linux/kernel/power/process.c

// SPDX-License-Identifier: GPL-2.0
/*
 * drivers/power/process.c - Functions for starting/stopping processes on
 *                           suspend transitions.
 *
 * Originally from swsusp.
 */

#include <linux/interrupt.h>
#include <linux/oom.h>
#include <linux/suspend.h>
#include <linux/module.h>
#include <linux/sched/debug.h>
#include <linux/sched/task.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>
#include <linux/delay.h>
#include <linux/workqueue.h>
#include <linux/kmod.h>
#include <trace/events/power.h>
#include <linux/cpuset.h>

/*
 * Timeout for stopping processes
 */
unsigned int __read_mostly freeze_timeout_msecs = …;

static int try_to_freeze_tasks(bool user_only)
{ … }

/**
 * freeze_processes - Signal user space processes to enter the refrigerator.
 * The current thread will not be frozen.  The same process that calls
 * freeze_processes must later call thaw_processes.
 *
 * On success, returns 0.  On failure, -errno and system is fully thawed.
 */
int freeze_processes(void)
{ … }

/**
 * 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)
{ … }

void thaw_processes(void)
{ … }

void thaw_kernel_threads(void)
{ … }