kernel/power/process.c - linux - Git at Google

 /*
  * 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)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&p->sighand->siglock, flags);
 	signal_wake_up(p, 0);
 	spin_unlock_irqrestore(&p->sighand->siglock, flags);
 }

 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);
 		} 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);
 				fake_signal_wake_up(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 (!freeze_task(p, freeze_user_space))
 				continue;

 			/*
 			 * Now that we've done set_freeze_flag, don't
 			 * perturb a task in TASK_STOPPED or TASK_TRACED.
 			 * It is "frozen enough".  If the task does wake
 			 * up, it will immediately call try_to_freeze.
 			 */
 			if (!task_is_stopped_or_traced(p) &&
 			    !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);
	/*
	* 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)
	{
	unsigned long flags;

	spin_lock_irqsave(&p->sighand->siglock, flags);
	signal_wake_up(p, 0);
	spin_unlock_irqrestore(&p->sighand->siglock, flags);
	}

	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);
	} 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);
	fake_signal_wake_up(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 (!freeze_task(p, freeze_user_space))
	continue;

	/*
	* Now that we've done set_freeze_flag, don't
	* perturb a task in TASK_STOPPED or TASK_TRACED.
	* It is "frozen enough". If the task does wake
	* up, it will immediately call try_to_freeze.
	*/
	if (!task_is_stopped_or_traced(p) &&
	!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);