process.c

/*
 * 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) ||
	    (p->state == TASK_TRACED))
		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);
	}
}

/* 0 = success, else # of processes that we failed to stop */