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Commit | Line | Data |
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1da177e4 LT |
1 | /* Kernel thread helper functions. |
2 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. | |
3 | * | |
73c27992 | 4 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
5 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
6 | * etc.). | |
7 | */ | |
ae7e81c0 | 8 | #include <uapi/linux/sched/types.h> |
1da177e4 | 9 | #include <linux/sched.h> |
29930025 | 10 | #include <linux/sched/task.h> |
1da177e4 LT |
11 | #include <linux/kthread.h> |
12 | #include <linux/completion.h> | |
13 | #include <linux/err.h> | |
58568d2a | 14 | #include <linux/cpuset.h> |
1da177e4 LT |
15 | #include <linux/unistd.h> |
16 | #include <linux/file.h> | |
9984de1a | 17 | #include <linux/export.h> |
97d1f15b | 18 | #include <linux/mutex.h> |
b56c0d89 TH |
19 | #include <linux/slab.h> |
20 | #include <linux/freezer.h> | |
a74fb73c | 21 | #include <linux/ptrace.h> |
cd42d559 | 22 | #include <linux/uaccess.h> |
ad8d75ff | 23 | #include <trace/events/sched.h> |
1da177e4 | 24 | |
73c27992 EB |
25 | static DEFINE_SPINLOCK(kthread_create_lock); |
26 | static LIST_HEAD(kthread_create_list); | |
27 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
28 | |
29 | struct kthread_create_info | |
30 | { | |
73c27992 | 31 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
32 | int (*threadfn)(void *data); |
33 | void *data; | |
207205a2 | 34 | int node; |
1da177e4 | 35 | |
73c27992 | 36 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 37 | struct task_struct *result; |
786235ee | 38 | struct completion *done; |
65f27f38 | 39 | |
73c27992 | 40 | struct list_head list; |
1da177e4 LT |
41 | }; |
42 | ||
63706172 | 43 | struct kthread { |
2a1d4460 TG |
44 | unsigned long flags; |
45 | unsigned int cpu; | |
82805ab7 | 46 | void *data; |
2a1d4460 | 47 | struct completion parked; |
63706172 | 48 | struct completion exited; |
0b508bc9 | 49 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
50 | struct cgroup_subsys_state *blkcg_css; |
51 | #endif | |
1da177e4 LT |
52 | }; |
53 | ||
2a1d4460 TG |
54 | enum KTHREAD_BITS { |
55 | KTHREAD_IS_PER_CPU = 0, | |
56 | KTHREAD_SHOULD_STOP, | |
57 | KTHREAD_SHOULD_PARK, | |
58 | KTHREAD_IS_PARKED, | |
59 | }; | |
60 | ||
1da5c46f ON |
61 | static inline void set_kthread_struct(void *kthread) |
62 | { | |
63 | /* | |
64 | * We abuse ->set_child_tid to avoid the new member and because it | |
65 | * can't be wrongly copied by copy_process(). We also rely on fact | |
66 | * that the caller can't exec, so PF_KTHREAD can't be cleared. | |
67 | */ | |
68 | current->set_child_tid = (__force void __user *)kthread; | |
69 | } | |
4ecdafc8 ON |
70 | |
71 | static inline struct kthread *to_kthread(struct task_struct *k) | |
72 | { | |
1da5c46f ON |
73 | WARN_ON(!(k->flags & PF_KTHREAD)); |
74 | return (__force void *)k->set_child_tid; | |
4ecdafc8 ON |
75 | } |
76 | ||
1da5c46f ON |
77 | void free_kthread_struct(struct task_struct *k) |
78 | { | |
05e3db95 SL |
79 | struct kthread *kthread; |
80 | ||
1da5c46f ON |
81 | /* |
82 | * Can be NULL if this kthread was created by kernel_thread() | |
83 | * or if kmalloc() in kthread() failed. | |
84 | */ | |
05e3db95 | 85 | kthread = to_kthread(k); |
0b508bc9 | 86 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
87 | WARN_ON_ONCE(kthread && kthread->blkcg_css); |
88 | #endif | |
89 | kfree(kthread); | |
1da5c46f ON |
90 | } |
91 | ||
9e37bd30 RD |
92 | /** |
93 | * kthread_should_stop - should this kthread return now? | |
94 | * | |
72fd4a35 | 95 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
96 | * and this will return true. You should then return, and your return |
97 | * value will be passed through to kthread_stop(). | |
98 | */ | |
2a1d4460 | 99 | bool kthread_should_stop(void) |
1da177e4 | 100 | { |
2a1d4460 | 101 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
102 | } |
103 | EXPORT_SYMBOL(kthread_should_stop); | |
104 | ||
2a1d4460 TG |
105 | /** |
106 | * kthread_should_park - should this kthread park now? | |
107 | * | |
108 | * When someone calls kthread_park() on your kthread, it will be woken | |
109 | * and this will return true. You should then do the necessary | |
110 | * cleanup and call kthread_parkme() | |
111 | * | |
112 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
113 | * and in a park position. kthread_unpark() "restarts" the thread and | |
114 | * calls the thread function again. | |
115 | */ | |
116 | bool kthread_should_park(void) | |
117 | { | |
118 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags); | |
119 | } | |
18896451 | 120 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 121 | |
8a32c441 TH |
122 | /** |
123 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
124 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
125 | * | |
126 | * kthread_should_stop() for freezable kthreads, which will enter | |
127 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
128 | * freezer deadlock and freezable kthreads should use this function instead | |
129 | * of calling try_to_freeze() directly. | |
130 | */ | |
131 | bool kthread_freezable_should_stop(bool *was_frozen) | |
132 | { | |
133 | bool frozen = false; | |
134 | ||
135 | might_sleep(); | |
136 | ||
137 | if (unlikely(freezing(current))) | |
138 | frozen = __refrigerator(true); | |
139 | ||
140 | if (was_frozen) | |
141 | *was_frozen = frozen; | |
142 | ||
143 | return kthread_should_stop(); | |
144 | } | |
145 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
146 | ||
82805ab7 TH |
147 | /** |
148 | * kthread_data - return data value specified on kthread creation | |
149 | * @task: kthread task in question | |
150 | * | |
151 | * Return the data value specified when kthread @task was created. | |
152 | * The caller is responsible for ensuring the validity of @task when | |
153 | * calling this function. | |
154 | */ | |
155 | void *kthread_data(struct task_struct *task) | |
156 | { | |
157 | return to_kthread(task)->data; | |
158 | } | |
159 | ||
cd42d559 | 160 | /** |
e700591a | 161 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
162 | * @task: possible kthread task in question |
163 | * | |
164 | * @task could be a kthread task. Return the data value specified when it | |
165 | * was created if accessible. If @task isn't a kthread task or its data is | |
166 | * inaccessible for any reason, %NULL is returned. This function requires | |
167 | * that @task itself is safe to dereference. | |
168 | */ | |
e700591a | 169 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 TH |
170 | { |
171 | struct kthread *kthread = to_kthread(task); | |
172 | void *data = NULL; | |
173 | ||
174 | probe_kernel_read(&data, &kthread->data, sizeof(data)); | |
175 | return data; | |
176 | } | |
177 | ||
2a1d4460 TG |
178 | static void __kthread_parkme(struct kthread *self) |
179 | { | |
f2530dc7 | 180 | __set_current_state(TASK_PARKED); |
2a1d4460 TG |
181 | while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) { |
182 | if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags)) | |
183 | complete(&self->parked); | |
184 | schedule(); | |
f2530dc7 | 185 | __set_current_state(TASK_PARKED); |
2a1d4460 TG |
186 | } |
187 | clear_bit(KTHREAD_IS_PARKED, &self->flags); | |
188 | __set_current_state(TASK_RUNNING); | |
189 | } | |
190 | ||
191 | void kthread_parkme(void) | |
192 | { | |
193 | __kthread_parkme(to_kthread(current)); | |
194 | } | |
18896451 | 195 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 196 | |
1da177e4 LT |
197 | static int kthread(void *_create) |
198 | { | |
63706172 | 199 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 200 | struct kthread_create_info *create = _create; |
63706172 ON |
201 | int (*threadfn)(void *data) = create->threadfn; |
202 | void *data = create->data; | |
786235ee | 203 | struct completion *done; |
1da5c46f | 204 | struct kthread *self; |
63706172 | 205 | int ret; |
1da177e4 | 206 | |
e10237cc | 207 | self = kzalloc(sizeof(*self), GFP_KERNEL); |
1da5c46f | 208 | set_kthread_struct(self); |
1da177e4 | 209 | |
786235ee TH |
210 | /* If user was SIGKILLed, I release the structure. */ |
211 | done = xchg(&create->done, NULL); | |
212 | if (!done) { | |
213 | kfree(create); | |
214 | do_exit(-EINTR); | |
215 | } | |
1da5c46f ON |
216 | |
217 | if (!self) { | |
218 | create->result = ERR_PTR(-ENOMEM); | |
219 | complete(done); | |
220 | do_exit(-ENOMEM); | |
221 | } | |
222 | ||
1da5c46f ON |
223 | self->data = data; |
224 | init_completion(&self->exited); | |
225 | init_completion(&self->parked); | |
226 | current->vfork_done = &self->exited; | |
227 | ||
1da177e4 | 228 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 229 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 230 | create->result = current; |
786235ee | 231 | complete(done); |
1da177e4 LT |
232 | schedule(); |
233 | ||
63706172 | 234 | ret = -EINTR; |
1da5c46f | 235 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
77f88796 | 236 | cgroup_kthread_ready(); |
1da5c46f | 237 | __kthread_parkme(self); |
2a1d4460 TG |
238 | ret = threadfn(data); |
239 | } | |
63706172 | 240 | do_exit(ret); |
1da177e4 LT |
241 | } |
242 | ||
207205a2 ED |
243 | /* called from do_fork() to get node information for about to be created task */ |
244 | int tsk_fork_get_node(struct task_struct *tsk) | |
245 | { | |
246 | #ifdef CONFIG_NUMA | |
247 | if (tsk == kthreadd_task) | |
248 | return tsk->pref_node_fork; | |
249 | #endif | |
81c98869 | 250 | return NUMA_NO_NODE; |
207205a2 ED |
251 | } |
252 | ||
73c27992 | 253 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 254 | { |
1da177e4 LT |
255 | int pid; |
256 | ||
207205a2 ED |
257 | #ifdef CONFIG_NUMA |
258 | current->pref_node_fork = create->node; | |
259 | #endif | |
1da177e4 LT |
260 | /* We want our own signal handler (we take no signals by default). */ |
261 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 262 | if (pid < 0) { |
786235ee TH |
263 | /* If user was SIGKILLed, I release the structure. */ |
264 | struct completion *done = xchg(&create->done, NULL); | |
265 | ||
266 | if (!done) { | |
267 | kfree(create); | |
268 | return; | |
269 | } | |
1da177e4 | 270 | create->result = ERR_PTR(pid); |
786235ee | 271 | complete(done); |
cdd140bd | 272 | } |
1da177e4 LT |
273 | } |
274 | ||
c0b942a7 NI |
275 | static __printf(4, 0) |
276 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
277 | void *data, int node, |
278 | const char namefmt[], | |
279 | va_list args) | |
1da177e4 | 280 | { |
786235ee TH |
281 | DECLARE_COMPLETION_ONSTACK(done); |
282 | struct task_struct *task; | |
283 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
284 | GFP_KERNEL); | |
285 | ||
286 | if (!create) | |
287 | return ERR_PTR(-ENOMEM); | |
288 | create->threadfn = threadfn; | |
289 | create->data = data; | |
290 | create->node = node; | |
291 | create->done = &done; | |
73c27992 EB |
292 | |
293 | spin_lock(&kthread_create_lock); | |
786235ee | 294 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
295 | spin_unlock(&kthread_create_lock); |
296 | ||
cbd9b67b | 297 | wake_up_process(kthreadd_task); |
786235ee TH |
298 | /* |
299 | * Wait for completion in killable state, for I might be chosen by | |
300 | * the OOM killer while kthreadd is trying to allocate memory for | |
301 | * new kernel thread. | |
302 | */ | |
303 | if (unlikely(wait_for_completion_killable(&done))) { | |
a0987ba0 TH |
304 | int i = 0; |
305 | ||
306 | /* | |
307 | * I got SIGKILL, but wait for 10 more seconds for completion | |
308 | * unless chosen by the OOM killer. This delay is there as a | |
309 | * workaround for boot failure caused by SIGKILL upon device | |
310 | * driver initialization timeout. | |
311 | */ | |
312 | while (i++ < 10 && !test_tsk_thread_flag(current, TIF_MEMDIE)) | |
313 | if (wait_for_completion_timeout(&done, HZ)) | |
314 | goto ready; | |
786235ee TH |
315 | /* |
316 | * If I was SIGKILLed before kthreadd (or new kernel thread) | |
317 | * calls complete(), leave the cleanup of this structure to | |
318 | * that thread. | |
319 | */ | |
320 | if (xchg(&create->done, NULL)) | |
8fe6929c | 321 | return ERR_PTR(-EINTR); |
786235ee TH |
322 | /* |
323 | * kthreadd (or new kernel thread) will call complete() | |
324 | * shortly. | |
325 | */ | |
326 | wait_for_completion(&done); | |
327 | } | |
a0987ba0 | 328 | ready: |
786235ee TH |
329 | task = create->result; |
330 | if (!IS_ERR(task)) { | |
c9b5f501 | 331 | static const struct sched_param param = { .sched_priority = 0 }; |
1c99315b | 332 | |
786235ee | 333 | vsnprintf(task->comm, sizeof(task->comm), namefmt, args); |
1c99315b ON |
334 | /* |
335 | * root may have changed our (kthreadd's) priority or CPU mask. | |
336 | * The kernel thread should not inherit these properties. | |
337 | */ | |
786235ee TH |
338 | sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
339 | set_cpus_allowed_ptr(task, cpu_all_mask); | |
1da177e4 | 340 | } |
786235ee TH |
341 | kfree(create); |
342 | return task; | |
1da177e4 | 343 | } |
255451e4 PM |
344 | |
345 | /** | |
346 | * kthread_create_on_node - create a kthread. | |
347 | * @threadfn: the function to run until signal_pending(current). | |
348 | * @data: data ptr for @threadfn. | |
349 | * @node: task and thread structures for the thread are allocated on this node | |
350 | * @namefmt: printf-style name for the thread. | |
351 | * | |
352 | * Description: This helper function creates and names a kernel | |
353 | * thread. The thread will be stopped: use wake_up_process() to start | |
354 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
355 | * is affine to all CPUs. | |
356 | * | |
357 | * If thread is going to be bound on a particular cpu, give its node | |
358 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
359 | * When woken, the thread will run @threadfn() with @data as its | |
360 | * argument. @threadfn() can either call do_exit() directly if it is a | |
361 | * standalone thread for which no one will call kthread_stop(), or | |
362 | * return when 'kthread_should_stop()' is true (which means | |
363 | * kthread_stop() has been called). The return value should be zero | |
364 | * or a negative error number; it will be passed to kthread_stop(). | |
365 | * | |
366 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
367 | */ | |
368 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
369 | void *data, int node, | |
370 | const char namefmt[], | |
371 | ...) | |
372 | { | |
373 | struct task_struct *task; | |
374 | va_list args; | |
375 | ||
376 | va_start(args, namefmt); | |
377 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
378 | va_end(args); | |
379 | ||
380 | return task; | |
381 | } | |
207205a2 | 382 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 383 | |
25834c73 | 384 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
2a1d4460 | 385 | { |
25834c73 PZ |
386 | unsigned long flags; |
387 | ||
f2530dc7 TG |
388 | if (!wait_task_inactive(p, state)) { |
389 | WARN_ON(1); | |
390 | return; | |
391 | } | |
25834c73 | 392 | |
2a1d4460 | 393 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
394 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
395 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 396 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
397 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
398 | } | |
399 | ||
400 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) | |
401 | { | |
402 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
403 | } | |
404 | ||
405 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
406 | { | |
407 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
408 | } |
409 | ||
881232b7 PZ |
410 | /** |
411 | * kthread_bind - bind a just-created kthread to a cpu. | |
412 | * @p: thread created by kthread_create(). | |
413 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
414 | * | |
415 | * Description: This function is equivalent to set_cpus_allowed(), | |
416 | * except that @cpu doesn't need to be online, and the thread must be | |
417 | * stopped (i.e., just returned from kthread_create()). | |
418 | */ | |
419 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
420 | { | |
f2530dc7 | 421 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
422 | } |
423 | EXPORT_SYMBOL(kthread_bind); | |
424 | ||
2a1d4460 TG |
425 | /** |
426 | * kthread_create_on_cpu - Create a cpu bound kthread | |
427 | * @threadfn: the function to run until signal_pending(current). | |
428 | * @data: data ptr for @threadfn. | |
429 | * @cpu: The cpu on which the thread should be bound, | |
430 | * @namefmt: printf-style name for the thread. Format is restricted | |
431 | * to "name.*%u". Code fills in cpu number. | |
432 | * | |
433 | * Description: This helper function creates and names a kernel thread | |
434 | * The thread will be woken and put into park mode. | |
435 | */ | |
436 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
437 | void *data, unsigned int cpu, | |
438 | const char *namefmt) | |
439 | { | |
440 | struct task_struct *p; | |
441 | ||
10922838 | 442 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
443 | cpu); |
444 | if (IS_ERR(p)) | |
445 | return p; | |
a65d4096 PM |
446 | kthread_bind(p, cpu); |
447 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 TG |
448 | set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); |
449 | to_kthread(p)->cpu = cpu; | |
2a1d4460 TG |
450 | return p; |
451 | } | |
452 | ||
cf380a4a ON |
453 | /** |
454 | * kthread_unpark - unpark a thread created by kthread_create(). | |
455 | * @k: thread created by kthread_create(). | |
456 | * | |
457 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
458 | * waits for it to return. If the thread is marked percpu then its | |
459 | * bound to the cpu again. | |
460 | */ | |
461 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 462 | { |
cf380a4a ON |
463 | struct kthread *kthread = to_kthread(k); |
464 | ||
f2530dc7 TG |
465 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
466 | /* | |
467 | * We clear the IS_PARKED bit here as we don't wait | |
468 | * until the task has left the park code. So if we'd | |
469 | * park before that happens we'd see the IS_PARKED bit | |
470 | * which might be about to be cleared. | |
471 | */ | |
472 | if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) { | |
a65d4096 PM |
473 | /* |
474 | * Newly created kthread was parked when the CPU was offline. | |
475 | * The binding was lost and we need to set it again. | |
476 | */ | |
f2530dc7 TG |
477 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
478 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
479 | wake_up_state(k, TASK_PARKED); | |
480 | } | |
481 | } | |
18896451 | 482 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
483 | |
484 | /** | |
485 | * kthread_park - park a thread created by kthread_create(). | |
486 | * @k: thread created by kthread_create(). | |
487 | * | |
488 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
489 | * waits for it to return. This can also be called after kthread_create() | |
490 | * instead of calling wake_up_process(): the thread will park without | |
491 | * calling threadfn(). | |
492 | * | |
493 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
494 | * If called by the kthread itself just the park bit is set. | |
495 | */ | |
496 | int kthread_park(struct task_struct *k) | |
497 | { | |
cf380a4a ON |
498 | struct kthread *kthread = to_kthread(k); |
499 | ||
500 | if (WARN_ON(k->flags & PF_EXITING)) | |
501 | return -ENOSYS; | |
502 | ||
503 | if (!test_bit(KTHREAD_IS_PARKED, &kthread->flags)) { | |
504 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
505 | if (k != current) { | |
506 | wake_up_process(k); | |
507 | wait_for_completion(&kthread->parked); | |
2a1d4460 | 508 | } |
2a1d4460 | 509 | } |
cf380a4a ON |
510 | |
511 | return 0; | |
2a1d4460 | 512 | } |
18896451 | 513 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 514 | |
9e37bd30 RD |
515 | /** |
516 | * kthread_stop - stop a thread created by kthread_create(). | |
517 | * @k: thread created by kthread_create(). | |
518 | * | |
519 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
520 | * waits for it to exit. This can also be called after kthread_create() |
521 | * instead of calling wake_up_process(): the thread will exit without | |
522 | * calling threadfn(). | |
523 | * | |
524 | * If threadfn() may call do_exit() itself, the caller must ensure | |
525 | * task_struct can't go away. | |
9e37bd30 RD |
526 | * |
527 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
528 | * was never called. | |
529 | */ | |
1da177e4 LT |
530 | int kthread_stop(struct task_struct *k) |
531 | { | |
b5c5442b | 532 | struct kthread *kthread; |
1da177e4 LT |
533 | int ret; |
534 | ||
0a16b607 | 535 | trace_sched_kthread_stop(k); |
b5c5442b ON |
536 | |
537 | get_task_struct(k); | |
efb29fbf ON |
538 | kthread = to_kthread(k); |
539 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 540 | kthread_unpark(k); |
efb29fbf ON |
541 | wake_up_process(k); |
542 | wait_for_completion(&kthread->exited); | |
63706172 | 543 | ret = k->exit_code; |
1da177e4 | 544 | put_task_struct(k); |
0a16b607 | 545 | |
b5c5442b | 546 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
547 | return ret; |
548 | } | |
52e92e57 | 549 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 550 | |
e804a4a4 | 551 | int kthreadd(void *unused) |
1da177e4 | 552 | { |
73c27992 | 553 | struct task_struct *tsk = current; |
1da177e4 | 554 | |
e804a4a4 | 555 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 556 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 557 | ignore_signals(tsk); |
1a2142af | 558 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa4 | 559 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 560 | |
34b087e4 | 561 | current->flags |= PF_NOFREEZE; |
77f88796 | 562 | cgroup_init_kthreadd(); |
73c27992 EB |
563 | |
564 | for (;;) { | |
565 | set_current_state(TASK_INTERRUPTIBLE); | |
566 | if (list_empty(&kthread_create_list)) | |
567 | schedule(); | |
568 | __set_current_state(TASK_RUNNING); | |
569 | ||
570 | spin_lock(&kthread_create_lock); | |
571 | while (!list_empty(&kthread_create_list)) { | |
572 | struct kthread_create_info *create; | |
573 | ||
574 | create = list_entry(kthread_create_list.next, | |
575 | struct kthread_create_info, list); | |
576 | list_del_init(&create->list); | |
577 | spin_unlock(&kthread_create_lock); | |
578 | ||
579 | create_kthread(create); | |
580 | ||
581 | spin_lock(&kthread_create_lock); | |
582 | } | |
583 | spin_unlock(&kthread_create_lock); | |
584 | } | |
585 | ||
586 | return 0; | |
587 | } | |
b56c0d89 | 588 | |
3989144f | 589 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
590 | const char *name, |
591 | struct lock_class_key *key) | |
592 | { | |
dbf52682 | 593 | memset(worker, 0, sizeof(struct kthread_worker)); |
4f32e9b1 YZ |
594 | spin_lock_init(&worker->lock); |
595 | lockdep_set_class_and_name(&worker->lock, key, name); | |
596 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 597 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 598 | } |
3989144f | 599 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 600 | |
b56c0d89 TH |
601 | /** |
602 | * kthread_worker_fn - kthread function to process kthread_worker | |
603 | * @worker_ptr: pointer to initialized kthread_worker | |
604 | * | |
fbae2d44 PM |
605 | * This function implements the main cycle of kthread worker. It processes |
606 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
607 | * is empty. | |
b56c0d89 | 608 | * |
fbae2d44 PM |
609 | * The works are not allowed to keep any locks, disable preemption or interrupts |
610 | * when they finish. There is defined a safe point for freezing when one work | |
611 | * finishes and before a new one is started. | |
8197b3d4 PM |
612 | * |
613 | * Also the works must not be handled by more than one worker at the same time, | |
614 | * see also kthread_queue_work(). | |
b56c0d89 TH |
615 | */ |
616 | int kthread_worker_fn(void *worker_ptr) | |
617 | { | |
618 | struct kthread_worker *worker = worker_ptr; | |
619 | struct kthread_work *work; | |
620 | ||
fbae2d44 PM |
621 | /* |
622 | * FIXME: Update the check and remove the assignment when all kthread | |
623 | * worker users are created using kthread_create_worker*() functions. | |
624 | */ | |
625 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 626 | worker->task = current; |
dbf52682 PM |
627 | |
628 | if (worker->flags & KTW_FREEZABLE) | |
629 | set_freezable(); | |
630 | ||
b56c0d89 TH |
631 | repeat: |
632 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
633 | ||
634 | if (kthread_should_stop()) { | |
635 | __set_current_state(TASK_RUNNING); | |
636 | spin_lock_irq(&worker->lock); | |
637 | worker->task = NULL; | |
638 | spin_unlock_irq(&worker->lock); | |
639 | return 0; | |
640 | } | |
641 | ||
642 | work = NULL; | |
643 | spin_lock_irq(&worker->lock); | |
644 | if (!list_empty(&worker->work_list)) { | |
645 | work = list_first_entry(&worker->work_list, | |
646 | struct kthread_work, node); | |
647 | list_del_init(&work->node); | |
648 | } | |
46f3d976 | 649 | worker->current_work = work; |
b56c0d89 TH |
650 | spin_unlock_irq(&worker->lock); |
651 | ||
652 | if (work) { | |
653 | __set_current_state(TASK_RUNNING); | |
654 | work->func(work); | |
b56c0d89 TH |
655 | } else if (!freezing(current)) |
656 | schedule(); | |
657 | ||
658 | try_to_freeze(); | |
22cf8bc6 | 659 | cond_resched(); |
b56c0d89 TH |
660 | goto repeat; |
661 | } | |
662 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
663 | ||
c0b942a7 | 664 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
665 | __kthread_create_worker(int cpu, unsigned int flags, |
666 | const char namefmt[], va_list args) | |
fbae2d44 PM |
667 | { |
668 | struct kthread_worker *worker; | |
669 | struct task_struct *task; | |
8fb9dcbd | 670 | int node = -1; |
fbae2d44 PM |
671 | |
672 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
673 | if (!worker) | |
674 | return ERR_PTR(-ENOMEM); | |
675 | ||
676 | kthread_init_worker(worker); | |
677 | ||
8fb9dcbd ON |
678 | if (cpu >= 0) |
679 | node = cpu_to_node(cpu); | |
fbae2d44 | 680 | |
8fb9dcbd ON |
681 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
682 | node, namefmt, args); | |
fbae2d44 PM |
683 | if (IS_ERR(task)) |
684 | goto fail_task; | |
685 | ||
8fb9dcbd ON |
686 | if (cpu >= 0) |
687 | kthread_bind(task, cpu); | |
688 | ||
dbf52682 | 689 | worker->flags = flags; |
fbae2d44 PM |
690 | worker->task = task; |
691 | wake_up_process(task); | |
692 | return worker; | |
693 | ||
694 | fail_task: | |
695 | kfree(worker); | |
696 | return ERR_CAST(task); | |
697 | } | |
698 | ||
699 | /** | |
700 | * kthread_create_worker - create a kthread worker | |
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 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
705 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
706 | * when the worker was SIGKILLed. | |
707 | */ | |
708 | struct kthread_worker * | |
dbf52682 | 709 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
710 | { |
711 | struct kthread_worker *worker; | |
712 | va_list args; | |
713 | ||
714 | va_start(args, namefmt); | |
dbf52682 | 715 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
716 | va_end(args); |
717 | ||
718 | return worker; | |
719 | } | |
720 | EXPORT_SYMBOL(kthread_create_worker); | |
721 | ||
722 | /** | |
723 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
724 | * it to a given CPU and the associated NUMA node. | |
725 | * @cpu: CPU number | |
dbf52682 | 726 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
727 | * @namefmt: printf-style name for the kthread worker (task). |
728 | * | |
729 | * Use a valid CPU number if you want to bind the kthread worker | |
730 | * to the given CPU and the associated NUMA node. | |
731 | * | |
732 | * A good practice is to add the cpu number also into the worker name. | |
733 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
734 | * | |
735 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
736 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
737 | * when the worker was SIGKILLed. | |
738 | */ | |
739 | struct kthread_worker * | |
dbf52682 PM |
740 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
741 | const char namefmt[], ...) | |
fbae2d44 PM |
742 | { |
743 | struct kthread_worker *worker; | |
744 | va_list args; | |
745 | ||
746 | va_start(args, namefmt); | |
dbf52682 | 747 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
748 | va_end(args); |
749 | ||
750 | return worker; | |
751 | } | |
752 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
753 | ||
37be45d4 PM |
754 | /* |
755 | * Returns true when the work could not be queued at the moment. | |
756 | * It happens when it is already pending in a worker list | |
757 | * or when it is being cancelled. | |
758 | */ | |
759 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
760 | struct kthread_work *work) | |
761 | { | |
762 | lockdep_assert_held(&worker->lock); | |
763 | ||
764 | return !list_empty(&work->node) || work->canceling; | |
765 | } | |
766 | ||
8197b3d4 PM |
767 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
768 | struct kthread_work *work) | |
769 | { | |
770 | lockdep_assert_held(&worker->lock); | |
771 | WARN_ON_ONCE(!list_empty(&work->node)); | |
772 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
773 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
774 | } | |
775 | ||
9a2e03d8 | 776 | /* insert @work before @pos in @worker */ |
3989144f | 777 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
778 | struct kthread_work *work, |
779 | struct list_head *pos) | |
9a2e03d8 | 780 | { |
8197b3d4 | 781 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 TH |
782 | |
783 | list_add_tail(&work->node, pos); | |
46f3d976 | 784 | work->worker = worker; |
ed1403ec | 785 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
786 | wake_up_process(worker->task); |
787 | } | |
788 | ||
b56c0d89 | 789 | /** |
3989144f | 790 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
791 | * @worker: target kthread_worker |
792 | * @work: kthread_work to queue | |
793 | * | |
794 | * Queue @work to work processor @task for async execution. @task | |
795 | * must have been created with kthread_worker_create(). Returns %true | |
796 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
797 | * |
798 | * Reinitialize the work if it needs to be used by another worker. | |
799 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 800 | */ |
3989144f | 801 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
802 | struct kthread_work *work) |
803 | { | |
804 | bool ret = false; | |
805 | unsigned long flags; | |
806 | ||
807 | spin_lock_irqsave(&worker->lock, flags); | |
37be45d4 | 808 | if (!queuing_blocked(worker, work)) { |
3989144f | 809 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
810 | ret = true; |
811 | } | |
812 | spin_unlock_irqrestore(&worker->lock, flags); | |
813 | return ret; | |
814 | } | |
3989144f | 815 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 816 | |
22597dc3 PM |
817 | /** |
818 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
819 | * delayed work when the timer expires. | |
fe5c3b69 | 820 | * @t: pointer to the expired timer |
22597dc3 PM |
821 | * |
822 | * The format of the function is defined by struct timer_list. | |
823 | * It should have been called from irqsafe timer with irq already off. | |
824 | */ | |
fe5c3b69 | 825 | void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3 | 826 | { |
fe5c3b69 | 827 | struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3 PM |
828 | struct kthread_work *work = &dwork->work; |
829 | struct kthread_worker *worker = work->worker; | |
830 | ||
831 | /* | |
832 | * This might happen when a pending work is reinitialized. | |
833 | * It means that it is used a wrong way. | |
834 | */ | |
835 | if (WARN_ON_ONCE(!worker)) | |
836 | return; | |
837 | ||
838 | spin_lock(&worker->lock); | |
839 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ | |
840 | WARN_ON_ONCE(work->worker != worker); | |
841 | ||
842 | /* Move the work from worker->delayed_work_list. */ | |
843 | WARN_ON_ONCE(list_empty(&work->node)); | |
844 | list_del_init(&work->node); | |
845 | kthread_insert_work(worker, work, &worker->work_list); | |
846 | ||
847 | spin_unlock(&worker->lock); | |
848 | } | |
849 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
850 | ||
851 | void __kthread_queue_delayed_work(struct kthread_worker *worker, | |
852 | struct kthread_delayed_work *dwork, | |
853 | unsigned long delay) | |
854 | { | |
855 | struct timer_list *timer = &dwork->timer; | |
856 | struct kthread_work *work = &dwork->work; | |
857 | ||
841b86f3 | 858 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3 PM |
859 | |
860 | /* | |
861 | * If @delay is 0, queue @dwork->work immediately. This is for | |
862 | * both optimization and correctness. The earliest @timer can | |
863 | * expire is on the closest next tick and delayed_work users depend | |
864 | * on that there's no such delay when @delay is 0. | |
865 | */ | |
866 | if (!delay) { | |
867 | kthread_insert_work(worker, work, &worker->work_list); | |
868 | return; | |
869 | } | |
870 | ||
871 | /* Be paranoid and try to detect possible races already now. */ | |
872 | kthread_insert_work_sanity_check(worker, work); | |
873 | ||
874 | list_add(&work->node, &worker->delayed_work_list); | |
875 | work->worker = worker; | |
22597dc3 PM |
876 | timer->expires = jiffies + delay; |
877 | add_timer(timer); | |
878 | } | |
879 | ||
880 | /** | |
881 | * kthread_queue_delayed_work - queue the associated kthread work | |
882 | * after a delay. | |
883 | * @worker: target kthread_worker | |
884 | * @dwork: kthread_delayed_work to queue | |
885 | * @delay: number of jiffies to wait before queuing | |
886 | * | |
887 | * If the work has not been pending it starts a timer that will queue | |
888 | * the work after the given @delay. If @delay is zero, it queues the | |
889 | * work immediately. | |
890 | * | |
891 | * Return: %false if the @work has already been pending. It means that | |
892 | * either the timer was running or the work was queued. It returns %true | |
893 | * otherwise. | |
894 | */ | |
895 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
896 | struct kthread_delayed_work *dwork, | |
897 | unsigned long delay) | |
898 | { | |
899 | struct kthread_work *work = &dwork->work; | |
900 | unsigned long flags; | |
901 | bool ret = false; | |
902 | ||
903 | spin_lock_irqsave(&worker->lock, flags); | |
904 | ||
37be45d4 | 905 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
906 | __kthread_queue_delayed_work(worker, dwork, delay); |
907 | ret = true; | |
908 | } | |
909 | ||
910 | spin_unlock_irqrestore(&worker->lock, flags); | |
911 | return ret; | |
912 | } | |
913 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
914 | ||
9a2e03d8 TH |
915 | struct kthread_flush_work { |
916 | struct kthread_work work; | |
917 | struct completion done; | |
918 | }; | |
919 | ||
920 | static void kthread_flush_work_fn(struct kthread_work *work) | |
921 | { | |
922 | struct kthread_flush_work *fwork = | |
923 | container_of(work, struct kthread_flush_work, work); | |
924 | complete(&fwork->done); | |
925 | } | |
926 | ||
b56c0d89 | 927 | /** |
3989144f | 928 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
929 | * @work: work to flush |
930 | * | |
931 | * If @work is queued or executing, wait for it to finish execution. | |
932 | */ | |
3989144f | 933 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 934 | { |
46f3d976 TH |
935 | struct kthread_flush_work fwork = { |
936 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
937 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
938 | }; | |
939 | struct kthread_worker *worker; | |
940 | bool noop = false; | |
941 | ||
46f3d976 TH |
942 | worker = work->worker; |
943 | if (!worker) | |
944 | return; | |
b56c0d89 | 945 | |
46f3d976 | 946 | spin_lock_irq(&worker->lock); |
8197b3d4 PM |
947 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
948 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 949 | |
46f3d976 | 950 | if (!list_empty(&work->node)) |
3989144f | 951 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 952 | else if (worker->current_work == work) |
3989144f PM |
953 | kthread_insert_work(worker, &fwork.work, |
954 | worker->work_list.next); | |
46f3d976 TH |
955 | else |
956 | noop = true; | |
b56c0d89 | 957 | |
46f3d976 | 958 | spin_unlock_irq(&worker->lock); |
b56c0d89 | 959 | |
46f3d976 TH |
960 | if (!noop) |
961 | wait_for_completion(&fwork.done); | |
b56c0d89 | 962 | } |
3989144f | 963 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 964 | |
37be45d4 PM |
965 | /* |
966 | * This function removes the work from the worker queue. Also it makes sure | |
967 | * that it won't get queued later via the delayed work's timer. | |
968 | * | |
969 | * The work might still be in use when this function finishes. See the | |
970 | * current_work proceed by the worker. | |
971 | * | |
972 | * Return: %true if @work was pending and successfully canceled, | |
973 | * %false if @work was not pending | |
974 | */ | |
975 | static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork, | |
976 | unsigned long *flags) | |
977 | { | |
978 | /* Try to cancel the timer if exists. */ | |
979 | if (is_dwork) { | |
980 | struct kthread_delayed_work *dwork = | |
981 | container_of(work, struct kthread_delayed_work, work); | |
982 | struct kthread_worker *worker = work->worker; | |
983 | ||
984 | /* | |
985 | * del_timer_sync() must be called to make sure that the timer | |
986 | * callback is not running. The lock must be temporary released | |
987 | * to avoid a deadlock with the callback. In the meantime, | |
988 | * any queuing is blocked by setting the canceling counter. | |
989 | */ | |
990 | work->canceling++; | |
991 | spin_unlock_irqrestore(&worker->lock, *flags); | |
992 | del_timer_sync(&dwork->timer); | |
993 | spin_lock_irqsave(&worker->lock, *flags); | |
994 | work->canceling--; | |
995 | } | |
996 | ||
997 | /* | |
998 | * Try to remove the work from a worker list. It might either | |
999 | * be from worker->work_list or from worker->delayed_work_list. | |
1000 | */ | |
1001 | if (!list_empty(&work->node)) { | |
1002 | list_del_init(&work->node); | |
1003 | return true; | |
1004 | } | |
1005 | ||
1006 | return false; | |
1007 | } | |
1008 | ||
9a6b06c8 PM |
1009 | /** |
1010 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1011 | * @worker: kthread worker to use | |
1012 | * @dwork: kthread delayed work to queue | |
1013 | * @delay: number of jiffies to wait before queuing | |
1014 | * | |
1015 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1016 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1017 | * @work is guaranteed to be queued immediately. | |
1018 | * | |
1019 | * Return: %true if @dwork was pending and its timer was modified, | |
1020 | * %false otherwise. | |
1021 | * | |
1022 | * A special case is when the work is being canceled in parallel. | |
1023 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1024 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
1025 | * win and return %false here. The caller is supposed to synchronize these | |
1026 | * operations a reasonable way. | |
1027 | * | |
1028 | * This function is safe to call from any context including IRQ handler. | |
1029 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1030 | * for details. | |
1031 | */ | |
1032 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1033 | struct kthread_delayed_work *dwork, | |
1034 | unsigned long delay) | |
1035 | { | |
1036 | struct kthread_work *work = &dwork->work; | |
1037 | unsigned long flags; | |
1038 | int ret = false; | |
1039 | ||
1040 | spin_lock_irqsave(&worker->lock, flags); | |
1041 | ||
1042 | /* Do not bother with canceling when never queued. */ | |
1043 | if (!work->worker) | |
1044 | goto fast_queue; | |
1045 | ||
1046 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1047 | WARN_ON_ONCE(work->worker != worker); | |
1048 | ||
1049 | /* Do not fight with another command that is canceling this work. */ | |
1050 | if (work->canceling) | |
1051 | goto out; | |
1052 | ||
1053 | ret = __kthread_cancel_work(work, true, &flags); | |
1054 | fast_queue: | |
1055 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1056 | out: | |
1057 | spin_unlock_irqrestore(&worker->lock, flags); | |
1058 | return ret; | |
1059 | } | |
1060 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1061 | ||
37be45d4 PM |
1062 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1063 | { | |
1064 | struct kthread_worker *worker = work->worker; | |
1065 | unsigned long flags; | |
1066 | int ret = false; | |
1067 | ||
1068 | if (!worker) | |
1069 | goto out; | |
1070 | ||
1071 | spin_lock_irqsave(&worker->lock, flags); | |
1072 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ | |
1073 | WARN_ON_ONCE(work->worker != worker); | |
1074 | ||
1075 | ret = __kthread_cancel_work(work, is_dwork, &flags); | |
1076 | ||
1077 | if (worker->current_work != work) | |
1078 | goto out_fast; | |
1079 | ||
1080 | /* | |
1081 | * The work is in progress and we need to wait with the lock released. | |
1082 | * In the meantime, block any queuing by setting the canceling counter. | |
1083 | */ | |
1084 | work->canceling++; | |
1085 | spin_unlock_irqrestore(&worker->lock, flags); | |
1086 | kthread_flush_work(work); | |
1087 | spin_lock_irqsave(&worker->lock, flags); | |
1088 | work->canceling--; | |
1089 | ||
1090 | out_fast: | |
1091 | spin_unlock_irqrestore(&worker->lock, flags); | |
1092 | out: | |
1093 | return ret; | |
1094 | } | |
1095 | ||
1096 | /** | |
1097 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1098 | * @work: the kthread work to cancel | |
1099 | * | |
1100 | * Cancel @work and wait for its execution to finish. This function | |
1101 | * can be used even if the work re-queues itself. On return from this | |
1102 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1103 | * | |
1104 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1105 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1106 | * | |
1107 | * The caller must ensure that the worker on which @work was last | |
1108 | * queued can't be destroyed before this function returns. | |
1109 | * | |
1110 | * Return: %true if @work was pending, %false otherwise. | |
1111 | */ | |
1112 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1113 | { | |
1114 | return __kthread_cancel_work_sync(work, false); | |
1115 | } | |
1116 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1117 | ||
1118 | /** | |
1119 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1120 | * wait for it to finish. | |
1121 | * @dwork: the kthread delayed work to cancel | |
1122 | * | |
1123 | * This is kthread_cancel_work_sync() for delayed works. | |
1124 | * | |
1125 | * Return: %true if @dwork was pending, %false otherwise. | |
1126 | */ | |
1127 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1128 | { | |
1129 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1130 | } | |
1131 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1132 | ||
b56c0d89 | 1133 | /** |
3989144f | 1134 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1135 | * @worker: worker to flush |
1136 | * | |
1137 | * Wait until all currently executing or pending works on @worker are | |
1138 | * finished. | |
1139 | */ | |
3989144f | 1140 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1141 | { |
1142 | struct kthread_flush_work fwork = { | |
1143 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1144 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1145 | }; | |
1146 | ||
3989144f | 1147 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1148 | wait_for_completion(&fwork.done); |
1149 | } | |
3989144f | 1150 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1151 | |
1152 | /** | |
1153 | * kthread_destroy_worker - destroy a kthread worker | |
1154 | * @worker: worker to be destroyed | |
1155 | * | |
1156 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1157 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1158 | * machines needed. | |
1159 | */ | |
1160 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1161 | { | |
1162 | struct task_struct *task; | |
1163 | ||
1164 | task = worker->task; | |
1165 | if (WARN_ON(!task)) | |
1166 | return; | |
1167 | ||
1168 | kthread_flush_worker(worker); | |
1169 | kthread_stop(task); | |
1170 | WARN_ON(!list_empty(&worker->work_list)); | |
1171 | kfree(worker); | |
1172 | } | |
1173 | EXPORT_SYMBOL(kthread_destroy_worker); | |
05e3db95 | 1174 | |
0b508bc9 | 1175 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
1176 | /** |
1177 | * kthread_associate_blkcg - associate blkcg to current kthread | |
1178 | * @css: the cgroup info | |
1179 | * | |
1180 | * Current thread must be a kthread. The thread is running jobs on behalf of | |
1181 | * other threads. In some cases, we expect the jobs attach cgroup info of | |
1182 | * original threads instead of that of current thread. This function stores | |
1183 | * original thread's cgroup info in current kthread context for later | |
1184 | * retrieval. | |
1185 | */ | |
1186 | void kthread_associate_blkcg(struct cgroup_subsys_state *css) | |
1187 | { | |
1188 | struct kthread *kthread; | |
1189 | ||
1190 | if (!(current->flags & PF_KTHREAD)) | |
1191 | return; | |
1192 | kthread = to_kthread(current); | |
1193 | if (!kthread) | |
1194 | return; | |
1195 | ||
1196 | if (kthread->blkcg_css) { | |
1197 | css_put(kthread->blkcg_css); | |
1198 | kthread->blkcg_css = NULL; | |
1199 | } | |
1200 | if (css) { | |
1201 | css_get(css); | |
1202 | kthread->blkcg_css = css; | |
1203 | } | |
1204 | } | |
1205 | EXPORT_SYMBOL(kthread_associate_blkcg); | |
1206 | ||
1207 | /** | |
1208 | * kthread_blkcg - get associated blkcg css of current kthread | |
1209 | * | |
1210 | * Current thread must be a kthread. | |
1211 | */ | |
1212 | struct cgroup_subsys_state *kthread_blkcg(void) | |
1213 | { | |
1214 | struct kthread *kthread; | |
1215 | ||
1216 | if (current->flags & PF_KTHREAD) { | |
1217 | kthread = to_kthread(current); | |
1218 | if (kthread) | |
1219 | return kthread->blkcg_css; | |
1220 | } | |
1221 | return NULL; | |
1222 | } | |
1223 | EXPORT_SYMBOL(kthread_blkcg); | |
1224 | #endif |