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Commit | Line | Data |
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1da177e4 LT |
1 | /* Kernel thread helper functions. |
2 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. | |
3 | * | |
73c27992 | 4 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
5 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
6 | * etc.). | |
7 | */ | |
ae7e81c0 | 8 | #include <uapi/linux/sched/types.h> |
1da177e4 | 9 | #include <linux/sched.h> |
29930025 | 10 | #include <linux/sched/task.h> |
1da177e4 LT |
11 | #include <linux/kthread.h> |
12 | #include <linux/completion.h> | |
13 | #include <linux/err.h> | |
58568d2a | 14 | #include <linux/cpuset.h> |
1da177e4 LT |
15 | #include <linux/unistd.h> |
16 | #include <linux/file.h> | |
9984de1a | 17 | #include <linux/export.h> |
97d1f15b | 18 | #include <linux/mutex.h> |
b56c0d89 TH |
19 | #include <linux/slab.h> |
20 | #include <linux/freezer.h> | |
a74fb73c | 21 | #include <linux/ptrace.h> |
cd42d559 | 22 | #include <linux/uaccess.h> |
ad8d75ff | 23 | #include <trace/events/sched.h> |
1da177e4 | 24 | |
73c27992 EB |
25 | static DEFINE_SPINLOCK(kthread_create_lock); |
26 | static LIST_HEAD(kthread_create_list); | |
27 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
28 | |
29 | struct kthread_create_info | |
30 | { | |
73c27992 | 31 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
32 | int (*threadfn)(void *data); |
33 | void *data; | |
207205a2 | 34 | int node; |
1da177e4 | 35 | |
73c27992 | 36 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 37 | struct task_struct *result; |
786235ee | 38 | struct completion *done; |
65f27f38 | 39 | |
73c27992 | 40 | struct list_head list; |
1da177e4 LT |
41 | }; |
42 | ||
63706172 | 43 | struct kthread { |
2a1d4460 TG |
44 | unsigned long flags; |
45 | unsigned int cpu; | |
82805ab7 | 46 | void *data; |
2a1d4460 | 47 | struct completion parked; |
63706172 | 48 | struct completion exited; |
0b508bc9 | 49 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
50 | struct cgroup_subsys_state *blkcg_css; |
51 | #endif | |
1da177e4 LT |
52 | }; |
53 | ||
2a1d4460 TG |
54 | enum KTHREAD_BITS { |
55 | KTHREAD_IS_PER_CPU = 0, | |
56 | KTHREAD_SHOULD_STOP, | |
57 | KTHREAD_SHOULD_PARK, | |
2a1d4460 TG |
58 | }; |
59 | ||
1da5c46f ON |
60 | static inline void set_kthread_struct(void *kthread) |
61 | { | |
62 | /* | |
63 | * We abuse ->set_child_tid to avoid the new member and because it | |
64 | * can't be wrongly copied by copy_process(). We also rely on fact | |
65 | * that the caller can't exec, so PF_KTHREAD can't be cleared. | |
66 | */ | |
67 | current->set_child_tid = (__force void __user *)kthread; | |
68 | } | |
4ecdafc8 ON |
69 | |
70 | static inline struct kthread *to_kthread(struct task_struct *k) | |
71 | { | |
1da5c46f ON |
72 | WARN_ON(!(k->flags & PF_KTHREAD)); |
73 | return (__force void *)k->set_child_tid; | |
4ecdafc8 ON |
74 | } |
75 | ||
1da5c46f ON |
76 | void free_kthread_struct(struct task_struct *k) |
77 | { | |
05e3db95 SL |
78 | struct kthread *kthread; |
79 | ||
1da5c46f ON |
80 | /* |
81 | * Can be NULL if this kthread was created by kernel_thread() | |
82 | * or if kmalloc() in kthread() failed. | |
83 | */ | |
05e3db95 | 84 | kthread = to_kthread(k); |
0b508bc9 | 85 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
86 | WARN_ON_ONCE(kthread && kthread->blkcg_css); |
87 | #endif | |
88 | kfree(kthread); | |
1da5c46f ON |
89 | } |
90 | ||
9e37bd30 RD |
91 | /** |
92 | * kthread_should_stop - should this kthread return now? | |
93 | * | |
72fd4a35 | 94 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
95 | * and this will return true. You should then return, and your return |
96 | * value will be passed through to kthread_stop(). | |
97 | */ | |
2a1d4460 | 98 | bool kthread_should_stop(void) |
1da177e4 | 99 | { |
2a1d4460 | 100 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
101 | } |
102 | EXPORT_SYMBOL(kthread_should_stop); | |
103 | ||
2a1d4460 TG |
104 | /** |
105 | * kthread_should_park - should this kthread park now? | |
106 | * | |
107 | * When someone calls kthread_park() on your kthread, it will be woken | |
108 | * and this will return true. You should then do the necessary | |
109 | * cleanup and call kthread_parkme() | |
110 | * | |
111 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
112 | * and in a park position. kthread_unpark() "restarts" the thread and | |
113 | * calls the thread function again. | |
114 | */ | |
115 | bool kthread_should_park(void) | |
116 | { | |
117 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags); | |
118 | } | |
18896451 | 119 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 120 | |
8a32c441 TH |
121 | /** |
122 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
123 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
124 | * | |
125 | * kthread_should_stop() for freezable kthreads, which will enter | |
126 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
127 | * freezer deadlock and freezable kthreads should use this function instead | |
128 | * of calling try_to_freeze() directly. | |
129 | */ | |
130 | bool kthread_freezable_should_stop(bool *was_frozen) | |
131 | { | |
132 | bool frozen = false; | |
133 | ||
134 | might_sleep(); | |
135 | ||
136 | if (unlikely(freezing(current))) | |
137 | frozen = __refrigerator(true); | |
138 | ||
139 | if (was_frozen) | |
140 | *was_frozen = frozen; | |
141 | ||
142 | return kthread_should_stop(); | |
143 | } | |
144 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
145 | ||
82805ab7 TH |
146 | /** |
147 | * kthread_data - return data value specified on kthread creation | |
148 | * @task: kthread task in question | |
149 | * | |
150 | * Return the data value specified when kthread @task was created. | |
151 | * The caller is responsible for ensuring the validity of @task when | |
152 | * calling this function. | |
153 | */ | |
154 | void *kthread_data(struct task_struct *task) | |
155 | { | |
156 | return to_kthread(task)->data; | |
157 | } | |
158 | ||
cd42d559 | 159 | /** |
e700591a | 160 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
161 | * @task: possible kthread task in question |
162 | * | |
163 | * @task could be a kthread task. Return the data value specified when it | |
164 | * was created if accessible. If @task isn't a kthread task or its data is | |
165 | * inaccessible for any reason, %NULL is returned. This function requires | |
166 | * that @task itself is safe to dereference. | |
167 | */ | |
e700591a | 168 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 TH |
169 | { |
170 | struct kthread *kthread = to_kthread(task); | |
171 | void *data = NULL; | |
172 | ||
173 | probe_kernel_read(&data, &kthread->data, sizeof(data)); | |
174 | return data; | |
175 | } | |
176 | ||
2a1d4460 TG |
177 | static void __kthread_parkme(struct kthread *self) |
178 | { | |
d088bcca PZ |
179 | for (;;) { |
180 | set_current_state(TASK_PARKED); | |
181 | if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) | |
182 | break; | |
2a1d4460 | 183 | schedule(); |
2a1d4460 | 184 | } |
2a1d4460 TG |
185 | __set_current_state(TASK_RUNNING); |
186 | } | |
187 | ||
188 | void kthread_parkme(void) | |
189 | { | |
190 | __kthread_parkme(to_kthread(current)); | |
191 | } | |
18896451 | 192 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 193 | |
605478e2 PZ |
194 | void kthread_park_complete(struct task_struct *k) |
195 | { | |
196 | complete(&to_kthread(k)->parked); | |
197 | } | |
198 | ||
1da177e4 LT |
199 | static int kthread(void *_create) |
200 | { | |
63706172 | 201 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 202 | struct kthread_create_info *create = _create; |
63706172 ON |
203 | int (*threadfn)(void *data) = create->threadfn; |
204 | void *data = create->data; | |
786235ee | 205 | struct completion *done; |
1da5c46f | 206 | struct kthread *self; |
63706172 | 207 | int ret; |
1da177e4 | 208 | |
e10237cc | 209 | self = kzalloc(sizeof(*self), GFP_KERNEL); |
1da5c46f | 210 | set_kthread_struct(self); |
1da177e4 | 211 | |
786235ee TH |
212 | /* If user was SIGKILLed, I release the structure. */ |
213 | done = xchg(&create->done, NULL); | |
214 | if (!done) { | |
215 | kfree(create); | |
216 | do_exit(-EINTR); | |
217 | } | |
1da5c46f ON |
218 | |
219 | if (!self) { | |
220 | create->result = ERR_PTR(-ENOMEM); | |
221 | complete(done); | |
222 | do_exit(-ENOMEM); | |
223 | } | |
224 | ||
1da5c46f ON |
225 | self->data = data; |
226 | init_completion(&self->exited); | |
227 | init_completion(&self->parked); | |
228 | current->vfork_done = &self->exited; | |
229 | ||
1da177e4 | 230 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 231 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 232 | create->result = current; |
786235ee | 233 | complete(done); |
1da177e4 LT |
234 | schedule(); |
235 | ||
63706172 | 236 | ret = -EINTR; |
1da5c46f | 237 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
77f88796 | 238 | cgroup_kthread_ready(); |
1da5c46f | 239 | __kthread_parkme(self); |
2a1d4460 TG |
240 | ret = threadfn(data); |
241 | } | |
63706172 | 242 | do_exit(ret); |
1da177e4 LT |
243 | } |
244 | ||
207205a2 ED |
245 | /* called from do_fork() to get node information for about to be created task */ |
246 | int tsk_fork_get_node(struct task_struct *tsk) | |
247 | { | |
248 | #ifdef CONFIG_NUMA | |
249 | if (tsk == kthreadd_task) | |
250 | return tsk->pref_node_fork; | |
251 | #endif | |
81c98869 | 252 | return NUMA_NO_NODE; |
207205a2 ED |
253 | } |
254 | ||
73c27992 | 255 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 256 | { |
1da177e4 LT |
257 | int pid; |
258 | ||
207205a2 ED |
259 | #ifdef CONFIG_NUMA |
260 | current->pref_node_fork = create->node; | |
261 | #endif | |
1da177e4 LT |
262 | /* We want our own signal handler (we take no signals by default). */ |
263 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 264 | if (pid < 0) { |
786235ee TH |
265 | /* If user was SIGKILLed, I release the structure. */ |
266 | struct completion *done = xchg(&create->done, NULL); | |
267 | ||
268 | if (!done) { | |
269 | kfree(create); | |
270 | return; | |
271 | } | |
1da177e4 | 272 | create->result = ERR_PTR(pid); |
786235ee | 273 | complete(done); |
cdd140bd | 274 | } |
1da177e4 LT |
275 | } |
276 | ||
c0b942a7 NI |
277 | static __printf(4, 0) |
278 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
279 | void *data, int node, |
280 | const char namefmt[], | |
281 | va_list args) | |
1da177e4 | 282 | { |
786235ee TH |
283 | DECLARE_COMPLETION_ONSTACK(done); |
284 | struct task_struct *task; | |
285 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
286 | GFP_KERNEL); | |
287 | ||
288 | if (!create) | |
289 | return ERR_PTR(-ENOMEM); | |
290 | create->threadfn = threadfn; | |
291 | create->data = data; | |
292 | create->node = node; | |
293 | create->done = &done; | |
73c27992 EB |
294 | |
295 | spin_lock(&kthread_create_lock); | |
786235ee | 296 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
297 | spin_unlock(&kthread_create_lock); |
298 | ||
cbd9b67b | 299 | wake_up_process(kthreadd_task); |
786235ee TH |
300 | /* |
301 | * Wait for completion in killable state, for I might be chosen by | |
302 | * the OOM killer while kthreadd is trying to allocate memory for | |
303 | * new kernel thread. | |
304 | */ | |
305 | if (unlikely(wait_for_completion_killable(&done))) { | |
a0987ba0 TH |
306 | int i = 0; |
307 | ||
308 | /* | |
309 | * I got SIGKILL, but wait for 10 more seconds for completion | |
310 | * unless chosen by the OOM killer. This delay is there as a | |
311 | * workaround for boot failure caused by SIGKILL upon device | |
312 | * driver initialization timeout. | |
313 | */ | |
314 | while (i++ < 10 && !test_tsk_thread_flag(current, TIF_MEMDIE)) | |
315 | if (wait_for_completion_timeout(&done, HZ)) | |
316 | goto ready; | |
786235ee TH |
317 | /* |
318 | * If I was SIGKILLed before kthreadd (or new kernel thread) | |
319 | * calls complete(), leave the cleanup of this structure to | |
320 | * that thread. | |
321 | */ | |
322 | if (xchg(&create->done, NULL)) | |
8fe6929c | 323 | return ERR_PTR(-EINTR); |
786235ee TH |
324 | /* |
325 | * kthreadd (or new kernel thread) will call complete() | |
326 | * shortly. | |
327 | */ | |
328 | wait_for_completion(&done); | |
329 | } | |
a0987ba0 | 330 | ready: |
786235ee TH |
331 | task = create->result; |
332 | if (!IS_ERR(task)) { | |
c9b5f501 | 333 | static const struct sched_param param = { .sched_priority = 0 }; |
1c99315b | 334 | |
786235ee | 335 | vsnprintf(task->comm, sizeof(task->comm), namefmt, args); |
1c99315b ON |
336 | /* |
337 | * root may have changed our (kthreadd's) priority or CPU mask. | |
338 | * The kernel thread should not inherit these properties. | |
339 | */ | |
786235ee TH |
340 | sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
341 | set_cpus_allowed_ptr(task, cpu_all_mask); | |
1da177e4 | 342 | } |
786235ee TH |
343 | kfree(create); |
344 | return task; | |
1da177e4 | 345 | } |
255451e4 PM |
346 | |
347 | /** | |
348 | * kthread_create_on_node - create a kthread. | |
349 | * @threadfn: the function to run until signal_pending(current). | |
350 | * @data: data ptr for @threadfn. | |
351 | * @node: task and thread structures for the thread are allocated on this node | |
352 | * @namefmt: printf-style name for the thread. | |
353 | * | |
354 | * Description: This helper function creates and names a kernel | |
355 | * thread. The thread will be stopped: use wake_up_process() to start | |
356 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
357 | * is affine to all CPUs. | |
358 | * | |
359 | * If thread is going to be bound on a particular cpu, give its node | |
360 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
361 | * When woken, the thread will run @threadfn() with @data as its | |
362 | * argument. @threadfn() can either call do_exit() directly if it is a | |
363 | * standalone thread for which no one will call kthread_stop(), or | |
364 | * return when 'kthread_should_stop()' is true (which means | |
365 | * kthread_stop() has been called). The return value should be zero | |
366 | * or a negative error number; it will be passed to kthread_stop(). | |
367 | * | |
368 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
369 | */ | |
370 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
371 | void *data, int node, | |
372 | const char namefmt[], | |
373 | ...) | |
374 | { | |
375 | struct task_struct *task; | |
376 | va_list args; | |
377 | ||
378 | va_start(args, namefmt); | |
379 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
380 | va_end(args); | |
381 | ||
382 | return task; | |
383 | } | |
207205a2 | 384 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 385 | |
25834c73 | 386 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
2a1d4460 | 387 | { |
25834c73 PZ |
388 | unsigned long flags; |
389 | ||
f2530dc7 TG |
390 | if (!wait_task_inactive(p, state)) { |
391 | WARN_ON(1); | |
392 | return; | |
393 | } | |
25834c73 | 394 | |
2a1d4460 | 395 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
396 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
397 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 398 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
399 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
400 | } | |
401 | ||
402 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) | |
403 | { | |
404 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
405 | } | |
406 | ||
407 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
408 | { | |
409 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
410 | } |
411 | ||
881232b7 PZ |
412 | /** |
413 | * kthread_bind - bind a just-created kthread to a cpu. | |
414 | * @p: thread created by kthread_create(). | |
415 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
416 | * | |
417 | * Description: This function is equivalent to set_cpus_allowed(), | |
418 | * except that @cpu doesn't need to be online, and the thread must be | |
419 | * stopped (i.e., just returned from kthread_create()). | |
420 | */ | |
421 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
422 | { | |
f2530dc7 | 423 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
424 | } |
425 | EXPORT_SYMBOL(kthread_bind); | |
426 | ||
2a1d4460 TG |
427 | /** |
428 | * kthread_create_on_cpu - Create a cpu bound kthread | |
429 | * @threadfn: the function to run until signal_pending(current). | |
430 | * @data: data ptr for @threadfn. | |
431 | * @cpu: The cpu on which the thread should be bound, | |
432 | * @namefmt: printf-style name for the thread. Format is restricted | |
433 | * to "name.*%u". Code fills in cpu number. | |
434 | * | |
435 | * Description: This helper function creates and names a kernel thread | |
436 | * The thread will be woken and put into park mode. | |
437 | */ | |
438 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
439 | void *data, unsigned int cpu, | |
440 | const char *namefmt) | |
441 | { | |
442 | struct task_struct *p; | |
443 | ||
10922838 | 444 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
445 | cpu); |
446 | if (IS_ERR(p)) | |
447 | return p; | |
a65d4096 PM |
448 | kthread_bind(p, cpu); |
449 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 TG |
450 | set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); |
451 | to_kthread(p)->cpu = cpu; | |
2a1d4460 TG |
452 | return p; |
453 | } | |
454 | ||
cf380a4a ON |
455 | /** |
456 | * kthread_unpark - unpark a thread created by kthread_create(). | |
457 | * @k: thread created by kthread_create(). | |
458 | * | |
459 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
460 | * waits for it to return. If the thread is marked percpu then its | |
461 | * bound to the cpu again. | |
462 | */ | |
463 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 464 | { |
cf380a4a ON |
465 | struct kthread *kthread = to_kthread(k); |
466 | ||
f2530dc7 | 467 | /* |
605478e2 PZ |
468 | * Newly created kthread was parked when the CPU was offline. |
469 | * The binding was lost and we need to set it again. | |
f2530dc7 | 470 | */ |
605478e2 PZ |
471 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
472 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
473 | ||
474 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
475 | wake_up_state(k, TASK_PARKED); | |
f2530dc7 | 476 | } |
18896451 | 477 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
478 | |
479 | /** | |
480 | * kthread_park - park a thread created by kthread_create(). | |
481 | * @k: thread created by kthread_create(). | |
482 | * | |
483 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
484 | * waits for it to return. This can also be called after kthread_create() | |
485 | * instead of calling wake_up_process(): the thread will park without | |
486 | * calling threadfn(). | |
487 | * | |
488 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
489 | * If called by the kthread itself just the park bit is set. | |
490 | */ | |
491 | int kthread_park(struct task_struct *k) | |
492 | { | |
cf380a4a ON |
493 | struct kthread *kthread = to_kthread(k); |
494 | ||
495 | if (WARN_ON(k->flags & PF_EXITING)) | |
496 | return -ENOSYS; | |
497 | ||
605478e2 PZ |
498 | if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) |
499 | return -EBUSY; | |
500 | ||
501 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
502 | if (k != current) { | |
503 | wake_up_process(k); | |
504 | wait_for_completion(&kthread->parked); | |
2a1d4460 | 505 | } |
cf380a4a ON |
506 | |
507 | return 0; | |
2a1d4460 | 508 | } |
18896451 | 509 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 510 | |
9e37bd30 RD |
511 | /** |
512 | * kthread_stop - stop a thread created by kthread_create(). | |
513 | * @k: thread created by kthread_create(). | |
514 | * | |
515 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
516 | * waits for it to exit. This can also be called after kthread_create() |
517 | * instead of calling wake_up_process(): the thread will exit without | |
518 | * calling threadfn(). | |
519 | * | |
520 | * If threadfn() may call do_exit() itself, the caller must ensure | |
521 | * task_struct can't go away. | |
9e37bd30 RD |
522 | * |
523 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
524 | * was never called. | |
525 | */ | |
1da177e4 LT |
526 | int kthread_stop(struct task_struct *k) |
527 | { | |
b5c5442b | 528 | struct kthread *kthread; |
1da177e4 LT |
529 | int ret; |
530 | ||
0a16b607 | 531 | trace_sched_kthread_stop(k); |
b5c5442b ON |
532 | |
533 | get_task_struct(k); | |
efb29fbf ON |
534 | kthread = to_kthread(k); |
535 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 536 | kthread_unpark(k); |
efb29fbf ON |
537 | wake_up_process(k); |
538 | wait_for_completion(&kthread->exited); | |
63706172 | 539 | ret = k->exit_code; |
1da177e4 | 540 | put_task_struct(k); |
0a16b607 | 541 | |
b5c5442b | 542 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
543 | return ret; |
544 | } | |
52e92e57 | 545 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 546 | |
e804a4a4 | 547 | int kthreadd(void *unused) |
1da177e4 | 548 | { |
73c27992 | 549 | struct task_struct *tsk = current; |
1da177e4 | 550 | |
e804a4a4 | 551 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 552 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 553 | ignore_signals(tsk); |
1a2142af | 554 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa4 | 555 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 556 | |
34b087e4 | 557 | current->flags |= PF_NOFREEZE; |
77f88796 | 558 | cgroup_init_kthreadd(); |
73c27992 EB |
559 | |
560 | for (;;) { | |
561 | set_current_state(TASK_INTERRUPTIBLE); | |
562 | if (list_empty(&kthread_create_list)) | |
563 | schedule(); | |
564 | __set_current_state(TASK_RUNNING); | |
565 | ||
566 | spin_lock(&kthread_create_lock); | |
567 | while (!list_empty(&kthread_create_list)) { | |
568 | struct kthread_create_info *create; | |
569 | ||
570 | create = list_entry(kthread_create_list.next, | |
571 | struct kthread_create_info, list); | |
572 | list_del_init(&create->list); | |
573 | spin_unlock(&kthread_create_lock); | |
574 | ||
575 | create_kthread(create); | |
576 | ||
577 | spin_lock(&kthread_create_lock); | |
578 | } | |
579 | spin_unlock(&kthread_create_lock); | |
580 | } | |
581 | ||
582 | return 0; | |
583 | } | |
b56c0d89 | 584 | |
3989144f | 585 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
586 | const char *name, |
587 | struct lock_class_key *key) | |
588 | { | |
dbf52682 | 589 | memset(worker, 0, sizeof(struct kthread_worker)); |
4f32e9b1 YZ |
590 | spin_lock_init(&worker->lock); |
591 | lockdep_set_class_and_name(&worker->lock, key, name); | |
592 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 593 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 594 | } |
3989144f | 595 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 596 | |
b56c0d89 TH |
597 | /** |
598 | * kthread_worker_fn - kthread function to process kthread_worker | |
599 | * @worker_ptr: pointer to initialized kthread_worker | |
600 | * | |
fbae2d44 PM |
601 | * This function implements the main cycle of kthread worker. It processes |
602 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
603 | * is empty. | |
b56c0d89 | 604 | * |
fbae2d44 PM |
605 | * The works are not allowed to keep any locks, disable preemption or interrupts |
606 | * when they finish. There is defined a safe point for freezing when one work | |
607 | * finishes and before a new one is started. | |
8197b3d4 PM |
608 | * |
609 | * Also the works must not be handled by more than one worker at the same time, | |
610 | * see also kthread_queue_work(). | |
b56c0d89 TH |
611 | */ |
612 | int kthread_worker_fn(void *worker_ptr) | |
613 | { | |
614 | struct kthread_worker *worker = worker_ptr; | |
615 | struct kthread_work *work; | |
616 | ||
fbae2d44 PM |
617 | /* |
618 | * FIXME: Update the check and remove the assignment when all kthread | |
619 | * worker users are created using kthread_create_worker*() functions. | |
620 | */ | |
621 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 622 | worker->task = current; |
dbf52682 PM |
623 | |
624 | if (worker->flags & KTW_FREEZABLE) | |
625 | set_freezable(); | |
626 | ||
b56c0d89 TH |
627 | repeat: |
628 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
629 | ||
630 | if (kthread_should_stop()) { | |
631 | __set_current_state(TASK_RUNNING); | |
632 | spin_lock_irq(&worker->lock); | |
633 | worker->task = NULL; | |
634 | spin_unlock_irq(&worker->lock); | |
635 | return 0; | |
636 | } | |
637 | ||
638 | work = NULL; | |
639 | spin_lock_irq(&worker->lock); | |
640 | if (!list_empty(&worker->work_list)) { | |
641 | work = list_first_entry(&worker->work_list, | |
642 | struct kthread_work, node); | |
643 | list_del_init(&work->node); | |
644 | } | |
46f3d976 | 645 | worker->current_work = work; |
b56c0d89 TH |
646 | spin_unlock_irq(&worker->lock); |
647 | ||
648 | if (work) { | |
649 | __set_current_state(TASK_RUNNING); | |
650 | work->func(work); | |
b56c0d89 TH |
651 | } else if (!freezing(current)) |
652 | schedule(); | |
653 | ||
654 | try_to_freeze(); | |
22cf8bc6 | 655 | cond_resched(); |
b56c0d89 TH |
656 | goto repeat; |
657 | } | |
658 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
659 | ||
c0b942a7 | 660 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
661 | __kthread_create_worker(int cpu, unsigned int flags, |
662 | const char namefmt[], va_list args) | |
fbae2d44 PM |
663 | { |
664 | struct kthread_worker *worker; | |
665 | struct task_struct *task; | |
8fb9dcbd | 666 | int node = -1; |
fbae2d44 PM |
667 | |
668 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
669 | if (!worker) | |
670 | return ERR_PTR(-ENOMEM); | |
671 | ||
672 | kthread_init_worker(worker); | |
673 | ||
8fb9dcbd ON |
674 | if (cpu >= 0) |
675 | node = cpu_to_node(cpu); | |
fbae2d44 | 676 | |
8fb9dcbd ON |
677 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
678 | node, namefmt, args); | |
fbae2d44 PM |
679 | if (IS_ERR(task)) |
680 | goto fail_task; | |
681 | ||
8fb9dcbd ON |
682 | if (cpu >= 0) |
683 | kthread_bind(task, cpu); | |
684 | ||
dbf52682 | 685 | worker->flags = flags; |
fbae2d44 PM |
686 | worker->task = task; |
687 | wake_up_process(task); | |
688 | return worker; | |
689 | ||
690 | fail_task: | |
691 | kfree(worker); | |
692 | return ERR_CAST(task); | |
693 | } | |
694 | ||
695 | /** | |
696 | * kthread_create_worker - create a kthread worker | |
dbf52682 | 697 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
698 | * @namefmt: printf-style name for the kthread worker (task). |
699 | * | |
700 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
701 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
702 | * when the worker was SIGKILLed. | |
703 | */ | |
704 | struct kthread_worker * | |
dbf52682 | 705 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
706 | { |
707 | struct kthread_worker *worker; | |
708 | va_list args; | |
709 | ||
710 | va_start(args, namefmt); | |
dbf52682 | 711 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
712 | va_end(args); |
713 | ||
714 | return worker; | |
715 | } | |
716 | EXPORT_SYMBOL(kthread_create_worker); | |
717 | ||
718 | /** | |
719 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
720 | * it to a given CPU and the associated NUMA node. | |
721 | * @cpu: CPU number | |
dbf52682 | 722 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
723 | * @namefmt: printf-style name for the kthread worker (task). |
724 | * | |
725 | * Use a valid CPU number if you want to bind the kthread worker | |
726 | * to the given CPU and the associated NUMA node. | |
727 | * | |
728 | * A good practice is to add the cpu number also into the worker name. | |
729 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
730 | * | |
731 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
732 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
733 | * when the worker was SIGKILLed. | |
734 | */ | |
735 | struct kthread_worker * | |
dbf52682 PM |
736 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
737 | const char namefmt[], ...) | |
fbae2d44 PM |
738 | { |
739 | struct kthread_worker *worker; | |
740 | va_list args; | |
741 | ||
742 | va_start(args, namefmt); | |
dbf52682 | 743 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
744 | va_end(args); |
745 | ||
746 | return worker; | |
747 | } | |
748 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
749 | ||
37be45d4 PM |
750 | /* |
751 | * Returns true when the work could not be queued at the moment. | |
752 | * It happens when it is already pending in a worker list | |
753 | * or when it is being cancelled. | |
754 | */ | |
755 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
756 | struct kthread_work *work) | |
757 | { | |
758 | lockdep_assert_held(&worker->lock); | |
759 | ||
760 | return !list_empty(&work->node) || work->canceling; | |
761 | } | |
762 | ||
8197b3d4 PM |
763 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
764 | struct kthread_work *work) | |
765 | { | |
766 | lockdep_assert_held(&worker->lock); | |
767 | WARN_ON_ONCE(!list_empty(&work->node)); | |
768 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
769 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
770 | } | |
771 | ||
9a2e03d8 | 772 | /* insert @work before @pos in @worker */ |
3989144f | 773 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
774 | struct kthread_work *work, |
775 | struct list_head *pos) | |
9a2e03d8 | 776 | { |
8197b3d4 | 777 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 TH |
778 | |
779 | list_add_tail(&work->node, pos); | |
46f3d976 | 780 | work->worker = worker; |
ed1403ec | 781 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
782 | wake_up_process(worker->task); |
783 | } | |
784 | ||
b56c0d89 | 785 | /** |
3989144f | 786 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
787 | * @worker: target kthread_worker |
788 | * @work: kthread_work to queue | |
789 | * | |
790 | * Queue @work to work processor @task for async execution. @task | |
791 | * must have been created with kthread_worker_create(). Returns %true | |
792 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
793 | * |
794 | * Reinitialize the work if it needs to be used by another worker. | |
795 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 796 | */ |
3989144f | 797 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
798 | struct kthread_work *work) |
799 | { | |
800 | bool ret = false; | |
801 | unsigned long flags; | |
802 | ||
803 | spin_lock_irqsave(&worker->lock, flags); | |
37be45d4 | 804 | if (!queuing_blocked(worker, work)) { |
3989144f | 805 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
806 | ret = true; |
807 | } | |
808 | spin_unlock_irqrestore(&worker->lock, flags); | |
809 | return ret; | |
810 | } | |
3989144f | 811 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 812 | |
22597dc3 PM |
813 | /** |
814 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
815 | * delayed work when the timer expires. | |
fe5c3b69 | 816 | * @t: pointer to the expired timer |
22597dc3 PM |
817 | * |
818 | * The format of the function is defined by struct timer_list. | |
819 | * It should have been called from irqsafe timer with irq already off. | |
820 | */ | |
fe5c3b69 | 821 | void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3 | 822 | { |
fe5c3b69 | 823 | struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3 PM |
824 | struct kthread_work *work = &dwork->work; |
825 | struct kthread_worker *worker = work->worker; | |
826 | ||
827 | /* | |
828 | * This might happen when a pending work is reinitialized. | |
829 | * It means that it is used a wrong way. | |
830 | */ | |
831 | if (WARN_ON_ONCE(!worker)) | |
832 | return; | |
833 | ||
834 | spin_lock(&worker->lock); | |
835 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ | |
836 | WARN_ON_ONCE(work->worker != worker); | |
837 | ||
838 | /* Move the work from worker->delayed_work_list. */ | |
839 | WARN_ON_ONCE(list_empty(&work->node)); | |
840 | list_del_init(&work->node); | |
841 | kthread_insert_work(worker, work, &worker->work_list); | |
842 | ||
843 | spin_unlock(&worker->lock); | |
844 | } | |
845 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
846 | ||
847 | void __kthread_queue_delayed_work(struct kthread_worker *worker, | |
848 | struct kthread_delayed_work *dwork, | |
849 | unsigned long delay) | |
850 | { | |
851 | struct timer_list *timer = &dwork->timer; | |
852 | struct kthread_work *work = &dwork->work; | |
853 | ||
841b86f3 | 854 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3 PM |
855 | |
856 | /* | |
857 | * If @delay is 0, queue @dwork->work immediately. This is for | |
858 | * both optimization and correctness. The earliest @timer can | |
859 | * expire is on the closest next tick and delayed_work users depend | |
860 | * on that there's no such delay when @delay is 0. | |
861 | */ | |
862 | if (!delay) { | |
863 | kthread_insert_work(worker, work, &worker->work_list); | |
864 | return; | |
865 | } | |
866 | ||
867 | /* Be paranoid and try to detect possible races already now. */ | |
868 | kthread_insert_work_sanity_check(worker, work); | |
869 | ||
870 | list_add(&work->node, &worker->delayed_work_list); | |
871 | work->worker = worker; | |
22597dc3 PM |
872 | timer->expires = jiffies + delay; |
873 | add_timer(timer); | |
874 | } | |
875 | ||
876 | /** | |
877 | * kthread_queue_delayed_work - queue the associated kthread work | |
878 | * after a delay. | |
879 | * @worker: target kthread_worker | |
880 | * @dwork: kthread_delayed_work to queue | |
881 | * @delay: number of jiffies to wait before queuing | |
882 | * | |
883 | * If the work has not been pending it starts a timer that will queue | |
884 | * the work after the given @delay. If @delay is zero, it queues the | |
885 | * work immediately. | |
886 | * | |
887 | * Return: %false if the @work has already been pending. It means that | |
888 | * either the timer was running or the work was queued. It returns %true | |
889 | * otherwise. | |
890 | */ | |
891 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
892 | struct kthread_delayed_work *dwork, | |
893 | unsigned long delay) | |
894 | { | |
895 | struct kthread_work *work = &dwork->work; | |
896 | unsigned long flags; | |
897 | bool ret = false; | |
898 | ||
899 | spin_lock_irqsave(&worker->lock, flags); | |
900 | ||
37be45d4 | 901 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
902 | __kthread_queue_delayed_work(worker, dwork, delay); |
903 | ret = true; | |
904 | } | |
905 | ||
906 | spin_unlock_irqrestore(&worker->lock, flags); | |
907 | return ret; | |
908 | } | |
909 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
910 | ||
9a2e03d8 TH |
911 | struct kthread_flush_work { |
912 | struct kthread_work work; | |
913 | struct completion done; | |
914 | }; | |
915 | ||
916 | static void kthread_flush_work_fn(struct kthread_work *work) | |
917 | { | |
918 | struct kthread_flush_work *fwork = | |
919 | container_of(work, struct kthread_flush_work, work); | |
920 | complete(&fwork->done); | |
921 | } | |
922 | ||
b56c0d89 | 923 | /** |
3989144f | 924 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
925 | * @work: work to flush |
926 | * | |
927 | * If @work is queued or executing, wait for it to finish execution. | |
928 | */ | |
3989144f | 929 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 930 | { |
46f3d976 TH |
931 | struct kthread_flush_work fwork = { |
932 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
933 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
934 | }; | |
935 | struct kthread_worker *worker; | |
936 | bool noop = false; | |
937 | ||
46f3d976 TH |
938 | worker = work->worker; |
939 | if (!worker) | |
940 | return; | |
b56c0d89 | 941 | |
46f3d976 | 942 | spin_lock_irq(&worker->lock); |
8197b3d4 PM |
943 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
944 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 945 | |
46f3d976 | 946 | if (!list_empty(&work->node)) |
3989144f | 947 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 948 | else if (worker->current_work == work) |
3989144f PM |
949 | kthread_insert_work(worker, &fwork.work, |
950 | worker->work_list.next); | |
46f3d976 TH |
951 | else |
952 | noop = true; | |
b56c0d89 | 953 | |
46f3d976 | 954 | spin_unlock_irq(&worker->lock); |
b56c0d89 | 955 | |
46f3d976 TH |
956 | if (!noop) |
957 | wait_for_completion(&fwork.done); | |
b56c0d89 | 958 | } |
3989144f | 959 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 960 | |
37be45d4 PM |
961 | /* |
962 | * This function removes the work from the worker queue. Also it makes sure | |
963 | * that it won't get queued later via the delayed work's timer. | |
964 | * | |
965 | * The work might still be in use when this function finishes. See the | |
966 | * current_work proceed by the worker. | |
967 | * | |
968 | * Return: %true if @work was pending and successfully canceled, | |
969 | * %false if @work was not pending | |
970 | */ | |
971 | static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork, | |
972 | unsigned long *flags) | |
973 | { | |
974 | /* Try to cancel the timer if exists. */ | |
975 | if (is_dwork) { | |
976 | struct kthread_delayed_work *dwork = | |
977 | container_of(work, struct kthread_delayed_work, work); | |
978 | struct kthread_worker *worker = work->worker; | |
979 | ||
980 | /* | |
981 | * del_timer_sync() must be called to make sure that the timer | |
982 | * callback is not running. The lock must be temporary released | |
983 | * to avoid a deadlock with the callback. In the meantime, | |
984 | * any queuing is blocked by setting the canceling counter. | |
985 | */ | |
986 | work->canceling++; | |
987 | spin_unlock_irqrestore(&worker->lock, *flags); | |
988 | del_timer_sync(&dwork->timer); | |
989 | spin_lock_irqsave(&worker->lock, *flags); | |
990 | work->canceling--; | |
991 | } | |
992 | ||
993 | /* | |
994 | * Try to remove the work from a worker list. It might either | |
995 | * be from worker->work_list or from worker->delayed_work_list. | |
996 | */ | |
997 | if (!list_empty(&work->node)) { | |
998 | list_del_init(&work->node); | |
999 | return true; | |
1000 | } | |
1001 | ||
1002 | return false; | |
1003 | } | |
1004 | ||
9a6b06c8 PM |
1005 | /** |
1006 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1007 | * @worker: kthread worker to use | |
1008 | * @dwork: kthread delayed work to queue | |
1009 | * @delay: number of jiffies to wait before queuing | |
1010 | * | |
1011 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1012 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1013 | * @work is guaranteed to be queued immediately. | |
1014 | * | |
1015 | * Return: %true if @dwork was pending and its timer was modified, | |
1016 | * %false otherwise. | |
1017 | * | |
1018 | * A special case is when the work is being canceled in parallel. | |
1019 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1020 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
1021 | * win and return %false here. The caller is supposed to synchronize these | |
1022 | * operations a reasonable way. | |
1023 | * | |
1024 | * This function is safe to call from any context including IRQ handler. | |
1025 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1026 | * for details. | |
1027 | */ | |
1028 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1029 | struct kthread_delayed_work *dwork, | |
1030 | unsigned long delay) | |
1031 | { | |
1032 | struct kthread_work *work = &dwork->work; | |
1033 | unsigned long flags; | |
1034 | int ret = false; | |
1035 | ||
1036 | spin_lock_irqsave(&worker->lock, flags); | |
1037 | ||
1038 | /* Do not bother with canceling when never queued. */ | |
1039 | if (!work->worker) | |
1040 | goto fast_queue; | |
1041 | ||
1042 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1043 | WARN_ON_ONCE(work->worker != worker); | |
1044 | ||
1045 | /* Do not fight with another command that is canceling this work. */ | |
1046 | if (work->canceling) | |
1047 | goto out; | |
1048 | ||
1049 | ret = __kthread_cancel_work(work, true, &flags); | |
1050 | fast_queue: | |
1051 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1052 | out: | |
1053 | spin_unlock_irqrestore(&worker->lock, flags); | |
1054 | return ret; | |
1055 | } | |
1056 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1057 | ||
37be45d4 PM |
1058 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1059 | { | |
1060 | struct kthread_worker *worker = work->worker; | |
1061 | unsigned long flags; | |
1062 | int ret = false; | |
1063 | ||
1064 | if (!worker) | |
1065 | goto out; | |
1066 | ||
1067 | spin_lock_irqsave(&worker->lock, flags); | |
1068 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ | |
1069 | WARN_ON_ONCE(work->worker != worker); | |
1070 | ||
1071 | ret = __kthread_cancel_work(work, is_dwork, &flags); | |
1072 | ||
1073 | if (worker->current_work != work) | |
1074 | goto out_fast; | |
1075 | ||
1076 | /* | |
1077 | * The work is in progress and we need to wait with the lock released. | |
1078 | * In the meantime, block any queuing by setting the canceling counter. | |
1079 | */ | |
1080 | work->canceling++; | |
1081 | spin_unlock_irqrestore(&worker->lock, flags); | |
1082 | kthread_flush_work(work); | |
1083 | spin_lock_irqsave(&worker->lock, flags); | |
1084 | work->canceling--; | |
1085 | ||
1086 | out_fast: | |
1087 | spin_unlock_irqrestore(&worker->lock, flags); | |
1088 | out: | |
1089 | return ret; | |
1090 | } | |
1091 | ||
1092 | /** | |
1093 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1094 | * @work: the kthread work to cancel | |
1095 | * | |
1096 | * Cancel @work and wait for its execution to finish. This function | |
1097 | * can be used even if the work re-queues itself. On return from this | |
1098 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1099 | * | |
1100 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1101 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1102 | * | |
1103 | * The caller must ensure that the worker on which @work was last | |
1104 | * queued can't be destroyed before this function returns. | |
1105 | * | |
1106 | * Return: %true if @work was pending, %false otherwise. | |
1107 | */ | |
1108 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1109 | { | |
1110 | return __kthread_cancel_work_sync(work, false); | |
1111 | } | |
1112 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1113 | ||
1114 | /** | |
1115 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1116 | * wait for it to finish. | |
1117 | * @dwork: the kthread delayed work to cancel | |
1118 | * | |
1119 | * This is kthread_cancel_work_sync() for delayed works. | |
1120 | * | |
1121 | * Return: %true if @dwork was pending, %false otherwise. | |
1122 | */ | |
1123 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1124 | { | |
1125 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1126 | } | |
1127 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1128 | ||
b56c0d89 | 1129 | /** |
3989144f | 1130 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1131 | * @worker: worker to flush |
1132 | * | |
1133 | * Wait until all currently executing or pending works on @worker are | |
1134 | * finished. | |
1135 | */ | |
3989144f | 1136 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1137 | { |
1138 | struct kthread_flush_work fwork = { | |
1139 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1140 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1141 | }; | |
1142 | ||
3989144f | 1143 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1144 | wait_for_completion(&fwork.done); |
1145 | } | |
3989144f | 1146 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1147 | |
1148 | /** | |
1149 | * kthread_destroy_worker - destroy a kthread worker | |
1150 | * @worker: worker to be destroyed | |
1151 | * | |
1152 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1153 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1154 | * machines needed. | |
1155 | */ | |
1156 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1157 | { | |
1158 | struct task_struct *task; | |
1159 | ||
1160 | task = worker->task; | |
1161 | if (WARN_ON(!task)) | |
1162 | return; | |
1163 | ||
1164 | kthread_flush_worker(worker); | |
1165 | kthread_stop(task); | |
1166 | WARN_ON(!list_empty(&worker->work_list)); | |
1167 | kfree(worker); | |
1168 | } | |
1169 | EXPORT_SYMBOL(kthread_destroy_worker); | |
05e3db95 | 1170 | |
0b508bc9 | 1171 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
1172 | /** |
1173 | * kthread_associate_blkcg - associate blkcg to current kthread | |
1174 | * @css: the cgroup info | |
1175 | * | |
1176 | * Current thread must be a kthread. The thread is running jobs on behalf of | |
1177 | * other threads. In some cases, we expect the jobs attach cgroup info of | |
1178 | * original threads instead of that of current thread. This function stores | |
1179 | * original thread's cgroup info in current kthread context for later | |
1180 | * retrieval. | |
1181 | */ | |
1182 | void kthread_associate_blkcg(struct cgroup_subsys_state *css) | |
1183 | { | |
1184 | struct kthread *kthread; | |
1185 | ||
1186 | if (!(current->flags & PF_KTHREAD)) | |
1187 | return; | |
1188 | kthread = to_kthread(current); | |
1189 | if (!kthread) | |
1190 | return; | |
1191 | ||
1192 | if (kthread->blkcg_css) { | |
1193 | css_put(kthread->blkcg_css); | |
1194 | kthread->blkcg_css = NULL; | |
1195 | } | |
1196 | if (css) { | |
1197 | css_get(css); | |
1198 | kthread->blkcg_css = css; | |
1199 | } | |
1200 | } | |
1201 | EXPORT_SYMBOL(kthread_associate_blkcg); | |
1202 | ||
1203 | /** | |
1204 | * kthread_blkcg - get associated blkcg css of current kthread | |
1205 | * | |
1206 | * Current thread must be a kthread. | |
1207 | */ | |
1208 | struct cgroup_subsys_state *kthread_blkcg(void) | |
1209 | { | |
1210 | struct kthread *kthread; | |
1211 | ||
1212 | if (current->flags & PF_KTHREAD) { | |
1213 | kthread = to_kthread(current); | |
1214 | if (kthread) | |
1215 | return kthread->blkcg_css; | |
1216 | } | |
1217 | return NULL; | |
1218 | } | |
1219 | EXPORT_SYMBOL(kthread_blkcg); | |
1220 | #endif |