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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> |
793adb1b | 21 | #include <linux/cgroup.h> |
ad8d75ff | 22 | #include <trace/events/sched.h> |
1da177e4 | 23 | |
73c27992 EB |
24 | static DEFINE_SPINLOCK(kthread_create_lock); |
25 | static LIST_HEAD(kthread_create_list); | |
26 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
27 | |
28 | struct kthread_create_info | |
29 | { | |
73c27992 | 30 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
31 | int (*threadfn)(void *data); |
32 | void *data; | |
207205a2 | 33 | int node; |
1da177e4 | 34 | |
73c27992 | 35 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 36 | struct task_struct *result; |
786235ee | 37 | struct completion *done; |
65f27f38 | 38 | |
73c27992 | 39 | struct list_head list; |
1da177e4 LT |
40 | }; |
41 | ||
63706172 | 42 | struct kthread { |
2a1d4460 TG |
43 | unsigned long flags; |
44 | unsigned int cpu; | |
82805ab7 | 45 | void *data; |
2a1d4460 | 46 | struct completion parked; |
63706172 | 47 | struct completion exited; |
1da177e4 LT |
48 | }; |
49 | ||
2a1d4460 TG |
50 | enum KTHREAD_BITS { |
51 | KTHREAD_IS_PER_CPU = 0, | |
52 | KTHREAD_SHOULD_STOP, | |
53 | KTHREAD_SHOULD_PARK, | |
54 | KTHREAD_IS_PARKED, | |
55 | }; | |
56 | ||
1da5c46f ON |
57 | static inline void set_kthread_struct(void *kthread) |
58 | { | |
59 | /* | |
60 | * We abuse ->set_child_tid to avoid the new member and because it | |
61 | * can't be wrongly copied by copy_process(). We also rely on fact | |
62 | * that the caller can't exec, so PF_KTHREAD can't be cleared. | |
63 | */ | |
64 | current->set_child_tid = (__force void __user *)kthread; | |
65 | } | |
4ecdafc8 ON |
66 | |
67 | static inline struct kthread *to_kthread(struct task_struct *k) | |
68 | { | |
1da5c46f ON |
69 | WARN_ON(!(k->flags & PF_KTHREAD)); |
70 | return (__force void *)k->set_child_tid; | |
4ecdafc8 ON |
71 | } |
72 | ||
1da5c46f ON |
73 | void free_kthread_struct(struct task_struct *k) |
74 | { | |
75 | /* | |
76 | * Can be NULL if this kthread was created by kernel_thread() | |
77 | * or if kmalloc() in kthread() failed. | |
78 | */ | |
79 | kfree(to_kthread(k)); | |
80 | } | |
81 | ||
9e37bd30 RD |
82 | /** |
83 | * kthread_should_stop - should this kthread return now? | |
84 | * | |
72fd4a35 | 85 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
86 | * and this will return true. You should then return, and your return |
87 | * value will be passed through to kthread_stop(). | |
88 | */ | |
2a1d4460 | 89 | bool kthread_should_stop(void) |
1da177e4 | 90 | { |
2a1d4460 | 91 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
92 | } |
93 | EXPORT_SYMBOL(kthread_should_stop); | |
94 | ||
2a1d4460 TG |
95 | /** |
96 | * kthread_should_park - should this kthread park now? | |
97 | * | |
98 | * When someone calls kthread_park() on your kthread, it will be woken | |
99 | * and this will return true. You should then do the necessary | |
100 | * cleanup and call kthread_parkme() | |
101 | * | |
102 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
103 | * and in a park position. kthread_unpark() "restarts" the thread and | |
104 | * calls the thread function again. | |
105 | */ | |
106 | bool kthread_should_park(void) | |
107 | { | |
108 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags); | |
109 | } | |
18896451 | 110 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 111 | |
8a32c441 TH |
112 | /** |
113 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
114 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
115 | * | |
116 | * kthread_should_stop() for freezable kthreads, which will enter | |
117 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
118 | * freezer deadlock and freezable kthreads should use this function instead | |
119 | * of calling try_to_freeze() directly. | |
120 | */ | |
121 | bool kthread_freezable_should_stop(bool *was_frozen) | |
122 | { | |
123 | bool frozen = false; | |
124 | ||
125 | might_sleep(); | |
126 | ||
127 | if (unlikely(freezing(current))) | |
128 | frozen = __refrigerator(true); | |
129 | ||
130 | if (was_frozen) | |
131 | *was_frozen = frozen; | |
132 | ||
133 | return kthread_should_stop(); | |
134 | } | |
135 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
136 | ||
82805ab7 TH |
137 | /** |
138 | * kthread_data - return data value specified on kthread creation | |
139 | * @task: kthread task in question | |
140 | * | |
141 | * Return the data value specified when kthread @task was created. | |
142 | * The caller is responsible for ensuring the validity of @task when | |
143 | * calling this function. | |
144 | */ | |
145 | void *kthread_data(struct task_struct *task) | |
146 | { | |
147 | return to_kthread(task)->data; | |
148 | } | |
149 | ||
cd42d559 | 150 | /** |
e700591a | 151 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
152 | * @task: possible kthread task in question |
153 | * | |
154 | * @task could be a kthread task. Return the data value specified when it | |
155 | * was created if accessible. If @task isn't a kthread task or its data is | |
156 | * inaccessible for any reason, %NULL is returned. This function requires | |
157 | * that @task itself is safe to dereference. | |
158 | */ | |
e700591a | 159 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 TH |
160 | { |
161 | struct kthread *kthread = to_kthread(task); | |
162 | void *data = NULL; | |
163 | ||
164 | probe_kernel_read(&data, &kthread->data, sizeof(data)); | |
165 | return data; | |
166 | } | |
167 | ||
2a1d4460 TG |
168 | static void __kthread_parkme(struct kthread *self) |
169 | { | |
f2530dc7 | 170 | __set_current_state(TASK_PARKED); |
2a1d4460 TG |
171 | while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) { |
172 | if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags)) | |
173 | complete(&self->parked); | |
174 | schedule(); | |
f2530dc7 | 175 | __set_current_state(TASK_PARKED); |
2a1d4460 TG |
176 | } |
177 | clear_bit(KTHREAD_IS_PARKED, &self->flags); | |
178 | __set_current_state(TASK_RUNNING); | |
179 | } | |
180 | ||
181 | void kthread_parkme(void) | |
182 | { | |
183 | __kthread_parkme(to_kthread(current)); | |
184 | } | |
18896451 | 185 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 186 | |
1da177e4 LT |
187 | static int kthread(void *_create) |
188 | { | |
63706172 | 189 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 190 | struct kthread_create_info *create = _create; |
63706172 ON |
191 | int (*threadfn)(void *data) = create->threadfn; |
192 | void *data = create->data; | |
786235ee | 193 | struct completion *done; |
1da5c46f | 194 | struct kthread *self; |
63706172 | 195 | int ret; |
1da177e4 | 196 | |
1da5c46f ON |
197 | self = kmalloc(sizeof(*self), GFP_KERNEL); |
198 | set_kthread_struct(self); | |
1da177e4 | 199 | |
786235ee TH |
200 | /* If user was SIGKILLed, I release the structure. */ |
201 | done = xchg(&create->done, NULL); | |
202 | if (!done) { | |
203 | kfree(create); | |
204 | do_exit(-EINTR); | |
205 | } | |
1da5c46f ON |
206 | |
207 | if (!self) { | |
208 | create->result = ERR_PTR(-ENOMEM); | |
209 | complete(done); | |
210 | do_exit(-ENOMEM); | |
211 | } | |
212 | ||
213 | self->flags = 0; | |
214 | self->data = data; | |
215 | init_completion(&self->exited); | |
216 | init_completion(&self->parked); | |
217 | current->vfork_done = &self->exited; | |
218 | ||
1da177e4 | 219 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 220 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 221 | create->result = current; |
786235ee | 222 | complete(done); |
1da177e4 LT |
223 | schedule(); |
224 | ||
63706172 | 225 | ret = -EINTR; |
1da5c46f | 226 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
793adb1b | 227 | cgroup_kthread_ready(); |
1da5c46f | 228 | __kthread_parkme(self); |
2a1d4460 TG |
229 | ret = threadfn(data); |
230 | } | |
63706172 | 231 | do_exit(ret); |
1da177e4 LT |
232 | } |
233 | ||
207205a2 ED |
234 | /* called from do_fork() to get node information for about to be created task */ |
235 | int tsk_fork_get_node(struct task_struct *tsk) | |
236 | { | |
237 | #ifdef CONFIG_NUMA | |
238 | if (tsk == kthreadd_task) | |
239 | return tsk->pref_node_fork; | |
240 | #endif | |
81c98869 | 241 | return NUMA_NO_NODE; |
207205a2 ED |
242 | } |
243 | ||
73c27992 | 244 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 245 | { |
1da177e4 LT |
246 | int pid; |
247 | ||
207205a2 ED |
248 | #ifdef CONFIG_NUMA |
249 | current->pref_node_fork = create->node; | |
250 | #endif | |
1da177e4 LT |
251 | /* We want our own signal handler (we take no signals by default). */ |
252 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 253 | if (pid < 0) { |
786235ee TH |
254 | /* If user was SIGKILLed, I release the structure. */ |
255 | struct completion *done = xchg(&create->done, NULL); | |
256 | ||
257 | if (!done) { | |
258 | kfree(create); | |
259 | return; | |
260 | } | |
1da177e4 | 261 | create->result = ERR_PTR(pid); |
786235ee | 262 | complete(done); |
cdd140bd | 263 | } |
1da177e4 LT |
264 | } |
265 | ||
c0b942a7 NI |
266 | static __printf(4, 0) |
267 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
268 | void *data, int node, |
269 | const char namefmt[], | |
270 | va_list args) | |
1da177e4 | 271 | { |
786235ee TH |
272 | DECLARE_COMPLETION_ONSTACK(done); |
273 | struct task_struct *task; | |
274 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
275 | GFP_KERNEL); | |
276 | ||
277 | if (!create) | |
278 | return ERR_PTR(-ENOMEM); | |
279 | create->threadfn = threadfn; | |
280 | create->data = data; | |
281 | create->node = node; | |
282 | create->done = &done; | |
73c27992 EB |
283 | |
284 | spin_lock(&kthread_create_lock); | |
786235ee | 285 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
286 | spin_unlock(&kthread_create_lock); |
287 | ||
cbd9b67b | 288 | wake_up_process(kthreadd_task); |
786235ee TH |
289 | /* |
290 | * Wait for completion in killable state, for I might be chosen by | |
291 | * the OOM killer while kthreadd is trying to allocate memory for | |
292 | * new kernel thread. | |
293 | */ | |
294 | if (unlikely(wait_for_completion_killable(&done))) { | |
cdbbd331 TH |
295 | int i = 0; |
296 | ||
297 | /* | |
298 | * I got SIGKILL, but wait for 10 more seconds for completion | |
299 | * unless chosen by the OOM killer. This delay is there as a | |
300 | * workaround for boot failure caused by SIGKILL upon device | |
301 | * driver initialization timeout. | |
302 | */ | |
303 | while (i++ < 10 && !test_tsk_thread_flag(current, TIF_MEMDIE)) | |
304 | if (wait_for_completion_timeout(&done, HZ)) | |
305 | goto ready; | |
786235ee TH |
306 | /* |
307 | * If I was SIGKILLed before kthreadd (or new kernel thread) | |
308 | * calls complete(), leave the cleanup of this structure to | |
309 | * that thread. | |
310 | */ | |
311 | if (xchg(&create->done, NULL)) | |
8fe6929c | 312 | return ERR_PTR(-EINTR); |
786235ee TH |
313 | /* |
314 | * kthreadd (or new kernel thread) will call complete() | |
315 | * shortly. | |
316 | */ | |
317 | wait_for_completion(&done); | |
318 | } | |
cdbbd331 | 319 | ready: |
786235ee TH |
320 | task = create->result; |
321 | if (!IS_ERR(task)) { | |
c9b5f501 | 322 | static const struct sched_param param = { .sched_priority = 0 }; |
1c99315b | 323 | |
786235ee | 324 | vsnprintf(task->comm, sizeof(task->comm), namefmt, args); |
1c99315b ON |
325 | /* |
326 | * root may have changed our (kthreadd's) priority or CPU mask. | |
327 | * The kernel thread should not inherit these properties. | |
328 | */ | |
786235ee TH |
329 | sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
330 | set_cpus_allowed_ptr(task, cpu_all_mask); | |
1da177e4 | 331 | } |
786235ee TH |
332 | kfree(create); |
333 | return task; | |
1da177e4 | 334 | } |
255451e4 PM |
335 | |
336 | /** | |
337 | * kthread_create_on_node - create a kthread. | |
338 | * @threadfn: the function to run until signal_pending(current). | |
339 | * @data: data ptr for @threadfn. | |
340 | * @node: task and thread structures for the thread are allocated on this node | |
341 | * @namefmt: printf-style name for the thread. | |
342 | * | |
343 | * Description: This helper function creates and names a kernel | |
344 | * thread. The thread will be stopped: use wake_up_process() to start | |
345 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
346 | * is affine to all CPUs. | |
347 | * | |
348 | * If thread is going to be bound on a particular cpu, give its node | |
349 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
350 | * When woken, the thread will run @threadfn() with @data as its | |
351 | * argument. @threadfn() can either call do_exit() directly if it is a | |
352 | * standalone thread for which no one will call kthread_stop(), or | |
353 | * return when 'kthread_should_stop()' is true (which means | |
354 | * kthread_stop() has been called). The return value should be zero | |
355 | * or a negative error number; it will be passed to kthread_stop(). | |
356 | * | |
357 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
358 | */ | |
359 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
360 | void *data, int node, | |
361 | const char namefmt[], | |
362 | ...) | |
363 | { | |
364 | struct task_struct *task; | |
365 | va_list args; | |
366 | ||
367 | va_start(args, namefmt); | |
368 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
369 | va_end(args); | |
370 | ||
371 | return task; | |
372 | } | |
207205a2 | 373 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 374 | |
25834c73 | 375 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
2a1d4460 | 376 | { |
25834c73 PZ |
377 | unsigned long flags; |
378 | ||
f2530dc7 TG |
379 | if (!wait_task_inactive(p, state)) { |
380 | WARN_ON(1); | |
381 | return; | |
382 | } | |
25834c73 | 383 | |
2a1d4460 | 384 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
385 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
386 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 387 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
388 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
389 | } | |
390 | ||
391 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) | |
392 | { | |
393 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
394 | } | |
395 | ||
396 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
397 | { | |
398 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
399 | } |
400 | ||
881232b7 PZ |
401 | /** |
402 | * kthread_bind - bind a just-created kthread to a cpu. | |
403 | * @p: thread created by kthread_create(). | |
404 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
405 | * | |
406 | * Description: This function is equivalent to set_cpus_allowed(), | |
407 | * except that @cpu doesn't need to be online, and the thread must be | |
408 | * stopped (i.e., just returned from kthread_create()). | |
409 | */ | |
410 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
411 | { | |
f2530dc7 | 412 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
413 | } |
414 | EXPORT_SYMBOL(kthread_bind); | |
415 | ||
2a1d4460 TG |
416 | /** |
417 | * kthread_create_on_cpu - Create a cpu bound kthread | |
418 | * @threadfn: the function to run until signal_pending(current). | |
419 | * @data: data ptr for @threadfn. | |
420 | * @cpu: The cpu on which the thread should be bound, | |
421 | * @namefmt: printf-style name for the thread. Format is restricted | |
422 | * to "name.*%u". Code fills in cpu number. | |
423 | * | |
424 | * Description: This helper function creates and names a kernel thread | |
425 | * The thread will be woken and put into park mode. | |
426 | */ | |
427 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
428 | void *data, unsigned int cpu, | |
429 | const char *namefmt) | |
430 | { | |
431 | struct task_struct *p; | |
432 | ||
10922838 | 433 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
434 | cpu); |
435 | if (IS_ERR(p)) | |
436 | return p; | |
a65d4096 PM |
437 | kthread_bind(p, cpu); |
438 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 TG |
439 | set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); |
440 | to_kthread(p)->cpu = cpu; | |
2a1d4460 TG |
441 | return p; |
442 | } | |
443 | ||
cf380a4a ON |
444 | /** |
445 | * kthread_unpark - unpark a thread created by kthread_create(). | |
446 | * @k: thread created by kthread_create(). | |
447 | * | |
448 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
449 | * waits for it to return. If the thread is marked percpu then its | |
450 | * bound to the cpu again. | |
451 | */ | |
452 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 453 | { |
cf380a4a ON |
454 | struct kthread *kthread = to_kthread(k); |
455 | ||
f2530dc7 TG |
456 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
457 | /* | |
458 | * We clear the IS_PARKED bit here as we don't wait | |
459 | * until the task has left the park code. So if we'd | |
460 | * park before that happens we'd see the IS_PARKED bit | |
461 | * which might be about to be cleared. | |
462 | */ | |
463 | if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) { | |
a65d4096 PM |
464 | /* |
465 | * Newly created kthread was parked when the CPU was offline. | |
466 | * The binding was lost and we need to set it again. | |
467 | */ | |
f2530dc7 TG |
468 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
469 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
470 | wake_up_state(k, TASK_PARKED); | |
471 | } | |
472 | } | |
18896451 | 473 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
474 | |
475 | /** | |
476 | * kthread_park - park a thread created by kthread_create(). | |
477 | * @k: thread created by kthread_create(). | |
478 | * | |
479 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
480 | * waits for it to return. This can also be called after kthread_create() | |
481 | * instead of calling wake_up_process(): the thread will park without | |
482 | * calling threadfn(). | |
483 | * | |
484 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
485 | * If called by the kthread itself just the park bit is set. | |
486 | */ | |
487 | int kthread_park(struct task_struct *k) | |
488 | { | |
cf380a4a ON |
489 | struct kthread *kthread = to_kthread(k); |
490 | ||
491 | if (WARN_ON(k->flags & PF_EXITING)) | |
492 | return -ENOSYS; | |
493 | ||
494 | if (!test_bit(KTHREAD_IS_PARKED, &kthread->flags)) { | |
495 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
496 | if (k != current) { | |
497 | wake_up_process(k); | |
498 | wait_for_completion(&kthread->parked); | |
2a1d4460 | 499 | } |
2a1d4460 | 500 | } |
cf380a4a ON |
501 | |
502 | return 0; | |
2a1d4460 | 503 | } |
18896451 | 504 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 505 | |
9e37bd30 RD |
506 | /** |
507 | * kthread_stop - stop a thread created by kthread_create(). | |
508 | * @k: thread created by kthread_create(). | |
509 | * | |
510 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
511 | * waits for it to exit. This can also be called after kthread_create() |
512 | * instead of calling wake_up_process(): the thread will exit without | |
513 | * calling threadfn(). | |
514 | * | |
515 | * If threadfn() may call do_exit() itself, the caller must ensure | |
516 | * task_struct can't go away. | |
9e37bd30 RD |
517 | * |
518 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
519 | * was never called. | |
520 | */ | |
1da177e4 LT |
521 | int kthread_stop(struct task_struct *k) |
522 | { | |
b5c5442b | 523 | struct kthread *kthread; |
1da177e4 LT |
524 | int ret; |
525 | ||
0a16b607 | 526 | trace_sched_kthread_stop(k); |
b5c5442b ON |
527 | |
528 | get_task_struct(k); | |
efb29fbf ON |
529 | kthread = to_kthread(k); |
530 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 531 | kthread_unpark(k); |
efb29fbf ON |
532 | wake_up_process(k); |
533 | wait_for_completion(&kthread->exited); | |
63706172 | 534 | ret = k->exit_code; |
1da177e4 | 535 | put_task_struct(k); |
0a16b607 | 536 | |
b5c5442b | 537 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
538 | return ret; |
539 | } | |
52e92e57 | 540 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 541 | |
e804a4a4 | 542 | int kthreadd(void *unused) |
1da177e4 | 543 | { |
73c27992 | 544 | struct task_struct *tsk = current; |
1da177e4 | 545 | |
e804a4a4 | 546 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 547 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 548 | ignore_signals(tsk); |
1a2142af | 549 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa4 | 550 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 551 | |
34b087e4 | 552 | current->flags |= PF_NOFREEZE; |
793adb1b | 553 | cgroup_init_kthreadd(); |
73c27992 EB |
554 | |
555 | for (;;) { | |
556 | set_current_state(TASK_INTERRUPTIBLE); | |
557 | if (list_empty(&kthread_create_list)) | |
558 | schedule(); | |
559 | __set_current_state(TASK_RUNNING); | |
560 | ||
561 | spin_lock(&kthread_create_lock); | |
562 | while (!list_empty(&kthread_create_list)) { | |
563 | struct kthread_create_info *create; | |
564 | ||
565 | create = list_entry(kthread_create_list.next, | |
566 | struct kthread_create_info, list); | |
567 | list_del_init(&create->list); | |
568 | spin_unlock(&kthread_create_lock); | |
569 | ||
570 | create_kthread(create); | |
571 | ||
572 | spin_lock(&kthread_create_lock); | |
573 | } | |
574 | spin_unlock(&kthread_create_lock); | |
575 | } | |
576 | ||
577 | return 0; | |
578 | } | |
b56c0d89 | 579 | |
3989144f | 580 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
581 | const char *name, |
582 | struct lock_class_key *key) | |
583 | { | |
dbf52682 | 584 | memset(worker, 0, sizeof(struct kthread_worker)); |
4f32e9b1 YZ |
585 | spin_lock_init(&worker->lock); |
586 | lockdep_set_class_and_name(&worker->lock, key, name); | |
587 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 588 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 589 | } |
3989144f | 590 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 591 | |
b56c0d89 TH |
592 | /** |
593 | * kthread_worker_fn - kthread function to process kthread_worker | |
594 | * @worker_ptr: pointer to initialized kthread_worker | |
595 | * | |
fbae2d44 PM |
596 | * This function implements the main cycle of kthread worker. It processes |
597 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
598 | * is empty. | |
b56c0d89 | 599 | * |
fbae2d44 PM |
600 | * The works are not allowed to keep any locks, disable preemption or interrupts |
601 | * when they finish. There is defined a safe point for freezing when one work | |
602 | * finishes and before a new one is started. | |
8197b3d4 PM |
603 | * |
604 | * Also the works must not be handled by more than one worker at the same time, | |
605 | * see also kthread_queue_work(). | |
b56c0d89 TH |
606 | */ |
607 | int kthread_worker_fn(void *worker_ptr) | |
608 | { | |
609 | struct kthread_worker *worker = worker_ptr; | |
610 | struct kthread_work *work; | |
611 | ||
fbae2d44 PM |
612 | /* |
613 | * FIXME: Update the check and remove the assignment when all kthread | |
614 | * worker users are created using kthread_create_worker*() functions. | |
615 | */ | |
616 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 617 | worker->task = current; |
dbf52682 PM |
618 | |
619 | if (worker->flags & KTW_FREEZABLE) | |
620 | set_freezable(); | |
621 | ||
b56c0d89 TH |
622 | repeat: |
623 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
624 | ||
625 | if (kthread_should_stop()) { | |
626 | __set_current_state(TASK_RUNNING); | |
627 | spin_lock_irq(&worker->lock); | |
628 | worker->task = NULL; | |
629 | spin_unlock_irq(&worker->lock); | |
630 | return 0; | |
631 | } | |
632 | ||
633 | work = NULL; | |
634 | spin_lock_irq(&worker->lock); | |
635 | if (!list_empty(&worker->work_list)) { | |
636 | work = list_first_entry(&worker->work_list, | |
637 | struct kthread_work, node); | |
638 | list_del_init(&work->node); | |
639 | } | |
46f3d976 | 640 | worker->current_work = work; |
b56c0d89 TH |
641 | spin_unlock_irq(&worker->lock); |
642 | ||
643 | if (work) { | |
644 | __set_current_state(TASK_RUNNING); | |
645 | work->func(work); | |
b56c0d89 TH |
646 | } else if (!freezing(current)) |
647 | schedule(); | |
648 | ||
649 | try_to_freeze(); | |
650 | goto repeat; | |
651 | } | |
652 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
653 | ||
c0b942a7 | 654 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
655 | __kthread_create_worker(int cpu, unsigned int flags, |
656 | const char namefmt[], va_list args) | |
fbae2d44 PM |
657 | { |
658 | struct kthread_worker *worker; | |
659 | struct task_struct *task; | |
8fb9dcbd | 660 | int node = -1; |
fbae2d44 PM |
661 | |
662 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
663 | if (!worker) | |
664 | return ERR_PTR(-ENOMEM); | |
665 | ||
666 | kthread_init_worker(worker); | |
667 | ||
8fb9dcbd ON |
668 | if (cpu >= 0) |
669 | node = cpu_to_node(cpu); | |
fbae2d44 | 670 | |
8fb9dcbd ON |
671 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
672 | node, namefmt, args); | |
fbae2d44 PM |
673 | if (IS_ERR(task)) |
674 | goto fail_task; | |
675 | ||
8fb9dcbd ON |
676 | if (cpu >= 0) |
677 | kthread_bind(task, cpu); | |
678 | ||
dbf52682 | 679 | worker->flags = flags; |
fbae2d44 PM |
680 | worker->task = task; |
681 | wake_up_process(task); | |
682 | return worker; | |
683 | ||
684 | fail_task: | |
685 | kfree(worker); | |
686 | return ERR_CAST(task); | |
687 | } | |
688 | ||
689 | /** | |
690 | * kthread_create_worker - create a kthread worker | |
dbf52682 | 691 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
692 | * @namefmt: printf-style name for the kthread worker (task). |
693 | * | |
694 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
695 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
696 | * when the worker was SIGKILLed. | |
697 | */ | |
698 | struct kthread_worker * | |
dbf52682 | 699 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
700 | { |
701 | struct kthread_worker *worker; | |
702 | va_list args; | |
703 | ||
704 | va_start(args, namefmt); | |
dbf52682 | 705 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
706 | va_end(args); |
707 | ||
708 | return worker; | |
709 | } | |
710 | EXPORT_SYMBOL(kthread_create_worker); | |
711 | ||
712 | /** | |
713 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
714 | * it to a given CPU and the associated NUMA node. | |
715 | * @cpu: CPU number | |
dbf52682 | 716 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
717 | * @namefmt: printf-style name for the kthread worker (task). |
718 | * | |
719 | * Use a valid CPU number if you want to bind the kthread worker | |
720 | * to the given CPU and the associated NUMA node. | |
721 | * | |
722 | * A good practice is to add the cpu number also into the worker name. | |
723 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
724 | * | |
725 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
726 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
727 | * when the worker was SIGKILLed. | |
728 | */ | |
729 | struct kthread_worker * | |
dbf52682 PM |
730 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
731 | const char namefmt[], ...) | |
fbae2d44 PM |
732 | { |
733 | struct kthread_worker *worker; | |
734 | va_list args; | |
735 | ||
736 | va_start(args, namefmt); | |
dbf52682 | 737 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
738 | va_end(args); |
739 | ||
740 | return worker; | |
741 | } | |
742 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
743 | ||
37be45d4 PM |
744 | /* |
745 | * Returns true when the work could not be queued at the moment. | |
746 | * It happens when it is already pending in a worker list | |
747 | * or when it is being cancelled. | |
748 | */ | |
749 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
750 | struct kthread_work *work) | |
751 | { | |
752 | lockdep_assert_held(&worker->lock); | |
753 | ||
754 | return !list_empty(&work->node) || work->canceling; | |
755 | } | |
756 | ||
8197b3d4 PM |
757 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
758 | struct kthread_work *work) | |
759 | { | |
760 | lockdep_assert_held(&worker->lock); | |
761 | WARN_ON_ONCE(!list_empty(&work->node)); | |
762 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
763 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
764 | } | |
765 | ||
9a2e03d8 | 766 | /* insert @work before @pos in @worker */ |
3989144f | 767 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
768 | struct kthread_work *work, |
769 | struct list_head *pos) | |
9a2e03d8 | 770 | { |
8197b3d4 | 771 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 TH |
772 | |
773 | list_add_tail(&work->node, pos); | |
46f3d976 | 774 | work->worker = worker; |
ed1403ec | 775 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
776 | wake_up_process(worker->task); |
777 | } | |
778 | ||
b56c0d89 | 779 | /** |
3989144f | 780 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
781 | * @worker: target kthread_worker |
782 | * @work: kthread_work to queue | |
783 | * | |
784 | * Queue @work to work processor @task for async execution. @task | |
785 | * must have been created with kthread_worker_create(). Returns %true | |
786 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
787 | * |
788 | * Reinitialize the work if it needs to be used by another worker. | |
789 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 790 | */ |
3989144f | 791 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
792 | struct kthread_work *work) |
793 | { | |
794 | bool ret = false; | |
795 | unsigned long flags; | |
796 | ||
797 | spin_lock_irqsave(&worker->lock, flags); | |
37be45d4 | 798 | if (!queuing_blocked(worker, work)) { |
3989144f | 799 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
800 | ret = true; |
801 | } | |
802 | spin_unlock_irqrestore(&worker->lock, flags); | |
803 | return ret; | |
804 | } | |
3989144f | 805 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 806 | |
22597dc3 PM |
807 | /** |
808 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
809 | * delayed work when the timer expires. | |
810 | * @__data: pointer to the data associated with the timer | |
811 | * | |
812 | * The format of the function is defined by struct timer_list. | |
813 | * It should have been called from irqsafe timer with irq already off. | |
814 | */ | |
815 | void kthread_delayed_work_timer_fn(unsigned long __data) | |
816 | { | |
817 | struct kthread_delayed_work *dwork = | |
818 | (struct kthread_delayed_work *)__data; | |
819 | struct kthread_work *work = &dwork->work; | |
820 | struct kthread_worker *worker = work->worker; | |
821 | ||
822 | /* | |
823 | * This might happen when a pending work is reinitialized. | |
824 | * It means that it is used a wrong way. | |
825 | */ | |
826 | if (WARN_ON_ONCE(!worker)) | |
827 | return; | |
828 | ||
829 | spin_lock(&worker->lock); | |
830 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ | |
831 | WARN_ON_ONCE(work->worker != worker); | |
832 | ||
833 | /* Move the work from worker->delayed_work_list. */ | |
834 | WARN_ON_ONCE(list_empty(&work->node)); | |
835 | list_del_init(&work->node); | |
836 | kthread_insert_work(worker, work, &worker->work_list); | |
837 | ||
838 | spin_unlock(&worker->lock); | |
839 | } | |
840 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
841 | ||
842 | void __kthread_queue_delayed_work(struct kthread_worker *worker, | |
843 | struct kthread_delayed_work *dwork, | |
844 | unsigned long delay) | |
845 | { | |
846 | struct timer_list *timer = &dwork->timer; | |
847 | struct kthread_work *work = &dwork->work; | |
848 | ||
849 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn || | |
850 | timer->data != (unsigned long)dwork); | |
851 | ||
852 | /* | |
853 | * If @delay is 0, queue @dwork->work immediately. This is for | |
854 | * both optimization and correctness. The earliest @timer can | |
855 | * expire is on the closest next tick and delayed_work users depend | |
856 | * on that there's no such delay when @delay is 0. | |
857 | */ | |
858 | if (!delay) { | |
859 | kthread_insert_work(worker, work, &worker->work_list); | |
860 | return; | |
861 | } | |
862 | ||
863 | /* Be paranoid and try to detect possible races already now. */ | |
864 | kthread_insert_work_sanity_check(worker, work); | |
865 | ||
866 | list_add(&work->node, &worker->delayed_work_list); | |
867 | work->worker = worker; | |
868 | timer_stats_timer_set_start_info(&dwork->timer); | |
869 | timer->expires = jiffies + delay; | |
870 | add_timer(timer); | |
871 | } | |
872 | ||
873 | /** | |
874 | * kthread_queue_delayed_work - queue the associated kthread work | |
875 | * after a delay. | |
876 | * @worker: target kthread_worker | |
877 | * @dwork: kthread_delayed_work to queue | |
878 | * @delay: number of jiffies to wait before queuing | |
879 | * | |
880 | * If the work has not been pending it starts a timer that will queue | |
881 | * the work after the given @delay. If @delay is zero, it queues the | |
882 | * work immediately. | |
883 | * | |
884 | * Return: %false if the @work has already been pending. It means that | |
885 | * either the timer was running or the work was queued. It returns %true | |
886 | * otherwise. | |
887 | */ | |
888 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
889 | struct kthread_delayed_work *dwork, | |
890 | unsigned long delay) | |
891 | { | |
892 | struct kthread_work *work = &dwork->work; | |
893 | unsigned long flags; | |
894 | bool ret = false; | |
895 | ||
896 | spin_lock_irqsave(&worker->lock, flags); | |
897 | ||
37be45d4 | 898 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
899 | __kthread_queue_delayed_work(worker, dwork, delay); |
900 | ret = true; | |
901 | } | |
902 | ||
903 | spin_unlock_irqrestore(&worker->lock, flags); | |
904 | return ret; | |
905 | } | |
906 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
907 | ||
9a2e03d8 TH |
908 | struct kthread_flush_work { |
909 | struct kthread_work work; | |
910 | struct completion done; | |
911 | }; | |
912 | ||
913 | static void kthread_flush_work_fn(struct kthread_work *work) | |
914 | { | |
915 | struct kthread_flush_work *fwork = | |
916 | container_of(work, struct kthread_flush_work, work); | |
917 | complete(&fwork->done); | |
918 | } | |
919 | ||
b56c0d89 | 920 | /** |
3989144f | 921 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
922 | * @work: work to flush |
923 | * | |
924 | * If @work is queued or executing, wait for it to finish execution. | |
925 | */ | |
3989144f | 926 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 927 | { |
46f3d976 TH |
928 | struct kthread_flush_work fwork = { |
929 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
930 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
931 | }; | |
932 | struct kthread_worker *worker; | |
933 | bool noop = false; | |
934 | ||
46f3d976 TH |
935 | worker = work->worker; |
936 | if (!worker) | |
937 | return; | |
b56c0d89 | 938 | |
46f3d976 | 939 | spin_lock_irq(&worker->lock); |
8197b3d4 PM |
940 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
941 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 942 | |
46f3d976 | 943 | if (!list_empty(&work->node)) |
3989144f | 944 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 945 | else if (worker->current_work == work) |
3989144f PM |
946 | kthread_insert_work(worker, &fwork.work, |
947 | worker->work_list.next); | |
46f3d976 TH |
948 | else |
949 | noop = true; | |
b56c0d89 | 950 | |
46f3d976 | 951 | spin_unlock_irq(&worker->lock); |
b56c0d89 | 952 | |
46f3d976 TH |
953 | if (!noop) |
954 | wait_for_completion(&fwork.done); | |
b56c0d89 | 955 | } |
3989144f | 956 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 957 | |
37be45d4 PM |
958 | /* |
959 | * This function removes the work from the worker queue. Also it makes sure | |
960 | * that it won't get queued later via the delayed work's timer. | |
961 | * | |
962 | * The work might still be in use when this function finishes. See the | |
963 | * current_work proceed by the worker. | |
964 | * | |
965 | * Return: %true if @work was pending and successfully canceled, | |
966 | * %false if @work was not pending | |
967 | */ | |
968 | static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork, | |
969 | unsigned long *flags) | |
970 | { | |
971 | /* Try to cancel the timer if exists. */ | |
972 | if (is_dwork) { | |
973 | struct kthread_delayed_work *dwork = | |
974 | container_of(work, struct kthread_delayed_work, work); | |
975 | struct kthread_worker *worker = work->worker; | |
976 | ||
977 | /* | |
978 | * del_timer_sync() must be called to make sure that the timer | |
979 | * callback is not running. The lock must be temporary released | |
980 | * to avoid a deadlock with the callback. In the meantime, | |
981 | * any queuing is blocked by setting the canceling counter. | |
982 | */ | |
983 | work->canceling++; | |
984 | spin_unlock_irqrestore(&worker->lock, *flags); | |
985 | del_timer_sync(&dwork->timer); | |
986 | spin_lock_irqsave(&worker->lock, *flags); | |
987 | work->canceling--; | |
988 | } | |
989 | ||
990 | /* | |
991 | * Try to remove the work from a worker list. It might either | |
992 | * be from worker->work_list or from worker->delayed_work_list. | |
993 | */ | |
994 | if (!list_empty(&work->node)) { | |
995 | list_del_init(&work->node); | |
996 | return true; | |
997 | } | |
998 | ||
999 | return false; | |
1000 | } | |
1001 | ||
9a6b06c8 PM |
1002 | /** |
1003 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1004 | * @worker: kthread worker to use | |
1005 | * @dwork: kthread delayed work to queue | |
1006 | * @delay: number of jiffies to wait before queuing | |
1007 | * | |
1008 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1009 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1010 | * @work is guaranteed to be queued immediately. | |
1011 | * | |
1012 | * Return: %true if @dwork was pending and its timer was modified, | |
1013 | * %false otherwise. | |
1014 | * | |
1015 | * A special case is when the work is being canceled in parallel. | |
1016 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1017 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
1018 | * win and return %false here. The caller is supposed to synchronize these | |
1019 | * operations a reasonable way. | |
1020 | * | |
1021 | * This function is safe to call from any context including IRQ handler. | |
1022 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1023 | * for details. | |
1024 | */ | |
1025 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1026 | struct kthread_delayed_work *dwork, | |
1027 | unsigned long delay) | |
1028 | { | |
1029 | struct kthread_work *work = &dwork->work; | |
1030 | unsigned long flags; | |
1031 | int ret = false; | |
1032 | ||
1033 | spin_lock_irqsave(&worker->lock, flags); | |
1034 | ||
1035 | /* Do not bother with canceling when never queued. */ | |
1036 | if (!work->worker) | |
1037 | goto fast_queue; | |
1038 | ||
1039 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1040 | WARN_ON_ONCE(work->worker != worker); | |
1041 | ||
1042 | /* Do not fight with another command that is canceling this work. */ | |
1043 | if (work->canceling) | |
1044 | goto out; | |
1045 | ||
1046 | ret = __kthread_cancel_work(work, true, &flags); | |
1047 | fast_queue: | |
1048 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1049 | out: | |
1050 | spin_unlock_irqrestore(&worker->lock, flags); | |
1051 | return ret; | |
1052 | } | |
1053 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1054 | ||
37be45d4 PM |
1055 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1056 | { | |
1057 | struct kthread_worker *worker = work->worker; | |
1058 | unsigned long flags; | |
1059 | int ret = false; | |
1060 | ||
1061 | if (!worker) | |
1062 | goto out; | |
1063 | ||
1064 | spin_lock_irqsave(&worker->lock, flags); | |
1065 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ | |
1066 | WARN_ON_ONCE(work->worker != worker); | |
1067 | ||
1068 | ret = __kthread_cancel_work(work, is_dwork, &flags); | |
1069 | ||
1070 | if (worker->current_work != work) | |
1071 | goto out_fast; | |
1072 | ||
1073 | /* | |
1074 | * The work is in progress and we need to wait with the lock released. | |
1075 | * In the meantime, block any queuing by setting the canceling counter. | |
1076 | */ | |
1077 | work->canceling++; | |
1078 | spin_unlock_irqrestore(&worker->lock, flags); | |
1079 | kthread_flush_work(work); | |
1080 | spin_lock_irqsave(&worker->lock, flags); | |
1081 | work->canceling--; | |
1082 | ||
1083 | out_fast: | |
1084 | spin_unlock_irqrestore(&worker->lock, flags); | |
1085 | out: | |
1086 | return ret; | |
1087 | } | |
1088 | ||
1089 | /** | |
1090 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1091 | * @work: the kthread work to cancel | |
1092 | * | |
1093 | * Cancel @work and wait for its execution to finish. This function | |
1094 | * can be used even if the work re-queues itself. On return from this | |
1095 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1096 | * | |
1097 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1098 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1099 | * | |
1100 | * The caller must ensure that the worker on which @work was last | |
1101 | * queued can't be destroyed before this function returns. | |
1102 | * | |
1103 | * Return: %true if @work was pending, %false otherwise. | |
1104 | */ | |
1105 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1106 | { | |
1107 | return __kthread_cancel_work_sync(work, false); | |
1108 | } | |
1109 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1110 | ||
1111 | /** | |
1112 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1113 | * wait for it to finish. | |
1114 | * @dwork: the kthread delayed work to cancel | |
1115 | * | |
1116 | * This is kthread_cancel_work_sync() for delayed works. | |
1117 | * | |
1118 | * Return: %true if @dwork was pending, %false otherwise. | |
1119 | */ | |
1120 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1121 | { | |
1122 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1123 | } | |
1124 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1125 | ||
b56c0d89 | 1126 | /** |
3989144f | 1127 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1128 | * @worker: worker to flush |
1129 | * | |
1130 | * Wait until all currently executing or pending works on @worker are | |
1131 | * finished. | |
1132 | */ | |
3989144f | 1133 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1134 | { |
1135 | struct kthread_flush_work fwork = { | |
1136 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1137 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1138 | }; | |
1139 | ||
3989144f | 1140 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1141 | wait_for_completion(&fwork.done); |
1142 | } | |
3989144f | 1143 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1144 | |
1145 | /** | |
1146 | * kthread_destroy_worker - destroy a kthread worker | |
1147 | * @worker: worker to be destroyed | |
1148 | * | |
1149 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1150 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1151 | * machines needed. | |
1152 | */ | |
1153 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1154 | { | |
1155 | struct task_struct *task; | |
1156 | ||
1157 | task = worker->task; | |
1158 | if (WARN_ON(!task)) | |
1159 | return; | |
1160 | ||
1161 | kthread_flush_worker(worker); | |
1162 | kthread_stop(task); | |
1163 | WARN_ON(!list_empty(&worker->work_list)); | |
1164 | kfree(worker); | |
1165 | } | |
1166 | EXPORT_SYMBOL(kthread_destroy_worker); |