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1 | /* |
2 | * kernel/workqueue.c - generic async execution with shared worker pool |
3 | * |
4 | * Copyright (C) 2002 Ingo Molnar |
5 | * |
6 | * Derived from the taskqueue/keventd code by: |
7 | * David Woodhouse <dwmw2@infradead.org> |
8 | * Andrew Morton |
9 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
10 | * Theodore Ts'o <tytso@mit.edu> |
11 | * |
12 | * Made to use alloc_percpu by Christoph Lameter. |
13 | * |
14 | * Copyright (C) 2010 SUSE Linux Products GmbH |
15 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> |
16 | * |
17 | * This is the generic async execution mechanism. Work items as are |
18 | * executed in process context. The worker pool is shared and |
19 | * automatically managed. There is one worker pool for each CPU and |
20 | * one extra for works which are better served by workers which are |
21 | * not bound to any specific CPU. |
22 | * |
23 | * Please read Documentation/workqueue.txt for details. |
24 | */ |
25 | |
26 | #include <linux/export.h> |
27 | #include <linux/kernel.h> |
28 | #include <linux/sched.h> |
29 | #include <linux/init.h> |
30 | #include <linux/signal.h> |
31 | #include <linux/completion.h> |
32 | #include <linux/workqueue.h> |
33 | #include <linux/slab.h> |
34 | #include <linux/cpu.h> |
35 | #include <linux/notifier.h> |
36 | #include <linux/kthread.h> |
37 | #include <linux/hardirq.h> |
38 | #include <linux/mempolicy.h> |
39 | #include <linux/freezer.h> |
40 | #include <linux/kallsyms.h> |
41 | #include <linux/debug_locks.h> |
42 | #include <linux/lockdep.h> |
43 | #include <linux/idr.h> |
44 | #include <linux/jhash.h> |
45 | #include <linux/hashtable.h> |
46 | #include <linux/rculist.h> |
47 | #include <linux/nodemask.h> |
48 | #include <linux/moduleparam.h> |
49 | #include <linux/uaccess.h> |
50 | |
51 | #include "workqueue_internal.h" |
52 | |
53 | enum { |
54 | /* |
55 | * worker_pool flags |
56 | * |
57 | * A bound pool is either associated or disassociated with its CPU. |
58 | * While associated (!DISASSOCIATED), all workers are bound to the |
59 | * CPU and none has %WORKER_UNBOUND set and concurrency management |
60 | * is in effect. |
61 | * |
62 | * While DISASSOCIATED, the cpu may be offline and all workers have |
63 | * %WORKER_UNBOUND set and concurrency management disabled, and may |
64 | * be executing on any CPU. The pool behaves as an unbound one. |
65 | * |
66 | * Note that DISASSOCIATED should be flipped only while holding |
67 | * manager_mutex to avoid changing binding state while |
68 | * create_worker() is in progress. |
69 | */ |
70 | POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ |
71 | POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
72 | POOL_FREEZING = 1 << 3, /* freeze in progress */ |
73 | |
74 | /* worker flags */ |
75 | WORKER_STARTED = 1 << 0, /* started */ |
76 | WORKER_DIE = 1 << 1, /* die die die */ |
77 | WORKER_IDLE = 1 << 2, /* is idle */ |
78 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
79 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
80 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
81 | WORKER_REBOUND = 1 << 8, /* worker was rebound */ |
82 | |
83 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | |
84 | WORKER_UNBOUND | WORKER_REBOUND, |
85 | |
86 | NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ |
87 | |
88 | UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ |
89 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
90 | |
91 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
92 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
93 | |
94 | MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, |
95 | /* call for help after 10ms |
96 | (min two ticks) */ |
97 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
98 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
99 | |
100 | /* |
101 | * Rescue workers are used only on emergencies and shared by |
102 | * all cpus. Give -20. |
103 | */ |
104 | RESCUER_NICE_LEVEL = -20, |
105 | HIGHPRI_NICE_LEVEL = -20, |
106 | |
107 | WQ_NAME_LEN = 24, |
108 | }; |
109 | |
110 | /* |
111 | * Structure fields follow one of the following exclusion rules. |
112 | * |
113 | * I: Modifiable by initialization/destruction paths and read-only for |
114 | * everyone else. |
115 | * |
116 | * P: Preemption protected. Disabling preemption is enough and should |
117 | * only be modified and accessed from the local cpu. |
118 | * |
119 | * L: pool->lock protected. Access with pool->lock held. |
120 | * |
121 | * X: During normal operation, modification requires pool->lock and should |
122 | * be done only from local cpu. Either disabling preemption on local |
123 | * cpu or grabbing pool->lock is enough for read access. If |
124 | * POOL_DISASSOCIATED is set, it's identical to L. |
125 | * |
126 | * MG: pool->manager_mutex and pool->lock protected. Writes require both |
127 | * locks. Reads can happen under either lock. |
128 | * |
129 | * PL: wq_pool_mutex protected. |
130 | * |
131 | * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads. |
132 | * |
133 | * WQ: wq->mutex protected. |
134 | * |
135 | * WR: wq->mutex protected for writes. Sched-RCU protected for reads. |
136 | * |
137 | * MD: wq_mayday_lock protected. |
138 | */ |
139 | |
140 | /* struct worker is defined in workqueue_internal.h */ |
141 | |
142 | struct worker_pool { |
143 | spinlock_t lock; /* the pool lock */ |
144 | int cpu; /* I: the associated cpu */ |
145 | int node; /* I: the associated node ID */ |
146 | int id; /* I: pool ID */ |
147 | unsigned int flags; /* X: flags */ |
148 | |
149 | struct list_head worklist; /* L: list of pending works */ |
150 | int nr_workers; /* L: total number of workers */ |
151 | |
152 | /* nr_idle includes the ones off idle_list for rebinding */ |
153 | int nr_idle; /* L: currently idle ones */ |
154 | |
155 | struct list_head idle_list; /* X: list of idle workers */ |
156 | struct timer_list idle_timer; /* L: worker idle timeout */ |
157 | struct timer_list mayday_timer; /* L: SOS timer for workers */ |
158 | |
159 | /* a workers is either on busy_hash or idle_list, or the manager */ |
160 | DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); |
161 | /* L: hash of busy workers */ |
162 | |
163 | /* see manage_workers() for details on the two manager mutexes */ |
164 | struct mutex manager_arb; /* manager arbitration */ |
165 | struct mutex manager_mutex; /* manager exclusion */ |
166 | struct idr worker_idr; /* MG: worker IDs and iteration */ |
167 | |
168 | struct workqueue_attrs *attrs; /* I: worker attributes */ |
169 | struct hlist_node hash_node; /* PL: unbound_pool_hash node */ |
170 | int refcnt; /* PL: refcnt for unbound pools */ |
171 | |
172 | /* |
173 | * The current concurrency level. As it's likely to be accessed |
174 | * from other CPUs during try_to_wake_up(), put it in a separate |
175 | * cacheline. |
176 | */ |
177 | atomic_t nr_running ____cacheline_aligned_in_smp; |
178 | |
179 | /* |
180 | * Destruction of pool is sched-RCU protected to allow dereferences |
181 | * from get_work_pool(). |
182 | */ |
183 | struct rcu_head rcu; |
184 | } ____cacheline_aligned_in_smp; |
185 | |
186 | /* |
187 | * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS |
188 | * of work_struct->data are used for flags and the remaining high bits |
189 | * point to the pwq; thus, pwqs need to be aligned at two's power of the |
190 | * number of flag bits. |
191 | */ |
192 | struct pool_workqueue { |
193 | struct worker_pool *pool; /* I: the associated pool */ |
194 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
195 | int work_color; /* L: current color */ |
196 | int flush_color; /* L: flushing color */ |
197 | int refcnt; /* L: reference count */ |
198 | int nr_in_flight[WORK_NR_COLORS]; |
199 | /* L: nr of in_flight works */ |
200 | int nr_active; /* L: nr of active works */ |
201 | int max_active; /* L: max active works */ |
202 | struct list_head delayed_works; /* L: delayed works */ |
203 | struct list_head pwqs_node; /* WR: node on wq->pwqs */ |
204 | struct list_head mayday_node; /* MD: node on wq->maydays */ |
205 | |
206 | /* |
207 | * Release of unbound pwq is punted to system_wq. See put_pwq() |
208 | * and pwq_unbound_release_workfn() for details. pool_workqueue |
209 | * itself is also sched-RCU protected so that the first pwq can be |
210 | * determined without grabbing wq->mutex. |
211 | */ |
212 | struct work_struct unbound_release_work; |
213 | struct rcu_head rcu; |
214 | } __aligned(1 << WORK_STRUCT_FLAG_BITS); |
215 | |
216 | /* |
217 | * Structure used to wait for workqueue flush. |
218 | */ |
219 | struct wq_flusher { |
220 | struct list_head list; /* WQ: list of flushers */ |
221 | int flush_color; /* WQ: flush color waiting for */ |
222 | struct completion done; /* flush completion */ |
223 | }; |
224 | |
225 | struct wq_device; |
226 | |
227 | /* |
228 | * The externally visible workqueue. It relays the issued work items to |
229 | * the appropriate worker_pool through its pool_workqueues. |
230 | */ |
231 | struct workqueue_struct { |
232 | struct list_head pwqs; /* WR: all pwqs of this wq */ |
233 | struct list_head list; /* PL: list of all workqueues */ |
234 | |
235 | struct mutex mutex; /* protects this wq */ |
236 | int work_color; /* WQ: current work color */ |
237 | int flush_color; /* WQ: current flush color */ |
238 | atomic_t nr_pwqs_to_flush; /* flush in progress */ |
239 | struct wq_flusher *first_flusher; /* WQ: first flusher */ |
240 | struct list_head flusher_queue; /* WQ: flush waiters */ |
241 | struct list_head flusher_overflow; /* WQ: flush overflow list */ |
242 | |
243 | struct list_head maydays; /* MD: pwqs requesting rescue */ |
244 | struct worker *rescuer; /* I: rescue worker */ |
245 | |
246 | int nr_drainers; /* WQ: drain in progress */ |
247 | int saved_max_active; /* WQ: saved pwq max_active */ |
248 | |
249 | struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */ |
250 | struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */ |
251 | |
252 | #ifdef CONFIG_SYSFS |
253 | struct wq_device *wq_dev; /* I: for sysfs interface */ |
254 | #endif |
255 | #ifdef CONFIG_LOCKDEP |
256 | struct lockdep_map lockdep_map; |
257 | #endif |
258 | char name[WQ_NAME_LEN]; /* I: workqueue name */ |
259 | |
260 | /* hot fields used during command issue, aligned to cacheline */ |
261 | unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ |
262 | struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ |
263 | struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */ |
264 | }; |
265 | |
266 | static struct kmem_cache *pwq_cache; |
267 | |
268 | static int wq_numa_tbl_len; /* highest possible NUMA node id + 1 */ |
269 | static cpumask_var_t *wq_numa_possible_cpumask; |
270 | /* possible CPUs of each node */ |
271 | |
272 | static bool wq_disable_numa; |
273 | module_param_named(disable_numa, wq_disable_numa, bool, 0444); |
274 | |
275 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ |
276 | #ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT |
277 | static bool wq_power_efficient = true; |
278 | #else |
279 | static bool wq_power_efficient; |
280 | #endif |
281 | |
282 | module_param_named(power_efficient, wq_power_efficient, bool, 0444); |
283 | |
284 | static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ |
285 | |
286 | /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ |
287 | static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; |
288 | |
289 | static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ |
290 | static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ |
291 | |
292 | static LIST_HEAD(workqueues); /* PL: list of all workqueues */ |
293 | static bool workqueue_freezing; /* PL: have wqs started freezing? */ |
294 | |
295 | /* the per-cpu worker pools */ |
296 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], |
297 | cpu_worker_pools); |
298 | |
299 | static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ |
300 | |
301 | /* PL: hash of all unbound pools keyed by pool->attrs */ |
302 | static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); |
303 | |
304 | /* I: attributes used when instantiating standard unbound pools on demand */ |
305 | static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; |
306 | |
307 | struct workqueue_struct *system_wq __read_mostly; |
308 | EXPORT_SYMBOL(system_wq); |
309 | struct workqueue_struct *system_highpri_wq __read_mostly; |
310 | EXPORT_SYMBOL_GPL(system_highpri_wq); |
311 | struct workqueue_struct *system_long_wq __read_mostly; |
312 | EXPORT_SYMBOL_GPL(system_long_wq); |
313 | struct workqueue_struct *system_unbound_wq __read_mostly; |
314 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
315 | struct workqueue_struct *system_freezable_wq __read_mostly; |
316 | EXPORT_SYMBOL_GPL(system_freezable_wq); |
317 | struct workqueue_struct *system_power_efficient_wq __read_mostly; |
318 | EXPORT_SYMBOL_GPL(system_power_efficient_wq); |
319 | struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; |
320 | EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); |
321 | |
322 | static int worker_thread(void *__worker); |
323 | static void copy_workqueue_attrs(struct workqueue_attrs *to, |
324 | const struct workqueue_attrs *from); |
325 | |
326 | #define CREATE_TRACE_POINTS |
327 | #include <trace/events/workqueue.h> |
328 | |
329 | #define assert_rcu_or_pool_mutex() \ |
330 | rcu_lockdep_assert(rcu_read_lock_sched_held() || \ |
331 | lockdep_is_held(&wq_pool_mutex), \ |
332 | "sched RCU or wq_pool_mutex should be held") |
333 | |
334 | #define assert_rcu_or_wq_mutex(wq) \ |
335 | rcu_lockdep_assert(rcu_read_lock_sched_held() || \ |
336 | lockdep_is_held(&wq->mutex), \ |
337 | "sched RCU or wq->mutex should be held") |
338 | |
339 | #ifdef CONFIG_LOCKDEP |
340 | #define assert_manager_or_pool_lock(pool) \ |
341 | WARN_ONCE(debug_locks && \ |
342 | !lockdep_is_held(&(pool)->manager_mutex) && \ |
343 | !lockdep_is_held(&(pool)->lock), \ |
344 | "pool->manager_mutex or ->lock should be held") |
345 | #else |
346 | #define assert_manager_or_pool_lock(pool) do { } while (0) |
347 | #endif |
348 | |
349 | #define for_each_cpu_worker_pool(pool, cpu) \ |
350 | for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ |
351 | (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ |
352 | (pool)++) |
353 | |
354 | /** |
355 | * for_each_pool - iterate through all worker_pools in the system |
356 | * @pool: iteration cursor |
357 | * @pi: integer used for iteration |
358 | * |
359 | * This must be called either with wq_pool_mutex held or sched RCU read |
360 | * locked. If the pool needs to be used beyond the locking in effect, the |
361 | * caller is responsible for guaranteeing that the pool stays online. |
362 | * |
363 | * The if/else clause exists only for the lockdep assertion and can be |
364 | * ignored. |
365 | */ |
366 | #define for_each_pool(pool, pi) \ |
367 | idr_for_each_entry(&worker_pool_idr, pool, pi) \ |
368 | if (({ assert_rcu_or_pool_mutex(); false; })) { } \ |
369 | else |
370 | |
371 | /** |
372 | * for_each_pool_worker - iterate through all workers of a worker_pool |
373 | * @worker: iteration cursor |
374 | * @wi: integer used for iteration |
375 | * @pool: worker_pool to iterate workers of |
376 | * |
377 | * This must be called with either @pool->manager_mutex or ->lock held. |
378 | * |
379 | * The if/else clause exists only for the lockdep assertion and can be |
380 | * ignored. |
381 | */ |
382 | #define for_each_pool_worker(worker, wi, pool) \ |
383 | idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \ |
384 | if (({ assert_manager_or_pool_lock((pool)); false; })) { } \ |
385 | else |
386 | |
387 | /** |
388 | * for_each_pwq - iterate through all pool_workqueues of the specified workqueue |
389 | * @pwq: iteration cursor |
390 | * @wq: the target workqueue |
391 | * |
392 | * This must be called either with wq->mutex held or sched RCU read locked. |
393 | * If the pwq needs to be used beyond the locking in effect, the caller is |
394 | * responsible for guaranteeing that the pwq stays online. |
395 | * |
396 | * The if/else clause exists only for the lockdep assertion and can be |
397 | * ignored. |
398 | */ |
399 | #define for_each_pwq(pwq, wq) \ |
400 | list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \ |
401 | if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ |
402 | else |
403 | |
404 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
405 | |
406 | static struct debug_obj_descr work_debug_descr; |
407 | |
408 | static void *work_debug_hint(void *addr) |
409 | { |
410 | return ((struct work_struct *) addr)->func; |
411 | } |
412 | |
413 | /* |
414 | * fixup_init is called when: |
415 | * - an active object is initialized |
416 | */ |
417 | static int work_fixup_init(void *addr, enum debug_obj_state state) |
418 | { |
419 | struct work_struct *work = addr; |
420 | |
421 | switch (state) { |
422 | case ODEBUG_STATE_ACTIVE: |
423 | cancel_work_sync(work); |
424 | debug_object_init(work, &work_debug_descr); |
425 | return 1; |
426 | default: |
427 | return 0; |
428 | } |
429 | } |
430 | |
431 | /* |
432 | * fixup_activate is called when: |
433 | * - an active object is activated |
434 | * - an unknown object is activated (might be a statically initialized object) |
435 | */ |
436 | static int work_fixup_activate(void *addr, enum debug_obj_state state) |
437 | { |
438 | struct work_struct *work = addr; |
439 | |
440 | switch (state) { |
441 | |
442 | case ODEBUG_STATE_NOTAVAILABLE: |
443 | /* |
444 | * This is not really a fixup. The work struct was |
445 | * statically initialized. We just make sure that it |
446 | * is tracked in the object tracker. |
447 | */ |
448 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
449 | debug_object_init(work, &work_debug_descr); |
450 | debug_object_activate(work, &work_debug_descr); |
451 | return 0; |
452 | } |
453 | WARN_ON_ONCE(1); |
454 | return 0; |
455 | |
456 | case ODEBUG_STATE_ACTIVE: |
457 | WARN_ON(1); |
458 | |
459 | default: |
460 | return 0; |
461 | } |
462 | } |
463 | |
464 | /* |
465 | * fixup_free is called when: |
466 | * - an active object is freed |
467 | */ |
468 | static int work_fixup_free(void *addr, enum debug_obj_state state) |
469 | { |
470 | struct work_struct *work = addr; |
471 | |
472 | switch (state) { |
473 | case ODEBUG_STATE_ACTIVE: |
474 | cancel_work_sync(work); |
475 | debug_object_free(work, &work_debug_descr); |
476 | return 1; |
477 | default: |
478 | return 0; |
479 | } |
480 | } |
481 | |
482 | static struct debug_obj_descr work_debug_descr = { |
483 | .name = "work_struct", |
484 | .debug_hint = work_debug_hint, |
485 | .fixup_init = work_fixup_init, |
486 | .fixup_activate = work_fixup_activate, |
487 | .fixup_free = work_fixup_free, |
488 | }; |
489 | |
490 | static inline void debug_work_activate(struct work_struct *work) |
491 | { |
492 | debug_object_activate(work, &work_debug_descr); |
493 | } |
494 | |
495 | static inline void debug_work_deactivate(struct work_struct *work) |
496 | { |
497 | debug_object_deactivate(work, &work_debug_descr); |
498 | } |
499 | |
500 | void __init_work(struct work_struct *work, int onstack) |
501 | { |
502 | if (onstack) |
503 | debug_object_init_on_stack(work, &work_debug_descr); |
504 | else |
505 | debug_object_init(work, &work_debug_descr); |
506 | } |
507 | EXPORT_SYMBOL_GPL(__init_work); |
508 | |
509 | void destroy_work_on_stack(struct work_struct *work) |
510 | { |
511 | debug_object_free(work, &work_debug_descr); |
512 | } |
513 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
514 | |
515 | #else |
516 | static inline void debug_work_activate(struct work_struct *work) { } |
517 | static inline void debug_work_deactivate(struct work_struct *work) { } |
518 | #endif |
519 | |
520 | /* allocate ID and assign it to @pool */ |
521 | static int worker_pool_assign_id(struct worker_pool *pool) |
522 | { |
523 | int ret; |
524 | |
525 | lockdep_assert_held(&wq_pool_mutex); |
526 | |
527 | ret = idr_alloc(&worker_pool_idr, pool, 0, 0, GFP_KERNEL); |
528 | if (ret >= 0) { |
529 | pool->id = ret; |
530 | return 0; |
531 | } |
532 | return ret; |
533 | } |
534 | |
535 | /** |
536 | * unbound_pwq_by_node - return the unbound pool_workqueue for the given node |
537 | * @wq: the target workqueue |
538 | * @node: the node ID |
539 | * |
540 | * This must be called either with pwq_lock held or sched RCU read locked. |
541 | * If the pwq needs to be used beyond the locking in effect, the caller is |
542 | * responsible for guaranteeing that the pwq stays online. |
543 | */ |
544 | static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, |
545 | int node) |
546 | { |
547 | assert_rcu_or_wq_mutex(wq); |
548 | return rcu_dereference_raw(wq->numa_pwq_tbl[node]); |
549 | } |
550 | |
551 | static unsigned int work_color_to_flags(int color) |
552 | { |
553 | return color << WORK_STRUCT_COLOR_SHIFT; |
554 | } |
555 | |
556 | static int get_work_color(struct work_struct *work) |
557 | { |
558 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & |
559 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
560 | } |
561 | |
562 | static int work_next_color(int color) |
563 | { |
564 | return (color + 1) % WORK_NR_COLORS; |
565 | } |
566 | |
567 | /* |
568 | * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data |
569 | * contain the pointer to the queued pwq. Once execution starts, the flag |
570 | * is cleared and the high bits contain OFFQ flags and pool ID. |
571 | * |
572 | * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() |
573 | * and clear_work_data() can be used to set the pwq, pool or clear |
574 | * work->data. These functions should only be called while the work is |
575 | * owned - ie. while the PENDING bit is set. |
576 | * |
577 | * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq |
578 | * corresponding to a work. Pool is available once the work has been |
579 | * queued anywhere after initialization until it is sync canceled. pwq is |
580 | * available only while the work item is queued. |
581 | * |
582 | * %WORK_OFFQ_CANCELING is used to mark a work item which is being |
583 | * canceled. While being canceled, a work item may have its PENDING set |
584 | * but stay off timer and worklist for arbitrarily long and nobody should |
585 | * try to steal the PENDING bit. |
586 | */ |
587 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
588 | unsigned long flags) |
589 | { |
590 | WARN_ON_ONCE(!work_pending(work)); |
591 | atomic_long_set(&work->data, data | flags | work_static(work)); |
592 | } |
593 | |
594 | static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, |
595 | unsigned long extra_flags) |
596 | { |
597 | set_work_data(work, (unsigned long)pwq, |
598 | WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); |
599 | } |
600 | |
601 | static void set_work_pool_and_keep_pending(struct work_struct *work, |
602 | int pool_id) |
603 | { |
604 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, |
605 | WORK_STRUCT_PENDING); |
606 | } |
607 | |
608 | static void set_work_pool_and_clear_pending(struct work_struct *work, |
609 | int pool_id) |
610 | { |
611 | /* |
612 | * The following wmb is paired with the implied mb in |
613 | * test_and_set_bit(PENDING) and ensures all updates to @work made |
614 | * here are visible to and precede any updates by the next PENDING |
615 | * owner. |
616 | */ |
617 | smp_wmb(); |
618 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); |
619 | } |
620 | |
621 | static void clear_work_data(struct work_struct *work) |
622 | { |
623 | smp_wmb(); /* see set_work_pool_and_clear_pending() */ |
624 | set_work_data(work, WORK_STRUCT_NO_POOL, 0); |
625 | } |
626 | |
627 | static struct pool_workqueue *get_work_pwq(struct work_struct *work) |
628 | { |
629 | unsigned long data = atomic_long_read(&work->data); |
630 | |
631 | if (data & WORK_STRUCT_PWQ) |
632 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
633 | else |
634 | return NULL; |
635 | } |
636 | |
637 | /** |
638 | * get_work_pool - return the worker_pool a given work was associated with |
639 | * @work: the work item of interest |
640 | * |
641 | * Return the worker_pool @work was last associated with. %NULL if none. |
642 | * |
643 | * Pools are created and destroyed under wq_pool_mutex, and allows read |
644 | * access under sched-RCU read lock. As such, this function should be |
645 | * called under wq_pool_mutex or with preemption disabled. |
646 | * |
647 | * All fields of the returned pool are accessible as long as the above |
648 | * mentioned locking is in effect. If the returned pool needs to be used |
649 | * beyond the critical section, the caller is responsible for ensuring the |
650 | * returned pool is and stays online. |
651 | */ |
652 | static struct worker_pool *get_work_pool(struct work_struct *work) |
653 | { |
654 | unsigned long data = atomic_long_read(&work->data); |
655 | int pool_id; |
656 | |
657 | assert_rcu_or_pool_mutex(); |
658 | |
659 | if (data & WORK_STRUCT_PWQ) |
660 | return ((struct pool_workqueue *) |
661 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool; |
662 | |
663 | pool_id = data >> WORK_OFFQ_POOL_SHIFT; |
664 | if (pool_id == WORK_OFFQ_POOL_NONE) |
665 | return NULL; |
666 | |
667 | return idr_find(&worker_pool_idr, pool_id); |
668 | } |
669 | |
670 | /** |
671 | * get_work_pool_id - return the worker pool ID a given work is associated with |
672 | * @work: the work item of interest |
673 | * |
674 | * Return the worker_pool ID @work was last associated with. |
675 | * %WORK_OFFQ_POOL_NONE if none. |
676 | */ |
677 | static int get_work_pool_id(struct work_struct *work) |
678 | { |
679 | unsigned long data = atomic_long_read(&work->data); |
680 | |
681 | if (data & WORK_STRUCT_PWQ) |
682 | return ((struct pool_workqueue *) |
683 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; |
684 | |
685 | return data >> WORK_OFFQ_POOL_SHIFT; |
686 | } |
687 | |
688 | static void mark_work_canceling(struct work_struct *work) |
689 | { |
690 | unsigned long pool_id = get_work_pool_id(work); |
691 | |
692 | pool_id <<= WORK_OFFQ_POOL_SHIFT; |
693 | set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); |
694 | } |
695 | |
696 | static bool work_is_canceling(struct work_struct *work) |
697 | { |
698 | unsigned long data = atomic_long_read(&work->data); |
699 | |
700 | return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); |
701 | } |
702 | |
703 | /* |
704 | * Policy functions. These define the policies on how the global worker |
705 | * pools are managed. Unless noted otherwise, these functions assume that |
706 | * they're being called with pool->lock held. |
707 | */ |
708 | |
709 | static bool __need_more_worker(struct worker_pool *pool) |
710 | { |
711 | return !atomic_read(&pool->nr_running); |
712 | } |
713 | |
714 | /* |
715 | * Need to wake up a worker? Called from anything but currently |
716 | * running workers. |
717 | * |
718 | * Note that, because unbound workers never contribute to nr_running, this |
719 | * function will always return %true for unbound pools as long as the |
720 | * worklist isn't empty. |
721 | */ |
722 | static bool need_more_worker(struct worker_pool *pool) |
723 | { |
724 | return !list_empty(&pool->worklist) && __need_more_worker(pool); |
725 | } |
726 | |
727 | /* Can I start working? Called from busy but !running workers. */ |
728 | static bool may_start_working(struct worker_pool *pool) |
729 | { |
730 | return pool->nr_idle; |
731 | } |
732 | |
733 | /* Do I need to keep working? Called from currently running workers. */ |
734 | static bool keep_working(struct worker_pool *pool) |
735 | { |
736 | return !list_empty(&pool->worklist) && |
737 | atomic_read(&pool->nr_running) <= 1; |
738 | } |
739 | |
740 | /* Do we need a new worker? Called from manager. */ |
741 | static bool need_to_create_worker(struct worker_pool *pool) |
742 | { |
743 | return need_more_worker(pool) && !may_start_working(pool); |
744 | } |
745 | |
746 | /* Do I need to be the manager? */ |
747 | static bool need_to_manage_workers(struct worker_pool *pool) |
748 | { |
749 | return need_to_create_worker(pool) || |
750 | (pool->flags & POOL_MANAGE_WORKERS); |
751 | } |
752 | |
753 | /* Do we have too many workers and should some go away? */ |
754 | static bool too_many_workers(struct worker_pool *pool) |
755 | { |
756 | bool managing = mutex_is_locked(&pool->manager_arb); |
757 | int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ |
758 | int nr_busy = pool->nr_workers - nr_idle; |
759 | |
760 | /* |
761 | * nr_idle and idle_list may disagree if idle rebinding is in |
762 | * progress. Never return %true if idle_list is empty. |
763 | */ |
764 | if (list_empty(&pool->idle_list)) |
765 | return false; |
766 | |
767 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
768 | } |
769 | |
770 | /* |
771 | * Wake up functions. |
772 | */ |
773 | |
774 | /* Return the first worker. Safe with preemption disabled */ |
775 | static struct worker *first_worker(struct worker_pool *pool) |
776 | { |
777 | if (unlikely(list_empty(&pool->idle_list))) |
778 | return NULL; |
779 | |
780 | return list_first_entry(&pool->idle_list, struct worker, entry); |
781 | } |
782 | |
783 | /** |
784 | * wake_up_worker - wake up an idle worker |
785 | * @pool: worker pool to wake worker from |
786 | * |
787 | * Wake up the first idle worker of @pool. |
788 | * |
789 | * CONTEXT: |
790 | * spin_lock_irq(pool->lock). |
791 | */ |
792 | static void wake_up_worker(struct worker_pool *pool) |
793 | { |
794 | struct worker *worker = first_worker(pool); |
795 | |
796 | if (likely(worker)) |
797 | wake_up_process(worker->task); |
798 | } |
799 | |
800 | /** |
801 | * wq_worker_waking_up - a worker is waking up |
802 | * @task: task waking up |
803 | * @cpu: CPU @task is waking up to |
804 | * |
805 | * This function is called during try_to_wake_up() when a worker is |
806 | * being awoken. |
807 | * |
808 | * CONTEXT: |
809 | * spin_lock_irq(rq->lock) |
810 | */ |
811 | void wq_worker_waking_up(struct task_struct *task, int cpu) |
812 | { |
813 | struct worker *worker = kthread_data(task); |
814 | |
815 | if (!(worker->flags & WORKER_NOT_RUNNING)) { |
816 | WARN_ON_ONCE(worker->pool->cpu != cpu); |
817 | atomic_inc(&worker->pool->nr_running); |
818 | } |
819 | } |
820 | |
821 | /** |
822 | * wq_worker_sleeping - a worker is going to sleep |
823 | * @task: task going to sleep |
824 | * @cpu: CPU in question, must be the current CPU number |
825 | * |
826 | * This function is called during schedule() when a busy worker is |
827 | * going to sleep. Worker on the same cpu can be woken up by |
828 | * returning pointer to its task. |
829 | * |
830 | * CONTEXT: |
831 | * spin_lock_irq(rq->lock) |
832 | * |
833 | * RETURNS: |
834 | * Worker task on @cpu to wake up, %NULL if none. |
835 | */ |
836 | struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu) |
837 | { |
838 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; |
839 | struct worker_pool *pool; |
840 | |
841 | /* |
842 | * Rescuers, which may not have all the fields set up like normal |
843 | * workers, also reach here, let's not access anything before |
844 | * checking NOT_RUNNING. |
845 | */ |
846 | if (worker->flags & WORKER_NOT_RUNNING) |
847 | return NULL; |
848 | |
849 | pool = worker->pool; |
850 | |
851 | /* this can only happen on the local cpu */ |
852 | if (WARN_ON_ONCE(cpu != raw_smp_processor_id())) |
853 | return NULL; |
854 | |
855 | /* |
856 | * The counterpart of the following dec_and_test, implied mb, |
857 | * worklist not empty test sequence is in insert_work(). |
858 | * Please read comment there. |
859 | * |
860 | * NOT_RUNNING is clear. This means that we're bound to and |
861 | * running on the local cpu w/ rq lock held and preemption |
862 | * disabled, which in turn means that none else could be |
863 | * manipulating idle_list, so dereferencing idle_list without pool |
864 | * lock is safe. |
865 | */ |
866 | if (atomic_dec_and_test(&pool->nr_running) && |
867 | !list_empty(&pool->worklist)) |
868 | to_wakeup = first_worker(pool); |
869 | return to_wakeup ? to_wakeup->task : NULL; |
870 | } |
871 | |
872 | /** |
873 | * worker_set_flags - set worker flags and adjust nr_running accordingly |
874 | * @worker: self |
875 | * @flags: flags to set |
876 | * @wakeup: wakeup an idle worker if necessary |
877 | * |
878 | * Set @flags in @worker->flags and adjust nr_running accordingly. If |
879 | * nr_running becomes zero and @wakeup is %true, an idle worker is |
880 | * woken up. |
881 | * |
882 | * CONTEXT: |
883 | * spin_lock_irq(pool->lock) |
884 | */ |
885 | static inline void worker_set_flags(struct worker *worker, unsigned int flags, |
886 | bool wakeup) |
887 | { |
888 | struct worker_pool *pool = worker->pool; |
889 | |
890 | WARN_ON_ONCE(worker->task != current); |
891 | |
892 | /* |
893 | * If transitioning into NOT_RUNNING, adjust nr_running and |
894 | * wake up an idle worker as necessary if requested by |
895 | * @wakeup. |
896 | */ |
897 | if ((flags & WORKER_NOT_RUNNING) && |
898 | !(worker->flags & WORKER_NOT_RUNNING)) { |
899 | if (wakeup) { |
900 | if (atomic_dec_and_test(&pool->nr_running) && |
901 | !list_empty(&pool->worklist)) |
902 | wake_up_worker(pool); |
903 | } else |
904 | atomic_dec(&pool->nr_running); |
905 | } |
906 | |
907 | worker->flags |= flags; |
908 | } |
909 | |
910 | /** |
911 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
912 | * @worker: self |
913 | * @flags: flags to clear |
914 | * |
915 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
916 | * |
917 | * CONTEXT: |
918 | * spin_lock_irq(pool->lock) |
919 | */ |
920 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
921 | { |
922 | struct worker_pool *pool = worker->pool; |
923 | unsigned int oflags = worker->flags; |
924 | |
925 | WARN_ON_ONCE(worker->task != current); |
926 | |
927 | worker->flags &= ~flags; |
928 | |
929 | /* |
930 | * If transitioning out of NOT_RUNNING, increment nr_running. Note |
931 | * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask |
932 | * of multiple flags, not a single flag. |
933 | */ |
934 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
935 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
936 | atomic_inc(&pool->nr_running); |
937 | } |
938 | |
939 | /** |
940 | * find_worker_executing_work - find worker which is executing a work |
941 | * @pool: pool of interest |
942 | * @work: work to find worker for |
943 | * |
944 | * Find a worker which is executing @work on @pool by searching |
945 | * @pool->busy_hash which is keyed by the address of @work. For a worker |
946 | * to match, its current execution should match the address of @work and |
947 | * its work function. This is to avoid unwanted dependency between |
948 | * unrelated work executions through a work item being recycled while still |
949 | * being executed. |
950 | * |
951 | * This is a bit tricky. A work item may be freed once its execution |
952 | * starts and nothing prevents the freed area from being recycled for |
953 | * another work item. If the same work item address ends up being reused |
954 | * before the original execution finishes, workqueue will identify the |
955 | * recycled work item as currently executing and make it wait until the |
956 | * current execution finishes, introducing an unwanted dependency. |
957 | * |
958 | * This function checks the work item address and work function to avoid |
959 | * false positives. Note that this isn't complete as one may construct a |
960 | * work function which can introduce dependency onto itself through a |
961 | * recycled work item. Well, if somebody wants to shoot oneself in the |
962 | * foot that badly, there's only so much we can do, and if such deadlock |
963 | * actually occurs, it should be easy to locate the culprit work function. |
964 | * |
965 | * CONTEXT: |
966 | * spin_lock_irq(pool->lock). |
967 | * |
968 | * RETURNS: |
969 | * Pointer to worker which is executing @work if found, NULL |
970 | * otherwise. |
971 | */ |
972 | static struct worker *find_worker_executing_work(struct worker_pool *pool, |
973 | struct work_struct *work) |
974 | { |
975 | struct worker *worker; |
976 | |
977 | hash_for_each_possible(pool->busy_hash, worker, hentry, |
978 | (unsigned long)work) |
979 | if (worker->current_work == work && |
980 | worker->current_func == work->func) |
981 | return worker; |
982 | |
983 | return NULL; |
984 | } |
985 | |
986 | /** |
987 | * move_linked_works - move linked works to a list |
988 | * @work: start of series of works to be scheduled |
989 | * @head: target list to append @work to |
990 | * @nextp: out paramter for nested worklist walking |
991 | * |
992 | * Schedule linked works starting from @work to @head. Work series to |
993 | * be scheduled starts at @work and includes any consecutive work with |
994 | * WORK_STRUCT_LINKED set in its predecessor. |
995 | * |
996 | * If @nextp is not NULL, it's updated to point to the next work of |
997 | * the last scheduled work. This allows move_linked_works() to be |
998 | * nested inside outer list_for_each_entry_safe(). |
999 | * |
1000 | * CONTEXT: |
1001 | * spin_lock_irq(pool->lock). |
1002 | */ |
1003 | static void move_linked_works(struct work_struct *work, struct list_head *head, |
1004 | struct work_struct **nextp) |
1005 | { |
1006 | struct work_struct *n; |
1007 | |
1008 | /* |
1009 | * Linked worklist will always end before the end of the list, |
1010 | * use NULL for list head. |
1011 | */ |
1012 | list_for_each_entry_safe_from(work, n, NULL, entry) { |
1013 | list_move_tail(&work->entry, head); |
1014 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
1015 | break; |
1016 | } |
1017 | |
1018 | /* |
1019 | * If we're already inside safe list traversal and have moved |
1020 | * multiple works to the scheduled queue, the next position |
1021 | * needs to be updated. |
1022 | */ |
1023 | if (nextp) |
1024 | *nextp = n; |
1025 | } |
1026 | |
1027 | /** |
1028 | * get_pwq - get an extra reference on the specified pool_workqueue |
1029 | * @pwq: pool_workqueue to get |
1030 | * |
1031 | * Obtain an extra reference on @pwq. The caller should guarantee that |
1032 | * @pwq has positive refcnt and be holding the matching pool->lock. |
1033 | */ |
1034 | static void get_pwq(struct pool_workqueue *pwq) |
1035 | { |
1036 | lockdep_assert_held(&pwq->pool->lock); |
1037 | WARN_ON_ONCE(pwq->refcnt <= 0); |
1038 | pwq->refcnt++; |
1039 | } |
1040 | |
1041 | /** |
1042 | * put_pwq - put a pool_workqueue reference |
1043 | * @pwq: pool_workqueue to put |
1044 | * |
1045 | * Drop a reference of @pwq. If its refcnt reaches zero, schedule its |
1046 | * destruction. The caller should be holding the matching pool->lock. |
1047 | */ |
1048 | static void put_pwq(struct pool_workqueue *pwq) |
1049 | { |
1050 | lockdep_assert_held(&pwq->pool->lock); |
1051 | if (likely(--pwq->refcnt)) |
1052 | return; |
1053 | if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) |
1054 | return; |
1055 | /* |
1056 | * @pwq can't be released under pool->lock, bounce to |
1057 | * pwq_unbound_release_workfn(). This never recurses on the same |
1058 | * pool->lock as this path is taken only for unbound workqueues and |
1059 | * the release work item is scheduled on a per-cpu workqueue. To |
1060 | * avoid lockdep warning, unbound pool->locks are given lockdep |
1061 | * subclass of 1 in get_unbound_pool(). |
1062 | */ |
1063 | schedule_work(&pwq->unbound_release_work); |
1064 | } |
1065 | |
1066 | /** |
1067 | * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock |
1068 | * @pwq: pool_workqueue to put (can be %NULL) |
1069 | * |
1070 | * put_pwq() with locking. This function also allows %NULL @pwq. |
1071 | */ |
1072 | static void put_pwq_unlocked(struct pool_workqueue *pwq) |
1073 | { |
1074 | if (pwq) { |
1075 | /* |
1076 | * As both pwqs and pools are sched-RCU protected, the |
1077 | * following lock operations are safe. |
1078 | */ |
1079 | spin_lock_irq(&pwq->pool->lock); |
1080 | put_pwq(pwq); |
1081 | spin_unlock_irq(&pwq->pool->lock); |
1082 | } |
1083 | } |
1084 | |
1085 | static void pwq_activate_delayed_work(struct work_struct *work) |
1086 | { |
1087 | struct pool_workqueue *pwq = get_work_pwq(work); |
1088 | |
1089 | trace_workqueue_activate_work(work); |
1090 | move_linked_works(work, &pwq->pool->worklist, NULL); |
1091 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); |
1092 | pwq->nr_active++; |
1093 | } |
1094 | |
1095 | static void pwq_activate_first_delayed(struct pool_workqueue *pwq) |
1096 | { |
1097 | struct work_struct *work = list_first_entry(&pwq->delayed_works, |
1098 | struct work_struct, entry); |
1099 | |
1100 | pwq_activate_delayed_work(work); |
1101 | } |
1102 | |
1103 | /** |
1104 | * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight |
1105 | * @pwq: pwq of interest |
1106 | * @color: color of work which left the queue |
1107 | * |
1108 | * A work either has completed or is removed from pending queue, |
1109 | * decrement nr_in_flight of its pwq and handle workqueue flushing. |
1110 | * |
1111 | * CONTEXT: |
1112 | * spin_lock_irq(pool->lock). |
1113 | */ |
1114 | static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) |
1115 | { |
1116 | /* uncolored work items don't participate in flushing or nr_active */ |
1117 | if (color == WORK_NO_COLOR) |
1118 | goto out_put; |
1119 | |
1120 | pwq->nr_in_flight[color]--; |
1121 | |
1122 | pwq->nr_active--; |
1123 | if (!list_empty(&pwq->delayed_works)) { |
1124 | /* one down, submit a delayed one */ |
1125 | if (pwq->nr_active < pwq->max_active) |
1126 | pwq_activate_first_delayed(pwq); |
1127 | } |
1128 | |
1129 | /* is flush in progress and are we at the flushing tip? */ |
1130 | if (likely(pwq->flush_color != color)) |
1131 | goto out_put; |
1132 | |
1133 | /* are there still in-flight works? */ |
1134 | if (pwq->nr_in_flight[color]) |
1135 | goto out_put; |
1136 | |
1137 | /* this pwq is done, clear flush_color */ |
1138 | pwq->flush_color = -1; |
1139 | |
1140 | /* |
1141 | * If this was the last pwq, wake up the first flusher. It |
1142 | * will handle the rest. |
1143 | */ |
1144 | if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) |
1145 | complete(&pwq->wq->first_flusher->done); |
1146 | out_put: |
1147 | put_pwq(pwq); |
1148 | } |
1149 | |
1150 | /** |
1151 | * try_to_grab_pending - steal work item from worklist and disable irq |
1152 | * @work: work item to steal |
1153 | * @is_dwork: @work is a delayed_work |
1154 | * @flags: place to store irq state |
1155 | * |
1156 | * Try to grab PENDING bit of @work. This function can handle @work in any |
1157 | * stable state - idle, on timer or on worklist. Return values are |
1158 | * |
1159 | * 1 if @work was pending and we successfully stole PENDING |
1160 | * 0 if @work was idle and we claimed PENDING |
1161 | * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry |
1162 | * -ENOENT if someone else is canceling @work, this state may persist |
1163 | * for arbitrarily long |
1164 | * |
1165 | * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting |
1166 | * interrupted while holding PENDING and @work off queue, irq must be |
1167 | * disabled on entry. This, combined with delayed_work->timer being |
1168 | * irqsafe, ensures that we return -EAGAIN for finite short period of time. |
1169 | * |
1170 | * On successful return, >= 0, irq is disabled and the caller is |
1171 | * responsible for releasing it using local_irq_restore(*@flags). |
1172 | * |
1173 | * This function is safe to call from any context including IRQ handler. |
1174 | */ |
1175 | static int try_to_grab_pending(struct work_struct *work, bool is_dwork, |
1176 | unsigned long *flags) |
1177 | { |
1178 | struct worker_pool *pool; |
1179 | struct pool_workqueue *pwq; |
1180 | |
1181 | local_irq_save(*flags); |
1182 | |
1183 | /* try to steal the timer if it exists */ |
1184 | if (is_dwork) { |
1185 | struct delayed_work *dwork = to_delayed_work(work); |
1186 | |
1187 | /* |
1188 | * dwork->timer is irqsafe. If del_timer() fails, it's |
1189 | * guaranteed that the timer is not queued anywhere and not |
1190 | * running on the local CPU. |
1191 | */ |
1192 | if (likely(del_timer(&dwork->timer))) |
1193 | return 1; |
1194 | } |
1195 | |
1196 | /* try to claim PENDING the normal way */ |
1197 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1198 | return 0; |
1199 | |
1200 | /* |
1201 | * The queueing is in progress, or it is already queued. Try to |
1202 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
1203 | */ |
1204 | pool = get_work_pool(work); |
1205 | if (!pool) |
1206 | goto fail; |
1207 | |
1208 | spin_lock(&pool->lock); |
1209 | /* |
1210 | * work->data is guaranteed to point to pwq only while the work |
1211 | * item is queued on pwq->wq, and both updating work->data to point |
1212 | * to pwq on queueing and to pool on dequeueing are done under |
1213 | * pwq->pool->lock. This in turn guarantees that, if work->data |
1214 | * points to pwq which is associated with a locked pool, the work |
1215 | * item is currently queued on that pool. |
1216 | */ |
1217 | pwq = get_work_pwq(work); |
1218 | if (pwq && pwq->pool == pool) { |
1219 | debug_work_deactivate(work); |
1220 | |
1221 | /* |
1222 | * A delayed work item cannot be grabbed directly because |
1223 | * it might have linked NO_COLOR work items which, if left |
1224 | * on the delayed_list, will confuse pwq->nr_active |
1225 | * management later on and cause stall. Make sure the work |
1226 | * item is activated before grabbing. |
1227 | */ |
1228 | if (*work_data_bits(work) & WORK_STRUCT_DELAYED) |
1229 | pwq_activate_delayed_work(work); |
1230 | |
1231 | list_del_init(&work->entry); |
1232 | pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work)); |
1233 | |
1234 | /* work->data points to pwq iff queued, point to pool */ |
1235 | set_work_pool_and_keep_pending(work, pool->id); |
1236 | |
1237 | spin_unlock(&pool->lock); |
1238 | return 1; |
1239 | } |
1240 | spin_unlock(&pool->lock); |
1241 | fail: |
1242 | local_irq_restore(*flags); |
1243 | if (work_is_canceling(work)) |
1244 | return -ENOENT; |
1245 | cpu_relax(); |
1246 | return -EAGAIN; |
1247 | } |
1248 | |
1249 | /** |
1250 | * insert_work - insert a work into a pool |
1251 | * @pwq: pwq @work belongs to |
1252 | * @work: work to insert |
1253 | * @head: insertion point |
1254 | * @extra_flags: extra WORK_STRUCT_* flags to set |
1255 | * |
1256 | * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to |
1257 | * work_struct flags. |
1258 | * |
1259 | * CONTEXT: |
1260 | * spin_lock_irq(pool->lock). |
1261 | */ |
1262 | static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, |
1263 | struct list_head *head, unsigned int extra_flags) |
1264 | { |
1265 | struct worker_pool *pool = pwq->pool; |
1266 | |
1267 | /* we own @work, set data and link */ |
1268 | set_work_pwq(work, pwq, extra_flags); |
1269 | list_add_tail(&work->entry, head); |
1270 | get_pwq(pwq); |
1271 | |
1272 | /* |
1273 | * Ensure either wq_worker_sleeping() sees the above |
1274 | * list_add_tail() or we see zero nr_running to avoid workers lying |
1275 | * around lazily while there are works to be processed. |
1276 | */ |
1277 | smp_mb(); |
1278 | |
1279 | if (__need_more_worker(pool)) |
1280 | wake_up_worker(pool); |
1281 | } |
1282 | |
1283 | /* |
1284 | * Test whether @work is being queued from another work executing on the |
1285 | * same workqueue. |
1286 | */ |
1287 | static bool is_chained_work(struct workqueue_struct *wq) |
1288 | { |
1289 | struct worker *worker; |
1290 | |
1291 | worker = current_wq_worker(); |
1292 | /* |
1293 | * Return %true iff I'm a worker execuing a work item on @wq. If |
1294 | * I'm @worker, it's safe to dereference it without locking. |
1295 | */ |
1296 | return worker && worker->current_pwq->wq == wq; |
1297 | } |
1298 | |
1299 | static void __queue_work(int cpu, struct workqueue_struct *wq, |
1300 | struct work_struct *work) |
1301 | { |
1302 | struct pool_workqueue *pwq; |
1303 | struct worker_pool *last_pool; |
1304 | struct list_head *worklist; |
1305 | unsigned int work_flags; |
1306 | unsigned int req_cpu = cpu; |
1307 | |
1308 | /* |
1309 | * While a work item is PENDING && off queue, a task trying to |
1310 | * steal the PENDING will busy-loop waiting for it to either get |
1311 | * queued or lose PENDING. Grabbing PENDING and queueing should |
1312 | * happen with IRQ disabled. |
1313 | */ |
1314 | WARN_ON_ONCE(!irqs_disabled()); |
1315 | |
1316 | debug_work_activate(work); |
1317 | |
1318 | /* if dying, only works from the same workqueue are allowed */ |
1319 | if (unlikely(wq->flags & __WQ_DRAINING) && |
1320 | WARN_ON_ONCE(!is_chained_work(wq))) |
1321 | return; |
1322 | retry: |
1323 | if (req_cpu == WORK_CPU_UNBOUND) |
1324 | cpu = raw_smp_processor_id(); |
1325 | |
1326 | /* pwq which will be used unless @work is executing elsewhere */ |
1327 | if (!(wq->flags & WQ_UNBOUND)) |
1328 | pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); |
1329 | else |
1330 | pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); |
1331 | |
1332 | /* |
1333 | * If @work was previously on a different pool, it might still be |
1334 | * running there, in which case the work needs to be queued on that |
1335 | * pool to guarantee non-reentrancy. |
1336 | */ |
1337 | last_pool = get_work_pool(work); |
1338 | if (last_pool && last_pool != pwq->pool) { |
1339 | struct worker *worker; |
1340 | |
1341 | spin_lock(&last_pool->lock); |
1342 | |
1343 | worker = find_worker_executing_work(last_pool, work); |
1344 | |
1345 | if (worker && worker->current_pwq->wq == wq) { |
1346 | pwq = worker->current_pwq; |
1347 | } else { |
1348 | /* meh... not running there, queue here */ |
1349 | spin_unlock(&last_pool->lock); |
1350 | spin_lock(&pwq->pool->lock); |
1351 | } |
1352 | } else { |
1353 | spin_lock(&pwq->pool->lock); |
1354 | } |
1355 | |
1356 | /* |
1357 | * pwq is determined and locked. For unbound pools, we could have |
1358 | * raced with pwq release and it could already be dead. If its |
1359 | * refcnt is zero, repeat pwq selection. Note that pwqs never die |
1360 | * without another pwq replacing it in the numa_pwq_tbl or while |
1361 | * work items are executing on it, so the retrying is guaranteed to |
1362 | * make forward-progress. |
1363 | */ |
1364 | if (unlikely(!pwq->refcnt)) { |
1365 | if (wq->flags & WQ_UNBOUND) { |
1366 | spin_unlock(&pwq->pool->lock); |
1367 | cpu_relax(); |
1368 | goto retry; |
1369 | } |
1370 | /* oops */ |
1371 | WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", |
1372 | wq->name, cpu); |
1373 | } |
1374 | |
1375 | /* pwq determined, queue */ |
1376 | trace_workqueue_queue_work(req_cpu, pwq, work); |
1377 | |
1378 | if (WARN_ON(!list_empty(&work->entry))) { |
1379 | spin_unlock(&pwq->pool->lock); |
1380 | return; |
1381 | } |
1382 | |
1383 | pwq->nr_in_flight[pwq->work_color]++; |
1384 | work_flags = work_color_to_flags(pwq->work_color); |
1385 | |
1386 | if (likely(pwq->nr_active < pwq->max_active)) { |
1387 | trace_workqueue_activate_work(work); |
1388 | pwq->nr_active++; |
1389 | worklist = &pwq->pool->worklist; |
1390 | } else { |
1391 | work_flags |= WORK_STRUCT_DELAYED; |
1392 | worklist = &pwq->delayed_works; |
1393 | } |
1394 | |
1395 | insert_work(pwq, work, worklist, work_flags); |
1396 | |
1397 | spin_unlock(&pwq->pool->lock); |
1398 | } |
1399 | |
1400 | /** |
1401 | * queue_work_on - queue work on specific cpu |
1402 | * @cpu: CPU number to execute work on |
1403 | * @wq: workqueue to use |
1404 | * @work: work to queue |
1405 | * |
1406 | * Returns %false if @work was already on a queue, %true otherwise. |
1407 | * |
1408 | * We queue the work to a specific CPU, the caller must ensure it |
1409 | * can't go away. |
1410 | */ |
1411 | bool queue_work_on(int cpu, struct workqueue_struct *wq, |
1412 | struct work_struct *work) |
1413 | { |
1414 | bool ret = false; |
1415 | unsigned long flags; |
1416 | |
1417 | local_irq_save(flags); |
1418 | |
1419 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1420 | __queue_work(cpu, wq, work); |
1421 | ret = true; |
1422 | } |
1423 | |
1424 | local_irq_restore(flags); |
1425 | return ret; |
1426 | } |
1427 | EXPORT_SYMBOL(queue_work_on); |
1428 | |
1429 | void delayed_work_timer_fn(unsigned long __data) |
1430 | { |
1431 | struct delayed_work *dwork = (struct delayed_work *)__data; |
1432 | |
1433 | /* should have been called from irqsafe timer with irq already off */ |
1434 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); |
1435 | } |
1436 | EXPORT_SYMBOL(delayed_work_timer_fn); |
1437 | |
1438 | static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, |
1439 | struct delayed_work *dwork, unsigned long delay) |
1440 | { |
1441 | struct timer_list *timer = &dwork->timer; |
1442 | struct work_struct *work = &dwork->work; |
1443 | |
1444 | WARN_ON_ONCE(timer->function != delayed_work_timer_fn || |
1445 | timer->data != (unsigned long)dwork); |
1446 | WARN_ON_ONCE(timer_pending(timer)); |
1447 | WARN_ON_ONCE(!list_empty(&work->entry)); |
1448 | |
1449 | /* |
1450 | * If @delay is 0, queue @dwork->work immediately. This is for |
1451 | * both optimization and correctness. The earliest @timer can |
1452 | * expire is on the closest next tick and delayed_work users depend |
1453 | * on that there's no such delay when @delay is 0. |
1454 | */ |
1455 | if (!delay) { |
1456 | __queue_work(cpu, wq, &dwork->work); |
1457 | return; |
1458 | } |
1459 | |
1460 | timer_stats_timer_set_start_info(&dwork->timer); |
1461 | |
1462 | dwork->wq = wq; |
1463 | dwork->cpu = cpu; |
1464 | timer->expires = jiffies + delay; |
1465 | |
1466 | if (unlikely(cpu != WORK_CPU_UNBOUND)) |
1467 | add_timer_on(timer, cpu); |
1468 | else |
1469 | add_timer(timer); |
1470 | } |
1471 | |
1472 | /** |
1473 | * queue_delayed_work_on - queue work on specific CPU after delay |
1474 | * @cpu: CPU number to execute work on |
1475 | * @wq: workqueue to use |
1476 | * @dwork: work to queue |
1477 | * @delay: number of jiffies to wait before queueing |
1478 | * |
1479 | * Returns %false if @work was already on a queue, %true otherwise. If |
1480 | * @delay is zero and @dwork is idle, it will be scheduled for immediate |
1481 | * execution. |
1482 | */ |
1483 | bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1484 | struct delayed_work *dwork, unsigned long delay) |
1485 | { |
1486 | struct work_struct *work = &dwork->work; |
1487 | bool ret = false; |
1488 | unsigned long flags; |
1489 | |
1490 | /* read the comment in __queue_work() */ |
1491 | local_irq_save(flags); |
1492 | |
1493 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1494 | __queue_delayed_work(cpu, wq, dwork, delay); |
1495 | ret = true; |
1496 | } |
1497 | |
1498 | local_irq_restore(flags); |
1499 | return ret; |
1500 | } |
1501 | EXPORT_SYMBOL(queue_delayed_work_on); |
1502 | |
1503 | /** |
1504 | * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU |
1505 | * @cpu: CPU number to execute work on |
1506 | * @wq: workqueue to use |
1507 | * @dwork: work to queue |
1508 | * @delay: number of jiffies to wait before queueing |
1509 | * |
1510 | * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, |
1511 | * modify @dwork's timer so that it expires after @delay. If @delay is |
1512 | * zero, @work is guaranteed to be scheduled immediately regardless of its |
1513 | * current state. |
1514 | * |
1515 | * Returns %false if @dwork was idle and queued, %true if @dwork was |
1516 | * pending and its timer was modified. |
1517 | * |
1518 | * This function is safe to call from any context including IRQ handler. |
1519 | * See try_to_grab_pending() for details. |
1520 | */ |
1521 | bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1522 | struct delayed_work *dwork, unsigned long delay) |
1523 | { |
1524 | unsigned long flags; |
1525 | int ret; |
1526 | |
1527 | do { |
1528 | ret = try_to_grab_pending(&dwork->work, true, &flags); |
1529 | } while (unlikely(ret == -EAGAIN)); |
1530 | |
1531 | if (likely(ret >= 0)) { |
1532 | __queue_delayed_work(cpu, wq, dwork, delay); |
1533 | local_irq_restore(flags); |
1534 | } |
1535 | |
1536 | /* -ENOENT from try_to_grab_pending() becomes %true */ |
1537 | return ret; |
1538 | } |
1539 | EXPORT_SYMBOL_GPL(mod_delayed_work_on); |
1540 | |
1541 | /** |
1542 | * worker_enter_idle - enter idle state |
1543 | * @worker: worker which is entering idle state |
1544 | * |
1545 | * @worker is entering idle state. Update stats and idle timer if |
1546 | * necessary. |
1547 | * |
1548 | * LOCKING: |
1549 | * spin_lock_irq(pool->lock). |
1550 | */ |
1551 | static void worker_enter_idle(struct worker *worker) |
1552 | { |
1553 | struct worker_pool *pool = worker->pool; |
1554 | |
1555 | if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || |
1556 | WARN_ON_ONCE(!list_empty(&worker->entry) && |
1557 | (worker->hentry.next || worker->hentry.pprev))) |
1558 | return; |
1559 | |
1560 | /* can't use worker_set_flags(), also called from start_worker() */ |
1561 | worker->flags |= WORKER_IDLE; |
1562 | pool->nr_idle++; |
1563 | worker->last_active = jiffies; |
1564 | |
1565 | /* idle_list is LIFO */ |
1566 | list_add(&worker->entry, &pool->idle_list); |
1567 | |
1568 | if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) |
1569 | mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); |
1570 | |
1571 | /* |
1572 | * Sanity check nr_running. Because wq_unbind_fn() releases |
1573 | * pool->lock between setting %WORKER_UNBOUND and zapping |
1574 | * nr_running, the warning may trigger spuriously. Check iff |
1575 | * unbind is not in progress. |
1576 | */ |
1577 | WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && |
1578 | pool->nr_workers == pool->nr_idle && |
1579 | atomic_read(&pool->nr_running)); |
1580 | } |
1581 | |
1582 | /** |
1583 | * worker_leave_idle - leave idle state |
1584 | * @worker: worker which is leaving idle state |
1585 | * |
1586 | * @worker is leaving idle state. Update stats. |
1587 | * |
1588 | * LOCKING: |
1589 | * spin_lock_irq(pool->lock). |
1590 | */ |
1591 | static void worker_leave_idle(struct worker *worker) |
1592 | { |
1593 | struct worker_pool *pool = worker->pool; |
1594 | |
1595 | if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) |
1596 | return; |
1597 | worker_clr_flags(worker, WORKER_IDLE); |
1598 | pool->nr_idle--; |
1599 | list_del_init(&worker->entry); |
1600 | } |
1601 | |
1602 | /** |
1603 | * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it |
1604 | * @pool: target worker_pool |
1605 | * |
1606 | * Bind %current to the cpu of @pool if it is associated and lock @pool. |
1607 | * |
1608 | * Works which are scheduled while the cpu is online must at least be |
1609 | * scheduled to a worker which is bound to the cpu so that if they are |
1610 | * flushed from cpu callbacks while cpu is going down, they are |
1611 | * guaranteed to execute on the cpu. |
1612 | * |
1613 | * This function is to be used by unbound workers and rescuers to bind |
1614 | * themselves to the target cpu and may race with cpu going down or |
1615 | * coming online. kthread_bind() can't be used because it may put the |
1616 | * worker to already dead cpu and set_cpus_allowed_ptr() can't be used |
1617 | * verbatim as it's best effort and blocking and pool may be |
1618 | * [dis]associated in the meantime. |
1619 | * |
1620 | * This function tries set_cpus_allowed() and locks pool and verifies the |
1621 | * binding against %POOL_DISASSOCIATED which is set during |
1622 | * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker |
1623 | * enters idle state or fetches works without dropping lock, it can |
1624 | * guarantee the scheduling requirement described in the first paragraph. |
1625 | * |
1626 | * CONTEXT: |
1627 | * Might sleep. Called without any lock but returns with pool->lock |
1628 | * held. |
1629 | * |
1630 | * RETURNS: |
1631 | * %true if the associated pool is online (@worker is successfully |
1632 | * bound), %false if offline. |
1633 | */ |
1634 | static bool worker_maybe_bind_and_lock(struct worker_pool *pool) |
1635 | __acquires(&pool->lock) |
1636 | { |
1637 | while (true) { |
1638 | /* |
1639 | * The following call may fail, succeed or succeed |
1640 | * without actually migrating the task to the cpu if |
1641 | * it races with cpu hotunplug operation. Verify |
1642 | * against POOL_DISASSOCIATED. |
1643 | */ |
1644 | if (!(pool->flags & POOL_DISASSOCIATED)) |
1645 | set_cpus_allowed_ptr(current, pool->attrs->cpumask); |
1646 | |
1647 | spin_lock_irq(&pool->lock); |
1648 | if (pool->flags & POOL_DISASSOCIATED) |
1649 | return false; |
1650 | if (task_cpu(current) == pool->cpu && |
1651 | cpumask_equal(¤t->cpus_allowed, pool->attrs->cpumask)) |
1652 | return true; |
1653 | spin_unlock_irq(&pool->lock); |
1654 | |
1655 | /* |
1656 | * We've raced with CPU hot[un]plug. Give it a breather |
1657 | * and retry migration. cond_resched() is required here; |
1658 | * otherwise, we might deadlock against cpu_stop trying to |
1659 | * bring down the CPU on non-preemptive kernel. |
1660 | */ |
1661 | cpu_relax(); |
1662 | cond_resched(); |
1663 | } |
1664 | } |
1665 | |
1666 | static struct worker *alloc_worker(void) |
1667 | { |
1668 | struct worker *worker; |
1669 | |
1670 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
1671 | if (worker) { |
1672 | INIT_LIST_HEAD(&worker->entry); |
1673 | INIT_LIST_HEAD(&worker->scheduled); |
1674 | /* on creation a worker is in !idle && prep state */ |
1675 | worker->flags = WORKER_PREP; |
1676 | } |
1677 | return worker; |
1678 | } |
1679 | |
1680 | /** |
1681 | * create_worker - create a new workqueue worker |
1682 | * @pool: pool the new worker will belong to |
1683 | * |
1684 | * Create a new worker which is bound to @pool. The returned worker |
1685 | * can be started by calling start_worker() or destroyed using |
1686 | * destroy_worker(). |
1687 | * |
1688 | * CONTEXT: |
1689 | * Might sleep. Does GFP_KERNEL allocations. |
1690 | * |
1691 | * RETURNS: |
1692 | * Pointer to the newly created worker. |
1693 | */ |
1694 | static struct worker *create_worker(struct worker_pool *pool) |
1695 | { |
1696 | struct worker *worker = NULL; |
1697 | int id = -1; |
1698 | char id_buf[16]; |
1699 | |
1700 | lockdep_assert_held(&pool->manager_mutex); |
1701 | |
1702 | /* |
1703 | * ID is needed to determine kthread name. Allocate ID first |
1704 | * without installing the pointer. |
1705 | */ |
1706 | idr_preload(GFP_KERNEL); |
1707 | spin_lock_irq(&pool->lock); |
1708 | |
1709 | id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_NOWAIT); |
1710 | |
1711 | spin_unlock_irq(&pool->lock); |
1712 | idr_preload_end(); |
1713 | if (id < 0) |
1714 | goto fail; |
1715 | |
1716 | worker = alloc_worker(); |
1717 | if (!worker) |
1718 | goto fail; |
1719 | |
1720 | worker->pool = pool; |
1721 | worker->id = id; |
1722 | |
1723 | if (pool->cpu >= 0) |
1724 | snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, |
1725 | pool->attrs->nice < 0 ? "H" : ""); |
1726 | else |
1727 | snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); |
1728 | |
1729 | worker->task = kthread_create_on_node(worker_thread, worker, pool->node, |
1730 | "kworker/%s", id_buf); |
1731 | if (IS_ERR(worker->task)) |
1732 | goto fail; |
1733 | |
1734 | /* |
1735 | * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any |
1736 | * online CPUs. It'll be re-applied when any of the CPUs come up. |
1737 | */ |
1738 | set_user_nice(worker->task, pool->attrs->nice); |
1739 | set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); |
1740 | |
1741 | /* prevent userland from meddling with cpumask of workqueue workers */ |
1742 | worker->task->flags |= PF_NO_SETAFFINITY; |
1743 | |
1744 | /* |
1745 | * The caller is responsible for ensuring %POOL_DISASSOCIATED |
1746 | * remains stable across this function. See the comments above the |
1747 | * flag definition for details. |
1748 | */ |
1749 | if (pool->flags & POOL_DISASSOCIATED) |
1750 | worker->flags |= WORKER_UNBOUND; |
1751 | |
1752 | /* successful, commit the pointer to idr */ |
1753 | spin_lock_irq(&pool->lock); |
1754 | idr_replace(&pool->worker_idr, worker, worker->id); |
1755 | spin_unlock_irq(&pool->lock); |
1756 | |
1757 | return worker; |
1758 | |
1759 | fail: |
1760 | if (id >= 0) { |
1761 | spin_lock_irq(&pool->lock); |
1762 | idr_remove(&pool->worker_idr, id); |
1763 | spin_unlock_irq(&pool->lock); |
1764 | } |
1765 | kfree(worker); |
1766 | return NULL; |
1767 | } |
1768 | |
1769 | /** |
1770 | * start_worker - start a newly created worker |
1771 | * @worker: worker to start |
1772 | * |
1773 | * Make the pool aware of @worker and start it. |
1774 | * |
1775 | * CONTEXT: |
1776 | * spin_lock_irq(pool->lock). |
1777 | */ |
1778 | static void start_worker(struct worker *worker) |
1779 | { |
1780 | worker->flags |= WORKER_STARTED; |
1781 | worker->pool->nr_workers++; |
1782 | worker_enter_idle(worker); |
1783 | wake_up_process(worker->task); |
1784 | } |
1785 | |
1786 | /** |
1787 | * create_and_start_worker - create and start a worker for a pool |
1788 | * @pool: the target pool |
1789 | * |
1790 | * Grab the managership of @pool and create and start a new worker for it. |
1791 | */ |
1792 | static int create_and_start_worker(struct worker_pool *pool) |
1793 | { |
1794 | struct worker *worker; |
1795 | |
1796 | mutex_lock(&pool->manager_mutex); |
1797 | |
1798 | worker = create_worker(pool); |
1799 | if (worker) { |
1800 | spin_lock_irq(&pool->lock); |
1801 | start_worker(worker); |
1802 | spin_unlock_irq(&pool->lock); |
1803 | } |
1804 | |
1805 | mutex_unlock(&pool->manager_mutex); |
1806 | |
1807 | return worker ? 0 : -ENOMEM; |
1808 | } |
1809 | |
1810 | /** |
1811 | * destroy_worker - destroy a workqueue worker |
1812 | * @worker: worker to be destroyed |
1813 | * |
1814 | * Destroy @worker and adjust @pool stats accordingly. |
1815 | * |
1816 | * CONTEXT: |
1817 | * spin_lock_irq(pool->lock) which is released and regrabbed. |
1818 | */ |
1819 | static void destroy_worker(struct worker *worker) |
1820 | { |
1821 | struct worker_pool *pool = worker->pool; |
1822 | |
1823 | lockdep_assert_held(&pool->manager_mutex); |
1824 | lockdep_assert_held(&pool->lock); |
1825 | |
1826 | /* sanity check frenzy */ |
1827 | if (WARN_ON(worker->current_work) || |
1828 | WARN_ON(!list_empty(&worker->scheduled))) |
1829 | return; |
1830 | |
1831 | if (worker->flags & WORKER_STARTED) |
1832 | pool->nr_workers--; |
1833 | if (worker->flags & WORKER_IDLE) |
1834 | pool->nr_idle--; |
1835 | |
1836 | list_del_init(&worker->entry); |
1837 | worker->flags |= WORKER_DIE; |
1838 | |
1839 | idr_remove(&pool->worker_idr, worker->id); |
1840 | |
1841 | spin_unlock_irq(&pool->lock); |
1842 | |
1843 | kthread_stop(worker->task); |
1844 | kfree(worker); |
1845 | |
1846 | spin_lock_irq(&pool->lock); |
1847 | } |
1848 | |
1849 | static void idle_worker_timeout(unsigned long __pool) |
1850 | { |
1851 | struct worker_pool *pool = (void *)__pool; |
1852 | |
1853 | spin_lock_irq(&pool->lock); |
1854 | |
1855 | if (too_many_workers(pool)) { |
1856 | struct worker *worker; |
1857 | unsigned long expires; |
1858 | |
1859 | /* idle_list is kept in LIFO order, check the last one */ |
1860 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
1861 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1862 | |
1863 | if (time_before(jiffies, expires)) |
1864 | mod_timer(&pool->idle_timer, expires); |
1865 | else { |
1866 | /* it's been idle for too long, wake up manager */ |
1867 | pool->flags |= POOL_MANAGE_WORKERS; |
1868 | wake_up_worker(pool); |
1869 | } |
1870 | } |
1871 | |
1872 | spin_unlock_irq(&pool->lock); |
1873 | } |
1874 | |
1875 | static void send_mayday(struct work_struct *work) |
1876 | { |
1877 | struct pool_workqueue *pwq = get_work_pwq(work); |
1878 | struct workqueue_struct *wq = pwq->wq; |
1879 | |
1880 | lockdep_assert_held(&wq_mayday_lock); |
1881 | |
1882 | if (!wq->rescuer) |
1883 | return; |
1884 | |
1885 | /* mayday mayday mayday */ |
1886 | if (list_empty(&pwq->mayday_node)) { |
1887 | list_add_tail(&pwq->mayday_node, &wq->maydays); |
1888 | wake_up_process(wq->rescuer->task); |
1889 | } |
1890 | } |
1891 | |
1892 | static void pool_mayday_timeout(unsigned long __pool) |
1893 | { |
1894 | struct worker_pool *pool = (void *)__pool; |
1895 | struct work_struct *work; |
1896 | |
1897 | spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */ |
1898 | spin_lock(&pool->lock); |
1899 | |
1900 | if (need_to_create_worker(pool)) { |
1901 | /* |
1902 | * We've been trying to create a new worker but |
1903 | * haven't been successful. We might be hitting an |
1904 | * allocation deadlock. Send distress signals to |
1905 | * rescuers. |
1906 | */ |
1907 | list_for_each_entry(work, &pool->worklist, entry) |
1908 | send_mayday(work); |
1909 | } |
1910 | |
1911 | spin_unlock(&pool->lock); |
1912 | spin_unlock_irq(&wq_mayday_lock); |
1913 | |
1914 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); |
1915 | } |
1916 | |
1917 | /** |
1918 | * maybe_create_worker - create a new worker if necessary |
1919 | * @pool: pool to create a new worker for |
1920 | * |
1921 | * Create a new worker for @pool if necessary. @pool is guaranteed to |
1922 | * have at least one idle worker on return from this function. If |
1923 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
1924 | * sent to all rescuers with works scheduled on @pool to resolve |
1925 | * possible allocation deadlock. |
1926 | * |
1927 | * On return, need_to_create_worker() is guaranteed to be %false and |
1928 | * may_start_working() %true. |
1929 | * |
1930 | * LOCKING: |
1931 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
1932 | * multiple times. Does GFP_KERNEL allocations. Called only from |
1933 | * manager. |
1934 | * |
1935 | * RETURNS: |
1936 | * %false if no action was taken and pool->lock stayed locked, %true |
1937 | * otherwise. |
1938 | */ |
1939 | static bool maybe_create_worker(struct worker_pool *pool) |
1940 | __releases(&pool->lock) |
1941 | __acquires(&pool->lock) |
1942 | { |
1943 | if (!need_to_create_worker(pool)) |
1944 | return false; |
1945 | restart: |
1946 | spin_unlock_irq(&pool->lock); |
1947 | |
1948 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
1949 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
1950 | |
1951 | while (true) { |
1952 | struct worker *worker; |
1953 | |
1954 | worker = create_worker(pool); |
1955 | if (worker) { |
1956 | del_timer_sync(&pool->mayday_timer); |
1957 | spin_lock_irq(&pool->lock); |
1958 | start_worker(worker); |
1959 | if (WARN_ON_ONCE(need_to_create_worker(pool))) |
1960 | goto restart; |
1961 | return true; |
1962 | } |
1963 | |
1964 | if (!need_to_create_worker(pool)) |
1965 | break; |
1966 | |
1967 | __set_current_state(TASK_INTERRUPTIBLE); |
1968 | schedule_timeout(CREATE_COOLDOWN); |
1969 | |
1970 | if (!need_to_create_worker(pool)) |
1971 | break; |
1972 | } |
1973 | |
1974 | del_timer_sync(&pool->mayday_timer); |
1975 | spin_lock_irq(&pool->lock); |
1976 | if (need_to_create_worker(pool)) |
1977 | goto restart; |
1978 | return true; |
1979 | } |
1980 | |
1981 | /** |
1982 | * maybe_destroy_worker - destroy workers which have been idle for a while |
1983 | * @pool: pool to destroy workers for |
1984 | * |
1985 | * Destroy @pool workers which have been idle for longer than |
1986 | * IDLE_WORKER_TIMEOUT. |
1987 | * |
1988 | * LOCKING: |
1989 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
1990 | * multiple times. Called only from manager. |
1991 | * |
1992 | * RETURNS: |
1993 | * %false if no action was taken and pool->lock stayed locked, %true |
1994 | * otherwise. |
1995 | */ |
1996 | static bool maybe_destroy_workers(struct worker_pool *pool) |
1997 | { |
1998 | bool ret = false; |
1999 | |
2000 | while (too_many_workers(pool)) { |
2001 | struct worker *worker; |
2002 | unsigned long expires; |
2003 | |
2004 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
2005 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
2006 | |
2007 | if (time_before(jiffies, expires)) { |
2008 | mod_timer(&pool->idle_timer, expires); |
2009 | break; |
2010 | } |
2011 | |
2012 | destroy_worker(worker); |
2013 | ret = true; |
2014 | } |
2015 | |
2016 | return ret; |
2017 | } |
2018 | |
2019 | /** |
2020 | * manage_workers - manage worker pool |
2021 | * @worker: self |
2022 | * |
2023 | * Assume the manager role and manage the worker pool @worker belongs |
2024 | * to. At any given time, there can be only zero or one manager per |
2025 | * pool. The exclusion is handled automatically by this function. |
2026 | * |
2027 | * The caller can safely start processing works on false return. On |
2028 | * true return, it's guaranteed that need_to_create_worker() is false |
2029 | * and may_start_working() is true. |
2030 | * |
2031 | * CONTEXT: |
2032 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
2033 | * multiple times. Does GFP_KERNEL allocations. |
2034 | * |
2035 | * RETURNS: |
2036 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
2037 | * multiple times. Does GFP_KERNEL allocations. |
2038 | */ |
2039 | static bool manage_workers(struct worker *worker) |
2040 | { |
2041 | struct worker_pool *pool = worker->pool; |
2042 | bool ret = false; |
2043 | |
2044 | /* |
2045 | * Managership is governed by two mutexes - manager_arb and |
2046 | * manager_mutex. manager_arb handles arbitration of manager role. |
2047 | * Anyone who successfully grabs manager_arb wins the arbitration |
2048 | * and becomes the manager. mutex_trylock() on pool->manager_arb |
2049 | * failure while holding pool->lock reliably indicates that someone |
2050 | * else is managing the pool and the worker which failed trylock |
2051 | * can proceed to executing work items. This means that anyone |
2052 | * grabbing manager_arb is responsible for actually performing |
2053 | * manager duties. If manager_arb is grabbed and released without |
2054 | * actual management, the pool may stall indefinitely. |
2055 | * |
2056 | * manager_mutex is used for exclusion of actual management |
2057 | * operations. The holder of manager_mutex can be sure that none |
2058 | * of management operations, including creation and destruction of |
2059 | * workers, won't take place until the mutex is released. Because |
2060 | * manager_mutex doesn't interfere with manager role arbitration, |
2061 | * it is guaranteed that the pool's management, while may be |
2062 | * delayed, won't be disturbed by someone else grabbing |
2063 | * manager_mutex. |
2064 | */ |
2065 | if (!mutex_trylock(&pool->manager_arb)) |
2066 | return ret; |
2067 | |
2068 | /* |
2069 | * With manager arbitration won, manager_mutex would be free in |
2070 | * most cases. trylock first without dropping @pool->lock. |
2071 | */ |
2072 | if (unlikely(!mutex_trylock(&pool->manager_mutex))) { |
2073 | spin_unlock_irq(&pool->lock); |
2074 | mutex_lock(&pool->manager_mutex); |
2075 | spin_lock_irq(&pool->lock); |
2076 | ret = true; |
2077 | } |
2078 | |
2079 | pool->flags &= ~POOL_MANAGE_WORKERS; |
2080 | |
2081 | /* |
2082 | * Destroy and then create so that may_start_working() is true |
2083 | * on return. |
2084 | */ |
2085 | ret |= maybe_destroy_workers(pool); |
2086 | ret |= maybe_create_worker(pool); |
2087 | |
2088 | mutex_unlock(&pool->manager_mutex); |
2089 | mutex_unlock(&pool->manager_arb); |
2090 | return ret; |
2091 | } |
2092 | |
2093 | /** |
2094 | * process_one_work - process single work |
2095 | * @worker: self |
2096 | * @work: work to process |
2097 | * |
2098 | * Process @work. This function contains all the logics necessary to |
2099 | * process a single work including synchronization against and |
2100 | * interaction with other workers on the same cpu, queueing and |
2101 | * flushing. As long as context requirement is met, any worker can |
2102 | * call this function to process a work. |
2103 | * |
2104 | * CONTEXT: |
2105 | * spin_lock_irq(pool->lock) which is released and regrabbed. |
2106 | */ |
2107 | static void process_one_work(struct worker *worker, struct work_struct *work) |
2108 | __releases(&pool->lock) |
2109 | __acquires(&pool->lock) |
2110 | { |
2111 | struct pool_workqueue *pwq = get_work_pwq(work); |
2112 | struct worker_pool *pool = worker->pool; |
2113 | bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; |
2114 | int work_color; |
2115 | struct worker *collision; |
2116 | #ifdef CONFIG_LOCKDEP |
2117 | /* |
2118 | * It is permissible to free the struct work_struct from |
2119 | * inside the function that is called from it, this we need to |
2120 | * take into account for lockdep too. To avoid bogus "held |
2121 | * lock freed" warnings as well as problems when looking into |
2122 | * work->lockdep_map, make a copy and use that here. |
2123 | */ |
2124 | struct lockdep_map lockdep_map; |
2125 | |
2126 | lockdep_copy_map(&lockdep_map, &work->lockdep_map); |
2127 | #endif |
2128 | /* |
2129 | * Ensure we're on the correct CPU. DISASSOCIATED test is |
2130 | * necessary to avoid spurious warnings from rescuers servicing the |
2131 | * unbound or a disassociated pool. |
2132 | */ |
2133 | WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && |
2134 | !(pool->flags & POOL_DISASSOCIATED) && |
2135 | raw_smp_processor_id() != pool->cpu); |
2136 | |
2137 | /* |
2138 | * A single work shouldn't be executed concurrently by |
2139 | * multiple workers on a single cpu. Check whether anyone is |
2140 | * already processing the work. If so, defer the work to the |
2141 | * currently executing one. |
2142 | */ |
2143 | collision = find_worker_executing_work(pool, work); |
2144 | if (unlikely(collision)) { |
2145 | move_linked_works(work, &collision->scheduled, NULL); |
2146 | return; |
2147 | } |
2148 | |
2149 | /* claim and dequeue */ |
2150 | debug_work_deactivate(work); |
2151 | hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); |
2152 | worker->current_work = work; |
2153 | worker->current_func = work->func; |
2154 | worker->current_pwq = pwq; |
2155 | work_color = get_work_color(work); |
2156 | |
2157 | list_del_init(&work->entry); |
2158 | |
2159 | /* |
2160 | * CPU intensive works don't participate in concurrency |
2161 | * management. They're the scheduler's responsibility. |
2162 | */ |
2163 | if (unlikely(cpu_intensive)) |
2164 | worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); |
2165 | |
2166 | /* |
2167 | * Unbound pool isn't concurrency managed and work items should be |
2168 | * executed ASAP. Wake up another worker if necessary. |
2169 | */ |
2170 | if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) |
2171 | wake_up_worker(pool); |
2172 | |
2173 | /* |
2174 | * Record the last pool and clear PENDING which should be the last |
2175 | * update to @work. Also, do this inside @pool->lock so that |
2176 | * PENDING and queued state changes happen together while IRQ is |
2177 | * disabled. |
2178 | */ |
2179 | set_work_pool_and_clear_pending(work, pool->id); |
2180 | |
2181 | spin_unlock_irq(&pool->lock); |
2182 | |
2183 | lock_map_acquire_read(&pwq->wq->lockdep_map); |
2184 | lock_map_acquire(&lockdep_map); |
2185 | trace_workqueue_execute_start(work); |
2186 | worker->current_func(work); |
2187 | /* |
2188 | * While we must be careful to not use "work" after this, the trace |
2189 | * point will only record its address. |
2190 | */ |
2191 | trace_workqueue_execute_end(work); |
2192 | lock_map_release(&lockdep_map); |
2193 | lock_map_release(&pwq->wq->lockdep_map); |
2194 | |
2195 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
2196 | pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" |
2197 | " last function: %pf\n", |
2198 | current->comm, preempt_count(), task_pid_nr(current), |
2199 | worker->current_func); |
2200 | debug_show_held_locks(current); |
2201 | dump_stack(); |
2202 | } |
2203 | |
2204 | /* |
2205 | * The following prevents a kworker from hogging CPU on !PREEMPT |
2206 | * kernels, where a requeueing work item waiting for something to |
2207 | * happen could deadlock with stop_machine as such work item could |
2208 | * indefinitely requeue itself while all other CPUs are trapped in |
2209 | * stop_machine. |
2210 | */ |
2211 | cond_resched(); |
2212 | |
2213 | spin_lock_irq(&pool->lock); |
2214 | |
2215 | /* clear cpu intensive status */ |
2216 | if (unlikely(cpu_intensive)) |
2217 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); |
2218 | |
2219 | /* we're done with it, release */ |
2220 | hash_del(&worker->hentry); |
2221 | worker->current_work = NULL; |
2222 | worker->current_func = NULL; |
2223 | worker->current_pwq = NULL; |
2224 | worker->desc_valid = false; |
2225 | pwq_dec_nr_in_flight(pwq, work_color); |
2226 | } |
2227 | |
2228 | /** |
2229 | * process_scheduled_works - process scheduled works |
2230 | * @worker: self |
2231 | * |
2232 | * Process all scheduled works. Please note that the scheduled list |
2233 | * may change while processing a work, so this function repeatedly |
2234 | * fetches a work from the top and executes it. |
2235 | * |
2236 | * CONTEXT: |
2237 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
2238 | * multiple times. |
2239 | */ |
2240 | static void process_scheduled_works(struct worker *worker) |
2241 | { |
2242 | while (!list_empty(&worker->scheduled)) { |
2243 | struct work_struct *work = list_first_entry(&worker->scheduled, |
2244 | struct work_struct, entry); |
2245 | process_one_work(worker, work); |
2246 | } |
2247 | } |
2248 | |
2249 | /** |
2250 | * worker_thread - the worker thread function |
2251 | * @__worker: self |
2252 | * |
2253 | * The worker thread function. All workers belong to a worker_pool - |
2254 | * either a per-cpu one or dynamic unbound one. These workers process all |
2255 | * work items regardless of their specific target workqueue. The only |
2256 | * exception is work items which belong to workqueues with a rescuer which |
2257 | * will be explained in rescuer_thread(). |
2258 | */ |
2259 | static int worker_thread(void *__worker) |
2260 | { |
2261 | struct worker *worker = __worker; |
2262 | struct worker_pool *pool = worker->pool; |
2263 | |
2264 | /* tell the scheduler that this is a workqueue worker */ |
2265 | worker->task->flags |= PF_WQ_WORKER; |
2266 | woke_up: |
2267 | spin_lock_irq(&pool->lock); |
2268 | |
2269 | /* am I supposed to die? */ |
2270 | if (unlikely(worker->flags & WORKER_DIE)) { |
2271 | spin_unlock_irq(&pool->lock); |
2272 | WARN_ON_ONCE(!list_empty(&worker->entry)); |
2273 | worker->task->flags &= ~PF_WQ_WORKER; |
2274 | return 0; |
2275 | } |
2276 | |
2277 | worker_leave_idle(worker); |
2278 | recheck: |
2279 | /* no more worker necessary? */ |
2280 | if (!need_more_worker(pool)) |
2281 | goto sleep; |
2282 | |
2283 | /* do we need to manage? */ |
2284 | if (unlikely(!may_start_working(pool)) && manage_workers(worker)) |
2285 | goto recheck; |
2286 | |
2287 | /* |
2288 | * ->scheduled list can only be filled while a worker is |
2289 | * preparing to process a work or actually processing it. |
2290 | * Make sure nobody diddled with it while I was sleeping. |
2291 | */ |
2292 | WARN_ON_ONCE(!list_empty(&worker->scheduled)); |
2293 | |
2294 | /* |
2295 | * Finish PREP stage. We're guaranteed to have at least one idle |
2296 | * worker or that someone else has already assumed the manager |
2297 | * role. This is where @worker starts participating in concurrency |
2298 | * management if applicable and concurrency management is restored |
2299 | * after being rebound. See rebind_workers() for details. |
2300 | */ |
2301 | worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); |
2302 | |
2303 | do { |
2304 | struct work_struct *work = |
2305 | list_first_entry(&pool->worklist, |
2306 | struct work_struct, entry); |
2307 | |
2308 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
2309 | /* optimization path, not strictly necessary */ |
2310 | process_one_work(worker, work); |
2311 | if (unlikely(!list_empty(&worker->scheduled))) |
2312 | process_scheduled_works(worker); |
2313 | } else { |
2314 | move_linked_works(work, &worker->scheduled, NULL); |
2315 | process_scheduled_works(worker); |
2316 | } |
2317 | } while (keep_working(pool)); |
2318 | |
2319 | worker_set_flags(worker, WORKER_PREP, false); |
2320 | sleep: |
2321 | if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) |
2322 | goto recheck; |
2323 | |
2324 | /* |
2325 | * pool->lock is held and there's no work to process and no need to |
2326 | * manage, sleep. Workers are woken up only while holding |
2327 | * pool->lock or from local cpu, so setting the current state |
2328 | * before releasing pool->lock is enough to prevent losing any |
2329 | * event. |
2330 | */ |
2331 | worker_enter_idle(worker); |
2332 | __set_current_state(TASK_INTERRUPTIBLE); |
2333 | spin_unlock_irq(&pool->lock); |
2334 | schedule(); |
2335 | goto woke_up; |
2336 | } |
2337 | |
2338 | /** |
2339 | * rescuer_thread - the rescuer thread function |
2340 | * @__rescuer: self |
2341 | * |
2342 | * Workqueue rescuer thread function. There's one rescuer for each |
2343 | * workqueue which has WQ_MEM_RECLAIM set. |
2344 | * |
2345 | * Regular work processing on a pool may block trying to create a new |
2346 | * worker which uses GFP_KERNEL allocation which has slight chance of |
2347 | * developing into deadlock if some works currently on the same queue |
2348 | * need to be processed to satisfy the GFP_KERNEL allocation. This is |
2349 | * the problem rescuer solves. |
2350 | * |
2351 | * When such condition is possible, the pool summons rescuers of all |
2352 | * workqueues which have works queued on the pool and let them process |
2353 | * those works so that forward progress can be guaranteed. |
2354 | * |
2355 | * This should happen rarely. |
2356 | */ |
2357 | static int rescuer_thread(void *__rescuer) |
2358 | { |
2359 | struct worker *rescuer = __rescuer; |
2360 | struct workqueue_struct *wq = rescuer->rescue_wq; |
2361 | struct list_head *scheduled = &rescuer->scheduled; |
2362 | |
2363 | set_user_nice(current, RESCUER_NICE_LEVEL); |
2364 | |
2365 | /* |
2366 | * Mark rescuer as worker too. As WORKER_PREP is never cleared, it |
2367 | * doesn't participate in concurrency management. |
2368 | */ |
2369 | rescuer->task->flags |= PF_WQ_WORKER; |
2370 | repeat: |
2371 | set_current_state(TASK_INTERRUPTIBLE); |
2372 | |
2373 | if (kthread_should_stop()) { |
2374 | __set_current_state(TASK_RUNNING); |
2375 | rescuer->task->flags &= ~PF_WQ_WORKER; |
2376 | return 0; |
2377 | } |
2378 | |
2379 | /* see whether any pwq is asking for help */ |
2380 | spin_lock_irq(&wq_mayday_lock); |
2381 | |
2382 | while (!list_empty(&wq->maydays)) { |
2383 | struct pool_workqueue *pwq = list_first_entry(&wq->maydays, |
2384 | struct pool_workqueue, mayday_node); |
2385 | struct worker_pool *pool = pwq->pool; |
2386 | struct work_struct *work, *n; |
2387 | |
2388 | __set_current_state(TASK_RUNNING); |
2389 | list_del_init(&pwq->mayday_node); |
2390 | |
2391 | spin_unlock_irq(&wq_mayday_lock); |
2392 | |
2393 | /* migrate to the target cpu if possible */ |
2394 | worker_maybe_bind_and_lock(pool); |
2395 | rescuer->pool = pool; |
2396 | |
2397 | /* |
2398 | * Slurp in all works issued via this workqueue and |
2399 | * process'em. |
2400 | */ |
2401 | WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); |
2402 | list_for_each_entry_safe(work, n, &pool->worklist, entry) |
2403 | if (get_work_pwq(work) == pwq) |
2404 | move_linked_works(work, scheduled, &n); |
2405 | |
2406 | process_scheduled_works(rescuer); |
2407 | |
2408 | /* |
2409 | * Leave this pool. If keep_working() is %true, notify a |
2410 | * regular worker; otherwise, we end up with 0 concurrency |
2411 | * and stalling the execution. |
2412 | */ |
2413 | if (keep_working(pool)) |
2414 | wake_up_worker(pool); |
2415 | |
2416 | rescuer->pool = NULL; |
2417 | spin_unlock(&pool->lock); |
2418 | spin_lock(&wq_mayday_lock); |
2419 | } |
2420 | |
2421 | spin_unlock_irq(&wq_mayday_lock); |
2422 | |
2423 | /* rescuers should never participate in concurrency management */ |
2424 | WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); |
2425 | schedule(); |
2426 | goto repeat; |
2427 | } |
2428 | |
2429 | struct wq_barrier { |
2430 | struct work_struct work; |
2431 | struct completion done; |
2432 | }; |
2433 | |
2434 | static void wq_barrier_func(struct work_struct *work) |
2435 | { |
2436 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
2437 | complete(&barr->done); |
2438 | } |
2439 | |
2440 | /** |
2441 | * insert_wq_barrier - insert a barrier work |
2442 | * @pwq: pwq to insert barrier into |
2443 | * @barr: wq_barrier to insert |
2444 | * @target: target work to attach @barr to |
2445 | * @worker: worker currently executing @target, NULL if @target is not executing |
2446 | * |
2447 | * @barr is linked to @target such that @barr is completed only after |
2448 | * @target finishes execution. Please note that the ordering |
2449 | * guarantee is observed only with respect to @target and on the local |
2450 | * cpu. |
2451 | * |
2452 | * Currently, a queued barrier can't be canceled. This is because |
2453 | * try_to_grab_pending() can't determine whether the work to be |
2454 | * grabbed is at the head of the queue and thus can't clear LINKED |
2455 | * flag of the previous work while there must be a valid next work |
2456 | * after a work with LINKED flag set. |
2457 | * |
2458 | * Note that when @worker is non-NULL, @target may be modified |
2459 | * underneath us, so we can't reliably determine pwq from @target. |
2460 | * |
2461 | * CONTEXT: |
2462 | * spin_lock_irq(pool->lock). |
2463 | */ |
2464 | static void insert_wq_barrier(struct pool_workqueue *pwq, |
2465 | struct wq_barrier *barr, |
2466 | struct work_struct *target, struct worker *worker) |
2467 | { |
2468 | struct list_head *head; |
2469 | unsigned int linked = 0; |
2470 | |
2471 | /* |
2472 | * debugobject calls are safe here even with pool->lock locked |
2473 | * as we know for sure that this will not trigger any of the |
2474 | * checks and call back into the fixup functions where we |
2475 | * might deadlock. |
2476 | */ |
2477 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
2478 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
2479 | init_completion(&barr->done); |
2480 | |
2481 | /* |
2482 | * If @target is currently being executed, schedule the |
2483 | * barrier to the worker; otherwise, put it after @target. |
2484 | */ |
2485 | if (worker) |
2486 | head = worker->scheduled.next; |
2487 | else { |
2488 | unsigned long *bits = work_data_bits(target); |
2489 | |
2490 | head = target->entry.next; |
2491 | /* there can already be other linked works, inherit and set */ |
2492 | linked = *bits & WORK_STRUCT_LINKED; |
2493 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
2494 | } |
2495 | |
2496 | debug_work_activate(&barr->work); |
2497 | insert_work(pwq, &barr->work, head, |
2498 | work_color_to_flags(WORK_NO_COLOR) | linked); |
2499 | } |
2500 | |
2501 | /** |
2502 | * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing |
2503 | * @wq: workqueue being flushed |
2504 | * @flush_color: new flush color, < 0 for no-op |
2505 | * @work_color: new work color, < 0 for no-op |
2506 | * |
2507 | * Prepare pwqs for workqueue flushing. |
2508 | * |
2509 | * If @flush_color is non-negative, flush_color on all pwqs should be |
2510 | * -1. If no pwq has in-flight commands at the specified color, all |
2511 | * pwq->flush_color's stay at -1 and %false is returned. If any pwq |
2512 | * has in flight commands, its pwq->flush_color is set to |
2513 | * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq |
2514 | * wakeup logic is armed and %true is returned. |
2515 | * |
2516 | * The caller should have initialized @wq->first_flusher prior to |
2517 | * calling this function with non-negative @flush_color. If |
2518 | * @flush_color is negative, no flush color update is done and %false |
2519 | * is returned. |
2520 | * |
2521 | * If @work_color is non-negative, all pwqs should have the same |
2522 | * work_color which is previous to @work_color and all will be |
2523 | * advanced to @work_color. |
2524 | * |
2525 | * CONTEXT: |
2526 | * mutex_lock(wq->mutex). |
2527 | * |
2528 | * RETURNS: |
2529 | * %true if @flush_color >= 0 and there's something to flush. %false |
2530 | * otherwise. |
2531 | */ |
2532 | static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, |
2533 | int flush_color, int work_color) |
2534 | { |
2535 | bool wait = false; |
2536 | struct pool_workqueue *pwq; |
2537 | |
2538 | if (flush_color >= 0) { |
2539 | WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); |
2540 | atomic_set(&wq->nr_pwqs_to_flush, 1); |
2541 | } |
2542 | |
2543 | for_each_pwq(pwq, wq) { |
2544 | struct worker_pool *pool = pwq->pool; |
2545 | |
2546 | spin_lock_irq(&pool->lock); |
2547 | |
2548 | if (flush_color >= 0) { |
2549 | WARN_ON_ONCE(pwq->flush_color != -1); |
2550 | |
2551 | if (pwq->nr_in_flight[flush_color]) { |
2552 | pwq->flush_color = flush_color; |
2553 | atomic_inc(&wq->nr_pwqs_to_flush); |
2554 | wait = true; |
2555 | } |
2556 | } |
2557 | |
2558 | if (work_color >= 0) { |
2559 | WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); |
2560 | pwq->work_color = work_color; |
2561 | } |
2562 | |
2563 | spin_unlock_irq(&pool->lock); |
2564 | } |
2565 | |
2566 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) |
2567 | complete(&wq->first_flusher->done); |
2568 | |
2569 | return wait; |
2570 | } |
2571 | |
2572 | /** |
2573 | * flush_workqueue - ensure that any scheduled work has run to completion. |
2574 | * @wq: workqueue to flush |
2575 | * |
2576 | * This function sleeps until all work items which were queued on entry |
2577 | * have finished execution, but it is not livelocked by new incoming ones. |
2578 | */ |
2579 | void flush_workqueue(struct workqueue_struct *wq) |
2580 | { |
2581 | struct wq_flusher this_flusher = { |
2582 | .list = LIST_HEAD_INIT(this_flusher.list), |
2583 | .flush_color = -1, |
2584 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), |
2585 | }; |
2586 | int next_color; |
2587 | |
2588 | lock_map_acquire(&wq->lockdep_map); |
2589 | lock_map_release(&wq->lockdep_map); |
2590 | |
2591 | mutex_lock(&wq->mutex); |
2592 | |
2593 | /* |
2594 | * Start-to-wait phase |
2595 | */ |
2596 | next_color = work_next_color(wq->work_color); |
2597 | |
2598 | if (next_color != wq->flush_color) { |
2599 | /* |
2600 | * Color space is not full. The current work_color |
2601 | * becomes our flush_color and work_color is advanced |
2602 | * by one. |
2603 | */ |
2604 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); |
2605 | this_flusher.flush_color = wq->work_color; |
2606 | wq->work_color = next_color; |
2607 | |
2608 | if (!wq->first_flusher) { |
2609 | /* no flush in progress, become the first flusher */ |
2610 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
2611 | |
2612 | wq->first_flusher = &this_flusher; |
2613 | |
2614 | if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, |
2615 | wq->work_color)) { |
2616 | /* nothing to flush, done */ |
2617 | wq->flush_color = next_color; |
2618 | wq->first_flusher = NULL; |
2619 | goto out_unlock; |
2620 | } |
2621 | } else { |
2622 | /* wait in queue */ |
2623 | WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); |
2624 | list_add_tail(&this_flusher.list, &wq->flusher_queue); |
2625 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
2626 | } |
2627 | } else { |
2628 | /* |
2629 | * Oops, color space is full, wait on overflow queue. |
2630 | * The next flush completion will assign us |
2631 | * flush_color and transfer to flusher_queue. |
2632 | */ |
2633 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
2634 | } |
2635 | |
2636 | mutex_unlock(&wq->mutex); |
2637 | |
2638 | wait_for_completion(&this_flusher.done); |
2639 | |
2640 | /* |
2641 | * Wake-up-and-cascade phase |
2642 | * |
2643 | * First flushers are responsible for cascading flushes and |
2644 | * handling overflow. Non-first flushers can simply return. |
2645 | */ |
2646 | if (wq->first_flusher != &this_flusher) |
2647 | return; |
2648 | |
2649 | mutex_lock(&wq->mutex); |
2650 | |
2651 | /* we might have raced, check again with mutex held */ |
2652 | if (wq->first_flusher != &this_flusher) |
2653 | goto out_unlock; |
2654 | |
2655 | wq->first_flusher = NULL; |
2656 | |
2657 | WARN_ON_ONCE(!list_empty(&this_flusher.list)); |
2658 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
2659 | |
2660 | while (true) { |
2661 | struct wq_flusher *next, *tmp; |
2662 | |
2663 | /* complete all the flushers sharing the current flush color */ |
2664 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
2665 | if (next->flush_color != wq->flush_color) |
2666 | break; |
2667 | list_del_init(&next->list); |
2668 | complete(&next->done); |
2669 | } |
2670 | |
2671 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && |
2672 | wq->flush_color != work_next_color(wq->work_color)); |
2673 | |
2674 | /* this flush_color is finished, advance by one */ |
2675 | wq->flush_color = work_next_color(wq->flush_color); |
2676 | |
2677 | /* one color has been freed, handle overflow queue */ |
2678 | if (!list_empty(&wq->flusher_overflow)) { |
2679 | /* |
2680 | * Assign the same color to all overflowed |
2681 | * flushers, advance work_color and append to |
2682 | * flusher_queue. This is the start-to-wait |
2683 | * phase for these overflowed flushers. |
2684 | */ |
2685 | list_for_each_entry(tmp, &wq->flusher_overflow, list) |
2686 | tmp->flush_color = wq->work_color; |
2687 | |
2688 | wq->work_color = work_next_color(wq->work_color); |
2689 | |
2690 | list_splice_tail_init(&wq->flusher_overflow, |
2691 | &wq->flusher_queue); |
2692 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
2693 | } |
2694 | |
2695 | if (list_empty(&wq->flusher_queue)) { |
2696 | WARN_ON_ONCE(wq->flush_color != wq->work_color); |
2697 | break; |
2698 | } |
2699 | |
2700 | /* |
2701 | * Need to flush more colors. Make the next flusher |
2702 | * the new first flusher and arm pwqs. |
2703 | */ |
2704 | WARN_ON_ONCE(wq->flush_color == wq->work_color); |
2705 | WARN_ON_ONCE(wq->flush_color != next->flush_color); |
2706 | |
2707 | list_del_init(&next->list); |
2708 | wq->first_flusher = next; |
2709 | |
2710 | if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) |
2711 | break; |
2712 | |
2713 | /* |
2714 | * Meh... this color is already done, clear first |
2715 | * flusher and repeat cascading. |
2716 | */ |
2717 | wq->first_flusher = NULL; |
2718 | } |
2719 | |
2720 | out_unlock: |
2721 | mutex_unlock(&wq->mutex); |
2722 | } |
2723 | EXPORT_SYMBOL_GPL(flush_workqueue); |
2724 | |
2725 | /** |
2726 | * drain_workqueue - drain a workqueue |
2727 | * @wq: workqueue to drain |
2728 | * |
2729 | * Wait until the workqueue becomes empty. While draining is in progress, |
2730 | * only chain queueing is allowed. IOW, only currently pending or running |
2731 | * work items on @wq can queue further work items on it. @wq is flushed |
2732 | * repeatedly until it becomes empty. The number of flushing is detemined |
2733 | * by the depth of chaining and should be relatively short. Whine if it |
2734 | * takes too long. |
2735 | */ |
2736 | void drain_workqueue(struct workqueue_struct *wq) |
2737 | { |
2738 | unsigned int flush_cnt = 0; |
2739 | struct pool_workqueue *pwq; |
2740 | |
2741 | /* |
2742 | * __queue_work() needs to test whether there are drainers, is much |
2743 | * hotter than drain_workqueue() and already looks at @wq->flags. |
2744 | * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. |
2745 | */ |
2746 | mutex_lock(&wq->mutex); |
2747 | if (!wq->nr_drainers++) |
2748 | wq->flags |= __WQ_DRAINING; |
2749 | mutex_unlock(&wq->mutex); |
2750 | reflush: |
2751 | flush_workqueue(wq); |
2752 | |
2753 | mutex_lock(&wq->mutex); |
2754 | |
2755 | for_each_pwq(pwq, wq) { |
2756 | bool drained; |
2757 | |
2758 | spin_lock_irq(&pwq->pool->lock); |
2759 | drained = !pwq->nr_active && list_empty(&pwq->delayed_works); |
2760 | spin_unlock_irq(&pwq->pool->lock); |
2761 | |
2762 | if (drained) |
2763 | continue; |
2764 | |
2765 | if (++flush_cnt == 10 || |
2766 | (flush_cnt % 100 == 0 && flush_cnt <= 1000)) |
2767 | pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n", |
2768 | wq->name, flush_cnt); |
2769 | |
2770 | mutex_unlock(&wq->mutex); |
2771 | goto reflush; |
2772 | } |
2773 | |
2774 | if (!--wq->nr_drainers) |
2775 | wq->flags &= ~__WQ_DRAINING; |
2776 | mutex_unlock(&wq->mutex); |
2777 | } |
2778 | EXPORT_SYMBOL_GPL(drain_workqueue); |
2779 | |
2780 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) |
2781 | { |
2782 | struct worker *worker = NULL; |
2783 | struct worker_pool *pool; |
2784 | struct pool_workqueue *pwq; |
2785 | |
2786 | might_sleep(); |
2787 | |
2788 | local_irq_disable(); |
2789 | pool = get_work_pool(work); |
2790 | if (!pool) { |
2791 | local_irq_enable(); |
2792 | return false; |
2793 | } |
2794 | |
2795 | spin_lock(&pool->lock); |
2796 | /* see the comment in try_to_grab_pending() with the same code */ |
2797 | pwq = get_work_pwq(work); |
2798 | if (pwq) { |
2799 | if (unlikely(pwq->pool != pool)) |
2800 | goto already_gone; |
2801 | } else { |
2802 | worker = find_worker_executing_work(pool, work); |
2803 | if (!worker) |
2804 | goto already_gone; |
2805 | pwq = worker->current_pwq; |
2806 | } |
2807 | |
2808 | insert_wq_barrier(pwq, barr, work, worker); |
2809 | spin_unlock_irq(&pool->lock); |
2810 | |
2811 | /* |
2812 | * If @max_active is 1 or rescuer is in use, flushing another work |
2813 | * item on the same workqueue may lead to deadlock. Make sure the |
2814 | * flusher is not running on the same workqueue by verifying write |
2815 | * access. |
2816 | */ |
2817 | if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) |
2818 | lock_map_acquire(&pwq->wq->lockdep_map); |
2819 | else |
2820 | lock_map_acquire_read(&pwq->wq->lockdep_map); |
2821 | lock_map_release(&pwq->wq->lockdep_map); |
2822 | |
2823 | return true; |
2824 | already_gone: |
2825 | spin_unlock_irq(&pool->lock); |
2826 | return false; |
2827 | } |
2828 | |
2829 | static bool __flush_work(struct work_struct *work) |
2830 | { |
2831 | struct wq_barrier barr; |
2832 | |
2833 | if (start_flush_work(work, &barr)) { |
2834 | wait_for_completion(&barr.done); |
2835 | destroy_work_on_stack(&barr.work); |
2836 | return true; |
2837 | } else { |
2838 | return false; |
2839 | } |
2840 | } |
2841 | |
2842 | /** |
2843 | * flush_work - wait for a work to finish executing the last queueing instance |
2844 | * @work: the work to flush |
2845 | * |
2846 | * Wait until @work has finished execution. @work is guaranteed to be idle |
2847 | * on return if it hasn't been requeued since flush started. |
2848 | * |
2849 | * RETURNS: |
2850 | * %true if flush_work() waited for the work to finish execution, |
2851 | * %false if it was already idle. |
2852 | */ |
2853 | bool flush_work(struct work_struct *work) |
2854 | { |
2855 | lock_map_acquire(&work->lockdep_map); |
2856 | lock_map_release(&work->lockdep_map); |
2857 | |
2858 | return __flush_work(work); |
2859 | } |
2860 | EXPORT_SYMBOL_GPL(flush_work); |
2861 | |
2862 | static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) |
2863 | { |
2864 | unsigned long flags; |
2865 | int ret; |
2866 | |
2867 | do { |
2868 | ret = try_to_grab_pending(work, is_dwork, &flags); |
2869 | /* |
2870 | * If someone else is canceling, wait for the same event it |
2871 | * would be waiting for before retrying. |
2872 | */ |
2873 | if (unlikely(ret == -ENOENT)) |
2874 | flush_work(work); |
2875 | } while (unlikely(ret < 0)); |
2876 | |
2877 | /* tell other tasks trying to grab @work to back off */ |
2878 | mark_work_canceling(work); |
2879 | local_irq_restore(flags); |
2880 | |
2881 | flush_work(work); |
2882 | clear_work_data(work); |
2883 | return ret; |
2884 | } |
2885 | |
2886 | /** |
2887 | * cancel_work_sync - cancel a work and wait for it to finish |
2888 | * @work: the work to cancel |
2889 | * |
2890 | * Cancel @work and wait for its execution to finish. This function |
2891 | * can be used even if the work re-queues itself or migrates to |
2892 | * another workqueue. On return from this function, @work is |
2893 | * guaranteed to be not pending or executing on any CPU. |
2894 | * |
2895 | * cancel_work_sync(&delayed_work->work) must not be used for |
2896 | * delayed_work's. Use cancel_delayed_work_sync() instead. |
2897 | * |
2898 | * The caller must ensure that the workqueue on which @work was last |
2899 | * queued can't be destroyed before this function returns. |
2900 | * |
2901 | * RETURNS: |
2902 | * %true if @work was pending, %false otherwise. |
2903 | */ |
2904 | bool cancel_work_sync(struct work_struct *work) |
2905 | { |
2906 | return __cancel_work_timer(work, false); |
2907 | } |
2908 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
2909 | |
2910 | /** |
2911 | * flush_delayed_work - wait for a dwork to finish executing the last queueing |
2912 | * @dwork: the delayed work to flush |
2913 | * |
2914 | * Delayed timer is cancelled and the pending work is queued for |
2915 | * immediate execution. Like flush_work(), this function only |
2916 | * considers the last queueing instance of @dwork. |
2917 | * |
2918 | * RETURNS: |
2919 | * %true if flush_work() waited for the work to finish execution, |
2920 | * %false if it was already idle. |
2921 | */ |
2922 | bool flush_delayed_work(struct delayed_work *dwork) |
2923 | { |
2924 | local_irq_disable(); |
2925 | if (del_timer_sync(&dwork->timer)) |
2926 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); |
2927 | local_irq_enable(); |
2928 | return flush_work(&dwork->work); |
2929 | } |
2930 | EXPORT_SYMBOL(flush_delayed_work); |
2931 | |
2932 | /** |
2933 | * cancel_delayed_work - cancel a delayed work |
2934 | * @dwork: delayed_work to cancel |
2935 | * |
2936 | * Kill off a pending delayed_work. Returns %true if @dwork was pending |
2937 | * and canceled; %false if wasn't pending. Note that the work callback |
2938 | * function may still be running on return, unless it returns %true and the |
2939 | * work doesn't re-arm itself. Explicitly flush or use |
2940 | * cancel_delayed_work_sync() to wait on it. |
2941 | * |
2942 | * This function is safe to call from any context including IRQ handler. |
2943 | */ |
2944 | bool cancel_delayed_work(struct delayed_work *dwork) |
2945 | { |
2946 | unsigned long flags; |
2947 | int ret; |
2948 | |
2949 | do { |
2950 | ret = try_to_grab_pending(&dwork->work, true, &flags); |
2951 | } while (unlikely(ret == -EAGAIN)); |
2952 | |
2953 | if (unlikely(ret < 0)) |
2954 | return false; |
2955 | |
2956 | set_work_pool_and_clear_pending(&dwork->work, |
2957 | get_work_pool_id(&dwork->work)); |
2958 | local_irq_restore(flags); |
2959 | return ret; |
2960 | } |
2961 | EXPORT_SYMBOL(cancel_delayed_work); |
2962 | |
2963 | /** |
2964 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish |
2965 | * @dwork: the delayed work cancel |
2966 | * |
2967 | * This is cancel_work_sync() for delayed works. |
2968 | * |
2969 | * RETURNS: |
2970 | * %true if @dwork was pending, %false otherwise. |
2971 | */ |
2972 | bool cancel_delayed_work_sync(struct delayed_work *dwork) |
2973 | { |
2974 | return __cancel_work_timer(&dwork->work, true); |
2975 | } |
2976 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
2977 | |
2978 | /** |
2979 | * schedule_on_each_cpu - execute a function synchronously on each online CPU |
2980 | * @func: the function to call |
2981 | * |
2982 | * schedule_on_each_cpu() executes @func on each online CPU using the |
2983 | * system workqueue and blocks until all CPUs have completed. |
2984 | * schedule_on_each_cpu() is very slow. |
2985 | * |
2986 | * RETURNS: |
2987 | * 0 on success, -errno on failure. |
2988 | */ |
2989 | int schedule_on_each_cpu(work_func_t func) |
2990 | { |
2991 | int cpu; |
2992 | struct work_struct __percpu *works; |
2993 | |
2994 | works = alloc_percpu(struct work_struct); |
2995 | if (!works) |
2996 | return -ENOMEM; |
2997 | |
2998 | get_online_cpus(); |
2999 | |
3000 | for_each_online_cpu(cpu) { |
3001 | struct work_struct *work = per_cpu_ptr(works, cpu); |
3002 | |
3003 | INIT_WORK(work, func); |
3004 | schedule_work_on(cpu, work); |
3005 | } |
3006 | |
3007 | for_each_online_cpu(cpu) |
3008 | flush_work(per_cpu_ptr(works, cpu)); |
3009 | |
3010 | put_online_cpus(); |
3011 | free_percpu(works); |
3012 | return 0; |
3013 | } |
3014 | |
3015 | /** |
3016 | * flush_scheduled_work - ensure that any scheduled work has run to completion. |
3017 | * |
3018 | * Forces execution of the kernel-global workqueue and blocks until its |
3019 | * completion. |
3020 | * |
3021 | * Think twice before calling this function! It's very easy to get into |
3022 | * trouble if you don't take great care. Either of the following situations |
3023 | * will lead to deadlock: |
3024 | * |
3025 | * One of the work items currently on the workqueue needs to acquire |
3026 | * a lock held by your code or its caller. |
3027 | * |
3028 | * Your code is running in the context of a work routine. |
3029 | * |
3030 | * They will be detected by lockdep when they occur, but the first might not |
3031 | * occur very often. It depends on what work items are on the workqueue and |
3032 | * what locks they need, which you have no control over. |
3033 | * |
3034 | * In most situations flushing the entire workqueue is overkill; you merely |
3035 | * need to know that a particular work item isn't queued and isn't running. |
3036 | * In such cases you should use cancel_delayed_work_sync() or |
3037 | * cancel_work_sync() instead. |
3038 | */ |
3039 | void flush_scheduled_work(void) |
3040 | { |
3041 | flush_workqueue(system_wq); |
3042 | } |
3043 | EXPORT_SYMBOL(flush_scheduled_work); |
3044 | |
3045 | /** |
3046 | * execute_in_process_context - reliably execute the routine with user context |
3047 | * @fn: the function to execute |
3048 | * @ew: guaranteed storage for the execute work structure (must |
3049 | * be available when the work executes) |
3050 | * |
3051 | * Executes the function immediately if process context is available, |
3052 | * otherwise schedules the function for delayed execution. |
3053 | * |
3054 | * Returns: 0 - function was executed |
3055 | * 1 - function was scheduled for execution |
3056 | */ |
3057 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
3058 | { |
3059 | if (!in_interrupt()) { |
3060 | fn(&ew->work); |
3061 | return 0; |
3062 | } |
3063 | |
3064 | INIT_WORK(&ew->work, fn); |
3065 | schedule_work(&ew->work); |
3066 | |
3067 | return 1; |
3068 | } |
3069 | EXPORT_SYMBOL_GPL(execute_in_process_context); |
3070 | |
3071 | #ifdef CONFIG_SYSFS |
3072 | /* |
3073 | * Workqueues with WQ_SYSFS flag set is visible to userland via |
3074 | * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the |
3075 | * following attributes. |
3076 | * |
3077 | * per_cpu RO bool : whether the workqueue is per-cpu or unbound |
3078 | * max_active RW int : maximum number of in-flight work items |
3079 | * |
3080 | * Unbound workqueues have the following extra attributes. |
3081 | * |
3082 | * id RO int : the associated pool ID |
3083 | * nice RW int : nice value of the workers |
3084 | * cpumask RW mask : bitmask of allowed CPUs for the workers |
3085 | */ |
3086 | struct wq_device { |
3087 | struct workqueue_struct *wq; |
3088 | struct device dev; |
3089 | }; |
3090 | |
3091 | static struct workqueue_struct *dev_to_wq(struct device *dev) |
3092 | { |
3093 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
3094 | |
3095 | return wq_dev->wq; |
3096 | } |
3097 | |
3098 | static ssize_t wq_per_cpu_show(struct device *dev, |
3099 | struct device_attribute *attr, char *buf) |
3100 | { |
3101 | struct workqueue_struct *wq = dev_to_wq(dev); |
3102 | |
3103 | return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); |
3104 | } |
3105 | |
3106 | static ssize_t wq_max_active_show(struct device *dev, |
3107 | struct device_attribute *attr, char *buf) |
3108 | { |
3109 | struct workqueue_struct *wq = dev_to_wq(dev); |
3110 | |
3111 | return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); |
3112 | } |
3113 | |
3114 | static ssize_t wq_max_active_store(struct device *dev, |
3115 | struct device_attribute *attr, |
3116 | const char *buf, size_t count) |
3117 | { |
3118 | struct workqueue_struct *wq = dev_to_wq(dev); |
3119 | int val; |
3120 | |
3121 | if (sscanf(buf, "%d", &val) != 1 || val <= 0) |
3122 | return -EINVAL; |
3123 | |
3124 | workqueue_set_max_active(wq, val); |
3125 | return count; |
3126 | } |
3127 | |
3128 | static struct device_attribute wq_sysfs_attrs[] = { |
3129 | __ATTR(per_cpu, 0444, wq_per_cpu_show, NULL), |
3130 | __ATTR(max_active, 0644, wq_max_active_show, wq_max_active_store), |
3131 | __ATTR_NULL, |
3132 | }; |
3133 | |
3134 | static ssize_t wq_pool_ids_show(struct device *dev, |
3135 | struct device_attribute *attr, char *buf) |
3136 | { |
3137 | struct workqueue_struct *wq = dev_to_wq(dev); |
3138 | const char *delim = ""; |
3139 | int node, written = 0; |
3140 | |
3141 | rcu_read_lock_sched(); |
3142 | for_each_node(node) { |
3143 | written += scnprintf(buf + written, PAGE_SIZE - written, |
3144 | "%s%d:%d", delim, node, |
3145 | unbound_pwq_by_node(wq, node)->pool->id); |
3146 | delim = " "; |
3147 | } |
3148 | written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); |
3149 | rcu_read_unlock_sched(); |
3150 | |
3151 | return written; |
3152 | } |
3153 | |
3154 | static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, |
3155 | char *buf) |
3156 | { |
3157 | struct workqueue_struct *wq = dev_to_wq(dev); |
3158 | int written; |
3159 | |
3160 | mutex_lock(&wq->mutex); |
3161 | written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); |
3162 | mutex_unlock(&wq->mutex); |
3163 | |
3164 | return written; |
3165 | } |
3166 | |
3167 | /* prepare workqueue_attrs for sysfs store operations */ |
3168 | static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) |
3169 | { |
3170 | struct workqueue_attrs *attrs; |
3171 | |
3172 | attrs = alloc_workqueue_attrs(GFP_KERNEL); |
3173 | if (!attrs) |
3174 | return NULL; |
3175 | |
3176 | mutex_lock(&wq->mutex); |
3177 | copy_workqueue_attrs(attrs, wq->unbound_attrs); |
3178 | mutex_unlock(&wq->mutex); |
3179 | return attrs; |
3180 | } |
3181 | |
3182 | static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, |
3183 | const char *buf, size_t count) |
3184 | { |
3185 | struct workqueue_struct *wq = dev_to_wq(dev); |
3186 | struct workqueue_attrs *attrs; |
3187 | int ret; |
3188 | |
3189 | attrs = wq_sysfs_prep_attrs(wq); |
3190 | if (!attrs) |
3191 | return -ENOMEM; |
3192 | |
3193 | if (sscanf(buf, "%d", &attrs->nice) == 1 && |
3194 | attrs->nice >= -20 && attrs->nice <= 19) |
3195 | ret = apply_workqueue_attrs(wq, attrs); |
3196 | else |
3197 | ret = -EINVAL; |
3198 | |
3199 | free_workqueue_attrs(attrs); |
3200 | return ret ?: count; |
3201 | } |
3202 | |
3203 | static ssize_t wq_cpumask_show(struct device *dev, |
3204 | struct device_attribute *attr, char *buf) |
3205 | { |
3206 | struct workqueue_struct *wq = dev_to_wq(dev); |
3207 | int written; |
3208 | |
3209 | mutex_lock(&wq->mutex); |
3210 | written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask); |
3211 | mutex_unlock(&wq->mutex); |
3212 | |
3213 | written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); |
3214 | return written; |
3215 | } |
3216 | |
3217 | static ssize_t wq_cpumask_store(struct device *dev, |
3218 | struct device_attribute *attr, |
3219 | const char *buf, size_t count) |
3220 | { |
3221 | struct workqueue_struct *wq = dev_to_wq(dev); |
3222 | struct workqueue_attrs *attrs; |
3223 | int ret; |
3224 | |
3225 | attrs = wq_sysfs_prep_attrs(wq); |
3226 | if (!attrs) |
3227 | return -ENOMEM; |
3228 | |
3229 | ret = cpumask_parse(buf, attrs->cpumask); |
3230 | if (!ret) |
3231 | ret = apply_workqueue_attrs(wq, attrs); |
3232 | |
3233 | free_workqueue_attrs(attrs); |
3234 | return ret ?: count; |
3235 | } |
3236 | |
3237 | static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, |
3238 | char *buf) |
3239 | { |
3240 | struct workqueue_struct *wq = dev_to_wq(dev); |
3241 | int written; |
3242 | |
3243 | mutex_lock(&wq->mutex); |
3244 | written = scnprintf(buf, PAGE_SIZE, "%d\n", |
3245 | !wq->unbound_attrs->no_numa); |
3246 | mutex_unlock(&wq->mutex); |
3247 | |
3248 | return written; |
3249 | } |
3250 | |
3251 | static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, |
3252 | const char *buf, size_t count) |
3253 | { |
3254 | struct workqueue_struct *wq = dev_to_wq(dev); |
3255 | struct workqueue_attrs *attrs; |
3256 | int v, ret; |
3257 | |
3258 | attrs = wq_sysfs_prep_attrs(wq); |
3259 | if (!attrs) |
3260 | return -ENOMEM; |
3261 | |
3262 | ret = -EINVAL; |
3263 | if (sscanf(buf, "%d", &v) == 1) { |
3264 | attrs->no_numa = !v; |
3265 | ret = apply_workqueue_attrs(wq, attrs); |
3266 | } |
3267 | |
3268 | free_workqueue_attrs(attrs); |
3269 | return ret ?: count; |
3270 | } |
3271 | |
3272 | static struct device_attribute wq_sysfs_unbound_attrs[] = { |
3273 | __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), |
3274 | __ATTR(nice, 0644, wq_nice_show, wq_nice_store), |
3275 | __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), |
3276 | __ATTR(numa, 0644, wq_numa_show, wq_numa_store), |
3277 | __ATTR_NULL, |
3278 | }; |
3279 | |
3280 | static struct bus_type wq_subsys = { |
3281 | .name = "workqueue", |
3282 | .dev_attrs = wq_sysfs_attrs, |
3283 | }; |
3284 | |
3285 | static int __init wq_sysfs_init(void) |
3286 | { |
3287 | return subsys_virtual_register(&wq_subsys, NULL); |
3288 | } |
3289 | core_initcall(wq_sysfs_init); |
3290 | |
3291 | static void wq_device_release(struct device *dev) |
3292 | { |
3293 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
3294 | |
3295 | kfree(wq_dev); |
3296 | } |
3297 | |
3298 | /** |
3299 | * workqueue_sysfs_register - make a workqueue visible in sysfs |
3300 | * @wq: the workqueue to register |
3301 | * |
3302 | * Expose @wq in sysfs under /sys/bus/workqueue/devices. |
3303 | * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set |
3304 | * which is the preferred method. |
3305 | * |
3306 | * Workqueue user should use this function directly iff it wants to apply |
3307 | * workqueue_attrs before making the workqueue visible in sysfs; otherwise, |
3308 | * apply_workqueue_attrs() may race against userland updating the |
3309 | * attributes. |
3310 | * |
3311 | * Returns 0 on success, -errno on failure. |
3312 | */ |
3313 | int workqueue_sysfs_register(struct workqueue_struct *wq) |
3314 | { |
3315 | struct wq_device *wq_dev; |
3316 | int ret; |
3317 | |
3318 | /* |
3319 | * Adjusting max_active or creating new pwqs by applyting |
3320 | * attributes breaks ordering guarantee. Disallow exposing ordered |
3321 | * workqueues. |
3322 | */ |
3323 | if (WARN_ON(wq->flags & __WQ_ORDERED)) |
3324 | return -EINVAL; |
3325 | |
3326 | wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); |
3327 | if (!wq_dev) |
3328 | return -ENOMEM; |
3329 | |
3330 | wq_dev->wq = wq; |
3331 | wq_dev->dev.bus = &wq_subsys; |
3332 | wq_dev->dev.init_name = wq->name; |
3333 | wq_dev->dev.release = wq_device_release; |
3334 | |
3335 | /* |
3336 | * unbound_attrs are created separately. Suppress uevent until |
3337 | * everything is ready. |
3338 | */ |
3339 | dev_set_uevent_suppress(&wq_dev->dev, true); |
3340 | |
3341 | ret = device_register(&wq_dev->dev); |
3342 | if (ret) { |
3343 | kfree(wq_dev); |
3344 | wq->wq_dev = NULL; |
3345 | return ret; |
3346 | } |
3347 | |
3348 | if (wq->flags & WQ_UNBOUND) { |
3349 | struct device_attribute *attr; |
3350 | |
3351 | for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { |
3352 | ret = device_create_file(&wq_dev->dev, attr); |
3353 | if (ret) { |
3354 | device_unregister(&wq_dev->dev); |
3355 | wq->wq_dev = NULL; |
3356 | return ret; |
3357 | } |
3358 | } |
3359 | } |
3360 | |
3361 | kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); |
3362 | return 0; |
3363 | } |
3364 | |
3365 | /** |
3366 | * workqueue_sysfs_unregister - undo workqueue_sysfs_register() |
3367 | * @wq: the workqueue to unregister |
3368 | * |
3369 | * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. |
3370 | */ |
3371 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) |
3372 | { |
3373 | struct wq_device *wq_dev = wq->wq_dev; |
3374 | |
3375 | if (!wq->wq_dev) |
3376 | return; |
3377 | |
3378 | wq->wq_dev = NULL; |
3379 | device_unregister(&wq_dev->dev); |
3380 | } |
3381 | #else /* CONFIG_SYSFS */ |
3382 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } |
3383 | #endif /* CONFIG_SYSFS */ |
3384 | |
3385 | /** |
3386 | * free_workqueue_attrs - free a workqueue_attrs |
3387 | * @attrs: workqueue_attrs to free |
3388 | * |
3389 | * Undo alloc_workqueue_attrs(). |
3390 | */ |
3391 | void free_workqueue_attrs(struct workqueue_attrs *attrs) |
3392 | { |
3393 | if (attrs) { |
3394 | free_cpumask_var(attrs->cpumask); |
3395 | kfree(attrs); |
3396 | } |
3397 | } |
3398 | |
3399 | /** |
3400 | * alloc_workqueue_attrs - allocate a workqueue_attrs |
3401 | * @gfp_mask: allocation mask to use |
3402 | * |
3403 | * Allocate a new workqueue_attrs, initialize with default settings and |
3404 | * return it. Returns NULL on failure. |
3405 | */ |
3406 | struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask) |
3407 | { |
3408 | struct workqueue_attrs *attrs; |
3409 | |
3410 | attrs = kzalloc(sizeof(*attrs), gfp_mask); |
3411 | if (!attrs) |
3412 | goto fail; |
3413 | if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask)) |
3414 | goto fail; |
3415 | |
3416 | cpumask_copy(attrs->cpumask, cpu_possible_mask); |
3417 | return attrs; |
3418 | fail: |
3419 | free_workqueue_attrs(attrs); |
3420 | return NULL; |
3421 | } |
3422 | |
3423 | static void copy_workqueue_attrs(struct workqueue_attrs *to, |
3424 | const struct workqueue_attrs *from) |
3425 | { |
3426 | to->nice = from->nice; |
3427 | cpumask_copy(to->cpumask, from->cpumask); |
3428 | /* |
3429 | * Unlike hash and equality test, this function doesn't ignore |
3430 | * ->no_numa as it is used for both pool and wq attrs. Instead, |
3431 | * get_unbound_pool() explicitly clears ->no_numa after copying. |
3432 | */ |
3433 | to->no_numa = from->no_numa; |
3434 | } |
3435 | |
3436 | /* hash value of the content of @attr */ |
3437 | static u32 wqattrs_hash(const struct workqueue_attrs *attrs) |
3438 | { |
3439 | u32 hash = 0; |
3440 | |
3441 | hash = jhash_1word(attrs->nice, hash); |
3442 | hash = jhash(cpumask_bits(attrs->cpumask), |
3443 | BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); |
3444 | return hash; |
3445 | } |
3446 | |
3447 | /* content equality test */ |
3448 | static bool wqattrs_equal(const struct workqueue_attrs *a, |
3449 | const struct workqueue_attrs *b) |
3450 | { |
3451 | if (a->nice != b->nice) |
3452 | return false; |
3453 | if (!cpumask_equal(a->cpumask, b->cpumask)) |
3454 | return false; |
3455 | return true; |
3456 | } |
3457 | |
3458 | /** |
3459 | * init_worker_pool - initialize a newly zalloc'd worker_pool |
3460 | * @pool: worker_pool to initialize |
3461 | * |
3462 | * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs. |
3463 | * Returns 0 on success, -errno on failure. Even on failure, all fields |
3464 | * inside @pool proper are initialized and put_unbound_pool() can be called |
3465 | * on @pool safely to release it. |
3466 | */ |
3467 | static int init_worker_pool(struct worker_pool *pool) |
3468 | { |
3469 | spin_lock_init(&pool->lock); |
3470 | pool->id = -1; |
3471 | pool->cpu = -1; |
3472 | pool->node = NUMA_NO_NODE; |
3473 | pool->flags |= POOL_DISASSOCIATED; |
3474 | INIT_LIST_HEAD(&pool->worklist); |
3475 | INIT_LIST_HEAD(&pool->idle_list); |
3476 | hash_init(pool->busy_hash); |
3477 | |
3478 | init_timer_deferrable(&pool->idle_timer); |
3479 | pool->idle_timer.function = idle_worker_timeout; |
3480 | pool->idle_timer.data = (unsigned long)pool; |
3481 | |
3482 | setup_timer(&pool->mayday_timer, pool_mayday_timeout, |
3483 | (unsigned long)pool); |
3484 | |
3485 | mutex_init(&pool->manager_arb); |
3486 | mutex_init(&pool->manager_mutex); |
3487 | idr_init(&pool->worker_idr); |
3488 | |
3489 | INIT_HLIST_NODE(&pool->hash_node); |
3490 | pool->refcnt = 1; |
3491 | |
3492 | /* shouldn't fail above this point */ |
3493 | pool->attrs = alloc_workqueue_attrs(GFP_KERNEL); |
3494 | if (!pool->attrs) |
3495 | return -ENOMEM; |
3496 | return 0; |
3497 | } |
3498 | |
3499 | static void rcu_free_pool(struct rcu_head *rcu) |
3500 | { |
3501 | struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); |
3502 | |
3503 | idr_destroy(&pool->worker_idr); |
3504 | free_workqueue_attrs(pool->attrs); |
3505 | kfree(pool); |
3506 | } |
3507 | |
3508 | /** |
3509 | * put_unbound_pool - put a worker_pool |
3510 | * @pool: worker_pool to put |
3511 | * |
3512 | * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU |
3513 | * safe manner. get_unbound_pool() calls this function on its failure path |
3514 | * and this function should be able to release pools which went through, |
3515 | * successfully or not, init_worker_pool(). |
3516 | * |
3517 | * Should be called with wq_pool_mutex held. |
3518 | */ |
3519 | static void put_unbound_pool(struct worker_pool *pool) |
3520 | { |
3521 | struct worker *worker; |
3522 | |
3523 | lockdep_assert_held(&wq_pool_mutex); |
3524 | |
3525 | if (--pool->refcnt) |
3526 | return; |
3527 | |
3528 | /* sanity checks */ |
3529 | if (WARN_ON(!(pool->flags & POOL_DISASSOCIATED)) || |
3530 | WARN_ON(!list_empty(&pool->worklist))) |
3531 | return; |
3532 | |
3533 | /* release id and unhash */ |
3534 | if (pool->id >= 0) |
3535 | idr_remove(&worker_pool_idr, pool->id); |
3536 | hash_del(&pool->hash_node); |
3537 | |
3538 | /* |
3539 | * Become the manager and destroy all workers. Grabbing |
3540 | * manager_arb prevents @pool's workers from blocking on |
3541 | * manager_mutex. |
3542 | */ |
3543 | mutex_lock(&pool->manager_arb); |
3544 | mutex_lock(&pool->manager_mutex); |
3545 | spin_lock_irq(&pool->lock); |
3546 | |
3547 | while ((worker = first_worker(pool))) |
3548 | destroy_worker(worker); |
3549 | WARN_ON(pool->nr_workers || pool->nr_idle); |
3550 | |
3551 | spin_unlock_irq(&pool->lock); |
3552 | mutex_unlock(&pool->manager_mutex); |
3553 | mutex_unlock(&pool->manager_arb); |
3554 | |
3555 | /* shut down the timers */ |
3556 | del_timer_sync(&pool->idle_timer); |
3557 | del_timer_sync(&pool->mayday_timer); |
3558 | |
3559 | /* sched-RCU protected to allow dereferences from get_work_pool() */ |
3560 | call_rcu_sched(&pool->rcu, rcu_free_pool); |
3561 | } |
3562 | |
3563 | /** |
3564 | * get_unbound_pool - get a worker_pool with the specified attributes |
3565 | * @attrs: the attributes of the worker_pool to get |
3566 | * |
3567 | * Obtain a worker_pool which has the same attributes as @attrs, bump the |
3568 | * reference count and return it. If there already is a matching |
3569 | * worker_pool, it will be used; otherwise, this function attempts to |
3570 | * create a new one. On failure, returns NULL. |
3571 | * |
3572 | * Should be called with wq_pool_mutex held. |
3573 | */ |
3574 | static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) |
3575 | { |
3576 | u32 hash = wqattrs_hash(attrs); |
3577 | struct worker_pool *pool; |
3578 | int node; |
3579 | |
3580 | lockdep_assert_held(&wq_pool_mutex); |
3581 | |
3582 | /* do we already have a matching pool? */ |
3583 | hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { |
3584 | if (wqattrs_equal(pool->attrs, attrs)) { |
3585 | pool->refcnt++; |
3586 | goto out_unlock; |
3587 | } |
3588 | } |
3589 | |
3590 | /* nope, create a new one */ |
3591 | pool = kzalloc(sizeof(*pool), GFP_KERNEL); |
3592 | if (!pool || init_worker_pool(pool) < 0) |
3593 | goto fail; |
3594 | |
3595 | if (workqueue_freezing) |
3596 | pool->flags |= POOL_FREEZING; |
3597 | |
3598 | lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ |
3599 | copy_workqueue_attrs(pool->attrs, attrs); |
3600 | |
3601 | /* |
3602 | * no_numa isn't a worker_pool attribute, always clear it. See |
3603 | * 'struct workqueue_attrs' comments for detail. |
3604 | */ |
3605 | pool->attrs->no_numa = false; |
3606 | |
3607 | /* if cpumask is contained inside a NUMA node, we belong to that node */ |
3608 | if (wq_numa_enabled) { |
3609 | for_each_node(node) { |
3610 | if (cpumask_subset(pool->attrs->cpumask, |
3611 | wq_numa_possible_cpumask[node])) { |
3612 | pool->node = node; |
3613 | break; |
3614 | } |
3615 | } |
3616 | } |
3617 | |
3618 | if (worker_pool_assign_id(pool) < 0) |
3619 | goto fail; |
3620 | |
3621 | /* create and start the initial worker */ |
3622 | if (create_and_start_worker(pool) < 0) |
3623 | goto fail; |
3624 | |
3625 | /* install */ |
3626 | hash_add(unbound_pool_hash, &pool->hash_node, hash); |
3627 | out_unlock: |
3628 | return pool; |
3629 | fail: |
3630 | if (pool) |
3631 | put_unbound_pool(pool); |
3632 | return NULL; |
3633 | } |
3634 | |
3635 | static void rcu_free_pwq(struct rcu_head *rcu) |
3636 | { |
3637 | kmem_cache_free(pwq_cache, |
3638 | container_of(rcu, struct pool_workqueue, rcu)); |
3639 | } |
3640 | |
3641 | /* |
3642 | * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt |
3643 | * and needs to be destroyed. |
3644 | */ |
3645 | static void pwq_unbound_release_workfn(struct work_struct *work) |
3646 | { |
3647 | struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, |
3648 | unbound_release_work); |
3649 | struct workqueue_struct *wq = pwq->wq; |
3650 | struct worker_pool *pool = pwq->pool; |
3651 | bool is_last; |
3652 | |
3653 | if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) |
3654 | return; |
3655 | |
3656 | /* |
3657 | * Unlink @pwq. Synchronization against wq->mutex isn't strictly |
3658 | * necessary on release but do it anyway. It's easier to verify |
3659 | * and consistent with the linking path. |
3660 | */ |
3661 | mutex_lock(&wq->mutex); |
3662 | list_del_rcu(&pwq->pwqs_node); |
3663 | is_last = list_empty(&wq->pwqs); |
3664 | mutex_unlock(&wq->mutex); |
3665 | |
3666 | mutex_lock(&wq_pool_mutex); |
3667 | put_unbound_pool(pool); |
3668 | mutex_unlock(&wq_pool_mutex); |
3669 | |
3670 | call_rcu_sched(&pwq->rcu, rcu_free_pwq); |
3671 | |
3672 | /* |
3673 | * If we're the last pwq going away, @wq is already dead and no one |
3674 | * is gonna access it anymore. Free it. |
3675 | */ |
3676 | if (is_last) { |
3677 | free_workqueue_attrs(wq->unbound_attrs); |
3678 | kfree(wq); |
3679 | } |
3680 | } |
3681 | |
3682 | /** |
3683 | * pwq_adjust_max_active - update a pwq's max_active to the current setting |
3684 | * @pwq: target pool_workqueue |
3685 | * |
3686 | * If @pwq isn't freezing, set @pwq->max_active to the associated |
3687 | * workqueue's saved_max_active and activate delayed work items |
3688 | * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. |
3689 | */ |
3690 | static void pwq_adjust_max_active(struct pool_workqueue *pwq) |
3691 | { |
3692 | struct workqueue_struct *wq = pwq->wq; |
3693 | bool freezable = wq->flags & WQ_FREEZABLE; |
3694 | |
3695 | /* for @wq->saved_max_active */ |
3696 | lockdep_assert_held(&wq->mutex); |
3697 | |
3698 | /* fast exit for non-freezable wqs */ |
3699 | if (!freezable && pwq->max_active == wq->saved_max_active) |
3700 | return; |
3701 | |
3702 | spin_lock_irq(&pwq->pool->lock); |
3703 | |
3704 | if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) { |
3705 | pwq->max_active = wq->saved_max_active; |
3706 | |
3707 | while (!list_empty(&pwq->delayed_works) && |
3708 | pwq->nr_active < pwq->max_active) |
3709 | pwq_activate_first_delayed(pwq); |
3710 | |
3711 | /* |
3712 | * Need to kick a worker after thawed or an unbound wq's |
3713 | * max_active is bumped. It's a slow path. Do it always. |
3714 | */ |
3715 | wake_up_worker(pwq->pool); |
3716 | } else { |
3717 | pwq->max_active = 0; |
3718 | } |
3719 | |
3720 | spin_unlock_irq(&pwq->pool->lock); |
3721 | } |
3722 | |
3723 | /* initialize newly alloced @pwq which is associated with @wq and @pool */ |
3724 | static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, |
3725 | struct worker_pool *pool) |
3726 | { |
3727 | BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); |
3728 | |
3729 | memset(pwq, 0, sizeof(*pwq)); |
3730 | |
3731 | pwq->pool = pool; |
3732 | pwq->wq = wq; |
3733 | pwq->flush_color = -1; |
3734 | pwq->refcnt = 1; |
3735 | INIT_LIST_HEAD(&pwq->delayed_works); |
3736 | INIT_LIST_HEAD(&pwq->pwqs_node); |
3737 | INIT_LIST_HEAD(&pwq->mayday_node); |
3738 | INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); |
3739 | } |
3740 | |
3741 | /* sync @pwq with the current state of its associated wq and link it */ |
3742 | static void link_pwq(struct pool_workqueue *pwq) |
3743 | { |
3744 | struct workqueue_struct *wq = pwq->wq; |
3745 | |
3746 | lockdep_assert_held(&wq->mutex); |
3747 | |
3748 | /* may be called multiple times, ignore if already linked */ |
3749 | if (!list_empty(&pwq->pwqs_node)) |
3750 | return; |
3751 | |
3752 | /* |
3753 | * Set the matching work_color. This is synchronized with |
3754 | * wq->mutex to avoid confusing flush_workqueue(). |
3755 | */ |
3756 | pwq->work_color = wq->work_color; |
3757 | |
3758 | /* sync max_active to the current setting */ |
3759 | pwq_adjust_max_active(pwq); |
3760 | |
3761 | /* link in @pwq */ |
3762 | list_add_rcu(&pwq->pwqs_node, &wq->pwqs); |
3763 | } |
3764 | |
3765 | /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ |
3766 | static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, |
3767 | const struct workqueue_attrs *attrs) |
3768 | { |
3769 | struct worker_pool *pool; |
3770 | struct pool_workqueue *pwq; |
3771 | |
3772 | lockdep_assert_held(&wq_pool_mutex); |
3773 | |
3774 | pool = get_unbound_pool(attrs); |
3775 | if (!pool) |
3776 | return NULL; |
3777 | |
3778 | pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); |
3779 | if (!pwq) { |
3780 | put_unbound_pool(pool); |
3781 | return NULL; |
3782 | } |
3783 | |
3784 | init_pwq(pwq, wq, pool); |
3785 | return pwq; |
3786 | } |
3787 | |
3788 | /* undo alloc_unbound_pwq(), used only in the error path */ |
3789 | static void free_unbound_pwq(struct pool_workqueue *pwq) |
3790 | { |
3791 | lockdep_assert_held(&wq_pool_mutex); |
3792 | |
3793 | if (pwq) { |
3794 | put_unbound_pool(pwq->pool); |
3795 | kmem_cache_free(pwq_cache, pwq); |
3796 | } |
3797 | } |
3798 | |
3799 | /** |
3800 | * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node |
3801 | * @attrs: the wq_attrs of interest |
3802 | * @node: the target NUMA node |
3803 | * @cpu_going_down: if >= 0, the CPU to consider as offline |
3804 | * @cpumask: outarg, the resulting cpumask |
3805 | * |
3806 | * Calculate the cpumask a workqueue with @attrs should use on @node. If |
3807 | * @cpu_going_down is >= 0, that cpu is considered offline during |
3808 | * calculation. The result is stored in @cpumask. This function returns |
3809 | * %true if the resulting @cpumask is different from @attrs->cpumask, |
3810 | * %false if equal. |
3811 | * |
3812 | * If NUMA affinity is not enabled, @attrs->cpumask is always used. If |
3813 | * enabled and @node has online CPUs requested by @attrs, the returned |
3814 | * cpumask is the intersection of the possible CPUs of @node and |
3815 | * @attrs->cpumask. |
3816 | * |
3817 | * The caller is responsible for ensuring that the cpumask of @node stays |
3818 | * stable. |
3819 | */ |
3820 | static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, |
3821 | int cpu_going_down, cpumask_t *cpumask) |
3822 | { |
3823 | if (!wq_numa_enabled || attrs->no_numa) |
3824 | goto use_dfl; |
3825 | |
3826 | /* does @node have any online CPUs @attrs wants? */ |
3827 | cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); |
3828 | if (cpu_going_down >= 0) |
3829 | cpumask_clear_cpu(cpu_going_down, cpumask); |
3830 | |
3831 | if (cpumask_empty(cpumask)) |
3832 | goto use_dfl; |
3833 | |
3834 | /* yeap, return possible CPUs in @node that @attrs wants */ |
3835 | cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); |
3836 | return !cpumask_equal(cpumask, attrs->cpumask); |
3837 | |
3838 | use_dfl: |
3839 | cpumask_copy(cpumask, attrs->cpumask); |
3840 | return false; |
3841 | } |
3842 | |
3843 | /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ |
3844 | static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, |
3845 | int node, |
3846 | struct pool_workqueue *pwq) |
3847 | { |
3848 | struct pool_workqueue *old_pwq; |
3849 | |
3850 | lockdep_assert_held(&wq->mutex); |
3851 | |
3852 | /* link_pwq() can handle duplicate calls */ |
3853 | link_pwq(pwq); |
3854 | |
3855 | old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); |
3856 | rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); |
3857 | return old_pwq; |
3858 | } |
3859 | |
3860 | /** |
3861 | * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue |
3862 | * @wq: the target workqueue |
3863 | * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() |
3864 | * |
3865 | * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA |
3866 | * machines, this function maps a separate pwq to each NUMA node with |
3867 | * possibles CPUs in @attrs->cpumask so that work items are affine to the |
3868 | * NUMA node it was issued on. Older pwqs are released as in-flight work |
3869 | * items finish. Note that a work item which repeatedly requeues itself |
3870 | * back-to-back will stay on its current pwq. |
3871 | * |
3872 | * Performs GFP_KERNEL allocations. Returns 0 on success and -errno on |
3873 | * failure. |
3874 | */ |
3875 | int apply_workqueue_attrs(struct workqueue_struct *wq, |
3876 | const struct workqueue_attrs *attrs) |
3877 | { |
3878 | struct workqueue_attrs *new_attrs, *tmp_attrs; |
3879 | struct pool_workqueue **pwq_tbl, *dfl_pwq; |
3880 | int node, ret; |
3881 | |
3882 | /* only unbound workqueues can change attributes */ |
3883 | if (WARN_ON(!(wq->flags & WQ_UNBOUND))) |
3884 | return -EINVAL; |
3885 | |
3886 | /* creating multiple pwqs breaks ordering guarantee */ |
3887 | if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))) |
3888 | return -EINVAL; |
3889 | |
3890 | pwq_tbl = kzalloc(wq_numa_tbl_len * sizeof(pwq_tbl[0]), GFP_KERNEL); |
3891 | new_attrs = alloc_workqueue_attrs(GFP_KERNEL); |
3892 | tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL); |
3893 | if (!pwq_tbl || !new_attrs || !tmp_attrs) |
3894 | goto enomem; |
3895 | |
3896 | /* make a copy of @attrs and sanitize it */ |
3897 | copy_workqueue_attrs(new_attrs, attrs); |
3898 | cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); |
3899 | |
3900 | /* |
3901 | * We may create multiple pwqs with differing cpumasks. Make a |
3902 | * copy of @new_attrs which will be modified and used to obtain |
3903 | * pools. |
3904 | */ |
3905 | copy_workqueue_attrs(tmp_attrs, new_attrs); |
3906 | |
3907 | /* |
3908 | * CPUs should stay stable across pwq creations and installations. |
3909 | * Pin CPUs, determine the target cpumask for each node and create |
3910 | * pwqs accordingly. |
3911 | */ |
3912 | get_online_cpus(); |
3913 | |
3914 | mutex_lock(&wq_pool_mutex); |
3915 | |
3916 | /* |
3917 | * If something goes wrong during CPU up/down, we'll fall back to |
3918 | * the default pwq covering whole @attrs->cpumask. Always create |
3919 | * it even if we don't use it immediately. |
3920 | */ |
3921 | dfl_pwq = alloc_unbound_pwq(wq, new_attrs); |
3922 | if (!dfl_pwq) |
3923 | goto enomem_pwq; |
3924 | |
3925 | for_each_node(node) { |
3926 | if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) { |
3927 | pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); |
3928 | if (!pwq_tbl[node]) |
3929 | goto enomem_pwq; |
3930 | } else { |
3931 | dfl_pwq->refcnt++; |
3932 | pwq_tbl[node] = dfl_pwq; |
3933 | } |
3934 | } |
3935 | |
3936 | mutex_unlock(&wq_pool_mutex); |
3937 | |
3938 | /* all pwqs have been created successfully, let's install'em */ |
3939 | mutex_lock(&wq->mutex); |
3940 | |
3941 | copy_workqueue_attrs(wq->unbound_attrs, new_attrs); |
3942 | |
3943 | /* save the previous pwq and install the new one */ |
3944 | for_each_node(node) |
3945 | pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]); |
3946 | |
3947 | /* @dfl_pwq might not have been used, ensure it's linked */ |
3948 | link_pwq(dfl_pwq); |
3949 | swap(wq->dfl_pwq, dfl_pwq); |
3950 | |
3951 | mutex_unlock(&wq->mutex); |
3952 | |
3953 | /* put the old pwqs */ |
3954 | for_each_node(node) |
3955 | put_pwq_unlocked(pwq_tbl[node]); |
3956 | put_pwq_unlocked(dfl_pwq); |
3957 | |
3958 | put_online_cpus(); |
3959 | ret = 0; |
3960 | /* fall through */ |
3961 | out_free: |
3962 | free_workqueue_attrs(tmp_attrs); |
3963 | free_workqueue_attrs(new_attrs); |
3964 | kfree(pwq_tbl); |
3965 | return ret; |
3966 | |
3967 | enomem_pwq: |
3968 | free_unbound_pwq(dfl_pwq); |
3969 | for_each_node(node) |
3970 | if (pwq_tbl && pwq_tbl[node] != dfl_pwq) |
3971 | free_unbound_pwq(pwq_tbl[node]); |
3972 | mutex_unlock(&wq_pool_mutex); |
3973 | put_online_cpus(); |
3974 | enomem: |
3975 | ret = -ENOMEM; |
3976 | goto out_free; |
3977 | } |
3978 | |
3979 | /** |
3980 | * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug |
3981 | * @wq: the target workqueue |
3982 | * @cpu: the CPU coming up or going down |
3983 | * @online: whether @cpu is coming up or going down |
3984 | * |
3985 | * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and |
3986 | * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of |
3987 | * @wq accordingly. |
3988 | * |
3989 | * If NUMA affinity can't be adjusted due to memory allocation failure, it |
3990 | * falls back to @wq->dfl_pwq which may not be optimal but is always |
3991 | * correct. |
3992 | * |
3993 | * Note that when the last allowed CPU of a NUMA node goes offline for a |
3994 | * workqueue with a cpumask spanning multiple nodes, the workers which were |
3995 | * already executing the work items for the workqueue will lose their CPU |
3996 | * affinity and may execute on any CPU. This is similar to how per-cpu |
3997 | * workqueues behave on CPU_DOWN. If a workqueue user wants strict |
3998 | * affinity, it's the user's responsibility to flush the work item from |
3999 | * CPU_DOWN_PREPARE. |
4000 | */ |
4001 | static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, |
4002 | bool online) |
4003 | { |
4004 | int node = cpu_to_node(cpu); |
4005 | int cpu_off = online ? -1 : cpu; |
4006 | struct pool_workqueue *old_pwq = NULL, *pwq; |
4007 | struct workqueue_attrs *target_attrs; |
4008 | cpumask_t *cpumask; |
4009 | |
4010 | lockdep_assert_held(&wq_pool_mutex); |
4011 | |
4012 | if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND)) |
4013 | return; |
4014 | |
4015 | /* |
4016 | * We don't wanna alloc/free wq_attrs for each wq for each CPU. |
4017 | * Let's use a preallocated one. The following buf is protected by |
4018 | * CPU hotplug exclusion. |
4019 | */ |
4020 | target_attrs = wq_update_unbound_numa_attrs_buf; |
4021 | cpumask = target_attrs->cpumask; |
4022 | |
4023 | mutex_lock(&wq->mutex); |
4024 | if (wq->unbound_attrs->no_numa) |
4025 | goto out_unlock; |
4026 | |
4027 | copy_workqueue_attrs(target_attrs, wq->unbound_attrs); |
4028 | pwq = unbound_pwq_by_node(wq, node); |
4029 | |
4030 | /* |
4031 | * Let's determine what needs to be done. If the target cpumask is |
4032 | * different from wq's, we need to compare it to @pwq's and create |
4033 | * a new one if they don't match. If the target cpumask equals |
4034 | * wq's, the default pwq should be used. If @pwq is already the |
4035 | * default one, nothing to do; otherwise, install the default one. |
4036 | */ |
4037 | if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) { |
4038 | if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) |
4039 | goto out_unlock; |
4040 | } else { |
4041 | if (pwq == wq->dfl_pwq) |
4042 | goto out_unlock; |
4043 | else |
4044 | goto use_dfl_pwq; |
4045 | } |
4046 | |
4047 | mutex_unlock(&wq->mutex); |
4048 | |
4049 | /* create a new pwq */ |
4050 | pwq = alloc_unbound_pwq(wq, target_attrs); |
4051 | if (!pwq) { |
4052 | pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", |
4053 | wq->name); |
4054 | goto out_unlock; |
4055 | } |
4056 | |
4057 | /* |
4058 | * Install the new pwq. As this function is called only from CPU |
4059 | * hotplug callbacks and applying a new attrs is wrapped with |
4060 | * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed |
4061 | * inbetween. |
4062 | */ |
4063 | mutex_lock(&wq->mutex); |
4064 | old_pwq = numa_pwq_tbl_install(wq, node, pwq); |
4065 | goto out_unlock; |
4066 | |
4067 | use_dfl_pwq: |
4068 | spin_lock_irq(&wq->dfl_pwq->pool->lock); |
4069 | get_pwq(wq->dfl_pwq); |
4070 | spin_unlock_irq(&wq->dfl_pwq->pool->lock); |
4071 | old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); |
4072 | out_unlock: |
4073 | mutex_unlock(&wq->mutex); |
4074 | put_pwq_unlocked(old_pwq); |
4075 | } |
4076 | |
4077 | static int alloc_and_link_pwqs(struct workqueue_struct *wq) |
4078 | { |
4079 | bool highpri = wq->flags & WQ_HIGHPRI; |
4080 | int cpu; |
4081 | |
4082 | if (!(wq->flags & WQ_UNBOUND)) { |
4083 | wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); |
4084 | if (!wq->cpu_pwqs) |
4085 | return -ENOMEM; |
4086 | |
4087 | for_each_possible_cpu(cpu) { |
4088 | struct pool_workqueue *pwq = |
4089 | per_cpu_ptr(wq->cpu_pwqs, cpu); |
4090 | struct worker_pool *cpu_pools = |
4091 | per_cpu(cpu_worker_pools, cpu); |
4092 | |
4093 | init_pwq(pwq, wq, &cpu_pools[highpri]); |
4094 | |
4095 | mutex_lock(&wq->mutex); |
4096 | link_pwq(pwq); |
4097 | mutex_unlock(&wq->mutex); |
4098 | } |
4099 | return 0; |
4100 | } else { |
4101 | return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); |
4102 | } |
4103 | } |
4104 | |
4105 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
4106 | const char *name) |
4107 | { |
4108 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
4109 | |
4110 | if (max_active < 1 || max_active > lim) |
4111 | pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", |
4112 | max_active, name, 1, lim); |
4113 | |
4114 | return clamp_val(max_active, 1, lim); |
4115 | } |
4116 | |
4117 | struct workqueue_struct *__alloc_workqueue_key(const char *fmt, |
4118 | unsigned int flags, |
4119 | int max_active, |
4120 | struct lock_class_key *key, |
4121 | const char *lock_name, ...) |
4122 | { |
4123 | size_t tbl_size = 0; |
4124 | va_list args; |
4125 | struct workqueue_struct *wq; |
4126 | struct pool_workqueue *pwq; |
4127 | |
4128 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ |
4129 | if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) |
4130 | flags |= WQ_UNBOUND; |
4131 | |
4132 | /* allocate wq and format name */ |
4133 | if (flags & WQ_UNBOUND) |
4134 | tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]); |
4135 | |
4136 | wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); |
4137 | if (!wq) |
4138 | return NULL; |
4139 | |
4140 | if (flags & WQ_UNBOUND) { |
4141 | wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL); |
4142 | if (!wq->unbound_attrs) |
4143 | goto err_free_wq; |
4144 | } |
4145 | |
4146 | va_start(args, lock_name); |
4147 | vsnprintf(wq->name, sizeof(wq->name), fmt, args); |
4148 | va_end(args); |
4149 | |
4150 | max_active = max_active ?: WQ_DFL_ACTIVE; |
4151 | max_active = wq_clamp_max_active(max_active, flags, wq->name); |
4152 | |
4153 | /* init wq */ |
4154 | wq->flags = flags; |
4155 | wq->saved_max_active = max_active; |
4156 | mutex_init(&wq->mutex); |
4157 | atomic_set(&wq->nr_pwqs_to_flush, 0); |
4158 | INIT_LIST_HEAD(&wq->pwqs); |
4159 | INIT_LIST_HEAD(&wq->flusher_queue); |
4160 | INIT_LIST_HEAD(&wq->flusher_overflow); |
4161 | INIT_LIST_HEAD(&wq->maydays); |
4162 | |
4163 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
4164 | INIT_LIST_HEAD(&wq->list); |
4165 | |
4166 | if (alloc_and_link_pwqs(wq) < 0) |
4167 | goto err_free_wq; |
4168 | |
4169 | /* |
4170 | * Workqueues which may be used during memory reclaim should |
4171 | * have a rescuer to guarantee forward progress. |
4172 | */ |
4173 | if (flags & WQ_MEM_RECLAIM) { |
4174 | struct worker *rescuer; |
4175 | |
4176 | rescuer = alloc_worker(); |
4177 | if (!rescuer) |
4178 | goto err_destroy; |
4179 | |
4180 | rescuer->rescue_wq = wq; |
4181 | rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", |
4182 | wq->name); |
4183 | if (IS_ERR(rescuer->task)) { |
4184 | kfree(rescuer); |
4185 | goto err_destroy; |
4186 | } |
4187 | |
4188 | wq->rescuer = rescuer; |
4189 | rescuer->task->flags |= PF_NO_SETAFFINITY; |
4190 | wake_up_process(rescuer->task); |
4191 | } |
4192 | |
4193 | if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) |
4194 | goto err_destroy; |
4195 | |
4196 | /* |
4197 | * wq_pool_mutex protects global freeze state and workqueues list. |
4198 | * Grab it, adjust max_active and add the new @wq to workqueues |
4199 | * list. |
4200 | */ |
4201 | mutex_lock(&wq_pool_mutex); |
4202 | |
4203 | mutex_lock(&wq->mutex); |
4204 | for_each_pwq(pwq, wq) |
4205 | pwq_adjust_max_active(pwq); |
4206 | mutex_unlock(&wq->mutex); |
4207 | |
4208 | list_add(&wq->list, &workqueues); |
4209 | |
4210 | mutex_unlock(&wq_pool_mutex); |
4211 | |
4212 | return wq; |
4213 | |
4214 | err_free_wq: |
4215 | free_workqueue_attrs(wq->unbound_attrs); |
4216 | kfree(wq); |
4217 | return NULL; |
4218 | err_destroy: |
4219 | destroy_workqueue(wq); |
4220 | return NULL; |
4221 | } |
4222 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
4223 | |
4224 | /** |
4225 | * destroy_workqueue - safely terminate a workqueue |
4226 | * @wq: target workqueue |
4227 | * |
4228 | * Safely destroy a workqueue. All work currently pending will be done first. |
4229 | */ |
4230 | void destroy_workqueue(struct workqueue_struct *wq) |
4231 | { |
4232 | struct pool_workqueue *pwq; |
4233 | int node; |
4234 | |
4235 | /* drain it before proceeding with destruction */ |
4236 | drain_workqueue(wq); |
4237 | |
4238 | /* sanity checks */ |
4239 | mutex_lock(&wq->mutex); |
4240 | for_each_pwq(pwq, wq) { |
4241 | int i; |
4242 | |
4243 | for (i = 0; i < WORK_NR_COLORS; i++) { |
4244 | if (WARN_ON(pwq->nr_in_flight[i])) { |
4245 | mutex_unlock(&wq->mutex); |
4246 | return; |
4247 | } |
4248 | } |
4249 | |
4250 | if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) || |
4251 | WARN_ON(pwq->nr_active) || |
4252 | WARN_ON(!list_empty(&pwq->delayed_works))) { |
4253 | mutex_unlock(&wq->mutex); |
4254 | return; |
4255 | } |
4256 | } |
4257 | mutex_unlock(&wq->mutex); |
4258 | |
4259 | /* |
4260 | * wq list is used to freeze wq, remove from list after |
4261 | * flushing is complete in case freeze races us. |
4262 | */ |
4263 | mutex_lock(&wq_pool_mutex); |
4264 | list_del_init(&wq->list); |
4265 | mutex_unlock(&wq_pool_mutex); |
4266 | |
4267 | workqueue_sysfs_unregister(wq); |
4268 | |
4269 | if (wq->rescuer) { |
4270 | kthread_stop(wq->rescuer->task); |
4271 | kfree(wq->rescuer); |
4272 | wq->rescuer = NULL; |
4273 | } |
4274 | |
4275 | if (!(wq->flags & WQ_UNBOUND)) { |
4276 | /* |
4277 | * The base ref is never dropped on per-cpu pwqs. Directly |
4278 | * free the pwqs and wq. |
4279 | */ |
4280 | free_percpu(wq->cpu_pwqs); |
4281 | kfree(wq); |
4282 | } else { |
4283 | /* |
4284 | * We're the sole accessor of @wq at this point. Directly |
4285 | * access numa_pwq_tbl[] and dfl_pwq to put the base refs. |
4286 | * @wq will be freed when the last pwq is released. |
4287 | */ |
4288 | for_each_node(node) { |
4289 | pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); |
4290 | RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); |
4291 | put_pwq_unlocked(pwq); |
4292 | } |
4293 | |
4294 | /* |
4295 | * Put dfl_pwq. @wq may be freed any time after dfl_pwq is |
4296 | * put. Don't access it afterwards. |
4297 | */ |
4298 | pwq = wq->dfl_pwq; |
4299 | wq->dfl_pwq = NULL; |
4300 | put_pwq_unlocked(pwq); |
4301 | } |
4302 | } |
4303 | EXPORT_SYMBOL_GPL(destroy_workqueue); |
4304 | |
4305 | /** |
4306 | * workqueue_set_max_active - adjust max_active of a workqueue |
4307 | * @wq: target workqueue |
4308 | * @max_active: new max_active value. |
4309 | * |
4310 | * Set max_active of @wq to @max_active. |
4311 | * |
4312 | * CONTEXT: |
4313 | * Don't call from IRQ context. |
4314 | */ |
4315 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
4316 | { |
4317 | struct pool_workqueue *pwq; |
4318 | |
4319 | /* disallow meddling with max_active for ordered workqueues */ |
4320 | if (WARN_ON(wq->flags & __WQ_ORDERED)) |
4321 | return; |
4322 | |
4323 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
4324 | |
4325 | mutex_lock(&wq->mutex); |
4326 | |
4327 | wq->saved_max_active = max_active; |
4328 | |
4329 | for_each_pwq(pwq, wq) |
4330 | pwq_adjust_max_active(pwq); |
4331 | |
4332 | mutex_unlock(&wq->mutex); |
4333 | } |
4334 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
4335 | |
4336 | /** |
4337 | * current_is_workqueue_rescuer - is %current workqueue rescuer? |
4338 | * |
4339 | * Determine whether %current is a workqueue rescuer. Can be used from |
4340 | * work functions to determine whether it's being run off the rescuer task. |
4341 | */ |
4342 | bool current_is_workqueue_rescuer(void) |
4343 | { |
4344 | struct worker *worker = current_wq_worker(); |
4345 | |
4346 | return worker && worker->rescue_wq; |
4347 | } |
4348 | |
4349 | /** |
4350 | * workqueue_congested - test whether a workqueue is congested |
4351 | * @cpu: CPU in question |
4352 | * @wq: target workqueue |
4353 | * |
4354 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
4355 | * no synchronization around this function and the test result is |
4356 | * unreliable and only useful as advisory hints or for debugging. |
4357 | * |
4358 | * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. |
4359 | * Note that both per-cpu and unbound workqueues may be associated with |
4360 | * multiple pool_workqueues which have separate congested states. A |
4361 | * workqueue being congested on one CPU doesn't mean the workqueue is also |
4362 | * contested on other CPUs / NUMA nodes. |
4363 | * |
4364 | * RETURNS: |
4365 | * %true if congested, %false otherwise. |
4366 | */ |
4367 | bool workqueue_congested(int cpu, struct workqueue_struct *wq) |
4368 | { |
4369 | struct pool_workqueue *pwq; |
4370 | bool ret; |
4371 | |
4372 | rcu_read_lock_sched(); |
4373 | |
4374 | if (cpu == WORK_CPU_UNBOUND) |
4375 | cpu = smp_processor_id(); |
4376 | |
4377 | if (!(wq->flags & WQ_UNBOUND)) |
4378 | pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); |
4379 | else |
4380 | pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); |
4381 | |
4382 | ret = !list_empty(&pwq->delayed_works); |
4383 | rcu_read_unlock_sched(); |
4384 | |
4385 | return ret; |
4386 | } |
4387 | EXPORT_SYMBOL_GPL(workqueue_congested); |
4388 | |
4389 | /** |
4390 | * work_busy - test whether a work is currently pending or running |
4391 | * @work: the work to be tested |
4392 | * |
4393 | * Test whether @work is currently pending or running. There is no |
4394 | * synchronization around this function and the test result is |
4395 | * unreliable and only useful as advisory hints or for debugging. |
4396 | * |
4397 | * RETURNS: |
4398 | * OR'd bitmask of WORK_BUSY_* bits. |
4399 | */ |
4400 | unsigned int work_busy(struct work_struct *work) |
4401 | { |
4402 | struct worker_pool *pool; |
4403 | unsigned long flags; |
4404 | unsigned int ret = 0; |
4405 | |
4406 | if (work_pending(work)) |
4407 | ret |= WORK_BUSY_PENDING; |
4408 | |
4409 | local_irq_save(flags); |
4410 | pool = get_work_pool(work); |
4411 | if (pool) { |
4412 | spin_lock(&pool->lock); |
4413 | if (find_worker_executing_work(pool, work)) |
4414 | ret |= WORK_BUSY_RUNNING; |
4415 | spin_unlock(&pool->lock); |
4416 | } |
4417 | local_irq_restore(flags); |
4418 | |
4419 | return ret; |
4420 | } |
4421 | EXPORT_SYMBOL_GPL(work_busy); |
4422 | |
4423 | /** |
4424 | * set_worker_desc - set description for the current work item |
4425 | * @fmt: printf-style format string |
4426 | * @...: arguments for the format string |
4427 | * |
4428 | * This function can be called by a running work function to describe what |
4429 | * the work item is about. If the worker task gets dumped, this |
4430 | * information will be printed out together to help debugging. The |
4431 | * description can be at most WORKER_DESC_LEN including the trailing '\0'. |
4432 | */ |
4433 | void set_worker_desc(const char *fmt, ...) |
4434 | { |
4435 | struct worker *worker = current_wq_worker(); |
4436 | va_list args; |
4437 | |
4438 | if (worker) { |
4439 | va_start(args, fmt); |
4440 | vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); |
4441 | va_end(args); |
4442 | worker->desc_valid = true; |
4443 | } |
4444 | } |
4445 | |
4446 | /** |
4447 | * print_worker_info - print out worker information and description |
4448 | * @log_lvl: the log level to use when printing |
4449 | * @task: target task |
4450 | * |
4451 | * If @task is a worker and currently executing a work item, print out the |
4452 | * name of the workqueue being serviced and worker description set with |
4453 | * set_worker_desc() by the currently executing work item. |
4454 | * |
4455 | * This function can be safely called on any task as long as the |
4456 | * task_struct itself is accessible. While safe, this function isn't |
4457 | * synchronized and may print out mixups or garbages of limited length. |
4458 | */ |
4459 | void print_worker_info(const char *log_lvl, struct task_struct *task) |
4460 | { |
4461 | work_func_t *fn = NULL; |
4462 | char name[WQ_NAME_LEN] = { }; |
4463 | char desc[WORKER_DESC_LEN] = { }; |
4464 | struct pool_workqueue *pwq = NULL; |
4465 | struct workqueue_struct *wq = NULL; |
4466 | bool desc_valid = false; |
4467 | struct worker *worker; |
4468 | |
4469 | if (!(task->flags & PF_WQ_WORKER)) |
4470 | return; |
4471 | |
4472 | /* |
4473 | * This function is called without any synchronization and @task |
4474 | * could be in any state. Be careful with dereferences. |
4475 | */ |
4476 | worker = probe_kthread_data(task); |
4477 | |
4478 | /* |
4479 | * Carefully copy the associated workqueue's workfn and name. Keep |
4480 | * the original last '\0' in case the original contains garbage. |
4481 | */ |
4482 | probe_kernel_read(&fn, &worker->current_func, sizeof(fn)); |
4483 | probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); |
4484 | probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); |
4485 | probe_kernel_read(name, wq->name, sizeof(name) - 1); |
4486 | |
4487 | /* copy worker description */ |
4488 | probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid)); |
4489 | if (desc_valid) |
4490 | probe_kernel_read(desc, worker->desc, sizeof(desc) - 1); |
4491 | |
4492 | if (fn || name[0] || desc[0]) { |
4493 | printk("%sWorkqueue: %s %pf", log_lvl, name, fn); |
4494 | if (desc[0]) |
4495 | pr_cont(" (%s)", desc); |
4496 | pr_cont("\n"); |
4497 | } |
4498 | } |
4499 | |
4500 | /* |
4501 | * CPU hotplug. |
4502 | * |
4503 | * There are two challenges in supporting CPU hotplug. Firstly, there |
4504 | * are a lot of assumptions on strong associations among work, pwq and |
4505 | * pool which make migrating pending and scheduled works very |
4506 | * difficult to implement without impacting hot paths. Secondly, |
4507 | * worker pools serve mix of short, long and very long running works making |
4508 | * blocked draining impractical. |
4509 | * |
4510 | * This is solved by allowing the pools to be disassociated from the CPU |
4511 | * running as an unbound one and allowing it to be reattached later if the |
4512 | * cpu comes back online. |
4513 | */ |
4514 | |
4515 | static void wq_unbind_fn(struct work_struct *work) |
4516 | { |
4517 | int cpu = smp_processor_id(); |
4518 | struct worker_pool *pool; |
4519 | struct worker *worker; |
4520 | int wi; |
4521 | |
4522 | for_each_cpu_worker_pool(pool, cpu) { |
4523 | WARN_ON_ONCE(cpu != smp_processor_id()); |
4524 | |
4525 | mutex_lock(&pool->manager_mutex); |
4526 | spin_lock_irq(&pool->lock); |
4527 | |
4528 | /* |
4529 | * We've blocked all manager operations. Make all workers |
4530 | * unbound and set DISASSOCIATED. Before this, all workers |
4531 | * except for the ones which are still executing works from |
4532 | * before the last CPU down must be on the cpu. After |
4533 | * this, they may become diasporas. |
4534 | */ |
4535 | for_each_pool_worker(worker, wi, pool) |
4536 | worker->flags |= WORKER_UNBOUND; |
4537 | |
4538 | pool->flags |= POOL_DISASSOCIATED; |
4539 | |
4540 | spin_unlock_irq(&pool->lock); |
4541 | mutex_unlock(&pool->manager_mutex); |
4542 | |
4543 | /* |
4544 | * Call schedule() so that we cross rq->lock and thus can |
4545 | * guarantee sched callbacks see the %WORKER_UNBOUND flag. |
4546 | * This is necessary as scheduler callbacks may be invoked |
4547 | * from other cpus. |
4548 | */ |
4549 | schedule(); |
4550 | |
4551 | /* |
4552 | * Sched callbacks are disabled now. Zap nr_running. |
4553 | * After this, nr_running stays zero and need_more_worker() |
4554 | * and keep_working() are always true as long as the |
4555 | * worklist is not empty. This pool now behaves as an |
4556 | * unbound (in terms of concurrency management) pool which |
4557 | * are served by workers tied to the pool. |
4558 | */ |
4559 | atomic_set(&pool->nr_running, 0); |
4560 | |
4561 | /* |
4562 | * With concurrency management just turned off, a busy |
4563 | * worker blocking could lead to lengthy stalls. Kick off |
4564 | * unbound chain execution of currently pending work items. |
4565 | */ |
4566 | spin_lock_irq(&pool->lock); |
4567 | wake_up_worker(pool); |
4568 | spin_unlock_irq(&pool->lock); |
4569 | } |
4570 | } |
4571 | |
4572 | /** |
4573 | * rebind_workers - rebind all workers of a pool to the associated CPU |
4574 | * @pool: pool of interest |
4575 | * |
4576 | * @pool->cpu is coming online. Rebind all workers to the CPU. |
4577 | */ |
4578 | static void rebind_workers(struct worker_pool *pool) |
4579 | { |
4580 | struct worker *worker; |
4581 | int wi; |
4582 | |
4583 | lockdep_assert_held(&pool->manager_mutex); |
4584 | |
4585 | /* |
4586 | * Restore CPU affinity of all workers. As all idle workers should |
4587 | * be on the run-queue of the associated CPU before any local |
4588 | * wake-ups for concurrency management happen, restore CPU affinty |
4589 | * of all workers first and then clear UNBOUND. As we're called |
4590 | * from CPU_ONLINE, the following shouldn't fail. |
4591 | */ |
4592 | for_each_pool_worker(worker, wi, pool) |
4593 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, |
4594 | pool->attrs->cpumask) < 0); |
4595 | |
4596 | spin_lock_irq(&pool->lock); |
4597 | |
4598 | for_each_pool_worker(worker, wi, pool) { |
4599 | unsigned int worker_flags = worker->flags; |
4600 | |
4601 | /* |
4602 | * A bound idle worker should actually be on the runqueue |
4603 | * of the associated CPU for local wake-ups targeting it to |
4604 | * work. Kick all idle workers so that they migrate to the |
4605 | * associated CPU. Doing this in the same loop as |
4606 | * replacing UNBOUND with REBOUND is safe as no worker will |
4607 | * be bound before @pool->lock is released. |
4608 | */ |
4609 | if (worker_flags & WORKER_IDLE) |
4610 | wake_up_process(worker->task); |
4611 | |
4612 | /* |
4613 | * We want to clear UNBOUND but can't directly call |
4614 | * worker_clr_flags() or adjust nr_running. Atomically |
4615 | * replace UNBOUND with another NOT_RUNNING flag REBOUND. |
4616 | * @worker will clear REBOUND using worker_clr_flags() when |
4617 | * it initiates the next execution cycle thus restoring |
4618 | * concurrency management. Note that when or whether |
4619 | * @worker clears REBOUND doesn't affect correctness. |
4620 | * |
4621 | * ACCESS_ONCE() is necessary because @worker->flags may be |
4622 | * tested without holding any lock in |
4623 | * wq_worker_waking_up(). Without it, NOT_RUNNING test may |
4624 | * fail incorrectly leading to premature concurrency |
4625 | * management operations. |
4626 | */ |
4627 | WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); |
4628 | worker_flags |= WORKER_REBOUND; |
4629 | worker_flags &= ~WORKER_UNBOUND; |
4630 | ACCESS_ONCE(worker->flags) = worker_flags; |
4631 | } |
4632 | |
4633 | spin_unlock_irq(&pool->lock); |
4634 | } |
4635 | |
4636 | /** |
4637 | * restore_unbound_workers_cpumask - restore cpumask of unbound workers |
4638 | * @pool: unbound pool of interest |
4639 | * @cpu: the CPU which is coming up |
4640 | * |
4641 | * An unbound pool may end up with a cpumask which doesn't have any online |
4642 | * CPUs. When a worker of such pool get scheduled, the scheduler resets |
4643 | * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any |
4644 | * online CPU before, cpus_allowed of all its workers should be restored. |
4645 | */ |
4646 | static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) |
4647 | { |
4648 | static cpumask_t cpumask; |
4649 | struct worker *worker; |
4650 | int wi; |
4651 | |
4652 | lockdep_assert_held(&pool->manager_mutex); |
4653 | |
4654 | /* is @cpu allowed for @pool? */ |
4655 | if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) |
4656 | return; |
4657 | |
4658 | /* is @cpu the only online CPU? */ |
4659 | cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); |
4660 | if (cpumask_weight(&cpumask) != 1) |
4661 | return; |
4662 | |
4663 | /* as we're called from CPU_ONLINE, the following shouldn't fail */ |
4664 | for_each_pool_worker(worker, wi, pool) |
4665 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, |
4666 | pool->attrs->cpumask) < 0); |
4667 | } |
4668 | |
4669 | /* |
4670 | * Workqueues should be brought up before normal priority CPU notifiers. |
4671 | * This will be registered high priority CPU notifier. |
4672 | */ |
4673 | static int workqueue_cpu_up_callback(struct notifier_block *nfb, |
4674 | unsigned long action, |
4675 | void *hcpu) |
4676 | { |
4677 | int cpu = (unsigned long)hcpu; |
4678 | struct worker_pool *pool; |
4679 | struct workqueue_struct *wq; |
4680 | int pi; |
4681 | |
4682 | switch (action & ~CPU_TASKS_FROZEN) { |
4683 | case CPU_UP_PREPARE: |
4684 | for_each_cpu_worker_pool(pool, cpu) { |
4685 | if (pool->nr_workers) |
4686 | continue; |
4687 | if (create_and_start_worker(pool) < 0) |
4688 | return NOTIFY_BAD; |
4689 | } |
4690 | break; |
4691 | |
4692 | case CPU_DOWN_FAILED: |
4693 | case CPU_ONLINE: |
4694 | mutex_lock(&wq_pool_mutex); |
4695 | |
4696 | for_each_pool(pool, pi) { |
4697 | mutex_lock(&pool->manager_mutex); |
4698 | |
4699 | if (pool->cpu == cpu) { |
4700 | spin_lock_irq(&pool->lock); |
4701 | pool->flags &= ~POOL_DISASSOCIATED; |
4702 | spin_unlock_irq(&pool->lock); |
4703 | |
4704 | rebind_workers(pool); |
4705 | } else if (pool->cpu < 0) { |
4706 | restore_unbound_workers_cpumask(pool, cpu); |
4707 | } |
4708 | |
4709 | mutex_unlock(&pool->manager_mutex); |
4710 | } |
4711 | |
4712 | /* update NUMA affinity of unbound workqueues */ |
4713 | list_for_each_entry(wq, &workqueues, list) |
4714 | wq_update_unbound_numa(wq, cpu, true); |
4715 | |
4716 | mutex_unlock(&wq_pool_mutex); |
4717 | break; |
4718 | } |
4719 | return NOTIFY_OK; |
4720 | } |
4721 | |
4722 | /* |
4723 | * Workqueues should be brought down after normal priority CPU notifiers. |
4724 | * This will be registered as low priority CPU notifier. |
4725 | */ |
4726 | static int workqueue_cpu_down_callback(struct notifier_block *nfb, |
4727 | unsigned long action, |
4728 | void *hcpu) |
4729 | { |
4730 | int cpu = (unsigned long)hcpu; |
4731 | struct work_struct unbind_work; |
4732 | struct workqueue_struct *wq; |
4733 | |
4734 | switch (action & ~CPU_TASKS_FROZEN) { |
4735 | case CPU_DOWN_PREPARE: |
4736 | /* unbinding per-cpu workers should happen on the local CPU */ |
4737 | INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn); |
4738 | queue_work_on(cpu, system_highpri_wq, &unbind_work); |
4739 | |
4740 | /* update NUMA affinity of unbound workqueues */ |
4741 | mutex_lock(&wq_pool_mutex); |
4742 | list_for_each_entry(wq, &workqueues, list) |
4743 | wq_update_unbound_numa(wq, cpu, false); |
4744 | mutex_unlock(&wq_pool_mutex); |
4745 | |
4746 | /* wait for per-cpu unbinding to finish */ |
4747 | flush_work(&unbind_work); |
4748 | break; |
4749 | } |
4750 | return NOTIFY_OK; |
4751 | } |
4752 | |
4753 | #ifdef CONFIG_SMP |
4754 | |
4755 | struct work_for_cpu { |
4756 | struct work_struct work; |
4757 | long (*fn)(void *); |
4758 | void *arg; |
4759 | long ret; |
4760 | }; |
4761 | |
4762 | static void work_for_cpu_fn(struct work_struct *work) |
4763 | { |
4764 | struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); |
4765 | |
4766 | wfc->ret = wfc->fn(wfc->arg); |
4767 | } |
4768 | |
4769 | /** |
4770 | * work_on_cpu - run a function in user context on a particular cpu |
4771 | * @cpu: the cpu to run on |
4772 | * @fn: the function to run |
4773 | * @arg: the function arg |
4774 | * |
4775 | * This will return the value @fn returns. |
4776 | * It is up to the caller to ensure that the cpu doesn't go offline. |
4777 | * The caller must not hold any locks which would prevent @fn from completing. |
4778 | */ |
4779 | long work_on_cpu(int cpu, long (*fn)(void *), void *arg) |
4780 | { |
4781 | struct work_for_cpu wfc = { .fn = fn, .arg = arg }; |
4782 | |
4783 | INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); |
4784 | schedule_work_on(cpu, &wfc.work); |
4785 | |
4786 | /* |
4787 | * The work item is on-stack and can't lead to deadlock through |
4788 | * flushing. Use __flush_work() to avoid spurious lockdep warnings |
4789 | * when work_on_cpu()s are nested. |
4790 | */ |
4791 | __flush_work(&wfc.work); |
4792 | |
4793 | return wfc.ret; |
4794 | } |
4795 | EXPORT_SYMBOL_GPL(work_on_cpu); |
4796 | #endif /* CONFIG_SMP */ |
4797 | |
4798 | #ifdef CONFIG_FREEZER |
4799 | |
4800 | /** |
4801 | * freeze_workqueues_begin - begin freezing workqueues |
4802 | * |
4803 | * Start freezing workqueues. After this function returns, all freezable |
4804 | * workqueues will queue new works to their delayed_works list instead of |
4805 | * pool->worklist. |
4806 | * |
4807 | * CONTEXT: |
4808 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. |
4809 | */ |
4810 | void freeze_workqueues_begin(void) |
4811 | { |
4812 | struct worker_pool *pool; |
4813 | struct workqueue_struct *wq; |
4814 | struct pool_workqueue *pwq; |
4815 | int pi; |
4816 | |
4817 | mutex_lock(&wq_pool_mutex); |
4818 | |
4819 | WARN_ON_ONCE(workqueue_freezing); |
4820 | workqueue_freezing = true; |
4821 | |
4822 | /* set FREEZING */ |
4823 | for_each_pool(pool, pi) { |
4824 | spin_lock_irq(&pool->lock); |
4825 | WARN_ON_ONCE(pool->flags & POOL_FREEZING); |
4826 | pool->flags |= POOL_FREEZING; |
4827 | spin_unlock_irq(&pool->lock); |
4828 | } |
4829 | |
4830 | list_for_each_entry(wq, &workqueues, list) { |
4831 | mutex_lock(&wq->mutex); |
4832 | for_each_pwq(pwq, wq) |
4833 | pwq_adjust_max_active(pwq); |
4834 | mutex_unlock(&wq->mutex); |
4835 | } |
4836 | |
4837 | mutex_unlock(&wq_pool_mutex); |
4838 | } |
4839 | |
4840 | /** |
4841 | * freeze_workqueues_busy - are freezable workqueues still busy? |
4842 | * |
4843 | * Check whether freezing is complete. This function must be called |
4844 | * between freeze_workqueues_begin() and thaw_workqueues(). |
4845 | * |
4846 | * CONTEXT: |
4847 | * Grabs and releases wq_pool_mutex. |
4848 | * |
4849 | * RETURNS: |
4850 | * %true if some freezable workqueues are still busy. %false if freezing |
4851 | * is complete. |
4852 | */ |
4853 | bool freeze_workqueues_busy(void) |
4854 | { |
4855 | bool busy = false; |
4856 | struct workqueue_struct *wq; |
4857 | struct pool_workqueue *pwq; |
4858 | |
4859 | mutex_lock(&wq_pool_mutex); |
4860 | |
4861 | WARN_ON_ONCE(!workqueue_freezing); |
4862 | |
4863 | list_for_each_entry(wq, &workqueues, list) { |
4864 | if (!(wq->flags & WQ_FREEZABLE)) |
4865 | continue; |
4866 | /* |
4867 | * nr_active is monotonically decreasing. It's safe |
4868 | * to peek without lock. |
4869 | */ |
4870 | rcu_read_lock_sched(); |
4871 | for_each_pwq(pwq, wq) { |
4872 | WARN_ON_ONCE(pwq->nr_active < 0); |
4873 | if (pwq->nr_active) { |
4874 | busy = true; |
4875 | rcu_read_unlock_sched(); |
4876 | goto out_unlock; |
4877 | } |
4878 | } |
4879 | rcu_read_unlock_sched(); |
4880 | } |
4881 | out_unlock: |
4882 | mutex_unlock(&wq_pool_mutex); |
4883 | return busy; |
4884 | } |
4885 | |
4886 | /** |
4887 | * thaw_workqueues - thaw workqueues |
4888 | * |
4889 | * Thaw workqueues. Normal queueing is restored and all collected |
4890 | * frozen works are transferred to their respective pool worklists. |
4891 | * |
4892 | * CONTEXT: |
4893 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. |
4894 | */ |
4895 | void thaw_workqueues(void) |
4896 | { |
4897 | struct workqueue_struct *wq; |
4898 | struct pool_workqueue *pwq; |
4899 | struct worker_pool *pool; |
4900 | int pi; |
4901 | |
4902 | mutex_lock(&wq_pool_mutex); |
4903 | |
4904 | if (!workqueue_freezing) |
4905 | goto out_unlock; |
4906 | |
4907 | /* clear FREEZING */ |
4908 | for_each_pool(pool, pi) { |
4909 | spin_lock_irq(&pool->lock); |
4910 | WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); |
4911 | pool->flags &= ~POOL_FREEZING; |
4912 | spin_unlock_irq(&pool->lock); |
4913 | } |
4914 | |
4915 | /* restore max_active and repopulate worklist */ |
4916 | list_for_each_entry(wq, &workqueues, list) { |
4917 | mutex_lock(&wq->mutex); |
4918 | for_each_pwq(pwq, wq) |
4919 | pwq_adjust_max_active(pwq); |
4920 | mutex_unlock(&wq->mutex); |
4921 | } |
4922 | |
4923 | workqueue_freezing = false; |
4924 | out_unlock: |
4925 | mutex_unlock(&wq_pool_mutex); |
4926 | } |
4927 | #endif /* CONFIG_FREEZER */ |
4928 | |
4929 | static void __init wq_numa_init(void) |
4930 | { |
4931 | cpumask_var_t *tbl; |
4932 | int node, cpu; |
4933 | |
4934 | /* determine NUMA pwq table len - highest node id + 1 */ |
4935 | for_each_node(node) |
4936 | wq_numa_tbl_len = max(wq_numa_tbl_len, node + 1); |
4937 | |
4938 | if (num_possible_nodes() <= 1) |
4939 | return; |
4940 | |
4941 | if (wq_disable_numa) { |
4942 | pr_info("workqueue: NUMA affinity support disabled\n"); |
4943 | return; |
4944 | } |
4945 | |
4946 | wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL); |
4947 | BUG_ON(!wq_update_unbound_numa_attrs_buf); |
4948 | |
4949 | /* |
4950 | * We want masks of possible CPUs of each node which isn't readily |
4951 | * available. Build one from cpu_to_node() which should have been |
4952 | * fully initialized by now. |
4953 | */ |
4954 | tbl = kzalloc(wq_numa_tbl_len * sizeof(tbl[0]), GFP_KERNEL); |
4955 | BUG_ON(!tbl); |
4956 | |
4957 | for_each_node(node) |
4958 | BUG_ON(!alloc_cpumask_var_node(&tbl[node], GFP_KERNEL, |
4959 | node_online(node) ? node : NUMA_NO_NODE)); |
4960 | |
4961 | for_each_possible_cpu(cpu) { |
4962 | node = cpu_to_node(cpu); |
4963 | if (WARN_ON(node == NUMA_NO_NODE)) { |
4964 | pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); |
4965 | /* happens iff arch is bonkers, let's just proceed */ |
4966 | return; |
4967 | } |
4968 | cpumask_set_cpu(cpu, tbl[node]); |
4969 | } |
4970 | |
4971 | wq_numa_possible_cpumask = tbl; |
4972 | wq_numa_enabled = true; |
4973 | } |
4974 | |
4975 | static int __init init_workqueues(void) |
4976 | { |
4977 | int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; |
4978 | int i, cpu; |
4979 | |
4980 | /* make sure we have enough bits for OFFQ pool ID */ |
4981 | BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) < |
4982 | WORK_CPU_END * NR_STD_WORKER_POOLS); |
4983 | |
4984 | WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); |
4985 | |
4986 | pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); |
4987 | |
4988 | cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); |
4989 | hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); |
4990 | |
4991 | wq_numa_init(); |
4992 | |
4993 | /* initialize CPU pools */ |
4994 | for_each_possible_cpu(cpu) { |
4995 | struct worker_pool *pool; |
4996 | |
4997 | i = 0; |
4998 | for_each_cpu_worker_pool(pool, cpu) { |
4999 | BUG_ON(init_worker_pool(pool)); |
5000 | pool->cpu = cpu; |
5001 | cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); |
5002 | pool->attrs->nice = std_nice[i++]; |
5003 | pool->node = cpu_to_node(cpu); |
5004 | |
5005 | /* alloc pool ID */ |
5006 | mutex_lock(&wq_pool_mutex); |
5007 | BUG_ON(worker_pool_assign_id(pool)); |
5008 | mutex_unlock(&wq_pool_mutex); |
5009 | } |
5010 | } |
5011 | |
5012 | /* create the initial worker */ |
5013 | for_each_online_cpu(cpu) { |
5014 | struct worker_pool *pool; |
5015 | |
5016 | for_each_cpu_worker_pool(pool, cpu) { |
5017 | pool->flags &= ~POOL_DISASSOCIATED; |
5018 | BUG_ON(create_and_start_worker(pool) < 0); |
5019 | } |
5020 | } |
5021 | |
5022 | /* create default unbound wq attrs */ |
5023 | for (i = 0; i < NR_STD_WORKER_POOLS; i++) { |
5024 | struct workqueue_attrs *attrs; |
5025 | |
5026 | BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); |
5027 | attrs->nice = std_nice[i]; |
5028 | unbound_std_wq_attrs[i] = attrs; |
5029 | } |
5030 | |
5031 | system_wq = alloc_workqueue("events", 0, 0); |
5032 | system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); |
5033 | system_long_wq = alloc_workqueue("events_long", 0, 0); |
5034 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
5035 | WQ_UNBOUND_MAX_ACTIVE); |
5036 | system_freezable_wq = alloc_workqueue("events_freezable", |
5037 | WQ_FREEZABLE, 0); |
5038 | system_power_efficient_wq = alloc_workqueue("events_power_efficient", |
5039 | WQ_POWER_EFFICIENT, 0); |
5040 | system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", |
5041 | WQ_FREEZABLE | WQ_POWER_EFFICIENT, |
5042 | 0); |
5043 | BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || |
5044 | !system_unbound_wq || !system_freezable_wq || |
5045 | !system_power_efficient_wq || |
5046 | !system_freezable_power_efficient_wq); |
5047 | return 0; |
5048 | } |
5049 | early_initcall(init_workqueues); |
5050 |
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