/* * drivers/power/process.c - Functions for starting/stopping processes on  *                           suspend transitions. * * Originally from swsusp. */  #undef DEBUG #include <linux/smp_lock.h>#include <linux/interrupt.h>#include <linux/suspend.h>#include <linux/module.h>#include <linux/syscalls.h> /*  * Timeout for stopping processes */#define TIMEOUT	(20 * HZ)  static inline int freezeable(struct task_struct * p){	if ((p == current) || 	    (p->flags & PF_NOFREEZE) ||	    (p->exit_state == EXIT_ZOMBIE) ||	    (p->exit_state == EXIT_DEAD) ||	    (p->state == TASK_STOPPED))		return 0;	return 1;} /* 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;	save = current->state;	pr_debug("%s entered refrigerator\n", current->comm);	printk("="); 	frozen_process(current);	spin_lock_irq(&current->sighand->siglock);	recalc_sigpending(); /* We sent fake signal, clean it up */	spin_unlock_irq(&current->sighand->siglock); 	while (frozen(current)) {		current->state = TASK_UNINTERRUPTIBLE;		schedule();	}	pr_debug("%s left refrigerator\n", current->comm);	current->state = save;} static inline void freeze_process(struct task_struct *p){	unsigned long flags; 	if (!freezing(p)) {		freeze(p);		spin_lock_irqsave(&p->sighand->siglock, flags);		signal_wake_up(p, 0);		spin_unlock_irqrestore(&p->sighand->siglock, flags);	}} static void cancel_freezing(struct task_struct *p){	unsigned long flags; 	if (freezing(p)) {		pr_debug("  clean up: %s\n", p->comm);		do_not_freeze(p);		spin_lock_irqsave(&p->sighand->siglock, flags);		recalc_sigpending_tsk(p);		spin_unlock_irqrestore(&p->sighand->siglock, flags);	}} /* 0 = success, else # of processes that we failed to stop */int freeze_processes(void){	int todo, nr_user, user_frozen;	unsigned long start_time;	struct task_struct *g, *p; 	printk( "Stopping tasks: " );	start_time = jiffies;	user_frozen = 0;	do {		nr_user = todo = 0;		read_lock(&tasklist_lock);		do_each_thread(g, p) {			if (!freezeable(p))				continue;			if (frozen(p))				continue;			if (p->state == TASK_TRACED && frozen(p->parent)) {				cancel_freezing(p);				continue;			}			if (p->mm && !(p->flags & PF_BORROWED_MM)) {				/* The task is a user-space one.				 * Freeze it unless there's a vfork completion				 * pending				 */				if (!p->vfork_done)					freeze_process(p);				nr_user++;			} else {				/* Freeze only if the user space is frozen */				if (user_frozen)					freeze_process(p);				todo++;			}		} while_each_thread(g, p);		read_unlock(&tasklist_lock);		todo += nr_user;		if (!user_frozen && !nr_user) {			sys_sync();			start_time = jiffies;		}		user_frozen = !nr_user;		yield();			/* Yield is okay here */		if (todo && time_after(jiffies, start_time + TIMEOUT))			break;	} while(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.	 */	if (todo) {		printk( "\n" );		printk(KERN_ERR " stopping tasks timed out "			"after %d seconds (%d tasks remaining):\n",			TIMEOUT / HZ, todo);		read_lock(&tasklist_lock);		do_each_thread(g, p) {			if (freezeable(p) && !frozen(p))				printk(KERN_ERR "  %s\n", p->comm);			cancel_freezing(p);		} while_each_thread(g, p);		read_unlock(&tasklist_lock);		return todo;	} 	printk( "|\n" );	BUG_ON(in_atomic());	return 0;} void thaw_processes(void){	struct task_struct *g, *p; 	printk( "Restarting tasks..." );	read_lock(&tasklist_lock);	do_each_thread(g, p) {		if (!freezeable(p))			continue;		if (!thaw_process(p))			printk(KERN_INFO " Strange, %s not stopped\n", p->comm );	} while_each_thread(g, p); 	read_unlock(&tasklist_lock);	schedule();	printk( " done\n" );} EXPORT_SYMBOL(refrigerator);