Branch data Line data Source code
1 : : // SPDX-License-Identifier: GPL-2.0-only
2 : : /* Kernel thread helper functions.
3 : : * Copyright (C) 2004 IBM Corporation, Rusty Russell.
4 : : *
5 : : * Creation is done via kthreadd, so that we get a clean environment
6 : : * even if we're invoked from userspace (think modprobe, hotplug cpu,
7 : : * etc.).
8 : : */
9 : : #include <uapi/linux/sched/types.h>
10 : : #include <linux/sched.h>
11 : : #include <linux/sched/task.h>
12 : : #include <linux/kthread.h>
13 : : #include <linux/completion.h>
14 : : #include <linux/err.h>
15 : : #include <linux/cgroup.h>
16 : : #include <linux/cpuset.h>
17 : : #include <linux/unistd.h>
18 : : #include <linux/file.h>
19 : : #include <linux/export.h>
20 : : #include <linux/mutex.h>
21 : : #include <linux/slab.h>
22 : : #include <linux/freezer.h>
23 : : #include <linux/ptrace.h>
24 : : #include <linux/uaccess.h>
25 : : #include <linux/numa.h>
26 : : #include <trace/events/sched.h>
27 : :
28 : : static DEFINE_SPINLOCK(kthread_create_lock);
29 : : static LIST_HEAD(kthread_create_list);
30 : : struct task_struct *kthreadd_task;
31 : :
32 : : struct kthread_create_info
33 : : {
34 : : /* Information passed to kthread() from kthreadd. */
35 : : int (*threadfn)(void *data);
36 : : void *data;
37 : : int node;
38 : :
39 : : /* Result passed back to kthread_create() from kthreadd. */
40 : : struct task_struct *result;
41 : : struct completion *done;
42 : :
43 : : struct list_head list;
44 : : };
45 : :
46 : : struct kthread {
47 : : unsigned long flags;
48 : : unsigned int cpu;
49 : : void *data;
50 : : struct completion parked;
51 : : struct completion exited;
52 : : #ifdef CONFIG_BLK_CGROUP
53 : : struct cgroup_subsys_state *blkcg_css;
54 : : #endif
55 : : };
56 : :
57 : : enum KTHREAD_BITS {
58 : : KTHREAD_IS_PER_CPU = 0,
59 : : KTHREAD_SHOULD_STOP,
60 : : KTHREAD_SHOULD_PARK,
61 : : };
62 : :
63 : 895 : static inline void set_kthread_struct(void *kthread)
64 : : {
65 : : /*
66 : : * We abuse ->set_child_tid to avoid the new member and because it
67 : : * can't be wrongly copied by copy_process(). We also rely on fact
68 : : * that the caller can't exec, so PF_KTHREAD can't be cleared.
69 : : */
70 : 895 : current->set_child_tid = (__force void __user *)kthread;
71 : : }
72 : :
73 : 82683 : static inline struct kthread *to_kthread(struct task_struct *k)
74 : : {
75 [ - - - + ]: 28662 : WARN_ON(!(k->flags & PF_KTHREAD));
76 : 82683 : return (__force void *)k->set_child_tid;
77 : : }
78 : :
79 : 663 : void free_kthread_struct(struct task_struct *k)
80 : : {
81 : 663 : struct kthread *kthread;
82 : :
83 : : /*
84 : : * Can be NULL if this kthread was created by kernel_thread()
85 : : * or if kmalloc() in kthread() failed.
86 : : */
87 [ - + ]: 663 : kthread = to_kthread(k);
88 : : #ifdef CONFIG_BLK_CGROUP
89 : : WARN_ON_ONCE(kthread && kthread->blkcg_css);
90 : : #endif
91 : 663 : kfree(kthread);
92 : 663 : }
93 : :
94 : : /**
95 : : * kthread_should_stop - should this kthread return now?
96 : : *
97 : : * When someone calls kthread_stop() on your kthread, it will be woken
98 : : * and this will return true. You should then return, and your return
99 : : * value will be passed through to kthread_stop().
100 : : */
101 : 28662 : bool kthread_should_stop(void)
102 : : {
103 [ - + ]: 28662 : return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags);
104 : : }
105 : : EXPORT_SYMBOL(kthread_should_stop);
106 : :
107 : 30002 : bool __kthread_should_park(struct task_struct *k)
108 : : {
109 [ - + ]: 30002 : return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags);
110 : : }
111 : : EXPORT_SYMBOL_GPL(__kthread_should_park);
112 : :
113 : : /**
114 : : * kthread_should_park - should this kthread park now?
115 : : *
116 : : * When someone calls kthread_park() on your kthread, it will be woken
117 : : * and this will return true. You should then do the necessary
118 : : * cleanup and call kthread_parkme()
119 : : *
120 : : * Similar to kthread_should_stop(), but this keeps the thread alive
121 : : * and in a park position. kthread_unpark() "restarts" the thread and
122 : : * calls the thread function again.
123 : : */
124 : 27999 : bool kthread_should_park(void)
125 : : {
126 : 27999 : return __kthread_should_park(current);
127 : : }
128 : : EXPORT_SYMBOL_GPL(kthread_should_park);
129 : :
130 : : /**
131 : : * kthread_freezable_should_stop - should this freezable kthread return now?
132 : : * @was_frozen: optional out parameter, indicates whether %current was frozen
133 : : *
134 : : * kthread_should_stop() for freezable kthreads, which will enter
135 : : * refrigerator if necessary. This function is safe from kthread_stop() /
136 : : * freezer deadlock and freezable kthreads should use this function instead
137 : : * of calling try_to_freeze() directly.
138 : : */
139 : 0 : bool kthread_freezable_should_stop(bool *was_frozen)
140 : : {
141 : 0 : bool frozen = false;
142 : :
143 : 0 : might_sleep();
144 : :
145 [ # # ]: 0 : if (unlikely(freezing(current)))
146 : 0 : frozen = __refrigerator(true);
147 : :
148 [ # # ]: 0 : if (was_frozen)
149 : 0 : *was_frozen = frozen;
150 : :
151 : 0 : return kthread_should_stop();
152 : : }
153 : : EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
154 : :
155 : : /**
156 : : * kthread_data - return data value specified on kthread creation
157 : : * @task: kthread task in question
158 : : *
159 : : * Return the data value specified when kthread @task was created.
160 : : * The caller is responsible for ensuring the validity of @task when
161 : : * calling this function.
162 : : */
163 : 23200 : void *kthread_data(struct task_struct *task)
164 : : {
165 [ - + ]: 23200 : return to_kthread(task)->data;
166 : : }
167 : :
168 : : /**
169 : : * kthread_probe_data - speculative version of kthread_data()
170 : : * @task: possible kthread task in question
171 : : *
172 : : * @task could be a kthread task. Return the data value specified when it
173 : : * was created if accessible. If @task isn't a kthread task or its data is
174 : : * inaccessible for any reason, %NULL is returned. This function requires
175 : : * that @task itself is safe to dereference.
176 : : */
177 : 0 : void *kthread_probe_data(struct task_struct *task)
178 : : {
179 [ # # ]: 0 : struct kthread *kthread = to_kthread(task);
180 : 0 : void *data = NULL;
181 : :
182 : 0 : probe_kernel_read(&data, &kthread->data, sizeof(data));
183 : 0 : return data;
184 : : }
185 : :
186 : 895 : static void __kthread_parkme(struct kthread *self)
187 : : {
188 : 973 : for (;;) {
189 : : /*
190 : : * TASK_PARKED is a special state; we must serialize against
191 : : * possible pending wakeups to avoid store-store collisions on
192 : : * task->state.
193 : : *
194 : : * Such a collision might possibly result in the task state
195 : : * changin from TASK_PARKED and us failing the
196 : : * wait_task_inactive() in kthread_park().
197 : : */
198 : 934 : set_special_state(TASK_PARKED);
199 [ + + ]: 934 : if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags))
200 : : break;
201 : :
202 : 39 : complete(&self->parked);
203 : 39 : schedule();
204 : : }
205 : 895 : __set_current_state(TASK_RUNNING);
206 : 895 : }
207 : :
208 : 0 : void kthread_parkme(void)
209 : : {
210 [ # # ]: 0 : __kthread_parkme(to_kthread(current));
211 : 0 : }
212 : : EXPORT_SYMBOL_GPL(kthread_parkme);
213 : :
214 : 895 : static int kthread(void *_create)
215 : : {
216 : : /* Copy data: it's on kthread's stack */
217 : 895 : struct kthread_create_info *create = _create;
218 : 895 : int (*threadfn)(void *data) = create->threadfn;
219 : 895 : void *data = create->data;
220 : 895 : struct completion *done;
221 : 895 : struct kthread *self;
222 : 895 : int ret;
223 : :
224 : 895 : self = kzalloc(sizeof(*self), GFP_KERNEL);
225 : 895 : set_kthread_struct(self);
226 : :
227 : : /* If user was SIGKILLed, I release the structure. */
228 : 895 : done = xchg(&create->done, NULL);
229 [ - + ]: 895 : if (!done) {
230 : 0 : kfree(create);
231 : 0 : do_exit(-EINTR);
232 : : }
233 : :
234 [ - + ]: 895 : if (!self) {
235 : 0 : create->result = ERR_PTR(-ENOMEM);
236 : 0 : complete(done);
237 : 0 : do_exit(-ENOMEM);
238 : : }
239 : :
240 : 895 : self->data = data;
241 : 895 : init_completion(&self->exited);
242 : 895 : init_completion(&self->parked);
243 : 895 : current->vfork_done = &self->exited;
244 : :
245 : : /* OK, tell user we're spawned, wait for stop or wakeup */
246 : 895 : __set_current_state(TASK_UNINTERRUPTIBLE);
247 : 895 : create->result = current;
248 : 895 : complete(done);
249 : 895 : schedule();
250 : :
251 : 895 : ret = -EINTR;
252 [ + - ]: 895 : if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
253 : 895 : cgroup_kthread_ready();
254 : 895 : __kthread_parkme(self);
255 : 895 : ret = threadfn(data);
256 : : }
257 : 0 : do_exit(ret);
258 : : }
259 : :
260 : : /* called from do_fork() to get node information for about to be created task */
261 : 6576 : int tsk_fork_get_node(struct task_struct *tsk)
262 : : {
263 : : #ifdef CONFIG_NUMA
264 [ + + ]: 6576 : if (tsk == kthreadd_task)
265 : 895 : return tsk->pref_node_fork;
266 : : #endif
267 : : return NUMA_NO_NODE;
268 : : }
269 : :
270 : 895 : static void create_kthread(struct kthread_create_info *create)
271 : : {
272 : 895 : int pid;
273 : :
274 : : #ifdef CONFIG_NUMA
275 : 895 : current->pref_node_fork = create->node;
276 : : #endif
277 : : /* We want our own signal handler (we take no signals by default). */
278 : 895 : pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
279 [ - + ]: 895 : if (pid < 0) {
280 : : /* If user was SIGKILLed, I release the structure. */
281 : 0 : struct completion *done = xchg(&create->done, NULL);
282 : :
283 [ # # ]: 0 : if (!done) {
284 : 0 : kfree(create);
285 : 0 : return;
286 : : }
287 : 0 : create->result = ERR_PTR(pid);
288 : 0 : complete(done);
289 : : }
290 : : }
291 : :
292 : : static __printf(4, 0)
293 : 895 : struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
294 : : void *data, int node,
295 : : const char namefmt[],
296 : : va_list args)
297 : : {
298 : 895 : DECLARE_COMPLETION_ONSTACK(done);
299 : 895 : struct task_struct *task;
300 : 895 : struct kthread_create_info *create = kmalloc(sizeof(*create),
301 : : GFP_KERNEL);
302 : :
303 [ + - ]: 895 : if (!create)
304 : : return ERR_PTR(-ENOMEM);
305 : 895 : create->threadfn = threadfn;
306 : 895 : create->data = data;
307 : 895 : create->node = node;
308 : 895 : create->done = &done;
309 : :
310 : 895 : spin_lock(&kthread_create_lock);
311 : 895 : list_add_tail(&create->list, &kthread_create_list);
312 : 895 : spin_unlock(&kthread_create_lock);
313 : :
314 : 895 : wake_up_process(kthreadd_task);
315 : : /*
316 : : * Wait for completion in killable state, for I might be chosen by
317 : : * the OOM killer while kthreadd is trying to allocate memory for
318 : : * new kernel thread.
319 : : */
320 [ - + ]: 895 : if (unlikely(wait_for_completion_killable(&done))) {
321 : : /*
322 : : * If I was SIGKILLed before kthreadd (or new kernel thread)
323 : : * calls complete(), leave the cleanup of this structure to
324 : : * that thread.
325 : : */
326 [ # # ]: 0 : if (xchg(&create->done, NULL))
327 : : return ERR_PTR(-EINTR);
328 : : /*
329 : : * kthreadd (or new kernel thread) will call complete()
330 : : * shortly.
331 : : */
332 : 0 : wait_for_completion(&done);
333 : : }
334 : 895 : task = create->result;
335 [ + - ]: 895 : if (!IS_ERR(task)) {
336 : 895 : static const struct sched_param param = { .sched_priority = 0 };
337 : 895 : char name[TASK_COMM_LEN];
338 : :
339 : : /*
340 : : * task is already visible to other tasks, so updating
341 : : * COMM must be protected.
342 : : */
343 : 895 : vsnprintf(name, sizeof(name), namefmt, args);
344 : 895 : set_task_comm(task, name);
345 : : /*
346 : : * root may have changed our (kthreadd's) priority or CPU mask.
347 : : * The kernel thread should not inherit these properties.
348 : : */
349 : 895 : sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m);
350 : 895 : set_cpus_allowed_ptr(task, cpu_all_mask);
351 : : }
352 : 895 : kfree(create);
353 : 895 : return task;
354 : : }
355 : :
356 : : /**
357 : : * kthread_create_on_node - create a kthread.
358 : : * @threadfn: the function to run until signal_pending(current).
359 : : * @data: data ptr for @threadfn.
360 : : * @node: task and thread structures for the thread are allocated on this node
361 : : * @namefmt: printf-style name for the thread.
362 : : *
363 : : * Description: This helper function creates and names a kernel
364 : : * thread. The thread will be stopped: use wake_up_process() to start
365 : : * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
366 : : * is affine to all CPUs.
367 : : *
368 : : * If thread is going to be bound on a particular cpu, give its node
369 : : * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
370 : : * When woken, the thread will run @threadfn() with @data as its
371 : : * argument. @threadfn() can either call do_exit() directly if it is a
372 : : * standalone thread for which no one will call kthread_stop(), or
373 : : * return when 'kthread_should_stop()' is true (which means
374 : : * kthread_stop() has been called). The return value should be zero
375 : : * or a negative error number; it will be passed to kthread_stop().
376 : : *
377 : : * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
378 : : */
379 : 895 : struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
380 : : void *data, int node,
381 : : const char namefmt[],
382 : : ...)
383 : : {
384 : 895 : struct task_struct *task;
385 : 895 : va_list args;
386 : :
387 : 895 : va_start(args, namefmt);
388 : 895 : task = __kthread_create_on_node(threadfn, data, node, namefmt, args);
389 : 895 : va_end(args);
390 : :
391 : 895 : return task;
392 : : }
393 : : EXPORT_SYMBOL(kthread_create_on_node);
394 : :
395 : 479 : static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state)
396 : : {
397 : 479 : unsigned long flags;
398 : :
399 [ - + ]: 479 : if (!wait_task_inactive(p, state)) {
400 : 0 : WARN_ON(1);
401 : 0 : return;
402 : : }
403 : :
404 : : /* It's safe because the task is inactive. */
405 : 479 : raw_spin_lock_irqsave(&p->pi_lock, flags);
406 : 479 : do_set_cpus_allowed(p, mask);
407 : 479 : p->flags |= PF_NO_SETAFFINITY;
408 : 479 : raw_spin_unlock_irqrestore(&p->pi_lock, flags);
409 : : }
410 : :
411 : 78 : static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
412 : : {
413 : 78 : __kthread_bind_mask(p, cpumask_of(cpu), state);
414 : 39 : }
415 : :
416 : 401 : void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
417 : : {
418 : 401 : __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
419 : 401 : }
420 : :
421 : : /**
422 : : * kthread_bind - bind a just-created kthread to a cpu.
423 : : * @p: thread created by kthread_create().
424 : : * @cpu: cpu (might not be online, must be possible) for @k to run on.
425 : : *
426 : : * Description: This function is equivalent to set_cpus_allowed(),
427 : : * except that @cpu doesn't need to be online, and the thread must be
428 : : * stopped (i.e., just returned from kthread_create()).
429 : : */
430 : 39 : void kthread_bind(struct task_struct *p, unsigned int cpu)
431 : : {
432 : 0 : __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
433 : 0 : }
434 : : EXPORT_SYMBOL(kthread_bind);
435 : :
436 : : /**
437 : : * kthread_create_on_cpu - Create a cpu bound kthread
438 : : * @threadfn: the function to run until signal_pending(current).
439 : : * @data: data ptr for @threadfn.
440 : : * @cpu: The cpu on which the thread should be bound,
441 : : * @namefmt: printf-style name for the thread. Format is restricted
442 : : * to "name.*%u". Code fills in cpu number.
443 : : *
444 : : * Description: This helper function creates and names a kernel thread
445 : : * The thread will be woken and put into park mode.
446 : : */
447 : 39 : struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
448 : : void *data, unsigned int cpu,
449 : : const char *namefmt)
450 : : {
451 : 39 : struct task_struct *p;
452 : :
453 : 39 : p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt,
454 : : cpu);
455 [ + - ]: 39 : if (IS_ERR(p))
456 : : return p;
457 : 39 : kthread_bind(p, cpu);
458 : : /* CPU hotplug need to bind once again when unparking the thread. */
459 [ - + ]: 39 : set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags);
460 [ - + ]: 39 : to_kthread(p)->cpu = cpu;
461 : 39 : return p;
462 : : }
463 : :
464 : : /**
465 : : * kthread_unpark - unpark a thread created by kthread_create().
466 : : * @k: thread created by kthread_create().
467 : : *
468 : : * Sets kthread_should_park() for @k to return false, wakes it, and
469 : : * waits for it to return. If the thread is marked percpu then its
470 : : * bound to the cpu again.
471 : : */
472 : 39 : void kthread_unpark(struct task_struct *k)
473 : : {
474 [ - + ]: 39 : struct kthread *kthread = to_kthread(k);
475 : :
476 : : /*
477 : : * Newly created kthread was parked when the CPU was offline.
478 : : * The binding was lost and we need to set it again.
479 : : */
480 [ + - ]: 39 : if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
481 : 39 : __kthread_bind(k, kthread->cpu, TASK_PARKED);
482 : :
483 : 39 : clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
484 : : /*
485 : : * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup.
486 : : */
487 : 39 : wake_up_state(k, TASK_PARKED);
488 : 39 : }
489 : : EXPORT_SYMBOL_GPL(kthread_unpark);
490 : :
491 : : /**
492 : : * kthread_park - park a thread created by kthread_create().
493 : : * @k: thread created by kthread_create().
494 : : *
495 : : * Sets kthread_should_park() for @k to return true, wakes it, and
496 : : * waits for it to return. This can also be called after kthread_create()
497 : : * instead of calling wake_up_process(): the thread will park without
498 : : * calling threadfn().
499 : : *
500 : : * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
501 : : * If called by the kthread itself just the park bit is set.
502 : : */
503 : 39 : int kthread_park(struct task_struct *k)
504 : : {
505 [ - + ]: 39 : struct kthread *kthread = to_kthread(k);
506 : :
507 [ - + + - ]: 39 : if (WARN_ON(k->flags & PF_EXITING))
508 : : return -ENOSYS;
509 : :
510 [ - + + - ]: 39 : if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags)))
511 : : return -EBUSY;
512 : :
513 : 39 : set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
514 [ + - ]: 39 : if (k != current) {
515 : 39 : wake_up_process(k);
516 : : /*
517 : : * Wait for __kthread_parkme() to complete(), this means we
518 : : * _will_ have TASK_PARKED and are about to call schedule().
519 : : */
520 : 39 : wait_for_completion(&kthread->parked);
521 : : /*
522 : : * Now wait for that schedule() to complete and the task to
523 : : * get scheduled out.
524 : : */
525 [ - + ]: 39 : WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED));
526 : : }
527 : :
528 : : return 0;
529 : : }
530 : : EXPORT_SYMBOL_GPL(kthread_park);
531 : :
532 : : /**
533 : : * kthread_stop - stop a thread created by kthread_create().
534 : : * @k: thread created by kthread_create().
535 : : *
536 : : * Sets kthread_should_stop() for @k to return true, wakes it, and
537 : : * waits for it to exit. This can also be called after kthread_create()
538 : : * instead of calling wake_up_process(): the thread will exit without
539 : : * calling threadfn().
540 : : *
541 : : * If threadfn() may call do_exit() itself, the caller must ensure
542 : : * task_struct can't go away.
543 : : *
544 : : * Returns the result of threadfn(), or %-EINTR if wake_up_process()
545 : : * was never called.
546 : : */
547 : 0 : int kthread_stop(struct task_struct *k)
548 : : {
549 : 0 : struct kthread *kthread;
550 : 0 : int ret;
551 : :
552 : 0 : trace_sched_kthread_stop(k);
553 : :
554 : 0 : get_task_struct(k);
555 [ # # ]: 0 : kthread = to_kthread(k);
556 : 0 : set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
557 : 0 : kthread_unpark(k);
558 : 0 : wake_up_process(k);
559 : 0 : wait_for_completion(&kthread->exited);
560 : 0 : ret = k->exit_code;
561 : 0 : put_task_struct(k);
562 : :
563 : 0 : trace_sched_kthread_stop_ret(ret);
564 : 0 : return ret;
565 : : }
566 : : EXPORT_SYMBOL(kthread_stop);
567 : :
568 : 13 : int kthreadd(void *unused)
569 : : {
570 : 13 : struct task_struct *tsk = current;
571 : :
572 : : /* Setup a clean context for our children to inherit. */
573 : 13 : set_task_comm(tsk, "kthreadd");
574 : 13 : ignore_signals(tsk);
575 : 13 : set_cpus_allowed_ptr(tsk, cpu_all_mask);
576 : 13 : set_mems_allowed(node_states[N_MEMORY]);
577 : :
578 : 13 : current->flags |= PF_NOFREEZE;
579 : 13 : cgroup_init_kthreadd();
580 : :
581 : 906 : for (;;) {
582 : 906 : set_current_state(TASK_INTERRUPTIBLE);
583 [ + - ]: 906 : if (list_empty(&kthread_create_list))
584 : 906 : schedule();
585 : 893 : __set_current_state(TASK_RUNNING);
586 : :
587 : 893 : spin_lock(&kthread_create_lock);
588 [ + + ]: 1788 : while (!list_empty(&kthread_create_list)) {
589 : 895 : struct kthread_create_info *create;
590 : :
591 : 895 : create = list_entry(kthread_create_list.next,
592 : : struct kthread_create_info, list);
593 : 895 : list_del_init(&create->list);
594 : 895 : spin_unlock(&kthread_create_lock);
595 : :
596 : 895 : create_kthread(create);
597 : :
598 : 895 : spin_lock(&kthread_create_lock);
599 : : }
600 : 893 : spin_unlock(&kthread_create_lock);
601 : : }
602 : :
603 : : return 0;
604 : : }
605 : :
606 : 0 : void __kthread_init_worker(struct kthread_worker *worker,
607 : : const char *name,
608 : : struct lock_class_key *key)
609 : : {
610 : 0 : memset(worker, 0, sizeof(struct kthread_worker));
611 : 0 : raw_spin_lock_init(&worker->lock);
612 : 0 : lockdep_set_class_and_name(&worker->lock, key, name);
613 : 0 : INIT_LIST_HEAD(&worker->work_list);
614 : 0 : INIT_LIST_HEAD(&worker->delayed_work_list);
615 : 0 : }
616 : : EXPORT_SYMBOL_GPL(__kthread_init_worker);
617 : :
618 : : /**
619 : : * kthread_worker_fn - kthread function to process kthread_worker
620 : : * @worker_ptr: pointer to initialized kthread_worker
621 : : *
622 : : * This function implements the main cycle of kthread worker. It processes
623 : : * work_list until it is stopped with kthread_stop(). It sleeps when the queue
624 : : * is empty.
625 : : *
626 : : * The works are not allowed to keep any locks, disable preemption or interrupts
627 : : * when they finish. There is defined a safe point for freezing when one work
628 : : * finishes and before a new one is started.
629 : : *
630 : : * Also the works must not be handled by more than one worker at the same time,
631 : : * see also kthread_queue_work().
632 : : */
633 : 0 : int kthread_worker_fn(void *worker_ptr)
634 : : {
635 : 0 : struct kthread_worker *worker = worker_ptr;
636 : 0 : struct kthread_work *work;
637 : :
638 : : /*
639 : : * FIXME: Update the check and remove the assignment when all kthread
640 : : * worker users are created using kthread_create_worker*() functions.
641 : : */
642 [ # # # # : 0 : WARN_ON(worker->task && worker->task != current);
# # ]
643 [ # # ]: 0 : worker->task = current;
644 : :
645 [ # # ]: 0 : if (worker->flags & KTW_FREEZABLE)
646 : 0 : set_freezable();
647 : :
648 : 0 : repeat:
649 : 0 : set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
650 : :
651 [ # # ]: 0 : if (kthread_should_stop()) {
652 : 0 : __set_current_state(TASK_RUNNING);
653 : 0 : raw_spin_lock_irq(&worker->lock);
654 : 0 : worker->task = NULL;
655 : 0 : raw_spin_unlock_irq(&worker->lock);
656 : 0 : return 0;
657 : : }
658 : :
659 : 0 : work = NULL;
660 : 0 : raw_spin_lock_irq(&worker->lock);
661 [ # # ]: 0 : if (!list_empty(&worker->work_list)) {
662 : 0 : work = list_first_entry(&worker->work_list,
663 : : struct kthread_work, node);
664 : 0 : list_del_init(&work->node);
665 : : }
666 : 0 : worker->current_work = work;
667 : 0 : raw_spin_unlock_irq(&worker->lock);
668 : :
669 [ # # ]: 0 : if (work) {
670 : 0 : __set_current_state(TASK_RUNNING);
671 : 0 : work->func(work);
672 [ # # ]: 0 : } else if (!freezing(current))
673 : 0 : schedule();
674 : :
675 : 0 : try_to_freeze();
676 : 0 : cond_resched();
677 : 0 : goto repeat;
678 : : }
679 : : EXPORT_SYMBOL_GPL(kthread_worker_fn);
680 : :
681 : : static __printf(3, 0) struct kthread_worker *
682 : 0 : __kthread_create_worker(int cpu, unsigned int flags,
683 : : const char namefmt[], va_list args)
684 : : {
685 : 0 : struct kthread_worker *worker;
686 : 0 : struct task_struct *task;
687 : 0 : int node = NUMA_NO_NODE;
688 : :
689 : 0 : worker = kzalloc(sizeof(*worker), GFP_KERNEL);
690 [ # # ]: 0 : if (!worker)
691 : : return ERR_PTR(-ENOMEM);
692 : :
693 [ # # ]: 0 : kthread_init_worker(worker);
694 : :
695 [ # # ]: 0 : if (cpu >= 0)
696 : 0 : node = cpu_to_node(cpu);
697 : :
698 : 0 : task = __kthread_create_on_node(kthread_worker_fn, worker,
699 : : node, namefmt, args);
700 [ # # ]: 0 : if (IS_ERR(task))
701 : 0 : goto fail_task;
702 : :
703 [ # # ]: 0 : if (cpu >= 0)
704 : 0 : kthread_bind(task, cpu);
705 : :
706 : 0 : worker->flags = flags;
707 : 0 : worker->task = task;
708 : 0 : wake_up_process(task);
709 : 0 : return worker;
710 : :
711 : : fail_task:
712 : 0 : kfree(worker);
713 : 0 : return ERR_CAST(task);
714 : : }
715 : :
716 : : /**
717 : : * kthread_create_worker - create a kthread worker
718 : : * @flags: flags modifying the default behavior of the worker
719 : : * @namefmt: printf-style name for the kthread worker (task).
720 : : *
721 : : * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
722 : : * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
723 : : * when the worker was SIGKILLed.
724 : : */
725 : : struct kthread_worker *
726 : 0 : kthread_create_worker(unsigned int flags, const char namefmt[], ...)
727 : : {
728 : 0 : struct kthread_worker *worker;
729 : 0 : va_list args;
730 : :
731 : 0 : va_start(args, namefmt);
732 : 0 : worker = __kthread_create_worker(-1, flags, namefmt, args);
733 : 0 : va_end(args);
734 : :
735 : 0 : return worker;
736 : : }
737 : : EXPORT_SYMBOL(kthread_create_worker);
738 : :
739 : : /**
740 : : * kthread_create_worker_on_cpu - create a kthread worker and bind it
741 : : * it to a given CPU and the associated NUMA node.
742 : : * @cpu: CPU number
743 : : * @flags: flags modifying the default behavior of the worker
744 : : * @namefmt: printf-style name for the kthread worker (task).
745 : : *
746 : : * Use a valid CPU number if you want to bind the kthread worker
747 : : * to the given CPU and the associated NUMA node.
748 : : *
749 : : * A good practice is to add the cpu number also into the worker name.
750 : : * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
751 : : *
752 : : * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
753 : : * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
754 : : * when the worker was SIGKILLed.
755 : : */
756 : : struct kthread_worker *
757 : 0 : kthread_create_worker_on_cpu(int cpu, unsigned int flags,
758 : : const char namefmt[], ...)
759 : : {
760 : 0 : struct kthread_worker *worker;
761 : 0 : va_list args;
762 : :
763 : 0 : va_start(args, namefmt);
764 : 0 : worker = __kthread_create_worker(cpu, flags, namefmt, args);
765 : 0 : va_end(args);
766 : :
767 : 0 : return worker;
768 : : }
769 : : EXPORT_SYMBOL(kthread_create_worker_on_cpu);
770 : :
771 : : /*
772 : : * Returns true when the work could not be queued at the moment.
773 : : * It happens when it is already pending in a worker list
774 : : * or when it is being cancelled.
775 : : */
776 : 0 : static inline bool queuing_blocked(struct kthread_worker *worker,
777 : : struct kthread_work *work)
778 : : {
779 : 0 : lockdep_assert_held(&worker->lock);
780 : :
781 [ # # # # ]: 0 : return !list_empty(&work->node) || work->canceling;
782 : : }
783 : :
784 : 0 : static void kthread_insert_work_sanity_check(struct kthread_worker *worker,
785 : : struct kthread_work *work)
786 : : {
787 : 0 : lockdep_assert_held(&worker->lock);
788 [ # # ]: 0 : WARN_ON_ONCE(!list_empty(&work->node));
789 : : /* Do not use a work with >1 worker, see kthread_queue_work() */
790 [ # # # # : 0 : WARN_ON_ONCE(work->worker && work->worker != worker);
# # ]
791 : 0 : }
792 : :
793 : : /* insert @work before @pos in @worker */
794 : 0 : static void kthread_insert_work(struct kthread_worker *worker,
795 : : struct kthread_work *work,
796 : : struct list_head *pos)
797 : : {
798 : 0 : kthread_insert_work_sanity_check(worker, work);
799 : :
800 [ # # ]: 0 : list_add_tail(&work->node, pos);
801 : 0 : work->worker = worker;
802 [ # # # # ]: 0 : if (!worker->current_work && likely(worker->task))
803 : 0 : wake_up_process(worker->task);
804 : 0 : }
805 : :
806 : : /**
807 : : * kthread_queue_work - queue a kthread_work
808 : : * @worker: target kthread_worker
809 : : * @work: kthread_work to queue
810 : : *
811 : : * Queue @work to work processor @task for async execution. @task
812 : : * must have been created with kthread_worker_create(). Returns %true
813 : : * if @work was successfully queued, %false if it was already pending.
814 : : *
815 : : * Reinitialize the work if it needs to be used by another worker.
816 : : * For example, when the worker was stopped and started again.
817 : : */
818 : 0 : bool kthread_queue_work(struct kthread_worker *worker,
819 : : struct kthread_work *work)
820 : : {
821 : 0 : bool ret = false;
822 : 0 : unsigned long flags;
823 : :
824 : 0 : raw_spin_lock_irqsave(&worker->lock, flags);
825 [ # # # # ]: 0 : if (!queuing_blocked(worker, work)) {
826 : 0 : kthread_insert_work(worker, work, &worker->work_list);
827 : 0 : ret = true;
828 : : }
829 : 0 : raw_spin_unlock_irqrestore(&worker->lock, flags);
830 : 0 : return ret;
831 : : }
832 : : EXPORT_SYMBOL_GPL(kthread_queue_work);
833 : :
834 : : /**
835 : : * kthread_delayed_work_timer_fn - callback that queues the associated kthread
836 : : * delayed work when the timer expires.
837 : : * @t: pointer to the expired timer
838 : : *
839 : : * The format of the function is defined by struct timer_list.
840 : : * It should have been called from irqsafe timer with irq already off.
841 : : */
842 : 0 : void kthread_delayed_work_timer_fn(struct timer_list *t)
843 : : {
844 : 0 : struct kthread_delayed_work *dwork = from_timer(dwork, t, timer);
845 : 0 : struct kthread_work *work = &dwork->work;
846 : 0 : struct kthread_worker *worker = work->worker;
847 : 0 : unsigned long flags;
848 : :
849 : : /*
850 : : * This might happen when a pending work is reinitialized.
851 : : * It means that it is used a wrong way.
852 : : */
853 [ # # # # ]: 0 : if (WARN_ON_ONCE(!worker))
854 : : return;
855 : :
856 : 0 : raw_spin_lock_irqsave(&worker->lock, flags);
857 : : /* Work must not be used with >1 worker, see kthread_queue_work(). */
858 [ # # ]: 0 : WARN_ON_ONCE(work->worker != worker);
859 : :
860 : : /* Move the work from worker->delayed_work_list. */
861 [ # # ]: 0 : WARN_ON_ONCE(list_empty(&work->node));
862 : 0 : list_del_init(&work->node);
863 : 0 : kthread_insert_work(worker, work, &worker->work_list);
864 : :
865 : 0 : raw_spin_unlock_irqrestore(&worker->lock, flags);
866 : : }
867 : : EXPORT_SYMBOL(kthread_delayed_work_timer_fn);
868 : :
869 : 0 : static void __kthread_queue_delayed_work(struct kthread_worker *worker,
870 : : struct kthread_delayed_work *dwork,
871 : : unsigned long delay)
872 : : {
873 : 0 : struct timer_list *timer = &dwork->timer;
874 : 0 : struct kthread_work *work = &dwork->work;
875 : :
876 [ # # ]: 0 : WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn);
877 : :
878 : : /*
879 : : * If @delay is 0, queue @dwork->work immediately. This is for
880 : : * both optimization and correctness. The earliest @timer can
881 : : * expire is on the closest next tick and delayed_work users depend
882 : : * on that there's no such delay when @delay is 0.
883 : : */
884 [ # # ]: 0 : if (!delay) {
885 : 0 : kthread_insert_work(worker, work, &worker->work_list);
886 : 0 : return;
887 : : }
888 : :
889 : : /* Be paranoid and try to detect possible races already now. */
890 : 0 : kthread_insert_work_sanity_check(worker, work);
891 : :
892 : 0 : list_add(&work->node, &worker->delayed_work_list);
893 : 0 : work->worker = worker;
894 : 0 : timer->expires = jiffies + delay;
895 : 0 : add_timer(timer);
896 : : }
897 : :
898 : : /**
899 : : * kthread_queue_delayed_work - queue the associated kthread work
900 : : * after a delay.
901 : : * @worker: target kthread_worker
902 : : * @dwork: kthread_delayed_work to queue
903 : : * @delay: number of jiffies to wait before queuing
904 : : *
905 : : * If the work has not been pending it starts a timer that will queue
906 : : * the work after the given @delay. If @delay is zero, it queues the
907 : : * work immediately.
908 : : *
909 : : * Return: %false if the @work has already been pending. It means that
910 : : * either the timer was running or the work was queued. It returns %true
911 : : * otherwise.
912 : : */
913 : 0 : bool kthread_queue_delayed_work(struct kthread_worker *worker,
914 : : struct kthread_delayed_work *dwork,
915 : : unsigned long delay)
916 : : {
917 : 0 : struct kthread_work *work = &dwork->work;
918 : 0 : unsigned long flags;
919 : 0 : bool ret = false;
920 : :
921 : 0 : raw_spin_lock_irqsave(&worker->lock, flags);
922 : :
923 [ # # # # ]: 0 : if (!queuing_blocked(worker, work)) {
924 : 0 : __kthread_queue_delayed_work(worker, dwork, delay);
925 : 0 : ret = true;
926 : : }
927 : :
928 : 0 : raw_spin_unlock_irqrestore(&worker->lock, flags);
929 : 0 : return ret;
930 : : }
931 : : EXPORT_SYMBOL_GPL(kthread_queue_delayed_work);
932 : :
933 : : struct kthread_flush_work {
934 : : struct kthread_work work;
935 : : struct completion done;
936 : : };
937 : :
938 : 0 : static void kthread_flush_work_fn(struct kthread_work *work)
939 : : {
940 : 0 : struct kthread_flush_work *fwork =
941 : 0 : container_of(work, struct kthread_flush_work, work);
942 : 0 : complete(&fwork->done);
943 : 0 : }
944 : :
945 : : /**
946 : : * kthread_flush_work - flush a kthread_work
947 : : * @work: work to flush
948 : : *
949 : : * If @work is queued or executing, wait for it to finish execution.
950 : : */
951 : 0 : void kthread_flush_work(struct kthread_work *work)
952 : : {
953 : 0 : struct kthread_flush_work fwork = {
954 : : KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
955 : 0 : COMPLETION_INITIALIZER_ONSTACK(fwork.done),
956 : : };
957 : 0 : struct kthread_worker *worker;
958 : 0 : bool noop = false;
959 : :
960 : 0 : worker = work->worker;
961 [ # # ]: 0 : if (!worker)
962 : 0 : return;
963 : :
964 : 0 : raw_spin_lock_irq(&worker->lock);
965 : : /* Work must not be used with >1 worker, see kthread_queue_work(). */
966 [ # # ]: 0 : WARN_ON_ONCE(work->worker != worker);
967 : :
968 [ # # ]: 0 : if (!list_empty(&work->node))
969 : 0 : kthread_insert_work(worker, &fwork.work, work->node.next);
970 [ # # ]: 0 : else if (worker->current_work == work)
971 : 0 : kthread_insert_work(worker, &fwork.work,
972 : : worker->work_list.next);
973 : : else
974 : : noop = true;
975 : :
976 : 0 : raw_spin_unlock_irq(&worker->lock);
977 : :
978 [ # # ]: 0 : if (!noop)
979 : 0 : wait_for_completion(&fwork.done);
980 : : }
981 : : EXPORT_SYMBOL_GPL(kthread_flush_work);
982 : :
983 : : /*
984 : : * This function removes the work from the worker queue. Also it makes sure
985 : : * that it won't get queued later via the delayed work's timer.
986 : : *
987 : : * The work might still be in use when this function finishes. See the
988 : : * current_work proceed by the worker.
989 : : *
990 : : * Return: %true if @work was pending and successfully canceled,
991 : : * %false if @work was not pending
992 : : */
993 : 0 : static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork,
994 : : unsigned long *flags)
995 : : {
996 : : /* Try to cancel the timer if exists. */
997 [ # # ]: 0 : if (is_dwork) {
998 : 0 : struct kthread_delayed_work *dwork =
999 : 0 : container_of(work, struct kthread_delayed_work, work);
1000 : 0 : struct kthread_worker *worker = work->worker;
1001 : :
1002 : : /*
1003 : : * del_timer_sync() must be called to make sure that the timer
1004 : : * callback is not running. The lock must be temporary released
1005 : : * to avoid a deadlock with the callback. In the meantime,
1006 : : * any queuing is blocked by setting the canceling counter.
1007 : : */
1008 : 0 : work->canceling++;
1009 : 0 : raw_spin_unlock_irqrestore(&worker->lock, *flags);
1010 : 0 : del_timer_sync(&dwork->timer);
1011 : 0 : raw_spin_lock_irqsave(&worker->lock, *flags);
1012 : 0 : work->canceling--;
1013 : : }
1014 : :
1015 : : /*
1016 : : * Try to remove the work from a worker list. It might either
1017 : : * be from worker->work_list or from worker->delayed_work_list.
1018 : : */
1019 [ # # ]: 0 : if (!list_empty(&work->node)) {
1020 : 0 : list_del_init(&work->node);
1021 : 0 : return true;
1022 : : }
1023 : :
1024 : : return false;
1025 : : }
1026 : :
1027 : : /**
1028 : : * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
1029 : : * @worker: kthread worker to use
1030 : : * @dwork: kthread delayed work to queue
1031 : : * @delay: number of jiffies to wait before queuing
1032 : : *
1033 : : * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
1034 : : * modify @dwork's timer so that it expires after @delay. If @delay is zero,
1035 : : * @work is guaranteed to be queued immediately.
1036 : : *
1037 : : * Return: %true if @dwork was pending and its timer was modified,
1038 : : * %false otherwise.
1039 : : *
1040 : : * A special case is when the work is being canceled in parallel.
1041 : : * It might be caused either by the real kthread_cancel_delayed_work_sync()
1042 : : * or yet another kthread_mod_delayed_work() call. We let the other command
1043 : : * win and return %false here. The caller is supposed to synchronize these
1044 : : * operations a reasonable way.
1045 : : *
1046 : : * This function is safe to call from any context including IRQ handler.
1047 : : * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1048 : : * for details.
1049 : : */
1050 : 0 : bool kthread_mod_delayed_work(struct kthread_worker *worker,
1051 : : struct kthread_delayed_work *dwork,
1052 : : unsigned long delay)
1053 : : {
1054 : 0 : struct kthread_work *work = &dwork->work;
1055 : 0 : unsigned long flags;
1056 : 0 : int ret = false;
1057 : :
1058 : 0 : raw_spin_lock_irqsave(&worker->lock, flags);
1059 : :
1060 : : /* Do not bother with canceling when never queued. */
1061 [ # # ]: 0 : if (!work->worker)
1062 : 0 : goto fast_queue;
1063 : :
1064 : : /* Work must not be used with >1 worker, see kthread_queue_work() */
1065 [ # # ]: 0 : WARN_ON_ONCE(work->worker != worker);
1066 : :
1067 : : /* Do not fight with another command that is canceling this work. */
1068 [ # # ]: 0 : if (work->canceling)
1069 : 0 : goto out;
1070 : :
1071 : 0 : ret = __kthread_cancel_work(work, true, &flags);
1072 : 0 : fast_queue:
1073 : 0 : __kthread_queue_delayed_work(worker, dwork, delay);
1074 : 0 : out:
1075 : 0 : raw_spin_unlock_irqrestore(&worker->lock, flags);
1076 : 0 : return ret;
1077 : : }
1078 : : EXPORT_SYMBOL_GPL(kthread_mod_delayed_work);
1079 : :
1080 : 0 : static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork)
1081 : : {
1082 : 0 : struct kthread_worker *worker = work->worker;
1083 : 0 : unsigned long flags;
1084 : 0 : int ret = false;
1085 : :
1086 [ # # ]: 0 : if (!worker)
1087 : 0 : goto out;
1088 : :
1089 : 0 : raw_spin_lock_irqsave(&worker->lock, flags);
1090 : : /* Work must not be used with >1 worker, see kthread_queue_work(). */
1091 [ # # ]: 0 : WARN_ON_ONCE(work->worker != worker);
1092 : :
1093 : 0 : ret = __kthread_cancel_work(work, is_dwork, &flags);
1094 : :
1095 [ # # ]: 0 : if (worker->current_work != work)
1096 : 0 : goto out_fast;
1097 : :
1098 : : /*
1099 : : * The work is in progress and we need to wait with the lock released.
1100 : : * In the meantime, block any queuing by setting the canceling counter.
1101 : : */
1102 : 0 : work->canceling++;
1103 : 0 : raw_spin_unlock_irqrestore(&worker->lock, flags);
1104 : 0 : kthread_flush_work(work);
1105 : 0 : raw_spin_lock_irqsave(&worker->lock, flags);
1106 : 0 : work->canceling--;
1107 : :
1108 : 0 : out_fast:
1109 : 0 : raw_spin_unlock_irqrestore(&worker->lock, flags);
1110 : 0 : out:
1111 : 0 : return ret;
1112 : : }
1113 : :
1114 : : /**
1115 : : * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1116 : : * @work: the kthread work to cancel
1117 : : *
1118 : : * Cancel @work and wait for its execution to finish. This function
1119 : : * can be used even if the work re-queues itself. On return from this
1120 : : * function, @work is guaranteed to be not pending or executing on any CPU.
1121 : : *
1122 : : * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1123 : : * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1124 : : *
1125 : : * The caller must ensure that the worker on which @work was last
1126 : : * queued can't be destroyed before this function returns.
1127 : : *
1128 : : * Return: %true if @work was pending, %false otherwise.
1129 : : */
1130 : 0 : bool kthread_cancel_work_sync(struct kthread_work *work)
1131 : : {
1132 : 0 : return __kthread_cancel_work_sync(work, false);
1133 : : }
1134 : : EXPORT_SYMBOL_GPL(kthread_cancel_work_sync);
1135 : :
1136 : : /**
1137 : : * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1138 : : * wait for it to finish.
1139 : : * @dwork: the kthread delayed work to cancel
1140 : : *
1141 : : * This is kthread_cancel_work_sync() for delayed works.
1142 : : *
1143 : : * Return: %true if @dwork was pending, %false otherwise.
1144 : : */
1145 : 0 : bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork)
1146 : : {
1147 : 0 : return __kthread_cancel_work_sync(&dwork->work, true);
1148 : : }
1149 : : EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync);
1150 : :
1151 : : /**
1152 : : * kthread_flush_worker - flush all current works on a kthread_worker
1153 : : * @worker: worker to flush
1154 : : *
1155 : : * Wait until all currently executing or pending works on @worker are
1156 : : * finished.
1157 : : */
1158 : 0 : void kthread_flush_worker(struct kthread_worker *worker)
1159 : : {
1160 : 0 : struct kthread_flush_work fwork = {
1161 : : KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
1162 : 0 : COMPLETION_INITIALIZER_ONSTACK(fwork.done),
1163 : : };
1164 : :
1165 : 0 : kthread_queue_work(worker, &fwork.work);
1166 : 0 : wait_for_completion(&fwork.done);
1167 : 0 : }
1168 : : EXPORT_SYMBOL_GPL(kthread_flush_worker);
1169 : :
1170 : : /**
1171 : : * kthread_destroy_worker - destroy a kthread worker
1172 : : * @worker: worker to be destroyed
1173 : : *
1174 : : * Flush and destroy @worker. The simple flush is enough because the kthread
1175 : : * worker API is used only in trivial scenarios. There are no multi-step state
1176 : : * machines needed.
1177 : : */
1178 : 0 : void kthread_destroy_worker(struct kthread_worker *worker)
1179 : : {
1180 : 0 : struct task_struct *task;
1181 : :
1182 : 0 : task = worker->task;
1183 [ # # # # ]: 0 : if (WARN_ON(!task))
1184 : : return;
1185 : :
1186 : 0 : kthread_flush_worker(worker);
1187 : 0 : kthread_stop(task);
1188 [ # # ]: 0 : WARN_ON(!list_empty(&worker->work_list));
1189 : 0 : kfree(worker);
1190 : : }
1191 : : EXPORT_SYMBOL(kthread_destroy_worker);
1192 : :
1193 : : #ifdef CONFIG_BLK_CGROUP
1194 : : /**
1195 : : * kthread_associate_blkcg - associate blkcg to current kthread
1196 : : * @css: the cgroup info
1197 : : *
1198 : : * Current thread must be a kthread. The thread is running jobs on behalf of
1199 : : * other threads. In some cases, we expect the jobs attach cgroup info of
1200 : : * original threads instead of that of current thread. This function stores
1201 : : * original thread's cgroup info in current kthread context for later
1202 : : * retrieval.
1203 : : */
1204 : : void kthread_associate_blkcg(struct cgroup_subsys_state *css)
1205 : : {
1206 : : struct kthread *kthread;
1207 : :
1208 : : if (!(current->flags & PF_KTHREAD))
1209 : : return;
1210 : : kthread = to_kthread(current);
1211 : : if (!kthread)
1212 : : return;
1213 : :
1214 : : if (kthread->blkcg_css) {
1215 : : css_put(kthread->blkcg_css);
1216 : : kthread->blkcg_css = NULL;
1217 : : }
1218 : : if (css) {
1219 : : css_get(css);
1220 : : kthread->blkcg_css = css;
1221 : : }
1222 : : }
1223 : : EXPORT_SYMBOL(kthread_associate_blkcg);
1224 : :
1225 : : /**
1226 : : * kthread_blkcg - get associated blkcg css of current kthread
1227 : : *
1228 : : * Current thread must be a kthread.
1229 : : */
1230 : : struct cgroup_subsys_state *kthread_blkcg(void)
1231 : : {
1232 : : struct kthread *kthread;
1233 : :
1234 : : if (current->flags & PF_KTHREAD) {
1235 : : kthread = to_kthread(current);
1236 : : if (kthread)
1237 : : return kthread->blkcg_css;
1238 : : }
1239 : : return NULL;
1240 : : }
1241 : : EXPORT_SYMBOL(kthread_blkcg);
1242 : : #endif
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