kernel26-2.6.12-alx-r9/kernel/workqueue.c

/*
 * linux/kernel/workqueue.c
 *
 * Generic mechanism for defining kernel helper threads for running
 * arbitrary tasks in process context.
 *
 * Started by Ingo Molnar, Copyright (C) 2002
 *
 * Derived from the taskqueue/keventd code by:
 *
 *   David Woodhouse <dwmw2@infradead.org>
 *   Andrew Morton <andrewm@uow.edu.au>
 *   Kai Petzke <wpp@marie.physik.tu-berlin.de>
 *   Theodore Ts'o <tytso@mit.edu>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/completion.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/kthread.h>

/*
 * The per-CPU workqueue (if single thread, we always use cpu 0's).
 *
 * The sequence counters are for flush_scheduled_work().  It wants to wait
 * until until all currently-scheduled works are completed, but it doesn't
 * want to be livelocked by new, incoming ones.  So it waits until
 * remove_sequence is >= the insert_sequence which pertained when
 * flush_scheduled_work() was called.
 */
struct cpu_workqueue_struct {

	spinlock_t lock;

	long remove_sequence;	/* Least-recently added (next to run) */
	long insert_sequence;	/* Next to add */

	struct list_head worklist;
	wait_queue_head_t more_work;
	wait_queue_head_t work_done;

	struct workqueue_struct *wq;
	task_t *thread;

	int run_depth;		/* Detect run_workqueue() recursion depth */
} ____cacheline_aligned;

/*
 * The externally visible workqueue abstraction is an array of
 * per-CPU workqueues:
 */
struct workqueue_struct {
	struct cpu_workqueue_struct cpu_wq[NR_CPUS];
	const char *name;
	struct list_head list; 	/* Empty if single thread */
};

/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
   threads to each one as cpus come/go. */
static DEFINE_SPINLOCK(workqueue_lock);
static LIST_HEAD(workqueues);

/* If it's single threaded, it isn't in the list of workqueues. */
static inline int is_single_threaded(struct workqueue_struct *wq)
{
	return list_empty(&wq->list);
}

/* Preempt must be disabled. */
static void __queue_work(struct cpu_workqueue_struct *cwq,
			 struct work_struct *work)
{
	unsigned long flags;

	spin_lock_irqsave(&cwq->lock, flags);
	work->wq_data = cwq;
	list_add_tail(&work->entry, &cwq->worklist);
	cwq->insert_sequence++;
	wake_up(&cwq->more_work);
	spin_unlock_irqrestore(&cwq->lock, flags);
}

/*
 * Queue work on a workqueue. Return non-zero if it was successfully
 * added.
 *
 * We queue the work to the CPU it was submitted, but there is no
 * guarantee that it will be processed by that CPU.
 */
int fastcall queue_work(struct workqueue_struct *wq, struct work_struct *work)
{
	int ret = 0, cpu = get_cpu();

	if (!test_and_set_bit(0, &work->pending)) {
		if (unlikely(is_single_threaded(wq)))
			cpu = 0;
		BUG_ON(!list_empty(&work->entry));
		__queue_work(wq->cpu_wq + cpu, work);
		ret = 1;
	}
	put_cpu();
	return ret;
}

static void delayed_work_timer_fn(unsigned long __data)
{
	struct work_struct *work = (struct work_struct *)__data;
	struct workqueue_struct *wq = work->wq_data;
	int cpu = smp_processor_id();

	if (unlikely(is_single_threaded(wq)))
		cpu = 0;

	__queue_work(wq->cpu_wq + cpu, work);
}

int fastcall queue_delayed_work(struct workqueue_struct *wq,
			struct work_struct *work, unsigned long delay)
{
	int ret = 0;
	struct timer_list *timer = &work->timer;

	if (!test_and_set_bit(0, &work->pending)) {
		BUG_ON(timer_pending(timer));
		BUG_ON(!list_empty(&work->entry));

		/* This stores wq for the moment, for the timer_fn */
		work->wq_data = wq;
		timer->expires = jiffies + delay;
		timer->data = (unsigned long)work;
		timer->function = delayed_work_timer_fn;
		add_timer(timer);
		ret = 1;
	}
	return ret;
}

static inline void run_workqueue(struct cpu_workqueue_struct *cwq)
{
	unsigned long flags;

	/*
	 * Keep taking off work from the queue until
	 * done.
	 */
	spin_lock_irqsave(&cwq->lock, flags);
	cwq->run_depth++;
	if (cwq->run_depth > 3) {
		/* morton gets to eat his hat */
		printk("%s: recursion depth exceeded: %d\n",
			__FUNCTION__, cwq->run_depth);
		dump_stack();
	}
	while (!list_empty(&cwq->worklist)) {
		struct work_struct *work = list_entry(cwq->worklist.next,
						struct work_struct, entry);
		void (*f) (void *) = work->func;
		void *data = work->data;

		list_del_init(cwq->worklist.next);
		spin_unlock_irqrestore(&cwq->lock, flags);

		BUG_ON(work->wq_data != cwq);
		clear_bit(0, &work->pending);
		f(data);

		spin_lock_irqsave(&cwq->lock, flags);
		cwq->remove_sequence++;
		wake_up(&cwq->work_done);
	}
	cwq->run_depth--;
	spin_unlock_irqrestore(&cwq->lock, flags);
}

static int worker_thread(void *__cwq)
{
	struct cpu_workqueue_struct *cwq = __cwq;
	DECLARE_WAITQUEUE(wait, current);
	struct k_sigaction sa;
	sigset_t blocked;

	current->flags |= PF_NOFREEZE;

	set_user_nice(current, -5);

	/* Block and flush all signals */
	sigfillset(&blocked);
	sigprocmask(SIG_BLOCK, &blocked, NULL);
	flush_signals(current);

	/* SIG_IGN makes children autoreap: see do_notify_parent(). */
	sa.sa.sa_handler = SIG_IGN;
	sa.sa.sa_flags = 0;
	siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
	do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);

	set_current_state(TASK_INTERRUPTIBLE);
	while (!kthread_should_stop()) {
		add_wait_queue(&cwq->more_work, &wait);
		if (list_empty(&cwq->worklist))
			schedule();
		else
			__set_current_state(TASK_RUNNING);
		remove_wait_queue(&cwq->more_work, &wait);

		if (!list_empty(&cwq->worklist))
			run_workqueue(cwq);
		set_current_state(TASK_INTERRUPTIBLE);
	}
	__set_current_state(TASK_RUNNING);
	return 0;
}

static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
{
	if (cwq->thread == current) {
		/*
		 * Probably keventd trying to flush its own queue. So simply run
		 * it by hand rather than deadlocking.
		 */
		run_workqueue(cwq);
	} else {
		DEFINE_WAIT(wait);
		long sequence_needed;

		spin_lock_irq(&cwq->lock);
		sequence_needed = cwq->insert_sequence;

		while (sequence_needed - cwq->remove_sequence > 0) {
			prepare_to_wait(&cwq->work_done, &wait,
					TASK_UNINTERRUPTIBLE);
			spin_unlock_irq(&cwq->lock);
			schedule();
			spin_lock_irq(&cwq->lock);
		}
		finish_wait(&cwq->work_done, &wait);
		spin_unlock_irq(&cwq->lock);
	}
}

/*
 * flush_workqueue - ensure that any scheduled work has run to completion.
 *
 * Forces execution of the workqueue and blocks until its completion.
 * This is typically used in driver shutdown handlers.
 *
 * This function will sample each workqueue's current insert_sequence number and
 * will sleep until the head sequence is greater than or equal to that.  This
 * means that we sleep until all works which were queued on entry have been
 * handled, but we are not livelocked by new incoming ones.
 *
 * This function used to run the workqueues itself.  Now we just wait for the
 * helper threads to do it.
 */
void fastcall flush_workqueue(struct workqueue_struct *wq)
{
	might_sleep();

	if (is_single_threaded(wq)) {
		/* Always use cpu 0's area. */
		flush_cpu_workqueue(wq->cpu_wq + 0);
	} else {
		int cpu;

		lock_cpu_hotplug();
		for_each_online_cpu(cpu)
			flush_cpu_workqueue(wq->cpu_wq + cpu);
		unlock_cpu_hotplug();
	}
}

static struct task_struct *create_workqueue_thread(struct workqueue_struct *wq,
						   int cpu)
{
	struct cpu_workqueue_struct *cwq = wq->cpu_wq + cpu;
	struct task_struct *p;

	spin_lock_init(&cwq->lock);
	cwq->wq = wq;
	cwq->thread = NULL;
	cwq->insert_sequence = 0;
	cwq->remove_sequence = 0;
	INIT_LIST_HEAD(&cwq->worklist);
	init_waitqueue_head(&cwq->more_work);
	init_waitqueue_head(&cwq->work_done);

	if (is_single_threaded(wq))
		p = kthread_create(worker_thread, cwq, "%s", wq->name);
	else
		p = kthread_create(worker_thread, cwq, "%s/%d", wq->name, cpu);
	if (IS_ERR(p))
		return NULL;
	cwq->thread = p;
	return p;
}

struct workqueue_struct *__create_workqueue(const char *name,
					    int singlethread)
{
	int cpu, destroy = 0;
	struct workqueue_struct *wq;
	struct task_struct *p;

	BUG_ON(strlen(name) > 10);

	wq = kmalloc(sizeof(*wq), GFP_KERNEL);
	if (!wq)
		return NULL;
	memset(wq, 0, sizeof(*wq));

	wq->name = name;
	/* We don't need the distraction of CPUs appearing and vanishing. */
	lock_cpu_hotplug();
	if (singlethread) {
		INIT_LIST_HEAD(&wq->list);
		p = create_workqueue_thread(wq, 0);
		if (!p)
			destroy = 1;
		else
			wake_up_process(p);
	} else {
		spin_lock(&workqueue_lock);
		list_add(&wq->list, &workqueues);
		spin_unlock(&workqueue_lock);
		for_each_online_cpu(cpu) {
			p = create_workqueue_thread(wq, cpu);
			if (p) {
				kthread_bind(p, cpu);
				wake_up_process(p);
			} else
				destroy = 1;
		}
	}
	unlock_cpu_hotplug();

	/*
	 * Was there any error during startup? If yes then clean up:
	 */
	if (destroy) {
		destroy_workqueue(wq);
		wq = NULL;
	}
	return wq;
}

static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)
{
	struct cpu_workqueue_struct *cwq;
	unsigned long flags;
	struct task_struct *p;

	cwq = wq->cpu_wq + cpu;
	spin_lock_irqsave(&cwq->lock, flags);
	p = cwq->thread;
	cwq->thread = NULL;
	spin_unlock_irqrestore(&cwq->lock, flags);
	if (p)
		kthread_stop(p);
}

void destroy_workqueue(struct workqueue_struct *wq)
{
	int cpu;

	flush_workqueue(wq);

	/* We don't need the distraction of CPUs appearing and vanishing. */
	lock_cpu_hotplug();
	if (is_single_threaded(wq))
		cleanup_workqueue_thread(wq, 0);
	else {
		for_each_online_cpu(cpu)
			cleanup_workqueue_thread(wq, cpu);
		spin_lock(&workqueue_lock);
		list_del(&wq->list);
		spin_unlock(&workqueue_lock);
	}
	unlock_cpu_hotplug();
	kfree(wq);
}

static struct workqueue_struct *keventd_wq;

int fastcall schedule_work(struct work_struct *work)
{
	return queue_work(keventd_wq, work);
}

int fastcall schedule_delayed_work(struct work_struct *work, unsigned long delay)
{
	return queue_delayed_work(keventd_wq, work, delay);
}

int schedule_delayed_work_on(int cpu,
			struct work_struct *work, unsigned long delay)
{
	int ret = 0;
	struct timer_list *timer = &work->timer;

	if (!test_and_set_bit(0, &work->pending)) {
		BUG_ON(timer_pending(timer));
		BUG_ON(!list_empty(&work->entry));
		/* This stores keventd_wq for the moment, for the timer_fn */
		work->wq_data = keventd_wq;
		timer->expires = jiffies + delay;
		timer->data = (unsigned long)work;
		timer->function = delayed_work_timer_fn;
		add_timer_on(timer, cpu);
		ret = 1;
	}
	return ret;
}

void flush_scheduled_work(void)
{
	flush_workqueue(keventd_wq);
}

/**
 * cancel_rearming_delayed_workqueue - reliably kill off a delayed
 *			work whose handler rearms the delayed work.
 * @wq:   the controlling workqueue structure
 * @work: the delayed work struct
 */
void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
				       struct work_struct *work)
{
	while (!cancel_delayed_work(work))
		flush_workqueue(wq);
}
EXPORT_SYMBOL(cancel_rearming_delayed_workqueue);

/**
 * cancel_rearming_delayed_work - reliably kill off a delayed keventd
 *			work whose handler rearms the delayed work.
 * @work: the delayed work struct
 */
void cancel_rearming_delayed_work(struct work_struct *work)
{
	cancel_rearming_delayed_workqueue(keventd_wq, work);
}
EXPORT_SYMBOL(cancel_rearming_delayed_work);

int keventd_up(void)
{
	return keventd_wq != NULL;
}

int current_is_keventd(void)
{
	struct cpu_workqueue_struct *cwq;
	int cpu = smp_processor_id();	/* preempt-safe: keventd is per-cpu */
	int ret = 0;

	BUG_ON(!keventd_wq);

	cwq = keventd_wq->cpu_wq + cpu;
	if (current == cwq->thread)
		ret = 1;

	return ret;

}

#ifdef CONFIG_HOTPLUG_CPU
/* Take the work from this (downed) CPU. */
static void take_over_work(struct workqueue_struct *wq, unsigned int cpu)
{
	struct cpu_workqueue_struct *cwq = wq->cpu_wq + cpu;
	LIST_HEAD(list);
	struct work_struct *work;

	spin_lock_irq(&cwq->lock);
	list_splice_init(&cwq->worklist, &list);

	while (!list_empty(&list)) {
		printk("Taking work for %s\n", wq->name);
		work = list_entry(list.next,struct work_struct,entry);
		list_del(&work->entry);
		__queue_work(wq->cpu_wq + smp_processor_id(), work);
	}
	spin_unlock_irq(&cwq->lock);
}

/* We're holding the cpucontrol mutex here */
static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
				  unsigned long action,
				  void *hcpu)
{
	unsigned int hotcpu = (unsigned long)hcpu;
	struct workqueue_struct *wq;

	switch (action) {
	case CPU_UP_PREPARE:
		/* Create a new workqueue thread for it. */
		list_for_each_entry(wq, &workqueues, list) {
			if (create_workqueue_thread(wq, hotcpu) < 0) {
				printk("workqueue for %i failed\n", hotcpu);
				return NOTIFY_BAD;
			}
		}
		break;

	case CPU_ONLINE:
		/* Kick off worker threads. */
		list_for_each_entry(wq, &workqueues, list) {
			kthread_bind(wq->cpu_wq[hotcpu].thread, hotcpu);
			wake_up_process(wq->cpu_wq[hotcpu].thread);
		}
		break;

	case CPU_UP_CANCELED:
		list_for_each_entry(wq, &workqueues, list) {
			/* Unbind so it can run. */
			kthread_bind(wq->cpu_wq[hotcpu].thread,
				     smp_processor_id());
			cleanup_workqueue_thread(wq, hotcpu);
		}
		break;

	case CPU_DEAD:
		list_for_each_entry(wq, &workqueues, list)
			cleanup_workqueue_thread(wq, hotcpu);
		list_for_each_entry(wq, &workqueues, list)
			take_over_work(wq, hotcpu);
		break;
	}

	return NOTIFY_OK;
}
#endif

void init_workqueues(void)
{
	hotcpu_notifier(workqueue_cpu_callback, 0);
	keventd_wq = create_workqueue("events");
	BUG_ON(!keventd_wq);
}

EXPORT_SYMBOL_GPL(__create_workqueue);
EXPORT_SYMBOL_GPL(queue_work);
EXPORT_SYMBOL_GPL(queue_delayed_work);
EXPORT_SYMBOL_GPL(flush_workqueue);
EXPORT_SYMBOL_GPL(destroy_workqueue);

EXPORT_SYMBOL(schedule_work);
EXPORT_SYMBOL(schedule_delayed_work);
EXPORT_SYMBOL(schedule_delayed_work_on);
EXPORT_SYMBOL(flush_scheduled_work);
1	/*
2	* linux/kernel/workqueue.c
3	*
4	* Generic mechanism for defining kernel helper threads for running
5	* arbitrary tasks in process context.
6	*
7	* Started by Ingo Molnar, Copyright (C) 2002
8	*
9	* Derived from the taskqueue/keventd code by:
10	*
11	* David Woodhouse <dwmw2@infradead.org>
12	* Andrew Morton <andrewm@uow.edu.au>
13	* Kai Petzke <wpp@marie.physik.tu-berlin.de>
14	* Theodore Ts'o <tytso@mit.edu>
15	*/
16
17	#include <linux/module.h>
18	#include <linux/kernel.h>
19	#include <linux/sched.h>
20	#include <linux/init.h>
21	#include <linux/signal.h>
22	#include <linux/completion.h>
23	#include <linux/workqueue.h>
24	#include <linux/slab.h>
25	#include <linux/cpu.h>
26	#include <linux/notifier.h>
27	#include <linux/kthread.h>
28
29	/*
30	* The per-CPU workqueue (if single thread, we always use cpu 0's).
31	*
32	* The sequence counters are for flush_scheduled_work(). It wants to wait
33	* until until all currently-scheduled works are completed, but it doesn't
34	* want to be livelocked by new, incoming ones. So it waits until
35	* remove_sequence is >= the insert_sequence which pertained when
36	* flush_scheduled_work() was called.
37	*/
38	struct cpu_workqueue_struct {
39
40	spinlock_t lock;
41
42	long remove_sequence; /* Least-recently added (next to run) */
43	long insert_sequence; /* Next to add */
44
45	struct list_head worklist;
46	wait_queue_head_t more_work;
47	wait_queue_head_t work_done;
48
49	struct workqueue_struct *wq;
50	task_t *thread;
51
52	int run_depth; /* Detect run_workqueue() recursion depth */
53	} ____cacheline_aligned;
54
55	/*
56	* The externally visible workqueue abstraction is an array of
57	* per-CPU workqueues:
58	*/
59	struct workqueue_struct {
60	struct cpu_workqueue_struct cpu_wq[NR_CPUS];
61	const char *name;
62	struct list_head list; /* Empty if single thread */
63	};
64
65	/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
66	threads to each one as cpus come/go. */
67	static DEFINE_SPINLOCK(workqueue_lock);
68	static LIST_HEAD(workqueues);
69
70	/* If it's single threaded, it isn't in the list of workqueues. */
71	static inline int is_single_threaded(struct workqueue_struct *wq)
72	{
73	return list_empty(&wq->list);
74	}
75
76	/* Preempt must be disabled. */
77	static void __queue_work(struct cpu_workqueue_struct *cwq,
78	struct work_struct *work)
79	{
80	unsigned long flags;
81
82	spin_lock_irqsave(&cwq->lock, flags);
83	work->wq_data = cwq;
84	list_add_tail(&work->entry, &cwq->worklist);
85	cwq->insert_sequence++;
86	wake_up(&cwq->more_work);
87	spin_unlock_irqrestore(&cwq->lock, flags);
88	}
89
90	/*
91	* Queue work on a workqueue. Return non-zero if it was successfully
92	* added.
93	*
94	* We queue the work to the CPU it was submitted, but there is no
95	* guarantee that it will be processed by that CPU.
96	*/
97	int fastcall queue_work(struct workqueue_struct wq, struct work_struct work)
98	{
99	int ret = 0, cpu = get_cpu();
100
101	if (!test_and_set_bit(0, &work->pending)) {
102	if (unlikely(is_single_threaded(wq)))
103	cpu = 0;
104	BUG_ON(!list_empty(&work->entry));
105	__queue_work(wq->cpu_wq + cpu, work);
106	ret = 1;
107	}
108	put_cpu();
109	return ret;
110	}
111
112	static void delayed_work_timer_fn(unsigned long __data)
113	{
114	struct work_struct work = (struct work_struct )__data;
115	struct workqueue_struct *wq = work->wq_data;
116	int cpu = smp_processor_id();
117
118	if (unlikely(is_single_threaded(wq)))
119	cpu = 0;
120
121	__queue_work(wq->cpu_wq + cpu, work);
122	}
123
124	int fastcall queue_delayed_work(struct workqueue_struct *wq,
125	struct work_struct *work, unsigned long delay)
126	{
127	int ret = 0;
128	struct timer_list *timer = &work->timer;
129
130	if (!test_and_set_bit(0, &work->pending)) {
131	BUG_ON(timer_pending(timer));
132	BUG_ON(!list_empty(&work->entry));
133
134	/* This stores wq for the moment, for the timer_fn */
135	work->wq_data = wq;
136	timer->expires = jiffies + delay;
137	timer->data = (unsigned long)work;
138	timer->function = delayed_work_timer_fn;
139	add_timer(timer);
140	ret = 1;
141	}
142	return ret;
143	}
144
145	static inline void run_workqueue(struct cpu_workqueue_struct *cwq)
146	{
147	unsigned long flags;
148
149	/*
150	* Keep taking off work from the queue until
151	* done.
152	*/
153	spin_lock_irqsave(&cwq->lock, flags);
154	cwq->run_depth++;
155	if (cwq->run_depth > 3) {
156	/* morton gets to eat his hat */
157	printk("%s: recursion depth exceeded: %d\n",
158	__FUNCTION__, cwq->run_depth);
159	dump_stack();
160	}
161	while (!list_empty(&cwq->worklist)) {
162	struct work_struct *work = list_entry(cwq->worklist.next,
163	struct work_struct, entry);
164	void (f) (void ) = work->func;
165	void *data = work->data;
166
167	list_del_init(cwq->worklist.next);
168	spin_unlock_irqrestore(&cwq->lock, flags);
169
170	BUG_ON(work->wq_data != cwq);
171	clear_bit(0, &work->pending);
172	f(data);
173
174	spin_lock_irqsave(&cwq->lock, flags);
175	cwq->remove_sequence++;
176	wake_up(&cwq->work_done);
177	}
178	cwq->run_depth--;
179	spin_unlock_irqrestore(&cwq->lock, flags);
180	}
181
182	static int worker_thread(void *__cwq)
183	{
184	struct cpu_workqueue_struct *cwq = __cwq;
185	DECLARE_WAITQUEUE(wait, current);
186	struct k_sigaction sa;
187	sigset_t blocked;
188
189	current->flags \|= PF_NOFREEZE;
190
191	set_user_nice(current, -5);
192
193	/* Block and flush all signals */
194	sigfillset(&blocked);
195	sigprocmask(SIG_BLOCK, &blocked, NULL);
196	flush_signals(current);
197
198	/* SIG_IGN makes children autoreap: see do_notify_parent(). */
199	sa.sa.sa_handler = SIG_IGN;
200	sa.sa.sa_flags = 0;
201	siginitset(&sa.sa.sa_mask, sigmask(SIGCHLD));
202	do_sigaction(SIGCHLD, &sa, (struct k_sigaction *)0);
203
204	set_current_state(TASK_INTERRUPTIBLE);
205	while (!kthread_should_stop()) {
206	add_wait_queue(&cwq->more_work, &wait);
207	if (list_empty(&cwq->worklist))
208	schedule();
209	else
210	__set_current_state(TASK_RUNNING);
211	remove_wait_queue(&cwq->more_work, &wait);
212
213	if (!list_empty(&cwq->worklist))
214	run_workqueue(cwq);
215	set_current_state(TASK_INTERRUPTIBLE);
216	}
217	__set_current_state(TASK_RUNNING);
218	return 0;
219	}
220
221	static void flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
222	{
223	if (cwq->thread == current) {
224	/*
225	* Probably keventd trying to flush its own queue. So simply run
226	* it by hand rather than deadlocking.
227	*/
228	run_workqueue(cwq);
229	} else {
230	DEFINE_WAIT(wait);
231	long sequence_needed;
232
233	spin_lock_irq(&cwq->lock);
234	sequence_needed = cwq->insert_sequence;
235
236	while (sequence_needed - cwq->remove_sequence > 0) {
237	prepare_to_wait(&cwq->work_done, &wait,
238	TASK_UNINTERRUPTIBLE);
239	spin_unlock_irq(&cwq->lock);
240	schedule();
241	spin_lock_irq(&cwq->lock);
242	}
243	finish_wait(&cwq->work_done, &wait);
244	spin_unlock_irq(&cwq->lock);
245	}
246	}
247
248	/*
249	* flush_workqueue - ensure that any scheduled work has run to completion.
250	*
251	* Forces execution of the workqueue and blocks until its completion.
252	* This is typically used in driver shutdown handlers.
253	*
254	* This function will sample each workqueue's current insert_sequence number and
255	* will sleep until the head sequence is greater than or equal to that. This
256	* means that we sleep until all works which were queued on entry have been
257	* handled, but we are not livelocked by new incoming ones.
258	*
259	* This function used to run the workqueues itself. Now we just wait for the
260	* helper threads to do it.
261	*/
262	void fastcall flush_workqueue(struct workqueue_struct *wq)
263	{
264	might_sleep();
265
266	if (is_single_threaded(wq)) {
267	/* Always use cpu 0's area. */
268	flush_cpu_workqueue(wq->cpu_wq + 0);
269	} else {
270	int cpu;
271
272	lock_cpu_hotplug();
273	for_each_online_cpu(cpu)
274	flush_cpu_workqueue(wq->cpu_wq + cpu);
275	unlock_cpu_hotplug();
276	}
277	}
278
279	static struct task_struct create_workqueue_thread(struct workqueue_struct wq,
280	int cpu)
281	{
282	struct cpu_workqueue_struct *cwq = wq->cpu_wq + cpu;
283	struct task_struct *p;
284
285	spin_lock_init(&cwq->lock);
286	cwq->wq = wq;
287	cwq->thread = NULL;
288	cwq->insert_sequence = 0;
289	cwq->remove_sequence = 0;
290	INIT_LIST_HEAD(&cwq->worklist);
291	init_waitqueue_head(&cwq->more_work);
292	init_waitqueue_head(&cwq->work_done);
293
294	if (is_single_threaded(wq))
295	p = kthread_create(worker_thread, cwq, "%s", wq->name);
296	else
297	p = kthread_create(worker_thread, cwq, "%s/%d", wq->name, cpu);
298	if (IS_ERR(p))
299	return NULL;
300	cwq->thread = p;
301	return p;
302	}
303
304	struct workqueue_struct __create_workqueue(const char name,
305	int singlethread)
306	{
307	int cpu, destroy = 0;
308	struct workqueue_struct *wq;
309	struct task_struct *p;
310
311	BUG_ON(strlen(name) > 10);
312
313	wq = kmalloc(sizeof(*wq), GFP_KERNEL);
314	if (!wq)
315	return NULL;
316	memset(wq, 0, sizeof(*wq));
317
318	wq->name = name;
319	/* We don't need the distraction of CPUs appearing and vanishing. */
320	lock_cpu_hotplug();
321	if (singlethread) {
322	INIT_LIST_HEAD(&wq->list);
323	p = create_workqueue_thread(wq, 0);
324	if (!p)
325	destroy = 1;
326	else
327	wake_up_process(p);
328	} else {
329	spin_lock(&workqueue_lock);
330	list_add(&wq->list, &workqueues);
331	spin_unlock(&workqueue_lock);
332	for_each_online_cpu(cpu) {
333	p = create_workqueue_thread(wq, cpu);
334	if (p) {
335	kthread_bind(p, cpu);
336	wake_up_process(p);
337	} else
338	destroy = 1;
339	}
340	}
341	unlock_cpu_hotplug();
342
343	/*
344	* Was there any error during startup? If yes then clean up:
345	*/
346	if (destroy) {
347	destroy_workqueue(wq);
348	wq = NULL;
349	}
350	return wq;
351	}
352
353	static void cleanup_workqueue_thread(struct workqueue_struct *wq, int cpu)
354	{
355	struct cpu_workqueue_struct *cwq;
356	unsigned long flags;
357	struct task_struct *p;
358
359	cwq = wq->cpu_wq + cpu;
360	spin_lock_irqsave(&cwq->lock, flags);
361	p = cwq->thread;
362	cwq->thread = NULL;
363	spin_unlock_irqrestore(&cwq->lock, flags);
364	if (p)
365	kthread_stop(p);
366	}
367
368	void destroy_workqueue(struct workqueue_struct *wq)
369	{
370	int cpu;
371
372	flush_workqueue(wq);
373
374	/* We don't need the distraction of CPUs appearing and vanishing. */
375	lock_cpu_hotplug();
376	if (is_single_threaded(wq))
377	cleanup_workqueue_thread(wq, 0);
378	else {
379	for_each_online_cpu(cpu)
380	cleanup_workqueue_thread(wq, cpu);
381	spin_lock(&workqueue_lock);
382	list_del(&wq->list);
383	spin_unlock(&workqueue_lock);
384	}
385	unlock_cpu_hotplug();
386	kfree(wq);
387	}
388
389	static struct workqueue_struct *keventd_wq;
390
391	int fastcall schedule_work(struct work_struct *work)
392	{
393	return queue_work(keventd_wq, work);
394	}
395
396	int fastcall schedule_delayed_work(struct work_struct *work, unsigned long delay)
397	{
398	return queue_delayed_work(keventd_wq, work, delay);
399	}
400
401	int schedule_delayed_work_on(int cpu,
402	struct work_struct *work, unsigned long delay)
403	{
404	int ret = 0;
405	struct timer_list *timer = &work->timer;
406
407	if (!test_and_set_bit(0, &work->pending)) {
408	BUG_ON(timer_pending(timer));
409	BUG_ON(!list_empty(&work->entry));
410	/* This stores keventd_wq for the moment, for the timer_fn */
411	work->wq_data = keventd_wq;
412	timer->expires = jiffies + delay;
413	timer->data = (unsigned long)work;
414	timer->function = delayed_work_timer_fn;
415	add_timer_on(timer, cpu);
416	ret = 1;
417	}
418	return ret;
419	}
420
421	void flush_scheduled_work(void)
422	{
423	flush_workqueue(keventd_wq);
424	}
425
426	/**
427	* cancel_rearming_delayed_workqueue - reliably kill off a delayed
428	* work whose handler rearms the delayed work.
429	* @wq: the controlling workqueue structure
430	* @work: the delayed work struct
431	*/
432	void cancel_rearming_delayed_workqueue(struct workqueue_struct *wq,
433	struct work_struct *work)
434	{
435	while (!cancel_delayed_work(work))
436	flush_workqueue(wq);
437	}
438	EXPORT_SYMBOL(cancel_rearming_delayed_workqueue);
439
440	/**
441	* cancel_rearming_delayed_work - reliably kill off a delayed keventd
442	* work whose handler rearms the delayed work.
443	* @work: the delayed work struct
444	*/
445	void cancel_rearming_delayed_work(struct work_struct *work)
446	{
447	cancel_rearming_delayed_workqueue(keventd_wq, work);
448	}
449	EXPORT_SYMBOL(cancel_rearming_delayed_work);
450
451	int keventd_up(void)
452	{
453	return keventd_wq != NULL;
454	}
455
456	int current_is_keventd(void)
457	{
458	struct cpu_workqueue_struct *cwq;
459	int cpu = smp_processor_id(); /* preempt-safe: keventd is per-cpu */
460	int ret = 0;
461
462	BUG_ON(!keventd_wq);
463
464	cwq = keventd_wq->cpu_wq + cpu;
465	if (current == cwq->thread)
466	ret = 1;
467
468	return ret;
469
470	}
471
472	#ifdef CONFIG_HOTPLUG_CPU
473	/* Take the work from this (downed) CPU. */
474	static void take_over_work(struct workqueue_struct *wq, unsigned int cpu)
475	{
476	struct cpu_workqueue_struct *cwq = wq->cpu_wq + cpu;
477	LIST_HEAD(list);
478	struct work_struct *work;
479
480	spin_lock_irq(&cwq->lock);
481	list_splice_init(&cwq->worklist, &list);
482
483	while (!list_empty(&list)) {
484	printk("Taking work for %s\n", wq->name);
485	work = list_entry(list.next,struct work_struct,entry);
486	list_del(&work->entry);
487	__queue_work(wq->cpu_wq + smp_processor_id(), work);
488	}
489	spin_unlock_irq(&cwq->lock);
490	}
491
492	/* We're holding the cpucontrol mutex here */
493	static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
494	unsigned long action,
495	void *hcpu)
496	{
497	unsigned int hotcpu = (unsigned long)hcpu;
498	struct workqueue_struct *wq;
499
500	switch (action) {
501	case CPU_UP_PREPARE:
502	/* Create a new workqueue thread for it. */
503	list_for_each_entry(wq, &workqueues, list) {
504	if (create_workqueue_thread(wq, hotcpu) < 0) {
505	printk("workqueue for %i failed\n", hotcpu);
506	return NOTIFY_BAD;
507	}
508	}
509	break;
510
511	case CPU_ONLINE:
512	/* Kick off worker threads. */
513	list_for_each_entry(wq, &workqueues, list) {
514	kthread_bind(wq->cpu_wq[hotcpu].thread, hotcpu);
515	wake_up_process(wq->cpu_wq[hotcpu].thread);
516	}
517	break;
518
519	case CPU_UP_CANCELED:
520	list_for_each_entry(wq, &workqueues, list) {
521	/* Unbind so it can run. */
522	kthread_bind(wq->cpu_wq[hotcpu].thread,
523	smp_processor_id());
524	cleanup_workqueue_thread(wq, hotcpu);
525	}
526	break;
527
528	case CPU_DEAD:
529	list_for_each_entry(wq, &workqueues, list)
530	cleanup_workqueue_thread(wq, hotcpu);
531	list_for_each_entry(wq, &workqueues, list)
532	take_over_work(wq, hotcpu);
533	break;
534	}
535
536	return NOTIFY_OK;
537	}
538	#endif
539
540	void init_workqueues(void)
541	{
542	hotcpu_notifier(workqueue_cpu_callback, 0);
543	keventd_wq = create_workqueue("events");
544	BUG_ON(!keventd_wq);
545	}
546
547	EXPORT_SYMBOL_GPL(__create_workqueue);
548	EXPORT_SYMBOL_GPL(queue_work);
549	EXPORT_SYMBOL_GPL(queue_delayed_work);
550	EXPORT_SYMBOL_GPL(flush_workqueue);
551	EXPORT_SYMBOL_GPL(destroy_workqueue);
552
553	EXPORT_SYMBOL(schedule_work);
554	EXPORT_SYMBOL(schedule_delayed_work);
555	EXPORT_SYMBOL(schedule_delayed_work_on);
556	EXPORT_SYMBOL(flush_scheduled_work);