see |
1525 | * insert_work()->wmb(). | |
1526 | */ | |
1527 | smp_rmb(); | |
7a22ad75 | 1528 | if (gcwq == get_work_gcwq(work)) { |
dc186ad7 | 1529 | debug_work_deactivate(work); |
6e84d644 | 1530 | list_del_init(&work->entry); |
7a22ad75 TH |
1531 | cwq_dec_nr_in_flight(get_work_cwq(work), |
1532 | get_work_color(work)); | |
6e84d644 ON |
1533 | ret = 1; |
1534 | } | |
1535 | } | |
8b03ae3c | 1536 | spin_unlock_irq(&gcwq->lock); |
6e84d644 ON |
1537 | |
1538 | return ret; | |
1539 | } | |
1540 | ||
7a22ad75 | 1541 | static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) |
b89deed3 ON |
1542 | { |
1543 | struct wq_barrier barr; | |
affee4b2 | 1544 | struct worker *worker; |
b89deed3 | 1545 | |
8b03ae3c | 1546 | spin_lock_irq(&gcwq->lock); |
affee4b2 | 1547 | |
7a22ad75 TH |
1548 | worker = find_worker_executing_work(gcwq, work); |
1549 | if (unlikely(worker)) | |
1550 | insert_wq_barrier(worker->current_cwq, &barr, work, worker); | |
affee4b2 | 1551 | |
8b03ae3c | 1552 | spin_unlock_irq(&gcwq->lock); |
b89deed3 | 1553 | |
affee4b2 | 1554 | if (unlikely(worker)) { |
b89deed3 | 1555 | wait_for_completion(&barr.done); |
dc186ad7 TG |
1556 | destroy_work_on_stack(&barr.work); |
1557 | } | |
b89deed3 ON |
1558 | } |
1559 | ||
6e84d644 | 1560 | static void wait_on_work(struct work_struct *work) |
b89deed3 | 1561 | { |
b1f4ec17 | 1562 | int cpu; |
b89deed3 | 1563 | |
f293ea92 ON |
1564 | might_sleep(); |
1565 | ||
3295f0ef IM |
1566 | lock_map_acquire(&work->lockdep_map); |
1567 | lock_map_release(&work->lockdep_map); | |
4e6045f1 | 1568 | |
1537663f | 1569 | for_each_possible_cpu(cpu) |
7a22ad75 | 1570 | wait_on_cpu_work(get_gcwq(cpu), work); |
6e84d644 ON |
1571 | } |
1572 | ||
1f1f642e ON |
1573 | static int __cancel_work_timer(struct work_struct *work, |
1574 | struct timer_list* timer) | |
1575 | { | |
1576 | int ret; | |
1577 | ||
1578 | do { | |
1579 | ret = (timer && likely(del_timer(timer))); | |
1580 | if (!ret) | |
1581 | ret = try_to_grab_pending(work); | |
1582 | wait_on_work(work); | |
1583 | } while (unlikely(ret < 0)); | |
1584 | ||
7a22ad75 | 1585 | clear_work_data(work); |
1f1f642e ON |
1586 | return ret; |
1587 | } | |
1588 | ||
6e84d644 ON |
1589 | /** |
1590 | * cancel_work_sync - block until a work_struct's callback has terminated | |
1591 | * @work: the work which is to be flushed | |
1592 | * | |
1f1f642e ON |
1593 | * Returns true if @work was pending. |
1594 | * | |
6e84d644 ON |
1595 | * cancel_work_sync() will cancel the work if it is queued. If the work's |
1596 | * callback appears to be running, cancel_work_sync() will block until it | |
1597 | * has completed. | |
1598 | * | |
1599 | * It is possible to use this function if the work re-queues itself. It can | |
1600 | * cancel the work even if it migrates to another workqueue, however in that | |
1601 | * case it only guarantees that work->func() has completed on the last queued | |
1602 | * workqueue. | |
1603 | * | |
1604 | * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not | |
1605 | * pending, otherwise it goes into a busy-wait loop until the timer expires. | |
1606 | * | |
1607 | * The caller must ensure that workqueue_struct on which this work was last | |
1608 | * queued can't be destroyed before this function returns. | |
1609 | */ | |
1f1f642e | 1610 | int cancel_work_sync(struct work_struct *work) |
6e84d644 | 1611 | { |
1f1f642e | 1612 | return __cancel_work_timer(work, NULL); |
b89deed3 | 1613 | } |
28e53bdd | 1614 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
b89deed3 | 1615 | |
6e84d644 | 1616 | /** |
f5a421a4 | 1617 | * cancel_delayed_work_sync - reliably kill off a delayed work. |
6e84d644 ON |
1618 | * @dwork: the delayed work struct |
1619 | * | |
1f1f642e ON |
1620 | * Returns true if @dwork was pending. |
1621 | * | |
6e84d644 ON |
1622 | * It is possible to use this function if @dwork rearms itself via queue_work() |
1623 | * or queue_delayed_work(). See also the comment for cancel_work_sync(). | |
1624 | */ | |
1f1f642e | 1625 | int cancel_delayed_work_sync(struct delayed_work *dwork) |
6e84d644 | 1626 | { |
1f1f642e | 1627 | return __cancel_work_timer(&dwork->work, &dwork->timer); |
6e84d644 | 1628 | } |
f5a421a4 | 1629 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
1da177e4 | 1630 | |
6e84d644 | 1631 | static struct workqueue_struct *keventd_wq __read_mostly; |
1da177e4 | 1632 | |
0fcb78c2 REB |
1633 | /** |
1634 | * schedule_work - put work task in global workqueue | |
1635 | * @work: job to be done | |
1636 | * | |
5b0f437d BVA |
1637 | * Returns zero if @work was already on the kernel-global workqueue and |
1638 | * non-zero otherwise. | |
1639 | * | |
1640 | * This puts a job in the kernel-global workqueue if it was not already | |
1641 | * queued and leaves it in the same position on the kernel-global | |
1642 | * workqueue otherwise. | |
0fcb78c2 | 1643 | */ |
7ad5b3a5 | 1644 | int schedule_work(struct work_struct *work) |
1da177e4 LT |
1645 | { |
1646 | return queue_work(keventd_wq, work); | |
1647 | } | |
ae90dd5d | 1648 | EXPORT_SYMBOL(schedule_work); |
1da177e4 | 1649 | |
c1a220e7 ZR |
1650 | /* |
1651 | * schedule_work_on - put work task on a specific cpu | |
1652 | * @cpu: cpu to put the work task on | |
1653 | * @work: job to be done | |
1654 | * | |
1655 | * This puts a job on a specific cpu | |
1656 | */ | |
1657 | int schedule_work_on(int cpu, struct work_struct *work) | |
1658 | { | |
1659 | return queue_work_on(cpu, keventd_wq, work); | |
1660 | } | |
1661 | EXPORT_SYMBOL(schedule_work_on); | |
1662 | ||
0fcb78c2 REB |
1663 | /** |
1664 | * schedule_delayed_work - put work task in global workqueue after delay | |
52bad64d DH |
1665 | * @dwork: job to be done |
1666 | * @delay: number of jiffies to wait or 0 for immediate execution | |
0fcb78c2 REB |
1667 | * |
1668 | * After waiting for a given time this puts a job in the kernel-global | |
1669 | * workqueue. | |
1670 | */ | |
7ad5b3a5 | 1671 | int schedule_delayed_work(struct delayed_work *dwork, |
82f67cd9 | 1672 | unsigned long delay) |
1da177e4 | 1673 | { |
52bad64d | 1674 | return queue_delayed_work(keventd_wq, dwork, delay); |
1da177e4 | 1675 | } |
ae90dd5d | 1676 | EXPORT_SYMBOL(schedule_delayed_work); |
1da177e4 | 1677 | |
8c53e463 LT |
1678 | /** |
1679 | * flush_delayed_work - block until a dwork_struct's callback has terminated | |
1680 | * @dwork: the delayed work which is to be flushed | |
1681 | * | |
1682 | * Any timeout is cancelled, and any pending work is run immediately. | |
1683 | */ | |
1684 | void flush_delayed_work(struct delayed_work *dwork) | |
1685 | { | |
1686 | if (del_timer_sync(&dwork->timer)) { | |
7a22ad75 | 1687 | __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq, |
4690c4ab | 1688 | &dwork->work); |
8c53e463 LT |
1689 | put_cpu(); |
1690 | } | |
1691 | flush_work(&dwork->work); | |
1692 | } | |
1693 | EXPORT_SYMBOL(flush_delayed_work); | |
1694 | ||
0fcb78c2 REB |
1695 | /** |
1696 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay | |
1697 | * @cpu: cpu to use | |
52bad64d | 1698 | * @dwork: job to be done |
0fcb78c2 REB |
1699 | * @delay: number of jiffies to wait |
1700 | * | |
1701 | * After waiting for a given time this puts a job in the kernel-global | |
1702 | * workqueue on the specified CPU. | |
1703 | */ | |
1da177e4 | 1704 | int schedule_delayed_work_on(int cpu, |
52bad64d | 1705 | struct delayed_work *dwork, unsigned long delay) |
1da177e4 | 1706 | { |
52bad64d | 1707 | return queue_delayed_work_on(cpu, keventd_wq, dwork, delay); |
1da177e4 | 1708 | } |
ae90dd5d | 1709 | EXPORT_SYMBOL(schedule_delayed_work_on); |
1da177e4 | 1710 | |
b6136773 AM |
1711 | /** |
1712 | * schedule_on_each_cpu - call a function on each online CPU from keventd | |
1713 | * @func: the function to call | |
b6136773 AM |
1714 | * |
1715 | * Returns zero on success. | |
1716 | * Returns -ve errno on failure. | |
1717 | * | |
b6136773 AM |
1718 | * schedule_on_each_cpu() is very slow. |
1719 | */ | |
65f27f38 | 1720 | int schedule_on_each_cpu(work_func_t func) |
15316ba8 CL |
1721 | { |
1722 | int cpu; | |
65a64464 | 1723 | int orig = -1; |
b6136773 | 1724 | struct work_struct *works; |
15316ba8 | 1725 | |
b6136773 AM |
1726 | works = alloc_percpu(struct work_struct); |
1727 | if (!works) | |
15316ba8 | 1728 | return -ENOMEM; |
b6136773 | 1729 | |
93981800 TH |
1730 | get_online_cpus(); |
1731 | ||
65a64464 | 1732 | /* |
93981800 TH |
1733 | * When running in keventd don't schedule a work item on |
1734 | * itself. Can just call directly because the work queue is | |
1735 | * already bound. This also is faster. | |
65a64464 | 1736 | */ |
93981800 | 1737 | if (current_is_keventd()) |
65a64464 | 1738 | orig = raw_smp_processor_id(); |
65a64464 | 1739 | |
15316ba8 | 1740 | for_each_online_cpu(cpu) { |
9bfb1839 IM |
1741 | struct work_struct *work = per_cpu_ptr(works, cpu); |
1742 | ||
1743 | INIT_WORK(work, func); | |
65a64464 | 1744 | if (cpu != orig) |
93981800 | 1745 | schedule_work_on(cpu, work); |
65a64464 | 1746 | } |
93981800 TH |
1747 | if (orig >= 0) |
1748 | func(per_cpu_ptr(works, orig)); | |
1749 | ||
1750 | for_each_online_cpu(cpu) | |
1751 | flush_work(per_cpu_ptr(works, cpu)); | |
1752 | ||
95402b38 | 1753 | put_online_cpus(); |
b6136773 | 1754 | free_percpu(works); |
15316ba8 CL |
1755 | return 0; |
1756 | } | |
1757 | ||
eef6a7d5 AS |
1758 | /** |
1759 | * flush_scheduled_work - ensure that any scheduled work has run to completion. | |
1760 | * | |
1761 | * Forces execution of the kernel-global workqueue and blocks until its | |
1762 | * completion. | |
1763 | * | |
1764 | * Think twice before calling this function! It's very easy to get into | |
1765 | * trouble if you don't take great care. Either of the following situations | |
1766 | * will lead to deadlock: | |
1767 | * | |
1768 | * One of the work items currently on the workqueue needs to acquire | |
1769 | * a lock held by your code or its caller. | |
1770 | * | |
1771 | * Your code is running in the context of a work routine. | |
1772 | * | |
1773 | * They will be detected by lockdep when they occur, but the first might not | |
1774 | * occur very often. It depends on what work items are on the workqueue and | |
1775 | * what locks they need, which you have no control over. | |
1776 | * | |
1777 | * In most situations flushing the entire workqueue is overkill; you merely | |
1778 | * need to know that a particular work item isn't queued and isn't running. | |
1779 | * In such cases you should use cancel_delayed_work_sync() or | |
1780 | * cancel_work_sync() instead. | |
1781 | */ | |
1da177e4 LT |
1782 | void flush_scheduled_work(void) |
1783 | { | |
1784 | flush_workqueue(keventd_wq); | |
1785 | } | |
ae90dd5d | 1786 | EXPORT_SYMBOL(flush_scheduled_work); |
1da177e4 | 1787 | |
1fa44eca JB |
1788 | /** |
1789 | * execute_in_process_context - reliably execute the routine with user context | |
1790 | * @fn: the function to execute | |
1fa44eca JB |
1791 | * @ew: guaranteed storage for the execute work structure (must |
1792 | * be available when the work executes) | |
1793 | * | |
1794 | * Executes the function immediately if process context is available, | |
1795 | * otherwise schedules the function for delayed execution. | |
1796 | * | |
1797 | * Returns: 0 - function was executed | |
1798 | * 1 - function was scheduled for execution | |
1799 | */ | |
65f27f38 | 1800 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
1fa44eca JB |
1801 | { |
1802 | if (!in_interrupt()) { | |
65f27f38 | 1803 | fn(&ew->work); |
1fa44eca JB |
1804 | return 0; |
1805 | } | |
1806 | ||
65f27f38 | 1807 | INIT_WORK(&ew->work, fn); |
1fa44eca JB |
1808 | schedule_work(&ew->work); |
1809 | ||
1810 | return 1; | |
1811 | } | |
1812 | EXPORT_SYMBOL_GPL(execute_in_process_context); | |
1813 | ||
1da177e4 LT |
1814 | int keventd_up(void) |
1815 | { | |
1816 | return keventd_wq != NULL; | |
1817 | } | |
1818 | ||
1819 | int current_is_keventd(void) | |
1820 | { | |
1821 | struct cpu_workqueue_struct *cwq; | |
d243769d | 1822 | int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ |
1da177e4 LT |
1823 | int ret = 0; |
1824 | ||
1825 | BUG_ON(!keventd_wq); | |
1826 | ||
1537663f | 1827 | cwq = get_cwq(cpu, keventd_wq); |
c34056a3 | 1828 | if (current == cwq->worker->task) |
1da177e4 LT |
1829 | ret = 1; |
1830 | ||
1831 | return ret; | |
1832 | ||
1833 | } | |
1834 | ||
0f900049 TH |
1835 | static struct cpu_workqueue_struct *alloc_cwqs(void) |
1836 | { | |
1837 | /* | |
1838 | * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. | |
1839 | * Make sure that the alignment isn't lower than that of | |
1840 | * unsigned long long. | |
1841 | */ | |
1842 | const size_t size = sizeof(struct cpu_workqueue_struct); | |
1843 | const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, | |
1844 | __alignof__(unsigned long long)); | |
1845 | struct cpu_workqueue_struct *cwqs; | |
1846 | #ifndef CONFIG_SMP | |
1847 | void *ptr; | |
1848 | ||
1849 | /* | |
1850 | * On UP, percpu allocator doesn't honor alignment parameter | |
1851 | * and simply uses arch-dependent default. Allocate enough | |
1852 | * room to align cwq and put an extra pointer at the end | |
1853 | * pointing back to the originally allocated pointer which | |
1854 | * will be used for free. | |
1855 | * | |
1856 | * FIXME: This really belongs to UP percpu code. Update UP | |
1857 | * percpu code to honor alignment and remove this ugliness. | |
1858 | */ | |
1859 | ptr = __alloc_percpu(size + align + sizeof(void *), 1); | |
1860 | cwqs = PTR_ALIGN(ptr, align); | |
1861 | *(void **)per_cpu_ptr(cwqs + 1, 0) = ptr; | |
1862 | #else | |
1863 | /* On SMP, percpu allocator can do it itself */ | |
1864 | cwqs = __alloc_percpu(size, align); | |
1865 | #endif | |
1866 | /* just in case, make sure it's actually aligned */ | |
1867 | BUG_ON(!IS_ALIGNED((unsigned long)cwqs, align)); | |
1868 | return cwqs; | |
1869 | } | |
1870 | ||
1871 | static void free_cwqs(struct cpu_workqueue_struct *cwqs) | |
1872 | { | |
1873 | #ifndef CONFIG_SMP | |
1874 | /* on UP, the pointer to free is stored right after the cwq */ | |
1875 | if (cwqs) | |
1876 | free_percpu(*(void **)per_cpu_ptr(cwqs + 1, 0)); | |
1877 | #else | |
1878 | free_percpu(cwqs); | |
1879 | #endif | |
1880 | } | |
1881 | ||
4e6045f1 | 1882 | struct workqueue_struct *__create_workqueue_key(const char *name, |
97e37d7b | 1883 | unsigned int flags, |
1e19ffc6 | 1884 | int max_active, |
eb13ba87 JB |
1885 | struct lock_class_key *key, |
1886 | const char *lock_name) | |
1da177e4 | 1887 | { |
1da177e4 | 1888 | struct workqueue_struct *wq; |
c34056a3 TH |
1889 | bool failed = false; |
1890 | unsigned int cpu; | |
1da177e4 | 1891 | |
1e19ffc6 TH |
1892 | max_active = clamp_val(max_active, 1, INT_MAX); |
1893 | ||
3af24433 ON |
1894 | wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
1895 | if (!wq) | |
4690c4ab | 1896 | goto err; |
3af24433 | 1897 | |
0f900049 | 1898 | wq->cpu_wq = alloc_cwqs(); |
4690c4ab TH |
1899 | if (!wq->cpu_wq) |
1900 | goto err; | |
3af24433 | 1901 | |
97e37d7b | 1902 | wq->flags = flags; |
a0a1a5fd | 1903 | wq->saved_max_active = max_active; |
73f53c4a TH |
1904 | mutex_init(&wq->flush_mutex); |
1905 | atomic_set(&wq->nr_cwqs_to_flush, 0); | |
1906 | INIT_LIST_HEAD(&wq->flusher_queue); | |
1907 | INIT_LIST_HEAD(&wq->flusher_overflow); | |
502ca9d8 TH |
1908 | wq->single_cpu = NR_CPUS; |
1909 | ||
3af24433 | 1910 | wq->name = name; |
eb13ba87 | 1911 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
cce1a165 | 1912 | INIT_LIST_HEAD(&wq->list); |
3af24433 | 1913 | |
1537663f TH |
1914 | cpu_maps_update_begin(); |
1915 | /* | |
1916 | * We must initialize cwqs for each possible cpu even if we | |
1917 | * are going to call destroy_workqueue() finally. Otherwise | |
1918 | * cpu_up() can hit the uninitialized cwq once we drop the | |
1919 | * lock. | |
1920 | */ | |
1921 | for_each_possible_cpu(cpu) { | |
1922 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
8b03ae3c | 1923 | struct global_cwq *gcwq = get_gcwq(cpu); |
1537663f | 1924 | |
0f900049 | 1925 | BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); |
8b03ae3c | 1926 | cwq->gcwq = gcwq; |
c34056a3 | 1927 | cwq->wq = wq; |
73f53c4a | 1928 | cwq->flush_color = -1; |
1e19ffc6 | 1929 | cwq->max_active = max_active; |
1537663f | 1930 | INIT_LIST_HEAD(&cwq->worklist); |
1e19ffc6 | 1931 | INIT_LIST_HEAD(&cwq->delayed_works); |
1537663f | 1932 | |
c34056a3 | 1933 | if (failed) |
1537663f | 1934 | continue; |
502ca9d8 | 1935 | cwq->worker = create_worker(cwq, cpu_online(cpu)); |
c34056a3 TH |
1936 | if (cwq->worker) |
1937 | start_worker(cwq->worker); | |
1537663f | 1938 | else |
c34056a3 | 1939 | failed = true; |
3af24433 ON |
1940 | } |
1941 | ||
a0a1a5fd TH |
1942 | /* |
1943 | * workqueue_lock protects global freeze state and workqueues | |
1944 | * list. Grab it, set max_active accordingly and add the new | |
1945 | * workqueue to workqueues list. | |
1946 | */ | |
1537663f | 1947 | spin_lock(&workqueue_lock); |
a0a1a5fd TH |
1948 | |
1949 | if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) | |
1950 | for_each_possible_cpu(cpu) | |
1951 | get_cwq(cpu, wq)->max_active = 0; | |
1952 | ||
1537663f | 1953 | list_add(&wq->list, &workqueues); |
a0a1a5fd | 1954 | |
1537663f TH |
1955 | spin_unlock(&workqueue_lock); |
1956 | ||
1957 | cpu_maps_update_done(); | |
1958 | ||
c34056a3 | 1959 | if (failed) { |
3af24433 ON |
1960 | destroy_workqueue(wq); |
1961 | wq = NULL; | |
1962 | } | |
1963 | return wq; | |
4690c4ab TH |
1964 | err: |
1965 | if (wq) { | |
0f900049 | 1966 | free_cwqs(wq->cpu_wq); |
4690c4ab TH |
1967 | kfree(wq); |
1968 | } | |
1969 | return NULL; | |
3af24433 | 1970 | } |
4e6045f1 | 1971 | EXPORT_SYMBOL_GPL(__create_workqueue_key); |
1da177e4 | 1972 | |
3af24433 ON |
1973 | /** |
1974 | * destroy_workqueue - safely terminate a workqueue | |
1975 | * @wq: target workqueue | |
1976 | * | |
1977 | * Safely destroy a workqueue. All work currently pending will be done first. | |
1978 | */ | |
1979 | void destroy_workqueue(struct workqueue_struct *wq) | |
1980 | { | |
c8e55f36 | 1981 | unsigned int cpu; |
3af24433 | 1982 | |
a0a1a5fd TH |
1983 | flush_workqueue(wq); |
1984 | ||
1985 | /* | |
1986 | * wq list is used to freeze wq, remove from list after | |
1987 | * flushing is complete in case freeze races us. | |
1988 | */ | |
3da1c84c | 1989 | cpu_maps_update_begin(); |
95402b38 | 1990 | spin_lock(&workqueue_lock); |
b1f4ec17 | 1991 | list_del(&wq->list); |
95402b38 | 1992 | spin_unlock(&workqueue_lock); |
1537663f | 1993 | cpu_maps_update_done(); |
3af24433 | 1994 | |
73f53c4a TH |
1995 | for_each_possible_cpu(cpu) { |
1996 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
1997 | int i; | |
1998 | ||
c34056a3 | 1999 | if (cwq->worker) { |
c8e55f36 | 2000 | spin_lock_irq(&cwq->gcwq->lock); |
c34056a3 TH |
2001 | destroy_worker(cwq->worker); |
2002 | cwq->worker = NULL; | |
c8e55f36 | 2003 | spin_unlock_irq(&cwq->gcwq->lock); |
73f53c4a TH |
2004 | } |
2005 | ||
2006 | for (i = 0; i < WORK_NR_COLORS; i++) | |
2007 | BUG_ON(cwq->nr_in_flight[i]); | |
1e19ffc6 TH |
2008 | BUG_ON(cwq->nr_active); |
2009 | BUG_ON(!list_empty(&cwq->delayed_works)); | |
73f53c4a | 2010 | } |
9b41ea72 | 2011 | |
0f900049 | 2012 | free_cwqs(wq->cpu_wq); |
3af24433 ON |
2013 | kfree(wq); |
2014 | } | |
2015 | EXPORT_SYMBOL_GPL(destroy_workqueue); | |
2016 | ||
db7bccf4 TH |
2017 | /* |
2018 | * CPU hotplug. | |
2019 | * | |
2020 | * CPU hotplug is implemented by allowing cwqs to be detached from | |
2021 | * CPU, running with unbound workers and allowing them to be | |
2022 | * reattached later if the cpu comes back online. A separate thread | |
2023 | * is created to govern cwqs in such state and is called the trustee. | |
2024 | * | |
2025 | * Trustee states and their descriptions. | |
2026 | * | |
2027 | * START Command state used on startup. On CPU_DOWN_PREPARE, a | |
2028 | * new trustee is started with this state. | |
2029 | * | |
2030 | * IN_CHARGE Once started, trustee will enter this state after | |
2031 | * making all existing workers rogue. DOWN_PREPARE waits | |
2032 | * for trustee to enter this state. After reaching | |
2033 | * IN_CHARGE, trustee tries to execute the pending | |
2034 | * worklist until it's empty and the state is set to | |
2035 | * BUTCHER, or the state is set to RELEASE. | |
2036 | * | |
2037 | * BUTCHER Command state which is set by the cpu callback after | |
2038 | * the cpu has went down. Once this state is set trustee | |
2039 | * knows that there will be no new works on the worklist | |
2040 | * and once the worklist is empty it can proceed to | |
2041 | * killing idle workers. | |
2042 | * | |
2043 | * RELEASE Command state which is set by the cpu callback if the | |
2044 | * cpu down has been canceled or it has come online | |
2045 | * again. After recognizing this state, trustee stops | |
2046 | * trying to drain or butcher and transits to DONE. | |
2047 | * | |
2048 | * DONE Trustee will enter this state after BUTCHER or RELEASE | |
2049 | * is complete. | |
2050 | * | |
2051 | * trustee CPU draining | |
2052 | * took over down complete | |
2053 | * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE | |
2054 | * | | ^ | |
2055 | * | CPU is back online v return workers | | |
2056 | * ----------------> RELEASE -------------- | |
2057 | */ | |
2058 | ||
2059 | /** | |
2060 | * trustee_wait_event_timeout - timed event wait for trustee | |
2061 | * @cond: condition to wait for | |
2062 | * @timeout: timeout in jiffies | |
2063 | * | |
2064 | * wait_event_timeout() for trustee to use. Handles locking and | |
2065 | * checks for RELEASE request. | |
2066 | * | |
2067 | * CONTEXT: | |
2068 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
2069 | * multiple times. To be used by trustee. | |
2070 | * | |
2071 | * RETURNS: | |
2072 | * Positive indicating left time if @cond is satisfied, 0 if timed | |
2073 | * out, -1 if canceled. | |
2074 | */ | |
2075 | #define trustee_wait_event_timeout(cond, timeout) ({ \ | |
2076 | long __ret = (timeout); \ | |
2077 | while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ | |
2078 | __ret) { \ | |
2079 | spin_unlock_irq(&gcwq->lock); \ | |
2080 | __wait_event_timeout(gcwq->trustee_wait, (cond) || \ | |
2081 | (gcwq->trustee_state == TRUSTEE_RELEASE), \ | |
2082 | __ret); \ | |
2083 | spin_lock_irq(&gcwq->lock); \ | |
2084 | } \ | |
2085 | gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ | |
2086 | }) | |
2087 | ||
2088 | /** | |
2089 | * trustee_wait_event - event wait for trustee | |
2090 | * @cond: condition to wait for | |
2091 | * | |
2092 | * wait_event() for trustee to use. Automatically handles locking and | |
2093 | * checks for CANCEL request. | |
2094 | * | |
2095 | * CONTEXT: | |
2096 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
2097 | * multiple times. To be used by trustee. | |
2098 | * | |
2099 | * RETURNS: | |
2100 | * 0 if @cond is satisfied, -1 if canceled. | |
2101 | */ | |
2102 | #define trustee_wait_event(cond) ({ \ | |
2103 | long __ret1; \ | |
2104 | __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ | |
2105 | __ret1 < 0 ? -1 : 0; \ | |
2106 | }) | |
2107 | ||
2108 | static int __cpuinit trustee_thread(void *__gcwq) | |
2109 | { | |
2110 | struct global_cwq *gcwq = __gcwq; | |
2111 | struct worker *worker; | |
2112 | struct hlist_node *pos; | |
2113 | int i; | |
2114 | ||
2115 | BUG_ON(gcwq->cpu != smp_processor_id()); | |
2116 | ||
2117 | spin_lock_irq(&gcwq->lock); | |
2118 | /* | |
502ca9d8 TH |
2119 | * Make all workers rogue. Trustee must be bound to the |
2120 | * target cpu and can't be cancelled. | |
db7bccf4 TH |
2121 | */ |
2122 | BUG_ON(gcwq->cpu != smp_processor_id()); | |
2123 | ||
2124 | list_for_each_entry(worker, &gcwq->idle_list, entry) | |
502ca9d8 | 2125 | worker->flags |= WORKER_ROGUE; |
db7bccf4 TH |
2126 | |
2127 | for_each_busy_worker(worker, i, pos, gcwq) | |
502ca9d8 | 2128 | worker->flags |= WORKER_ROGUE; |
db7bccf4 TH |
2129 | |
2130 | /* | |
2131 | * We're now in charge. Notify and proceed to drain. We need | |
2132 | * to keep the gcwq running during the whole CPU down | |
2133 | * procedure as other cpu hotunplug callbacks may need to | |
2134 | * flush currently running tasks. | |
2135 | */ | |
2136 | gcwq->trustee_state = TRUSTEE_IN_CHARGE; | |
2137 | wake_up_all(&gcwq->trustee_wait); | |
2138 | ||
2139 | /* | |
2140 | * The original cpu is in the process of dying and may go away | |
2141 | * anytime now. When that happens, we and all workers would | |
2142 | * be migrated to other cpus. Try draining any left work. | |
2143 | * Note that if the gcwq is frozen, there may be frozen works | |
2144 | * in freezeable cwqs. Don't declare completion while frozen. | |
2145 | */ | |
2146 | while (gcwq->nr_workers != gcwq->nr_idle || | |
2147 | gcwq->flags & GCWQ_FREEZING || | |
2148 | gcwq->trustee_state == TRUSTEE_IN_CHARGE) { | |
2149 | /* give a breather */ | |
2150 | if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) | |
2151 | break; | |
2152 | } | |
2153 | ||
2154 | /* notify completion */ | |
2155 | gcwq->trustee = NULL; | |
2156 | gcwq->trustee_state = TRUSTEE_DONE; | |
2157 | wake_up_all(&gcwq->trustee_wait); | |
2158 | spin_unlock_irq(&gcwq->lock); | |
2159 | return 0; | |
2160 | } | |
2161 | ||
2162 | /** | |
2163 | * wait_trustee_state - wait for trustee to enter the specified state | |
2164 | * @gcwq: gcwq the trustee of interest belongs to | |
2165 | * @state: target state to wait for | |
2166 | * | |
2167 | * Wait for the trustee to reach @state. DONE is already matched. | |
2168 | * | |
2169 | * CONTEXT: | |
2170 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
2171 | * multiple times. To be used by cpu_callback. | |
2172 | */ | |
2173 | static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) | |
2174 | { | |
2175 | if (!(gcwq->trustee_state == state || | |
2176 | gcwq->trustee_state == TRUSTEE_DONE)) { | |
2177 | spin_unlock_irq(&gcwq->lock); | |
2178 | __wait_event(gcwq->trustee_wait, | |
2179 | gcwq->trustee_state == state || | |
2180 | gcwq->trustee_state == TRUSTEE_DONE); | |
2181 | spin_lock_irq(&gcwq->lock); | |
2182 | } | |
2183 | } | |
2184 | ||
3af24433 ON |
2185 | static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, |
2186 | unsigned long action, | |
2187 | void *hcpu) | |
2188 | { | |
2189 | unsigned int cpu = (unsigned long)hcpu; | |
db7bccf4 TH |
2190 | struct global_cwq *gcwq = get_gcwq(cpu); |
2191 | struct task_struct *new_trustee = NULL; | |
2192 | struct worker *worker; | |
2193 | struct hlist_node *pos; | |
2194 | unsigned long flags; | |
2195 | int i; | |
3af24433 | 2196 | |
8bb78442 RW |
2197 | action &= ~CPU_TASKS_FROZEN; |
2198 | ||
db7bccf4 TH |
2199 | switch (action) { |
2200 | case CPU_DOWN_PREPARE: | |
2201 | new_trustee = kthread_create(trustee_thread, gcwq, | |
2202 | "workqueue_trustee/%d\n", cpu); | |
2203 | if (IS_ERR(new_trustee)) | |
2204 | return notifier_from_errno(PTR_ERR(new_trustee)); | |
2205 | kthread_bind(new_trustee, cpu); | |
2206 | } | |
3af24433 | 2207 | |
db7bccf4 TH |
2208 | /* some are called w/ irq disabled, don't disturb irq status */ |
2209 | spin_lock_irqsave(&gcwq->lock, flags); | |
3af24433 | 2210 | |
db7bccf4 TH |
2211 | switch (action) { |
2212 | case CPU_DOWN_PREPARE: | |
2213 | /* initialize trustee and tell it to acquire the gcwq */ | |
2214 | BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); | |
2215 | gcwq->trustee = new_trustee; | |
2216 | gcwq->trustee_state = TRUSTEE_START; | |
2217 | wake_up_process(gcwq->trustee); | |
2218 | wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); | |
2219 | break; | |
2220 | ||
2221 | case CPU_POST_DEAD: | |
2222 | gcwq->trustee_state = TRUSTEE_BUTCHER; | |
2223 | break; | |
2224 | ||
2225 | case CPU_DOWN_FAILED: | |
2226 | case CPU_ONLINE: | |
2227 | if (gcwq->trustee_state != TRUSTEE_DONE) { | |
2228 | gcwq->trustee_state = TRUSTEE_RELEASE; | |
2229 | wake_up_process(gcwq->trustee); | |
2230 | wait_trustee_state(gcwq, TRUSTEE_DONE); | |
3af24433 | 2231 | } |
db7bccf4 | 2232 | |
502ca9d8 | 2233 | /* clear ROGUE from all workers */ |
db7bccf4 | 2234 | list_for_each_entry(worker, &gcwq->idle_list, entry) |
502ca9d8 | 2235 | worker->flags &= ~WORKER_ROGUE; |
db7bccf4 TH |
2236 | |
2237 | for_each_busy_worker(worker, i, pos, gcwq) | |
502ca9d8 | 2238 | worker->flags &= ~WORKER_ROGUE; |
db7bccf4 | 2239 | break; |
1da177e4 LT |
2240 | } |
2241 | ||
db7bccf4 TH |
2242 | spin_unlock_irqrestore(&gcwq->lock, flags); |
2243 | ||
1537663f | 2244 | return notifier_from_errno(0); |
1da177e4 | 2245 | } |
1da177e4 | 2246 | |
2d3854a3 | 2247 | #ifdef CONFIG_SMP |
8ccad40d | 2248 | |
2d3854a3 | 2249 | struct work_for_cpu { |
6b44003e | 2250 | struct completion completion; |
2d3854a3 RR |
2251 | long (*fn)(void *); |
2252 | void *arg; | |
2253 | long ret; | |
2254 | }; | |
2255 | ||
6b44003e | 2256 | static int do_work_for_cpu(void *_wfc) |
2d3854a3 | 2257 | { |
6b44003e | 2258 | struct work_for_cpu *wfc = _wfc; |
2d3854a3 | 2259 | wfc->ret = wfc->fn(wfc->arg); |
6b44003e AM |
2260 | complete(&wfc->completion); |
2261 | return 0; | |
2d3854a3 RR |
2262 | } |
2263 | ||
2264 | /** | |
2265 | * work_on_cpu - run a function in user context on a particular cpu | |
2266 | * @cpu: the cpu to run on | |
2267 | * @fn: the function to run | |
2268 | * @arg: the function arg | |
2269 | * | |
31ad9081 RR |
2270 | * This will return the value @fn returns. |
2271 | * It is up to the caller to ensure that the cpu doesn't go offline. | |
6b44003e | 2272 | * The caller must not hold any locks which would prevent @fn from completing. |
2d3854a3 RR |
2273 | */ |
2274 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) | |
2275 | { | |
6b44003e AM |
2276 | struct task_struct *sub_thread; |
2277 | struct work_for_cpu wfc = { | |
2278 | .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), | |
2279 | .fn = fn, | |
2280 | .arg = arg, | |
2281 | }; | |
2282 | ||
2283 | sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); | |
2284 | if (IS_ERR(sub_thread)) | |
2285 | return PTR_ERR(sub_thread); | |
2286 | kthread_bind(sub_thread, cpu); | |
2287 | wake_up_process(sub_thread); | |
2288 | wait_for_completion(&wfc.completion); | |
2d3854a3 RR |
2289 | return wfc.ret; |
2290 | } | |
2291 | EXPORT_SYMBOL_GPL(work_on_cpu); | |
2292 | #endif /* CONFIG_SMP */ | |
2293 | ||
a0a1a5fd TH |
2294 | #ifdef CONFIG_FREEZER |
2295 | ||
2296 | /** | |
2297 | * freeze_workqueues_begin - begin freezing workqueues | |
2298 | * | |
2299 | * Start freezing workqueues. After this function returns, all | |
2300 | * freezeable workqueues will queue new works to their frozen_works | |
2301 | * list instead of the cwq ones. | |
2302 | * | |
2303 | * CONTEXT: | |
8b03ae3c | 2304 | * Grabs and releases workqueue_lock and gcwq->lock's. |
a0a1a5fd TH |
2305 | */ |
2306 | void freeze_workqueues_begin(void) | |
2307 | { | |
2308 | struct workqueue_struct *wq; | |
2309 | unsigned int cpu; | |
2310 | ||
2311 | spin_lock(&workqueue_lock); | |
2312 | ||
2313 | BUG_ON(workqueue_freezing); | |
2314 | workqueue_freezing = true; | |
2315 | ||
2316 | for_each_possible_cpu(cpu) { | |
8b03ae3c TH |
2317 | struct global_cwq *gcwq = get_gcwq(cpu); |
2318 | ||
2319 | spin_lock_irq(&gcwq->lock); | |
2320 | ||
db7bccf4 TH |
2321 | BUG_ON(gcwq->flags & GCWQ_FREEZING); |
2322 | gcwq->flags |= GCWQ_FREEZING; | |
2323 | ||
a0a1a5fd TH |
2324 | list_for_each_entry(wq, &workqueues, list) { |
2325 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
2326 | ||
a0a1a5fd TH |
2327 | if (wq->flags & WQ_FREEZEABLE) |
2328 | cwq->max_active = 0; | |
a0a1a5fd | 2329 | } |
8b03ae3c TH |
2330 | |
2331 | spin_unlock_irq(&gcwq->lock); | |
a0a1a5fd TH |
2332 | } |
2333 | ||
2334 | spin_unlock(&workqueue_lock); | |
2335 | } | |
2336 | ||
2337 | /** | |
2338 | * freeze_workqueues_busy - are freezeable workqueues still busy? | |
2339 | * | |
2340 | * Check whether freezing is complete. This function must be called | |
2341 | * between freeze_workqueues_begin() and thaw_workqueues(). | |
2342 | * | |
2343 | * CONTEXT: | |
2344 | * Grabs and releases workqueue_lock. | |
2345 | * | |
2346 | * RETURNS: | |
2347 | * %true if some freezeable workqueues are still busy. %false if | |
2348 | * freezing is complete. | |
2349 | */ | |
2350 | bool freeze_workqueues_busy(void) | |
2351 | { | |
2352 | struct workqueue_struct *wq; | |
2353 | unsigned int cpu; | |
2354 | bool busy = false; | |
2355 | ||
2356 | spin_lock(&workqueue_lock); | |
2357 | ||
2358 | BUG_ON(!workqueue_freezing); | |
2359 | ||
2360 | for_each_possible_cpu(cpu) { | |
2361 | /* | |
2362 | * nr_active is monotonically decreasing. It's safe | |
2363 | * to peek without lock. | |
2364 | */ | |
2365 | list_for_each_entry(wq, &workqueues, list) { | |
2366 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
2367 | ||
2368 | if (!(wq->flags & WQ_FREEZEABLE)) | |
2369 | continue; | |
2370 | ||
2371 | BUG_ON(cwq->nr_active < 0); | |
2372 | if (cwq->nr_active) { | |
2373 | busy = true; | |
2374 | goto out_unlock; | |
2375 | } | |
2376 | } | |
2377 | } | |
2378 | out_unlock: | |
2379 | spin_unlock(&workqueue_lock); | |
2380 | return busy; | |
2381 | } | |
2382 | ||
2383 | /** | |
2384 | * thaw_workqueues - thaw workqueues | |
2385 | * | |
2386 | * Thaw workqueues. Normal queueing is restored and all collected | |
2387 | * frozen works are transferred to their respective cwq worklists. | |
2388 | * | |
2389 | * CONTEXT: | |
8b03ae3c | 2390 | * Grabs and releases workqueue_lock and gcwq->lock's. |
a0a1a5fd TH |
2391 | */ |
2392 | void thaw_workqueues(void) | |
2393 | { | |
2394 | struct workqueue_struct *wq; | |
2395 | unsigned int cpu; | |
2396 | ||
2397 | spin_lock(&workqueue_lock); | |
2398 | ||
2399 | if (!workqueue_freezing) | |
2400 | goto out_unlock; | |
2401 | ||
2402 | for_each_possible_cpu(cpu) { | |
8b03ae3c TH |
2403 | struct global_cwq *gcwq = get_gcwq(cpu); |
2404 | ||
2405 | spin_lock_irq(&gcwq->lock); | |
2406 | ||
db7bccf4 TH |
2407 | BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); |
2408 | gcwq->flags &= ~GCWQ_FREEZING; | |
2409 | ||
a0a1a5fd TH |
2410 | list_for_each_entry(wq, &workqueues, list) { |
2411 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
2412 | ||
2413 | if (!(wq->flags & WQ_FREEZEABLE)) | |
2414 | continue; | |
2415 | ||
a0a1a5fd TH |
2416 | /* restore max_active and repopulate worklist */ |
2417 | cwq->max_active = wq->saved_max_active; | |
2418 | ||
2419 | while (!list_empty(&cwq->delayed_works) && | |
2420 | cwq->nr_active < cwq->max_active) | |
2421 | cwq_activate_first_delayed(cwq); | |
2422 | ||
502ca9d8 TH |
2423 | /* perform delayed unbind from single cpu if empty */ |
2424 | if (wq->single_cpu == gcwq->cpu && | |
2425 | !cwq->nr_active && list_empty(&cwq->delayed_works)) | |
2426 | cwq_unbind_single_cpu(cwq); | |
2427 | ||
c8e55f36 | 2428 | wake_up_process(cwq->worker->task); |
a0a1a5fd | 2429 | } |
8b03ae3c TH |
2430 | |
2431 | spin_unlock_irq(&gcwq->lock); | |
a0a1a5fd TH |
2432 | } |
2433 | ||
2434 | workqueue_freezing = false; | |
2435 | out_unlock: | |
2436 | spin_unlock(&workqueue_lock); | |
2437 | } | |
2438 | #endif /* CONFIG_FREEZER */ | |
2439 | ||
c12920d1 | 2440 | void __init init_workqueues(void) |
1da177e4 | 2441 | { |
c34056a3 | 2442 | unsigned int cpu; |
c8e55f36 | 2443 | int i; |
c34056a3 | 2444 | |
7a22ad75 TH |
2445 | /* |
2446 | * The pointer part of work->data is either pointing to the | |
2447 | * cwq or contains the cpu number the work ran last on. Make | |
2448 | * sure cpu number won't overflow into kernel pointer area so | |
2449 | * that they can be distinguished. | |
2450 | */ | |
2451 | BUILD_BUG_ON(NR_CPUS << WORK_STRUCT_FLAG_BITS >= PAGE_OFFSET); | |
2452 | ||
db7bccf4 | 2453 | hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); |
8b03ae3c TH |
2454 | |
2455 | /* initialize gcwqs */ | |
2456 | for_each_possible_cpu(cpu) { | |
2457 | struct global_cwq *gcwq = get_gcwq(cpu); | |
2458 | ||
2459 | spin_lock_init(&gcwq->lock); | |
2460 | gcwq->cpu = cpu; | |
2461 | ||
c8e55f36 TH |
2462 | INIT_LIST_HEAD(&gcwq->idle_list); |
2463 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) | |
2464 | INIT_HLIST_HEAD(&gcwq->busy_hash[i]); | |
2465 | ||
8b03ae3c | 2466 | ida_init(&gcwq->worker_ida); |
db7bccf4 TH |
2467 | |
2468 | gcwq->trustee_state = TRUSTEE_DONE; | |
2469 | init_waitqueue_head(&gcwq->trustee_wait); | |
8b03ae3c TH |
2470 | } |
2471 | ||
1da177e4 LT |
2472 | keventd_wq = create_workqueue("events"); |
2473 | BUG_ON(!keventd_wq); | |
2474 | } |