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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* Kernel thread helper functions. |
3 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. | |
4 | * | |
73c27992 | 5 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
6 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
7 | * etc.). | |
8 | */ | |
ae7e81c0 | 9 | #include <uapi/linux/sched/types.h> |
1da177e4 | 10 | #include <linux/sched.h> |
29930025 | 11 | #include <linux/sched/task.h> |
1da177e4 LT |
12 | #include <linux/kthread.h> |
13 | #include <linux/completion.h> | |
14 | #include <linux/err.h> | |
8af0c18a | 15 | #include <linux/cgroup.h> |
58568d2a | 16 | #include <linux/cpuset.h> |
1da177e4 LT |
17 | #include <linux/unistd.h> |
18 | #include <linux/file.h> | |
9984de1a | 19 | #include <linux/export.h> |
97d1f15b | 20 | #include <linux/mutex.h> |
b56c0d89 TH |
21 | #include <linux/slab.h> |
22 | #include <linux/freezer.h> | |
a74fb73c | 23 | #include <linux/ptrace.h> |
cd42d559 | 24 | #include <linux/uaccess.h> |
98fa15f3 | 25 | #include <linux/numa.h> |
ad8d75ff | 26 | #include <trace/events/sched.h> |
1da177e4 | 27 | |
73c27992 EB |
28 | static DEFINE_SPINLOCK(kthread_create_lock); |
29 | static LIST_HEAD(kthread_create_list); | |
30 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
31 | |
32 | struct kthread_create_info | |
33 | { | |
73c27992 | 34 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
35 | int (*threadfn)(void *data); |
36 | void *data; | |
207205a2 | 37 | int node; |
1da177e4 | 38 | |
73c27992 | 39 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 40 | struct task_struct *result; |
786235ee | 41 | struct completion *done; |
65f27f38 | 42 | |
73c27992 | 43 | struct list_head list; |
1da177e4 LT |
44 | }; |
45 | ||
63706172 | 46 | struct kthread { |
2a1d4460 TG |
47 | unsigned long flags; |
48 | unsigned int cpu; | |
82805ab7 | 49 | void *data; |
2a1d4460 | 50 | struct completion parked; |
63706172 | 51 | struct completion exited; |
0b508bc9 | 52 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
53 | struct cgroup_subsys_state *blkcg_css; |
54 | #endif | |
1da177e4 LT |
55 | }; |
56 | ||
2a1d4460 TG |
57 | enum KTHREAD_BITS { |
58 | KTHREAD_IS_PER_CPU = 0, | |
59 | KTHREAD_SHOULD_STOP, | |
60 | KTHREAD_SHOULD_PARK, | |
2a1d4460 TG |
61 | }; |
62 | ||
1da5c46f ON |
63 | static inline void set_kthread_struct(void *kthread) |
64 | { | |
65 | /* | |
66 | * We abuse ->set_child_tid to avoid the new member and because it | |
67 | * can't be wrongly copied by copy_process(). We also rely on fact | |
68 | * that the caller can't exec, so PF_KTHREAD can't be cleared. | |
69 | */ | |
70 | current->set_child_tid = (__force void __user *)kthread; | |
71 | } | |
4ecdafc8 ON |
72 | |
73 | static inline struct kthread *to_kthread(struct task_struct *k) | |
74 | { | |
1da5c46f ON |
75 | WARN_ON(!(k->flags & PF_KTHREAD)); |
76 | return (__force void *)k->set_child_tid; | |
4ecdafc8 ON |
77 | } |
78 | ||
1da5c46f ON |
79 | void free_kthread_struct(struct task_struct *k) |
80 | { | |
05e3db95 SL |
81 | struct kthread *kthread; |
82 | ||
1da5c46f ON |
83 | /* |
84 | * Can be NULL if this kthread was created by kernel_thread() | |
85 | * or if kmalloc() in kthread() failed. | |
86 | */ | |
05e3db95 | 87 | kthread = to_kthread(k); |
0b508bc9 | 88 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
89 | WARN_ON_ONCE(kthread && kthread->blkcg_css); |
90 | #endif | |
91 | kfree(kthread); | |
1da5c46f ON |
92 | } |
93 | ||
9e37bd30 RD |
94 | /** |
95 | * kthread_should_stop - should this kthread return now? | |
96 | * | |
72fd4a35 | 97 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
98 | * and this will return true. You should then return, and your return |
99 | * value will be passed through to kthread_stop(). | |
100 | */ | |
2a1d4460 | 101 | bool kthread_should_stop(void) |
1da177e4 | 102 | { |
2a1d4460 | 103 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
104 | } |
105 | EXPORT_SYMBOL(kthread_should_stop); | |
106 | ||
0121805d MK |
107 | bool __kthread_should_park(struct task_struct *k) |
108 | { | |
109 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); | |
110 | } | |
111 | EXPORT_SYMBOL_GPL(__kthread_should_park); | |
112 | ||
2a1d4460 TG |
113 | /** |
114 | * kthread_should_park - should this kthread park now? | |
115 | * | |
116 | * When someone calls kthread_park() on your kthread, it will be woken | |
117 | * and this will return true. You should then do the necessary | |
118 | * cleanup and call kthread_parkme() | |
119 | * | |
120 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
121 | * and in a park position. kthread_unpark() "restarts" the thread and | |
122 | * calls the thread function again. | |
123 | */ | |
124 | bool kthread_should_park(void) | |
125 | { | |
0121805d | 126 | return __kthread_should_park(current); |
2a1d4460 | 127 | } |
18896451 | 128 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 129 | |
8a32c441 TH |
130 | /** |
131 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
132 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
133 | * | |
134 | * kthread_should_stop() for freezable kthreads, which will enter | |
135 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
136 | * freezer deadlock and freezable kthreads should use this function instead | |
137 | * of calling try_to_freeze() directly. | |
138 | */ | |
139 | bool kthread_freezable_should_stop(bool *was_frozen) | |
140 | { | |
141 | bool frozen = false; | |
142 | ||
143 | might_sleep(); | |
144 | ||
145 | if (unlikely(freezing(current))) | |
146 | frozen = __refrigerator(true); | |
147 | ||
148 | if (was_frozen) | |
149 | *was_frozen = frozen; | |
150 | ||
151 | return kthread_should_stop(); | |
152 | } | |
153 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
154 | ||
82805ab7 TH |
155 | /** |
156 | * kthread_data - return data value specified on kthread creation | |
157 | * @task: kthread task in question | |
158 | * | |
159 | * Return the data value specified when kthread @task was created. | |
160 | * The caller is responsible for ensuring the validity of @task when | |
161 | * calling this function. | |
162 | */ | |
163 | void *kthread_data(struct task_struct *task) | |
164 | { | |
165 | return to_kthread(task)->data; | |
166 | } | |
167 | ||
cd42d559 | 168 | /** |
e700591a | 169 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
170 | * @task: possible kthread task in question |
171 | * | |
172 | * @task could be a kthread task. Return the data value specified when it | |
173 | * was created if accessible. If @task isn't a kthread task or its data is | |
174 | * inaccessible for any reason, %NULL is returned. This function requires | |
175 | * that @task itself is safe to dereference. | |
176 | */ | |
e700591a | 177 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 TH |
178 | { |
179 | struct kthread *kthread = to_kthread(task); | |
180 | void *data = NULL; | |
181 | ||
182 | probe_kernel_read(&data, &kthread->data, sizeof(data)); | |
183 | return data; | |
184 | } | |
185 | ||
2a1d4460 TG |
186 | static void __kthread_parkme(struct kthread *self) |
187 | { | |
741a76b3 | 188 | for (;;) { |
1cef1150 PZ |
189 | /* |
190 | * TASK_PARKED is a special state; we must serialize against | |
191 | * possible pending wakeups to avoid store-store collisions on | |
192 | * task->state. | |
193 | * | |
194 | * Such a collision might possibly result in the task state | |
195 | * changin from TASK_PARKED and us failing the | |
196 | * wait_task_inactive() in kthread_park(). | |
197 | */ | |
198 | set_special_state(TASK_PARKED); | |
741a76b3 PZ |
199 | if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) |
200 | break; | |
1cef1150 | 201 | |
f83ee19b | 202 | complete(&self->parked); |
2a1d4460 | 203 | schedule(); |
2a1d4460 | 204 | } |
2a1d4460 TG |
205 | __set_current_state(TASK_RUNNING); |
206 | } | |
207 | ||
208 | void kthread_parkme(void) | |
209 | { | |
210 | __kthread_parkme(to_kthread(current)); | |
211 | } | |
18896451 | 212 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 213 | |
1da177e4 LT |
214 | static int kthread(void *_create) |
215 | { | |
63706172 | 216 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 217 | struct kthread_create_info *create = _create; |
63706172 ON |
218 | int (*threadfn)(void *data) = create->threadfn; |
219 | void *data = create->data; | |
786235ee | 220 | struct completion *done; |
1da5c46f | 221 | struct kthread *self; |
63706172 | 222 | int ret; |
1da177e4 | 223 | |
e10237cc | 224 | self = kzalloc(sizeof(*self), GFP_KERNEL); |
1da5c46f | 225 | set_kthread_struct(self); |
1da177e4 | 226 | |
786235ee TH |
227 | /* If user was SIGKILLed, I release the structure. */ |
228 | done = xchg(&create->done, NULL); | |
229 | if (!done) { | |
230 | kfree(create); | |
231 | do_exit(-EINTR); | |
232 | } | |
1da5c46f ON |
233 | |
234 | if (!self) { | |
235 | create->result = ERR_PTR(-ENOMEM); | |
236 | complete(done); | |
237 | do_exit(-ENOMEM); | |
238 | } | |
239 | ||
1da5c46f ON |
240 | self->data = data; |
241 | init_completion(&self->exited); | |
242 | init_completion(&self->parked); | |
243 | current->vfork_done = &self->exited; | |
244 | ||
1da177e4 | 245 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 246 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 247 | create->result = current; |
786235ee | 248 | complete(done); |
1da177e4 LT |
249 | schedule(); |
250 | ||
63706172 | 251 | ret = -EINTR; |
1da5c46f | 252 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
77f88796 | 253 | cgroup_kthread_ready(); |
1da5c46f | 254 | __kthread_parkme(self); |
2a1d4460 TG |
255 | ret = threadfn(data); |
256 | } | |
63706172 | 257 | do_exit(ret); |
1da177e4 LT |
258 | } |
259 | ||
207205a2 ED |
260 | /* called from do_fork() to get node information for about to be created task */ |
261 | int tsk_fork_get_node(struct task_struct *tsk) | |
262 | { | |
263 | #ifdef CONFIG_NUMA | |
264 | if (tsk == kthreadd_task) | |
265 | return tsk->pref_node_fork; | |
266 | #endif | |
81c98869 | 267 | return NUMA_NO_NODE; |
207205a2 ED |
268 | } |
269 | ||
73c27992 | 270 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 271 | { |
1da177e4 LT |
272 | int pid; |
273 | ||
207205a2 ED |
274 | #ifdef CONFIG_NUMA |
275 | current->pref_node_fork = create->node; | |
276 | #endif | |
1da177e4 LT |
277 | /* We want our own signal handler (we take no signals by default). */ |
278 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 279 | if (pid < 0) { |
786235ee TH |
280 | /* If user was SIGKILLed, I release the structure. */ |
281 | struct completion *done = xchg(&create->done, NULL); | |
282 | ||
283 | if (!done) { | |
284 | kfree(create); | |
285 | return; | |
286 | } | |
1da177e4 | 287 | create->result = ERR_PTR(pid); |
786235ee | 288 | complete(done); |
cdd140bd | 289 | } |
1da177e4 LT |
290 | } |
291 | ||
c0b942a7 NI |
292 | static __printf(4, 0) |
293 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
294 | void *data, int node, |
295 | const char namefmt[], | |
296 | va_list args) | |
1da177e4 | 297 | { |
786235ee TH |
298 | DECLARE_COMPLETION_ONSTACK(done); |
299 | struct task_struct *task; | |
300 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
301 | GFP_KERNEL); | |
302 | ||
303 | if (!create) | |
304 | return ERR_PTR(-ENOMEM); | |
305 | create->threadfn = threadfn; | |
306 | create->data = data; | |
307 | create->node = node; | |
308 | create->done = &done; | |
73c27992 EB |
309 | |
310 | spin_lock(&kthread_create_lock); | |
786235ee | 311 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
312 | spin_unlock(&kthread_create_lock); |
313 | ||
cbd9b67b | 314 | wake_up_process(kthreadd_task); |
786235ee TH |
315 | /* |
316 | * Wait for completion in killable state, for I might be chosen by | |
317 | * the OOM killer while kthreadd is trying to allocate memory for | |
318 | * new kernel thread. | |
319 | */ | |
320 | if (unlikely(wait_for_completion_killable(&done))) { | |
3bb8b184 TH |
321 | int i = 0; |
322 | ||
323 | /* | |
324 | * I got SIGKILL, but wait for 10 more seconds for completion | |
325 | * unless chosen by the OOM killer. This delay is there as a | |
326 | * workaround for boot failure caused by SIGKILL upon device | |
327 | * driver initialization timeout. | |
328 | */ | |
329 | while (i++ < 10 && !test_tsk_thread_flag(current, TIF_MEMDIE)) | |
330 | if (wait_for_completion_timeout(&done, HZ)) | |
331 | goto ready; | |
786235ee TH |
332 | /* |
333 | * If I was SIGKILLed before kthreadd (or new kernel thread) | |
334 | * calls complete(), leave the cleanup of this structure to | |
335 | * that thread. | |
336 | */ | |
337 | if (xchg(&create->done, NULL)) | |
8fe6929c | 338 | return ERR_PTR(-EINTR); |
786235ee TH |
339 | /* |
340 | * kthreadd (or new kernel thread) will call complete() | |
341 | * shortly. | |
342 | */ | |
343 | wait_for_completion(&done); | |
344 | } | |
3bb8b184 | 345 | ready: |
786235ee TH |
346 | task = create->result; |
347 | if (!IS_ERR(task)) { | |
c9b5f501 | 348 | static const struct sched_param param = { .sched_priority = 0 }; |
3e536e22 | 349 | char name[TASK_COMM_LEN]; |
1c99315b | 350 | |
3e536e22 SD |
351 | /* |
352 | * task is already visible to other tasks, so updating | |
353 | * COMM must be protected. | |
354 | */ | |
355 | vsnprintf(name, sizeof(name), namefmt, args); | |
356 | set_task_comm(task, name); | |
1c99315b ON |
357 | /* |
358 | * root may have changed our (kthreadd's) priority or CPU mask. | |
359 | * The kernel thread should not inherit these properties. | |
360 | */ | |
786235ee TH |
361 | sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
362 | set_cpus_allowed_ptr(task, cpu_all_mask); | |
1da177e4 | 363 | } |
786235ee TH |
364 | kfree(create); |
365 | return task; | |
1da177e4 | 366 | } |
255451e4 PM |
367 | |
368 | /** | |
369 | * kthread_create_on_node - create a kthread. | |
370 | * @threadfn: the function to run until signal_pending(current). | |
371 | * @data: data ptr for @threadfn. | |
372 | * @node: task and thread structures for the thread are allocated on this node | |
373 | * @namefmt: printf-style name for the thread. | |
374 | * | |
375 | * Description: This helper function creates and names a kernel | |
376 | * thread. The thread will be stopped: use wake_up_process() to start | |
377 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
378 | * is affine to all CPUs. | |
379 | * | |
380 | * If thread is going to be bound on a particular cpu, give its node | |
381 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
382 | * When woken, the thread will run @threadfn() with @data as its | |
383 | * argument. @threadfn() can either call do_exit() directly if it is a | |
384 | * standalone thread for which no one will call kthread_stop(), or | |
385 | * return when 'kthread_should_stop()' is true (which means | |
386 | * kthread_stop() has been called). The return value should be zero | |
387 | * or a negative error number; it will be passed to kthread_stop(). | |
388 | * | |
389 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
390 | */ | |
391 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
392 | void *data, int node, | |
393 | const char namefmt[], | |
394 | ...) | |
395 | { | |
396 | struct task_struct *task; | |
397 | va_list args; | |
398 | ||
399 | va_start(args, namefmt); | |
400 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
401 | va_end(args); | |
402 | ||
403 | return task; | |
404 | } | |
207205a2 | 405 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 406 | |
25834c73 | 407 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
2a1d4460 | 408 | { |
25834c73 PZ |
409 | unsigned long flags; |
410 | ||
f2530dc7 TG |
411 | if (!wait_task_inactive(p, state)) { |
412 | WARN_ON(1); | |
413 | return; | |
414 | } | |
25834c73 | 415 | |
2a1d4460 | 416 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
417 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
418 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 419 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
420 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
421 | } | |
422 | ||
423 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) | |
424 | { | |
425 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
426 | } | |
427 | ||
428 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
429 | { | |
430 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
431 | } |
432 | ||
881232b7 PZ |
433 | /** |
434 | * kthread_bind - bind a just-created kthread to a cpu. | |
435 | * @p: thread created by kthread_create(). | |
436 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
437 | * | |
438 | * Description: This function is equivalent to set_cpus_allowed(), | |
439 | * except that @cpu doesn't need to be online, and the thread must be | |
440 | * stopped (i.e., just returned from kthread_create()). | |
441 | */ | |
442 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
443 | { | |
f2530dc7 | 444 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
445 | } |
446 | EXPORT_SYMBOL(kthread_bind); | |
447 | ||
2a1d4460 TG |
448 | /** |
449 | * kthread_create_on_cpu - Create a cpu bound kthread | |
450 | * @threadfn: the function to run until signal_pending(current). | |
451 | * @data: data ptr for @threadfn. | |
452 | * @cpu: The cpu on which the thread should be bound, | |
453 | * @namefmt: printf-style name for the thread. Format is restricted | |
454 | * to "name.*%u". Code fills in cpu number. | |
455 | * | |
456 | * Description: This helper function creates and names a kernel thread | |
457 | * The thread will be woken and put into park mode. | |
458 | */ | |
459 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
460 | void *data, unsigned int cpu, | |
461 | const char *namefmt) | |
462 | { | |
463 | struct task_struct *p; | |
464 | ||
10922838 | 465 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
466 | cpu); |
467 | if (IS_ERR(p)) | |
468 | return p; | |
a65d4096 PM |
469 | kthread_bind(p, cpu); |
470 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 TG |
471 | set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); |
472 | to_kthread(p)->cpu = cpu; | |
2a1d4460 TG |
473 | return p; |
474 | } | |
475 | ||
cf380a4a ON |
476 | /** |
477 | * kthread_unpark - unpark a thread created by kthread_create(). | |
478 | * @k: thread created by kthread_create(). | |
479 | * | |
480 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
481 | * waits for it to return. If the thread is marked percpu then its | |
482 | * bound to the cpu again. | |
483 | */ | |
484 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 485 | { |
cf380a4a ON |
486 | struct kthread *kthread = to_kthread(k); |
487 | ||
f2530dc7 | 488 | /* |
85f1abe0 PZ |
489 | * Newly created kthread was parked when the CPU was offline. |
490 | * The binding was lost and we need to set it again. | |
f2530dc7 | 491 | */ |
85f1abe0 PZ |
492 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
493 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
494 | ||
495 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
1cef1150 PZ |
496 | /* |
497 | * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. | |
498 | */ | |
85f1abe0 | 499 | wake_up_state(k, TASK_PARKED); |
f2530dc7 | 500 | } |
18896451 | 501 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
502 | |
503 | /** | |
504 | * kthread_park - park a thread created by kthread_create(). | |
505 | * @k: thread created by kthread_create(). | |
506 | * | |
507 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
508 | * waits for it to return. This can also be called after kthread_create() | |
509 | * instead of calling wake_up_process(): the thread will park without | |
510 | * calling threadfn(). | |
511 | * | |
512 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
513 | * If called by the kthread itself just the park bit is set. | |
514 | */ | |
515 | int kthread_park(struct task_struct *k) | |
516 | { | |
cf380a4a ON |
517 | struct kthread *kthread = to_kthread(k); |
518 | ||
519 | if (WARN_ON(k->flags & PF_EXITING)) | |
520 | return -ENOSYS; | |
521 | ||
f83ee19b PZ |
522 | if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) |
523 | return -EBUSY; | |
524 | ||
85f1abe0 PZ |
525 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
526 | if (k != current) { | |
527 | wake_up_process(k); | |
1cef1150 PZ |
528 | /* |
529 | * Wait for __kthread_parkme() to complete(), this means we | |
530 | * _will_ have TASK_PARKED and are about to call schedule(). | |
531 | */ | |
85f1abe0 | 532 | wait_for_completion(&kthread->parked); |
1cef1150 PZ |
533 | /* |
534 | * Now wait for that schedule() to complete and the task to | |
535 | * get scheduled out. | |
536 | */ | |
537 | WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED)); | |
2a1d4460 | 538 | } |
cf380a4a ON |
539 | |
540 | return 0; | |
2a1d4460 | 541 | } |
18896451 | 542 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 543 | |
9e37bd30 RD |
544 | /** |
545 | * kthread_stop - stop a thread created by kthread_create(). | |
546 | * @k: thread created by kthread_create(). | |
547 | * | |
548 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
549 | * waits for it to exit. This can also be called after kthread_create() |
550 | * instead of calling wake_up_process(): the thread will exit without | |
551 | * calling threadfn(). | |
552 | * | |
553 | * If threadfn() may call do_exit() itself, the caller must ensure | |
554 | * task_struct can't go away. | |
9e37bd30 RD |
555 | * |
556 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
557 | * was never called. | |
558 | */ | |
1da177e4 LT |
559 | int kthread_stop(struct task_struct *k) |
560 | { | |
b5c5442b | 561 | struct kthread *kthread; |
1da177e4 LT |
562 | int ret; |
563 | ||
0a16b607 | 564 | trace_sched_kthread_stop(k); |
b5c5442b ON |
565 | |
566 | get_task_struct(k); | |
efb29fbf ON |
567 | kthread = to_kthread(k); |
568 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 569 | kthread_unpark(k); |
efb29fbf ON |
570 | wake_up_process(k); |
571 | wait_for_completion(&kthread->exited); | |
63706172 | 572 | ret = k->exit_code; |
1da177e4 | 573 | put_task_struct(k); |
0a16b607 | 574 | |
b5c5442b | 575 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
576 | return ret; |
577 | } | |
52e92e57 | 578 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 579 | |
e804a4a4 | 580 | int kthreadd(void *unused) |
1da177e4 | 581 | { |
73c27992 | 582 | struct task_struct *tsk = current; |
1da177e4 | 583 | |
e804a4a4 | 584 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 585 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 586 | ignore_signals(tsk); |
1a2142af | 587 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa4 | 588 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 589 | |
34b087e4 | 590 | current->flags |= PF_NOFREEZE; |
77f88796 | 591 | cgroup_init_kthreadd(); |
73c27992 EB |
592 | |
593 | for (;;) { | |
594 | set_current_state(TASK_INTERRUPTIBLE); | |
595 | if (list_empty(&kthread_create_list)) | |
596 | schedule(); | |
597 | __set_current_state(TASK_RUNNING); | |
598 | ||
599 | spin_lock(&kthread_create_lock); | |
600 | while (!list_empty(&kthread_create_list)) { | |
601 | struct kthread_create_info *create; | |
602 | ||
603 | create = list_entry(kthread_create_list.next, | |
604 | struct kthread_create_info, list); | |
605 | list_del_init(&create->list); | |
606 | spin_unlock(&kthread_create_lock); | |
607 | ||
608 | create_kthread(create); | |
609 | ||
610 | spin_lock(&kthread_create_lock); | |
611 | } | |
612 | spin_unlock(&kthread_create_lock); | |
613 | } | |
614 | ||
615 | return 0; | |
616 | } | |
b56c0d89 | 617 | |
3989144f | 618 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
619 | const char *name, |
620 | struct lock_class_key *key) | |
621 | { | |
dbf52682 | 622 | memset(worker, 0, sizeof(struct kthread_worker)); |
fe99a4f4 | 623 | raw_spin_lock_init(&worker->lock); |
4f32e9b1 YZ |
624 | lockdep_set_class_and_name(&worker->lock, key, name); |
625 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 626 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 627 | } |
3989144f | 628 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 629 | |
b56c0d89 TH |
630 | /** |
631 | * kthread_worker_fn - kthread function to process kthread_worker | |
632 | * @worker_ptr: pointer to initialized kthread_worker | |
633 | * | |
fbae2d44 PM |
634 | * This function implements the main cycle of kthread worker. It processes |
635 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
636 | * is empty. | |
b56c0d89 | 637 | * |
fbae2d44 PM |
638 | * The works are not allowed to keep any locks, disable preemption or interrupts |
639 | * when they finish. There is defined a safe point for freezing when one work | |
640 | * finishes and before a new one is started. | |
8197b3d4 PM |
641 | * |
642 | * Also the works must not be handled by more than one worker at the same time, | |
643 | * see also kthread_queue_work(). | |
b56c0d89 TH |
644 | */ |
645 | int kthread_worker_fn(void *worker_ptr) | |
646 | { | |
647 | struct kthread_worker *worker = worker_ptr; | |
648 | struct kthread_work *work; | |
649 | ||
fbae2d44 PM |
650 | /* |
651 | * FIXME: Update the check and remove the assignment when all kthread | |
652 | * worker users are created using kthread_create_worker*() functions. | |
653 | */ | |
654 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 655 | worker->task = current; |
dbf52682 PM |
656 | |
657 | if (worker->flags & KTW_FREEZABLE) | |
658 | set_freezable(); | |
659 | ||
b56c0d89 TH |
660 | repeat: |
661 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
662 | ||
663 | if (kthread_should_stop()) { | |
664 | __set_current_state(TASK_RUNNING); | |
fe99a4f4 | 665 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 | 666 | worker->task = NULL; |
fe99a4f4 | 667 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
668 | return 0; |
669 | } | |
670 | ||
671 | work = NULL; | |
fe99a4f4 | 672 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 TH |
673 | if (!list_empty(&worker->work_list)) { |
674 | work = list_first_entry(&worker->work_list, | |
675 | struct kthread_work, node); | |
676 | list_del_init(&work->node); | |
677 | } | |
46f3d976 | 678 | worker->current_work = work; |
fe99a4f4 | 679 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
680 | |
681 | if (work) { | |
682 | __set_current_state(TASK_RUNNING); | |
683 | work->func(work); | |
b56c0d89 TH |
684 | } else if (!freezing(current)) |
685 | schedule(); | |
686 | ||
687 | try_to_freeze(); | |
22cf8bc6 | 688 | cond_resched(); |
b56c0d89 TH |
689 | goto repeat; |
690 | } | |
691 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
692 | ||
c0b942a7 | 693 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
694 | __kthread_create_worker(int cpu, unsigned int flags, |
695 | const char namefmt[], va_list args) | |
fbae2d44 PM |
696 | { |
697 | struct kthread_worker *worker; | |
698 | struct task_struct *task; | |
98fa15f3 | 699 | int node = NUMA_NO_NODE; |
fbae2d44 PM |
700 | |
701 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
702 | if (!worker) | |
703 | return ERR_PTR(-ENOMEM); | |
704 | ||
705 | kthread_init_worker(worker); | |
706 | ||
8fb9dcbd ON |
707 | if (cpu >= 0) |
708 | node = cpu_to_node(cpu); | |
fbae2d44 | 709 | |
8fb9dcbd ON |
710 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
711 | node, namefmt, args); | |
fbae2d44 PM |
712 | if (IS_ERR(task)) |
713 | goto fail_task; | |
714 | ||
8fb9dcbd ON |
715 | if (cpu >= 0) |
716 | kthread_bind(task, cpu); | |
717 | ||
dbf52682 | 718 | worker->flags = flags; |
fbae2d44 PM |
719 | worker->task = task; |
720 | wake_up_process(task); | |
721 | return worker; | |
722 | ||
723 | fail_task: | |
724 | kfree(worker); | |
725 | return ERR_CAST(task); | |
726 | } | |
727 | ||
728 | /** | |
729 | * kthread_create_worker - create a kthread worker | |
dbf52682 | 730 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
731 | * @namefmt: printf-style name for the kthread worker (task). |
732 | * | |
733 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
734 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
735 | * when the worker was SIGKILLed. | |
736 | */ | |
737 | struct kthread_worker * | |
dbf52682 | 738 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
739 | { |
740 | struct kthread_worker *worker; | |
741 | va_list args; | |
742 | ||
743 | va_start(args, namefmt); | |
dbf52682 | 744 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
745 | va_end(args); |
746 | ||
747 | return worker; | |
748 | } | |
749 | EXPORT_SYMBOL(kthread_create_worker); | |
750 | ||
751 | /** | |
752 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
753 | * it to a given CPU and the associated NUMA node. | |
754 | * @cpu: CPU number | |
dbf52682 | 755 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
756 | * @namefmt: printf-style name for the kthread worker (task). |
757 | * | |
758 | * Use a valid CPU number if you want to bind the kthread worker | |
759 | * to the given CPU and the associated NUMA node. | |
760 | * | |
761 | * A good practice is to add the cpu number also into the worker name. | |
762 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
763 | * | |
764 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
765 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
766 | * when the worker was SIGKILLed. | |
767 | */ | |
768 | struct kthread_worker * | |
dbf52682 PM |
769 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
770 | const char namefmt[], ...) | |
fbae2d44 PM |
771 | { |
772 | struct kthread_worker *worker; | |
773 | va_list args; | |
774 | ||
775 | va_start(args, namefmt); | |
dbf52682 | 776 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
777 | va_end(args); |
778 | ||
779 | return worker; | |
780 | } | |
781 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
782 | ||
37be45d4 PM |
783 | /* |
784 | * Returns true when the work could not be queued at the moment. | |
785 | * It happens when it is already pending in a worker list | |
786 | * or when it is being cancelled. | |
787 | */ | |
788 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
789 | struct kthread_work *work) | |
790 | { | |
791 | lockdep_assert_held(&worker->lock); | |
792 | ||
793 | return !list_empty(&work->node) || work->canceling; | |
794 | } | |
795 | ||
8197b3d4 PM |
796 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
797 | struct kthread_work *work) | |
798 | { | |
799 | lockdep_assert_held(&worker->lock); | |
800 | WARN_ON_ONCE(!list_empty(&work->node)); | |
801 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
802 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
803 | } | |
804 | ||
9a2e03d8 | 805 | /* insert @work before @pos in @worker */ |
3989144f | 806 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
807 | struct kthread_work *work, |
808 | struct list_head *pos) | |
9a2e03d8 | 809 | { |
8197b3d4 | 810 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 TH |
811 | |
812 | list_add_tail(&work->node, pos); | |
46f3d976 | 813 | work->worker = worker; |
ed1403ec | 814 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
815 | wake_up_process(worker->task); |
816 | } | |
817 | ||
b56c0d89 | 818 | /** |
3989144f | 819 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
820 | * @worker: target kthread_worker |
821 | * @work: kthread_work to queue | |
822 | * | |
823 | * Queue @work to work processor @task for async execution. @task | |
824 | * must have been created with kthread_worker_create(). Returns %true | |
825 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
826 | * |
827 | * Reinitialize the work if it needs to be used by another worker. | |
828 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 829 | */ |
3989144f | 830 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
831 | struct kthread_work *work) |
832 | { | |
833 | bool ret = false; | |
834 | unsigned long flags; | |
835 | ||
fe99a4f4 | 836 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 | 837 | if (!queuing_blocked(worker, work)) { |
3989144f | 838 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
839 | ret = true; |
840 | } | |
fe99a4f4 | 841 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
b56c0d89 TH |
842 | return ret; |
843 | } | |
3989144f | 844 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 845 | |
22597dc3 PM |
846 | /** |
847 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
848 | * delayed work when the timer expires. | |
fe5c3b69 | 849 | * @t: pointer to the expired timer |
22597dc3 PM |
850 | * |
851 | * The format of the function is defined by struct timer_list. | |
852 | * It should have been called from irqsafe timer with irq already off. | |
853 | */ | |
fe5c3b69 | 854 | void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3 | 855 | { |
fe5c3b69 | 856 | struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3 PM |
857 | struct kthread_work *work = &dwork->work; |
858 | struct kthread_worker *worker = work->worker; | |
ad01423a | 859 | unsigned long flags; |
22597dc3 PM |
860 | |
861 | /* | |
862 | * This might happen when a pending work is reinitialized. | |
863 | * It means that it is used a wrong way. | |
864 | */ | |
865 | if (WARN_ON_ONCE(!worker)) | |
866 | return; | |
867 | ||
ad01423a | 868 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 PM |
869 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
870 | WARN_ON_ONCE(work->worker != worker); | |
871 | ||
872 | /* Move the work from worker->delayed_work_list. */ | |
873 | WARN_ON_ONCE(list_empty(&work->node)); | |
874 | list_del_init(&work->node); | |
875 | kthread_insert_work(worker, work, &worker->work_list); | |
876 | ||
ad01423a | 877 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
878 | } |
879 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
880 | ||
bc88f85c BD |
881 | static void __kthread_queue_delayed_work(struct kthread_worker *worker, |
882 | struct kthread_delayed_work *dwork, | |
883 | unsigned long delay) | |
22597dc3 PM |
884 | { |
885 | struct timer_list *timer = &dwork->timer; | |
886 | struct kthread_work *work = &dwork->work; | |
887 | ||
841b86f3 | 888 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3 PM |
889 | |
890 | /* | |
891 | * If @delay is 0, queue @dwork->work immediately. This is for | |
892 | * both optimization and correctness. The earliest @timer can | |
893 | * expire is on the closest next tick and delayed_work users depend | |
894 | * on that there's no such delay when @delay is 0. | |
895 | */ | |
896 | if (!delay) { | |
897 | kthread_insert_work(worker, work, &worker->work_list); | |
898 | return; | |
899 | } | |
900 | ||
901 | /* Be paranoid and try to detect possible races already now. */ | |
902 | kthread_insert_work_sanity_check(worker, work); | |
903 | ||
904 | list_add(&work->node, &worker->delayed_work_list); | |
905 | work->worker = worker; | |
22597dc3 PM |
906 | timer->expires = jiffies + delay; |
907 | add_timer(timer); | |
908 | } | |
909 | ||
910 | /** | |
911 | * kthread_queue_delayed_work - queue the associated kthread work | |
912 | * after a delay. | |
913 | * @worker: target kthread_worker | |
914 | * @dwork: kthread_delayed_work to queue | |
915 | * @delay: number of jiffies to wait before queuing | |
916 | * | |
917 | * If the work has not been pending it starts a timer that will queue | |
918 | * the work after the given @delay. If @delay is zero, it queues the | |
919 | * work immediately. | |
920 | * | |
921 | * Return: %false if the @work has already been pending. It means that | |
922 | * either the timer was running or the work was queued. It returns %true | |
923 | * otherwise. | |
924 | */ | |
925 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
926 | struct kthread_delayed_work *dwork, | |
927 | unsigned long delay) | |
928 | { | |
929 | struct kthread_work *work = &dwork->work; | |
930 | unsigned long flags; | |
931 | bool ret = false; | |
932 | ||
fe99a4f4 | 933 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 | 934 | |
37be45d4 | 935 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
936 | __kthread_queue_delayed_work(worker, dwork, delay); |
937 | ret = true; | |
938 | } | |
939 | ||
fe99a4f4 | 940 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
941 | return ret; |
942 | } | |
943 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
944 | ||
9a2e03d8 TH |
945 | struct kthread_flush_work { |
946 | struct kthread_work work; | |
947 | struct completion done; | |
948 | }; | |
949 | ||
950 | static void kthread_flush_work_fn(struct kthread_work *work) | |
951 | { | |
952 | struct kthread_flush_work *fwork = | |
953 | container_of(work, struct kthread_flush_work, work); | |
954 | complete(&fwork->done); | |
955 | } | |
956 | ||
b56c0d89 | 957 | /** |
3989144f | 958 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
959 | * @work: work to flush |
960 | * | |
961 | * If @work is queued or executing, wait for it to finish execution. | |
962 | */ | |
3989144f | 963 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 964 | { |
46f3d976 TH |
965 | struct kthread_flush_work fwork = { |
966 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
967 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
968 | }; | |
969 | struct kthread_worker *worker; | |
970 | bool noop = false; | |
971 | ||
46f3d976 TH |
972 | worker = work->worker; |
973 | if (!worker) | |
974 | return; | |
b56c0d89 | 975 | |
fe99a4f4 | 976 | raw_spin_lock_irq(&worker->lock); |
8197b3d4 PM |
977 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
978 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 979 | |
46f3d976 | 980 | if (!list_empty(&work->node)) |
3989144f | 981 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 982 | else if (worker->current_work == work) |
3989144f PM |
983 | kthread_insert_work(worker, &fwork.work, |
984 | worker->work_list.next); | |
46f3d976 TH |
985 | else |
986 | noop = true; | |
b56c0d89 | 987 | |
fe99a4f4 | 988 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 | 989 | |
46f3d976 TH |
990 | if (!noop) |
991 | wait_for_completion(&fwork.done); | |
b56c0d89 | 992 | } |
3989144f | 993 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 994 | |
37be45d4 PM |
995 | /* |
996 | * This function removes the work from the worker queue. Also it makes sure | |
997 | * that it won't get queued later via the delayed work's timer. | |
998 | * | |
999 | * The work might still be in use when this function finishes. See the | |
1000 | * current_work proceed by the worker. | |
1001 | * | |
1002 | * Return: %true if @work was pending and successfully canceled, | |
1003 | * %false if @work was not pending | |
1004 | */ | |
1005 | static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork, | |
1006 | unsigned long *flags) | |
1007 | { | |
1008 | /* Try to cancel the timer if exists. */ | |
1009 | if (is_dwork) { | |
1010 | struct kthread_delayed_work *dwork = | |
1011 | container_of(work, struct kthread_delayed_work, work); | |
1012 | struct kthread_worker *worker = work->worker; | |
1013 | ||
1014 | /* | |
1015 | * del_timer_sync() must be called to make sure that the timer | |
1016 | * callback is not running. The lock must be temporary released | |
1017 | * to avoid a deadlock with the callback. In the meantime, | |
1018 | * any queuing is blocked by setting the canceling counter. | |
1019 | */ | |
1020 | work->canceling++; | |
fe99a4f4 | 1021 | raw_spin_unlock_irqrestore(&worker->lock, *flags); |
37be45d4 | 1022 | del_timer_sync(&dwork->timer); |
fe99a4f4 | 1023 | raw_spin_lock_irqsave(&worker->lock, *flags); |
37be45d4 PM |
1024 | work->canceling--; |
1025 | } | |
1026 | ||
1027 | /* | |
1028 | * Try to remove the work from a worker list. It might either | |
1029 | * be from worker->work_list or from worker->delayed_work_list. | |
1030 | */ | |
1031 | if (!list_empty(&work->node)) { | |
1032 | list_del_init(&work->node); | |
1033 | return true; | |
1034 | } | |
1035 | ||
1036 | return false; | |
1037 | } | |
1038 | ||
9a6b06c8 PM |
1039 | /** |
1040 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1041 | * @worker: kthread worker to use | |
1042 | * @dwork: kthread delayed work to queue | |
1043 | * @delay: number of jiffies to wait before queuing | |
1044 | * | |
1045 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1046 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1047 | * @work is guaranteed to be queued immediately. | |
1048 | * | |
1049 | * Return: %true if @dwork was pending and its timer was modified, | |
1050 | * %false otherwise. | |
1051 | * | |
1052 | * A special case is when the work is being canceled in parallel. | |
1053 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1054 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
1055 | * win and return %false here. The caller is supposed to synchronize these | |
1056 | * operations a reasonable way. | |
1057 | * | |
1058 | * This function is safe to call from any context including IRQ handler. | |
1059 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1060 | * for details. | |
1061 | */ | |
1062 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1063 | struct kthread_delayed_work *dwork, | |
1064 | unsigned long delay) | |
1065 | { | |
1066 | struct kthread_work *work = &dwork->work; | |
1067 | unsigned long flags; | |
1068 | int ret = false; | |
1069 | ||
fe99a4f4 | 1070 | raw_spin_lock_irqsave(&worker->lock, flags); |
9a6b06c8 PM |
1071 | |
1072 | /* Do not bother with canceling when never queued. */ | |
1073 | if (!work->worker) | |
1074 | goto fast_queue; | |
1075 | ||
1076 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1077 | WARN_ON_ONCE(work->worker != worker); | |
1078 | ||
1079 | /* Do not fight with another command that is canceling this work. */ | |
1080 | if (work->canceling) | |
1081 | goto out; | |
1082 | ||
1083 | ret = __kthread_cancel_work(work, true, &flags); | |
1084 | fast_queue: | |
1085 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1086 | out: | |
fe99a4f4 | 1087 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
9a6b06c8 PM |
1088 | return ret; |
1089 | } | |
1090 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1091 | ||
37be45d4 PM |
1092 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1093 | { | |
1094 | struct kthread_worker *worker = work->worker; | |
1095 | unsigned long flags; | |
1096 | int ret = false; | |
1097 | ||
1098 | if (!worker) | |
1099 | goto out; | |
1100 | ||
fe99a4f4 | 1101 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1102 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1103 | WARN_ON_ONCE(work->worker != worker); | |
1104 | ||
1105 | ret = __kthread_cancel_work(work, is_dwork, &flags); | |
1106 | ||
1107 | if (worker->current_work != work) | |
1108 | goto out_fast; | |
1109 | ||
1110 | /* | |
1111 | * The work is in progress and we need to wait with the lock released. | |
1112 | * In the meantime, block any queuing by setting the canceling counter. | |
1113 | */ | |
1114 | work->canceling++; | |
fe99a4f4 | 1115 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 | 1116 | kthread_flush_work(work); |
fe99a4f4 | 1117 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1118 | work->canceling--; |
1119 | ||
1120 | out_fast: | |
fe99a4f4 | 1121 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 PM |
1122 | out: |
1123 | return ret; | |
1124 | } | |
1125 | ||
1126 | /** | |
1127 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1128 | * @work: the kthread work to cancel | |
1129 | * | |
1130 | * Cancel @work and wait for its execution to finish. This function | |
1131 | * can be used even if the work re-queues itself. On return from this | |
1132 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1133 | * | |
1134 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1135 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1136 | * | |
1137 | * The caller must ensure that the worker on which @work was last | |
1138 | * queued can't be destroyed before this function returns. | |
1139 | * | |
1140 | * Return: %true if @work was pending, %false otherwise. | |
1141 | */ | |
1142 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1143 | { | |
1144 | return __kthread_cancel_work_sync(work, false); | |
1145 | } | |
1146 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1147 | ||
1148 | /** | |
1149 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1150 | * wait for it to finish. | |
1151 | * @dwork: the kthread delayed work to cancel | |
1152 | * | |
1153 | * This is kthread_cancel_work_sync() for delayed works. | |
1154 | * | |
1155 | * Return: %true if @dwork was pending, %false otherwise. | |
1156 | */ | |
1157 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1158 | { | |
1159 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1160 | } | |
1161 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1162 | ||
b56c0d89 | 1163 | /** |
3989144f | 1164 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1165 | * @worker: worker to flush |
1166 | * | |
1167 | * Wait until all currently executing or pending works on @worker are | |
1168 | * finished. | |
1169 | */ | |
3989144f | 1170 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1171 | { |
1172 | struct kthread_flush_work fwork = { | |
1173 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1174 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1175 | }; | |
1176 | ||
3989144f | 1177 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1178 | wait_for_completion(&fwork.done); |
1179 | } | |
3989144f | 1180 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1181 | |
1182 | /** | |
1183 | * kthread_destroy_worker - destroy a kthread worker | |
1184 | * @worker: worker to be destroyed | |
1185 | * | |
1186 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1187 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1188 | * machines needed. | |
1189 | */ | |
1190 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1191 | { | |
1192 | struct task_struct *task; | |
1193 | ||
1194 | task = worker->task; | |
1195 | if (WARN_ON(!task)) | |
1196 | return; | |
1197 | ||
1198 | kthread_flush_worker(worker); | |
1199 | kthread_stop(task); | |
1200 | WARN_ON(!list_empty(&worker->work_list)); | |
1201 | kfree(worker); | |
1202 | } | |
1203 | EXPORT_SYMBOL(kthread_destroy_worker); | |
05e3db95 | 1204 | |
0b508bc9 | 1205 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
1206 | /** |
1207 | * kthread_associate_blkcg - associate blkcg to current kthread | |
1208 | * @css: the cgroup info | |
1209 | * | |
1210 | * Current thread must be a kthread. The thread is running jobs on behalf of | |
1211 | * other threads. In some cases, we expect the jobs attach cgroup info of | |
1212 | * original threads instead of that of current thread. This function stores | |
1213 | * original thread's cgroup info in current kthread context for later | |
1214 | * retrieval. | |
1215 | */ | |
1216 | void kthread_associate_blkcg(struct cgroup_subsys_state *css) | |
1217 | { | |
1218 | struct kthread *kthread; | |
1219 | ||
1220 | if (!(current->flags & PF_KTHREAD)) | |
1221 | return; | |
1222 | kthread = to_kthread(current); | |
1223 | if (!kthread) | |
1224 | return; | |
1225 | ||
1226 | if (kthread->blkcg_css) { | |
1227 | css_put(kthread->blkcg_css); | |
1228 | kthread->blkcg_css = NULL; | |
1229 | } | |
1230 | if (css) { | |
1231 | css_get(css); | |
1232 | kthread->blkcg_css = css; | |
1233 | } | |
1234 | } | |
1235 | EXPORT_SYMBOL(kthread_associate_blkcg); | |
1236 | ||
1237 | /** | |
1238 | * kthread_blkcg - get associated blkcg css of current kthread | |
1239 | * | |
1240 | * Current thread must be a kthread. | |
1241 | */ | |
1242 | struct cgroup_subsys_state *kthread_blkcg(void) | |
1243 | { | |
1244 | struct kthread *kthread; | |
1245 | ||
1246 | if (current->flags & PF_KTHREAD) { | |
1247 | kthread = to_kthread(current); | |
1248 | if (kthread) | |
1249 | return kthread->blkcg_css; | |
1250 | } | |
1251 | return NULL; | |
1252 | } | |
1253 | EXPORT_SYMBOL(kthread_blkcg); | |
1254 | #endif |