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1 | // SPDX-License-Identifier: GPL-2.0-only | |
2 | /* | |
3 | * kernel/workqueue.c - generic async execution with shared worker pool | |
4 | * | |
5 | * Copyright (C) 2002 Ingo Molnar | |
6 | * | |
7 | * Derived from the taskqueue/keventd code by: | |
8 | * David Woodhouse <dwmw2@infradead.org> | |
9 | * Andrew Morton | |
10 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> | |
11 | * Theodore Ts'o <tytso@mit.edu> | |
12 | * | |
13 | * Made to use alloc_percpu by Christoph Lameter. | |
14 | * | |
15 | * Copyright (C) 2010 SUSE Linux Products GmbH | |
16 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> | |
17 | * | |
18 | * This is the generic async execution mechanism. Work items as are | |
19 | * executed in process context. The worker pool is shared and | |
20 | * automatically managed. There are two worker pools for each CPU (one for | |
21 | * normal work items and the other for high priority ones) and some extra | |
22 | * pools for workqueues which are not bound to any specific CPU - the | |
23 | * number of these backing pools is dynamic. | |
24 | * | |
25 | * Please read Documentation/core-api/workqueue.rst for details. | |
26 | */ | |
27 | ||
28 | #include <linux/export.h> | |
29 | #include <linux/kernel.h> | |
30 | #include <linux/sched.h> | |
31 | #include <linux/init.h> | |
32 | #include <linux/signal.h> | |
33 | #include <linux/completion.h> | |
34 | #include <linux/workqueue.h> | |
35 | #include <linux/slab.h> | |
36 | #include <linux/cpu.h> | |
37 | #include <linux/notifier.h> | |
38 | #include <linux/kthread.h> | |
39 | #include <linux/hardirq.h> | |
40 | #include <linux/mempolicy.h> | |
41 | #include <linux/freezer.h> | |
42 | #include <linux/debug_locks.h> | |
43 | #include <linux/lockdep.h> | |
44 | #include <linux/idr.h> | |
45 | #include <linux/jhash.h> | |
46 | #include <linux/hashtable.h> | |
47 | #include <linux/rculist.h> | |
48 | #include <linux/nodemask.h> | |
49 | #include <linux/moduleparam.h> | |
50 | #include <linux/uaccess.h> | |
51 | #include <linux/sched/isolation.h> | |
52 | #include <linux/nmi.h> | |
53 | ||
54 | #include "workqueue_internal.h" | |
55 | ||
56 | enum { | |
57 | /* | |
58 | * worker_pool flags | |
59 | * | |
60 | * A bound pool is either associated or disassociated with its CPU. | |
61 | * While associated (!DISASSOCIATED), all workers are bound to the | |
62 | * CPU and none has %WORKER_UNBOUND set and concurrency management | |
63 | * is in effect. | |
64 | * | |
65 | * While DISASSOCIATED, the cpu may be offline and all workers have | |
66 | * %WORKER_UNBOUND set and concurrency management disabled, and may | |
67 | * be executing on any CPU. The pool behaves as an unbound one. | |
68 | * | |
69 | * Note that DISASSOCIATED should be flipped only while holding | |
70 | * wq_pool_attach_mutex to avoid changing binding state while | |
71 | * worker_attach_to_pool() is in progress. | |
72 | */ | |
73 | POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */ | |
74 | POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ | |
75 | ||
76 | /* worker flags */ | |
77 | WORKER_DIE = 1 << 1, /* die die die */ | |
78 | WORKER_IDLE = 1 << 2, /* is idle */ | |
79 | WORKER_PREP = 1 << 3, /* preparing to run works */ | |
80 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ | |
81 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ | |
82 | WORKER_REBOUND = 1 << 8, /* worker was rebound */ | |
83 | ||
84 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | | |
85 | WORKER_UNBOUND | WORKER_REBOUND, | |
86 | ||
87 | NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ | |
88 | ||
89 | UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ | |
90 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ | |
91 | ||
92 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ | |
93 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ | |
94 | ||
95 | MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, | |
96 | /* call for help after 10ms | |
97 | (min two ticks) */ | |
98 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ | |
99 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ | |
100 | ||
101 | /* | |
102 | * Rescue workers are used only on emergencies and shared by | |
103 | * all cpus. Give MIN_NICE. | |
104 | */ | |
105 | RESCUER_NICE_LEVEL = MIN_NICE, | |
106 | HIGHPRI_NICE_LEVEL = MIN_NICE, | |
107 | ||
108 | WQ_NAME_LEN = 24, | |
109 | }; | |
110 | ||
111 | /* | |
112 | * Structure fields follow one of the following exclusion rules. | |
113 | * | |
114 | * I: Modifiable by initialization/destruction paths and read-only for | |
115 | * everyone else. | |
116 | * | |
117 | * P: Preemption protected. Disabling preemption is enough and should | |
118 | * only be modified and accessed from the local cpu. | |
119 | * | |
120 | * L: pool->lock protected. Access with pool->lock held. | |
121 | * | |
122 | * X: During normal operation, modification requires pool->lock and should | |
123 | * be done only from local cpu. Either disabling preemption on local | |
124 | * cpu or grabbing pool->lock is enough for read access. If | |
125 | * POOL_DISASSOCIATED is set, it's identical to L. | |
126 | * | |
127 | * A: wq_pool_attach_mutex protected. | |
128 | * | |
129 | * PL: wq_pool_mutex protected. | |
130 | * | |
131 | * PR: wq_pool_mutex protected for writes. RCU protected for reads. | |
132 | * | |
133 | * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. | |
134 | * | |
135 | * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or | |
136 | * RCU for reads. | |
137 | * | |
138 | * WQ: wq->mutex protected. | |
139 | * | |
140 | * WR: wq->mutex protected for writes. RCU protected for reads. | |
141 | * | |
142 | * MD: wq_mayday_lock protected. | |
143 | */ | |
144 | ||
145 | /* struct worker is defined in workqueue_internal.h */ | |
146 | ||
147 | struct worker_pool { | |
148 | spinlock_t lock; /* the pool lock */ | |
149 | int cpu; /* I: the associated cpu */ | |
150 | int node; /* I: the associated node ID */ | |
151 | int id; /* I: pool ID */ | |
152 | unsigned int flags; /* X: flags */ | |
153 | ||
154 | unsigned long watchdog_ts; /* L: watchdog timestamp */ | |
155 | ||
156 | struct list_head worklist; /* L: list of pending works */ | |
157 | ||
158 | int nr_workers; /* L: total number of workers */ | |
159 | int nr_idle; /* L: currently idle workers */ | |
160 | ||
161 | struct list_head idle_list; /* X: list of idle workers */ | |
162 | struct timer_list idle_timer; /* L: worker idle timeout */ | |
163 | struct timer_list mayday_timer; /* L: SOS timer for workers */ | |
164 | ||
165 | /* a workers is either on busy_hash or idle_list, or the manager */ | |
166 | DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); | |
167 | /* L: hash of busy workers */ | |
168 | ||
169 | struct worker *manager; /* L: purely informational */ | |
170 | struct list_head workers; /* A: attached workers */ | |
171 | struct completion *detach_completion; /* all workers detached */ | |
172 | ||
173 | struct ida worker_ida; /* worker IDs for task name */ | |
174 | ||
175 | struct workqueue_attrs *attrs; /* I: worker attributes */ | |
176 | struct hlist_node hash_node; /* PL: unbound_pool_hash node */ | |
177 | int refcnt; /* PL: refcnt for unbound pools */ | |
178 | ||
179 | /* | |
180 | * The current concurrency level. As it's likely to be accessed | |
181 | * from other CPUs during try_to_wake_up(), put it in a separate | |
182 | * cacheline. | |
183 | */ | |
184 | atomic_t nr_running ____cacheline_aligned_in_smp; | |
185 | ||
186 | /* | |
187 | * Destruction of pool is RCU protected to allow dereferences | |
188 | * from get_work_pool(). | |
189 | */ | |
190 | struct rcu_head rcu; | |
191 | } ____cacheline_aligned_in_smp; | |
192 | ||
193 | /* | |
194 | * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS | |
195 | * of work_struct->data are used for flags and the remaining high bits | |
196 | * point to the pwq; thus, pwqs need to be aligned at two's power of the | |
197 | * number of flag bits. | |
198 | */ | |
199 | struct pool_workqueue { | |
200 | struct worker_pool *pool; /* I: the associated pool */ | |
201 | struct workqueue_struct *wq; /* I: the owning workqueue */ | |
202 | int work_color; /* L: current color */ | |
203 | int flush_color; /* L: flushing color */ | |
204 | int refcnt; /* L: reference count */ | |
205 | int nr_in_flight[WORK_NR_COLORS]; | |
206 | /* L: nr of in_flight works */ | |
207 | int nr_active; /* L: nr of active works */ | |
208 | int max_active; /* L: max active works */ | |
209 | struct list_head delayed_works; /* L: delayed works */ | |
210 | struct list_head pwqs_node; /* WR: node on wq->pwqs */ | |
211 | struct list_head mayday_node; /* MD: node on wq->maydays */ | |
212 | ||
213 | /* | |
214 | * Release of unbound pwq is punted to system_wq. See put_pwq() | |
215 | * and pwq_unbound_release_workfn() for details. pool_workqueue | |
216 | * itself is also RCU protected so that the first pwq can be | |
217 | * determined without grabbing wq->mutex. | |
218 | */ | |
219 | struct work_struct unbound_release_work; | |
220 | struct rcu_head rcu; | |
221 | } __aligned(1 << WORK_STRUCT_FLAG_BITS); | |
222 | ||
223 | /* | |
224 | * Structure used to wait for workqueue flush. | |
225 | */ | |
226 | struct wq_flusher { | |
227 | struct list_head list; /* WQ: list of flushers */ | |
228 | int flush_color; /* WQ: flush color waiting for */ | |
229 | struct completion done; /* flush completion */ | |
230 | }; | |
231 | ||
232 | struct wq_device; | |
233 | ||
234 | /* | |
235 | * The externally visible workqueue. It relays the issued work items to | |
236 | * the appropriate worker_pool through its pool_workqueues. | |
237 | */ | |
238 | struct workqueue_struct { | |
239 | struct list_head pwqs; /* WR: all pwqs of this wq */ | |
240 | struct list_head list; /* PR: list of all workqueues */ | |
241 | ||
242 | struct mutex mutex; /* protects this wq */ | |
243 | int work_color; /* WQ: current work color */ | |
244 | int flush_color; /* WQ: current flush color */ | |
245 | atomic_t nr_pwqs_to_flush; /* flush in progress */ | |
246 | struct wq_flusher *first_flusher; /* WQ: first flusher */ | |
247 | struct list_head flusher_queue; /* WQ: flush waiters */ | |
248 | struct list_head flusher_overflow; /* WQ: flush overflow list */ | |
249 | ||
250 | struct list_head maydays; /* MD: pwqs requesting rescue */ | |
251 | struct worker *rescuer; /* I: rescue worker */ | |
252 | ||
253 | int nr_drainers; /* WQ: drain in progress */ | |
254 | int saved_max_active; /* WQ: saved pwq max_active */ | |
255 | ||
256 | struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ | |
257 | struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */ | |
258 | ||
259 | #ifdef CONFIG_SYSFS | |
260 | struct wq_device *wq_dev; /* I: for sysfs interface */ | |
261 | #endif | |
262 | #ifdef CONFIG_LOCKDEP | |
263 | char *lock_name; | |
264 | struct lock_class_key key; | |
265 | struct lockdep_map lockdep_map; | |
266 | #endif | |
267 | char name[WQ_NAME_LEN]; /* I: workqueue name */ | |
268 | ||
269 | /* | |
270 | * Destruction of workqueue_struct is RCU protected to allow walking | |
271 | * the workqueues list without grabbing wq_pool_mutex. | |
272 | * This is used to dump all workqueues from sysrq. | |
273 | */ | |
274 | struct rcu_head rcu; | |
275 | ||
276 | /* hot fields used during command issue, aligned to cacheline */ | |
277 | unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ | |
278 | struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ | |
279 | struct pool_workqueue __rcu *numa_pwq_tbl[]; /* PWR: unbound pwqs indexed by node */ | |
280 | }; | |
281 | ||
282 | static struct kmem_cache *pwq_cache; | |
283 | ||
284 | static cpumask_var_t *wq_numa_possible_cpumask; | |
285 | /* possible CPUs of each node */ | |
286 | ||
287 | static bool wq_disable_numa; | |
288 | module_param_named(disable_numa, wq_disable_numa, bool, 0444); | |
289 | ||
290 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ | |
291 | static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); | |
292 | module_param_named(power_efficient, wq_power_efficient, bool, 0444); | |
293 | ||
294 | static bool wq_online; /* can kworkers be created yet? */ | |
295 | ||
296 | static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ | |
297 | ||
298 | /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ | |
299 | static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; | |
300 | ||
301 | static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ | |
302 | static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ | |
303 | static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ | |
304 | static DECLARE_WAIT_QUEUE_HEAD(wq_manager_wait); /* wait for manager to go away */ | |
305 | ||
306 | static LIST_HEAD(workqueues); /* PR: list of all workqueues */ | |
307 | static bool workqueue_freezing; /* PL: have wqs started freezing? */ | |
308 | ||
309 | /* PL: allowable cpus for unbound wqs and work items */ | |
310 | static cpumask_var_t wq_unbound_cpumask; | |
311 | ||
312 | /* CPU where unbound work was last round robin scheduled from this CPU */ | |
313 | static DEFINE_PER_CPU(int, wq_rr_cpu_last); | |
314 | ||
315 | /* | |
316 | * Local execution of unbound work items is no longer guaranteed. The | |
317 | * following always forces round-robin CPU selection on unbound work items | |
318 | * to uncover usages which depend on it. | |
319 | */ | |
320 | #ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU | |
321 | static bool wq_debug_force_rr_cpu = true; | |
322 | #else | |
323 | static bool wq_debug_force_rr_cpu = false; | |
324 | #endif | |
325 | module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); | |
326 | ||
327 | /* the per-cpu worker pools */ | |
328 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); | |
329 | ||
330 | static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ | |
331 | ||
332 | /* PL: hash of all unbound pools keyed by pool->attrs */ | |
333 | static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); | |
334 | ||
335 | /* I: attributes used when instantiating standard unbound pools on demand */ | |
336 | static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; | |
337 | ||
338 | /* I: attributes used when instantiating ordered pools on demand */ | |
339 | static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; | |
340 | ||
341 | struct workqueue_struct *system_wq __read_mostly; | |
342 | EXPORT_SYMBOL(system_wq); | |
343 | struct workqueue_struct *system_highpri_wq __read_mostly; | |
344 | EXPORT_SYMBOL_GPL(system_highpri_wq); | |
345 | struct workqueue_struct *system_long_wq __read_mostly; | |
346 | EXPORT_SYMBOL_GPL(system_long_wq); | |
347 | struct workqueue_struct *system_unbound_wq __read_mostly; | |
348 | EXPORT_SYMBOL_GPL(system_unbound_wq); | |
349 | struct workqueue_struct *system_freezable_wq __read_mostly; | |
350 | EXPORT_SYMBOL_GPL(system_freezable_wq); | |
351 | struct workqueue_struct *system_power_efficient_wq __read_mostly; | |
352 | EXPORT_SYMBOL_GPL(system_power_efficient_wq); | |
353 | struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; | |
354 | EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); | |
355 | ||
356 | static int worker_thread(void *__worker); | |
357 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq); | |
358 | ||
359 | #define CREATE_TRACE_POINTS | |
360 | #include <trace/events/workqueue.h> | |
361 | ||
362 | #define assert_rcu_or_pool_mutex() \ | |
363 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ | |
364 | !lockdep_is_held(&wq_pool_mutex), \ | |
365 | "RCU or wq_pool_mutex should be held") | |
366 | ||
367 | #define assert_rcu_or_wq_mutex(wq) \ | |
368 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ | |
369 | !lockdep_is_held(&wq->mutex), \ | |
370 | "RCU or wq->mutex should be held") | |
371 | ||
372 | #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \ | |
373 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ | |
374 | !lockdep_is_held(&wq->mutex) && \ | |
375 | !lockdep_is_held(&wq_pool_mutex), \ | |
376 | "RCU, wq->mutex or wq_pool_mutex should be held") | |
377 | ||
378 | #define for_each_cpu_worker_pool(pool, cpu) \ | |
379 | for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ | |
380 | (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ | |
381 | (pool)++) | |
382 | ||
383 | /** | |
384 | * for_each_pool - iterate through all worker_pools in the system | |
385 | * @pool: iteration cursor | |
386 | * @pi: integer used for iteration | |
387 | * | |
388 | * This must be called either with wq_pool_mutex held or RCU read | |
389 | * locked. If the pool needs to be used beyond the locking in effect, the | |
390 | * caller is responsible for guaranteeing that the pool stays online. | |
391 | * | |
392 | * The if/else clause exists only for the lockdep assertion and can be | |
393 | * ignored. | |
394 | */ | |
395 | #define for_each_pool(pool, pi) \ | |
396 | idr_for_each_entry(&worker_pool_idr, pool, pi) \ | |
397 | if (({ assert_rcu_or_pool_mutex(); false; })) { } \ | |
398 | else | |
399 | ||
400 | /** | |
401 | * for_each_pool_worker - iterate through all workers of a worker_pool | |
402 | * @worker: iteration cursor | |
403 | * @pool: worker_pool to iterate workers of | |
404 | * | |
405 | * This must be called with wq_pool_attach_mutex. | |
406 | * | |
407 | * The if/else clause exists only for the lockdep assertion and can be | |
408 | * ignored. | |
409 | */ | |
410 | #define for_each_pool_worker(worker, pool) \ | |
411 | list_for_each_entry((worker), &(pool)->workers, node) \ | |
412 | if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \ | |
413 | else | |
414 | ||
415 | /** | |
416 | * for_each_pwq - iterate through all pool_workqueues of the specified workqueue | |
417 | * @pwq: iteration cursor | |
418 | * @wq: the target workqueue | |
419 | * | |
420 | * This must be called either with wq->mutex held or RCU read locked. | |
421 | * If the pwq needs to be used beyond the locking in effect, the caller is | |
422 | * responsible for guaranteeing that the pwq stays online. | |
423 | * | |
424 | * The if/else clause exists only for the lockdep assertion and can be | |
425 | * ignored. | |
426 | */ | |
427 | #define for_each_pwq(pwq, wq) \ | |
428 | list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \ | |
429 | lockdep_is_held(&wq->mutex)) \ | |
430 | if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ | |
431 | else | |
432 | ||
433 | #ifdef CONFIG_DEBUG_OBJECTS_WORK | |
434 | ||
435 | static struct debug_obj_descr work_debug_descr; | |
436 | ||
437 | static void *work_debug_hint(void *addr) | |
438 | { | |
439 | return ((struct work_struct *) addr)->func; | |
440 | } | |
441 | ||
442 | static bool work_is_static_object(void *addr) | |
443 | { | |
444 | struct work_struct *work = addr; | |
445 | ||
446 | return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work)); | |
447 | } | |
448 | ||
449 | /* | |
450 | * fixup_init is called when: | |
451 | * - an active object is initialized | |
452 | */ | |
453 | static bool work_fixup_init(void *addr, enum debug_obj_state state) | |
454 | { | |
455 | struct work_struct *work = addr; | |
456 | ||
457 | switch (state) { | |
458 | case ODEBUG_STATE_ACTIVE: | |
459 | cancel_work_sync(work); | |
460 | debug_object_init(work, &work_debug_descr); | |
461 | return true; | |
462 | default: | |
463 | return false; | |
464 | } | |
465 | } | |
466 | ||
467 | /* | |
468 | * fixup_free is called when: | |
469 | * - an active object is freed | |
470 | */ | |
471 | static bool work_fixup_free(void *addr, enum debug_obj_state state) | |
472 | { | |
473 | struct work_struct *work = addr; | |
474 | ||
475 | switch (state) { | |
476 | case ODEBUG_STATE_ACTIVE: | |
477 | cancel_work_sync(work); | |
478 | debug_object_free(work, &work_debug_descr); | |
479 | return true; | |
480 | default: | |
481 | return false; | |
482 | } | |
483 | } | |
484 | ||
485 | static struct debug_obj_descr work_debug_descr = { | |
486 | .name = "work_struct", | |
487 | .debug_hint = work_debug_hint, | |
488 | .is_static_object = work_is_static_object, | |
489 | .fixup_init = work_fixup_init, | |
490 | .fixup_free = work_fixup_free, | |
491 | }; | |
492 | ||
493 | static inline void debug_work_activate(struct work_struct *work) | |
494 | { | |
495 | debug_object_activate(work, &work_debug_descr); | |
496 | } | |
497 | ||
498 | static inline void debug_work_deactivate(struct work_struct *work) | |
499 | { | |
500 | debug_object_deactivate(work, &work_debug_descr); | |
501 | } | |
502 | ||
503 | void __init_work(struct work_struct *work, int onstack) | |
504 | { | |
505 | if (onstack) | |
506 | debug_object_init_on_stack(work, &work_debug_descr); | |
507 | else | |
508 | debug_object_init(work, &work_debug_descr); | |
509 | } | |
510 | EXPORT_SYMBOL_GPL(__init_work); | |
511 | ||
512 | void destroy_work_on_stack(struct work_struct *work) | |
513 | { | |
514 | debug_object_free(work, &work_debug_descr); | |
515 | } | |
516 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); | |
517 | ||
518 | void destroy_delayed_work_on_stack(struct delayed_work *work) | |
519 | { | |
520 | destroy_timer_on_stack(&work->timer); | |
521 | debug_object_free(&work->work, &work_debug_descr); | |
522 | } | |
523 | EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); | |
524 | ||
525 | #else | |
526 | static inline void debug_work_activate(struct work_struct *work) { } | |
527 | static inline void debug_work_deactivate(struct work_struct *work) { } | |
528 | #endif | |
529 | ||
530 | /** | |
531 | * worker_pool_assign_id - allocate ID and assing it to @pool | |
532 | * @pool: the pool pointer of interest | |
533 | * | |
534 | * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned | |
535 | * successfully, -errno on failure. | |
536 | */ | |
537 | static int worker_pool_assign_id(struct worker_pool *pool) | |
538 | { | |
539 | int ret; | |
540 | ||
541 | lockdep_assert_held(&wq_pool_mutex); | |
542 | ||
543 | ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, | |
544 | GFP_KERNEL); | |
545 | if (ret >= 0) { | |
546 | pool->id = ret; | |
547 | return 0; | |
548 | } | |
549 | return ret; | |
550 | } | |
551 | ||
552 | /** | |
553 | * unbound_pwq_by_node - return the unbound pool_workqueue for the given node | |
554 | * @wq: the target workqueue | |
555 | * @node: the node ID | |
556 | * | |
557 | * This must be called with any of wq_pool_mutex, wq->mutex or RCU | |
558 | * read locked. | |
559 | * If the pwq needs to be used beyond the locking in effect, the caller is | |
560 | * responsible for guaranteeing that the pwq stays online. | |
561 | * | |
562 | * Return: The unbound pool_workqueue for @node. | |
563 | */ | |
564 | static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, | |
565 | int node) | |
566 | { | |
567 | assert_rcu_or_wq_mutex_or_pool_mutex(wq); | |
568 | ||
569 | /* | |
570 | * XXX: @node can be NUMA_NO_NODE if CPU goes offline while a | |
571 | * delayed item is pending. The plan is to keep CPU -> NODE | |
572 | * mapping valid and stable across CPU on/offlines. Once that | |
573 | * happens, this workaround can be removed. | |
574 | */ | |
575 | if (unlikely(node == NUMA_NO_NODE)) | |
576 | return wq->dfl_pwq; | |
577 | ||
578 | return rcu_dereference_raw(wq->numa_pwq_tbl[node]); | |
579 | } | |
580 | ||
581 | static unsigned int work_color_to_flags(int color) | |
582 | { | |
583 | return color << WORK_STRUCT_COLOR_SHIFT; | |
584 | } | |
585 | ||
586 | static int get_work_color(struct work_struct *work) | |
587 | { | |
588 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & | |
589 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); | |
590 | } | |
591 | ||
592 | static int work_next_color(int color) | |
593 | { | |
594 | return (color + 1) % WORK_NR_COLORS; | |
595 | } | |
596 | ||
597 | /* | |
598 | * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data | |
599 | * contain the pointer to the queued pwq. Once execution starts, the flag | |
600 | * is cleared and the high bits contain OFFQ flags and pool ID. | |
601 | * | |
602 | * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() | |
603 | * and clear_work_data() can be used to set the pwq, pool or clear | |
604 | * work->data. These functions should only be called while the work is | |
605 | * owned - ie. while the PENDING bit is set. | |
606 | * | |
607 | * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq | |
608 | * corresponding to a work. Pool is available once the work has been | |
609 | * queued anywhere after initialization until it is sync canceled. pwq is | |
610 | * available only while the work item is queued. | |
611 | * | |
612 | * %WORK_OFFQ_CANCELING is used to mark a work item which is being | |
613 | * canceled. While being canceled, a work item may have its PENDING set | |
614 | * but stay off timer and worklist for arbitrarily long and nobody should | |
615 | * try to steal the PENDING bit. | |
616 | */ | |
617 | static inline void set_work_data(struct work_struct *work, unsigned long data, | |
618 | unsigned long flags) | |
619 | { | |
620 | WARN_ON_ONCE(!work_pending(work)); | |
621 | atomic_long_set(&work->data, data | flags | work_static(work)); | |
622 | } | |
623 | ||
624 | static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, | |
625 | unsigned long extra_flags) | |
626 | { | |
627 | set_work_data(work, (unsigned long)pwq, | |
628 | WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); | |
629 | } | |
630 | ||
631 | static void set_work_pool_and_keep_pending(struct work_struct *work, | |
632 | int pool_id) | |
633 | { | |
634 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, | |
635 | WORK_STRUCT_PENDING); | |
636 | } | |
637 | ||
638 | static void set_work_pool_and_clear_pending(struct work_struct *work, | |
639 | int pool_id) | |
640 | { | |
641 | /* | |
642 | * The following wmb is paired with the implied mb in | |
643 | * test_and_set_bit(PENDING) and ensures all updates to @work made | |
644 | * here are visible to and precede any updates by the next PENDING | |
645 | * owner. | |
646 | */ | |
647 | smp_wmb(); | |
648 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); | |
649 | /* | |
650 | * The following mb guarantees that previous clear of a PENDING bit | |
651 | * will not be reordered with any speculative LOADS or STORES from | |
652 | * work->current_func, which is executed afterwards. This possible | |
653 | * reordering can lead to a missed execution on attempt to queue | |
654 | * the same @work. E.g. consider this case: | |
655 | * | |
656 | * CPU#0 CPU#1 | |
657 | * ---------------------------- -------------------------------- | |
658 | * | |
659 | * 1 STORE event_indicated | |
660 | * 2 queue_work_on() { | |
661 | * 3 test_and_set_bit(PENDING) | |
662 | * 4 } set_..._and_clear_pending() { | |
663 | * 5 set_work_data() # clear bit | |
664 | * 6 smp_mb() | |
665 | * 7 work->current_func() { | |
666 | * 8 LOAD event_indicated | |
667 | * } | |
668 | * | |
669 | * Without an explicit full barrier speculative LOAD on line 8 can | |
670 | * be executed before CPU#0 does STORE on line 1. If that happens, | |
671 | * CPU#0 observes the PENDING bit is still set and new execution of | |
672 | * a @work is not queued in a hope, that CPU#1 will eventually | |
673 | * finish the queued @work. Meanwhile CPU#1 does not see | |
674 | * event_indicated is set, because speculative LOAD was executed | |
675 | * before actual STORE. | |
676 | */ | |
677 | smp_mb(); | |
678 | } | |
679 | ||
680 | static void clear_work_data(struct work_struct *work) | |
681 | { | |
682 | smp_wmb(); /* see set_work_pool_and_clear_pending() */ | |
683 | set_work_data(work, WORK_STRUCT_NO_POOL, 0); | |
684 | } | |
685 | ||
686 | static struct pool_workqueue *get_work_pwq(struct work_struct *work) | |
687 | { | |
688 | unsigned long data = atomic_long_read(&work->data); | |
689 | ||
690 | if (data & WORK_STRUCT_PWQ) | |
691 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); | |
692 | else | |
693 | return NULL; | |
694 | } | |
695 | ||
696 | /** | |
697 | * get_work_pool - return the worker_pool a given work was associated with | |
698 | * @work: the work item of interest | |
699 | * | |
700 | * Pools are created and destroyed under wq_pool_mutex, and allows read | |
701 | * access under RCU read lock. As such, this function should be | |
702 | * called under wq_pool_mutex or inside of a rcu_read_lock() region. | |
703 | * | |
704 | * All fields of the returned pool are accessible as long as the above | |
705 | * mentioned locking is in effect. If the returned pool needs to be used | |
706 | * beyond the critical section, the caller is responsible for ensuring the | |
707 | * returned pool is and stays online. | |
708 | * | |
709 | * Return: The worker_pool @work was last associated with. %NULL if none. | |
710 | */ | |
711 | static struct worker_pool *get_work_pool(struct work_struct *work) | |
712 | { | |
713 | unsigned long data = atomic_long_read(&work->data); | |
714 | int pool_id; | |
715 | ||
716 | assert_rcu_or_pool_mutex(); | |
717 | ||
718 | if (data & WORK_STRUCT_PWQ) | |
719 | return ((struct pool_workqueue *) | |
720 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool; | |
721 | ||
722 | pool_id = data >> WORK_OFFQ_POOL_SHIFT; | |
723 | if (pool_id == WORK_OFFQ_POOL_NONE) | |
724 | return NULL; | |
725 | ||
726 | return idr_find(&worker_pool_idr, pool_id); | |
727 | } | |
728 | ||
729 | /** | |
730 | * get_work_pool_id - return the worker pool ID a given work is associated with | |
731 | * @work: the work item of interest | |
732 | * | |
733 | * Return: The worker_pool ID @work was last associated with. | |
734 | * %WORK_OFFQ_POOL_NONE if none. | |
735 | */ | |
736 | static int get_work_pool_id(struct work_struct *work) | |
737 | { | |
738 | unsigned long data = atomic_long_read(&work->data); | |
739 | ||
740 | if (data & WORK_STRUCT_PWQ) | |
741 | return ((struct pool_workqueue *) | |
742 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; | |
743 | ||
744 | return data >> WORK_OFFQ_POOL_SHIFT; | |
745 | } | |
746 | ||
747 | static void mark_work_canceling(struct work_struct *work) | |
748 | { | |
749 | unsigned long pool_id = get_work_pool_id(work); | |
750 | ||
751 | pool_id <<= WORK_OFFQ_POOL_SHIFT; | |
752 | set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); | |
753 | } | |
754 | ||
755 | static bool work_is_canceling(struct work_struct *work) | |
756 | { | |
757 | unsigned long data = atomic_long_read(&work->data); | |
758 | ||
759 | return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); | |
760 | } | |
761 | ||
762 | /* | |
763 | * Policy functions. These define the policies on how the global worker | |
764 | * pools are managed. Unless noted otherwise, these functions assume that | |
765 | * they're being called with pool->lock held. | |
766 | */ | |
767 | ||
768 | static bool __need_more_worker(struct worker_pool *pool) | |
769 | { | |
770 | return !atomic_read(&pool->nr_running); | |
771 | } | |
772 | ||
773 | /* | |
774 | * Need to wake up a worker? Called from anything but currently | |
775 | * running workers. | |
776 | * | |
777 | * Note that, because unbound workers never contribute to nr_running, this | |
778 | * function will always return %true for unbound pools as long as the | |
779 | * worklist isn't empty. | |
780 | */ | |
781 | static bool need_more_worker(struct worker_pool *pool) | |
782 | { | |
783 | return !list_empty(&pool->worklist) && __need_more_worker(pool); | |
784 | } | |
785 | ||
786 | /* Can I start working? Called from busy but !running workers. */ | |
787 | static bool may_start_working(struct worker_pool *pool) | |
788 | { | |
789 | return pool->nr_idle; | |
790 | } | |
791 | ||
792 | /* Do I need to keep working? Called from currently running workers. */ | |
793 | static bool keep_working(struct worker_pool *pool) | |
794 | { | |
795 | return !list_empty(&pool->worklist) && | |
796 | atomic_read(&pool->nr_running) <= 1; | |
797 | } | |
798 | ||
799 | /* Do we need a new worker? Called from manager. */ | |
800 | static bool need_to_create_worker(struct worker_pool *pool) | |
801 | { | |
802 | return need_more_worker(pool) && !may_start_working(pool); | |
803 | } | |
804 | ||
805 | /* Do we have too many workers and should some go away? */ | |
806 | static bool too_many_workers(struct worker_pool *pool) | |
807 | { | |
808 | bool managing = pool->flags & POOL_MANAGER_ACTIVE; | |
809 | int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ | |
810 | int nr_busy = pool->nr_workers - nr_idle; | |
811 | ||
812 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; | |
813 | } | |
814 | ||
815 | /* | |
816 | * Wake up functions. | |
817 | */ | |
818 | ||
819 | /* Return the first idle worker. Safe with preemption disabled */ | |
820 | static struct worker *first_idle_worker(struct worker_pool *pool) | |
821 | { | |
822 | if (unlikely(list_empty(&pool->idle_list))) | |
823 | return NULL; | |
824 | ||
825 | return list_first_entry(&pool->idle_list, struct worker, entry); | |
826 | } | |
827 | ||
828 | /** | |
829 | * wake_up_worker - wake up an idle worker | |
830 | * @pool: worker pool to wake worker from | |
831 | * | |
832 | * Wake up the first idle worker of @pool. | |
833 | * | |
834 | * CONTEXT: | |
835 | * spin_lock_irq(pool->lock). | |
836 | */ | |
837 | static void wake_up_worker(struct worker_pool *pool) | |
838 | { | |
839 | struct worker *worker = first_idle_worker(pool); | |
840 | ||
841 | if (likely(worker)) | |
842 | wake_up_process(worker->task); | |
843 | } | |
844 | ||
845 | /** | |
846 | * wq_worker_running - a worker is running again | |
847 | * @task: task waking up | |
848 | * | |
849 | * This function is called when a worker returns from schedule() | |
850 | */ | |
851 | void wq_worker_running(struct task_struct *task) | |
852 | { | |
853 | struct worker *worker = kthread_data(task); | |
854 | ||
855 | if (!worker->sleeping) | |
856 | return; | |
857 | if (!(worker->flags & WORKER_NOT_RUNNING)) | |
858 | atomic_inc(&worker->pool->nr_running); | |
859 | worker->sleeping = 0; | |
860 | } | |
861 | ||
862 | /** | |
863 | * wq_worker_sleeping - a worker is going to sleep | |
864 | * @task: task going to sleep | |
865 | * | |
866 | * This function is called from schedule() when a busy worker is | |
867 | * going to sleep. | |
868 | */ | |
869 | void wq_worker_sleeping(struct task_struct *task) | |
870 | { | |
871 | struct worker *next, *worker = kthread_data(task); | |
872 | struct worker_pool *pool; | |
873 | ||
874 | /* | |
875 | * Rescuers, which may not have all the fields set up like normal | |
876 | * workers, also reach here, let's not access anything before | |
877 | * checking NOT_RUNNING. | |
878 | */ | |
879 | if (worker->flags & WORKER_NOT_RUNNING) | |
880 | return; | |
881 | ||
882 | pool = worker->pool; | |
883 | ||
884 | if (WARN_ON_ONCE(worker->sleeping)) | |
885 | return; | |
886 | ||
887 | worker->sleeping = 1; | |
888 | spin_lock_irq(&pool->lock); | |
889 | ||
890 | /* | |
891 | * The counterpart of the following dec_and_test, implied mb, | |
892 | * worklist not empty test sequence is in insert_work(). | |
893 | * Please read comment there. | |
894 | * | |
895 | * NOT_RUNNING is clear. This means that we're bound to and | |
896 | * running on the local cpu w/ rq lock held and preemption | |
897 | * disabled, which in turn means that none else could be | |
898 | * manipulating idle_list, so dereferencing idle_list without pool | |
899 | * lock is safe. | |
900 | */ | |
901 | if (atomic_dec_and_test(&pool->nr_running) && | |
902 | !list_empty(&pool->worklist)) { | |
903 | next = first_idle_worker(pool); | |
904 | if (next) | |
905 | wake_up_process(next->task); | |
906 | } | |
907 | spin_unlock_irq(&pool->lock); | |
908 | } | |
909 | ||
910 | /** | |
911 | * wq_worker_last_func - retrieve worker's last work function | |
912 | * @task: Task to retrieve last work function of. | |
913 | * | |
914 | * Determine the last function a worker executed. This is called from | |
915 | * the scheduler to get a worker's last known identity. | |
916 | * | |
917 | * CONTEXT: | |
918 | * spin_lock_irq(rq->lock) | |
919 | * | |
920 | * This function is called during schedule() when a kworker is going | |
921 | * to sleep. It's used by psi to identify aggregation workers during | |
922 | * dequeuing, to allow periodic aggregation to shut-off when that | |
923 | * worker is the last task in the system or cgroup to go to sleep. | |
924 | * | |
925 | * As this function doesn't involve any workqueue-related locking, it | |
926 | * only returns stable values when called from inside the scheduler's | |
927 | * queuing and dequeuing paths, when @task, which must be a kworker, | |
928 | * is guaranteed to not be processing any works. | |
929 | * | |
930 | * Return: | |
931 | * The last work function %current executed as a worker, NULL if it | |
932 | * hasn't executed any work yet. | |
933 | */ | |
934 | work_func_t wq_worker_last_func(struct task_struct *task) | |
935 | { | |
936 | struct worker *worker = kthread_data(task); | |
937 | ||
938 | return worker->last_func; | |
939 | } | |
940 | ||
941 | /** | |
942 | * worker_set_flags - set worker flags and adjust nr_running accordingly | |
943 | * @worker: self | |
944 | * @flags: flags to set | |
945 | * | |
946 | * Set @flags in @worker->flags and adjust nr_running accordingly. | |
947 | * | |
948 | * CONTEXT: | |
949 | * spin_lock_irq(pool->lock) | |
950 | */ | |
951 | static inline void worker_set_flags(struct worker *worker, unsigned int flags) | |
952 | { | |
953 | struct worker_pool *pool = worker->pool; | |
954 | ||
955 | WARN_ON_ONCE(worker->task != current); | |
956 | ||
957 | /* If transitioning into NOT_RUNNING, adjust nr_running. */ | |
958 | if ((flags & WORKER_NOT_RUNNING) && | |
959 | !(worker->flags & WORKER_NOT_RUNNING)) { | |
960 | atomic_dec(&pool->nr_running); | |
961 | } | |
962 | ||
963 | worker->flags |= flags; | |
964 | } | |
965 | ||
966 | /** | |
967 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly | |
968 | * @worker: self | |
969 | * @flags: flags to clear | |
970 | * | |
971 | * Clear @flags in @worker->flags and adjust nr_running accordingly. | |
972 | * | |
973 | * CONTEXT: | |
974 | * spin_lock_irq(pool->lock) | |
975 | */ | |
976 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) | |
977 | { | |
978 | struct worker_pool *pool = worker->pool; | |
979 | unsigned int oflags = worker->flags; | |
980 | ||
981 | WARN_ON_ONCE(worker->task != current); | |
982 | ||
983 | worker->flags &= ~flags; | |
984 | ||
985 | /* | |
986 | * If transitioning out of NOT_RUNNING, increment nr_running. Note | |
987 | * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask | |
988 | * of multiple flags, not a single flag. | |
989 | */ | |
990 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) | |
991 | if (!(worker->flags & WORKER_NOT_RUNNING)) | |
992 | atomic_inc(&pool->nr_running); | |
993 | } | |
994 | ||
995 | /** | |
996 | * find_worker_executing_work - find worker which is executing a work | |
997 | * @pool: pool of interest | |
998 | * @work: work to find worker for | |
999 | * | |
1000 | * Find a worker which is executing @work on @pool by searching | |
1001 | * @pool->busy_hash which is keyed by the address of @work. For a worker | |
1002 | * to match, its current execution should match the address of @work and | |
1003 | * its work function. This is to avoid unwanted dependency between | |
1004 | * unrelated work executions through a work item being recycled while still | |
1005 | * being executed. | |
1006 | * | |
1007 | * This is a bit tricky. A work item may be freed once its execution | |
1008 | * starts and nothing prevents the freed area from being recycled for | |
1009 | * another work item. If the same work item address ends up being reused | |
1010 | * before the original execution finishes, workqueue will identify the | |
1011 | * recycled work item as currently executing and make it wait until the | |
1012 | * current execution finishes, introducing an unwanted dependency. | |
1013 | * | |
1014 | * This function checks the work item address and work function to avoid | |
1015 | * false positives. Note that this isn't complete as one may construct a | |
1016 | * work function which can introduce dependency onto itself through a | |
1017 | * recycled work item. Well, if somebody wants to shoot oneself in the | |
1018 | * foot that badly, there's only so much we can do, and if such deadlock | |
1019 | * actually occurs, it should be easy to locate the culprit work function. | |
1020 | * | |
1021 | * CONTEXT: | |
1022 | * spin_lock_irq(pool->lock). | |
1023 | * | |
1024 | * Return: | |
1025 | * Pointer to worker which is executing @work if found, %NULL | |
1026 | * otherwise. | |
1027 | */ | |
1028 | static struct worker *find_worker_executing_work(struct worker_pool *pool, | |
1029 | struct work_struct *work) | |
1030 | { | |
1031 | struct worker *worker; | |
1032 | ||
1033 | hash_for_each_possible(pool->busy_hash, worker, hentry, | |
1034 | (unsigned long)work) | |
1035 | if (worker->current_work == work && | |
1036 | worker->current_func == work->func) | |
1037 | return worker; | |
1038 | ||
1039 | return NULL; | |
1040 | } | |
1041 | ||
1042 | /** | |
1043 | * move_linked_works - move linked works to a list | |
1044 | * @work: start of series of works to be scheduled | |
1045 | * @head: target list to append @work to | |
1046 | * @nextp: out parameter for nested worklist walking | |
1047 | * | |
1048 | * Schedule linked works starting from @work to @head. Work series to | |
1049 | * be scheduled starts at @work and includes any consecutive work with | |
1050 | * WORK_STRUCT_LINKED set in its predecessor. | |
1051 | * | |
1052 | * If @nextp is not NULL, it's updated to point to the next work of | |
1053 | * the last scheduled work. This allows move_linked_works() to be | |
1054 | * nested inside outer list_for_each_entry_safe(). | |
1055 | * | |
1056 | * CONTEXT: | |
1057 | * spin_lock_irq(pool->lock). | |
1058 | */ | |
1059 | static void move_linked_works(struct work_struct *work, struct list_head *head, | |
1060 | struct work_struct **nextp) | |
1061 | { | |
1062 | struct work_struct *n; | |
1063 | ||
1064 | /* | |
1065 | * Linked worklist will always end before the end of the list, | |
1066 | * use NULL for list head. | |
1067 | */ | |
1068 | list_for_each_entry_safe_from(work, n, NULL, entry) { | |
1069 | list_move_tail(&work->entry, head); | |
1070 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) | |
1071 | break; | |
1072 | } | |
1073 | ||
1074 | /* | |
1075 | * If we're already inside safe list traversal and have moved | |
1076 | * multiple works to the scheduled queue, the next position | |
1077 | * needs to be updated. | |
1078 | */ | |
1079 | if (nextp) | |
1080 | *nextp = n; | |
1081 | } | |
1082 | ||
1083 | /** | |
1084 | * get_pwq - get an extra reference on the specified pool_workqueue | |
1085 | * @pwq: pool_workqueue to get | |
1086 | * | |
1087 | * Obtain an extra reference on @pwq. The caller should guarantee that | |
1088 | * @pwq has positive refcnt and be holding the matching pool->lock. | |
1089 | */ | |
1090 | static void get_pwq(struct pool_workqueue *pwq) | |
1091 | { | |
1092 | lockdep_assert_held(&pwq->pool->lock); | |
1093 | WARN_ON_ONCE(pwq->refcnt <= 0); | |
1094 | pwq->refcnt++; | |
1095 | } | |
1096 | ||
1097 | /** | |
1098 | * put_pwq - put a pool_workqueue reference | |
1099 | * @pwq: pool_workqueue to put | |
1100 | * | |
1101 | * Drop a reference of @pwq. If its refcnt reaches zero, schedule its | |
1102 | * destruction. The caller should be holding the matching pool->lock. | |
1103 | */ | |
1104 | static void put_pwq(struct pool_workqueue *pwq) | |
1105 | { | |
1106 | lockdep_assert_held(&pwq->pool->lock); | |
1107 | if (likely(--pwq->refcnt)) | |
1108 | return; | |
1109 | if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) | |
1110 | return; | |
1111 | /* | |
1112 | * @pwq can't be released under pool->lock, bounce to | |
1113 | * pwq_unbound_release_workfn(). This never recurses on the same | |
1114 | * pool->lock as this path is taken only for unbound workqueues and | |
1115 | * the release work item is scheduled on a per-cpu workqueue. To | |
1116 | * avoid lockdep warning, unbound pool->locks are given lockdep | |
1117 | * subclass of 1 in get_unbound_pool(). | |
1118 | */ | |
1119 | schedule_work(&pwq->unbound_release_work); | |
1120 | } | |
1121 | ||
1122 | /** | |
1123 | * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock | |
1124 | * @pwq: pool_workqueue to put (can be %NULL) | |
1125 | * | |
1126 | * put_pwq() with locking. This function also allows %NULL @pwq. | |
1127 | */ | |
1128 | static void put_pwq_unlocked(struct pool_workqueue *pwq) | |
1129 | { | |
1130 | if (pwq) { | |
1131 | /* | |
1132 | * As both pwqs and pools are RCU protected, the | |
1133 | * following lock operations are safe. | |
1134 | */ | |
1135 | spin_lock_irq(&pwq->pool->lock); | |
1136 | put_pwq(pwq); | |
1137 | spin_unlock_irq(&pwq->pool->lock); | |
1138 | } | |
1139 | } | |
1140 | ||
1141 | static void pwq_activate_delayed_work(struct work_struct *work) | |
1142 | { | |
1143 | struct pool_workqueue *pwq = get_work_pwq(work); | |
1144 | ||
1145 | trace_workqueue_activate_work(work); | |
1146 | if (list_empty(&pwq->pool->worklist)) | |
1147 | pwq->pool->watchdog_ts = jiffies; | |
1148 | move_linked_works(work, &pwq->pool->worklist, NULL); | |
1149 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); | |
1150 | pwq->nr_active++; | |
1151 | } | |
1152 | ||
1153 | static void pwq_activate_first_delayed(struct pool_workqueue *pwq) | |
1154 | { | |
1155 | struct work_struct *work = list_first_entry(&pwq->delayed_works, | |
1156 | struct work_struct, entry); | |
1157 | ||
1158 | pwq_activate_delayed_work(work); | |
1159 | } | |
1160 | ||
1161 | /** | |
1162 | * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight | |
1163 | * @pwq: pwq of interest | |
1164 | * @color: color of work which left the queue | |
1165 | * | |
1166 | * A work either has completed or is removed from pending queue, | |
1167 | * decrement nr_in_flight of its pwq and handle workqueue flushing. | |
1168 | * | |
1169 | * CONTEXT: | |
1170 | * spin_lock_irq(pool->lock). | |
1171 | */ | |
1172 | static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) | |
1173 | { | |
1174 | /* uncolored work items don't participate in flushing or nr_active */ | |
1175 | if (color == WORK_NO_COLOR) | |
1176 | goto out_put; | |
1177 | ||
1178 | pwq->nr_in_flight[color]--; | |
1179 | ||
1180 | pwq->nr_active--; | |
1181 | if (!list_empty(&pwq->delayed_works)) { | |
1182 | /* one down, submit a delayed one */ | |
1183 | if (pwq->nr_active < pwq->max_active) | |
1184 | pwq_activate_first_delayed(pwq); | |
1185 | } | |
1186 | ||
1187 | /* is flush in progress and are we at the flushing tip? */ | |
1188 | if (likely(pwq->flush_color != color)) | |
1189 | goto out_put; | |
1190 | ||
1191 | /* are there still in-flight works? */ | |
1192 | if (pwq->nr_in_flight[color]) | |
1193 | goto out_put; | |
1194 | ||
1195 | /* this pwq is done, clear flush_color */ | |
1196 | pwq->flush_color = -1; | |
1197 | ||
1198 | /* | |
1199 | * If this was the last pwq, wake up the first flusher. It | |
1200 | * will handle the rest. | |
1201 | */ | |
1202 | if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) | |
1203 | complete(&pwq->wq->first_flusher->done); | |
1204 | out_put: | |
1205 | put_pwq(pwq); | |
1206 | } | |
1207 | ||
1208 | /** | |
1209 | * try_to_grab_pending - steal work item from worklist and disable irq | |
1210 | * @work: work item to steal | |
1211 | * @is_dwork: @work is a delayed_work | |
1212 | * @flags: place to store irq state | |
1213 | * | |
1214 | * Try to grab PENDING bit of @work. This function can handle @work in any | |
1215 | * stable state - idle, on timer or on worklist. | |
1216 | * | |
1217 | * Return: | |
1218 | * 1 if @work was pending and we successfully stole PENDING | |
1219 | * 0 if @work was idle and we claimed PENDING | |
1220 | * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry | |
1221 | * -ENOENT if someone else is canceling @work, this state may persist | |
1222 | * for arbitrarily long | |
1223 | * | |
1224 | * Note: | |
1225 | * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting | |
1226 | * interrupted while holding PENDING and @work off queue, irq must be | |
1227 | * disabled on entry. This, combined with delayed_work->timer being | |
1228 | * irqsafe, ensures that we return -EAGAIN for finite short period of time. | |
1229 | * | |
1230 | * On successful return, >= 0, irq is disabled and the caller is | |
1231 | * responsible for releasing it using local_irq_restore(*@flags). | |
1232 | * | |
1233 | * This function is safe to call from any context including IRQ handler. | |
1234 | */ | |
1235 | static int try_to_grab_pending(struct work_struct *work, bool is_dwork, | |
1236 | unsigned long *flags) | |
1237 | { | |
1238 | struct worker_pool *pool; | |
1239 | struct pool_workqueue *pwq; | |
1240 | ||
1241 | local_irq_save(*flags); | |
1242 | ||
1243 | /* try to steal the timer if it exists */ | |
1244 | if (is_dwork) { | |
1245 | struct delayed_work *dwork = to_delayed_work(work); | |
1246 | ||
1247 | /* | |
1248 | * dwork->timer is irqsafe. If del_timer() fails, it's | |
1249 | * guaranteed that the timer is not queued anywhere and not | |
1250 | * running on the local CPU. | |
1251 | */ | |
1252 | if (likely(del_timer(&dwork->timer))) | |
1253 | return 1; | |
1254 | } | |
1255 | ||
1256 | /* try to claim PENDING the normal way */ | |
1257 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) | |
1258 | return 0; | |
1259 | ||
1260 | rcu_read_lock(); | |
1261 | /* | |
1262 | * The queueing is in progress, or it is already queued. Try to | |
1263 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. | |
1264 | */ | |
1265 | pool = get_work_pool(work); | |
1266 | if (!pool) | |
1267 | goto fail; | |
1268 | ||
1269 | spin_lock(&pool->lock); | |
1270 | /* | |
1271 | * work->data is guaranteed to point to pwq only while the work | |
1272 | * item is queued on pwq->wq, and both updating work->data to point | |
1273 | * to pwq on queueing and to pool on dequeueing are done under | |
1274 | * pwq->pool->lock. This in turn guarantees that, if work->data | |
1275 | * points to pwq which is associated with a locked pool, the work | |
1276 | * item is currently queued on that pool. | |
1277 | */ | |
1278 | pwq = get_work_pwq(work); | |
1279 | if (pwq && pwq->pool == pool) { | |
1280 | debug_work_deactivate(work); | |
1281 | ||
1282 | /* | |
1283 | * A delayed work item cannot be grabbed directly because | |
1284 | * it might have linked NO_COLOR work items which, if left | |
1285 | * on the delayed_list, will confuse pwq->nr_active | |
1286 | * management later on and cause stall. Make sure the work | |
1287 | * item is activated before grabbing. | |
1288 | */ | |
1289 | if (*work_data_bits(work) & WORK_STRUCT_DELAYED) | |
1290 | pwq_activate_delayed_work(work); | |
1291 | ||
1292 | list_del_init(&work->entry); | |
1293 | pwq_dec_nr_in_flight(pwq, get_work_color(work)); | |
1294 | ||
1295 | /* work->data points to pwq iff queued, point to pool */ | |
1296 | set_work_pool_and_keep_pending(work, pool->id); | |
1297 | ||
1298 | spin_unlock(&pool->lock); | |
1299 | rcu_read_unlock(); | |
1300 | return 1; | |
1301 | } | |
1302 | spin_unlock(&pool->lock); | |
1303 | fail: | |
1304 | rcu_read_unlock(); | |
1305 | local_irq_restore(*flags); | |
1306 | if (work_is_canceling(work)) | |
1307 | return -ENOENT; | |
1308 | cpu_relax(); | |
1309 | return -EAGAIN; | |
1310 | } | |
1311 | ||
1312 | /** | |
1313 | * insert_work - insert a work into a pool | |
1314 | * @pwq: pwq @work belongs to | |
1315 | * @work: work to insert | |
1316 | * @head: insertion point | |
1317 | * @extra_flags: extra WORK_STRUCT_* flags to set | |
1318 | * | |
1319 | * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to | |
1320 | * work_struct flags. | |
1321 | * | |
1322 | * CONTEXT: | |
1323 | * spin_lock_irq(pool->lock). | |
1324 | */ | |
1325 | static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, | |
1326 | struct list_head *head, unsigned int extra_flags) | |
1327 | { | |
1328 | struct worker_pool *pool = pwq->pool; | |
1329 | ||
1330 | /* we own @work, set data and link */ | |
1331 | set_work_pwq(work, pwq, extra_flags); | |
1332 | list_add_tail(&work->entry, head); | |
1333 | get_pwq(pwq); | |
1334 | ||
1335 | /* | |
1336 | * Ensure either wq_worker_sleeping() sees the above | |
1337 | * list_add_tail() or we see zero nr_running to avoid workers lying | |
1338 | * around lazily while there are works to be processed. | |
1339 | */ | |
1340 | smp_mb(); | |
1341 | ||
1342 | if (__need_more_worker(pool)) | |
1343 | wake_up_worker(pool); | |
1344 | } | |
1345 | ||
1346 | /* | |
1347 | * Test whether @work is being queued from another work executing on the | |
1348 | * same workqueue. | |
1349 | */ | |
1350 | static bool is_chained_work(struct workqueue_struct *wq) | |
1351 | { | |
1352 | struct worker *worker; | |
1353 | ||
1354 | worker = current_wq_worker(); | |
1355 | /* | |
1356 | * Return %true iff I'm a worker executing a work item on @wq. If | |
1357 | * I'm @worker, it's safe to dereference it without locking. | |
1358 | */ | |
1359 | return worker && worker->current_pwq->wq == wq; | |
1360 | } | |
1361 | ||
1362 | /* | |
1363 | * When queueing an unbound work item to a wq, prefer local CPU if allowed | |
1364 | * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to | |
1365 | * avoid perturbing sensitive tasks. | |
1366 | */ | |
1367 | static int wq_select_unbound_cpu(int cpu) | |
1368 | { | |
1369 | static bool printed_dbg_warning; | |
1370 | int new_cpu; | |
1371 | ||
1372 | if (likely(!wq_debug_force_rr_cpu)) { | |
1373 | if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) | |
1374 | return cpu; | |
1375 | } else if (!printed_dbg_warning) { | |
1376 | pr_warn("workqueue: round-robin CPU selection forced, expect performance impact\n"); | |
1377 | printed_dbg_warning = true; | |
1378 | } | |
1379 | ||
1380 | if (cpumask_empty(wq_unbound_cpumask)) | |
1381 | return cpu; | |
1382 | ||
1383 | new_cpu = __this_cpu_read(wq_rr_cpu_last); | |
1384 | new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask); | |
1385 | if (unlikely(new_cpu >= nr_cpu_ids)) { | |
1386 | new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask); | |
1387 | if (unlikely(new_cpu >= nr_cpu_ids)) | |
1388 | return cpu; | |
1389 | } | |
1390 | __this_cpu_write(wq_rr_cpu_last, new_cpu); | |
1391 | ||
1392 | return new_cpu; | |
1393 | } | |
1394 | ||
1395 | static void __queue_work(int cpu, struct workqueue_struct *wq, | |
1396 | struct work_struct *work) | |
1397 | { | |
1398 | struct pool_workqueue *pwq; | |
1399 | struct worker_pool *last_pool; | |
1400 | struct list_head *worklist; | |
1401 | unsigned int work_flags; | |
1402 | unsigned int req_cpu = cpu; | |
1403 | ||
1404 | /* | |
1405 | * While a work item is PENDING && off queue, a task trying to | |
1406 | * steal the PENDING will busy-loop waiting for it to either get | |
1407 | * queued or lose PENDING. Grabbing PENDING and queueing should | |
1408 | * happen with IRQ disabled. | |
1409 | */ | |
1410 | lockdep_assert_irqs_disabled(); | |
1411 | ||
1412 | debug_work_activate(work); | |
1413 | ||
1414 | /* if draining, only works from the same workqueue are allowed */ | |
1415 | if (unlikely(wq->flags & __WQ_DRAINING) && | |
1416 | WARN_ON_ONCE(!is_chained_work(wq))) | |
1417 | return; | |
1418 | rcu_read_lock(); | |
1419 | retry: | |
1420 | /* pwq which will be used unless @work is executing elsewhere */ | |
1421 | if (wq->flags & WQ_UNBOUND) { | |
1422 | if (req_cpu == WORK_CPU_UNBOUND) | |
1423 | cpu = wq_select_unbound_cpu(raw_smp_processor_id()); | |
1424 | pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); | |
1425 | } else { | |
1426 | if (req_cpu == WORK_CPU_UNBOUND) | |
1427 | cpu = raw_smp_processor_id(); | |
1428 | pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); | |
1429 | } | |
1430 | ||
1431 | /* | |
1432 | * If @work was previously on a different pool, it might still be | |
1433 | * running there, in which case the work needs to be queued on that | |
1434 | * pool to guarantee non-reentrancy. | |
1435 | */ | |
1436 | last_pool = get_work_pool(work); | |
1437 | if (last_pool && last_pool != pwq->pool) { | |
1438 | struct worker *worker; | |
1439 | ||
1440 | spin_lock(&last_pool->lock); | |
1441 | ||
1442 | worker = find_worker_executing_work(last_pool, work); | |
1443 | ||
1444 | if (worker && worker->current_pwq->wq == wq) { | |
1445 | pwq = worker->current_pwq; | |
1446 | } else { | |
1447 | /* meh... not running there, queue here */ | |
1448 | spin_unlock(&last_pool->lock); | |
1449 | spin_lock(&pwq->pool->lock); | |
1450 | } | |
1451 | } else { | |
1452 | spin_lock(&pwq->pool->lock); | |
1453 | } | |
1454 | ||
1455 | /* | |
1456 | * pwq is determined and locked. For unbound pools, we could have | |
1457 | * raced with pwq release and it could already be dead. If its | |
1458 | * refcnt is zero, repeat pwq selection. Note that pwqs never die | |
1459 | * without another pwq replacing it in the numa_pwq_tbl or while | |
1460 | * work items are executing on it, so the retrying is guaranteed to | |
1461 | * make forward-progress. | |
1462 | */ | |
1463 | if (unlikely(!pwq->refcnt)) { | |
1464 | if (wq->flags & WQ_UNBOUND) { | |
1465 | spin_unlock(&pwq->pool->lock); | |
1466 | cpu_relax(); | |
1467 | goto retry; | |
1468 | } | |
1469 | /* oops */ | |
1470 | WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", | |
1471 | wq->name, cpu); | |
1472 | } | |
1473 | ||
1474 | /* pwq determined, queue */ | |
1475 | trace_workqueue_queue_work(req_cpu, pwq, work); | |
1476 | ||
1477 | if (WARN_ON(!list_empty(&work->entry))) | |
1478 | goto out; | |
1479 | ||
1480 | pwq->nr_in_flight[pwq->work_color]++; | |
1481 | work_flags = work_color_to_flags(pwq->work_color); | |
1482 | ||
1483 | if (likely(pwq->nr_active < pwq->max_active)) { | |
1484 | trace_workqueue_activate_work(work); | |
1485 | pwq->nr_active++; | |
1486 | worklist = &pwq->pool->worklist; | |
1487 | if (list_empty(worklist)) | |
1488 | pwq->pool->watchdog_ts = jiffies; | |
1489 | } else { | |
1490 | work_flags |= WORK_STRUCT_DELAYED; | |
1491 | worklist = &pwq->delayed_works; | |
1492 | } | |
1493 | ||
1494 | insert_work(pwq, work, worklist, work_flags); | |
1495 | ||
1496 | out: | |
1497 | spin_unlock(&pwq->pool->lock); | |
1498 | rcu_read_unlock(); | |
1499 | } | |
1500 | ||
1501 | /** | |
1502 | * queue_work_on - queue work on specific cpu | |
1503 | * @cpu: CPU number to execute work on | |
1504 | * @wq: workqueue to use | |
1505 | * @work: work to queue | |
1506 | * | |
1507 | * We queue the work to a specific CPU, the caller must ensure it | |
1508 | * can't go away. | |
1509 | * | |
1510 | * Return: %false if @work was already on a queue, %true otherwise. | |
1511 | */ | |
1512 | bool queue_work_on(int cpu, struct workqueue_struct *wq, | |
1513 | struct work_struct *work) | |
1514 | { | |
1515 | bool ret = false; | |
1516 | unsigned long flags; | |
1517 | ||
1518 | local_irq_save(flags); | |
1519 | ||
1520 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { | |
1521 | __queue_work(cpu, wq, work); | |
1522 | ret = true; | |
1523 | } | |
1524 | ||
1525 | local_irq_restore(flags); | |
1526 | return ret; | |
1527 | } | |
1528 | EXPORT_SYMBOL(queue_work_on); | |
1529 | ||
1530 | /** | |
1531 | * workqueue_select_cpu_near - Select a CPU based on NUMA node | |
1532 | * @node: NUMA node ID that we want to select a CPU from | |
1533 | * | |
1534 | * This function will attempt to find a "random" cpu available on a given | |
1535 | * node. If there are no CPUs available on the given node it will return | |
1536 | * WORK_CPU_UNBOUND indicating that we should just schedule to any | |
1537 | * available CPU if we need to schedule this work. | |
1538 | */ | |
1539 | static int workqueue_select_cpu_near(int node) | |
1540 | { | |
1541 | int cpu; | |
1542 | ||
1543 | /* No point in doing this if NUMA isn't enabled for workqueues */ | |
1544 | if (!wq_numa_enabled) | |
1545 | return WORK_CPU_UNBOUND; | |
1546 | ||
1547 | /* Delay binding to CPU if node is not valid or online */ | |
1548 | if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) | |
1549 | return WORK_CPU_UNBOUND; | |
1550 | ||
1551 | /* Use local node/cpu if we are already there */ | |
1552 | cpu = raw_smp_processor_id(); | |
1553 | if (node == cpu_to_node(cpu)) | |
1554 | return cpu; | |
1555 | ||
1556 | /* Use "random" otherwise know as "first" online CPU of node */ | |
1557 | cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); | |
1558 | ||
1559 | /* If CPU is valid return that, otherwise just defer */ | |
1560 | return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND; | |
1561 | } | |
1562 | ||
1563 | /** | |
1564 | * queue_work_node - queue work on a "random" cpu for a given NUMA node | |
1565 | * @node: NUMA node that we are targeting the work for | |
1566 | * @wq: workqueue to use | |
1567 | * @work: work to queue | |
1568 | * | |
1569 | * We queue the work to a "random" CPU within a given NUMA node. The basic | |
1570 | * idea here is to provide a way to somehow associate work with a given | |
1571 | * NUMA node. | |
1572 | * | |
1573 | * This function will only make a best effort attempt at getting this onto | |
1574 | * the right NUMA node. If no node is requested or the requested node is | |
1575 | * offline then we just fall back to standard queue_work behavior. | |
1576 | * | |
1577 | * Currently the "random" CPU ends up being the first available CPU in the | |
1578 | * intersection of cpu_online_mask and the cpumask of the node, unless we | |
1579 | * are running on the node. In that case we just use the current CPU. | |
1580 | * | |
1581 | * Return: %false if @work was already on a queue, %true otherwise. | |
1582 | */ | |
1583 | bool queue_work_node(int node, struct workqueue_struct *wq, | |
1584 | struct work_struct *work) | |
1585 | { | |
1586 | unsigned long flags; | |
1587 | bool ret = false; | |
1588 | ||
1589 | /* | |
1590 | * This current implementation is specific to unbound workqueues. | |
1591 | * Specifically we only return the first available CPU for a given | |
1592 | * node instead of cycling through individual CPUs within the node. | |
1593 | * | |
1594 | * If this is used with a per-cpu workqueue then the logic in | |
1595 | * workqueue_select_cpu_near would need to be updated to allow for | |
1596 | * some round robin type logic. | |
1597 | */ | |
1598 | WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)); | |
1599 | ||
1600 | local_irq_save(flags); | |
1601 | ||
1602 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { | |
1603 | int cpu = workqueue_select_cpu_near(node); | |
1604 | ||
1605 | __queue_work(cpu, wq, work); | |
1606 | ret = true; | |
1607 | } | |
1608 | ||
1609 | local_irq_restore(flags); | |
1610 | return ret; | |
1611 | } | |
1612 | EXPORT_SYMBOL_GPL(queue_work_node); | |
1613 | ||
1614 | void delayed_work_timer_fn(struct timer_list *t) | |
1615 | { | |
1616 | struct delayed_work *dwork = from_timer(dwork, t, timer); | |
1617 | ||
1618 | /* should have been called from irqsafe timer with irq already off */ | |
1619 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); | |
1620 | } | |
1621 | EXPORT_SYMBOL(delayed_work_timer_fn); | |
1622 | ||
1623 | static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, | |
1624 | struct delayed_work *dwork, unsigned long delay) | |
1625 | { | |
1626 | struct timer_list *timer = &dwork->timer; | |
1627 | struct work_struct *work = &dwork->work; | |
1628 | ||
1629 | WARN_ON_ONCE(!wq); | |
1630 | WARN_ON_ONCE(timer->function != delayed_work_timer_fn); | |
1631 | WARN_ON_ONCE(timer_pending(timer)); | |
1632 | WARN_ON_ONCE(!list_empty(&work->entry)); | |
1633 | ||
1634 | /* | |
1635 | * If @delay is 0, queue @dwork->work immediately. This is for | |
1636 | * both optimization and correctness. The earliest @timer can | |
1637 | * expire is on the closest next tick and delayed_work users depend | |
1638 | * on that there's no such delay when @delay is 0. | |
1639 | */ | |
1640 | if (!delay) { | |
1641 | __queue_work(cpu, wq, &dwork->work); | |
1642 | return; | |
1643 | } | |
1644 | ||
1645 | dwork->wq = wq; | |
1646 | dwork->cpu = cpu; | |
1647 | timer->expires = jiffies + delay; | |
1648 | ||
1649 | if (unlikely(cpu != WORK_CPU_UNBOUND)) | |
1650 | add_timer_on(timer, cpu); | |
1651 | else | |
1652 | add_timer(timer); | |
1653 | } | |
1654 | ||
1655 | /** | |
1656 | * queue_delayed_work_on - queue work on specific CPU after delay | |
1657 | * @cpu: CPU number to execute work on | |
1658 | * @wq: workqueue to use | |
1659 | * @dwork: work to queue | |
1660 | * @delay: number of jiffies to wait before queueing | |
1661 | * | |
1662 | * Return: %false if @work was already on a queue, %true otherwise. If | |
1663 | * @delay is zero and @dwork is idle, it will be scheduled for immediate | |
1664 | * execution. | |
1665 | */ | |
1666 | bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, | |
1667 | struct delayed_work *dwork, unsigned long delay) | |
1668 | { | |
1669 | struct work_struct *work = &dwork->work; | |
1670 | bool ret = false; | |
1671 | unsigned long flags; | |
1672 | ||
1673 | /* read the comment in __queue_work() */ | |
1674 | local_irq_save(flags); | |
1675 | ||
1676 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { | |
1677 | __queue_delayed_work(cpu, wq, dwork, delay); | |
1678 | ret = true; | |
1679 | } | |
1680 | ||
1681 | local_irq_restore(flags); | |
1682 | return ret; | |
1683 | } | |
1684 | EXPORT_SYMBOL(queue_delayed_work_on); | |
1685 | ||
1686 | /** | |
1687 | * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU | |
1688 | * @cpu: CPU number to execute work on | |
1689 | * @wq: workqueue to use | |
1690 | * @dwork: work to queue | |
1691 | * @delay: number of jiffies to wait before queueing | |
1692 | * | |
1693 | * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, | |
1694 | * modify @dwork's timer so that it expires after @delay. If @delay is | |
1695 | * zero, @work is guaranteed to be scheduled immediately regardless of its | |
1696 | * current state. | |
1697 | * | |
1698 | * Return: %false if @dwork was idle and queued, %true if @dwork was | |
1699 | * pending and its timer was modified. | |
1700 | * | |
1701 | * This function is safe to call from any context including IRQ handler. | |
1702 | * See try_to_grab_pending() for details. | |
1703 | */ | |
1704 | bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, | |
1705 | struct delayed_work *dwork, unsigned long delay) | |
1706 | { | |
1707 | unsigned long flags; | |
1708 | int ret; | |
1709 | ||
1710 | do { | |
1711 | ret = try_to_grab_pending(&dwork->work, true, &flags); | |
1712 | } while (unlikely(ret == -EAGAIN)); | |
1713 | ||
1714 | if (likely(ret >= 0)) { | |
1715 | __queue_delayed_work(cpu, wq, dwork, delay); | |
1716 | local_irq_restore(flags); | |
1717 | } | |
1718 | ||
1719 | /* -ENOENT from try_to_grab_pending() becomes %true */ | |
1720 | return ret; | |
1721 | } | |
1722 | EXPORT_SYMBOL_GPL(mod_delayed_work_on); | |
1723 | ||
1724 | static void rcu_work_rcufn(struct rcu_head *rcu) | |
1725 | { | |
1726 | struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu); | |
1727 | ||
1728 | /* read the comment in __queue_work() */ | |
1729 | local_irq_disable(); | |
1730 | __queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work); | |
1731 | local_irq_enable(); | |
1732 | } | |
1733 | ||
1734 | /** | |
1735 | * queue_rcu_work - queue work after a RCU grace period | |
1736 | * @wq: workqueue to use | |
1737 | * @rwork: work to queue | |
1738 | * | |
1739 | * Return: %false if @rwork was already pending, %true otherwise. Note | |
1740 | * that a full RCU grace period is guaranteed only after a %true return. | |
1741 | * While @rwork is guaranteed to be executed after a %false return, the | |
1742 | * execution may happen before a full RCU grace period has passed. | |
1743 | */ | |
1744 | bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) | |
1745 | { | |
1746 | struct work_struct *work = &rwork->work; | |
1747 | ||
1748 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { | |
1749 | rwork->wq = wq; | |
1750 | call_rcu(&rwork->rcu, rcu_work_rcufn); | |
1751 | return true; | |
1752 | } | |
1753 | ||
1754 | return false; | |
1755 | } | |
1756 | EXPORT_SYMBOL(queue_rcu_work); | |
1757 | ||
1758 | /** | |
1759 | * worker_enter_idle - enter idle state | |
1760 | * @worker: worker which is entering idle state | |
1761 | * | |
1762 | * @worker is entering idle state. Update stats and idle timer if | |
1763 | * necessary. | |
1764 | * | |
1765 | * LOCKING: | |
1766 | * spin_lock_irq(pool->lock). | |
1767 | */ | |
1768 | static void worker_enter_idle(struct worker *worker) | |
1769 | { | |
1770 | struct worker_pool *pool = worker->pool; | |
1771 | ||
1772 | if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || | |
1773 | WARN_ON_ONCE(!list_empty(&worker->entry) && | |
1774 | (worker->hentry.next || worker->hentry.pprev))) | |
1775 | return; | |
1776 | ||
1777 | /* can't use worker_set_flags(), also called from create_worker() */ | |
1778 | worker->flags |= WORKER_IDLE; | |
1779 | pool->nr_idle++; | |
1780 | worker->last_active = jiffies; | |
1781 | ||
1782 | /* idle_list is LIFO */ | |
1783 | list_add(&worker->entry, &pool->idle_list); | |
1784 | ||
1785 | if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) | |
1786 | mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); | |
1787 | ||
1788 | /* | |
1789 | * Sanity check nr_running. Because unbind_workers() releases | |
1790 | * pool->lock between setting %WORKER_UNBOUND and zapping | |
1791 | * nr_running, the warning may trigger spuriously. Check iff | |
1792 | * unbind is not in progress. | |
1793 | */ | |
1794 | WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && | |
1795 | pool->nr_workers == pool->nr_idle && | |
1796 | atomic_read(&pool->nr_running)); | |
1797 | } | |
1798 | ||
1799 | /** | |
1800 | * worker_leave_idle - leave idle state | |
1801 | * @worker: worker which is leaving idle state | |
1802 | * | |
1803 | * @worker is leaving idle state. Update stats. | |
1804 | * | |
1805 | * LOCKING: | |
1806 | * spin_lock_irq(pool->lock). | |
1807 | */ | |
1808 | static void worker_leave_idle(struct worker *worker) | |
1809 | { | |
1810 | struct worker_pool *pool = worker->pool; | |
1811 | ||
1812 | if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) | |
1813 | return; | |
1814 | worker_clr_flags(worker, WORKER_IDLE); | |
1815 | pool->nr_idle--; | |
1816 | list_del_init(&worker->entry); | |
1817 | } | |
1818 | ||
1819 | static struct worker *alloc_worker(int node) | |
1820 | { | |
1821 | struct worker *worker; | |
1822 | ||
1823 | worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); | |
1824 | if (worker) { | |
1825 | INIT_LIST_HEAD(&worker->entry); | |
1826 | INIT_LIST_HEAD(&worker->scheduled); | |
1827 | INIT_LIST_HEAD(&worker->node); | |
1828 | /* on creation a worker is in !idle && prep state */ | |
1829 | worker->flags = WORKER_PREP; | |
1830 | } | |
1831 | return worker; | |
1832 | } | |
1833 | ||
1834 | /** | |
1835 | * worker_attach_to_pool() - attach a worker to a pool | |
1836 | * @worker: worker to be attached | |
1837 | * @pool: the target pool | |
1838 | * | |
1839 | * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and | |
1840 | * cpu-binding of @worker are kept coordinated with the pool across | |
1841 | * cpu-[un]hotplugs. | |
1842 | */ | |
1843 | static void worker_attach_to_pool(struct worker *worker, | |
1844 | struct worker_pool *pool) | |
1845 | { | |
1846 | mutex_lock(&wq_pool_attach_mutex); | |
1847 | ||
1848 | /* | |
1849 | * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any | |
1850 | * online CPUs. It'll be re-applied when any of the CPUs come up. | |
1851 | */ | |
1852 | set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); | |
1853 | ||
1854 | /* | |
1855 | * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains | |
1856 | * stable across this function. See the comments above the flag | |
1857 | * definition for details. | |
1858 | */ | |
1859 | if (pool->flags & POOL_DISASSOCIATED) | |
1860 | worker->flags |= WORKER_UNBOUND; | |
1861 | ||
1862 | list_add_tail(&worker->node, &pool->workers); | |
1863 | worker->pool = pool; | |
1864 | ||
1865 | mutex_unlock(&wq_pool_attach_mutex); | |
1866 | } | |
1867 | ||
1868 | /** | |
1869 | * worker_detach_from_pool() - detach a worker from its pool | |
1870 | * @worker: worker which is attached to its pool | |
1871 | * | |
1872 | * Undo the attaching which had been done in worker_attach_to_pool(). The | |
1873 | * caller worker shouldn't access to the pool after detached except it has | |
1874 | * other reference to the pool. | |
1875 | */ | |
1876 | static void worker_detach_from_pool(struct worker *worker) | |
1877 | { | |
1878 | struct worker_pool *pool = worker->pool; | |
1879 | struct completion *detach_completion = NULL; | |
1880 | ||
1881 | mutex_lock(&wq_pool_attach_mutex); | |
1882 | ||
1883 | list_del(&worker->node); | |
1884 | worker->pool = NULL; | |
1885 | ||
1886 | if (list_empty(&pool->workers)) | |
1887 | detach_completion = pool->detach_completion; | |
1888 | mutex_unlock(&wq_pool_attach_mutex); | |
1889 | ||
1890 | /* clear leftover flags without pool->lock after it is detached */ | |
1891 | worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); | |
1892 | ||
1893 | if (detach_completion) | |
1894 | complete(detach_completion); | |
1895 | } | |
1896 | ||
1897 | /** | |
1898 | * create_worker - create a new workqueue worker | |
1899 | * @pool: pool the new worker will belong to | |
1900 | * | |
1901 | * Create and start a new worker which is attached to @pool. | |
1902 | * | |
1903 | * CONTEXT: | |
1904 | * Might sleep. Does GFP_KERNEL allocations. | |
1905 | * | |
1906 | * Return: | |
1907 | * Pointer to the newly created worker. | |
1908 | */ | |
1909 | static struct worker *create_worker(struct worker_pool *pool) | |
1910 | { | |
1911 | struct worker *worker = NULL; | |
1912 | int id = -1; | |
1913 | char id_buf[16]; | |
1914 | ||
1915 | /* ID is needed to determine kthread name */ | |
1916 | id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL); | |
1917 | if (id < 0) | |
1918 | goto fail; | |
1919 | ||
1920 | worker = alloc_worker(pool->node); | |
1921 | if (!worker) | |
1922 | goto fail; | |
1923 | ||
1924 | worker->id = id; | |
1925 | ||
1926 | if (pool->cpu >= 0) | |
1927 | snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, | |
1928 | pool->attrs->nice < 0 ? "H" : ""); | |
1929 | else | |
1930 | snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); | |
1931 | ||
1932 | worker->task = kthread_create_on_node(worker_thread, worker, pool->node, | |
1933 | "kworker/%s", id_buf); | |
1934 | if (IS_ERR(worker->task)) | |
1935 | goto fail; | |
1936 | ||
1937 | set_user_nice(worker->task, pool->attrs->nice); | |
1938 | kthread_bind_mask(worker->task, pool->attrs->cpumask); | |
1939 | ||
1940 | /* successful, attach the worker to the pool */ | |
1941 | worker_attach_to_pool(worker, pool); | |
1942 | ||
1943 | /* start the newly created worker */ | |
1944 | spin_lock_irq(&pool->lock); | |
1945 | worker->pool->nr_workers++; | |
1946 | worker_enter_idle(worker); | |
1947 | wake_up_process(worker->task); | |
1948 | spin_unlock_irq(&pool->lock); | |
1949 | ||
1950 | return worker; | |
1951 | ||
1952 | fail: | |
1953 | if (id >= 0) | |
1954 | ida_simple_remove(&pool->worker_ida, id); | |
1955 | kfree(worker); | |
1956 | return NULL; | |
1957 | } | |
1958 | ||
1959 | /** | |
1960 | * destroy_worker - destroy a workqueue worker | |
1961 | * @worker: worker to be destroyed | |
1962 | * | |
1963 | * Destroy @worker and adjust @pool stats accordingly. The worker should | |
1964 | * be idle. | |
1965 | * | |
1966 | * CONTEXT: | |
1967 | * spin_lock_irq(pool->lock). | |
1968 | */ | |
1969 | static void destroy_worker(struct worker *worker) | |
1970 | { | |
1971 | struct worker_pool *pool = worker->pool; | |
1972 | ||
1973 | lockdep_assert_held(&pool->lock); | |
1974 | ||
1975 | /* sanity check frenzy */ | |
1976 | if (WARN_ON(worker->current_work) || | |
1977 | WARN_ON(!list_empty(&worker->scheduled)) || | |
1978 | WARN_ON(!(worker->flags & WORKER_IDLE))) | |
1979 | return; | |
1980 | ||
1981 | pool->nr_workers--; | |
1982 | pool->nr_idle--; | |
1983 | ||
1984 | list_del_init(&worker->entry); | |
1985 | worker->flags |= WORKER_DIE; | |
1986 | wake_up_process(worker->task); | |
1987 | } | |
1988 | ||
1989 | static void idle_worker_timeout(struct timer_list *t) | |
1990 | { | |
1991 | struct worker_pool *pool = from_timer(pool, t, idle_timer); | |
1992 | ||
1993 | spin_lock_irq(&pool->lock); | |
1994 | ||
1995 | while (too_many_workers(pool)) { | |
1996 | struct worker *worker; | |
1997 | unsigned long expires; | |
1998 | ||
1999 | /* idle_list is kept in LIFO order, check the last one */ | |
2000 | worker = list_entry(pool->idle_list.prev, struct worker, entry); | |
2001 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; | |
2002 | ||
2003 | if (time_before(jiffies, expires)) { | |
2004 | mod_timer(&pool->idle_timer, expires); | |
2005 | break; | |
2006 | } | |
2007 | ||
2008 | destroy_worker(worker); | |
2009 | } | |
2010 | ||
2011 | spin_unlock_irq(&pool->lock); | |
2012 | } | |
2013 | ||
2014 | static void send_mayday(struct work_struct *work) | |
2015 | { | |
2016 | struct pool_workqueue *pwq = get_work_pwq(work); | |
2017 | struct workqueue_struct *wq = pwq->wq; | |
2018 | ||
2019 | lockdep_assert_held(&wq_mayday_lock); | |
2020 | ||
2021 | if (!wq->rescuer) | |
2022 | return; | |
2023 | ||
2024 | /* mayday mayday mayday */ | |
2025 | if (list_empty(&pwq->mayday_node)) { | |
2026 | /* | |
2027 | * If @pwq is for an unbound wq, its base ref may be put at | |
2028 | * any time due to an attribute change. Pin @pwq until the | |
2029 | * rescuer is done with it. | |
2030 | */ | |
2031 | get_pwq(pwq); | |
2032 | list_add_tail(&pwq->mayday_node, &wq->maydays); | |
2033 | wake_up_process(wq->rescuer->task); | |
2034 | } | |
2035 | } | |
2036 | ||
2037 | static void pool_mayday_timeout(struct timer_list *t) | |
2038 | { | |
2039 | struct worker_pool *pool = from_timer(pool, t, mayday_timer); | |
2040 | struct work_struct *work; | |
2041 | ||
2042 | spin_lock_irq(&pool->lock); | |
2043 | spin_lock(&wq_mayday_lock); /* for wq->maydays */ | |
2044 | ||
2045 | if (need_to_create_worker(pool)) { | |
2046 | /* | |
2047 | * We've been trying to create a new worker but | |
2048 | * haven't been successful. We might be hitting an | |
2049 | * allocation deadlock. Send distress signals to | |
2050 | * rescuers. | |
2051 | */ | |
2052 | list_for_each_entry(work, &pool->worklist, entry) | |
2053 | send_mayday(work); | |
2054 | } | |
2055 | ||
2056 | spin_unlock(&wq_mayday_lock); | |
2057 | spin_unlock_irq(&pool->lock); | |
2058 | ||
2059 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); | |
2060 | } | |
2061 | ||
2062 | /** | |
2063 | * maybe_create_worker - create a new worker if necessary | |
2064 | * @pool: pool to create a new worker for | |
2065 | * | |
2066 | * Create a new worker for @pool if necessary. @pool is guaranteed to | |
2067 | * have at least one idle worker on return from this function. If | |
2068 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is | |
2069 | * sent to all rescuers with works scheduled on @pool to resolve | |
2070 | * possible allocation deadlock. | |
2071 | * | |
2072 | * On return, need_to_create_worker() is guaranteed to be %false and | |
2073 | * may_start_working() %true. | |
2074 | * | |
2075 | * LOCKING: | |
2076 | * spin_lock_irq(pool->lock) which may be released and regrabbed | |
2077 | * multiple times. Does GFP_KERNEL allocations. Called only from | |
2078 | * manager. | |
2079 | */ | |
2080 | static void maybe_create_worker(struct worker_pool *pool) | |
2081 | __releases(&pool->lock) | |
2082 | __acquires(&pool->lock) | |
2083 | { | |
2084 | restart: | |
2085 | spin_unlock_irq(&pool->lock); | |
2086 | ||
2087 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ | |
2088 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); | |
2089 | ||
2090 | while (true) { | |
2091 | if (create_worker(pool) || !need_to_create_worker(pool)) | |
2092 | break; | |
2093 | ||
2094 | schedule_timeout_interruptible(CREATE_COOLDOWN); | |
2095 | ||
2096 | if (!need_to_create_worker(pool)) | |
2097 | break; | |
2098 | } | |
2099 | ||
2100 | del_timer_sync(&pool->mayday_timer); | |
2101 | spin_lock_irq(&pool->lock); | |
2102 | /* | |
2103 | * This is necessary even after a new worker was just successfully | |
2104 | * created as @pool->lock was dropped and the new worker might have | |
2105 | * already become busy. | |
2106 | */ | |
2107 | if (need_to_create_worker(pool)) | |
2108 | goto restart; | |
2109 | } | |
2110 | ||
2111 | /** | |
2112 | * manage_workers - manage worker pool | |
2113 | * @worker: self | |
2114 | * | |
2115 | * Assume the manager role and manage the worker pool @worker belongs | |
2116 | * to. At any given time, there can be only zero or one manager per | |
2117 | * pool. The exclusion is handled automatically by this function. | |
2118 | * | |
2119 | * The caller can safely start processing works on false return. On | |
2120 | * true return, it's guaranteed that need_to_create_worker() is false | |
2121 | * and may_start_working() is true. | |
2122 | * | |
2123 | * CONTEXT: | |
2124 | * spin_lock_irq(pool->lock) which may be released and regrabbed | |
2125 | * multiple times. Does GFP_KERNEL allocations. | |
2126 | * | |
2127 | * Return: | |
2128 | * %false if the pool doesn't need management and the caller can safely | |
2129 | * start processing works, %true if management function was performed and | |
2130 | * the conditions that the caller verified before calling the function may | |
2131 | * no longer be true. | |
2132 | */ | |
2133 | static bool manage_workers(struct worker *worker) | |
2134 | { | |
2135 | struct worker_pool *pool = worker->pool; | |
2136 | ||
2137 | if (pool->flags & POOL_MANAGER_ACTIVE) | |
2138 | return false; | |
2139 | ||
2140 | pool->flags |= POOL_MANAGER_ACTIVE; | |
2141 | pool->manager = worker; | |
2142 | ||
2143 | maybe_create_worker(pool); | |
2144 | ||
2145 | pool->manager = NULL; | |
2146 | pool->flags &= ~POOL_MANAGER_ACTIVE; | |
2147 | wake_up(&wq_manager_wait); | |
2148 | return true; | |
2149 | } | |
2150 | ||
2151 | /** | |
2152 | * process_one_work - process single work | |
2153 | * @worker: self | |
2154 | * @work: work to process | |
2155 | * | |
2156 | * Process @work. This function contains all the logics necessary to | |
2157 | * process a single work including synchronization against and | |
2158 | * interaction with other workers on the same cpu, queueing and | |
2159 | * flushing. As long as context requirement is met, any worker can | |
2160 | * call this function to process a work. | |
2161 | * | |
2162 | * CONTEXT: | |
2163 | * spin_lock_irq(pool->lock) which is released and regrabbed. | |
2164 | */ | |
2165 | static void process_one_work(struct worker *worker, struct work_struct *work) | |
2166 | __releases(&pool->lock) | |
2167 | __acquires(&pool->lock) | |
2168 | { | |
2169 | struct pool_workqueue *pwq = get_work_pwq(work); | |
2170 | struct worker_pool *pool = worker->pool; | |
2171 | bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; | |
2172 | int work_color; | |
2173 | struct worker *collision; | |
2174 | #ifdef CONFIG_LOCKDEP | |
2175 | /* | |
2176 | * It is permissible to free the struct work_struct from | |
2177 | * inside the function that is called from it, this we need to | |
2178 | * take into account for lockdep too. To avoid bogus "held | |
2179 | * lock freed" warnings as well as problems when looking into | |
2180 | * work->lockdep_map, make a copy and use that here. | |
2181 | */ | |
2182 | struct lockdep_map lockdep_map; | |
2183 | ||
2184 | lockdep_copy_map(&lockdep_map, &work->lockdep_map); | |
2185 | #endif | |
2186 | /* ensure we're on the correct CPU */ | |
2187 | WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && | |
2188 | raw_smp_processor_id() != pool->cpu); | |
2189 | ||
2190 | /* | |
2191 | * A single work shouldn't be executed concurrently by | |
2192 | * multiple workers on a single cpu. Check whether anyone is | |
2193 | * already processing the work. If so, defer the work to the | |
2194 | * currently executing one. | |
2195 | */ | |
2196 | collision = find_worker_executing_work(pool, work); | |
2197 | if (unlikely(collision)) { | |
2198 | move_linked_works(work, &collision->scheduled, NULL); | |
2199 | return; | |
2200 | } | |
2201 | ||
2202 | /* claim and dequeue */ | |
2203 | debug_work_deactivate(work); | |
2204 | hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); | |
2205 | worker->current_work = work; | |
2206 | worker->current_func = work->func; | |
2207 | worker->current_pwq = pwq; | |
2208 | work_color = get_work_color(work); | |
2209 | ||
2210 | /* | |
2211 | * Record wq name for cmdline and debug reporting, may get | |
2212 | * overridden through set_worker_desc(). | |
2213 | */ | |
2214 | strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN); | |
2215 | ||
2216 | list_del_init(&work->entry); | |
2217 | ||
2218 | /* | |
2219 | * CPU intensive works don't participate in concurrency management. | |
2220 | * They're the scheduler's responsibility. This takes @worker out | |
2221 | * of concurrency management and the next code block will chain | |
2222 | * execution of the pending work items. | |
2223 | */ | |
2224 | if (unlikely(cpu_intensive)) | |
2225 | worker_set_flags(worker, WORKER_CPU_INTENSIVE); | |
2226 | ||
2227 | /* | |
2228 | * Wake up another worker if necessary. The condition is always | |
2229 | * false for normal per-cpu workers since nr_running would always | |
2230 | * be >= 1 at this point. This is used to chain execution of the | |
2231 | * pending work items for WORKER_NOT_RUNNING workers such as the | |
2232 | * UNBOUND and CPU_INTENSIVE ones. | |
2233 | */ | |
2234 | if (need_more_worker(pool)) | |
2235 | wake_up_worker(pool); | |
2236 | ||
2237 | /* | |
2238 | * Record the last pool and clear PENDING which should be the last | |
2239 | * update to @work. Also, do this inside @pool->lock so that | |
2240 | * PENDING and queued state changes happen together while IRQ is | |
2241 | * disabled. | |
2242 | */ | |
2243 | set_work_pool_and_clear_pending(work, pool->id); | |
2244 | ||
2245 | spin_unlock_irq(&pool->lock); | |
2246 | ||
2247 | lock_map_acquire(&pwq->wq->lockdep_map); | |
2248 | lock_map_acquire(&lockdep_map); | |
2249 | /* | |
2250 | * Strictly speaking we should mark the invariant state without holding | |
2251 | * any locks, that is, before these two lock_map_acquire()'s. | |
2252 | * | |
2253 | * However, that would result in: | |
2254 | * | |
2255 | * A(W1) | |
2256 | * WFC(C) | |
2257 | * A(W1) | |
2258 | * C(C) | |
2259 | * | |
2260 | * Which would create W1->C->W1 dependencies, even though there is no | |
2261 | * actual deadlock possible. There are two solutions, using a | |
2262 | * read-recursive acquire on the work(queue) 'locks', but this will then | |
2263 | * hit the lockdep limitation on recursive locks, or simply discard | |
2264 | * these locks. | |
2265 | * | |
2266 | * AFAICT there is no possible deadlock scenario between the | |
2267 | * flush_work() and complete() primitives (except for single-threaded | |
2268 | * workqueues), so hiding them isn't a problem. | |
2269 | */ | |
2270 | lockdep_invariant_state(true); | |
2271 | trace_workqueue_execute_start(work); | |
2272 | worker->current_func(work); | |
2273 | /* | |
2274 | * While we must be careful to not use "work" after this, the trace | |
2275 | * point will only record its address. | |
2276 | */ | |
2277 | trace_workqueue_execute_end(work); | |
2278 | lock_map_release(&lockdep_map); | |
2279 | lock_map_release(&pwq->wq->lockdep_map); | |
2280 | ||
2281 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { | |
2282 | pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" | |
2283 | " last function: %ps\n", | |
2284 | current->comm, preempt_count(), task_pid_nr(current), | |
2285 | worker->current_func); | |
2286 | debug_show_held_locks(current); | |
2287 | dump_stack(); | |
2288 | } | |
2289 | ||
2290 | /* | |
2291 | * The following prevents a kworker from hogging CPU on !PREEMPT | |
2292 | * kernels, where a requeueing work item waiting for something to | |
2293 | * happen could deadlock with stop_machine as such work item could | |
2294 | * indefinitely requeue itself while all other CPUs are trapped in | |
2295 | * stop_machine. At the same time, report a quiescent RCU state so | |
2296 | * the same condition doesn't freeze RCU. | |
2297 | */ | |
2298 | cond_resched(); | |
2299 | ||
2300 | spin_lock_irq(&pool->lock); | |
2301 | ||
2302 | /* clear cpu intensive status */ | |
2303 | if (unlikely(cpu_intensive)) | |
2304 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); | |
2305 | ||
2306 | /* tag the worker for identification in schedule() */ | |
2307 | worker->last_func = worker->current_func; | |
2308 | ||
2309 | /* we're done with it, release */ | |
2310 | hash_del(&worker->hentry); | |
2311 | worker->current_work = NULL; | |
2312 | worker->current_func = NULL; | |
2313 | worker->current_pwq = NULL; | |
2314 | pwq_dec_nr_in_flight(pwq, work_color); | |
2315 | } | |
2316 | ||
2317 | /** | |
2318 | * process_scheduled_works - process scheduled works | |
2319 | * @worker: self | |
2320 | * | |
2321 | * Process all scheduled works. Please note that the scheduled list | |
2322 | * may change while processing a work, so this function repeatedly | |
2323 | * fetches a work from the top and executes it. | |
2324 | * | |
2325 | * CONTEXT: | |
2326 | * spin_lock_irq(pool->lock) which may be released and regrabbed | |
2327 | * multiple times. | |
2328 | */ | |
2329 | static void process_scheduled_works(struct worker *worker) | |
2330 | { | |
2331 | while (!list_empty(&worker->scheduled)) { | |
2332 | struct work_struct *work = list_first_entry(&worker->scheduled, | |
2333 | struct work_struct, entry); | |
2334 | process_one_work(worker, work); | |
2335 | } | |
2336 | } | |
2337 | ||
2338 | static void set_pf_worker(bool val) | |
2339 | { | |
2340 | mutex_lock(&wq_pool_attach_mutex); | |
2341 | if (val) | |
2342 | current->flags |= PF_WQ_WORKER; | |
2343 | else | |
2344 | current->flags &= ~PF_WQ_WORKER; | |
2345 | mutex_unlock(&wq_pool_attach_mutex); | |
2346 | } | |
2347 | ||
2348 | /** | |
2349 | * worker_thread - the worker thread function | |
2350 | * @__worker: self | |
2351 | * | |
2352 | * The worker thread function. All workers belong to a worker_pool - | |
2353 | * either a per-cpu one or dynamic unbound one. These workers process all | |
2354 | * work items regardless of their specific target workqueue. The only | |
2355 | * exception is work items which belong to workqueues with a rescuer which | |
2356 | * will be explained in rescuer_thread(). | |
2357 | * | |
2358 | * Return: 0 | |
2359 | */ | |
2360 | static int worker_thread(void *__worker) | |
2361 | { | |
2362 | struct worker *worker = __worker; | |
2363 | struct worker_pool *pool = worker->pool; | |
2364 | ||
2365 | /* tell the scheduler that this is a workqueue worker */ | |
2366 | set_pf_worker(true); | |
2367 | woke_up: | |
2368 | spin_lock_irq(&pool->lock); | |
2369 | ||
2370 | /* am I supposed to die? */ | |
2371 | if (unlikely(worker->flags & WORKER_DIE)) { | |
2372 | spin_unlock_irq(&pool->lock); | |
2373 | WARN_ON_ONCE(!list_empty(&worker->entry)); | |
2374 | set_pf_worker(false); | |
2375 | ||
2376 | set_task_comm(worker->task, "kworker/dying"); | |
2377 | ida_simple_remove(&pool->worker_ida, worker->id); | |
2378 | worker_detach_from_pool(worker); | |
2379 | kfree(worker); | |
2380 | return 0; | |
2381 | } | |
2382 | ||
2383 | worker_leave_idle(worker); | |
2384 | recheck: | |
2385 | /* no more worker necessary? */ | |
2386 | if (!need_more_worker(pool)) | |
2387 | goto sleep; | |
2388 | ||
2389 | /* do we need to manage? */ | |
2390 | if (unlikely(!may_start_working(pool)) && manage_workers(worker)) | |
2391 | goto recheck; | |
2392 | ||
2393 | /* | |
2394 | * ->scheduled list can only be filled while a worker is | |
2395 | * preparing to process a work or actually processing it. | |
2396 | * Make sure nobody diddled with it while I was sleeping. | |
2397 | */ | |
2398 | WARN_ON_ONCE(!list_empty(&worker->scheduled)); | |
2399 | ||
2400 | /* | |
2401 | * Finish PREP stage. We're guaranteed to have at least one idle | |
2402 | * worker or that someone else has already assumed the manager | |
2403 | * role. This is where @worker starts participating in concurrency | |
2404 | * management if applicable and concurrency management is restored | |
2405 | * after being rebound. See rebind_workers() for details. | |
2406 | */ | |
2407 | worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); | |
2408 | ||
2409 | do { | |
2410 | struct work_struct *work = | |
2411 | list_first_entry(&pool->worklist, | |
2412 | struct work_struct, entry); | |
2413 | ||
2414 | pool->watchdog_ts = jiffies; | |
2415 | ||
2416 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { | |
2417 | /* optimization path, not strictly necessary */ | |
2418 | process_one_work(worker, work); | |
2419 | if (unlikely(!list_empty(&worker->scheduled))) | |
2420 | process_scheduled_works(worker); | |
2421 | } else { | |
2422 | move_linked_works(work, &worker->scheduled, NULL); | |
2423 | process_scheduled_works(worker); | |
2424 | } | |
2425 | } while (keep_working(pool)); | |
2426 | ||
2427 | worker_set_flags(worker, WORKER_PREP); | |
2428 | sleep: | |
2429 | /* | |
2430 | * pool->lock is held and there's no work to process and no need to | |
2431 | * manage, sleep. Workers are woken up only while holding | |
2432 | * pool->lock or from local cpu, so setting the current state | |
2433 | * before releasing pool->lock is enough to prevent losing any | |
2434 | * event. | |
2435 | */ | |
2436 | worker_enter_idle(worker); | |
2437 | __set_current_state(TASK_IDLE); | |
2438 | spin_unlock_irq(&pool->lock); | |
2439 | schedule(); | |
2440 | goto woke_up; | |
2441 | } | |
2442 | ||
2443 | /** | |
2444 | * rescuer_thread - the rescuer thread function | |
2445 | * @__rescuer: self | |
2446 | * | |
2447 | * Workqueue rescuer thread function. There's one rescuer for each | |
2448 | * workqueue which has WQ_MEM_RECLAIM set. | |
2449 | * | |
2450 | * Regular work processing on a pool may block trying to create a new | |
2451 | * worker which uses GFP_KERNEL allocation which has slight chance of | |
2452 | * developing into deadlock if some works currently on the same queue | |
2453 | * need to be processed to satisfy the GFP_KERNEL allocation. This is | |
2454 | * the problem rescuer solves. | |
2455 | * | |
2456 | * When such condition is possible, the pool summons rescuers of all | |
2457 | * workqueues which have works queued on the pool and let them process | |
2458 | * those works so that forward progress can be guaranteed. | |
2459 | * | |
2460 | * This should happen rarely. | |
2461 | * | |
2462 | * Return: 0 | |
2463 | */ | |
2464 | static int rescuer_thread(void *__rescuer) | |
2465 | { | |
2466 | struct worker *rescuer = __rescuer; | |
2467 | struct workqueue_struct *wq = rescuer->rescue_wq; | |
2468 | struct list_head *scheduled = &rescuer->scheduled; | |
2469 | bool should_stop; | |
2470 | ||
2471 | set_user_nice(current, RESCUER_NICE_LEVEL); | |
2472 | ||
2473 | /* | |
2474 | * Mark rescuer as worker too. As WORKER_PREP is never cleared, it | |
2475 | * doesn't participate in concurrency management. | |
2476 | */ | |
2477 | set_pf_worker(true); | |
2478 | repeat: | |
2479 | set_current_state(TASK_IDLE); | |
2480 | ||
2481 | /* | |
2482 | * By the time the rescuer is requested to stop, the workqueue | |
2483 | * shouldn't have any work pending, but @wq->maydays may still have | |
2484 | * pwq(s) queued. This can happen by non-rescuer workers consuming | |
2485 | * all the work items before the rescuer got to them. Go through | |
2486 | * @wq->maydays processing before acting on should_stop so that the | |
2487 | * list is always empty on exit. | |
2488 | */ | |
2489 | should_stop = kthread_should_stop(); | |
2490 | ||
2491 | /* see whether any pwq is asking for help */ | |
2492 | spin_lock_irq(&wq_mayday_lock); | |
2493 | ||
2494 | while (!list_empty(&wq->maydays)) { | |
2495 | struct pool_workqueue *pwq = list_first_entry(&wq->maydays, | |
2496 | struct pool_workqueue, mayday_node); | |
2497 | struct worker_pool *pool = pwq->pool; | |
2498 | struct work_struct *work, *n; | |
2499 | bool first = true; | |
2500 | ||
2501 | __set_current_state(TASK_RUNNING); | |
2502 | list_del_init(&pwq->mayday_node); | |
2503 | ||
2504 | spin_unlock_irq(&wq_mayday_lock); | |
2505 | ||
2506 | worker_attach_to_pool(rescuer, pool); | |
2507 | ||
2508 | spin_lock_irq(&pool->lock); | |
2509 | ||
2510 | /* | |
2511 | * Slurp in all works issued via this workqueue and | |
2512 | * process'em. | |
2513 | */ | |
2514 | WARN_ON_ONCE(!list_empty(scheduled)); | |
2515 | list_for_each_entry_safe(work, n, &pool->worklist, entry) { | |
2516 | if (get_work_pwq(work) == pwq) { | |
2517 | if (first) | |
2518 | pool->watchdog_ts = jiffies; | |
2519 | move_linked_works(work, scheduled, &n); | |
2520 | } | |
2521 | first = false; | |
2522 | } | |
2523 | ||
2524 | if (!list_empty(scheduled)) { | |
2525 | process_scheduled_works(rescuer); | |
2526 | ||
2527 | /* | |
2528 | * The above execution of rescued work items could | |
2529 | * have created more to rescue through | |
2530 | * pwq_activate_first_delayed() or chained | |
2531 | * queueing. Let's put @pwq back on mayday list so | |
2532 | * that such back-to-back work items, which may be | |
2533 | * being used to relieve memory pressure, don't | |
2534 | * incur MAYDAY_INTERVAL delay inbetween. | |
2535 | */ | |
2536 | if (need_to_create_worker(pool)) { | |
2537 | spin_lock(&wq_mayday_lock); | |
2538 | /* | |
2539 | * Queue iff we aren't racing destruction | |
2540 | * and somebody else hasn't queued it already. | |
2541 | */ | |
2542 | if (wq->rescuer && list_empty(&pwq->mayday_node)) { | |
2543 | get_pwq(pwq); | |
2544 | list_add_tail(&pwq->mayday_node, &wq->maydays); | |
2545 | } | |
2546 | spin_unlock(&wq_mayday_lock); | |
2547 | } | |
2548 | } | |
2549 | ||
2550 | /* | |
2551 | * Put the reference grabbed by send_mayday(). @pool won't | |
2552 | * go away while we're still attached to it. | |
2553 | */ | |
2554 | put_pwq(pwq); | |
2555 | ||
2556 | /* | |
2557 | * Leave this pool. If need_more_worker() is %true, notify a | |
2558 | * regular worker; otherwise, we end up with 0 concurrency | |
2559 | * and stalling the execution. | |
2560 | */ | |
2561 | if (need_more_worker(pool)) | |
2562 | wake_up_worker(pool); | |
2563 | ||
2564 | spin_unlock_irq(&pool->lock); | |
2565 | ||
2566 | worker_detach_from_pool(rescuer); | |
2567 | ||
2568 | spin_lock_irq(&wq_mayday_lock); | |
2569 | } | |
2570 | ||
2571 | spin_unlock_irq(&wq_mayday_lock); | |
2572 | ||
2573 | if (should_stop) { | |
2574 | __set_current_state(TASK_RUNNING); | |
2575 | set_pf_worker(false); | |
2576 | return 0; | |
2577 | } | |
2578 | ||
2579 | /* rescuers should never participate in concurrency management */ | |
2580 | WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); | |
2581 | schedule(); | |
2582 | goto repeat; | |
2583 | } | |
2584 | ||
2585 | /** | |
2586 | * check_flush_dependency - check for flush dependency sanity | |
2587 | * @target_wq: workqueue being flushed | |
2588 | * @target_work: work item being flushed (NULL for workqueue flushes) | |
2589 | * | |
2590 | * %current is trying to flush the whole @target_wq or @target_work on it. | |
2591 | * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not | |
2592 | * reclaiming memory or running on a workqueue which doesn't have | |
2593 | * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to | |
2594 | * a deadlock. | |
2595 | */ | |
2596 | static void check_flush_dependency(struct workqueue_struct *target_wq, | |
2597 | struct work_struct *target_work) | |
2598 | { | |
2599 | work_func_t target_func = target_work ? target_work->func : NULL; | |
2600 | struct worker *worker; | |
2601 | ||
2602 | if (target_wq->flags & WQ_MEM_RECLAIM) | |
2603 | return; | |
2604 | ||
2605 | worker = current_wq_worker(); | |
2606 | ||
2607 | WARN_ONCE(current->flags & PF_MEMALLOC, | |
2608 | "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", | |
2609 | current->pid, current->comm, target_wq->name, target_func); | |
2610 | WARN_ONCE(worker && ((worker->current_pwq->wq->flags & | |
2611 | (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), | |
2612 | "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps", | |
2613 | worker->current_pwq->wq->name, worker->current_func, | |
2614 | target_wq->name, target_func); | |
2615 | } | |
2616 | ||
2617 | struct wq_barrier { | |
2618 | struct work_struct work; | |
2619 | struct completion done; | |
2620 | struct task_struct *task; /* purely informational */ | |
2621 | }; | |
2622 | ||
2623 | static void wq_barrier_func(struct work_struct *work) | |
2624 | { | |
2625 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); | |
2626 | complete(&barr->done); | |
2627 | } | |
2628 | ||
2629 | /** | |
2630 | * insert_wq_barrier - insert a barrier work | |
2631 | * @pwq: pwq to insert barrier into | |
2632 | * @barr: wq_barrier to insert | |
2633 | * @target: target work to attach @barr to | |
2634 | * @worker: worker currently executing @target, NULL if @target is not executing | |
2635 | * | |
2636 | * @barr is linked to @target such that @barr is completed only after | |
2637 | * @target finishes execution. Please note that the ordering | |
2638 | * guarantee is observed only with respect to @target and on the local | |
2639 | * cpu. | |
2640 | * | |
2641 | * Currently, a queued barrier can't be canceled. This is because | |
2642 | * try_to_grab_pending() can't determine whether the work to be | |
2643 | * grabbed is at the head of the queue and thus can't clear LINKED | |
2644 | * flag of the previous work while there must be a valid next work | |
2645 | * after a work with LINKED flag set. | |
2646 | * | |
2647 | * Note that when @worker is non-NULL, @target may be modified | |
2648 | * underneath us, so we can't reliably determine pwq from @target. | |
2649 | * | |
2650 | * CONTEXT: | |
2651 | * spin_lock_irq(pool->lock). | |
2652 | */ | |
2653 | static void insert_wq_barrier(struct pool_workqueue *pwq, | |
2654 | struct wq_barrier *barr, | |
2655 | struct work_struct *target, struct worker *worker) | |
2656 | { | |
2657 | struct list_head *head; | |
2658 | unsigned int linked = 0; | |
2659 | ||
2660 | /* | |
2661 | * debugobject calls are safe here even with pool->lock locked | |
2662 | * as we know for sure that this will not trigger any of the | |
2663 | * checks and call back into the fixup functions where we | |
2664 | * might deadlock. | |
2665 | */ | |
2666 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); | |
2667 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); | |
2668 | ||
2669 | init_completion_map(&barr->done, &target->lockdep_map); | |
2670 | ||
2671 | barr->task = current; | |
2672 | ||
2673 | /* | |
2674 | * If @target is currently being executed, schedule the | |
2675 | * barrier to the worker; otherwise, put it after @target. | |
2676 | */ | |
2677 | if (worker) | |
2678 | head = worker->scheduled.next; | |
2679 | else { | |
2680 | unsigned long *bits = work_data_bits(target); | |
2681 | ||
2682 | head = target->entry.next; | |
2683 | /* there can already be other linked works, inherit and set */ | |
2684 | linked = *bits & WORK_STRUCT_LINKED; | |
2685 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); | |
2686 | } | |
2687 | ||
2688 | debug_work_activate(&barr->work); | |
2689 | insert_work(pwq, &barr->work, head, | |
2690 | work_color_to_flags(WORK_NO_COLOR) | linked); | |
2691 | } | |
2692 | ||
2693 | /** | |
2694 | * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing | |
2695 | * @wq: workqueue being flushed | |
2696 | * @flush_color: new flush color, < 0 for no-op | |
2697 | * @work_color: new work color, < 0 for no-op | |
2698 | * | |
2699 | * Prepare pwqs for workqueue flushing. | |
2700 | * | |
2701 | * If @flush_color is non-negative, flush_color on all pwqs should be | |
2702 | * -1. If no pwq has in-flight commands at the specified color, all | |
2703 | * pwq->flush_color's stay at -1 and %false is returned. If any pwq | |
2704 | * has in flight commands, its pwq->flush_color is set to | |
2705 | * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq | |
2706 | * wakeup logic is armed and %true is returned. | |
2707 | * | |
2708 | * The caller should have initialized @wq->first_flusher prior to | |
2709 | * calling this function with non-negative @flush_color. If | |
2710 | * @flush_color is negative, no flush color update is done and %false | |
2711 | * is returned. | |
2712 | * | |
2713 | * If @work_color is non-negative, all pwqs should have the same | |
2714 | * work_color which is previous to @work_color and all will be | |
2715 | * advanced to @work_color. | |
2716 | * | |
2717 | * CONTEXT: | |
2718 | * mutex_lock(wq->mutex). | |
2719 | * | |
2720 | * Return: | |
2721 | * %true if @flush_color >= 0 and there's something to flush. %false | |
2722 | * otherwise. | |
2723 | */ | |
2724 | static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, | |
2725 | int flush_color, int work_color) | |
2726 | { | |
2727 | bool wait = false; | |
2728 | struct pool_workqueue *pwq; | |
2729 | ||
2730 | if (flush_color >= 0) { | |
2731 | WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); | |
2732 | atomic_set(&wq->nr_pwqs_to_flush, 1); | |
2733 | } | |
2734 | ||
2735 | for_each_pwq(pwq, wq) { | |
2736 | struct worker_pool *pool = pwq->pool; | |
2737 | ||
2738 | spin_lock_irq(&pool->lock); | |
2739 | ||
2740 | if (flush_color >= 0) { | |
2741 | WARN_ON_ONCE(pwq->flush_color != -1); | |
2742 | ||
2743 | if (pwq->nr_in_flight[flush_color]) { | |
2744 | pwq->flush_color = flush_color; | |
2745 | atomic_inc(&wq->nr_pwqs_to_flush); | |
2746 | wait = true; | |
2747 | } | |
2748 | } | |
2749 | ||
2750 | if (work_color >= 0) { | |
2751 | WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); | |
2752 | pwq->work_color = work_color; | |
2753 | } | |
2754 | ||
2755 | spin_unlock_irq(&pool->lock); | |
2756 | } | |
2757 | ||
2758 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) | |
2759 | complete(&wq->first_flusher->done); | |
2760 | ||
2761 | return wait; | |
2762 | } | |
2763 | ||
2764 | /** | |
2765 | * flush_workqueue - ensure that any scheduled work has run to completion. | |
2766 | * @wq: workqueue to flush | |
2767 | * | |
2768 | * This function sleeps until all work items which were queued on entry | |
2769 | * have finished execution, but it is not livelocked by new incoming ones. | |
2770 | */ | |
2771 | void flush_workqueue(struct workqueue_struct *wq) | |
2772 | { | |
2773 | struct wq_flusher this_flusher = { | |
2774 | .list = LIST_HEAD_INIT(this_flusher.list), | |
2775 | .flush_color = -1, | |
2776 | .done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map), | |
2777 | }; | |
2778 | int next_color; | |
2779 | ||
2780 | if (WARN_ON(!wq_online)) | |
2781 | return; | |
2782 | ||
2783 | lock_map_acquire(&wq->lockdep_map); | |
2784 | lock_map_release(&wq->lockdep_map); | |
2785 | ||
2786 | mutex_lock(&wq->mutex); | |
2787 | ||
2788 | /* | |
2789 | * Start-to-wait phase | |
2790 | */ | |
2791 | next_color = work_next_color(wq->work_color); | |
2792 | ||
2793 | if (next_color != wq->flush_color) { | |
2794 | /* | |
2795 | * Color space is not full. The current work_color | |
2796 | * becomes our flush_color and work_color is advanced | |
2797 | * by one. | |
2798 | */ | |
2799 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); | |
2800 | this_flusher.flush_color = wq->work_color; | |
2801 | wq->work_color = next_color; | |
2802 | ||
2803 | if (!wq->first_flusher) { | |
2804 | /* no flush in progress, become the first flusher */ | |
2805 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); | |
2806 | ||
2807 | wq->first_flusher = &this_flusher; | |
2808 | ||
2809 | if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, | |
2810 | wq->work_color)) { | |
2811 | /* nothing to flush, done */ | |
2812 | wq->flush_color = next_color; | |
2813 | wq->first_flusher = NULL; | |
2814 | goto out_unlock; | |
2815 | } | |
2816 | } else { | |
2817 | /* wait in queue */ | |
2818 | WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); | |
2819 | list_add_tail(&this_flusher.list, &wq->flusher_queue); | |
2820 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); | |
2821 | } | |
2822 | } else { | |
2823 | /* | |
2824 | * Oops, color space is full, wait on overflow queue. | |
2825 | * The next flush completion will assign us | |
2826 | * flush_color and transfer to flusher_queue. | |
2827 | */ | |
2828 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); | |
2829 | } | |
2830 | ||
2831 | check_flush_dependency(wq, NULL); | |
2832 | ||
2833 | mutex_unlock(&wq->mutex); | |
2834 | ||
2835 | wait_for_completion(&this_flusher.done); | |
2836 | ||
2837 | /* | |
2838 | * Wake-up-and-cascade phase | |
2839 | * | |
2840 | * First flushers are responsible for cascading flushes and | |
2841 | * handling overflow. Non-first flushers can simply return. | |
2842 | */ | |
2843 | if (wq->first_flusher != &this_flusher) | |
2844 | return; | |
2845 | ||
2846 | mutex_lock(&wq->mutex); | |
2847 | ||
2848 | /* we might have raced, check again with mutex held */ | |
2849 | if (wq->first_flusher != &this_flusher) | |
2850 | goto out_unlock; | |
2851 | ||
2852 | wq->first_flusher = NULL; | |
2853 | ||
2854 | WARN_ON_ONCE(!list_empty(&this_flusher.list)); | |
2855 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); | |
2856 | ||
2857 | while (true) { | |
2858 | struct wq_flusher *next, *tmp; | |
2859 | ||
2860 | /* complete all the flushers sharing the current flush color */ | |
2861 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { | |
2862 | if (next->flush_color != wq->flush_color) | |
2863 | break; | |
2864 | list_del_init(&next->list); | |
2865 | complete(&next->done); | |
2866 | } | |
2867 | ||
2868 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && | |
2869 | wq->flush_color != work_next_color(wq->work_color)); | |
2870 | ||
2871 | /* this flush_color is finished, advance by one */ | |
2872 | wq->flush_color = work_next_color(wq->flush_color); | |
2873 | ||
2874 | /* one color has been freed, handle overflow queue */ | |
2875 | if (!list_empty(&wq->flusher_overflow)) { | |
2876 | /* | |
2877 | * Assign the same color to all overflowed | |
2878 | * flushers, advance work_color and append to | |
2879 | * flusher_queue. This is the start-to-wait | |
2880 | * phase for these overflowed flushers. | |
2881 | */ | |
2882 | list_for_each_entry(tmp, &wq->flusher_overflow, list) | |
2883 | tmp->flush_color = wq->work_color; | |
2884 | ||
2885 | wq->work_color = work_next_color(wq->work_color); | |
2886 | ||
2887 | list_splice_tail_init(&wq->flusher_overflow, | |
2888 | &wq->flusher_queue); | |
2889 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); | |
2890 | } | |
2891 | ||
2892 | if (list_empty(&wq->flusher_queue)) { | |
2893 | WARN_ON_ONCE(wq->flush_color != wq->work_color); | |
2894 | break; | |
2895 | } | |
2896 | ||
2897 | /* | |
2898 | * Need to flush more colors. Make the next flusher | |
2899 | * the new first flusher and arm pwqs. | |
2900 | */ | |
2901 | WARN_ON_ONCE(wq->flush_color == wq->work_color); | |
2902 | WARN_ON_ONCE(wq->flush_color != next->flush_color); | |
2903 | ||
2904 | list_del_init(&next->list); | |
2905 | wq->first_flusher = next; | |
2906 | ||
2907 | if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) | |
2908 | break; | |
2909 | ||
2910 | /* | |
2911 | * Meh... this color is already done, clear first | |
2912 | * flusher and repeat cascading. | |
2913 | */ | |
2914 | wq->first_flusher = NULL; | |
2915 | } | |
2916 | ||
2917 | out_unlock: | |
2918 | mutex_unlock(&wq->mutex); | |
2919 | } | |
2920 | EXPORT_SYMBOL(flush_workqueue); | |
2921 | ||
2922 | /** | |
2923 | * drain_workqueue - drain a workqueue | |
2924 | * @wq: workqueue to drain | |
2925 | * | |
2926 | * Wait until the workqueue becomes empty. While draining is in progress, | |
2927 | * only chain queueing is allowed. IOW, only currently pending or running | |
2928 | * work items on @wq can queue further work items on it. @wq is flushed | |
2929 | * repeatedly until it becomes empty. The number of flushing is determined | |
2930 | * by the depth of chaining and should be relatively short. Whine if it | |
2931 | * takes too long. | |
2932 | */ | |
2933 | void drain_workqueue(struct workqueue_struct *wq) | |
2934 | { | |
2935 | unsigned int flush_cnt = 0; | |
2936 | struct pool_workqueue *pwq; | |
2937 | ||
2938 | /* | |
2939 | * __queue_work() needs to test whether there are drainers, is much | |
2940 | * hotter than drain_workqueue() and already looks at @wq->flags. | |
2941 | * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. | |
2942 | */ | |
2943 | mutex_lock(&wq->mutex); | |
2944 | if (!wq->nr_drainers++) | |
2945 | wq->flags |= __WQ_DRAINING; | |
2946 | mutex_unlock(&wq->mutex); | |
2947 | reflush: | |
2948 | flush_workqueue(wq); | |
2949 | ||
2950 | mutex_lock(&wq->mutex); | |
2951 | ||
2952 | for_each_pwq(pwq, wq) { | |
2953 | bool drained; | |
2954 | ||
2955 | spin_lock_irq(&pwq->pool->lock); | |
2956 | drained = !pwq->nr_active && list_empty(&pwq->delayed_works); | |
2957 | spin_unlock_irq(&pwq->pool->lock); | |
2958 | ||
2959 | if (drained) | |
2960 | continue; | |
2961 | ||
2962 | if (++flush_cnt == 10 || | |
2963 | (flush_cnt % 100 == 0 && flush_cnt <= 1000)) | |
2964 | pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n", | |
2965 | wq->name, flush_cnt); | |
2966 | ||
2967 | mutex_unlock(&wq->mutex); | |
2968 | goto reflush; | |
2969 | } | |
2970 | ||
2971 | if (!--wq->nr_drainers) | |
2972 | wq->flags &= ~__WQ_DRAINING; | |
2973 | mutex_unlock(&wq->mutex); | |
2974 | } | |
2975 | EXPORT_SYMBOL_GPL(drain_workqueue); | |
2976 | ||
2977 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, | |
2978 | bool from_cancel) | |
2979 | { | |
2980 | struct worker *worker = NULL; | |
2981 | struct worker_pool *pool; | |
2982 | struct pool_workqueue *pwq; | |
2983 | ||
2984 | might_sleep(); | |
2985 | ||
2986 | rcu_read_lock(); | |
2987 | pool = get_work_pool(work); | |
2988 | if (!pool) { | |
2989 | rcu_read_unlock(); | |
2990 | return false; | |
2991 | } | |
2992 | ||
2993 | spin_lock_irq(&pool->lock); | |
2994 | /* see the comment in try_to_grab_pending() with the same code */ | |
2995 | pwq = get_work_pwq(work); | |
2996 | if (pwq) { | |
2997 | if (unlikely(pwq->pool != pool)) | |
2998 | goto already_gone; | |
2999 | } else { | |
3000 | worker = find_worker_executing_work(pool, work); | |
3001 | if (!worker) | |
3002 | goto already_gone; | |
3003 | pwq = worker->current_pwq; | |
3004 | } | |
3005 | ||
3006 | check_flush_dependency(pwq->wq, work); | |
3007 | ||
3008 | insert_wq_barrier(pwq, barr, work, worker); | |
3009 | spin_unlock_irq(&pool->lock); | |
3010 | ||
3011 | /* | |
3012 | * Force a lock recursion deadlock when using flush_work() inside a | |
3013 | * single-threaded or rescuer equipped workqueue. | |
3014 | * | |
3015 | * For single threaded workqueues the deadlock happens when the work | |
3016 | * is after the work issuing the flush_work(). For rescuer equipped | |
3017 | * workqueues the deadlock happens when the rescuer stalls, blocking | |
3018 | * forward progress. | |
3019 | */ | |
3020 | if (!from_cancel && | |
3021 | (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)) { | |
3022 | lock_map_acquire(&pwq->wq->lockdep_map); | |
3023 | lock_map_release(&pwq->wq->lockdep_map); | |
3024 | } | |
3025 | rcu_read_unlock(); | |
3026 | return true; | |
3027 | already_gone: | |
3028 | spin_unlock_irq(&pool->lock); | |
3029 | rcu_read_unlock(); | |
3030 | return false; | |
3031 | } | |
3032 | ||
3033 | static bool __flush_work(struct work_struct *work, bool from_cancel) | |
3034 | { | |
3035 | struct wq_barrier barr; | |
3036 | ||
3037 | if (WARN_ON(!wq_online)) | |
3038 | return false; | |
3039 | ||
3040 | if (WARN_ON(!work->func)) | |
3041 | return false; | |
3042 | ||
3043 | if (!from_cancel) { | |
3044 | lock_map_acquire(&work->lockdep_map); | |
3045 | lock_map_release(&work->lockdep_map); | |
3046 | } | |
3047 | ||
3048 | if (start_flush_work(work, &barr, from_cancel)) { | |
3049 | wait_for_completion(&barr.done); | |
3050 | destroy_work_on_stack(&barr.work); | |
3051 | return true; | |
3052 | } else { | |
3053 | return false; | |
3054 | } | |
3055 | } | |
3056 | ||
3057 | /** | |
3058 | * flush_work - wait for a work to finish executing the last queueing instance | |
3059 | * @work: the work to flush | |
3060 | * | |
3061 | * Wait until @work has finished execution. @work is guaranteed to be idle | |
3062 | * on return if it hasn't been requeued since flush started. | |
3063 | * | |
3064 | * Return: | |
3065 | * %true if flush_work() waited for the work to finish execution, | |
3066 | * %false if it was already idle. | |
3067 | */ | |
3068 | bool flush_work(struct work_struct *work) | |
3069 | { | |
3070 | return __flush_work(work, false); | |
3071 | } | |
3072 | EXPORT_SYMBOL_GPL(flush_work); | |
3073 | ||
3074 | struct cwt_wait { | |
3075 | wait_queue_entry_t wait; | |
3076 | struct work_struct *work; | |
3077 | }; | |
3078 | ||
3079 | static int cwt_wakefn(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) | |
3080 | { | |
3081 | struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait); | |
3082 | ||
3083 | if (cwait->work != key) | |
3084 | return 0; | |
3085 | return autoremove_wake_function(wait, mode, sync, key); | |
3086 | } | |
3087 | ||
3088 | static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) | |
3089 | { | |
3090 | static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq); | |
3091 | unsigned long flags; | |
3092 | int ret; | |
3093 | ||
3094 | do { | |
3095 | ret = try_to_grab_pending(work, is_dwork, &flags); | |
3096 | /* | |
3097 | * If someone else is already canceling, wait for it to | |
3098 | * finish. flush_work() doesn't work for PREEMPT_NONE | |
3099 | * because we may get scheduled between @work's completion | |
3100 | * and the other canceling task resuming and clearing | |
3101 | * CANCELING - flush_work() will return false immediately | |
3102 | * as @work is no longer busy, try_to_grab_pending() will | |
3103 | * return -ENOENT as @work is still being canceled and the | |
3104 | * other canceling task won't be able to clear CANCELING as | |
3105 | * we're hogging the CPU. | |
3106 | * | |
3107 | * Let's wait for completion using a waitqueue. As this | |
3108 | * may lead to the thundering herd problem, use a custom | |
3109 | * wake function which matches @work along with exclusive | |
3110 | * wait and wakeup. | |
3111 | */ | |
3112 | if (unlikely(ret == -ENOENT)) { | |
3113 | struct cwt_wait cwait; | |
3114 | ||
3115 | init_wait(&cwait.wait); | |
3116 | cwait.wait.func = cwt_wakefn; | |
3117 | cwait.work = work; | |
3118 | ||
3119 | prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait, | |
3120 | TASK_UNINTERRUPTIBLE); | |
3121 | if (work_is_canceling(work)) | |
3122 | schedule(); | |
3123 | finish_wait(&cancel_waitq, &cwait.wait); | |
3124 | } | |
3125 | } while (unlikely(ret < 0)); | |
3126 | ||
3127 | /* tell other tasks trying to grab @work to back off */ | |
3128 | mark_work_canceling(work); | |
3129 | local_irq_restore(flags); | |
3130 | ||
3131 | /* | |
3132 | * This allows canceling during early boot. We know that @work | |
3133 | * isn't executing. | |
3134 | */ | |
3135 | if (wq_online) | |
3136 | __flush_work(work, true); | |
3137 | ||
3138 | clear_work_data(work); | |
3139 | ||
3140 | /* | |
3141 | * Paired with prepare_to_wait() above so that either | |
3142 | * waitqueue_active() is visible here or !work_is_canceling() is | |
3143 | * visible there. | |
3144 | */ | |
3145 | smp_mb(); | |
3146 | if (waitqueue_active(&cancel_waitq)) | |
3147 | __wake_up(&cancel_waitq, TASK_NORMAL, 1, work); | |
3148 | ||
3149 | return ret; | |
3150 | } | |
3151 | ||
3152 | /** | |
3153 | * cancel_work_sync - cancel a work and wait for it to finish | |
3154 | * @work: the work to cancel | |
3155 | * | |
3156 | * Cancel @work and wait for its execution to finish. This function | |
3157 | * can be used even if the work re-queues itself or migrates to | |
3158 | * another workqueue. On return from this function, @work is | |
3159 | * guaranteed to be not pending or executing on any CPU. | |
3160 | * | |
3161 | * cancel_work_sync(&delayed_work->work) must not be used for | |
3162 | * delayed_work's. Use cancel_delayed_work_sync() instead. | |
3163 | * | |
3164 | * The caller must ensure that the workqueue on which @work was last | |
3165 | * queued can't be destroyed before this function returns. | |
3166 | * | |
3167 | * Return: | |
3168 | * %true if @work was pending, %false otherwise. | |
3169 | */ | |
3170 | bool cancel_work_sync(struct work_struct *work) | |
3171 | { | |
3172 | return __cancel_work_timer(work, false); | |
3173 | } | |
3174 | EXPORT_SYMBOL_GPL(cancel_work_sync); | |
3175 | ||
3176 | /** | |
3177 | * flush_delayed_work - wait for a dwork to finish executing the last queueing | |
3178 | * @dwork: the delayed work to flush | |
3179 | * | |
3180 | * Delayed timer is cancelled and the pending work is queued for | |
3181 | * immediate execution. Like flush_work(), this function only | |
3182 | * considers the last queueing instance of @dwork. | |
3183 | * | |
3184 | * Return: | |
3185 | * %true if flush_work() waited for the work to finish execution, | |
3186 | * %false if it was already idle. | |
3187 | */ | |
3188 | bool flush_delayed_work(struct delayed_work *dwork) | |
3189 | { | |
3190 | local_irq_disable(); | |
3191 | if (del_timer_sync(&dwork->timer)) | |
3192 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); | |
3193 | local_irq_enable(); | |
3194 | return flush_work(&dwork->work); | |
3195 | } | |
3196 | EXPORT_SYMBOL(flush_delayed_work); | |
3197 | ||
3198 | /** | |
3199 | * flush_rcu_work - wait for a rwork to finish executing the last queueing | |
3200 | * @rwork: the rcu work to flush | |
3201 | * | |
3202 | * Return: | |
3203 | * %true if flush_rcu_work() waited for the work to finish execution, | |
3204 | * %false if it was already idle. | |
3205 | */ | |
3206 | bool flush_rcu_work(struct rcu_work *rwork) | |
3207 | { | |
3208 | if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) { | |
3209 | rcu_barrier(); | |
3210 | flush_work(&rwork->work); | |
3211 | return true; | |
3212 | } else { | |
3213 | return flush_work(&rwork->work); | |
3214 | } | |
3215 | } | |
3216 | EXPORT_SYMBOL(flush_rcu_work); | |
3217 | ||
3218 | static bool __cancel_work(struct work_struct *work, bool is_dwork) | |
3219 | { | |
3220 | unsigned long flags; | |
3221 | int ret; | |
3222 | ||
3223 | do { | |
3224 | ret = try_to_grab_pending(work, is_dwork, &flags); | |
3225 | } while (unlikely(ret == -EAGAIN)); | |
3226 | ||
3227 | if (unlikely(ret < 0)) | |
3228 | return false; | |
3229 | ||
3230 | set_work_pool_and_clear_pending(work, get_work_pool_id(work)); | |
3231 | local_irq_restore(flags); | |
3232 | return ret; | |
3233 | } | |
3234 | ||
3235 | /** | |
3236 | * cancel_delayed_work - cancel a delayed work | |
3237 | * @dwork: delayed_work to cancel | |
3238 | * | |
3239 | * Kill off a pending delayed_work. | |
3240 | * | |
3241 | * Return: %true if @dwork was pending and canceled; %false if it wasn't | |
3242 | * pending. | |
3243 | * | |
3244 | * Note: | |
3245 | * The work callback function may still be running on return, unless | |
3246 | * it returns %true and the work doesn't re-arm itself. Explicitly flush or | |
3247 | * use cancel_delayed_work_sync() to wait on it. | |
3248 | * | |
3249 | * This function is safe to call from any context including IRQ handler. | |
3250 | */ | |
3251 | bool cancel_delayed_work(struct delayed_work *dwork) | |
3252 | { | |
3253 | return __cancel_work(&dwork->work, true); | |
3254 | } | |
3255 | EXPORT_SYMBOL(cancel_delayed_work); | |
3256 | ||
3257 | /** | |
3258 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish | |
3259 | * @dwork: the delayed work cancel | |
3260 | * | |
3261 | * This is cancel_work_sync() for delayed works. | |
3262 | * | |
3263 | * Return: | |
3264 | * %true if @dwork was pending, %false otherwise. | |
3265 | */ | |
3266 | bool cancel_delayed_work_sync(struct delayed_work *dwork) | |
3267 | { | |
3268 | return __cancel_work_timer(&dwork->work, true); | |
3269 | } | |
3270 | EXPORT_SYMBOL(cancel_delayed_work_sync); | |
3271 | ||
3272 | /** | |
3273 | * schedule_on_each_cpu - execute a function synchronously on each online CPU | |
3274 | * @func: the function to call | |
3275 | * | |
3276 | * schedule_on_each_cpu() executes @func on each online CPU using the | |
3277 | * system workqueue and blocks until all CPUs have completed. | |
3278 | * schedule_on_each_cpu() is very slow. | |
3279 | * | |
3280 | * Return: | |
3281 | * 0 on success, -errno on failure. | |
3282 | */ | |
3283 | int schedule_on_each_cpu(work_func_t func) | |
3284 | { | |
3285 | int cpu; | |
3286 | struct work_struct __percpu *works; | |
3287 | ||
3288 | works = alloc_percpu(struct work_struct); | |
3289 | if (!works) | |
3290 | return -ENOMEM; | |
3291 | ||
3292 | get_online_cpus(); | |
3293 | ||
3294 | for_each_online_cpu(cpu) { | |
3295 | struct work_struct *work = per_cpu_ptr(works, cpu); | |
3296 | ||
3297 | INIT_WORK(work, func); | |
3298 | schedule_work_on(cpu, work); | |
3299 | } | |
3300 | ||
3301 | for_each_online_cpu(cpu) | |
3302 | flush_work(per_cpu_ptr(works, cpu)); | |
3303 | ||
3304 | put_online_cpus(); | |
3305 | free_percpu(works); | |
3306 | return 0; | |
3307 | } | |
3308 | ||
3309 | /** | |
3310 | * execute_in_process_context - reliably execute the routine with user context | |
3311 | * @fn: the function to execute | |
3312 | * @ew: guaranteed storage for the execute work structure (must | |
3313 | * be available when the work executes) | |
3314 | * | |
3315 | * Executes the function immediately if process context is available, | |
3316 | * otherwise schedules the function for delayed execution. | |
3317 | * | |
3318 | * Return: 0 - function was executed | |
3319 | * 1 - function was scheduled for execution | |
3320 | */ | |
3321 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) | |
3322 | { | |
3323 | if (!in_interrupt()) { | |
3324 | fn(&ew->work); | |
3325 | return 0; | |
3326 | } | |
3327 | ||
3328 | INIT_WORK(&ew->work, fn); | |
3329 | schedule_work(&ew->work); | |
3330 | ||
3331 | return 1; | |
3332 | } | |
3333 | EXPORT_SYMBOL_GPL(execute_in_process_context); | |
3334 | ||
3335 | /** | |
3336 | * free_workqueue_attrs - free a workqueue_attrs | |
3337 | * @attrs: workqueue_attrs to free | |
3338 | * | |
3339 | * Undo alloc_workqueue_attrs(). | |
3340 | */ | |
3341 | void free_workqueue_attrs(struct workqueue_attrs *attrs) | |
3342 | { | |
3343 | if (attrs) { | |
3344 | free_cpumask_var(attrs->cpumask); | |
3345 | kfree(attrs); | |
3346 | } | |
3347 | } | |
3348 | ||
3349 | /** | |
3350 | * alloc_workqueue_attrs - allocate a workqueue_attrs | |
3351 | * | |
3352 | * Allocate a new workqueue_attrs, initialize with default settings and | |
3353 | * return it. | |
3354 | * | |
3355 | * Return: The allocated new workqueue_attr on success. %NULL on failure. | |
3356 | */ | |
3357 | struct workqueue_attrs *alloc_workqueue_attrs(void) | |
3358 | { | |
3359 | struct workqueue_attrs *attrs; | |
3360 | ||
3361 | attrs = kzalloc(sizeof(*attrs), GFP_KERNEL); | |
3362 | if (!attrs) | |
3363 | goto fail; | |
3364 | if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL)) | |
3365 | goto fail; | |
3366 | ||
3367 | cpumask_copy(attrs->cpumask, cpu_possible_mask); | |
3368 | return attrs; | |
3369 | fail: | |
3370 | free_workqueue_attrs(attrs); | |
3371 | return NULL; | |
3372 | } | |
3373 | ||
3374 | static void copy_workqueue_attrs(struct workqueue_attrs *to, | |
3375 | const struct workqueue_attrs *from) | |
3376 | { | |
3377 | to->nice = from->nice; | |
3378 | cpumask_copy(to->cpumask, from->cpumask); | |
3379 | /* | |
3380 | * Unlike hash and equality test, this function doesn't ignore | |
3381 | * ->no_numa as it is used for both pool and wq attrs. Instead, | |
3382 | * get_unbound_pool() explicitly clears ->no_numa after copying. | |
3383 | */ | |
3384 | to->no_numa = from->no_numa; | |
3385 | } | |
3386 | ||
3387 | /* hash value of the content of @attr */ | |
3388 | static u32 wqattrs_hash(const struct workqueue_attrs *attrs) | |
3389 | { | |
3390 | u32 hash = 0; | |
3391 | ||
3392 | hash = jhash_1word(attrs->nice, hash); | |
3393 | hash = jhash(cpumask_bits(attrs->cpumask), | |
3394 | BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); | |
3395 | return hash; | |
3396 | } | |
3397 | ||
3398 | /* content equality test */ | |
3399 | static bool wqattrs_equal(const struct workqueue_attrs *a, | |
3400 | const struct workqueue_attrs *b) | |
3401 | { | |
3402 | if (a->nice != b->nice) | |
3403 | return false; | |
3404 | if (!cpumask_equal(a->cpumask, b->cpumask)) | |
3405 | return false; | |
3406 | return true; | |
3407 | } | |
3408 | ||
3409 | /** | |
3410 | * init_worker_pool - initialize a newly zalloc'd worker_pool | |
3411 | * @pool: worker_pool to initialize | |
3412 | * | |
3413 | * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. | |
3414 | * | |
3415 | * Return: 0 on success, -errno on failure. Even on failure, all fields | |
3416 | * inside @pool proper are initialized and put_unbound_pool() can be called | |
3417 | * on @pool safely to release it. | |
3418 | */ | |
3419 | static int init_worker_pool(struct worker_pool *pool) | |
3420 | { | |
3421 | spin_lock_init(&pool->lock); | |
3422 | pool->id = -1; | |
3423 | pool->cpu = -1; | |
3424 | pool->node = NUMA_NO_NODE; | |
3425 | pool->flags |= POOL_DISASSOCIATED; | |
3426 | pool->watchdog_ts = jiffies; | |
3427 | INIT_LIST_HEAD(&pool->worklist); | |
3428 | INIT_LIST_HEAD(&pool->idle_list); | |
3429 | hash_init(pool->busy_hash); | |
3430 | ||
3431 | timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE); | |
3432 | ||
3433 | timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0); | |
3434 | ||
3435 | INIT_LIST_HEAD(&pool->workers); | |
3436 | ||
3437 | ida_init(&pool->worker_ida); | |
3438 | INIT_HLIST_NODE(&pool->hash_node); | |
3439 | pool->refcnt = 1; | |
3440 | ||
3441 | /* shouldn't fail above this point */ | |
3442 | pool->attrs = alloc_workqueue_attrs(); | |
3443 | if (!pool->attrs) | |
3444 | return -ENOMEM; | |
3445 | return 0; | |
3446 | } | |
3447 | ||
3448 | #ifdef CONFIG_LOCKDEP | |
3449 | static void wq_init_lockdep(struct workqueue_struct *wq) | |
3450 | { | |
3451 | char *lock_name; | |
3452 | ||
3453 | lockdep_register_key(&wq->key); | |
3454 | lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name); | |
3455 | if (!lock_name) | |
3456 | lock_name = wq->name; | |
3457 | ||
3458 | wq->lock_name = lock_name; | |
3459 | lockdep_init_map(&wq->lockdep_map, lock_name, &wq->key, 0); | |
3460 | } | |
3461 | ||
3462 | static void wq_unregister_lockdep(struct workqueue_struct *wq) | |
3463 | { | |
3464 | lockdep_unregister_key(&wq->key); | |
3465 | } | |
3466 | ||
3467 | static void wq_free_lockdep(struct workqueue_struct *wq) | |
3468 | { | |
3469 | if (wq->lock_name != wq->name) | |
3470 | kfree(wq->lock_name); | |
3471 | } | |
3472 | #else | |
3473 | static void wq_init_lockdep(struct workqueue_struct *wq) | |
3474 | { | |
3475 | } | |
3476 | ||
3477 | static void wq_unregister_lockdep(struct workqueue_struct *wq) | |
3478 | { | |
3479 | } | |
3480 | ||
3481 | static void wq_free_lockdep(struct workqueue_struct *wq) | |
3482 | { | |
3483 | } | |
3484 | #endif | |
3485 | ||
3486 | static void rcu_free_wq(struct rcu_head *rcu) | |
3487 | { | |
3488 | struct workqueue_struct *wq = | |
3489 | container_of(rcu, struct workqueue_struct, rcu); | |
3490 | ||
3491 | wq_free_lockdep(wq); | |
3492 | ||
3493 | if (!(wq->flags & WQ_UNBOUND)) | |
3494 | free_percpu(wq->cpu_pwqs); | |
3495 | else | |
3496 | free_workqueue_attrs(wq->unbound_attrs); | |
3497 | ||
3498 | kfree(wq->rescuer); | |
3499 | kfree(wq); | |
3500 | } | |
3501 | ||
3502 | static void rcu_free_pool(struct rcu_head *rcu) | |
3503 | { | |
3504 | struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); | |
3505 | ||
3506 | ida_destroy(&pool->worker_ida); | |
3507 | free_workqueue_attrs(pool->attrs); | |
3508 | kfree(pool); | |
3509 | } | |
3510 | ||
3511 | /** | |
3512 | * put_unbound_pool - put a worker_pool | |
3513 | * @pool: worker_pool to put | |
3514 | * | |
3515 | * Put @pool. If its refcnt reaches zero, it gets destroyed in RCU | |
3516 | * safe manner. get_unbound_pool() calls this function on its failure path | |
3517 | * and this function should be able to release pools which went through, | |
3518 | * successfully or not, init_worker_pool(). | |
3519 | * | |
3520 | * Should be called with wq_pool_mutex held. | |
3521 | */ | |
3522 | static void put_unbound_pool(struct worker_pool *pool) | |
3523 | { | |
3524 | DECLARE_COMPLETION_ONSTACK(detach_completion); | |
3525 | struct worker *worker; | |
3526 | ||
3527 | lockdep_assert_held(&wq_pool_mutex); | |
3528 | ||
3529 | if (--pool->refcnt) | |
3530 | return; | |
3531 | ||
3532 | /* sanity checks */ | |
3533 | if (WARN_ON(!(pool->cpu < 0)) || | |
3534 | WARN_ON(!list_empty(&pool->worklist))) | |
3535 | return; | |
3536 | ||
3537 | /* release id and unhash */ | |
3538 | if (pool->id >= 0) | |
3539 | idr_remove(&worker_pool_idr, pool->id); | |
3540 | hash_del(&pool->hash_node); | |
3541 | ||
3542 | /* | |
3543 | * Become the manager and destroy all workers. This prevents | |
3544 | * @pool's workers from blocking on attach_mutex. We're the last | |
3545 | * manager and @pool gets freed with the flag set. | |
3546 | */ | |
3547 | spin_lock_irq(&pool->lock); | |
3548 | wait_event_lock_irq(wq_manager_wait, | |
3549 | !(pool->flags & POOL_MANAGER_ACTIVE), pool->lock); | |
3550 | pool->flags |= POOL_MANAGER_ACTIVE; | |
3551 | ||
3552 | while ((worker = first_idle_worker(pool))) | |
3553 | destroy_worker(worker); | |
3554 | WARN_ON(pool->nr_workers || pool->nr_idle); | |
3555 | spin_unlock_irq(&pool->lock); | |
3556 | ||
3557 | mutex_lock(&wq_pool_attach_mutex); | |
3558 | if (!list_empty(&pool->workers)) | |
3559 | pool->detach_completion = &detach_completion; | |
3560 | mutex_unlock(&wq_pool_attach_mutex); | |
3561 | ||
3562 | if (pool->detach_completion) | |
3563 | wait_for_completion(pool->detach_completion); | |
3564 | ||
3565 | /* shut down the timers */ | |
3566 | del_timer_sync(&pool->idle_timer); | |
3567 | del_timer_sync(&pool->mayday_timer); | |
3568 | ||
3569 | /* RCU protected to allow dereferences from get_work_pool() */ | |
3570 | call_rcu(&pool->rcu, rcu_free_pool); | |
3571 | } | |
3572 | ||
3573 | /** | |
3574 | * get_unbound_pool - get a worker_pool with the specified attributes | |
3575 | * @attrs: the attributes of the worker_pool to get | |
3576 | * | |
3577 | * Obtain a worker_pool which has the same attributes as @attrs, bump the | |
3578 | * reference count and return it. If there already is a matching | |
3579 | * worker_pool, it will be used; otherwise, this function attempts to | |
3580 | * create a new one. | |
3581 | * | |
3582 | * Should be called with wq_pool_mutex held. | |
3583 | * | |
3584 | * Return: On success, a worker_pool with the same attributes as @attrs. | |
3585 | * On failure, %NULL. | |
3586 | */ | |
3587 | static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) | |
3588 | { | |
3589 | u32 hash = wqattrs_hash(attrs); | |
3590 | struct worker_pool *pool; | |
3591 | int node; | |
3592 | int target_node = NUMA_NO_NODE; | |
3593 | ||
3594 | lockdep_assert_held(&wq_pool_mutex); | |
3595 | ||
3596 | /* do we already have a matching pool? */ | |
3597 | hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { | |
3598 | if (wqattrs_equal(pool->attrs, attrs)) { | |
3599 | pool->refcnt++; | |
3600 | return pool; | |
3601 | } | |
3602 | } | |
3603 | ||
3604 | /* if cpumask is contained inside a NUMA node, we belong to that node */ | |
3605 | if (wq_numa_enabled) { | |
3606 | for_each_node(node) { | |
3607 | if (cpumask_subset(attrs->cpumask, | |
3608 | wq_numa_possible_cpumask[node])) { | |
3609 | target_node = node; | |
3610 | break; | |
3611 | } | |
3612 | } | |
3613 | } | |
3614 | ||
3615 | /* nope, create a new one */ | |
3616 | pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, target_node); | |
3617 | if (!pool || init_worker_pool(pool) < 0) | |
3618 | goto fail; | |
3619 | ||
3620 | lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ | |
3621 | copy_workqueue_attrs(pool->attrs, attrs); | |
3622 | pool->node = target_node; | |
3623 | ||
3624 | /* | |
3625 | * no_numa isn't a worker_pool attribute, always clear it. See | |
3626 | * 'struct workqueue_attrs' comments for detail. | |
3627 | */ | |
3628 | pool->attrs->no_numa = false; | |
3629 | ||
3630 | if (worker_pool_assign_id(pool) < 0) | |
3631 | goto fail; | |
3632 | ||
3633 | /* create and start the initial worker */ | |
3634 | if (wq_online && !create_worker(pool)) | |
3635 | goto fail; | |
3636 | ||
3637 | /* install */ | |
3638 | hash_add(unbound_pool_hash, &pool->hash_node, hash); | |
3639 | ||
3640 | return pool; | |
3641 | fail: | |
3642 | if (pool) | |
3643 | put_unbound_pool(pool); | |
3644 | return NULL; | |
3645 | } | |
3646 | ||
3647 | static void rcu_free_pwq(struct rcu_head *rcu) | |
3648 | { | |
3649 | kmem_cache_free(pwq_cache, | |
3650 | container_of(rcu, struct pool_workqueue, rcu)); | |
3651 | } | |
3652 | ||
3653 | /* | |
3654 | * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt | |
3655 | * and needs to be destroyed. | |
3656 | */ | |
3657 | static void pwq_unbound_release_workfn(struct work_struct *work) | |
3658 | { | |
3659 | struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, | |
3660 | unbound_release_work); | |
3661 | struct workqueue_struct *wq = pwq->wq; | |
3662 | struct worker_pool *pool = pwq->pool; | |
3663 | bool is_last; | |
3664 | ||
3665 | if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) | |
3666 | return; | |
3667 | ||
3668 | mutex_lock(&wq->mutex); | |
3669 | list_del_rcu(&pwq->pwqs_node); | |
3670 | is_last = list_empty(&wq->pwqs); | |
3671 | mutex_unlock(&wq->mutex); | |
3672 | ||
3673 | mutex_lock(&wq_pool_mutex); | |
3674 | put_unbound_pool(pool); | |
3675 | mutex_unlock(&wq_pool_mutex); | |
3676 | ||
3677 | call_rcu(&pwq->rcu, rcu_free_pwq); | |
3678 | ||
3679 | /* | |
3680 | * If we're the last pwq going away, @wq is already dead and no one | |
3681 | * is gonna access it anymore. Schedule RCU free. | |
3682 | */ | |
3683 | if (is_last) { | |
3684 | wq_unregister_lockdep(wq); | |
3685 | call_rcu(&wq->rcu, rcu_free_wq); | |
3686 | } | |
3687 | } | |
3688 | ||
3689 | /** | |
3690 | * pwq_adjust_max_active - update a pwq's max_active to the current setting | |
3691 | * @pwq: target pool_workqueue | |
3692 | * | |
3693 | * If @pwq isn't freezing, set @pwq->max_active to the associated | |
3694 | * workqueue's saved_max_active and activate delayed work items | |
3695 | * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. | |
3696 | */ | |
3697 | static void pwq_adjust_max_active(struct pool_workqueue *pwq) | |
3698 | { | |
3699 | struct workqueue_struct *wq = pwq->wq; | |
3700 | bool freezable = wq->flags & WQ_FREEZABLE; | |
3701 | unsigned long flags; | |
3702 | ||
3703 | /* for @wq->saved_max_active */ | |
3704 | lockdep_assert_held(&wq->mutex); | |
3705 | ||
3706 | /* fast exit for non-freezable wqs */ | |
3707 | if (!freezable && pwq->max_active == wq->saved_max_active) | |
3708 | return; | |
3709 | ||
3710 | /* this function can be called during early boot w/ irq disabled */ | |
3711 | spin_lock_irqsave(&pwq->pool->lock, flags); | |
3712 | ||
3713 | /* | |
3714 | * During [un]freezing, the caller is responsible for ensuring that | |
3715 | * this function is called at least once after @workqueue_freezing | |
3716 | * is updated and visible. | |
3717 | */ | |
3718 | if (!freezable || !workqueue_freezing) { | |
3719 | pwq->max_active = wq->saved_max_active; | |
3720 | ||
3721 | while (!list_empty(&pwq->delayed_works) && | |
3722 | pwq->nr_active < pwq->max_active) | |
3723 | pwq_activate_first_delayed(pwq); | |
3724 | ||
3725 | /* | |
3726 | * Need to kick a worker after thawed or an unbound wq's | |
3727 | * max_active is bumped. It's a slow path. Do it always. | |
3728 | */ | |
3729 | wake_up_worker(pwq->pool); | |
3730 | } else { | |
3731 | pwq->max_active = 0; | |
3732 | } | |
3733 | ||
3734 | spin_unlock_irqrestore(&pwq->pool->lock, flags); | |
3735 | } | |
3736 | ||
3737 | /* initialize newly alloced @pwq which is associated with @wq and @pool */ | |
3738 | static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, | |
3739 | struct worker_pool *pool) | |
3740 | { | |
3741 | BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); | |
3742 | ||
3743 | memset(pwq, 0, sizeof(*pwq)); | |
3744 | ||
3745 | pwq->pool = pool; | |
3746 | pwq->wq = wq; | |
3747 | pwq->flush_color = -1; | |
3748 | pwq->refcnt = 1; | |
3749 | INIT_LIST_HEAD(&pwq->delayed_works); | |
3750 | INIT_LIST_HEAD(&pwq->pwqs_node); | |
3751 | INIT_LIST_HEAD(&pwq->mayday_node); | |
3752 | INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); | |
3753 | } | |
3754 | ||
3755 | /* sync @pwq with the current state of its associated wq and link it */ | |
3756 | static void link_pwq(struct pool_workqueue *pwq) | |
3757 | { | |
3758 | struct workqueue_struct *wq = pwq->wq; | |
3759 | ||
3760 | lockdep_assert_held(&wq->mutex); | |
3761 | ||
3762 | /* may be called multiple times, ignore if already linked */ | |
3763 | if (!list_empty(&pwq->pwqs_node)) | |
3764 | return; | |
3765 | ||
3766 | /* set the matching work_color */ | |
3767 | pwq->work_color = wq->work_color; | |
3768 | ||
3769 | /* sync max_active to the current setting */ | |
3770 | pwq_adjust_max_active(pwq); | |
3771 | ||
3772 | /* link in @pwq */ | |
3773 | list_add_rcu(&pwq->pwqs_node, &wq->pwqs); | |
3774 | } | |
3775 | ||
3776 | /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ | |
3777 | static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, | |
3778 | const struct workqueue_attrs *attrs) | |
3779 | { | |
3780 | struct worker_pool *pool; | |
3781 | struct pool_workqueue *pwq; | |
3782 | ||
3783 | lockdep_assert_held(&wq_pool_mutex); | |
3784 | ||
3785 | pool = get_unbound_pool(attrs); | |
3786 | if (!pool) | |
3787 | return NULL; | |
3788 | ||
3789 | pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); | |
3790 | if (!pwq) { | |
3791 | put_unbound_pool(pool); | |
3792 | return NULL; | |
3793 | } | |
3794 | ||
3795 | init_pwq(pwq, wq, pool); | |
3796 | return pwq; | |
3797 | } | |
3798 | ||
3799 | /** | |
3800 | * wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node | |
3801 | * @attrs: the wq_attrs of the default pwq of the target workqueue | |
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. | |
3809 | * | |
3810 | * If NUMA affinity is not enabled, @attrs->cpumask is always used. If | |
3811 | * enabled and @node has online CPUs requested by @attrs, the returned | |
3812 | * cpumask is the intersection of the possible CPUs of @node and | |
3813 | * @attrs->cpumask. | |
3814 | * | |
3815 | * The caller is responsible for ensuring that the cpumask of @node stays | |
3816 | * stable. | |
3817 | * | |
3818 | * Return: %true if the resulting @cpumask is different from @attrs->cpumask, | |
3819 | * %false if equal. | |
3820 | */ | |
3821 | static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, | |
3822 | int cpu_going_down, cpumask_t *cpumask) | |
3823 | { | |
3824 | if (!wq_numa_enabled || attrs->no_numa) | |
3825 | goto use_dfl; | |
3826 | ||
3827 | /* does @node have any online CPUs @attrs wants? */ | |
3828 | cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); | |
3829 | if (cpu_going_down >= 0) | |
3830 | cpumask_clear_cpu(cpu_going_down, cpumask); | |
3831 | ||
3832 | if (cpumask_empty(cpumask)) | |
3833 | goto use_dfl; | |
3834 | ||
3835 | /* yeap, return possible CPUs in @node that @attrs wants */ | |
3836 | cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); | |
3837 | ||
3838 | if (cpumask_empty(cpumask)) { | |
3839 | pr_warn_once("WARNING: workqueue cpumask: online intersect > " | |
3840 | "possible intersect\n"); | |
3841 | return false; | |
3842 | } | |
3843 | ||
3844 | return !cpumask_equal(cpumask, attrs->cpumask); | |
3845 | ||
3846 | use_dfl: | |
3847 | cpumask_copy(cpumask, attrs->cpumask); | |
3848 | return false; | |
3849 | } | |
3850 | ||
3851 | /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ | |
3852 | static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, | |
3853 | int node, | |
3854 | struct pool_workqueue *pwq) | |
3855 | { | |
3856 | struct pool_workqueue *old_pwq; | |
3857 | ||
3858 | lockdep_assert_held(&wq_pool_mutex); | |
3859 | lockdep_assert_held(&wq->mutex); | |
3860 | ||
3861 | /* link_pwq() can handle duplicate calls */ | |
3862 | link_pwq(pwq); | |
3863 | ||
3864 | old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); | |
3865 | rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); | |
3866 | return old_pwq; | |
3867 | } | |
3868 | ||
3869 | /* context to store the prepared attrs & pwqs before applying */ | |
3870 | struct apply_wqattrs_ctx { | |
3871 | struct workqueue_struct *wq; /* target workqueue */ | |
3872 | struct workqueue_attrs *attrs; /* attrs to apply */ | |
3873 | struct list_head list; /* queued for batching commit */ | |
3874 | struct pool_workqueue *dfl_pwq; | |
3875 | struct pool_workqueue *pwq_tbl[]; | |
3876 | }; | |
3877 | ||
3878 | /* free the resources after success or abort */ | |
3879 | static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) | |
3880 | { | |
3881 | if (ctx) { | |
3882 | int node; | |
3883 | ||
3884 | for_each_node(node) | |
3885 | put_pwq_unlocked(ctx->pwq_tbl[node]); | |
3886 | put_pwq_unlocked(ctx->dfl_pwq); | |
3887 | ||
3888 | free_workqueue_attrs(ctx->attrs); | |
3889 | ||
3890 | kfree(ctx); | |
3891 | } | |
3892 | } | |
3893 | ||
3894 | /* allocate the attrs and pwqs for later installation */ | |
3895 | static struct apply_wqattrs_ctx * | |
3896 | apply_wqattrs_prepare(struct workqueue_struct *wq, | |
3897 | const struct workqueue_attrs *attrs) | |
3898 | { | |
3899 | struct apply_wqattrs_ctx *ctx; | |
3900 | struct workqueue_attrs *new_attrs, *tmp_attrs; | |
3901 | int node; | |
3902 | ||
3903 | lockdep_assert_held(&wq_pool_mutex); | |
3904 | ||
3905 | ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_node_ids), GFP_KERNEL); | |
3906 | ||
3907 | new_attrs = alloc_workqueue_attrs(); | |
3908 | tmp_attrs = alloc_workqueue_attrs(); | |
3909 | if (!ctx || !new_attrs || !tmp_attrs) | |
3910 | goto out_free; | |
3911 | ||
3912 | /* | |
3913 | * Calculate the attrs of the default pwq. | |
3914 | * If the user configured cpumask doesn't overlap with the | |
3915 | * wq_unbound_cpumask, we fallback to the wq_unbound_cpumask. | |
3916 | */ | |
3917 | copy_workqueue_attrs(new_attrs, attrs); | |
3918 | cpumask_and(new_attrs->cpumask, new_attrs->cpumask, wq_unbound_cpumask); | |
3919 | if (unlikely(cpumask_empty(new_attrs->cpumask))) | |
3920 | cpumask_copy(new_attrs->cpumask, wq_unbound_cpumask); | |
3921 | ||
3922 | /* | |
3923 | * We may create multiple pwqs with differing cpumasks. Make a | |
3924 | * copy of @new_attrs which will be modified and used to obtain | |
3925 | * pools. | |
3926 | */ | |
3927 | copy_workqueue_attrs(tmp_attrs, new_attrs); | |
3928 | ||
3929 | /* | |
3930 | * If something goes wrong during CPU up/down, we'll fall back to | |
3931 | * the default pwq covering whole @attrs->cpumask. Always create | |
3932 | * it even if we don't use it immediately. | |
3933 | */ | |
3934 | ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs); | |
3935 | if (!ctx->dfl_pwq) | |
3936 | goto out_free; | |
3937 | ||
3938 | for_each_node(node) { | |
3939 | if (wq_calc_node_cpumask(new_attrs, node, -1, tmp_attrs->cpumask)) { | |
3940 | ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); | |
3941 | if (!ctx->pwq_tbl[node]) | |
3942 | goto out_free; | |
3943 | } else { | |
3944 | ctx->dfl_pwq->refcnt++; | |
3945 | ctx->pwq_tbl[node] = ctx->dfl_pwq; | |
3946 | } | |
3947 | } | |
3948 | ||
3949 | /* save the user configured attrs and sanitize it. */ | |
3950 | copy_workqueue_attrs(new_attrs, attrs); | |
3951 | cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); | |
3952 | ctx->attrs = new_attrs; | |
3953 | ||
3954 | ctx->wq = wq; | |
3955 | free_workqueue_attrs(tmp_attrs); | |
3956 | return ctx; | |
3957 | ||
3958 | out_free: | |
3959 | free_workqueue_attrs(tmp_attrs); | |
3960 | free_workqueue_attrs(new_attrs); | |
3961 | apply_wqattrs_cleanup(ctx); | |
3962 | return NULL; | |
3963 | } | |
3964 | ||
3965 | /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ | |
3966 | static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) | |
3967 | { | |
3968 | int node; | |
3969 | ||
3970 | /* all pwqs have been created successfully, let's install'em */ | |
3971 | mutex_lock(&ctx->wq->mutex); | |
3972 | ||
3973 | copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs); | |
3974 | ||
3975 | /* save the previous pwq and install the new one */ | |
3976 | for_each_node(node) | |
3977 | ctx->pwq_tbl[node] = numa_pwq_tbl_install(ctx->wq, node, | |
3978 | ctx->pwq_tbl[node]); | |
3979 | ||
3980 | /* @dfl_pwq might not have been used, ensure it's linked */ | |
3981 | link_pwq(ctx->dfl_pwq); | |
3982 | swap(ctx->wq->dfl_pwq, ctx->dfl_pwq); | |
3983 | ||
3984 | mutex_unlock(&ctx->wq->mutex); | |
3985 | } | |
3986 | ||
3987 | static void apply_wqattrs_lock(void) | |
3988 | { | |
3989 | /* CPUs should stay stable across pwq creations and installations */ | |
3990 | get_online_cpus(); | |
3991 | mutex_lock(&wq_pool_mutex); | |
3992 | } | |
3993 | ||
3994 | static void apply_wqattrs_unlock(void) | |
3995 | { | |
3996 | mutex_unlock(&wq_pool_mutex); | |
3997 | put_online_cpus(); | |
3998 | } | |
3999 | ||
4000 | static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, | |
4001 | const struct workqueue_attrs *attrs) | |
4002 | { | |
4003 | struct apply_wqattrs_ctx *ctx; | |
4004 | ||
4005 | /* only unbound workqueues can change attributes */ | |
4006 | if (WARN_ON(!(wq->flags & WQ_UNBOUND))) | |
4007 | return -EINVAL; | |
4008 | ||
4009 | /* creating multiple pwqs breaks ordering guarantee */ | |
4010 | if (!list_empty(&wq->pwqs)) { | |
4011 | if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) | |
4012 | return -EINVAL; | |
4013 | ||
4014 | wq->flags &= ~__WQ_ORDERED; | |
4015 | } | |
4016 | ||
4017 | ctx = apply_wqattrs_prepare(wq, attrs); | |
4018 | if (!ctx) | |
4019 | return -ENOMEM; | |
4020 | ||
4021 | /* the ctx has been prepared successfully, let's commit it */ | |
4022 | apply_wqattrs_commit(ctx); | |
4023 | apply_wqattrs_cleanup(ctx); | |
4024 | ||
4025 | return 0; | |
4026 | } | |
4027 | ||
4028 | /** | |
4029 | * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue | |
4030 | * @wq: the target workqueue | |
4031 | * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() | |
4032 | * | |
4033 | * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA | |
4034 | * machines, this function maps a separate pwq to each NUMA node with | |
4035 | * possibles CPUs in @attrs->cpumask so that work items are affine to the | |
4036 | * NUMA node it was issued on. Older pwqs are released as in-flight work | |
4037 | * items finish. Note that a work item which repeatedly requeues itself | |
4038 | * back-to-back will stay on its current pwq. | |
4039 | * | |
4040 | * Performs GFP_KERNEL allocations. | |
4041 | * | |
4042 | * Assumes caller has CPU hotplug read exclusion, i.e. get_online_cpus(). | |
4043 | * | |
4044 | * Return: 0 on success and -errno on failure. | |
4045 | */ | |
4046 | int apply_workqueue_attrs(struct workqueue_struct *wq, | |
4047 | const struct workqueue_attrs *attrs) | |
4048 | { | |
4049 | int ret; | |
4050 | ||
4051 | lockdep_assert_cpus_held(); | |
4052 | ||
4053 | mutex_lock(&wq_pool_mutex); | |
4054 | ret = apply_workqueue_attrs_locked(wq, attrs); | |
4055 | mutex_unlock(&wq_pool_mutex); | |
4056 | ||
4057 | return ret; | |
4058 | } | |
4059 | ||
4060 | /** | |
4061 | * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug | |
4062 | * @wq: the target workqueue | |
4063 | * @cpu: the CPU coming up or going down | |
4064 | * @online: whether @cpu is coming up or going down | |
4065 | * | |
4066 | * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and | |
4067 | * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of | |
4068 | * @wq accordingly. | |
4069 | * | |
4070 | * If NUMA affinity can't be adjusted due to memory allocation failure, it | |
4071 | * falls back to @wq->dfl_pwq which may not be optimal but is always | |
4072 | * correct. | |
4073 | * | |
4074 | * Note that when the last allowed CPU of a NUMA node goes offline for a | |
4075 | * workqueue with a cpumask spanning multiple nodes, the workers which were | |
4076 | * already executing the work items for the workqueue will lose their CPU | |
4077 | * affinity and may execute on any CPU. This is similar to how per-cpu | |
4078 | * workqueues behave on CPU_DOWN. If a workqueue user wants strict | |
4079 | * affinity, it's the user's responsibility to flush the work item from | |
4080 | * CPU_DOWN_PREPARE. | |
4081 | */ | |
4082 | static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, | |
4083 | bool online) | |
4084 | { | |
4085 | int node = cpu_to_node(cpu); | |
4086 | int cpu_off = online ? -1 : cpu; | |
4087 | struct pool_workqueue *old_pwq = NULL, *pwq; | |
4088 | struct workqueue_attrs *target_attrs; | |
4089 | cpumask_t *cpumask; | |
4090 | ||
4091 | lockdep_assert_held(&wq_pool_mutex); | |
4092 | ||
4093 | if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND) || | |
4094 | wq->unbound_attrs->no_numa) | |
4095 | return; | |
4096 | ||
4097 | /* | |
4098 | * We don't wanna alloc/free wq_attrs for each wq for each CPU. | |
4099 | * Let's use a preallocated one. The following buf is protected by | |
4100 | * CPU hotplug exclusion. | |
4101 | */ | |
4102 | target_attrs = wq_update_unbound_numa_attrs_buf; | |
4103 | cpumask = target_attrs->cpumask; | |
4104 | ||
4105 | copy_workqueue_attrs(target_attrs, wq->unbound_attrs); | |
4106 | pwq = unbound_pwq_by_node(wq, node); | |
4107 | ||
4108 | /* | |
4109 | * Let's determine what needs to be done. If the target cpumask is | |
4110 | * different from the default pwq's, we need to compare it to @pwq's | |
4111 | * and create a new one if they don't match. If the target cpumask | |
4112 | * equals the default pwq's, the default pwq should be used. | |
4113 | */ | |
4114 | if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) { | |
4115 | if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) | |
4116 | return; | |
4117 | } else { | |
4118 | goto use_dfl_pwq; | |
4119 | } | |
4120 | ||
4121 | /* create a new pwq */ | |
4122 | pwq = alloc_unbound_pwq(wq, target_attrs); | |
4123 | if (!pwq) { | |
4124 | pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", | |
4125 | wq->name); | |
4126 | goto use_dfl_pwq; | |
4127 | } | |
4128 | ||
4129 | /* Install the new pwq. */ | |
4130 | mutex_lock(&wq->mutex); | |
4131 | old_pwq = numa_pwq_tbl_install(wq, node, pwq); | |
4132 | goto out_unlock; | |
4133 | ||
4134 | use_dfl_pwq: | |
4135 | mutex_lock(&wq->mutex); | |
4136 | spin_lock_irq(&wq->dfl_pwq->pool->lock); | |
4137 | get_pwq(wq->dfl_pwq); | |
4138 | spin_unlock_irq(&wq->dfl_pwq->pool->lock); | |
4139 | old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); | |
4140 | out_unlock: | |
4141 | mutex_unlock(&wq->mutex); | |
4142 | put_pwq_unlocked(old_pwq); | |
4143 | } | |
4144 | ||
4145 | static int alloc_and_link_pwqs(struct workqueue_struct *wq) | |
4146 | { | |
4147 | bool highpri = wq->flags & WQ_HIGHPRI; | |
4148 | int cpu, ret; | |
4149 | ||
4150 | if (!(wq->flags & WQ_UNBOUND)) { | |
4151 | wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); | |
4152 | if (!wq->cpu_pwqs) | |
4153 | return -ENOMEM; | |
4154 | ||
4155 | for_each_possible_cpu(cpu) { | |
4156 | struct pool_workqueue *pwq = | |
4157 | per_cpu_ptr(wq->cpu_pwqs, cpu); | |
4158 | struct worker_pool *cpu_pools = | |
4159 | per_cpu(cpu_worker_pools, cpu); | |
4160 | ||
4161 | init_pwq(pwq, wq, &cpu_pools[highpri]); | |
4162 | ||
4163 | mutex_lock(&wq->mutex); | |
4164 | link_pwq(pwq); | |
4165 | mutex_unlock(&wq->mutex); | |
4166 | } | |
4167 | return 0; | |
4168 | } | |
4169 | ||
4170 | get_online_cpus(); | |
4171 | if (wq->flags & __WQ_ORDERED) { | |
4172 | ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); | |
4173 | /* there should only be single pwq for ordering guarantee */ | |
4174 | WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || | |
4175 | wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), | |
4176 | "ordering guarantee broken for workqueue %s\n", wq->name); | |
4177 | } else { | |
4178 | ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); | |
4179 | } | |
4180 | put_online_cpus(); | |
4181 | ||
4182 | return ret; | |
4183 | } | |
4184 | ||
4185 | static int wq_clamp_max_active(int max_active, unsigned int flags, | |
4186 | const char *name) | |
4187 | { | |
4188 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; | |
4189 | ||
4190 | if (max_active < 1 || max_active > lim) | |
4191 | pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", | |
4192 | max_active, name, 1, lim); | |
4193 | ||
4194 | return clamp_val(max_active, 1, lim); | |
4195 | } | |
4196 | ||
4197 | /* | |
4198 | * Workqueues which may be used during memory reclaim should have a rescuer | |
4199 | * to guarantee forward progress. | |
4200 | */ | |
4201 | static int init_rescuer(struct workqueue_struct *wq) | |
4202 | { | |
4203 | struct worker *rescuer; | |
4204 | int ret; | |
4205 | ||
4206 | if (!(wq->flags & WQ_MEM_RECLAIM)) | |
4207 | return 0; | |
4208 | ||
4209 | rescuer = alloc_worker(NUMA_NO_NODE); | |
4210 | if (!rescuer) | |
4211 | return -ENOMEM; | |
4212 | ||
4213 | rescuer->rescue_wq = wq; | |
4214 | rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name); | |
4215 | ret = PTR_ERR_OR_ZERO(rescuer->task); | |
4216 | if (ret) { | |
4217 | kfree(rescuer); | |
4218 | return ret; | |
4219 | } | |
4220 | ||
4221 | wq->rescuer = rescuer; | |
4222 | kthread_bind_mask(rescuer->task, cpu_possible_mask); | |
4223 | wake_up_process(rescuer->task); | |
4224 | ||
4225 | return 0; | |
4226 | } | |
4227 | ||
4228 | __printf(1, 4) | |
4229 | struct workqueue_struct *alloc_workqueue(const char *fmt, | |
4230 | unsigned int flags, | |
4231 | int max_active, ...) | |
4232 | { | |
4233 | size_t tbl_size = 0; | |
4234 | va_list args; | |
4235 | struct workqueue_struct *wq; | |
4236 | struct pool_workqueue *pwq; | |
4237 | ||
4238 | /* | |
4239 | * Unbound && max_active == 1 used to imply ordered, which is no | |
4240 | * longer the case on NUMA machines due to per-node pools. While | |
4241 | * alloc_ordered_workqueue() is the right way to create an ordered | |
4242 | * workqueue, keep the previous behavior to avoid subtle breakages | |
4243 | * on NUMA. | |
4244 | */ | |
4245 | if ((flags & WQ_UNBOUND) && max_active == 1) | |
4246 | flags |= __WQ_ORDERED; | |
4247 | ||
4248 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ | |
4249 | if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) | |
4250 | flags |= WQ_UNBOUND; | |
4251 | ||
4252 | /* allocate wq and format name */ | |
4253 | if (flags & WQ_UNBOUND) | |
4254 | tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]); | |
4255 | ||
4256 | wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); | |
4257 | if (!wq) | |
4258 | return NULL; | |
4259 | ||
4260 | if (flags & WQ_UNBOUND) { | |
4261 | wq->unbound_attrs = alloc_workqueue_attrs(); | |
4262 | if (!wq->unbound_attrs) | |
4263 | goto err_free_wq; | |
4264 | } | |
4265 | ||
4266 | va_start(args, max_active); | |
4267 | vsnprintf(wq->name, sizeof(wq->name), fmt, args); | |
4268 | va_end(args); | |
4269 | ||
4270 | max_active = max_active ?: WQ_DFL_ACTIVE; | |
4271 | max_active = wq_clamp_max_active(max_active, flags, wq->name); | |
4272 | ||
4273 | /* init wq */ | |
4274 | wq->flags = flags; | |
4275 | wq->saved_max_active = max_active; | |
4276 | mutex_init(&wq->mutex); | |
4277 | atomic_set(&wq->nr_pwqs_to_flush, 0); | |
4278 | INIT_LIST_HEAD(&wq->pwqs); | |
4279 | INIT_LIST_HEAD(&wq->flusher_queue); | |
4280 | INIT_LIST_HEAD(&wq->flusher_overflow); | |
4281 | INIT_LIST_HEAD(&wq->maydays); | |
4282 | ||
4283 | wq_init_lockdep(wq); | |
4284 | INIT_LIST_HEAD(&wq->list); | |
4285 | ||
4286 | if (alloc_and_link_pwqs(wq) < 0) | |
4287 | goto err_unreg_lockdep; | |
4288 | ||
4289 | if (wq_online && init_rescuer(wq) < 0) | |
4290 | goto err_destroy; | |
4291 | ||
4292 | if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) | |
4293 | goto err_destroy; | |
4294 | ||
4295 | /* | |
4296 | * wq_pool_mutex protects global freeze state and workqueues list. | |
4297 | * Grab it, adjust max_active and add the new @wq to workqueues | |
4298 | * list. | |
4299 | */ | |
4300 | mutex_lock(&wq_pool_mutex); | |
4301 | ||
4302 | mutex_lock(&wq->mutex); | |
4303 | for_each_pwq(pwq, wq) | |
4304 | pwq_adjust_max_active(pwq); | |
4305 | mutex_unlock(&wq->mutex); | |
4306 | ||
4307 | list_add_tail_rcu(&wq->list, &workqueues); | |
4308 | ||
4309 | mutex_unlock(&wq_pool_mutex); | |
4310 | ||
4311 | return wq; | |
4312 | ||
4313 | err_unreg_lockdep: | |
4314 | wq_unregister_lockdep(wq); | |
4315 | wq_free_lockdep(wq); | |
4316 | err_free_wq: | |
4317 | free_workqueue_attrs(wq->unbound_attrs); | |
4318 | kfree(wq); | |
4319 | return NULL; | |
4320 | err_destroy: | |
4321 | destroy_workqueue(wq); | |
4322 | return NULL; | |
4323 | } | |
4324 | EXPORT_SYMBOL_GPL(alloc_workqueue); | |
4325 | ||
4326 | /** | |
4327 | * destroy_workqueue - safely terminate a workqueue | |
4328 | * @wq: target workqueue | |
4329 | * | |
4330 | * Safely destroy a workqueue. All work currently pending will be done first. | |
4331 | */ | |
4332 | void destroy_workqueue(struct workqueue_struct *wq) | |
4333 | { | |
4334 | struct pool_workqueue *pwq; | |
4335 | int node; | |
4336 | ||
4337 | /* | |
4338 | * Remove it from sysfs first so that sanity check failure doesn't | |
4339 | * lead to sysfs name conflicts. | |
4340 | */ | |
4341 | workqueue_sysfs_unregister(wq); | |
4342 | ||
4343 | /* drain it before proceeding with destruction */ | |
4344 | drain_workqueue(wq); | |
4345 | ||
4346 | /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ | |
4347 | if (wq->rescuer) { | |
4348 | struct worker *rescuer = wq->rescuer; | |
4349 | ||
4350 | /* this prevents new queueing */ | |
4351 | spin_lock_irq(&wq_mayday_lock); | |
4352 | wq->rescuer = NULL; | |
4353 | spin_unlock_irq(&wq_mayday_lock); | |
4354 | ||
4355 | /* rescuer will empty maydays list before exiting */ | |
4356 | kthread_stop(rescuer->task); | |
4357 | kfree(rescuer); | |
4358 | } | |
4359 | ||
4360 | /* sanity checks */ | |
4361 | mutex_lock(&wq->mutex); | |
4362 | for_each_pwq(pwq, wq) { | |
4363 | int i; | |
4364 | ||
4365 | for (i = 0; i < WORK_NR_COLORS; i++) { | |
4366 | if (WARN_ON(pwq->nr_in_flight[i])) { | |
4367 | mutex_unlock(&wq->mutex); | |
4368 | show_workqueue_state(); | |
4369 | return; | |
4370 | } | |
4371 | } | |
4372 | ||
4373 | if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) || | |
4374 | WARN_ON(pwq->nr_active) || | |
4375 | WARN_ON(!list_empty(&pwq->delayed_works))) { | |
4376 | mutex_unlock(&wq->mutex); | |
4377 | show_workqueue_state(); | |
4378 | return; | |
4379 | } | |
4380 | } | |
4381 | mutex_unlock(&wq->mutex); | |
4382 | ||
4383 | /* | |
4384 | * wq list is used to freeze wq, remove from list after | |
4385 | * flushing is complete in case freeze races us. | |
4386 | */ | |
4387 | mutex_lock(&wq_pool_mutex); | |
4388 | list_del_rcu(&wq->list); | |
4389 | mutex_unlock(&wq_pool_mutex); | |
4390 | ||
4391 | if (!(wq->flags & WQ_UNBOUND)) { | |
4392 | wq_unregister_lockdep(wq); | |
4393 | /* | |
4394 | * The base ref is never dropped on per-cpu pwqs. Directly | |
4395 | * schedule RCU free. | |
4396 | */ | |
4397 | call_rcu(&wq->rcu, rcu_free_wq); | |
4398 | } else { | |
4399 | /* | |
4400 | * We're the sole accessor of @wq at this point. Directly | |
4401 | * access numa_pwq_tbl[] and dfl_pwq to put the base refs. | |
4402 | * @wq will be freed when the last pwq is released. | |
4403 | */ | |
4404 | for_each_node(node) { | |
4405 | pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); | |
4406 | RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); | |
4407 | put_pwq_unlocked(pwq); | |
4408 | } | |
4409 | ||
4410 | /* | |
4411 | * Put dfl_pwq. @wq may be freed any time after dfl_pwq is | |
4412 | * put. Don't access it afterwards. | |
4413 | */ | |
4414 | pwq = wq->dfl_pwq; | |
4415 | wq->dfl_pwq = NULL; | |
4416 | put_pwq_unlocked(pwq); | |
4417 | } | |
4418 | } | |
4419 | EXPORT_SYMBOL_GPL(destroy_workqueue); | |
4420 | ||
4421 | /** | |
4422 | * workqueue_set_max_active - adjust max_active of a workqueue | |
4423 | * @wq: target workqueue | |
4424 | * @max_active: new max_active value. | |
4425 | * | |
4426 | * Set max_active of @wq to @max_active. | |
4427 | * | |
4428 | * CONTEXT: | |
4429 | * Don't call from IRQ context. | |
4430 | */ | |
4431 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) | |
4432 | { | |
4433 | struct pool_workqueue *pwq; | |
4434 | ||
4435 | /* disallow meddling with max_active for ordered workqueues */ | |
4436 | if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) | |
4437 | return; | |
4438 | ||
4439 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); | |
4440 | ||
4441 | mutex_lock(&wq->mutex); | |
4442 | ||
4443 | wq->flags &= ~__WQ_ORDERED; | |
4444 | wq->saved_max_active = max_active; | |
4445 | ||
4446 | for_each_pwq(pwq, wq) | |
4447 | pwq_adjust_max_active(pwq); | |
4448 | ||
4449 | mutex_unlock(&wq->mutex); | |
4450 | } | |
4451 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); | |
4452 | ||
4453 | /** | |
4454 | * current_work - retrieve %current task's work struct | |
4455 | * | |
4456 | * Determine if %current task is a workqueue worker and what it's working on. | |
4457 | * Useful to find out the context that the %current task is running in. | |
4458 | * | |
4459 | * Return: work struct if %current task is a workqueue worker, %NULL otherwise. | |
4460 | */ | |
4461 | struct work_struct *current_work(void) | |
4462 | { | |
4463 | struct worker *worker = current_wq_worker(); | |
4464 | ||
4465 | return worker ? worker->current_work : NULL; | |
4466 | } | |
4467 | EXPORT_SYMBOL(current_work); | |
4468 | ||
4469 | /** | |
4470 | * current_is_workqueue_rescuer - is %current workqueue rescuer? | |
4471 | * | |
4472 | * Determine whether %current is a workqueue rescuer. Can be used from | |
4473 | * work functions to determine whether it's being run off the rescuer task. | |
4474 | * | |
4475 | * Return: %true if %current is a workqueue rescuer. %false otherwise. | |
4476 | */ | |
4477 | bool current_is_workqueue_rescuer(void) | |
4478 | { | |
4479 | struct worker *worker = current_wq_worker(); | |
4480 | ||
4481 | return worker && worker->rescue_wq; | |
4482 | } | |
4483 | ||
4484 | /** | |
4485 | * workqueue_congested - test whether a workqueue is congested | |
4486 | * @cpu: CPU in question | |
4487 | * @wq: target workqueue | |
4488 | * | |
4489 | * Test whether @wq's cpu workqueue for @cpu is congested. There is | |
4490 | * no synchronization around this function and the test result is | |
4491 | * unreliable and only useful as advisory hints or for debugging. | |
4492 | * | |
4493 | * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. | |
4494 | * Note that both per-cpu and unbound workqueues may be associated with | |
4495 | * multiple pool_workqueues which have separate congested states. A | |
4496 | * workqueue being congested on one CPU doesn't mean the workqueue is also | |
4497 | * contested on other CPUs / NUMA nodes. | |
4498 | * | |
4499 | * Return: | |
4500 | * %true if congested, %false otherwise. | |
4501 | */ | |
4502 | bool workqueue_congested(int cpu, struct workqueue_struct *wq) | |
4503 | { | |
4504 | struct pool_workqueue *pwq; | |
4505 | bool ret; | |
4506 | ||
4507 | rcu_read_lock(); | |
4508 | preempt_disable(); | |
4509 | ||
4510 | if (cpu == WORK_CPU_UNBOUND) | |
4511 | cpu = smp_processor_id(); | |
4512 | ||
4513 | if (!(wq->flags & WQ_UNBOUND)) | |
4514 | pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); | |
4515 | else | |
4516 | pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); | |
4517 | ||
4518 | ret = !list_empty(&pwq->delayed_works); | |
4519 | preempt_enable(); | |
4520 | rcu_read_unlock(); | |
4521 | ||
4522 | return ret; | |
4523 | } | |
4524 | EXPORT_SYMBOL_GPL(workqueue_congested); | |
4525 | ||
4526 | /** | |
4527 | * work_busy - test whether a work is currently pending or running | |
4528 | * @work: the work to be tested | |
4529 | * | |
4530 | * Test whether @work is currently pending or running. There is no | |
4531 | * synchronization around this function and the test result is | |
4532 | * unreliable and only useful as advisory hints or for debugging. | |
4533 | * | |
4534 | * Return: | |
4535 | * OR'd bitmask of WORK_BUSY_* bits. | |
4536 | */ | |
4537 | unsigned int work_busy(struct work_struct *work) | |
4538 | { | |
4539 | struct worker_pool *pool; | |
4540 | unsigned long flags; | |
4541 | unsigned int ret = 0; | |
4542 | ||
4543 | if (work_pending(work)) | |
4544 | ret |= WORK_BUSY_PENDING; | |
4545 | ||
4546 | rcu_read_lock(); | |
4547 | pool = get_work_pool(work); | |
4548 | if (pool) { | |
4549 | spin_lock_irqsave(&pool->lock, flags); | |
4550 | if (find_worker_executing_work(pool, work)) | |
4551 | ret |= WORK_BUSY_RUNNING; | |
4552 | spin_unlock_irqrestore(&pool->lock, flags); | |
4553 | } | |
4554 | rcu_read_unlock(); | |
4555 | ||
4556 | return ret; | |
4557 | } | |
4558 | EXPORT_SYMBOL_GPL(work_busy); | |
4559 | ||
4560 | /** | |
4561 | * set_worker_desc - set description for the current work item | |
4562 | * @fmt: printf-style format string | |
4563 | * @...: arguments for the format string | |
4564 | * | |
4565 | * This function can be called by a running work function to describe what | |
4566 | * the work item is about. If the worker task gets dumped, this | |
4567 | * information will be printed out together to help debugging. The | |
4568 | * description can be at most WORKER_DESC_LEN including the trailing '\0'. | |
4569 | */ | |
4570 | void set_worker_desc(const char *fmt, ...) | |
4571 | { | |
4572 | struct worker *worker = current_wq_worker(); | |
4573 | va_list args; | |
4574 | ||
4575 | if (worker) { | |
4576 | va_start(args, fmt); | |
4577 | vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); | |
4578 | va_end(args); | |
4579 | } | |
4580 | } | |
4581 | EXPORT_SYMBOL_GPL(set_worker_desc); | |
4582 | ||
4583 | /** | |
4584 | * print_worker_info - print out worker information and description | |
4585 | * @log_lvl: the log level to use when printing | |
4586 | * @task: target task | |
4587 | * | |
4588 | * If @task is a worker and currently executing a work item, print out the | |
4589 | * name of the workqueue being serviced and worker description set with | |
4590 | * set_worker_desc() by the currently executing work item. | |
4591 | * | |
4592 | * This function can be safely called on any task as long as the | |
4593 | * task_struct itself is accessible. While safe, this function isn't | |
4594 | * synchronized and may print out mixups or garbages of limited length. | |
4595 | */ | |
4596 | void print_worker_info(const char *log_lvl, struct task_struct *task) | |
4597 | { | |
4598 | work_func_t *fn = NULL; | |
4599 | char name[WQ_NAME_LEN] = { }; | |
4600 | char desc[WORKER_DESC_LEN] = { }; | |
4601 | struct pool_workqueue *pwq = NULL; | |
4602 | struct workqueue_struct *wq = NULL; | |
4603 | struct worker *worker; | |
4604 | ||
4605 | if (!(task->flags & PF_WQ_WORKER)) | |
4606 | return; | |
4607 | ||
4608 | /* | |
4609 | * This function is called without any synchronization and @task | |
4610 | * could be in any state. Be careful with dereferences. | |
4611 | */ | |
4612 | worker = kthread_probe_data(task); | |
4613 | ||
4614 | /* | |
4615 | * Carefully copy the associated workqueue's workfn, name and desc. | |
4616 | * Keep the original last '\0' in case the original is garbage. | |
4617 | */ | |
4618 | probe_kernel_read(&fn, &worker->current_func, sizeof(fn)); | |
4619 | probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); | |
4620 | probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); | |
4621 | probe_kernel_read(name, wq->name, sizeof(name) - 1); | |
4622 | probe_kernel_read(desc, worker->desc, sizeof(desc) - 1); | |
4623 | ||
4624 | if (fn || name[0] || desc[0]) { | |
4625 | printk("%sWorkqueue: %s %ps", log_lvl, name, fn); | |
4626 | if (strcmp(name, desc)) | |
4627 | pr_cont(" (%s)", desc); | |
4628 | pr_cont("\n"); | |
4629 | } | |
4630 | } | |
4631 | ||
4632 | static void pr_cont_pool_info(struct worker_pool *pool) | |
4633 | { | |
4634 | pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask); | |
4635 | if (pool->node != NUMA_NO_NODE) | |
4636 | pr_cont(" node=%d", pool->node); | |
4637 | pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice); | |
4638 | } | |
4639 | ||
4640 | static void pr_cont_work(bool comma, struct work_struct *work) | |
4641 | { | |
4642 | if (work->func == wq_barrier_func) { | |
4643 | struct wq_barrier *barr; | |
4644 | ||
4645 | barr = container_of(work, struct wq_barrier, work); | |
4646 | ||
4647 | pr_cont("%s BAR(%d)", comma ? "," : "", | |
4648 | task_pid_nr(barr->task)); | |
4649 | } else { | |
4650 | pr_cont("%s %ps", comma ? "," : "", work->func); | |
4651 | } | |
4652 | } | |
4653 | ||
4654 | static void show_pwq(struct pool_workqueue *pwq) | |
4655 | { | |
4656 | struct worker_pool *pool = pwq->pool; | |
4657 | struct work_struct *work; | |
4658 | struct worker *worker; | |
4659 | bool has_in_flight = false, has_pending = false; | |
4660 | int bkt; | |
4661 | ||
4662 | pr_info(" pwq %d:", pool->id); | |
4663 | pr_cont_pool_info(pool); | |
4664 | ||
4665 | pr_cont(" active=%d/%d refcnt=%d%s\n", | |
4666 | pwq->nr_active, pwq->max_active, pwq->refcnt, | |
4667 | !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); | |
4668 | ||
4669 | hash_for_each(pool->busy_hash, bkt, worker, hentry) { | |
4670 | if (worker->current_pwq == pwq) { | |
4671 | has_in_flight = true; | |
4672 | break; | |
4673 | } | |
4674 | } | |
4675 | if (has_in_flight) { | |
4676 | bool comma = false; | |
4677 | ||
4678 | pr_info(" in-flight:"); | |
4679 | hash_for_each(pool->busy_hash, bkt, worker, hentry) { | |
4680 | if (worker->current_pwq != pwq) | |
4681 | continue; | |
4682 | ||
4683 | pr_cont("%s %d%s:%ps", comma ? "," : "", | |
4684 | task_pid_nr(worker->task), | |
4685 | worker == pwq->wq->rescuer ? "(RESCUER)" : "", | |
4686 | worker->current_func); | |
4687 | list_for_each_entry(work, &worker->scheduled, entry) | |
4688 | pr_cont_work(false, work); | |
4689 | comma = true; | |
4690 | } | |
4691 | pr_cont("\n"); | |
4692 | } | |
4693 | ||
4694 | list_for_each_entry(work, &pool->worklist, entry) { | |
4695 | if (get_work_pwq(work) == pwq) { | |
4696 | has_pending = true; | |
4697 | break; | |
4698 | } | |
4699 | } | |
4700 | if (has_pending) { | |
4701 | bool comma = false; | |
4702 | ||
4703 | pr_info(" pending:"); | |
4704 | list_for_each_entry(work, &pool->worklist, entry) { | |
4705 | if (get_work_pwq(work) != pwq) | |
4706 | continue; | |
4707 | ||
4708 | pr_cont_work(comma, work); | |
4709 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); | |
4710 | } | |
4711 | pr_cont("\n"); | |
4712 | } | |
4713 | ||
4714 | if (!list_empty(&pwq->delayed_works)) { | |
4715 | bool comma = false; | |
4716 | ||
4717 | pr_info(" delayed:"); | |
4718 | list_for_each_entry(work, &pwq->delayed_works, entry) { | |
4719 | pr_cont_work(comma, work); | |
4720 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); | |
4721 | } | |
4722 | pr_cont("\n"); | |
4723 | } | |
4724 | } | |
4725 | ||
4726 | /** | |
4727 | * show_workqueue_state - dump workqueue state | |
4728 | * | |
4729 | * Called from a sysrq handler or try_to_freeze_tasks() and prints out | |
4730 | * all busy workqueues and pools. | |
4731 | */ | |
4732 | void show_workqueue_state(void) | |
4733 | { | |
4734 | struct workqueue_struct *wq; | |
4735 | struct worker_pool *pool; | |
4736 | unsigned long flags; | |
4737 | int pi; | |
4738 | ||
4739 | rcu_read_lock(); | |
4740 | ||
4741 | pr_info("Showing busy workqueues and worker pools:\n"); | |
4742 | ||
4743 | list_for_each_entry_rcu(wq, &workqueues, list) { | |
4744 | struct pool_workqueue *pwq; | |
4745 | bool idle = true; | |
4746 | ||
4747 | for_each_pwq(pwq, wq) { | |
4748 | if (pwq->nr_active || !list_empty(&pwq->delayed_works)) { | |
4749 | idle = false; | |
4750 | break; | |
4751 | } | |
4752 | } | |
4753 | if (idle) | |
4754 | continue; | |
4755 | ||
4756 | pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags); | |
4757 | ||
4758 | for_each_pwq(pwq, wq) { | |
4759 | spin_lock_irqsave(&pwq->pool->lock, flags); | |
4760 | if (pwq->nr_active || !list_empty(&pwq->delayed_works)) | |
4761 | show_pwq(pwq); | |
4762 | spin_unlock_irqrestore(&pwq->pool->lock, flags); | |
4763 | /* | |
4764 | * We could be printing a lot from atomic context, e.g. | |
4765 | * sysrq-t -> show_workqueue_state(). Avoid triggering | |
4766 | * hard lockup. | |
4767 | */ | |
4768 | touch_nmi_watchdog(); | |
4769 | } | |
4770 | } | |
4771 | ||
4772 | for_each_pool(pool, pi) { | |
4773 | struct worker *worker; | |
4774 | bool first = true; | |
4775 | ||
4776 | spin_lock_irqsave(&pool->lock, flags); | |
4777 | if (pool->nr_workers == pool->nr_idle) | |
4778 | goto next_pool; | |
4779 | ||
4780 | pr_info("pool %d:", pool->id); | |
4781 | pr_cont_pool_info(pool); | |
4782 | pr_cont(" hung=%us workers=%d", | |
4783 | jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000, | |
4784 | pool->nr_workers); | |
4785 | if (pool->manager) | |
4786 | pr_cont(" manager: %d", | |
4787 | task_pid_nr(pool->manager->task)); | |
4788 | list_for_each_entry(worker, &pool->idle_list, entry) { | |
4789 | pr_cont(" %s%d", first ? "idle: " : "", | |
4790 | task_pid_nr(worker->task)); | |
4791 | first = false; | |
4792 | } | |
4793 | pr_cont("\n"); | |
4794 | next_pool: | |
4795 | spin_unlock_irqrestore(&pool->lock, flags); | |
4796 | /* | |
4797 | * We could be printing a lot from atomic context, e.g. | |
4798 | * sysrq-t -> show_workqueue_state(). Avoid triggering | |
4799 | * hard lockup. | |
4800 | */ | |
4801 | touch_nmi_watchdog(); | |
4802 | } | |
4803 | ||
4804 | rcu_read_unlock(); | |
4805 | } | |
4806 | ||
4807 | /* used to show worker information through /proc/PID/{comm,stat,status} */ | |
4808 | void wq_worker_comm(char *buf, size_t size, struct task_struct *task) | |
4809 | { | |
4810 | int off; | |
4811 | ||
4812 | /* always show the actual comm */ | |
4813 | off = strscpy(buf, task->comm, size); | |
4814 | if (off < 0) | |
4815 | return; | |
4816 | ||
4817 | /* stabilize PF_WQ_WORKER and worker pool association */ | |
4818 | mutex_lock(&wq_pool_attach_mutex); | |
4819 | ||
4820 | if (task->flags & PF_WQ_WORKER) { | |
4821 | struct worker *worker = kthread_data(task); | |
4822 | struct worker_pool *pool = worker->pool; | |
4823 | ||
4824 | if (pool) { | |
4825 | spin_lock_irq(&pool->lock); | |
4826 | /* | |
4827 | * ->desc tracks information (wq name or | |
4828 | * set_worker_desc()) for the latest execution. If | |
4829 | * current, prepend '+', otherwise '-'. | |
4830 | */ | |
4831 | if (worker->desc[0] != '\0') { | |
4832 | if (worker->current_work) | |
4833 | scnprintf(buf + off, size - off, "+%s", | |
4834 | worker->desc); | |
4835 | else | |
4836 | scnprintf(buf + off, size - off, "-%s", | |
4837 | worker->desc); | |
4838 | } | |
4839 | spin_unlock_irq(&pool->lock); | |
4840 | } | |
4841 | } | |
4842 | ||
4843 | mutex_unlock(&wq_pool_attach_mutex); | |
4844 | } | |
4845 | ||
4846 | #ifdef CONFIG_SMP | |
4847 | ||
4848 | /* | |
4849 | * CPU hotplug. | |
4850 | * | |
4851 | * There are two challenges in supporting CPU hotplug. Firstly, there | |
4852 | * are a lot of assumptions on strong associations among work, pwq and | |
4853 | * pool which make migrating pending and scheduled works very | |
4854 | * difficult to implement without impacting hot paths. Secondly, | |
4855 | * worker pools serve mix of short, long and very long running works making | |
4856 | * blocked draining impractical. | |
4857 | * | |
4858 | * This is solved by allowing the pools to be disassociated from the CPU | |
4859 | * running as an unbound one and allowing it to be reattached later if the | |
4860 | * cpu comes back online. | |
4861 | */ | |
4862 | ||
4863 | static void unbind_workers(int cpu) | |
4864 | { | |
4865 | struct worker_pool *pool; | |
4866 | struct worker *worker; | |
4867 | ||
4868 | for_each_cpu_worker_pool(pool, cpu) { | |
4869 | mutex_lock(&wq_pool_attach_mutex); | |
4870 | spin_lock_irq(&pool->lock); | |
4871 | ||
4872 | /* | |
4873 | * We've blocked all attach/detach operations. Make all workers | |
4874 | * unbound and set DISASSOCIATED. Before this, all workers | |
4875 | * except for the ones which are still executing works from | |
4876 | * before the last CPU down must be on the cpu. After | |
4877 | * this, they may become diasporas. | |
4878 | */ | |
4879 | for_each_pool_worker(worker, pool) | |
4880 | worker->flags |= WORKER_UNBOUND; | |
4881 | ||
4882 | pool->flags |= POOL_DISASSOCIATED; | |
4883 | ||
4884 | spin_unlock_irq(&pool->lock); | |
4885 | mutex_unlock(&wq_pool_attach_mutex); | |
4886 | ||
4887 | /* | |
4888 | * Call schedule() so that we cross rq->lock and thus can | |
4889 | * guarantee sched callbacks see the %WORKER_UNBOUND flag. | |
4890 | * This is necessary as scheduler callbacks may be invoked | |
4891 | * from other cpus. | |
4892 | */ | |
4893 | schedule(); | |
4894 | ||
4895 | /* | |
4896 | * Sched callbacks are disabled now. Zap nr_running. | |
4897 | * After this, nr_running stays zero and need_more_worker() | |
4898 | * and keep_working() are always true as long as the | |
4899 | * worklist is not empty. This pool now behaves as an | |
4900 | * unbound (in terms of concurrency management) pool which | |
4901 | * are served by workers tied to the pool. | |
4902 | */ | |
4903 | atomic_set(&pool->nr_running, 0); | |
4904 | ||
4905 | /* | |
4906 | * With concurrency management just turned off, a busy | |
4907 | * worker blocking could lead to lengthy stalls. Kick off | |
4908 | * unbound chain execution of currently pending work items. | |
4909 | */ | |
4910 | spin_lock_irq(&pool->lock); | |
4911 | wake_up_worker(pool); | |
4912 | spin_unlock_irq(&pool->lock); | |
4913 | } | |
4914 | } | |
4915 | ||
4916 | /** | |
4917 | * rebind_workers - rebind all workers of a pool to the associated CPU | |
4918 | * @pool: pool of interest | |
4919 | * | |
4920 | * @pool->cpu is coming online. Rebind all workers to the CPU. | |
4921 | */ | |
4922 | static void rebind_workers(struct worker_pool *pool) | |
4923 | { | |
4924 | struct worker *worker; | |
4925 | ||
4926 | lockdep_assert_held(&wq_pool_attach_mutex); | |
4927 | ||
4928 | /* | |
4929 | * Restore CPU affinity of all workers. As all idle workers should | |
4930 | * be on the run-queue of the associated CPU before any local | |
4931 | * wake-ups for concurrency management happen, restore CPU affinity | |
4932 | * of all workers first and then clear UNBOUND. As we're called | |
4933 | * from CPU_ONLINE, the following shouldn't fail. | |
4934 | */ | |
4935 | for_each_pool_worker(worker, pool) | |
4936 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, | |
4937 | pool->attrs->cpumask) < 0); | |
4938 | ||
4939 | spin_lock_irq(&pool->lock); | |
4940 | ||
4941 | pool->flags &= ~POOL_DISASSOCIATED; | |
4942 | ||
4943 | for_each_pool_worker(worker, pool) { | |
4944 | unsigned int worker_flags = worker->flags; | |
4945 | ||
4946 | /* | |
4947 | * A bound idle worker should actually be on the runqueue | |
4948 | * of the associated CPU for local wake-ups targeting it to | |
4949 | * work. Kick all idle workers so that they migrate to the | |
4950 | * associated CPU. Doing this in the same loop as | |
4951 | * replacing UNBOUND with REBOUND is safe as no worker will | |
4952 | * be bound before @pool->lock is released. | |
4953 | */ | |
4954 | if (worker_flags & WORKER_IDLE) | |
4955 | wake_up_process(worker->task); | |
4956 | ||
4957 | /* | |
4958 | * We want to clear UNBOUND but can't directly call | |
4959 | * worker_clr_flags() or adjust nr_running. Atomically | |
4960 | * replace UNBOUND with another NOT_RUNNING flag REBOUND. | |
4961 | * @worker will clear REBOUND using worker_clr_flags() when | |
4962 | * it initiates the next execution cycle thus restoring | |
4963 | * concurrency management. Note that when or whether | |
4964 | * @worker clears REBOUND doesn't affect correctness. | |
4965 | * | |
4966 | * WRITE_ONCE() is necessary because @worker->flags may be | |
4967 | * tested without holding any lock in | |
4968 | * wq_worker_running(). Without it, NOT_RUNNING test may | |
4969 | * fail incorrectly leading to premature concurrency | |
4970 | * management operations. | |
4971 | */ | |
4972 | WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); | |
4973 | worker_flags |= WORKER_REBOUND; | |
4974 | worker_flags &= ~WORKER_UNBOUND; | |
4975 | WRITE_ONCE(worker->flags, worker_flags); | |
4976 | } | |
4977 | ||
4978 | spin_unlock_irq(&pool->lock); | |
4979 | } | |
4980 | ||
4981 | /** | |
4982 | * restore_unbound_workers_cpumask - restore cpumask of unbound workers | |
4983 | * @pool: unbound pool of interest | |
4984 | * @cpu: the CPU which is coming up | |
4985 | * | |
4986 | * An unbound pool may end up with a cpumask which doesn't have any online | |
4987 | * CPUs. When a worker of such pool get scheduled, the scheduler resets | |
4988 | * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any | |
4989 | * online CPU before, cpus_allowed of all its workers should be restored. | |
4990 | */ | |
4991 | static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) | |
4992 | { | |
4993 | static cpumask_t cpumask; | |
4994 | struct worker *worker; | |
4995 | ||
4996 | lockdep_assert_held(&wq_pool_attach_mutex); | |
4997 | ||
4998 | /* is @cpu allowed for @pool? */ | |
4999 | if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) | |
5000 | return; | |
5001 | ||
5002 | cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); | |
5003 | ||
5004 | /* as we're called from CPU_ONLINE, the following shouldn't fail */ | |
5005 | for_each_pool_worker(worker, pool) | |
5006 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0); | |
5007 | } | |
5008 | ||
5009 | int workqueue_prepare_cpu(unsigned int cpu) | |
5010 | { | |
5011 | struct worker_pool *pool; | |
5012 | ||
5013 | for_each_cpu_worker_pool(pool, cpu) { | |
5014 | if (pool->nr_workers) | |
5015 | continue; | |
5016 | if (!create_worker(pool)) | |
5017 | return -ENOMEM; | |
5018 | } | |
5019 | return 0; | |
5020 | } | |
5021 | ||
5022 | int workqueue_online_cpu(unsigned int cpu) | |
5023 | { | |
5024 | struct worker_pool *pool; | |
5025 | struct workqueue_struct *wq; | |
5026 | int pi; | |
5027 | ||
5028 | mutex_lock(&wq_pool_mutex); | |
5029 | ||
5030 | for_each_pool(pool, pi) { | |
5031 | mutex_lock(&wq_pool_attach_mutex); | |
5032 | ||
5033 | if (pool->cpu == cpu) | |
5034 | rebind_workers(pool); | |
5035 | else if (pool->cpu < 0) | |
5036 | restore_unbound_workers_cpumask(pool, cpu); | |
5037 | ||
5038 | mutex_unlock(&wq_pool_attach_mutex); | |
5039 | } | |
5040 | ||
5041 | /* update NUMA affinity of unbound workqueues */ | |
5042 | list_for_each_entry(wq, &workqueues, list) | |
5043 | wq_update_unbound_numa(wq, cpu, true); | |
5044 | ||
5045 | mutex_unlock(&wq_pool_mutex); | |
5046 | return 0; | |
5047 | } | |
5048 | ||
5049 | int workqueue_offline_cpu(unsigned int cpu) | |
5050 | { | |
5051 | struct workqueue_struct *wq; | |
5052 | ||
5053 | /* unbinding per-cpu workers should happen on the local CPU */ | |
5054 | if (WARN_ON(cpu != smp_processor_id())) | |
5055 | return -1; | |
5056 | ||
5057 | unbind_workers(cpu); | |
5058 | ||
5059 | /* update NUMA affinity of unbound workqueues */ | |
5060 | mutex_lock(&wq_pool_mutex); | |
5061 | list_for_each_entry(wq, &workqueues, list) | |
5062 | wq_update_unbound_numa(wq, cpu, false); | |
5063 | mutex_unlock(&wq_pool_mutex); | |
5064 | ||
5065 | return 0; | |
5066 | } | |
5067 | ||
5068 | struct work_for_cpu { | |
5069 | struct work_struct work; | |
5070 | long (*fn)(void *); | |
5071 | void *arg; | |
5072 | long ret; | |
5073 | }; | |
5074 | ||
5075 | static void work_for_cpu_fn(struct work_struct *work) | |
5076 | { | |
5077 | struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); | |
5078 | ||
5079 | wfc->ret = wfc->fn(wfc->arg); | |
5080 | } | |
5081 | ||
5082 | /** | |
5083 | * work_on_cpu - run a function in thread context on a particular cpu | |
5084 | * @cpu: the cpu to run on | |
5085 | * @fn: the function to run | |
5086 | * @arg: the function arg | |
5087 | * | |
5088 | * It is up to the caller to ensure that the cpu doesn't go offline. | |
5089 | * The caller must not hold any locks which would prevent @fn from completing. | |
5090 | * | |
5091 | * Return: The value @fn returns. | |
5092 | */ | |
5093 | long work_on_cpu(int cpu, long (*fn)(void *), void *arg) | |
5094 | { | |
5095 | struct work_for_cpu wfc = { .fn = fn, .arg = arg }; | |
5096 | ||
5097 | INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); | |
5098 | schedule_work_on(cpu, &wfc.work); | |
5099 | flush_work(&wfc.work); | |
5100 | destroy_work_on_stack(&wfc.work); | |
5101 | return wfc.ret; | |
5102 | } | |
5103 | EXPORT_SYMBOL_GPL(work_on_cpu); | |
5104 | ||
5105 | /** | |
5106 | * work_on_cpu_safe - run a function in thread context on a particular cpu | |
5107 | * @cpu: the cpu to run on | |
5108 | * @fn: the function to run | |
5109 | * @arg: the function argument | |
5110 | * | |
5111 | * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold | |
5112 | * any locks which would prevent @fn from completing. | |
5113 | * | |
5114 | * Return: The value @fn returns. | |
5115 | */ | |
5116 | long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg) | |
5117 | { | |
5118 | long ret = -ENODEV; | |
5119 | ||
5120 | get_online_cpus(); | |
5121 | if (cpu_online(cpu)) | |
5122 | ret = work_on_cpu(cpu, fn, arg); | |
5123 | put_online_cpus(); | |
5124 | return ret; | |
5125 | } | |
5126 | EXPORT_SYMBOL_GPL(work_on_cpu_safe); | |
5127 | #endif /* CONFIG_SMP */ | |
5128 | ||
5129 | #ifdef CONFIG_FREEZER | |
5130 | ||
5131 | /** | |
5132 | * freeze_workqueues_begin - begin freezing workqueues | |
5133 | * | |
5134 | * Start freezing workqueues. After this function returns, all freezable | |
5135 | * workqueues will queue new works to their delayed_works list instead of | |
5136 | * pool->worklist. | |
5137 | * | |
5138 | * CONTEXT: | |
5139 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. | |
5140 | */ | |
5141 | void freeze_workqueues_begin(void) | |
5142 | { | |
5143 | struct workqueue_struct *wq; | |
5144 | struct pool_workqueue *pwq; | |
5145 | ||
5146 | mutex_lock(&wq_pool_mutex); | |
5147 | ||
5148 | WARN_ON_ONCE(workqueue_freezing); | |
5149 | workqueue_freezing = true; | |
5150 | ||
5151 | list_for_each_entry(wq, &workqueues, list) { | |
5152 | mutex_lock(&wq->mutex); | |
5153 | for_each_pwq(pwq, wq) | |
5154 | pwq_adjust_max_active(pwq); | |
5155 | mutex_unlock(&wq->mutex); | |
5156 | } | |
5157 | ||
5158 | mutex_unlock(&wq_pool_mutex); | |
5159 | } | |
5160 | ||
5161 | /** | |
5162 | * freeze_workqueues_busy - are freezable workqueues still busy? | |
5163 | * | |
5164 | * Check whether freezing is complete. This function must be called | |
5165 | * between freeze_workqueues_begin() and thaw_workqueues(). | |
5166 | * | |
5167 | * CONTEXT: | |
5168 | * Grabs and releases wq_pool_mutex. | |
5169 | * | |
5170 | * Return: | |
5171 | * %true if some freezable workqueues are still busy. %false if freezing | |
5172 | * is complete. | |
5173 | */ | |
5174 | bool freeze_workqueues_busy(void) | |
5175 | { | |
5176 | bool busy = false; | |
5177 | struct workqueue_struct *wq; | |
5178 | struct pool_workqueue *pwq; | |
5179 | ||
5180 | mutex_lock(&wq_pool_mutex); | |
5181 | ||
5182 | WARN_ON_ONCE(!workqueue_freezing); | |
5183 | ||
5184 | list_for_each_entry(wq, &workqueues, list) { | |
5185 | if (!(wq->flags & WQ_FREEZABLE)) | |
5186 | continue; | |
5187 | /* | |
5188 | * nr_active is monotonically decreasing. It's safe | |
5189 | * to peek without lock. | |
5190 | */ | |
5191 | rcu_read_lock(); | |
5192 | for_each_pwq(pwq, wq) { | |
5193 | WARN_ON_ONCE(pwq->nr_active < 0); | |
5194 | if (pwq->nr_active) { | |
5195 | busy = true; | |
5196 | rcu_read_unlock(); | |
5197 | goto out_unlock; | |
5198 | } | |
5199 | } | |
5200 | rcu_read_unlock(); | |
5201 | } | |
5202 | out_unlock: | |
5203 | mutex_unlock(&wq_pool_mutex); | |
5204 | return busy; | |
5205 | } | |
5206 | ||
5207 | /** | |
5208 | * thaw_workqueues - thaw workqueues | |
5209 | * | |
5210 | * Thaw workqueues. Normal queueing is restored and all collected | |
5211 | * frozen works are transferred to their respective pool worklists. | |
5212 | * | |
5213 | * CONTEXT: | |
5214 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. | |
5215 | */ | |
5216 | void thaw_workqueues(void) | |
5217 | { | |
5218 | struct workqueue_struct *wq; | |
5219 | struct pool_workqueue *pwq; | |
5220 | ||
5221 | mutex_lock(&wq_pool_mutex); | |
5222 | ||
5223 | if (!workqueue_freezing) | |
5224 | goto out_unlock; | |
5225 | ||
5226 | workqueue_freezing = false; | |
5227 | ||
5228 | /* restore max_active and repopulate worklist */ | |
5229 | list_for_each_entry(wq, &workqueues, list) { | |
5230 | mutex_lock(&wq->mutex); | |
5231 | for_each_pwq(pwq, wq) | |
5232 | pwq_adjust_max_active(pwq); | |
5233 | mutex_unlock(&wq->mutex); | |
5234 | } | |
5235 | ||
5236 | out_unlock: | |
5237 | mutex_unlock(&wq_pool_mutex); | |
5238 | } | |
5239 | #endif /* CONFIG_FREEZER */ | |
5240 | ||
5241 | static int workqueue_apply_unbound_cpumask(void) | |
5242 | { | |
5243 | LIST_HEAD(ctxs); | |
5244 | int ret = 0; | |
5245 | struct workqueue_struct *wq; | |
5246 | struct apply_wqattrs_ctx *ctx, *n; | |
5247 | ||
5248 | lockdep_assert_held(&wq_pool_mutex); | |
5249 | ||
5250 | list_for_each_entry(wq, &workqueues, list) { | |
5251 | if (!(wq->flags & WQ_UNBOUND)) | |
5252 | continue; | |
5253 | /* creating multiple pwqs breaks ordering guarantee */ | |
5254 | if (wq->flags & __WQ_ORDERED) | |
5255 | continue; | |
5256 | ||
5257 | ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs); | |
5258 | if (!ctx) { | |
5259 | ret = -ENOMEM; | |
5260 | break; | |
5261 | } | |
5262 | ||
5263 | list_add_tail(&ctx->list, &ctxs); | |
5264 | } | |
5265 | ||
5266 | list_for_each_entry_safe(ctx, n, &ctxs, list) { | |
5267 | if (!ret) | |
5268 | apply_wqattrs_commit(ctx); | |
5269 | apply_wqattrs_cleanup(ctx); | |
5270 | } | |
5271 | ||
5272 | return ret; | |
5273 | } | |
5274 | ||
5275 | /** | |
5276 | * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask | |
5277 | * @cpumask: the cpumask to set | |
5278 | * | |
5279 | * The low-level workqueues cpumask is a global cpumask that limits | |
5280 | * the affinity of all unbound workqueues. This function check the @cpumask | |
5281 | * and apply it to all unbound workqueues and updates all pwqs of them. | |
5282 | * | |
5283 | * Retun: 0 - Success | |
5284 | * -EINVAL - Invalid @cpumask | |
5285 | * -ENOMEM - Failed to allocate memory for attrs or pwqs. | |
5286 | */ | |
5287 | int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) | |
5288 | { | |
5289 | int ret = -EINVAL; | |
5290 | cpumask_var_t saved_cpumask; | |
5291 | ||
5292 | if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL)) | |
5293 | return -ENOMEM; | |
5294 | ||
5295 | /* | |
5296 | * Not excluding isolated cpus on purpose. | |
5297 | * If the user wishes to include them, we allow that. | |
5298 | */ | |
5299 | cpumask_and(cpumask, cpumask, cpu_possible_mask); | |
5300 | if (!cpumask_empty(cpumask)) { | |
5301 | apply_wqattrs_lock(); | |
5302 | ||
5303 | /* save the old wq_unbound_cpumask. */ | |
5304 | cpumask_copy(saved_cpumask, wq_unbound_cpumask); | |
5305 | ||
5306 | /* update wq_unbound_cpumask at first and apply it to wqs. */ | |
5307 | cpumask_copy(wq_unbound_cpumask, cpumask); | |
5308 | ret = workqueue_apply_unbound_cpumask(); | |
5309 | ||
5310 | /* restore the wq_unbound_cpumask when failed. */ | |
5311 | if (ret < 0) | |
5312 | cpumask_copy(wq_unbound_cpumask, saved_cpumask); | |
5313 | ||
5314 | apply_wqattrs_unlock(); | |
5315 | } | |
5316 | ||
5317 | free_cpumask_var(saved_cpumask); | |
5318 | return ret; | |
5319 | } | |
5320 | ||
5321 | #ifdef CONFIG_SYSFS | |
5322 | /* | |
5323 | * Workqueues with WQ_SYSFS flag set is visible to userland via | |
5324 | * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the | |
5325 | * following attributes. | |
5326 | * | |
5327 | * per_cpu RO bool : whether the workqueue is per-cpu or unbound | |
5328 | * max_active RW int : maximum number of in-flight work items | |
5329 | * | |
5330 | * Unbound workqueues have the following extra attributes. | |
5331 | * | |
5332 | * pool_ids RO int : the associated pool IDs for each node | |
5333 | * nice RW int : nice value of the workers | |
5334 | * cpumask RW mask : bitmask of allowed CPUs for the workers | |
5335 | * numa RW bool : whether enable NUMA affinity | |
5336 | */ | |
5337 | struct wq_device { | |
5338 | struct workqueue_struct *wq; | |
5339 | struct device dev; | |
5340 | }; | |
5341 | ||
5342 | static struct workqueue_struct *dev_to_wq(struct device *dev) | |
5343 | { | |
5344 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); | |
5345 | ||
5346 | return wq_dev->wq; | |
5347 | } | |
5348 | ||
5349 | static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, | |
5350 | char *buf) | |
5351 | { | |
5352 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5353 | ||
5354 | return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); | |
5355 | } | |
5356 | static DEVICE_ATTR_RO(per_cpu); | |
5357 | ||
5358 | static ssize_t max_active_show(struct device *dev, | |
5359 | struct device_attribute *attr, char *buf) | |
5360 | { | |
5361 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5362 | ||
5363 | return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); | |
5364 | } | |
5365 | ||
5366 | static ssize_t max_active_store(struct device *dev, | |
5367 | struct device_attribute *attr, const char *buf, | |
5368 | size_t count) | |
5369 | { | |
5370 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5371 | int val; | |
5372 | ||
5373 | if (sscanf(buf, "%d", &val) != 1 || val <= 0) | |
5374 | return -EINVAL; | |
5375 | ||
5376 | workqueue_set_max_active(wq, val); | |
5377 | return count; | |
5378 | } | |
5379 | static DEVICE_ATTR_RW(max_active); | |
5380 | ||
5381 | static struct attribute *wq_sysfs_attrs[] = { | |
5382 | &dev_attr_per_cpu.attr, | |
5383 | &dev_attr_max_active.attr, | |
5384 | NULL, | |
5385 | }; | |
5386 | ATTRIBUTE_GROUPS(wq_sysfs); | |
5387 | ||
5388 | static ssize_t wq_pool_ids_show(struct device *dev, | |
5389 | struct device_attribute *attr, char *buf) | |
5390 | { | |
5391 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5392 | const char *delim = ""; | |
5393 | int node, written = 0; | |
5394 | ||
5395 | get_online_cpus(); | |
5396 | rcu_read_lock(); | |
5397 | for_each_node(node) { | |
5398 | written += scnprintf(buf + written, PAGE_SIZE - written, | |
5399 | "%s%d:%d", delim, node, | |
5400 | unbound_pwq_by_node(wq, node)->pool->id); | |
5401 | delim = " "; | |
5402 | } | |
5403 | written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); | |
5404 | rcu_read_unlock(); | |
5405 | put_online_cpus(); | |
5406 | ||
5407 | return written; | |
5408 | } | |
5409 | ||
5410 | static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, | |
5411 | char *buf) | |
5412 | { | |
5413 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5414 | int written; | |
5415 | ||
5416 | mutex_lock(&wq->mutex); | |
5417 | written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); | |
5418 | mutex_unlock(&wq->mutex); | |
5419 | ||
5420 | return written; | |
5421 | } | |
5422 | ||
5423 | /* prepare workqueue_attrs for sysfs store operations */ | |
5424 | static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) | |
5425 | { | |
5426 | struct workqueue_attrs *attrs; | |
5427 | ||
5428 | lockdep_assert_held(&wq_pool_mutex); | |
5429 | ||
5430 | attrs = alloc_workqueue_attrs(); | |
5431 | if (!attrs) | |
5432 | return NULL; | |
5433 | ||
5434 | copy_workqueue_attrs(attrs, wq->unbound_attrs); | |
5435 | return attrs; | |
5436 | } | |
5437 | ||
5438 | static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, | |
5439 | const char *buf, size_t count) | |
5440 | { | |
5441 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5442 | struct workqueue_attrs *attrs; | |
5443 | int ret = -ENOMEM; | |
5444 | ||
5445 | apply_wqattrs_lock(); | |
5446 | ||
5447 | attrs = wq_sysfs_prep_attrs(wq); | |
5448 | if (!attrs) | |
5449 | goto out_unlock; | |
5450 | ||
5451 | if (sscanf(buf, "%d", &attrs->nice) == 1 && | |
5452 | attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) | |
5453 | ret = apply_workqueue_attrs_locked(wq, attrs); | |
5454 | else | |
5455 | ret = -EINVAL; | |
5456 | ||
5457 | out_unlock: | |
5458 | apply_wqattrs_unlock(); | |
5459 | free_workqueue_attrs(attrs); | |
5460 | return ret ?: count; | |
5461 | } | |
5462 | ||
5463 | static ssize_t wq_cpumask_show(struct device *dev, | |
5464 | struct device_attribute *attr, char *buf) | |
5465 | { | |
5466 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5467 | int written; | |
5468 | ||
5469 | mutex_lock(&wq->mutex); | |
5470 | written = scnprintf(buf, PAGE_SIZE, "%*pb\n", | |
5471 | cpumask_pr_args(wq->unbound_attrs->cpumask)); | |
5472 | mutex_unlock(&wq->mutex); | |
5473 | return written; | |
5474 | } | |
5475 | ||
5476 | static ssize_t wq_cpumask_store(struct device *dev, | |
5477 | struct device_attribute *attr, | |
5478 | const char *buf, size_t count) | |
5479 | { | |
5480 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5481 | struct workqueue_attrs *attrs; | |
5482 | int ret = -ENOMEM; | |
5483 | ||
5484 | apply_wqattrs_lock(); | |
5485 | ||
5486 | attrs = wq_sysfs_prep_attrs(wq); | |
5487 | if (!attrs) | |
5488 | goto out_unlock; | |
5489 | ||
5490 | ret = cpumask_parse(buf, attrs->cpumask); | |
5491 | if (!ret) | |
5492 | ret = apply_workqueue_attrs_locked(wq, attrs); | |
5493 | ||
5494 | out_unlock: | |
5495 | apply_wqattrs_unlock(); | |
5496 | free_workqueue_attrs(attrs); | |
5497 | return ret ?: count; | |
5498 | } | |
5499 | ||
5500 | static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, | |
5501 | char *buf) | |
5502 | { | |
5503 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5504 | int written; | |
5505 | ||
5506 | mutex_lock(&wq->mutex); | |
5507 | written = scnprintf(buf, PAGE_SIZE, "%d\n", | |
5508 | !wq->unbound_attrs->no_numa); | |
5509 | mutex_unlock(&wq->mutex); | |
5510 | ||
5511 | return written; | |
5512 | } | |
5513 | ||
5514 | static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, | |
5515 | const char *buf, size_t count) | |
5516 | { | |
5517 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5518 | struct workqueue_attrs *attrs; | |
5519 | int v, ret = -ENOMEM; | |
5520 | ||
5521 | apply_wqattrs_lock(); | |
5522 | ||
5523 | attrs = wq_sysfs_prep_attrs(wq); | |
5524 | if (!attrs) | |
5525 | goto out_unlock; | |
5526 | ||
5527 | ret = -EINVAL; | |
5528 | if (sscanf(buf, "%d", &v) == 1) { | |
5529 | attrs->no_numa = !v; | |
5530 | ret = apply_workqueue_attrs_locked(wq, attrs); | |
5531 | } | |
5532 | ||
5533 | out_unlock: | |
5534 | apply_wqattrs_unlock(); | |
5535 | free_workqueue_attrs(attrs); | |
5536 | return ret ?: count; | |
5537 | } | |
5538 | ||
5539 | static struct device_attribute wq_sysfs_unbound_attrs[] = { | |
5540 | __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), | |
5541 | __ATTR(nice, 0644, wq_nice_show, wq_nice_store), | |
5542 | __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), | |
5543 | __ATTR(numa, 0644, wq_numa_show, wq_numa_store), | |
5544 | __ATTR_NULL, | |
5545 | }; | |
5546 | ||
5547 | static struct bus_type wq_subsys = { | |
5548 | .name = "workqueue", | |
5549 | .dev_groups = wq_sysfs_groups, | |
5550 | }; | |
5551 | ||
5552 | static ssize_t wq_unbound_cpumask_show(struct device *dev, | |
5553 | struct device_attribute *attr, char *buf) | |
5554 | { | |
5555 | int written; | |
5556 | ||
5557 | mutex_lock(&wq_pool_mutex); | |
5558 | written = scnprintf(buf, PAGE_SIZE, "%*pb\n", | |
5559 | cpumask_pr_args(wq_unbound_cpumask)); | |
5560 | mutex_unlock(&wq_pool_mutex); | |
5561 | ||
5562 | return written; | |
5563 | } | |
5564 | ||
5565 | static ssize_t wq_unbound_cpumask_store(struct device *dev, | |
5566 | struct device_attribute *attr, const char *buf, size_t count) | |
5567 | { | |
5568 | cpumask_var_t cpumask; | |
5569 | int ret; | |
5570 | ||
5571 | if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) | |
5572 | return -ENOMEM; | |
5573 | ||
5574 | ret = cpumask_parse(buf, cpumask); | |
5575 | if (!ret) | |
5576 | ret = workqueue_set_unbound_cpumask(cpumask); | |
5577 | ||
5578 | free_cpumask_var(cpumask); | |
5579 | return ret ? ret : count; | |
5580 | } | |
5581 | ||
5582 | static struct device_attribute wq_sysfs_cpumask_attr = | |
5583 | __ATTR(cpumask, 0644, wq_unbound_cpumask_show, | |
5584 | wq_unbound_cpumask_store); | |
5585 | ||
5586 | static int __init wq_sysfs_init(void) | |
5587 | { | |
5588 | int err; | |
5589 | ||
5590 | err = subsys_virtual_register(&wq_subsys, NULL); | |
5591 | if (err) | |
5592 | return err; | |
5593 | ||
5594 | return device_create_file(wq_subsys.dev_root, &wq_sysfs_cpumask_attr); | |
5595 | } | |
5596 | core_initcall(wq_sysfs_init); | |
5597 | ||
5598 | static void wq_device_release(struct device *dev) | |
5599 | { | |
5600 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); | |
5601 | ||
5602 | kfree(wq_dev); | |
5603 | } | |
5604 | ||
5605 | /** | |
5606 | * workqueue_sysfs_register - make a workqueue visible in sysfs | |
5607 | * @wq: the workqueue to register | |
5608 | * | |
5609 | * Expose @wq in sysfs under /sys/bus/workqueue/devices. | |
5610 | * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set | |
5611 | * which is the preferred method. | |
5612 | * | |
5613 | * Workqueue user should use this function directly iff it wants to apply | |
5614 | * workqueue_attrs before making the workqueue visible in sysfs; otherwise, | |
5615 | * apply_workqueue_attrs() may race against userland updating the | |
5616 | * attributes. | |
5617 | * | |
5618 | * Return: 0 on success, -errno on failure. | |
5619 | */ | |
5620 | int workqueue_sysfs_register(struct workqueue_struct *wq) | |
5621 | { | |
5622 | struct wq_device *wq_dev; | |
5623 | int ret; | |
5624 | ||
5625 | /* | |
5626 | * Adjusting max_active or creating new pwqs by applying | |
5627 | * attributes breaks ordering guarantee. Disallow exposing ordered | |
5628 | * workqueues. | |
5629 | */ | |
5630 | if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) | |
5631 | return -EINVAL; | |
5632 | ||
5633 | wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); | |
5634 | if (!wq_dev) | |
5635 | return -ENOMEM; | |
5636 | ||
5637 | wq_dev->wq = wq; | |
5638 | wq_dev->dev.bus = &wq_subsys; | |
5639 | wq_dev->dev.release = wq_device_release; | |
5640 | dev_set_name(&wq_dev->dev, "%s", wq->name); | |
5641 | ||
5642 | /* | |
5643 | * unbound_attrs are created separately. Suppress uevent until | |
5644 | * everything is ready. | |
5645 | */ | |
5646 | dev_set_uevent_suppress(&wq_dev->dev, true); | |
5647 | ||
5648 | ret = device_register(&wq_dev->dev); | |
5649 | if (ret) { | |
5650 | put_device(&wq_dev->dev); | |
5651 | wq->wq_dev = NULL; | |
5652 | return ret; | |
5653 | } | |
5654 | ||
5655 | if (wq->flags & WQ_UNBOUND) { | |
5656 | struct device_attribute *attr; | |
5657 | ||
5658 | for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { | |
5659 | ret = device_create_file(&wq_dev->dev, attr); | |
5660 | if (ret) { | |
5661 | device_unregister(&wq_dev->dev); | |
5662 | wq->wq_dev = NULL; | |
5663 | return ret; | |
5664 | } | |
5665 | } | |
5666 | } | |
5667 | ||
5668 | dev_set_uevent_suppress(&wq_dev->dev, false); | |
5669 | kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); | |
5670 | return 0; | |
5671 | } | |
5672 | ||
5673 | /** | |
5674 | * workqueue_sysfs_unregister - undo workqueue_sysfs_register() | |
5675 | * @wq: the workqueue to unregister | |
5676 | * | |
5677 | * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. | |
5678 | */ | |
5679 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) | |
5680 | { | |
5681 | struct wq_device *wq_dev = wq->wq_dev; | |
5682 | ||
5683 | if (!wq->wq_dev) | |
5684 | return; | |
5685 | ||
5686 | wq->wq_dev = NULL; | |
5687 | device_unregister(&wq_dev->dev); | |
5688 | } | |
5689 | #else /* CONFIG_SYSFS */ | |
5690 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } | |
5691 | #endif /* CONFIG_SYSFS */ | |
5692 | ||
5693 | /* | |
5694 | * Workqueue watchdog. | |
5695 | * | |
5696 | * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal | |
5697 | * flush dependency, a concurrency managed work item which stays RUNNING | |
5698 | * indefinitely. Workqueue stalls can be very difficult to debug as the | |
5699 | * usual warning mechanisms don't trigger and internal workqueue state is | |
5700 | * largely opaque. | |
5701 | * | |
5702 | * Workqueue watchdog monitors all worker pools periodically and dumps | |
5703 | * state if some pools failed to make forward progress for a while where | |
5704 | * forward progress is defined as the first item on ->worklist changing. | |
5705 | * | |
5706 | * This mechanism is controlled through the kernel parameter | |
5707 | * "workqueue.watchdog_thresh" which can be updated at runtime through the | |
5708 | * corresponding sysfs parameter file. | |
5709 | */ | |
5710 | #ifdef CONFIG_WQ_WATCHDOG | |
5711 | ||
5712 | static unsigned long wq_watchdog_thresh = 30; | |
5713 | static struct timer_list wq_watchdog_timer; | |
5714 | ||
5715 | static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; | |
5716 | static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; | |
5717 | ||
5718 | static void wq_watchdog_reset_touched(void) | |
5719 | { | |
5720 | int cpu; | |
5721 | ||
5722 | wq_watchdog_touched = jiffies; | |
5723 | for_each_possible_cpu(cpu) | |
5724 | per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; | |
5725 | } | |
5726 | ||
5727 | static void wq_watchdog_timer_fn(struct timer_list *unused) | |
5728 | { | |
5729 | unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; | |
5730 | bool lockup_detected = false; | |
5731 | struct worker_pool *pool; | |
5732 | int pi; | |
5733 | ||
5734 | if (!thresh) | |
5735 | return; | |
5736 | ||
5737 | rcu_read_lock(); | |
5738 | ||
5739 | for_each_pool(pool, pi) { | |
5740 | unsigned long pool_ts, touched, ts; | |
5741 | ||
5742 | if (list_empty(&pool->worklist)) | |
5743 | continue; | |
5744 | ||
5745 | /* get the latest of pool and touched timestamps */ | |
5746 | pool_ts = READ_ONCE(pool->watchdog_ts); | |
5747 | touched = READ_ONCE(wq_watchdog_touched); | |
5748 | ||
5749 | if (time_after(pool_ts, touched)) | |
5750 | ts = pool_ts; | |
5751 | else | |
5752 | ts = touched; | |
5753 | ||
5754 | if (pool->cpu >= 0) { | |
5755 | unsigned long cpu_touched = | |
5756 | READ_ONCE(per_cpu(wq_watchdog_touched_cpu, | |
5757 | pool->cpu)); | |
5758 | if (time_after(cpu_touched, ts)) | |
5759 | ts = cpu_touched; | |
5760 | } | |
5761 | ||
5762 | /* did we stall? */ | |
5763 | if (time_after(jiffies, ts + thresh)) { | |
5764 | lockup_detected = true; | |
5765 | pr_emerg("BUG: workqueue lockup - pool"); | |
5766 | pr_cont_pool_info(pool); | |
5767 | pr_cont(" stuck for %us!\n", | |
5768 | jiffies_to_msecs(jiffies - pool_ts) / 1000); | |
5769 | } | |
5770 | } | |
5771 | ||
5772 | rcu_read_unlock(); | |
5773 | ||
5774 | if (lockup_detected) | |
5775 | show_workqueue_state(); | |
5776 | ||
5777 | wq_watchdog_reset_touched(); | |
5778 | mod_timer(&wq_watchdog_timer, jiffies + thresh); | |
5779 | } | |
5780 | ||
5781 | notrace void wq_watchdog_touch(int cpu) | |
5782 | { | |
5783 | if (cpu >= 0) | |
5784 | per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; | |
5785 | else | |
5786 | wq_watchdog_touched = jiffies; | |
5787 | } | |
5788 | ||
5789 | static void wq_watchdog_set_thresh(unsigned long thresh) | |
5790 | { | |
5791 | wq_watchdog_thresh = 0; | |
5792 | del_timer_sync(&wq_watchdog_timer); | |
5793 | ||
5794 | if (thresh) { | |
5795 | wq_watchdog_thresh = thresh; | |
5796 | wq_watchdog_reset_touched(); | |
5797 | mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ); | |
5798 | } | |
5799 | } | |
5800 | ||
5801 | static int wq_watchdog_param_set_thresh(const char *val, | |
5802 | const struct kernel_param *kp) | |
5803 | { | |
5804 | unsigned long thresh; | |
5805 | int ret; | |
5806 | ||
5807 | ret = kstrtoul(val, 0, &thresh); | |
5808 | if (ret) | |
5809 | return ret; | |
5810 | ||
5811 | if (system_wq) | |
5812 | wq_watchdog_set_thresh(thresh); | |
5813 | else | |
5814 | wq_watchdog_thresh = thresh; | |
5815 | ||
5816 | return 0; | |
5817 | } | |
5818 | ||
5819 | static const struct kernel_param_ops wq_watchdog_thresh_ops = { | |
5820 | .set = wq_watchdog_param_set_thresh, | |
5821 | .get = param_get_ulong, | |
5822 | }; | |
5823 | ||
5824 | module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, | |
5825 | 0644); | |
5826 | ||
5827 | static void wq_watchdog_init(void) | |
5828 | { | |
5829 | timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE); | |
5830 | wq_watchdog_set_thresh(wq_watchdog_thresh); | |
5831 | } | |
5832 | ||
5833 | #else /* CONFIG_WQ_WATCHDOG */ | |
5834 | ||
5835 | static inline void wq_watchdog_init(void) { } | |
5836 | ||
5837 | #endif /* CONFIG_WQ_WATCHDOG */ | |
5838 | ||
5839 | static void __init wq_numa_init(void) | |
5840 | { | |
5841 | cpumask_var_t *tbl; | |
5842 | int node, cpu; | |
5843 | ||
5844 | if (num_possible_nodes() <= 1) | |
5845 | return; | |
5846 | ||
5847 | if (wq_disable_numa) { | |
5848 | pr_info("workqueue: NUMA affinity support disabled\n"); | |
5849 | return; | |
5850 | } | |
5851 | ||
5852 | wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(); | |
5853 | BUG_ON(!wq_update_unbound_numa_attrs_buf); | |
5854 | ||
5855 | /* | |
5856 | * We want masks of possible CPUs of each node which isn't readily | |
5857 | * available. Build one from cpu_to_node() which should have been | |
5858 | * fully initialized by now. | |
5859 | */ | |
5860 | tbl = kcalloc(nr_node_ids, sizeof(tbl[0]), GFP_KERNEL); | |
5861 | BUG_ON(!tbl); | |
5862 | ||
5863 | for_each_node(node) | |
5864 | BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL, | |
5865 | node_online(node) ? node : NUMA_NO_NODE)); | |
5866 | ||
5867 | for_each_possible_cpu(cpu) { | |
5868 | node = cpu_to_node(cpu); | |
5869 | if (WARN_ON(node == NUMA_NO_NODE)) { | |
5870 | pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); | |
5871 | /* happens iff arch is bonkers, let's just proceed */ | |
5872 | return; | |
5873 | } | |
5874 | cpumask_set_cpu(cpu, tbl[node]); | |
5875 | } | |
5876 | ||
5877 | wq_numa_possible_cpumask = tbl; | |
5878 | wq_numa_enabled = true; | |
5879 | } | |
5880 | ||
5881 | /** | |
5882 | * workqueue_init_early - early init for workqueue subsystem | |
5883 | * | |
5884 | * This is the first half of two-staged workqueue subsystem initialization | |
5885 | * and invoked as soon as the bare basics - memory allocation, cpumasks and | |
5886 | * idr are up. It sets up all the data structures and system workqueues | |
5887 | * and allows early boot code to create workqueues and queue/cancel work | |
5888 | * items. Actual work item execution starts only after kthreads can be | |
5889 | * created and scheduled right before early initcalls. | |
5890 | */ | |
5891 | int __init workqueue_init_early(void) | |
5892 | { | |
5893 | int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; | |
5894 | int hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ; | |
5895 | int i, cpu; | |
5896 | ||
5897 | WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); | |
5898 | ||
5899 | BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); | |
5900 | cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(hk_flags)); | |
5901 | ||
5902 | pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); | |
5903 | ||
5904 | /* initialize CPU pools */ | |
5905 | for_each_possible_cpu(cpu) { | |
5906 | struct worker_pool *pool; | |
5907 | ||
5908 | i = 0; | |
5909 | for_each_cpu_worker_pool(pool, cpu) { | |
5910 | BUG_ON(init_worker_pool(pool)); | |
5911 | pool->cpu = cpu; | |
5912 | cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); | |
5913 | pool->attrs->nice = std_nice[i++]; | |
5914 | pool->node = cpu_to_node(cpu); | |
5915 | ||
5916 | /* alloc pool ID */ | |
5917 | mutex_lock(&wq_pool_mutex); | |
5918 | BUG_ON(worker_pool_assign_id(pool)); | |
5919 | mutex_unlock(&wq_pool_mutex); | |
5920 | } | |
5921 | } | |
5922 | ||
5923 | /* create default unbound and ordered wq attrs */ | |
5924 | for (i = 0; i < NR_STD_WORKER_POOLS; i++) { | |
5925 | struct workqueue_attrs *attrs; | |
5926 | ||
5927 | BUG_ON(!(attrs = alloc_workqueue_attrs())); | |
5928 | attrs->nice = std_nice[i]; | |
5929 | unbound_std_wq_attrs[i] = attrs; | |
5930 | ||
5931 | /* | |
5932 | * An ordered wq should have only one pwq as ordering is | |
5933 | * guaranteed by max_active which is enforced by pwqs. | |
5934 | * Turn off NUMA so that dfl_pwq is used for all nodes. | |
5935 | */ | |
5936 | BUG_ON(!(attrs = alloc_workqueue_attrs())); | |
5937 | attrs->nice = std_nice[i]; | |
5938 | attrs->no_numa = true; | |
5939 | ordered_wq_attrs[i] = attrs; | |
5940 | } | |
5941 | ||
5942 | system_wq = alloc_workqueue("events", 0, 0); | |
5943 | system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); | |
5944 | system_long_wq = alloc_workqueue("events_long", 0, 0); | |
5945 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, | |
5946 | WQ_UNBOUND_MAX_ACTIVE); | |
5947 | system_freezable_wq = alloc_workqueue("events_freezable", | |
5948 | WQ_FREEZABLE, 0); | |
5949 | system_power_efficient_wq = alloc_workqueue("events_power_efficient", | |
5950 | WQ_POWER_EFFICIENT, 0); | |
5951 | system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", | |
5952 | WQ_FREEZABLE | WQ_POWER_EFFICIENT, | |
5953 | 0); | |
5954 | BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || | |
5955 | !system_unbound_wq || !system_freezable_wq || | |
5956 | !system_power_efficient_wq || | |
5957 | !system_freezable_power_efficient_wq); | |
5958 | ||
5959 | return 0; | |
5960 | } | |
5961 | ||
5962 | /** | |
5963 | * workqueue_init - bring workqueue subsystem fully online | |
5964 | * | |
5965 | * This is the latter half of two-staged workqueue subsystem initialization | |
5966 | * and invoked as soon as kthreads can be created and scheduled. | |
5967 | * Workqueues have been created and work items queued on them, but there | |
5968 | * are no kworkers executing the work items yet. Populate the worker pools | |
5969 | * with the initial workers and enable future kworker creations. | |
5970 | */ | |
5971 | int __init workqueue_init(void) | |
5972 | { | |
5973 | struct workqueue_struct *wq; | |
5974 | struct worker_pool *pool; | |
5975 | int cpu, bkt; | |
5976 | ||
5977 | /* | |
5978 | * It'd be simpler to initialize NUMA in workqueue_init_early() but | |
5979 | * CPU to node mapping may not be available that early on some | |
5980 | * archs such as power and arm64. As per-cpu pools created | |
5981 | * previously could be missing node hint and unbound pools NUMA | |
5982 | * affinity, fix them up. | |
5983 | * | |
5984 | * Also, while iterating workqueues, create rescuers if requested. | |
5985 | */ | |
5986 | wq_numa_init(); | |
5987 | ||
5988 | mutex_lock(&wq_pool_mutex); | |
5989 | ||
5990 | for_each_possible_cpu(cpu) { | |
5991 | for_each_cpu_worker_pool(pool, cpu) { | |
5992 | pool->node = cpu_to_node(cpu); | |
5993 | } | |
5994 | } | |
5995 | ||
5996 | list_for_each_entry(wq, &workqueues, list) { | |
5997 | wq_update_unbound_numa(wq, smp_processor_id(), true); | |
5998 | WARN(init_rescuer(wq), | |
5999 | "workqueue: failed to create early rescuer for %s", | |
6000 | wq->name); | |
6001 | } | |
6002 | ||
6003 | mutex_unlock(&wq_pool_mutex); | |
6004 | ||
6005 | /* create the initial workers */ | |
6006 | for_each_online_cpu(cpu) { | |
6007 | for_each_cpu_worker_pool(pool, cpu) { | |
6008 | pool->flags &= ~POOL_DISASSOCIATED; | |
6009 | BUG_ON(!create_worker(pool)); | |
6010 | } | |
6011 | } | |
6012 | ||
6013 | hash_for_each(unbound_pool_hash, bkt, pool, hash_node) | |
6014 | BUG_ON(!create_worker(pool)); | |
6015 | ||
6016 | wq_online = true; | |
6017 | wq_watchdog_init(); | |
6018 | ||
6019 | return 0; | |
6020 | } |