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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 | ||
b9bd0679 PZ |
79 | /* |
80 | * Variant of to_kthread() that doesn't assume @p is a kthread. | |
81 | * | |
82 | * Per construction; when: | |
83 | * | |
84 | * (p->flags & PF_KTHREAD) && p->set_child_tid | |
85 | * | |
86 | * the task is both a kthread and struct kthread is persistent. However | |
87 | * PF_KTHREAD on it's own is not, kernel_thread() can exec() (See umh.c and | |
88 | * begin_new_exec()). | |
89 | */ | |
90 | static inline struct kthread *__to_kthread(struct task_struct *p) | |
91 | { | |
92 | void *kthread = (__force void *)p->set_child_tid; | |
93 | if (kthread && !(p->flags & PF_KTHREAD)) | |
94 | kthread = NULL; | |
95 | return kthread; | |
96 | } | |
97 | ||
1da5c46f ON |
98 | void free_kthread_struct(struct task_struct *k) |
99 | { | |
05e3db95 SL |
100 | struct kthread *kthread; |
101 | ||
1da5c46f ON |
102 | /* |
103 | * Can be NULL if this kthread was created by kernel_thread() | |
104 | * or if kmalloc() in kthread() failed. | |
105 | */ | |
05e3db95 | 106 | kthread = to_kthread(k); |
0b508bc9 | 107 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
108 | WARN_ON_ONCE(kthread && kthread->blkcg_css); |
109 | #endif | |
110 | kfree(kthread); | |
1da5c46f ON |
111 | } |
112 | ||
9e37bd30 RD |
113 | /** |
114 | * kthread_should_stop - should this kthread return now? | |
115 | * | |
72fd4a35 | 116 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
117 | * and this will return true. You should then return, and your return |
118 | * value will be passed through to kthread_stop(). | |
119 | */ | |
2a1d4460 | 120 | bool kthread_should_stop(void) |
1da177e4 | 121 | { |
2a1d4460 | 122 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
123 | } |
124 | EXPORT_SYMBOL(kthread_should_stop); | |
125 | ||
0121805d MK |
126 | bool __kthread_should_park(struct task_struct *k) |
127 | { | |
128 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); | |
129 | } | |
130 | EXPORT_SYMBOL_GPL(__kthread_should_park); | |
131 | ||
2a1d4460 TG |
132 | /** |
133 | * kthread_should_park - should this kthread park now? | |
134 | * | |
135 | * When someone calls kthread_park() on your kthread, it will be woken | |
136 | * and this will return true. You should then do the necessary | |
137 | * cleanup and call kthread_parkme() | |
138 | * | |
139 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
140 | * and in a park position. kthread_unpark() "restarts" the thread and | |
141 | * calls the thread function again. | |
142 | */ | |
143 | bool kthread_should_park(void) | |
144 | { | |
0121805d | 145 | return __kthread_should_park(current); |
2a1d4460 | 146 | } |
18896451 | 147 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 148 | |
8a32c441 TH |
149 | /** |
150 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
151 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
152 | * | |
153 | * kthread_should_stop() for freezable kthreads, which will enter | |
154 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
155 | * freezer deadlock and freezable kthreads should use this function instead | |
156 | * of calling try_to_freeze() directly. | |
157 | */ | |
158 | bool kthread_freezable_should_stop(bool *was_frozen) | |
159 | { | |
160 | bool frozen = false; | |
161 | ||
162 | might_sleep(); | |
163 | ||
164 | if (unlikely(freezing(current))) | |
165 | frozen = __refrigerator(true); | |
166 | ||
167 | if (was_frozen) | |
168 | *was_frozen = frozen; | |
169 | ||
170 | return kthread_should_stop(); | |
171 | } | |
172 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
173 | ||
82805ab7 TH |
174 | /** |
175 | * kthread_data - return data value specified on kthread creation | |
176 | * @task: kthread task in question | |
177 | * | |
178 | * Return the data value specified when kthread @task was created. | |
179 | * The caller is responsible for ensuring the validity of @task when | |
180 | * calling this function. | |
181 | */ | |
182 | void *kthread_data(struct task_struct *task) | |
183 | { | |
184 | return to_kthread(task)->data; | |
185 | } | |
186 | ||
cd42d559 | 187 | /** |
e700591a | 188 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
189 | * @task: possible kthread task in question |
190 | * | |
191 | * @task could be a kthread task. Return the data value specified when it | |
192 | * was created if accessible. If @task isn't a kthread task or its data is | |
193 | * inaccessible for any reason, %NULL is returned. This function requires | |
194 | * that @task itself is safe to dereference. | |
195 | */ | |
e700591a | 196 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 | 197 | { |
b9bd0679 | 198 | struct kthread *kthread = __to_kthread(task); |
cd42d559 TH |
199 | void *data = NULL; |
200 | ||
b9bd0679 PZ |
201 | if (kthread) |
202 | probe_kernel_read(&data, &kthread->data, sizeof(data)); | |
cd42d559 TH |
203 | return data; |
204 | } | |
205 | ||
2a1d4460 TG |
206 | static void __kthread_parkme(struct kthread *self) |
207 | { | |
741a76b3 | 208 | for (;;) { |
1cef1150 PZ |
209 | /* |
210 | * TASK_PARKED is a special state; we must serialize against | |
211 | * possible pending wakeups to avoid store-store collisions on | |
212 | * task->state. | |
213 | * | |
214 | * Such a collision might possibly result in the task state | |
215 | * changin from TASK_PARKED and us failing the | |
216 | * wait_task_inactive() in kthread_park(). | |
217 | */ | |
218 | set_special_state(TASK_PARKED); | |
741a76b3 PZ |
219 | if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) |
220 | break; | |
1cef1150 | 221 | |
a8e777fd LC |
222 | /* |
223 | * Thread is going to call schedule(), do not preempt it, | |
224 | * or the caller of kthread_park() may spend more time in | |
225 | * wait_task_inactive(). | |
226 | */ | |
227 | preempt_disable(); | |
f83ee19b | 228 | complete(&self->parked); |
a8e777fd LC |
229 | schedule_preempt_disabled(); |
230 | preempt_enable(); | |
2a1d4460 | 231 | } |
2a1d4460 TG |
232 | __set_current_state(TASK_RUNNING); |
233 | } | |
234 | ||
235 | void kthread_parkme(void) | |
236 | { | |
237 | __kthread_parkme(to_kthread(current)); | |
238 | } | |
18896451 | 239 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 240 | |
1da177e4 LT |
241 | static int kthread(void *_create) |
242 | { | |
63706172 | 243 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 244 | struct kthread_create_info *create = _create; |
63706172 ON |
245 | int (*threadfn)(void *data) = create->threadfn; |
246 | void *data = create->data; | |
786235ee | 247 | struct completion *done; |
1da5c46f | 248 | struct kthread *self; |
63706172 | 249 | int ret; |
1da177e4 | 250 | |
e10237cc | 251 | self = kzalloc(sizeof(*self), GFP_KERNEL); |
1da5c46f | 252 | set_kthread_struct(self); |
1da177e4 | 253 | |
786235ee TH |
254 | /* If user was SIGKILLed, I release the structure. */ |
255 | done = xchg(&create->done, NULL); | |
256 | if (!done) { | |
257 | kfree(create); | |
258 | do_exit(-EINTR); | |
259 | } | |
1da5c46f ON |
260 | |
261 | if (!self) { | |
262 | create->result = ERR_PTR(-ENOMEM); | |
263 | complete(done); | |
264 | do_exit(-ENOMEM); | |
265 | } | |
266 | ||
1da5c46f ON |
267 | self->data = data; |
268 | init_completion(&self->exited); | |
269 | init_completion(&self->parked); | |
270 | current->vfork_done = &self->exited; | |
271 | ||
1da177e4 | 272 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 273 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 274 | create->result = current; |
a8e777fd LC |
275 | /* |
276 | * Thread is going to call schedule(), do not preempt it, | |
277 | * or the creator may spend more time in wait_task_inactive(). | |
278 | */ | |
279 | preempt_disable(); | |
786235ee | 280 | complete(done); |
a8e777fd LC |
281 | schedule_preempt_disabled(); |
282 | preempt_enable(); | |
1da177e4 | 283 | |
63706172 | 284 | ret = -EINTR; |
1da5c46f | 285 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
77f88796 | 286 | cgroup_kthread_ready(); |
1da5c46f | 287 | __kthread_parkme(self); |
2a1d4460 TG |
288 | ret = threadfn(data); |
289 | } | |
63706172 | 290 | do_exit(ret); |
1da177e4 LT |
291 | } |
292 | ||
207205a2 ED |
293 | /* called from do_fork() to get node information for about to be created task */ |
294 | int tsk_fork_get_node(struct task_struct *tsk) | |
295 | { | |
296 | #ifdef CONFIG_NUMA | |
297 | if (tsk == kthreadd_task) | |
298 | return tsk->pref_node_fork; | |
299 | #endif | |
81c98869 | 300 | return NUMA_NO_NODE; |
207205a2 ED |
301 | } |
302 | ||
73c27992 | 303 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 304 | { |
1da177e4 LT |
305 | int pid; |
306 | ||
207205a2 ED |
307 | #ifdef CONFIG_NUMA |
308 | current->pref_node_fork = create->node; | |
309 | #endif | |
1da177e4 LT |
310 | /* We want our own signal handler (we take no signals by default). */ |
311 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 312 | if (pid < 0) { |
786235ee TH |
313 | /* If user was SIGKILLed, I release the structure. */ |
314 | struct completion *done = xchg(&create->done, NULL); | |
315 | ||
316 | if (!done) { | |
317 | kfree(create); | |
318 | return; | |
319 | } | |
1da177e4 | 320 | create->result = ERR_PTR(pid); |
786235ee | 321 | complete(done); |
cdd140bd | 322 | } |
1da177e4 LT |
323 | } |
324 | ||
c0b942a7 NI |
325 | static __printf(4, 0) |
326 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
327 | void *data, int node, |
328 | const char namefmt[], | |
329 | va_list args) | |
1da177e4 | 330 | { |
786235ee TH |
331 | DECLARE_COMPLETION_ONSTACK(done); |
332 | struct task_struct *task; | |
333 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
334 | GFP_KERNEL); | |
335 | ||
336 | if (!create) | |
337 | return ERR_PTR(-ENOMEM); | |
338 | create->threadfn = threadfn; | |
339 | create->data = data; | |
340 | create->node = node; | |
341 | create->done = &done; | |
73c27992 EB |
342 | |
343 | spin_lock(&kthread_create_lock); | |
786235ee | 344 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
345 | spin_unlock(&kthread_create_lock); |
346 | ||
cbd9b67b | 347 | wake_up_process(kthreadd_task); |
786235ee TH |
348 | /* |
349 | * Wait for completion in killable state, for I might be chosen by | |
350 | * the OOM killer while kthreadd is trying to allocate memory for | |
351 | * new kernel thread. | |
352 | */ | |
353 | if (unlikely(wait_for_completion_killable(&done))) { | |
3bb8b184 TH |
354 | int i = 0; |
355 | ||
356 | /* | |
357 | * I got SIGKILL, but wait for 10 more seconds for completion | |
358 | * unless chosen by the OOM killer. This delay is there as a | |
359 | * workaround for boot failure caused by SIGKILL upon device | |
360 | * driver initialization timeout. | |
361 | */ | |
362 | while (i++ < 10 && !test_tsk_thread_flag(current, TIF_MEMDIE)) | |
363 | if (wait_for_completion_timeout(&done, HZ)) | |
364 | goto ready; | |
786235ee TH |
365 | /* |
366 | * If I was SIGKILLed before kthreadd (or new kernel thread) | |
367 | * calls complete(), leave the cleanup of this structure to | |
368 | * that thread. | |
369 | */ | |
370 | if (xchg(&create->done, NULL)) | |
8fe6929c | 371 | return ERR_PTR(-EINTR); |
786235ee TH |
372 | /* |
373 | * kthreadd (or new kernel thread) will call complete() | |
374 | * shortly. | |
375 | */ | |
376 | wait_for_completion(&done); | |
377 | } | |
3bb8b184 | 378 | ready: |
786235ee TH |
379 | task = create->result; |
380 | if (!IS_ERR(task)) { | |
c9b5f501 | 381 | static const struct sched_param param = { .sched_priority = 0 }; |
3e536e22 | 382 | char name[TASK_COMM_LEN]; |
1c99315b | 383 | |
3e536e22 SD |
384 | /* |
385 | * task is already visible to other tasks, so updating | |
386 | * COMM must be protected. | |
387 | */ | |
388 | vsnprintf(name, sizeof(name), namefmt, args); | |
389 | set_task_comm(task, name); | |
1c99315b ON |
390 | /* |
391 | * root may have changed our (kthreadd's) priority or CPU mask. | |
392 | * The kernel thread should not inherit these properties. | |
393 | */ | |
786235ee TH |
394 | sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
395 | set_cpus_allowed_ptr(task, cpu_all_mask); | |
1da177e4 | 396 | } |
786235ee TH |
397 | kfree(create); |
398 | return task; | |
1da177e4 | 399 | } |
255451e4 PM |
400 | |
401 | /** | |
402 | * kthread_create_on_node - create a kthread. | |
403 | * @threadfn: the function to run until signal_pending(current). | |
404 | * @data: data ptr for @threadfn. | |
405 | * @node: task and thread structures for the thread are allocated on this node | |
406 | * @namefmt: printf-style name for the thread. | |
407 | * | |
408 | * Description: This helper function creates and names a kernel | |
409 | * thread. The thread will be stopped: use wake_up_process() to start | |
410 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
411 | * is affine to all CPUs. | |
412 | * | |
413 | * If thread is going to be bound on a particular cpu, give its node | |
414 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
415 | * When woken, the thread will run @threadfn() with @data as its | |
416 | * argument. @threadfn() can either call do_exit() directly if it is a | |
417 | * standalone thread for which no one will call kthread_stop(), or | |
418 | * return when 'kthread_should_stop()' is true (which means | |
419 | * kthread_stop() has been called). The return value should be zero | |
420 | * or a negative error number; it will be passed to kthread_stop(). | |
421 | * | |
422 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
423 | */ | |
424 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
425 | void *data, int node, | |
426 | const char namefmt[], | |
427 | ...) | |
428 | { | |
429 | struct task_struct *task; | |
430 | va_list args; | |
431 | ||
432 | va_start(args, namefmt); | |
433 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
434 | va_end(args); | |
435 | ||
436 | return task; | |
437 | } | |
207205a2 | 438 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 439 | |
25834c73 | 440 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
2a1d4460 | 441 | { |
25834c73 PZ |
442 | unsigned long flags; |
443 | ||
f2530dc7 TG |
444 | if (!wait_task_inactive(p, state)) { |
445 | WARN_ON(1); | |
446 | return; | |
447 | } | |
25834c73 | 448 | |
2a1d4460 | 449 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
450 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
451 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 452 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
453 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
454 | } | |
455 | ||
456 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) | |
457 | { | |
458 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
459 | } | |
460 | ||
461 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
462 | { | |
463 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
464 | } |
465 | ||
881232b7 PZ |
466 | /** |
467 | * kthread_bind - bind a just-created kthread to a cpu. | |
468 | * @p: thread created by kthread_create(). | |
469 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
470 | * | |
471 | * Description: This function is equivalent to set_cpus_allowed(), | |
472 | * except that @cpu doesn't need to be online, and the thread must be | |
473 | * stopped (i.e., just returned from kthread_create()). | |
474 | */ | |
475 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
476 | { | |
f2530dc7 | 477 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
478 | } |
479 | EXPORT_SYMBOL(kthread_bind); | |
480 | ||
2a1d4460 TG |
481 | /** |
482 | * kthread_create_on_cpu - Create a cpu bound kthread | |
483 | * @threadfn: the function to run until signal_pending(current). | |
484 | * @data: data ptr for @threadfn. | |
485 | * @cpu: The cpu on which the thread should be bound, | |
486 | * @namefmt: printf-style name for the thread. Format is restricted | |
487 | * to "name.*%u". Code fills in cpu number. | |
488 | * | |
489 | * Description: This helper function creates and names a kernel thread | |
490 | * The thread will be woken and put into park mode. | |
491 | */ | |
492 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
493 | void *data, unsigned int cpu, | |
494 | const char *namefmt) | |
495 | { | |
496 | struct task_struct *p; | |
497 | ||
10922838 | 498 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
499 | cpu); |
500 | if (IS_ERR(p)) | |
501 | return p; | |
a65d4096 PM |
502 | kthread_bind(p, cpu); |
503 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 | 504 | to_kthread(p)->cpu = cpu; |
2a1d4460 TG |
505 | return p; |
506 | } | |
507 | ||
2379c7b6 PZ |
508 | void kthread_set_per_cpu(struct task_struct *k, int cpu) |
509 | { | |
510 | struct kthread *kthread = to_kthread(k); | |
511 | if (!kthread) | |
512 | return; | |
513 | ||
514 | WARN_ON_ONCE(!(k->flags & PF_NO_SETAFFINITY)); | |
515 | ||
516 | if (cpu < 0) { | |
517 | clear_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
518 | return; | |
519 | } | |
520 | ||
521 | kthread->cpu = cpu; | |
522 | set_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
523 | } | |
524 | ||
b9bd0679 | 525 | bool kthread_is_per_cpu(struct task_struct *p) |
2379c7b6 | 526 | { |
b9bd0679 | 527 | struct kthread *kthread = __to_kthread(p); |
2379c7b6 PZ |
528 | if (!kthread) |
529 | return false; | |
530 | ||
531 | return test_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
532 | } | |
533 | ||
cf380a4a ON |
534 | /** |
535 | * kthread_unpark - unpark a thread created by kthread_create(). | |
536 | * @k: thread created by kthread_create(). | |
537 | * | |
538 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
539 | * waits for it to return. If the thread is marked percpu then its | |
540 | * bound to the cpu again. | |
541 | */ | |
542 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 543 | { |
cf380a4a ON |
544 | struct kthread *kthread = to_kthread(k); |
545 | ||
f2530dc7 | 546 | /* |
85f1abe0 PZ |
547 | * Newly created kthread was parked when the CPU was offline. |
548 | * The binding was lost and we need to set it again. | |
f2530dc7 | 549 | */ |
85f1abe0 PZ |
550 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
551 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
552 | ||
553 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
1cef1150 PZ |
554 | /* |
555 | * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. | |
556 | */ | |
85f1abe0 | 557 | wake_up_state(k, TASK_PARKED); |
f2530dc7 | 558 | } |
18896451 | 559 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
560 | |
561 | /** | |
562 | * kthread_park - park a thread created by kthread_create(). | |
563 | * @k: thread created by kthread_create(). | |
564 | * | |
565 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
566 | * waits for it to return. This can also be called after kthread_create() | |
567 | * instead of calling wake_up_process(): the thread will park without | |
568 | * calling threadfn(). | |
569 | * | |
570 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
571 | * If called by the kthread itself just the park bit is set. | |
572 | */ | |
573 | int kthread_park(struct task_struct *k) | |
574 | { | |
cf380a4a ON |
575 | struct kthread *kthread = to_kthread(k); |
576 | ||
577 | if (WARN_ON(k->flags & PF_EXITING)) | |
578 | return -ENOSYS; | |
579 | ||
f83ee19b PZ |
580 | if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) |
581 | return -EBUSY; | |
582 | ||
85f1abe0 PZ |
583 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
584 | if (k != current) { | |
585 | wake_up_process(k); | |
1cef1150 PZ |
586 | /* |
587 | * Wait for __kthread_parkme() to complete(), this means we | |
588 | * _will_ have TASK_PARKED and are about to call schedule(). | |
589 | */ | |
85f1abe0 | 590 | wait_for_completion(&kthread->parked); |
1cef1150 PZ |
591 | /* |
592 | * Now wait for that schedule() to complete and the task to | |
593 | * get scheduled out. | |
594 | */ | |
595 | WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED)); | |
2a1d4460 | 596 | } |
cf380a4a ON |
597 | |
598 | return 0; | |
2a1d4460 | 599 | } |
18896451 | 600 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 601 | |
9e37bd30 RD |
602 | /** |
603 | * kthread_stop - stop a thread created by kthread_create(). | |
604 | * @k: thread created by kthread_create(). | |
605 | * | |
606 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
607 | * waits for it to exit. This can also be called after kthread_create() |
608 | * instead of calling wake_up_process(): the thread will exit without | |
609 | * calling threadfn(). | |
610 | * | |
611 | * If threadfn() may call do_exit() itself, the caller must ensure | |
612 | * task_struct can't go away. | |
9e37bd30 RD |
613 | * |
614 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
615 | * was never called. | |
616 | */ | |
1da177e4 LT |
617 | int kthread_stop(struct task_struct *k) |
618 | { | |
b5c5442b | 619 | struct kthread *kthread; |
1da177e4 LT |
620 | int ret; |
621 | ||
0a16b607 | 622 | trace_sched_kthread_stop(k); |
b5c5442b ON |
623 | |
624 | get_task_struct(k); | |
efb29fbf ON |
625 | kthread = to_kthread(k); |
626 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 627 | kthread_unpark(k); |
efb29fbf ON |
628 | wake_up_process(k); |
629 | wait_for_completion(&kthread->exited); | |
63706172 | 630 | ret = k->exit_code; |
1da177e4 | 631 | put_task_struct(k); |
0a16b607 | 632 | |
b5c5442b | 633 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
634 | return ret; |
635 | } | |
52e92e57 | 636 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 637 | |
e804a4a4 | 638 | int kthreadd(void *unused) |
1da177e4 | 639 | { |
73c27992 | 640 | struct task_struct *tsk = current; |
1da177e4 | 641 | |
e804a4a4 | 642 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 643 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 644 | ignore_signals(tsk); |
1a2142af | 645 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa4 | 646 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 647 | |
34b087e4 | 648 | current->flags |= PF_NOFREEZE; |
77f88796 | 649 | cgroup_init_kthreadd(); |
73c27992 EB |
650 | |
651 | for (;;) { | |
652 | set_current_state(TASK_INTERRUPTIBLE); | |
653 | if (list_empty(&kthread_create_list)) | |
654 | schedule(); | |
655 | __set_current_state(TASK_RUNNING); | |
656 | ||
657 | spin_lock(&kthread_create_lock); | |
658 | while (!list_empty(&kthread_create_list)) { | |
659 | struct kthread_create_info *create; | |
660 | ||
661 | create = list_entry(kthread_create_list.next, | |
662 | struct kthread_create_info, list); | |
663 | list_del_init(&create->list); | |
664 | spin_unlock(&kthread_create_lock); | |
665 | ||
666 | create_kthread(create); | |
667 | ||
668 | spin_lock(&kthread_create_lock); | |
669 | } | |
670 | spin_unlock(&kthread_create_lock); | |
671 | } | |
672 | ||
673 | return 0; | |
674 | } | |
b56c0d89 | 675 | |
3989144f | 676 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
677 | const char *name, |
678 | struct lock_class_key *key) | |
679 | { | |
dbf52682 | 680 | memset(worker, 0, sizeof(struct kthread_worker)); |
fe99a4f4 | 681 | raw_spin_lock_init(&worker->lock); |
4f32e9b1 YZ |
682 | lockdep_set_class_and_name(&worker->lock, key, name); |
683 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 684 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 685 | } |
3989144f | 686 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 687 | |
b56c0d89 TH |
688 | /** |
689 | * kthread_worker_fn - kthread function to process kthread_worker | |
690 | * @worker_ptr: pointer to initialized kthread_worker | |
691 | * | |
fbae2d44 PM |
692 | * This function implements the main cycle of kthread worker. It processes |
693 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
694 | * is empty. | |
b56c0d89 | 695 | * |
fbae2d44 PM |
696 | * The works are not allowed to keep any locks, disable preemption or interrupts |
697 | * when they finish. There is defined a safe point for freezing when one work | |
698 | * finishes and before a new one is started. | |
8197b3d4 PM |
699 | * |
700 | * Also the works must not be handled by more than one worker at the same time, | |
701 | * see also kthread_queue_work(). | |
b56c0d89 TH |
702 | */ |
703 | int kthread_worker_fn(void *worker_ptr) | |
704 | { | |
705 | struct kthread_worker *worker = worker_ptr; | |
706 | struct kthread_work *work; | |
707 | ||
fbae2d44 PM |
708 | /* |
709 | * FIXME: Update the check and remove the assignment when all kthread | |
710 | * worker users are created using kthread_create_worker*() functions. | |
711 | */ | |
712 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 713 | worker->task = current; |
dbf52682 PM |
714 | |
715 | if (worker->flags & KTW_FREEZABLE) | |
716 | set_freezable(); | |
717 | ||
b56c0d89 TH |
718 | repeat: |
719 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
720 | ||
721 | if (kthread_should_stop()) { | |
722 | __set_current_state(TASK_RUNNING); | |
fe99a4f4 | 723 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 | 724 | worker->task = NULL; |
fe99a4f4 | 725 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
726 | return 0; |
727 | } | |
728 | ||
729 | work = NULL; | |
fe99a4f4 | 730 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 TH |
731 | if (!list_empty(&worker->work_list)) { |
732 | work = list_first_entry(&worker->work_list, | |
733 | struct kthread_work, node); | |
734 | list_del_init(&work->node); | |
735 | } | |
46f3d976 | 736 | worker->current_work = work; |
fe99a4f4 | 737 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
738 | |
739 | if (work) { | |
740 | __set_current_state(TASK_RUNNING); | |
741 | work->func(work); | |
b56c0d89 TH |
742 | } else if (!freezing(current)) |
743 | schedule(); | |
744 | ||
745 | try_to_freeze(); | |
22cf8bc6 | 746 | cond_resched(); |
b56c0d89 TH |
747 | goto repeat; |
748 | } | |
749 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
750 | ||
c0b942a7 | 751 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
752 | __kthread_create_worker(int cpu, unsigned int flags, |
753 | const char namefmt[], va_list args) | |
fbae2d44 PM |
754 | { |
755 | struct kthread_worker *worker; | |
756 | struct task_struct *task; | |
98fa15f3 | 757 | int node = NUMA_NO_NODE; |
fbae2d44 PM |
758 | |
759 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
760 | if (!worker) | |
761 | return ERR_PTR(-ENOMEM); | |
762 | ||
763 | kthread_init_worker(worker); | |
764 | ||
8fb9dcbd ON |
765 | if (cpu >= 0) |
766 | node = cpu_to_node(cpu); | |
fbae2d44 | 767 | |
8fb9dcbd ON |
768 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
769 | node, namefmt, args); | |
fbae2d44 PM |
770 | if (IS_ERR(task)) |
771 | goto fail_task; | |
772 | ||
8fb9dcbd ON |
773 | if (cpu >= 0) |
774 | kthread_bind(task, cpu); | |
775 | ||
dbf52682 | 776 | worker->flags = flags; |
fbae2d44 PM |
777 | worker->task = task; |
778 | wake_up_process(task); | |
779 | return worker; | |
780 | ||
781 | fail_task: | |
782 | kfree(worker); | |
783 | return ERR_CAST(task); | |
784 | } | |
785 | ||
786 | /** | |
787 | * kthread_create_worker - create a kthread worker | |
dbf52682 | 788 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
789 | * @namefmt: printf-style name for the kthread worker (task). |
790 | * | |
791 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
792 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
793 | * when the worker was SIGKILLed. | |
794 | */ | |
795 | struct kthread_worker * | |
dbf52682 | 796 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
797 | { |
798 | struct kthread_worker *worker; | |
799 | va_list args; | |
800 | ||
801 | va_start(args, namefmt); | |
dbf52682 | 802 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
803 | va_end(args); |
804 | ||
805 | return worker; | |
806 | } | |
807 | EXPORT_SYMBOL(kthread_create_worker); | |
808 | ||
809 | /** | |
810 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
811 | * it to a given CPU and the associated NUMA node. | |
812 | * @cpu: CPU number | |
dbf52682 | 813 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
814 | * @namefmt: printf-style name for the kthread worker (task). |
815 | * | |
816 | * Use a valid CPU number if you want to bind the kthread worker | |
817 | * to the given CPU and the associated NUMA node. | |
818 | * | |
819 | * A good practice is to add the cpu number also into the worker name. | |
820 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
821 | * | |
822 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
823 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
824 | * when the worker was SIGKILLed. | |
825 | */ | |
826 | struct kthread_worker * | |
dbf52682 PM |
827 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
828 | const char namefmt[], ...) | |
fbae2d44 PM |
829 | { |
830 | struct kthread_worker *worker; | |
831 | va_list args; | |
832 | ||
833 | va_start(args, namefmt); | |
dbf52682 | 834 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
835 | va_end(args); |
836 | ||
837 | return worker; | |
838 | } | |
839 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
840 | ||
37be45d4 PM |
841 | /* |
842 | * Returns true when the work could not be queued at the moment. | |
843 | * It happens when it is already pending in a worker list | |
844 | * or when it is being cancelled. | |
845 | */ | |
846 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
847 | struct kthread_work *work) | |
848 | { | |
849 | lockdep_assert_held(&worker->lock); | |
850 | ||
851 | return !list_empty(&work->node) || work->canceling; | |
852 | } | |
853 | ||
8197b3d4 PM |
854 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
855 | struct kthread_work *work) | |
856 | { | |
857 | lockdep_assert_held(&worker->lock); | |
858 | WARN_ON_ONCE(!list_empty(&work->node)); | |
859 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
860 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
861 | } | |
862 | ||
9a2e03d8 | 863 | /* insert @work before @pos in @worker */ |
3989144f | 864 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
865 | struct kthread_work *work, |
866 | struct list_head *pos) | |
9a2e03d8 | 867 | { |
8197b3d4 | 868 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 TH |
869 | |
870 | list_add_tail(&work->node, pos); | |
46f3d976 | 871 | work->worker = worker; |
ed1403ec | 872 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
873 | wake_up_process(worker->task); |
874 | } | |
875 | ||
b56c0d89 | 876 | /** |
3989144f | 877 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
878 | * @worker: target kthread_worker |
879 | * @work: kthread_work to queue | |
880 | * | |
881 | * Queue @work to work processor @task for async execution. @task | |
882 | * must have been created with kthread_worker_create(). Returns %true | |
883 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
884 | * |
885 | * Reinitialize the work if it needs to be used by another worker. | |
886 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 887 | */ |
3989144f | 888 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
889 | struct kthread_work *work) |
890 | { | |
891 | bool ret = false; | |
892 | unsigned long flags; | |
893 | ||
fe99a4f4 | 894 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 | 895 | if (!queuing_blocked(worker, work)) { |
3989144f | 896 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
897 | ret = true; |
898 | } | |
fe99a4f4 | 899 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
b56c0d89 TH |
900 | return ret; |
901 | } | |
3989144f | 902 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 903 | |
22597dc3 PM |
904 | /** |
905 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
906 | * delayed work when the timer expires. | |
fe5c3b69 | 907 | * @t: pointer to the expired timer |
22597dc3 PM |
908 | * |
909 | * The format of the function is defined by struct timer_list. | |
910 | * It should have been called from irqsafe timer with irq already off. | |
911 | */ | |
fe5c3b69 | 912 | void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3 | 913 | { |
fe5c3b69 | 914 | struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3 PM |
915 | struct kthread_work *work = &dwork->work; |
916 | struct kthread_worker *worker = work->worker; | |
ad01423a | 917 | unsigned long flags; |
22597dc3 PM |
918 | |
919 | /* | |
920 | * This might happen when a pending work is reinitialized. | |
921 | * It means that it is used a wrong way. | |
922 | */ | |
923 | if (WARN_ON_ONCE(!worker)) | |
924 | return; | |
925 | ||
ad01423a | 926 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 PM |
927 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
928 | WARN_ON_ONCE(work->worker != worker); | |
929 | ||
930 | /* Move the work from worker->delayed_work_list. */ | |
931 | WARN_ON_ONCE(list_empty(&work->node)); | |
932 | list_del_init(&work->node); | |
533ef6ea Z |
933 | if (!work->canceling) |
934 | kthread_insert_work(worker, work, &worker->work_list); | |
22597dc3 | 935 | |
ad01423a | 936 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
937 | } |
938 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
939 | ||
bc88f85c BD |
940 | static void __kthread_queue_delayed_work(struct kthread_worker *worker, |
941 | struct kthread_delayed_work *dwork, | |
942 | unsigned long delay) | |
22597dc3 PM |
943 | { |
944 | struct timer_list *timer = &dwork->timer; | |
945 | struct kthread_work *work = &dwork->work; | |
946 | ||
841b86f3 | 947 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3 PM |
948 | |
949 | /* | |
950 | * If @delay is 0, queue @dwork->work immediately. This is for | |
951 | * both optimization and correctness. The earliest @timer can | |
952 | * expire is on the closest next tick and delayed_work users depend | |
953 | * on that there's no such delay when @delay is 0. | |
954 | */ | |
955 | if (!delay) { | |
956 | kthread_insert_work(worker, work, &worker->work_list); | |
957 | return; | |
958 | } | |
959 | ||
960 | /* Be paranoid and try to detect possible races already now. */ | |
961 | kthread_insert_work_sanity_check(worker, work); | |
962 | ||
963 | list_add(&work->node, &worker->delayed_work_list); | |
964 | work->worker = worker; | |
22597dc3 PM |
965 | timer->expires = jiffies + delay; |
966 | add_timer(timer); | |
967 | } | |
968 | ||
969 | /** | |
970 | * kthread_queue_delayed_work - queue the associated kthread work | |
971 | * after a delay. | |
972 | * @worker: target kthread_worker | |
973 | * @dwork: kthread_delayed_work to queue | |
974 | * @delay: number of jiffies to wait before queuing | |
975 | * | |
976 | * If the work has not been pending it starts a timer that will queue | |
977 | * the work after the given @delay. If @delay is zero, it queues the | |
978 | * work immediately. | |
979 | * | |
980 | * Return: %false if the @work has already been pending. It means that | |
981 | * either the timer was running or the work was queued. It returns %true | |
982 | * otherwise. | |
983 | */ | |
984 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
985 | struct kthread_delayed_work *dwork, | |
986 | unsigned long delay) | |
987 | { | |
988 | struct kthread_work *work = &dwork->work; | |
989 | unsigned long flags; | |
990 | bool ret = false; | |
991 | ||
fe99a4f4 | 992 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 | 993 | |
37be45d4 | 994 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
995 | __kthread_queue_delayed_work(worker, dwork, delay); |
996 | ret = true; | |
997 | } | |
998 | ||
fe99a4f4 | 999 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
1000 | return ret; |
1001 | } | |
1002 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
1003 | ||
9a2e03d8 TH |
1004 | struct kthread_flush_work { |
1005 | struct kthread_work work; | |
1006 | struct completion done; | |
1007 | }; | |
1008 | ||
1009 | static void kthread_flush_work_fn(struct kthread_work *work) | |
1010 | { | |
1011 | struct kthread_flush_work *fwork = | |
1012 | container_of(work, struct kthread_flush_work, work); | |
1013 | complete(&fwork->done); | |
1014 | } | |
1015 | ||
b56c0d89 | 1016 | /** |
3989144f | 1017 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
1018 | * @work: work to flush |
1019 | * | |
1020 | * If @work is queued or executing, wait for it to finish execution. | |
1021 | */ | |
3989144f | 1022 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 1023 | { |
46f3d976 TH |
1024 | struct kthread_flush_work fwork = { |
1025 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1026 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1027 | }; | |
1028 | struct kthread_worker *worker; | |
1029 | bool noop = false; | |
1030 | ||
46f3d976 TH |
1031 | worker = work->worker; |
1032 | if (!worker) | |
1033 | return; | |
b56c0d89 | 1034 | |
fe99a4f4 | 1035 | raw_spin_lock_irq(&worker->lock); |
8197b3d4 PM |
1036 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1037 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 1038 | |
46f3d976 | 1039 | if (!list_empty(&work->node)) |
3989144f | 1040 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 1041 | else if (worker->current_work == work) |
3989144f PM |
1042 | kthread_insert_work(worker, &fwork.work, |
1043 | worker->work_list.next); | |
46f3d976 TH |
1044 | else |
1045 | noop = true; | |
b56c0d89 | 1046 | |
fe99a4f4 | 1047 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 | 1048 | |
46f3d976 TH |
1049 | if (!noop) |
1050 | wait_for_completion(&fwork.done); | |
b56c0d89 | 1051 | } |
3989144f | 1052 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 1053 | |
fb36f850 PM |
1054 | /* |
1055 | * Make sure that the timer is neither set nor running and could | |
1056 | * not manipulate the work list_head any longer. | |
1057 | * | |
1058 | * The function is called under worker->lock. The lock is temporary | |
1059 | * released but the timer can't be set again in the meantime. | |
1060 | */ | |
1061 | static void kthread_cancel_delayed_work_timer(struct kthread_work *work, | |
1062 | unsigned long *flags) | |
1063 | { | |
1064 | struct kthread_delayed_work *dwork = | |
1065 | container_of(work, struct kthread_delayed_work, work); | |
1066 | struct kthread_worker *worker = work->worker; | |
1067 | ||
1068 | /* | |
1069 | * del_timer_sync() must be called to make sure that the timer | |
1070 | * callback is not running. The lock must be temporary released | |
1071 | * to avoid a deadlock with the callback. In the meantime, | |
1072 | * any queuing is blocked by setting the canceling counter. | |
1073 | */ | |
1074 | work->canceling++; | |
1075 | raw_spin_unlock_irqrestore(&worker->lock, *flags); | |
1076 | del_timer_sync(&dwork->timer); | |
1077 | raw_spin_lock_irqsave(&worker->lock, *flags); | |
1078 | work->canceling--; | |
1079 | } | |
1080 | ||
37be45d4 | 1081 | /* |
f7958e0b PM |
1082 | * This function removes the work from the worker queue. |
1083 | * | |
1084 | * It is called under worker->lock. The caller must make sure that | |
1085 | * the timer used by delayed work is not running, e.g. by calling | |
1086 | * kthread_cancel_delayed_work_timer(). | |
37be45d4 PM |
1087 | * |
1088 | * The work might still be in use when this function finishes. See the | |
1089 | * current_work proceed by the worker. | |
1090 | * | |
1091 | * Return: %true if @work was pending and successfully canceled, | |
1092 | * %false if @work was not pending | |
1093 | */ | |
f7958e0b | 1094 | static bool __kthread_cancel_work(struct kthread_work *work) |
37be45d4 | 1095 | { |
37be45d4 PM |
1096 | /* |
1097 | * Try to remove the work from a worker list. It might either | |
1098 | * be from worker->work_list or from worker->delayed_work_list. | |
1099 | */ | |
1100 | if (!list_empty(&work->node)) { | |
1101 | list_del_init(&work->node); | |
1102 | return true; | |
1103 | } | |
1104 | ||
1105 | return false; | |
1106 | } | |
1107 | ||
9a6b06c8 PM |
1108 | /** |
1109 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1110 | * @worker: kthread worker to use | |
1111 | * @dwork: kthread delayed work to queue | |
1112 | * @delay: number of jiffies to wait before queuing | |
1113 | * | |
1114 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1115 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1116 | * @work is guaranteed to be queued immediately. | |
1117 | * | |
3571d5cb | 1118 | * Return: %false if @dwork was idle and queued, %true otherwise. |
9a6b06c8 PM |
1119 | * |
1120 | * A special case is when the work is being canceled in parallel. | |
1121 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1122 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
3571d5cb PM |
1123 | * win and return %true here. The return value can be used for reference |
1124 | * counting and the number of queued works stays the same. Anyway, the caller | |
1125 | * is supposed to synchronize these operations a reasonable way. | |
9a6b06c8 PM |
1126 | * |
1127 | * This function is safe to call from any context including IRQ handler. | |
1128 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1129 | * for details. | |
1130 | */ | |
1131 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1132 | struct kthread_delayed_work *dwork, | |
1133 | unsigned long delay) | |
1134 | { | |
1135 | struct kthread_work *work = &dwork->work; | |
1136 | unsigned long flags; | |
3571d5cb | 1137 | int ret; |
9a6b06c8 | 1138 | |
fe99a4f4 | 1139 | raw_spin_lock_irqsave(&worker->lock, flags); |
9a6b06c8 PM |
1140 | |
1141 | /* Do not bother with canceling when never queued. */ | |
3571d5cb PM |
1142 | if (!work->worker) { |
1143 | ret = false; | |
9a6b06c8 | 1144 | goto fast_queue; |
3571d5cb | 1145 | } |
9a6b06c8 PM |
1146 | |
1147 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1148 | WARN_ON_ONCE(work->worker != worker); | |
1149 | ||
f7958e0b PM |
1150 | /* |
1151 | * Temporary cancel the work but do not fight with another command | |
1152 | * that is canceling the work as well. | |
1153 | * | |
1154 | * It is a bit tricky because of possible races with another | |
1155 | * mod_delayed_work() and cancel_delayed_work() callers. | |
1156 | * | |
1157 | * The timer must be canceled first because worker->lock is released | |
1158 | * when doing so. But the work can be removed from the queue (list) | |
1159 | * only when it can be queued again so that the return value can | |
1160 | * be used for reference counting. | |
1161 | */ | |
1162 | kthread_cancel_delayed_work_timer(work, &flags); | |
3571d5cb PM |
1163 | if (work->canceling) { |
1164 | /* The number of works in the queue does not change. */ | |
1165 | ret = true; | |
9a6b06c8 | 1166 | goto out; |
3571d5cb | 1167 | } |
f7958e0b | 1168 | ret = __kthread_cancel_work(work); |
9a6b06c8 | 1169 | |
9a6b06c8 PM |
1170 | fast_queue: |
1171 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1172 | out: | |
fe99a4f4 | 1173 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
9a6b06c8 PM |
1174 | return ret; |
1175 | } | |
1176 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1177 | ||
37be45d4 PM |
1178 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1179 | { | |
1180 | struct kthread_worker *worker = work->worker; | |
1181 | unsigned long flags; | |
1182 | int ret = false; | |
1183 | ||
1184 | if (!worker) | |
1185 | goto out; | |
1186 | ||
fe99a4f4 | 1187 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1188 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1189 | WARN_ON_ONCE(work->worker != worker); | |
1190 | ||
f7958e0b PM |
1191 | if (is_dwork) |
1192 | kthread_cancel_delayed_work_timer(work, &flags); | |
1193 | ||
1194 | ret = __kthread_cancel_work(work); | |
37be45d4 PM |
1195 | |
1196 | if (worker->current_work != work) | |
1197 | goto out_fast; | |
1198 | ||
1199 | /* | |
1200 | * The work is in progress and we need to wait with the lock released. | |
1201 | * In the meantime, block any queuing by setting the canceling counter. | |
1202 | */ | |
1203 | work->canceling++; | |
fe99a4f4 | 1204 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 | 1205 | kthread_flush_work(work); |
fe99a4f4 | 1206 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1207 | work->canceling--; |
1208 | ||
1209 | out_fast: | |
fe99a4f4 | 1210 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 PM |
1211 | out: |
1212 | return ret; | |
1213 | } | |
1214 | ||
1215 | /** | |
1216 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1217 | * @work: the kthread work to cancel | |
1218 | * | |
1219 | * Cancel @work and wait for its execution to finish. This function | |
1220 | * can be used even if the work re-queues itself. On return from this | |
1221 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1222 | * | |
1223 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1224 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1225 | * | |
1226 | * The caller must ensure that the worker on which @work was last | |
1227 | * queued can't be destroyed before this function returns. | |
1228 | * | |
1229 | * Return: %true if @work was pending, %false otherwise. | |
1230 | */ | |
1231 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1232 | { | |
1233 | return __kthread_cancel_work_sync(work, false); | |
1234 | } | |
1235 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1236 | ||
1237 | /** | |
1238 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1239 | * wait for it to finish. | |
1240 | * @dwork: the kthread delayed work to cancel | |
1241 | * | |
1242 | * This is kthread_cancel_work_sync() for delayed works. | |
1243 | * | |
1244 | * Return: %true if @dwork was pending, %false otherwise. | |
1245 | */ | |
1246 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1247 | { | |
1248 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1249 | } | |
1250 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1251 | ||
b56c0d89 | 1252 | /** |
3989144f | 1253 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1254 | * @worker: worker to flush |
1255 | * | |
1256 | * Wait until all currently executing or pending works on @worker are | |
1257 | * finished. | |
1258 | */ | |
3989144f | 1259 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1260 | { |
1261 | struct kthread_flush_work fwork = { | |
1262 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1263 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1264 | }; | |
1265 | ||
3989144f | 1266 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1267 | wait_for_completion(&fwork.done); |
1268 | } | |
3989144f | 1269 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1270 | |
1271 | /** | |
1272 | * kthread_destroy_worker - destroy a kthread worker | |
1273 | * @worker: worker to be destroyed | |
1274 | * | |
1275 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1276 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1277 | * machines needed. | |
1278 | */ | |
1279 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1280 | { | |
1281 | struct task_struct *task; | |
1282 | ||
1283 | task = worker->task; | |
1284 | if (WARN_ON(!task)) | |
1285 | return; | |
1286 | ||
1287 | kthread_flush_worker(worker); | |
1288 | kthread_stop(task); | |
1289 | WARN_ON(!list_empty(&worker->work_list)); | |
1290 | kfree(worker); | |
1291 | } | |
1292 | EXPORT_SYMBOL(kthread_destroy_worker); | |
05e3db95 | 1293 | |
0b508bc9 | 1294 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
1295 | /** |
1296 | * kthread_associate_blkcg - associate blkcg to current kthread | |
1297 | * @css: the cgroup info | |
1298 | * | |
1299 | * Current thread must be a kthread. The thread is running jobs on behalf of | |
1300 | * other threads. In some cases, we expect the jobs attach cgroup info of | |
1301 | * original threads instead of that of current thread. This function stores | |
1302 | * original thread's cgroup info in current kthread context for later | |
1303 | * retrieval. | |
1304 | */ | |
1305 | void kthread_associate_blkcg(struct cgroup_subsys_state *css) | |
1306 | { | |
b9bd0679 PZ |
1307 | struct kthread *kthread = __to_kthread(current); |
1308 | ||
05e3db95 | 1309 | |
05e3db95 SL |
1310 | if (!kthread) |
1311 | return; | |
1312 | ||
1313 | if (kthread->blkcg_css) { | |
1314 | css_put(kthread->blkcg_css); | |
1315 | kthread->blkcg_css = NULL; | |
1316 | } | |
1317 | if (css) { | |
1318 | css_get(css); | |
1319 | kthread->blkcg_css = css; | |
1320 | } | |
1321 | } | |
1322 | EXPORT_SYMBOL(kthread_associate_blkcg); | |
1323 | ||
1324 | /** | |
1325 | * kthread_blkcg - get associated blkcg css of current kthread | |
1326 | * | |
1327 | * Current thread must be a kthread. | |
1328 | */ | |
1329 | struct cgroup_subsys_state *kthread_blkcg(void) | |
1330 | { | |
b9bd0679 | 1331 | struct kthread *kthread = __to_kthread(current); |
05e3db95 | 1332 | |
b9bd0679 PZ |
1333 | if (kthread) |
1334 | return kthread->blkcg_css; | |
05e3db95 SL |
1335 | return NULL; |
1336 | } | |
1337 | EXPORT_SYMBOL(kthread_blkcg); | |
1338 | #endif |