/* * drivers/power/process.c - Functions for starting/stopping processes on  *                           suspend transitions. * * Originally from swsusp. */  #undef DEBUG #include <linux/interrupt.h>#include <linux/oom.h>#include <linux/suspend.h>#include <linux/module.h>#include <linux/syscalls.h>#include <linux/freezer.h>#include <linux/delay.h>#include <linux/workqueue.h>#include <linux/kmod.h> /*  * Timeout for stopping processes */#define TIMEOUT	(20 * HZ) static int try_to_freeze_tasks(bool user_only){	struct task_struct *g, *p;	unsigned long end_time;	unsigned int todo;	bool wq_busy = false;	struct timeval start, end;	u64 elapsed_csecs64;	unsigned int elapsed_csecs;	bool wakeup = false; 	do_gettimeofday(&start); 	end_time = jiffies + TIMEOUT; 	if (!user_only)		freeze_workqueues_begin(); 	while (true) {		todo = 0;		read_lock(&tasklist_lock);		do_each_thread(g, p) {			if (p == current || !freeze_task(p))				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.			 *			 * Because freeze_task() goes through p's scheduler lock, it's			 * guaranteed that TASK_STOPPED/TRACED -> TASK_RUNNING			 * transition can't race with task state testing here.			 */			if (!task_is_stopped_or_traced(p) &&			    !freezer_should_skip(p))				todo++;		} while_each_thread(g, p);		read_unlock(&tasklist_lock); 		if (!user_only) {			wq_busy = freeze_workqueues_busy();			todo += wq_busy;		} 		if (!todo || time_after(jiffies, end_time))			break; 		if (pm_wakeup_pending()) {			wakeup = true;			break;		} 		/*		 * We need to retry, but first give the freezing tasks some		 * time to enter the regrigerator.		 */		msleep(10);	} 	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) {		printk("\n");		printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "		       "(%d tasks refusing to freeze, wq_busy=%d):\n",		       wakeup ? "aborted" : "failed",		       elapsed_csecs / 100, elapsed_csecs % 100,		       todo - wq_busy, wq_busy); 		if (!wakeup) {			read_lock(&tasklist_lock);			do_each_thread(g, p) {				if (p != current && !freezer_should_skip(p)				    && freezing(p) && !frozen(p))					sched_show_task(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 - Signal user space processes to enter the refrigerator. * * On success, returns 0.  On failure, -errno and system is fully thawed. */int freeze_processes(void){	int error; 	error = __usermodehelper_disable(UMH_FREEZING);	if (error)		return error; 	if (!pm_freezing)		atomic_inc(&system_freezing_cnt); 	printk("Freezing user space processes ... ");	pm_freezing = true;	error = try_to_freeze_tasks(true);	if (!error) {		printk("done.");		__usermodehelper_set_disable_depth(UMH_DISABLED);		oom_killer_disable();	}	printk("\n");	BUG_ON(in_atomic()); 	if (error)		thaw_processes();	return error;} /** * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator. * * On success, returns 0.  On failure, -errno and only the kernel threads are * thawed, so as to give a chance to the caller to do additional cleanups * (if any) before thawing the userspace tasks. So, it is the responsibility * of the caller to thaw the userspace tasks, when the time is right. */int freeze_kernel_threads(void){	int error; 	printk("Freezing remaining freezable tasks ... ");	pm_nosig_freezing = true;	error = try_to_freeze_tasks(false);	if (!error)		printk("done."); 	printk("\n");	BUG_ON(in_atomic()); 	if (error)		thaw_kernel_threads();	return error;} void thaw_processes(void){	struct task_struct *g, *p; 	if (pm_freezing)		atomic_dec(&system_freezing_cnt);	pm_freezing = false;	pm_nosig_freezing = false; 	oom_killer_enable(); 	printk("Restarting tasks ... "); 	thaw_workqueues(); 	read_lock(&tasklist_lock);	do_each_thread(g, p) {		__thaw_task(p);	} while_each_thread(g, p);	read_unlock(&tasklist_lock); 	usermodehelper_enable(); 	schedule();	printk("done.\n");} void thaw_kernel_threads(void){	struct task_struct *g, *p; 	pm_nosig_freezing = false;	printk("Restarting kernel threads ... "); 	thaw_workqueues(); 	read_lock(&tasklist_lock);	do_each_thread(g, p) {		if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))			__thaw_task(p);	} while_each_thread(g, p);	read_unlock(&tasklist_lock); 	schedule();	printk("done.\n");}