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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> |
cd42d559 | 20 | #include <linux/uaccess.h> |
ad8d75ff | 21 | #include <trace/events/sched.h> |
1da177e4 | 22 | |
73c27992 EB |
23 | static DEFINE_SPINLOCK(kthread_create_lock); |
24 | static LIST_HEAD(kthread_create_list); | |
25 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
26 | |
27 | struct kthread_create_info | |
28 | { | |
73c27992 | 29 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
30 | int (*threadfn)(void *data); |
31 | void *data; | |
207205a2 | 32 | int node; |
1da177e4 | 33 | |
73c27992 | 34 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 35 | struct task_struct *result; |
786235ee | 36 | struct completion *done; |
65f27f38 | 37 | |
73c27992 | 38 | struct list_head list; |
1da177e4 LT |
39 | }; |
40 | ||
63706172 | 41 | struct kthread { |
2a1d4460 TG |
42 | unsigned long flags; |
43 | unsigned int cpu; | |
82805ab7 | 44 | void *data; |
2a1d4460 | 45 | struct completion parked; |
63706172 | 46 | struct completion exited; |
1da177e4 LT |
47 | }; |
48 | ||
2a1d4460 TG |
49 | enum KTHREAD_BITS { |
50 | KTHREAD_IS_PER_CPU = 0, | |
51 | KTHREAD_SHOULD_STOP, | |
52 | KTHREAD_SHOULD_PARK, | |
53 | KTHREAD_IS_PARKED, | |
54 | }; | |
55 | ||
4ecdafc8 ON |
56 | #define __to_kthread(vfork) \ |
57 | container_of(vfork, struct kthread, exited) | |
58 | ||
59 | static inline struct kthread *to_kthread(struct task_struct *k) | |
60 | { | |
61 | return __to_kthread(k->vfork_done); | |
62 | } | |
63 | ||
64 | static struct kthread *to_live_kthread(struct task_struct *k) | |
65 | { | |
66 | struct completion *vfork = ACCESS_ONCE(k->vfork_done); | |
23196f2e | 67 | if (likely(vfork) && try_get_task_stack(k)) |
4ecdafc8 ON |
68 | return __to_kthread(vfork); |
69 | return NULL; | |
70 | } | |
1da177e4 | 71 | |
9e37bd30 RD |
72 | /** |
73 | * kthread_should_stop - should this kthread return now? | |
74 | * | |
72fd4a35 | 75 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
76 | * and this will return true. You should then return, and your return |
77 | * value will be passed through to kthread_stop(). | |
78 | */ | |
2a1d4460 | 79 | bool kthread_should_stop(void) |
1da177e4 | 80 | { |
2a1d4460 | 81 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
82 | } |
83 | EXPORT_SYMBOL(kthread_should_stop); | |
84 | ||
2a1d4460 TG |
85 | /** |
86 | * kthread_should_park - should this kthread park now? | |
87 | * | |
88 | * When someone calls kthread_park() on your kthread, it will be woken | |
89 | * and this will return true. You should then do the necessary | |
90 | * cleanup and call kthread_parkme() | |
91 | * | |
92 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
93 | * and in a park position. kthread_unpark() "restarts" the thread and | |
94 | * calls the thread function again. | |
95 | */ | |
96 | bool kthread_should_park(void) | |
97 | { | |
98 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags); | |
99 | } | |
18896451 | 100 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 101 | |
8a32c441 TH |
102 | /** |
103 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
104 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
105 | * | |
106 | * kthread_should_stop() for freezable kthreads, which will enter | |
107 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
108 | * freezer deadlock and freezable kthreads should use this function instead | |
109 | * of calling try_to_freeze() directly. | |
110 | */ | |
111 | bool kthread_freezable_should_stop(bool *was_frozen) | |
112 | { | |
113 | bool frozen = false; | |
114 | ||
115 | might_sleep(); | |
116 | ||
117 | if (unlikely(freezing(current))) | |
118 | frozen = __refrigerator(true); | |
119 | ||
120 | if (was_frozen) | |
121 | *was_frozen = frozen; | |
122 | ||
123 | return kthread_should_stop(); | |
124 | } | |
125 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
126 | ||
82805ab7 TH |
127 | /** |
128 | * kthread_data - return data value specified on kthread creation | |
129 | * @task: kthread task in question | |
130 | * | |
131 | * Return the data value specified when kthread @task was created. | |
132 | * The caller is responsible for ensuring the validity of @task when | |
133 | * calling this function. | |
134 | */ | |
135 | void *kthread_data(struct task_struct *task) | |
136 | { | |
137 | return to_kthread(task)->data; | |
138 | } | |
139 | ||
cd42d559 | 140 | /** |
e700591a | 141 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
142 | * @task: possible kthread task in question |
143 | * | |
144 | * @task could be a kthread task. Return the data value specified when it | |
145 | * was created if accessible. If @task isn't a kthread task or its data is | |
146 | * inaccessible for any reason, %NULL is returned. This function requires | |
147 | * that @task itself is safe to dereference. | |
148 | */ | |
e700591a | 149 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 TH |
150 | { |
151 | struct kthread *kthread = to_kthread(task); | |
152 | void *data = NULL; | |
153 | ||
154 | probe_kernel_read(&data, &kthread->data, sizeof(data)); | |
155 | return data; | |
156 | } | |
157 | ||
2a1d4460 TG |
158 | static void __kthread_parkme(struct kthread *self) |
159 | { | |
f2530dc7 | 160 | __set_current_state(TASK_PARKED); |
2a1d4460 TG |
161 | while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) { |
162 | if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags)) | |
163 | complete(&self->parked); | |
164 | schedule(); | |
f2530dc7 | 165 | __set_current_state(TASK_PARKED); |
2a1d4460 TG |
166 | } |
167 | clear_bit(KTHREAD_IS_PARKED, &self->flags); | |
168 | __set_current_state(TASK_RUNNING); | |
169 | } | |
170 | ||
171 | void kthread_parkme(void) | |
172 | { | |
173 | __kthread_parkme(to_kthread(current)); | |
174 | } | |
18896451 | 175 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 176 | |
1da177e4 LT |
177 | static int kthread(void *_create) |
178 | { | |
63706172 | 179 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 180 | struct kthread_create_info *create = _create; |
63706172 ON |
181 | int (*threadfn)(void *data) = create->threadfn; |
182 | void *data = create->data; | |
786235ee | 183 | struct completion *done; |
63706172 ON |
184 | struct kthread self; |
185 | int ret; | |
1da177e4 | 186 | |
2a1d4460 | 187 | self.flags = 0; |
82805ab7 | 188 | self.data = data; |
63706172 | 189 | init_completion(&self.exited); |
2a1d4460 | 190 | init_completion(&self.parked); |
63706172 | 191 | current->vfork_done = &self.exited; |
1da177e4 | 192 | |
786235ee TH |
193 | /* If user was SIGKILLed, I release the structure. */ |
194 | done = xchg(&create->done, NULL); | |
195 | if (!done) { | |
196 | kfree(create); | |
197 | do_exit(-EINTR); | |
198 | } | |
1da177e4 | 199 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 200 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 201 | create->result = current; |
786235ee | 202 | complete(done); |
1da177e4 LT |
203 | schedule(); |
204 | ||
63706172 | 205 | ret = -EINTR; |
1da177e4 | 206 | |
2a1d4460 TG |
207 | if (!test_bit(KTHREAD_SHOULD_STOP, &self.flags)) { |
208 | __kthread_parkme(&self); | |
209 | ret = threadfn(data); | |
210 | } | |
63706172 ON |
211 | /* we can't just return, we must preserve "self" on stack */ |
212 | do_exit(ret); | |
1da177e4 LT |
213 | } |
214 | ||
207205a2 ED |
215 | /* called from do_fork() to get node information for about to be created task */ |
216 | int tsk_fork_get_node(struct task_struct *tsk) | |
217 | { | |
218 | #ifdef CONFIG_NUMA | |
219 | if (tsk == kthreadd_task) | |
220 | return tsk->pref_node_fork; | |
221 | #endif | |
81c98869 | 222 | return NUMA_NO_NODE; |
207205a2 ED |
223 | } |
224 | ||
73c27992 | 225 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 226 | { |
1da177e4 LT |
227 | int pid; |
228 | ||
207205a2 ED |
229 | #ifdef CONFIG_NUMA |
230 | current->pref_node_fork = create->node; | |
231 | #endif | |
1da177e4 LT |
232 | /* We want our own signal handler (we take no signals by default). */ |
233 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 234 | if (pid < 0) { |
786235ee TH |
235 | /* If user was SIGKILLed, I release the structure. */ |
236 | struct completion *done = xchg(&create->done, NULL); | |
237 | ||
238 | if (!done) { | |
239 | kfree(create); | |
240 | return; | |
241 | } | |
1da177e4 | 242 | create->result = ERR_PTR(pid); |
786235ee | 243 | complete(done); |
cdd140bd | 244 | } |
1da177e4 LT |
245 | } |
246 | ||
9e37bd30 | 247 | /** |
207205a2 | 248 | * kthread_create_on_node - create a kthread. |
9e37bd30 RD |
249 | * @threadfn: the function to run until signal_pending(current). |
250 | * @data: data ptr for @threadfn. | |
e9f06986 | 251 | * @node: task and thread structures for the thread are allocated on this node |
9e37bd30 RD |
252 | * @namefmt: printf-style name for the thread. |
253 | * | |
254 | * Description: This helper function creates and names a kernel | |
255 | * thread. The thread will be stopped: use wake_up_process() to start | |
e9f06986 AM |
256 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and |
257 | * is affine to all CPUs. | |
9e37bd30 | 258 | * |
207205a2 | 259 | * If thread is going to be bound on a particular cpu, give its node |
e9f06986 | 260 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. |
9e37bd30 | 261 | * When woken, the thread will run @threadfn() with @data as its |
72fd4a35 | 262 | * argument. @threadfn() can either call do_exit() directly if it is a |
25985edc | 263 | * standalone thread for which no one will call kthread_stop(), or |
9e37bd30 RD |
264 | * return when 'kthread_should_stop()' is true (which means |
265 | * kthread_stop() has been called). The return value should be zero | |
266 | * or a negative error number; it will be passed to kthread_stop(). | |
267 | * | |
8fe6929c | 268 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). |
9e37bd30 | 269 | */ |
207205a2 | 270 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), |
2a1d4460 | 271 | void *data, int node, |
207205a2 ED |
272 | const char namefmt[], |
273 | ...) | |
1da177e4 | 274 | { |
786235ee TH |
275 | DECLARE_COMPLETION_ONSTACK(done); |
276 | struct task_struct *task; | |
277 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
278 | GFP_KERNEL); | |
279 | ||
280 | if (!create) | |
281 | return ERR_PTR(-ENOMEM); | |
282 | create->threadfn = threadfn; | |
283 | create->data = data; | |
284 | create->node = node; | |
285 | create->done = &done; | |
73c27992 EB |
286 | |
287 | spin_lock(&kthread_create_lock); | |
786235ee | 288 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
289 | spin_unlock(&kthread_create_lock); |
290 | ||
cbd9b67b | 291 | wake_up_process(kthreadd_task); |
786235ee TH |
292 | /* |
293 | * Wait for completion in killable state, for I might be chosen by | |
294 | * the OOM killer while kthreadd is trying to allocate memory for | |
295 | * new kernel thread. | |
296 | */ | |
297 | if (unlikely(wait_for_completion_killable(&done))) { | |
298 | /* | |
299 | * If I was SIGKILLed before kthreadd (or new kernel thread) | |
300 | * calls complete(), leave the cleanup of this structure to | |
301 | * that thread. | |
302 | */ | |
303 | if (xchg(&create->done, NULL)) | |
8fe6929c | 304 | return ERR_PTR(-EINTR); |
786235ee TH |
305 | /* |
306 | * kthreadd (or new kernel thread) will call complete() | |
307 | * shortly. | |
308 | */ | |
309 | wait_for_completion(&done); | |
310 | } | |
311 | task = create->result; | |
312 | if (!IS_ERR(task)) { | |
c9b5f501 | 313 | static const struct sched_param param = { .sched_priority = 0 }; |
1da177e4 | 314 | va_list args; |
1c99315b | 315 | |
1da177e4 | 316 | va_start(args, namefmt); |
786235ee | 317 | vsnprintf(task->comm, sizeof(task->comm), namefmt, args); |
1da177e4 | 318 | va_end(args); |
1c99315b ON |
319 | /* |
320 | * root may have changed our (kthreadd's) priority or CPU mask. | |
321 | * The kernel thread should not inherit these properties. | |
322 | */ | |
786235ee TH |
323 | sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
324 | set_cpus_allowed_ptr(task, cpu_all_mask); | |
1da177e4 | 325 | } |
786235ee TH |
326 | kfree(create); |
327 | return task; | |
1da177e4 | 328 | } |
207205a2 | 329 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 330 | |
25834c73 | 331 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
2a1d4460 | 332 | { |
25834c73 PZ |
333 | unsigned long flags; |
334 | ||
f2530dc7 TG |
335 | if (!wait_task_inactive(p, state)) { |
336 | WARN_ON(1); | |
337 | return; | |
338 | } | |
25834c73 | 339 | |
2a1d4460 | 340 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
341 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
342 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 343 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
344 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
345 | } | |
346 | ||
347 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) | |
348 | { | |
349 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
350 | } | |
351 | ||
352 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
353 | { | |
354 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
355 | } |
356 | ||
881232b7 PZ |
357 | /** |
358 | * kthread_bind - bind a just-created kthread to a cpu. | |
359 | * @p: thread created by kthread_create(). | |
360 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
361 | * | |
362 | * Description: This function is equivalent to set_cpus_allowed(), | |
363 | * except that @cpu doesn't need to be online, and the thread must be | |
364 | * stopped (i.e., just returned from kthread_create()). | |
365 | */ | |
366 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
367 | { | |
f2530dc7 | 368 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
369 | } |
370 | EXPORT_SYMBOL(kthread_bind); | |
371 | ||
2a1d4460 TG |
372 | /** |
373 | * kthread_create_on_cpu - Create a cpu bound kthread | |
374 | * @threadfn: the function to run until signal_pending(current). | |
375 | * @data: data ptr for @threadfn. | |
376 | * @cpu: The cpu on which the thread should be bound, | |
377 | * @namefmt: printf-style name for the thread. Format is restricted | |
378 | * to "name.*%u". Code fills in cpu number. | |
379 | * | |
380 | * Description: This helper function creates and names a kernel thread | |
381 | * The thread will be woken and put into park mode. | |
382 | */ | |
383 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
384 | void *data, unsigned int cpu, | |
385 | const char *namefmt) | |
386 | { | |
387 | struct task_struct *p; | |
388 | ||
10922838 | 389 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
390 | cpu); |
391 | if (IS_ERR(p)) | |
392 | return p; | |
a65d4096 PM |
393 | kthread_bind(p, cpu); |
394 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 TG |
395 | set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); |
396 | to_kthread(p)->cpu = cpu; | |
2a1d4460 TG |
397 | return p; |
398 | } | |
399 | ||
f2530dc7 TG |
400 | static void __kthread_unpark(struct task_struct *k, struct kthread *kthread) |
401 | { | |
402 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
403 | /* | |
404 | * We clear the IS_PARKED bit here as we don't wait | |
405 | * until the task has left the park code. So if we'd | |
406 | * park before that happens we'd see the IS_PARKED bit | |
407 | * which might be about to be cleared. | |
408 | */ | |
409 | if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) { | |
a65d4096 PM |
410 | /* |
411 | * Newly created kthread was parked when the CPU was offline. | |
412 | * The binding was lost and we need to set it again. | |
413 | */ | |
f2530dc7 TG |
414 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
415 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
416 | wake_up_state(k, TASK_PARKED); | |
417 | } | |
418 | } | |
419 | ||
2a1d4460 TG |
420 | /** |
421 | * kthread_unpark - unpark a thread created by kthread_create(). | |
422 | * @k: thread created by kthread_create(). | |
423 | * | |
424 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
425 | * waits for it to return. If the thread is marked percpu then its | |
426 | * bound to the cpu again. | |
427 | */ | |
428 | void kthread_unpark(struct task_struct *k) | |
429 | { | |
b5c5442b | 430 | struct kthread *kthread = to_live_kthread(k); |
2a1d4460 | 431 | |
23196f2e | 432 | if (kthread) { |
f2530dc7 | 433 | __kthread_unpark(k, kthread); |
23196f2e ON |
434 | put_task_stack(k); |
435 | } | |
2a1d4460 | 436 | } |
18896451 | 437 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
438 | |
439 | /** | |
440 | * kthread_park - park a thread created by kthread_create(). | |
441 | * @k: thread created by kthread_create(). | |
442 | * | |
443 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
444 | * waits for it to return. This can also be called after kthread_create() | |
445 | * instead of calling wake_up_process(): the thread will park without | |
446 | * calling threadfn(). | |
447 | * | |
448 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
449 | * If called by the kthread itself just the park bit is set. | |
450 | */ | |
451 | int kthread_park(struct task_struct *k) | |
452 | { | |
b5c5442b | 453 | struct kthread *kthread = to_live_kthread(k); |
2a1d4460 TG |
454 | int ret = -ENOSYS; |
455 | ||
456 | if (kthread) { | |
457 | if (!test_bit(KTHREAD_IS_PARKED, &kthread->flags)) { | |
458 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
459 | if (k != current) { | |
460 | wake_up_process(k); | |
461 | wait_for_completion(&kthread->parked); | |
462 | } | |
463 | } | |
23196f2e | 464 | put_task_stack(k); |
2a1d4460 TG |
465 | ret = 0; |
466 | } | |
2a1d4460 TG |
467 | return ret; |
468 | } | |
18896451 | 469 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 470 | |
9e37bd30 RD |
471 | /** |
472 | * kthread_stop - stop a thread created by kthread_create(). | |
473 | * @k: thread created by kthread_create(). | |
474 | * | |
475 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
476 | * waits for it to exit. This can also be called after kthread_create() |
477 | * instead of calling wake_up_process(): the thread will exit without | |
478 | * calling threadfn(). | |
479 | * | |
480 | * If threadfn() may call do_exit() itself, the caller must ensure | |
481 | * task_struct can't go away. | |
9e37bd30 RD |
482 | * |
483 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
484 | * was never called. | |
485 | */ | |
1da177e4 LT |
486 | int kthread_stop(struct task_struct *k) |
487 | { | |
b5c5442b | 488 | struct kthread *kthread; |
1da177e4 LT |
489 | int ret; |
490 | ||
0a16b607 | 491 | trace_sched_kthread_stop(k); |
b5c5442b ON |
492 | |
493 | get_task_struct(k); | |
494 | kthread = to_live_kthread(k); | |
2a1d4460 TG |
495 | if (kthread) { |
496 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
f2530dc7 | 497 | __kthread_unpark(k, kthread); |
63706172 ON |
498 | wake_up_process(k); |
499 | wait_for_completion(&kthread->exited); | |
23196f2e | 500 | put_task_stack(k); |
63706172 ON |
501 | } |
502 | ret = k->exit_code; | |
1da177e4 | 503 | put_task_struct(k); |
0a16b607 | 504 | |
b5c5442b | 505 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
506 | return ret; |
507 | } | |
52e92e57 | 508 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 509 | |
e804a4a4 | 510 | int kthreadd(void *unused) |
1da177e4 | 511 | { |
73c27992 | 512 | struct task_struct *tsk = current; |
1da177e4 | 513 | |
e804a4a4 | 514 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 515 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 516 | ignore_signals(tsk); |
1a2142af | 517 | set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa4 | 518 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 519 | |
34b087e4 | 520 | current->flags |= PF_NOFREEZE; |
73c27992 EB |
521 | |
522 | for (;;) { | |
523 | set_current_state(TASK_INTERRUPTIBLE); | |
524 | if (list_empty(&kthread_create_list)) | |
525 | schedule(); | |
526 | __set_current_state(TASK_RUNNING); | |
527 | ||
528 | spin_lock(&kthread_create_lock); | |
529 | while (!list_empty(&kthread_create_list)) { | |
530 | struct kthread_create_info *create; | |
531 | ||
532 | create = list_entry(kthread_create_list.next, | |
533 | struct kthread_create_info, list); | |
534 | list_del_init(&create->list); | |
535 | spin_unlock(&kthread_create_lock); | |
536 | ||
537 | create_kthread(create); | |
538 | ||
539 | spin_lock(&kthread_create_lock); | |
540 | } | |
541 | spin_unlock(&kthread_create_lock); | |
542 | } | |
543 | ||
544 | return 0; | |
545 | } | |
b56c0d89 | 546 | |
3989144f | 547 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
548 | const char *name, |
549 | struct lock_class_key *key) | |
550 | { | |
551 | spin_lock_init(&worker->lock); | |
552 | lockdep_set_class_and_name(&worker->lock, key, name); | |
553 | INIT_LIST_HEAD(&worker->work_list); | |
554 | worker->task = NULL; | |
555 | } | |
3989144f | 556 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 557 | |
b56c0d89 TH |
558 | /** |
559 | * kthread_worker_fn - kthread function to process kthread_worker | |
560 | * @worker_ptr: pointer to initialized kthread_worker | |
561 | * | |
562 | * This function can be used as @threadfn to kthread_create() or | |
563 | * kthread_run() with @worker_ptr argument pointing to an initialized | |
564 | * kthread_worker. The started kthread will process work_list until | |
565 | * the it is stopped with kthread_stop(). A kthread can also call | |
566 | * this function directly after extra initialization. | |
567 | * | |
568 | * Different kthreads can be used for the same kthread_worker as long | |
569 | * as there's only one kthread attached to it at any given time. A | |
570 | * kthread_worker without an attached kthread simply collects queued | |
571 | * kthread_works. | |
572 | */ | |
573 | int kthread_worker_fn(void *worker_ptr) | |
574 | { | |
575 | struct kthread_worker *worker = worker_ptr; | |
576 | struct kthread_work *work; | |
577 | ||
578 | WARN_ON(worker->task); | |
579 | worker->task = current; | |
580 | repeat: | |
581 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
582 | ||
583 | if (kthread_should_stop()) { | |
584 | __set_current_state(TASK_RUNNING); | |
585 | spin_lock_irq(&worker->lock); | |
586 | worker->task = NULL; | |
587 | spin_unlock_irq(&worker->lock); | |
588 | return 0; | |
589 | } | |
590 | ||
591 | work = NULL; | |
592 | spin_lock_irq(&worker->lock); | |
593 | if (!list_empty(&worker->work_list)) { | |
594 | work = list_first_entry(&worker->work_list, | |
595 | struct kthread_work, node); | |
596 | list_del_init(&work->node); | |
597 | } | |
46f3d976 | 598 | worker->current_work = work; |
b56c0d89 TH |
599 | spin_unlock_irq(&worker->lock); |
600 | ||
601 | if (work) { | |
602 | __set_current_state(TASK_RUNNING); | |
603 | work->func(work); | |
b56c0d89 TH |
604 | } else if (!freezing(current)) |
605 | schedule(); | |
606 | ||
607 | try_to_freeze(); | |
608 | goto repeat; | |
609 | } | |
610 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
611 | ||
9a2e03d8 | 612 | /* insert @work before @pos in @worker */ |
3989144f | 613 | static void kthread_insert_work(struct kthread_worker *worker, |
9a2e03d8 TH |
614 | struct kthread_work *work, |
615 | struct list_head *pos) | |
616 | { | |
617 | lockdep_assert_held(&worker->lock); | |
618 | ||
619 | list_add_tail(&work->node, pos); | |
46f3d976 | 620 | work->worker = worker; |
ed1403ec | 621 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
622 | wake_up_process(worker->task); |
623 | } | |
624 | ||
b56c0d89 | 625 | /** |
3989144f | 626 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
627 | * @worker: target kthread_worker |
628 | * @work: kthread_work to queue | |
629 | * | |
630 | * Queue @work to work processor @task for async execution. @task | |
631 | * must have been created with kthread_worker_create(). Returns %true | |
632 | * if @work was successfully queued, %false if it was already pending. | |
633 | */ | |
3989144f | 634 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
635 | struct kthread_work *work) |
636 | { | |
637 | bool ret = false; | |
638 | unsigned long flags; | |
639 | ||
640 | spin_lock_irqsave(&worker->lock, flags); | |
641 | if (list_empty(&work->node)) { | |
3989144f | 642 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
643 | ret = true; |
644 | } | |
645 | spin_unlock_irqrestore(&worker->lock, flags); | |
646 | return ret; | |
647 | } | |
3989144f | 648 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 649 | |
9a2e03d8 TH |
650 | struct kthread_flush_work { |
651 | struct kthread_work work; | |
652 | struct completion done; | |
653 | }; | |
654 | ||
655 | static void kthread_flush_work_fn(struct kthread_work *work) | |
656 | { | |
657 | struct kthread_flush_work *fwork = | |
658 | container_of(work, struct kthread_flush_work, work); | |
659 | complete(&fwork->done); | |
660 | } | |
661 | ||
b56c0d89 | 662 | /** |
3989144f | 663 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
664 | * @work: work to flush |
665 | * | |
666 | * If @work is queued or executing, wait for it to finish execution. | |
667 | */ | |
3989144f | 668 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 669 | { |
46f3d976 TH |
670 | struct kthread_flush_work fwork = { |
671 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
672 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
673 | }; | |
674 | struct kthread_worker *worker; | |
675 | bool noop = false; | |
676 | ||
677 | retry: | |
678 | worker = work->worker; | |
679 | if (!worker) | |
680 | return; | |
b56c0d89 | 681 | |
46f3d976 TH |
682 | spin_lock_irq(&worker->lock); |
683 | if (work->worker != worker) { | |
684 | spin_unlock_irq(&worker->lock); | |
685 | goto retry; | |
686 | } | |
b56c0d89 | 687 | |
46f3d976 | 688 | if (!list_empty(&work->node)) |
3989144f | 689 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 690 | else if (worker->current_work == work) |
3989144f PM |
691 | kthread_insert_work(worker, &fwork.work, |
692 | worker->work_list.next); | |
46f3d976 TH |
693 | else |
694 | noop = true; | |
b56c0d89 | 695 | |
46f3d976 | 696 | spin_unlock_irq(&worker->lock); |
b56c0d89 | 697 | |
46f3d976 TH |
698 | if (!noop) |
699 | wait_for_completion(&fwork.done); | |
b56c0d89 | 700 | } |
3989144f | 701 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 702 | |
b56c0d89 | 703 | /** |
3989144f | 704 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
705 | * @worker: worker to flush |
706 | * | |
707 | * Wait until all currently executing or pending works on @worker are | |
708 | * finished. | |
709 | */ | |
3989144f | 710 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
711 | { |
712 | struct kthread_flush_work fwork = { | |
713 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
714 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
715 | }; | |
716 | ||
3989144f | 717 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
718 | wait_for_completion(&fwork.done); |
719 | } | |
3989144f | 720 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |