xref: /linux-6.15/kernel/workqueue.c (revision 23b2e599)
11da177e4SLinus Torvalds /*
21da177e4SLinus Torvalds  * linux/kernel/workqueue.c
31da177e4SLinus Torvalds  *
41da177e4SLinus Torvalds  * Generic mechanism for defining kernel helper threads for running
51da177e4SLinus Torvalds  * arbitrary tasks in process context.
61da177e4SLinus Torvalds  *
71da177e4SLinus Torvalds  * Started by Ingo Molnar, Copyright (C) 2002
81da177e4SLinus Torvalds  *
91da177e4SLinus Torvalds  * Derived from the taskqueue/keventd code by:
101da177e4SLinus Torvalds  *
111da177e4SLinus Torvalds  *   David Woodhouse <[email protected]>
121da177e4SLinus Torvalds  *   Andrew Morton <[email protected]>
131da177e4SLinus Torvalds  *   Kai Petzke <[email protected]>
141da177e4SLinus Torvalds  *   Theodore Ts'o <[email protected]>
1589ada679SChristoph Lameter  *
1689ada679SChristoph Lameter  * Made to use alloc_percpu by Christoph Lameter <[email protected]>.
171da177e4SLinus Torvalds  */
181da177e4SLinus Torvalds 
191da177e4SLinus Torvalds #include <linux/module.h>
201da177e4SLinus Torvalds #include <linux/kernel.h>
211da177e4SLinus Torvalds #include <linux/sched.h>
221da177e4SLinus Torvalds #include <linux/init.h>
231da177e4SLinus Torvalds #include <linux/signal.h>
241da177e4SLinus Torvalds #include <linux/completion.h>
251da177e4SLinus Torvalds #include <linux/workqueue.h>
261da177e4SLinus Torvalds #include <linux/slab.h>
271da177e4SLinus Torvalds #include <linux/cpu.h>
281da177e4SLinus Torvalds #include <linux/notifier.h>
291da177e4SLinus Torvalds #include <linux/kthread.h>
301fa44ecaSJames Bottomley #include <linux/hardirq.h>
3146934023SChristoph Lameter #include <linux/mempolicy.h>
32341a5958SRafael J. Wysocki #include <linux/freezer.h>
33d5abe669SPeter Zijlstra #include <linux/kallsyms.h>
34d5abe669SPeter Zijlstra #include <linux/debug_locks.h>
351da177e4SLinus Torvalds 
361da177e4SLinus Torvalds /*
37f756d5e2SNathan Lynch  * The per-CPU workqueue (if single thread, we always use the first
38f756d5e2SNathan Lynch  * possible cpu).
391da177e4SLinus Torvalds  */
401da177e4SLinus Torvalds struct cpu_workqueue_struct {
411da177e4SLinus Torvalds 
421da177e4SLinus Torvalds 	spinlock_t lock;
431da177e4SLinus Torvalds 
441da177e4SLinus Torvalds 	struct list_head worklist;
451da177e4SLinus Torvalds 	wait_queue_head_t more_work;
463af24433SOleg Nesterov 	struct work_struct *current_work;
471da177e4SLinus Torvalds 
481da177e4SLinus Torvalds 	struct workqueue_struct *wq;
4936c8b586SIngo Molnar 	struct task_struct *thread;
503af24433SOleg Nesterov 	int should_stop;
511da177e4SLinus Torvalds 
521da177e4SLinus Torvalds 	int run_depth;		/* Detect run_workqueue() recursion depth */
531da177e4SLinus Torvalds } ____cacheline_aligned;
541da177e4SLinus Torvalds 
551da177e4SLinus Torvalds /*
561da177e4SLinus Torvalds  * The externally visible workqueue abstraction is an array of
571da177e4SLinus Torvalds  * per-CPU workqueues:
581da177e4SLinus Torvalds  */
591da177e4SLinus Torvalds struct workqueue_struct {
6089ada679SChristoph Lameter 	struct cpu_workqueue_struct *cpu_wq;
61cce1a165SOleg Nesterov 	struct list_head list;
621da177e4SLinus Torvalds 	const char *name;
63cce1a165SOleg Nesterov 	int singlethread;
64319c2a98SOleg Nesterov 	int freezeable;		/* Freeze threads during suspend */
651da177e4SLinus Torvalds };
661da177e4SLinus Torvalds 
671da177e4SLinus Torvalds /* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
681da177e4SLinus Torvalds    threads to each one as cpus come/go. */
699b41ea72SAndrew Morton static DEFINE_MUTEX(workqueue_mutex);
701da177e4SLinus Torvalds static LIST_HEAD(workqueues);
711da177e4SLinus Torvalds 
723af24433SOleg Nesterov static int singlethread_cpu __read_mostly;
73b1f4ec17SOleg Nesterov static cpumask_t cpu_singlethread_map __read_mostly;
743af24433SOleg Nesterov /* optimization, we could use cpu_possible_map */
753af24433SOleg Nesterov static cpumask_t cpu_populated_map __read_mostly;
76f756d5e2SNathan Lynch 
771da177e4SLinus Torvalds /* If it's single threaded, it isn't in the list of workqueues. */
781da177e4SLinus Torvalds static inline int is_single_threaded(struct workqueue_struct *wq)
791da177e4SLinus Torvalds {
80cce1a165SOleg Nesterov 	return wq->singlethread;
811da177e4SLinus Torvalds }
821da177e4SLinus Torvalds 
83b1f4ec17SOleg Nesterov static const cpumask_t *wq_cpu_map(struct workqueue_struct *wq)
84b1f4ec17SOleg Nesterov {
85b1f4ec17SOleg Nesterov 	return is_single_threaded(wq)
86b1f4ec17SOleg Nesterov 		? &cpu_singlethread_map : &cpu_populated_map;
87b1f4ec17SOleg Nesterov }
88b1f4ec17SOleg Nesterov 
89a848e3b6SOleg Nesterov static
90a848e3b6SOleg Nesterov struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
91a848e3b6SOleg Nesterov {
92a848e3b6SOleg Nesterov 	if (unlikely(is_single_threaded(wq)))
93a848e3b6SOleg Nesterov 		cpu = singlethread_cpu;
94a848e3b6SOleg Nesterov 	return per_cpu_ptr(wq->cpu_wq, cpu);
95a848e3b6SOleg Nesterov }
96a848e3b6SOleg Nesterov 
974594bf15SDavid Howells /*
984594bf15SDavid Howells  * Set the workqueue on which a work item is to be run
994594bf15SDavid Howells  * - Must *only* be called if the pending flag is set
1004594bf15SDavid Howells  */
101ed7c0feeSOleg Nesterov static inline void set_wq_data(struct work_struct *work,
102ed7c0feeSOleg Nesterov 				struct cpu_workqueue_struct *cwq)
103365970a1SDavid Howells {
1044594bf15SDavid Howells 	unsigned long new;
105365970a1SDavid Howells 
1064594bf15SDavid Howells 	BUG_ON(!work_pending(work));
1074594bf15SDavid Howells 
108ed7c0feeSOleg Nesterov 	new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING);
109a08727baSLinus Torvalds 	new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work);
110a08727baSLinus Torvalds 	atomic_long_set(&work->data, new);
111365970a1SDavid Howells }
112365970a1SDavid Howells 
113ed7c0feeSOleg Nesterov static inline
114ed7c0feeSOleg Nesterov struct cpu_workqueue_struct *get_wq_data(struct work_struct *work)
115365970a1SDavid Howells {
116a08727baSLinus Torvalds 	return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK);
117365970a1SDavid Howells }
118365970a1SDavid Howells 
119b89deed3SOleg Nesterov static void insert_work(struct cpu_workqueue_struct *cwq,
120b89deed3SOleg Nesterov 				struct work_struct *work, int tail)
121b89deed3SOleg Nesterov {
122b89deed3SOleg Nesterov 	set_wq_data(work, cwq);
123b89deed3SOleg Nesterov 	if (tail)
124b89deed3SOleg Nesterov 		list_add_tail(&work->entry, &cwq->worklist);
125b89deed3SOleg Nesterov 	else
126b89deed3SOleg Nesterov 		list_add(&work->entry, &cwq->worklist);
127b89deed3SOleg Nesterov 	wake_up(&cwq->more_work);
128b89deed3SOleg Nesterov }
129b89deed3SOleg Nesterov 
1301da177e4SLinus Torvalds /* Preempt must be disabled. */
1311da177e4SLinus Torvalds static void __queue_work(struct cpu_workqueue_struct *cwq,
1321da177e4SLinus Torvalds 			 struct work_struct *work)
1331da177e4SLinus Torvalds {
1341da177e4SLinus Torvalds 	unsigned long flags;
1351da177e4SLinus Torvalds 
1361da177e4SLinus Torvalds 	spin_lock_irqsave(&cwq->lock, flags);
137b89deed3SOleg Nesterov 	insert_work(cwq, work, 1);
1381da177e4SLinus Torvalds 	spin_unlock_irqrestore(&cwq->lock, flags);
1391da177e4SLinus Torvalds }
1401da177e4SLinus Torvalds 
1410fcb78c2SRolf Eike Beer /**
1420fcb78c2SRolf Eike Beer  * queue_work - queue work on a workqueue
1430fcb78c2SRolf Eike Beer  * @wq: workqueue to use
1440fcb78c2SRolf Eike Beer  * @work: work to queue
1450fcb78c2SRolf Eike Beer  *
146057647fcSAlan Stern  * Returns 0 if @work was already on a queue, non-zero otherwise.
1471da177e4SLinus Torvalds  *
1481da177e4SLinus Torvalds  * We queue the work to the CPU it was submitted, but there is no
1491da177e4SLinus Torvalds  * guarantee that it will be processed by that CPU.
1501da177e4SLinus Torvalds  */
1511da177e4SLinus Torvalds int fastcall queue_work(struct workqueue_struct *wq, struct work_struct *work)
1521da177e4SLinus Torvalds {
153a848e3b6SOleg Nesterov 	int ret = 0;
1541da177e4SLinus Torvalds 
155a08727baSLinus Torvalds 	if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
1561da177e4SLinus Torvalds 		BUG_ON(!list_empty(&work->entry));
157a848e3b6SOleg Nesterov 		__queue_work(wq_per_cpu(wq, get_cpu()), work);
158a848e3b6SOleg Nesterov 		put_cpu();
1591da177e4SLinus Torvalds 		ret = 1;
1601da177e4SLinus Torvalds 	}
1611da177e4SLinus Torvalds 	return ret;
1621da177e4SLinus Torvalds }
163ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_work);
1641da177e4SLinus Torvalds 
16582f67cd9SIngo Molnar void delayed_work_timer_fn(unsigned long __data)
1661da177e4SLinus Torvalds {
16752bad64dSDavid Howells 	struct delayed_work *dwork = (struct delayed_work *)__data;
168ed7c0feeSOleg Nesterov 	struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
169ed7c0feeSOleg Nesterov 	struct workqueue_struct *wq = cwq->wq;
1701da177e4SLinus Torvalds 
171a848e3b6SOleg Nesterov 	__queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work);
1721da177e4SLinus Torvalds }
1731da177e4SLinus Torvalds 
1740fcb78c2SRolf Eike Beer /**
1750fcb78c2SRolf Eike Beer  * queue_delayed_work - queue work on a workqueue after delay
1760fcb78c2SRolf Eike Beer  * @wq: workqueue to use
177af9997e4SRandy Dunlap  * @dwork: delayable work to queue
1780fcb78c2SRolf Eike Beer  * @delay: number of jiffies to wait before queueing
1790fcb78c2SRolf Eike Beer  *
180057647fcSAlan Stern  * Returns 0 if @work was already on a queue, non-zero otherwise.
1810fcb78c2SRolf Eike Beer  */
1821da177e4SLinus Torvalds int fastcall queue_delayed_work(struct workqueue_struct *wq,
18352bad64dSDavid Howells 			struct delayed_work *dwork, unsigned long delay)
1841da177e4SLinus Torvalds {
18563bc0362SOleg Nesterov 	timer_stats_timer_set_start_info(&dwork->timer);
18652bad64dSDavid Howells 	if (delay == 0)
18763bc0362SOleg Nesterov 		return queue_work(wq, &dwork->work);
1881da177e4SLinus Torvalds 
18963bc0362SOleg Nesterov 	return queue_delayed_work_on(-1, wq, dwork, delay);
1901da177e4SLinus Torvalds }
191ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work);
1921da177e4SLinus Torvalds 
1930fcb78c2SRolf Eike Beer /**
1940fcb78c2SRolf Eike Beer  * queue_delayed_work_on - queue work on specific CPU after delay
1950fcb78c2SRolf Eike Beer  * @cpu: CPU number to execute work on
1960fcb78c2SRolf Eike Beer  * @wq: workqueue to use
197af9997e4SRandy Dunlap  * @dwork: work to queue
1980fcb78c2SRolf Eike Beer  * @delay: number of jiffies to wait before queueing
1990fcb78c2SRolf Eike Beer  *
200057647fcSAlan Stern  * Returns 0 if @work was already on a queue, non-zero otherwise.
2010fcb78c2SRolf Eike Beer  */
2027a6bc1cdSVenkatesh Pallipadi int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
20352bad64dSDavid Howells 			struct delayed_work *dwork, unsigned long delay)
2047a6bc1cdSVenkatesh Pallipadi {
2057a6bc1cdSVenkatesh Pallipadi 	int ret = 0;
20652bad64dSDavid Howells 	struct timer_list *timer = &dwork->timer;
20752bad64dSDavid Howells 	struct work_struct *work = &dwork->work;
2087a6bc1cdSVenkatesh Pallipadi 
209a08727baSLinus Torvalds 	if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) {
2107a6bc1cdSVenkatesh Pallipadi 		BUG_ON(timer_pending(timer));
2117a6bc1cdSVenkatesh Pallipadi 		BUG_ON(!list_empty(&work->entry));
2127a6bc1cdSVenkatesh Pallipadi 
213ed7c0feeSOleg Nesterov 		/* This stores cwq for the moment, for the timer_fn */
214a848e3b6SOleg Nesterov 		set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id()));
2157a6bc1cdSVenkatesh Pallipadi 		timer->expires = jiffies + delay;
21652bad64dSDavid Howells 		timer->data = (unsigned long)dwork;
2177a6bc1cdSVenkatesh Pallipadi 		timer->function = delayed_work_timer_fn;
21863bc0362SOleg Nesterov 
21963bc0362SOleg Nesterov 		if (unlikely(cpu >= 0))
2207a6bc1cdSVenkatesh Pallipadi 			add_timer_on(timer, cpu);
22163bc0362SOleg Nesterov 		else
22263bc0362SOleg Nesterov 			add_timer(timer);
2237a6bc1cdSVenkatesh Pallipadi 		ret = 1;
2247a6bc1cdSVenkatesh Pallipadi 	}
2257a6bc1cdSVenkatesh Pallipadi 	return ret;
2267a6bc1cdSVenkatesh Pallipadi }
227ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on);
2281da177e4SLinus Torvalds 
229858119e1SArjan van de Ven static void run_workqueue(struct cpu_workqueue_struct *cwq)
2301da177e4SLinus Torvalds {
231f293ea92SOleg Nesterov 	spin_lock_irq(&cwq->lock);
2321da177e4SLinus Torvalds 	cwq->run_depth++;
2331da177e4SLinus Torvalds 	if (cwq->run_depth > 3) {
2341da177e4SLinus Torvalds 		/* morton gets to eat his hat */
2351da177e4SLinus Torvalds 		printk("%s: recursion depth exceeded: %d\n",
2361da177e4SLinus Torvalds 			__FUNCTION__, cwq->run_depth);
2371da177e4SLinus Torvalds 		dump_stack();
2381da177e4SLinus Torvalds 	}
2391da177e4SLinus Torvalds 	while (!list_empty(&cwq->worklist)) {
2401da177e4SLinus Torvalds 		struct work_struct *work = list_entry(cwq->worklist.next,
2411da177e4SLinus Torvalds 						struct work_struct, entry);
2426bb49e59SDavid Howells 		work_func_t f = work->func;
2431da177e4SLinus Torvalds 
244b89deed3SOleg Nesterov 		cwq->current_work = work;
2451da177e4SLinus Torvalds 		list_del_init(cwq->worklist.next);
246f293ea92SOleg Nesterov 		spin_unlock_irq(&cwq->lock);
2471da177e4SLinus Torvalds 
248365970a1SDavid Howells 		BUG_ON(get_wq_data(work) != cwq);
249*23b2e599SOleg Nesterov 		work_clear_pending(work);
25065f27f38SDavid Howells 		f(work);
2511da177e4SLinus Torvalds 
252d5abe669SPeter Zijlstra 		if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
253d5abe669SPeter Zijlstra 			printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
254d5abe669SPeter Zijlstra 					"%s/0x%08x/%d\n",
255d5abe669SPeter Zijlstra 					current->comm, preempt_count(),
256d5abe669SPeter Zijlstra 				       	current->pid);
257d5abe669SPeter Zijlstra 			printk(KERN_ERR "    last function: ");
258d5abe669SPeter Zijlstra 			print_symbol("%s\n", (unsigned long)f);
259d5abe669SPeter Zijlstra 			debug_show_held_locks(current);
260d5abe669SPeter Zijlstra 			dump_stack();
261d5abe669SPeter Zijlstra 		}
262d5abe669SPeter Zijlstra 
263f293ea92SOleg Nesterov 		spin_lock_irq(&cwq->lock);
264b89deed3SOleg Nesterov 		cwq->current_work = NULL;
2651da177e4SLinus Torvalds 	}
2661da177e4SLinus Torvalds 	cwq->run_depth--;
267f293ea92SOleg Nesterov 	spin_unlock_irq(&cwq->lock);
2681da177e4SLinus Torvalds }
2691da177e4SLinus Torvalds 
2703af24433SOleg Nesterov /*
2713af24433SOleg Nesterov  * NOTE: the caller must not touch *cwq if this func returns true
2723af24433SOleg Nesterov  */
2733af24433SOleg Nesterov static int cwq_should_stop(struct cpu_workqueue_struct *cwq)
2743af24433SOleg Nesterov {
2753af24433SOleg Nesterov 	int should_stop = cwq->should_stop;
2763af24433SOleg Nesterov 
2773af24433SOleg Nesterov 	if (unlikely(should_stop)) {
2783af24433SOleg Nesterov 		spin_lock_irq(&cwq->lock);
2793af24433SOleg Nesterov 		should_stop = cwq->should_stop && list_empty(&cwq->worklist);
2803af24433SOleg Nesterov 		if (should_stop)
2813af24433SOleg Nesterov 			cwq->thread = NULL;
2823af24433SOleg Nesterov 		spin_unlock_irq(&cwq->lock);
2833af24433SOleg Nesterov 	}
2843af24433SOleg Nesterov 
2853af24433SOleg Nesterov 	return should_stop;
2863af24433SOleg Nesterov }
2873af24433SOleg Nesterov 
2881da177e4SLinus Torvalds static int worker_thread(void *__cwq)
2891da177e4SLinus Torvalds {
2901da177e4SLinus Torvalds 	struct cpu_workqueue_struct *cwq = __cwq;
2913af24433SOleg Nesterov 	DEFINE_WAIT(wait);
2921da177e4SLinus Torvalds 	struct k_sigaction sa;
2931da177e4SLinus Torvalds 	sigset_t blocked;
2941da177e4SLinus Torvalds 
295319c2a98SOleg Nesterov 	if (!cwq->wq->freezeable)
2961da177e4SLinus Torvalds 		current->flags |= PF_NOFREEZE;
2971da177e4SLinus Torvalds 
2981da177e4SLinus Torvalds 	set_user_nice(current, -5);
2991da177e4SLinus Torvalds 
3001da177e4SLinus Torvalds 	/* Block and flush all signals */
3011da177e4SLinus Torvalds 	sigfillset(&blocked);
3021da177e4SLinus Torvalds 	sigprocmask(SIG_BLOCK, &blocked, NULL);
3031da177e4SLinus Torvalds 	flush_signals(current);
3041da177e4SLinus Torvalds 
30546934023SChristoph Lameter 	/*
30646934023SChristoph Lameter 	 * We inherited MPOL_INTERLEAVE from the booting kernel.
30746934023SChristoph Lameter 	 * Set MPOL_DEFAULT to insure node local allocations.
30846934023SChristoph Lameter 	 */
30946934023SChristoph Lameter 	numa_default_policy();
31046934023SChristoph Lameter 
3111da177e4SLinus Torvalds 	/* SIG_IGN makes children autoreap: see do_notify_parent(). */
3121da177e4SLinus Torvalds 	sa.sa.sa_handler = SIG_IGN;
3131da177e4SLinus Torvalds 	sa.sa.sa_flags = 0;
3141da177e4SLinus Torvalds 	siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
3151da177e4SLinus Torvalds 	do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
3161da177e4SLinus Torvalds 
3173af24433SOleg Nesterov 	for (;;) {
318319c2a98SOleg Nesterov 		if (cwq->wq->freezeable)
319341a5958SRafael J. Wysocki 			try_to_freeze();
320341a5958SRafael J. Wysocki 
3213af24433SOleg Nesterov 		prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
3223af24433SOleg Nesterov 		if (!cwq->should_stop && list_empty(&cwq->worklist))
3231da177e4SLinus Torvalds 			schedule();
3243af24433SOleg Nesterov 		finish_wait(&cwq->more_work, &wait);
3251da177e4SLinus Torvalds 
3263af24433SOleg Nesterov 		if (cwq_should_stop(cwq))
3273af24433SOleg Nesterov 			break;
3283af24433SOleg Nesterov 
3291da177e4SLinus Torvalds 		run_workqueue(cwq);
3301da177e4SLinus Torvalds 	}
3313af24433SOleg Nesterov 
3321da177e4SLinus Torvalds 	return 0;
3331da177e4SLinus Torvalds }
3341da177e4SLinus Torvalds 
335fc2e4d70SOleg Nesterov struct wq_barrier {
336fc2e4d70SOleg Nesterov 	struct work_struct	work;
337fc2e4d70SOleg Nesterov 	struct completion	done;
338fc2e4d70SOleg Nesterov };
339fc2e4d70SOleg Nesterov 
340fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work)
341fc2e4d70SOleg Nesterov {
342fc2e4d70SOleg Nesterov 	struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
343fc2e4d70SOleg Nesterov 	complete(&barr->done);
344fc2e4d70SOleg Nesterov }
345fc2e4d70SOleg Nesterov 
34683c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
34783c22520SOleg Nesterov 					struct wq_barrier *barr, int tail)
348fc2e4d70SOleg Nesterov {
349fc2e4d70SOleg Nesterov 	INIT_WORK(&barr->work, wq_barrier_func);
350fc2e4d70SOleg Nesterov 	__set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
351fc2e4d70SOleg Nesterov 
352fc2e4d70SOleg Nesterov 	init_completion(&barr->done);
35383c22520SOleg Nesterov 
35483c22520SOleg Nesterov 	insert_work(cwq, &barr->work, tail);
355fc2e4d70SOleg Nesterov }
356fc2e4d70SOleg Nesterov 
3571da177e4SLinus Torvalds static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
3581da177e4SLinus Torvalds {
3591da177e4SLinus Torvalds 	if (cwq->thread == current) {
3601da177e4SLinus Torvalds 		/*
3611da177e4SLinus Torvalds 		 * Probably keventd trying to flush its own queue. So simply run
3621da177e4SLinus Torvalds 		 * it by hand rather than deadlocking.
3631da177e4SLinus Torvalds 		 */
3641da177e4SLinus Torvalds 		run_workqueue(cwq);
3651da177e4SLinus Torvalds 	} else {
366fc2e4d70SOleg Nesterov 		struct wq_barrier barr;
36783c22520SOleg Nesterov 		int active = 0;
3681da177e4SLinus Torvalds 
36983c22520SOleg Nesterov 		spin_lock_irq(&cwq->lock);
37083c22520SOleg Nesterov 		if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) {
37183c22520SOleg Nesterov 			insert_wq_barrier(cwq, &barr, 1);
37283c22520SOleg Nesterov 			active = 1;
37383c22520SOleg Nesterov 		}
37483c22520SOleg Nesterov 		spin_unlock_irq(&cwq->lock);
3751da177e4SLinus Torvalds 
376d721304dSOleg Nesterov 		if (active)
377fc2e4d70SOleg Nesterov 			wait_for_completion(&barr.done);
3781da177e4SLinus Torvalds 	}
37983c22520SOleg Nesterov }
3801da177e4SLinus Torvalds 
3810fcb78c2SRolf Eike Beer /**
3821da177e4SLinus Torvalds  * flush_workqueue - ensure that any scheduled work has run to completion.
3830fcb78c2SRolf Eike Beer  * @wq: workqueue to flush
3841da177e4SLinus Torvalds  *
3851da177e4SLinus Torvalds  * Forces execution of the workqueue and blocks until its completion.
3861da177e4SLinus Torvalds  * This is typically used in driver shutdown handlers.
3871da177e4SLinus Torvalds  *
388fc2e4d70SOleg Nesterov  * We sleep until all works which were queued on entry have been handled,
389fc2e4d70SOleg Nesterov  * but we are not livelocked by new incoming ones.
3901da177e4SLinus Torvalds  *
3911da177e4SLinus Torvalds  * This function used to run the workqueues itself.  Now we just wait for the
3921da177e4SLinus Torvalds  * helper threads to do it.
3931da177e4SLinus Torvalds  */
3941da177e4SLinus Torvalds void fastcall flush_workqueue(struct workqueue_struct *wq)
3951da177e4SLinus Torvalds {
396b1f4ec17SOleg Nesterov 	const cpumask_t *cpu_map = wq_cpu_map(wq);
397cce1a165SOleg Nesterov 	int cpu;
398b1f4ec17SOleg Nesterov 
399f293ea92SOleg Nesterov 	might_sleep();
400b1f4ec17SOleg Nesterov 	for_each_cpu_mask(cpu, *cpu_map)
40189ada679SChristoph Lameter 		flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
4021da177e4SLinus Torvalds }
403ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue);
4041da177e4SLinus Torvalds 
405b89deed3SOleg Nesterov static void wait_on_work(struct cpu_workqueue_struct *cwq,
406b89deed3SOleg Nesterov 				struct work_struct *work)
407b89deed3SOleg Nesterov {
408b89deed3SOleg Nesterov 	struct wq_barrier barr;
409b89deed3SOleg Nesterov 	int running = 0;
410b89deed3SOleg Nesterov 
411b89deed3SOleg Nesterov 	spin_lock_irq(&cwq->lock);
412b89deed3SOleg Nesterov 	if (unlikely(cwq->current_work == work)) {
41383c22520SOleg Nesterov 		insert_wq_barrier(cwq, &barr, 0);
414b89deed3SOleg Nesterov 		running = 1;
415b89deed3SOleg Nesterov 	}
416b89deed3SOleg Nesterov 	spin_unlock_irq(&cwq->lock);
417b89deed3SOleg Nesterov 
4183af24433SOleg Nesterov 	if (unlikely(running))
419b89deed3SOleg Nesterov 		wait_for_completion(&barr.done);
420b89deed3SOleg Nesterov }
421b89deed3SOleg Nesterov 
422b89deed3SOleg Nesterov /**
423b89deed3SOleg Nesterov  * flush_work - block until a work_struct's callback has terminated
424b89deed3SOleg Nesterov  * @wq: the workqueue on which the work is queued
425b89deed3SOleg Nesterov  * @work: the work which is to be flushed
426b89deed3SOleg Nesterov  *
427b89deed3SOleg Nesterov  * flush_work() will attempt to cancel the work if it is queued.  If the work's
428b89deed3SOleg Nesterov  * callback appears to be running, flush_work() will block until it has
429b89deed3SOleg Nesterov  * completed.
430b89deed3SOleg Nesterov  *
431b89deed3SOleg Nesterov  * flush_work() is designed to be used when the caller is tearing down data
432b89deed3SOleg Nesterov  * structures which the callback function operates upon.  It is expected that,
433b89deed3SOleg Nesterov  * prior to calling flush_work(), the caller has arranged for the work to not
434b89deed3SOleg Nesterov  * be requeued.
435b89deed3SOleg Nesterov  */
436b89deed3SOleg Nesterov void flush_work(struct workqueue_struct *wq, struct work_struct *work)
437b89deed3SOleg Nesterov {
438b1f4ec17SOleg Nesterov 	const cpumask_t *cpu_map = wq_cpu_map(wq);
439b89deed3SOleg Nesterov 	struct cpu_workqueue_struct *cwq;
440b1f4ec17SOleg Nesterov 	int cpu;
441b89deed3SOleg Nesterov 
442f293ea92SOleg Nesterov 	might_sleep();
443f293ea92SOleg Nesterov 
444b89deed3SOleg Nesterov 	cwq = get_wq_data(work);
445b89deed3SOleg Nesterov 	/* Was it ever queued ? */
446b89deed3SOleg Nesterov 	if (!cwq)
4473af24433SOleg Nesterov 		return;
448b89deed3SOleg Nesterov 
449b89deed3SOleg Nesterov 	/*
4503af24433SOleg Nesterov 	 * This work can't be re-queued, no need to re-check that
4513af24433SOleg Nesterov 	 * get_wq_data() is still the same when we take cwq->lock.
452b89deed3SOleg Nesterov 	 */
453b89deed3SOleg Nesterov 	spin_lock_irq(&cwq->lock);
454b89deed3SOleg Nesterov 	list_del_init(&work->entry);
455*23b2e599SOleg Nesterov 	work_clear_pending(work);
456b89deed3SOleg Nesterov 	spin_unlock_irq(&cwq->lock);
457b89deed3SOleg Nesterov 
458b1f4ec17SOleg Nesterov 	for_each_cpu_mask(cpu, *cpu_map)
459b89deed3SOleg Nesterov 		wait_on_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
460b89deed3SOleg Nesterov }
461b89deed3SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work);
462b89deed3SOleg Nesterov 
4631da177e4SLinus Torvalds 
4641da177e4SLinus Torvalds static struct workqueue_struct *keventd_wq;
4651da177e4SLinus Torvalds 
4660fcb78c2SRolf Eike Beer /**
4670fcb78c2SRolf Eike Beer  * schedule_work - put work task in global workqueue
4680fcb78c2SRolf Eike Beer  * @work: job to be done
4690fcb78c2SRolf Eike Beer  *
4700fcb78c2SRolf Eike Beer  * This puts a job in the kernel-global workqueue.
4710fcb78c2SRolf Eike Beer  */
4721da177e4SLinus Torvalds int fastcall schedule_work(struct work_struct *work)
4731da177e4SLinus Torvalds {
4741da177e4SLinus Torvalds 	return queue_work(keventd_wq, work);
4751da177e4SLinus Torvalds }
476ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_work);
4771da177e4SLinus Torvalds 
4780fcb78c2SRolf Eike Beer /**
4790fcb78c2SRolf Eike Beer  * schedule_delayed_work - put work task in global workqueue after delay
48052bad64dSDavid Howells  * @dwork: job to be done
48152bad64dSDavid Howells  * @delay: number of jiffies to wait or 0 for immediate execution
4820fcb78c2SRolf Eike Beer  *
4830fcb78c2SRolf Eike Beer  * After waiting for a given time this puts a job in the kernel-global
4840fcb78c2SRolf Eike Beer  * workqueue.
4850fcb78c2SRolf Eike Beer  */
48682f67cd9SIngo Molnar int fastcall schedule_delayed_work(struct delayed_work *dwork,
48782f67cd9SIngo Molnar 					unsigned long delay)
4881da177e4SLinus Torvalds {
48982f67cd9SIngo Molnar 	timer_stats_timer_set_start_info(&dwork->timer);
49052bad64dSDavid Howells 	return queue_delayed_work(keventd_wq, dwork, delay);
4911da177e4SLinus Torvalds }
492ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work);
4931da177e4SLinus Torvalds 
4940fcb78c2SRolf Eike Beer /**
4950fcb78c2SRolf Eike Beer  * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
4960fcb78c2SRolf Eike Beer  * @cpu: cpu to use
49752bad64dSDavid Howells  * @dwork: job to be done
4980fcb78c2SRolf Eike Beer  * @delay: number of jiffies to wait
4990fcb78c2SRolf Eike Beer  *
5000fcb78c2SRolf Eike Beer  * After waiting for a given time this puts a job in the kernel-global
5010fcb78c2SRolf Eike Beer  * workqueue on the specified CPU.
5020fcb78c2SRolf Eike Beer  */
5031da177e4SLinus Torvalds int schedule_delayed_work_on(int cpu,
50452bad64dSDavid Howells 			struct delayed_work *dwork, unsigned long delay)
5051da177e4SLinus Torvalds {
50652bad64dSDavid Howells 	return queue_delayed_work_on(cpu, keventd_wq, dwork, delay);
5071da177e4SLinus Torvalds }
508ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on);
5091da177e4SLinus Torvalds 
510b6136773SAndrew Morton /**
511b6136773SAndrew Morton  * schedule_on_each_cpu - call a function on each online CPU from keventd
512b6136773SAndrew Morton  * @func: the function to call
513b6136773SAndrew Morton  *
514b6136773SAndrew Morton  * Returns zero on success.
515b6136773SAndrew Morton  * Returns -ve errno on failure.
516b6136773SAndrew Morton  *
517b6136773SAndrew Morton  * Appears to be racy against CPU hotplug.
518b6136773SAndrew Morton  *
519b6136773SAndrew Morton  * schedule_on_each_cpu() is very slow.
520b6136773SAndrew Morton  */
52165f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func)
52215316ba8SChristoph Lameter {
52315316ba8SChristoph Lameter 	int cpu;
524b6136773SAndrew Morton 	struct work_struct *works;
52515316ba8SChristoph Lameter 
526b6136773SAndrew Morton 	works = alloc_percpu(struct work_struct);
527b6136773SAndrew Morton 	if (!works)
52815316ba8SChristoph Lameter 		return -ENOMEM;
529b6136773SAndrew Morton 
530e18f3ffbSAndrew Morton 	preempt_disable();		/* CPU hotplug */
53115316ba8SChristoph Lameter 	for_each_online_cpu(cpu) {
5329bfb1839SIngo Molnar 		struct work_struct *work = per_cpu_ptr(works, cpu);
5339bfb1839SIngo Molnar 
5349bfb1839SIngo Molnar 		INIT_WORK(work, func);
5359bfb1839SIngo Molnar 		set_bit(WORK_STRUCT_PENDING, work_data_bits(work));
5369bfb1839SIngo Molnar 		__queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), work);
53715316ba8SChristoph Lameter 	}
538e18f3ffbSAndrew Morton 	preempt_enable();
53915316ba8SChristoph Lameter 	flush_workqueue(keventd_wq);
540b6136773SAndrew Morton 	free_percpu(works);
54115316ba8SChristoph Lameter 	return 0;
54215316ba8SChristoph Lameter }
54315316ba8SChristoph Lameter 
5441da177e4SLinus Torvalds void flush_scheduled_work(void)
5451da177e4SLinus Torvalds {
5461da177e4SLinus Torvalds 	flush_workqueue(keventd_wq);
5471da177e4SLinus Torvalds }
548ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work);
5491da177e4SLinus Torvalds 
550b89deed3SOleg Nesterov void flush_work_keventd(struct work_struct *work)
551b89deed3SOleg Nesterov {
552b89deed3SOleg Nesterov 	flush_work(keventd_wq, work);
553b89deed3SOleg Nesterov }
554b89deed3SOleg Nesterov EXPORT_SYMBOL(flush_work_keventd);
555b89deed3SOleg Nesterov 
5561da177e4SLinus Torvalds /**
5571634c48fSOleg Nesterov  * cancel_rearming_delayed_work - kill off a delayed work whose handler rearms the delayed work.
55852bad64dSDavid Howells  * @dwork: the delayed work struct
559ed7c0feeSOleg Nesterov  *
560ed7c0feeSOleg Nesterov  * Note that the work callback function may still be running on return from
561ed7c0feeSOleg Nesterov  * cancel_delayed_work(). Run flush_workqueue() or flush_work() to wait on it.
5621da177e4SLinus Torvalds  */
5631634c48fSOleg Nesterov void cancel_rearming_delayed_work(struct delayed_work *dwork)
5641da177e4SLinus Torvalds {
5651634c48fSOleg Nesterov 	struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work);
5661634c48fSOleg Nesterov 
567dfb4b82eSOleg Nesterov 	/* Was it ever queued ? */
5681634c48fSOleg Nesterov 	if (cwq != NULL) {
5691634c48fSOleg Nesterov 		struct workqueue_struct *wq = cwq->wq;
570dfb4b82eSOleg Nesterov 
57152bad64dSDavid Howells 		while (!cancel_delayed_work(dwork))
5721da177e4SLinus Torvalds 			flush_workqueue(wq);
5731da177e4SLinus Torvalds 	}
5741da177e4SLinus Torvalds }
5751da177e4SLinus Torvalds EXPORT_SYMBOL(cancel_rearming_delayed_work);
5761da177e4SLinus Torvalds 
5771fa44ecaSJames Bottomley /**
5781fa44ecaSJames Bottomley  * execute_in_process_context - reliably execute the routine with user context
5791fa44ecaSJames Bottomley  * @fn:		the function to execute
5801fa44ecaSJames Bottomley  * @ew:		guaranteed storage for the execute work structure (must
5811fa44ecaSJames Bottomley  *		be available when the work executes)
5821fa44ecaSJames Bottomley  *
5831fa44ecaSJames Bottomley  * Executes the function immediately if process context is available,
5841fa44ecaSJames Bottomley  * otherwise schedules the function for delayed execution.
5851fa44ecaSJames Bottomley  *
5861fa44ecaSJames Bottomley  * Returns:	0 - function was executed
5871fa44ecaSJames Bottomley  *		1 - function was scheduled for execution
5881fa44ecaSJames Bottomley  */
58965f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew)
5901fa44ecaSJames Bottomley {
5911fa44ecaSJames Bottomley 	if (!in_interrupt()) {
59265f27f38SDavid Howells 		fn(&ew->work);
5931fa44ecaSJames Bottomley 		return 0;
5941fa44ecaSJames Bottomley 	}
5951fa44ecaSJames Bottomley 
59665f27f38SDavid Howells 	INIT_WORK(&ew->work, fn);
5971fa44ecaSJames Bottomley 	schedule_work(&ew->work);
5981fa44ecaSJames Bottomley 
5991fa44ecaSJames Bottomley 	return 1;
6001fa44ecaSJames Bottomley }
6011fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context);
6021fa44ecaSJames Bottomley 
6031da177e4SLinus Torvalds int keventd_up(void)
6041da177e4SLinus Torvalds {
6051da177e4SLinus Torvalds 	return keventd_wq != NULL;
6061da177e4SLinus Torvalds }
6071da177e4SLinus Torvalds 
6081da177e4SLinus Torvalds int current_is_keventd(void)
6091da177e4SLinus Torvalds {
6101da177e4SLinus Torvalds 	struct cpu_workqueue_struct *cwq;
6111da177e4SLinus Torvalds 	int cpu = smp_processor_id();	/* preempt-safe: keventd is per-cpu */
6121da177e4SLinus Torvalds 	int ret = 0;
6131da177e4SLinus Torvalds 
6141da177e4SLinus Torvalds 	BUG_ON(!keventd_wq);
6151da177e4SLinus Torvalds 
61689ada679SChristoph Lameter 	cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu);
6171da177e4SLinus Torvalds 	if (current == cwq->thread)
6181da177e4SLinus Torvalds 		ret = 1;
6191da177e4SLinus Torvalds 
6201da177e4SLinus Torvalds 	return ret;
6211da177e4SLinus Torvalds 
6221da177e4SLinus Torvalds }
6231da177e4SLinus Torvalds 
6243af24433SOleg Nesterov static struct cpu_workqueue_struct *
6253af24433SOleg Nesterov init_cpu_workqueue(struct workqueue_struct *wq, int cpu)
6261da177e4SLinus Torvalds {
62789ada679SChristoph Lameter 	struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu);
6283af24433SOleg Nesterov 
6293af24433SOleg Nesterov 	cwq->wq = wq;
6303af24433SOleg Nesterov 	spin_lock_init(&cwq->lock);
6313af24433SOleg Nesterov 	INIT_LIST_HEAD(&cwq->worklist);
6323af24433SOleg Nesterov 	init_waitqueue_head(&cwq->more_work);
6333af24433SOleg Nesterov 
6343af24433SOleg Nesterov 	return cwq;
6353af24433SOleg Nesterov }
6363af24433SOleg Nesterov 
6373af24433SOleg Nesterov static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
6383af24433SOleg Nesterov {
6393af24433SOleg Nesterov 	struct workqueue_struct *wq = cwq->wq;
6403af24433SOleg Nesterov 	const char *fmt = is_single_threaded(wq) ? "%s" : "%s/%d";
6413af24433SOleg Nesterov 	struct task_struct *p;
6423af24433SOleg Nesterov 
6433af24433SOleg Nesterov 	p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu);
6443af24433SOleg Nesterov 	/*
6453af24433SOleg Nesterov 	 * Nobody can add the work_struct to this cwq,
6463af24433SOleg Nesterov 	 *	if (caller is __create_workqueue)
6473af24433SOleg Nesterov 	 *		nobody should see this wq
6483af24433SOleg Nesterov 	 *	else // caller is CPU_UP_PREPARE
6493af24433SOleg Nesterov 	 *		cpu is not on cpu_online_map
6503af24433SOleg Nesterov 	 * so we can abort safely.
6513af24433SOleg Nesterov 	 */
6523af24433SOleg Nesterov 	if (IS_ERR(p))
6533af24433SOleg Nesterov 		return PTR_ERR(p);
6543af24433SOleg Nesterov 
6553af24433SOleg Nesterov 	cwq->thread = p;
6563af24433SOleg Nesterov 	cwq->should_stop = 0;
6573af24433SOleg Nesterov 
6583af24433SOleg Nesterov 	return 0;
6593af24433SOleg Nesterov }
6603af24433SOleg Nesterov 
66106ba38a9SOleg Nesterov static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
66206ba38a9SOleg Nesterov {
66306ba38a9SOleg Nesterov 	struct task_struct *p = cwq->thread;
66406ba38a9SOleg Nesterov 
66506ba38a9SOleg Nesterov 	if (p != NULL) {
66606ba38a9SOleg Nesterov 		if (cpu >= 0)
66706ba38a9SOleg Nesterov 			kthread_bind(p, cpu);
66806ba38a9SOleg Nesterov 		wake_up_process(p);
66906ba38a9SOleg Nesterov 	}
67006ba38a9SOleg Nesterov }
67106ba38a9SOleg Nesterov 
6723af24433SOleg Nesterov struct workqueue_struct *__create_workqueue(const char *name,
6733af24433SOleg Nesterov 					    int singlethread, int freezeable)
6743af24433SOleg Nesterov {
6753af24433SOleg Nesterov 	struct workqueue_struct *wq;
6763af24433SOleg Nesterov 	struct cpu_workqueue_struct *cwq;
6773af24433SOleg Nesterov 	int err = 0, cpu;
6783af24433SOleg Nesterov 
6793af24433SOleg Nesterov 	wq = kzalloc(sizeof(*wq), GFP_KERNEL);
6803af24433SOleg Nesterov 	if (!wq)
6813af24433SOleg Nesterov 		return NULL;
6823af24433SOleg Nesterov 
6833af24433SOleg Nesterov 	wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct);
6843af24433SOleg Nesterov 	if (!wq->cpu_wq) {
6853af24433SOleg Nesterov 		kfree(wq);
6863af24433SOleg Nesterov 		return NULL;
6873af24433SOleg Nesterov 	}
6883af24433SOleg Nesterov 
6893af24433SOleg Nesterov 	wq->name = name;
690cce1a165SOleg Nesterov 	wq->singlethread = singlethread;
6913af24433SOleg Nesterov 	wq->freezeable = freezeable;
692cce1a165SOleg Nesterov 	INIT_LIST_HEAD(&wq->list);
6933af24433SOleg Nesterov 
6943af24433SOleg Nesterov 	if (singlethread) {
6953af24433SOleg Nesterov 		cwq = init_cpu_workqueue(wq, singlethread_cpu);
6963af24433SOleg Nesterov 		err = create_workqueue_thread(cwq, singlethread_cpu);
69706ba38a9SOleg Nesterov 		start_workqueue_thread(cwq, -1);
6983af24433SOleg Nesterov 	} else {
6993af24433SOleg Nesterov 		mutex_lock(&workqueue_mutex);
7003af24433SOleg Nesterov 		list_add(&wq->list, &workqueues);
7013af24433SOleg Nesterov 
7023af24433SOleg Nesterov 		for_each_possible_cpu(cpu) {
7033af24433SOleg Nesterov 			cwq = init_cpu_workqueue(wq, cpu);
7043af24433SOleg Nesterov 			if (err || !cpu_online(cpu))
7053af24433SOleg Nesterov 				continue;
7063af24433SOleg Nesterov 			err = create_workqueue_thread(cwq, cpu);
70706ba38a9SOleg Nesterov 			start_workqueue_thread(cwq, cpu);
7083af24433SOleg Nesterov 		}
7093af24433SOleg Nesterov 		mutex_unlock(&workqueue_mutex);
7103af24433SOleg Nesterov 	}
7113af24433SOleg Nesterov 
7123af24433SOleg Nesterov 	if (err) {
7133af24433SOleg Nesterov 		destroy_workqueue(wq);
7143af24433SOleg Nesterov 		wq = NULL;
7153af24433SOleg Nesterov 	}
7163af24433SOleg Nesterov 	return wq;
7173af24433SOleg Nesterov }
7183af24433SOleg Nesterov EXPORT_SYMBOL_GPL(__create_workqueue);
7193af24433SOleg Nesterov 
7203af24433SOleg Nesterov static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu)
7213af24433SOleg Nesterov {
7223af24433SOleg Nesterov 	struct wq_barrier barr;
7233af24433SOleg Nesterov 	int alive = 0;
7241da177e4SLinus Torvalds 
7251da177e4SLinus Torvalds 	spin_lock_irq(&cwq->lock);
7263af24433SOleg Nesterov 	if (cwq->thread != NULL) {
7273af24433SOleg Nesterov 		insert_wq_barrier(cwq, &barr, 1);
7283af24433SOleg Nesterov 		cwq->should_stop = 1;
7293af24433SOleg Nesterov 		alive = 1;
7301da177e4SLinus Torvalds 	}
7311da177e4SLinus Torvalds 	spin_unlock_irq(&cwq->lock);
7323af24433SOleg Nesterov 
7333af24433SOleg Nesterov 	if (alive) {
7343af24433SOleg Nesterov 		wait_for_completion(&barr.done);
7353af24433SOleg Nesterov 
7363af24433SOleg Nesterov 		while (unlikely(cwq->thread != NULL))
7373af24433SOleg Nesterov 			cpu_relax();
7383af24433SOleg Nesterov 		/*
7393af24433SOleg Nesterov 		 * Wait until cwq->thread unlocks cwq->lock,
7403af24433SOleg Nesterov 		 * it won't touch *cwq after that.
7413af24433SOleg Nesterov 		 */
7423af24433SOleg Nesterov 		smp_rmb();
7433af24433SOleg Nesterov 		spin_unlock_wait(&cwq->lock);
7443af24433SOleg Nesterov 	}
7451da177e4SLinus Torvalds }
7461da177e4SLinus Torvalds 
7473af24433SOleg Nesterov /**
7483af24433SOleg Nesterov  * destroy_workqueue - safely terminate a workqueue
7493af24433SOleg Nesterov  * @wq: target workqueue
7503af24433SOleg Nesterov  *
7513af24433SOleg Nesterov  * Safely destroy a workqueue. All work currently pending will be done first.
7523af24433SOleg Nesterov  */
7533af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq)
7543af24433SOleg Nesterov {
755b1f4ec17SOleg Nesterov 	const cpumask_t *cpu_map = wq_cpu_map(wq);
7563af24433SOleg Nesterov 	struct cpu_workqueue_struct *cwq;
7573af24433SOleg Nesterov 	int cpu;
7583af24433SOleg Nesterov 
7593af24433SOleg Nesterov 	mutex_lock(&workqueue_mutex);
7603af24433SOleg Nesterov 	list_del(&wq->list);
7613af24433SOleg Nesterov 	mutex_unlock(&workqueue_mutex);
7623af24433SOleg Nesterov 
763b1f4ec17SOleg Nesterov 	for_each_cpu_mask(cpu, *cpu_map) {
7643af24433SOleg Nesterov 		cwq = per_cpu_ptr(wq->cpu_wq, cpu);
7653af24433SOleg Nesterov 		cleanup_workqueue_thread(cwq, cpu);
7663af24433SOleg Nesterov 	}
7673af24433SOleg Nesterov 
7683af24433SOleg Nesterov 	free_percpu(wq->cpu_wq);
7693af24433SOleg Nesterov 	kfree(wq);
7703af24433SOleg Nesterov }
7713af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue);
7723af24433SOleg Nesterov 
7739c7b216dSChandra Seetharaman static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
7741da177e4SLinus Torvalds 						unsigned long action,
7751da177e4SLinus Torvalds 						void *hcpu)
7761da177e4SLinus Torvalds {
7773af24433SOleg Nesterov 	unsigned int cpu = (unsigned long)hcpu;
7783af24433SOleg Nesterov 	struct cpu_workqueue_struct *cwq;
7791da177e4SLinus Torvalds 	struct workqueue_struct *wq;
7801da177e4SLinus Torvalds 
7811da177e4SLinus Torvalds 	switch (action) {
7823af24433SOleg Nesterov 	case CPU_LOCK_ACQUIRE:
7839b41ea72SAndrew Morton 		mutex_lock(&workqueue_mutex);
7843af24433SOleg Nesterov 		return NOTIFY_OK;
7853af24433SOleg Nesterov 
7863af24433SOleg Nesterov 	case CPU_LOCK_RELEASE:
7873af24433SOleg Nesterov 		mutex_unlock(&workqueue_mutex);
7883af24433SOleg Nesterov 		return NOTIFY_OK;
7893af24433SOleg Nesterov 
7903af24433SOleg Nesterov 	case CPU_UP_PREPARE:
7913af24433SOleg Nesterov 		cpu_set(cpu, cpu_populated_map);
7923af24433SOleg Nesterov 	}
7933af24433SOleg Nesterov 
7941da177e4SLinus Torvalds 	list_for_each_entry(wq, &workqueues, list) {
7953af24433SOleg Nesterov 		cwq = per_cpu_ptr(wq->cpu_wq, cpu);
7963af24433SOleg Nesterov 
7973af24433SOleg Nesterov 		switch (action) {
7983af24433SOleg Nesterov 		case CPU_UP_PREPARE:
7993af24433SOleg Nesterov 			if (!create_workqueue_thread(cwq, cpu))
8001da177e4SLinus Torvalds 				break;
8013af24433SOleg Nesterov 			printk(KERN_ERR "workqueue for %i failed\n", cpu);
8023af24433SOleg Nesterov 			return NOTIFY_BAD;
8031da177e4SLinus Torvalds 
8041da177e4SLinus Torvalds 		case CPU_ONLINE:
80506ba38a9SOleg Nesterov 			start_workqueue_thread(cwq, cpu);
8061da177e4SLinus Torvalds 			break;
8071da177e4SLinus Torvalds 
8081da177e4SLinus Torvalds 		case CPU_UP_CANCELED:
80906ba38a9SOleg Nesterov 			start_workqueue_thread(cwq, -1);
8101da177e4SLinus Torvalds 		case CPU_DEAD:
8113af24433SOleg Nesterov 			cleanup_workqueue_thread(cwq, cpu);
8121da177e4SLinus Torvalds 			break;
8131da177e4SLinus Torvalds 		}
8143af24433SOleg Nesterov 	}
8151da177e4SLinus Torvalds 
8161da177e4SLinus Torvalds 	return NOTIFY_OK;
8171da177e4SLinus Torvalds }
8181da177e4SLinus Torvalds 
819c12920d1SOleg Nesterov void __init init_workqueues(void)
8201da177e4SLinus Torvalds {
8213af24433SOleg Nesterov 	cpu_populated_map = cpu_online_map;
822f756d5e2SNathan Lynch 	singlethread_cpu = first_cpu(cpu_possible_map);
823b1f4ec17SOleg Nesterov 	cpu_singlethread_map = cpumask_of_cpu(singlethread_cpu);
8241da177e4SLinus Torvalds 	hotcpu_notifier(workqueue_cpu_callback, 0);
8251da177e4SLinus Torvalds 	keventd_wq = create_workqueue("events");
8261da177e4SLinus Torvalds 	BUG_ON(!keventd_wq);
8271da177e4SLinus Torvalds }
828