]>
Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
c54fce6e | 2 | * kernel/workqueue.c - generic async execution with shared worker pool |
1da177e4 | 3 | * |
c54fce6e | 4 | * Copyright (C) 2002 Ingo Molnar |
1da177e4 | 5 | * |
c54fce6e TH |
6 | * Derived from the taskqueue/keventd code by: |
7 | * David Woodhouse <dwmw2@infradead.org> | |
8 | * Andrew Morton | |
9 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> | |
10 | * Theodore Ts'o <tytso@mit.edu> | |
1da177e4 | 11 | * |
c54fce6e | 12 | * Made to use alloc_percpu by Christoph Lameter. |
1da177e4 | 13 | * |
c54fce6e TH |
14 | * Copyright (C) 2010 SUSE Linux Products GmbH |
15 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> | |
89ada679 | 16 | * |
c54fce6e TH |
17 | * This is the generic async execution mechanism. Work items as are |
18 | * executed in process context. The worker pool is shared and | |
b11895c4 L |
19 | * automatically managed. There are two worker pools for each CPU (one for |
20 | * normal work items and the other for high priority ones) and some extra | |
21 | * pools for workqueues which are not bound to any specific CPU - the | |
22 | * number of these backing pools is dynamic. | |
c54fce6e TH |
23 | * |
24 | * Please read Documentation/workqueue.txt for details. | |
1da177e4 LT |
25 | */ |
26 | ||
9984de1a | 27 | #include <linux/export.h> |
1da177e4 LT |
28 | #include <linux/kernel.h> |
29 | #include <linux/sched.h> | |
30 | #include <linux/init.h> | |
31 | #include <linux/signal.h> | |
32 | #include <linux/completion.h> | |
33 | #include <linux/workqueue.h> | |
34 | #include <linux/slab.h> | |
35 | #include <linux/cpu.h> | |
36 | #include <linux/notifier.h> | |
37 | #include <linux/kthread.h> | |
1fa44eca | 38 | #include <linux/hardirq.h> |
46934023 | 39 | #include <linux/mempolicy.h> |
341a5958 | 40 | #include <linux/freezer.h> |
d5abe669 PZ |
41 | #include <linux/kallsyms.h> |
42 | #include <linux/debug_locks.h> | |
4e6045f1 | 43 | #include <linux/lockdep.h> |
c34056a3 | 44 | #include <linux/idr.h> |
29c91e99 | 45 | #include <linux/jhash.h> |
42f8570f | 46 | #include <linux/hashtable.h> |
76af4d93 | 47 | #include <linux/rculist.h> |
bce90380 | 48 | #include <linux/nodemask.h> |
4c16bd32 | 49 | #include <linux/moduleparam.h> |
3d1cb205 | 50 | #include <linux/uaccess.h> |
e22bee78 | 51 | |
ea138446 | 52 | #include "workqueue_internal.h" |
1da177e4 | 53 | |
c8e55f36 | 54 | enum { |
24647570 TH |
55 | /* |
56 | * worker_pool flags | |
bc2ae0f5 | 57 | * |
24647570 | 58 | * A bound pool is either associated or disassociated with its CPU. |
bc2ae0f5 TH |
59 | * While associated (!DISASSOCIATED), all workers are bound to the |
60 | * CPU and none has %WORKER_UNBOUND set and concurrency management | |
61 | * is in effect. | |
62 | * | |
63 | * While DISASSOCIATED, the cpu may be offline and all workers have | |
64 | * %WORKER_UNBOUND set and concurrency management disabled, and may | |
24647570 | 65 | * be executing on any CPU. The pool behaves as an unbound one. |
bc2ae0f5 | 66 | * |
bc3a1afc | 67 | * Note that DISASSOCIATED should be flipped only while holding |
92f9c5c4 | 68 | * attach_mutex to avoid changing binding state while |
4736cbf7 | 69 | * worker_attach_to_pool() is in progress. |
bc2ae0f5 | 70 | */ |
24647570 | 71 | POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
db7bccf4 | 72 | |
c8e55f36 | 73 | /* worker flags */ |
c8e55f36 TH |
74 | WORKER_DIE = 1 << 1, /* die die die */ |
75 | WORKER_IDLE = 1 << 2, /* is idle */ | |
e22bee78 | 76 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
fb0e7beb | 77 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
f3421797 | 78 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
a9ab775b | 79 | WORKER_REBOUND = 1 << 8, /* worker was rebound */ |
e22bee78 | 80 | |
a9ab775b TH |
81 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | |
82 | WORKER_UNBOUND | WORKER_REBOUND, | |
db7bccf4 | 83 | |
e34cdddb | 84 | NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ |
4ce62e9e | 85 | |
29c91e99 | 86 | UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ |
c8e55f36 | 87 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
db7bccf4 | 88 | |
e22bee78 TH |
89 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
90 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ | |
91 | ||
3233cdbd TH |
92 | MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, |
93 | /* call for help after 10ms | |
94 | (min two ticks) */ | |
e22bee78 TH |
95 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
96 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ | |
e22bee78 TH |
97 | |
98 | /* | |
99 | * Rescue workers are used only on emergencies and shared by | |
8698a745 | 100 | * all cpus. Give MIN_NICE. |
e22bee78 | 101 | */ |
8698a745 DY |
102 | RESCUER_NICE_LEVEL = MIN_NICE, |
103 | HIGHPRI_NICE_LEVEL = MIN_NICE, | |
ecf6881f TH |
104 | |
105 | WQ_NAME_LEN = 24, | |
c8e55f36 | 106 | }; |
1da177e4 LT |
107 | |
108 | /* | |
4690c4ab TH |
109 | * Structure fields follow one of the following exclusion rules. |
110 | * | |
e41e704b TH |
111 | * I: Modifiable by initialization/destruction paths and read-only for |
112 | * everyone else. | |
4690c4ab | 113 | * |
e22bee78 TH |
114 | * P: Preemption protected. Disabling preemption is enough and should |
115 | * only be modified and accessed from the local cpu. | |
116 | * | |
d565ed63 | 117 | * L: pool->lock protected. Access with pool->lock held. |
4690c4ab | 118 | * |
d565ed63 TH |
119 | * X: During normal operation, modification requires pool->lock and should |
120 | * be done only from local cpu. Either disabling preemption on local | |
121 | * cpu or grabbing pool->lock is enough for read access. If | |
122 | * POOL_DISASSOCIATED is set, it's identical to L. | |
e22bee78 | 123 | * |
92f9c5c4 | 124 | * A: pool->attach_mutex protected. |
822d8405 | 125 | * |
68e13a67 | 126 | * PL: wq_pool_mutex protected. |
5bcab335 | 127 | * |
68e13a67 | 128 | * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads. |
76af4d93 | 129 | * |
5b95e1af LJ |
130 | * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. |
131 | * | |
132 | * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or | |
133 | * sched-RCU for reads. | |
134 | * | |
3c25a55d LJ |
135 | * WQ: wq->mutex protected. |
136 | * | |
b5927605 | 137 | * WR: wq->mutex protected for writes. Sched-RCU protected for reads. |
2e109a28 TH |
138 | * |
139 | * MD: wq_mayday_lock protected. | |
1da177e4 | 140 | */ |
1da177e4 | 141 | |
2eaebdb3 | 142 | /* struct worker is defined in workqueue_internal.h */ |
c34056a3 | 143 | |
bd7bdd43 | 144 | struct worker_pool { |
d565ed63 | 145 | spinlock_t lock; /* the pool lock */ |
d84ff051 | 146 | int cpu; /* I: the associated cpu */ |
f3f90ad4 | 147 | int node; /* I: the associated node ID */ |
9daf9e67 | 148 | int id; /* I: pool ID */ |
11ebea50 | 149 | unsigned int flags; /* X: flags */ |
bd7bdd43 | 150 | |
82607adc TH |
151 | unsigned long watchdog_ts; /* L: watchdog timestamp */ |
152 | ||
bd7bdd43 TH |
153 | struct list_head worklist; /* L: list of pending works */ |
154 | int nr_workers; /* L: total number of workers */ | |
ea1abd61 LJ |
155 | |
156 | /* nr_idle includes the ones off idle_list for rebinding */ | |
bd7bdd43 TH |
157 | int nr_idle; /* L: currently idle ones */ |
158 | ||
159 | struct list_head idle_list; /* X: list of idle workers */ | |
160 | struct timer_list idle_timer; /* L: worker idle timeout */ | |
161 | struct timer_list mayday_timer; /* L: SOS timer for workers */ | |
162 | ||
c5aa87bb | 163 | /* a workers is either on busy_hash or idle_list, or the manager */ |
c9e7cf27 TH |
164 | DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); |
165 | /* L: hash of busy workers */ | |
166 | ||
bc3a1afc | 167 | /* see manage_workers() for details on the two manager mutexes */ |
34a06bd6 | 168 | struct mutex manager_arb; /* manager arbitration */ |
2607d7a6 | 169 | struct worker *manager; /* L: purely informational */ |
92f9c5c4 LJ |
170 | struct mutex attach_mutex; /* attach/detach exclusion */ |
171 | struct list_head workers; /* A: attached workers */ | |
60f5a4bc | 172 | struct completion *detach_completion; /* all workers detached */ |
e19e397a | 173 | |
7cda9aae | 174 | struct ida worker_ida; /* worker IDs for task name */ |
e19e397a | 175 | |
7a4e344c | 176 | struct workqueue_attrs *attrs; /* I: worker attributes */ |
68e13a67 LJ |
177 | struct hlist_node hash_node; /* PL: unbound_pool_hash node */ |
178 | int refcnt; /* PL: refcnt for unbound pools */ | |
7a4e344c | 179 | |
e19e397a TH |
180 | /* |
181 | * The current concurrency level. As it's likely to be accessed | |
182 | * from other CPUs during try_to_wake_up(), put it in a separate | |
183 | * cacheline. | |
184 | */ | |
185 | atomic_t nr_running ____cacheline_aligned_in_smp; | |
29c91e99 TH |
186 | |
187 | /* | |
188 | * Destruction of pool is sched-RCU protected to allow dereferences | |
189 | * from get_work_pool(). | |
190 | */ | |
191 | struct rcu_head rcu; | |
8b03ae3c TH |
192 | } ____cacheline_aligned_in_smp; |
193 | ||
1da177e4 | 194 | /* |
112202d9 TH |
195 | * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS |
196 | * of work_struct->data are used for flags and the remaining high bits | |
197 | * point to the pwq; thus, pwqs need to be aligned at two's power of the | |
198 | * number of flag bits. | |
1da177e4 | 199 | */ |
112202d9 | 200 | struct pool_workqueue { |
bd7bdd43 | 201 | struct worker_pool *pool; /* I: the associated pool */ |
4690c4ab | 202 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
73f53c4a TH |
203 | int work_color; /* L: current color */ |
204 | int flush_color; /* L: flushing color */ | |
8864b4e5 | 205 | int refcnt; /* L: reference count */ |
73f53c4a TH |
206 | int nr_in_flight[WORK_NR_COLORS]; |
207 | /* L: nr of in_flight works */ | |
1e19ffc6 | 208 | int nr_active; /* L: nr of active works */ |
a0a1a5fd | 209 | int max_active; /* L: max active works */ |
1e19ffc6 | 210 | struct list_head delayed_works; /* L: delayed works */ |
3c25a55d | 211 | struct list_head pwqs_node; /* WR: node on wq->pwqs */ |
2e109a28 | 212 | struct list_head mayday_node; /* MD: node on wq->maydays */ |
8864b4e5 TH |
213 | |
214 | /* | |
215 | * Release of unbound pwq is punted to system_wq. See put_pwq() | |
216 | * and pwq_unbound_release_workfn() for details. pool_workqueue | |
217 | * itself is also sched-RCU protected so that the first pwq can be | |
b09f4fd3 | 218 | * determined without grabbing wq->mutex. |
8864b4e5 TH |
219 | */ |
220 | struct work_struct unbound_release_work; | |
221 | struct rcu_head rcu; | |
e904e6c2 | 222 | } __aligned(1 << WORK_STRUCT_FLAG_BITS); |
1da177e4 | 223 | |
73f53c4a TH |
224 | /* |
225 | * Structure used to wait for workqueue flush. | |
226 | */ | |
227 | struct wq_flusher { | |
3c25a55d LJ |
228 | struct list_head list; /* WQ: list of flushers */ |
229 | int flush_color; /* WQ: flush color waiting for */ | |
73f53c4a TH |
230 | struct completion done; /* flush completion */ |
231 | }; | |
232 | ||
226223ab TH |
233 | struct wq_device; |
234 | ||
1da177e4 | 235 | /* |
c5aa87bb TH |
236 | * The externally visible workqueue. It relays the issued work items to |
237 | * the appropriate worker_pool through its pool_workqueues. | |
1da177e4 LT |
238 | */ |
239 | struct workqueue_struct { | |
3c25a55d | 240 | struct list_head pwqs; /* WR: all pwqs of this wq */ |
e2dca7ad | 241 | struct list_head list; /* PR: list of all workqueues */ |
73f53c4a | 242 | |
3c25a55d LJ |
243 | struct mutex mutex; /* protects this wq */ |
244 | int work_color; /* WQ: current work color */ | |
245 | int flush_color; /* WQ: current flush color */ | |
112202d9 | 246 | atomic_t nr_pwqs_to_flush; /* flush in progress */ |
3c25a55d LJ |
247 | struct wq_flusher *first_flusher; /* WQ: first flusher */ |
248 | struct list_head flusher_queue; /* WQ: flush waiters */ | |
249 | struct list_head flusher_overflow; /* WQ: flush overflow list */ | |
73f53c4a | 250 | |
2e109a28 | 251 | struct list_head maydays; /* MD: pwqs requesting rescue */ |
e22bee78 TH |
252 | struct worker *rescuer; /* I: rescue worker */ |
253 | ||
87fc741e | 254 | int nr_drainers; /* WQ: drain in progress */ |
a357fc03 | 255 | int saved_max_active; /* WQ: saved pwq max_active */ |
226223ab | 256 | |
5b95e1af LJ |
257 | struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ |
258 | struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */ | |
6029a918 | 259 | |
226223ab TH |
260 | #ifdef CONFIG_SYSFS |
261 | struct wq_device *wq_dev; /* I: for sysfs interface */ | |
262 | #endif | |
4e6045f1 | 263 | #ifdef CONFIG_LOCKDEP |
4690c4ab | 264 | struct lockdep_map lockdep_map; |
4e6045f1 | 265 | #endif |
ecf6881f | 266 | char name[WQ_NAME_LEN]; /* I: workqueue name */ |
2728fd2f | 267 | |
e2dca7ad TH |
268 | /* |
269 | * Destruction of workqueue_struct is sched-RCU protected to allow | |
270 | * walking the workqueues list without grabbing wq_pool_mutex. | |
271 | * This is used to dump all workqueues from sysrq. | |
272 | */ | |
273 | struct rcu_head rcu; | |
274 | ||
2728fd2f TH |
275 | /* hot fields used during command issue, aligned to cacheline */ |
276 | unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ | |
277 | struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ | |
5b95e1af | 278 | struct pool_workqueue __rcu *numa_pwq_tbl[]; /* PWR: unbound pwqs indexed by node */ |
1da177e4 LT |
279 | }; |
280 | ||
e904e6c2 TH |
281 | static struct kmem_cache *pwq_cache; |
282 | ||
bce90380 TH |
283 | static cpumask_var_t *wq_numa_possible_cpumask; |
284 | /* possible CPUs of each node */ | |
285 | ||
d55262c4 TH |
286 | static bool wq_disable_numa; |
287 | module_param_named(disable_numa, wq_disable_numa, bool, 0444); | |
288 | ||
cee22a15 | 289 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ |
552f530c | 290 | static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); |
cee22a15 VK |
291 | module_param_named(power_efficient, wq_power_efficient, bool, 0444); |
292 | ||
bce90380 TH |
293 | static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ |
294 | ||
4c16bd32 TH |
295 | /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ |
296 | static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; | |
297 | ||
68e13a67 | 298 | static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ |
2e109a28 | 299 | static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ |
5bcab335 | 300 | |
e2dca7ad | 301 | static LIST_HEAD(workqueues); /* PR: list of all workqueues */ |
68e13a67 | 302 | static bool workqueue_freezing; /* PL: have wqs started freezing? */ |
7d19c5ce | 303 | |
ef557180 MG |
304 | /* PL: allowable cpus for unbound wqs and work items */ |
305 | static cpumask_var_t wq_unbound_cpumask; | |
306 | ||
307 | /* CPU where unbound work was last round robin scheduled from this CPU */ | |
308 | static DEFINE_PER_CPU(int, wq_rr_cpu_last); | |
b05a7928 | 309 | |
f303fccb TH |
310 | /* |
311 | * Local execution of unbound work items is no longer guaranteed. The | |
312 | * following always forces round-robin CPU selection on unbound work items | |
313 | * to uncover usages which depend on it. | |
314 | */ | |
315 | #ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU | |
316 | static bool wq_debug_force_rr_cpu = true; | |
317 | #else | |
318 | static bool wq_debug_force_rr_cpu = false; | |
319 | #endif | |
320 | module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); | |
321 | ||
7d19c5ce TH |
322 | /* the per-cpu worker pools */ |
323 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], | |
324 | cpu_worker_pools); | |
325 | ||
68e13a67 | 326 | static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ |
7d19c5ce | 327 | |
68e13a67 | 328 | /* PL: hash of all unbound pools keyed by pool->attrs */ |
29c91e99 TH |
329 | static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); |
330 | ||
c5aa87bb | 331 | /* I: attributes used when instantiating standard unbound pools on demand */ |
29c91e99 TH |
332 | static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; |
333 | ||
8a2b7538 TH |
334 | /* I: attributes used when instantiating ordered pools on demand */ |
335 | static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; | |
336 | ||
d320c038 | 337 | struct workqueue_struct *system_wq __read_mostly; |
ad7b1f84 | 338 | EXPORT_SYMBOL(system_wq); |
044c782c | 339 | struct workqueue_struct *system_highpri_wq __read_mostly; |
1aabe902 | 340 | EXPORT_SYMBOL_GPL(system_highpri_wq); |
044c782c | 341 | struct workqueue_struct *system_long_wq __read_mostly; |
d320c038 | 342 | EXPORT_SYMBOL_GPL(system_long_wq); |
044c782c | 343 | struct workqueue_struct *system_unbound_wq __read_mostly; |
f3421797 | 344 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
044c782c | 345 | struct workqueue_struct *system_freezable_wq __read_mostly; |
24d51add | 346 | EXPORT_SYMBOL_GPL(system_freezable_wq); |
0668106c VK |
347 | struct workqueue_struct *system_power_efficient_wq __read_mostly; |
348 | EXPORT_SYMBOL_GPL(system_power_efficient_wq); | |
349 | struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; | |
350 | EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); | |
d320c038 | 351 | |
7d19c5ce | 352 | static int worker_thread(void *__worker); |
6ba94429 | 353 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq); |
7d19c5ce | 354 | |
97bd2347 TH |
355 | #define CREATE_TRACE_POINTS |
356 | #include <trace/events/workqueue.h> | |
357 | ||
68e13a67 | 358 | #define assert_rcu_or_pool_mutex() \ |
f78f5b90 PM |
359 | RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held() && \ |
360 | !lockdep_is_held(&wq_pool_mutex), \ | |
361 | "sched RCU or wq_pool_mutex should be held") | |
5bcab335 | 362 | |
b09f4fd3 | 363 | #define assert_rcu_or_wq_mutex(wq) \ |
f78f5b90 PM |
364 | RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held() && \ |
365 | !lockdep_is_held(&wq->mutex), \ | |
366 | "sched RCU or wq->mutex should be held") | |
76af4d93 | 367 | |
5b95e1af | 368 | #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \ |
f78f5b90 PM |
369 | RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held() && \ |
370 | !lockdep_is_held(&wq->mutex) && \ | |
371 | !lockdep_is_held(&wq_pool_mutex), \ | |
372 | "sched RCU, wq->mutex or wq_pool_mutex should be held") | |
5b95e1af | 373 | |
f02ae73a TH |
374 | #define for_each_cpu_worker_pool(pool, cpu) \ |
375 | for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ | |
376 | (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ | |
7a62c2c8 | 377 | (pool)++) |
4ce62e9e | 378 | |
17116969 TH |
379 | /** |
380 | * for_each_pool - iterate through all worker_pools in the system | |
381 | * @pool: iteration cursor | |
611c92a0 | 382 | * @pi: integer used for iteration |
fa1b54e6 | 383 | * |
68e13a67 LJ |
384 | * This must be called either with wq_pool_mutex held or sched RCU read |
385 | * locked. If the pool needs to be used beyond the locking in effect, the | |
386 | * caller is responsible for guaranteeing that the pool stays online. | |
fa1b54e6 TH |
387 | * |
388 | * The if/else clause exists only for the lockdep assertion and can be | |
389 | * ignored. | |
17116969 | 390 | */ |
611c92a0 TH |
391 | #define for_each_pool(pool, pi) \ |
392 | idr_for_each_entry(&worker_pool_idr, pool, pi) \ | |
68e13a67 | 393 | if (({ assert_rcu_or_pool_mutex(); false; })) { } \ |
fa1b54e6 | 394 | else |
17116969 | 395 | |
822d8405 TH |
396 | /** |
397 | * for_each_pool_worker - iterate through all workers of a worker_pool | |
398 | * @worker: iteration cursor | |
822d8405 TH |
399 | * @pool: worker_pool to iterate workers of |
400 | * | |
92f9c5c4 | 401 | * This must be called with @pool->attach_mutex. |
822d8405 TH |
402 | * |
403 | * The if/else clause exists only for the lockdep assertion and can be | |
404 | * ignored. | |
405 | */ | |
da028469 LJ |
406 | #define for_each_pool_worker(worker, pool) \ |
407 | list_for_each_entry((worker), &(pool)->workers, node) \ | |
92f9c5c4 | 408 | if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \ |
822d8405 TH |
409 | else |
410 | ||
49e3cf44 TH |
411 | /** |
412 | * for_each_pwq - iterate through all pool_workqueues of the specified workqueue | |
413 | * @pwq: iteration cursor | |
414 | * @wq: the target workqueue | |
76af4d93 | 415 | * |
b09f4fd3 | 416 | * This must be called either with wq->mutex held or sched RCU read locked. |
794b18bc TH |
417 | * If the pwq needs to be used beyond the locking in effect, the caller is |
418 | * responsible for guaranteeing that the pwq stays online. | |
76af4d93 TH |
419 | * |
420 | * The if/else clause exists only for the lockdep assertion and can be | |
421 | * ignored. | |
49e3cf44 TH |
422 | */ |
423 | #define for_each_pwq(pwq, wq) \ | |
76af4d93 | 424 | list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \ |
b09f4fd3 | 425 | if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ |
76af4d93 | 426 | else |
f3421797 | 427 | |
dc186ad7 TG |
428 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
429 | ||
430 | static struct debug_obj_descr work_debug_descr; | |
431 | ||
99777288 SG |
432 | static void *work_debug_hint(void *addr) |
433 | { | |
434 | return ((struct work_struct *) addr)->func; | |
435 | } | |
436 | ||
dc186ad7 TG |
437 | /* |
438 | * fixup_init is called when: | |
439 | * - an active object is initialized | |
440 | */ | |
441 | static int work_fixup_init(void *addr, enum debug_obj_state state) | |
442 | { | |
443 | struct work_struct *work = addr; | |
444 | ||
445 | switch (state) { | |
446 | case ODEBUG_STATE_ACTIVE: | |
447 | cancel_work_sync(work); | |
448 | debug_object_init(work, &work_debug_descr); | |
449 | return 1; | |
450 | default: | |
451 | return 0; | |
452 | } | |
453 | } | |
454 | ||
455 | /* | |
456 | * fixup_activate is called when: | |
457 | * - an active object is activated | |
458 | * - an unknown object is activated (might be a statically initialized object) | |
459 | */ | |
460 | static int work_fixup_activate(void *addr, enum debug_obj_state state) | |
461 | { | |
462 | struct work_struct *work = addr; | |
463 | ||
464 | switch (state) { | |
465 | ||
466 | case ODEBUG_STATE_NOTAVAILABLE: | |
467 | /* | |
468 | * This is not really a fixup. The work struct was | |
469 | * statically initialized. We just make sure that it | |
470 | * is tracked in the object tracker. | |
471 | */ | |
22df02bb | 472 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
dc186ad7 TG |
473 | debug_object_init(work, &work_debug_descr); |
474 | debug_object_activate(work, &work_debug_descr); | |
475 | return 0; | |
476 | } | |
477 | WARN_ON_ONCE(1); | |
478 | return 0; | |
479 | ||
480 | case ODEBUG_STATE_ACTIVE: | |
481 | WARN_ON(1); | |
482 | ||
483 | default: | |
484 | return 0; | |
485 | } | |
486 | } | |
487 | ||
488 | /* | |
489 | * fixup_free is called when: | |
490 | * - an active object is freed | |
491 | */ | |
492 | static int work_fixup_free(void *addr, enum debug_obj_state state) | |
493 | { | |
494 | struct work_struct *work = addr; | |
495 | ||
496 | switch (state) { | |
497 | case ODEBUG_STATE_ACTIVE: | |
498 | cancel_work_sync(work); | |
499 | debug_object_free(work, &work_debug_descr); | |
500 | return 1; | |
501 | default: | |
502 | return 0; | |
503 | } | |
504 | } | |
505 | ||
506 | static struct debug_obj_descr work_debug_descr = { | |
507 | .name = "work_struct", | |
99777288 | 508 | .debug_hint = work_debug_hint, |
dc186ad7 TG |
509 | .fixup_init = work_fixup_init, |
510 | .fixup_activate = work_fixup_activate, | |
511 | .fixup_free = work_fixup_free, | |
512 | }; | |
513 | ||
514 | static inline void debug_work_activate(struct work_struct *work) | |
515 | { | |
516 | debug_object_activate(work, &work_debug_descr); | |
517 | } | |
518 | ||
519 | static inline void debug_work_deactivate(struct work_struct *work) | |
520 | { | |
521 | debug_object_deactivate(work, &work_debug_descr); | |
522 | } | |
523 | ||
524 | void __init_work(struct work_struct *work, int onstack) | |
525 | { | |
526 | if (onstack) | |
527 | debug_object_init_on_stack(work, &work_debug_descr); | |
528 | else | |
529 | debug_object_init(work, &work_debug_descr); | |
530 | } | |
531 | EXPORT_SYMBOL_GPL(__init_work); | |
532 | ||
533 | void destroy_work_on_stack(struct work_struct *work) | |
534 | { | |
535 | debug_object_free(work, &work_debug_descr); | |
536 | } | |
537 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); | |
538 | ||
ea2e64f2 TG |
539 | void destroy_delayed_work_on_stack(struct delayed_work *work) |
540 | { | |
541 | destroy_timer_on_stack(&work->timer); | |
542 | debug_object_free(&work->work, &work_debug_descr); | |
543 | } | |
544 | EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); | |
545 | ||
dc186ad7 TG |
546 | #else |
547 | static inline void debug_work_activate(struct work_struct *work) { } | |
548 | static inline void debug_work_deactivate(struct work_struct *work) { } | |
549 | #endif | |
550 | ||
4e8b22bd LB |
551 | /** |
552 | * worker_pool_assign_id - allocate ID and assing it to @pool | |
553 | * @pool: the pool pointer of interest | |
554 | * | |
555 | * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned | |
556 | * successfully, -errno on failure. | |
557 | */ | |
9daf9e67 TH |
558 | static int worker_pool_assign_id(struct worker_pool *pool) |
559 | { | |
560 | int ret; | |
561 | ||
68e13a67 | 562 | lockdep_assert_held(&wq_pool_mutex); |
5bcab335 | 563 | |
4e8b22bd LB |
564 | ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, |
565 | GFP_KERNEL); | |
229641a6 | 566 | if (ret >= 0) { |
e68035fb | 567 | pool->id = ret; |
229641a6 TH |
568 | return 0; |
569 | } | |
fa1b54e6 | 570 | return ret; |
7c3eed5c TH |
571 | } |
572 | ||
df2d5ae4 TH |
573 | /** |
574 | * unbound_pwq_by_node - return the unbound pool_workqueue for the given node | |
575 | * @wq: the target workqueue | |
576 | * @node: the node ID | |
577 | * | |
5b95e1af LJ |
578 | * This must be called with any of wq_pool_mutex, wq->mutex or sched RCU |
579 | * read locked. | |
df2d5ae4 TH |
580 | * If the pwq needs to be used beyond the locking in effect, the caller is |
581 | * responsible for guaranteeing that the pwq stays online. | |
d185af30 YB |
582 | * |
583 | * Return: The unbound pool_workqueue for @node. | |
df2d5ae4 TH |
584 | */ |
585 | static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, | |
586 | int node) | |
587 | { | |
5b95e1af | 588 | assert_rcu_or_wq_mutex_or_pool_mutex(wq); |
df2d5ae4 TH |
589 | return rcu_dereference_raw(wq->numa_pwq_tbl[node]); |
590 | } | |
591 | ||
73f53c4a TH |
592 | static unsigned int work_color_to_flags(int color) |
593 | { | |
594 | return color << WORK_STRUCT_COLOR_SHIFT; | |
595 | } | |
596 | ||
597 | static int get_work_color(struct work_struct *work) | |
598 | { | |
599 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & | |
600 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); | |
601 | } | |
602 | ||
603 | static int work_next_color(int color) | |
604 | { | |
605 | return (color + 1) % WORK_NR_COLORS; | |
606 | } | |
1da177e4 | 607 | |
14441960 | 608 | /* |
112202d9 TH |
609 | * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data |
610 | * contain the pointer to the queued pwq. Once execution starts, the flag | |
7c3eed5c | 611 | * is cleared and the high bits contain OFFQ flags and pool ID. |
7a22ad75 | 612 | * |
112202d9 TH |
613 | * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() |
614 | * and clear_work_data() can be used to set the pwq, pool or clear | |
bbb68dfa TH |
615 | * work->data. These functions should only be called while the work is |
616 | * owned - ie. while the PENDING bit is set. | |
7a22ad75 | 617 | * |
112202d9 | 618 | * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq |
7c3eed5c | 619 | * corresponding to a work. Pool is available once the work has been |
112202d9 | 620 | * queued anywhere after initialization until it is sync canceled. pwq is |
7c3eed5c | 621 | * available only while the work item is queued. |
7a22ad75 | 622 | * |
bbb68dfa TH |
623 | * %WORK_OFFQ_CANCELING is used to mark a work item which is being |
624 | * canceled. While being canceled, a work item may have its PENDING set | |
625 | * but stay off timer and worklist for arbitrarily long and nobody should | |
626 | * try to steal the PENDING bit. | |
14441960 | 627 | */ |
7a22ad75 TH |
628 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
629 | unsigned long flags) | |
365970a1 | 630 | { |
6183c009 | 631 | WARN_ON_ONCE(!work_pending(work)); |
7a22ad75 TH |
632 | atomic_long_set(&work->data, data | flags | work_static(work)); |
633 | } | |
365970a1 | 634 | |
112202d9 | 635 | static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, |
7a22ad75 TH |
636 | unsigned long extra_flags) |
637 | { | |
112202d9 TH |
638 | set_work_data(work, (unsigned long)pwq, |
639 | WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); | |
365970a1 DH |
640 | } |
641 | ||
4468a00f LJ |
642 | static void set_work_pool_and_keep_pending(struct work_struct *work, |
643 | int pool_id) | |
644 | { | |
645 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, | |
646 | WORK_STRUCT_PENDING); | |
647 | } | |
648 | ||
7c3eed5c TH |
649 | static void set_work_pool_and_clear_pending(struct work_struct *work, |
650 | int pool_id) | |
7a22ad75 | 651 | { |
23657bb1 TH |
652 | /* |
653 | * The following wmb is paired with the implied mb in | |
654 | * test_and_set_bit(PENDING) and ensures all updates to @work made | |
655 | * here are visible to and precede any updates by the next PENDING | |
656 | * owner. | |
657 | */ | |
658 | smp_wmb(); | |
7c3eed5c | 659 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); |
7a22ad75 | 660 | } |
f756d5e2 | 661 | |
7a22ad75 | 662 | static void clear_work_data(struct work_struct *work) |
1da177e4 | 663 | { |
7c3eed5c TH |
664 | smp_wmb(); /* see set_work_pool_and_clear_pending() */ |
665 | set_work_data(work, WORK_STRUCT_NO_POOL, 0); | |
1da177e4 LT |
666 | } |
667 | ||
112202d9 | 668 | static struct pool_workqueue *get_work_pwq(struct work_struct *work) |
b1f4ec17 | 669 | { |
e120153d | 670 | unsigned long data = atomic_long_read(&work->data); |
7a22ad75 | 671 | |
112202d9 | 672 | if (data & WORK_STRUCT_PWQ) |
e120153d TH |
673 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
674 | else | |
675 | return NULL; | |
4d707b9f ON |
676 | } |
677 | ||
7c3eed5c TH |
678 | /** |
679 | * get_work_pool - return the worker_pool a given work was associated with | |
680 | * @work: the work item of interest | |
681 | * | |
68e13a67 LJ |
682 | * Pools are created and destroyed under wq_pool_mutex, and allows read |
683 | * access under sched-RCU read lock. As such, this function should be | |
684 | * called under wq_pool_mutex or with preemption disabled. | |
fa1b54e6 TH |
685 | * |
686 | * All fields of the returned pool are accessible as long as the above | |
687 | * mentioned locking is in effect. If the returned pool needs to be used | |
688 | * beyond the critical section, the caller is responsible for ensuring the | |
689 | * returned pool is and stays online. | |
d185af30 YB |
690 | * |
691 | * Return: The worker_pool @work was last associated with. %NULL if none. | |
7c3eed5c TH |
692 | */ |
693 | static struct worker_pool *get_work_pool(struct work_struct *work) | |
365970a1 | 694 | { |
e120153d | 695 | unsigned long data = atomic_long_read(&work->data); |
7c3eed5c | 696 | int pool_id; |
7a22ad75 | 697 | |
68e13a67 | 698 | assert_rcu_or_pool_mutex(); |
fa1b54e6 | 699 | |
112202d9 TH |
700 | if (data & WORK_STRUCT_PWQ) |
701 | return ((struct pool_workqueue *) | |
7c3eed5c | 702 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool; |
7a22ad75 | 703 | |
7c3eed5c TH |
704 | pool_id = data >> WORK_OFFQ_POOL_SHIFT; |
705 | if (pool_id == WORK_OFFQ_POOL_NONE) | |
7a22ad75 TH |
706 | return NULL; |
707 | ||
fa1b54e6 | 708 | return idr_find(&worker_pool_idr, pool_id); |
7c3eed5c TH |
709 | } |
710 | ||
711 | /** | |
712 | * get_work_pool_id - return the worker pool ID a given work is associated with | |
713 | * @work: the work item of interest | |
714 | * | |
d185af30 | 715 | * Return: The worker_pool ID @work was last associated with. |
7c3eed5c TH |
716 | * %WORK_OFFQ_POOL_NONE if none. |
717 | */ | |
718 | static int get_work_pool_id(struct work_struct *work) | |
719 | { | |
54d5b7d0 LJ |
720 | unsigned long data = atomic_long_read(&work->data); |
721 | ||
112202d9 TH |
722 | if (data & WORK_STRUCT_PWQ) |
723 | return ((struct pool_workqueue *) | |
54d5b7d0 | 724 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; |
7c3eed5c | 725 | |
54d5b7d0 | 726 | return data >> WORK_OFFQ_POOL_SHIFT; |
7c3eed5c TH |
727 | } |
728 | ||
bbb68dfa TH |
729 | static void mark_work_canceling(struct work_struct *work) |
730 | { | |
7c3eed5c | 731 | unsigned long pool_id = get_work_pool_id(work); |
bbb68dfa | 732 | |
7c3eed5c TH |
733 | pool_id <<= WORK_OFFQ_POOL_SHIFT; |
734 | set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); | |
bbb68dfa TH |
735 | } |
736 | ||
737 | static bool work_is_canceling(struct work_struct *work) | |
738 | { | |
739 | unsigned long data = atomic_long_read(&work->data); | |
740 | ||
112202d9 | 741 | return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); |
bbb68dfa TH |
742 | } |
743 | ||
e22bee78 | 744 | /* |
3270476a TH |
745 | * Policy functions. These define the policies on how the global worker |
746 | * pools are managed. Unless noted otherwise, these functions assume that | |
d565ed63 | 747 | * they're being called with pool->lock held. |
e22bee78 TH |
748 | */ |
749 | ||
63d95a91 | 750 | static bool __need_more_worker(struct worker_pool *pool) |
a848e3b6 | 751 | { |
e19e397a | 752 | return !atomic_read(&pool->nr_running); |
a848e3b6 ON |
753 | } |
754 | ||
4594bf15 | 755 | /* |
e22bee78 TH |
756 | * Need to wake up a worker? Called from anything but currently |
757 | * running workers. | |
974271c4 TH |
758 | * |
759 | * Note that, because unbound workers never contribute to nr_running, this | |
706026c2 | 760 | * function will always return %true for unbound pools as long as the |
974271c4 | 761 | * worklist isn't empty. |
4594bf15 | 762 | */ |
63d95a91 | 763 | static bool need_more_worker(struct worker_pool *pool) |
365970a1 | 764 | { |
63d95a91 | 765 | return !list_empty(&pool->worklist) && __need_more_worker(pool); |
e22bee78 | 766 | } |
4594bf15 | 767 | |
e22bee78 | 768 | /* Can I start working? Called from busy but !running workers. */ |
63d95a91 | 769 | static bool may_start_working(struct worker_pool *pool) |
e22bee78 | 770 | { |
63d95a91 | 771 | return pool->nr_idle; |
e22bee78 TH |
772 | } |
773 | ||
774 | /* Do I need to keep working? Called from currently running workers. */ | |
63d95a91 | 775 | static bool keep_working(struct worker_pool *pool) |
e22bee78 | 776 | { |
e19e397a TH |
777 | return !list_empty(&pool->worklist) && |
778 | atomic_read(&pool->nr_running) <= 1; | |
e22bee78 TH |
779 | } |
780 | ||
781 | /* Do we need a new worker? Called from manager. */ | |
63d95a91 | 782 | static bool need_to_create_worker(struct worker_pool *pool) |
e22bee78 | 783 | { |
63d95a91 | 784 | return need_more_worker(pool) && !may_start_working(pool); |
e22bee78 | 785 | } |
365970a1 | 786 | |
e22bee78 | 787 | /* Do we have too many workers and should some go away? */ |
63d95a91 | 788 | static bool too_many_workers(struct worker_pool *pool) |
e22bee78 | 789 | { |
34a06bd6 | 790 | bool managing = mutex_is_locked(&pool->manager_arb); |
63d95a91 TH |
791 | int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ |
792 | int nr_busy = pool->nr_workers - nr_idle; | |
e22bee78 TH |
793 | |
794 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; | |
365970a1 DH |
795 | } |
796 | ||
4d707b9f | 797 | /* |
e22bee78 TH |
798 | * Wake up functions. |
799 | */ | |
800 | ||
1037de36 LJ |
801 | /* Return the first idle worker. Safe with preemption disabled */ |
802 | static struct worker *first_idle_worker(struct worker_pool *pool) | |
7e11629d | 803 | { |
63d95a91 | 804 | if (unlikely(list_empty(&pool->idle_list))) |
7e11629d TH |
805 | return NULL; |
806 | ||
63d95a91 | 807 | return list_first_entry(&pool->idle_list, struct worker, entry); |
7e11629d TH |
808 | } |
809 | ||
810 | /** | |
811 | * wake_up_worker - wake up an idle worker | |
63d95a91 | 812 | * @pool: worker pool to wake worker from |
7e11629d | 813 | * |
63d95a91 | 814 | * Wake up the first idle worker of @pool. |
7e11629d TH |
815 | * |
816 | * CONTEXT: | |
d565ed63 | 817 | * spin_lock_irq(pool->lock). |
7e11629d | 818 | */ |
63d95a91 | 819 | static void wake_up_worker(struct worker_pool *pool) |
7e11629d | 820 | { |
1037de36 | 821 | struct worker *worker = first_idle_worker(pool); |
7e11629d TH |
822 | |
823 | if (likely(worker)) | |
824 | wake_up_process(worker->task); | |
825 | } | |
826 | ||
d302f017 | 827 | /** |
e22bee78 TH |
828 | * wq_worker_waking_up - a worker is waking up |
829 | * @task: task waking up | |
830 | * @cpu: CPU @task is waking up to | |
831 | * | |
832 | * This function is called during try_to_wake_up() when a worker is | |
833 | * being awoken. | |
834 | * | |
835 | * CONTEXT: | |
836 | * spin_lock_irq(rq->lock) | |
837 | */ | |
d84ff051 | 838 | void wq_worker_waking_up(struct task_struct *task, int cpu) |
e22bee78 TH |
839 | { |
840 | struct worker *worker = kthread_data(task); | |
841 | ||
36576000 | 842 | if (!(worker->flags & WORKER_NOT_RUNNING)) { |
ec22ca5e | 843 | WARN_ON_ONCE(worker->pool->cpu != cpu); |
e19e397a | 844 | atomic_inc(&worker->pool->nr_running); |
36576000 | 845 | } |
e22bee78 TH |
846 | } |
847 | ||
848 | /** | |
849 | * wq_worker_sleeping - a worker is going to sleep | |
850 | * @task: task going to sleep | |
851 | * @cpu: CPU in question, must be the current CPU number | |
852 | * | |
853 | * This function is called during schedule() when a busy worker is | |
854 | * going to sleep. Worker on the same cpu can be woken up by | |
855 | * returning pointer to its task. | |
856 | * | |
857 | * CONTEXT: | |
858 | * spin_lock_irq(rq->lock) | |
859 | * | |
d185af30 | 860 | * Return: |
e22bee78 TH |
861 | * Worker task on @cpu to wake up, %NULL if none. |
862 | */ | |
d84ff051 | 863 | struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu) |
e22bee78 TH |
864 | { |
865 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; | |
111c225a | 866 | struct worker_pool *pool; |
e22bee78 | 867 | |
111c225a TH |
868 | /* |
869 | * Rescuers, which may not have all the fields set up like normal | |
870 | * workers, also reach here, let's not access anything before | |
871 | * checking NOT_RUNNING. | |
872 | */ | |
2d64672e | 873 | if (worker->flags & WORKER_NOT_RUNNING) |
e22bee78 TH |
874 | return NULL; |
875 | ||
111c225a | 876 | pool = worker->pool; |
111c225a | 877 | |
e22bee78 | 878 | /* this can only happen on the local cpu */ |
92b69f50 | 879 | if (WARN_ON_ONCE(cpu != raw_smp_processor_id() || pool->cpu != cpu)) |
6183c009 | 880 | return NULL; |
e22bee78 TH |
881 | |
882 | /* | |
883 | * The counterpart of the following dec_and_test, implied mb, | |
884 | * worklist not empty test sequence is in insert_work(). | |
885 | * Please read comment there. | |
886 | * | |
628c78e7 TH |
887 | * NOT_RUNNING is clear. This means that we're bound to and |
888 | * running on the local cpu w/ rq lock held and preemption | |
889 | * disabled, which in turn means that none else could be | |
d565ed63 | 890 | * manipulating idle_list, so dereferencing idle_list without pool |
628c78e7 | 891 | * lock is safe. |
e22bee78 | 892 | */ |
e19e397a TH |
893 | if (atomic_dec_and_test(&pool->nr_running) && |
894 | !list_empty(&pool->worklist)) | |
1037de36 | 895 | to_wakeup = first_idle_worker(pool); |
e22bee78 TH |
896 | return to_wakeup ? to_wakeup->task : NULL; |
897 | } | |
898 | ||
899 | /** | |
900 | * worker_set_flags - set worker flags and adjust nr_running accordingly | |
cb444766 | 901 | * @worker: self |
d302f017 | 902 | * @flags: flags to set |
d302f017 | 903 | * |
228f1d00 | 904 | * Set @flags in @worker->flags and adjust nr_running accordingly. |
d302f017 | 905 | * |
cb444766 | 906 | * CONTEXT: |
d565ed63 | 907 | * spin_lock_irq(pool->lock) |
d302f017 | 908 | */ |
228f1d00 | 909 | static inline void worker_set_flags(struct worker *worker, unsigned int flags) |
d302f017 | 910 | { |
bd7bdd43 | 911 | struct worker_pool *pool = worker->pool; |
e22bee78 | 912 | |
cb444766 TH |
913 | WARN_ON_ONCE(worker->task != current); |
914 | ||
228f1d00 | 915 | /* If transitioning into NOT_RUNNING, adjust nr_running. */ |
e22bee78 TH |
916 | if ((flags & WORKER_NOT_RUNNING) && |
917 | !(worker->flags & WORKER_NOT_RUNNING)) { | |
228f1d00 | 918 | atomic_dec(&pool->nr_running); |
e22bee78 TH |
919 | } |
920 | ||
d302f017 TH |
921 | worker->flags |= flags; |
922 | } | |
923 | ||
924 | /** | |
e22bee78 | 925 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
cb444766 | 926 | * @worker: self |
d302f017 TH |
927 | * @flags: flags to clear |
928 | * | |
e22bee78 | 929 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
d302f017 | 930 | * |
cb444766 | 931 | * CONTEXT: |
d565ed63 | 932 | * spin_lock_irq(pool->lock) |
d302f017 TH |
933 | */ |
934 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) | |
935 | { | |
63d95a91 | 936 | struct worker_pool *pool = worker->pool; |
e22bee78 TH |
937 | unsigned int oflags = worker->flags; |
938 | ||
cb444766 TH |
939 | WARN_ON_ONCE(worker->task != current); |
940 | ||
d302f017 | 941 | worker->flags &= ~flags; |
e22bee78 | 942 | |
42c025f3 TH |
943 | /* |
944 | * If transitioning out of NOT_RUNNING, increment nr_running. Note | |
945 | * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask | |
946 | * of multiple flags, not a single flag. | |
947 | */ | |
e22bee78 TH |
948 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
949 | if (!(worker->flags & WORKER_NOT_RUNNING)) | |
e19e397a | 950 | atomic_inc(&pool->nr_running); |
d302f017 TH |
951 | } |
952 | ||
8cca0eea TH |
953 | /** |
954 | * find_worker_executing_work - find worker which is executing a work | |
c9e7cf27 | 955 | * @pool: pool of interest |
8cca0eea TH |
956 | * @work: work to find worker for |
957 | * | |
c9e7cf27 TH |
958 | * Find a worker which is executing @work on @pool by searching |
959 | * @pool->busy_hash which is keyed by the address of @work. For a worker | |
a2c1c57b TH |
960 | * to match, its current execution should match the address of @work and |
961 | * its work function. This is to avoid unwanted dependency between | |
962 | * unrelated work executions through a work item being recycled while still | |
963 | * being executed. | |
964 | * | |
965 | * This is a bit tricky. A work item may be freed once its execution | |
966 | * starts and nothing prevents the freed area from being recycled for | |
967 | * another work item. If the same work item address ends up being reused | |
968 | * before the original execution finishes, workqueue will identify the | |
969 | * recycled work item as currently executing and make it wait until the | |
970 | * current execution finishes, introducing an unwanted dependency. | |
971 | * | |
c5aa87bb TH |
972 | * This function checks the work item address and work function to avoid |
973 | * false positives. Note that this isn't complete as one may construct a | |
974 | * work function which can introduce dependency onto itself through a | |
975 | * recycled work item. Well, if somebody wants to shoot oneself in the | |
976 | * foot that badly, there's only so much we can do, and if such deadlock | |
977 | * actually occurs, it should be easy to locate the culprit work function. | |
8cca0eea TH |
978 | * |
979 | * CONTEXT: | |
d565ed63 | 980 | * spin_lock_irq(pool->lock). |
8cca0eea | 981 | * |
d185af30 YB |
982 | * Return: |
983 | * Pointer to worker which is executing @work if found, %NULL | |
8cca0eea | 984 | * otherwise. |
4d707b9f | 985 | */ |
c9e7cf27 | 986 | static struct worker *find_worker_executing_work(struct worker_pool *pool, |
8cca0eea | 987 | struct work_struct *work) |
4d707b9f | 988 | { |
42f8570f | 989 | struct worker *worker; |
42f8570f | 990 | |
b67bfe0d | 991 | hash_for_each_possible(pool->busy_hash, worker, hentry, |
a2c1c57b TH |
992 | (unsigned long)work) |
993 | if (worker->current_work == work && | |
994 | worker->current_func == work->func) | |
42f8570f SL |
995 | return worker; |
996 | ||
997 | return NULL; | |
4d707b9f ON |
998 | } |
999 | ||
bf4ede01 TH |
1000 | /** |
1001 | * move_linked_works - move linked works to a list | |
1002 | * @work: start of series of works to be scheduled | |
1003 | * @head: target list to append @work to | |
402dd89d | 1004 | * @nextp: out parameter for nested worklist walking |
bf4ede01 TH |
1005 | * |
1006 | * Schedule linked works starting from @work to @head. Work series to | |
1007 | * be scheduled starts at @work and includes any consecutive work with | |
1008 | * WORK_STRUCT_LINKED set in its predecessor. | |
1009 | * | |
1010 | * If @nextp is not NULL, it's updated to point to the next work of | |
1011 | * the last scheduled work. This allows move_linked_works() to be | |
1012 | * nested inside outer list_for_each_entry_safe(). | |
1013 | * | |
1014 | * CONTEXT: | |
d565ed63 | 1015 | * spin_lock_irq(pool->lock). |
bf4ede01 TH |
1016 | */ |
1017 | static void move_linked_works(struct work_struct *work, struct list_head *head, | |
1018 | struct work_struct **nextp) | |
1019 | { | |
1020 | struct work_struct *n; | |
1021 | ||
1022 | /* | |
1023 | * Linked worklist will always end before the end of the list, | |
1024 | * use NULL for list head. | |
1025 | */ | |
1026 | list_for_each_entry_safe_from(work, n, NULL, entry) { | |
1027 | list_move_tail(&work->entry, head); | |
1028 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) | |
1029 | break; | |
1030 | } | |
1031 | ||
1032 | /* | |
1033 | * If we're already inside safe list traversal and have moved | |
1034 | * multiple works to the scheduled queue, the next position | |
1035 | * needs to be updated. | |
1036 | */ | |
1037 | if (nextp) | |
1038 | *nextp = n; | |
1039 | } | |
1040 | ||
8864b4e5 TH |
1041 | /** |
1042 | * get_pwq - get an extra reference on the specified pool_workqueue | |
1043 | * @pwq: pool_workqueue to get | |
1044 | * | |
1045 | * Obtain an extra reference on @pwq. The caller should guarantee that | |
1046 | * @pwq has positive refcnt and be holding the matching pool->lock. | |
1047 | */ | |
1048 | static void get_pwq(struct pool_workqueue *pwq) | |
1049 | { | |
1050 | lockdep_assert_held(&pwq->pool->lock); | |
1051 | WARN_ON_ONCE(pwq->refcnt <= 0); | |
1052 | pwq->refcnt++; | |
1053 | } | |
1054 | ||
1055 | /** | |
1056 | * put_pwq - put a pool_workqueue reference | |
1057 | * @pwq: pool_workqueue to put | |
1058 | * | |
1059 | * Drop a reference of @pwq. If its refcnt reaches zero, schedule its | |
1060 | * destruction. The caller should be holding the matching pool->lock. | |
1061 | */ | |
1062 | static void put_pwq(struct pool_workqueue *pwq) | |
1063 | { | |
1064 | lockdep_assert_held(&pwq->pool->lock); | |
1065 | if (likely(--pwq->refcnt)) | |
1066 | return; | |
1067 | if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) | |
1068 | return; | |
1069 | /* | |
1070 | * @pwq can't be released under pool->lock, bounce to | |
1071 | * pwq_unbound_release_workfn(). This never recurses on the same | |
1072 | * pool->lock as this path is taken only for unbound workqueues and | |
1073 | * the release work item is scheduled on a per-cpu workqueue. To | |
1074 | * avoid lockdep warning, unbound pool->locks are given lockdep | |
1075 | * subclass of 1 in get_unbound_pool(). | |
1076 | */ | |
1077 | schedule_work(&pwq->unbound_release_work); | |
1078 | } | |
1079 | ||
dce90d47 TH |
1080 | /** |
1081 | * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock | |
1082 | * @pwq: pool_workqueue to put (can be %NULL) | |
1083 | * | |
1084 | * put_pwq() with locking. This function also allows %NULL @pwq. | |
1085 | */ | |
1086 | static void put_pwq_unlocked(struct pool_workqueue *pwq) | |
1087 | { | |
1088 | if (pwq) { | |
1089 | /* | |
1090 | * As both pwqs and pools are sched-RCU protected, the | |
1091 | * following lock operations are safe. | |
1092 | */ | |
1093 | spin_lock_irq(&pwq->pool->lock); | |
1094 | put_pwq(pwq); | |
1095 | spin_unlock_irq(&pwq->pool->lock); | |
1096 | } | |
1097 | } | |
1098 | ||
112202d9 | 1099 | static void pwq_activate_delayed_work(struct work_struct *work) |
bf4ede01 | 1100 | { |
112202d9 | 1101 | struct pool_workqueue *pwq = get_work_pwq(work); |
bf4ede01 TH |
1102 | |
1103 | trace_workqueue_activate_work(work); | |
82607adc TH |
1104 | if (list_empty(&pwq->pool->worklist)) |
1105 | pwq->pool->watchdog_ts = jiffies; | |
112202d9 | 1106 | move_linked_works(work, &pwq->pool->worklist, NULL); |
bf4ede01 | 1107 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); |
112202d9 | 1108 | pwq->nr_active++; |
bf4ede01 TH |
1109 | } |
1110 | ||
112202d9 | 1111 | static void pwq_activate_first_delayed(struct pool_workqueue *pwq) |
3aa62497 | 1112 | { |
112202d9 | 1113 | struct work_struct *work = list_first_entry(&pwq->delayed_works, |
3aa62497 LJ |
1114 | struct work_struct, entry); |
1115 | ||
112202d9 | 1116 | pwq_activate_delayed_work(work); |
3aa62497 LJ |
1117 | } |
1118 | ||
bf4ede01 | 1119 | /** |
112202d9 TH |
1120 | * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight |
1121 | * @pwq: pwq of interest | |
bf4ede01 | 1122 | * @color: color of work which left the queue |
bf4ede01 TH |
1123 | * |
1124 | * A work either has completed or is removed from pending queue, | |
112202d9 | 1125 | * decrement nr_in_flight of its pwq and handle workqueue flushing. |
bf4ede01 TH |
1126 | * |
1127 | * CONTEXT: | |
d565ed63 | 1128 | * spin_lock_irq(pool->lock). |
bf4ede01 | 1129 | */ |
112202d9 | 1130 | static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) |
bf4ede01 | 1131 | { |
8864b4e5 | 1132 | /* uncolored work items don't participate in flushing or nr_active */ |
bf4ede01 | 1133 | if (color == WORK_NO_COLOR) |
8864b4e5 | 1134 | goto out_put; |
bf4ede01 | 1135 | |
112202d9 | 1136 | pwq->nr_in_flight[color]--; |
bf4ede01 | 1137 | |
112202d9 TH |
1138 | pwq->nr_active--; |
1139 | if (!list_empty(&pwq->delayed_works)) { | |
b3f9f405 | 1140 | /* one down, submit a delayed one */ |
112202d9 TH |
1141 | if (pwq->nr_active < pwq->max_active) |
1142 | pwq_activate_first_delayed(pwq); | |
bf4ede01 TH |
1143 | } |
1144 | ||
1145 | /* is flush in progress and are we at the flushing tip? */ | |
112202d9 | 1146 | if (likely(pwq->flush_color != color)) |
8864b4e5 | 1147 | goto out_put; |
bf4ede01 TH |
1148 | |
1149 | /* are there still in-flight works? */ | |
112202d9 | 1150 | if (pwq->nr_in_flight[color]) |
8864b4e5 | 1151 | goto out_put; |
bf4ede01 | 1152 | |
112202d9 TH |
1153 | /* this pwq is done, clear flush_color */ |
1154 | pwq->flush_color = -1; | |
bf4ede01 TH |
1155 | |
1156 | /* | |
112202d9 | 1157 | * If this was the last pwq, wake up the first flusher. It |
bf4ede01 TH |
1158 | * will handle the rest. |
1159 | */ | |
112202d9 TH |
1160 | if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) |
1161 | complete(&pwq->wq->first_flusher->done); | |
8864b4e5 TH |
1162 | out_put: |
1163 | put_pwq(pwq); | |
bf4ede01 TH |
1164 | } |
1165 | ||
36e227d2 | 1166 | /** |
bbb68dfa | 1167 | * try_to_grab_pending - steal work item from worklist and disable irq |
36e227d2 TH |
1168 | * @work: work item to steal |
1169 | * @is_dwork: @work is a delayed_work | |
bbb68dfa | 1170 | * @flags: place to store irq state |
36e227d2 TH |
1171 | * |
1172 | * Try to grab PENDING bit of @work. This function can handle @work in any | |
d185af30 | 1173 | * stable state - idle, on timer or on worklist. |
36e227d2 | 1174 | * |
d185af30 | 1175 | * Return: |
36e227d2 TH |
1176 | * 1 if @work was pending and we successfully stole PENDING |
1177 | * 0 if @work was idle and we claimed PENDING | |
1178 | * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry | |
bbb68dfa TH |
1179 | * -ENOENT if someone else is canceling @work, this state may persist |
1180 | * for arbitrarily long | |
36e227d2 | 1181 | * |
d185af30 | 1182 | * Note: |
bbb68dfa | 1183 | * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting |
e0aecdd8 TH |
1184 | * interrupted while holding PENDING and @work off queue, irq must be |
1185 | * disabled on entry. This, combined with delayed_work->timer being | |
1186 | * irqsafe, ensures that we return -EAGAIN for finite short period of time. | |
bbb68dfa TH |
1187 | * |
1188 | * On successful return, >= 0, irq is disabled and the caller is | |
1189 | * responsible for releasing it using local_irq_restore(*@flags). | |
1190 | * | |
e0aecdd8 | 1191 | * This function is safe to call from any context including IRQ handler. |
bf4ede01 | 1192 | */ |
bbb68dfa TH |
1193 | static int try_to_grab_pending(struct work_struct *work, bool is_dwork, |
1194 | unsigned long *flags) | |
bf4ede01 | 1195 | { |
d565ed63 | 1196 | struct worker_pool *pool; |
112202d9 | 1197 | struct pool_workqueue *pwq; |
bf4ede01 | 1198 | |
bbb68dfa TH |
1199 | local_irq_save(*flags); |
1200 | ||
36e227d2 TH |
1201 | /* try to steal the timer if it exists */ |
1202 | if (is_dwork) { | |
1203 | struct delayed_work *dwork = to_delayed_work(work); | |
1204 | ||
e0aecdd8 TH |
1205 | /* |
1206 | * dwork->timer is irqsafe. If del_timer() fails, it's | |
1207 | * guaranteed that the timer is not queued anywhere and not | |
1208 | * running on the local CPU. | |
1209 | */ | |
36e227d2 TH |
1210 | if (likely(del_timer(&dwork->timer))) |
1211 | return 1; | |
1212 | } | |
1213 | ||
1214 | /* try to claim PENDING the normal way */ | |
bf4ede01 TH |
1215 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1216 | return 0; | |
1217 | ||
1218 | /* | |
1219 | * The queueing is in progress, or it is already queued. Try to | |
1220 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. | |
1221 | */ | |
d565ed63 TH |
1222 | pool = get_work_pool(work); |
1223 | if (!pool) | |
bbb68dfa | 1224 | goto fail; |
bf4ede01 | 1225 | |
d565ed63 | 1226 | spin_lock(&pool->lock); |
0b3dae68 | 1227 | /* |
112202d9 TH |
1228 | * work->data is guaranteed to point to pwq only while the work |
1229 | * item is queued on pwq->wq, and both updating work->data to point | |
1230 | * to pwq on queueing and to pool on dequeueing are done under | |
1231 | * pwq->pool->lock. This in turn guarantees that, if work->data | |
1232 | * points to pwq which is associated with a locked pool, the work | |
0b3dae68 LJ |
1233 | * item is currently queued on that pool. |
1234 | */ | |
112202d9 TH |
1235 | pwq = get_work_pwq(work); |
1236 | if (pwq && pwq->pool == pool) { | |
16062836 TH |
1237 | debug_work_deactivate(work); |
1238 | ||
1239 | /* | |
1240 | * A delayed work item cannot be grabbed directly because | |
1241 | * it might have linked NO_COLOR work items which, if left | |
112202d9 | 1242 | * on the delayed_list, will confuse pwq->nr_active |
16062836 TH |
1243 | * management later on and cause stall. Make sure the work |
1244 | * item is activated before grabbing. | |
1245 | */ | |
1246 | if (*work_data_bits(work) & WORK_STRUCT_DELAYED) | |
112202d9 | 1247 | pwq_activate_delayed_work(work); |
16062836 TH |
1248 | |
1249 | list_del_init(&work->entry); | |
9c34a704 | 1250 | pwq_dec_nr_in_flight(pwq, get_work_color(work)); |
16062836 | 1251 | |
112202d9 | 1252 | /* work->data points to pwq iff queued, point to pool */ |
16062836 TH |
1253 | set_work_pool_and_keep_pending(work, pool->id); |
1254 | ||
1255 | spin_unlock(&pool->lock); | |
1256 | return 1; | |
bf4ede01 | 1257 | } |
d565ed63 | 1258 | spin_unlock(&pool->lock); |
bbb68dfa TH |
1259 | fail: |
1260 | local_irq_restore(*flags); | |
1261 | if (work_is_canceling(work)) | |
1262 | return -ENOENT; | |
1263 | cpu_relax(); | |
36e227d2 | 1264 | return -EAGAIN; |
bf4ede01 TH |
1265 | } |
1266 | ||
4690c4ab | 1267 | /** |
706026c2 | 1268 | * insert_work - insert a work into a pool |
112202d9 | 1269 | * @pwq: pwq @work belongs to |
4690c4ab TH |
1270 | * @work: work to insert |
1271 | * @head: insertion point | |
1272 | * @extra_flags: extra WORK_STRUCT_* flags to set | |
1273 | * | |
112202d9 | 1274 | * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to |
706026c2 | 1275 | * work_struct flags. |
4690c4ab TH |
1276 | * |
1277 | * CONTEXT: | |
d565ed63 | 1278 | * spin_lock_irq(pool->lock). |
4690c4ab | 1279 | */ |
112202d9 TH |
1280 | static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, |
1281 | struct list_head *head, unsigned int extra_flags) | |
b89deed3 | 1282 | { |
112202d9 | 1283 | struct worker_pool *pool = pwq->pool; |
e22bee78 | 1284 | |
4690c4ab | 1285 | /* we own @work, set data and link */ |
112202d9 | 1286 | set_work_pwq(work, pwq, extra_flags); |
1a4d9b0a | 1287 | list_add_tail(&work->entry, head); |
8864b4e5 | 1288 | get_pwq(pwq); |
e22bee78 TH |
1289 | |
1290 | /* | |
c5aa87bb TH |
1291 | * Ensure either wq_worker_sleeping() sees the above |
1292 | * list_add_tail() or we see zero nr_running to avoid workers lying | |
1293 | * around lazily while there are works to be processed. | |
e22bee78 TH |
1294 | */ |
1295 | smp_mb(); | |
1296 | ||
63d95a91 TH |
1297 | if (__need_more_worker(pool)) |
1298 | wake_up_worker(pool); | |
b89deed3 ON |
1299 | } |
1300 | ||
c8efcc25 TH |
1301 | /* |
1302 | * Test whether @work is being queued from another work executing on the | |
8d03ecfe | 1303 | * same workqueue. |
c8efcc25 TH |
1304 | */ |
1305 | static bool is_chained_work(struct workqueue_struct *wq) | |
1306 | { | |
8d03ecfe TH |
1307 | struct worker *worker; |
1308 | ||
1309 | worker = current_wq_worker(); | |
1310 | /* | |
1311 | * Return %true iff I'm a worker execuing a work item on @wq. If | |
1312 | * I'm @worker, it's safe to dereference it without locking. | |
1313 | */ | |
112202d9 | 1314 | return worker && worker->current_pwq->wq == wq; |
c8efcc25 TH |
1315 | } |
1316 | ||
ef557180 MG |
1317 | /* |
1318 | * When queueing an unbound work item to a wq, prefer local CPU if allowed | |
1319 | * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to | |
1320 | * avoid perturbing sensitive tasks. | |
1321 | */ | |
1322 | static int wq_select_unbound_cpu(int cpu) | |
1323 | { | |
f303fccb | 1324 | static bool printed_dbg_warning; |
ef557180 MG |
1325 | int new_cpu; |
1326 | ||
f303fccb TH |
1327 | if (likely(!wq_debug_force_rr_cpu)) { |
1328 | if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) | |
1329 | return cpu; | |
1330 | } else if (!printed_dbg_warning) { | |
1331 | pr_warn("workqueue: round-robin CPU selection forced, expect performance impact\n"); | |
1332 | printed_dbg_warning = true; | |
1333 | } | |
1334 | ||
ef557180 MG |
1335 | if (cpumask_empty(wq_unbound_cpumask)) |
1336 | return cpu; | |
1337 | ||
1338 | new_cpu = __this_cpu_read(wq_rr_cpu_last); | |
1339 | new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask); | |
1340 | if (unlikely(new_cpu >= nr_cpu_ids)) { | |
1341 | new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask); | |
1342 | if (unlikely(new_cpu >= nr_cpu_ids)) | |
1343 | return cpu; | |
1344 | } | |
1345 | __this_cpu_write(wq_rr_cpu_last, new_cpu); | |
1346 | ||
1347 | return new_cpu; | |
1348 | } | |
1349 | ||
d84ff051 | 1350 | static void __queue_work(int cpu, struct workqueue_struct *wq, |
1da177e4 LT |
1351 | struct work_struct *work) |
1352 | { | |
112202d9 | 1353 | struct pool_workqueue *pwq; |
c9178087 | 1354 | struct worker_pool *last_pool; |
1e19ffc6 | 1355 | struct list_head *worklist; |
8a2e8e5d | 1356 | unsigned int work_flags; |
b75cac93 | 1357 | unsigned int req_cpu = cpu; |
8930caba TH |
1358 | |
1359 | /* | |
1360 | * While a work item is PENDING && off queue, a task trying to | |
1361 | * steal the PENDING will busy-loop waiting for it to either get | |
1362 | * queued or lose PENDING. Grabbing PENDING and queueing should | |
1363 | * happen with IRQ disabled. | |
1364 | */ | |
1365 | WARN_ON_ONCE(!irqs_disabled()); | |
1da177e4 | 1366 | |
dc186ad7 | 1367 | debug_work_activate(work); |
1e19ffc6 | 1368 | |
9ef28a73 | 1369 | /* if draining, only works from the same workqueue are allowed */ |
618b01eb | 1370 | if (unlikely(wq->flags & __WQ_DRAINING) && |
c8efcc25 | 1371 | WARN_ON_ONCE(!is_chained_work(wq))) |
e41e704b | 1372 | return; |
9e8cd2f5 | 1373 | retry: |
df2d5ae4 | 1374 | if (req_cpu == WORK_CPU_UNBOUND) |
ef557180 | 1375 | cpu = wq_select_unbound_cpu(raw_smp_processor_id()); |
df2d5ae4 | 1376 | |
c9178087 | 1377 | /* pwq which will be used unless @work is executing elsewhere */ |
df2d5ae4 | 1378 | if (!(wq->flags & WQ_UNBOUND)) |
7fb98ea7 | 1379 | pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); |
df2d5ae4 TH |
1380 | else |
1381 | pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); | |
dbf2576e | 1382 | |
c9178087 TH |
1383 | /* |
1384 | * If @work was previously on a different pool, it might still be | |
1385 | * running there, in which case the work needs to be queued on that | |
1386 | * pool to guarantee non-reentrancy. | |
1387 | */ | |
1388 | last_pool = get_work_pool(work); | |
1389 | if (last_pool && last_pool != pwq->pool) { | |
1390 | struct worker *worker; | |
18aa9eff | 1391 | |
c9178087 | 1392 | spin_lock(&last_pool->lock); |
18aa9eff | 1393 | |
c9178087 | 1394 | worker = find_worker_executing_work(last_pool, work); |
18aa9eff | 1395 | |
c9178087 TH |
1396 | if (worker && worker->current_pwq->wq == wq) { |
1397 | pwq = worker->current_pwq; | |
8930caba | 1398 | } else { |
c9178087 TH |
1399 | /* meh... not running there, queue here */ |
1400 | spin_unlock(&last_pool->lock); | |
112202d9 | 1401 | spin_lock(&pwq->pool->lock); |
8930caba | 1402 | } |
f3421797 | 1403 | } else { |
112202d9 | 1404 | spin_lock(&pwq->pool->lock); |
502ca9d8 TH |
1405 | } |
1406 | ||
9e8cd2f5 TH |
1407 | /* |
1408 | * pwq is determined and locked. For unbound pools, we could have | |
1409 | * raced with pwq release and it could already be dead. If its | |
1410 | * refcnt is zero, repeat pwq selection. Note that pwqs never die | |
df2d5ae4 TH |
1411 | * without another pwq replacing it in the numa_pwq_tbl or while |
1412 | * work items are executing on it, so the retrying is guaranteed to | |
9e8cd2f5 TH |
1413 | * make forward-progress. |
1414 | */ | |
1415 | if (unlikely(!pwq->refcnt)) { | |
1416 | if (wq->flags & WQ_UNBOUND) { | |
1417 | spin_unlock(&pwq->pool->lock); | |
1418 | cpu_relax(); | |
1419 | goto retry; | |
1420 | } | |
1421 | /* oops */ | |
1422 | WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", | |
1423 | wq->name, cpu); | |
1424 | } | |
1425 | ||
112202d9 TH |
1426 | /* pwq determined, queue */ |
1427 | trace_workqueue_queue_work(req_cpu, pwq, work); | |
502ca9d8 | 1428 | |
f5b2552b | 1429 | if (WARN_ON(!list_empty(&work->entry))) { |
112202d9 | 1430 | spin_unlock(&pwq->pool->lock); |
f5b2552b DC |
1431 | return; |
1432 | } | |
1e19ffc6 | 1433 | |
112202d9 TH |
1434 | pwq->nr_in_flight[pwq->work_color]++; |
1435 | work_flags = work_color_to_flags(pwq->work_color); | |
1e19ffc6 | 1436 | |
112202d9 | 1437 | if (likely(pwq->nr_active < pwq->max_active)) { |
cdadf009 | 1438 | trace_workqueue_activate_work(work); |
112202d9 TH |
1439 | pwq->nr_active++; |
1440 | worklist = &pwq->pool->worklist; | |
82607adc TH |
1441 | if (list_empty(worklist)) |
1442 | pwq->pool->watchdog_ts = jiffies; | |
8a2e8e5d TH |
1443 | } else { |
1444 | work_flags |= WORK_STRUCT_DELAYED; | |
112202d9 | 1445 | worklist = &pwq->delayed_works; |
8a2e8e5d | 1446 | } |
1e19ffc6 | 1447 | |
112202d9 | 1448 | insert_work(pwq, work, worklist, work_flags); |
1e19ffc6 | 1449 | |
112202d9 | 1450 | spin_unlock(&pwq->pool->lock); |
1da177e4 LT |
1451 | } |
1452 | ||
0fcb78c2 | 1453 | /** |
c1a220e7 ZR |
1454 | * queue_work_on - queue work on specific cpu |
1455 | * @cpu: CPU number to execute work on | |
0fcb78c2 REB |
1456 | * @wq: workqueue to use |
1457 | * @work: work to queue | |
1458 | * | |
c1a220e7 ZR |
1459 | * We queue the work to a specific CPU, the caller must ensure it |
1460 | * can't go away. | |
d185af30 YB |
1461 | * |
1462 | * Return: %false if @work was already on a queue, %true otherwise. | |
1da177e4 | 1463 | */ |
d4283e93 TH |
1464 | bool queue_work_on(int cpu, struct workqueue_struct *wq, |
1465 | struct work_struct *work) | |
1da177e4 | 1466 | { |
d4283e93 | 1467 | bool ret = false; |
8930caba | 1468 | unsigned long flags; |
ef1ca236 | 1469 | |
8930caba | 1470 | local_irq_save(flags); |
c1a220e7 | 1471 | |
22df02bb | 1472 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
4690c4ab | 1473 | __queue_work(cpu, wq, work); |
d4283e93 | 1474 | ret = true; |
c1a220e7 | 1475 | } |
ef1ca236 | 1476 | |
8930caba | 1477 | local_irq_restore(flags); |
1da177e4 LT |
1478 | return ret; |
1479 | } | |
ad7b1f84 | 1480 | EXPORT_SYMBOL(queue_work_on); |
1da177e4 | 1481 | |
d8e794df | 1482 | void delayed_work_timer_fn(unsigned long __data) |
1da177e4 | 1483 | { |
52bad64d | 1484 | struct delayed_work *dwork = (struct delayed_work *)__data; |
1da177e4 | 1485 | |
e0aecdd8 | 1486 | /* should have been called from irqsafe timer with irq already off */ |
60c057bc | 1487 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); |
1da177e4 | 1488 | } |
1438ade5 | 1489 | EXPORT_SYMBOL(delayed_work_timer_fn); |
1da177e4 | 1490 | |
7beb2edf TH |
1491 | static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, |
1492 | struct delayed_work *dwork, unsigned long delay) | |
1da177e4 | 1493 | { |
7beb2edf TH |
1494 | struct timer_list *timer = &dwork->timer; |
1495 | struct work_struct *work = &dwork->work; | |
7beb2edf TH |
1496 | |
1497 | WARN_ON_ONCE(timer->function != delayed_work_timer_fn || | |
1498 | timer->data != (unsigned long)dwork); | |
fc4b514f TH |
1499 | WARN_ON_ONCE(timer_pending(timer)); |
1500 | WARN_ON_ONCE(!list_empty(&work->entry)); | |
7beb2edf | 1501 | |
8852aac2 TH |
1502 | /* |
1503 | * If @delay is 0, queue @dwork->work immediately. This is for | |
1504 | * both optimization and correctness. The earliest @timer can | |
1505 | * expire is on the closest next tick and delayed_work users depend | |
1506 | * on that there's no such delay when @delay is 0. | |
1507 | */ | |
1508 | if (!delay) { | |
1509 | __queue_work(cpu, wq, &dwork->work); | |
1510 | return; | |
1511 | } | |
1512 | ||
7beb2edf | 1513 | timer_stats_timer_set_start_info(&dwork->timer); |
1da177e4 | 1514 | |
60c057bc | 1515 | dwork->wq = wq; |
1265057f | 1516 | dwork->cpu = cpu; |
7beb2edf TH |
1517 | timer->expires = jiffies + delay; |
1518 | ||
041bd12e TH |
1519 | if (unlikely(cpu != WORK_CPU_UNBOUND)) |
1520 | add_timer_on(timer, cpu); | |
1521 | else | |
1522 | add_timer(timer); | |
1da177e4 LT |
1523 | } |
1524 | ||
0fcb78c2 REB |
1525 | /** |
1526 | * queue_delayed_work_on - queue work on specific CPU after delay | |
1527 | * @cpu: CPU number to execute work on | |
1528 | * @wq: workqueue to use | |
af9997e4 | 1529 | * @dwork: work to queue |
0fcb78c2 REB |
1530 | * @delay: number of jiffies to wait before queueing |
1531 | * | |
d185af30 | 1532 | * Return: %false if @work was already on a queue, %true otherwise. If |
715f1300 TH |
1533 | * @delay is zero and @dwork is idle, it will be scheduled for immediate |
1534 | * execution. | |
0fcb78c2 | 1535 | */ |
d4283e93 TH |
1536 | bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1537 | struct delayed_work *dwork, unsigned long delay) | |
7a6bc1cd | 1538 | { |
52bad64d | 1539 | struct work_struct *work = &dwork->work; |
d4283e93 | 1540 | bool ret = false; |
8930caba | 1541 | unsigned long flags; |
7a6bc1cd | 1542 | |
8930caba TH |
1543 | /* read the comment in __queue_work() */ |
1544 | local_irq_save(flags); | |
7a6bc1cd | 1545 | |
22df02bb | 1546 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
7beb2edf | 1547 | __queue_delayed_work(cpu, wq, dwork, delay); |
d4283e93 | 1548 | ret = true; |
7a6bc1cd | 1549 | } |
8a3e77cc | 1550 | |
8930caba | 1551 | local_irq_restore(flags); |
7a6bc1cd VP |
1552 | return ret; |
1553 | } | |
ad7b1f84 | 1554 | EXPORT_SYMBOL(queue_delayed_work_on); |
c7fc77f7 | 1555 | |
8376fe22 TH |
1556 | /** |
1557 | * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU | |
1558 | * @cpu: CPU number to execute work on | |
1559 | * @wq: workqueue to use | |
1560 | * @dwork: work to queue | |
1561 | * @delay: number of jiffies to wait before queueing | |
1562 | * | |
1563 | * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, | |
1564 | * modify @dwork's timer so that it expires after @delay. If @delay is | |
1565 | * zero, @work is guaranteed to be scheduled immediately regardless of its | |
1566 | * current state. | |
1567 | * | |
d185af30 | 1568 | * Return: %false if @dwork was idle and queued, %true if @dwork was |
8376fe22 TH |
1569 | * pending and its timer was modified. |
1570 | * | |
e0aecdd8 | 1571 | * This function is safe to call from any context including IRQ handler. |
8376fe22 TH |
1572 | * See try_to_grab_pending() for details. |
1573 | */ | |
1574 | bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, | |
1575 | struct delayed_work *dwork, unsigned long delay) | |
1576 | { | |
1577 | unsigned long flags; | |
1578 | int ret; | |
c7fc77f7 | 1579 | |
8376fe22 TH |
1580 | do { |
1581 | ret = try_to_grab_pending(&dwork->work, true, &flags); | |
1582 | } while (unlikely(ret == -EAGAIN)); | |
63bc0362 | 1583 | |
8376fe22 TH |
1584 | if (likely(ret >= 0)) { |
1585 | __queue_delayed_work(cpu, wq, dwork, delay); | |
1586 | local_irq_restore(flags); | |
7a6bc1cd | 1587 | } |
8376fe22 TH |
1588 | |
1589 | /* -ENOENT from try_to_grab_pending() becomes %true */ | |
7a6bc1cd VP |
1590 | return ret; |
1591 | } | |
8376fe22 TH |
1592 | EXPORT_SYMBOL_GPL(mod_delayed_work_on); |
1593 | ||
c8e55f36 TH |
1594 | /** |
1595 | * worker_enter_idle - enter idle state | |
1596 | * @worker: worker which is entering idle state | |
1597 | * | |
1598 | * @worker is entering idle state. Update stats and idle timer if | |
1599 | * necessary. | |
1600 | * | |
1601 | * LOCKING: | |
d565ed63 | 1602 | * spin_lock_irq(pool->lock). |
c8e55f36 TH |
1603 | */ |
1604 | static void worker_enter_idle(struct worker *worker) | |
1da177e4 | 1605 | { |
bd7bdd43 | 1606 | struct worker_pool *pool = worker->pool; |
c8e55f36 | 1607 | |
6183c009 TH |
1608 | if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || |
1609 | WARN_ON_ONCE(!list_empty(&worker->entry) && | |
1610 | (worker->hentry.next || worker->hentry.pprev))) | |
1611 | return; | |
c8e55f36 | 1612 | |
051e1850 | 1613 | /* can't use worker_set_flags(), also called from create_worker() */ |
cb444766 | 1614 | worker->flags |= WORKER_IDLE; |
bd7bdd43 | 1615 | pool->nr_idle++; |
e22bee78 | 1616 | worker->last_active = jiffies; |
c8e55f36 TH |
1617 | |
1618 | /* idle_list is LIFO */ | |
bd7bdd43 | 1619 | list_add(&worker->entry, &pool->idle_list); |
db7bccf4 | 1620 | |
628c78e7 TH |
1621 | if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) |
1622 | mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); | |
cb444766 | 1623 | |
544ecf31 | 1624 | /* |
706026c2 | 1625 | * Sanity check nr_running. Because wq_unbind_fn() releases |
d565ed63 | 1626 | * pool->lock between setting %WORKER_UNBOUND and zapping |
628c78e7 TH |
1627 | * nr_running, the warning may trigger spuriously. Check iff |
1628 | * unbind is not in progress. | |
544ecf31 | 1629 | */ |
24647570 | 1630 | WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && |
bd7bdd43 | 1631 | pool->nr_workers == pool->nr_idle && |
e19e397a | 1632 | atomic_read(&pool->nr_running)); |
c8e55f36 TH |
1633 | } |
1634 | ||
1635 | /** | |
1636 | * worker_leave_idle - leave idle state | |
1637 | * @worker: worker which is leaving idle state | |
1638 | * | |
1639 | * @worker is leaving idle state. Update stats. | |
1640 | * | |
1641 | * LOCKING: | |
d565ed63 | 1642 | * spin_lock_irq(pool->lock). |
c8e55f36 TH |
1643 | */ |
1644 | static void worker_leave_idle(struct worker *worker) | |
1645 | { | |
bd7bdd43 | 1646 | struct worker_pool *pool = worker->pool; |
c8e55f36 | 1647 | |
6183c009 TH |
1648 | if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) |
1649 | return; | |
d302f017 | 1650 | worker_clr_flags(worker, WORKER_IDLE); |
bd7bdd43 | 1651 | pool->nr_idle--; |
c8e55f36 TH |
1652 | list_del_init(&worker->entry); |
1653 | } | |
1654 | ||
f7537df5 | 1655 | static struct worker *alloc_worker(int node) |
c34056a3 TH |
1656 | { |
1657 | struct worker *worker; | |
1658 | ||
f7537df5 | 1659 | worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); |
c8e55f36 TH |
1660 | if (worker) { |
1661 | INIT_LIST_HEAD(&worker->entry); | |
affee4b2 | 1662 | INIT_LIST_HEAD(&worker->scheduled); |
da028469 | 1663 | INIT_LIST_HEAD(&worker->node); |
e22bee78 TH |
1664 | /* on creation a worker is in !idle && prep state */ |
1665 | worker->flags = WORKER_PREP; | |
c8e55f36 | 1666 | } |
c34056a3 TH |
1667 | return worker; |
1668 | } | |
1669 | ||
4736cbf7 LJ |
1670 | /** |
1671 | * worker_attach_to_pool() - attach a worker to a pool | |
1672 | * @worker: worker to be attached | |
1673 | * @pool: the target pool | |
1674 | * | |
1675 | * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and | |
1676 | * cpu-binding of @worker are kept coordinated with the pool across | |
1677 | * cpu-[un]hotplugs. | |
1678 | */ | |
1679 | static void worker_attach_to_pool(struct worker *worker, | |
1680 | struct worker_pool *pool) | |
1681 | { | |
1682 | mutex_lock(&pool->attach_mutex); | |
1683 | ||
1684 | /* | |
1685 | * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any | |
1686 | * online CPUs. It'll be re-applied when any of the CPUs come up. | |
1687 | */ | |
1688 | set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); | |
1689 | ||
1690 | /* | |
1691 | * The pool->attach_mutex ensures %POOL_DISASSOCIATED remains | |
1692 | * stable across this function. See the comments above the | |
1693 | * flag definition for details. | |
1694 | */ | |
1695 | if (pool->flags & POOL_DISASSOCIATED) | |
1696 | worker->flags |= WORKER_UNBOUND; | |
1697 | ||
1698 | list_add_tail(&worker->node, &pool->workers); | |
1699 | ||
1700 | mutex_unlock(&pool->attach_mutex); | |
1701 | } | |
1702 | ||
60f5a4bc LJ |
1703 | /** |
1704 | * worker_detach_from_pool() - detach a worker from its pool | |
1705 | * @worker: worker which is attached to its pool | |
1706 | * @pool: the pool @worker is attached to | |
1707 | * | |
4736cbf7 LJ |
1708 | * Undo the attaching which had been done in worker_attach_to_pool(). The |
1709 | * caller worker shouldn't access to the pool after detached except it has | |
1710 | * other reference to the pool. | |
60f5a4bc LJ |
1711 | */ |
1712 | static void worker_detach_from_pool(struct worker *worker, | |
1713 | struct worker_pool *pool) | |
1714 | { | |
1715 | struct completion *detach_completion = NULL; | |
1716 | ||
92f9c5c4 | 1717 | mutex_lock(&pool->attach_mutex); |
da028469 LJ |
1718 | list_del(&worker->node); |
1719 | if (list_empty(&pool->workers)) | |
60f5a4bc | 1720 | detach_completion = pool->detach_completion; |
92f9c5c4 | 1721 | mutex_unlock(&pool->attach_mutex); |
60f5a4bc | 1722 | |
b62c0751 LJ |
1723 | /* clear leftover flags without pool->lock after it is detached */ |
1724 | worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); | |
1725 | ||
60f5a4bc LJ |
1726 | if (detach_completion) |
1727 | complete(detach_completion); | |
1728 | } | |
1729 | ||
c34056a3 TH |
1730 | /** |
1731 | * create_worker - create a new workqueue worker | |
63d95a91 | 1732 | * @pool: pool the new worker will belong to |
c34056a3 | 1733 | * |
051e1850 | 1734 | * Create and start a new worker which is attached to @pool. |
c34056a3 TH |
1735 | * |
1736 | * CONTEXT: | |
1737 | * Might sleep. Does GFP_KERNEL allocations. | |
1738 | * | |
d185af30 | 1739 | * Return: |
c34056a3 TH |
1740 | * Pointer to the newly created worker. |
1741 | */ | |
bc2ae0f5 | 1742 | static struct worker *create_worker(struct worker_pool *pool) |
c34056a3 | 1743 | { |
c34056a3 | 1744 | struct worker *worker = NULL; |
f3421797 | 1745 | int id = -1; |
e3c916a4 | 1746 | char id_buf[16]; |
c34056a3 | 1747 | |
7cda9aae LJ |
1748 | /* ID is needed to determine kthread name */ |
1749 | id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL); | |
822d8405 TH |
1750 | if (id < 0) |
1751 | goto fail; | |
c34056a3 | 1752 | |
f7537df5 | 1753 | worker = alloc_worker(pool->node); |
c34056a3 TH |
1754 | if (!worker) |
1755 | goto fail; | |
1756 | ||
bd7bdd43 | 1757 | worker->pool = pool; |
c34056a3 TH |
1758 | worker->id = id; |
1759 | ||
29c91e99 | 1760 | if (pool->cpu >= 0) |
e3c916a4 TH |
1761 | snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, |
1762 | pool->attrs->nice < 0 ? "H" : ""); | |
f3421797 | 1763 | else |
e3c916a4 TH |
1764 | snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); |
1765 | ||
f3f90ad4 | 1766 | worker->task = kthread_create_on_node(worker_thread, worker, pool->node, |
e3c916a4 | 1767 | "kworker/%s", id_buf); |
c34056a3 TH |
1768 | if (IS_ERR(worker->task)) |
1769 | goto fail; | |
1770 | ||
91151228 | 1771 | set_user_nice(worker->task, pool->attrs->nice); |
25834c73 | 1772 | kthread_bind_mask(worker->task, pool->attrs->cpumask); |
91151228 | 1773 | |
da028469 | 1774 | /* successful, attach the worker to the pool */ |
4736cbf7 | 1775 | worker_attach_to_pool(worker, pool); |
822d8405 | 1776 | |
051e1850 LJ |
1777 | /* start the newly created worker */ |
1778 | spin_lock_irq(&pool->lock); | |
1779 | worker->pool->nr_workers++; | |
1780 | worker_enter_idle(worker); | |
1781 | wake_up_process(worker->task); | |
1782 | spin_unlock_irq(&pool->lock); | |
1783 | ||
c34056a3 | 1784 | return worker; |
822d8405 | 1785 | |
c34056a3 | 1786 | fail: |
9625ab17 | 1787 | if (id >= 0) |
7cda9aae | 1788 | ida_simple_remove(&pool->worker_ida, id); |
c34056a3 TH |
1789 | kfree(worker); |
1790 | return NULL; | |
1791 | } | |
1792 | ||
c34056a3 TH |
1793 | /** |
1794 | * destroy_worker - destroy a workqueue worker | |
1795 | * @worker: worker to be destroyed | |
1796 | * | |
73eb7fe7 LJ |
1797 | * Destroy @worker and adjust @pool stats accordingly. The worker should |
1798 | * be idle. | |
c8e55f36 TH |
1799 | * |
1800 | * CONTEXT: | |
60f5a4bc | 1801 | * spin_lock_irq(pool->lock). |
c34056a3 TH |
1802 | */ |
1803 | static void destroy_worker(struct worker *worker) | |
1804 | { | |
bd7bdd43 | 1805 | struct worker_pool *pool = worker->pool; |
c34056a3 | 1806 | |
cd549687 TH |
1807 | lockdep_assert_held(&pool->lock); |
1808 | ||
c34056a3 | 1809 | /* sanity check frenzy */ |
6183c009 | 1810 | if (WARN_ON(worker->current_work) || |
73eb7fe7 LJ |
1811 | WARN_ON(!list_empty(&worker->scheduled)) || |
1812 | WARN_ON(!(worker->flags & WORKER_IDLE))) | |
6183c009 | 1813 | return; |
c34056a3 | 1814 | |
73eb7fe7 LJ |
1815 | pool->nr_workers--; |
1816 | pool->nr_idle--; | |
5bdfff96 | 1817 | |
c8e55f36 | 1818 | list_del_init(&worker->entry); |
cb444766 | 1819 | worker->flags |= WORKER_DIE; |
60f5a4bc | 1820 | wake_up_process(worker->task); |
c34056a3 TH |
1821 | } |
1822 | ||
63d95a91 | 1823 | static void idle_worker_timeout(unsigned long __pool) |
e22bee78 | 1824 | { |
63d95a91 | 1825 | struct worker_pool *pool = (void *)__pool; |
e22bee78 | 1826 | |
d565ed63 | 1827 | spin_lock_irq(&pool->lock); |
e22bee78 | 1828 | |
3347fc9f | 1829 | while (too_many_workers(pool)) { |
e22bee78 TH |
1830 | struct worker *worker; |
1831 | unsigned long expires; | |
1832 | ||
1833 | /* idle_list is kept in LIFO order, check the last one */ | |
63d95a91 | 1834 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
e22bee78 TH |
1835 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1836 | ||
3347fc9f | 1837 | if (time_before(jiffies, expires)) { |
63d95a91 | 1838 | mod_timer(&pool->idle_timer, expires); |
3347fc9f | 1839 | break; |
d5abe669 | 1840 | } |
3347fc9f LJ |
1841 | |
1842 | destroy_worker(worker); | |
e22bee78 TH |
1843 | } |
1844 | ||
d565ed63 | 1845 | spin_unlock_irq(&pool->lock); |
e22bee78 | 1846 | } |
d5abe669 | 1847 | |
493a1724 | 1848 | static void send_mayday(struct work_struct *work) |
e22bee78 | 1849 | { |
112202d9 TH |
1850 | struct pool_workqueue *pwq = get_work_pwq(work); |
1851 | struct workqueue_struct *wq = pwq->wq; | |
493a1724 | 1852 | |
2e109a28 | 1853 | lockdep_assert_held(&wq_mayday_lock); |
e22bee78 | 1854 | |
493008a8 | 1855 | if (!wq->rescuer) |
493a1724 | 1856 | return; |
e22bee78 TH |
1857 | |
1858 | /* mayday mayday mayday */ | |
493a1724 | 1859 | if (list_empty(&pwq->mayday_node)) { |
77668c8b LJ |
1860 | /* |
1861 | * If @pwq is for an unbound wq, its base ref may be put at | |
1862 | * any time due to an attribute change. Pin @pwq until the | |
1863 | * rescuer is done with it. | |
1864 | */ | |
1865 | get_pwq(pwq); | |
493a1724 | 1866 | list_add_tail(&pwq->mayday_node, &wq->maydays); |
e22bee78 | 1867 | wake_up_process(wq->rescuer->task); |
493a1724 | 1868 | } |
e22bee78 TH |
1869 | } |
1870 | ||
706026c2 | 1871 | static void pool_mayday_timeout(unsigned long __pool) |
e22bee78 | 1872 | { |
63d95a91 | 1873 | struct worker_pool *pool = (void *)__pool; |
e22bee78 TH |
1874 | struct work_struct *work; |
1875 | ||
b2d82909 TH |
1876 | spin_lock_irq(&pool->lock); |
1877 | spin_lock(&wq_mayday_lock); /* for wq->maydays */ | |
e22bee78 | 1878 | |
63d95a91 | 1879 | if (need_to_create_worker(pool)) { |
e22bee78 TH |
1880 | /* |
1881 | * We've been trying to create a new worker but | |
1882 | * haven't been successful. We might be hitting an | |
1883 | * allocation deadlock. Send distress signals to | |
1884 | * rescuers. | |
1885 | */ | |
63d95a91 | 1886 | list_for_each_entry(work, &pool->worklist, entry) |
e22bee78 | 1887 | send_mayday(work); |
1da177e4 | 1888 | } |
e22bee78 | 1889 | |
b2d82909 TH |
1890 | spin_unlock(&wq_mayday_lock); |
1891 | spin_unlock_irq(&pool->lock); | |
e22bee78 | 1892 | |
63d95a91 | 1893 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); |
1da177e4 LT |
1894 | } |
1895 | ||
e22bee78 TH |
1896 | /** |
1897 | * maybe_create_worker - create a new worker if necessary | |
63d95a91 | 1898 | * @pool: pool to create a new worker for |
e22bee78 | 1899 | * |
63d95a91 | 1900 | * Create a new worker for @pool if necessary. @pool is guaranteed to |
e22bee78 TH |
1901 | * have at least one idle worker on return from this function. If |
1902 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is | |
63d95a91 | 1903 | * sent to all rescuers with works scheduled on @pool to resolve |
e22bee78 TH |
1904 | * possible allocation deadlock. |
1905 | * | |
c5aa87bb TH |
1906 | * On return, need_to_create_worker() is guaranteed to be %false and |
1907 | * may_start_working() %true. | |
e22bee78 TH |
1908 | * |
1909 | * LOCKING: | |
d565ed63 | 1910 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
e22bee78 TH |
1911 | * multiple times. Does GFP_KERNEL allocations. Called only from |
1912 | * manager. | |
e22bee78 | 1913 | */ |
29187a9e | 1914 | static void maybe_create_worker(struct worker_pool *pool) |
d565ed63 TH |
1915 | __releases(&pool->lock) |
1916 | __acquires(&pool->lock) | |
1da177e4 | 1917 | { |
e22bee78 | 1918 | restart: |
d565ed63 | 1919 | spin_unlock_irq(&pool->lock); |
9f9c2364 | 1920 | |
e22bee78 | 1921 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
63d95a91 | 1922 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
e22bee78 TH |
1923 | |
1924 | while (true) { | |
051e1850 | 1925 | if (create_worker(pool) || !need_to_create_worker(pool)) |
e22bee78 | 1926 | break; |
1da177e4 | 1927 | |
e212f361 | 1928 | schedule_timeout_interruptible(CREATE_COOLDOWN); |
9f9c2364 | 1929 | |
63d95a91 | 1930 | if (!need_to_create_worker(pool)) |
e22bee78 TH |
1931 | break; |
1932 | } | |
1933 | ||
63d95a91 | 1934 | del_timer_sync(&pool->mayday_timer); |
d565ed63 | 1935 | spin_lock_irq(&pool->lock); |
051e1850 LJ |
1936 | /* |
1937 | * This is necessary even after a new worker was just successfully | |
1938 | * created as @pool->lock was dropped and the new worker might have | |
1939 | * already become busy. | |
1940 | */ | |
63d95a91 | 1941 | if (need_to_create_worker(pool)) |
e22bee78 | 1942 | goto restart; |
e22bee78 TH |
1943 | } |
1944 | ||
73f53c4a | 1945 | /** |
e22bee78 TH |
1946 | * manage_workers - manage worker pool |
1947 | * @worker: self | |
73f53c4a | 1948 | * |
706026c2 | 1949 | * Assume the manager role and manage the worker pool @worker belongs |
e22bee78 | 1950 | * to. At any given time, there can be only zero or one manager per |
706026c2 | 1951 | * pool. The exclusion is handled automatically by this function. |
e22bee78 TH |
1952 | * |
1953 | * The caller can safely start processing works on false return. On | |
1954 | * true return, it's guaranteed that need_to_create_worker() is false | |
1955 | * and may_start_working() is true. | |
73f53c4a TH |
1956 | * |
1957 | * CONTEXT: | |
d565ed63 | 1958 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
e22bee78 TH |
1959 | * multiple times. Does GFP_KERNEL allocations. |
1960 | * | |
d185af30 | 1961 | * Return: |
29187a9e TH |
1962 | * %false if the pool doesn't need management and the caller can safely |
1963 | * start processing works, %true if management function was performed and | |
1964 | * the conditions that the caller verified before calling the function may | |
1965 | * no longer be true. | |
73f53c4a | 1966 | */ |
e22bee78 | 1967 | static bool manage_workers(struct worker *worker) |
73f53c4a | 1968 | { |
63d95a91 | 1969 | struct worker_pool *pool = worker->pool; |
73f53c4a | 1970 | |
bc3a1afc | 1971 | /* |
bc3a1afc TH |
1972 | * Anyone who successfully grabs manager_arb wins the arbitration |
1973 | * and becomes the manager. mutex_trylock() on pool->manager_arb | |
1974 | * failure while holding pool->lock reliably indicates that someone | |
1975 | * else is managing the pool and the worker which failed trylock | |
1976 | * can proceed to executing work items. This means that anyone | |
1977 | * grabbing manager_arb is responsible for actually performing | |
1978 | * manager duties. If manager_arb is grabbed and released without | |
1979 | * actual management, the pool may stall indefinitely. | |
bc3a1afc | 1980 | */ |
34a06bd6 | 1981 | if (!mutex_trylock(&pool->manager_arb)) |
29187a9e | 1982 | return false; |
2607d7a6 | 1983 | pool->manager = worker; |
1e19ffc6 | 1984 | |
29187a9e | 1985 | maybe_create_worker(pool); |
e22bee78 | 1986 | |
2607d7a6 | 1987 | pool->manager = NULL; |
34a06bd6 | 1988 | mutex_unlock(&pool->manager_arb); |
29187a9e | 1989 | return true; |
73f53c4a TH |
1990 | } |
1991 | ||
a62428c0 TH |
1992 | /** |
1993 | * process_one_work - process single work | |
c34056a3 | 1994 | * @worker: self |
a62428c0 TH |
1995 | * @work: work to process |
1996 | * | |
1997 | * Process @work. This function contains all the logics necessary to | |
1998 | * process a single work including synchronization against and | |
1999 | * interaction with other workers on the same cpu, queueing and | |
2000 | * flushing. As long as context requirement is met, any worker can | |
2001 | * call this function to process a work. | |
2002 | * | |
2003 | * CONTEXT: | |
d565ed63 | 2004 | * spin_lock_irq(pool->lock) which is released and regrabbed. |
a62428c0 | 2005 | */ |
c34056a3 | 2006 | static void process_one_work(struct worker *worker, struct work_struct *work) |
d565ed63 TH |
2007 | __releases(&pool->lock) |
2008 | __acquires(&pool->lock) | |
a62428c0 | 2009 | { |
112202d9 | 2010 | struct pool_workqueue *pwq = get_work_pwq(work); |
bd7bdd43 | 2011 | struct worker_pool *pool = worker->pool; |
112202d9 | 2012 | bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; |
73f53c4a | 2013 | int work_color; |
7e11629d | 2014 | struct worker *collision; |
a62428c0 TH |
2015 | #ifdef CONFIG_LOCKDEP |
2016 | /* | |
2017 | * It is permissible to free the struct work_struct from | |
2018 | * inside the function that is called from it, this we need to | |
2019 | * take into account for lockdep too. To avoid bogus "held | |
2020 | * lock freed" warnings as well as problems when looking into | |
2021 | * work->lockdep_map, make a copy and use that here. | |
2022 | */ | |
4d82a1de PZ |
2023 | struct lockdep_map lockdep_map; |
2024 | ||
2025 | lockdep_copy_map(&lockdep_map, &work->lockdep_map); | |
a62428c0 | 2026 | #endif |
807407c0 | 2027 | /* ensure we're on the correct CPU */ |
85327af6 | 2028 | WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && |
ec22ca5e | 2029 | raw_smp_processor_id() != pool->cpu); |
25511a47 | 2030 | |
7e11629d TH |
2031 | /* |
2032 | * A single work shouldn't be executed concurrently by | |
2033 | * multiple workers on a single cpu. Check whether anyone is | |
2034 | * already processing the work. If so, defer the work to the | |
2035 | * currently executing one. | |
2036 | */ | |
c9e7cf27 | 2037 | collision = find_worker_executing_work(pool, work); |
7e11629d TH |
2038 | if (unlikely(collision)) { |
2039 | move_linked_works(work, &collision->scheduled, NULL); | |
2040 | return; | |
2041 | } | |
2042 | ||
8930caba | 2043 | /* claim and dequeue */ |
a62428c0 | 2044 | debug_work_deactivate(work); |
c9e7cf27 | 2045 | hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); |
c34056a3 | 2046 | worker->current_work = work; |
a2c1c57b | 2047 | worker->current_func = work->func; |
112202d9 | 2048 | worker->current_pwq = pwq; |
73f53c4a | 2049 | work_color = get_work_color(work); |
7a22ad75 | 2050 | |
a62428c0 TH |
2051 | list_del_init(&work->entry); |
2052 | ||
fb0e7beb | 2053 | /* |
228f1d00 LJ |
2054 | * CPU intensive works don't participate in concurrency management. |
2055 | * They're the scheduler's responsibility. This takes @worker out | |
2056 | * of concurrency management and the next code block will chain | |
2057 | * execution of the pending work items. | |
fb0e7beb TH |
2058 | */ |
2059 | if (unlikely(cpu_intensive)) | |
228f1d00 | 2060 | worker_set_flags(worker, WORKER_CPU_INTENSIVE); |
fb0e7beb | 2061 | |
974271c4 | 2062 | /* |
a489a03e LJ |
2063 | * Wake up another worker if necessary. The condition is always |
2064 | * false for normal per-cpu workers since nr_running would always | |
2065 | * be >= 1 at this point. This is used to chain execution of the | |
2066 | * pending work items for WORKER_NOT_RUNNING workers such as the | |
228f1d00 | 2067 | * UNBOUND and CPU_INTENSIVE ones. |
974271c4 | 2068 | */ |
a489a03e | 2069 | if (need_more_worker(pool)) |
63d95a91 | 2070 | wake_up_worker(pool); |
974271c4 | 2071 | |
8930caba | 2072 | /* |
7c3eed5c | 2073 | * Record the last pool and clear PENDING which should be the last |
d565ed63 | 2074 | * update to @work. Also, do this inside @pool->lock so that |
23657bb1 TH |
2075 | * PENDING and queued state changes happen together while IRQ is |
2076 | * disabled. | |
8930caba | 2077 | */ |
7c3eed5c | 2078 | set_work_pool_and_clear_pending(work, pool->id); |
a62428c0 | 2079 | |
d565ed63 | 2080 | spin_unlock_irq(&pool->lock); |
a62428c0 | 2081 | |
112202d9 | 2082 | lock_map_acquire_read(&pwq->wq->lockdep_map); |
a62428c0 | 2083 | lock_map_acquire(&lockdep_map); |
e36c886a | 2084 | trace_workqueue_execute_start(work); |
a2c1c57b | 2085 | worker->current_func(work); |
e36c886a AV |
2086 | /* |
2087 | * While we must be careful to not use "work" after this, the trace | |
2088 | * point will only record its address. | |
2089 | */ | |
2090 | trace_workqueue_execute_end(work); | |
a62428c0 | 2091 | lock_map_release(&lockdep_map); |
112202d9 | 2092 | lock_map_release(&pwq->wq->lockdep_map); |
a62428c0 TH |
2093 | |
2094 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { | |
044c782c VI |
2095 | pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" |
2096 | " last function: %pf\n", | |
a2c1c57b TH |
2097 | current->comm, preempt_count(), task_pid_nr(current), |
2098 | worker->current_func); | |
a62428c0 TH |
2099 | debug_show_held_locks(current); |
2100 | dump_stack(); | |
2101 | } | |
2102 | ||
b22ce278 TH |
2103 | /* |
2104 | * The following prevents a kworker from hogging CPU on !PREEMPT | |
2105 | * kernels, where a requeueing work item waiting for something to | |
2106 | * happen could deadlock with stop_machine as such work item could | |
2107 | * indefinitely requeue itself while all other CPUs are trapped in | |
789cbbec JL |
2108 | * stop_machine. At the same time, report a quiescent RCU state so |
2109 | * the same condition doesn't freeze RCU. | |
b22ce278 | 2110 | */ |
3e28e377 | 2111 | cond_resched_rcu_qs(); |
b22ce278 | 2112 | |
d565ed63 | 2113 | spin_lock_irq(&pool->lock); |
a62428c0 | 2114 | |
fb0e7beb TH |
2115 | /* clear cpu intensive status */ |
2116 | if (unlikely(cpu_intensive)) | |
2117 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); | |
2118 | ||
a62428c0 | 2119 | /* we're done with it, release */ |
42f8570f | 2120 | hash_del(&worker->hentry); |
c34056a3 | 2121 | worker->current_work = NULL; |
a2c1c57b | 2122 | worker->current_func = NULL; |
112202d9 | 2123 | worker->current_pwq = NULL; |
3d1cb205 | 2124 | worker->desc_valid = false; |
112202d9 | 2125 | pwq_dec_nr_in_flight(pwq, work_color); |
a62428c0 TH |
2126 | } |
2127 | ||
affee4b2 TH |
2128 | /** |
2129 | * process_scheduled_works - process scheduled works | |
2130 | * @worker: self | |
2131 | * | |
2132 | * Process all scheduled works. Please note that the scheduled list | |
2133 | * may change while processing a work, so this function repeatedly | |
2134 | * fetches a work from the top and executes it. | |
2135 | * | |
2136 | * CONTEXT: | |
d565ed63 | 2137 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
affee4b2 TH |
2138 | * multiple times. |
2139 | */ | |
2140 | static void process_scheduled_works(struct worker *worker) | |
1da177e4 | 2141 | { |
affee4b2 TH |
2142 | while (!list_empty(&worker->scheduled)) { |
2143 | struct work_struct *work = list_first_entry(&worker->scheduled, | |
1da177e4 | 2144 | struct work_struct, entry); |
c34056a3 | 2145 | process_one_work(worker, work); |
1da177e4 | 2146 | } |
1da177e4 LT |
2147 | } |
2148 | ||
4690c4ab TH |
2149 | /** |
2150 | * worker_thread - the worker thread function | |
c34056a3 | 2151 | * @__worker: self |
4690c4ab | 2152 | * |
c5aa87bb TH |
2153 | * The worker thread function. All workers belong to a worker_pool - |
2154 | * either a per-cpu one or dynamic unbound one. These workers process all | |
2155 | * work items regardless of their specific target workqueue. The only | |
2156 | * exception is work items which belong to workqueues with a rescuer which | |
2157 | * will be explained in rescuer_thread(). | |
d185af30 YB |
2158 | * |
2159 | * Return: 0 | |
4690c4ab | 2160 | */ |
c34056a3 | 2161 | static int worker_thread(void *__worker) |
1da177e4 | 2162 | { |
c34056a3 | 2163 | struct worker *worker = __worker; |
bd7bdd43 | 2164 | struct worker_pool *pool = worker->pool; |
1da177e4 | 2165 | |
e22bee78 TH |
2166 | /* tell the scheduler that this is a workqueue worker */ |
2167 | worker->task->flags |= PF_WQ_WORKER; | |
c8e55f36 | 2168 | woke_up: |
d565ed63 | 2169 | spin_lock_irq(&pool->lock); |
1da177e4 | 2170 | |
a9ab775b TH |
2171 | /* am I supposed to die? */ |
2172 | if (unlikely(worker->flags & WORKER_DIE)) { | |
d565ed63 | 2173 | spin_unlock_irq(&pool->lock); |
a9ab775b TH |
2174 | WARN_ON_ONCE(!list_empty(&worker->entry)); |
2175 | worker->task->flags &= ~PF_WQ_WORKER; | |
60f5a4bc LJ |
2176 | |
2177 | set_task_comm(worker->task, "kworker/dying"); | |
7cda9aae | 2178 | ida_simple_remove(&pool->worker_ida, worker->id); |
60f5a4bc LJ |
2179 | worker_detach_from_pool(worker, pool); |
2180 | kfree(worker); | |
a9ab775b | 2181 | return 0; |
c8e55f36 | 2182 | } |
affee4b2 | 2183 | |
c8e55f36 | 2184 | worker_leave_idle(worker); |
db7bccf4 | 2185 | recheck: |
e22bee78 | 2186 | /* no more worker necessary? */ |
63d95a91 | 2187 | if (!need_more_worker(pool)) |
e22bee78 TH |
2188 | goto sleep; |
2189 | ||
2190 | /* do we need to manage? */ | |
63d95a91 | 2191 | if (unlikely(!may_start_working(pool)) && manage_workers(worker)) |
e22bee78 TH |
2192 | goto recheck; |
2193 | ||
c8e55f36 TH |
2194 | /* |
2195 | * ->scheduled list can only be filled while a worker is | |
2196 | * preparing to process a work or actually processing it. | |
2197 | * Make sure nobody diddled with it while I was sleeping. | |
2198 | */ | |
6183c009 | 2199 | WARN_ON_ONCE(!list_empty(&worker->scheduled)); |
c8e55f36 | 2200 | |
e22bee78 | 2201 | /* |
a9ab775b TH |
2202 | * Finish PREP stage. We're guaranteed to have at least one idle |
2203 | * worker or that someone else has already assumed the manager | |
2204 | * role. This is where @worker starts participating in concurrency | |
2205 | * management if applicable and concurrency management is restored | |
2206 | * after being rebound. See rebind_workers() for details. | |
e22bee78 | 2207 | */ |
a9ab775b | 2208 | worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); |
e22bee78 TH |
2209 | |
2210 | do { | |
c8e55f36 | 2211 | struct work_struct *work = |
bd7bdd43 | 2212 | list_first_entry(&pool->worklist, |
c8e55f36 TH |
2213 | struct work_struct, entry); |
2214 | ||
82607adc TH |
2215 | pool->watchdog_ts = jiffies; |
2216 | ||
c8e55f36 TH |
2217 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
2218 | /* optimization path, not strictly necessary */ | |
2219 | process_one_work(worker, work); | |
2220 | if (unlikely(!list_empty(&worker->scheduled))) | |
affee4b2 | 2221 | process_scheduled_works(worker); |
c8e55f36 TH |
2222 | } else { |
2223 | move_linked_works(work, &worker->scheduled, NULL); | |
2224 | process_scheduled_works(worker); | |
affee4b2 | 2225 | } |
63d95a91 | 2226 | } while (keep_working(pool)); |
e22bee78 | 2227 | |
228f1d00 | 2228 | worker_set_flags(worker, WORKER_PREP); |
d313dd85 | 2229 | sleep: |
c8e55f36 | 2230 | /* |
d565ed63 TH |
2231 | * pool->lock is held and there's no work to process and no need to |
2232 | * manage, sleep. Workers are woken up only while holding | |
2233 | * pool->lock or from local cpu, so setting the current state | |
2234 | * before releasing pool->lock is enough to prevent losing any | |
2235 | * event. | |
c8e55f36 TH |
2236 | */ |
2237 | worker_enter_idle(worker); | |
2238 | __set_current_state(TASK_INTERRUPTIBLE); | |
d565ed63 | 2239 | spin_unlock_irq(&pool->lock); |
c8e55f36 TH |
2240 | schedule(); |
2241 | goto woke_up; | |
1da177e4 LT |
2242 | } |
2243 | ||
e22bee78 TH |
2244 | /** |
2245 | * rescuer_thread - the rescuer thread function | |
111c225a | 2246 | * @__rescuer: self |
e22bee78 TH |
2247 | * |
2248 | * Workqueue rescuer thread function. There's one rescuer for each | |
493008a8 | 2249 | * workqueue which has WQ_MEM_RECLAIM set. |
e22bee78 | 2250 | * |
706026c2 | 2251 | * Regular work processing on a pool may block trying to create a new |
e22bee78 TH |
2252 | * worker which uses GFP_KERNEL allocation which has slight chance of |
2253 | * developing into deadlock if some works currently on the same queue | |
2254 | * need to be processed to satisfy the GFP_KERNEL allocation. This is | |
2255 | * the problem rescuer solves. | |
2256 | * | |
706026c2 TH |
2257 | * When such condition is possible, the pool summons rescuers of all |
2258 | * workqueues which have works queued on the pool and let them process | |
e22bee78 TH |
2259 | * those works so that forward progress can be guaranteed. |
2260 | * | |
2261 | * This should happen rarely. | |
d185af30 YB |
2262 | * |
2263 | * Return: 0 | |
e22bee78 | 2264 | */ |
111c225a | 2265 | static int rescuer_thread(void *__rescuer) |
e22bee78 | 2266 | { |
111c225a TH |
2267 | struct worker *rescuer = __rescuer; |
2268 | struct workqueue_struct *wq = rescuer->rescue_wq; | |
e22bee78 | 2269 | struct list_head *scheduled = &rescuer->scheduled; |
4d595b86 | 2270 | bool should_stop; |
e22bee78 TH |
2271 | |
2272 | set_user_nice(current, RESCUER_NICE_LEVEL); | |
111c225a TH |
2273 | |
2274 | /* | |
2275 | * Mark rescuer as worker too. As WORKER_PREP is never cleared, it | |
2276 | * doesn't participate in concurrency management. | |
2277 | */ | |
2278 | rescuer->task->flags |= PF_WQ_WORKER; | |
e22bee78 TH |
2279 | repeat: |
2280 | set_current_state(TASK_INTERRUPTIBLE); | |
2281 | ||
4d595b86 LJ |
2282 | /* |
2283 | * By the time the rescuer is requested to stop, the workqueue | |
2284 | * shouldn't have any work pending, but @wq->maydays may still have | |
2285 | * pwq(s) queued. This can happen by non-rescuer workers consuming | |
2286 | * all the work items before the rescuer got to them. Go through | |
2287 | * @wq->maydays processing before acting on should_stop so that the | |
2288 | * list is always empty on exit. | |
2289 | */ | |
2290 | should_stop = kthread_should_stop(); | |
e22bee78 | 2291 | |
493a1724 | 2292 | /* see whether any pwq is asking for help */ |
2e109a28 | 2293 | spin_lock_irq(&wq_mayday_lock); |
493a1724 TH |
2294 | |
2295 | while (!list_empty(&wq->maydays)) { | |
2296 | struct pool_workqueue *pwq = list_first_entry(&wq->maydays, | |
2297 | struct pool_workqueue, mayday_node); | |
112202d9 | 2298 | struct worker_pool *pool = pwq->pool; |
e22bee78 | 2299 | struct work_struct *work, *n; |
82607adc | 2300 | bool first = true; |
e22bee78 TH |
2301 | |
2302 | __set_current_state(TASK_RUNNING); | |
493a1724 TH |
2303 | list_del_init(&pwq->mayday_node); |
2304 | ||
2e109a28 | 2305 | spin_unlock_irq(&wq_mayday_lock); |
e22bee78 | 2306 | |
51697d39 LJ |
2307 | worker_attach_to_pool(rescuer, pool); |
2308 | ||
2309 | spin_lock_irq(&pool->lock); | |
b3104104 | 2310 | rescuer->pool = pool; |
e22bee78 TH |
2311 | |
2312 | /* | |
2313 | * Slurp in all works issued via this workqueue and | |
2314 | * process'em. | |
2315 | */ | |
0479c8c5 | 2316 | WARN_ON_ONCE(!list_empty(scheduled)); |
82607adc TH |
2317 | list_for_each_entry_safe(work, n, &pool->worklist, entry) { |
2318 | if (get_work_pwq(work) == pwq) { | |
2319 | if (first) | |
2320 | pool->watchdog_ts = jiffies; | |
e22bee78 | 2321 | move_linked_works(work, scheduled, &n); |
82607adc TH |
2322 | } |
2323 | first = false; | |
2324 | } | |
e22bee78 | 2325 | |
008847f6 N |
2326 | if (!list_empty(scheduled)) { |
2327 | process_scheduled_works(rescuer); | |
2328 | ||
2329 | /* | |
2330 | * The above execution of rescued work items could | |
2331 | * have created more to rescue through | |
2332 | * pwq_activate_first_delayed() or chained | |
2333 | * queueing. Let's put @pwq back on mayday list so | |
2334 | * that such back-to-back work items, which may be | |
2335 | * being used to relieve memory pressure, don't | |
2336 | * incur MAYDAY_INTERVAL delay inbetween. | |
2337 | */ | |
2338 | if (need_to_create_worker(pool)) { | |
2339 | spin_lock(&wq_mayday_lock); | |
2340 | get_pwq(pwq); | |
2341 | list_move_tail(&pwq->mayday_node, &wq->maydays); | |
2342 | spin_unlock(&wq_mayday_lock); | |
2343 | } | |
2344 | } | |
7576958a | 2345 | |
77668c8b LJ |
2346 | /* |
2347 | * Put the reference grabbed by send_mayday(). @pool won't | |
13b1d625 | 2348 | * go away while we're still attached to it. |
77668c8b LJ |
2349 | */ |
2350 | put_pwq(pwq); | |
2351 | ||
7576958a | 2352 | /* |
d8ca83e6 | 2353 | * Leave this pool. If need_more_worker() is %true, notify a |
7576958a TH |
2354 | * regular worker; otherwise, we end up with 0 concurrency |
2355 | * and stalling the execution. | |
2356 | */ | |
d8ca83e6 | 2357 | if (need_more_worker(pool)) |
63d95a91 | 2358 | wake_up_worker(pool); |
7576958a | 2359 | |
b3104104 | 2360 | rescuer->pool = NULL; |
13b1d625 LJ |
2361 | spin_unlock_irq(&pool->lock); |
2362 | ||
2363 | worker_detach_from_pool(rescuer, pool); | |
2364 | ||
2365 | spin_lock_irq(&wq_mayday_lock); | |
e22bee78 TH |
2366 | } |
2367 | ||
2e109a28 | 2368 | spin_unlock_irq(&wq_mayday_lock); |
493a1724 | 2369 | |
4d595b86 LJ |
2370 | if (should_stop) { |
2371 | __set_current_state(TASK_RUNNING); | |
2372 | rescuer->task->flags &= ~PF_WQ_WORKER; | |
2373 | return 0; | |
2374 | } | |
2375 | ||
111c225a TH |
2376 | /* rescuers should never participate in concurrency management */ |
2377 | WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); | |
e22bee78 TH |
2378 | schedule(); |
2379 | goto repeat; | |
1da177e4 LT |
2380 | } |
2381 | ||
fca839c0 TH |
2382 | /** |
2383 | * check_flush_dependency - check for flush dependency sanity | |
2384 | * @target_wq: workqueue being flushed | |
2385 | * @target_work: work item being flushed (NULL for workqueue flushes) | |
2386 | * | |
2387 | * %current is trying to flush the whole @target_wq or @target_work on it. | |
2388 | * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not | |
2389 | * reclaiming memory or running on a workqueue which doesn't have | |
2390 | * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to | |
2391 | * a deadlock. | |
2392 | */ | |
2393 | static void check_flush_dependency(struct workqueue_struct *target_wq, | |
2394 | struct work_struct *target_work) | |
2395 | { | |
2396 | work_func_t target_func = target_work ? target_work->func : NULL; | |
2397 | struct worker *worker; | |
2398 | ||
2399 | if (target_wq->flags & WQ_MEM_RECLAIM) | |
2400 | return; | |
2401 | ||
2402 | worker = current_wq_worker(); | |
2403 | ||
2404 | WARN_ONCE(current->flags & PF_MEMALLOC, | |
2405 | "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%pf", | |
2406 | current->pid, current->comm, target_wq->name, target_func); | |
23d11a58 TH |
2407 | WARN_ONCE(worker && ((worker->current_pwq->wq->flags & |
2408 | (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), | |
fca839c0 TH |
2409 | "workqueue: WQ_MEM_RECLAIM %s:%pf is flushing !WQ_MEM_RECLAIM %s:%pf", |
2410 | worker->current_pwq->wq->name, worker->current_func, | |
2411 | target_wq->name, target_func); | |
2412 | } | |
2413 | ||
fc2e4d70 ON |
2414 | struct wq_barrier { |
2415 | struct work_struct work; | |
2416 | struct completion done; | |
2607d7a6 | 2417 | struct task_struct *task; /* purely informational */ |
fc2e4d70 ON |
2418 | }; |
2419 | ||
2420 | static void wq_barrier_func(struct work_struct *work) | |
2421 | { | |
2422 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); | |
2423 | complete(&barr->done); | |
2424 | } | |
2425 | ||
4690c4ab TH |
2426 | /** |
2427 | * insert_wq_barrier - insert a barrier work | |
112202d9 | 2428 | * @pwq: pwq to insert barrier into |
4690c4ab | 2429 | * @barr: wq_barrier to insert |
affee4b2 TH |
2430 | * @target: target work to attach @barr to |
2431 | * @worker: worker currently executing @target, NULL if @target is not executing | |
4690c4ab | 2432 | * |
affee4b2 TH |
2433 | * @barr is linked to @target such that @barr is completed only after |
2434 | * @target finishes execution. Please note that the ordering | |
2435 | * guarantee is observed only with respect to @target and on the local | |
2436 | * cpu. | |
2437 | * | |
2438 | * Currently, a queued barrier can't be canceled. This is because | |
2439 | * try_to_grab_pending() can't determine whether the work to be | |
2440 | * grabbed is at the head of the queue and thus can't clear LINKED | |
2441 | * flag of the previous work while there must be a valid next work | |
2442 | * after a work with LINKED flag set. | |
2443 | * | |
2444 | * Note that when @worker is non-NULL, @target may be modified | |
112202d9 | 2445 | * underneath us, so we can't reliably determine pwq from @target. |
4690c4ab TH |
2446 | * |
2447 | * CONTEXT: | |
d565ed63 | 2448 | * spin_lock_irq(pool->lock). |
4690c4ab | 2449 | */ |
112202d9 | 2450 | static void insert_wq_barrier(struct pool_workqueue *pwq, |
affee4b2 TH |
2451 | struct wq_barrier *barr, |
2452 | struct work_struct *target, struct worker *worker) | |
fc2e4d70 | 2453 | { |
affee4b2 TH |
2454 | struct list_head *head; |
2455 | unsigned int linked = 0; | |
2456 | ||
dc186ad7 | 2457 | /* |
d565ed63 | 2458 | * debugobject calls are safe here even with pool->lock locked |
dc186ad7 TG |
2459 | * as we know for sure that this will not trigger any of the |
2460 | * checks and call back into the fixup functions where we | |
2461 | * might deadlock. | |
2462 | */ | |
ca1cab37 | 2463 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
22df02bb | 2464 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
fc2e4d70 | 2465 | init_completion(&barr->done); |
2607d7a6 | 2466 | barr->task = current; |
83c22520 | 2467 | |
affee4b2 TH |
2468 | /* |
2469 | * If @target is currently being executed, schedule the | |
2470 | * barrier to the worker; otherwise, put it after @target. | |
2471 | */ | |
2472 | if (worker) | |
2473 | head = worker->scheduled.next; | |
2474 | else { | |
2475 | unsigned long *bits = work_data_bits(target); | |
2476 | ||
2477 | head = target->entry.next; | |
2478 | /* there can already be other linked works, inherit and set */ | |
2479 | linked = *bits & WORK_STRUCT_LINKED; | |
2480 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); | |
2481 | } | |
2482 | ||
dc186ad7 | 2483 | debug_work_activate(&barr->work); |
112202d9 | 2484 | insert_work(pwq, &barr->work, head, |
affee4b2 | 2485 | work_color_to_flags(WORK_NO_COLOR) | linked); |
fc2e4d70 ON |
2486 | } |
2487 | ||
73f53c4a | 2488 | /** |
112202d9 | 2489 | * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing |
73f53c4a TH |
2490 | * @wq: workqueue being flushed |
2491 | * @flush_color: new flush color, < 0 for no-op | |
2492 | * @work_color: new work color, < 0 for no-op | |
2493 | * | |
112202d9 | 2494 | * Prepare pwqs for workqueue flushing. |
73f53c4a | 2495 | * |
112202d9 TH |
2496 | * If @flush_color is non-negative, flush_color on all pwqs should be |
2497 | * -1. If no pwq has in-flight commands at the specified color, all | |
2498 | * pwq->flush_color's stay at -1 and %false is returned. If any pwq | |
2499 | * has in flight commands, its pwq->flush_color is set to | |
2500 | * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq | |
73f53c4a TH |
2501 | * wakeup logic is armed and %true is returned. |
2502 | * | |
2503 | * The caller should have initialized @wq->first_flusher prior to | |
2504 | * calling this function with non-negative @flush_color. If | |
2505 | * @flush_color is negative, no flush color update is done and %false | |
2506 | * is returned. | |
2507 | * | |
112202d9 | 2508 | * If @work_color is non-negative, all pwqs should have the same |
73f53c4a TH |
2509 | * work_color which is previous to @work_color and all will be |
2510 | * advanced to @work_color. | |
2511 | * | |
2512 | * CONTEXT: | |
3c25a55d | 2513 | * mutex_lock(wq->mutex). |
73f53c4a | 2514 | * |
d185af30 | 2515 | * Return: |
73f53c4a TH |
2516 | * %true if @flush_color >= 0 and there's something to flush. %false |
2517 | * otherwise. | |
2518 | */ | |
112202d9 | 2519 | static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, |
73f53c4a | 2520 | int flush_color, int work_color) |
1da177e4 | 2521 | { |
73f53c4a | 2522 | bool wait = false; |
49e3cf44 | 2523 | struct pool_workqueue *pwq; |
1da177e4 | 2524 | |
73f53c4a | 2525 | if (flush_color >= 0) { |
6183c009 | 2526 | WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); |
112202d9 | 2527 | atomic_set(&wq->nr_pwqs_to_flush, 1); |
1da177e4 | 2528 | } |
2355b70f | 2529 | |
49e3cf44 | 2530 | for_each_pwq(pwq, wq) { |
112202d9 | 2531 | struct worker_pool *pool = pwq->pool; |
fc2e4d70 | 2532 | |
b09f4fd3 | 2533 | spin_lock_irq(&pool->lock); |
83c22520 | 2534 | |
73f53c4a | 2535 | if (flush_color >= 0) { |
6183c009 | 2536 | WARN_ON_ONCE(pwq->flush_color != -1); |
fc2e4d70 | 2537 | |
112202d9 TH |
2538 | if (pwq->nr_in_flight[flush_color]) { |
2539 | pwq->flush_color = flush_color; | |
2540 | atomic_inc(&wq->nr_pwqs_to_flush); | |
73f53c4a TH |
2541 | wait = true; |
2542 | } | |
2543 | } | |
1da177e4 | 2544 | |
73f53c4a | 2545 | if (work_color >= 0) { |
6183c009 | 2546 | WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); |
112202d9 | 2547 | pwq->work_color = work_color; |
73f53c4a | 2548 | } |
1da177e4 | 2549 | |
b09f4fd3 | 2550 | spin_unlock_irq(&pool->lock); |
1da177e4 | 2551 | } |
2355b70f | 2552 | |
112202d9 | 2553 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) |
73f53c4a | 2554 | complete(&wq->first_flusher->done); |
14441960 | 2555 | |
73f53c4a | 2556 | return wait; |
1da177e4 LT |
2557 | } |
2558 | ||
0fcb78c2 | 2559 | /** |
1da177e4 | 2560 | * flush_workqueue - ensure that any scheduled work has run to completion. |
0fcb78c2 | 2561 | * @wq: workqueue to flush |
1da177e4 | 2562 | * |
c5aa87bb TH |
2563 | * This function sleeps until all work items which were queued on entry |
2564 | * have finished execution, but it is not livelocked by new incoming ones. | |
1da177e4 | 2565 | */ |
7ad5b3a5 | 2566 | void flush_workqueue(struct workqueue_struct *wq) |
1da177e4 | 2567 | { |
73f53c4a TH |
2568 | struct wq_flusher this_flusher = { |
2569 | .list = LIST_HEAD_INIT(this_flusher.list), | |
2570 | .flush_color = -1, | |
2571 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), | |
2572 | }; | |
2573 | int next_color; | |
1da177e4 | 2574 | |
3295f0ef IM |
2575 | lock_map_acquire(&wq->lockdep_map); |
2576 | lock_map_release(&wq->lockdep_map); | |
73f53c4a | 2577 | |
3c25a55d | 2578 | mutex_lock(&wq->mutex); |
73f53c4a TH |
2579 | |
2580 | /* | |
2581 | * Start-to-wait phase | |
2582 | */ | |
2583 | next_color = work_next_color(wq->work_color); | |
2584 | ||
2585 | if (next_color != wq->flush_color) { | |
2586 | /* | |
2587 | * Color space is not full. The current work_color | |
2588 | * becomes our flush_color and work_color is advanced | |
2589 | * by one. | |
2590 | */ | |
6183c009 | 2591 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); |
73f53c4a TH |
2592 | this_flusher.flush_color = wq->work_color; |
2593 | wq->work_color = next_color; | |
2594 | ||
2595 | if (!wq->first_flusher) { | |
2596 | /* no flush in progress, become the first flusher */ | |
6183c009 | 2597 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
73f53c4a TH |
2598 | |
2599 | wq->first_flusher = &this_flusher; | |
2600 | ||
112202d9 | 2601 | if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, |
73f53c4a TH |
2602 | wq->work_color)) { |
2603 | /* nothing to flush, done */ | |
2604 | wq->flush_color = next_color; | |
2605 | wq->first_flusher = NULL; | |
2606 | goto out_unlock; | |
2607 | } | |
2608 | } else { | |
2609 | /* wait in queue */ | |
6183c009 | 2610 | WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); |
73f53c4a | 2611 | list_add_tail(&this_flusher.list, &wq->flusher_queue); |
112202d9 | 2612 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
73f53c4a TH |
2613 | } |
2614 | } else { | |
2615 | /* | |
2616 | * Oops, color space is full, wait on overflow queue. | |
2617 | * The next flush completion will assign us | |
2618 | * flush_color and transfer to flusher_queue. | |
2619 | */ | |
2620 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); | |
2621 | } | |
2622 | ||
fca839c0 TH |
2623 | check_flush_dependency(wq, NULL); |
2624 | ||
3c25a55d | 2625 | mutex_unlock(&wq->mutex); |
73f53c4a TH |
2626 | |
2627 | wait_for_completion(&this_flusher.done); | |
2628 | ||
2629 | /* | |
2630 | * Wake-up-and-cascade phase | |
2631 | * | |
2632 | * First flushers are responsible for cascading flushes and | |
2633 | * handling overflow. Non-first flushers can simply return. | |
2634 | */ | |
2635 | if (wq->first_flusher != &this_flusher) | |
2636 | return; | |
2637 | ||
3c25a55d | 2638 | mutex_lock(&wq->mutex); |
73f53c4a | 2639 | |
4ce48b37 TH |
2640 | /* we might have raced, check again with mutex held */ |
2641 | if (wq->first_flusher != &this_flusher) | |
2642 | goto out_unlock; | |
2643 | ||
73f53c4a TH |
2644 | wq->first_flusher = NULL; |
2645 | ||
6183c009 TH |
2646 | WARN_ON_ONCE(!list_empty(&this_flusher.list)); |
2647 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); | |
73f53c4a TH |
2648 | |
2649 | while (true) { | |
2650 | struct wq_flusher *next, *tmp; | |
2651 | ||
2652 | /* complete all the flushers sharing the current flush color */ | |
2653 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { | |
2654 | if (next->flush_color != wq->flush_color) | |
2655 | break; | |
2656 | list_del_init(&next->list); | |
2657 | complete(&next->done); | |
2658 | } | |
2659 | ||
6183c009 TH |
2660 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && |
2661 | wq->flush_color != work_next_color(wq->work_color)); | |
73f53c4a TH |
2662 | |
2663 | /* this flush_color is finished, advance by one */ | |
2664 | wq->flush_color = work_next_color(wq->flush_color); | |
2665 | ||
2666 | /* one color has been freed, handle overflow queue */ | |
2667 | if (!list_empty(&wq->flusher_overflow)) { | |
2668 | /* | |
2669 | * Assign the same color to all overflowed | |
2670 | * flushers, advance work_color and append to | |
2671 | * flusher_queue. This is the start-to-wait | |
2672 | * phase for these overflowed flushers. | |
2673 | */ | |
2674 | list_for_each_entry(tmp, &wq->flusher_overflow, list) | |
2675 | tmp->flush_color = wq->work_color; | |
2676 | ||
2677 | wq->work_color = work_next_color(wq->work_color); | |
2678 | ||
2679 | list_splice_tail_init(&wq->flusher_overflow, | |
2680 | &wq->flusher_queue); | |
112202d9 | 2681 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
73f53c4a TH |
2682 | } |
2683 | ||
2684 | if (list_empty(&wq->flusher_queue)) { | |
6183c009 | 2685 | WARN_ON_ONCE(wq->flush_color != wq->work_color); |
73f53c4a TH |
2686 | break; |
2687 | } | |
2688 | ||
2689 | /* | |
2690 | * Need to flush more colors. Make the next flusher | |
112202d9 | 2691 | * the new first flusher and arm pwqs. |
73f53c4a | 2692 | */ |
6183c009 TH |
2693 | WARN_ON_ONCE(wq->flush_color == wq->work_color); |
2694 | WARN_ON_ONCE(wq->flush_color != next->flush_color); | |
73f53c4a TH |
2695 | |
2696 | list_del_init(&next->list); | |
2697 | wq->first_flusher = next; | |
2698 | ||
112202d9 | 2699 | if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) |
73f53c4a TH |
2700 | break; |
2701 | ||
2702 | /* | |
2703 | * Meh... this color is already done, clear first | |
2704 | * flusher and repeat cascading. | |
2705 | */ | |
2706 | wq->first_flusher = NULL; | |
2707 | } | |
2708 | ||
2709 | out_unlock: | |
3c25a55d | 2710 | mutex_unlock(&wq->mutex); |
1da177e4 | 2711 | } |
1dadafa8 | 2712 | EXPORT_SYMBOL(flush_workqueue); |
1da177e4 | 2713 | |
9c5a2ba7 TH |
2714 | /** |
2715 | * drain_workqueue - drain a workqueue | |
2716 | * @wq: workqueue to drain | |
2717 | * | |
2718 | * Wait until the workqueue becomes empty. While draining is in progress, | |
2719 | * only chain queueing is allowed. IOW, only currently pending or running | |
2720 | * work items on @wq can queue further work items on it. @wq is flushed | |
b749b1b6 | 2721 | * repeatedly until it becomes empty. The number of flushing is determined |
9c5a2ba7 TH |
2722 | * by the depth of chaining and should be relatively short. Whine if it |
2723 | * takes too long. | |
2724 | */ | |
2725 | void drain_workqueue(struct workqueue_struct *wq) | |
2726 | { | |
2727 | unsigned int flush_cnt = 0; | |
49e3cf44 | 2728 | struct pool_workqueue *pwq; |
9c5a2ba7 TH |
2729 | |
2730 | /* | |
2731 | * __queue_work() needs to test whether there are drainers, is much | |
2732 | * hotter than drain_workqueue() and already looks at @wq->flags. | |
618b01eb | 2733 | * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. |
9c5a2ba7 | 2734 | */ |
87fc741e | 2735 | mutex_lock(&wq->mutex); |
9c5a2ba7 | 2736 | if (!wq->nr_drainers++) |
618b01eb | 2737 | wq->flags |= __WQ_DRAINING; |
87fc741e | 2738 | mutex_unlock(&wq->mutex); |
9c5a2ba7 TH |
2739 | reflush: |
2740 | flush_workqueue(wq); | |
2741 | ||
b09f4fd3 | 2742 | mutex_lock(&wq->mutex); |
76af4d93 | 2743 | |
49e3cf44 | 2744 | for_each_pwq(pwq, wq) { |
fa2563e4 | 2745 | bool drained; |
9c5a2ba7 | 2746 | |
b09f4fd3 | 2747 | spin_lock_irq(&pwq->pool->lock); |
112202d9 | 2748 | drained = !pwq->nr_active && list_empty(&pwq->delayed_works); |
b09f4fd3 | 2749 | spin_unlock_irq(&pwq->pool->lock); |
fa2563e4 TT |
2750 | |
2751 | if (drained) | |
9c5a2ba7 TH |
2752 | continue; |
2753 | ||
2754 | if (++flush_cnt == 10 || | |
2755 | (flush_cnt % 100 == 0 && flush_cnt <= 1000)) | |
c5aa87bb | 2756 | pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n", |
044c782c | 2757 | wq->name, flush_cnt); |
76af4d93 | 2758 | |
b09f4fd3 | 2759 | mutex_unlock(&wq->mutex); |
9c5a2ba7 TH |
2760 | goto reflush; |
2761 | } | |
2762 | ||
9c5a2ba7 | 2763 | if (!--wq->nr_drainers) |
618b01eb | 2764 | wq->flags &= ~__WQ_DRAINING; |
87fc741e | 2765 | mutex_unlock(&wq->mutex); |
9c5a2ba7 TH |
2766 | } |
2767 | EXPORT_SYMBOL_GPL(drain_workqueue); | |
2768 | ||
606a5020 | 2769 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) |
db700897 | 2770 | { |
affee4b2 | 2771 | struct worker *worker = NULL; |
c9e7cf27 | 2772 | struct worker_pool *pool; |
112202d9 | 2773 | struct pool_workqueue *pwq; |
db700897 ON |
2774 | |
2775 | might_sleep(); | |
fa1b54e6 TH |
2776 | |
2777 | local_irq_disable(); | |
c9e7cf27 | 2778 | pool = get_work_pool(work); |
fa1b54e6 TH |
2779 | if (!pool) { |
2780 | local_irq_enable(); | |
baf59022 | 2781 | return false; |
fa1b54e6 | 2782 | } |
db700897 | 2783 | |
fa1b54e6 | 2784 | spin_lock(&pool->lock); |
0b3dae68 | 2785 | /* see the comment in try_to_grab_pending() with the same code */ |
112202d9 TH |
2786 | pwq = get_work_pwq(work); |
2787 | if (pwq) { | |
2788 | if (unlikely(pwq->pool != pool)) | |
4690c4ab | 2789 | goto already_gone; |
606a5020 | 2790 | } else { |
c9e7cf27 | 2791 | worker = find_worker_executing_work(pool, work); |
affee4b2 | 2792 | if (!worker) |
4690c4ab | 2793 | goto already_gone; |
112202d9 | 2794 | pwq = worker->current_pwq; |
606a5020 | 2795 | } |
db700897 | 2796 | |
fca839c0 TH |
2797 | check_flush_dependency(pwq->wq, work); |
2798 | ||
112202d9 | 2799 | insert_wq_barrier(pwq, barr, work, worker); |
d565ed63 | 2800 | spin_unlock_irq(&pool->lock); |
7a22ad75 | 2801 | |
e159489b TH |
2802 | /* |
2803 | * If @max_active is 1 or rescuer is in use, flushing another work | |
2804 | * item on the same workqueue may lead to deadlock. Make sure the | |
2805 | * flusher is not running on the same workqueue by verifying write | |
2806 | * access. | |
2807 | */ | |
493008a8 | 2808 | if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) |
112202d9 | 2809 | lock_map_acquire(&pwq->wq->lockdep_map); |
e159489b | 2810 | else |
112202d9 TH |
2811 | lock_map_acquire_read(&pwq->wq->lockdep_map); |
2812 | lock_map_release(&pwq->wq->lockdep_map); | |
e159489b | 2813 | |
401a8d04 | 2814 | return true; |
4690c4ab | 2815 | already_gone: |
d565ed63 | 2816 | spin_unlock_irq(&pool->lock); |
401a8d04 | 2817 | return false; |
db700897 | 2818 | } |
baf59022 TH |
2819 | |
2820 | /** | |
2821 | * flush_work - wait for a work to finish executing the last queueing instance | |
2822 | * @work: the work to flush | |
2823 | * | |
606a5020 TH |
2824 | * Wait until @work has finished execution. @work is guaranteed to be idle |
2825 | * on return if it hasn't been requeued since flush started. | |
baf59022 | 2826 | * |
d185af30 | 2827 | * Return: |
baf59022 TH |
2828 | * %true if flush_work() waited for the work to finish execution, |
2829 | * %false if it was already idle. | |
2830 | */ | |
2831 | bool flush_work(struct work_struct *work) | |
2832 | { | |
12997d1a BH |
2833 | struct wq_barrier barr; |
2834 | ||
0976dfc1 SB |
2835 | lock_map_acquire(&work->lockdep_map); |
2836 | lock_map_release(&work->lockdep_map); | |
2837 | ||
12997d1a BH |
2838 | if (start_flush_work(work, &barr)) { |
2839 | wait_for_completion(&barr.done); | |
2840 | destroy_work_on_stack(&barr.work); | |
2841 | return true; | |
2842 | } else { | |
2843 | return false; | |
2844 | } | |
6e84d644 | 2845 | } |
606a5020 | 2846 | EXPORT_SYMBOL_GPL(flush_work); |
6e84d644 | 2847 | |
8603e1b3 TH |
2848 | struct cwt_wait { |
2849 | wait_queue_t wait; | |
2850 | struct work_struct *work; | |
2851 | }; | |
2852 | ||
2853 | static int cwt_wakefn(wait_queue_t *wait, unsigned mode, int sync, void *key) | |
2854 | { | |
2855 | struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait); | |
2856 | ||
2857 | if (cwait->work != key) | |
2858 | return 0; | |
2859 | return autoremove_wake_function(wait, mode, sync, key); | |
2860 | } | |
2861 | ||
36e227d2 | 2862 | static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) |
1f1f642e | 2863 | { |
8603e1b3 | 2864 | static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq); |
bbb68dfa | 2865 | unsigned long flags; |
1f1f642e ON |
2866 | int ret; |
2867 | ||
2868 | do { | |
bbb68dfa TH |
2869 | ret = try_to_grab_pending(work, is_dwork, &flags); |
2870 | /* | |
8603e1b3 TH |
2871 | * If someone else is already canceling, wait for it to |
2872 | * finish. flush_work() doesn't work for PREEMPT_NONE | |
2873 | * because we may get scheduled between @work's completion | |
2874 | * and the other canceling task resuming and clearing | |
2875 | * CANCELING - flush_work() will return false immediately | |
2876 | * as @work is no longer busy, try_to_grab_pending() will | |
2877 | * return -ENOENT as @work is still being canceled and the | |
2878 | * other canceling task won't be able to clear CANCELING as | |
2879 | * we're hogging the CPU. | |
2880 | * | |
2881 | * Let's wait for completion using a waitqueue. As this | |
2882 | * may lead to the thundering herd problem, use a custom | |
2883 | * wake function which matches @work along with exclusive | |
2884 | * wait and wakeup. | |
bbb68dfa | 2885 | */ |
8603e1b3 TH |
2886 | if (unlikely(ret == -ENOENT)) { |
2887 | struct cwt_wait cwait; | |
2888 | ||
2889 | init_wait(&cwait.wait); | |
2890 | cwait.wait.func = cwt_wakefn; | |
2891 | cwait.work = work; | |
2892 | ||
2893 | prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait, | |
2894 | TASK_UNINTERRUPTIBLE); | |
2895 | if (work_is_canceling(work)) | |
2896 | schedule(); | |
2897 | finish_wait(&cancel_waitq, &cwait.wait); | |
2898 | } | |
1f1f642e ON |
2899 | } while (unlikely(ret < 0)); |
2900 | ||
bbb68dfa TH |
2901 | /* tell other tasks trying to grab @work to back off */ |
2902 | mark_work_canceling(work); | |
2903 | local_irq_restore(flags); | |
2904 | ||
606a5020 | 2905 | flush_work(work); |
7a22ad75 | 2906 | clear_work_data(work); |
8603e1b3 TH |
2907 | |
2908 | /* | |
2909 | * Paired with prepare_to_wait() above so that either | |
2910 | * waitqueue_active() is visible here or !work_is_canceling() is | |
2911 | * visible there. | |
2912 | */ | |
2913 | smp_mb(); | |
2914 | if (waitqueue_active(&cancel_waitq)) | |
2915 | __wake_up(&cancel_waitq, TASK_NORMAL, 1, work); | |
2916 | ||
1f1f642e ON |
2917 | return ret; |
2918 | } | |
2919 | ||
6e84d644 | 2920 | /** |
401a8d04 TH |
2921 | * cancel_work_sync - cancel a work and wait for it to finish |
2922 | * @work: the work to cancel | |
6e84d644 | 2923 | * |
401a8d04 TH |
2924 | * Cancel @work and wait for its execution to finish. This function |
2925 | * can be used even if the work re-queues itself or migrates to | |
2926 | * another workqueue. On return from this function, @work is | |
2927 | * guaranteed to be not pending or executing on any CPU. | |
1f1f642e | 2928 | * |
401a8d04 TH |
2929 | * cancel_work_sync(&delayed_work->work) must not be used for |
2930 | * delayed_work's. Use cancel_delayed_work_sync() instead. | |
6e84d644 | 2931 | * |
401a8d04 | 2932 | * The caller must ensure that the workqueue on which @work was last |
6e84d644 | 2933 | * queued can't be destroyed before this function returns. |
401a8d04 | 2934 | * |
d185af30 | 2935 | * Return: |
401a8d04 | 2936 | * %true if @work was pending, %false otherwise. |
6e84d644 | 2937 | */ |
401a8d04 | 2938 | bool cancel_work_sync(struct work_struct *work) |
6e84d644 | 2939 | { |
36e227d2 | 2940 | return __cancel_work_timer(work, false); |
b89deed3 | 2941 | } |
28e53bdd | 2942 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
b89deed3 | 2943 | |
6e84d644 | 2944 | /** |
401a8d04 TH |
2945 | * flush_delayed_work - wait for a dwork to finish executing the last queueing |
2946 | * @dwork: the delayed work to flush | |
6e84d644 | 2947 | * |
401a8d04 TH |
2948 | * Delayed timer is cancelled and the pending work is queued for |
2949 | * immediate execution. Like flush_work(), this function only | |
2950 | * considers the last queueing instance of @dwork. | |
1f1f642e | 2951 | * |
d185af30 | 2952 | * Return: |
401a8d04 TH |
2953 | * %true if flush_work() waited for the work to finish execution, |
2954 | * %false if it was already idle. | |
6e84d644 | 2955 | */ |
401a8d04 TH |
2956 | bool flush_delayed_work(struct delayed_work *dwork) |
2957 | { | |
8930caba | 2958 | local_irq_disable(); |
401a8d04 | 2959 | if (del_timer_sync(&dwork->timer)) |
60c057bc | 2960 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); |
8930caba | 2961 | local_irq_enable(); |
401a8d04 TH |
2962 | return flush_work(&dwork->work); |
2963 | } | |
2964 | EXPORT_SYMBOL(flush_delayed_work); | |
2965 | ||
09383498 | 2966 | /** |
57b30ae7 TH |
2967 | * cancel_delayed_work - cancel a delayed work |
2968 | * @dwork: delayed_work to cancel | |
09383498 | 2969 | * |
d185af30 YB |
2970 | * Kill off a pending delayed_work. |
2971 | * | |
2972 | * Return: %true if @dwork was pending and canceled; %false if it wasn't | |
2973 | * pending. | |
2974 | * | |
2975 | * Note: | |
2976 | * The work callback function may still be running on return, unless | |
2977 | * it returns %true and the work doesn't re-arm itself. Explicitly flush or | |
2978 | * use cancel_delayed_work_sync() to wait on it. | |
09383498 | 2979 | * |
57b30ae7 | 2980 | * This function is safe to call from any context including IRQ handler. |
09383498 | 2981 | */ |
57b30ae7 | 2982 | bool cancel_delayed_work(struct delayed_work *dwork) |
09383498 | 2983 | { |
57b30ae7 TH |
2984 | unsigned long flags; |
2985 | int ret; | |
2986 | ||
2987 | do { | |
2988 | ret = try_to_grab_pending(&dwork->work, true, &flags); | |
2989 | } while (unlikely(ret == -EAGAIN)); | |
2990 | ||
2991 | if (unlikely(ret < 0)) | |
2992 | return false; | |
2993 | ||
7c3eed5c TH |
2994 | set_work_pool_and_clear_pending(&dwork->work, |
2995 | get_work_pool_id(&dwork->work)); | |
57b30ae7 | 2996 | local_irq_restore(flags); |
c0158ca6 | 2997 | return ret; |
09383498 | 2998 | } |
57b30ae7 | 2999 | EXPORT_SYMBOL(cancel_delayed_work); |
09383498 | 3000 | |
401a8d04 TH |
3001 | /** |
3002 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish | |
3003 | * @dwork: the delayed work cancel | |
3004 | * | |
3005 | * This is cancel_work_sync() for delayed works. | |
3006 | * | |
d185af30 | 3007 | * Return: |
401a8d04 TH |
3008 | * %true if @dwork was pending, %false otherwise. |
3009 | */ | |
3010 | bool cancel_delayed_work_sync(struct delayed_work *dwork) | |
6e84d644 | 3011 | { |
36e227d2 | 3012 | return __cancel_work_timer(&dwork->work, true); |
6e84d644 | 3013 | } |
f5a421a4 | 3014 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
1da177e4 | 3015 | |
b6136773 | 3016 | /** |
31ddd871 | 3017 | * schedule_on_each_cpu - execute a function synchronously on each online CPU |
b6136773 | 3018 | * @func: the function to call |
b6136773 | 3019 | * |
31ddd871 TH |
3020 | * schedule_on_each_cpu() executes @func on each online CPU using the |
3021 | * system workqueue and blocks until all CPUs have completed. | |
b6136773 | 3022 | * schedule_on_each_cpu() is very slow. |
31ddd871 | 3023 | * |
d185af30 | 3024 | * Return: |
31ddd871 | 3025 | * 0 on success, -errno on failure. |
b6136773 | 3026 | */ |
65f27f38 | 3027 | int schedule_on_each_cpu(work_func_t func) |
15316ba8 CL |
3028 | { |
3029 | int cpu; | |
38f51568 | 3030 | struct work_struct __percpu *works; |
15316ba8 | 3031 | |
b6136773 AM |
3032 | works = alloc_percpu(struct work_struct); |
3033 | if (!works) | |
15316ba8 | 3034 | return -ENOMEM; |
b6136773 | 3035 | |
93981800 TH |
3036 | get_online_cpus(); |
3037 | ||
15316ba8 | 3038 | for_each_online_cpu(cpu) { |
9bfb1839 IM |
3039 | struct work_struct *work = per_cpu_ptr(works, cpu); |
3040 | ||
3041 | INIT_WORK(work, func); | |
b71ab8c2 | 3042 | schedule_work_on(cpu, work); |
65a64464 | 3043 | } |
93981800 TH |
3044 | |
3045 | for_each_online_cpu(cpu) | |
3046 | flush_work(per_cpu_ptr(works, cpu)); | |
3047 | ||
95402b38 | 3048 | put_online_cpus(); |
b6136773 | 3049 | free_percpu(works); |
15316ba8 CL |
3050 | return 0; |
3051 | } | |
3052 | ||
1fa44eca JB |
3053 | /** |
3054 | * execute_in_process_context - reliably execute the routine with user context | |
3055 | * @fn: the function to execute | |
1fa44eca JB |
3056 | * @ew: guaranteed storage for the execute work structure (must |
3057 | * be available when the work executes) | |
3058 | * | |
3059 | * Executes the function immediately if process context is available, | |
3060 | * otherwise schedules the function for delayed execution. | |
3061 | * | |
d185af30 | 3062 | * Return: 0 - function was executed |
1fa44eca JB |
3063 | * 1 - function was scheduled for execution |
3064 | */ | |
65f27f38 | 3065 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
1fa44eca JB |
3066 | { |
3067 | if (!in_interrupt()) { | |
65f27f38 | 3068 | fn(&ew->work); |
1fa44eca JB |
3069 | return 0; |
3070 | } | |
3071 | ||
65f27f38 | 3072 | INIT_WORK(&ew->work, fn); |
1fa44eca JB |
3073 | schedule_work(&ew->work); |
3074 | ||
3075 | return 1; | |
3076 | } | |
3077 | EXPORT_SYMBOL_GPL(execute_in_process_context); | |
3078 | ||
6ba94429 FW |
3079 | /** |
3080 | * free_workqueue_attrs - free a workqueue_attrs | |
3081 | * @attrs: workqueue_attrs to free | |
226223ab | 3082 | * |
6ba94429 | 3083 | * Undo alloc_workqueue_attrs(). |
226223ab | 3084 | */ |
6ba94429 | 3085 | void free_workqueue_attrs(struct workqueue_attrs *attrs) |
226223ab | 3086 | { |
6ba94429 FW |
3087 | if (attrs) { |
3088 | free_cpumask_var(attrs->cpumask); | |
3089 | kfree(attrs); | |
3090 | } | |
226223ab TH |
3091 | } |
3092 | ||
6ba94429 FW |
3093 | /** |
3094 | * alloc_workqueue_attrs - allocate a workqueue_attrs | |
3095 | * @gfp_mask: allocation mask to use | |
3096 | * | |
3097 | * Allocate a new workqueue_attrs, initialize with default settings and | |
3098 | * return it. | |
3099 | * | |
3100 | * Return: The allocated new workqueue_attr on success. %NULL on failure. | |
3101 | */ | |
3102 | struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask) | |
226223ab | 3103 | { |
6ba94429 | 3104 | struct workqueue_attrs *attrs; |
226223ab | 3105 | |
6ba94429 FW |
3106 | attrs = kzalloc(sizeof(*attrs), gfp_mask); |
3107 | if (!attrs) | |
3108 | goto fail; | |
3109 | if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask)) | |
3110 | goto fail; | |
3111 | ||
3112 | cpumask_copy(attrs->cpumask, cpu_possible_mask); | |
3113 | return attrs; | |
3114 | fail: | |
3115 | free_workqueue_attrs(attrs); | |
3116 | return NULL; | |
226223ab TH |
3117 | } |
3118 | ||
6ba94429 FW |
3119 | static void copy_workqueue_attrs(struct workqueue_attrs *to, |
3120 | const struct workqueue_attrs *from) | |
226223ab | 3121 | { |
6ba94429 FW |
3122 | to->nice = from->nice; |
3123 | cpumask_copy(to->cpumask, from->cpumask); | |
3124 | /* | |
3125 | * Unlike hash and equality test, this function doesn't ignore | |
3126 | * ->no_numa as it is used for both pool and wq attrs. Instead, | |
3127 | * get_unbound_pool() explicitly clears ->no_numa after copying. | |
3128 | */ | |
3129 | to->no_numa = from->no_numa; | |
226223ab TH |
3130 | } |
3131 | ||
6ba94429 FW |
3132 | /* hash value of the content of @attr */ |
3133 | static u32 wqattrs_hash(const struct workqueue_attrs *attrs) | |
226223ab | 3134 | { |
6ba94429 | 3135 | u32 hash = 0; |
226223ab | 3136 | |
6ba94429 FW |
3137 | hash = jhash_1word(attrs->nice, hash); |
3138 | hash = jhash(cpumask_bits(attrs->cpumask), | |
3139 | BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); | |
3140 | return hash; | |
226223ab | 3141 | } |
226223ab | 3142 | |
6ba94429 FW |
3143 | /* content equality test */ |
3144 | static bool wqattrs_equal(const struct workqueue_attrs *a, | |
3145 | const struct workqueue_attrs *b) | |
226223ab | 3146 | { |
6ba94429 FW |
3147 | if (a->nice != b->nice) |
3148 | return false; | |
3149 | if (!cpumask_equal(a->cpumask, b->cpumask)) | |
3150 | return false; | |
3151 | return true; | |
226223ab TH |
3152 | } |
3153 | ||
6ba94429 FW |
3154 | /** |
3155 | * init_worker_pool - initialize a newly zalloc'd worker_pool | |
3156 | * @pool: worker_pool to initialize | |
3157 | * | |
402dd89d | 3158 | * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. |
6ba94429 FW |
3159 | * |
3160 | * Return: 0 on success, -errno on failure. Even on failure, all fields | |
3161 | * inside @pool proper are initialized and put_unbound_pool() can be called | |
3162 | * on @pool safely to release it. | |
3163 | */ | |
3164 | static int init_worker_pool(struct worker_pool *pool) | |
226223ab | 3165 | { |
6ba94429 FW |
3166 | spin_lock_init(&pool->lock); |
3167 | pool->id = -1; | |
3168 | pool->cpu = -1; | |
3169 | pool->node = NUMA_NO_NODE; | |
3170 | pool->flags |= POOL_DISASSOCIATED; | |
82607adc | 3171 | pool->watchdog_ts = jiffies; |
6ba94429 FW |
3172 | INIT_LIST_HEAD(&pool->worklist); |
3173 | INIT_LIST_HEAD(&pool->idle_list); | |
3174 | hash_init(pool->busy_hash); | |
226223ab | 3175 | |
6ba94429 FW |
3176 | init_timer_deferrable(&pool->idle_timer); |
3177 | pool->idle_timer.function = idle_worker_timeout; | |
3178 | pool->idle_timer.data = (unsigned long)pool; | |
226223ab | 3179 | |
6ba94429 FW |
3180 | setup_timer(&pool->mayday_timer, pool_mayday_timeout, |
3181 | (unsigned long)pool); | |
226223ab | 3182 | |
6ba94429 FW |
3183 | mutex_init(&pool->manager_arb); |
3184 | mutex_init(&pool->attach_mutex); | |
3185 | INIT_LIST_HEAD(&pool->workers); | |
226223ab | 3186 | |
6ba94429 FW |
3187 | ida_init(&pool->worker_ida); |
3188 | INIT_HLIST_NODE(&pool->hash_node); | |
3189 | pool->refcnt = 1; | |
226223ab | 3190 | |
6ba94429 FW |
3191 | /* shouldn't fail above this point */ |
3192 | pool->attrs = alloc_workqueue_attrs(GFP_KERNEL); | |
3193 | if (!pool->attrs) | |
3194 | return -ENOMEM; | |
3195 | return 0; | |
226223ab TH |
3196 | } |
3197 | ||
6ba94429 | 3198 | static void rcu_free_wq(struct rcu_head *rcu) |
226223ab | 3199 | { |
6ba94429 FW |
3200 | struct workqueue_struct *wq = |
3201 | container_of(rcu, struct workqueue_struct, rcu); | |
226223ab | 3202 | |
6ba94429 FW |
3203 | if (!(wq->flags & WQ_UNBOUND)) |
3204 | free_percpu(wq->cpu_pwqs); | |
226223ab | 3205 | else |
6ba94429 | 3206 | free_workqueue_attrs(wq->unbound_attrs); |
226223ab | 3207 | |
6ba94429 FW |
3208 | kfree(wq->rescuer); |
3209 | kfree(wq); | |
226223ab TH |
3210 | } |
3211 | ||
6ba94429 | 3212 | static void rcu_free_pool(struct rcu_head *rcu) |
226223ab | 3213 | { |
6ba94429 | 3214 | struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); |
226223ab | 3215 | |
6ba94429 FW |
3216 | ida_destroy(&pool->worker_ida); |
3217 | free_workqueue_attrs(pool->attrs); | |
3218 | kfree(pool); | |
226223ab TH |
3219 | } |
3220 | ||
6ba94429 FW |
3221 | /** |
3222 | * put_unbound_pool - put a worker_pool | |
3223 | * @pool: worker_pool to put | |
3224 | * | |
3225 | * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU | |
3226 | * safe manner. get_unbound_pool() calls this function on its failure path | |
3227 | * and this function should be able to release pools which went through, | |
3228 | * successfully or not, init_worker_pool(). | |
3229 | * | |
3230 | * Should be called with wq_pool_mutex held. | |
3231 | */ | |
3232 | static void put_unbound_pool(struct worker_pool *pool) | |
226223ab | 3233 | { |
6ba94429 FW |
3234 | DECLARE_COMPLETION_ONSTACK(detach_completion); |
3235 | struct worker *worker; | |
226223ab | 3236 | |
6ba94429 | 3237 | lockdep_assert_held(&wq_pool_mutex); |
226223ab | 3238 | |
6ba94429 FW |
3239 | if (--pool->refcnt) |
3240 | return; | |
226223ab | 3241 | |
6ba94429 FW |
3242 | /* sanity checks */ |
3243 | if (WARN_ON(!(pool->cpu < 0)) || | |
3244 | WARN_ON(!list_empty(&pool->worklist))) | |
3245 | return; | |
226223ab | 3246 | |
6ba94429 FW |
3247 | /* release id and unhash */ |
3248 | if (pool->id >= 0) | |
3249 | idr_remove(&worker_pool_idr, pool->id); | |
3250 | hash_del(&pool->hash_node); | |
d55262c4 | 3251 | |
6ba94429 FW |
3252 | /* |
3253 | * Become the manager and destroy all workers. Grabbing | |
3254 | * manager_arb prevents @pool's workers from blocking on | |
3255 | * attach_mutex. | |
3256 | */ | |
3257 | mutex_lock(&pool->manager_arb); | |
d55262c4 | 3258 | |
6ba94429 FW |
3259 | spin_lock_irq(&pool->lock); |
3260 | while ((worker = first_idle_worker(pool))) | |
3261 | destroy_worker(worker); | |
3262 | WARN_ON(pool->nr_workers || pool->nr_idle); | |
3263 | spin_unlock_irq(&pool->lock); | |
d55262c4 | 3264 | |
6ba94429 FW |
3265 | mutex_lock(&pool->attach_mutex); |
3266 | if (!list_empty(&pool->workers)) | |
3267 | pool->detach_completion = &detach_completion; | |
3268 | mutex_unlock(&pool->attach_mutex); | |
226223ab | 3269 | |
6ba94429 FW |
3270 | if (pool->detach_completion) |
3271 | wait_for_completion(pool->detach_completion); | |
226223ab | 3272 | |
6ba94429 | 3273 | mutex_unlock(&pool->manager_arb); |
226223ab | 3274 | |
6ba94429 FW |
3275 | /* shut down the timers */ |
3276 | del_timer_sync(&pool->idle_timer); | |
3277 | del_timer_sync(&pool->mayday_timer); | |
226223ab | 3278 | |
6ba94429 FW |
3279 | /* sched-RCU protected to allow dereferences from get_work_pool() */ |
3280 | call_rcu_sched(&pool->rcu, rcu_free_pool); | |
226223ab TH |
3281 | } |
3282 | ||
3283 | /** | |
6ba94429 FW |
3284 | * get_unbound_pool - get a worker_pool with the specified attributes |
3285 | * @attrs: the attributes of the worker_pool to get | |
226223ab | 3286 | * |
6ba94429 FW |
3287 | * Obtain a worker_pool which has the same attributes as @attrs, bump the |
3288 | * reference count and return it. If there already is a matching | |
3289 | * worker_pool, it will be used; otherwise, this function attempts to | |
3290 | * create a new one. | |
226223ab | 3291 | * |
6ba94429 | 3292 | * Should be called with wq_pool_mutex held. |
226223ab | 3293 | * |
6ba94429 FW |
3294 | * Return: On success, a worker_pool with the same attributes as @attrs. |
3295 | * On failure, %NULL. | |
226223ab | 3296 | */ |
6ba94429 | 3297 | static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) |
226223ab | 3298 | { |
6ba94429 FW |
3299 | u32 hash = wqattrs_hash(attrs); |
3300 | struct worker_pool *pool; | |
3301 | int node; | |
e2273584 | 3302 | int target_node = NUMA_NO_NODE; |
226223ab | 3303 | |
6ba94429 | 3304 | lockdep_assert_held(&wq_pool_mutex); |
226223ab | 3305 | |
6ba94429 FW |
3306 | /* do we already have a matching pool? */ |
3307 | hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { | |
3308 | if (wqattrs_equal(pool->attrs, attrs)) { | |
3309 | pool->refcnt++; | |
3310 | return pool; | |
3311 | } | |
3312 | } | |
226223ab | 3313 | |
e2273584 XP |
3314 | /* if cpumask is contained inside a NUMA node, we belong to that node */ |
3315 | if (wq_numa_enabled) { | |
3316 | for_each_node(node) { | |
3317 | if (cpumask_subset(attrs->cpumask, | |
3318 | wq_numa_possible_cpumask[node])) { | |
3319 | target_node = node; | |
3320 | break; | |
3321 | } | |
3322 | } | |
3323 | } | |
3324 | ||
6ba94429 | 3325 | /* nope, create a new one */ |
e2273584 | 3326 | pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, target_node); |
6ba94429 FW |
3327 | if (!pool || init_worker_pool(pool) < 0) |
3328 | goto fail; | |
3329 | ||
3330 | lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ | |
3331 | copy_workqueue_attrs(pool->attrs, attrs); | |
e2273584 | 3332 | pool->node = target_node; |
226223ab TH |
3333 | |
3334 | /* | |
6ba94429 FW |
3335 | * no_numa isn't a worker_pool attribute, always clear it. See |
3336 | * 'struct workqueue_attrs' comments for detail. | |
226223ab | 3337 | */ |
6ba94429 | 3338 | pool->attrs->no_numa = false; |
226223ab | 3339 | |
6ba94429 FW |
3340 | if (worker_pool_assign_id(pool) < 0) |
3341 | goto fail; | |
226223ab | 3342 | |
6ba94429 FW |
3343 | /* create and start the initial worker */ |
3344 | if (!create_worker(pool)) | |
3345 | goto fail; | |
226223ab | 3346 | |
6ba94429 FW |
3347 | /* install */ |
3348 | hash_add(unbound_pool_hash, &pool->hash_node, hash); | |
226223ab | 3349 | |
6ba94429 FW |
3350 | return pool; |
3351 | fail: | |
3352 | if (pool) | |
3353 | put_unbound_pool(pool); | |
3354 | return NULL; | |
226223ab | 3355 | } |
226223ab | 3356 | |
6ba94429 | 3357 | static void rcu_free_pwq(struct rcu_head *rcu) |
7a4e344c | 3358 | { |
6ba94429 FW |
3359 | kmem_cache_free(pwq_cache, |
3360 | container_of(rcu, struct pool_workqueue, rcu)); | |
7a4e344c TH |
3361 | } |
3362 | ||
6ba94429 FW |
3363 | /* |
3364 | * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt | |
3365 | * and needs to be destroyed. | |
7a4e344c | 3366 | */ |
6ba94429 | 3367 | static void pwq_unbound_release_workfn(struct work_struct *work) |
7a4e344c | 3368 | { |
6ba94429 FW |
3369 | struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, |
3370 | unbound_release_work); | |
3371 | struct workqueue_struct *wq = pwq->wq; | |
3372 | struct worker_pool *pool = pwq->pool; | |
3373 | bool is_last; | |
7a4e344c | 3374 | |
6ba94429 FW |
3375 | if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) |
3376 | return; | |
7a4e344c | 3377 | |
6ba94429 FW |
3378 | mutex_lock(&wq->mutex); |
3379 | list_del_rcu(&pwq->pwqs_node); | |
3380 | is_last = list_empty(&wq->pwqs); | |
3381 | mutex_unlock(&wq->mutex); | |
3382 | ||
3383 | mutex_lock(&wq_pool_mutex); | |
3384 | put_unbound_pool(pool); | |
3385 | mutex_unlock(&wq_pool_mutex); | |
3386 | ||
3387 | call_rcu_sched(&pwq->rcu, rcu_free_pwq); | |
7a4e344c | 3388 | |
2865a8fb | 3389 | /* |
6ba94429 FW |
3390 | * If we're the last pwq going away, @wq is already dead and no one |
3391 | * is gonna access it anymore. Schedule RCU free. | |
2865a8fb | 3392 | */ |
6ba94429 FW |
3393 | if (is_last) |
3394 | call_rcu_sched(&wq->rcu, rcu_free_wq); | |
29c91e99 TH |
3395 | } |
3396 | ||
7a4e344c | 3397 | /** |
6ba94429 FW |
3398 | * pwq_adjust_max_active - update a pwq's max_active to the current setting |
3399 | * @pwq: target pool_workqueue | |
d185af30 | 3400 | * |
6ba94429 FW |
3401 | * If @pwq isn't freezing, set @pwq->max_active to the associated |
3402 | * workqueue's saved_max_active and activate delayed work items | |
3403 | * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. | |
7a4e344c | 3404 | */ |
6ba94429 | 3405 | static void pwq_adjust_max_active(struct pool_workqueue *pwq) |
4e1a1f9a | 3406 | { |
6ba94429 FW |
3407 | struct workqueue_struct *wq = pwq->wq; |
3408 | bool freezable = wq->flags & WQ_FREEZABLE; | |
4e1a1f9a | 3409 | |
6ba94429 FW |
3410 | /* for @wq->saved_max_active */ |
3411 | lockdep_assert_held(&wq->mutex); | |
4e1a1f9a | 3412 | |
6ba94429 FW |
3413 | /* fast exit for non-freezable wqs */ |
3414 | if (!freezable && pwq->max_active == wq->saved_max_active) | |
3415 | return; | |
7a4e344c | 3416 | |
6ba94429 | 3417 | spin_lock_irq(&pwq->pool->lock); |
29c91e99 | 3418 | |
6ba94429 FW |
3419 | /* |
3420 | * During [un]freezing, the caller is responsible for ensuring that | |
3421 | * this function is called at least once after @workqueue_freezing | |
3422 | * is updated and visible. | |
3423 | */ | |
3424 | if (!freezable || !workqueue_freezing) { | |
3425 | pwq->max_active = wq->saved_max_active; | |
4e1a1f9a | 3426 | |
6ba94429 FW |
3427 | while (!list_empty(&pwq->delayed_works) && |
3428 | pwq->nr_active < pwq->max_active) | |
3429 | pwq_activate_first_delayed(pwq); | |
e2dca7ad | 3430 | |
6ba94429 FW |
3431 | /* |
3432 | * Need to kick a worker after thawed or an unbound wq's | |
3433 | * max_active is bumped. It's a slow path. Do it always. | |
3434 | */ | |
3435 | wake_up_worker(pwq->pool); | |
3436 | } else { | |
3437 | pwq->max_active = 0; | |
3438 | } | |
e2dca7ad | 3439 | |
6ba94429 | 3440 | spin_unlock_irq(&pwq->pool->lock); |
e2dca7ad TH |
3441 | } |
3442 | ||
6ba94429 FW |
3443 | /* initialize newly alloced @pwq which is associated with @wq and @pool */ |
3444 | static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, | |
3445 | struct worker_pool *pool) | |
29c91e99 | 3446 | { |
6ba94429 | 3447 | BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); |
29c91e99 | 3448 | |
6ba94429 FW |
3449 | memset(pwq, 0, sizeof(*pwq)); |
3450 | ||
3451 | pwq->pool = pool; | |
3452 | pwq->wq = wq; | |
3453 | pwq->flush_color = -1; | |
3454 | pwq->refcnt = 1; | |
3455 | INIT_LIST_HEAD(&pwq->delayed_works); | |
3456 | INIT_LIST_HEAD(&pwq->pwqs_node); | |
3457 | INIT_LIST_HEAD(&pwq->mayday_node); | |
3458 | INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); | |
29c91e99 TH |
3459 | } |
3460 | ||
6ba94429 FW |
3461 | /* sync @pwq with the current state of its associated wq and link it */ |
3462 | static void link_pwq(struct pool_workqueue *pwq) | |
29c91e99 | 3463 | { |
6ba94429 | 3464 | struct workqueue_struct *wq = pwq->wq; |
29c91e99 | 3465 | |
6ba94429 | 3466 | lockdep_assert_held(&wq->mutex); |
a892cacc | 3467 | |
6ba94429 FW |
3468 | /* may be called multiple times, ignore if already linked */ |
3469 | if (!list_empty(&pwq->pwqs_node)) | |
29c91e99 | 3470 | return; |
29c91e99 | 3471 | |
6ba94429 FW |
3472 | /* set the matching work_color */ |
3473 | pwq->work_color = wq->work_color; | |
29c91e99 | 3474 | |
6ba94429 FW |
3475 | /* sync max_active to the current setting */ |
3476 | pwq_adjust_max_active(pwq); | |
29c91e99 | 3477 | |
6ba94429 FW |
3478 | /* link in @pwq */ |
3479 | list_add_rcu(&pwq->pwqs_node, &wq->pwqs); | |
3480 | } | |
29c91e99 | 3481 | |
6ba94429 FW |
3482 | /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ |
3483 | static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, | |
3484 | const struct workqueue_attrs *attrs) | |
3485 | { | |
3486 | struct worker_pool *pool; | |
3487 | struct pool_workqueue *pwq; | |
60f5a4bc | 3488 | |
6ba94429 | 3489 | lockdep_assert_held(&wq_pool_mutex); |
60f5a4bc | 3490 | |
6ba94429 FW |
3491 | pool = get_unbound_pool(attrs); |
3492 | if (!pool) | |
3493 | return NULL; | |
60f5a4bc | 3494 | |
6ba94429 FW |
3495 | pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); |
3496 | if (!pwq) { | |
3497 | put_unbound_pool(pool); | |
3498 | return NULL; | |
3499 | } | |
29c91e99 | 3500 | |
6ba94429 FW |
3501 | init_pwq(pwq, wq, pool); |
3502 | return pwq; | |
3503 | } | |
29c91e99 | 3504 | |
29c91e99 | 3505 | /** |
30186c6f | 3506 | * wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node |
042f7df1 | 3507 | * @attrs: the wq_attrs of the default pwq of the target workqueue |
6ba94429 FW |
3508 | * @node: the target NUMA node |
3509 | * @cpu_going_down: if >= 0, the CPU to consider as offline | |
3510 | * @cpumask: outarg, the resulting cpumask | |
29c91e99 | 3511 | * |
6ba94429 FW |
3512 | * Calculate the cpumask a workqueue with @attrs should use on @node. If |
3513 | * @cpu_going_down is >= 0, that cpu is considered offline during | |
3514 | * calculation. The result is stored in @cpumask. | |
a892cacc | 3515 | * |
6ba94429 FW |
3516 | * If NUMA affinity is not enabled, @attrs->cpumask is always used. If |
3517 | * enabled and @node has online CPUs requested by @attrs, the returned | |
3518 | * cpumask is the intersection of the possible CPUs of @node and | |
3519 | * @attrs->cpumask. | |
d185af30 | 3520 | * |
6ba94429 FW |
3521 | * The caller is responsible for ensuring that the cpumask of @node stays |
3522 | * stable. | |
3523 | * | |
3524 | * Return: %true if the resulting @cpumask is different from @attrs->cpumask, | |
3525 | * %false if equal. | |
29c91e99 | 3526 | */ |
6ba94429 FW |
3527 | static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, |
3528 | int cpu_going_down, cpumask_t *cpumask) | |
29c91e99 | 3529 | { |
6ba94429 FW |
3530 | if (!wq_numa_enabled || attrs->no_numa) |
3531 | goto use_dfl; | |
29c91e99 | 3532 | |
6ba94429 FW |
3533 | /* does @node have any online CPUs @attrs wants? */ |
3534 | cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); | |
3535 | if (cpu_going_down >= 0) | |
3536 | cpumask_clear_cpu(cpu_going_down, cpumask); | |
29c91e99 | 3537 | |
6ba94429 FW |
3538 | if (cpumask_empty(cpumask)) |
3539 | goto use_dfl; | |
4c16bd32 TH |
3540 | |
3541 | /* yeap, return possible CPUs in @node that @attrs wants */ | |
3542 | cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); | |
3543 | return !cpumask_equal(cpumask, attrs->cpumask); | |
3544 | ||
3545 | use_dfl: | |
3546 | cpumask_copy(cpumask, attrs->cpumask); | |
3547 | return false; | |
3548 | } | |
3549 | ||
1befcf30 TH |
3550 | /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ |
3551 | static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, | |
3552 | int node, | |
3553 | struct pool_workqueue *pwq) | |
3554 | { | |
3555 | struct pool_workqueue *old_pwq; | |
3556 | ||
5b95e1af | 3557 | lockdep_assert_held(&wq_pool_mutex); |
1befcf30 TH |
3558 | lockdep_assert_held(&wq->mutex); |
3559 | ||
3560 | /* link_pwq() can handle duplicate calls */ | |
3561 | link_pwq(pwq); | |
3562 | ||
3563 | old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); | |
3564 | rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); | |
3565 | return old_pwq; | |
3566 | } | |
3567 | ||
2d5f0764 LJ |
3568 | /* context to store the prepared attrs & pwqs before applying */ |
3569 | struct apply_wqattrs_ctx { | |
3570 | struct workqueue_struct *wq; /* target workqueue */ | |
3571 | struct workqueue_attrs *attrs; /* attrs to apply */ | |
042f7df1 | 3572 | struct list_head list; /* queued for batching commit */ |
2d5f0764 LJ |
3573 | struct pool_workqueue *dfl_pwq; |
3574 | struct pool_workqueue *pwq_tbl[]; | |
3575 | }; | |
3576 | ||
3577 | /* free the resources after success or abort */ | |
3578 | static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) | |
3579 | { | |
3580 | if (ctx) { | |
3581 | int node; | |
3582 | ||
3583 | for_each_node(node) | |
3584 | put_pwq_unlocked(ctx->pwq_tbl[node]); | |
3585 | put_pwq_unlocked(ctx->dfl_pwq); | |
3586 | ||
3587 | free_workqueue_attrs(ctx->attrs); | |
3588 | ||
3589 | kfree(ctx); | |
3590 | } | |
3591 | } | |
3592 | ||
3593 | /* allocate the attrs and pwqs for later installation */ | |
3594 | static struct apply_wqattrs_ctx * | |
3595 | apply_wqattrs_prepare(struct workqueue_struct *wq, | |
3596 | const struct workqueue_attrs *attrs) | |
9e8cd2f5 | 3597 | { |
2d5f0764 | 3598 | struct apply_wqattrs_ctx *ctx; |
4c16bd32 | 3599 | struct workqueue_attrs *new_attrs, *tmp_attrs; |
2d5f0764 | 3600 | int node; |
9e8cd2f5 | 3601 | |
2d5f0764 | 3602 | lockdep_assert_held(&wq_pool_mutex); |
9e8cd2f5 | 3603 | |
2d5f0764 LJ |
3604 | ctx = kzalloc(sizeof(*ctx) + nr_node_ids * sizeof(ctx->pwq_tbl[0]), |
3605 | GFP_KERNEL); | |
8719dcea | 3606 | |
13e2e556 | 3607 | new_attrs = alloc_workqueue_attrs(GFP_KERNEL); |
4c16bd32 | 3608 | tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL); |
2d5f0764 LJ |
3609 | if (!ctx || !new_attrs || !tmp_attrs) |
3610 | goto out_free; | |
13e2e556 | 3611 | |
042f7df1 LJ |
3612 | /* |
3613 | * Calculate the attrs of the default pwq. | |
3614 | * If the user configured cpumask doesn't overlap with the | |
3615 | * wq_unbound_cpumask, we fallback to the wq_unbound_cpumask. | |
3616 | */ | |
13e2e556 | 3617 | copy_workqueue_attrs(new_attrs, attrs); |
b05a7928 | 3618 | cpumask_and(new_attrs->cpumask, new_attrs->cpumask, wq_unbound_cpumask); |
042f7df1 LJ |
3619 | if (unlikely(cpumask_empty(new_attrs->cpumask))) |
3620 | cpumask_copy(new_attrs->cpumask, wq_unbound_cpumask); | |
13e2e556 | 3621 | |
4c16bd32 TH |
3622 | /* |
3623 | * We may create multiple pwqs with differing cpumasks. Make a | |
3624 | * copy of @new_attrs which will be modified and used to obtain | |
3625 | * pools. | |
3626 | */ | |
3627 | copy_workqueue_attrs(tmp_attrs, new_attrs); | |
3628 | ||
4c16bd32 TH |
3629 | /* |
3630 | * If something goes wrong during CPU up/down, we'll fall back to | |
3631 | * the default pwq covering whole @attrs->cpumask. Always create | |
3632 | * it even if we don't use it immediately. | |
3633 | */ | |
2d5f0764 LJ |
3634 | ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs); |
3635 | if (!ctx->dfl_pwq) | |
3636 | goto out_free; | |
4c16bd32 TH |
3637 | |
3638 | for_each_node(node) { | |
042f7df1 | 3639 | if (wq_calc_node_cpumask(new_attrs, node, -1, tmp_attrs->cpumask)) { |
2d5f0764 LJ |
3640 | ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); |
3641 | if (!ctx->pwq_tbl[node]) | |
3642 | goto out_free; | |
4c16bd32 | 3643 | } else { |
2d5f0764 LJ |
3644 | ctx->dfl_pwq->refcnt++; |
3645 | ctx->pwq_tbl[node] = ctx->dfl_pwq; | |
4c16bd32 TH |
3646 | } |
3647 | } | |
3648 | ||
042f7df1 LJ |
3649 | /* save the user configured attrs and sanitize it. */ |
3650 | copy_workqueue_attrs(new_attrs, attrs); | |
3651 | cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); | |
2d5f0764 | 3652 | ctx->attrs = new_attrs; |
042f7df1 | 3653 | |
2d5f0764 LJ |
3654 | ctx->wq = wq; |
3655 | free_workqueue_attrs(tmp_attrs); | |
3656 | return ctx; | |
3657 | ||
3658 | out_free: | |
3659 | free_workqueue_attrs(tmp_attrs); | |
3660 | free_workqueue_attrs(new_attrs); | |
3661 | apply_wqattrs_cleanup(ctx); | |
3662 | return NULL; | |
3663 | } | |
3664 | ||
3665 | /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ | |
3666 | static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) | |
3667 | { | |
3668 | int node; | |
9e8cd2f5 | 3669 | |
4c16bd32 | 3670 | /* all pwqs have been created successfully, let's install'em */ |
2d5f0764 | 3671 | mutex_lock(&ctx->wq->mutex); |
a892cacc | 3672 | |
2d5f0764 | 3673 | copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs); |
4c16bd32 TH |
3674 | |
3675 | /* save the previous pwq and install the new one */ | |
f147f29e | 3676 | for_each_node(node) |
2d5f0764 LJ |
3677 | ctx->pwq_tbl[node] = numa_pwq_tbl_install(ctx->wq, node, |
3678 | ctx->pwq_tbl[node]); | |
4c16bd32 TH |
3679 | |
3680 | /* @dfl_pwq might not have been used, ensure it's linked */ | |
2d5f0764 LJ |
3681 | link_pwq(ctx->dfl_pwq); |
3682 | swap(ctx->wq->dfl_pwq, ctx->dfl_pwq); | |
f147f29e | 3683 | |
2d5f0764 LJ |
3684 | mutex_unlock(&ctx->wq->mutex); |
3685 | } | |
9e8cd2f5 | 3686 | |
a0111cf6 LJ |
3687 | static void apply_wqattrs_lock(void) |
3688 | { | |
3689 | /* CPUs should stay stable across pwq creations and installations */ | |
3690 | get_online_cpus(); | |
3691 | mutex_lock(&wq_pool_mutex); | |
3692 | } | |
3693 | ||
3694 | static void apply_wqattrs_unlock(void) | |
3695 | { | |
3696 | mutex_unlock(&wq_pool_mutex); | |
3697 | put_online_cpus(); | |
3698 | } | |
3699 | ||
3700 | static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, | |
3701 | const struct workqueue_attrs *attrs) | |
2d5f0764 LJ |
3702 | { |
3703 | struct apply_wqattrs_ctx *ctx; | |
4c16bd32 | 3704 | |
2d5f0764 LJ |
3705 | /* only unbound workqueues can change attributes */ |
3706 | if (WARN_ON(!(wq->flags & WQ_UNBOUND))) | |
3707 | return -EINVAL; | |
13e2e556 | 3708 | |
2d5f0764 LJ |
3709 | /* creating multiple pwqs breaks ordering guarantee */ |
3710 | if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))) | |
3711 | return -EINVAL; | |
3712 | ||
2d5f0764 | 3713 | ctx = apply_wqattrs_prepare(wq, attrs); |
6201171e | 3714 | if (!ctx) |
3715 | return -ENOMEM; | |
2d5f0764 LJ |
3716 | |
3717 | /* the ctx has been prepared successfully, let's commit it */ | |
6201171e | 3718 | apply_wqattrs_commit(ctx); |
2d5f0764 LJ |
3719 | apply_wqattrs_cleanup(ctx); |
3720 | ||
6201171e | 3721 | return 0; |
9e8cd2f5 TH |
3722 | } |
3723 | ||
a0111cf6 LJ |
3724 | /** |
3725 | * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue | |
3726 | * @wq: the target workqueue | |
3727 | * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() | |
3728 | * | |
3729 | * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA | |
3730 | * machines, this function maps a separate pwq to each NUMA node with | |
3731 | * possibles CPUs in @attrs->cpumask so that work items are affine to the | |
3732 | * NUMA node it was issued on. Older pwqs are released as in-flight work | |
3733 | * items finish. Note that a work item which repeatedly requeues itself | |
3734 | * back-to-back will stay on its current pwq. | |
3735 | * | |
3736 | * Performs GFP_KERNEL allocations. | |
3737 | * | |
3738 | * Return: 0 on success and -errno on failure. | |
3739 | */ | |
3740 | int apply_workqueue_attrs(struct workqueue_struct *wq, | |
3741 | const struct workqueue_attrs *attrs) | |
3742 | { | |
3743 | int ret; | |
3744 | ||
3745 | apply_wqattrs_lock(); | |
3746 | ret = apply_workqueue_attrs_locked(wq, attrs); | |
3747 | apply_wqattrs_unlock(); | |
3748 | ||
3749 | return ret; | |
3750 | } | |
3751 | ||
4c16bd32 TH |
3752 | /** |
3753 | * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug | |
3754 | * @wq: the target workqueue | |
3755 | * @cpu: the CPU coming up or going down | |
3756 | * @online: whether @cpu is coming up or going down | |
3757 | * | |
3758 | * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and | |
3759 | * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of | |
3760 | * @wq accordingly. | |
3761 | * | |
3762 | * If NUMA affinity can't be adjusted due to memory allocation failure, it | |
3763 | * falls back to @wq->dfl_pwq which may not be optimal but is always | |
3764 | * correct. | |
3765 | * | |
3766 | * Note that when the last allowed CPU of a NUMA node goes offline for a | |
3767 | * workqueue with a cpumask spanning multiple nodes, the workers which were | |
3768 | * already executing the work items for the workqueue will lose their CPU | |
3769 | * affinity and may execute on any CPU. This is similar to how per-cpu | |
3770 | * workqueues behave on CPU_DOWN. If a workqueue user wants strict | |
3771 | * affinity, it's the user's responsibility to flush the work item from | |
3772 | * CPU_DOWN_PREPARE. | |
3773 | */ | |
3774 | static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, | |
3775 | bool online) | |
3776 | { | |
3777 | int node = cpu_to_node(cpu); | |
3778 | int cpu_off = online ? -1 : cpu; | |
3779 | struct pool_workqueue *old_pwq = NULL, *pwq; | |
3780 | struct workqueue_attrs *target_attrs; | |
3781 | cpumask_t *cpumask; | |
3782 | ||
3783 | lockdep_assert_held(&wq_pool_mutex); | |
3784 | ||
f7142ed4 LJ |
3785 | if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND) || |
3786 | wq->unbound_attrs->no_numa) | |
4c16bd32 TH |
3787 | return; |
3788 | ||
3789 | /* | |
3790 | * We don't wanna alloc/free wq_attrs for each wq for each CPU. | |
3791 | * Let's use a preallocated one. The following buf is protected by | |
3792 | * CPU hotplug exclusion. | |
3793 | */ | |
3794 | target_attrs = wq_update_unbound_numa_attrs_buf; | |
3795 | cpumask = target_attrs->cpumask; | |
3796 | ||
4c16bd32 TH |
3797 | copy_workqueue_attrs(target_attrs, wq->unbound_attrs); |
3798 | pwq = unbound_pwq_by_node(wq, node); | |
3799 | ||
3800 | /* | |
3801 | * Let's determine what needs to be done. If the target cpumask is | |
042f7df1 LJ |
3802 | * different from the default pwq's, we need to compare it to @pwq's |
3803 | * and create a new one if they don't match. If the target cpumask | |
3804 | * equals the default pwq's, the default pwq should be used. | |
4c16bd32 | 3805 | */ |
042f7df1 | 3806 | if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) { |
4c16bd32 | 3807 | if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) |
f7142ed4 | 3808 | return; |
4c16bd32 | 3809 | } else { |
534a3fbb | 3810 | goto use_dfl_pwq; |
4c16bd32 TH |
3811 | } |
3812 | ||
4c16bd32 TH |
3813 | /* create a new pwq */ |
3814 | pwq = alloc_unbound_pwq(wq, target_attrs); | |
3815 | if (!pwq) { | |
2d916033 FF |
3816 | pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", |
3817 | wq->name); | |
77f300b1 | 3818 | goto use_dfl_pwq; |
4c16bd32 TH |
3819 | } |
3820 | ||
f7142ed4 | 3821 | /* Install the new pwq. */ |
4c16bd32 TH |
3822 | mutex_lock(&wq->mutex); |
3823 | old_pwq = numa_pwq_tbl_install(wq, node, pwq); | |
3824 | goto out_unlock; | |
3825 | ||
3826 | use_dfl_pwq: | |
f7142ed4 | 3827 | mutex_lock(&wq->mutex); |
4c16bd32 TH |
3828 | spin_lock_irq(&wq->dfl_pwq->pool->lock); |
3829 | get_pwq(wq->dfl_pwq); | |
3830 | spin_unlock_irq(&wq->dfl_pwq->pool->lock); | |
3831 | old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); | |
3832 | out_unlock: | |
3833 | mutex_unlock(&wq->mutex); | |
3834 | put_pwq_unlocked(old_pwq); | |
3835 | } | |
3836 | ||
30cdf249 | 3837 | static int alloc_and_link_pwqs(struct workqueue_struct *wq) |
0f900049 | 3838 | { |
49e3cf44 | 3839 | bool highpri = wq->flags & WQ_HIGHPRI; |
8a2b7538 | 3840 | int cpu, ret; |
30cdf249 TH |
3841 | |
3842 | if (!(wq->flags & WQ_UNBOUND)) { | |
420c0ddb TH |
3843 | wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); |
3844 | if (!wq->cpu_pwqs) | |
30cdf249 TH |
3845 | return -ENOMEM; |
3846 | ||
3847 | for_each_possible_cpu(cpu) { | |
7fb98ea7 TH |
3848 | struct pool_workqueue *pwq = |
3849 | per_cpu_ptr(wq->cpu_pwqs, cpu); | |
7a62c2c8 | 3850 | struct worker_pool *cpu_pools = |
f02ae73a | 3851 | per_cpu(cpu_worker_pools, cpu); |
f3421797 | 3852 | |
f147f29e TH |
3853 | init_pwq(pwq, wq, &cpu_pools[highpri]); |
3854 | ||
3855 | mutex_lock(&wq->mutex); | |
1befcf30 | 3856 | link_pwq(pwq); |
f147f29e | 3857 | mutex_unlock(&wq->mutex); |
30cdf249 | 3858 | } |
9e8cd2f5 | 3859 | return 0; |
8a2b7538 TH |
3860 | } else if (wq->flags & __WQ_ORDERED) { |
3861 | ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); | |
3862 | /* there should only be single pwq for ordering guarantee */ | |
3863 | WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || | |
3864 | wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), | |
3865 | "ordering guarantee broken for workqueue %s\n", wq->name); | |
3866 | return ret; | |
30cdf249 | 3867 | } else { |
9e8cd2f5 | 3868 | return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); |
30cdf249 | 3869 | } |
0f900049 TH |
3870 | } |
3871 | ||
f3421797 TH |
3872 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
3873 | const char *name) | |
b71ab8c2 | 3874 | { |
f3421797 TH |
3875 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
3876 | ||
3877 | if (max_active < 1 || max_active > lim) | |
044c782c VI |
3878 | pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", |
3879 | max_active, name, 1, lim); | |
b71ab8c2 | 3880 | |
f3421797 | 3881 | return clamp_val(max_active, 1, lim); |
b71ab8c2 TH |
3882 | } |
3883 | ||
b196be89 | 3884 | struct workqueue_struct *__alloc_workqueue_key(const char *fmt, |
d320c038 TH |
3885 | unsigned int flags, |
3886 | int max_active, | |
3887 | struct lock_class_key *key, | |
b196be89 | 3888 | const char *lock_name, ...) |
1da177e4 | 3889 | { |
df2d5ae4 | 3890 | size_t tbl_size = 0; |
ecf6881f | 3891 | va_list args; |
1da177e4 | 3892 | struct workqueue_struct *wq; |
49e3cf44 | 3893 | struct pool_workqueue *pwq; |
b196be89 | 3894 | |
cee22a15 VK |
3895 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ |
3896 | if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) | |
3897 | flags |= WQ_UNBOUND; | |
3898 | ||
ecf6881f | 3899 | /* allocate wq and format name */ |
df2d5ae4 | 3900 | if (flags & WQ_UNBOUND) |
ddcb57e2 | 3901 | tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]); |
df2d5ae4 TH |
3902 | |
3903 | wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); | |
b196be89 | 3904 | if (!wq) |
d2c1d404 | 3905 | return NULL; |
b196be89 | 3906 | |
6029a918 TH |
3907 | if (flags & WQ_UNBOUND) { |
3908 | wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL); | |
3909 | if (!wq->unbound_attrs) | |
3910 | goto err_free_wq; | |
3911 | } | |
3912 | ||
ecf6881f TH |
3913 | va_start(args, lock_name); |
3914 | vsnprintf(wq->name, sizeof(wq->name), fmt, args); | |
b196be89 | 3915 | va_end(args); |
1da177e4 | 3916 | |
d320c038 | 3917 | max_active = max_active ?: WQ_DFL_ACTIVE; |
b196be89 | 3918 | max_active = wq_clamp_max_active(max_active, flags, wq->name); |
3af24433 | 3919 | |
b196be89 | 3920 | /* init wq */ |
97e37d7b | 3921 | wq->flags = flags; |
a0a1a5fd | 3922 | wq->saved_max_active = max_active; |
3c25a55d | 3923 | mutex_init(&wq->mutex); |
112202d9 | 3924 | atomic_set(&wq->nr_pwqs_to_flush, 0); |
30cdf249 | 3925 | INIT_LIST_HEAD(&wq->pwqs); |
73f53c4a TH |
3926 | INIT_LIST_HEAD(&wq->flusher_queue); |
3927 | INIT_LIST_HEAD(&wq->flusher_overflow); | |
493a1724 | 3928 | INIT_LIST_HEAD(&wq->maydays); |
502ca9d8 | 3929 | |
eb13ba87 | 3930 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
cce1a165 | 3931 | INIT_LIST_HEAD(&wq->list); |
3af24433 | 3932 | |
30cdf249 | 3933 | if (alloc_and_link_pwqs(wq) < 0) |
d2c1d404 | 3934 | goto err_free_wq; |
1537663f | 3935 | |
493008a8 TH |
3936 | /* |
3937 | * Workqueues which may be used during memory reclaim should | |
3938 | * have a rescuer to guarantee forward progress. | |
3939 | */ | |
3940 | if (flags & WQ_MEM_RECLAIM) { | |
e22bee78 TH |
3941 | struct worker *rescuer; |
3942 | ||
f7537df5 | 3943 | rescuer = alloc_worker(NUMA_NO_NODE); |
e22bee78 | 3944 | if (!rescuer) |
d2c1d404 | 3945 | goto err_destroy; |
e22bee78 | 3946 | |
111c225a TH |
3947 | rescuer->rescue_wq = wq; |
3948 | rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", | |
b196be89 | 3949 | wq->name); |
d2c1d404 TH |
3950 | if (IS_ERR(rescuer->task)) { |
3951 | kfree(rescuer); | |
3952 | goto err_destroy; | |
3953 | } | |
e22bee78 | 3954 | |
d2c1d404 | 3955 | wq->rescuer = rescuer; |
25834c73 | 3956 | kthread_bind_mask(rescuer->task, cpu_possible_mask); |
e22bee78 | 3957 | wake_up_process(rescuer->task); |
3af24433 ON |
3958 | } |
3959 | ||
226223ab TH |
3960 | if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) |
3961 | goto err_destroy; | |
3962 | ||
a0a1a5fd | 3963 | /* |
68e13a67 LJ |
3964 | * wq_pool_mutex protects global freeze state and workqueues list. |
3965 | * Grab it, adjust max_active and add the new @wq to workqueues | |
3966 | * list. | |
a0a1a5fd | 3967 | */ |
68e13a67 | 3968 | mutex_lock(&wq_pool_mutex); |
a0a1a5fd | 3969 | |
a357fc03 | 3970 | mutex_lock(&wq->mutex); |
699ce097 TH |
3971 | for_each_pwq(pwq, wq) |
3972 | pwq_adjust_max_active(pwq); | |
a357fc03 | 3973 | mutex_unlock(&wq->mutex); |
a0a1a5fd | 3974 | |
e2dca7ad | 3975 | list_add_tail_rcu(&wq->list, &workqueues); |
a0a1a5fd | 3976 | |
68e13a67 | 3977 | mutex_unlock(&wq_pool_mutex); |
1537663f | 3978 | |
3af24433 | 3979 | return wq; |
d2c1d404 TH |
3980 | |
3981 | err_free_wq: | |
6029a918 | 3982 | free_workqueue_attrs(wq->unbound_attrs); |
d2c1d404 TH |
3983 | kfree(wq); |
3984 | return NULL; | |
3985 | err_destroy: | |
3986 | destroy_workqueue(wq); | |
4690c4ab | 3987 | return NULL; |
3af24433 | 3988 | } |
d320c038 | 3989 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
1da177e4 | 3990 | |
3af24433 ON |
3991 | /** |
3992 | * destroy_workqueue - safely terminate a workqueue | |
3993 | * @wq: target workqueue | |
3994 | * | |
3995 | * Safely destroy a workqueue. All work currently pending will be done first. | |
3996 | */ | |
3997 | void destroy_workqueue(struct workqueue_struct *wq) | |
3998 | { | |
49e3cf44 | 3999 | struct pool_workqueue *pwq; |
4c16bd32 | 4000 | int node; |
3af24433 | 4001 | |
9c5a2ba7 TH |
4002 | /* drain it before proceeding with destruction */ |
4003 | drain_workqueue(wq); | |
c8efcc25 | 4004 | |
6183c009 | 4005 | /* sanity checks */ |
b09f4fd3 | 4006 | mutex_lock(&wq->mutex); |
49e3cf44 | 4007 | for_each_pwq(pwq, wq) { |
6183c009 TH |
4008 | int i; |
4009 | ||
76af4d93 TH |
4010 | for (i = 0; i < WORK_NR_COLORS; i++) { |
4011 | if (WARN_ON(pwq->nr_in_flight[i])) { | |
b09f4fd3 | 4012 | mutex_unlock(&wq->mutex); |
6183c009 | 4013 | return; |
76af4d93 TH |
4014 | } |
4015 | } | |
4016 | ||
5c529597 | 4017 | if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) || |
8864b4e5 | 4018 | WARN_ON(pwq->nr_active) || |
76af4d93 | 4019 | WARN_ON(!list_empty(&pwq->delayed_works))) { |
b09f4fd3 | 4020 | mutex_unlock(&wq->mutex); |
6183c009 | 4021 | return; |
76af4d93 | 4022 | } |
6183c009 | 4023 | } |
b09f4fd3 | 4024 | mutex_unlock(&wq->mutex); |
6183c009 | 4025 | |
a0a1a5fd TH |
4026 | /* |
4027 | * wq list is used to freeze wq, remove from list after | |
4028 | * flushing is complete in case freeze races us. | |
4029 | */ | |
68e13a67 | 4030 | mutex_lock(&wq_pool_mutex); |
e2dca7ad | 4031 | list_del_rcu(&wq->list); |
68e13a67 | 4032 | mutex_unlock(&wq_pool_mutex); |
3af24433 | 4033 | |
226223ab TH |
4034 | workqueue_sysfs_unregister(wq); |
4035 | ||
e2dca7ad | 4036 | if (wq->rescuer) |
e22bee78 | 4037 | kthread_stop(wq->rescuer->task); |
e22bee78 | 4038 | |
8864b4e5 TH |
4039 | if (!(wq->flags & WQ_UNBOUND)) { |
4040 | /* | |
4041 | * The base ref is never dropped on per-cpu pwqs. Directly | |
e2dca7ad | 4042 | * schedule RCU free. |
8864b4e5 | 4043 | */ |
e2dca7ad | 4044 | call_rcu_sched(&wq->rcu, rcu_free_wq); |
8864b4e5 TH |
4045 | } else { |
4046 | /* | |
4047 | * We're the sole accessor of @wq at this point. Directly | |
4c16bd32 TH |
4048 | * access numa_pwq_tbl[] and dfl_pwq to put the base refs. |
4049 | * @wq will be freed when the last pwq is released. | |
8864b4e5 | 4050 | */ |
4c16bd32 TH |
4051 | for_each_node(node) { |
4052 | pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); | |
4053 | RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); | |
4054 | put_pwq_unlocked(pwq); | |
4055 | } | |
4056 | ||
4057 | /* | |
4058 | * Put dfl_pwq. @wq may be freed any time after dfl_pwq is | |
4059 | * put. Don't access it afterwards. | |
4060 | */ | |
4061 | pwq = wq->dfl_pwq; | |
4062 | wq->dfl_pwq = NULL; | |
dce90d47 | 4063 | put_pwq_unlocked(pwq); |
29c91e99 | 4064 | } |
3af24433 ON |
4065 | } |
4066 | EXPORT_SYMBOL_GPL(destroy_workqueue); | |
4067 | ||
dcd989cb TH |
4068 | /** |
4069 | * workqueue_set_max_active - adjust max_active of a workqueue | |
4070 | * @wq: target workqueue | |
4071 | * @max_active: new max_active value. | |
4072 | * | |
4073 | * Set max_active of @wq to @max_active. | |
4074 | * | |
4075 | * CONTEXT: | |
4076 | * Don't call from IRQ context. | |
4077 | */ | |
4078 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) | |
4079 | { | |
49e3cf44 | 4080 | struct pool_workqueue *pwq; |
dcd989cb | 4081 | |
8719dcea TH |
4082 | /* disallow meddling with max_active for ordered workqueues */ |
4083 | if (WARN_ON(wq->flags & __WQ_ORDERED)) | |
4084 | return; | |
4085 | ||
f3421797 | 4086 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
dcd989cb | 4087 | |
a357fc03 | 4088 | mutex_lock(&wq->mutex); |
dcd989cb TH |
4089 | |
4090 | wq->saved_max_active = max_active; | |
4091 | ||
699ce097 TH |
4092 | for_each_pwq(pwq, wq) |
4093 | pwq_adjust_max_active(pwq); | |
93981800 | 4094 | |
a357fc03 | 4095 | mutex_unlock(&wq->mutex); |
15316ba8 | 4096 | } |
dcd989cb | 4097 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
15316ba8 | 4098 | |
e6267616 TH |
4099 | /** |
4100 | * current_is_workqueue_rescuer - is %current workqueue rescuer? | |
4101 | * | |
4102 | * Determine whether %current is a workqueue rescuer. Can be used from | |
4103 | * work functions to determine whether it's being run off the rescuer task. | |
d185af30 YB |
4104 | * |
4105 | * Return: %true if %current is a workqueue rescuer. %false otherwise. | |
e6267616 TH |
4106 | */ |
4107 | bool current_is_workqueue_rescuer(void) | |
4108 | { | |
4109 | struct worker *worker = current_wq_worker(); | |
4110 | ||
6a092dfd | 4111 | return worker && worker->rescue_wq; |
e6267616 TH |
4112 | } |
4113 | ||
eef6a7d5 | 4114 | /** |
dcd989cb TH |
4115 | * workqueue_congested - test whether a workqueue is congested |
4116 | * @cpu: CPU in question | |
4117 | * @wq: target workqueue | |
eef6a7d5 | 4118 | * |
dcd989cb TH |
4119 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
4120 | * no synchronization around this function and the test result is | |
4121 | * unreliable and only useful as advisory hints or for debugging. | |
eef6a7d5 | 4122 | * |
d3251859 TH |
4123 | * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. |
4124 | * Note that both per-cpu and unbound workqueues may be associated with | |
4125 | * multiple pool_workqueues which have separate congested states. A | |
4126 | * workqueue being congested on one CPU doesn't mean the workqueue is also | |
4127 | * contested on other CPUs / NUMA nodes. | |
4128 | * | |
d185af30 | 4129 | * Return: |
dcd989cb | 4130 | * %true if congested, %false otherwise. |
eef6a7d5 | 4131 | */ |
d84ff051 | 4132 | bool workqueue_congested(int cpu, struct workqueue_struct *wq) |
1da177e4 | 4133 | { |
7fb98ea7 | 4134 | struct pool_workqueue *pwq; |
76af4d93 TH |
4135 | bool ret; |
4136 | ||
88109453 | 4137 | rcu_read_lock_sched(); |
7fb98ea7 | 4138 | |
d3251859 TH |
4139 | if (cpu == WORK_CPU_UNBOUND) |
4140 | cpu = smp_processor_id(); | |
4141 | ||
7fb98ea7 TH |
4142 | if (!(wq->flags & WQ_UNBOUND)) |
4143 | pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); | |
4144 | else | |
df2d5ae4 | 4145 | pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); |
dcd989cb | 4146 | |
76af4d93 | 4147 | ret = !list_empty(&pwq->delayed_works); |
88109453 | 4148 | rcu_read_unlock_sched(); |
76af4d93 TH |
4149 | |
4150 | return ret; | |
1da177e4 | 4151 | } |
dcd989cb | 4152 | EXPORT_SYMBOL_GPL(workqueue_congested); |
1da177e4 | 4153 | |
dcd989cb TH |
4154 | /** |
4155 | * work_busy - test whether a work is currently pending or running | |
4156 | * @work: the work to be tested | |
4157 | * | |
4158 | * Test whether @work is currently pending or running. There is no | |
4159 | * synchronization around this function and the test result is | |
4160 | * unreliable and only useful as advisory hints or for debugging. | |
dcd989cb | 4161 | * |
d185af30 | 4162 | * Return: |
dcd989cb TH |
4163 | * OR'd bitmask of WORK_BUSY_* bits. |
4164 | */ | |
4165 | unsigned int work_busy(struct work_struct *work) | |
1da177e4 | 4166 | { |
fa1b54e6 | 4167 | struct worker_pool *pool; |
dcd989cb TH |
4168 | unsigned long flags; |
4169 | unsigned int ret = 0; | |
1da177e4 | 4170 | |
dcd989cb TH |
4171 | if (work_pending(work)) |
4172 | ret |= WORK_BUSY_PENDING; | |
1da177e4 | 4173 | |
fa1b54e6 TH |
4174 | local_irq_save(flags); |
4175 | pool = get_work_pool(work); | |
038366c5 | 4176 | if (pool) { |
fa1b54e6 | 4177 | spin_lock(&pool->lock); |
038366c5 LJ |
4178 | if (find_worker_executing_work(pool, work)) |
4179 | ret |= WORK_BUSY_RUNNING; | |
fa1b54e6 | 4180 | spin_unlock(&pool->lock); |
038366c5 | 4181 | } |
fa1b54e6 | 4182 | local_irq_restore(flags); |
1da177e4 | 4183 | |
dcd989cb | 4184 | return ret; |
1da177e4 | 4185 | } |
dcd989cb | 4186 | EXPORT_SYMBOL_GPL(work_busy); |
1da177e4 | 4187 | |
3d1cb205 TH |
4188 | /** |
4189 | * set_worker_desc - set description for the current work item | |
4190 | * @fmt: printf-style format string | |
4191 | * @...: arguments for the format string | |
4192 | * | |
4193 | * This function can be called by a running work function to describe what | |
4194 | * the work item is about. If the worker task gets dumped, this | |
4195 | * information will be printed out together to help debugging. The | |
4196 | * description can be at most WORKER_DESC_LEN including the trailing '\0'. | |
4197 | */ | |
4198 | void set_worker_desc(const char *fmt, ...) | |
4199 | { | |
4200 | struct worker *worker = current_wq_worker(); | |
4201 | va_list args; | |
4202 | ||
4203 | if (worker) { | |
4204 | va_start(args, fmt); | |
4205 | vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); | |
4206 | va_end(args); | |
4207 | worker->desc_valid = true; | |
4208 | } | |
4209 | } | |
4210 | ||
4211 | /** | |
4212 | * print_worker_info - print out worker information and description | |
4213 | * @log_lvl: the log level to use when printing | |
4214 | * @task: target task | |
4215 | * | |
4216 | * If @task is a worker and currently executing a work item, print out the | |
4217 | * name of the workqueue being serviced and worker description set with | |
4218 | * set_worker_desc() by the currently executing work item. | |
4219 | * | |
4220 | * This function can be safely called on any task as long as the | |
4221 | * task_struct itself is accessible. While safe, this function isn't | |
4222 | * synchronized and may print out mixups or garbages of limited length. | |
4223 | */ | |
4224 | void print_worker_info(const char *log_lvl, struct task_struct *task) | |
4225 | { | |
4226 | work_func_t *fn = NULL; | |
4227 | char name[WQ_NAME_LEN] = { }; | |
4228 | char desc[WORKER_DESC_LEN] = { }; | |
4229 | struct pool_workqueue *pwq = NULL; | |
4230 | struct workqueue_struct *wq = NULL; | |
4231 | bool desc_valid = false; | |
4232 | struct worker *worker; | |
4233 | ||
4234 | if (!(task->flags & PF_WQ_WORKER)) | |
4235 | return; | |
4236 | ||
4237 | /* | |
4238 | * This function is called without any synchronization and @task | |
4239 | * could be in any state. Be careful with dereferences. | |
4240 | */ | |
4241 | worker = probe_kthread_data(task); | |
4242 | ||
4243 | /* | |
4244 | * Carefully copy the associated workqueue's workfn and name. Keep | |
4245 | * the original last '\0' in case the original contains garbage. | |
4246 | */ | |
4247 | probe_kernel_read(&fn, &worker->current_func, sizeof(fn)); | |
4248 | probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); | |
4249 | probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); | |
4250 | probe_kernel_read(name, wq->name, sizeof(name) - 1); | |
4251 | ||
4252 | /* copy worker description */ | |
4253 | probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid)); | |
4254 | if (desc_valid) | |
4255 | probe_kernel_read(desc, worker->desc, sizeof(desc) - 1); | |
4256 | ||
4257 | if (fn || name[0] || desc[0]) { | |
4258 | printk("%sWorkqueue: %s %pf", log_lvl, name, fn); | |
4259 | if (desc[0]) | |
4260 | pr_cont(" (%s)", desc); | |
4261 | pr_cont("\n"); | |
4262 | } | |
4263 | } | |
4264 | ||
3494fc30 TH |
4265 | static void pr_cont_pool_info(struct worker_pool *pool) |
4266 | { | |
4267 | pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask); | |
4268 | if (pool->node != NUMA_NO_NODE) | |
4269 | pr_cont(" node=%d", pool->node); | |
4270 | pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice); | |
4271 | } | |
4272 | ||
4273 | static void pr_cont_work(bool comma, struct work_struct *work) | |
4274 | { | |
4275 | if (work->func == wq_barrier_func) { | |
4276 | struct wq_barrier *barr; | |
4277 | ||
4278 | barr = container_of(work, struct wq_barrier, work); | |
4279 | ||
4280 | pr_cont("%s BAR(%d)", comma ? "," : "", | |
4281 | task_pid_nr(barr->task)); | |
4282 | } else { | |
4283 | pr_cont("%s %pf", comma ? "," : "", work->func); | |
4284 | } | |
4285 | } | |
4286 | ||
4287 | static void show_pwq(struct pool_workqueue *pwq) | |
4288 | { | |
4289 | struct worker_pool *pool = pwq->pool; | |
4290 | struct work_struct *work; | |
4291 | struct worker *worker; | |
4292 | bool has_in_flight = false, has_pending = false; | |
4293 | int bkt; | |
4294 | ||
4295 | pr_info(" pwq %d:", pool->id); | |
4296 | pr_cont_pool_info(pool); | |
4297 | ||
4298 | pr_cont(" active=%d/%d%s\n", pwq->nr_active, pwq->max_active, | |
4299 | !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); | |
4300 | ||
4301 | hash_for_each(pool->busy_hash, bkt, worker, hentry) { | |
4302 | if (worker->current_pwq == pwq) { | |
4303 | has_in_flight = true; | |
4304 | break; | |
4305 | } | |
4306 | } | |
4307 | if (has_in_flight) { | |
4308 | bool comma = false; | |
4309 | ||
4310 | pr_info(" in-flight:"); | |
4311 | hash_for_each(pool->busy_hash, bkt, worker, hentry) { | |
4312 | if (worker->current_pwq != pwq) | |
4313 | continue; | |
4314 | ||
4315 | pr_cont("%s %d%s:%pf", comma ? "," : "", | |
4316 | task_pid_nr(worker->task), | |
4317 | worker == pwq->wq->rescuer ? "(RESCUER)" : "", | |
4318 | worker->current_func); | |
4319 | list_for_each_entry(work, &worker->scheduled, entry) | |
4320 | pr_cont_work(false, work); | |
4321 | comma = true; | |
4322 | } | |
4323 | pr_cont("\n"); | |
4324 | } | |
4325 | ||
4326 | list_for_each_entry(work, &pool->worklist, entry) { | |
4327 | if (get_work_pwq(work) == pwq) { | |
4328 | has_pending = true; | |
4329 | break; | |
4330 | } | |
4331 | } | |
4332 | if (has_pending) { | |
4333 | bool comma = false; | |
4334 | ||
4335 | pr_info(" pending:"); | |
4336 | list_for_each_entry(work, &pool->worklist, entry) { | |
4337 | if (get_work_pwq(work) != pwq) | |
4338 | continue; | |
4339 | ||
4340 | pr_cont_work(comma, work); | |
4341 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); | |
4342 | } | |
4343 | pr_cont("\n"); | |
4344 | } | |
4345 | ||
4346 | if (!list_empty(&pwq->delayed_works)) { | |
4347 | bool comma = false; | |
4348 | ||
4349 | pr_info(" delayed:"); | |
4350 | list_for_each_entry(work, &pwq->delayed_works, entry) { | |
4351 | pr_cont_work(comma, work); | |
4352 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); | |
4353 | } | |
4354 | pr_cont("\n"); | |
4355 | } | |
4356 | } | |
4357 | ||
4358 | /** | |
4359 | * show_workqueue_state - dump workqueue state | |
4360 | * | |
4361 | * Called from a sysrq handler and prints out all busy workqueues and | |
4362 | * pools. | |
4363 | */ | |
4364 | void show_workqueue_state(void) | |
4365 | { | |
4366 | struct workqueue_struct *wq; | |
4367 | struct worker_pool *pool; | |
4368 | unsigned long flags; | |
4369 | int pi; | |
4370 | ||
4371 | rcu_read_lock_sched(); | |
4372 | ||
4373 | pr_info("Showing busy workqueues and worker pools:\n"); | |
4374 | ||
4375 | list_for_each_entry_rcu(wq, &workqueues, list) { | |
4376 | struct pool_workqueue *pwq; | |
4377 | bool idle = true; | |
4378 | ||
4379 | for_each_pwq(pwq, wq) { | |
4380 | if (pwq->nr_active || !list_empty(&pwq->delayed_works)) { | |
4381 | idle = false; | |
4382 | break; | |
4383 | } | |
4384 | } | |
4385 | if (idle) | |
4386 | continue; | |
4387 | ||
4388 | pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags); | |
4389 | ||
4390 | for_each_pwq(pwq, wq) { | |
4391 | spin_lock_irqsave(&pwq->pool->lock, flags); | |
4392 | if (pwq->nr_active || !list_empty(&pwq->delayed_works)) | |
4393 | show_pwq(pwq); | |
4394 | spin_unlock_irqrestore(&pwq->pool->lock, flags); | |
4395 | } | |
4396 | } | |
4397 | ||
4398 | for_each_pool(pool, pi) { | |
4399 | struct worker *worker; | |
4400 | bool first = true; | |
4401 | ||
4402 | spin_lock_irqsave(&pool->lock, flags); | |
4403 | if (pool->nr_workers == pool->nr_idle) | |
4404 | goto next_pool; | |
4405 | ||
4406 | pr_info("pool %d:", pool->id); | |
4407 | pr_cont_pool_info(pool); | |
82607adc TH |
4408 | pr_cont(" hung=%us workers=%d", |
4409 | jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000, | |
4410 | pool->nr_workers); | |
3494fc30 TH |
4411 | if (pool->manager) |
4412 | pr_cont(" manager: %d", | |
4413 | task_pid_nr(pool->manager->task)); | |
4414 | list_for_each_entry(worker, &pool->idle_list, entry) { | |
4415 | pr_cont(" %s%d", first ? "idle: " : "", | |
4416 | task_pid_nr(worker->task)); | |
4417 | first = false; | |
4418 | } | |
4419 | pr_cont("\n"); | |
4420 | next_pool: | |
4421 | spin_unlock_irqrestore(&pool->lock, flags); | |
4422 | } | |
4423 | ||
4424 | rcu_read_unlock_sched(); | |
4425 | } | |
4426 | ||
db7bccf4 TH |
4427 | /* |
4428 | * CPU hotplug. | |
4429 | * | |
e22bee78 | 4430 | * There are two challenges in supporting CPU hotplug. Firstly, there |
112202d9 | 4431 | * are a lot of assumptions on strong associations among work, pwq and |
706026c2 | 4432 | * pool which make migrating pending and scheduled works very |
e22bee78 | 4433 | * difficult to implement without impacting hot paths. Secondly, |
94cf58bb | 4434 | * worker pools serve mix of short, long and very long running works making |
e22bee78 TH |
4435 | * blocked draining impractical. |
4436 | * | |
24647570 | 4437 | * This is solved by allowing the pools to be disassociated from the CPU |
628c78e7 TH |
4438 | * running as an unbound one and allowing it to be reattached later if the |
4439 | * cpu comes back online. | |
db7bccf4 | 4440 | */ |
1da177e4 | 4441 | |
706026c2 | 4442 | static void wq_unbind_fn(struct work_struct *work) |
3af24433 | 4443 | { |
38db41d9 | 4444 | int cpu = smp_processor_id(); |
4ce62e9e | 4445 | struct worker_pool *pool; |
db7bccf4 | 4446 | struct worker *worker; |
3af24433 | 4447 | |
f02ae73a | 4448 | for_each_cpu_worker_pool(pool, cpu) { |
92f9c5c4 | 4449 | mutex_lock(&pool->attach_mutex); |
94cf58bb | 4450 | spin_lock_irq(&pool->lock); |
3af24433 | 4451 | |
94cf58bb | 4452 | /* |
92f9c5c4 | 4453 | * We've blocked all attach/detach operations. Make all workers |
94cf58bb TH |
4454 | * unbound and set DISASSOCIATED. Before this, all workers |
4455 | * except for the ones which are still executing works from | |
4456 | * before the last CPU down must be on the cpu. After | |
4457 | * this, they may become diasporas. | |
4458 | */ | |
da028469 | 4459 | for_each_pool_worker(worker, pool) |
c9e7cf27 | 4460 | worker->flags |= WORKER_UNBOUND; |
06ba38a9 | 4461 | |
24647570 | 4462 | pool->flags |= POOL_DISASSOCIATED; |
f2d5a0ee | 4463 | |
94cf58bb | 4464 | spin_unlock_irq(&pool->lock); |
92f9c5c4 | 4465 | mutex_unlock(&pool->attach_mutex); |
628c78e7 | 4466 | |
eb283428 LJ |
4467 | /* |
4468 | * Call schedule() so that we cross rq->lock and thus can | |
4469 | * guarantee sched callbacks see the %WORKER_UNBOUND flag. | |
4470 | * This is necessary as scheduler callbacks may be invoked | |
4471 | * from other cpus. | |
4472 | */ | |
4473 | schedule(); | |
06ba38a9 | 4474 | |
eb283428 LJ |
4475 | /* |
4476 | * Sched callbacks are disabled now. Zap nr_running. | |
4477 | * After this, nr_running stays zero and need_more_worker() | |
4478 | * and keep_working() are always true as long as the | |
4479 | * worklist is not empty. This pool now behaves as an | |
4480 | * unbound (in terms of concurrency management) pool which | |
4481 | * are served by workers tied to the pool. | |
4482 | */ | |
e19e397a | 4483 | atomic_set(&pool->nr_running, 0); |
eb283428 LJ |
4484 | |
4485 | /* | |
4486 | * With concurrency management just turned off, a busy | |
4487 | * worker blocking could lead to lengthy stalls. Kick off | |
4488 | * unbound chain execution of currently pending work items. | |
4489 | */ | |
4490 | spin_lock_irq(&pool->lock); | |
4491 | wake_up_worker(pool); | |
4492 | spin_unlock_irq(&pool->lock); | |
4493 | } | |
3af24433 | 4494 | } |
3af24433 | 4495 | |
bd7c089e TH |
4496 | /** |
4497 | * rebind_workers - rebind all workers of a pool to the associated CPU | |
4498 | * @pool: pool of interest | |
4499 | * | |
a9ab775b | 4500 | * @pool->cpu is coming online. Rebind all workers to the CPU. |
bd7c089e TH |
4501 | */ |
4502 | static void rebind_workers(struct worker_pool *pool) | |
4503 | { | |
a9ab775b | 4504 | struct worker *worker; |
bd7c089e | 4505 | |
92f9c5c4 | 4506 | lockdep_assert_held(&pool->attach_mutex); |
bd7c089e | 4507 | |
a9ab775b TH |
4508 | /* |
4509 | * Restore CPU affinity of all workers. As all idle workers should | |
4510 | * be on the run-queue of the associated CPU before any local | |
402dd89d | 4511 | * wake-ups for concurrency management happen, restore CPU affinity |
a9ab775b TH |
4512 | * of all workers first and then clear UNBOUND. As we're called |
4513 | * from CPU_ONLINE, the following shouldn't fail. | |
4514 | */ | |
da028469 | 4515 | for_each_pool_worker(worker, pool) |
a9ab775b TH |
4516 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, |
4517 | pool->attrs->cpumask) < 0); | |
bd7c089e | 4518 | |
a9ab775b | 4519 | spin_lock_irq(&pool->lock); |
3de5e884 | 4520 | pool->flags &= ~POOL_DISASSOCIATED; |
bd7c089e | 4521 | |
da028469 | 4522 | for_each_pool_worker(worker, pool) { |
a9ab775b | 4523 | unsigned int worker_flags = worker->flags; |
bd7c089e TH |
4524 | |
4525 | /* | |
a9ab775b TH |
4526 | * A bound idle worker should actually be on the runqueue |
4527 | * of the associated CPU for local wake-ups targeting it to | |
4528 | * work. Kick all idle workers so that they migrate to the | |
4529 | * associated CPU. Doing this in the same loop as | |
4530 | * replacing UNBOUND with REBOUND is safe as no worker will | |
4531 | * be bound before @pool->lock is released. | |
bd7c089e | 4532 | */ |
a9ab775b TH |
4533 | if (worker_flags & WORKER_IDLE) |
4534 | wake_up_process(worker->task); | |
bd7c089e | 4535 | |
a9ab775b TH |
4536 | /* |
4537 | * We want to clear UNBOUND but can't directly call | |
4538 | * worker_clr_flags() or adjust nr_running. Atomically | |
4539 | * replace UNBOUND with another NOT_RUNNING flag REBOUND. | |
4540 | * @worker will clear REBOUND using worker_clr_flags() when | |
4541 | * it initiates the next execution cycle thus restoring | |
4542 | * concurrency management. Note that when or whether | |
4543 | * @worker clears REBOUND doesn't affect correctness. | |
4544 | * | |
4545 | * ACCESS_ONCE() is necessary because @worker->flags may be | |
4546 | * tested without holding any lock in | |
4547 | * wq_worker_waking_up(). Without it, NOT_RUNNING test may | |
4548 | * fail incorrectly leading to premature concurrency | |
4549 | * management operations. | |
4550 | */ | |
4551 | WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); | |
4552 | worker_flags |= WORKER_REBOUND; | |
4553 | worker_flags &= ~WORKER_UNBOUND; | |
4554 | ACCESS_ONCE(worker->flags) = worker_flags; | |
bd7c089e | 4555 | } |
a9ab775b TH |
4556 | |
4557 | spin_unlock_irq(&pool->lock); | |
bd7c089e TH |
4558 | } |
4559 | ||
7dbc725e TH |
4560 | /** |
4561 | * restore_unbound_workers_cpumask - restore cpumask of unbound workers | |
4562 | * @pool: unbound pool of interest | |
4563 | * @cpu: the CPU which is coming up | |
4564 | * | |
4565 | * An unbound pool may end up with a cpumask which doesn't have any online | |
4566 | * CPUs. When a worker of such pool get scheduled, the scheduler resets | |
4567 | * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any | |
4568 | * online CPU before, cpus_allowed of all its workers should be restored. | |
4569 | */ | |
4570 | static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) | |
4571 | { | |
4572 | static cpumask_t cpumask; | |
4573 | struct worker *worker; | |
7dbc725e | 4574 | |
92f9c5c4 | 4575 | lockdep_assert_held(&pool->attach_mutex); |
7dbc725e TH |
4576 | |
4577 | /* is @cpu allowed for @pool? */ | |
4578 | if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) | |
4579 | return; | |
4580 | ||
4581 | /* is @cpu the only online CPU? */ | |
4582 | cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); | |
4583 | if (cpumask_weight(&cpumask) != 1) | |
4584 | return; | |
4585 | ||
4586 | /* as we're called from CPU_ONLINE, the following shouldn't fail */ | |
da028469 | 4587 | for_each_pool_worker(worker, pool) |
7dbc725e TH |
4588 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, |
4589 | pool->attrs->cpumask) < 0); | |
4590 | } | |
4591 | ||
8db25e78 TH |
4592 | /* |
4593 | * Workqueues should be brought up before normal priority CPU notifiers. | |
4594 | * This will be registered high priority CPU notifier. | |
4595 | */ | |
0db0628d | 4596 | static int workqueue_cpu_up_callback(struct notifier_block *nfb, |
8db25e78 TH |
4597 | unsigned long action, |
4598 | void *hcpu) | |
3af24433 | 4599 | { |
d84ff051 | 4600 | int cpu = (unsigned long)hcpu; |
4ce62e9e | 4601 | struct worker_pool *pool; |
4c16bd32 | 4602 | struct workqueue_struct *wq; |
7dbc725e | 4603 | int pi; |
3ce63377 | 4604 | |
8db25e78 | 4605 | switch (action & ~CPU_TASKS_FROZEN) { |
3af24433 | 4606 | case CPU_UP_PREPARE: |
f02ae73a | 4607 | for_each_cpu_worker_pool(pool, cpu) { |
3ce63377 TH |
4608 | if (pool->nr_workers) |
4609 | continue; | |
051e1850 | 4610 | if (!create_worker(pool)) |
3ce63377 | 4611 | return NOTIFY_BAD; |
3af24433 | 4612 | } |
8db25e78 | 4613 | break; |
3af24433 | 4614 | |
db7bccf4 TH |
4615 | case CPU_DOWN_FAILED: |
4616 | case CPU_ONLINE: | |
68e13a67 | 4617 | mutex_lock(&wq_pool_mutex); |
7dbc725e TH |
4618 | |
4619 | for_each_pool(pool, pi) { | |
92f9c5c4 | 4620 | mutex_lock(&pool->attach_mutex); |
94cf58bb | 4621 | |
f05b558d | 4622 | if (pool->cpu == cpu) |
7dbc725e | 4623 | rebind_workers(pool); |
f05b558d | 4624 | else if (pool->cpu < 0) |
7dbc725e | 4625 | restore_unbound_workers_cpumask(pool, cpu); |
94cf58bb | 4626 | |
6ba94429 FW |
4627 | mutex_unlock(&pool->attach_mutex); |
4628 | } | |
4629 | ||
4630 | /* update NUMA affinity of unbound workqueues */ | |
4631 | list_for_each_entry(wq, &workqueues, list) | |
4632 | wq_update_unbound_numa(wq, cpu, true); | |
4633 | ||
4634 | mutex_unlock(&wq_pool_mutex); | |
4635 | break; | |
4636 | } | |
4637 | return NOTIFY_OK; | |
4638 | } | |
4639 | ||
4640 | /* | |
4641 | * Workqueues should be brought down after normal priority CPU notifiers. | |
4642 | * This will be registered as low priority CPU notifier. | |
4643 | */ | |
4644 | static int workqueue_cpu_down_callback(struct notifier_block *nfb, | |
4645 | unsigned long action, | |
4646 | void *hcpu) | |
4647 | { | |
4648 | int cpu = (unsigned long)hcpu; | |
4649 | struct work_struct unbind_work; | |
4650 | struct workqueue_struct *wq; | |
4651 | ||
4652 | switch (action & ~CPU_TASKS_FROZEN) { | |
4653 | case CPU_DOWN_PREPARE: | |
4654 | /* unbinding per-cpu workers should happen on the local CPU */ | |
4655 | INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn); | |
4656 | queue_work_on(cpu, system_highpri_wq, &unbind_work); | |
4657 | ||
4658 | /* update NUMA affinity of unbound workqueues */ | |
4659 | mutex_lock(&wq_pool_mutex); | |
4660 | list_for_each_entry(wq, &workqueues, list) | |
4661 | wq_update_unbound_numa(wq, cpu, false); | |
4662 | mutex_unlock(&wq_pool_mutex); | |
4663 | ||
4664 | /* wait for per-cpu unbinding to finish */ | |
4665 | flush_work(&unbind_work); | |
4666 | destroy_work_on_stack(&unbind_work); | |
4667 | break; | |
4668 | } | |
4669 | return NOTIFY_OK; | |
4670 | } | |
4671 | ||
4672 | #ifdef CONFIG_SMP | |
4673 | ||
4674 | struct work_for_cpu { | |
4675 | struct work_struct work; | |
4676 | long (*fn)(void *); | |
4677 | void *arg; | |
4678 | long ret; | |
4679 | }; | |
4680 | ||
4681 | static void work_for_cpu_fn(struct work_struct *work) | |
4682 | { | |
4683 | struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); | |
4684 | ||
4685 | wfc->ret = wfc->fn(wfc->arg); | |
4686 | } | |
4687 | ||
4688 | /** | |
4689 | * work_on_cpu - run a function in user context on a particular cpu | |
4690 | * @cpu: the cpu to run on | |
4691 | * @fn: the function to run | |
4692 | * @arg: the function arg | |
4693 | * | |
4694 | * It is up to the caller to ensure that the cpu doesn't go offline. | |
4695 | * The caller must not hold any locks which would prevent @fn from completing. | |
4696 | * | |
4697 | * Return: The value @fn returns. | |
4698 | */ | |
4699 | long work_on_cpu(int cpu, long (*fn)(void *), void *arg) | |
4700 | { | |
4701 | struct work_for_cpu wfc = { .fn = fn, .arg = arg }; | |
4702 | ||
4703 | INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); | |
4704 | schedule_work_on(cpu, &wfc.work); | |
4705 | flush_work(&wfc.work); | |
4706 | destroy_work_on_stack(&wfc.work); | |
4707 | return wfc.ret; | |
4708 | } | |
4709 | EXPORT_SYMBOL_GPL(work_on_cpu); | |
4710 | #endif /* CONFIG_SMP */ | |
4711 | ||
4712 | #ifdef CONFIG_FREEZER | |
4713 | ||
4714 | /** | |
4715 | * freeze_workqueues_begin - begin freezing workqueues | |
4716 | * | |
4717 | * Start freezing workqueues. After this function returns, all freezable | |
4718 | * workqueues will queue new works to their delayed_works list instead of | |
4719 | * pool->worklist. | |
4720 | * | |
4721 | * CONTEXT: | |
4722 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. | |
4723 | */ | |
4724 | void freeze_workqueues_begin(void) | |
4725 | { | |
4726 | struct workqueue_struct *wq; | |
4727 | struct pool_workqueue *pwq; | |
4728 | ||
4729 | mutex_lock(&wq_pool_mutex); | |
4730 | ||
4731 | WARN_ON_ONCE(workqueue_freezing); | |
4732 | workqueue_freezing = true; | |
4733 | ||
4734 | list_for_each_entry(wq, &workqueues, list) { | |
4735 | mutex_lock(&wq->mutex); | |
4736 | for_each_pwq(pwq, wq) | |
4737 | pwq_adjust_max_active(pwq); | |
4738 | mutex_unlock(&wq->mutex); | |
4739 | } | |
4740 | ||
4741 | mutex_unlock(&wq_pool_mutex); | |
4742 | } | |
4743 | ||
4744 | /** | |
4745 | * freeze_workqueues_busy - are freezable workqueues still busy? | |
4746 | * | |
4747 | * Check whether freezing is complete. This function must be called | |
4748 | * between freeze_workqueues_begin() and thaw_workqueues(). | |
4749 | * | |
4750 | * CONTEXT: | |
4751 | * Grabs and releases wq_pool_mutex. | |
4752 | * | |
4753 | * Return: | |
4754 | * %true if some freezable workqueues are still busy. %false if freezing | |
4755 | * is complete. | |
4756 | */ | |
4757 | bool freeze_workqueues_busy(void) | |
4758 | { | |
4759 | bool busy = false; | |
4760 | struct workqueue_struct *wq; | |
4761 | struct pool_workqueue *pwq; | |
4762 | ||
4763 | mutex_lock(&wq_pool_mutex); | |
4764 | ||
4765 | WARN_ON_ONCE(!workqueue_freezing); | |
4766 | ||
4767 | list_for_each_entry(wq, &workqueues, list) { | |
4768 | if (!(wq->flags & WQ_FREEZABLE)) | |
4769 | continue; | |
4770 | /* | |
4771 | * nr_active is monotonically decreasing. It's safe | |
4772 | * to peek without lock. | |
4773 | */ | |
4774 | rcu_read_lock_sched(); | |
4775 | for_each_pwq(pwq, wq) { | |
4776 | WARN_ON_ONCE(pwq->nr_active < 0); | |
4777 | if (pwq->nr_active) { | |
4778 | busy = true; | |
4779 | rcu_read_unlock_sched(); | |
4780 | goto out_unlock; | |
4781 | } | |
4782 | } | |
4783 | rcu_read_unlock_sched(); | |
4784 | } | |
4785 | out_unlock: | |
4786 | mutex_unlock(&wq_pool_mutex); | |
4787 | return busy; | |
4788 | } | |
4789 | ||
4790 | /** | |
4791 | * thaw_workqueues - thaw workqueues | |
4792 | * | |
4793 | * Thaw workqueues. Normal queueing is restored and all collected | |
4794 | * frozen works are transferred to their respective pool worklists. | |
4795 | * | |
4796 | * CONTEXT: | |
4797 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. | |
4798 | */ | |
4799 | void thaw_workqueues(void) | |
4800 | { | |
4801 | struct workqueue_struct *wq; | |
4802 | struct pool_workqueue *pwq; | |
4803 | ||
4804 | mutex_lock(&wq_pool_mutex); | |
4805 | ||
4806 | if (!workqueue_freezing) | |
4807 | goto out_unlock; | |
4808 | ||
4809 | workqueue_freezing = false; | |
4810 | ||
4811 | /* restore max_active and repopulate worklist */ | |
4812 | list_for_each_entry(wq, &workqueues, list) { | |
4813 | mutex_lock(&wq->mutex); | |
4814 | for_each_pwq(pwq, wq) | |
4815 | pwq_adjust_max_active(pwq); | |
4816 | mutex_unlock(&wq->mutex); | |
4817 | } | |
4818 | ||
4819 | out_unlock: | |
4820 | mutex_unlock(&wq_pool_mutex); | |
4821 | } | |
4822 | #endif /* CONFIG_FREEZER */ | |
4823 | ||
042f7df1 LJ |
4824 | static int workqueue_apply_unbound_cpumask(void) |
4825 | { | |
4826 | LIST_HEAD(ctxs); | |
4827 | int ret = 0; | |
4828 | struct workqueue_struct *wq; | |
4829 | struct apply_wqattrs_ctx *ctx, *n; | |
4830 | ||
4831 | lockdep_assert_held(&wq_pool_mutex); | |
4832 | ||
4833 | list_for_each_entry(wq, &workqueues, list) { | |
4834 | if (!(wq->flags & WQ_UNBOUND)) | |
4835 | continue; | |
4836 | /* creating multiple pwqs breaks ordering guarantee */ | |
4837 | if (wq->flags & __WQ_ORDERED) | |
4838 | continue; | |
4839 | ||
4840 | ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs); | |
4841 | if (!ctx) { | |
4842 | ret = -ENOMEM; | |
4843 | break; | |
4844 | } | |
4845 | ||
4846 | list_add_tail(&ctx->list, &ctxs); | |
4847 | } | |
4848 | ||
4849 | list_for_each_entry_safe(ctx, n, &ctxs, list) { | |
4850 | if (!ret) | |
4851 | apply_wqattrs_commit(ctx); | |
4852 | apply_wqattrs_cleanup(ctx); | |
4853 | } | |
4854 | ||
4855 | return ret; | |
4856 | } | |
4857 | ||
4858 | /** | |
4859 | * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask | |
4860 | * @cpumask: the cpumask to set | |
4861 | * | |
4862 | * The low-level workqueues cpumask is a global cpumask that limits | |
4863 | * the affinity of all unbound workqueues. This function check the @cpumask | |
4864 | * and apply it to all unbound workqueues and updates all pwqs of them. | |
4865 | * | |
4866 | * Retun: 0 - Success | |
4867 | * -EINVAL - Invalid @cpumask | |
4868 | * -ENOMEM - Failed to allocate memory for attrs or pwqs. | |
4869 | */ | |
4870 | int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) | |
4871 | { | |
4872 | int ret = -EINVAL; | |
4873 | cpumask_var_t saved_cpumask; | |
4874 | ||
4875 | if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL)) | |
4876 | return -ENOMEM; | |
4877 | ||
042f7df1 LJ |
4878 | cpumask_and(cpumask, cpumask, cpu_possible_mask); |
4879 | if (!cpumask_empty(cpumask)) { | |
a0111cf6 | 4880 | apply_wqattrs_lock(); |
042f7df1 LJ |
4881 | |
4882 | /* save the old wq_unbound_cpumask. */ | |
4883 | cpumask_copy(saved_cpumask, wq_unbound_cpumask); | |
4884 | ||
4885 | /* update wq_unbound_cpumask at first and apply it to wqs. */ | |
4886 | cpumask_copy(wq_unbound_cpumask, cpumask); | |
4887 | ret = workqueue_apply_unbound_cpumask(); | |
4888 | ||
4889 | /* restore the wq_unbound_cpumask when failed. */ | |
4890 | if (ret < 0) | |
4891 | cpumask_copy(wq_unbound_cpumask, saved_cpumask); | |
4892 | ||
a0111cf6 | 4893 | apply_wqattrs_unlock(); |
042f7df1 | 4894 | } |
042f7df1 LJ |
4895 | |
4896 | free_cpumask_var(saved_cpumask); | |
4897 | return ret; | |
4898 | } | |
4899 | ||
6ba94429 FW |
4900 | #ifdef CONFIG_SYSFS |
4901 | /* | |
4902 | * Workqueues with WQ_SYSFS flag set is visible to userland via | |
4903 | * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the | |
4904 | * following attributes. | |
4905 | * | |
4906 | * per_cpu RO bool : whether the workqueue is per-cpu or unbound | |
4907 | * max_active RW int : maximum number of in-flight work items | |
4908 | * | |
4909 | * Unbound workqueues have the following extra attributes. | |
4910 | * | |
4911 | * id RO int : the associated pool ID | |
4912 | * nice RW int : nice value of the workers | |
4913 | * cpumask RW mask : bitmask of allowed CPUs for the workers | |
4914 | */ | |
4915 | struct wq_device { | |
4916 | struct workqueue_struct *wq; | |
4917 | struct device dev; | |
4918 | }; | |
4919 | ||
4920 | static struct workqueue_struct *dev_to_wq(struct device *dev) | |
4921 | { | |
4922 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); | |
4923 | ||
4924 | return wq_dev->wq; | |
4925 | } | |
4926 | ||
4927 | static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, | |
4928 | char *buf) | |
4929 | { | |
4930 | struct workqueue_struct *wq = dev_to_wq(dev); | |
4931 | ||
4932 | return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); | |
4933 | } | |
4934 | static DEVICE_ATTR_RO(per_cpu); | |
4935 | ||
4936 | static ssize_t max_active_show(struct device *dev, | |
4937 | struct device_attribute *attr, char *buf) | |
4938 | { | |
4939 | struct workqueue_struct *wq = dev_to_wq(dev); | |
4940 | ||
4941 | return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); | |
4942 | } | |
4943 | ||
4944 | static ssize_t max_active_store(struct device *dev, | |
4945 | struct device_attribute *attr, const char *buf, | |
4946 | size_t count) | |
4947 | { | |
4948 | struct workqueue_struct *wq = dev_to_wq(dev); | |
4949 | int val; | |
4950 | ||
4951 | if (sscanf(buf, "%d", &val) != 1 || val <= 0) | |
4952 | return -EINVAL; | |
4953 | ||
4954 | workqueue_set_max_active(wq, val); | |
4955 | return count; | |
4956 | } | |
4957 | static DEVICE_ATTR_RW(max_active); | |
4958 | ||
4959 | static struct attribute *wq_sysfs_attrs[] = { | |
4960 | &dev_attr_per_cpu.attr, | |
4961 | &dev_attr_max_active.attr, | |
4962 | NULL, | |
4963 | }; | |
4964 | ATTRIBUTE_GROUPS(wq_sysfs); | |
4965 | ||
4966 | static ssize_t wq_pool_ids_show(struct device *dev, | |
4967 | struct device_attribute *attr, char *buf) | |
4968 | { | |
4969 | struct workqueue_struct *wq = dev_to_wq(dev); | |
4970 | const char *delim = ""; | |
4971 | int node, written = 0; | |
4972 | ||
4973 | rcu_read_lock_sched(); | |
4974 | for_each_node(node) { | |
4975 | written += scnprintf(buf + written, PAGE_SIZE - written, | |
4976 | "%s%d:%d", delim, node, | |
4977 | unbound_pwq_by_node(wq, node)->pool->id); | |
4978 | delim = " "; | |
4979 | } | |
4980 | written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); | |
4981 | rcu_read_unlock_sched(); | |
4982 | ||
4983 | return written; | |
4984 | } | |
4985 | ||
4986 | static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, | |
4987 | char *buf) | |
4988 | { | |
4989 | struct workqueue_struct *wq = dev_to_wq(dev); | |
4990 | int written; | |
4991 | ||
4992 | mutex_lock(&wq->mutex); | |
4993 | written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); | |
4994 | mutex_unlock(&wq->mutex); | |
4995 | ||
4996 | return written; | |
4997 | } | |
4998 | ||
4999 | /* prepare workqueue_attrs for sysfs store operations */ | |
5000 | static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) | |
5001 | { | |
5002 | struct workqueue_attrs *attrs; | |
5003 | ||
899a94fe LJ |
5004 | lockdep_assert_held(&wq_pool_mutex); |
5005 | ||
6ba94429 FW |
5006 | attrs = alloc_workqueue_attrs(GFP_KERNEL); |
5007 | if (!attrs) | |
5008 | return NULL; | |
5009 | ||
6ba94429 | 5010 | copy_workqueue_attrs(attrs, wq->unbound_attrs); |
6ba94429 FW |
5011 | return attrs; |
5012 | } | |
5013 | ||
5014 | static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, | |
5015 | const char *buf, size_t count) | |
5016 | { | |
5017 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5018 | struct workqueue_attrs *attrs; | |
d4d3e257 LJ |
5019 | int ret = -ENOMEM; |
5020 | ||
5021 | apply_wqattrs_lock(); | |
6ba94429 FW |
5022 | |
5023 | attrs = wq_sysfs_prep_attrs(wq); | |
5024 | if (!attrs) | |
d4d3e257 | 5025 | goto out_unlock; |
6ba94429 FW |
5026 | |
5027 | if (sscanf(buf, "%d", &attrs->nice) == 1 && | |
5028 | attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) | |
d4d3e257 | 5029 | ret = apply_workqueue_attrs_locked(wq, attrs); |
6ba94429 FW |
5030 | else |
5031 | ret = -EINVAL; | |
5032 | ||
d4d3e257 LJ |
5033 | out_unlock: |
5034 | apply_wqattrs_unlock(); | |
6ba94429 FW |
5035 | free_workqueue_attrs(attrs); |
5036 | return ret ?: count; | |
5037 | } | |
5038 | ||
5039 | static ssize_t wq_cpumask_show(struct device *dev, | |
5040 | struct device_attribute *attr, char *buf) | |
5041 | { | |
5042 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5043 | int written; | |
5044 | ||
5045 | mutex_lock(&wq->mutex); | |
5046 | written = scnprintf(buf, PAGE_SIZE, "%*pb\n", | |
5047 | cpumask_pr_args(wq->unbound_attrs->cpumask)); | |
5048 | mutex_unlock(&wq->mutex); | |
5049 | return written; | |
5050 | } | |
5051 | ||
5052 | static ssize_t wq_cpumask_store(struct device *dev, | |
5053 | struct device_attribute *attr, | |
5054 | const char *buf, size_t count) | |
5055 | { | |
5056 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5057 | struct workqueue_attrs *attrs; | |
d4d3e257 LJ |
5058 | int ret = -ENOMEM; |
5059 | ||
5060 | apply_wqattrs_lock(); | |
6ba94429 FW |
5061 | |
5062 | attrs = wq_sysfs_prep_attrs(wq); | |
5063 | if (!attrs) | |
d4d3e257 | 5064 | goto out_unlock; |
6ba94429 FW |
5065 | |
5066 | ret = cpumask_parse(buf, attrs->cpumask); | |
5067 | if (!ret) | |
d4d3e257 | 5068 | ret = apply_workqueue_attrs_locked(wq, attrs); |
6ba94429 | 5069 | |
d4d3e257 LJ |
5070 | out_unlock: |
5071 | apply_wqattrs_unlock(); | |
6ba94429 FW |
5072 | free_workqueue_attrs(attrs); |
5073 | return ret ?: count; | |
5074 | } | |
5075 | ||
5076 | static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, | |
5077 | char *buf) | |
5078 | { | |
5079 | struct workqueue_struct *wq = dev_to_wq(dev); | |
5080 | int written; | |
7dbc725e | 5081 | |
6ba94429 FW |
5082 | mutex_lock(&wq->mutex); |
5083 | written = scnprintf(buf, PAGE_SIZE, "%d\n", | |
5084 | !wq->unbound_attrs->no_numa); | |
5085 | mutex_unlock(&wq->mutex); | |
4c16bd32 | 5086 | |
6ba94429 | 5087 | return written; |
65758202 TH |
5088 | } |
5089 | ||
6ba94429 FW |
5090 | static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, |
5091 | const char *buf, size_t count) | |
65758202 | 5092 | { |
6ba94429 FW |
5093 | struct workqueue_struct *wq = dev_to_wq(dev); |
5094 | struct workqueue_attrs *attrs; | |
d4d3e257 LJ |
5095 | int v, ret = -ENOMEM; |
5096 | ||
5097 | apply_wqattrs_lock(); | |
4c16bd32 | 5098 | |
6ba94429 FW |
5099 | attrs = wq_sysfs_prep_attrs(wq); |
5100 | if (!attrs) | |
d4d3e257 | 5101 | goto out_unlock; |
4c16bd32 | 5102 | |
6ba94429 FW |
5103 | ret = -EINVAL; |
5104 | if (sscanf(buf, "%d", &v) == 1) { | |
5105 | attrs->no_numa = !v; | |
d4d3e257 | 5106 | ret = apply_workqueue_attrs_locked(wq, attrs); |
65758202 | 5107 | } |
6ba94429 | 5108 | |
d4d3e257 LJ |
5109 | out_unlock: |
5110 | apply_wqattrs_unlock(); | |
6ba94429 FW |
5111 | free_workqueue_attrs(attrs); |
5112 | return ret ?: count; | |
65758202 TH |
5113 | } |
5114 | ||
6ba94429 FW |
5115 | static struct device_attribute wq_sysfs_unbound_attrs[] = { |
5116 | __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), | |
5117 | __ATTR(nice, 0644, wq_nice_show, wq_nice_store), | |
5118 | __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), | |
5119 | __ATTR(numa, 0644, wq_numa_show, wq_numa_store), | |
5120 | __ATTR_NULL, | |
5121 | }; | |
8ccad40d | 5122 | |
6ba94429 FW |
5123 | static struct bus_type wq_subsys = { |
5124 | .name = "workqueue", | |
5125 | .dev_groups = wq_sysfs_groups, | |
2d3854a3 RR |
5126 | }; |
5127 | ||
b05a7928 FW |
5128 | static ssize_t wq_unbound_cpumask_show(struct device *dev, |
5129 | struct device_attribute *attr, char *buf) | |
5130 | { | |
5131 | int written; | |
5132 | ||
042f7df1 | 5133 | mutex_lock(&wq_pool_mutex); |
b05a7928 FW |
5134 | written = scnprintf(buf, PAGE_SIZE, "%*pb\n", |
5135 | cpumask_pr_args(wq_unbound_cpumask)); | |
042f7df1 | 5136 | mutex_unlock(&wq_pool_mutex); |
b05a7928 FW |
5137 | |
5138 | return written; | |
5139 | } | |
5140 | ||
042f7df1 LJ |
5141 | static ssize_t wq_unbound_cpumask_store(struct device *dev, |
5142 | struct device_attribute *attr, const char *buf, size_t count) | |
5143 | { | |
5144 | cpumask_var_t cpumask; | |
5145 | int ret; | |
5146 | ||
5147 | if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) | |
5148 | return -ENOMEM; | |
5149 | ||
5150 | ret = cpumask_parse(buf, cpumask); | |
5151 | if (!ret) | |
5152 | ret = workqueue_set_unbound_cpumask(cpumask); | |
5153 | ||
5154 | free_cpumask_var(cpumask); | |
5155 | return ret ? ret : count; | |
5156 | } | |
5157 | ||
b05a7928 | 5158 | static struct device_attribute wq_sysfs_cpumask_attr = |
042f7df1 LJ |
5159 | __ATTR(cpumask, 0644, wq_unbound_cpumask_show, |
5160 | wq_unbound_cpumask_store); | |
b05a7928 | 5161 | |
6ba94429 | 5162 | static int __init wq_sysfs_init(void) |
2d3854a3 | 5163 | { |
b05a7928 FW |
5164 | int err; |
5165 | ||
5166 | err = subsys_virtual_register(&wq_subsys, NULL); | |
5167 | if (err) | |
5168 | return err; | |
5169 | ||
5170 | return device_create_file(wq_subsys.dev_root, &wq_sysfs_cpumask_attr); | |
2d3854a3 | 5171 | } |
6ba94429 | 5172 | core_initcall(wq_sysfs_init); |
2d3854a3 | 5173 | |
6ba94429 | 5174 | static void wq_device_release(struct device *dev) |
2d3854a3 | 5175 | { |
6ba94429 | 5176 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
6b44003e | 5177 | |
6ba94429 | 5178 | kfree(wq_dev); |
2d3854a3 | 5179 | } |
a0a1a5fd TH |
5180 | |
5181 | /** | |
6ba94429 FW |
5182 | * workqueue_sysfs_register - make a workqueue visible in sysfs |
5183 | * @wq: the workqueue to register | |
a0a1a5fd | 5184 | * |
6ba94429 FW |
5185 | * Expose @wq in sysfs under /sys/bus/workqueue/devices. |
5186 | * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set | |
5187 | * which is the preferred method. | |
a0a1a5fd | 5188 | * |
6ba94429 FW |
5189 | * Workqueue user should use this function directly iff it wants to apply |
5190 | * workqueue_attrs before making the workqueue visible in sysfs; otherwise, | |
5191 | * apply_workqueue_attrs() may race against userland updating the | |
5192 | * attributes. | |
5193 | * | |
5194 | * Return: 0 on success, -errno on failure. | |
a0a1a5fd | 5195 | */ |
6ba94429 | 5196 | int workqueue_sysfs_register(struct workqueue_struct *wq) |
a0a1a5fd | 5197 | { |
6ba94429 FW |
5198 | struct wq_device *wq_dev; |
5199 | int ret; | |
a0a1a5fd | 5200 | |
6ba94429 | 5201 | /* |
402dd89d | 5202 | * Adjusting max_active or creating new pwqs by applying |
6ba94429 FW |
5203 | * attributes breaks ordering guarantee. Disallow exposing ordered |
5204 | * workqueues. | |
5205 | */ | |
5206 | if (WARN_ON(wq->flags & __WQ_ORDERED)) | |
5207 | return -EINVAL; | |
a0a1a5fd | 5208 | |
6ba94429 FW |
5209 | wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); |
5210 | if (!wq_dev) | |
5211 | return -ENOMEM; | |
5bcab335 | 5212 | |
6ba94429 FW |
5213 | wq_dev->wq = wq; |
5214 | wq_dev->dev.bus = &wq_subsys; | |
5215 | wq_dev->dev.init_name = wq->name; | |
5216 | wq_dev->dev.release = wq_device_release; | |
a0a1a5fd | 5217 | |
6ba94429 FW |
5218 | /* |
5219 | * unbound_attrs are created separately. Suppress uevent until | |
5220 | * everything is ready. | |
5221 | */ | |
5222 | dev_set_uevent_suppress(&wq_dev->dev, true); | |
a0a1a5fd | 5223 | |
6ba94429 FW |
5224 | ret = device_register(&wq_dev->dev); |
5225 | if (ret) { | |
5226 | kfree(wq_dev); | |
5227 | wq->wq_dev = NULL; | |
5228 | return ret; | |
5229 | } | |
a0a1a5fd | 5230 | |
6ba94429 FW |
5231 | if (wq->flags & WQ_UNBOUND) { |
5232 | struct device_attribute *attr; | |
a0a1a5fd | 5233 | |
6ba94429 FW |
5234 | for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { |
5235 | ret = device_create_file(&wq_dev->dev, attr); | |
5236 | if (ret) { | |
5237 | device_unregister(&wq_dev->dev); | |
5238 | wq->wq_dev = NULL; | |
5239 | return ret; | |
a0a1a5fd TH |
5240 | } |
5241 | } | |
5242 | } | |
6ba94429 FW |
5243 | |
5244 | dev_set_uevent_suppress(&wq_dev->dev, false); | |
5245 | kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); | |
5246 | return 0; | |
a0a1a5fd TH |
5247 | } |
5248 | ||
5249 | /** | |
6ba94429 FW |
5250 | * workqueue_sysfs_unregister - undo workqueue_sysfs_register() |
5251 | * @wq: the workqueue to unregister | |
a0a1a5fd | 5252 | * |
6ba94429 | 5253 | * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. |
a0a1a5fd | 5254 | */ |
6ba94429 | 5255 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) |
a0a1a5fd | 5256 | { |
6ba94429 | 5257 | struct wq_device *wq_dev = wq->wq_dev; |
8b03ae3c | 5258 | |
6ba94429 FW |
5259 | if (!wq->wq_dev) |
5260 | return; | |
a0a1a5fd | 5261 | |
6ba94429 FW |
5262 | wq->wq_dev = NULL; |
5263 | device_unregister(&wq_dev->dev); | |
a0a1a5fd | 5264 | } |
6ba94429 FW |
5265 | #else /* CONFIG_SYSFS */ |
5266 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } | |
5267 | #endif /* CONFIG_SYSFS */ | |
a0a1a5fd | 5268 | |
82607adc TH |
5269 | /* |
5270 | * Workqueue watchdog. | |
5271 | * | |
5272 | * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal | |
5273 | * flush dependency, a concurrency managed work item which stays RUNNING | |
5274 | * indefinitely. Workqueue stalls can be very difficult to debug as the | |
5275 | * usual warning mechanisms don't trigger and internal workqueue state is | |
5276 | * largely opaque. | |
5277 | * | |
5278 | * Workqueue watchdog monitors all worker pools periodically and dumps | |
5279 | * state if some pools failed to make forward progress for a while where | |
5280 | * forward progress is defined as the first item on ->worklist changing. | |
5281 | * | |
5282 | * This mechanism is controlled through the kernel parameter | |
5283 | * "workqueue.watchdog_thresh" which can be updated at runtime through the | |
5284 | * corresponding sysfs parameter file. | |
5285 | */ | |
5286 | #ifdef CONFIG_WQ_WATCHDOG | |
5287 | ||
5288 | static void wq_watchdog_timer_fn(unsigned long data); | |
5289 | ||
5290 | static unsigned long wq_watchdog_thresh = 30; | |
5291 | static struct timer_list wq_watchdog_timer = | |
5292 | TIMER_DEFERRED_INITIALIZER(wq_watchdog_timer_fn, 0, 0); | |
5293 | ||
5294 | static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; | |
5295 | static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; | |
5296 | ||
5297 | static void wq_watchdog_reset_touched(void) | |
5298 | { | |
5299 | int cpu; | |
5300 | ||
5301 | wq_watchdog_touched = jiffies; | |
5302 | for_each_possible_cpu(cpu) | |
5303 | per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; | |
5304 | } | |
5305 | ||
5306 | static void wq_watchdog_timer_fn(unsigned long data) | |
5307 | { | |
5308 | unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; | |
5309 | bool lockup_detected = false; | |
5310 | struct worker_pool *pool; | |
5311 | int pi; | |
5312 | ||
5313 | if (!thresh) | |
5314 | return; | |
5315 | ||
5316 | rcu_read_lock(); | |
5317 | ||
5318 | for_each_pool(pool, pi) { | |
5319 | unsigned long pool_ts, touched, ts; | |
5320 | ||
5321 | if (list_empty(&pool->worklist)) | |
5322 | continue; | |
5323 | ||
5324 | /* get the latest of pool and touched timestamps */ | |
5325 | pool_ts = READ_ONCE(pool->watchdog_ts); | |
5326 | touched = READ_ONCE(wq_watchdog_touched); | |
5327 | ||
5328 | if (time_after(pool_ts, touched)) | |
5329 | ts = pool_ts; | |
5330 | else | |
5331 | ts = touched; | |
5332 | ||
5333 | if (pool->cpu >= 0) { | |
5334 | unsigned long cpu_touched = | |
5335 | READ_ONCE(per_cpu(wq_watchdog_touched_cpu, | |
5336 | pool->cpu)); | |
5337 | if (time_after(cpu_touched, ts)) | |
5338 | ts = cpu_touched; | |
5339 | } | |
5340 | ||
5341 | /* did we stall? */ | |
5342 | if (time_after(jiffies, ts + thresh)) { | |
5343 | lockup_detected = true; | |
5344 | pr_emerg("BUG: workqueue lockup - pool"); | |
5345 | pr_cont_pool_info(pool); | |
5346 | pr_cont(" stuck for %us!\n", | |
5347 | jiffies_to_msecs(jiffies - pool_ts) / 1000); | |
5348 | } | |
5349 | } | |
5350 | ||
5351 | rcu_read_unlock(); | |
5352 | ||
5353 | if (lockup_detected) | |
5354 | show_workqueue_state(); | |
5355 | ||
5356 | wq_watchdog_reset_touched(); | |
5357 | mod_timer(&wq_watchdog_timer, jiffies + thresh); | |
5358 | } | |
5359 | ||
5360 | void wq_watchdog_touch(int cpu) | |
5361 | { | |
5362 | if (cpu >= 0) | |
5363 | per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; | |
5364 | else | |
5365 | wq_watchdog_touched = jiffies; | |
5366 | } | |
5367 | ||
5368 | static void wq_watchdog_set_thresh(unsigned long thresh) | |
5369 | { | |
5370 | wq_watchdog_thresh = 0; | |
5371 | del_timer_sync(&wq_watchdog_timer); | |
5372 | ||
5373 | if (thresh) { | |
5374 | wq_watchdog_thresh = thresh; | |
5375 | wq_watchdog_reset_touched(); | |
5376 | mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ); | |
5377 | } | |
5378 | } | |
5379 | ||
5380 | static int wq_watchdog_param_set_thresh(const char *val, | |
5381 | const struct kernel_param *kp) | |
5382 | { | |
5383 | unsigned long thresh; | |
5384 | int ret; | |
5385 | ||
5386 | ret = kstrtoul(val, 0, &thresh); | |
5387 | if (ret) | |
5388 | return ret; | |
5389 | ||
5390 | if (system_wq) | |
5391 | wq_watchdog_set_thresh(thresh); | |
5392 | else | |
5393 | wq_watchdog_thresh = thresh; | |
5394 | ||
5395 | return 0; | |
5396 | } | |
5397 | ||
5398 | static const struct kernel_param_ops wq_watchdog_thresh_ops = { | |
5399 | .set = wq_watchdog_param_set_thresh, | |
5400 | .get = param_get_ulong, | |
5401 | }; | |
5402 | ||
5403 | module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, | |
5404 | 0644); | |
5405 | ||
5406 | static void wq_watchdog_init(void) | |
5407 | { | |
5408 | wq_watchdog_set_thresh(wq_watchdog_thresh); | |
5409 | } | |
5410 | ||
5411 | #else /* CONFIG_WQ_WATCHDOG */ | |
5412 | ||
5413 | static inline void wq_watchdog_init(void) { } | |
5414 | ||
5415 | #endif /* CONFIG_WQ_WATCHDOG */ | |
5416 | ||
bce90380 TH |
5417 | static void __init wq_numa_init(void) |
5418 | { | |
5419 | cpumask_var_t *tbl; | |
5420 | int node, cpu; | |
5421 | ||
bce90380 TH |
5422 | if (num_possible_nodes() <= 1) |
5423 | return; | |
5424 | ||
d55262c4 TH |
5425 | if (wq_disable_numa) { |
5426 | pr_info("workqueue: NUMA affinity support disabled\n"); | |
5427 | return; | |
5428 | } | |
5429 | ||
4c16bd32 TH |
5430 | wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL); |
5431 | BUG_ON(!wq_update_unbound_numa_attrs_buf); | |
5432 | ||
bce90380 TH |
5433 | /* |
5434 | * We want masks of possible CPUs of each node which isn't readily | |
5435 | * available. Build one from cpu_to_node() which should have been | |
5436 | * fully initialized by now. | |
5437 | */ | |
ddcb57e2 | 5438 | tbl = kzalloc(nr_node_ids * sizeof(tbl[0]), GFP_KERNEL); |
bce90380 TH |
5439 | BUG_ON(!tbl); |
5440 | ||
5441 | for_each_node(node) | |
5a6024f1 | 5442 | BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL, |
1be0c25d | 5443 | node_online(node) ? node : NUMA_NO_NODE)); |
bce90380 TH |
5444 | |
5445 | for_each_possible_cpu(cpu) { | |
5446 | node = cpu_to_node(cpu); | |
5447 | if (WARN_ON(node == NUMA_NO_NODE)) { | |
5448 | pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); | |
5449 | /* happens iff arch is bonkers, let's just proceed */ | |
5450 | return; | |
5451 | } | |
5452 | cpumask_set_cpu(cpu, tbl[node]); | |
5453 | } | |
5454 | ||
5455 | wq_numa_possible_cpumask = tbl; | |
5456 | wq_numa_enabled = true; | |
5457 | } | |
5458 | ||
6ee0578b | 5459 | static int __init init_workqueues(void) |
1da177e4 | 5460 | { |
7a4e344c TH |
5461 | int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; |
5462 | int i, cpu; | |
c34056a3 | 5463 | |
e904e6c2 TH |
5464 | WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); |
5465 | ||
b05a7928 FW |
5466 | BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); |
5467 | cpumask_copy(wq_unbound_cpumask, cpu_possible_mask); | |
5468 | ||
e904e6c2 TH |
5469 | pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); |
5470 | ||
65758202 | 5471 | cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); |
a5b4e57d | 5472 | hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); |
8b03ae3c | 5473 | |
bce90380 TH |
5474 | wq_numa_init(); |
5475 | ||
706026c2 | 5476 | /* initialize CPU pools */ |
29c91e99 | 5477 | for_each_possible_cpu(cpu) { |
4ce62e9e | 5478 | struct worker_pool *pool; |
8b03ae3c | 5479 | |
7a4e344c | 5480 | i = 0; |
f02ae73a | 5481 | for_each_cpu_worker_pool(pool, cpu) { |
7a4e344c | 5482 | BUG_ON(init_worker_pool(pool)); |
ec22ca5e | 5483 | pool->cpu = cpu; |
29c91e99 | 5484 | cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); |
7a4e344c | 5485 | pool->attrs->nice = std_nice[i++]; |
f3f90ad4 | 5486 | pool->node = cpu_to_node(cpu); |
7a4e344c | 5487 | |
9daf9e67 | 5488 | /* alloc pool ID */ |
68e13a67 | 5489 | mutex_lock(&wq_pool_mutex); |
9daf9e67 | 5490 | BUG_ON(worker_pool_assign_id(pool)); |
68e13a67 | 5491 | mutex_unlock(&wq_pool_mutex); |
4ce62e9e | 5492 | } |
8b03ae3c TH |
5493 | } |
5494 | ||
e22bee78 | 5495 | /* create the initial worker */ |
29c91e99 | 5496 | for_each_online_cpu(cpu) { |
4ce62e9e | 5497 | struct worker_pool *pool; |
e22bee78 | 5498 | |
f02ae73a | 5499 | for_each_cpu_worker_pool(pool, cpu) { |
29c91e99 | 5500 | pool->flags &= ~POOL_DISASSOCIATED; |
051e1850 | 5501 | BUG_ON(!create_worker(pool)); |
4ce62e9e | 5502 | } |
e22bee78 TH |
5503 | } |
5504 | ||
8a2b7538 | 5505 | /* create default unbound and ordered wq attrs */ |
29c91e99 TH |
5506 | for (i = 0; i < NR_STD_WORKER_POOLS; i++) { |
5507 | struct workqueue_attrs *attrs; | |
5508 | ||
5509 | BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); | |
29c91e99 | 5510 | attrs->nice = std_nice[i]; |
29c91e99 | 5511 | unbound_std_wq_attrs[i] = attrs; |
8a2b7538 TH |
5512 | |
5513 | /* | |
5514 | * An ordered wq should have only one pwq as ordering is | |
5515 | * guaranteed by max_active which is enforced by pwqs. | |
5516 | * Turn off NUMA so that dfl_pwq is used for all nodes. | |
5517 | */ | |
5518 | BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); | |
5519 | attrs->nice = std_nice[i]; | |
5520 | attrs->no_numa = true; | |
5521 | ordered_wq_attrs[i] = attrs; | |
29c91e99 TH |
5522 | } |
5523 | ||
d320c038 | 5524 | system_wq = alloc_workqueue("events", 0, 0); |
1aabe902 | 5525 | system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); |
d320c038 | 5526 | system_long_wq = alloc_workqueue("events_long", 0, 0); |
f3421797 TH |
5527 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
5528 | WQ_UNBOUND_MAX_ACTIVE); | |
24d51add TH |
5529 | system_freezable_wq = alloc_workqueue("events_freezable", |
5530 | WQ_FREEZABLE, 0); | |
0668106c VK |
5531 | system_power_efficient_wq = alloc_workqueue("events_power_efficient", |
5532 | WQ_POWER_EFFICIENT, 0); | |
5533 | system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", | |
5534 | WQ_FREEZABLE | WQ_POWER_EFFICIENT, | |
5535 | 0); | |
1aabe902 | 5536 | BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || |
0668106c VK |
5537 | !system_unbound_wq || !system_freezable_wq || |
5538 | !system_power_efficient_wq || | |
5539 | !system_freezable_power_efficient_wq); | |
82607adc TH |
5540 | |
5541 | wq_watchdog_init(); | |
5542 | ||
6ee0578b | 5543 | return 0; |
1da177e4 | 5544 | } |
6ee0578b | 5545 | early_initcall(init_workqueues); |