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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>
Anshuman Khandual98fa15f2019-03-05 15:42:58 -080023#include <linux/numa.h>
Steven Rostedtad8d75f2009-04-14 19:39:12 -040024#include <trace/events/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025
Eric W. Biederman73c27992007-05-09 02:34:32 -070026static DEFINE_SPINLOCK(kthread_create_lock);
27static LIST_HEAD(kthread_create_list);
28struct task_struct *kthreadd_task;
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
30struct kthread_create_info
31{
Eric W. Biederman73c27992007-05-09 02:34:32 -070032 /* Information passed to kthread() from kthreadd. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070033 int (*threadfn)(void *data);
34 void *data;
Eric Dumazet207205a2011-03-22 16:30:44 -070035 int node;
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
Eric W. Biederman73c27992007-05-09 02:34:32 -070037 /* Result passed back to kthread_create() from kthreadd. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 struct task_struct *result;
Tetsuo Handa786235ee2013-11-12 15:06:45 -080039 struct completion *done;
David Howells65f27f32006-11-22 14:55:48 +000040
Eric W. Biederman73c27992007-05-09 02:34:32 -070041 struct list_head list;
Linus Torvalds1da177e2005-04-16 15:20:36 -070042};
43
Oleg Nesterov63706172009-06-17 16:27:45 -070044struct kthread {
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000045 unsigned long flags;
46 unsigned int cpu;
Tejun Heo82805ab2010-06-29 10:07:09 +020047 void *data;
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000048 struct completion parked;
Oleg Nesterov63706172009-06-17 16:27:45 -070049 struct completion exited;
Shaohua Li0b508bc2017-09-26 11:02:12 -070050#ifdef CONFIG_BLK_CGROUP
Shaohua Li05e3db92017-09-14 14:02:04 -070051 struct cgroup_subsys_state *blkcg_css;
52#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070053};
54
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000055enum KTHREAD_BITS {
56 KTHREAD_IS_PER_CPU = 0,
57 KTHREAD_SHOULD_STOP,
58 KTHREAD_SHOULD_PARK,
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000059};
60
Oleg Nesterov1da5c462016-11-29 18:50:57 +010061static inline void set_kthread_struct(void *kthread)
62{
63 /*
64 * We abuse ->set_child_tid to avoid the new member and because it
65 * can't be wrongly copied by copy_process(). We also rely on fact
66 * that the caller can't exec, so PF_KTHREAD can't be cleared.
67 */
68 current->set_child_tid = (__force void __user *)kthread;
69}
Oleg Nesterov4ecdafc2013-04-29 15:05:01 -070070
71static inline struct kthread *to_kthread(struct task_struct *k)
72{
Oleg Nesterov1da5c462016-11-29 18:50:57 +010073 WARN_ON(!(k->flags & PF_KTHREAD));
74 return (__force void *)k->set_child_tid;
Oleg Nesterov4ecdafc2013-04-29 15:05:01 -070075}
76
Oleg Nesterov1da5c462016-11-29 18:50:57 +010077void free_kthread_struct(struct task_struct *k)
78{
Shaohua Li05e3db92017-09-14 14:02:04 -070079 struct kthread *kthread;
80
Oleg Nesterov1da5c462016-11-29 18:50:57 +010081 /*
82 * Can be NULL if this kthread was created by kernel_thread()
83 * or if kmalloc() in kthread() failed.
84 */
Shaohua Li05e3db92017-09-14 14:02:04 -070085 kthread = to_kthread(k);
Shaohua Li0b508bc2017-09-26 11:02:12 -070086#ifdef CONFIG_BLK_CGROUP
Shaohua Li05e3db92017-09-14 14:02:04 -070087 WARN_ON_ONCE(kthread && kthread->blkcg_css);
88#endif
89 kfree(kthread);
Oleg Nesterov1da5c462016-11-29 18:50:57 +010090}
91
Randy Dunlap9e37bd32006-06-25 05:49:19 -070092/**
93 * kthread_should_stop - should this kthread return now?
94 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -080095 * When someone calls kthread_stop() on your kthread, it will be woken
Randy Dunlap9e37bd32006-06-25 05:49:19 -070096 * and this will return true. You should then return, and your return
97 * value will be passed through to kthread_stop().
98 */
Thomas Gleixner2a1d4462012-07-16 10:42:36 +000099bool kthread_should_stop(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100{
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000101 return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102}
103EXPORT_SYMBOL(kthread_should_stop);
104
Tejun Heo82805ab2010-06-29 10:07:09 +0200105/**
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000106 * kthread_should_park - should this kthread park now?
107 *
108 * When someone calls kthread_park() on your kthread, it will be woken
109 * and this will return true. You should then do the necessary
110 * cleanup and call kthread_parkme()
111 *
112 * Similar to kthread_should_stop(), but this keeps the thread alive
113 * and in a park position. kthread_unpark() "restarts" the thread and
114 * calls the thread function again.
115 */
116bool kthread_should_park(void)
117{
118 return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags);
119}
David Kershner18896452015-08-06 15:46:45 -0700120EXPORT_SYMBOL_GPL(kthread_should_park);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000121
122/**
Tejun Heo8a32c442011-11-21 12:32:23 -0800123 * kthread_freezable_should_stop - should this freezable kthread return now?
124 * @was_frozen: optional out parameter, indicates whether %current was frozen
125 *
126 * kthread_should_stop() for freezable kthreads, which will enter
127 * refrigerator if necessary. This function is safe from kthread_stop() /
128 * freezer deadlock and freezable kthreads should use this function instead
129 * of calling try_to_freeze() directly.
130 */
131bool kthread_freezable_should_stop(bool *was_frozen)
132{
133 bool frozen = false;
134
135 might_sleep();
136
137 if (unlikely(freezing(current)))
138 frozen = __refrigerator(true);
139
140 if (was_frozen)
141 *was_frozen = frozen;
142
143 return kthread_should_stop();
144}
145EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
146
147/**
Tejun Heo82805ab2010-06-29 10:07:09 +0200148 * kthread_data - return data value specified on kthread creation
149 * @task: kthread task in question
150 *
151 * Return the data value specified when kthread @task was created.
152 * The caller is responsible for ensuring the validity of @task when
153 * calling this function.
154 */
155void *kthread_data(struct task_struct *task)
156{
157 return to_kthread(task)->data;
158}
159
Tejun Heocd42d552013-04-30 15:27:21 -0700160/**
Petr Mladeke7005912016-10-11 13:55:17 -0700161 * kthread_probe_data - speculative version of kthread_data()
Tejun Heocd42d552013-04-30 15:27:21 -0700162 * @task: possible kthread task in question
163 *
164 * @task could be a kthread task. Return the data value specified when it
165 * was created if accessible. If @task isn't a kthread task or its data is
166 * inaccessible for any reason, %NULL is returned. This function requires
167 * that @task itself is safe to dereference.
168 */
Petr Mladeke7005912016-10-11 13:55:17 -0700169void *kthread_probe_data(struct task_struct *task)
Tejun Heocd42d552013-04-30 15:27:21 -0700170{
171 struct kthread *kthread = to_kthread(task);
172 void *data = NULL;
173
174 probe_kernel_read(&data, &kthread->data, sizeof(data));
175 return data;
176}
177
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000178static void __kthread_parkme(struct kthread *self)
179{
Peter Zijlstra741a76b2018-04-30 14:50:22 +0200180 for (;;) {
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200181 /*
182 * TASK_PARKED is a special state; we must serialize against
183 * possible pending wakeups to avoid store-store collisions on
184 * task->state.
185 *
186 * Such a collision might possibly result in the task state
187 * changin from TASK_PARKED and us failing the
188 * wait_task_inactive() in kthread_park().
189 */
190 set_special_state(TASK_PARKED);
Peter Zijlstra741a76b2018-04-30 14:50:22 +0200191 if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags))
192 break;
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200193
Peter Zijlstraf83ee192018-06-07 10:55:56 +0200194 complete(&self->parked);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000195 schedule();
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000196 }
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000197 __set_current_state(TASK_RUNNING);
198}
199
200void kthread_parkme(void)
201{
202 __kthread_parkme(to_kthread(current));
203}
David Kershner18896452015-08-06 15:46:45 -0700204EXPORT_SYMBOL_GPL(kthread_parkme);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000205
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206static int kthread(void *_create)
207{
Eric W. Biederman73c27992007-05-09 02:34:32 -0700208 /* Copy data: it's on kthread's stack */
Oleg Nesterov63706172009-06-17 16:27:45 -0700209 struct kthread_create_info *create = _create;
210 int (*threadfn)(void *data) = create->threadfn;
211 void *data = create->data;
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800212 struct completion *done;
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100213 struct kthread *self;
Oleg Nesterov63706172009-06-17 16:27:45 -0700214 int ret;
215
Shaohua Lie10237c2017-11-07 11:09:50 -0800216 self = kzalloc(sizeof(*self), GFP_KERNEL);
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100217 set_kthread_struct(self);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800219 /* If user was SIGKILLed, I release the structure. */
220 done = xchg(&create->done, NULL);
221 if (!done) {
222 kfree(create);
223 do_exit(-EINTR);
224 }
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100225
226 if (!self) {
227 create->result = ERR_PTR(-ENOMEM);
228 complete(done);
229 do_exit(-ENOMEM);
230 }
231
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100232 self->data = data;
233 init_completion(&self->exited);
234 init_completion(&self->parked);
235 current->vfork_done = &self->exited;
236
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 /* OK, tell user we're spawned, wait for stop or wakeup */
Oleg Nesterova076e4b2007-05-23 13:57:27 -0700238 __set_current_state(TASK_UNINTERRUPTIBLE);
Vitaliy Gusev3217ab92009-04-09 09:50:35 -0600239 create->result = current;
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800240 complete(done);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 schedule();
242
Oleg Nesterov63706172009-06-17 16:27:45 -0700243 ret = -EINTR;
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100244 if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) {
Tejun Heo77f88792017-03-16 16:54:24 -0400245 cgroup_kthread_ready();
Oleg Nesterov1da5c462016-11-29 18:50:57 +0100246 __kthread_parkme(self);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000247 ret = threadfn(data);
248 }
Oleg Nesterov63706172009-06-17 16:27:45 -0700249 do_exit(ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250}
251
Eric Dumazet207205a2011-03-22 16:30:44 -0700252/* called from do_fork() to get node information for about to be created task */
253int tsk_fork_get_node(struct task_struct *tsk)
254{
255#ifdef CONFIG_NUMA
256 if (tsk == kthreadd_task)
257 return tsk->pref_node_fork;
258#endif
Nishanth Aravamudan81c98862014-04-03 14:46:25 -0700259 return NUMA_NO_NODE;
Eric Dumazet207205a2011-03-22 16:30:44 -0700260}
261
Eric W. Biederman73c27992007-05-09 02:34:32 -0700262static void create_kthread(struct kthread_create_info *create)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 int pid;
265
Eric Dumazet207205a2011-03-22 16:30:44 -0700266#ifdef CONFIG_NUMA
267 current->pref_node_fork = create->node;
268#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 /* We want our own signal handler (we take no signals by default). */
270 pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
Oleg Nesterovcdd140b2009-06-17 16:27:43 -0700271 if (pid < 0) {
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800272 /* If user was SIGKILLed, I release the structure. */
273 struct completion *done = xchg(&create->done, NULL);
274
275 if (!done) {
276 kfree(create);
277 return;
278 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 create->result = ERR_PTR(pid);
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800280 complete(done);
Oleg Nesterovcdd140b2009-06-17 16:27:43 -0700281 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282}
283
Nicolas Ioossc0b942a2016-12-12 16:40:39 -0800284static __printf(4, 0)
285struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
Petr Mladek255451e2016-10-11 13:55:27 -0700286 void *data, int node,
287 const char namefmt[],
288 va_list args)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289{
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800290 DECLARE_COMPLETION_ONSTACK(done);
291 struct task_struct *task;
292 struct kthread_create_info *create = kmalloc(sizeof(*create),
293 GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800295 if (!create)
296 return ERR_PTR(-ENOMEM);
297 create->threadfn = threadfn;
298 create->data = data;
299 create->node = node;
300 create->done = &done;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301
Eric W. Biederman73c27992007-05-09 02:34:32 -0700302 spin_lock(&kthread_create_lock);
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800303 list_add_tail(&create->list, &kthread_create_list);
Eric W. Biederman73c27992007-05-09 02:34:32 -0700304 spin_unlock(&kthread_create_lock);
305
Dmitry Adamushkocbd9b672008-04-29 00:59:23 -0700306 wake_up_process(kthreadd_task);
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800307 /*
308 * Wait for completion in killable state, for I might be chosen by
309 * the OOM killer while kthreadd is trying to allocate memory for
310 * new kernel thread.
311 */
312 if (unlikely(wait_for_completion_killable(&done))) {
313 /*
314 * If I was SIGKILLed before kthreadd (or new kernel thread)
315 * calls complete(), leave the cleanup of this structure to
316 * that thread.
317 */
318 if (xchg(&create->done, NULL))
Tetsuo Handa8fe69292014-06-04 16:05:36 -0700319 return ERR_PTR(-EINTR);
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800320 /*
321 * kthreadd (or new kernel thread) will call complete()
322 * shortly.
323 */
324 wait_for_completion(&done);
325 }
326 task = create->result;
327 if (!IS_ERR(task)) {
Peter Zijlstrac9b5f502011-01-07 13:41:40 +0100328 static const struct sched_param param = { .sched_priority = 0 };
Snild Dolkow3e536e22018-07-26 09:15:39 +0200329 char name[TASK_COMM_LEN];
Oleg Nesterov1c993152009-04-09 09:50:36 -0600330
Snild Dolkow3e536e22018-07-26 09:15:39 +0200331 /*
332 * task is already visible to other tasks, so updating
333 * COMM must be protected.
334 */
335 vsnprintf(name, sizeof(name), namefmt, args);
336 set_task_comm(task, name);
Oleg Nesterov1c993152009-04-09 09:50:36 -0600337 /*
338 * root may have changed our (kthreadd's) priority or CPU mask.
339 * The kernel thread should not inherit these properties.
340 */
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800341 sched_setscheduler_nocheck(task, SCHED_NORMAL, &param);
342 set_cpus_allowed_ptr(task, cpu_all_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 }
Tetsuo Handa786235ee2013-11-12 15:06:45 -0800344 kfree(create);
345 return task;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346}
Petr Mladek255451e2016-10-11 13:55:27 -0700347
348/**
349 * kthread_create_on_node - create a kthread.
350 * @threadfn: the function to run until signal_pending(current).
351 * @data: data ptr for @threadfn.
352 * @node: task and thread structures for the thread are allocated on this node
353 * @namefmt: printf-style name for the thread.
354 *
355 * Description: This helper function creates and names a kernel
356 * thread. The thread will be stopped: use wake_up_process() to start
357 * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
358 * is affine to all CPUs.
359 *
360 * If thread is going to be bound on a particular cpu, give its node
361 * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
362 * When woken, the thread will run @threadfn() with @data as its
363 * argument. @threadfn() can either call do_exit() directly if it is a
364 * standalone thread for which no one will call kthread_stop(), or
365 * return when 'kthread_should_stop()' is true (which means
366 * kthread_stop() has been called). The return value should be zero
367 * or a negative error number; it will be passed to kthread_stop().
368 *
369 * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
370 */
371struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
372 void *data, int node,
373 const char namefmt[],
374 ...)
375{
376 struct task_struct *task;
377 va_list args;
378
379 va_start(args, namefmt);
380 task = __kthread_create_on_node(threadfn, data, node, namefmt, args);
381 va_end(args);
382
383 return task;
384}
Eric Dumazet207205a2011-03-22 16:30:44 -0700385EXPORT_SYMBOL(kthread_create_on_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386
Peter Zijlstra25834c72015-05-15 17:43:34 +0200387static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state)
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000388{
Peter Zijlstra25834c72015-05-15 17:43:34 +0200389 unsigned long flags;
390
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200391 if (!wait_task_inactive(p, state)) {
392 WARN_ON(1);
393 return;
394 }
Peter Zijlstra25834c72015-05-15 17:43:34 +0200395
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000396 /* It's safe because the task is inactive. */
Peter Zijlstra25834c72015-05-15 17:43:34 +0200397 raw_spin_lock_irqsave(&p->pi_lock, flags);
398 do_set_cpus_allowed(p, mask);
Tejun Heo14a40ff2013-03-19 13:45:20 -0700399 p->flags |= PF_NO_SETAFFINITY;
Peter Zijlstra25834c72015-05-15 17:43:34 +0200400 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
401}
402
403static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
404{
405 __kthread_bind_mask(p, cpumask_of(cpu), state);
406}
407
408void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
409{
410 __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000411}
412
Randy Dunlap9e37bd32006-06-25 05:49:19 -0700413/**
Peter Zijlstra881232b2009-12-16 18:04:39 +0100414 * kthread_bind - bind a just-created kthread to a cpu.
415 * @p: thread created by kthread_create().
416 * @cpu: cpu (might not be online, must be possible) for @k to run on.
417 *
418 * Description: This function is equivalent to set_cpus_allowed(),
419 * except that @cpu doesn't need to be online, and the thread must be
420 * stopped (i.e., just returned from kthread_create()).
421 */
422void kthread_bind(struct task_struct *p, unsigned int cpu)
423{
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200424 __kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
Peter Zijlstra881232b2009-12-16 18:04:39 +0100425}
426EXPORT_SYMBOL(kthread_bind);
427
428/**
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000429 * kthread_create_on_cpu - Create a cpu bound kthread
430 * @threadfn: the function to run until signal_pending(current).
431 * @data: data ptr for @threadfn.
432 * @cpu: The cpu on which the thread should be bound,
433 * @namefmt: printf-style name for the thread. Format is restricted
434 * to "name.*%u". Code fills in cpu number.
435 *
436 * Description: This helper function creates and names a kernel thread
437 * The thread will be woken and put into park mode.
438 */
439struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
440 void *data, unsigned int cpu,
441 const char *namefmt)
442{
443 struct task_struct *p;
444
Nishanth Aravamudan10922832014-10-09 15:26:18 -0700445 p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt,
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000446 cpu);
447 if (IS_ERR(p))
448 return p;
Petr Mladeka65d4092016-10-11 13:55:23 -0700449 kthread_bind(p, cpu);
450 /* CPU hotplug need to bind once again when unparking the thread. */
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000451 set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags);
452 to_kthread(p)->cpu = cpu;
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000453 return p;
454}
455
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100456/**
457 * kthread_unpark - unpark a thread created by kthread_create().
458 * @k: thread created by kthread_create().
459 *
460 * Sets kthread_should_park() for @k to return false, wakes it, and
461 * waits for it to return. If the thread is marked percpu then its
462 * bound to the cpu again.
463 */
464void kthread_unpark(struct task_struct *k)
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200465{
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100466 struct kthread *kthread = to_kthread(k);
467
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200468 /*
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200469 * Newly created kthread was parked when the CPU was offline.
470 * The binding was lost and we need to set it again.
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200471 */
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200472 if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
473 __kthread_bind(k, kthread->cpu, TASK_PARKED);
474
475 clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200476 /*
477 * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup.
478 */
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200479 wake_up_state(k, TASK_PARKED);
Thomas Gleixnerf2530dc2013-04-09 09:33:34 +0200480}
David Kershner18896452015-08-06 15:46:45 -0700481EXPORT_SYMBOL_GPL(kthread_unpark);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000482
483/**
484 * kthread_park - park a thread created by kthread_create().
485 * @k: thread created by kthread_create().
486 *
487 * Sets kthread_should_park() for @k to return true, wakes it, and
488 * waits for it to return. This can also be called after kthread_create()
489 * instead of calling wake_up_process(): the thread will park without
490 * calling threadfn().
491 *
492 * Returns 0 if the thread is parked, -ENOSYS if the thread exited.
493 * If called by the kthread itself just the park bit is set.
494 */
495int kthread_park(struct task_struct *k)
496{
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100497 struct kthread *kthread = to_kthread(k);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000498
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100499 if (WARN_ON(k->flags & PF_EXITING))
500 return -ENOSYS;
501
Peter Zijlstraf83ee192018-06-07 10:55:56 +0200502 if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags)))
503 return -EBUSY;
504
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200505 set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
506 if (k != current) {
507 wake_up_process(k);
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200508 /*
509 * Wait for __kthread_parkme() to complete(), this means we
510 * _will_ have TASK_PARKED and are about to call schedule().
511 */
Peter Zijlstra85f1abe2018-05-01 18:14:45 +0200512 wait_for_completion(&kthread->parked);
Peter Zijlstra1cef1152018-06-07 11:45:49 +0200513 /*
514 * Now wait for that schedule() to complete and the task to
515 * get scheduled out.
516 */
517 WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED));
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000518 }
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100519
520 return 0;
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000521}
David Kershner18896452015-08-06 15:46:45 -0700522EXPORT_SYMBOL_GPL(kthread_park);
Thomas Gleixner2a1d4462012-07-16 10:42:36 +0000523
524/**
Randy Dunlap9e37bd32006-06-25 05:49:19 -0700525 * kthread_stop - stop a thread created by kthread_create().
526 * @k: thread created by kthread_create().
527 *
528 * Sets kthread_should_stop() for @k to return true, wakes it, and
Oleg Nesterov9ae26022009-06-19 02:51:13 +0200529 * waits for it to exit. This can also be called after kthread_create()
530 * instead of calling wake_up_process(): the thread will exit without
531 * calling threadfn().
532 *
533 * If threadfn() may call do_exit() itself, the caller must ensure
534 * task_struct can't go away.
Randy Dunlap9e37bd32006-06-25 05:49:19 -0700535 *
536 * Returns the result of threadfn(), or %-EINTR if wake_up_process()
537 * was never called.
538 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539int kthread_stop(struct task_struct *k)
540{
Oleg Nesterovb5c54422013-04-29 15:05:12 -0700541 struct kthread *kthread;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 int ret;
543
Oleg Nesterov63706172009-06-17 16:27:45 -0700544 trace_sched_kthread_stop(k);
Oleg Nesterovb5c54422013-04-29 15:05:12 -0700545
546 get_task_struct(k);
Oleg Nesterovefb29fb2016-11-29 18:51:03 +0100547 kthread = to_kthread(k);
548 set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
Oleg Nesterovcf380a42016-11-29 18:51:07 +0100549 kthread_unpark(k);
Oleg Nesterovefb29fb2016-11-29 18:51:03 +0100550 wake_up_process(k);
551 wait_for_completion(&kthread->exited);
Oleg Nesterov63706172009-06-17 16:27:45 -0700552 ret = k->exit_code;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 put_task_struct(k);
Mathieu Desnoyers0a16b602008-07-18 12:16:17 -0400554
Oleg Nesterovb5c54422013-04-29 15:05:12 -0700555 trace_sched_kthread_stop_ret(ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 return ret;
557}
Adrian Bunk52e92e52006-07-14 00:24:05 -0700558EXPORT_SYMBOL(kthread_stop);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559
Satyam Sharmae804a4a2007-07-31 00:39:16 -0700560int kthreadd(void *unused)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561{
Eric W. Biederman73c27992007-05-09 02:34:32 -0700562 struct task_struct *tsk = current;
Eric W. Biederman73c27992007-05-09 02:34:32 -0700563
Satyam Sharmae804a4a2007-07-31 00:39:16 -0700564 /* Setup a clean context for our children to inherit. */
Eric W. Biederman73c27992007-05-09 02:34:32 -0700565 set_task_comm(tsk, "kthreadd");
Oleg Nesterov10ab8252007-05-09 02:34:37 -0700566 ignore_signals(tsk);
Rusty Russell1a2142a2009-03-30 22:05:10 -0600567 set_cpus_allowed_ptr(tsk, cpu_all_mask);
Lai Jiangshanaee4faa2012-12-12 13:51:39 -0800568 set_mems_allowed(node_states[N_MEMORY]);
Eric W. Biederman73c27992007-05-09 02:34:32 -0700569
Tejun Heo34b087e2011-11-23 09:28:17 -0800570 current->flags |= PF_NOFREEZE;
Tejun Heo77f88792017-03-16 16:54:24 -0400571 cgroup_init_kthreadd();
Eric W. Biederman73c27992007-05-09 02:34:32 -0700572
573 for (;;) {
574 set_current_state(TASK_INTERRUPTIBLE);
575 if (list_empty(&kthread_create_list))
576 schedule();
577 __set_current_state(TASK_RUNNING);
578
579 spin_lock(&kthread_create_lock);
580 while (!list_empty(&kthread_create_list)) {
581 struct kthread_create_info *create;
582
583 create = list_entry(kthread_create_list.next,
584 struct kthread_create_info, list);
585 list_del_init(&create->list);
586 spin_unlock(&kthread_create_lock);
587
588 create_kthread(create);
589
590 spin_lock(&kthread_create_lock);
591 }
592 spin_unlock(&kthread_create_lock);
593 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594
595 return 0;
596}
Tejun Heob56c0d82010-06-29 10:07:09 +0200597
Petr Mladek39891442016-10-11 13:55:20 -0700598void __kthread_init_worker(struct kthread_worker *worker,
Yong Zhang4f32e9b2010-12-22 10:27:53 +0100599 const char *name,
600 struct lock_class_key *key)
601{
Petr Mladekdbf52682016-10-11 13:55:50 -0700602 memset(worker, 0, sizeof(struct kthread_worker));
Yong Zhang4f32e9b2010-12-22 10:27:53 +0100603 spin_lock_init(&worker->lock);
604 lockdep_set_class_and_name(&worker->lock, key, name);
605 INIT_LIST_HEAD(&worker->work_list);
Petr Mladek22597dc2016-10-11 13:55:40 -0700606 INIT_LIST_HEAD(&worker->delayed_work_list);
Yong Zhang4f32e9b2010-12-22 10:27:53 +0100607}
Petr Mladek39891442016-10-11 13:55:20 -0700608EXPORT_SYMBOL_GPL(__kthread_init_worker);
Yong Zhang4f32e9b2010-12-22 10:27:53 +0100609
Tejun Heob56c0d82010-06-29 10:07:09 +0200610/**
611 * kthread_worker_fn - kthread function to process kthread_worker
612 * @worker_ptr: pointer to initialized kthread_worker
613 *
Petr Mladekfbae2d42016-10-11 13:55:30 -0700614 * This function implements the main cycle of kthread worker. It processes
615 * work_list until it is stopped with kthread_stop(). It sleeps when the queue
616 * is empty.
Tejun Heob56c0d82010-06-29 10:07:09 +0200617 *
Petr Mladekfbae2d42016-10-11 13:55:30 -0700618 * The works are not allowed to keep any locks, disable preemption or interrupts
619 * when they finish. There is defined a safe point for freezing when one work
620 * finishes and before a new one is started.
Petr Mladek8197b3d42016-10-11 13:55:36 -0700621 *
622 * Also the works must not be handled by more than one worker at the same time,
623 * see also kthread_queue_work().
Tejun Heob56c0d82010-06-29 10:07:09 +0200624 */
625int kthread_worker_fn(void *worker_ptr)
626{
627 struct kthread_worker *worker = worker_ptr;
628 struct kthread_work *work;
629
Petr Mladekfbae2d42016-10-11 13:55:30 -0700630 /*
631 * FIXME: Update the check and remove the assignment when all kthread
632 * worker users are created using kthread_create_worker*() functions.
633 */
634 WARN_ON(worker->task && worker->task != current);
Tejun Heob56c0d82010-06-29 10:07:09 +0200635 worker->task = current;
Petr Mladekdbf52682016-10-11 13:55:50 -0700636
637 if (worker->flags & KTW_FREEZABLE)
638 set_freezable();
639
Tejun Heob56c0d82010-06-29 10:07:09 +0200640repeat:
641 set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
642
643 if (kthread_should_stop()) {
644 __set_current_state(TASK_RUNNING);
645 spin_lock_irq(&worker->lock);
646 worker->task = NULL;
647 spin_unlock_irq(&worker->lock);
648 return 0;
649 }
650
651 work = NULL;
652 spin_lock_irq(&worker->lock);
653 if (!list_empty(&worker->work_list)) {
654 work = list_first_entry(&worker->work_list,
655 struct kthread_work, node);
656 list_del_init(&work->node);
657 }
Tejun Heo46f3d972012-07-19 13:52:53 -0700658 worker->current_work = work;
Tejun Heob56c0d82010-06-29 10:07:09 +0200659 spin_unlock_irq(&worker->lock);
660
661 if (work) {
662 __set_current_state(TASK_RUNNING);
663 work->func(work);
Tejun Heob56c0d82010-06-29 10:07:09 +0200664 } else if (!freezing(current))
665 schedule();
666
667 try_to_freeze();
Shaohua Li22cf8bc2017-08-31 16:15:23 -0700668 cond_resched();
Tejun Heob56c0d82010-06-29 10:07:09 +0200669 goto repeat;
670}
671EXPORT_SYMBOL_GPL(kthread_worker_fn);
672
Nicolas Ioossc0b942a2016-12-12 16:40:39 -0800673static __printf(3, 0) struct kthread_worker *
Petr Mladekdbf52682016-10-11 13:55:50 -0700674__kthread_create_worker(int cpu, unsigned int flags,
675 const char namefmt[], va_list args)
Petr Mladekfbae2d42016-10-11 13:55:30 -0700676{
677 struct kthread_worker *worker;
678 struct task_struct *task;
Anshuman Khandual98fa15f2019-03-05 15:42:58 -0800679 int node = NUMA_NO_NODE;
Petr Mladekfbae2d42016-10-11 13:55:30 -0700680
681 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
682 if (!worker)
683 return ERR_PTR(-ENOMEM);
684
685 kthread_init_worker(worker);
686
Oleg Nesterov8fb9dcb2016-11-29 18:51:10 +0100687 if (cpu >= 0)
688 node = cpu_to_node(cpu);
Petr Mladekfbae2d42016-10-11 13:55:30 -0700689
Oleg Nesterov8fb9dcb2016-11-29 18:51:10 +0100690 task = __kthread_create_on_node(kthread_worker_fn, worker,
691 node, namefmt, args);
Petr Mladekfbae2d42016-10-11 13:55:30 -0700692 if (IS_ERR(task))
693 goto fail_task;
694
Oleg Nesterov8fb9dcb2016-11-29 18:51:10 +0100695 if (cpu >= 0)
696 kthread_bind(task, cpu);
697
Petr Mladekdbf52682016-10-11 13:55:50 -0700698 worker->flags = flags;
Petr Mladekfbae2d42016-10-11 13:55:30 -0700699 worker->task = task;
700 wake_up_process(task);
701 return worker;
702
703fail_task:
704 kfree(worker);
705 return ERR_CAST(task);
706}
707
708/**
709 * kthread_create_worker - create a kthread worker
Petr Mladekdbf52682016-10-11 13:55:50 -0700710 * @flags: flags modifying the default behavior of the worker
Petr Mladekfbae2d42016-10-11 13:55:30 -0700711 * @namefmt: printf-style name for the kthread worker (task).
712 *
713 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
714 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
715 * when the worker was SIGKILLed.
716 */
717struct kthread_worker *
Petr Mladekdbf52682016-10-11 13:55:50 -0700718kthread_create_worker(unsigned int flags, const char namefmt[], ...)
Petr Mladekfbae2d42016-10-11 13:55:30 -0700719{
720 struct kthread_worker *worker;
721 va_list args;
722
723 va_start(args, namefmt);
Petr Mladekdbf52682016-10-11 13:55:50 -0700724 worker = __kthread_create_worker(-1, flags, namefmt, args);
Petr Mladekfbae2d42016-10-11 13:55:30 -0700725 va_end(args);
726
727 return worker;
728}
729EXPORT_SYMBOL(kthread_create_worker);
730
731/**
732 * kthread_create_worker_on_cpu - create a kthread worker and bind it
733 * it to a given CPU and the associated NUMA node.
734 * @cpu: CPU number
Petr Mladekdbf52682016-10-11 13:55:50 -0700735 * @flags: flags modifying the default behavior of the worker
Petr Mladekfbae2d42016-10-11 13:55:30 -0700736 * @namefmt: printf-style name for the kthread worker (task).
737 *
738 * Use a valid CPU number if you want to bind the kthread worker
739 * to the given CPU and the associated NUMA node.
740 *
741 * A good practice is to add the cpu number also into the worker name.
742 * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
743 *
744 * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
745 * when the needed structures could not get allocated, and ERR_PTR(-EINTR)
746 * when the worker was SIGKILLed.
747 */
748struct kthread_worker *
Petr Mladekdbf52682016-10-11 13:55:50 -0700749kthread_create_worker_on_cpu(int cpu, unsigned int flags,
750 const char namefmt[], ...)
Petr Mladekfbae2d42016-10-11 13:55:30 -0700751{
752 struct kthread_worker *worker;
753 va_list args;
754
755 va_start(args, namefmt);
Petr Mladekdbf52682016-10-11 13:55:50 -0700756 worker = __kthread_create_worker(cpu, flags, namefmt, args);
Petr Mladekfbae2d42016-10-11 13:55:30 -0700757 va_end(args);
758
759 return worker;
760}
761EXPORT_SYMBOL(kthread_create_worker_on_cpu);
762
Petr Mladek37be45d2016-10-11 13:55:43 -0700763/*
764 * Returns true when the work could not be queued at the moment.
765 * It happens when it is already pending in a worker list
766 * or when it is being cancelled.
767 */
768static inline bool queuing_blocked(struct kthread_worker *worker,
769 struct kthread_work *work)
770{
771 lockdep_assert_held(&worker->lock);
772
773 return !list_empty(&work->node) || work->canceling;
774}
775
Petr Mladek8197b3d42016-10-11 13:55:36 -0700776static void kthread_insert_work_sanity_check(struct kthread_worker *worker,
777 struct kthread_work *work)
Tejun Heo9a2e03d2012-07-19 13:52:53 -0700778{
779 lockdep_assert_held(&worker->lock);
Petr Mladek8197b3d42016-10-11 13:55:36 -0700780 WARN_ON_ONCE(!list_empty(&work->node));
781 /* Do not use a work with >1 worker, see kthread_queue_work() */
782 WARN_ON_ONCE(work->worker && work->worker != worker);
783}
784
785/* insert @work before @pos in @worker */
786static void kthread_insert_work(struct kthread_worker *worker,
787 struct kthread_work *work,
788 struct list_head *pos)
789{
790 kthread_insert_work_sanity_check(worker, work);
Tejun Heo9a2e03d2012-07-19 13:52:53 -0700791
792 list_add_tail(&work->node, pos);
Tejun Heo46f3d972012-07-19 13:52:53 -0700793 work->worker = worker;
Lai Jiangshaned1403e2014-07-26 12:03:59 +0800794 if (!worker->current_work && likely(worker->task))
Tejun Heo9a2e03d2012-07-19 13:52:53 -0700795 wake_up_process(worker->task);
796}
797
Tejun Heob56c0d82010-06-29 10:07:09 +0200798/**
Petr Mladek39891442016-10-11 13:55:20 -0700799 * kthread_queue_work - queue a kthread_work
Tejun Heob56c0d82010-06-29 10:07:09 +0200800 * @worker: target kthread_worker
801 * @work: kthread_work to queue
802 *
803 * Queue @work to work processor @task for async execution. @task
804 * must have been created with kthread_worker_create(). Returns %true
805 * if @work was successfully queued, %false if it was already pending.
Petr Mladek8197b3d42016-10-11 13:55:36 -0700806 *
807 * Reinitialize the work if it needs to be used by another worker.
808 * For example, when the worker was stopped and started again.
Tejun Heob56c0d82010-06-29 10:07:09 +0200809 */
Petr Mladek39891442016-10-11 13:55:20 -0700810bool kthread_queue_work(struct kthread_worker *worker,
Tejun Heob56c0d82010-06-29 10:07:09 +0200811 struct kthread_work *work)
812{
813 bool ret = false;
814 unsigned long flags;
815
816 spin_lock_irqsave(&worker->lock, flags);
Petr Mladek37be45d2016-10-11 13:55:43 -0700817 if (!queuing_blocked(worker, work)) {
Petr Mladek39891442016-10-11 13:55:20 -0700818 kthread_insert_work(worker, work, &worker->work_list);
Tejun Heob56c0d82010-06-29 10:07:09 +0200819 ret = true;
820 }
821 spin_unlock_irqrestore(&worker->lock, flags);
822 return ret;
823}
Petr Mladek39891442016-10-11 13:55:20 -0700824EXPORT_SYMBOL_GPL(kthread_queue_work);
Tejun Heob56c0d82010-06-29 10:07:09 +0200825
Petr Mladek22597dc2016-10-11 13:55:40 -0700826/**
827 * kthread_delayed_work_timer_fn - callback that queues the associated kthread
828 * delayed work when the timer expires.
Kees Cookfe5c3b62017-10-04 16:27:06 -0700829 * @t: pointer to the expired timer
Petr Mladek22597dc2016-10-11 13:55:40 -0700830 *
831 * The format of the function is defined by struct timer_list.
832 * It should have been called from irqsafe timer with irq already off.
833 */
Kees Cookfe5c3b62017-10-04 16:27:06 -0700834void kthread_delayed_work_timer_fn(struct timer_list *t)
Petr Mladek22597dc2016-10-11 13:55:40 -0700835{
Kees Cookfe5c3b62017-10-04 16:27:06 -0700836 struct kthread_delayed_work *dwork = from_timer(dwork, t, timer);
Petr Mladek22597dc2016-10-11 13:55:40 -0700837 struct kthread_work *work = &dwork->work;
838 struct kthread_worker *worker = work->worker;
839
840 /*
841 * This might happen when a pending work is reinitialized.
842 * It means that it is used a wrong way.
843 */
844 if (WARN_ON_ONCE(!worker))
845 return;
846
847 spin_lock(&worker->lock);
848 /* Work must not be used with >1 worker, see kthread_queue_work(). */
849 WARN_ON_ONCE(work->worker != worker);
850
851 /* Move the work from worker->delayed_work_list. */
852 WARN_ON_ONCE(list_empty(&work->node));
853 list_del_init(&work->node);
854 kthread_insert_work(worker, work, &worker->work_list);
855
856 spin_unlock(&worker->lock);
857}
858EXPORT_SYMBOL(kthread_delayed_work_timer_fn);
859
860void __kthread_queue_delayed_work(struct kthread_worker *worker,
861 struct kthread_delayed_work *dwork,
862 unsigned long delay)
863{
864 struct timer_list *timer = &dwork->timer;
865 struct kthread_work *work = &dwork->work;
866
Kees Cook841b86f2017-10-23 09:40:42 +0200867 WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn);
Petr Mladek22597dc2016-10-11 13:55:40 -0700868
869 /*
870 * If @delay is 0, queue @dwork->work immediately. This is for
871 * both optimization and correctness. The earliest @timer can
872 * expire is on the closest next tick and delayed_work users depend
873 * on that there's no such delay when @delay is 0.
874 */
875 if (!delay) {
876 kthread_insert_work(worker, work, &worker->work_list);
877 return;
878 }
879
880 /* Be paranoid and try to detect possible races already now. */
881 kthread_insert_work_sanity_check(worker, work);
882
883 list_add(&work->node, &worker->delayed_work_list);
884 work->worker = worker;
Petr Mladek22597dc2016-10-11 13:55:40 -0700885 timer->expires = jiffies + delay;
886 add_timer(timer);
887}
888
889/**
890 * kthread_queue_delayed_work - queue the associated kthread work
891 * after a delay.
892 * @worker: target kthread_worker
893 * @dwork: kthread_delayed_work to queue
894 * @delay: number of jiffies to wait before queuing
895 *
896 * If the work has not been pending it starts a timer that will queue
897 * the work after the given @delay. If @delay is zero, it queues the
898 * work immediately.
899 *
900 * Return: %false if the @work has already been pending. It means that
901 * either the timer was running or the work was queued. It returns %true
902 * otherwise.
903 */
904bool kthread_queue_delayed_work(struct kthread_worker *worker,
905 struct kthread_delayed_work *dwork,
906 unsigned long delay)
907{
908 struct kthread_work *work = &dwork->work;
909 unsigned long flags;
910 bool ret = false;
911
912 spin_lock_irqsave(&worker->lock, flags);
913
Petr Mladek37be45d2016-10-11 13:55:43 -0700914 if (!queuing_blocked(worker, work)) {
Petr Mladek22597dc2016-10-11 13:55:40 -0700915 __kthread_queue_delayed_work(worker, dwork, delay);
916 ret = true;
917 }
918
919 spin_unlock_irqrestore(&worker->lock, flags);
920 return ret;
921}
922EXPORT_SYMBOL_GPL(kthread_queue_delayed_work);
923
Tejun Heo9a2e03d2012-07-19 13:52:53 -0700924struct kthread_flush_work {
925 struct kthread_work work;
926 struct completion done;
927};
928
929static void kthread_flush_work_fn(struct kthread_work *work)
930{
931 struct kthread_flush_work *fwork =
932 container_of(work, struct kthread_flush_work, work);
933 complete(&fwork->done);
934}
935
Tejun Heob56c0d82010-06-29 10:07:09 +0200936/**
Petr Mladek39891442016-10-11 13:55:20 -0700937 * kthread_flush_work - flush a kthread_work
Tejun Heob56c0d82010-06-29 10:07:09 +0200938 * @work: work to flush
939 *
940 * If @work is queued or executing, wait for it to finish execution.
941 */
Petr Mladek39891442016-10-11 13:55:20 -0700942void kthread_flush_work(struct kthread_work *work)
Tejun Heob56c0d82010-06-29 10:07:09 +0200943{
Tejun Heo46f3d972012-07-19 13:52:53 -0700944 struct kthread_flush_work fwork = {
945 KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
946 COMPLETION_INITIALIZER_ONSTACK(fwork.done),
947 };
948 struct kthread_worker *worker;
949 bool noop = false;
Tejun Heob56c0d82010-06-29 10:07:09 +0200950
Tejun Heo46f3d972012-07-19 13:52:53 -0700951 worker = work->worker;
952 if (!worker)
953 return;
Tejun Heob56c0d82010-06-29 10:07:09 +0200954
Tejun Heo46f3d972012-07-19 13:52:53 -0700955 spin_lock_irq(&worker->lock);
Petr Mladek8197b3d42016-10-11 13:55:36 -0700956 /* Work must not be used with >1 worker, see kthread_queue_work(). */
957 WARN_ON_ONCE(work->worker != worker);
Tejun Heob56c0d82010-06-29 10:07:09 +0200958
Tejun Heo46f3d972012-07-19 13:52:53 -0700959 if (!list_empty(&work->node))
Petr Mladek39891442016-10-11 13:55:20 -0700960 kthread_insert_work(worker, &fwork.work, work->node.next);
Tejun Heo46f3d972012-07-19 13:52:53 -0700961 else if (worker->current_work == work)
Petr Mladek39891442016-10-11 13:55:20 -0700962 kthread_insert_work(worker, &fwork.work,
963 worker->work_list.next);
Tejun Heo46f3d972012-07-19 13:52:53 -0700964 else
965 noop = true;
Tejun Heob56c0d82010-06-29 10:07:09 +0200966
Tejun Heo46f3d972012-07-19 13:52:53 -0700967 spin_unlock_irq(&worker->lock);
968
969 if (!noop)
970 wait_for_completion(&fwork.done);
Tejun Heob56c0d82010-06-29 10:07:09 +0200971}
Petr Mladek39891442016-10-11 13:55:20 -0700972EXPORT_SYMBOL_GPL(kthread_flush_work);
Tejun Heob56c0d82010-06-29 10:07:09 +0200973
Petr Mladek37be45d2016-10-11 13:55:43 -0700974/*
975 * This function removes the work from the worker queue. Also it makes sure
976 * that it won't get queued later via the delayed work's timer.
977 *
978 * The work might still be in use when this function finishes. See the
979 * current_work proceed by the worker.
980 *
981 * Return: %true if @work was pending and successfully canceled,
982 * %false if @work was not pending
983 */
984static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork,
985 unsigned long *flags)
986{
987 /* Try to cancel the timer if exists. */
988 if (is_dwork) {
989 struct kthread_delayed_work *dwork =
990 container_of(work, struct kthread_delayed_work, work);
991 struct kthread_worker *worker = work->worker;
992
993 /*
994 * del_timer_sync() must be called to make sure that the timer
995 * callback is not running. The lock must be temporary released
996 * to avoid a deadlock with the callback. In the meantime,
997 * any queuing is blocked by setting the canceling counter.
998 */
999 work->canceling++;
1000 spin_unlock_irqrestore(&worker->lock, *flags);
1001 del_timer_sync(&dwork->timer);
1002 spin_lock_irqsave(&worker->lock, *flags);
1003 work->canceling--;
1004 }
1005
1006 /*
1007 * Try to remove the work from a worker list. It might either
1008 * be from worker->work_list or from worker->delayed_work_list.
1009 */
1010 if (!list_empty(&work->node)) {
1011 list_del_init(&work->node);
1012 return true;
1013 }
1014
1015 return false;
1016}
1017
Petr Mladek9a6b06c2016-10-11 13:55:46 -07001018/**
1019 * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
1020 * @worker: kthread worker to use
1021 * @dwork: kthread delayed work to queue
1022 * @delay: number of jiffies to wait before queuing
1023 *
1024 * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
1025 * modify @dwork's timer so that it expires after @delay. If @delay is zero,
1026 * @work is guaranteed to be queued immediately.
1027 *
1028 * Return: %true if @dwork was pending and its timer was modified,
1029 * %false otherwise.
1030 *
1031 * A special case is when the work is being canceled in parallel.
1032 * It might be caused either by the real kthread_cancel_delayed_work_sync()
1033 * or yet another kthread_mod_delayed_work() call. We let the other command
1034 * win and return %false here. The caller is supposed to synchronize these
1035 * operations a reasonable way.
1036 *
1037 * This function is safe to call from any context including IRQ handler.
1038 * See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
1039 * for details.
1040 */
1041bool kthread_mod_delayed_work(struct kthread_worker *worker,
1042 struct kthread_delayed_work *dwork,
1043 unsigned long delay)
1044{
1045 struct kthread_work *work = &dwork->work;
1046 unsigned long flags;
1047 int ret = false;
1048
1049 spin_lock_irqsave(&worker->lock, flags);
1050
1051 /* Do not bother with canceling when never queued. */
1052 if (!work->worker)
1053 goto fast_queue;
1054
1055 /* Work must not be used with >1 worker, see kthread_queue_work() */
1056 WARN_ON_ONCE(work->worker != worker);
1057
1058 /* Do not fight with another command that is canceling this work. */
1059 if (work->canceling)
1060 goto out;
1061
1062 ret = __kthread_cancel_work(work, true, &flags);
1063fast_queue:
1064 __kthread_queue_delayed_work(worker, dwork, delay);
1065out:
1066 spin_unlock_irqrestore(&worker->lock, flags);
1067 return ret;
1068}
1069EXPORT_SYMBOL_GPL(kthread_mod_delayed_work);
1070
Petr Mladek37be45d2016-10-11 13:55:43 -07001071static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork)
1072{
1073 struct kthread_worker *worker = work->worker;
1074 unsigned long flags;
1075 int ret = false;
1076
1077 if (!worker)
1078 goto out;
1079
1080 spin_lock_irqsave(&worker->lock, flags);
1081 /* Work must not be used with >1 worker, see kthread_queue_work(). */
1082 WARN_ON_ONCE(work->worker != worker);
1083
1084 ret = __kthread_cancel_work(work, is_dwork, &flags);
1085
1086 if (worker->current_work != work)
1087 goto out_fast;
1088
1089 /*
1090 * The work is in progress and we need to wait with the lock released.
1091 * In the meantime, block any queuing by setting the canceling counter.
1092 */
1093 work->canceling++;
1094 spin_unlock_irqrestore(&worker->lock, flags);
1095 kthread_flush_work(work);
1096 spin_lock_irqsave(&worker->lock, flags);
1097 work->canceling--;
1098
1099out_fast:
1100 spin_unlock_irqrestore(&worker->lock, flags);
1101out:
1102 return ret;
1103}
1104
1105/**
1106 * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
1107 * @work: the kthread work to cancel
1108 *
1109 * Cancel @work and wait for its execution to finish. This function
1110 * can be used even if the work re-queues itself. On return from this
1111 * function, @work is guaranteed to be not pending or executing on any CPU.
1112 *
1113 * kthread_cancel_work_sync(&delayed_work->work) must not be used for
1114 * delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
1115 *
1116 * The caller must ensure that the worker on which @work was last
1117 * queued can't be destroyed before this function returns.
1118 *
1119 * Return: %true if @work was pending, %false otherwise.
1120 */
1121bool kthread_cancel_work_sync(struct kthread_work *work)
1122{
1123 return __kthread_cancel_work_sync(work, false);
1124}
1125EXPORT_SYMBOL_GPL(kthread_cancel_work_sync);
1126
1127/**
1128 * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
1129 * wait for it to finish.
1130 * @dwork: the kthread delayed work to cancel
1131 *
1132 * This is kthread_cancel_work_sync() for delayed works.
1133 *
1134 * Return: %true if @dwork was pending, %false otherwise.
1135 */
1136bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork)
1137{
1138 return __kthread_cancel_work_sync(&dwork->work, true);
1139}
1140EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync);
1141
Tejun Heob56c0d82010-06-29 10:07:09 +02001142/**
Petr Mladek39891442016-10-11 13:55:20 -07001143 * kthread_flush_worker - flush all current works on a kthread_worker
Tejun Heob56c0d82010-06-29 10:07:09 +02001144 * @worker: worker to flush
1145 *
1146 * Wait until all currently executing or pending works on @worker are
1147 * finished.
1148 */
Petr Mladek39891442016-10-11 13:55:20 -07001149void kthread_flush_worker(struct kthread_worker *worker)
Tejun Heob56c0d82010-06-29 10:07:09 +02001150{
1151 struct kthread_flush_work fwork = {
1152 KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
1153 COMPLETION_INITIALIZER_ONSTACK(fwork.done),
1154 };
1155
Petr Mladek39891442016-10-11 13:55:20 -07001156 kthread_queue_work(worker, &fwork.work);
Tejun Heob56c0d82010-06-29 10:07:09 +02001157 wait_for_completion(&fwork.done);
1158}
Petr Mladek39891442016-10-11 13:55:20 -07001159EXPORT_SYMBOL_GPL(kthread_flush_worker);
Petr Mladek35033fe2016-10-11 13:55:33 -07001160
1161/**
1162 * kthread_destroy_worker - destroy a kthread worker
1163 * @worker: worker to be destroyed
1164 *
1165 * Flush and destroy @worker. The simple flush is enough because the kthread
1166 * worker API is used only in trivial scenarios. There are no multi-step state
1167 * machines needed.
1168 */
1169void kthread_destroy_worker(struct kthread_worker *worker)
1170{
1171 struct task_struct *task;
1172
1173 task = worker->task;
1174 if (WARN_ON(!task))
1175 return;
1176
1177 kthread_flush_worker(worker);
1178 kthread_stop(task);
1179 WARN_ON(!list_empty(&worker->work_list));
1180 kfree(worker);
1181}
1182EXPORT_SYMBOL(kthread_destroy_worker);
Shaohua Li05e3db92017-09-14 14:02:04 -07001183
Shaohua Li0b508bc2017-09-26 11:02:12 -07001184#ifdef CONFIG_BLK_CGROUP
Shaohua Li05e3db92017-09-14 14:02:04 -07001185/**
1186 * kthread_associate_blkcg - associate blkcg to current kthread
1187 * @css: the cgroup info
1188 *
1189 * Current thread must be a kthread. The thread is running jobs on behalf of
1190 * other threads. In some cases, we expect the jobs attach cgroup info of
1191 * original threads instead of that of current thread. This function stores
1192 * original thread's cgroup info in current kthread context for later
1193 * retrieval.
1194 */
1195void kthread_associate_blkcg(struct cgroup_subsys_state *css)
1196{
1197 struct kthread *kthread;
1198
1199 if (!(current->flags & PF_KTHREAD))
1200 return;
1201 kthread = to_kthread(current);
1202 if (!kthread)
1203 return;
1204
1205 if (kthread->blkcg_css) {
1206 css_put(kthread->blkcg_css);
1207 kthread->blkcg_css = NULL;
1208 }
1209 if (css) {
1210 css_get(css);
1211 kthread->blkcg_css = css;
1212 }
1213}
1214EXPORT_SYMBOL(kthread_associate_blkcg);
1215
1216/**
1217 * kthread_blkcg - get associated blkcg css of current kthread
1218 *
1219 * Current thread must be a kthread.
1220 */
1221struct cgroup_subsys_state *kthread_blkcg(void)
1222{
1223 struct kthread *kthread;
1224
1225 if (current->flags & PF_KTHREAD) {
1226 kthread = to_kthread(current);
1227 if (kthread)
1228 return kthread->blkcg_css;
1229 }
1230 return NULL;
1231}
1232EXPORT_SYMBOL(kthread_blkcg);
1233#endif