Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* Kernel thread helper functions. |
3 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. | |
9bf5b9eb | 4 | * Copyright (C) 2009 Red Hat, Inc. |
1da177e4 | 5 | * |
73c27992 | 6 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
7 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
8 | * etc.). | |
9 | */ | |
ae7e81c0 | 10 | #include <uapi/linux/sched/types.h> |
9bf5b9eb CH |
11 | #include <linux/mm.h> |
12 | #include <linux/mmu_context.h> | |
1da177e4 | 13 | #include <linux/sched.h> |
9bf5b9eb | 14 | #include <linux/sched/mm.h> |
29930025 | 15 | #include <linux/sched/task.h> |
1da177e4 LT |
16 | #include <linux/kthread.h> |
17 | #include <linux/completion.h> | |
18 | #include <linux/err.h> | |
8af0c18a | 19 | #include <linux/cgroup.h> |
58568d2a | 20 | #include <linux/cpuset.h> |
1da177e4 LT |
21 | #include <linux/unistd.h> |
22 | #include <linux/file.h> | |
9984de1a | 23 | #include <linux/export.h> |
97d1f15b | 24 | #include <linux/mutex.h> |
b56c0d89 TH |
25 | #include <linux/slab.h> |
26 | #include <linux/freezer.h> | |
a74fb73c | 27 | #include <linux/ptrace.h> |
cd42d559 | 28 | #include <linux/uaccess.h> |
98fa15f3 | 29 | #include <linux/numa.h> |
9cc5b865 | 30 | #include <linux/sched/isolation.h> |
ad8d75ff | 31 | #include <trace/events/sched.h> |
1da177e4 | 32 | |
9bf5b9eb | 33 | |
73c27992 EB |
34 | static DEFINE_SPINLOCK(kthread_create_lock); |
35 | static LIST_HEAD(kthread_create_list); | |
36 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
37 | |
38 | struct kthread_create_info | |
39 | { | |
73c27992 | 40 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
41 | int (*threadfn)(void *data); |
42 | void *data; | |
207205a2 | 43 | int node; |
1da177e4 | 44 | |
73c27992 | 45 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 46 | struct task_struct *result; |
786235ee | 47 | struct completion *done; |
65f27f38 | 48 | |
73c27992 | 49 | struct list_head list; |
1da177e4 LT |
50 | }; |
51 | ||
63706172 | 52 | struct kthread { |
2a1d4460 TG |
53 | unsigned long flags; |
54 | unsigned int cpu; | |
6b124879 | 55 | int result; |
52782c92 | 56 | int (*threadfn)(void *); |
82805ab7 | 57 | void *data; |
2a1d4460 | 58 | struct completion parked; |
63706172 | 59 | struct completion exited; |
0b508bc9 | 60 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
61 | struct cgroup_subsys_state *blkcg_css; |
62 | #endif | |
d6986ce2 YS |
63 | /* To store the full name if task comm is truncated. */ |
64 | char *full_name; | |
1da177e4 LT |
65 | }; |
66 | ||
2a1d4460 TG |
67 | enum KTHREAD_BITS { |
68 | KTHREAD_IS_PER_CPU = 0, | |
69 | KTHREAD_SHOULD_STOP, | |
70 | KTHREAD_SHOULD_PARK, | |
2a1d4460 TG |
71 | }; |
72 | ||
4ecdafc8 ON |
73 | static inline struct kthread *to_kthread(struct task_struct *k) |
74 | { | |
1da5c46f | 75 | WARN_ON(!(k->flags & PF_KTHREAD)); |
e32cf5df | 76 | return k->worker_private; |
4ecdafc8 ON |
77 | } |
78 | ||
3a7956e2 PZ |
79 | /* |
80 | * Variant of to_kthread() that doesn't assume @p is a kthread. | |
81 | * | |
82 | * Per construction; when: | |
83 | * | |
e32cf5df | 84 | * (p->flags & PF_KTHREAD) && p->worker_private |
3a7956e2 PZ |
85 | * |
86 | * the task is both a kthread and struct kthread is persistent. However | |
87 | * PF_KTHREAD on it's own is not, kernel_thread() can exec() (See umh.c and | |
88 | * begin_new_exec()). | |
89 | */ | |
90 | static inline struct kthread *__to_kthread(struct task_struct *p) | |
91 | { | |
e32cf5df | 92 | void *kthread = p->worker_private; |
3a7956e2 PZ |
93 | if (kthread && !(p->flags & PF_KTHREAD)) |
94 | kthread = NULL; | |
95 | return kthread; | |
96 | } | |
97 | ||
d6986ce2 YS |
98 | void get_kthread_comm(char *buf, size_t buf_size, struct task_struct *tsk) |
99 | { | |
100 | struct kthread *kthread = to_kthread(tsk); | |
101 | ||
102 | if (!kthread || !kthread->full_name) { | |
103 | __get_task_comm(buf, buf_size, tsk); | |
104 | return; | |
105 | } | |
106 | ||
107 | strscpy_pad(buf, kthread->full_name, buf_size); | |
108 | } | |
109 | ||
40966e31 | 110 | bool set_kthread_struct(struct task_struct *p) |
00b89fe0 VS |
111 | { |
112 | struct kthread *kthread; | |
113 | ||
40966e31 EB |
114 | if (WARN_ON_ONCE(to_kthread(p))) |
115 | return false; | |
00b89fe0 VS |
116 | |
117 | kthread = kzalloc(sizeof(*kthread), GFP_KERNEL); | |
40966e31 EB |
118 | if (!kthread) |
119 | return false; | |
120 | ||
121 | init_completion(&kthread->exited); | |
122 | init_completion(&kthread->parked); | |
123 | p->vfork_done = &kthread->exited; | |
124 | ||
e32cf5df | 125 | p->worker_private = kthread; |
40966e31 | 126 | return true; |
00b89fe0 VS |
127 | } |
128 | ||
1da5c46f ON |
129 | void free_kthread_struct(struct task_struct *k) |
130 | { | |
05e3db95 SL |
131 | struct kthread *kthread; |
132 | ||
1da5c46f | 133 | /* |
40966e31 | 134 | * Can be NULL if kmalloc() in set_kthread_struct() failed. |
1da5c46f | 135 | */ |
05e3db95 | 136 | kthread = to_kthread(k); |
d6986ce2 YS |
137 | if (!kthread) |
138 | return; | |
139 | ||
0b508bc9 | 140 | #ifdef CONFIG_BLK_CGROUP |
d6986ce2 | 141 | WARN_ON_ONCE(kthread->blkcg_css); |
05e3db95 | 142 | #endif |
e32cf5df | 143 | k->worker_private = NULL; |
d6986ce2 | 144 | kfree(kthread->full_name); |
05e3db95 | 145 | kfree(kthread); |
1da5c46f ON |
146 | } |
147 | ||
9e37bd30 RD |
148 | /** |
149 | * kthread_should_stop - should this kthread return now? | |
150 | * | |
72fd4a35 | 151 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
152 | * and this will return true. You should then return, and your return |
153 | * value will be passed through to kthread_stop(). | |
154 | */ | |
2a1d4460 | 155 | bool kthread_should_stop(void) |
1da177e4 | 156 | { |
2a1d4460 | 157 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
158 | } |
159 | EXPORT_SYMBOL(kthread_should_stop); | |
160 | ||
0121805d MK |
161 | bool __kthread_should_park(struct task_struct *k) |
162 | { | |
163 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); | |
164 | } | |
165 | EXPORT_SYMBOL_GPL(__kthread_should_park); | |
166 | ||
2a1d4460 TG |
167 | /** |
168 | * kthread_should_park - should this kthread park now? | |
169 | * | |
170 | * When someone calls kthread_park() on your kthread, it will be woken | |
171 | * and this will return true. You should then do the necessary | |
172 | * cleanup and call kthread_parkme() | |
173 | * | |
174 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
175 | * and in a park position. kthread_unpark() "restarts" the thread and | |
176 | * calls the thread function again. | |
177 | */ | |
178 | bool kthread_should_park(void) | |
179 | { | |
0121805d | 180 | return __kthread_should_park(current); |
2a1d4460 | 181 | } |
18896451 | 182 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 183 | |
8a32c441 TH |
184 | /** |
185 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
186 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
187 | * | |
188 | * kthread_should_stop() for freezable kthreads, which will enter | |
189 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
190 | * freezer deadlock and freezable kthreads should use this function instead | |
191 | * of calling try_to_freeze() directly. | |
192 | */ | |
193 | bool kthread_freezable_should_stop(bool *was_frozen) | |
194 | { | |
195 | bool frozen = false; | |
196 | ||
197 | might_sleep(); | |
198 | ||
199 | if (unlikely(freezing(current))) | |
200 | frozen = __refrigerator(true); | |
201 | ||
202 | if (was_frozen) | |
203 | *was_frozen = frozen; | |
204 | ||
205 | return kthread_should_stop(); | |
206 | } | |
207 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
208 | ||
52782c92 BF |
209 | /** |
210 | * kthread_func - return the function specified on kthread creation | |
211 | * @task: kthread task in question | |
212 | * | |
213 | * Returns NULL if the task is not a kthread. | |
214 | */ | |
215 | void *kthread_func(struct task_struct *task) | |
216 | { | |
3a7956e2 PZ |
217 | struct kthread *kthread = __to_kthread(task); |
218 | if (kthread) | |
219 | return kthread->threadfn; | |
52782c92 BF |
220 | return NULL; |
221 | } | |
222 | EXPORT_SYMBOL_GPL(kthread_func); | |
223 | ||
82805ab7 TH |
224 | /** |
225 | * kthread_data - return data value specified on kthread creation | |
226 | * @task: kthread task in question | |
227 | * | |
228 | * Return the data value specified when kthread @task was created. | |
229 | * The caller is responsible for ensuring the validity of @task when | |
230 | * calling this function. | |
231 | */ | |
232 | void *kthread_data(struct task_struct *task) | |
233 | { | |
234 | return to_kthread(task)->data; | |
235 | } | |
52782c92 | 236 | EXPORT_SYMBOL_GPL(kthread_data); |
82805ab7 | 237 | |
cd42d559 | 238 | /** |
e700591a | 239 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
240 | * @task: possible kthread task in question |
241 | * | |
242 | * @task could be a kthread task. Return the data value specified when it | |
243 | * was created if accessible. If @task isn't a kthread task or its data is | |
244 | * inaccessible for any reason, %NULL is returned. This function requires | |
245 | * that @task itself is safe to dereference. | |
246 | */ | |
e700591a | 247 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 | 248 | { |
3a7956e2 | 249 | struct kthread *kthread = __to_kthread(task); |
cd42d559 TH |
250 | void *data = NULL; |
251 | ||
3a7956e2 PZ |
252 | if (kthread) |
253 | copy_from_kernel_nofault(&data, &kthread->data, sizeof(data)); | |
cd42d559 TH |
254 | return data; |
255 | } | |
256 | ||
2a1d4460 TG |
257 | static void __kthread_parkme(struct kthread *self) |
258 | { | |
741a76b3 | 259 | for (;;) { |
1cef1150 PZ |
260 | /* |
261 | * TASK_PARKED is a special state; we must serialize against | |
262 | * possible pending wakeups to avoid store-store collisions on | |
263 | * task->state. | |
264 | * | |
265 | * Such a collision might possibly result in the task state | |
266 | * changin from TASK_PARKED and us failing the | |
267 | * wait_task_inactive() in kthread_park(). | |
268 | */ | |
269 | set_special_state(TASK_PARKED); | |
741a76b3 PZ |
270 | if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) |
271 | break; | |
1cef1150 | 272 | |
26c7295b LC |
273 | /* |
274 | * Thread is going to call schedule(), do not preempt it, | |
275 | * or the caller of kthread_park() may spend more time in | |
276 | * wait_task_inactive(). | |
277 | */ | |
278 | preempt_disable(); | |
f83ee19b | 279 | complete(&self->parked); |
26c7295b LC |
280 | schedule_preempt_disabled(); |
281 | preempt_enable(); | |
2a1d4460 | 282 | } |
2a1d4460 TG |
283 | __set_current_state(TASK_RUNNING); |
284 | } | |
285 | ||
286 | void kthread_parkme(void) | |
287 | { | |
288 | __kthread_parkme(to_kthread(current)); | |
289 | } | |
18896451 | 290 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 291 | |
bbda86e9 EB |
292 | /** |
293 | * kthread_exit - Cause the current kthread return @result to kthread_stop(). | |
294 | * @result: The integer value to return to kthread_stop(). | |
295 | * | |
296 | * While kthread_exit can be called directly, it exists so that | |
297 | * functions which do some additional work in non-modular code such as | |
298 | * module_put_and_kthread_exit can be implemented. | |
299 | * | |
300 | * Does not return. | |
301 | */ | |
302 | void __noreturn kthread_exit(long result) | |
303 | { | |
6b124879 EB |
304 | struct kthread *kthread = to_kthread(current); |
305 | kthread->result = result; | |
306 | do_exit(0); | |
bbda86e9 EB |
307 | } |
308 | ||
cead1855 | 309 | /** |
5eb6f228 | 310 | * kthread_complete_and_exit - Exit the current kthread. |
cead1855 EB |
311 | * @comp: Completion to complete |
312 | * @code: The integer value to return to kthread_stop(). | |
313 | * | |
314 | * If present complete @comp and the reuturn code to kthread_stop(). | |
315 | * | |
316 | * A kernel thread whose module may be removed after the completion of | |
317 | * @comp can use this function exit safely. | |
318 | * | |
319 | * Does not return. | |
320 | */ | |
321 | void __noreturn kthread_complete_and_exit(struct completion *comp, long code) | |
322 | { | |
323 | if (comp) | |
324 | complete(comp); | |
325 | ||
326 | kthread_exit(code); | |
327 | } | |
328 | EXPORT_SYMBOL(kthread_complete_and_exit); | |
329 | ||
1da177e4 LT |
330 | static int kthread(void *_create) |
331 | { | |
1a7243ca | 332 | static const struct sched_param param = { .sched_priority = 0 }; |
63706172 | 333 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 334 | struct kthread_create_info *create = _create; |
63706172 ON |
335 | int (*threadfn)(void *data) = create->threadfn; |
336 | void *data = create->data; | |
786235ee | 337 | struct completion *done; |
1da5c46f | 338 | struct kthread *self; |
63706172 | 339 | int ret; |
1da177e4 | 340 | |
00b89fe0 | 341 | self = to_kthread(current); |
1da177e4 | 342 | |
d25c83c6 | 343 | /* Release the structure when caller killed by a fatal signal. */ |
786235ee TH |
344 | done = xchg(&create->done, NULL); |
345 | if (!done) { | |
346 | kfree(create); | |
bbda86e9 | 347 | kthread_exit(-EINTR); |
1da5c46f ON |
348 | } |
349 | ||
52782c92 | 350 | self->threadfn = threadfn; |
1da5c46f | 351 | self->data = data; |
1da5c46f | 352 | |
1a7243ca SAS |
353 | /* |
354 | * The new thread inherited kthreadd's priority and CPU mask. Reset | |
355 | * back to default in case they have been changed. | |
356 | */ | |
357 | sched_setscheduler_nocheck(current, SCHED_NORMAL, ¶m); | |
04d4e665 | 358 | set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_TYPE_KTHREAD)); |
1a7243ca | 359 | |
1da177e4 | 360 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 361 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 362 | create->result = current; |
26c7295b LC |
363 | /* |
364 | * Thread is going to call schedule(), do not preempt it, | |
365 | * or the creator may spend more time in wait_task_inactive(). | |
366 | */ | |
367 | preempt_disable(); | |
786235ee | 368 | complete(done); |
26c7295b LC |
369 | schedule_preempt_disabled(); |
370 | preempt_enable(); | |
1da177e4 | 371 | |
63706172 | 372 | ret = -EINTR; |
1da5c46f | 373 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
77f88796 | 374 | cgroup_kthread_ready(); |
1da5c46f | 375 | __kthread_parkme(self); |
2a1d4460 TG |
376 | ret = threadfn(data); |
377 | } | |
bbda86e9 | 378 | kthread_exit(ret); |
1da177e4 LT |
379 | } |
380 | ||
cb5021ca | 381 | /* called from kernel_clone() to get node information for about to be created task */ |
207205a2 ED |
382 | int tsk_fork_get_node(struct task_struct *tsk) |
383 | { | |
384 | #ifdef CONFIG_NUMA | |
385 | if (tsk == kthreadd_task) | |
386 | return tsk->pref_node_fork; | |
387 | #endif | |
81c98869 | 388 | return NUMA_NO_NODE; |
207205a2 ED |
389 | } |
390 | ||
73c27992 | 391 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 392 | { |
1da177e4 LT |
393 | int pid; |
394 | ||
207205a2 ED |
395 | #ifdef CONFIG_NUMA |
396 | current->pref_node_fork = create->node; | |
397 | #endif | |
1da177e4 LT |
398 | /* We want our own signal handler (we take no signals by default). */ |
399 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 400 | if (pid < 0) { |
d25c83c6 | 401 | /* Release the structure when caller killed by a fatal signal. */ |
786235ee TH |
402 | struct completion *done = xchg(&create->done, NULL); |
403 | ||
404 | if (!done) { | |
405 | kfree(create); | |
406 | return; | |
407 | } | |
1da177e4 | 408 | create->result = ERR_PTR(pid); |
786235ee | 409 | complete(done); |
cdd140bd | 410 | } |
1da177e4 LT |
411 | } |
412 | ||
c0b942a7 NI |
413 | static __printf(4, 0) |
414 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
415 | void *data, int node, |
416 | const char namefmt[], | |
417 | va_list args) | |
1da177e4 | 418 | { |
786235ee TH |
419 | DECLARE_COMPLETION_ONSTACK(done); |
420 | struct task_struct *task; | |
421 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
422 | GFP_KERNEL); | |
423 | ||
424 | if (!create) | |
425 | return ERR_PTR(-ENOMEM); | |
426 | create->threadfn = threadfn; | |
427 | create->data = data; | |
428 | create->node = node; | |
429 | create->done = &done; | |
73c27992 EB |
430 | |
431 | spin_lock(&kthread_create_lock); | |
786235ee | 432 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
433 | spin_unlock(&kthread_create_lock); |
434 | ||
cbd9b67b | 435 | wake_up_process(kthreadd_task); |
786235ee TH |
436 | /* |
437 | * Wait for completion in killable state, for I might be chosen by | |
438 | * the OOM killer while kthreadd is trying to allocate memory for | |
439 | * new kernel thread. | |
440 | */ | |
441 | if (unlikely(wait_for_completion_killable(&done))) { | |
442 | /* | |
d25c83c6 PM |
443 | * If I was killed by a fatal signal before kthreadd (or new |
444 | * kernel thread) calls complete(), leave the cleanup of this | |
445 | * structure to that thread. | |
786235ee TH |
446 | */ |
447 | if (xchg(&create->done, NULL)) | |
8fe6929c | 448 | return ERR_PTR(-EINTR); |
786235ee TH |
449 | /* |
450 | * kthreadd (or new kernel thread) will call complete() | |
451 | * shortly. | |
452 | */ | |
453 | wait_for_completion(&done); | |
454 | } | |
455 | task = create->result; | |
456 | if (!IS_ERR(task)) { | |
3e536e22 | 457 | char name[TASK_COMM_LEN]; |
d6986ce2 YS |
458 | va_list aq; |
459 | int len; | |
1c99315b | 460 | |
3e536e22 SD |
461 | /* |
462 | * task is already visible to other tasks, so updating | |
463 | * COMM must be protected. | |
464 | */ | |
d6986ce2 YS |
465 | va_copy(aq, args); |
466 | len = vsnprintf(name, sizeof(name), namefmt, aq); | |
467 | va_end(aq); | |
468 | if (len >= TASK_COMM_LEN) { | |
469 | struct kthread *kthread = to_kthread(task); | |
470 | ||
471 | /* leave it truncated when out of memory. */ | |
472 | kthread->full_name = kvasprintf(GFP_KERNEL, namefmt, args); | |
473 | } | |
3e536e22 | 474 | set_task_comm(task, name); |
1da177e4 | 475 | } |
786235ee TH |
476 | kfree(create); |
477 | return task; | |
1da177e4 | 478 | } |
255451e4 PM |
479 | |
480 | /** | |
481 | * kthread_create_on_node - create a kthread. | |
482 | * @threadfn: the function to run until signal_pending(current). | |
483 | * @data: data ptr for @threadfn. | |
484 | * @node: task and thread structures for the thread are allocated on this node | |
485 | * @namefmt: printf-style name for the thread. | |
486 | * | |
487 | * Description: This helper function creates and names a kernel | |
488 | * thread. The thread will be stopped: use wake_up_process() to start | |
489 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
490 | * is affine to all CPUs. | |
491 | * | |
492 | * If thread is going to be bound on a particular cpu, give its node | |
493 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
494 | * When woken, the thread will run @threadfn() with @data as its | |
111e7049 | 495 | * argument. @threadfn() can either return directly if it is a |
255451e4 PM |
496 | * standalone thread for which no one will call kthread_stop(), or |
497 | * return when 'kthread_should_stop()' is true (which means | |
498 | * kthread_stop() has been called). The return value should be zero | |
499 | * or a negative error number; it will be passed to kthread_stop(). | |
500 | * | |
501 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
502 | */ | |
503 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
504 | void *data, int node, | |
505 | const char namefmt[], | |
506 | ...) | |
507 | { | |
508 | struct task_struct *task; | |
509 | va_list args; | |
510 | ||
511 | va_start(args, namefmt); | |
512 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
513 | va_end(args); | |
514 | ||
515 | return task; | |
516 | } | |
207205a2 | 517 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 518 | |
2f064a59 | 519 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, unsigned int state) |
2a1d4460 | 520 | { |
25834c73 PZ |
521 | unsigned long flags; |
522 | ||
f2530dc7 TG |
523 | if (!wait_task_inactive(p, state)) { |
524 | WARN_ON(1); | |
525 | return; | |
526 | } | |
25834c73 | 527 | |
2a1d4460 | 528 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
529 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
530 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 531 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
532 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
533 | } | |
534 | ||
2f064a59 | 535 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, unsigned int state) |
25834c73 PZ |
536 | { |
537 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
538 | } | |
539 | ||
540 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
541 | { | |
542 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
543 | } |
544 | ||
881232b7 PZ |
545 | /** |
546 | * kthread_bind - bind a just-created kthread to a cpu. | |
547 | * @p: thread created by kthread_create(). | |
548 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
549 | * | |
550 | * Description: This function is equivalent to set_cpus_allowed(), | |
551 | * except that @cpu doesn't need to be online, and the thread must be | |
552 | * stopped (i.e., just returned from kthread_create()). | |
553 | */ | |
554 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
555 | { | |
f2530dc7 | 556 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
557 | } |
558 | EXPORT_SYMBOL(kthread_bind); | |
559 | ||
2a1d4460 TG |
560 | /** |
561 | * kthread_create_on_cpu - Create a cpu bound kthread | |
562 | * @threadfn: the function to run until signal_pending(current). | |
563 | * @data: data ptr for @threadfn. | |
564 | * @cpu: The cpu on which the thread should be bound, | |
565 | * @namefmt: printf-style name for the thread. Format is restricted | |
566 | * to "name.*%u". Code fills in cpu number. | |
567 | * | |
568 | * Description: This helper function creates and names a kernel thread | |
2a1d4460 TG |
569 | */ |
570 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
571 | void *data, unsigned int cpu, | |
572 | const char *namefmt) | |
573 | { | |
574 | struct task_struct *p; | |
575 | ||
10922838 | 576 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
577 | cpu); |
578 | if (IS_ERR(p)) | |
579 | return p; | |
a65d4096 PM |
580 | kthread_bind(p, cpu); |
581 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 | 582 | to_kthread(p)->cpu = cpu; |
2a1d4460 TG |
583 | return p; |
584 | } | |
800977f6 | 585 | EXPORT_SYMBOL(kthread_create_on_cpu); |
2a1d4460 | 586 | |
ac687e6e PZ |
587 | void kthread_set_per_cpu(struct task_struct *k, int cpu) |
588 | { | |
589 | struct kthread *kthread = to_kthread(k); | |
590 | if (!kthread) | |
591 | return; | |
592 | ||
593 | WARN_ON_ONCE(!(k->flags & PF_NO_SETAFFINITY)); | |
594 | ||
595 | if (cpu < 0) { | |
596 | clear_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
597 | return; | |
598 | } | |
599 | ||
600 | kthread->cpu = cpu; | |
601 | set_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
602 | } | |
603 | ||
3a7956e2 | 604 | bool kthread_is_per_cpu(struct task_struct *p) |
ac687e6e | 605 | { |
3a7956e2 | 606 | struct kthread *kthread = __to_kthread(p); |
ac687e6e PZ |
607 | if (!kthread) |
608 | return false; | |
609 | ||
610 | return test_bit(KTHREAD_IS_PER_CPU, &kthread->flags); | |
611 | } | |
612 | ||
cf380a4a ON |
613 | /** |
614 | * kthread_unpark - unpark a thread created by kthread_create(). | |
615 | * @k: thread created by kthread_create(). | |
616 | * | |
617 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
618 | * waits for it to return. If the thread is marked percpu then its | |
619 | * bound to the cpu again. | |
620 | */ | |
621 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 622 | { |
cf380a4a ON |
623 | struct kthread *kthread = to_kthread(k); |
624 | ||
f2530dc7 | 625 | /* |
85f1abe0 PZ |
626 | * Newly created kthread was parked when the CPU was offline. |
627 | * The binding was lost and we need to set it again. | |
f2530dc7 | 628 | */ |
85f1abe0 PZ |
629 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
630 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
631 | ||
632 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
1cef1150 PZ |
633 | /* |
634 | * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. | |
635 | */ | |
85f1abe0 | 636 | wake_up_state(k, TASK_PARKED); |
f2530dc7 | 637 | } |
18896451 | 638 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
639 | |
640 | /** | |
641 | * kthread_park - park a thread created by kthread_create(). | |
642 | * @k: thread created by kthread_create(). | |
643 | * | |
644 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
645 | * waits for it to return. This can also be called after kthread_create() | |
646 | * instead of calling wake_up_process(): the thread will park without | |
647 | * calling threadfn(). | |
648 | * | |
649 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
650 | * If called by the kthread itself just the park bit is set. | |
651 | */ | |
652 | int kthread_park(struct task_struct *k) | |
653 | { | |
cf380a4a ON |
654 | struct kthread *kthread = to_kthread(k); |
655 | ||
656 | if (WARN_ON(k->flags & PF_EXITING)) | |
657 | return -ENOSYS; | |
658 | ||
f83ee19b PZ |
659 | if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) |
660 | return -EBUSY; | |
661 | ||
85f1abe0 PZ |
662 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
663 | if (k != current) { | |
664 | wake_up_process(k); | |
1cef1150 PZ |
665 | /* |
666 | * Wait for __kthread_parkme() to complete(), this means we | |
667 | * _will_ have TASK_PARKED and are about to call schedule(). | |
668 | */ | |
85f1abe0 | 669 | wait_for_completion(&kthread->parked); |
1cef1150 PZ |
670 | /* |
671 | * Now wait for that schedule() to complete and the task to | |
672 | * get scheduled out. | |
673 | */ | |
674 | WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED)); | |
2a1d4460 | 675 | } |
cf380a4a ON |
676 | |
677 | return 0; | |
2a1d4460 | 678 | } |
18896451 | 679 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 680 | |
9e37bd30 RD |
681 | /** |
682 | * kthread_stop - stop a thread created by kthread_create(). | |
683 | * @k: thread created by kthread_create(). | |
684 | * | |
685 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
686 | * waits for it to exit. This can also be called after kthread_create() |
687 | * instead of calling wake_up_process(): the thread will exit without | |
688 | * calling threadfn(). | |
689 | * | |
bbda86e9 | 690 | * If threadfn() may call kthread_exit() itself, the caller must ensure |
9ae26027 | 691 | * task_struct can't go away. |
9e37bd30 RD |
692 | * |
693 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
694 | * was never called. | |
695 | */ | |
1da177e4 LT |
696 | int kthread_stop(struct task_struct *k) |
697 | { | |
b5c5442b | 698 | struct kthread *kthread; |
1da177e4 LT |
699 | int ret; |
700 | ||
0a16b607 | 701 | trace_sched_kthread_stop(k); |
b5c5442b ON |
702 | |
703 | get_task_struct(k); | |
efb29fbf ON |
704 | kthread = to_kthread(k); |
705 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 706 | kthread_unpark(k); |
a7c01fa9 | 707 | set_tsk_thread_flag(k, TIF_NOTIFY_SIGNAL); |
efb29fbf ON |
708 | wake_up_process(k); |
709 | wait_for_completion(&kthread->exited); | |
6b124879 | 710 | ret = kthread->result; |
1da177e4 | 711 | put_task_struct(k); |
0a16b607 | 712 | |
b5c5442b | 713 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
714 | return ret; |
715 | } | |
52e92e57 | 716 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 717 | |
e804a4a4 | 718 | int kthreadd(void *unused) |
1da177e4 | 719 | { |
73c27992 | 720 | struct task_struct *tsk = current; |
1da177e4 | 721 | |
e804a4a4 | 722 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 723 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 724 | ignore_signals(tsk); |
04d4e665 | 725 | set_cpus_allowed_ptr(tsk, housekeeping_cpumask(HK_TYPE_KTHREAD)); |
aee4faa4 | 726 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 727 | |
34b087e4 | 728 | current->flags |= PF_NOFREEZE; |
77f88796 | 729 | cgroup_init_kthreadd(); |
73c27992 EB |
730 | |
731 | for (;;) { | |
732 | set_current_state(TASK_INTERRUPTIBLE); | |
733 | if (list_empty(&kthread_create_list)) | |
734 | schedule(); | |
735 | __set_current_state(TASK_RUNNING); | |
736 | ||
737 | spin_lock(&kthread_create_lock); | |
738 | while (!list_empty(&kthread_create_list)) { | |
739 | struct kthread_create_info *create; | |
740 | ||
741 | create = list_entry(kthread_create_list.next, | |
742 | struct kthread_create_info, list); | |
743 | list_del_init(&create->list); | |
744 | spin_unlock(&kthread_create_lock); | |
745 | ||
746 | create_kthread(create); | |
747 | ||
748 | spin_lock(&kthread_create_lock); | |
749 | } | |
750 | spin_unlock(&kthread_create_lock); | |
751 | } | |
752 | ||
753 | return 0; | |
754 | } | |
b56c0d89 | 755 | |
3989144f | 756 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
757 | const char *name, |
758 | struct lock_class_key *key) | |
759 | { | |
dbf52682 | 760 | memset(worker, 0, sizeof(struct kthread_worker)); |
fe99a4f4 | 761 | raw_spin_lock_init(&worker->lock); |
4f32e9b1 YZ |
762 | lockdep_set_class_and_name(&worker->lock, key, name); |
763 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 764 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 765 | } |
3989144f | 766 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 767 | |
b56c0d89 TH |
768 | /** |
769 | * kthread_worker_fn - kthread function to process kthread_worker | |
770 | * @worker_ptr: pointer to initialized kthread_worker | |
771 | * | |
fbae2d44 PM |
772 | * This function implements the main cycle of kthread worker. It processes |
773 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
774 | * is empty. | |
b56c0d89 | 775 | * |
fbae2d44 PM |
776 | * The works are not allowed to keep any locks, disable preemption or interrupts |
777 | * when they finish. There is defined a safe point for freezing when one work | |
778 | * finishes and before a new one is started. | |
8197b3d4 PM |
779 | * |
780 | * Also the works must not be handled by more than one worker at the same time, | |
781 | * see also kthread_queue_work(). | |
b56c0d89 TH |
782 | */ |
783 | int kthread_worker_fn(void *worker_ptr) | |
784 | { | |
785 | struct kthread_worker *worker = worker_ptr; | |
786 | struct kthread_work *work; | |
787 | ||
fbae2d44 PM |
788 | /* |
789 | * FIXME: Update the check and remove the assignment when all kthread | |
790 | * worker users are created using kthread_create_worker*() functions. | |
791 | */ | |
792 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 793 | worker->task = current; |
dbf52682 PM |
794 | |
795 | if (worker->flags & KTW_FREEZABLE) | |
796 | set_freezable(); | |
797 | ||
b56c0d89 TH |
798 | repeat: |
799 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
800 | ||
801 | if (kthread_should_stop()) { | |
802 | __set_current_state(TASK_RUNNING); | |
fe99a4f4 | 803 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 | 804 | worker->task = NULL; |
fe99a4f4 | 805 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
806 | return 0; |
807 | } | |
808 | ||
809 | work = NULL; | |
fe99a4f4 | 810 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 TH |
811 | if (!list_empty(&worker->work_list)) { |
812 | work = list_first_entry(&worker->work_list, | |
813 | struct kthread_work, node); | |
814 | list_del_init(&work->node); | |
815 | } | |
46f3d976 | 816 | worker->current_work = work; |
fe99a4f4 | 817 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
818 | |
819 | if (work) { | |
f630c7c6 | 820 | kthread_work_func_t func = work->func; |
b56c0d89 | 821 | __set_current_state(TASK_RUNNING); |
f630c7c6 | 822 | trace_sched_kthread_work_execute_start(work); |
b56c0d89 | 823 | work->func(work); |
f630c7c6 RC |
824 | /* |
825 | * Avoid dereferencing work after this point. The trace | |
826 | * event only cares about the address. | |
827 | */ | |
828 | trace_sched_kthread_work_execute_end(work, func); | |
b56c0d89 TH |
829 | } else if (!freezing(current)) |
830 | schedule(); | |
831 | ||
832 | try_to_freeze(); | |
22cf8bc6 | 833 | cond_resched(); |
b56c0d89 TH |
834 | goto repeat; |
835 | } | |
836 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
837 | ||
c0b942a7 | 838 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
839 | __kthread_create_worker(int cpu, unsigned int flags, |
840 | const char namefmt[], va_list args) | |
fbae2d44 PM |
841 | { |
842 | struct kthread_worker *worker; | |
843 | struct task_struct *task; | |
98fa15f3 | 844 | int node = NUMA_NO_NODE; |
fbae2d44 PM |
845 | |
846 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
847 | if (!worker) | |
848 | return ERR_PTR(-ENOMEM); | |
849 | ||
850 | kthread_init_worker(worker); | |
851 | ||
8fb9dcbd ON |
852 | if (cpu >= 0) |
853 | node = cpu_to_node(cpu); | |
fbae2d44 | 854 | |
8fb9dcbd ON |
855 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
856 | node, namefmt, args); | |
fbae2d44 PM |
857 | if (IS_ERR(task)) |
858 | goto fail_task; | |
859 | ||
8fb9dcbd ON |
860 | if (cpu >= 0) |
861 | kthread_bind(task, cpu); | |
862 | ||
dbf52682 | 863 | worker->flags = flags; |
fbae2d44 PM |
864 | worker->task = task; |
865 | wake_up_process(task); | |
866 | return worker; | |
867 | ||
868 | fail_task: | |
869 | kfree(worker); | |
870 | return ERR_CAST(task); | |
871 | } | |
872 | ||
873 | /** | |
874 | * kthread_create_worker - create a kthread worker | |
dbf52682 | 875 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
876 | * @namefmt: printf-style name for the kthread worker (task). |
877 | * | |
878 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
879 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
d25c83c6 | 880 | * when the caller was killed by a fatal signal. |
fbae2d44 PM |
881 | */ |
882 | struct kthread_worker * | |
dbf52682 | 883 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
884 | { |
885 | struct kthread_worker *worker; | |
886 | va_list args; | |
887 | ||
888 | va_start(args, namefmt); | |
dbf52682 | 889 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
890 | va_end(args); |
891 | ||
892 | return worker; | |
893 | } | |
894 | EXPORT_SYMBOL(kthread_create_worker); | |
895 | ||
896 | /** | |
897 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
7b7b8a2c | 898 | * to a given CPU and the associated NUMA node. |
fbae2d44 | 899 | * @cpu: CPU number |
dbf52682 | 900 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
901 | * @namefmt: printf-style name for the kthread worker (task). |
902 | * | |
903 | * Use a valid CPU number if you want to bind the kthread worker | |
904 | * to the given CPU and the associated NUMA node. | |
905 | * | |
906 | * A good practice is to add the cpu number also into the worker name. | |
907 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
908 | * | |
ebb2bdce PM |
909 | * CPU hotplug: |
910 | * The kthread worker API is simple and generic. It just provides a way | |
911 | * to create, use, and destroy workers. | |
912 | * | |
913 | * It is up to the API user how to handle CPU hotplug. They have to decide | |
914 | * how to handle pending work items, prevent queuing new ones, and | |
915 | * restore the functionality when the CPU goes off and on. There are a | |
916 | * few catches: | |
917 | * | |
918 | * - CPU affinity gets lost when it is scheduled on an offline CPU. | |
919 | * | |
920 | * - The worker might not exist when the CPU was off when the user | |
921 | * created the workers. | |
922 | * | |
923 | * Good practice is to implement two CPU hotplug callbacks and to | |
924 | * destroy/create the worker when the CPU goes down/up. | |
925 | * | |
926 | * Return: | |
927 | * The pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
fbae2d44 | 928 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) |
d25c83c6 | 929 | * when the caller was killed by a fatal signal. |
fbae2d44 PM |
930 | */ |
931 | struct kthread_worker * | |
dbf52682 PM |
932 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
933 | const char namefmt[], ...) | |
fbae2d44 PM |
934 | { |
935 | struct kthread_worker *worker; | |
936 | va_list args; | |
937 | ||
938 | va_start(args, namefmt); | |
dbf52682 | 939 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
940 | va_end(args); |
941 | ||
942 | return worker; | |
943 | } | |
944 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
945 | ||
37be45d4 PM |
946 | /* |
947 | * Returns true when the work could not be queued at the moment. | |
948 | * It happens when it is already pending in a worker list | |
949 | * or when it is being cancelled. | |
950 | */ | |
951 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
952 | struct kthread_work *work) | |
953 | { | |
954 | lockdep_assert_held(&worker->lock); | |
955 | ||
956 | return !list_empty(&work->node) || work->canceling; | |
957 | } | |
958 | ||
8197b3d4 PM |
959 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
960 | struct kthread_work *work) | |
961 | { | |
962 | lockdep_assert_held(&worker->lock); | |
963 | WARN_ON_ONCE(!list_empty(&work->node)); | |
964 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
965 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
966 | } | |
967 | ||
9a2e03d8 | 968 | /* insert @work before @pos in @worker */ |
3989144f | 969 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
970 | struct kthread_work *work, |
971 | struct list_head *pos) | |
9a2e03d8 | 972 | { |
8197b3d4 | 973 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 | 974 | |
f630c7c6 RC |
975 | trace_sched_kthread_work_queue_work(worker, work); |
976 | ||
9a2e03d8 | 977 | list_add_tail(&work->node, pos); |
46f3d976 | 978 | work->worker = worker; |
ed1403ec | 979 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
980 | wake_up_process(worker->task); |
981 | } | |
982 | ||
b56c0d89 | 983 | /** |
3989144f | 984 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
985 | * @worker: target kthread_worker |
986 | * @work: kthread_work to queue | |
987 | * | |
988 | * Queue @work to work processor @task for async execution. @task | |
989 | * must have been created with kthread_worker_create(). Returns %true | |
990 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
991 | * |
992 | * Reinitialize the work if it needs to be used by another worker. | |
993 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 994 | */ |
3989144f | 995 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
996 | struct kthread_work *work) |
997 | { | |
998 | bool ret = false; | |
999 | unsigned long flags; | |
1000 | ||
fe99a4f4 | 1001 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 | 1002 | if (!queuing_blocked(worker, work)) { |
3989144f | 1003 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
1004 | ret = true; |
1005 | } | |
fe99a4f4 | 1006 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
b56c0d89 TH |
1007 | return ret; |
1008 | } | |
3989144f | 1009 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 1010 | |
22597dc3 PM |
1011 | /** |
1012 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
1013 | * delayed work when the timer expires. | |
fe5c3b69 | 1014 | * @t: pointer to the expired timer |
22597dc3 PM |
1015 | * |
1016 | * The format of the function is defined by struct timer_list. | |
1017 | * It should have been called from irqsafe timer with irq already off. | |
1018 | */ | |
fe5c3b69 | 1019 | void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3 | 1020 | { |
fe5c3b69 | 1021 | struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3 PM |
1022 | struct kthread_work *work = &dwork->work; |
1023 | struct kthread_worker *worker = work->worker; | |
ad01423a | 1024 | unsigned long flags; |
22597dc3 PM |
1025 | |
1026 | /* | |
1027 | * This might happen when a pending work is reinitialized. | |
1028 | * It means that it is used a wrong way. | |
1029 | */ | |
1030 | if (WARN_ON_ONCE(!worker)) | |
1031 | return; | |
1032 | ||
ad01423a | 1033 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 PM |
1034 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1035 | WARN_ON_ONCE(work->worker != worker); | |
1036 | ||
1037 | /* Move the work from worker->delayed_work_list. */ | |
1038 | WARN_ON_ONCE(list_empty(&work->node)); | |
1039 | list_del_init(&work->node); | |
6993d0fd Z |
1040 | if (!work->canceling) |
1041 | kthread_insert_work(worker, work, &worker->work_list); | |
22597dc3 | 1042 | |
ad01423a | 1043 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
1044 | } |
1045 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
1046 | ||
bc88f85c BD |
1047 | static void __kthread_queue_delayed_work(struct kthread_worker *worker, |
1048 | struct kthread_delayed_work *dwork, | |
1049 | unsigned long delay) | |
22597dc3 PM |
1050 | { |
1051 | struct timer_list *timer = &dwork->timer; | |
1052 | struct kthread_work *work = &dwork->work; | |
1053 | ||
4b243563 | 1054 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3 PM |
1055 | |
1056 | /* | |
1057 | * If @delay is 0, queue @dwork->work immediately. This is for | |
1058 | * both optimization and correctness. The earliest @timer can | |
1059 | * expire is on the closest next tick and delayed_work users depend | |
1060 | * on that there's no such delay when @delay is 0. | |
1061 | */ | |
1062 | if (!delay) { | |
1063 | kthread_insert_work(worker, work, &worker->work_list); | |
1064 | return; | |
1065 | } | |
1066 | ||
1067 | /* Be paranoid and try to detect possible races already now. */ | |
1068 | kthread_insert_work_sanity_check(worker, work); | |
1069 | ||
1070 | list_add(&work->node, &worker->delayed_work_list); | |
1071 | work->worker = worker; | |
22597dc3 PM |
1072 | timer->expires = jiffies + delay; |
1073 | add_timer(timer); | |
1074 | } | |
1075 | ||
1076 | /** | |
1077 | * kthread_queue_delayed_work - queue the associated kthread work | |
1078 | * after a delay. | |
1079 | * @worker: target kthread_worker | |
1080 | * @dwork: kthread_delayed_work to queue | |
1081 | * @delay: number of jiffies to wait before queuing | |
1082 | * | |
1083 | * If the work has not been pending it starts a timer that will queue | |
1084 | * the work after the given @delay. If @delay is zero, it queues the | |
1085 | * work immediately. | |
1086 | * | |
1087 | * Return: %false if the @work has already been pending. It means that | |
1088 | * either the timer was running or the work was queued. It returns %true | |
1089 | * otherwise. | |
1090 | */ | |
1091 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
1092 | struct kthread_delayed_work *dwork, | |
1093 | unsigned long delay) | |
1094 | { | |
1095 | struct kthread_work *work = &dwork->work; | |
1096 | unsigned long flags; | |
1097 | bool ret = false; | |
1098 | ||
fe99a4f4 | 1099 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 | 1100 | |
37be45d4 | 1101 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
1102 | __kthread_queue_delayed_work(worker, dwork, delay); |
1103 | ret = true; | |
1104 | } | |
1105 | ||
fe99a4f4 | 1106 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
1107 | return ret; |
1108 | } | |
1109 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
1110 | ||
9a2e03d8 TH |
1111 | struct kthread_flush_work { |
1112 | struct kthread_work work; | |
1113 | struct completion done; | |
1114 | }; | |
1115 | ||
1116 | static void kthread_flush_work_fn(struct kthread_work *work) | |
1117 | { | |
1118 | struct kthread_flush_work *fwork = | |
1119 | container_of(work, struct kthread_flush_work, work); | |
1120 | complete(&fwork->done); | |
1121 | } | |
1122 | ||
b56c0d89 | 1123 | /** |
3989144f | 1124 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
1125 | * @work: work to flush |
1126 | * | |
1127 | * If @work is queued or executing, wait for it to finish execution. | |
1128 | */ | |
3989144f | 1129 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 1130 | { |
46f3d976 TH |
1131 | struct kthread_flush_work fwork = { |
1132 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1133 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1134 | }; | |
1135 | struct kthread_worker *worker; | |
1136 | bool noop = false; | |
1137 | ||
46f3d976 TH |
1138 | worker = work->worker; |
1139 | if (!worker) | |
1140 | return; | |
b56c0d89 | 1141 | |
fe99a4f4 | 1142 | raw_spin_lock_irq(&worker->lock); |
8197b3d4 PM |
1143 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1144 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 1145 | |
46f3d976 | 1146 | if (!list_empty(&work->node)) |
3989144f | 1147 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 1148 | else if (worker->current_work == work) |
3989144f PM |
1149 | kthread_insert_work(worker, &fwork.work, |
1150 | worker->work_list.next); | |
46f3d976 TH |
1151 | else |
1152 | noop = true; | |
b56c0d89 | 1153 | |
fe99a4f4 | 1154 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 | 1155 | |
46f3d976 TH |
1156 | if (!noop) |
1157 | wait_for_completion(&fwork.done); | |
b56c0d89 | 1158 | } |
3989144f | 1159 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 1160 | |
34b3d534 PM |
1161 | /* |
1162 | * Make sure that the timer is neither set nor running and could | |
1163 | * not manipulate the work list_head any longer. | |
1164 | * | |
1165 | * The function is called under worker->lock. The lock is temporary | |
1166 | * released but the timer can't be set again in the meantime. | |
1167 | */ | |
1168 | static void kthread_cancel_delayed_work_timer(struct kthread_work *work, | |
1169 | unsigned long *flags) | |
1170 | { | |
1171 | struct kthread_delayed_work *dwork = | |
1172 | container_of(work, struct kthread_delayed_work, work); | |
1173 | struct kthread_worker *worker = work->worker; | |
1174 | ||
1175 | /* | |
1176 | * del_timer_sync() must be called to make sure that the timer | |
1177 | * callback is not running. The lock must be temporary released | |
1178 | * to avoid a deadlock with the callback. In the meantime, | |
1179 | * any queuing is blocked by setting the canceling counter. | |
1180 | */ | |
1181 | work->canceling++; | |
1182 | raw_spin_unlock_irqrestore(&worker->lock, *flags); | |
1183 | del_timer_sync(&dwork->timer); | |
1184 | raw_spin_lock_irqsave(&worker->lock, *flags); | |
1185 | work->canceling--; | |
1186 | } | |
1187 | ||
37be45d4 | 1188 | /* |
5fa54346 PM |
1189 | * This function removes the work from the worker queue. |
1190 | * | |
1191 | * It is called under worker->lock. The caller must make sure that | |
1192 | * the timer used by delayed work is not running, e.g. by calling | |
1193 | * kthread_cancel_delayed_work_timer(). | |
37be45d4 PM |
1194 | * |
1195 | * The work might still be in use when this function finishes. See the | |
1196 | * current_work proceed by the worker. | |
1197 | * | |
1198 | * Return: %true if @work was pending and successfully canceled, | |
1199 | * %false if @work was not pending | |
1200 | */ | |
5fa54346 | 1201 | static bool __kthread_cancel_work(struct kthread_work *work) |
37be45d4 | 1202 | { |
37be45d4 PM |
1203 | /* |
1204 | * Try to remove the work from a worker list. It might either | |
1205 | * be from worker->work_list or from worker->delayed_work_list. | |
1206 | */ | |
1207 | if (!list_empty(&work->node)) { | |
1208 | list_del_init(&work->node); | |
1209 | return true; | |
1210 | } | |
1211 | ||
1212 | return false; | |
1213 | } | |
1214 | ||
9a6b06c8 PM |
1215 | /** |
1216 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1217 | * @worker: kthread worker to use | |
1218 | * @dwork: kthread delayed work to queue | |
1219 | * @delay: number of jiffies to wait before queuing | |
1220 | * | |
1221 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1222 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1223 | * @work is guaranteed to be queued immediately. | |
1224 | * | |
d71ba164 | 1225 | * Return: %false if @dwork was idle and queued, %true otherwise. |
9a6b06c8 PM |
1226 | * |
1227 | * A special case is when the work is being canceled in parallel. | |
1228 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1229 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
d71ba164 PM |
1230 | * win and return %true here. The return value can be used for reference |
1231 | * counting and the number of queued works stays the same. Anyway, the caller | |
1232 | * is supposed to synchronize these operations a reasonable way. | |
9a6b06c8 PM |
1233 | * |
1234 | * This function is safe to call from any context including IRQ handler. | |
1235 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1236 | * for details. | |
1237 | */ | |
1238 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1239 | struct kthread_delayed_work *dwork, | |
1240 | unsigned long delay) | |
1241 | { | |
1242 | struct kthread_work *work = &dwork->work; | |
1243 | unsigned long flags; | |
d71ba164 | 1244 | int ret; |
9a6b06c8 | 1245 | |
fe99a4f4 | 1246 | raw_spin_lock_irqsave(&worker->lock, flags); |
9a6b06c8 PM |
1247 | |
1248 | /* Do not bother with canceling when never queued. */ | |
d71ba164 PM |
1249 | if (!work->worker) { |
1250 | ret = false; | |
9a6b06c8 | 1251 | goto fast_queue; |
d71ba164 | 1252 | } |
9a6b06c8 PM |
1253 | |
1254 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1255 | WARN_ON_ONCE(work->worker != worker); | |
1256 | ||
5fa54346 PM |
1257 | /* |
1258 | * Temporary cancel the work but do not fight with another command | |
1259 | * that is canceling the work as well. | |
1260 | * | |
1261 | * It is a bit tricky because of possible races with another | |
1262 | * mod_delayed_work() and cancel_delayed_work() callers. | |
1263 | * | |
1264 | * The timer must be canceled first because worker->lock is released | |
1265 | * when doing so. But the work can be removed from the queue (list) | |
1266 | * only when it can be queued again so that the return value can | |
1267 | * be used for reference counting. | |
1268 | */ | |
1269 | kthread_cancel_delayed_work_timer(work, &flags); | |
d71ba164 PM |
1270 | if (work->canceling) { |
1271 | /* The number of works in the queue does not change. */ | |
1272 | ret = true; | |
9a6b06c8 | 1273 | goto out; |
d71ba164 | 1274 | } |
5fa54346 | 1275 | ret = __kthread_cancel_work(work); |
9a6b06c8 | 1276 | |
9a6b06c8 PM |
1277 | fast_queue: |
1278 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1279 | out: | |
fe99a4f4 | 1280 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
9a6b06c8 PM |
1281 | return ret; |
1282 | } | |
1283 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1284 | ||
37be45d4 PM |
1285 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1286 | { | |
1287 | struct kthread_worker *worker = work->worker; | |
1288 | unsigned long flags; | |
1289 | int ret = false; | |
1290 | ||
1291 | if (!worker) | |
1292 | goto out; | |
1293 | ||
fe99a4f4 | 1294 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1295 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1296 | WARN_ON_ONCE(work->worker != worker); | |
1297 | ||
5fa54346 PM |
1298 | if (is_dwork) |
1299 | kthread_cancel_delayed_work_timer(work, &flags); | |
1300 | ||
1301 | ret = __kthread_cancel_work(work); | |
37be45d4 PM |
1302 | |
1303 | if (worker->current_work != work) | |
1304 | goto out_fast; | |
1305 | ||
1306 | /* | |
1307 | * The work is in progress and we need to wait with the lock released. | |
1308 | * In the meantime, block any queuing by setting the canceling counter. | |
1309 | */ | |
1310 | work->canceling++; | |
fe99a4f4 | 1311 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 | 1312 | kthread_flush_work(work); |
fe99a4f4 | 1313 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1314 | work->canceling--; |
1315 | ||
1316 | out_fast: | |
fe99a4f4 | 1317 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 PM |
1318 | out: |
1319 | return ret; | |
1320 | } | |
1321 | ||
1322 | /** | |
1323 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1324 | * @work: the kthread work to cancel | |
1325 | * | |
1326 | * Cancel @work and wait for its execution to finish. This function | |
1327 | * can be used even if the work re-queues itself. On return from this | |
1328 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1329 | * | |
1330 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1331 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1332 | * | |
1333 | * The caller must ensure that the worker on which @work was last | |
1334 | * queued can't be destroyed before this function returns. | |
1335 | * | |
1336 | * Return: %true if @work was pending, %false otherwise. | |
1337 | */ | |
1338 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1339 | { | |
1340 | return __kthread_cancel_work_sync(work, false); | |
1341 | } | |
1342 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1343 | ||
1344 | /** | |
1345 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1346 | * wait for it to finish. | |
1347 | * @dwork: the kthread delayed work to cancel | |
1348 | * | |
1349 | * This is kthread_cancel_work_sync() for delayed works. | |
1350 | * | |
1351 | * Return: %true if @dwork was pending, %false otherwise. | |
1352 | */ | |
1353 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1354 | { | |
1355 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1356 | } | |
1357 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1358 | ||
b56c0d89 | 1359 | /** |
3989144f | 1360 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1361 | * @worker: worker to flush |
1362 | * | |
1363 | * Wait until all currently executing or pending works on @worker are | |
1364 | * finished. | |
1365 | */ | |
3989144f | 1366 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1367 | { |
1368 | struct kthread_flush_work fwork = { | |
1369 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1370 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1371 | }; | |
1372 | ||
3989144f | 1373 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1374 | wait_for_completion(&fwork.done); |
1375 | } | |
3989144f | 1376 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1377 | |
1378 | /** | |
1379 | * kthread_destroy_worker - destroy a kthread worker | |
1380 | * @worker: worker to be destroyed | |
1381 | * | |
1382 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1383 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1384 | * machines needed. | |
1385 | */ | |
1386 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1387 | { | |
1388 | struct task_struct *task; | |
1389 | ||
1390 | task = worker->task; | |
1391 | if (WARN_ON(!task)) | |
1392 | return; | |
1393 | ||
1394 | kthread_flush_worker(worker); | |
1395 | kthread_stop(task); | |
1396 | WARN_ON(!list_empty(&worker->work_list)); | |
1397 | kfree(worker); | |
1398 | } | |
1399 | EXPORT_SYMBOL(kthread_destroy_worker); | |
05e3db95 | 1400 | |
f5678e7f CH |
1401 | /** |
1402 | * kthread_use_mm - make the calling kthread operate on an address space | |
1403 | * @mm: address space to operate on | |
9bf5b9eb | 1404 | */ |
f5678e7f | 1405 | void kthread_use_mm(struct mm_struct *mm) |
9bf5b9eb CH |
1406 | { |
1407 | struct mm_struct *active_mm; | |
1408 | struct task_struct *tsk = current; | |
1409 | ||
f5678e7f CH |
1410 | WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
1411 | WARN_ON_ONCE(tsk->mm); | |
1412 | ||
9bf5b9eb | 1413 | task_lock(tsk); |
38cf307c PZ |
1414 | /* Hold off tlb flush IPIs while switching mm's */ |
1415 | local_irq_disable(); | |
9bf5b9eb CH |
1416 | active_mm = tsk->active_mm; |
1417 | if (active_mm != mm) { | |
1418 | mmgrab(mm); | |
1419 | tsk->active_mm = mm; | |
1420 | } | |
1421 | tsk->mm = mm; | |
618758ed | 1422 | membarrier_update_current_mm(mm); |
38cf307c PZ |
1423 | switch_mm_irqs_off(active_mm, mm, tsk); |
1424 | local_irq_enable(); | |
9bf5b9eb CH |
1425 | task_unlock(tsk); |
1426 | #ifdef finish_arch_post_lock_switch | |
1427 | finish_arch_post_lock_switch(); | |
1428 | #endif | |
1429 | ||
618758ed MD |
1430 | /* |
1431 | * When a kthread starts operating on an address space, the loop | |
1432 | * in membarrier_{private,global}_expedited() may not observe | |
1433 | * that tsk->mm, and not issue an IPI. Membarrier requires a | |
1434 | * memory barrier after storing to tsk->mm, before accessing | |
1435 | * user-space memory. A full memory barrier for membarrier | |
1436 | * {PRIVATE,GLOBAL}_EXPEDITED is implicitly provided by | |
1437 | * mmdrop(), or explicitly with smp_mb(). | |
1438 | */ | |
9bf5b9eb CH |
1439 | if (active_mm != mm) |
1440 | mmdrop(active_mm); | |
618758ed MD |
1441 | else |
1442 | smp_mb(); | |
9bf5b9eb | 1443 | } |
f5678e7f | 1444 | EXPORT_SYMBOL_GPL(kthread_use_mm); |
9bf5b9eb | 1445 | |
f5678e7f CH |
1446 | /** |
1447 | * kthread_unuse_mm - reverse the effect of kthread_use_mm() | |
1448 | * @mm: address space to operate on | |
9bf5b9eb | 1449 | */ |
f5678e7f | 1450 | void kthread_unuse_mm(struct mm_struct *mm) |
9bf5b9eb CH |
1451 | { |
1452 | struct task_struct *tsk = current; | |
1453 | ||
f5678e7f CH |
1454 | WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
1455 | WARN_ON_ONCE(!tsk->mm); | |
1456 | ||
9bf5b9eb | 1457 | task_lock(tsk); |
618758ed MD |
1458 | /* |
1459 | * When a kthread stops operating on an address space, the loop | |
1460 | * in membarrier_{private,global}_expedited() may not observe | |
1461 | * that tsk->mm, and not issue an IPI. Membarrier requires a | |
1462 | * memory barrier after accessing user-space memory, before | |
1463 | * clearing tsk->mm. | |
1464 | */ | |
1465 | smp_mb__after_spinlock(); | |
9bf5b9eb | 1466 | sync_mm_rss(mm); |
38cf307c | 1467 | local_irq_disable(); |
9bf5b9eb | 1468 | tsk->mm = NULL; |
618758ed | 1469 | membarrier_update_current_mm(NULL); |
9bf5b9eb CH |
1470 | /* active_mm is still 'mm' */ |
1471 | enter_lazy_tlb(mm, tsk); | |
38cf307c | 1472 | local_irq_enable(); |
9bf5b9eb CH |
1473 | task_unlock(tsk); |
1474 | } | |
f5678e7f | 1475 | EXPORT_SYMBOL_GPL(kthread_unuse_mm); |
9bf5b9eb | 1476 | |
0b508bc9 | 1477 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
1478 | /** |
1479 | * kthread_associate_blkcg - associate blkcg to current kthread | |
1480 | * @css: the cgroup info | |
1481 | * | |
1482 | * Current thread must be a kthread. The thread is running jobs on behalf of | |
1483 | * other threads. In some cases, we expect the jobs attach cgroup info of | |
1484 | * original threads instead of that of current thread. This function stores | |
1485 | * original thread's cgroup info in current kthread context for later | |
1486 | * retrieval. | |
1487 | */ | |
1488 | void kthread_associate_blkcg(struct cgroup_subsys_state *css) | |
1489 | { | |
1490 | struct kthread *kthread; | |
1491 | ||
1492 | if (!(current->flags & PF_KTHREAD)) | |
1493 | return; | |
1494 | kthread = to_kthread(current); | |
1495 | if (!kthread) | |
1496 | return; | |
1497 | ||
1498 | if (kthread->blkcg_css) { | |
1499 | css_put(kthread->blkcg_css); | |
1500 | kthread->blkcg_css = NULL; | |
1501 | } | |
1502 | if (css) { | |
1503 | css_get(css); | |
1504 | kthread->blkcg_css = css; | |
1505 | } | |
1506 | } | |
1507 | EXPORT_SYMBOL(kthread_associate_blkcg); | |
1508 | ||
1509 | /** | |
1510 | * kthread_blkcg - get associated blkcg css of current kthread | |
1511 | * | |
1512 | * Current thread must be a kthread. | |
1513 | */ | |
1514 | struct cgroup_subsys_state *kthread_blkcg(void) | |
1515 | { | |
1516 | struct kthread *kthread; | |
1517 | ||
1518 | if (current->flags & PF_KTHREAD) { | |
1519 | kthread = to_kthread(current); | |
1520 | if (kthread) | |
1521 | return kthread->blkcg_css; | |
1522 | } | |
1523 | return NULL; | |
1524 | } | |
05e3db95 | 1525 | #endif |