[mirror_ubuntu-zesty-kernel.git] / kernel / power / process.c

/*
 * drivers/power/process.c - Functions for starting/stopping processes on 
 *                           suspend transitions.
 *
 * Originally from swsusp.
 */


#undef DEBUG

#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>

/* 
 * Timeout for stopping processes
 */
#define TIMEOUT	(20 * HZ)

#define FREEZER_KERNEL_THREADS 0
#define FREEZER_USER_SPACE 1

static inline int freezeable(struct task_struct * p)
{
	if ((p == current) ||
	    (p->flags & PF_NOFREEZE) ||
	    (p->exit_state != 0))
		return 0;
	return 1;
}

/*
 * freezing is complete, mark current process as frozen
 */
static inline void frozen_process(void)
{
	if (!unlikely(current->flags & PF_NOFREEZE)) {
		current->flags |= PF_FROZEN;
		wmb();
	}
	clear_freeze_flag(current);
}

/* Refrigerator is place where frozen processes are stored :-). */
void refrigerator(void)
{
	/* Hmm, should we be allowed to suspend when there are realtime
	   processes around? */
	long save;

	task_lock(current);
	if (freezing(current)) {
		frozen_process();
		task_unlock(current);
	} else {
		task_unlock(current);
		return;
	}
	save = current->state;
	pr_debug("%s entered refrigerator\n", current->comm);

	spin_lock_irq(&current->sighand->siglock);
	recalc_sigpending(); /* We sent fake signal, clean it up */
	spin_unlock_irq(&current->sighand->siglock);

	for (;;) {
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (!frozen(current))
			break;
		schedule();
	}
	pr_debug("%s left refrigerator\n", current->comm);
	__set_current_state(save);
}

static void fake_signal_wake_up(struct task_struct *p, int resume)
{
	unsigned long flags;

	spin_lock_irqsave(&p->sighand->siglock, flags);
	signal_wake_up(p, resume);
	spin_unlock_irqrestore(&p->sighand->siglock, flags);
}

static void send_fake_signal(struct task_struct *p)
{
	if (task_is_stopped(p))
		force_sig_specific(SIGSTOP, p);
	fake_signal_wake_up(p, task_is_stopped(p));
}

static int has_mm(struct task_struct *p)
{
	return (p->mm && !(p->flags & PF_BORROWED_MM));
}

/**
 *	freeze_task - send a freeze request to given task
 *	@p: task to send the request to
 *	@with_mm_only: if set, the request will only be sent if the task has its
 *		own mm
 *	Return value: 0, if @with_mm_only is set and the task has no mm of its
 *		own or the task is frozen, 1, otherwise
 *
 *	The freeze request is sent by seting the tasks's TIF_FREEZE flag and
 *	either sending a fake signal to it or waking it up, depending on whether
 *	or not it has its own mm (ie. it is a user land task).  If @with_mm_only
 *	is set and the task has no mm of its own (ie. it is a kernel thread),
 *	its TIF_FREEZE flag should not be set.
 *
 *	The task_lock() is necessary to prevent races with exit_mm() or
 *	use_mm()/unuse_mm() from occuring.
 */
static int freeze_task(struct task_struct *p, int with_mm_only)
{
	int ret = 1;

	task_lock(p);
	if (freezing(p)) {
		if (has_mm(p)) {
			if (!signal_pending(p))
				fake_signal_wake_up(p, 0);
		} else {
			if (with_mm_only)
				ret = 0;
			else
				wake_up_state(p, TASK_INTERRUPTIBLE);
		}
	} else {
		rmb();
		if (frozen(p)) {
			ret = 0;
		} else {
			if (has_mm(p)) {
				set_freeze_flag(p);
				send_fake_signal(p);
			} else {
				if (with_mm_only) {
					ret = 0;
				} else {
					set_freeze_flag(p);
					wake_up_state(p, TASK_INTERRUPTIBLE);
				}
			}
		}
	}
	task_unlock(p);
	return ret;
}

static void cancel_freezing(struct task_struct *p)
{
	unsigned long flags;

	if (freezing(p)) {
		pr_debug("  clean up: %s\n", p->comm);
		clear_freeze_flag(p);
		spin_lock_irqsave(&p->sighand->siglock, flags);
		recalc_sigpending_and_wake(p);
		spin_unlock_irqrestore(&p->sighand->siglock, flags);
	}
}

static int try_to_freeze_tasks(int freeze_user_space)
{
	struct task_struct *g, *p;
	unsigned long end_time;
	unsigned int todo;
	struct timeval start, end;
	s64 elapsed_csecs64;
	unsigned int elapsed_csecs;

	do_gettimeofday(&start);

	end_time = jiffies + TIMEOUT;
	do {
		todo = 0;
		read_lock(&tasklist_lock);
		do_each_thread(g, p) {
			if (frozen(p) || !freezeable(p))
				continue;

			if (task_is_traced(p) && frozen(p->parent)) {
				cancel_freezing(p);
				continue;
			}

			if (!freeze_task(p, freeze_user_space))
				continue;

			if (!freezer_should_skip(p))
				todo++;
		} while_each_thread(g, p);
		read_unlock(&tasklist_lock);
		yield();			/* Yield is okay here */
		if (time_after(jiffies, end_time))
			break;
	} while (todo);

	do_gettimeofday(&end);
	elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
	do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
	elapsed_csecs = elapsed_csecs64;

	if (todo) {
		/* This does not unfreeze processes that are already frozen
		 * (we have slightly ugly calling convention in that respect,
		 * and caller must call thaw_processes() if something fails),
		 * but it cleans up leftover PF_FREEZE requests.
		 */
		printk("\n");
		printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
				"(%d tasks refusing to freeze):\n",
				elapsed_csecs / 100, elapsed_csecs % 100, todo);
		show_state();
		read_lock(&tasklist_lock);
		do_each_thread(g, p) {
			task_lock(p);
			if (freezing(p) && !freezer_should_skip(p))
				printk(KERN_ERR " %s\n", p->comm);
			cancel_freezing(p);
			task_unlock(p);
		} while_each_thread(g, p);
		read_unlock(&tasklist_lock);
	} else {
		printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
			elapsed_csecs % 100);
	}

	return todo ? -EBUSY : 0;
}

/**
 *	freeze_processes - tell processes to enter the refrigerator
 */
int freeze_processes(void)
{
	int error;

	printk("Freezing user space processes ... ");
	error = try_to_freeze_tasks(FREEZER_USER_SPACE);
	if (error)
		goto Exit;
	printk("done.\n");

	printk("Freezing remaining freezable tasks ... ");
	error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
	if (error)
		goto Exit;
	printk("done.");
 Exit:
	BUG_ON(in_atomic());
	printk("\n");
	return error;
}

static void thaw_tasks(int thaw_user_space)
{
	struct task_struct *g, *p;

	read_lock(&tasklist_lock);
	do_each_thread(g, p) {
		if (!freezeable(p))
			continue;

		if (!p->mm == thaw_user_space)
			continue;

		thaw_process(p);
	} while_each_thread(g, p);
	read_unlock(&tasklist_lock);
}

void thaw_processes(void)
{
	printk("Restarting tasks ... ");
	thaw_tasks(FREEZER_KERNEL_THREADS);
	thaw_tasks(FREEZER_USER_SPACE);
	schedule();
	printk("done.\n");
}

EXPORT_SYMBOL(refrigerator);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* drivers/power/process.c - Functions for starting/stopping processes on
	3	* suspend transitions.
	4	*
	5	* Originally from swsusp.
	6	*/
	7
	8
	9	#undef DEBUG
	10
1da177e4 LT	11	#include <linux/interrupt.h>
	12	#include <linux/suspend.h>
	13	#include <linux/module.h>
02aaeb9b	14	#include <linux/syscalls.h>
7dfb7103	15	#include <linux/freezer.h>
1da177e4 LT	16
	17	/*
	18	* Timeout for stopping processes
	19	*/
02aaeb9b	20	#define TIMEOUT (20 * HZ)
1da177e4	21
a9b6f562 RW	22	#define FREEZER_KERNEL_THREADS 0
a9b6f562 RW	23	#define FREEZER_USER_SPACE 1
1da177e4 LT	24
	25	static inline int freezeable(struct task_struct * p)
	26	{
1065d130	27	if ((p == current) \|\|
1da177e4	28	(p->flags & PF_NOFREEZE) \|\|
1065d130	29	(p->exit_state != 0))
1da177e4 LT	30	return 0;
	31	return 1;
	32	}
	33
88f18ba0 GS	34	/*
	35	* freezing is complete, mark current process as frozen
	36	*/
	37	static inline void frozen_process(void)
	38	{
	39	if (!unlikely(current->flags & PF_NOFREEZE)) {
	40	current->flags \|= PF_FROZEN;
	41	wmb();
	42	}
0c1eecfb	43	clear_freeze_flag(current);
88f18ba0 GS	44	}
88f18ba0 GS	45
1da177e4	46	/* Refrigerator is place where frozen processes are stored :-). */
3e1d1d28	47	void refrigerator(void)
1da177e4 LT	48	{
	49	/* Hmm, should we be allowed to suspend when there are realtime
	50	processes around? */
	51	long save;
33e1c288 RW	52
	53	task_lock(current);
	54	if (freezing(current)) {
88f18ba0	55	frozen_process();
33e1c288 RW	56	task_unlock(current);
	57	} else {
	58	task_unlock(current);
	59	return;
	60	}
1da177e4	61	save = current->state;
1da177e4	62	pr_debug("%s entered refrigerator\n", current->comm);
1da177e4 LT	63
	64	spin_lock_irq(&current->sighand->siglock);
	65	recalc_sigpending(); /* We sent fake signal, clean it up */
	66	spin_unlock_irq(&current->sighand->siglock);
	67
433ecb4a ON	68	for (;;) {
	69	set_current_state(TASK_UNINTERRUPTIBLE);
	70	if (!frozen(current))
	71	break;
1da177e4	72	schedule();
2a23b5d1	73	}
1da177e4	74	pr_debug("%s left refrigerator\n", current->comm);
f4a3a7d6	75	__set_current_state(save);
1da177e4 LT	76	}
1da177e4 LT	77
d5d8c597	78	static void fake_signal_wake_up(struct task_struct *p, int resume)
02aaeb9b RW	79	{
	80	unsigned long flags;
	81
d5d8c597 RW	82	spin_lock_irqsave(&p->sighand->siglock, flags);
	83	signal_wake_up(p, resume);
	84	spin_unlock_irqrestore(&p->sighand->siglock, flags);
	85	}
	86
	87	static void send_fake_signal(struct task_struct *p)
	88	{
d2f60e5f	89	if (task_is_stopped(p))
d5d8c597	90	force_sig_specific(SIGSTOP, p);
d2f60e5f	91	fake_signal_wake_up(p, task_is_stopped(p));
d5d8c597 RW	92	}
	93
	94	static int has_mm(struct task_struct *p)
	95	{
	96	return (p->mm && !(p->flags & PF_BORROWED_MM));
	97	}
	98
	99	/**
	100	* freeze_task - send a freeze request to given task
	101	* @p: task to send the request to
	102	* @with_mm_only: if set, the request will only be sent if the task has its
	103	* own mm
	104	* Return value: 0, if @with_mm_only is set and the task has no mm of its
	105	* own or the task is frozen, 1, otherwise
	106	*
	107	* The freeze request is sent by seting the tasks's TIF_FREEZE flag and
	108	* either sending a fake signal to it or waking it up, depending on whether
	109	* or not it has its own mm (ie. it is a user land task). If @with_mm_only
	110	* is set and the task has no mm of its own (ie. it is a kernel thread),
	111	* its TIF_FREEZE flag should not be set.
	112	*
	113	* The task_lock() is necessary to prevent races with exit_mm() or
	114	* use_mm()/unuse_mm() from occuring.
	115	*/
	116	static int freeze_task(struct task_struct *p, int with_mm_only)
	117	{
	118	int ret = 1;
	119
	120	task_lock(p);
	121	if (freezing(p)) {
	122	if (has_mm(p)) {
	123	if (!signal_pending(p))
	124	fake_signal_wake_up(p, 0);
	125	} else {
	126	if (with_mm_only)
	127	ret = 0;
	128	else
	129	wake_up_state(p, TASK_INTERRUPTIBLE);
	130	}
	131	} else {
8a102eed	132	rmb();
d5d8c597 RW	133	if (frozen(p)) {
	134	ret = 0;
	135	} else {
	136	if (has_mm(p)) {
	137	set_freeze_flag(p);
	138	send_fake_signal(p);
	139	} else {
	140	if (with_mm_only) {
	141	ret = 0;
	142	} else {
	143	set_freeze_flag(p);
	144	wake_up_state(p, TASK_INTERRUPTIBLE);
	145	}
	146	}
8a102eed	147	}
02aaeb9b	148	}
d5d8c597 RW	149	task_unlock(p);
d5d8c597 RW	150	return ret;
02aaeb9b RW	151	}
02aaeb9b RW	152
a7ef7878 RW	153	static void cancel_freezing(struct task_struct *p)
	154	{
	155	unsigned long flags;
	156
	157	if (freezing(p)) {
	158	pr_debug(" clean up: %s\n", p->comm);
0c1eecfb	159	clear_freeze_flag(p);
a7ef7878	160	spin_lock_irqsave(&p->sighand->siglock, flags);
7bb44ade	161	recalc_sigpending_and_wake(p);
a7ef7878 RW	162	spin_unlock_irqrestore(&p->sighand->siglock, flags);
	163	}
	164	}
	165
e7cd8a72	166	static int try_to_freeze_tasks(int freeze_user_space)
1da177e4	167	{
1da177e4	168	struct task_struct g, p;
11b2ce2b RW	169	unsigned long end_time;
11b2ce2b RW	170	unsigned int todo;
438e2ce6 RW	171	struct timeval start, end;
	172	s64 elapsed_csecs64;
	173	unsigned int elapsed_csecs;
	174
	175	do_gettimeofday(&start);
3e1d1d28	176
11b2ce2b	177	end_time = jiffies + TIMEOUT;
1da177e4	178	do {
11b2ce2b	179	todo = 0;
1da177e4 LT	180	read_lock(&tasklist_lock);
1da177e4 LT	181	do_each_thread(g, p) {
0c1eecfb	182	if (frozen(p) \|\| !freezeable(p))
1da177e4	183	continue;
11b2ce2b	184
d2f60e5f	185	if (task_is_traced(p) && frozen(p->parent)) {
d5d8c597 RW	186	cancel_freezing(p);
d5d8c597 RW	187	continue;
a7ef7878	188	}
d5d8c597 RW	189
	190	if (!freeze_task(p, freeze_user_space))
	191	continue;
	192
ba96a0c8 RW	193	if (!freezer_should_skip(p))
ba96a0c8 RW	194	todo++;
1da177e4 LT	195	} while_each_thread(g, p);
	196	read_unlock(&tasklist_lock);
	197	yield(); /* Yield is okay here */
c2cf7d87	198	if (time_after(jiffies, end_time))
6161b2ce	199	break;
11b2ce2b	200	} while (todo);
3e1d1d28	201
438e2ce6 RW	202	do_gettimeofday(&end);
	203	elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
	204	do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
	205	elapsed_csecs = elapsed_csecs64;
	206
6161b2ce	207	if (todo) {
11b2ce2b RW	208	/* This does not unfreeze processes that are already frozen
	209	* (we have slightly ugly calling convention in that respect,
	210	* and caller must call thaw_processes() if something fails),
	211	* but it cleans up leftover PF_FREEZE requests.
	212	*/
14b5b7cf	213	printk("\n");
438e2ce6	214	printk(KERN_ERR "Freezing of tasks failed after %d.%02d seconds "
11b2ce2b	215	"(%d tasks refusing to freeze):\n",
438e2ce6	216	elapsed_csecs / 100, elapsed_csecs % 100, todo);
328616e3	217	show_state();
6161b2ce	218	read_lock(&tasklist_lock);
02aaeb9b	219	do_each_thread(g, p) {
33e1c288	220	task_lock(p);
0c1eecfb	221	if (freezing(p) && !freezer_should_skip(p))
14b5b7cf	222	printk(KERN_ERR " %s\n", p->comm);
a7ef7878	223	cancel_freezing(p);
33e1c288	224	task_unlock(p);
02aaeb9b	225	} while_each_thread(g, p);
6161b2ce	226	read_unlock(&tasklist_lock);
438e2ce6 RW	227	} else {
	228	printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
	229	elapsed_csecs % 100);
6161b2ce PM	230	}
6161b2ce PM	231
e7cd8a72	232	return todo ? -EBUSY : 0;
11b2ce2b RW	233	}
	234
	235	/**
	236	* freeze_processes - tell processes to enter the refrigerator
11b2ce2b RW	237	*/
	238	int freeze_processes(void)
	239	{
e7cd8a72	240	int error;
11b2ce2b	241
b842ee57	242	printk("Freezing user space processes ... ");
e7cd8a72 RW	243	error = try_to_freeze_tasks(FREEZER_USER_SPACE);
e7cd8a72 RW	244	if (error)
b842ee57 RW	245	goto Exit;
b842ee57 RW	246	printk("done.\n");
11b2ce2b	247
b842ee57	248	printk("Freezing remaining freezable tasks ... ");
e7cd8a72 RW	249	error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
e7cd8a72 RW	250	if (error)
b842ee57 RW	251	goto Exit;
	252	printk("done.");
	253	Exit:
1da177e4	254	BUG_ON(in_atomic());
b842ee57 RW	255	printk("\n");
b842ee57 RW	256	return error;
1da177e4 LT	257	}
1da177e4 LT	258
a9b6f562	259	static void thaw_tasks(int thaw_user_space)
1da177e4 LT	260	{
	261	struct task_struct g, p;
	262
1da177e4	263	read_lock(&tasklist_lock);
a9b6f562 RW	264	do_each_thread(g, p) {
	265	if (!freezeable(p))
	266	continue;
ff39593a	267
0c1eecfb	268	if (!p->mm == thaw_user_space)
a9b6f562	269	continue;
1da177e4	270
ba96a0c8	271	thaw_process(p);
a9b6f562	272	} while_each_thread(g, p);
1da177e4	273	read_unlock(&tasklist_lock);
a9b6f562 RW	274	}
	275
	276	void thaw_processes(void)
	277	{
	278	printk("Restarting tasks ... ");
	279	thaw_tasks(FREEZER_KERNEL_THREADS);
	280	thaw_tasks(FREEZER_USER_SPACE);
1da177e4	281	schedule();
14b5b7cf	282	printk("done.\n");
1da177e4 LT	283	}
	284
	285	EXPORT_SYMBOL(refrigerator);