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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* Kernel thread helper functions. |
3 | * Copyright (C) 2004 IBM Corporation, Rusty Russell. | |
9bf5b9eb | 4 | * Copyright (C) 2009 Red Hat, Inc. |
1da177e4 | 5 | * |
73c27992 | 6 | * Creation is done via kthreadd, so that we get a clean environment |
1da177e4 LT |
7 | * even if we're invoked from userspace (think modprobe, hotplug cpu, |
8 | * etc.). | |
9 | */ | |
ae7e81c0 | 10 | #include <uapi/linux/sched/types.h> |
9bf5b9eb CH |
11 | #include <linux/mm.h> |
12 | #include <linux/mmu_context.h> | |
1da177e4 | 13 | #include <linux/sched.h> |
9bf5b9eb | 14 | #include <linux/sched/mm.h> |
29930025 | 15 | #include <linux/sched/task.h> |
1da177e4 LT |
16 | #include <linux/kthread.h> |
17 | #include <linux/completion.h> | |
18 | #include <linux/err.h> | |
8af0c18a | 19 | #include <linux/cgroup.h> |
58568d2a | 20 | #include <linux/cpuset.h> |
1da177e4 LT |
21 | #include <linux/unistd.h> |
22 | #include <linux/file.h> | |
9984de1a | 23 | #include <linux/export.h> |
97d1f15b | 24 | #include <linux/mutex.h> |
b56c0d89 TH |
25 | #include <linux/slab.h> |
26 | #include <linux/freezer.h> | |
a74fb73c | 27 | #include <linux/ptrace.h> |
cd42d559 | 28 | #include <linux/uaccess.h> |
98fa15f3 | 29 | #include <linux/numa.h> |
9cc5b865 | 30 | #include <linux/sched/isolation.h> |
ad8d75ff | 31 | #include <trace/events/sched.h> |
1da177e4 | 32 | |
9bf5b9eb | 33 | |
73c27992 EB |
34 | static DEFINE_SPINLOCK(kthread_create_lock); |
35 | static LIST_HEAD(kthread_create_list); | |
36 | struct task_struct *kthreadd_task; | |
1da177e4 LT |
37 | |
38 | struct kthread_create_info | |
39 | { | |
73c27992 | 40 | /* Information passed to kthread() from kthreadd. */ |
1da177e4 LT |
41 | int (*threadfn)(void *data); |
42 | void *data; | |
207205a2 | 43 | int node; |
1da177e4 | 44 | |
73c27992 | 45 | /* Result passed back to kthread_create() from kthreadd. */ |
1da177e4 | 46 | struct task_struct *result; |
786235ee | 47 | struct completion *done; |
65f27f38 | 48 | |
73c27992 | 49 | struct list_head list; |
1da177e4 LT |
50 | }; |
51 | ||
63706172 | 52 | struct kthread { |
2a1d4460 TG |
53 | unsigned long flags; |
54 | unsigned int cpu; | |
52782c92 | 55 | int (*threadfn)(void *); |
82805ab7 | 56 | void *data; |
37c54f9b | 57 | mm_segment_t oldfs; |
2a1d4460 | 58 | struct completion parked; |
63706172 | 59 | struct completion exited; |
0b508bc9 | 60 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
61 | struct cgroup_subsys_state *blkcg_css; |
62 | #endif | |
1da177e4 LT |
63 | }; |
64 | ||
2a1d4460 TG |
65 | enum KTHREAD_BITS { |
66 | KTHREAD_IS_PER_CPU = 0, | |
67 | KTHREAD_SHOULD_STOP, | |
68 | KTHREAD_SHOULD_PARK, | |
2a1d4460 TG |
69 | }; |
70 | ||
1da5c46f ON |
71 | static inline void set_kthread_struct(void *kthread) |
72 | { | |
73 | /* | |
74 | * We abuse ->set_child_tid to avoid the new member and because it | |
75 | * can't be wrongly copied by copy_process(). We also rely on fact | |
76 | * that the caller can't exec, so PF_KTHREAD can't be cleared. | |
77 | */ | |
78 | current->set_child_tid = (__force void __user *)kthread; | |
79 | } | |
4ecdafc8 ON |
80 | |
81 | static inline struct kthread *to_kthread(struct task_struct *k) | |
82 | { | |
1da5c46f ON |
83 | WARN_ON(!(k->flags & PF_KTHREAD)); |
84 | return (__force void *)k->set_child_tid; | |
4ecdafc8 ON |
85 | } |
86 | ||
1da5c46f ON |
87 | void free_kthread_struct(struct task_struct *k) |
88 | { | |
05e3db95 SL |
89 | struct kthread *kthread; |
90 | ||
1da5c46f ON |
91 | /* |
92 | * Can be NULL if this kthread was created by kernel_thread() | |
93 | * or if kmalloc() in kthread() failed. | |
94 | */ | |
05e3db95 | 95 | kthread = to_kthread(k); |
0b508bc9 | 96 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
97 | WARN_ON_ONCE(kthread && kthread->blkcg_css); |
98 | #endif | |
99 | kfree(kthread); | |
1da5c46f ON |
100 | } |
101 | ||
9e37bd30 RD |
102 | /** |
103 | * kthread_should_stop - should this kthread return now? | |
104 | * | |
72fd4a35 | 105 | * When someone calls kthread_stop() on your kthread, it will be woken |
9e37bd30 RD |
106 | * and this will return true. You should then return, and your return |
107 | * value will be passed through to kthread_stop(). | |
108 | */ | |
2a1d4460 | 109 | bool kthread_should_stop(void) |
1da177e4 | 110 | { |
2a1d4460 | 111 | return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
1da177e4 LT |
112 | } |
113 | EXPORT_SYMBOL(kthread_should_stop); | |
114 | ||
0121805d MK |
115 | bool __kthread_should_park(struct task_struct *k) |
116 | { | |
117 | return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); | |
118 | } | |
119 | EXPORT_SYMBOL_GPL(__kthread_should_park); | |
120 | ||
2a1d4460 TG |
121 | /** |
122 | * kthread_should_park - should this kthread park now? | |
123 | * | |
124 | * When someone calls kthread_park() on your kthread, it will be woken | |
125 | * and this will return true. You should then do the necessary | |
126 | * cleanup and call kthread_parkme() | |
127 | * | |
128 | * Similar to kthread_should_stop(), but this keeps the thread alive | |
129 | * and in a park position. kthread_unpark() "restarts" the thread and | |
130 | * calls the thread function again. | |
131 | */ | |
132 | bool kthread_should_park(void) | |
133 | { | |
0121805d | 134 | return __kthread_should_park(current); |
2a1d4460 | 135 | } |
18896451 | 136 | EXPORT_SYMBOL_GPL(kthread_should_park); |
2a1d4460 | 137 | |
8a32c441 TH |
138 | /** |
139 | * kthread_freezable_should_stop - should this freezable kthread return now? | |
140 | * @was_frozen: optional out parameter, indicates whether %current was frozen | |
141 | * | |
142 | * kthread_should_stop() for freezable kthreads, which will enter | |
143 | * refrigerator if necessary. This function is safe from kthread_stop() / | |
144 | * freezer deadlock and freezable kthreads should use this function instead | |
145 | * of calling try_to_freeze() directly. | |
146 | */ | |
147 | bool kthread_freezable_should_stop(bool *was_frozen) | |
148 | { | |
149 | bool frozen = false; | |
150 | ||
151 | might_sleep(); | |
152 | ||
153 | if (unlikely(freezing(current))) | |
154 | frozen = __refrigerator(true); | |
155 | ||
156 | if (was_frozen) | |
157 | *was_frozen = frozen; | |
158 | ||
159 | return kthread_should_stop(); | |
160 | } | |
161 | EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); | |
162 | ||
52782c92 BF |
163 | /** |
164 | * kthread_func - return the function specified on kthread creation | |
165 | * @task: kthread task in question | |
166 | * | |
167 | * Returns NULL if the task is not a kthread. | |
168 | */ | |
169 | void *kthread_func(struct task_struct *task) | |
170 | { | |
171 | if (task->flags & PF_KTHREAD) | |
172 | return to_kthread(task)->threadfn; | |
173 | return NULL; | |
174 | } | |
175 | EXPORT_SYMBOL_GPL(kthread_func); | |
176 | ||
82805ab7 TH |
177 | /** |
178 | * kthread_data - return data value specified on kthread creation | |
179 | * @task: kthread task in question | |
180 | * | |
181 | * Return the data value specified when kthread @task was created. | |
182 | * The caller is responsible for ensuring the validity of @task when | |
183 | * calling this function. | |
184 | */ | |
185 | void *kthread_data(struct task_struct *task) | |
186 | { | |
187 | return to_kthread(task)->data; | |
188 | } | |
52782c92 | 189 | EXPORT_SYMBOL_GPL(kthread_data); |
82805ab7 | 190 | |
cd42d559 | 191 | /** |
e700591a | 192 | * kthread_probe_data - speculative version of kthread_data() |
cd42d559 TH |
193 | * @task: possible kthread task in question |
194 | * | |
195 | * @task could be a kthread task. Return the data value specified when it | |
196 | * was created if accessible. If @task isn't a kthread task or its data is | |
197 | * inaccessible for any reason, %NULL is returned. This function requires | |
198 | * that @task itself is safe to dereference. | |
199 | */ | |
e700591a | 200 | void *kthread_probe_data(struct task_struct *task) |
cd42d559 TH |
201 | { |
202 | struct kthread *kthread = to_kthread(task); | |
203 | void *data = NULL; | |
204 | ||
fe557319 | 205 | copy_from_kernel_nofault(&data, &kthread->data, sizeof(data)); |
cd42d559 TH |
206 | return data; |
207 | } | |
208 | ||
2a1d4460 TG |
209 | static void __kthread_parkme(struct kthread *self) |
210 | { | |
741a76b3 | 211 | for (;;) { |
1cef1150 PZ |
212 | /* |
213 | * TASK_PARKED is a special state; we must serialize against | |
214 | * possible pending wakeups to avoid store-store collisions on | |
215 | * task->state. | |
216 | * | |
217 | * Such a collision might possibly result in the task state | |
218 | * changin from TASK_PARKED and us failing the | |
219 | * wait_task_inactive() in kthread_park(). | |
220 | */ | |
221 | set_special_state(TASK_PARKED); | |
741a76b3 PZ |
222 | if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) |
223 | break; | |
1cef1150 | 224 | |
26c7295b LC |
225 | /* |
226 | * Thread is going to call schedule(), do not preempt it, | |
227 | * or the caller of kthread_park() may spend more time in | |
228 | * wait_task_inactive(). | |
229 | */ | |
230 | preempt_disable(); | |
f83ee19b | 231 | complete(&self->parked); |
26c7295b LC |
232 | schedule_preempt_disabled(); |
233 | preempt_enable(); | |
2a1d4460 | 234 | } |
2a1d4460 TG |
235 | __set_current_state(TASK_RUNNING); |
236 | } | |
237 | ||
238 | void kthread_parkme(void) | |
239 | { | |
240 | __kthread_parkme(to_kthread(current)); | |
241 | } | |
18896451 | 242 | EXPORT_SYMBOL_GPL(kthread_parkme); |
2a1d4460 | 243 | |
1da177e4 LT |
244 | static int kthread(void *_create) |
245 | { | |
63706172 | 246 | /* Copy data: it's on kthread's stack */ |
1da177e4 | 247 | struct kthread_create_info *create = _create; |
63706172 ON |
248 | int (*threadfn)(void *data) = create->threadfn; |
249 | void *data = create->data; | |
786235ee | 250 | struct completion *done; |
1da5c46f | 251 | struct kthread *self; |
63706172 | 252 | int ret; |
1da177e4 | 253 | |
e10237cc | 254 | self = kzalloc(sizeof(*self), GFP_KERNEL); |
1da5c46f | 255 | set_kthread_struct(self); |
1da177e4 | 256 | |
786235ee TH |
257 | /* If user was SIGKILLed, I release the structure. */ |
258 | done = xchg(&create->done, NULL); | |
259 | if (!done) { | |
260 | kfree(create); | |
261 | do_exit(-EINTR); | |
262 | } | |
1da5c46f ON |
263 | |
264 | if (!self) { | |
265 | create->result = ERR_PTR(-ENOMEM); | |
266 | complete(done); | |
267 | do_exit(-ENOMEM); | |
268 | } | |
269 | ||
52782c92 | 270 | self->threadfn = threadfn; |
1da5c46f ON |
271 | self->data = data; |
272 | init_completion(&self->exited); | |
273 | init_completion(&self->parked); | |
274 | current->vfork_done = &self->exited; | |
275 | ||
1da177e4 | 276 | /* OK, tell user we're spawned, wait for stop or wakeup */ |
a076e4bc | 277 | __set_current_state(TASK_UNINTERRUPTIBLE); |
3217ab97 | 278 | create->result = current; |
26c7295b LC |
279 | /* |
280 | * Thread is going to call schedule(), do not preempt it, | |
281 | * or the creator may spend more time in wait_task_inactive(). | |
282 | */ | |
283 | preempt_disable(); | |
786235ee | 284 | complete(done); |
26c7295b LC |
285 | schedule_preempt_disabled(); |
286 | preempt_enable(); | |
1da177e4 | 287 | |
63706172 | 288 | ret = -EINTR; |
1da5c46f | 289 | if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
77f88796 | 290 | cgroup_kthread_ready(); |
1da5c46f | 291 | __kthread_parkme(self); |
2a1d4460 TG |
292 | ret = threadfn(data); |
293 | } | |
63706172 | 294 | do_exit(ret); |
1da177e4 LT |
295 | } |
296 | ||
207205a2 ED |
297 | /* called from do_fork() to get node information for about to be created task */ |
298 | int tsk_fork_get_node(struct task_struct *tsk) | |
299 | { | |
300 | #ifdef CONFIG_NUMA | |
301 | if (tsk == kthreadd_task) | |
302 | return tsk->pref_node_fork; | |
303 | #endif | |
81c98869 | 304 | return NUMA_NO_NODE; |
207205a2 ED |
305 | } |
306 | ||
73c27992 | 307 | static void create_kthread(struct kthread_create_info *create) |
1da177e4 | 308 | { |
1da177e4 LT |
309 | int pid; |
310 | ||
207205a2 ED |
311 | #ifdef CONFIG_NUMA |
312 | current->pref_node_fork = create->node; | |
313 | #endif | |
1da177e4 LT |
314 | /* We want our own signal handler (we take no signals by default). */ |
315 | pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); | |
cdd140bd | 316 | if (pid < 0) { |
786235ee TH |
317 | /* If user was SIGKILLed, I release the structure. */ |
318 | struct completion *done = xchg(&create->done, NULL); | |
319 | ||
320 | if (!done) { | |
321 | kfree(create); | |
322 | return; | |
323 | } | |
1da177e4 | 324 | create->result = ERR_PTR(pid); |
786235ee | 325 | complete(done); |
cdd140bd | 326 | } |
1da177e4 LT |
327 | } |
328 | ||
c0b942a7 NI |
329 | static __printf(4, 0) |
330 | struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), | |
255451e4 PM |
331 | void *data, int node, |
332 | const char namefmt[], | |
333 | va_list args) | |
1da177e4 | 334 | { |
786235ee TH |
335 | DECLARE_COMPLETION_ONSTACK(done); |
336 | struct task_struct *task; | |
337 | struct kthread_create_info *create = kmalloc(sizeof(*create), | |
338 | GFP_KERNEL); | |
339 | ||
340 | if (!create) | |
341 | return ERR_PTR(-ENOMEM); | |
342 | create->threadfn = threadfn; | |
343 | create->data = data; | |
344 | create->node = node; | |
345 | create->done = &done; | |
73c27992 EB |
346 | |
347 | spin_lock(&kthread_create_lock); | |
786235ee | 348 | list_add_tail(&create->list, &kthread_create_list); |
73c27992 EB |
349 | spin_unlock(&kthread_create_lock); |
350 | ||
cbd9b67b | 351 | wake_up_process(kthreadd_task); |
786235ee TH |
352 | /* |
353 | * Wait for completion in killable state, for I might be chosen by | |
354 | * the OOM killer while kthreadd is trying to allocate memory for | |
355 | * new kernel thread. | |
356 | */ | |
357 | if (unlikely(wait_for_completion_killable(&done))) { | |
358 | /* | |
359 | * If I was SIGKILLed before kthreadd (or new kernel thread) | |
360 | * calls complete(), leave the cleanup of this structure to | |
361 | * that thread. | |
362 | */ | |
363 | if (xchg(&create->done, NULL)) | |
8fe6929c | 364 | return ERR_PTR(-EINTR); |
786235ee TH |
365 | /* |
366 | * kthreadd (or new kernel thread) will call complete() | |
367 | * shortly. | |
368 | */ | |
369 | wait_for_completion(&done); | |
370 | } | |
371 | task = create->result; | |
372 | if (!IS_ERR(task)) { | |
c9b5f501 | 373 | static const struct sched_param param = { .sched_priority = 0 }; |
3e536e22 | 374 | char name[TASK_COMM_LEN]; |
1c99315b | 375 | |
3e536e22 SD |
376 | /* |
377 | * task is already visible to other tasks, so updating | |
378 | * COMM must be protected. | |
379 | */ | |
380 | vsnprintf(name, sizeof(name), namefmt, args); | |
381 | set_task_comm(task, name); | |
1c99315b ON |
382 | /* |
383 | * root may have changed our (kthreadd's) priority or CPU mask. | |
384 | * The kernel thread should not inherit these properties. | |
385 | */ | |
786235ee | 386 | sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); |
9cc5b865 MT |
387 | set_cpus_allowed_ptr(task, |
388 | housekeeping_cpumask(HK_FLAG_KTHREAD)); | |
1da177e4 | 389 | } |
786235ee TH |
390 | kfree(create); |
391 | return task; | |
1da177e4 | 392 | } |
255451e4 PM |
393 | |
394 | /** | |
395 | * kthread_create_on_node - create a kthread. | |
396 | * @threadfn: the function to run until signal_pending(current). | |
397 | * @data: data ptr for @threadfn. | |
398 | * @node: task and thread structures for the thread are allocated on this node | |
399 | * @namefmt: printf-style name for the thread. | |
400 | * | |
401 | * Description: This helper function creates and names a kernel | |
402 | * thread. The thread will be stopped: use wake_up_process() to start | |
403 | * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and | |
404 | * is affine to all CPUs. | |
405 | * | |
406 | * If thread is going to be bound on a particular cpu, give its node | |
407 | * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. | |
408 | * When woken, the thread will run @threadfn() with @data as its | |
409 | * argument. @threadfn() can either call do_exit() directly if it is a | |
410 | * standalone thread for which no one will call kthread_stop(), or | |
411 | * return when 'kthread_should_stop()' is true (which means | |
412 | * kthread_stop() has been called). The return value should be zero | |
413 | * or a negative error number; it will be passed to kthread_stop(). | |
414 | * | |
415 | * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). | |
416 | */ | |
417 | struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), | |
418 | void *data, int node, | |
419 | const char namefmt[], | |
420 | ...) | |
421 | { | |
422 | struct task_struct *task; | |
423 | va_list args; | |
424 | ||
425 | va_start(args, namefmt); | |
426 | task = __kthread_create_on_node(threadfn, data, node, namefmt, args); | |
427 | va_end(args); | |
428 | ||
429 | return task; | |
430 | } | |
207205a2 | 431 | EXPORT_SYMBOL(kthread_create_on_node); |
1da177e4 | 432 | |
25834c73 | 433 | static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
2a1d4460 | 434 | { |
25834c73 PZ |
435 | unsigned long flags; |
436 | ||
f2530dc7 TG |
437 | if (!wait_task_inactive(p, state)) { |
438 | WARN_ON(1); | |
439 | return; | |
440 | } | |
25834c73 | 441 | |
2a1d4460 | 442 | /* It's safe because the task is inactive. */ |
25834c73 PZ |
443 | raw_spin_lock_irqsave(&p->pi_lock, flags); |
444 | do_set_cpus_allowed(p, mask); | |
14a40ffc | 445 | p->flags |= PF_NO_SETAFFINITY; |
25834c73 PZ |
446 | raw_spin_unlock_irqrestore(&p->pi_lock, flags); |
447 | } | |
448 | ||
449 | static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) | |
450 | { | |
451 | __kthread_bind_mask(p, cpumask_of(cpu), state); | |
452 | } | |
453 | ||
454 | void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) | |
455 | { | |
456 | __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); | |
2a1d4460 TG |
457 | } |
458 | ||
881232b7 PZ |
459 | /** |
460 | * kthread_bind - bind a just-created kthread to a cpu. | |
461 | * @p: thread created by kthread_create(). | |
462 | * @cpu: cpu (might not be online, must be possible) for @k to run on. | |
463 | * | |
464 | * Description: This function is equivalent to set_cpus_allowed(), | |
465 | * except that @cpu doesn't need to be online, and the thread must be | |
466 | * stopped (i.e., just returned from kthread_create()). | |
467 | */ | |
468 | void kthread_bind(struct task_struct *p, unsigned int cpu) | |
469 | { | |
f2530dc7 | 470 | __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
881232b7 PZ |
471 | } |
472 | EXPORT_SYMBOL(kthread_bind); | |
473 | ||
2a1d4460 TG |
474 | /** |
475 | * kthread_create_on_cpu - Create a cpu bound kthread | |
476 | * @threadfn: the function to run until signal_pending(current). | |
477 | * @data: data ptr for @threadfn. | |
478 | * @cpu: The cpu on which the thread should be bound, | |
479 | * @namefmt: printf-style name for the thread. Format is restricted | |
480 | * to "name.*%u". Code fills in cpu number. | |
481 | * | |
482 | * Description: This helper function creates and names a kernel thread | |
2a1d4460 TG |
483 | */ |
484 | struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), | |
485 | void *data, unsigned int cpu, | |
486 | const char *namefmt) | |
487 | { | |
488 | struct task_struct *p; | |
489 | ||
10922838 | 490 | p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
2a1d4460 TG |
491 | cpu); |
492 | if (IS_ERR(p)) | |
493 | return p; | |
a65d4096 PM |
494 | kthread_bind(p, cpu); |
495 | /* CPU hotplug need to bind once again when unparking the thread. */ | |
2a1d4460 TG |
496 | set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); |
497 | to_kthread(p)->cpu = cpu; | |
2a1d4460 TG |
498 | return p; |
499 | } | |
500 | ||
cf380a4a ON |
501 | /** |
502 | * kthread_unpark - unpark a thread created by kthread_create(). | |
503 | * @k: thread created by kthread_create(). | |
504 | * | |
505 | * Sets kthread_should_park() for @k to return false, wakes it, and | |
506 | * waits for it to return. If the thread is marked percpu then its | |
507 | * bound to the cpu again. | |
508 | */ | |
509 | void kthread_unpark(struct task_struct *k) | |
f2530dc7 | 510 | { |
cf380a4a ON |
511 | struct kthread *kthread = to_kthread(k); |
512 | ||
f2530dc7 | 513 | /* |
85f1abe0 PZ |
514 | * Newly created kthread was parked when the CPU was offline. |
515 | * The binding was lost and we need to set it again. | |
f2530dc7 | 516 | */ |
85f1abe0 PZ |
517 | if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) |
518 | __kthread_bind(k, kthread->cpu, TASK_PARKED); | |
519 | ||
520 | clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); | |
1cef1150 PZ |
521 | /* |
522 | * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. | |
523 | */ | |
85f1abe0 | 524 | wake_up_state(k, TASK_PARKED); |
f2530dc7 | 525 | } |
18896451 | 526 | EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d4460 TG |
527 | |
528 | /** | |
529 | * kthread_park - park a thread created by kthread_create(). | |
530 | * @k: thread created by kthread_create(). | |
531 | * | |
532 | * Sets kthread_should_park() for @k to return true, wakes it, and | |
533 | * waits for it to return. This can also be called after kthread_create() | |
534 | * instead of calling wake_up_process(): the thread will park without | |
535 | * calling threadfn(). | |
536 | * | |
537 | * Returns 0 if the thread is parked, -ENOSYS if the thread exited. | |
538 | * If called by the kthread itself just the park bit is set. | |
539 | */ | |
540 | int kthread_park(struct task_struct *k) | |
541 | { | |
cf380a4a ON |
542 | struct kthread *kthread = to_kthread(k); |
543 | ||
544 | if (WARN_ON(k->flags & PF_EXITING)) | |
545 | return -ENOSYS; | |
546 | ||
f83ee19b PZ |
547 | if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) |
548 | return -EBUSY; | |
549 | ||
85f1abe0 PZ |
550 | set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
551 | if (k != current) { | |
552 | wake_up_process(k); | |
1cef1150 PZ |
553 | /* |
554 | * Wait for __kthread_parkme() to complete(), this means we | |
555 | * _will_ have TASK_PARKED and are about to call schedule(). | |
556 | */ | |
85f1abe0 | 557 | wait_for_completion(&kthread->parked); |
1cef1150 PZ |
558 | /* |
559 | * Now wait for that schedule() to complete and the task to | |
560 | * get scheduled out. | |
561 | */ | |
562 | WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED)); | |
2a1d4460 | 563 | } |
cf380a4a ON |
564 | |
565 | return 0; | |
2a1d4460 | 566 | } |
18896451 | 567 | EXPORT_SYMBOL_GPL(kthread_park); |
2a1d4460 | 568 | |
9e37bd30 RD |
569 | /** |
570 | * kthread_stop - stop a thread created by kthread_create(). | |
571 | * @k: thread created by kthread_create(). | |
572 | * | |
573 | * Sets kthread_should_stop() for @k to return true, wakes it, and | |
9ae26027 ON |
574 | * waits for it to exit. This can also be called after kthread_create() |
575 | * instead of calling wake_up_process(): the thread will exit without | |
576 | * calling threadfn(). | |
577 | * | |
578 | * If threadfn() may call do_exit() itself, the caller must ensure | |
579 | * task_struct can't go away. | |
9e37bd30 RD |
580 | * |
581 | * Returns the result of threadfn(), or %-EINTR if wake_up_process() | |
582 | * was never called. | |
583 | */ | |
1da177e4 LT |
584 | int kthread_stop(struct task_struct *k) |
585 | { | |
b5c5442b | 586 | struct kthread *kthread; |
1da177e4 LT |
587 | int ret; |
588 | ||
0a16b607 | 589 | trace_sched_kthread_stop(k); |
b5c5442b ON |
590 | |
591 | get_task_struct(k); | |
efb29fbf ON |
592 | kthread = to_kthread(k); |
593 | set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); | |
cf380a4a | 594 | kthread_unpark(k); |
efb29fbf ON |
595 | wake_up_process(k); |
596 | wait_for_completion(&kthread->exited); | |
63706172 | 597 | ret = k->exit_code; |
1da177e4 | 598 | put_task_struct(k); |
0a16b607 | 599 | |
b5c5442b | 600 | trace_sched_kthread_stop_ret(ret); |
1da177e4 LT |
601 | return ret; |
602 | } | |
52e92e57 | 603 | EXPORT_SYMBOL(kthread_stop); |
1da177e4 | 604 | |
e804a4a4 | 605 | int kthreadd(void *unused) |
1da177e4 | 606 | { |
73c27992 | 607 | struct task_struct *tsk = current; |
1da177e4 | 608 | |
e804a4a4 | 609 | /* Setup a clean context for our children to inherit. */ |
73c27992 | 610 | set_task_comm(tsk, "kthreadd"); |
10ab825b | 611 | ignore_signals(tsk); |
9cc5b865 | 612 | set_cpus_allowed_ptr(tsk, housekeeping_cpumask(HK_FLAG_KTHREAD)); |
aee4faa4 | 613 | set_mems_allowed(node_states[N_MEMORY]); |
73c27992 | 614 | |
34b087e4 | 615 | current->flags |= PF_NOFREEZE; |
77f88796 | 616 | cgroup_init_kthreadd(); |
73c27992 EB |
617 | |
618 | for (;;) { | |
619 | set_current_state(TASK_INTERRUPTIBLE); | |
620 | if (list_empty(&kthread_create_list)) | |
621 | schedule(); | |
622 | __set_current_state(TASK_RUNNING); | |
623 | ||
624 | spin_lock(&kthread_create_lock); | |
625 | while (!list_empty(&kthread_create_list)) { | |
626 | struct kthread_create_info *create; | |
627 | ||
628 | create = list_entry(kthread_create_list.next, | |
629 | struct kthread_create_info, list); | |
630 | list_del_init(&create->list); | |
631 | spin_unlock(&kthread_create_lock); | |
632 | ||
633 | create_kthread(create); | |
634 | ||
635 | spin_lock(&kthread_create_lock); | |
636 | } | |
637 | spin_unlock(&kthread_create_lock); | |
638 | } | |
639 | ||
640 | return 0; | |
641 | } | |
b56c0d89 | 642 | |
3989144f | 643 | void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1 YZ |
644 | const char *name, |
645 | struct lock_class_key *key) | |
646 | { | |
dbf52682 | 647 | memset(worker, 0, sizeof(struct kthread_worker)); |
fe99a4f4 | 648 | raw_spin_lock_init(&worker->lock); |
4f32e9b1 YZ |
649 | lockdep_set_class_and_name(&worker->lock, key, name); |
650 | INIT_LIST_HEAD(&worker->work_list); | |
22597dc3 | 651 | INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1 | 652 | } |
3989144f | 653 | EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1 | 654 | |
b56c0d89 TH |
655 | /** |
656 | * kthread_worker_fn - kthread function to process kthread_worker | |
657 | * @worker_ptr: pointer to initialized kthread_worker | |
658 | * | |
fbae2d44 PM |
659 | * This function implements the main cycle of kthread worker. It processes |
660 | * work_list until it is stopped with kthread_stop(). It sleeps when the queue | |
661 | * is empty. | |
b56c0d89 | 662 | * |
fbae2d44 PM |
663 | * The works are not allowed to keep any locks, disable preemption or interrupts |
664 | * when they finish. There is defined a safe point for freezing when one work | |
665 | * finishes and before a new one is started. | |
8197b3d4 PM |
666 | * |
667 | * Also the works must not be handled by more than one worker at the same time, | |
668 | * see also kthread_queue_work(). | |
b56c0d89 TH |
669 | */ |
670 | int kthread_worker_fn(void *worker_ptr) | |
671 | { | |
672 | struct kthread_worker *worker = worker_ptr; | |
673 | struct kthread_work *work; | |
674 | ||
fbae2d44 PM |
675 | /* |
676 | * FIXME: Update the check and remove the assignment when all kthread | |
677 | * worker users are created using kthread_create_worker*() functions. | |
678 | */ | |
679 | WARN_ON(worker->task && worker->task != current); | |
b56c0d89 | 680 | worker->task = current; |
dbf52682 PM |
681 | |
682 | if (worker->flags & KTW_FREEZABLE) | |
683 | set_freezable(); | |
684 | ||
b56c0d89 TH |
685 | repeat: |
686 | set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ | |
687 | ||
688 | if (kthread_should_stop()) { | |
689 | __set_current_state(TASK_RUNNING); | |
fe99a4f4 | 690 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 | 691 | worker->task = NULL; |
fe99a4f4 | 692 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
693 | return 0; |
694 | } | |
695 | ||
696 | work = NULL; | |
fe99a4f4 | 697 | raw_spin_lock_irq(&worker->lock); |
b56c0d89 TH |
698 | if (!list_empty(&worker->work_list)) { |
699 | work = list_first_entry(&worker->work_list, | |
700 | struct kthread_work, node); | |
701 | list_del_init(&work->node); | |
702 | } | |
46f3d976 | 703 | worker->current_work = work; |
fe99a4f4 | 704 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 TH |
705 | |
706 | if (work) { | |
707 | __set_current_state(TASK_RUNNING); | |
708 | work->func(work); | |
b56c0d89 TH |
709 | } else if (!freezing(current)) |
710 | schedule(); | |
711 | ||
712 | try_to_freeze(); | |
22cf8bc6 | 713 | cond_resched(); |
b56c0d89 TH |
714 | goto repeat; |
715 | } | |
716 | EXPORT_SYMBOL_GPL(kthread_worker_fn); | |
717 | ||
c0b942a7 | 718 | static __printf(3, 0) struct kthread_worker * |
dbf52682 PM |
719 | __kthread_create_worker(int cpu, unsigned int flags, |
720 | const char namefmt[], va_list args) | |
fbae2d44 PM |
721 | { |
722 | struct kthread_worker *worker; | |
723 | struct task_struct *task; | |
98fa15f3 | 724 | int node = NUMA_NO_NODE; |
fbae2d44 PM |
725 | |
726 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
727 | if (!worker) | |
728 | return ERR_PTR(-ENOMEM); | |
729 | ||
730 | kthread_init_worker(worker); | |
731 | ||
8fb9dcbd ON |
732 | if (cpu >= 0) |
733 | node = cpu_to_node(cpu); | |
fbae2d44 | 734 | |
8fb9dcbd ON |
735 | task = __kthread_create_on_node(kthread_worker_fn, worker, |
736 | node, namefmt, args); | |
fbae2d44 PM |
737 | if (IS_ERR(task)) |
738 | goto fail_task; | |
739 | ||
8fb9dcbd ON |
740 | if (cpu >= 0) |
741 | kthread_bind(task, cpu); | |
742 | ||
dbf52682 | 743 | worker->flags = flags; |
fbae2d44 PM |
744 | worker->task = task; |
745 | wake_up_process(task); | |
746 | return worker; | |
747 | ||
748 | fail_task: | |
749 | kfree(worker); | |
750 | return ERR_CAST(task); | |
751 | } | |
752 | ||
753 | /** | |
754 | * kthread_create_worker - create a kthread worker | |
dbf52682 | 755 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
756 | * @namefmt: printf-style name for the kthread worker (task). |
757 | * | |
758 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
759 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
760 | * when the worker was SIGKILLed. | |
761 | */ | |
762 | struct kthread_worker * | |
dbf52682 | 763 | kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44 PM |
764 | { |
765 | struct kthread_worker *worker; | |
766 | va_list args; | |
767 | ||
768 | va_start(args, namefmt); | |
dbf52682 | 769 | worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44 PM |
770 | va_end(args); |
771 | ||
772 | return worker; | |
773 | } | |
774 | EXPORT_SYMBOL(kthread_create_worker); | |
775 | ||
776 | /** | |
777 | * kthread_create_worker_on_cpu - create a kthread worker and bind it | |
778 | * it to a given CPU and the associated NUMA node. | |
779 | * @cpu: CPU number | |
dbf52682 | 780 | * @flags: flags modifying the default behavior of the worker |
fbae2d44 PM |
781 | * @namefmt: printf-style name for the kthread worker (task). |
782 | * | |
783 | * Use a valid CPU number if you want to bind the kthread worker | |
784 | * to the given CPU and the associated NUMA node. | |
785 | * | |
786 | * A good practice is to add the cpu number also into the worker name. | |
787 | * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). | |
788 | * | |
789 | * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) | |
790 | * when the needed structures could not get allocated, and ERR_PTR(-EINTR) | |
791 | * when the worker was SIGKILLed. | |
792 | */ | |
793 | struct kthread_worker * | |
dbf52682 PM |
794 | kthread_create_worker_on_cpu(int cpu, unsigned int flags, |
795 | const char namefmt[], ...) | |
fbae2d44 PM |
796 | { |
797 | struct kthread_worker *worker; | |
798 | va_list args; | |
799 | ||
800 | va_start(args, namefmt); | |
dbf52682 | 801 | worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44 PM |
802 | va_end(args); |
803 | ||
804 | return worker; | |
805 | } | |
806 | EXPORT_SYMBOL(kthread_create_worker_on_cpu); | |
807 | ||
37be45d4 PM |
808 | /* |
809 | * Returns true when the work could not be queued at the moment. | |
810 | * It happens when it is already pending in a worker list | |
811 | * or when it is being cancelled. | |
812 | */ | |
813 | static inline bool queuing_blocked(struct kthread_worker *worker, | |
814 | struct kthread_work *work) | |
815 | { | |
816 | lockdep_assert_held(&worker->lock); | |
817 | ||
818 | return !list_empty(&work->node) || work->canceling; | |
819 | } | |
820 | ||
8197b3d4 PM |
821 | static void kthread_insert_work_sanity_check(struct kthread_worker *worker, |
822 | struct kthread_work *work) | |
823 | { | |
824 | lockdep_assert_held(&worker->lock); | |
825 | WARN_ON_ONCE(!list_empty(&work->node)); | |
826 | /* Do not use a work with >1 worker, see kthread_queue_work() */ | |
827 | WARN_ON_ONCE(work->worker && work->worker != worker); | |
828 | } | |
829 | ||
9a2e03d8 | 830 | /* insert @work before @pos in @worker */ |
3989144f | 831 | static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d4 PM |
832 | struct kthread_work *work, |
833 | struct list_head *pos) | |
9a2e03d8 | 834 | { |
8197b3d4 | 835 | kthread_insert_work_sanity_check(worker, work); |
9a2e03d8 TH |
836 | |
837 | list_add_tail(&work->node, pos); | |
46f3d976 | 838 | work->worker = worker; |
ed1403ec | 839 | if (!worker->current_work && likely(worker->task)) |
9a2e03d8 TH |
840 | wake_up_process(worker->task); |
841 | } | |
842 | ||
b56c0d89 | 843 | /** |
3989144f | 844 | * kthread_queue_work - queue a kthread_work |
b56c0d89 TH |
845 | * @worker: target kthread_worker |
846 | * @work: kthread_work to queue | |
847 | * | |
848 | * Queue @work to work processor @task for async execution. @task | |
849 | * must have been created with kthread_worker_create(). Returns %true | |
850 | * if @work was successfully queued, %false if it was already pending. | |
8197b3d4 PM |
851 | * |
852 | * Reinitialize the work if it needs to be used by another worker. | |
853 | * For example, when the worker was stopped and started again. | |
b56c0d89 | 854 | */ |
3989144f | 855 | bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d89 TH |
856 | struct kthread_work *work) |
857 | { | |
858 | bool ret = false; | |
859 | unsigned long flags; | |
860 | ||
fe99a4f4 | 861 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 | 862 | if (!queuing_blocked(worker, work)) { |
3989144f | 863 | kthread_insert_work(worker, work, &worker->work_list); |
b56c0d89 TH |
864 | ret = true; |
865 | } | |
fe99a4f4 | 866 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
b56c0d89 TH |
867 | return ret; |
868 | } | |
3989144f | 869 | EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d89 | 870 | |
22597dc3 PM |
871 | /** |
872 | * kthread_delayed_work_timer_fn - callback that queues the associated kthread | |
873 | * delayed work when the timer expires. | |
fe5c3b69 | 874 | * @t: pointer to the expired timer |
22597dc3 PM |
875 | * |
876 | * The format of the function is defined by struct timer_list. | |
877 | * It should have been called from irqsafe timer with irq already off. | |
878 | */ | |
fe5c3b69 | 879 | void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3 | 880 | { |
fe5c3b69 | 881 | struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3 PM |
882 | struct kthread_work *work = &dwork->work; |
883 | struct kthread_worker *worker = work->worker; | |
ad01423a | 884 | unsigned long flags; |
22597dc3 PM |
885 | |
886 | /* | |
887 | * This might happen when a pending work is reinitialized. | |
888 | * It means that it is used a wrong way. | |
889 | */ | |
890 | if (WARN_ON_ONCE(!worker)) | |
891 | return; | |
892 | ||
ad01423a | 893 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 PM |
894 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
895 | WARN_ON_ONCE(work->worker != worker); | |
896 | ||
897 | /* Move the work from worker->delayed_work_list. */ | |
898 | WARN_ON_ONCE(list_empty(&work->node)); | |
899 | list_del_init(&work->node); | |
900 | kthread_insert_work(worker, work, &worker->work_list); | |
901 | ||
ad01423a | 902 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
903 | } |
904 | EXPORT_SYMBOL(kthread_delayed_work_timer_fn); | |
905 | ||
bc88f85c BD |
906 | static void __kthread_queue_delayed_work(struct kthread_worker *worker, |
907 | struct kthread_delayed_work *dwork, | |
908 | unsigned long delay) | |
22597dc3 PM |
909 | { |
910 | struct timer_list *timer = &dwork->timer; | |
911 | struct kthread_work *work = &dwork->work; | |
912 | ||
841b86f3 | 913 | WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3 PM |
914 | |
915 | /* | |
916 | * If @delay is 0, queue @dwork->work immediately. This is for | |
917 | * both optimization and correctness. The earliest @timer can | |
918 | * expire is on the closest next tick and delayed_work users depend | |
919 | * on that there's no such delay when @delay is 0. | |
920 | */ | |
921 | if (!delay) { | |
922 | kthread_insert_work(worker, work, &worker->work_list); | |
923 | return; | |
924 | } | |
925 | ||
926 | /* Be paranoid and try to detect possible races already now. */ | |
927 | kthread_insert_work_sanity_check(worker, work); | |
928 | ||
929 | list_add(&work->node, &worker->delayed_work_list); | |
930 | work->worker = worker; | |
22597dc3 PM |
931 | timer->expires = jiffies + delay; |
932 | add_timer(timer); | |
933 | } | |
934 | ||
935 | /** | |
936 | * kthread_queue_delayed_work - queue the associated kthread work | |
937 | * after a delay. | |
938 | * @worker: target kthread_worker | |
939 | * @dwork: kthread_delayed_work to queue | |
940 | * @delay: number of jiffies to wait before queuing | |
941 | * | |
942 | * If the work has not been pending it starts a timer that will queue | |
943 | * the work after the given @delay. If @delay is zero, it queues the | |
944 | * work immediately. | |
945 | * | |
946 | * Return: %false if the @work has already been pending. It means that | |
947 | * either the timer was running or the work was queued. It returns %true | |
948 | * otherwise. | |
949 | */ | |
950 | bool kthread_queue_delayed_work(struct kthread_worker *worker, | |
951 | struct kthread_delayed_work *dwork, | |
952 | unsigned long delay) | |
953 | { | |
954 | struct kthread_work *work = &dwork->work; | |
955 | unsigned long flags; | |
956 | bool ret = false; | |
957 | ||
fe99a4f4 | 958 | raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3 | 959 | |
37be45d4 | 960 | if (!queuing_blocked(worker, work)) { |
22597dc3 PM |
961 | __kthread_queue_delayed_work(worker, dwork, delay); |
962 | ret = true; | |
963 | } | |
964 | ||
fe99a4f4 | 965 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3 PM |
966 | return ret; |
967 | } | |
968 | EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); | |
969 | ||
9a2e03d8 TH |
970 | struct kthread_flush_work { |
971 | struct kthread_work work; | |
972 | struct completion done; | |
973 | }; | |
974 | ||
975 | static void kthread_flush_work_fn(struct kthread_work *work) | |
976 | { | |
977 | struct kthread_flush_work *fwork = | |
978 | container_of(work, struct kthread_flush_work, work); | |
979 | complete(&fwork->done); | |
980 | } | |
981 | ||
b56c0d89 | 982 | /** |
3989144f | 983 | * kthread_flush_work - flush a kthread_work |
b56c0d89 TH |
984 | * @work: work to flush |
985 | * | |
986 | * If @work is queued or executing, wait for it to finish execution. | |
987 | */ | |
3989144f | 988 | void kthread_flush_work(struct kthread_work *work) |
b56c0d89 | 989 | { |
46f3d976 TH |
990 | struct kthread_flush_work fwork = { |
991 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
992 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
993 | }; | |
994 | struct kthread_worker *worker; | |
995 | bool noop = false; | |
996 | ||
46f3d976 TH |
997 | worker = work->worker; |
998 | if (!worker) | |
999 | return; | |
b56c0d89 | 1000 | |
fe99a4f4 | 1001 | raw_spin_lock_irq(&worker->lock); |
8197b3d4 PM |
1002 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1003 | WARN_ON_ONCE(work->worker != worker); | |
b56c0d89 | 1004 | |
46f3d976 | 1005 | if (!list_empty(&work->node)) |
3989144f | 1006 | kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d976 | 1007 | else if (worker->current_work == work) |
3989144f PM |
1008 | kthread_insert_work(worker, &fwork.work, |
1009 | worker->work_list.next); | |
46f3d976 TH |
1010 | else |
1011 | noop = true; | |
b56c0d89 | 1012 | |
fe99a4f4 | 1013 | raw_spin_unlock_irq(&worker->lock); |
b56c0d89 | 1014 | |
46f3d976 TH |
1015 | if (!noop) |
1016 | wait_for_completion(&fwork.done); | |
b56c0d89 | 1017 | } |
3989144f | 1018 | EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d89 | 1019 | |
37be45d4 PM |
1020 | /* |
1021 | * This function removes the work from the worker queue. Also it makes sure | |
1022 | * that it won't get queued later via the delayed work's timer. | |
1023 | * | |
1024 | * The work might still be in use when this function finishes. See the | |
1025 | * current_work proceed by the worker. | |
1026 | * | |
1027 | * Return: %true if @work was pending and successfully canceled, | |
1028 | * %false if @work was not pending | |
1029 | */ | |
1030 | static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork, | |
1031 | unsigned long *flags) | |
1032 | { | |
1033 | /* Try to cancel the timer if exists. */ | |
1034 | if (is_dwork) { | |
1035 | struct kthread_delayed_work *dwork = | |
1036 | container_of(work, struct kthread_delayed_work, work); | |
1037 | struct kthread_worker *worker = work->worker; | |
1038 | ||
1039 | /* | |
1040 | * del_timer_sync() must be called to make sure that the timer | |
1041 | * callback is not running. The lock must be temporary released | |
1042 | * to avoid a deadlock with the callback. In the meantime, | |
1043 | * any queuing is blocked by setting the canceling counter. | |
1044 | */ | |
1045 | work->canceling++; | |
fe99a4f4 | 1046 | raw_spin_unlock_irqrestore(&worker->lock, *flags); |
37be45d4 | 1047 | del_timer_sync(&dwork->timer); |
fe99a4f4 | 1048 | raw_spin_lock_irqsave(&worker->lock, *flags); |
37be45d4 PM |
1049 | work->canceling--; |
1050 | } | |
1051 | ||
1052 | /* | |
1053 | * Try to remove the work from a worker list. It might either | |
1054 | * be from worker->work_list or from worker->delayed_work_list. | |
1055 | */ | |
1056 | if (!list_empty(&work->node)) { | |
1057 | list_del_init(&work->node); | |
1058 | return true; | |
1059 | } | |
1060 | ||
1061 | return false; | |
1062 | } | |
1063 | ||
9a6b06c8 PM |
1064 | /** |
1065 | * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work | |
1066 | * @worker: kthread worker to use | |
1067 | * @dwork: kthread delayed work to queue | |
1068 | * @delay: number of jiffies to wait before queuing | |
1069 | * | |
1070 | * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, | |
1071 | * modify @dwork's timer so that it expires after @delay. If @delay is zero, | |
1072 | * @work is guaranteed to be queued immediately. | |
1073 | * | |
1074 | * Return: %true if @dwork was pending and its timer was modified, | |
1075 | * %false otherwise. | |
1076 | * | |
1077 | * A special case is when the work is being canceled in parallel. | |
1078 | * It might be caused either by the real kthread_cancel_delayed_work_sync() | |
1079 | * or yet another kthread_mod_delayed_work() call. We let the other command | |
1080 | * win and return %false here. The caller is supposed to synchronize these | |
1081 | * operations a reasonable way. | |
1082 | * | |
1083 | * This function is safe to call from any context including IRQ handler. | |
1084 | * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() | |
1085 | * for details. | |
1086 | */ | |
1087 | bool kthread_mod_delayed_work(struct kthread_worker *worker, | |
1088 | struct kthread_delayed_work *dwork, | |
1089 | unsigned long delay) | |
1090 | { | |
1091 | struct kthread_work *work = &dwork->work; | |
1092 | unsigned long flags; | |
1093 | int ret = false; | |
1094 | ||
fe99a4f4 | 1095 | raw_spin_lock_irqsave(&worker->lock, flags); |
9a6b06c8 PM |
1096 | |
1097 | /* Do not bother with canceling when never queued. */ | |
1098 | if (!work->worker) | |
1099 | goto fast_queue; | |
1100 | ||
1101 | /* Work must not be used with >1 worker, see kthread_queue_work() */ | |
1102 | WARN_ON_ONCE(work->worker != worker); | |
1103 | ||
1104 | /* Do not fight with another command that is canceling this work. */ | |
1105 | if (work->canceling) | |
1106 | goto out; | |
1107 | ||
1108 | ret = __kthread_cancel_work(work, true, &flags); | |
1109 | fast_queue: | |
1110 | __kthread_queue_delayed_work(worker, dwork, delay); | |
1111 | out: | |
fe99a4f4 | 1112 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
9a6b06c8 PM |
1113 | return ret; |
1114 | } | |
1115 | EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); | |
1116 | ||
37be45d4 PM |
1117 | static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) |
1118 | { | |
1119 | struct kthread_worker *worker = work->worker; | |
1120 | unsigned long flags; | |
1121 | int ret = false; | |
1122 | ||
1123 | if (!worker) | |
1124 | goto out; | |
1125 | ||
fe99a4f4 | 1126 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1127 | /* Work must not be used with >1 worker, see kthread_queue_work(). */ |
1128 | WARN_ON_ONCE(work->worker != worker); | |
1129 | ||
1130 | ret = __kthread_cancel_work(work, is_dwork, &flags); | |
1131 | ||
1132 | if (worker->current_work != work) | |
1133 | goto out_fast; | |
1134 | ||
1135 | /* | |
1136 | * The work is in progress and we need to wait with the lock released. | |
1137 | * In the meantime, block any queuing by setting the canceling counter. | |
1138 | */ | |
1139 | work->canceling++; | |
fe99a4f4 | 1140 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 | 1141 | kthread_flush_work(work); |
fe99a4f4 | 1142 | raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d4 PM |
1143 | work->canceling--; |
1144 | ||
1145 | out_fast: | |
fe99a4f4 | 1146 | raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d4 PM |
1147 | out: |
1148 | return ret; | |
1149 | } | |
1150 | ||
1151 | /** | |
1152 | * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish | |
1153 | * @work: the kthread work to cancel | |
1154 | * | |
1155 | * Cancel @work and wait for its execution to finish. This function | |
1156 | * can be used even if the work re-queues itself. On return from this | |
1157 | * function, @work is guaranteed to be not pending or executing on any CPU. | |
1158 | * | |
1159 | * kthread_cancel_work_sync(&delayed_work->work) must not be used for | |
1160 | * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. | |
1161 | * | |
1162 | * The caller must ensure that the worker on which @work was last | |
1163 | * queued can't be destroyed before this function returns. | |
1164 | * | |
1165 | * Return: %true if @work was pending, %false otherwise. | |
1166 | */ | |
1167 | bool kthread_cancel_work_sync(struct kthread_work *work) | |
1168 | { | |
1169 | return __kthread_cancel_work_sync(work, false); | |
1170 | } | |
1171 | EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); | |
1172 | ||
1173 | /** | |
1174 | * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and | |
1175 | * wait for it to finish. | |
1176 | * @dwork: the kthread delayed work to cancel | |
1177 | * | |
1178 | * This is kthread_cancel_work_sync() for delayed works. | |
1179 | * | |
1180 | * Return: %true if @dwork was pending, %false otherwise. | |
1181 | */ | |
1182 | bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) | |
1183 | { | |
1184 | return __kthread_cancel_work_sync(&dwork->work, true); | |
1185 | } | |
1186 | EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); | |
1187 | ||
b56c0d89 | 1188 | /** |
3989144f | 1189 | * kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d89 TH |
1190 | * @worker: worker to flush |
1191 | * | |
1192 | * Wait until all currently executing or pending works on @worker are | |
1193 | * finished. | |
1194 | */ | |
3989144f | 1195 | void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d89 TH |
1196 | { |
1197 | struct kthread_flush_work fwork = { | |
1198 | KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), | |
1199 | COMPLETION_INITIALIZER_ONSTACK(fwork.done), | |
1200 | }; | |
1201 | ||
3989144f | 1202 | kthread_queue_work(worker, &fwork.work); |
b56c0d89 TH |
1203 | wait_for_completion(&fwork.done); |
1204 | } | |
3989144f | 1205 | EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9 PM |
1206 | |
1207 | /** | |
1208 | * kthread_destroy_worker - destroy a kthread worker | |
1209 | * @worker: worker to be destroyed | |
1210 | * | |
1211 | * Flush and destroy @worker. The simple flush is enough because the kthread | |
1212 | * worker API is used only in trivial scenarios. There are no multi-step state | |
1213 | * machines needed. | |
1214 | */ | |
1215 | void kthread_destroy_worker(struct kthread_worker *worker) | |
1216 | { | |
1217 | struct task_struct *task; | |
1218 | ||
1219 | task = worker->task; | |
1220 | if (WARN_ON(!task)) | |
1221 | return; | |
1222 | ||
1223 | kthread_flush_worker(worker); | |
1224 | kthread_stop(task); | |
1225 | WARN_ON(!list_empty(&worker->work_list)); | |
1226 | kfree(worker); | |
1227 | } | |
1228 | EXPORT_SYMBOL(kthread_destroy_worker); | |
05e3db95 | 1229 | |
f5678e7f CH |
1230 | /** |
1231 | * kthread_use_mm - make the calling kthread operate on an address space | |
1232 | * @mm: address space to operate on | |
9bf5b9eb | 1233 | */ |
f5678e7f | 1234 | void kthread_use_mm(struct mm_struct *mm) |
9bf5b9eb CH |
1235 | { |
1236 | struct mm_struct *active_mm; | |
1237 | struct task_struct *tsk = current; | |
1238 | ||
f5678e7f CH |
1239 | WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
1240 | WARN_ON_ONCE(tsk->mm); | |
1241 | ||
9bf5b9eb | 1242 | task_lock(tsk); |
38cf307c PZ |
1243 | /* Hold off tlb flush IPIs while switching mm's */ |
1244 | local_irq_disable(); | |
9bf5b9eb CH |
1245 | active_mm = tsk->active_mm; |
1246 | if (active_mm != mm) { | |
1247 | mmgrab(mm); | |
1248 | tsk->active_mm = mm; | |
1249 | } | |
1250 | tsk->mm = mm; | |
38cf307c PZ |
1251 | switch_mm_irqs_off(active_mm, mm, tsk); |
1252 | local_irq_enable(); | |
9bf5b9eb CH |
1253 | task_unlock(tsk); |
1254 | #ifdef finish_arch_post_lock_switch | |
1255 | finish_arch_post_lock_switch(); | |
1256 | #endif | |
1257 | ||
1258 | if (active_mm != mm) | |
1259 | mmdrop(active_mm); | |
37c54f9b | 1260 | |
3d13f313 | 1261 | to_kthread(tsk)->oldfs = force_uaccess_begin(); |
9bf5b9eb | 1262 | } |
f5678e7f | 1263 | EXPORT_SYMBOL_GPL(kthread_use_mm); |
9bf5b9eb | 1264 | |
f5678e7f CH |
1265 | /** |
1266 | * kthread_unuse_mm - reverse the effect of kthread_use_mm() | |
1267 | * @mm: address space to operate on | |
9bf5b9eb | 1268 | */ |
f5678e7f | 1269 | void kthread_unuse_mm(struct mm_struct *mm) |
9bf5b9eb CH |
1270 | { |
1271 | struct task_struct *tsk = current; | |
1272 | ||
f5678e7f CH |
1273 | WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); |
1274 | WARN_ON_ONCE(!tsk->mm); | |
1275 | ||
3d13f313 | 1276 | force_uaccess_end(to_kthread(tsk)->oldfs); |
37c54f9b | 1277 | |
9bf5b9eb CH |
1278 | task_lock(tsk); |
1279 | sync_mm_rss(mm); | |
38cf307c | 1280 | local_irq_disable(); |
9bf5b9eb CH |
1281 | tsk->mm = NULL; |
1282 | /* active_mm is still 'mm' */ | |
1283 | enter_lazy_tlb(mm, tsk); | |
38cf307c | 1284 | local_irq_enable(); |
9bf5b9eb CH |
1285 | task_unlock(tsk); |
1286 | } | |
f5678e7f | 1287 | EXPORT_SYMBOL_GPL(kthread_unuse_mm); |
9bf5b9eb | 1288 | |
0b508bc9 | 1289 | #ifdef CONFIG_BLK_CGROUP |
05e3db95 SL |
1290 | /** |
1291 | * kthread_associate_blkcg - associate blkcg to current kthread | |
1292 | * @css: the cgroup info | |
1293 | * | |
1294 | * Current thread must be a kthread. The thread is running jobs on behalf of | |
1295 | * other threads. In some cases, we expect the jobs attach cgroup info of | |
1296 | * original threads instead of that of current thread. This function stores | |
1297 | * original thread's cgroup info in current kthread context for later | |
1298 | * retrieval. | |
1299 | */ | |
1300 | void kthread_associate_blkcg(struct cgroup_subsys_state *css) | |
1301 | { | |
1302 | struct kthread *kthread; | |
1303 | ||
1304 | if (!(current->flags & PF_KTHREAD)) | |
1305 | return; | |
1306 | kthread = to_kthread(current); | |
1307 | if (!kthread) | |
1308 | return; | |
1309 | ||
1310 | if (kthread->blkcg_css) { | |
1311 | css_put(kthread->blkcg_css); | |
1312 | kthread->blkcg_css = NULL; | |
1313 | } | |
1314 | if (css) { | |
1315 | css_get(css); | |
1316 | kthread->blkcg_css = css; | |
1317 | } | |
1318 | } | |
1319 | EXPORT_SYMBOL(kthread_associate_blkcg); | |
1320 | ||
1321 | /** | |
1322 | * kthread_blkcg - get associated blkcg css of current kthread | |
1323 | * | |
1324 | * Current thread must be a kthread. | |
1325 | */ | |
1326 | struct cgroup_subsys_state *kthread_blkcg(void) | |
1327 | { | |
1328 | struct kthread *kthread; | |
1329 | ||
1330 | if (current->flags & PF_KTHREAD) { | |
1331 | kthread = to_kthread(current); | |
1332 | if (kthread) | |
1333 | return kthread->blkcg_css; | |
1334 | } | |
1335 | return NULL; | |
1336 | } | |
1337 | EXPORT_SYMBOL(kthread_blkcg); | |
1338 | #endif |