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