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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. | |
9bf5b9eb | 4 | * Copyright (C) 2009 Red Hat, Inc. |
1da177e4 | 5 | * |
73c27992 | 6 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
7 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
8 | * etc.). | |
9 | */ | |
ae7e81c0 | 10 | #include <uapi/linux/sched/types.h> |
9bf5b9eb CH |
11 | #include <linux/mm.h> |
12 | #include <linux/mmu_context.h> | |
1da177e4 | 13 | #include <linux/sched.h> |
9bf5b9eb | 14 | #include <linux/sched/mm.h> |
29930025 | 15 | #include <linux/sched/task.h> |
1da177e4 LT |
16 | #include <linux/kthread.h> |
17 | #include <linux/completion.h> | |
18 | #include <linux/err.h> | |
8af0c18a | 19 | #include <linux/cgroup.h> |
58568d2a | 20 | #include <linux/cpuset.h> |
1da177e4 LT |
21 | #include <linux/unistd.h> |
22 | #include <linux/file.h> | |
9984de1a | 23 | #include <linux/export.h> |
97d1f15b | 24 | #include <linux/mutex.h> |
b56c0d89 TH |
25 | #include <linux/slab.h> |
26 | #include <linux/freezer.h> | |
a74fb73c | 27 | #include <linux/ptrace.h> |
cd42d559 | 28 | #include <linux/uaccess.h> |
98fa15f3 | 29 | #include <linux/numa.h> |
ad8d75ff | 30 | #include <trace/events/sched.h> |
1da177e4 | 31 | |
9bf5b9eb | 32 | |
73c27992 EB |
33 | static DEFINE_SPINLOCK(kthread_create_lock); |
34 | static LIST_HEAD(kthread_create_list); | |
35 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
36 | |
37 | struct kthread_create_info | |
38 | { | |
73c27992 | 39 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
40 | int (*threadfn)(void *data); |
41 | void *data; | |
207205a2 | 42 | int node; |
1da177e4 | 43 | |
73c27992 | 44 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 45 | struct task_struct *result; |
786235ee | 46 | struct completion *done; |
65f27f38 | 47 | |
73c27992 | 48 | struct list_head list; |
1da177e4 LT |
49 | }; |
50 | ||
63706172 | 51 | struct kthread { |
2a1d4460 TG |
52 | unsigned long flags; |
53 | unsigned int cpu; | |
52782c92 | 54 | int (*threadfn)(void *); |
82805ab7 | 55 | void *data; |
37c54f9b | 56 | mm_segment_t oldfs; |
2a1d4460 | 57 | struct completion parked; |
63706172 | 58 | struct completion exited; |
0b508bc9 | 59 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
60 | struct cgroup_subsys_state *blkcg_css; |
61 | #endif | |
1da177e4 LT |
62 | }; |
63 | ||
2a1d4460 TG |
64 | enum KTHREAD_BITS { |
65 | KTHREAD_IS_PER_CPU = 0, | |
66 | KTHREAD_SHOULD_STOP, | |
67 | KTHREAD_SHOULD_PARK, | |
2a1d4460 TG |
68 | }; |
69 | ||
1da5c46f ON |
70 | static inline void set_kthread_struct(void *kthread) |
71 | { | |
72 | /* | |
73 | * We abuse ->set_child_tid to avoid the new member and because it | |
74 | * can't be wrongly copied by copy_process(). We also rely on fact | |
75 | * that the caller can't exec, so PF_KTHREAD can't be cleared. | |
76 | */ | |
77 | current->set_child_tid = (__force void __user *)kthread; | |
78 | } | |
4ecdafc8 ON |
79 | |
80 | static inline struct kthread *to_kthread(struct task_struct *k) | |
81 | { | |
1da5c46f ON |
82 | WARN_ON(!(k->flags & PF_KTHREAD)); |
83 | return (__force void *)k->set_child_tid; | |
4ecdafc8 ON |
84 | } |
85 | ||
1da5c46f ON |
86 | void free_kthread_struct(struct task_struct *k) |
87 | { | |
05e3db95 SL |
88 | struct kthread *kthread; |
89 | ||
1da5c46f ON |
90 | /* |
91 | * Can be NULL if this kthread was created by kernel_thread() | |
92 | * or if kmalloc() in kthread() failed. | |
93 | */ | |
05e3db95 | 94 | kthread = to_kthread(k); |
0b508bc9 | 95 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
96 | WARN_ON_ONCE(kthread && kthread->blkcg_css); |
97 | #endif | |
98 | kfree(kthread); | |
1da5c46f ON |
99 | } |
100 | ||
9e37bd30 RD |
101 | /** |
102 | * kthread_should_stop - should this kthread return now? | |
103 | * | |
72fd4a35 | 104 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
105 | * and this will return true. You should then return, and your return |
106 | * value will be passed through to kthread_stop(). | |
107 | */ | |
2a1d4460 | 108 | bool kthread_should_stop(void) |
1da177e4 | 109 | { |
2a1d4460 | 110 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
111 | } |
112 | EXPORT_SYMBOL(kthread_should_stop); | |
113 | ||
0121805d MK |
114 | bool __kthread_should_park(struct task_struct *k) |
115 | { | |
116 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); | |
117 | } | |
118 | EXPORT_SYMBOL_GPL(__kthread_should_park); | |
119 | ||
2a1d4460 TG |
120 | /** |
121 | * kthread_should_park - should this kthread park now? | |
122 | * | |
123 | * When someone calls kthread_park() on your kthread, it will be woken | |
124 | * and this will return true. You should then do the necessary | |
125 | * cleanup and call kthread_parkme() | |
126 | * | |
127 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
128 | * and in a park position. kthread_unpark() "restarts" the thread and | |
129 | * calls the thread function again. | |
130 | */ | |
131 | bool kthread_should_park(void) | |
132 | { | |
0121805d | 133 | return __kthread_should_park(current); |
2a1d4460 | 134 | } |
18896451 | 135 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 136 | |
8a32c441 TH |
137 | /** |
138 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
139 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
140 | * | |
141 | * kthread_should_stop() for freezable kthreads, which will enter | |
142 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
143 | * freezer deadlock and freezable kthreads should use this function instead | |
144 | * of calling try_to_freeze() directly. | |
145 | */ | |
146 | bool kthread_freezable_should_stop(bool *was_frozen) | |
147 | { | |
148 | bool frozen = false; | |
149 | ||
150 | might_sleep(); | |
151 | ||
152 | if (unlikely(freezing(current))) | |
153 | frozen = __refrigerator(true); | |
154 | ||
155 | if (was_frozen) | |
156 | *was_frozen = frozen; | |
157 | ||
158 | return kthread_should_stop(); | |
159 | } | |
160 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
161 | ||
52782c92 BF |
162 | /** |
163 | * kthread_func - return the function specified on kthread creation | |
164 | * @task: kthread task in question | |
165 | * | |
166 | * Returns NULL if the task is not a kthread. | |
167 | */ | |
168 | void *kthread_func(struct task_struct *task) | |
169 | { | |
170 | if (task->flags & PF_KTHREAD) | |
171 | return to_kthread(task)->threadfn; | |
172 | return NULL; | |
173 | } | |
174 | EXPORT_SYMBOL_GPL(kthread_func); | |
175 | ||
82805ab7 TH |
176 | /** |
177 | * kthread_data - return data value specified on kthread creation | |
178 | * @task: kthread task in question | |
179 | * | |
180 | * Return the data value specified when kthread @task was created. | |
181 | * The caller is responsible for ensuring the validity of @task when | |
182 | * calling this function. | |
183 | */ | |
184 | void *kthread_data(struct task_struct *task) | |
185 | { | |
186 | return to_kthread(task)->data; | |
187 | } | |
52782c92 | 188 | EXPORT_SYMBOL_GPL(kthread_data); |
82805ab7 | 189 | |
cd42d559 | 190 | /** |
e700591a | 191 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
192 | * @task: possible kthread task in question |
193 | * | |
194 | * @task could be a kthread task. Return the data value specified when it | |
195 | * was created if accessible. If @task isn't a kthread task or its data is | |
196 | * inaccessible for any reason, %NULL is returned. This function requires | |
197 | * that @task itself is safe to dereference. | |
198 | */ | |
e700591a | 199 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 TH |
200 | { |
201 | struct kthread *kthread = to_kthread(task); | |
202 | void *data = NULL; | |
203 | ||
fe557319 | 204 | copy_from_kernel_nofault(&data, &kthread->data, sizeof(data)); |
cd42d559 TH |
205 | return data; |
206 | } | |
207 | ||
2a1d4460 TG |
208 | static void __kthread_parkme(struct kthread *self) |
209 | { | |
741a76b3 | 210 | for (;;) { |
1cef1150 PZ |
211 | /* |
212 | * TASK_PARKED is a special state; we must serialize against | |
213 | * possible pending wakeups to avoid store-store collisions on | |
214 | * task->state. | |
215 | * | |
216 | * Such a collision might possibly result in the task state | |
217 | * changin from TASK_PARKED and us failing the | |
218 | * wait_task_inactive() in kthread_park(). | |
219 | */ | |
220 | set_special_state(TASK_PARKED); | |
741a76b3 PZ |
221 | if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) |
222 | break; | |
1cef1150 | 223 | |
26c7295b LC |
224 | /* |
225 | * Thread is going to call schedule(), do not preempt it, | |
226 | * or the caller of kthread_park() may spend more time in | |
227 | * wait_task_inactive(). | |
228 | */ | |
229 | preempt_disable(); | |
f83ee19b | 230 | complete(&self->parked); |
26c7295b LC |
231 | schedule_preempt_disabled(); |
232 | preempt_enable(); | |
2a1d4460 | 233 | } |
2a1d4460 TG |
234 | __set_current_state(TASK_RUNNING); |
235 | } | |
236 | ||
237 | void kthread_parkme(void) | |
238 | { | |
239 | __kthread_parkme(to_kthread(current)); | |
240 | } | |
18896451 | 241 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 242 | |
1da177e4 LT |
243 | static int kthread(void *_create) |
244 | { | |
63706172 | 245 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 246 | struct kthread_create_info *create = _create; |
63706172 ON |
247 | int (*threadfn)(void *data) = create->threadfn; |
248 | void *data = create->data; | |
786235ee | 249 | struct completion *done; |
1da5c46f | 250 | struct kthread *self; |
63706172 | 251 | int ret; |
1da177e4 | 252 | |
e10237cc | 253 | self = kzalloc(sizeof(*self), GFP_KERNEL); |
1da5c46f | 254 | set_kthread_struct(self); |
1da177e4 | 255 | |
786235ee TH |
256 | /* If user was SIGKILLed, I release the structure. */ |
257 | done = xchg(&create->done, NULL); | |
258 | if (!done) { | |
259 | kfree(create); | |
260 | do_exit(-EINTR); | |
261 | } | |
1da5c46f ON |
262 | |
263 | if (!self) { | |
264 | create->result = ERR_PTR(-ENOMEM); | |
265 | complete(done); | |
266 | do_exit(-ENOMEM); | |
267 | } | |
268 | ||
52782c92 | 269 | self->threadfn = threadfn; |
1da5c46f ON |
270 | self->data = data; |
271 | init_completion(&self->exited); | |
272 | init_completion(&self->parked); | |
273 | current->vfork_done = &self->exited; | |
274 | ||
1da177e4 | 275 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 276 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 277 | create->result = current; |
26c7295b LC |
278 | /* |
279 | * Thread is going to call schedule(), do not preempt it, | |
280 | * or the creator may spend more time in wait_task_inactive(). | |
281 | */ | |
282 | preempt_disable(); | |
786235ee | 283 | complete(done); |
26c7295b LC |
284 | schedule_preempt_disabled(); |
285 | preempt_enable(); | |
1da177e4 | 286 | |
63706172 | 287 | ret = -EINTR; |
1da5c46f | 288 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
77f88796 | 289 | cgroup_kthread_ready(); |
1da5c46f | 290 | __kthread_parkme(self); |
2a1d4460 TG |
291 | ret = threadfn(data); |
292 | } | |
63706172 | 293 | do_exit(ret); |
1da177e4 LT |
294 | } |
295 | ||
207205a2 ED |
296 | /* called from do_fork() to get node information for about to be created task */ |
297 | int tsk_fork_get_node(struct task_struct *tsk) | |
298 | { | |
299 | #ifdef CONFIG_NUMA | |
300 | if (tsk == kthreadd_task) | |
301 | return tsk->pref_node_fork; | |
302 | #endif | |
81c98869 | 303 | return NUMA_NO_NODE; |
207205a2 ED |
304 | } |
305 | ||
73c27992 | 306 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 307 | { |
1da177e4 LT |
308 | int pid; |
309 | ||
207205a2 ED |
310 | #ifdef CONFIG_NUMA |
311 | current->pref_node_fork = create->node; | |
312 | #endif | |
1da177e4 LT |
313 | /* We want our own signal handler (we take no signals by default). */ |
314 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 315 | if (pid < 0) { |
786235ee TH |
316 | /* If user was SIGKILLed, I release the structure. */ |
317 | struct completion *done = xchg(&create->done, NULL); | |
318 | ||
319 | if (!done) { | |
320 | kfree(create); | |
321 | return; | |
322 | } | |
1da177e4 | 323 | create->result = ERR_PTR(pid); |
786235ee | 324 | complete(done); |
cdd140bd | 325 | } |
1da177e4 LT |
326 | } |
327 | ||
c0b942a7 NI |
328 | static __printf(4, 0) |
329 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
330 | void *data, int node, |
331 | const char namefmt[], | |
332 | va_list args) | |
1da177e4 | 333 | { |
786235ee TH |
334 | DECLARE_COMPLETION_ONSTACK(done); |
335 | struct task_struct *task; | |
336 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
337 | GFP_KERNEL); | |
338 | ||
339 | if (!create) | |
340 | return ERR_PTR(-ENOMEM); | |
341 | create->threadfn = threadfn; | |
342 | create->data = data; | |
343 | create->node = node; | |
344 | create->done = &done; | |
73c27992 EB |
345 | |
346 | spin_lock(&kthread_create_lock); | |
786235ee | 347 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
348 | spin_unlock(&kthread_create_lock); |
349 | ||
cbd9b67b | 350 | wake_up_process(kthreadd_task); |
786235ee TH |
351 | /* |
352 | * Wait for completion in killable state, for I might be chosen by | |
353 | * the OOM killer while kthreadd is trying to allocate memory for | |
354 | * new kernel thread. | |
355 | */ | |
356 | if (unlikely(wait_for_completion_killable(&done))) { | |
357 | /* | |
358 | * If I was SIGKILLed before kthreadd (or new kernel thread) | |
359 | * calls complete(), leave the cleanup of this structure to | |
360 | * that thread. | |
361 | */ | |
362 | if (xchg(&create->done, NULL)) | |
8fe6929c | 363 | return ERR_PTR(-EINTR); |
786235ee TH |
364 | /* |
365 | * kthreadd (or new kernel thread) will call complete() | |
366 | * shortly. | |
367 | */ | |
368 | wait_for_completion(&done); | |
369 | } | |
370 | task = create->result; | |
371 | if (!IS_ERR(task)) { | |
c9b5f501 | 372 | static const struct sched_param param = { .sched_priority = 0 }; |
3e536e22 | 373 | char name[TASK_COMM_LEN]; |
1c99315b | 374 | |
3e536e22 SD |
375 | /* |
376 | * task is already visible to other tasks, so updating | |
377 | * COMM must be protected. | |
378 | */ | |
379 | vsnprintf(name, sizeof(name), namefmt, args); | |
380 | set_task_comm(task, name); | |
1c99315b ON |
381 | /* |
382 | * root may have changed our (kthreadd's) priority or CPU mask. | |
383 | * The kernel thread should not inherit these properties. | |
384 | */ | |
786235ee TH |
385 | sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
386 | set_cpus_allowed_ptr(task, cpu_all_mask); | |
1da177e4 | 387 | } |
786235ee TH |
388 | kfree(create); |
389 | return task; | |
1da177e4 | 390 | } |
255451e4 PM |
391 | |
392 | /** | |
393 | * kthread_create_on_node - create a kthread. | |
394 | * @threadfn: the function to run until signal_pending(current). | |
395 | * @data: data ptr for @threadfn. | |
396 | * @node: task and thread structures for the thread are allocated on this node | |
397 | * @namefmt: printf-style name for the thread. | |
398 | * | |
399 | * Description: This helper function creates and names a kernel | |
400 | * thread. The thread will be stopped: use wake_up_process() to start | |
401 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
402 | * is affine to all CPUs. | |
403 | * | |
404 | * If thread is going to be bound on a particular cpu, give its node | |
405 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
406 | * When woken, the thread will run @threadfn() with @data as its | |
407 | * argument. @threadfn() can either call do_exit() directly if it is a | |
408 | * standalone thread for which no one will call kthread_stop(), or | |
409 | * return when 'kthread_should_stop()' is true (which means | |
410 | * kthread_stop() has been called). The return value should be zero | |
411 | * or a negative error number; it will be passed to kthread_stop(). | |
412 | * | |
413 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
414 | */ | |
415 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
416 | void *data, int node, | |
417 | const char namefmt[], | |
418 | ...) | |
419 | { | |
420 | struct task_struct *task; | |
421 | va_list args; | |
422 | ||
423 | va_start(args, namefmt); | |
424 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
425 | va_end(args); | |
426 | ||
427 | return task; | |
428 | } | |
207205a2 | 429 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 430 | |
25834c73 | 431 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
2a1d4460 | 432 | { |
25834c73 PZ |
433 | unsigned long flags; |
434 | ||
f2530dc7 TG |
435 | if (!wait_task_inactive(p, state)) { |
436 | WARN_ON(1); | |
437 | return; | |
438 | } | |
25834c73 | 439 | |
2a1d4460 | 440 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
441 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
442 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 443 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
444 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
445 | } | |
446 | ||
447 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) | |
448 | { | |
449 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
450 | } | |
451 | ||
452 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
453 | { | |
454 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
455 | } |
456 | ||
881232b7 PZ |
457 | /** |
458 | * kthread_bind - bind a just-created kthread to a cpu. | |
459 | * @p: thread created by kthread_create(). | |
460 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
461 | * | |
462 | * Description: This function is equivalent to set_cpus_allowed(), | |
463 | * except that @cpu doesn't need to be online, and the thread must be | |
464 | * stopped (i.e., just returned from kthread_create()). | |
465 | */ | |
466 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
467 | { | |
f2530dc7 | 468 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
469 | } |
470 | EXPORT_SYMBOL(kthread_bind); | |
471 | ||
2a1d4460 TG |
472 | /** |
473 | * kthread_create_on_cpu - Create a cpu bound kthread | |
474 | * @threadfn: the function to run until signal_pending(current). | |
475 | * @data: data ptr for @threadfn. | |
476 | * @cpu: The cpu on which the thread should be bound, | |
477 | * @namefmt: printf-style name for the thread. Format is restricted | |
478 | * to "name.*%u". Code fills in cpu number. | |
479 | * | |
480 | * Description: This helper function creates and names a kernel thread | |
481 | * The thread will be woken and put into park mode. | |
482 | */ | |
483 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
484 | void *data, unsigned int cpu, | |
485 | const char *namefmt) | |
486 | { | |
487 | struct task_struct *p; | |
488 | ||
10922838 | 489 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
490 | cpu); |
491 | if (IS_ERR(p)) | |
492 | return p; | |
a65d4096 PM |
493 | kthread_bind(p, cpu); |
494 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 TG |
495 | set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); |
496 | to_kthread(p)->cpu = cpu; | |
2a1d4460 TG |
497 | return p; |
498 | } | |
499 | ||
cf380a4a ON |
500 | /** |
501 | * kthread_unpark - unpark a thread created by kthread_create(). | |
502 | * @k: thread created by kthread_create(). | |
503 | * | |
504 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
505 | * waits for it to return. If the thread is marked percpu then its | |
506 | * bound to the cpu again. | |
507 | */ | |
508 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 509 | { |
cf380a4a ON |
510 | struct kthread *kthread = to_kthread(k); |
511 | ||
f2530dc7 | 512 | /* |
85f1abe0 PZ |
513 | * Newly created kthread was parked when the CPU was offline. |
514 | * The binding was lost and we need to set it again. | |
f2530dc7 | 515 | */ |
85f1abe0 PZ |
516 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
517 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
518 | ||
519 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
1cef1150 PZ |
520 | /* |
521 | * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. | |
522 | */ | |
85f1abe0 | 523 | wake_up_state(k, TASK_PARKED); |
f2530dc7 | 524 | } |
18896451 | 525 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
526 | |
527 | /** | |
528 | * kthread_park - park a thread created by kthread_create(). | |
529 | * @k: thread created by kthread_create(). | |
530 | * | |
531 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
532 | * waits for it to return. This can also be called after kthread_create() | |
533 | * instead of calling wake_up_process(): the thread will park without | |
534 | * calling threadfn(). | |
535 | * | |
536 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
537 | * If called by the kthread itself just the park bit is set. | |
538 | */ | |
539 | int kthread_park(struct task_struct *k) | |
540 | { | |
cf380a4a ON |
541 | struct kthread *kthread = to_kthread(k); |
542 | ||
543 | if (WARN_ON(k->flags & PF_EXITING)) | |
544 | return -ENOSYS; | |
545 | ||
f83ee19b PZ |
546 | if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) |
547 | return -EBUSY; | |
548 | ||
85f1abe0 PZ |
549 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
550 | if (k != current) { | |
551 | wake_up_process(k); | |
1cef1150 PZ |
552 | /* |
553 | * Wait for __kthread_parkme() to complete(), this means we | |
554 | * _will_ have TASK_PARKED and are about to call schedule(). | |
555 | */ | |
85f1abe0 | 556 | wait_for_completion(&kthread->parked); |
1cef1150 PZ |
557 | /* |
558 | * Now wait for that schedule() to complete and the task to | |
559 | * get scheduled out. | |
560 | */ | |
561 | WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED)); | |
2a1d4460 | 562 | } |
cf380a4a ON |
563 | |
564 | return 0; | |
2a1d4460 | 565 | } |
18896451 | 566 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 567 | |
9e37bd30 RD |
568 | /** |
569 | * kthread_stop - stop a thread created by kthread_create(). | |
570 | * @k: thread created by kthread_create(). | |
571 | * | |
572 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
573 | * waits for it to exit. This can also be called after kthread_create() |
574 | * instead of calling wake_up_process(): the thread will exit without | |
575 | * calling threadfn(). | |
576 | * | |
577 | * If threadfn() may call do_exit() itself, the caller must ensure | |
578 | * task_struct can't go away. | |
9e37bd30 RD |
579 | * |
580 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
581 | * was never called. | |
582 | */ | |
1da177e4 LT |
583 | int kthread_stop(struct task_struct *k) |
584 | { | |
b5c5442b | 585 | struct kthread *kthread; |
1da177e4 LT |
586 | int ret; |
587 | ||
0a16b607 | 588 | trace_sched_kthread_stop(k); |
b5c5442b ON |
589 | |
590 | get_task_struct(k); | |
efb29fbf ON |
591 | kthread = to_kthread(k); |
592 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 593 | kthread_unpark(k); |
efb29fbf ON |
594 | wake_up_process(k); |
595 | wait_for_completion(&kthread->exited); | |
63706172 | 596 | ret = k->exit_code; |
1da177e4 | 597 | put_task_struct(k); |
0a16b607 | 598 | |
b5c5442b | 599 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
600 | return ret; |
601 | } | |
52e92e57 | 602 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 603 | |
e804a4a4 | 604 | int kthreadd(void *unused) |
1da177e4 | 605 | { |
73c27992 | 606 | struct task_struct *tsk = current; |
1da177e4 | 607 | |
e804a4a4 | 608 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 609 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 610 | ignore_signals(tsk); |
1a2142af | 611 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa4 | 612 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 613 | |
34b087e4 | 614 | current->flags |= PF_NOFREEZE; |
77f88796 | 615 | cgroup_init_kthreadd(); |
73c27992 EB |
616 | |
617 | for (;;) { | |
618 | set_current_state(TASK_INTERRUPTIBLE); | |
619 | if (list_empty(&kthread_create_list)) | |
620 | schedule(); | |
621 | __set_current_state(TASK_RUNNING); | |
622 | ||
623 | spin_lock(&kthread_create_lock); | |
624 | while (!list_empty(&kthread_create_list)) { | |
625 | struct kthread_create_info *create; | |
626 | ||
627 | create = list_entry(kthread_create_list.next, | |
628 | struct kthread_create_info, list); | |
629 | list_del_init(&create->list); | |
630 | spin_unlock(&kthread_create_lock); | |
631 | ||
632 | create_kthread(create); | |
633 | ||
634 | spin_lock(&kthread_create_lock); | |
635 | } | |
636 | spin_unlock(&kthread_create_lock); | |
637 | } | |
638 | ||
639 | return 0; | |
640 | } | |
b56c0d89 | 641 | |
3989144f | 642 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
643 | const char *name, |
644 | struct lock_class_key *key) | |
645 | { | |
dbf52682 | 646 | memset(worker, 0, sizeof(struct kthread_worker)); |
fe99a4f4 | 647 | raw_spin_lock_init(&worker->lock); |
4f32e9b1 YZ |
648 | lockdep_set_class_and_name(&worker->lock, key, name); |
649 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 650 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 651 | } |
3989144f | 652 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 653 | |
b56c0d89 TH |
654 | /** |
655 | * kthread_worker_fn - kthread function to process kthread_worker | |
656 | * @worker_ptr: pointer to initialized kthread_worker | |
657 | * | |
fbae2d44 PM |
658 | * This function implements the main cycle of kthread worker. It processes |
659 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
660 | * is empty. | |
b56c0d89 | 661 | * |
fbae2d44 PM |
662 | * The works are not allowed to keep any locks, disable preemption or interrupts |
663 | * when they finish. There is defined a safe point for freezing when one work | |
664 | * finishes and before a new one is started. | |
8197b3d4 PM |
665 | * |
666 | * Also the works must not be handled by more than one worker at the same time, | |
667 | * see also kthread_queue_work(). | |
b56c0d89 TH |
668 | */ |
669 | int kthread_worker_fn(void *worker_ptr) | |
670 | { | |
671 | struct kthread_worker *worker = worker_ptr; | |
672 | struct kthread_work *work; | |
673 | ||
fbae2d44 PM |
674 | /* |
675 | * FIXME: Update the check and remove the assignment when all kthread | |
676 | * worker users are created using kthread_create_worker*() functions. | |
677 | */ | |
678 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 679 | worker->task = current; |
dbf52682 PM |
680 | |
681 | if (worker->flags & KTW_FREEZABLE) | |
682 | set_freezable(); | |
683 | ||
b56c0d89 TH |
684 | repeat: |
685 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
686 | ||
687 | if (kthread_should_stop()) { | |
688 | __set_current_state(TASK_RUNNING); | |
fe99a4f4 | 689 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 | 690 | worker->task = NULL; |
fe99a4f4 | 691 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
692 | return 0; |
693 | } | |
694 | ||
695 | work = NULL; | |
fe99a4f4 | 696 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 TH |
697 | if (!list_empty(&worker->work_list)) { |
698 | work = list_first_entry(&worker->work_list, | |
699 | struct kthread_work, node); | |
700 | list_del_init(&work->node); | |
701 | } | |
46f3d976 | 702 | worker->current_work = work; |
fe99a4f4 | 703 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
704 | |
705 | if (work) { | |
706 | __set_current_state(TASK_RUNNING); | |
707 | work->func(work); | |
b56c0d89 TH |
708 | } else if (!freezing(current)) |
709 | schedule(); | |
710 | ||
711 | try_to_freeze(); | |
22cf8bc6 | 712 | cond_resched(); |
b56c0d89 TH |
713 | goto repeat; |
714 | } | |
715 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
716 | ||
c0b942a7 | 717 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
718 | __kthread_create_worker(int cpu, unsigned int flags, |
719 | const char namefmt[], va_list args) | |
fbae2d44 PM |
720 | { |
721 | struct kthread_worker *worker; | |
722 | struct task_struct *task; | |
98fa15f3 | 723 | int node = NUMA_NO_NODE; |
fbae2d44 PM |
724 | |
725 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
726 | if (!worker) | |
727 | return ERR_PTR(-ENOMEM); | |
728 | ||
729 | kthread_init_worker(worker); | |
730 | ||
8fb9dcbd ON |
731 | if (cpu >= 0) |
732 | node = cpu_to_node(cpu); | |
fbae2d44 | 733 | |
8fb9dcbd ON |
734 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
735 | node, namefmt, args); | |
fbae2d44 PM |
736 | if (IS_ERR(task)) |
737 | goto fail_task; | |
738 | ||
8fb9dcbd ON |
739 | if (cpu >= 0) |
740 | kthread_bind(task, cpu); | |
741 | ||
dbf52682 | 742 | worker->flags = flags; |
fbae2d44 PM |
743 | worker->task = task; |
744 | wake_up_process(task); | |
745 | return worker; | |
746 | ||
747 | fail_task: | |
748 | kfree(worker); | |
749 | return ERR_CAST(task); | |
750 | } | |
751 | ||
752 | /** | |
753 | * kthread_create_worker - create a kthread worker | |
dbf52682 | 754 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
755 | * @namefmt: printf-style name for the kthread worker (task). |
756 | * | |
757 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
758 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
759 | * when the worker was SIGKILLed. | |
760 | */ | |
761 | struct kthread_worker * | |
dbf52682 | 762 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
763 | { |
764 | struct kthread_worker *worker; | |
765 | va_list args; | |
766 | ||
767 | va_start(args, namefmt); | |
dbf52682 | 768 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
769 | va_end(args); |
770 | ||
771 | return worker; | |
772 | } | |
773 | EXPORT_SYMBOL(kthread_create_worker); | |
774 | ||
775 | /** | |
776 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
777 | * it to a given CPU and the associated NUMA node. | |
778 | * @cpu: CPU number | |
dbf52682 | 779 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
780 | * @namefmt: printf-style name for the kthread worker (task). |
781 | * | |
782 | * Use a valid CPU number if you want to bind the kthread worker | |
783 | * to the given CPU and the associated NUMA node. | |
784 | * | |
785 | * A good practice is to add the cpu number also into the worker name. | |
786 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
787 | * | |
788 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
789 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
790 | * when the worker was SIGKILLed. | |
791 | */ | |
792 | struct kthread_worker * | |
dbf52682 PM |
793 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
794 | const char namefmt[], ...) | |
fbae2d44 PM |
795 | { |
796 | struct kthread_worker *worker; | |
797 | va_list args; | |
798 | ||
799 | va_start(args, namefmt); | |
dbf52682 | 800 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
801 | va_end(args); |
802 | ||
803 | return worker; | |
804 | } | |
805 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
806 | ||
37be45d4 PM |
807 | /* |
808 | * Returns true when the work could not be queued at the moment. | |
809 | * It happens when it is already pending in a worker list | |
810 | * or when it is being cancelled. | |
811 | */ | |
812 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
813 | struct kthread_work *work) | |
814 | { | |
815 | lockdep_assert_held(&worker->lock); | |
816 | ||
817 | return !list_empty(&work->node) || work->canceling; | |
818 | } | |
819 | ||
8197b3d4 PM |
820 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
821 | struct kthread_work *work) | |
822 | { | |
823 | lockdep_assert_held(&worker->lock); | |
824 | WARN_ON_ONCE(!list_empty(&work->node)); | |
825 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
826 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
827 | } | |
828 | ||
9a2e03d8 | 829 | /* insert @work before @pos in @worker */ |
3989144f | 830 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
831 | struct kthread_work *work, |
832 | struct list_head *pos) | |
9a2e03d8 | 833 | { |
8197b3d4 | 834 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 TH |
835 | |
836 | list_add_tail(&work->node, pos); | |
46f3d976 | 837 | work->worker = worker; |
ed1403ec | 838 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
839 | wake_up_process(worker->task); |
840 | } | |
841 | ||
b56c0d89 | 842 | /** |
3989144f | 843 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
844 | * @worker: target kthread_worker |
845 | * @work: kthread_work to queue | |
846 | * | |
847 | * Queue @work to work processor @task for async execution. @task | |
848 | * must have been created with kthread_worker_create(). Returns %true | |
849 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
850 | * |
851 | * Reinitialize the work if it needs to be used by another worker. | |
852 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 853 | */ |
3989144f | 854 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
855 | struct kthread_work *work) |
856 | { | |
857 | bool ret = false; | |
858 | unsigned long flags; | |
859 | ||
fe99a4f4 | 860 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 | 861 | if (!queuing_blocked(worker, work)) { |
3989144f | 862 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
863 | ret = true; |
864 | } | |
fe99a4f4 | 865 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
b56c0d89 TH |
866 | return ret; |
867 | } | |
3989144f | 868 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 869 | |
22597dc3 PM |
870 | /** |
871 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
872 | * delayed work when the timer expires. | |
fe5c3b69 | 873 | * @t: pointer to the expired timer |
22597dc3 PM |
874 | * |
875 | * The format of the function is defined by struct timer_list. | |
876 | * It should have been called from irqsafe timer with irq already off. | |
877 | */ | |
fe5c3b69 | 878 | void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3 | 879 | { |
fe5c3b69 | 880 | struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3 PM |
881 | struct kthread_work *work = &dwork->work; |
882 | struct kthread_worker *worker = work->worker; | |
ad01423a | 883 | unsigned long flags; |
22597dc3 PM |
884 | |
885 | /* | |
886 | * This might happen when a pending work is reinitialized. | |
887 | * It means that it is used a wrong way. | |
888 | */ | |
889 | if (WARN_ON_ONCE(!worker)) | |
890 | return; | |
891 | ||
ad01423a | 892 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 PM |
893 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
894 | WARN_ON_ONCE(work->worker != worker); | |
895 | ||
896 | /* Move the work from worker->delayed_work_list. */ | |
897 | WARN_ON_ONCE(list_empty(&work->node)); | |
898 | list_del_init(&work->node); | |
899 | kthread_insert_work(worker, work, &worker->work_list); | |
900 | ||
ad01423a | 901 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
902 | } |
903 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
904 | ||
bc88f85c BD |
905 | static void __kthread_queue_delayed_work(struct kthread_worker *worker, |
906 | struct kthread_delayed_work *dwork, | |
907 | unsigned long delay) | |
22597dc3 PM |
908 | { |
909 | struct timer_list *timer = &dwork->timer; | |
910 | struct kthread_work *work = &dwork->work; | |
911 | ||
841b86f3 | 912 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3 PM |
913 | |
914 | /* | |
915 | * If @delay is 0, queue @dwork->work immediately. This is for | |
916 | * both optimization and correctness. The earliest @timer can | |
917 | * expire is on the closest next tick and delayed_work users depend | |
918 | * on that there's no such delay when @delay is 0. | |
919 | */ | |
920 | if (!delay) { | |
921 | kthread_insert_work(worker, work, &worker->work_list); | |
922 | return; | |
923 | } | |
924 | ||
925 | /* Be paranoid and try to detect possible races already now. */ | |
926 | kthread_insert_work_sanity_check(worker, work); | |
927 | ||
928 | list_add(&work->node, &worker->delayed_work_list); | |
929 | work->worker = worker; | |
22597dc3 PM |
930 | timer->expires = jiffies + delay; |
931 | add_timer(timer); | |
932 | } | |
933 | ||
934 | /** | |
935 | * kthread_queue_delayed_work - queue the associated kthread work | |
936 | * after a delay. | |
937 | * @worker: target kthread_worker | |
938 | * @dwork: kthread_delayed_work to queue | |
939 | * @delay: number of jiffies to wait before queuing | |
940 | * | |
941 | * If the work has not been pending it starts a timer that will queue | |
942 | * the work after the given @delay. If @delay is zero, it queues the | |
943 | * work immediately. | |
944 | * | |
945 | * Return: %false if the @work has already been pending. It means that | |
946 | * either the timer was running or the work was queued. It returns %true | |
947 | * otherwise. | |
948 | */ | |
949 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
950 | struct kthread_delayed_work *dwork, | |
951 | unsigned long delay) | |
952 | { | |
953 | struct kthread_work *work = &dwork->work; | |
954 | unsigned long flags; | |
955 | bool ret = false; | |
956 | ||
fe99a4f4 | 957 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 | 958 | |
37be45d4 | 959 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
960 | __kthread_queue_delayed_work(worker, dwork, delay); |
961 | ret = true; | |
962 | } | |
963 | ||
fe99a4f4 | 964 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
965 | return ret; |
966 | } | |
967 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
968 | ||
9a2e03d8 TH |
969 | struct kthread_flush_work { |
970 | struct kthread_work work; | |
971 | struct completion done; | |
972 | }; | |
973 | ||
974 | static void kthread_flush_work_fn(struct kthread_work *work) | |
975 | { | |
976 | struct kthread_flush_work *fwork = | |
977 | container_of(work, struct kthread_flush_work, work); | |
978 | complete(&fwork->done); | |
979 | } | |
980 | ||
b56c0d89 | 981 | /** |
3989144f | 982 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
983 | * @work: work to flush |
984 | * | |
985 | * If @work is queued or executing, wait for it to finish execution. | |
986 | */ | |
3989144f | 987 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 988 | { |
46f3d976 TH |
989 | struct kthread_flush_work fwork = { |
990 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
991 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
992 | }; | |
993 | struct kthread_worker *worker; | |
994 | bool noop = false; | |
995 | ||
46f3d976 TH |
996 | worker = work->worker; |
997 | if (!worker) | |
998 | return; | |
b56c0d89 | 999 | |
fe99a4f4 | 1000 | raw_spin_lock_irq(&worker->lock); |
8197b3d4 PM |
1001 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1002 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 1003 | |
46f3d976 | 1004 | if (!list_empty(&work->node)) |
3989144f | 1005 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 1006 | else if (worker->current_work == work) |
3989144f PM |
1007 | kthread_insert_work(worker, &fwork.work, |
1008 | worker->work_list.next); | |
46f3d976 TH |
1009 | else |
1010 | noop = true; | |
b56c0d89 | 1011 | |
fe99a4f4 | 1012 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 | 1013 | |
46f3d976 TH |
1014 | if (!noop) |
1015 | wait_for_completion(&fwork.done); | |
b56c0d89 | 1016 | } |
3989144f | 1017 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 1018 | |
37be45d4 PM |
1019 | /* |
1020 | * This function removes the work from the worker queue. Also it makes sure | |
1021 | * that it won't get queued later via the delayed work's timer. | |
1022 | * | |
1023 | * The work might still be in use when this function finishes. See the | |
1024 | * current_work proceed by the worker. | |
1025 | * | |
1026 | * Return: %true if @work was pending and successfully canceled, | |
1027 | * %false if @work was not pending | |
1028 | */ | |
1029 | static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork, | |
1030 | unsigned long *flags) | |
1031 | { | |
1032 | /* Try to cancel the timer if exists. */ | |
1033 | if (is_dwork) { | |
1034 | struct kthread_delayed_work *dwork = | |
1035 | container_of(work, struct kthread_delayed_work, work); | |
1036 | struct kthread_worker *worker = work->worker; | |
1037 | ||
1038 | /* | |
1039 | * del_timer_sync() must be called to make sure that the timer | |
1040 | * callback is not running. The lock must be temporary released | |
1041 | * to avoid a deadlock with the callback. In the meantime, | |
1042 | * any queuing is blocked by setting the canceling counter. | |
1043 | */ | |
1044 | work->canceling++; | |
fe99a4f4 | 1045 | raw_spin_unlock_irqrestore(&worker->lock, *flags); |
37be45d4 | 1046 | del_timer_sync(&dwork->timer); |
fe99a4f4 | 1047 | raw_spin_lock_irqsave(&worker->lock, *flags); |
37be45d4 PM |
1048 | work->canceling--; |
1049 | } | |
1050 | ||
1051 | /* | |
1052 | * Try to remove the work from a worker list. It might either | |
1053 | * be from worker->work_list or from worker->delayed_work_list. | |
1054 | */ | |
1055 | if (!list_empty(&work->node)) { | |
1056 | list_del_init(&work->node); | |
1057 | return true; | |
1058 | } | |
1059 | ||
1060 | return false; | |
1061 | } | |
1062 | ||
9a6b06c8 PM |
1063 | /** |
1064 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1065 | * @worker: kthread worker to use | |
1066 | * @dwork: kthread delayed work to queue | |
1067 | * @delay: number of jiffies to wait before queuing | |
1068 | * | |
1069 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1070 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1071 | * @work is guaranteed to be queued immediately. | |
1072 | * | |
1073 | * Return: %true if @dwork was pending and its timer was modified, | |
1074 | * %false otherwise. | |
1075 | * | |
1076 | * A special case is when the work is being canceled in parallel. | |
1077 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1078 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
1079 | * win and return %false here. The caller is supposed to synchronize these | |
1080 | * operations a reasonable way. | |
1081 | * | |
1082 | * This function is safe to call from any context including IRQ handler. | |
1083 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1084 | * for details. | |
1085 | */ | |
1086 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1087 | struct kthread_delayed_work *dwork, | |
1088 | unsigned long delay) | |
1089 | { | |
1090 | struct kthread_work *work = &dwork->work; | |
1091 | unsigned long flags; | |
1092 | int ret = false; | |
1093 | ||
fe99a4f4 | 1094 | raw_spin_lock_irqsave(&worker->lock, flags); |
9a6b06c8 PM |
1095 | |
1096 | /* Do not bother with canceling when never queued. */ | |
1097 | if (!work->worker) | |
1098 | goto fast_queue; | |
1099 | ||
1100 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1101 | WARN_ON_ONCE(work->worker != worker); | |
1102 | ||
1103 | /* Do not fight with another command that is canceling this work. */ | |
1104 | if (work->canceling) | |
1105 | goto out; | |
1106 | ||
1107 | ret = __kthread_cancel_work(work, true, &flags); | |
1108 | fast_queue: | |
1109 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1110 | out: | |
fe99a4f4 | 1111 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
9a6b06c8 PM |
1112 | return ret; |
1113 | } | |
1114 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1115 | ||
37be45d4 PM |
1116 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1117 | { | |
1118 | struct kthread_worker *worker = work->worker; | |
1119 | unsigned long flags; | |
1120 | int ret = false; | |
1121 | ||
1122 | if (!worker) | |
1123 | goto out; | |
1124 | ||
fe99a4f4 | 1125 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1126 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1127 | WARN_ON_ONCE(work->worker != worker); | |
1128 | ||
1129 | ret = __kthread_cancel_work(work, is_dwork, &flags); | |
1130 | ||
1131 | if (worker->current_work != work) | |
1132 | goto out_fast; | |
1133 | ||
1134 | /* | |
1135 | * The work is in progress and we need to wait with the lock released. | |
1136 | * In the meantime, block any queuing by setting the canceling counter. | |
1137 | */ | |
1138 | work->canceling++; | |
fe99a4f4 | 1139 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 | 1140 | kthread_flush_work(work); |
fe99a4f4 | 1141 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1142 | work->canceling--; |
1143 | ||
1144 | out_fast: | |
fe99a4f4 | 1145 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 PM |
1146 | out: |
1147 | return ret; | |
1148 | } | |
1149 | ||
1150 | /** | |
1151 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1152 | * @work: the kthread work to cancel | |
1153 | * | |
1154 | * Cancel @work and wait for its execution to finish. This function | |
1155 | * can be used even if the work re-queues itself. On return from this | |
1156 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1157 | * | |
1158 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1159 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1160 | * | |
1161 | * The caller must ensure that the worker on which @work was last | |
1162 | * queued can't be destroyed before this function returns. | |
1163 | * | |
1164 | * Return: %true if @work was pending, %false otherwise. | |
1165 | */ | |
1166 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1167 | { | |
1168 | return __kthread_cancel_work_sync(work, false); | |
1169 | } | |
1170 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1171 | ||
1172 | /** | |
1173 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1174 | * wait for it to finish. | |
1175 | * @dwork: the kthread delayed work to cancel | |
1176 | * | |
1177 | * This is kthread_cancel_work_sync() for delayed works. | |
1178 | * | |
1179 | * Return: %true if @dwork was pending, %false otherwise. | |
1180 | */ | |
1181 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1182 | { | |
1183 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1184 | } | |
1185 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1186 | ||
b56c0d89 | 1187 | /** |
3989144f | 1188 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1189 | * @worker: worker to flush |
1190 | * | |
1191 | * Wait until all currently executing or pending works on @worker are | |
1192 | * finished. | |
1193 | */ | |
3989144f | 1194 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1195 | { |
1196 | struct kthread_flush_work fwork = { | |
1197 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1198 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1199 | }; | |
1200 | ||
3989144f | 1201 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1202 | wait_for_completion(&fwork.done); |
1203 | } | |
3989144f | 1204 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1205 | |
1206 | /** | |
1207 | * kthread_destroy_worker - destroy a kthread worker | |
1208 | * @worker: worker to be destroyed | |
1209 | * | |
1210 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1211 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1212 | * machines needed. | |
1213 | */ | |
1214 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1215 | { | |
1216 | struct task_struct *task; | |
1217 | ||
1218 | task = worker->task; | |
1219 | if (WARN_ON(!task)) | |
1220 | return; | |
1221 | ||
1222 | kthread_flush_worker(worker); | |
1223 | kthread_stop(task); | |
1224 | WARN_ON(!list_empty(&worker->work_list)); | |
1225 | kfree(worker); | |
1226 | } | |
1227 | EXPORT_SYMBOL(kthread_destroy_worker); | |
05e3db95 | 1228 | |
f5678e7f CH |
1229 | /** |
1230 | * kthread_use_mm - make the calling kthread operate on an address space | |
1231 | * @mm: address space to operate on | |
9bf5b9eb | 1232 | */ |
f5678e7f | 1233 | void kthread_use_mm(struct mm_struct *mm) |
9bf5b9eb CH |
1234 | { |
1235 | struct mm_struct *active_mm; | |
1236 | struct task_struct *tsk = current; | |
1237 | ||
f5678e7f CH |
1238 | WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
1239 | WARN_ON_ONCE(tsk->mm); | |
1240 | ||
9bf5b9eb CH |
1241 | task_lock(tsk); |
1242 | active_mm = tsk->active_mm; | |
1243 | if (active_mm != mm) { | |
1244 | mmgrab(mm); | |
1245 | tsk->active_mm = mm; | |
1246 | } | |
1247 | tsk->mm = mm; | |
1248 | switch_mm(active_mm, mm, tsk); | |
1249 | task_unlock(tsk); | |
1250 | #ifdef finish_arch_post_lock_switch | |
1251 | finish_arch_post_lock_switch(); | |
1252 | #endif | |
1253 | ||
1254 | if (active_mm != mm) | |
1255 | mmdrop(active_mm); | |
37c54f9b CH |
1256 | |
1257 | to_kthread(tsk)->oldfs = get_fs(); | |
1258 | set_fs(USER_DS); | |
9bf5b9eb | 1259 | } |
f5678e7f | 1260 | EXPORT_SYMBOL_GPL(kthread_use_mm); |
9bf5b9eb | 1261 | |
f5678e7f CH |
1262 | /** |
1263 | * kthread_unuse_mm - reverse the effect of kthread_use_mm() | |
1264 | * @mm: address space to operate on | |
9bf5b9eb | 1265 | */ |
f5678e7f | 1266 | void kthread_unuse_mm(struct mm_struct *mm) |
9bf5b9eb CH |
1267 | { |
1268 | struct task_struct *tsk = current; | |
1269 | ||
f5678e7f CH |
1270 | WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
1271 | WARN_ON_ONCE(!tsk->mm); | |
1272 | ||
37c54f9b CH |
1273 | set_fs(to_kthread(tsk)->oldfs); |
1274 | ||
9bf5b9eb CH |
1275 | task_lock(tsk); |
1276 | sync_mm_rss(mm); | |
1277 | tsk->mm = NULL; | |
1278 | /* active_mm is still 'mm' */ | |
1279 | enter_lazy_tlb(mm, tsk); | |
1280 | task_unlock(tsk); | |
1281 | } | |
f5678e7f | 1282 | EXPORT_SYMBOL_GPL(kthread_unuse_mm); |
9bf5b9eb | 1283 | |
0b508bc9 | 1284 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
1285 | /** |
1286 | * kthread_associate_blkcg - associate blkcg to current kthread | |
1287 | * @css: the cgroup info | |
1288 | * | |
1289 | * Current thread must be a kthread. The thread is running jobs on behalf of | |
1290 | * other threads. In some cases, we expect the jobs attach cgroup info of | |
1291 | * original threads instead of that of current thread. This function stores | |
1292 | * original thread's cgroup info in current kthread context for later | |
1293 | * retrieval. | |
1294 | */ | |
1295 | void kthread_associate_blkcg(struct cgroup_subsys_state *css) | |
1296 | { | |
1297 | struct kthread *kthread; | |
1298 | ||
1299 | if (!(current->flags & PF_KTHREAD)) | |
1300 | return; | |
1301 | kthread = to_kthread(current); | |
1302 | if (!kthread) | |
1303 | return; | |
1304 | ||
1305 | if (kthread->blkcg_css) { | |
1306 | css_put(kthread->blkcg_css); | |
1307 | kthread->blkcg_css = NULL; | |
1308 | } | |
1309 | if (css) { | |
1310 | css_get(css); | |
1311 | kthread->blkcg_css = css; | |
1312 | } | |
1313 | } | |
1314 | EXPORT_SYMBOL(kthread_associate_blkcg); | |
1315 | ||
1316 | /** | |
1317 | * kthread_blkcg - get associated blkcg css of current kthread | |
1318 | * | |
1319 | * Current thread must be a kthread. | |
1320 | */ | |
1321 | struct cgroup_subsys_state *kthread_blkcg(void) | |
1322 | { | |
1323 | struct kthread *kthread; | |
1324 | ||
1325 | if (current->flags & PF_KTHREAD) { | |
1326 | kthread = to_kthread(current); | |
1327 | if (kthread) | |
1328 | return kthread->blkcg_css; | |
1329 | } | |
1330 | return NULL; | |
1331 | } | |
1332 | EXPORT_SYMBOL(kthread_blkcg); | |
1333 | #endif |