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