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1da177e4 LT |
1 | /* Kernel thread helper functions. |
2 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. | |
3 | * | |
73c27992 | 4 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
5 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
6 | * etc.). | |
7 | */ | |
8 | #include <linux/sched.h> | |
9 | #include <linux/kthread.h> | |
10 | #include <linux/completion.h> | |
11 | #include <linux/err.h> | |
58568d2a | 12 | #include <linux/cpuset.h> |
1da177e4 LT |
13 | #include <linux/unistd.h> |
14 | #include <linux/file.h> | |
9984de1a | 15 | #include <linux/export.h> |
97d1f15b | 16 | #include <linux/mutex.h> |
b56c0d89 TH |
17 | #include <linux/slab.h> |
18 | #include <linux/freezer.h> | |
a74fb73c | 19 | #include <linux/ptrace.h> |
ad8d75ff | 20 | #include <trace/events/sched.h> |
1da177e4 | 21 | |
73c27992 EB |
22 | static DEFINE_SPINLOCK(kthread_create_lock); |
23 | static LIST_HEAD(kthread_create_list); | |
24 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
25 | |
26 | struct kthread_create_info | |
27 | { | |
73c27992 | 28 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
29 | int (*threadfn)(void *data); |
30 | void *data; | |
207205a2 | 31 | int node; |
1da177e4 | 32 | |
73c27992 | 33 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 LT |
34 | struct task_struct *result; |
35 | struct completion done; | |
65f27f38 | 36 | |
73c27992 | 37 | struct list_head list; |
1da177e4 LT |
38 | }; |
39 | ||
63706172 | 40 | struct kthread { |
2a1d4460 TG |
41 | unsigned long flags; |
42 | unsigned int cpu; | |
82805ab7 | 43 | void *data; |
2a1d4460 | 44 | struct completion parked; |
63706172 | 45 | struct completion exited; |
1da177e4 LT |
46 | }; |
47 | ||
2a1d4460 TG |
48 | enum KTHREAD_BITS { |
49 | KTHREAD_IS_PER_CPU = 0, | |
50 | KTHREAD_SHOULD_STOP, | |
51 | KTHREAD_SHOULD_PARK, | |
52 | KTHREAD_IS_PARKED, | |
53 | }; | |
54 | ||
4ecdafc8 ON |
55 | #define __to_kthread(vfork) \ |
56 | container_of(vfork, struct kthread, exited) | |
57 | ||
58 | static inline struct kthread *to_kthread(struct task_struct *k) | |
59 | { | |
60 | return __to_kthread(k->vfork_done); | |
61 | } | |
62 | ||
63 | static struct kthread *to_live_kthread(struct task_struct *k) | |
64 | { | |
65 | struct completion *vfork = ACCESS_ONCE(k->vfork_done); | |
66 | if (likely(vfork)) | |
67 | return __to_kthread(vfork); | |
68 | return NULL; | |
69 | } | |
1da177e4 | 70 | |
9e37bd30 RD |
71 | /** |
72 | * kthread_should_stop - should this kthread return now? | |
73 | * | |
72fd4a35 | 74 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
75 | * and this will return true. You should then return, and your return |
76 | * value will be passed through to kthread_stop(). | |
77 | */ | |
2a1d4460 | 78 | bool kthread_should_stop(void) |
1da177e4 | 79 | { |
2a1d4460 | 80 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
81 | } |
82 | EXPORT_SYMBOL(kthread_should_stop); | |
83 | ||
2a1d4460 TG |
84 | /** |
85 | * kthread_should_park - should this kthread park now? | |
86 | * | |
87 | * When someone calls kthread_park() on your kthread, it will be woken | |
88 | * and this will return true. You should then do the necessary | |
89 | * cleanup and call kthread_parkme() | |
90 | * | |
91 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
92 | * and in a park position. kthread_unpark() "restarts" the thread and | |
93 | * calls the thread function again. | |
94 | */ | |
95 | bool kthread_should_park(void) | |
96 | { | |
97 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags); | |
98 | } | |
99 | ||
8a32c441 TH |
100 | /** |
101 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
102 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
103 | * | |
104 | * kthread_should_stop() for freezable kthreads, which will enter | |
105 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
106 | * freezer deadlock and freezable kthreads should use this function instead | |
107 | * of calling try_to_freeze() directly. | |
108 | */ | |
109 | bool kthread_freezable_should_stop(bool *was_frozen) | |
110 | { | |
111 | bool frozen = false; | |
112 | ||
113 | might_sleep(); | |
114 | ||
115 | if (unlikely(freezing(current))) | |
116 | frozen = __refrigerator(true); | |
117 | ||
118 | if (was_frozen) | |
119 | *was_frozen = frozen; | |
120 | ||
121 | return kthread_should_stop(); | |
122 | } | |
123 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
124 | ||
82805ab7 TH |
125 | /** |
126 | * kthread_data - return data value specified on kthread creation | |
127 | * @task: kthread task in question | |
128 | * | |
129 | * Return the data value specified when kthread @task was created. | |
130 | * The caller is responsible for ensuring the validity of @task when | |
131 | * calling this function. | |
132 | */ | |
133 | void *kthread_data(struct task_struct *task) | |
134 | { | |
135 | return to_kthread(task)->data; | |
136 | } | |
137 | ||
2a1d4460 TG |
138 | static void __kthread_parkme(struct kthread *self) |
139 | { | |
f2530dc7 | 140 | __set_current_state(TASK_PARKED); |
2a1d4460 TG |
141 | while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) { |
142 | if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags)) | |
143 | complete(&self->parked); | |
144 | schedule(); | |
f2530dc7 | 145 | __set_current_state(TASK_PARKED); |
2a1d4460 TG |
146 | } |
147 | clear_bit(KTHREAD_IS_PARKED, &self->flags); | |
148 | __set_current_state(TASK_RUNNING); | |
149 | } | |
150 | ||
151 | void kthread_parkme(void) | |
152 | { | |
153 | __kthread_parkme(to_kthread(current)); | |
154 | } | |
155 | ||
1da177e4 LT |
156 | static int kthread(void *_create) |
157 | { | |
63706172 | 158 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 159 | struct kthread_create_info *create = _create; |
63706172 ON |
160 | int (*threadfn)(void *data) = create->threadfn; |
161 | void *data = create->data; | |
162 | struct kthread self; | |
163 | int ret; | |
1da177e4 | 164 | |
2a1d4460 | 165 | self.flags = 0; |
82805ab7 | 166 | self.data = data; |
63706172 | 167 | init_completion(&self.exited); |
2a1d4460 | 168 | init_completion(&self.parked); |
63706172 | 169 | current->vfork_done = &self.exited; |
1da177e4 | 170 | |
1da177e4 | 171 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 172 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 173 | create->result = current; |
cdd140bd | 174 | complete(&create->done); |
1da177e4 LT |
175 | schedule(); |
176 | ||
63706172 | 177 | ret = -EINTR; |
1da177e4 | 178 | |
2a1d4460 TG |
179 | if (!test_bit(KTHREAD_SHOULD_STOP, &self.flags)) { |
180 | __kthread_parkme(&self); | |
181 | ret = threadfn(data); | |
182 | } | |
63706172 ON |
183 | /* we can't just return, we must preserve "self" on stack */ |
184 | do_exit(ret); | |
1da177e4 LT |
185 | } |
186 | ||
207205a2 ED |
187 | /* called from do_fork() to get node information for about to be created task */ |
188 | int tsk_fork_get_node(struct task_struct *tsk) | |
189 | { | |
190 | #ifdef CONFIG_NUMA | |
191 | if (tsk == kthreadd_task) | |
192 | return tsk->pref_node_fork; | |
193 | #endif | |
194 | return numa_node_id(); | |
195 | } | |
196 | ||
73c27992 | 197 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 198 | { |
1da177e4 LT |
199 | int pid; |
200 | ||
207205a2 ED |
201 | #ifdef CONFIG_NUMA |
202 | current->pref_node_fork = create->node; | |
203 | #endif | |
1da177e4 LT |
204 | /* We want our own signal handler (we take no signals by default). */ |
205 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 206 | if (pid < 0) { |
1da177e4 | 207 | create->result = ERR_PTR(pid); |
cdd140bd ON |
208 | complete(&create->done); |
209 | } | |
1da177e4 LT |
210 | } |
211 | ||
9e37bd30 | 212 | /** |
207205a2 | 213 | * kthread_create_on_node - create a kthread. |
9e37bd30 RD |
214 | * @threadfn: the function to run until signal_pending(current). |
215 | * @data: data ptr for @threadfn. | |
207205a2 | 216 | * @node: memory node number. |
9e37bd30 RD |
217 | * @namefmt: printf-style name for the thread. |
218 | * | |
219 | * Description: This helper function creates and names a kernel | |
220 | * thread. The thread will be stopped: use wake_up_process() to start | |
301ba045 | 221 | * it. See also kthread_run(). |
9e37bd30 | 222 | * |
207205a2 ED |
223 | * If thread is going to be bound on a particular cpu, give its node |
224 | * in @node, to get NUMA affinity for kthread stack, or else give -1. | |
9e37bd30 | 225 | * When woken, the thread will run @threadfn() with @data as its |
72fd4a35 | 226 | * argument. @threadfn() can either call do_exit() directly if it is a |
25985edc | 227 | * standalone thread for which no one will call kthread_stop(), or |
9e37bd30 RD |
228 | * return when 'kthread_should_stop()' is true (which means |
229 | * kthread_stop() has been called). The return value should be zero | |
230 | * or a negative error number; it will be passed to kthread_stop(). | |
231 | * | |
232 | * Returns a task_struct or ERR_PTR(-ENOMEM). | |
233 | */ | |
207205a2 | 234 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), |
2a1d4460 | 235 | void *data, int node, |
207205a2 ED |
236 | const char namefmt[], |
237 | ...) | |
1da177e4 LT |
238 | { |
239 | struct kthread_create_info create; | |
1da177e4 LT |
240 | |
241 | create.threadfn = threadfn; | |
242 | create.data = data; | |
207205a2 | 243 | create.node = node; |
1da177e4 | 244 | init_completion(&create.done); |
73c27992 EB |
245 | |
246 | spin_lock(&kthread_create_lock); | |
247 | list_add_tail(&create.list, &kthread_create_list); | |
73c27992 EB |
248 | spin_unlock(&kthread_create_lock); |
249 | ||
cbd9b67b | 250 | wake_up_process(kthreadd_task); |
73c27992 EB |
251 | wait_for_completion(&create.done); |
252 | ||
1da177e4 | 253 | if (!IS_ERR(create.result)) { |
c9b5f501 | 254 | static const struct sched_param param = { .sched_priority = 0 }; |
1da177e4 | 255 | va_list args; |
1c99315b | 256 | |
1da177e4 LT |
257 | va_start(args, namefmt); |
258 | vsnprintf(create.result->comm, sizeof(create.result->comm), | |
259 | namefmt, args); | |
260 | va_end(args); | |
1c99315b ON |
261 | /* |
262 | * root may have changed our (kthreadd's) priority or CPU mask. | |
263 | * The kernel thread should not inherit these properties. | |
264 | */ | |
265 | sched_setscheduler_nocheck(create.result, SCHED_NORMAL, ¶m); | |
1c99315b | 266 | set_cpus_allowed_ptr(create.result, cpu_all_mask); |
1da177e4 | 267 | } |
1da177e4 LT |
268 | return create.result; |
269 | } | |
207205a2 | 270 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 271 | |
f2530dc7 | 272 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) |
2a1d4460 | 273 | { |
f2530dc7 TG |
274 | /* Must have done schedule() in kthread() before we set_task_cpu */ |
275 | if (!wait_task_inactive(p, state)) { | |
276 | WARN_ON(1); | |
277 | return; | |
278 | } | |
2a1d4460 TG |
279 | /* It's safe because the task is inactive. */ |
280 | do_set_cpus_allowed(p, cpumask_of(cpu)); | |
281 | p->flags |= PF_THREAD_BOUND; | |
282 | } | |
283 | ||
881232b7 PZ |
284 | /** |
285 | * kthread_bind - bind a just-created kthread to a cpu. | |
286 | * @p: thread created by kthread_create(). | |
287 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
288 | * | |
289 | * Description: This function is equivalent to set_cpus_allowed(), | |
290 | * except that @cpu doesn't need to be online, and the thread must be | |
291 | * stopped (i.e., just returned from kthread_create()). | |
292 | */ | |
293 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
294 | { | |
f2530dc7 | 295 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
296 | } |
297 | EXPORT_SYMBOL(kthread_bind); | |
298 | ||
2a1d4460 TG |
299 | /** |
300 | * kthread_create_on_cpu - Create a cpu bound kthread | |
301 | * @threadfn: the function to run until signal_pending(current). | |
302 | * @data: data ptr for @threadfn. | |
303 | * @cpu: The cpu on which the thread should be bound, | |
304 | * @namefmt: printf-style name for the thread. Format is restricted | |
305 | * to "name.*%u". Code fills in cpu number. | |
306 | * | |
307 | * Description: This helper function creates and names a kernel thread | |
308 | * The thread will be woken and put into park mode. | |
309 | */ | |
310 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
311 | void *data, unsigned int cpu, | |
312 | const char *namefmt) | |
313 | { | |
314 | struct task_struct *p; | |
315 | ||
316 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, | |
317 | cpu); | |
318 | if (IS_ERR(p)) | |
319 | return p; | |
320 | set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); | |
321 | to_kthread(p)->cpu = cpu; | |
322 | /* Park the thread to get it out of TASK_UNINTERRUPTIBLE state */ | |
323 | kthread_park(p); | |
324 | return p; | |
325 | } | |
326 | ||
327 | static struct kthread *task_get_live_kthread(struct task_struct *k) | |
328 | { | |
2a1d4460 | 329 | get_task_struct(k); |
4ecdafc8 | 330 | return to_live_kthread(k); |
2a1d4460 TG |
331 | } |
332 | ||
f2530dc7 TG |
333 | static void __kthread_unpark(struct task_struct *k, struct kthread *kthread) |
334 | { | |
335 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
336 | /* | |
337 | * We clear the IS_PARKED bit here as we don't wait | |
338 | * until the task has left the park code. So if we'd | |
339 | * park before that happens we'd see the IS_PARKED bit | |
340 | * which might be about to be cleared. | |
341 | */ | |
342 | if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) { | |
343 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) | |
344 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
345 | wake_up_state(k, TASK_PARKED); | |
346 | } | |
347 | } | |
348 | ||
2a1d4460 TG |
349 | /** |
350 | * kthread_unpark - unpark a thread created by kthread_create(). | |
351 | * @k: thread created by kthread_create(). | |
352 | * | |
353 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
354 | * waits for it to return. If the thread is marked percpu then its | |
355 | * bound to the cpu again. | |
356 | */ | |
357 | void kthread_unpark(struct task_struct *k) | |
358 | { | |
359 | struct kthread *kthread = task_get_live_kthread(k); | |
360 | ||
f2530dc7 TG |
361 | if (kthread) |
362 | __kthread_unpark(k, kthread); | |
2a1d4460 TG |
363 | put_task_struct(k); |
364 | } | |
365 | ||
366 | /** | |
367 | * kthread_park - park a thread created by kthread_create(). | |
368 | * @k: thread created by kthread_create(). | |
369 | * | |
370 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
371 | * waits for it to return. This can also be called after kthread_create() | |
372 | * instead of calling wake_up_process(): the thread will park without | |
373 | * calling threadfn(). | |
374 | * | |
375 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
376 | * If called by the kthread itself just the park bit is set. | |
377 | */ | |
378 | int kthread_park(struct task_struct *k) | |
379 | { | |
380 | struct kthread *kthread = task_get_live_kthread(k); | |
381 | int ret = -ENOSYS; | |
382 | ||
383 | if (kthread) { | |
384 | if (!test_bit(KTHREAD_IS_PARKED, &kthread->flags)) { | |
385 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
386 | if (k != current) { | |
387 | wake_up_process(k); | |
388 | wait_for_completion(&kthread->parked); | |
389 | } | |
390 | } | |
391 | ret = 0; | |
392 | } | |
393 | put_task_struct(k); | |
394 | return ret; | |
395 | } | |
396 | ||
9e37bd30 RD |
397 | /** |
398 | * kthread_stop - stop a thread created by kthread_create(). | |
399 | * @k: thread created by kthread_create(). | |
400 | * | |
401 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
402 | * waits for it to exit. This can also be called after kthread_create() |
403 | * instead of calling wake_up_process(): the thread will exit without | |
404 | * calling threadfn(). | |
405 | * | |
406 | * If threadfn() may call do_exit() itself, the caller must ensure | |
407 | * task_struct can't go away. | |
9e37bd30 RD |
408 | * |
409 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
410 | * was never called. | |
411 | */ | |
1da177e4 LT |
412 | int kthread_stop(struct task_struct *k) |
413 | { | |
2a1d4460 | 414 | struct kthread *kthread = task_get_live_kthread(k); |
1da177e4 LT |
415 | int ret; |
416 | ||
0a16b607 | 417 | trace_sched_kthread_stop(k); |
2a1d4460 TG |
418 | if (kthread) { |
419 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
f2530dc7 | 420 | __kthread_unpark(k, kthread); |
63706172 ON |
421 | wake_up_process(k); |
422 | wait_for_completion(&kthread->exited); | |
423 | } | |
424 | ret = k->exit_code; | |
1da177e4 | 425 | |
1da177e4 | 426 | put_task_struct(k); |
0a16b607 MD |
427 | trace_sched_kthread_stop_ret(ret); |
428 | ||
1da177e4 LT |
429 | return ret; |
430 | } | |
52e92e57 | 431 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 432 | |
e804a4a4 | 433 | int kthreadd(void *unused) |
1da177e4 | 434 | { |
73c27992 | 435 | struct task_struct *tsk = current; |
1da177e4 | 436 | |
e804a4a4 | 437 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 438 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 439 | ignore_signals(tsk); |
1a2142af | 440 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa4 | 441 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 442 | |
34b087e4 | 443 | current->flags |= PF_NOFREEZE; |
73c27992 EB |
444 | |
445 | for (;;) { | |
446 | set_current_state(TASK_INTERRUPTIBLE); | |
447 | if (list_empty(&kthread_create_list)) | |
448 | schedule(); | |
449 | __set_current_state(TASK_RUNNING); | |
450 | ||
451 | spin_lock(&kthread_create_lock); | |
452 | while (!list_empty(&kthread_create_list)) { | |
453 | struct kthread_create_info *create; | |
454 | ||
455 | create = list_entry(kthread_create_list.next, | |
456 | struct kthread_create_info, list); | |
457 | list_del_init(&create->list); | |
458 | spin_unlock(&kthread_create_lock); | |
459 | ||
460 | create_kthread(create); | |
461 | ||
462 | spin_lock(&kthread_create_lock); | |
463 | } | |
464 | spin_unlock(&kthread_create_lock); | |
465 | } | |
466 | ||
467 | return 0; | |
468 | } | |
b56c0d89 | 469 | |
4f32e9b1 YZ |
470 | void __init_kthread_worker(struct kthread_worker *worker, |
471 | const char *name, | |
472 | struct lock_class_key *key) | |
473 | { | |
474 | spin_lock_init(&worker->lock); | |
475 | lockdep_set_class_and_name(&worker->lock, key, name); | |
476 | INIT_LIST_HEAD(&worker->work_list); | |
477 | worker->task = NULL; | |
478 | } | |
479 | EXPORT_SYMBOL_GPL(__init_kthread_worker); | |
480 | ||
b56c0d89 TH |
481 | /** |
482 | * kthread_worker_fn - kthread function to process kthread_worker | |
483 | * @worker_ptr: pointer to initialized kthread_worker | |
484 | * | |
485 | * This function can be used as @threadfn to kthread_create() or | |
486 | * kthread_run() with @worker_ptr argument pointing to an initialized | |
487 | * kthread_worker. The started kthread will process work_list until | |
488 | * the it is stopped with kthread_stop(). A kthread can also call | |
489 | * this function directly after extra initialization. | |
490 | * | |
491 | * Different kthreads can be used for the same kthread_worker as long | |
492 | * as there's only one kthread attached to it at any given time. A | |
493 | * kthread_worker without an attached kthread simply collects queued | |
494 | * kthread_works. | |
495 | */ | |
496 | int kthread_worker_fn(void *worker_ptr) | |
497 | { | |
498 | struct kthread_worker *worker = worker_ptr; | |
499 | struct kthread_work *work; | |
500 | ||
501 | WARN_ON(worker->task); | |
502 | worker->task = current; | |
503 | repeat: | |
504 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
505 | ||
506 | if (kthread_should_stop()) { | |
507 | __set_current_state(TASK_RUNNING); | |
508 | spin_lock_irq(&worker->lock); | |
509 | worker->task = NULL; | |
510 | spin_unlock_irq(&worker->lock); | |
511 | return 0; | |
512 | } | |
513 | ||
514 | work = NULL; | |
515 | spin_lock_irq(&worker->lock); | |
516 | if (!list_empty(&worker->work_list)) { | |
517 | work = list_first_entry(&worker->work_list, | |
518 | struct kthread_work, node); | |
519 | list_del_init(&work->node); | |
520 | } | |
46f3d976 | 521 | worker->current_work = work; |
b56c0d89 TH |
522 | spin_unlock_irq(&worker->lock); |
523 | ||
524 | if (work) { | |
525 | __set_current_state(TASK_RUNNING); | |
526 | work->func(work); | |
b56c0d89 TH |
527 | } else if (!freezing(current)) |
528 | schedule(); | |
529 | ||
530 | try_to_freeze(); | |
531 | goto repeat; | |
532 | } | |
533 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
534 | ||
9a2e03d8 TH |
535 | /* insert @work before @pos in @worker */ |
536 | static void insert_kthread_work(struct kthread_worker *worker, | |
537 | struct kthread_work *work, | |
538 | struct list_head *pos) | |
539 | { | |
540 | lockdep_assert_held(&worker->lock); | |
541 | ||
542 | list_add_tail(&work->node, pos); | |
46f3d976 | 543 | work->worker = worker; |
9a2e03d8 TH |
544 | if (likely(worker->task)) |
545 | wake_up_process(worker->task); | |
546 | } | |
547 | ||
b56c0d89 TH |
548 | /** |
549 | * queue_kthread_work - queue a kthread_work | |
550 | * @worker: target kthread_worker | |
551 | * @work: kthread_work to queue | |
552 | * | |
553 | * Queue @work to work processor @task for async execution. @task | |
554 | * must have been created with kthread_worker_create(). Returns %true | |
555 | * if @work was successfully queued, %false if it was already pending. | |
556 | */ | |
557 | bool queue_kthread_work(struct kthread_worker *worker, | |
558 | struct kthread_work *work) | |
559 | { | |
560 | bool ret = false; | |
561 | unsigned long flags; | |
562 | ||
563 | spin_lock_irqsave(&worker->lock, flags); | |
564 | if (list_empty(&work->node)) { | |
9a2e03d8 | 565 | insert_kthread_work(worker, work, &worker->work_list); |
b56c0d89 TH |
566 | ret = true; |
567 | } | |
568 | spin_unlock_irqrestore(&worker->lock, flags); | |
569 | return ret; | |
570 | } | |
571 | EXPORT_SYMBOL_GPL(queue_kthread_work); | |
572 | ||
9a2e03d8 TH |
573 | struct kthread_flush_work { |
574 | struct kthread_work work; | |
575 | struct completion done; | |
576 | }; | |
577 | ||
578 | static void kthread_flush_work_fn(struct kthread_work *work) | |
579 | { | |
580 | struct kthread_flush_work *fwork = | |
581 | container_of(work, struct kthread_flush_work, work); | |
582 | complete(&fwork->done); | |
583 | } | |
584 | ||
b56c0d89 TH |
585 | /** |
586 | * flush_kthread_work - flush a kthread_work | |
587 | * @work: work to flush | |
588 | * | |
589 | * If @work is queued or executing, wait for it to finish execution. | |
590 | */ | |
591 | void flush_kthread_work(struct kthread_work *work) | |
592 | { | |
46f3d976 TH |
593 | struct kthread_flush_work fwork = { |
594 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
595 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
596 | }; | |
597 | struct kthread_worker *worker; | |
598 | bool noop = false; | |
599 | ||
600 | retry: | |
601 | worker = work->worker; | |
602 | if (!worker) | |
603 | return; | |
b56c0d89 | 604 | |
46f3d976 TH |
605 | spin_lock_irq(&worker->lock); |
606 | if (work->worker != worker) { | |
607 | spin_unlock_irq(&worker->lock); | |
608 | goto retry; | |
609 | } | |
b56c0d89 | 610 | |
46f3d976 TH |
611 | if (!list_empty(&work->node)) |
612 | insert_kthread_work(worker, &fwork.work, work->node.next); | |
613 | else if (worker->current_work == work) | |
614 | insert_kthread_work(worker, &fwork.work, worker->work_list.next); | |
615 | else | |
616 | noop = true; | |
b56c0d89 | 617 | |
46f3d976 | 618 | spin_unlock_irq(&worker->lock); |
b56c0d89 | 619 | |
46f3d976 TH |
620 | if (!noop) |
621 | wait_for_completion(&fwork.done); | |
b56c0d89 TH |
622 | } |
623 | EXPORT_SYMBOL_GPL(flush_kthread_work); | |
624 | ||
b56c0d89 TH |
625 | /** |
626 | * flush_kthread_worker - flush all current works on a kthread_worker | |
627 | * @worker: worker to flush | |
628 | * | |
629 | * Wait until all currently executing or pending works on @worker are | |
630 | * finished. | |
631 | */ | |
632 | void flush_kthread_worker(struct kthread_worker *worker) | |
633 | { | |
634 | struct kthread_flush_work fwork = { | |
635 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
636 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
637 | }; | |
638 | ||
639 | queue_kthread_work(worker, &fwork.work); | |
640 | wait_for_completion(&fwork.done); | |
641 | } | |
642 | EXPORT_SYMBOL_GPL(flush_kthread_worker); |