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