path: root/kernel/power/main.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * kernel/power/main.c - PM subsystem core functionality.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 */

#include <linux/acpi.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/pm-trace.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/suspend.h>
#include <linux/syscalls.h>
#include <linux/pm_runtime.h>

#include "power.h"

#ifdef CONFIG_PM_SLEEP
/*
 * The following functions are used by the suspend/hibernate code to temporarily
 * change gfp_allowed_mask in order to avoid using I/O during memory allocations
 * while devices are suspended.  To avoid races with the suspend/hibernate code,
 * they should always be called with system_transition_mutex held
 * (gfp_allowed_mask also should only be modified with system_transition_mutex
 * held, unless the suspend/hibernate code is guaranteed not to run in parallel
 * with that modification).
 */
static unsigned int saved_gfp_count;
static gfp_t saved_gfp_mask;

void pm_restore_gfp_mask(void)
{
	WARN_ON(!mutex_is_locked(&system_transition_mutex));

	if (WARN_ON(!saved_gfp_count) || --saved_gfp_count)
		return;

	gfp_allowed_mask = saved_gfp_mask;
	saved_gfp_mask = 0;

	pm_pr_dbg("GFP mask restored\n");
}

void pm_restrict_gfp_mask(void)
{
	WARN_ON(!mutex_is_locked(&system_transition_mutex));

	if (saved_gfp_count++) {
		WARN_ON((saved_gfp_mask & ~(__GFP_IO | __GFP_FS)) != gfp_allowed_mask);
		return;
	}

	saved_gfp_mask = gfp_allowed_mask;
	gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);

	pm_pr_dbg("GFP mask restricted\n");
}

unsigned int lock_system_sleep(void)
{
	unsigned int flags = current->flags;
	current->flags |= PF_NOFREEZE;
	mutex_lock(&system_transition_mutex);
	return flags;
}
EXPORT_SYMBOL_GPL(lock_system_sleep);

void unlock_system_sleep(unsigned int flags)
{
	if (!(flags & PF_NOFREEZE))
		current->flags &= ~PF_NOFREEZE;
	mutex_unlock(&system_transition_mutex);
}
EXPORT_SYMBOL_GPL(unlock_system_sleep);

void ksys_sync_helper(void)
{
	ktime_t start;
	long elapsed_msecs;

	start = ktime_get();
	ksys_sync();
	elapsed_msecs = ktime_to_ms(ktime_sub(ktime_get(), start));
	pr_info("Filesystems sync: %ld.%03ld seconds\n",
		elapsed_msecs / MSEC_PER_SEC, elapsed_msecs % MSEC_PER_SEC);
}
EXPORT_SYMBOL_GPL(ksys_sync_helper);

/* Routines for PM-transition notifications */

static BLOCKING_NOTIFIER_HEAD(pm_chain_head);

int register_pm_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&pm_chain_head, nb);
}
EXPORT_SYMBOL_GPL(register_pm_notifier);

int unregister_pm_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_unregister(&pm_chain_head, nb);
}
EXPORT_SYMBOL_GPL(unregister_pm_notifier);

int pm_notifier_call_chain_robust(unsigned long val_up, unsigned long val_down)
{
	int ret;

	ret = blocking_notifier_call_chain_robust(&pm_chain_head, val_up, val_down, NULL);

	return notifier_to_errno(ret);
}

int pm_notifier_call_chain(unsigned long val)
{
	return blocking_notifier_call_chain(&pm_chain_head, val, NULL);
}

/* If set, devices may be suspended and resumed asynchronously. */
int pm_async_enabled = 1;

static int __init pm_async_setup(char *str)
{
	if (!strcmp(str, "off"))
		pm_async_enabled = 0;
	return 1;
}
__setup("pm_async=", pm_async_setup);

static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
			     char *buf)
{
	return sysfs_emit(buf, "%d\n", pm_async_enabled);
}

static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
			      const char *