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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* Kernel thread helper functions.
2 * Copyright (C) 2004 IBM Corporation, Rusty Russell.
3 *
Eric W. Biederman73c27992007-05-09 02:34:32 -07004 * Creation is done via kthreadd, so that we get a clean environment
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 * even if we're invoked from userspace (think modprobe, hotplug cpu,
6 * etc.).
7 */
Ingo Molnarae7e81c2017-02-01 18:07:51 +01008#include <uapi/linux/sched/types.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07009#include <linux/sched.h>
Ingo Molnar29930022017-02-08 18:51:36 +010010#include <linux/sched/task.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/kthread.h>
12#include <linux/completion.h>
13#include <linux/err.h>
Miao Xie58568d22009-06-16 15:31:49 -070014#include <linux/cpuset.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/unistd.h>
16#include <linux/file.h>
Paul Gortmaker9984de12011-05-23 14:51:41 -040017#include <linux/export.h>
Arjan van de Ven97d1f152006-03-23 03:00:24 -080018#include <linux/mutex.h>
Tejun Heob56c0d82010-06-29 10:07:09 +020019#include <linux/slab.h>
20#include <linux/freezer.h>
Al Viroa74fb732012-10-10 21:28:25 -040021#include <linux/ptrace.h>
Tejun Heocd42d552013-04-30 15:27:21 -070022#include <linux/uaccess.h>
Steven Rostedtad8d75f2009-04-14 19:39:12 -040023#include <trace/events/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
Eric W. Biederman73c27992007-05-09 02:34:32 -070025static DEFINE_SPINLOCK(kthread_create_lock);
26static LIST_HEAD(kthread_create_list);
27struct task_struct *kthreadd_task;
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
29struct kthread_create_info
30{
Eric W. Biederman73c27992007-05-09 02:34:32 -070031 /* Information passed to kthread() from kthreadd. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070032 int (*threadfn)(void *data);
33 void *data;
Eric Dumazet207205a2011-03-22 16:30:44 -070034 int node;
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
Eric W. Biederman73c27992007-05-09 02:34:32 -070036 /* Result passed back to kthread_create() from kthreadd. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 struct task_struct *result;
Tetsuo Handa786235ee2013-11-12 15:06:45 -080038 struct completion *done;
David Howells65f27f32006-11-22 14:55:48 +000039
Eric W. Biederman73c27992007-05-09 02:34:32 -070040 struct list_head list;
Linus Torvalds1da177e2005-04-16 15:20:36 -070041};
42
Oleg Nesterov63706172009-06-17 16:27:45 -070043struct kthread {
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000044 unsigned long flags;
45 unsigned int cpu;
Tejun Heo82805ab2010-06-29 10:07:09 +020046 void *data;
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000047 struct completion parked;
Oleg Nesterov63706172009-06-17 16:27:45 -070048 struct completion exited;
Shaohua Li0b508bc2017-09-26 11:02:12 -070049#ifdef CONFIG_BLK_CGROUP
Shaohua Li05e3db92017-09-14 14:02:04 -070050 struct cgroup_subsys_state *blkcg_css;
51#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070052};
53
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000054enum KTHREAD_BITS {
55 KTHREAD_IS_PER_CPU = 0,
56 KTHREAD_SHOULD_STOP,
57 KTHREAD_SHOULD_PARK,
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000058};
59
Oleg Nesterov1da5c462016-11-29 18:50:57 +010060static inline void set_kthread_struct(void *kthread)
61{
62 /*
63 * We abuse ->set_child_tid to avoid the new member and because it
64 * can't be wrongly copied by copy_process(). We also rely on fact
65 * that the caller can't exec, so PF_KTHREAD can't be cleared.
66 */
67 current->set_child_tid = (__force void __user *)kthread;
68}
Oleg Nesterov4ecdafc2013-04-29 15:05:01 -070069
70static inline struct kthread *to_kthread(struct task_struct *k)
71{
Oleg Nesterov1da5c462016-11-29 18:50:57 +010072 WARN_ON(!(k->flags & PF_KTHREAD));
73 return (__force void *)k->set_child_tid;
Oleg Nesterov4ecdafc2013-04-29 15:05:01 -070074}
75
Oleg Nesterov1da5c462016-11-29 18:50:57 +010076void free_kthread_struct(struct task_struct *k)
77{
Shaohua Li05e3db92017-09-14 14:02:04 -070078 struct kthread *kthread;
79
Oleg Nesterov1da5c462016-11-29 18:50:57 +010080 /*
81 * Can be NULL if this kthread was created by kernel_thread()
82 * or if kmalloc() in kthread() failed.
83 */
Shaohua Li05e3db92017-09-14 14:02:04 -070084 kthread = to_kthread(k);
Shaohua Li0b508bc2017-09-26 11:02:12 -070085#ifdef CONFIG_BLK_CGROUP
Shaohua Li05e3db92017-09-14 14:02:04 -070086 WARN_ON_ONCE(kthread && kthread->blkcg_css);
87#endif
88 kfree(kthread);
Oleg Nesterov1da5c462016-11-29 18:50:57 +010089}
90
Randy Dunlap9e37bd32006-06-25 05:49:19 -070091/**
92 * kthread_should_stop - should this kthread return now?
93 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -080094 * When someone calls kthread_stop() on your kthread, it will be woken
Randy Dunlap9e37bd32006-06-25 05:49:19 -070095 * and this will return true. You should then return, and your return
96 * value will be passed through to kthread_stop().
97 */
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000098bool kthread_should_stop(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -070099{
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000100 return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101}
102EXPORT_SYMBOL(kthread_should_stop);
103
Tejun Heo82805ab2010-06-29 10:07:09 +0200104/**
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000105 * kthread_should_park - should this kthread park now?
106 *
107 * When someone calls kthread_park() on your kthread, it will be woken
108 * and this will return true. You should then do the necessary
109 * cleanup and call kthread_parkme()
110 *
111 * Similar to kthread_should_stop(), but this keeps the thread alive
112 * and in a park position. kthread_unpark() "restarts" the thread and
113 * calls the thread function again.
114 */
115bool kthread_should_park(void)
116{
117 return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags);
118}
David Kershner18896452015-08-06 15:46:45 -0700119EXPORT_SYMBOL_GPL(kthread_should_park);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000120
121/**
Tejun Heo8a32c442011-11-21 12:32:23 -0800122 * kthread_freezable_should_stop - should this freezable kthread return now?
123 * @was_frozen: optional out parameter, indicates whether %current was frozen
124 *
125 * kthread_should_stop() for freezable kthreads, which will enter
126 * refrigerator if necessary. This function is safe from kthread_stop() /
127 * freezer deadlock and freezable kthreads should use this function instead
128 * of calling try_to_freeze() directly.
129 */
130bool kthread_freezable_should_stop(bool *was_frozen)
131{
132 bool frozen = false;
133
134 might_sleep();
135
136 if (unlikely(freezing(current)))
137 frozen = __refrigerator(true);
138
139 if (was_frozen)
140 *was_frozen = frozen;
141
142 return kthread_should_stop();
143}
144EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
145
146/**
Tejun Heo82805ab2010-06-29 10:07:09 +0200147 * kthread_data - return data value specified on kthread creation
148 * @task: kthread task in question
149 *
150 * Return the data value specified when kthread @task was created.
151 * The caller is responsible for ensuring the validity of @task when
152 * calling this function.
153 */
154void *kthread_data(struct task_struct *task)
155{
156 return to_kthread(task)->data;
157}
158
Tejun Heocd42d552013-04-30 15:27:21 -0700159/**
Petr Mladeke7005912016-10-11 13:55:17 -0700160 * kthread_probe_data - speculative version of kthread_data()
Tejun Heocd42d552013-04-30 15:27:21 -0700161 * @task: possible kthread task in question
162 *
163 * @task could be a kthread task. Return the data value specified when it
164 * was created if accessible. If @task isn't a kthread task or its data is
165 * inaccessible for any reason, %NULL is returned. This function requires
166 * that @task itself is safe to dereference.
167 */
Petr Mladeke7005912016-10-11 13:55:17 -0700168void *kthread_probe_data(struct task_struct *task)
Tejun Heocd42d552013-04-30 15:27:21 -0700169{
170 struct kthread *kthread = to_kthread(task);
171 void *data = NULL;
172
173 probe_kernel_read(&data, &kthread->data, sizeof(data));
174 return data;
175}
176
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000177static void __kthread_parkme(struct kthread *self)
178{
Peter Zijlstra741a76b2018-04-30 14:50:22 +0200179 for (;;) {
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200180 /*
181 * TASK_PARKED is a special state; we must serialize against
182 * possible pending wakeups to avoid store-store collisions on
183 * task->state.
184 *
185 * Such a collision might possibly result in the task state
186 * changin from TASK_PARKED and us failing the
187 * wait_task_inactive() in kthread_park().
188 */
189 set_special_state(TASK_PARKED);
Peter Zijlstra741a76b2018-04-30 14:50:22 +0200190 if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags))
191 break;
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200192
193 complete_all(&self->parked);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000194 schedule();
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000195 }
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000196 __set_current_state(TASK_RUNNING);
197}
198
199void kthread_parkme(void)
200{
201 __kthread_parkme(to_kthread(current));
202}
David Kershner18896452015-08-06 15:46:45 -0700203EXPORT_SYMBOL_GPL(kthread_parkme);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000204
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205static int kthread(void *_create)
206{
Eric W. Biederman73c27992007-05-09 02:34:32 -0700207 /* Copy data: it's on kthread's stack */
Oleg Nesterov63706172009-06-17 16:27:45 -0700208 struct kthread_create_info *create = _create;
209 int (*threadfn)(void *data) = create->threadfn;
210 void *data = create->data;
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800211 struct completion *done;
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100212 struct kthread *self;
Oleg Nesterov63706172009-06-17 16:27:45 -0700213 int ret;
214
Shaohua Lie10237c2017-11-07 11:09:50 -0800215 self = kzalloc(sizeof(*self), GFP_KERNEL);
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100216 set_kthread_struct(self);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800218 /* If user was SIGKILLed, I release the structure. */
219 done = xchg(&create->done, NULL);
220 if (!done) {
221 kfree(create);
222 do_exit(-EINTR);
223 }
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100224
225 if (!self) {
226 create->result = ERR_PTR(-ENOMEM);
227 complete(done);
228 do_exit(-ENOMEM);
229 }
230
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100231 self->data = data;
232 init_completion(&self->exited);
233 init_completion(&self->parked);
234 current->vfork_done = &self->exited;
235
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 /* OK, tell user we're spawned, wait for stop or wakeup */
Oleg Nesterova076e4b2007-05-23 13:57:27 -0700237 __set_current_state(TASK_UNINTERRUPTIBLE);
Vitaliy Gusev3217ab92009-04-09 09:50:35 -0600238 create->result = current;
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800239 complete(done);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 schedule();
241
Oleg Nesterov63706172009-06-17 16:27:45 -0700242 ret = -EINTR;
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100243 if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
Tejun Heo77f88792017-03-16 16:54:24 -0400244 cgroup_kthread_ready();
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100245 __kthread_parkme(self);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000246 ret = threadfn(data);
247 }
Oleg Nesterov63706172009-06-17 16:27:45 -0700248 do_exit(ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249}
250
Eric Dumazet207205a2011-03-22 16:30:44 -0700251/* called from do_fork() to get node information for about to be created task */
252int tsk_fork_get_node(struct task_struct *tsk)
253{
254#ifdef CONFIG_NUMA
255 if (tsk == kthreadd_task)
256 return tsk->pref_node_fork;
257#endif
Nishanth Aravamudan81c98862014-04-03 14:46:25 -0700258 return NUMA_NO_NODE;
Eric Dumazet207205a2011-03-22 16:30:44 -0700259}
260
Eric W. Biederman73c27992007-05-09 02:34:32 -0700261static void create_kthread(struct kthread_create_info *create)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 int pid;
264
Eric Dumazet207205a2011-03-22 16:30:44 -0700265#ifdef CONFIG_NUMA
266 current->pref_node_fork = create->node;
267#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 /* We want our own signal handler (we take no signals by default). */
269 pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
Oleg Nesterovcdd140b2009-06-17 16:27:43 -0700270 if (pid < 0) {
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800271 /* If user was SIGKILLed, I release the structure. */
272 struct completion *done = xchg(&create->done, NULL);
273
274 if (!done) {
275 kfree(create);
276 return;
277 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 create->result = ERR_PTR(pid);
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800279 complete(done);
Oleg Nesterovcdd140b2009-06-17 16:27:43 -0700280 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281}
282
Nicolas Ioossc0b942a2016-12-12 16:40:39 -0800283static __printf(4, 0)
284struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
Petr Mladek255451e2016-10-11 13:55:27 -0700285 void *data, int node,
286 const char namefmt[],
287 va_list args)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288{
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800289 DECLARE_COMPLETION_ONSTACK(done);
290 struct task_struct *task;
291 struct kthread_create_info *create = kmalloc(sizeof(*create),
292 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800294 if (!create)
295 return ERR_PTR(-ENOMEM);
296 create->threadfn = threadfn;
297 create->data = data;
298 create->node = node;
299 create->done = &done;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300
Eric W. Biederman73c27992007-05-09 02:34:32 -0700301 spin_lock(&kthread_create_lock);
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800302 list_add_tail(&create->list, &kthread_create_list);
Eric W. Biederman73c27992007-05-09 02:34:32 -0700303 spin_unlock(&kthread_create_lock);
304
Dmitry Adamushkocbd9b672008-04-29 00:59:23 -0700305 wake_up_process(kthreadd_task);
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800306 /*
307 * Wait for completion in killable state, for I might be chosen by
308 * the OOM killer while kthreadd is trying to allocate memory for
309 * new kernel thread.
310 */
311 if (unlikely(wait_for_completion_killable(&done))) {
312 /*
313 * If I was SIGKILLed before kthreadd (or new kernel thread)
314 * calls complete(), leave the cleanup of this structure to
315 * that thread.
316 */
317 if (xchg(&create->done, NULL))
Tetsuo Handa8fe69292014-06-04 16:05:36 -0700318 return ERR_PTR(-EINTR);
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800319 /*
320 * kthreadd (or new kernel thread) will call complete()
321 * shortly.
322 */
323 wait_for_completion(&done);
324 }
325 task = create->result;
326 if (!IS_ERR(task)) {
Peter Zijlstrac9b5f502011-01-07 13:41:40 +0100327 static const struct sched_param param = { .sched_priority = 0 };
Oleg Nesterov1c993152009-04-09 09:50:36 -0600328
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800329 vsnprintf(task->comm, sizeof(task->comm), namefmt, args);
Oleg Nesterov1c993152009-04-09 09:50:36 -0600330 /*
331 * root may have changed our (kthreadd's) priority or CPU mask.
332 * The kernel thread should not inherit these properties.
333 */
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800334 sched_setscheduler_nocheck(task, SCHED_NORMAL, &param);
335 set_cpus_allowed_ptr(task, cpu_all_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 }
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800337 kfree(create);
338 return task;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339}
Petr Mladek255451e2016-10-11 13:55:27 -0700340
341/**
342 * kthread_create_on_node - create a kthread.
343 * @threadfn: the function to run until signal_pending(current).
344 * @data: data ptr for @threadfn.
345 * @node: task and thread structures for the thread are allocated on this node
346 * @namefmt: printf-style name for the thread.
347 *
348 * Description: This helper function creates and names a kernel
349 * thread. The thread will be stopped: use wake_up_process() to start
350 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
351 * is affine to all CPUs.
352 *
353 * If thread is going to be bound on a particular cpu, give its node
354 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
355 * When woken, the thread will run @threadfn() with @data as its
356 * argument. @threadfn() can either call do_exit() directly if it is a
357 * standalone thread for which no one will call kthread_stop(), or
358 * return when 'kthread_should_stop()' is true (which means
359 * kthread_stop() has been called). The return value should be zero
360 * or a negative error number; it will be passed to kthread_stop().
361 *
362 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
363 */
364struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
365 void *data, int node,
366 const char namefmt[],
367 ...)
368{
369 struct task_struct *task;
370 va_list args;
371
372 va_start(args, namefmt);
373 task = __kthread_create_on_node(threadfn, data, node, namefmt, args);
374 va_end(args);
375
376 return task;
377}
Eric Dumazet207205a2011-03-22 16:30:44 -0700378EXPORT_SYMBOL(kthread_create_on_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379
Peter Zijlstra25834c72015-05-15 17:43:34 +0200380static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state)
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000381{
Peter Zijlstra25834c72015-05-15 17:43:34 +0200382 unsigned long flags;
383
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200384 if (!wait_task_inactive(p, state)) {
385 WARN_ON(1);
386 return;
387 }
Peter Zijlstra25834c72015-05-15 17:43:34 +0200388
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000389 /* It's safe because the task is inactive. */
Peter Zijlstra25834c72015-05-15 17:43:34 +0200390 raw_spin_lock_irqsave(&p->pi_lock, flags);
391 do_set_cpus_allowed(p, mask);
Tejun Heo14a40ff2013-03-19 13:45:20 -0700392 p->flags |= PF_NO_SETAFFINITY;
Peter Zijlstra25834c72015-05-15 17:43:34 +0200393 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
394}
395
396static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
397{
398 __kthread_bind_mask(p, cpumask_of(cpu), state);
399}
400
401void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
402{
403 __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000404}
405
Randy Dunlap9e37bd32006-06-25 05:49:19 -0700406/**
Peter Zijlstra881232b2009-12-16 18:04:39 +0100407 * kthread_bind - bind a just-created kthread to a cpu.
408 * @p: thread created by kthread_create().
409 * @cpu: cpu (might not be online, must be possible) for @k to run on.
410 *
411 * Description: This function is equivalent to set_cpus_allowed(),
412 * except that @cpu doesn't need to be online, and the thread must be
413 * stopped (i.e., just returned from kthread_create()).
414 */
415void kthread_bind(struct task_struct *p, unsigned int cpu)
416{
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200417 __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
Peter Zijlstra881232b2009-12-16 18:04:39 +0100418}
419EXPORT_SYMBOL(kthread_bind);
420
421/**
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000422 * kthread_create_on_cpu - Create a cpu bound kthread
423 * @threadfn: the function to run until signal_pending(current).
424 * @data: data ptr for @threadfn.
425 * @cpu: The cpu on which the thread should be bound,
426 * @namefmt: printf-style name for the thread. Format is restricted
427 * to "name.*%u". Code fills in cpu number.
428 *
429 * Description: This helper function creates and names a kernel thread
430 * The thread will be woken and put into park mode.
431 */
432struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
433 void *data, unsigned int cpu,
434 const char *namefmt)
435{
436 struct task_struct *p;
437
Nishanth Aravamudan10922832014-10-09 15:26:18 -0700438 p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt,
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000439 cpu);
440 if (IS_ERR(p))
441 return p;
Petr Mladeka65d4092016-10-11 13:55:23 -0700442 kthread_bind(p, cpu);
443 /* CPU hotplug need to bind once again when unparking the thread. */
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000444 set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags);
445 to_kthread(p)->cpu = cpu;
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000446 return p;
447}
448
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100449/**
450 * kthread_unpark - unpark a thread created by kthread_create().
451 * @k: thread created by kthread_create().
452 *
453 * Sets kthread_should_park() for @k to return false, wakes it, and
454 * waits for it to return. If the thread is marked percpu then its
455 * bound to the cpu again.
456 */
457void kthread_unpark(struct task_struct *k)
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200458{
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100459 struct kthread *kthread = to_kthread(k);
460
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200461 /*
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200462 * Newly created kthread was parked when the CPU was offline.
463 * The binding was lost and we need to set it again.
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200464 */
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200465 if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
466 __kthread_bind(k, kthread->cpu, TASK_PARKED);
467
Peter Zijlstrab1f5b372018-05-04 11:11:42 +0200468 reinit_completion(&kthread->parked);
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200469 clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200470 /*
471 * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup.
472 */
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200473 wake_up_state(k, TASK_PARKED);
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200474}
David Kershner18896452015-08-06 15:46:45 -0700475EXPORT_SYMBOL_GPL(kthread_unpark);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000476
477/**
478 * kthread_park - park a thread created by kthread_create().
479 * @k: thread created by kthread_create().
480 *
481 * Sets kthread_should_park() for @k to return true, wakes it, and
482 * waits for it to return. This can also be called after kthread_create()
483 * instead of calling wake_up_process(): the thread will park without
484 * calling threadfn().
485 *
486 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
487 * If called by the kthread itself just the park bit is set.
488 */
489int kthread_park(struct task_struct *k)
490{
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100491 struct kthread *kthread = to_kthread(k);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000492
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100493 if (WARN_ON(k->flags & PF_EXITING))
494 return -ENOSYS;
495
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200496 set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
497 if (k != current) {
498 wake_up_process(k);
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200499 /*
500 * Wait for __kthread_parkme() to complete(), this means we
501 * _will_ have TASK_PARKED and are about to call schedule().
502 */
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200503 wait_for_completion(&kthread->parked);
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200504 /*
505 * Now wait for that schedule() to complete and the task to
506 * get scheduled out.
507 */
508 WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED));
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000509 }
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100510
511 return 0;
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000512}
David Kershner18896452015-08-06 15:46:45 -0700513EXPORT_SYMBOL_GPL(kthread_park);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000514
515/**
Randy Dunlap9e37bd32006-06-25 05:49:19 -0700516 * kthread_stop - stop a thread created by kthread_create().
517 * @k: thread created by kthread_create().
518 *
519 * Sets kthread_should_stop() for @k to return true, wakes it, and
Oleg Nesterov9ae26022009-06-19 02:51:13 +0200520 * waits for it to exit. This can also be called after kthread_create()
521 * instead of calling wake_up_process(): the thread will exit without
522 * calling threadfn().
523 *
524 * If threadfn() may call do_exit() itself, the caller must ensure
525 * task_struct can't go away.
Randy Dunlap9e37bd32006-06-25 05:49:19 -0700526 *
527 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
528 * was never called.
529 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700530int kthread_stop(struct task_struct *k)
531{
Oleg Nesterovb5c54422013-04-29 15:05:12 -0700532 struct kthread *kthread;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 int ret;
534
Oleg Nesterov63706172009-06-17 16:27:45 -0700535 trace_sched_kthread_stop(k);
Oleg Nesterovb5c54422013-04-29 15:05:12 -0700536
537 get_task_struct(k);
Oleg Nesterovefb29fb2016-11-29 18:51:03 +0100538 kthread = to_kthread(k);
539 set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100540 kthread_unpark(k);
Oleg Nesterovefb29fb2016-11-29 18:51:03 +0100541 wake_up_process(k);
542 wait_for_completion(&kthread->exited);
Oleg Nesterov63706172009-06-17 16:27:45 -0700543 ret = k->exit_code;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 put_task_struct(k);
Mathieu Desnoyers0a16b602008-07-18 12:16:17 -0400545
Oleg Nesterovb5c54422013-04-29 15:05:12 -0700546 trace_sched_kthread_stop_ret(ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 return ret;
548}
Adrian Bunk52e92e52006-07-14 00:24:05 -0700549EXPORT_SYMBOL(kthread_stop);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550
Satyam Sharmae804a4a2007-07-31 00:39:16 -0700551int kthreadd(void *unused)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552{
Eric W. Biederman73c27992007-05-09 02:34:32 -0700553 struct task_struct *tsk = current;
Eric W. Biederman73c27992007-05-09 02:34:32 -0700554
Satyam Sharmae804a4a2007-07-31 00:39:16 -0700555 /* Setup a clean context for our children to inherit. */
Eric W. Biederman73c27992007-05-09 02:34:32 -0700556 set_task_comm(tsk, "kthreadd");
Oleg Nesterov10ab8252007-05-09 02:34:37 -0700557 ignore_signals(tsk);
Rusty Russell1a2142a2009-03-30 22:05:10 -0600558 set_cpus_allowed_ptr(tsk, cpu_all_mask);
Lai Jiangshanaee4faa2012-12-12 13:51:39 -0800559 set_mems_allowed(node_states[N_MEMORY]);
Eric W. Biederman73c27992007-05-09 02:34:32 -0700560
Tejun Heo34b087e2011-11-23 09:28:17 -0800561 current->flags |= PF_NOFREEZE;
Tejun Heo77f88792017-03-16 16:54:24 -0400562 cgroup_init_kthreadd();
Eric W. Biederman73c27992007-05-09 02:34:32 -0700563
564 for (;;) {
565 set_current_state(TASK_INTERRUPTIBLE);
566 if (list_empty(&kthread_create_list))
567 schedule();
568 __set_current_state(TASK_RUNNING);
569
570 spin_lock(&kthread_create_lock);
571 while (!list_empty(&kthread_create_list)) {
572 struct kthread_create_info *create;
573
574 create = list_entry(kthread_create_list.next,
575 struct kthread_create_info, list);
576 list_del_init(&create->list);
577 spin_unlock(&kthread_create_lock);
578
579 create_kthread(create);
580
581 spin_lock(&kthread_create_lock);
582 }
583 spin_unlock(&kthread_create_lock);
584 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585
586 return 0;
587}
Tejun Heob56c0d82010-06-29 10:07:09 +0200588
Petr Mladek39891442016-10-11 13:55:20 -0700589void __kthread_init_worker(struct kthread_worker *worker,
Yong Zhang4f32e9b2010-12-22 10:27:53 +0100590 const char *name,
591 struct lock_class_key *key)
592{
Petr Mladekdbf52682016-10-11 13:55:50 -0700593 memset(worker, 0, sizeof(struct kthread_worker));
Yong Zhang4f32e9b2010-12-22 10:27:53 +0100594 spin_lock_init(&worker->lock);
595 lockdep_set_class_and_name(&worker->lock, key, name);
596 INIT_LIST_HEAD(&worker->work_list);
Petr Mladek22597dc2016-10-11 13:55:40 -0700597 INIT_LIST_HEAD(&worker->delayed_work_list);
Yong Zhang4f32e9b2010-12-22 10:27:53 +0100598}
Petr Mladek39891442016-10-11 13:55:20 -0700599EXPORT_SYMBOL_GPL(__kthread_init_worker);
Yong Zhang4f32e9b2010-12-22 10:27:53 +0100600
Tejun Heob56c0d82010-06-29 10:07:09 +0200601/**
602 * kthread_worker_fn - kthread function to process kthread_worker
603 * @worker_ptr: pointer to initialized kthread_worker
604 *
Petr Mladekfbae2d42016-10-11 13:55:30 -0700605 * This function implements the main cycle of kthread worker. It processes
606 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
607 * is empty.
Tejun Heob56c0d82010-06-29 10:07:09 +0200608 *
Petr Mladekfbae2d42016-10-11 13:55:30 -0700609 * The works are not allowed to keep any locks, disable preemption or interrupts
610 * when they finish. There is defined a safe point for freezing when one work
611 * finishes and before a new one is started.
Petr Mladek8197b3d42016-10-11 13:55:36 -0700612 *
613 * Also the works must not be handled by more than one worker at the same time,
614 * see also kthread_queue_work().
Tejun Heob56c0d82010-06-29 10:07:09 +0200615 */
616int kthread_worker_fn(void *worker_ptr)
617{
618 struct kthread_worker *worker = worker_ptr;
619 struct kthread_work *work;
620
Petr Mladekfbae2d42016-10-11 13:55:30 -0700621 /*
622 * FIXME: Update the check and remove the assignment when all kthread
623 * worker users are created using kthread_create_worker*() functions.
624 */
625 WARN_ON(worker->task && worker->task != current);
Tejun Heob56c0d82010-06-29 10:07:09 +0200626 worker->task = current;
Petr Mladekdbf52682016-10-11 13:55:50 -0700627
628 if (worker->flags & KTW_FREEZABLE)
629 set_freezable();
630
Tejun Heob56c0d82010-06-29 10:07:09 +0200631repeat:
632 set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
633
634 if (kthread_should_stop()) {
635 __set_current_state(TASK_RUNNING);
636 spin_lock_irq(&worker->lock);
637 worker->task = NULL;
638 spin_unlock_irq(&worker->lock);
639 return 0;
640 }
641
642 work = NULL;
643 spin_lock_irq(&worker->lock);
644 if (!list_empty(&worker->work_list)) {
645 work = list_first_entry(&worker->work_list,
646 struct kthread_work, node);
647 list_del_init(&work->node);
648 }
Tejun Heo46f3d972012-07-19 13:52:53 -0700649 worker->current_work = work;
Tejun Heob56c0d82010-06-29 10:07:09 +0200650 spin_unlock_irq(&worker->lock);
651
652 if (work) {
653 __set_current_state(TASK_RUNNING);
654 work->func(work);
Tejun Heob56c0d82010-06-29 10:07:09 +0200655 } else if (!freezing(current))
656 schedule();
657
658 try_to_freeze();
Shaohua Li22cf8bc2017-08-31 16:15:23 -0700659 cond_resched();
Tejun Heob56c0d82010-06-29 10:07:09 +0200660 goto repeat;
661}
662EXPORT_SYMBOL_GPL(kthread_worker_fn);
663
Nicolas Ioossc0b942a2016-12-12 16:40:39 -0800664static __printf(3, 0) struct kthread_worker *
Petr Mladekdbf52682016-10-11 13:55:50 -0700665__kthread_create_worker(int cpu, unsigned int flags,
666 const char namefmt[], va_list args)
Petr Mladekfbae2d42016-10-11 13:55:30 -0700667{
668 struct kthread_worker *worker;
669 struct task_struct *task;
Oleg Nesterov8fb9dcb2016-11-29 18:51:10 +0100670 int node = -1;
Petr Mladekfbae2d42016-10-11 13:55:30 -0700671
672 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
673 if (!worker)
674 return ERR_PTR(-ENOMEM);
675
676 kthread_init_worker(worker);
677
Oleg Nesterov8fb9dcb2016-11-29 18:51:10 +0100678 if (cpu >= 0)
679 node = cpu_to_node(cpu);
Petr Mladekfbae2d42016-10-11 13:55:30 -0700680
Oleg Nesterov8fb9dcb2016-11-29 18:51:10 +0100681 task = __kthread_create_on_node(kthread_worker_fn, worker,
682 node, namefmt, args);
Petr Mladekfbae2d42016-10-11 13:55:30 -0700683 if (IS_ERR(task))
684 goto fail_task;
685
Oleg Nesterov8fb9dcb2016-11-29 18:51:10 +0100686 if (cpu >= 0)
687 kthread_bind(task, cpu);
688
Petr Mladekdbf52682016-10-11 13:55:50 -0700689 worker->flags = flags;
Petr Mladekfbae2d42016-10-11 13:55:30 -0700690 worker->task = task;
691 wake_up_process(task);
692 return worker;
693
694fail_task:
695 kfree(worker);
696 return ERR_CAST(task);
697}
698
699/**
700 * kthread_create_worker - create a kthread worker
Petr Mladekdbf52682016-10-11 13:55:50 -0700701 * @flags: flags modifying the default behavior of the worker
Petr Mladekfbae2d42016-10-11 13:55:30 -0700702 * @namefmt: printf-style name for the kthread worker (task).
703 *
704 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
705 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
706 * when the worker was SIGKILLed.
707 */
708struct kthread_worker *
Petr Mladekdbf52682016-10-11 13:55:50 -0700709kthread_create_worker(unsigned int flags, const char namefmt[], ...)
Petr Mladekfbae2d42016-10-11 13:55:30 -0700710{
711 struct kthread_worker *worker;
712 va_list args;
713
714 va_start(args, namefmt);
Petr Mladekdbf52682016-10-11 13:55:50 -0700715 worker = __kthread_create_worker(-1, flags, namefmt, args);
Petr Mladekfbae2d42016-10-11 13:55:30 -0700716 va_end(args);
717
718 return worker;
719}
720EXPORT_SYMBOL(kthread_create_worker);
721
722/**
723 * kthread_create_worker_on_cpu - create a kthread worker and bind it
724 * it to a given CPU and the associated NUMA node.
725 * @cpu: CPU number
Petr Mladekdbf52682016-10-11 13:55:50 -0700726 * @flags: flags modifying the default behavior of the worker
Petr Mladekfbae2d42016-10-11 13:55:30 -0700727 * @namefmt: printf-style name for the kthread worker (task).
728 *
729 * Use a valid CPU number if you want to bind the kthread worker
730 * to the given CPU and the associated NUMA node.
731 *
732 * A good practice is to add the cpu number also into the worker name.
733 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
734 *
735 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
736 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
737 * when the worker was SIGKILLed.
738 */
739struct kthread_worker *
Petr Mladekdbf52682016-10-11 13:55:50 -0700740kthread_create_worker_on_cpu(int cpu, unsigned int flags,
741 const char namefmt[], ...)
Petr Mladekfbae2d42016-10-11 13:55:30 -0700742{
743 struct kthread_worker *worker;
744 va_list args;
745
746 va_start(args, namefmt);
Petr Mladekdbf52682016-10-11 13:55:50 -0700747 worker = __kthread_create_worker(cpu, flags, namefmt, args);
Petr Mladekfbae2d42016-10-11 13:55:30 -0700748 va_end(args);
749
750 return worker;
751}
752EXPORT_SYMBOL(kthread_create_worker_on_cpu);
753
Petr Mladek37be45d2016-10-11 13:55:43 -0700754/*
755 * Returns true when the work could not be queued at the moment.
756 * It happens when it is already pending in a worker list
757 * or when it is being cancelled.
758 */
759static inline bool queuing_blocked(struct kthread_worker *worker,
760 struct kthread_work *work)
761{
762 lockdep_assert_held(&worker->lock);
763
764 return !list_empty(&work->node) || work->canceling;
765}
766
Petr Mladek8197b3d42016-10-11 13:55:36 -0700767static void kthread_insert_work_sanity_check(struct kthread_worker *worker,
768 struct kthread_work *work)
Tejun Heo9a2e03d2012-07-19 13:52:53 -0700769{
770 lockdep_assert_held(&worker->lock);
Petr Mladek8197b3d42016-10-11 13:55:36 -0700771 WARN_ON_ONCE(!list_empty(&work->node));
772 /* Do not use a work with >1 worker, see kthread_queue_work() */
773 WARN_ON_ONCE(work->worker && work->worker != worker);
774}
775
776/* insert @work before @pos in @worker */
777static void kthread_insert_work(struct kthread_worker *worker,
778 struct kthread_work *work,
779 struct list_head *pos)
780{
781 kthread_insert_work_sanity_check(worker, work);
Tejun Heo9a2e03d2012-07-19 13:52:53 -0700782
783 list_add_tail(&work->node, pos);
Tejun Heo46f3d972012-07-19 13:52:53 -0700784 work->worker = worker;
Lai Jiangshaned1403e2014-07-26 12:03:59 +0800785 if (!worker->current_work && likely(worker->task))
Tejun Heo9a2e03d2012-07-19 13:52:53 -0700786 wake_up_process(worker->task);
787}
788
Tejun Heob56c0d82010-06-29 10:07:09 +0200789/**
Petr Mladek39891442016-10-11 13:55:20 -0700790 * kthread_queue_work - queue a kthread_work
Tejun Heob56c0d82010-06-29 10:07:09 +0200791 * @worker: target kthread_worker
792 * @work: kthread_work to queue
793 *
794 * Queue @work to work processor @task for async execution. @task
795 * must have been created with kthread_worker_create(). Returns %true
796 * if @work was successfully queued, %false if it was already pending.
Petr Mladek8197b3d42016-10-11 13:55:36 -0700797 *
798 * Reinitialize the work if it needs to be used by another worker.
799 * For example, when the worker was stopped and started again.
Tejun Heob56c0d82010-06-29 10:07:09 +0200800 */
Petr Mladek39891442016-10-11 13:55:20 -0700801bool kthread_queue_work(struct kthread_worker *worker,
Tejun Heob56c0d82010-06-29 10:07:09 +0200802 struct kthread_work *work)
803{
804 bool ret = false;
805 unsigned long flags;
806
807 spin_lock_irqsave(&worker->lock, flags);
Petr Mladek37be45d2016-10-11 13:55:43 -0700808 if (!queuing_blocked(worker, work)) {
Petr Mladek39891442016-10-11 13:55:20 -0700809 kthread_insert_work(worker, work, &worker->work_list);
Tejun Heob56c0d82010-06-29 10:07:09 +0200810 ret = true;
811 }
812 spin_unlock_irqrestore(&worker->lock, flags);
813 return ret;
814}
Petr Mladek39891442016-10-11 13:55:20 -0700815EXPORT_SYMBOL_GPL(kthread_queue_work);
Tejun Heob56c0d82010-06-29 10:07:09 +0200816
Petr Mladek22597dc2016-10-11 13:55:40 -0700817/**
818 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
819 * delayed work when the timer expires.
Kees Cookfe5c3b62017-10-04 16:27:06 -0700820 * @t: pointer to the expired timer
Petr Mladek22597dc2016-10-11 13:55:40 -0700821 *
822 * The format of the function is defined by struct timer_list.
823 * It should have been called from irqsafe timer with irq already off.
824 */
Kees Cookfe5c3b62017-10-04 16:27:06 -0700825void kthread_delayed_work_timer_fn(struct timer_list *t)
Petr Mladek22597dc2016-10-11 13:55:40 -0700826{
Kees Cookfe5c3b62017-10-04 16:27:06 -0700827 struct kthread_delayed_work *dwork = from_timer(dwork, t, timer);
Petr Mladek22597dc2016-10-11 13:55:40 -0700828 struct kthread_work *work = &dwork->work;
829 struct kthread_worker *worker = work->worker;
830
831 /*
832 * This might happen when a pending work is reinitialized.
833 * It means that it is used a wrong way.
834 */
835 if (WARN_ON_ONCE(!worker))
836 return;
837
838 spin_lock(&worker->lock);
839 /* Work must not be used with >1 worker, see kthread_queue_work(). */
840 WARN_ON_ONCE(work->worker != worker);
841
842 /* Move the work from worker->delayed_work_list. */
843 WARN_ON_ONCE(list_empty(&work->node));
844 list_del_init(&work->node);
845 kthread_insert_work(worker, work, &worker->work_list);
846
847 spin_unlock(&worker->lock);
848}
849EXPORT_SYMBOL(kthread_delayed_work_timer_fn);
850
851void __kthread_queue_delayed_work(struct kthread_worker *worker,
852 struct kthread_delayed_work *dwork,
853 unsigned long delay)
854{
855 struct timer_list *timer = &dwork->timer;
856 struct kthread_work *work = &dwork->work;
857
Kees Cook841b86f2017-10-23 09:40:42 +0200858 WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn);
Petr Mladek22597dc2016-10-11 13:55:40 -0700859
860 /*
861 * If @delay is 0, queue @dwork->work immediately. This is for
862 * both optimization and correctness. The earliest @timer can
863 * expire is on the closest next tick and delayed_work users depend
864 * on that there's no such delay when @delay is 0.
865 */
866 if (!delay) {
867 kthread_insert_work(worker, work, &worker->work_list);
868 return;
869 }
870
871 /* Be paranoid and try to detect possible races already now. */
872 kthread_insert_work_sanity_check(worker, work);
873
874 list_add(&work->node, &worker->delayed_work_list);
875 work->worker = worker;
Petr Mladek22597dc2016-10-11 13:55:40 -0700876 timer->expires = jiffies + delay;
877 add_timer(timer);
878}
879
880/**
881 * kthread_queue_delayed_work - queue the associated kthread work
882 * after a delay.
883 * @worker: target kthread_worker
884 * @dwork: kthread_delayed_work to queue
885 * @delay: number of jiffies to wait before queuing
886 *
887 * If the work has not been pending it starts a timer that will queue
888 * the work after the given @delay. If @delay is zero, it queues the
889 * work immediately.
890 *
891 * Return: %false if the @work has already been pending. It means that
892 * either the timer was running or the work was queued. It returns %true
893 * otherwise.
894 */
895bool kthread_queue_delayed_work(struct kthread_worker *worker,
896 struct kthread_delayed_work *dwork,
897 unsigned long delay)
898{
899 struct kthread_work *work = &dwork->work;
900 unsigned long flags;
901 bool ret = false;
902
903 spin_lock_irqsave(&worker->lock, flags);
904
Petr Mladek37be45d2016-10-11 13:55:43 -0700905 if (!queuing_blocked(worker, work)) {
Petr Mladek22597dc2016-10-11 13:55:40 -0700906 __kthread_queue_delayed_work(worker, dwork, delay);
907 ret = true;
908 }
909
910 spin_unlock_irqrestore(&worker->lock, flags);
911 return ret;
912}
913EXPORT_SYMBOL_GPL(kthread_queue_delayed_work);
914
Tejun Heo9a2e03d2012-07-19 13:52:53 -0700915struct kthread_flush_work {
916 struct kthread_work work;
917 struct completion done;
918};
919
920static void kthread_flush_work_fn(struct kthread_work *work)
921{
922 struct kthread_flush_work *fwork =
923 container_of(work, struct kthread_flush_work, work);
924 complete(&fwork->done);
925}
926
Tejun Heob56c0d82010-06-29 10:07:09 +0200927/**
Petr Mladek39891442016-10-11 13:55:20 -0700928 * kthread_flush_work - flush a kthread_work
Tejun Heob56c0d82010-06-29 10:07:09 +0200929 * @work: work to flush
930 *
931 * If @work is queued or executing, wait for it to finish execution.
932 */
Petr Mladek39891442016-10-11 13:55:20 -0700933void kthread_flush_work(struct kthread_work *work)
Tejun Heob56c0d82010-06-29 10:07:09 +0200934{
Tejun Heo46f3d972012-07-19 13:52:53 -0700935 struct kthread_flush_work fwork = {
936 KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
937 COMPLETION_INITIALIZER_ONSTACK(fwork.done),
938 };
939 struct kthread_worker *worker;
940 bool noop = false;
Tejun Heob56c0d82010-06-29 10:07:09 +0200941
Tejun Heo46f3d972012-07-19 13:52:53 -0700942 worker = work->worker;
943 if (!worker)
944 return;
Tejun Heob56c0d82010-06-29 10:07:09 +0200945
Tejun Heo46f3d972012-07-19 13:52:53 -0700946 spin_lock_irq(&worker->lock);
Petr Mladek8197b3d42016-10-11 13:55:36 -0700947 /* Work must not be used with >1 worker, see kthread_queue_work(). */
948 WARN_ON_ONCE(work->worker != worker);
Tejun Heob56c0d82010-06-29 10:07:09 +0200949
Tejun Heo46f3d972012-07-19 13:52:53 -0700950 if (!list_empty(&work->node))
Petr Mladek39891442016-10-11 13:55:20 -0700951 kthread_insert_work(worker, &fwork.work, work->node.next);
Tejun Heo46f3d972012-07-19 13:52:53 -0700952 else if (worker->current_work == work)
Petr Mladek39891442016-10-11 13:55:20 -0700953 kthread_insert_work(worker, &fwork.work,
954 worker->work_list.next);
Tejun Heo46f3d972012-07-19 13:52:53 -0700955 else
956 noop = true;
Tejun Heob56c0d82010-06-29 10:07:09 +0200957
Tejun Heo46f3d972012-07-19 13:52:53 -0700958 spin_unlock_irq(&worker->lock);
959
960 if (!noop)
961 wait_for_completion(&fwork.done);
Tejun Heob56c0d82010-06-29 10:07:09 +0200962}
Petr Mladek39891442016-10-11 13:55:20 -0700963EXPORT_SYMBOL_GPL(kthread_flush_work);
Tejun Heob56c0d82010-06-29 10:07:09 +0200964
Petr Mladek37be45d2016-10-11 13:55:43 -0700965/*
966 * This function removes the work from the worker queue. Also it makes sure
967 * that it won't get queued later via the delayed work's timer.
968 *
969 * The work might still be in use when this function finishes. See the
970 * current_work proceed by the worker.
971 *
972 * Return: %true if @work was pending and successfully canceled,
973 * %false if @work was not pending
974 */
975static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork,
976 unsigned long *flags)
977{
978 /* Try to cancel the timer if exists. */
979 if (is_dwork) {
980 struct kthread_delayed_work *dwork =
981 container_of(work, struct kthread_delayed_work, work);
982 struct kthread_worker *worker = work->worker;
983
984 /*
985 * del_timer_sync() must be called to make sure that the timer
986 * callback is not running. The lock must be temporary released
987 * to avoid a deadlock with the callback. In the meantime,
988 * any queuing is blocked by setting the canceling counter.
989 */
990 work->canceling++;
991 spin_unlock_irqrestore(&worker->lock, *flags);
992 del_timer_sync(&dwork->timer);
993 spin_lock_irqsave(&worker->lock, *flags);
994 work->canceling--;
995 }
996
997 /*
998 * Try to remove the work from a worker list. It might either
999 * be from worker->work_list or from worker->delayed_work_list.
1000 */
1001 if (!list_empty(&work->node)) {
1002 list_del_init(&work->node);
1003 return true;
1004 }
1005
1006 return false;
1007}
1008
Petr Mladek9a6b06c2016-10-11 13:55:46 -07001009/**
1010 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
1011 * @worker: kthread worker to use
1012 * @dwork: kthread delayed work to queue
1013 * @delay: number of jiffies to wait before queuing
1014 *
1015 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
1016 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
1017 * @work is guaranteed to be queued immediately.
1018 *
1019 * Return: %true if @dwork was pending and its timer was modified,
1020 * %false otherwise.
1021 *
1022 * A special case is when the work is being canceled in parallel.
1023 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1024 * or yet another kthread_mod_delayed_work() call. We let the other command
1025 * win and return %false here. The caller is supposed to synchronize these
1026 * operations a reasonable way.
1027 *
1028 * This function is safe to call from any context including IRQ handler.
1029 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1030 * for details.
1031 */
1032bool kthread_mod_delayed_work(struct kthread_worker *worker,
1033 struct kthread_delayed_work *dwork,
1034 unsigned long delay)
1035{
1036 struct kthread_work *work = &dwork->work;
1037 unsigned long flags;
1038 int ret = false;
1039
1040 spin_lock_irqsave(&worker->lock, flags);
1041
1042 /* Do not bother with canceling when never queued. */
1043 if (!work->worker)
1044 goto fast_queue;
1045
1046 /* Work must not be used with >1 worker, see kthread_queue_work() */
1047 WARN_ON_ONCE(work->worker != worker);
1048
1049 /* Do not fight with another command that is canceling this work. */
1050 if (work->canceling)
1051 goto out;
1052
1053 ret = __kthread_cancel_work(work, true, &flags);
1054fast_queue:
1055 __kthread_queue_delayed_work(worker, dwork, delay);
1056out:
1057 spin_unlock_irqrestore(&worker->lock, flags);
1058 return ret;
1059}
1060EXPORT_SYMBOL_GPL(kthread_mod_delayed_work);
1061
Petr Mladek37be45d2016-10-11 13:55:43 -07001062static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork)
1063{
1064 struct kthread_worker *worker = work->worker;
1065 unsigned long flags;
1066 int ret = false;
1067
1068 if (!worker)
1069 goto out;
1070
1071 spin_lock_irqsave(&worker->lock, flags);
1072 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1073 WARN_ON_ONCE(work->worker != worker);
1074
1075 ret = __kthread_cancel_work(work, is_dwork, &flags);
1076
1077 if (worker->current_work != work)
1078 goto out_fast;
1079
1080 /*
1081 * The work is in progress and we need to wait with the lock released.
1082 * In the meantime, block any queuing by setting the canceling counter.
1083 */
1084 work->canceling++;
1085 spin_unlock_irqrestore(&worker->lock, flags);
1086 kthread_flush_work(work);
1087 spin_lock_irqsave(&worker->lock, flags);
1088 work->canceling--;
1089
1090out_fast:
1091 spin_unlock_irqrestore(&worker->lock, flags);
1092out:
1093 return ret;
1094}
1095
1096/**
1097 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1098 * @work: the kthread work to cancel
1099 *
1100 * Cancel @work and wait for its execution to finish. This function
1101 * can be used even if the work re-queues itself. On return from this
1102 * function, @work is guaranteed to be not pending or executing on any CPU.
1103 *
1104 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1105 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1106 *
1107 * The caller must ensure that the worker on which @work was last
1108 * queued can't be destroyed before this function returns.
1109 *
1110 * Return: %true if @work was pending, %false otherwise.
1111 */
1112bool kthread_cancel_work_sync(struct kthread_work *work)
1113{
1114 return __kthread_cancel_work_sync(work, false);
1115}
1116EXPORT_SYMBOL_GPL(kthread_cancel_work_sync);
1117
1118/**
1119 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1120 * wait for it to finish.
1121 * @dwork: the kthread delayed work to cancel
1122 *
1123 * This is kthread_cancel_work_sync() for delayed works.
1124 *
1125 * Return: %true if @dwork was pending, %false otherwise.
1126 */
1127bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork)
1128{
1129 return __kthread_cancel_work_sync(&dwork->work, true);
1130}
1131EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync);
1132
Tejun Heob56c0d82010-06-29 10:07:09 +02001133/**
Petr Mladek39891442016-10-11 13:55:20 -07001134 * kthread_flush_worker - flush all current works on a kthread_worker
Tejun Heob56c0d82010-06-29 10:07:09 +02001135 * @worker: worker to flush
1136 *
1137 * Wait until all currently executing or pending works on @worker are
1138 * finished.
1139 */
Petr Mladek39891442016-10-11 13:55:20 -07001140void kthread_flush_worker(struct kthread_worker *worker)
Tejun Heob56c0d82010-06-29 10:07:09 +02001141{
1142 struct kthread_flush_work fwork = {
1143 KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
1144 COMPLETION_INITIALIZER_ONSTACK(fwork.done),
1145 };
1146
Petr Mladek39891442016-10-11 13:55:20 -07001147 kthread_queue_work(worker, &fwork.work);
Tejun Heob56c0d82010-06-29 10:07:09 +02001148 wait_for_completion(&fwork.done);
1149}
Petr Mladek39891442016-10-11 13:55:20 -07001150EXPORT_SYMBOL_GPL(kthread_flush_worker);
Petr Mladek35033fe2016-10-11 13:55:33 -07001151
1152/**
1153 * kthread_destroy_worker - destroy a kthread worker
1154 * @worker: worker to be destroyed
1155 *
1156 * Flush and destroy @worker. The simple flush is enough because the kthread
1157 * worker API is used only in trivial scenarios. There are no multi-step state
1158 * machines needed.
1159 */
1160void kthread_destroy_worker(struct kthread_worker *worker)
1161{
1162 struct task_struct *task;
1163
1164 task = worker->task;
1165 if (WARN_ON(!task))
1166 return;
1167
1168 kthread_flush_worker(worker);
1169 kthread_stop(task);
1170 WARN_ON(!list_empty(&worker->work_list));
1171 kfree(worker);
1172}
1173EXPORT_SYMBOL(kthread_destroy_worker);
Shaohua Li05e3db92017-09-14 14:02:04 -07001174
Shaohua Li0b508bc2017-09-26 11:02:12 -07001175#ifdef CONFIG_BLK_CGROUP
Shaohua Li05e3db92017-09-14 14:02:04 -07001176/**
1177 * kthread_associate_blkcg - associate blkcg to current kthread
1178 * @css: the cgroup info
1179 *
1180 * Current thread must be a kthread. The thread is running jobs on behalf of
1181 * other threads. In some cases, we expect the jobs attach cgroup info of
1182 * original threads instead of that of current thread. This function stores
1183 * original thread's cgroup info in current kthread context for later
1184 * retrieval.
1185 */
1186void kthread_associate_blkcg(struct cgroup_subsys_state *css)
1187{
1188 struct kthread *kthread;
1189
1190 if (!(current->flags & PF_KTHREAD))
1191 return;
1192 kthread = to_kthread(current);
1193 if (!kthread)
1194 return;
1195
1196 if (kthread->blkcg_css) {
1197 css_put(kthread->blkcg_css);
1198 kthread->blkcg_css = NULL;
1199 }
1200 if (css) {
1201 css_get(css);
1202 kthread->blkcg_css = css;
1203 }
1204}
1205EXPORT_SYMBOL(kthread_associate_blkcg);
1206
1207/**
1208 * kthread_blkcg - get associated blkcg css of current kthread
1209 *
1210 * Current thread must be a kthread.
1211 */
1212struct cgroup_subsys_state *kthread_blkcg(void)
1213{
1214 struct kthread *kthread;
1215
1216 if (current->flags & PF_KTHREAD) {
1217 kthread = to_kthread(current);
1218 if (kthread)
1219 return kthread->blkcg_css;
1220 }
1221 return NULL;
1222}
1223EXPORT_SYMBOL(kthread_blkcg);
1224#endif