[linux-2.6-block.git] / kernel / power / user.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/kernel/power/user.c
 *
 * This file provides the user space interface for software suspend/resume.
 *
 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
 */

#include <linux/suspend.h>
#include <linux/reboot.h>
#include <linux/string.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/fs.h>
#include <linux/compat.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/freezer.h>

#include <linux/uaccess.h>

#include "power.h"

static bool need_wait;

static struct snapshot_data {
	struct snapshot_handle handle;
	int swap;
	int mode;
	bool frozen;
	bool ready;
	bool platform_support;
	bool free_bitmaps;
	dev_t dev;
} snapshot_state;

int is_hibernate_resume_dev(dev_t dev)
{
	return hibernation_available() && snapshot_state.dev == dev;
}

static int snapshot_open(struct inode *inode, struct file *filp)
{
	struct snapshot_data *data;
	unsigned int sleep_flags;
	int error;

	if (!hibernation_available())
		return -EPERM;

	sleep_flags = lock_system_sleep();

	if (!hibernate_acquire()) {
		error = -EBUSY;
		goto Unlock;
	}

	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
		hibernate_release();
		error = -ENOSYS;
		goto Unlock;
	}
	nonseekable_open(inode, filp);
	data = &snapshot_state;
	filp->private_data = data;
	memset(&data->handle, 0, sizeof(struct snapshot_handle));
	if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
		/* Hibernating.  The image device should be accessible. */
		data->swap = swap_type_of(swsusp_resume_device, 0);
		data->mode = O_RDONLY;
		data->free_bitmaps = false;
		error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
	} else {
		/*
		 * Resuming.  We may need to wait for the image device to
		 * appear.
		 */
		need_wait = true;

		data->swap = -1;
		data->mode = O_WRONLY;
		error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
		if (!error) {
			error = create_basic_memory_bitmaps();
			data->free_bitmaps = !error;
		}
	}
	if (error)
		hibernate_release();

	data->frozen = false;
	data->ready = false;
	data->platform_support = false;
	data->dev = 0;

 Unlock:
	unlock_system_sleep(sleep_flags);

	return error;
}

static int snapshot_release(struct inode *inode, struct file *filp)
{
	struct snapshot_data *data;
	unsigned int sleep_flags;

	sleep_flags = lock_system_sleep();

	swsusp_free();
	data = filp->private_data;
	data->dev = 0;
	free_all_swap_pages(data->swap);
	if (data->frozen) {
		pm_restore_gfp_mask();
		free_basic_memory_bitmaps();
		thaw_processes();
	} else if (data->free_bitmaps) {
		free_basic_memory_bitmaps();
	}
	pm_notifier_call_chain(data->mode == O_RDONLY ?
			PM_POST_HIBERNATION : PM_POST_RESTORE);
	hibernate_release();

	unlock_system_sleep(sleep_flags);

	return 0;
}

static ssize_t snapshot_read(struct file *filp, char __user *buf,
                             size_t count, loff_t *offp)
{
	loff_t pg_offp = *offp & ~PAGE_MASK;
	struct snapshot_data *data;
	unsigned int sleep_flags;
	ssize_t res;

	sleep_flags = lock_system_sleep();

	data = filp->private_data;
	if (!data->ready) {
		res = -ENODATA;
		goto Unlock;
	}
	if (!pg_offp) { /* on page boundary? */
		res = snapshot_read_next(&data->handle);
		if (res <= 0)
			goto Unlock;
	} else {
		res = PAGE_SIZE - pg_offp;
	}

	res = simple_read_from_buffer(buf, count, &pg_offp,
			data_of(data->handle), res);
	if (res > 0)
		*offp += res;

 Unlock:
	unlock_system_sleep(sleep_flags);

	return res;
}

static ssize_t snapshot_write(struct file *filp, const char __user *buf,
                              size_t count, loff_t *offp)
{
	loff_t pg_offp = *offp & ~PAGE_MASK;
	struct snapshot_data *data;
	unsigned long sleep_flags;
	ssize_t res;

	if (need_wait) {
		wait_for_device_probe();
		need_wait = false;
	}

	sleep_flags = lock_system_sleep();

	data = filp->private_data;

	if (!pg_offp) {
		res = snapshot_write_next(&data->handle);
		if (res <= 0)
			goto unlock;
	} else {
		res = PAGE_SIZE;
	}

	if (!data_of(data->handle)) {
		res = -EINVAL;
		goto unlock;
	}

	res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
			buf, count);
	if (res > 0)
		*offp += res;
unlock:
	unlock_system_sleep(sleep_flags);

	return res;
}

struct compat_resume_swap_area {
	compat_loff_t offset;
	u32 dev;
} __packed;

static int snapshot_set_swap_area(struct snapshot_data *data,
		void __user *argp)
{
	sector_t offset;
	dev_t swdev;

	if (swsusp_swap_in_use())
		return -EPERM;

	if (in_compat_syscall()) {
		struct compat_resume_swap_area swap_area;

		if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
			return -EFAULT;
		swdev = new_decode_dev(swap_area.dev);
		offset = swap_area.offset;
	} else {
		struct resume_swap_area swap_area;

		if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
			return -EFAULT;
		swdev = new_decode_dev(swap_area.dev);
		offset = swap_area.offset;
	}

	/*
	 * User space encodes device types as two-byte values,
	 * so we need to recode them
	 */
	data->swap = swap_type_of(swdev, offset);
	if (data->swap < 0)
		return swdev ? -ENODEV : -EINVAL;
	data->dev = swdev;
	return 0;
}

static long snapshot_ioctl(struct file *filp, unsigned int cmd,
							unsigned long arg)
{
	int error = 0;
	struct snapshot_data *data;
	loff_t size;
	sector_t offset;

	if (need_wait) {
		wait_for_device_probe();
		need_wait = false;
	}

	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
		return -ENOTTY;
	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
		return -ENOTTY;
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	if (!mutex_trylock(&system_transition_mutex))
		return -EBUSY;

	lock_device_hotplug();
	data = filp->private_data;

	switch (cmd) {

	case SNAPSHOT_FREEZE:
		if (data->frozen)
			break;

		ksys_sync_helper();

		error = freeze_processes();
		if (error)
			break;

		error = create_basic_memory_bitmaps();
		if (error)
			thaw_processes();
		else
			data->frozen = true;

		break;

	case SNAPSHOT_UNFREEZE:
		if (!data->frozen || data->ready)
			break;
		pm_restore_gfp_mask();
		free_basic_memory_bitmaps();
		data->free_bitmaps = false;
		thaw_processes();
		data->frozen = false;
		break;

	case SNAPSHOT_CREATE_IMAGE:
		if (data->mode != O_RDONLY || !data->frozen  || data->ready) {
			error = -EPERM;
			break;
		}
		pm_restore_gfp_mask();
		error = hibernation_snapshot(data->platform_support);
		if (!error) {
			error = put_user(in_suspend, (int __user *)arg);
			data->ready = !freezer_test_done && !error;
			freezer_test_done = false;
		}
		break;

	case SNAPSHOT_ATOMIC_RESTORE:
		error = snapshot_write_finalize(&data->handle);
		if (error)
			break;
		if (data->mode != O_WRONLY || !data->frozen ||
		    !snapshot_image_loaded(&data->handle)) {
			error = -EPERM;
			break;
		}
		error = hibernation_restore(data->platform_support);
		break;

	case SNAPSHOT_FREE:
		swsusp_free();
		memset(&data->handle, 0, sizeof(struct snapshot_handle));
		data->ready = false;
		/*
		 * It is necessary to thaw kernel threads here, because
		 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
		 * SNAPSHOT_FREE.  In that case, if kernel threads were not
		 * thawed, the preallocation of memory carried out by
		 * hibernation_snapshot() might run into problems (i.e. it
		 * might fail or even deadlock).
		 */
		thaw_kernel_threads();
		break;

	case SNAPSHOT_PREF_IMAGE_SIZE:
		image_size = arg;
		break;

	case SNAPSHOT_GET_IMAGE_SIZE:
		if (!data->ready) {
			error = -ENODATA;
			break;
		}
		size = snapshot_get_image_size();
		size <<= PAGE_SHIFT;
		error = put_user(size, (loff_t __user *)arg);
		break;

	case SNAPSHOT_AVAIL_SWAP_SIZE:
		size = count_swap_pages(data->swap, 1);
		size <<= PAGE_SHIFT;
		error = put_user(size, (loff_t __user *)arg);
		break;

	case SNAPSHOT_ALLOC_SWAP_PAGE:
		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
			error = -ENODEV;
			break;
		}
		offset = alloc_swapdev_block(data->swap);
		if (offset) {
			offset <<= PAGE_SHIFT;
			error = put_user(offset, (loff_t __user *)arg);
		} else {
			error = -ENOSPC;
		}
		break;

	case SNAPSHOT_FREE_SWAP_PAGES:
		if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
			error = -ENODEV;
			break;
		}
		free_all_swap_pages(data->swap);
		break;

	case SNAPSHOT_S2RAM:
		if (!data->frozen) {
			error = -EPERM;
			break;
		}
		/*
		 * Tasks are frozen and the notifiers have been called with
		 * PM_HIBERNATION_PREPARE
		 */
		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
		data->ready = false;
		break;

	case SNAPSHOT_PLATFORM_SUPPORT:
		data->platform_support = !!arg;
		break;

	case SNAPSHOT_POWER_OFF:
		if (data->platform_support)
			error = hibernation_platform_enter();
		break;

	case SNAPSHOT_SET_SWAP_AREA:
		error = snapshot_set_swap_area(data, (void __user *)arg);
		break;

	default:
		error = -ENOTTY;

	}

	unlock_device_hotplug();
	mutex_unlock(&system_transition_mutex);

	return error;
}

#ifdef CONFIG_COMPAT
static long
snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));

	switch (cmd) {
	case SNAPSHOT_GET_IMAGE_SIZE:
	case SNAPSHOT_AVAIL_SWAP_SIZE:
	case SNAPSHOT_ALLOC_SWAP_PAGE:
	case SNAPSHOT_CREATE_IMAGE:
	case SNAPSHOT_SET_SWAP_AREA:
		return snapshot_ioctl(file, cmd,
				      (unsigned long) compat_ptr(arg));
	default:
		return snapshot_ioctl(file, cmd, arg);
	}
}
#endif /* CONFIG_COMPAT */

static const struct file_operations snapshot_fops = {
	.open = snapshot_open,
	.release = snapshot_release,
	.read = snapshot_read,
	.write = snapshot_write,
	.unlocked_ioctl = snapshot_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = snapshot_compat_ioctl,
#endif
};

static struct miscdevice snapshot_device = {
	.minor = SNAPSHOT_MINOR,
	.name = "snapshot",
	.fops = &snapshot_fops,
};

static int __init snapshot_device_init(void)
{
	return misc_register(&snapshot_device);
};

device_initcall(snapshot_device_init);
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-only
	2	/*
	3	* linux/kernel/power/user.c
	4	*
	5	* This file provides the user space interface for software suspend/resume.
	6	*
	7	* Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
	8	*/
	9
	10	#include <linux/suspend.h>
	11	#include <linux/reboot.h>
	12	#include <linux/string.h>
	13	#include <linux/device.h>
	14	#include <linux/miscdevice.h>
	15	#include <linux/mm.h>
	16	#include <linux/swap.h>
	17	#include <linux/swapops.h>
	18	#include <linux/pm.h>
	19	#include <linux/fs.h>
	20	#include <linux/compat.h>
	21	#include <linux/console.h>
	22	#include <linux/cpu.h>
	23	#include <linux/freezer.h>
	24
	25	#include <linux/uaccess.h>
	26
	27	#include "power.h"
	28
	29	static bool need_wait;
	30
	31	static struct snapshot_data {
	32	struct snapshot_handle handle;
	33	int swap;
	34	int mode;
	35	bool frozen;
	36	bool ready;
	37	bool platform_support;
	38	bool free_bitmaps;
	39	dev_t dev;
	40	} snapshot_state;
	41
	42	int is_hibernate_resume_dev(dev_t dev)
	43	{
	44	return hibernation_available() && snapshot_state.dev == dev;
	45	}
	46
	47	static int snapshot_open(struct inode inode, struct file filp)
	48	{
	49	struct snapshot_data *data;
	50	unsigned int sleep_flags;
	51	int error;
	52
	53	if (!hibernation_available())
	54	return -EPERM;
	55
	56	sleep_flags = lock_system_sleep();
	57
	58	if (!hibernate_acquire()) {
	59	error = -EBUSY;
	60	goto Unlock;
	61	}
	62
	63	if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
	64	hibernate_release();
	65	error = -ENOSYS;
	66	goto Unlock;
	67	}
	68	nonseekable_open(inode, filp);
	69	data = &snapshot_state;
	70	filp->private_data = data;
	71	memset(&data->handle, 0, sizeof(struct snapshot_handle));
	72	if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
	73	/* Hibernating. The image device should be accessible. */
	74	data->swap = swap_type_of(swsusp_resume_device, 0);
	75	data->mode = O_RDONLY;
	76	data->free_bitmaps = false;
	77	error = pm_notifier_call_chain_robust(PM_HIBERNATION_PREPARE, PM_POST_HIBERNATION);
	78	} else {
	79	/*
	80	* Resuming. We may need to wait for the image device to
	81	* appear.
	82	*/
	83	need_wait = true;
	84
	85	data->swap = -1;
	86	data->mode = O_WRONLY;
	87	error = pm_notifier_call_chain_robust(PM_RESTORE_PREPARE, PM_POST_RESTORE);
	88	if (!error) {
	89	error = create_basic_memory_bitmaps();
	90	data->free_bitmaps = !error;
	91	}
	92	}
	93	if (error)
	94	hibernate_release();
	95
	96	data->frozen = false;
	97	data->ready = false;
	98	data->platform_support = false;
	99	data->dev = 0;
	100
	101	Unlock:
	102	unlock_system_sleep(sleep_flags);
	103
	104	return error;
	105	}
	106
	107	static int snapshot_release(struct inode inode, struct file filp)
	108	{
	109	struct snapshot_data *data;
	110	unsigned int sleep_flags;
	111
	112	sleep_flags = lock_system_sleep();
	113
	114	swsusp_free();
	115	data = filp->private_data;
	116	data->dev = 0;
	117	free_all_swap_pages(data->swap);
	118	if (data->frozen) {
	119	pm_restore_gfp_mask();
	120	free_basic_memory_bitmaps();
	121	thaw_processes();
	122	} else if (data->free_bitmaps) {
	123	free_basic_memory_bitmaps();
	124	}
	125	pm_notifier_call_chain(data->mode == O_RDONLY ?
	126	PM_POST_HIBERNATION : PM_POST_RESTORE);
	127	hibernate_release();
	128
	129	unlock_system_sleep(sleep_flags);
	130
	131	return 0;
	132	}
	133
	134	static ssize_t snapshot_read(struct file filp, char __user buf,
	135	size_t count, loff_t *offp)
	136	{
	137	loff_t pg_offp = *offp & ~PAGE_MASK;
	138	struct snapshot_data *data;
	139	unsigned int sleep_flags;
	140	ssize_t res;
	141
	142	sleep_flags = lock_system_sleep();
	143
	144	data = filp->private_data;
	145	if (!data->ready) {
	146	res = -ENODATA;
	147	goto Unlock;
	148	}
	149	if (!pg_offp) { /* on page boundary? */
	150	res = snapshot_read_next(&data->handle);
	151	if (res <= 0)
	152	goto Unlock;
	153	} else {
	154	res = PAGE_SIZE - pg_offp;
	155	}
	156
	157	res = simple_read_from_buffer(buf, count, &pg_offp,
	158	data_of(data->handle), res);
	159	if (res > 0)
	160	*offp += res;
	161
	162	Unlock:
	163	unlock_system_sleep(sleep_flags);
	164
	165	return res;
	166	}
	167
	168	static ssize_t snapshot_write(struct file filp, const char __user buf,
	169	size_t count, loff_t *offp)
	170	{
	171	loff_t pg_offp = *offp & ~PAGE_MASK;
	172	struct snapshot_data *data;
	173	unsigned long sleep_flags;
	174	ssize_t res;
	175
	176	if (need_wait) {
	177	wait_for_device_probe();
	178	need_wait = false;
	179	}
	180
	181	sleep_flags = lock_system_sleep();
	182
	183	data = filp->private_data;
	184
	185	if (!pg_offp) {
	186	res = snapshot_write_next(&data->handle);
	187	if (res <= 0)
	188	goto unlock;
	189	} else {
	190	res = PAGE_SIZE;
	191	}
	192
	193	if (!data_of(data->handle)) {
	194	res = -EINVAL;
	195	goto unlock;
	196	}
	197
	198	res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp,
	199	buf, count);
	200	if (res > 0)
	201	*offp += res;
	202	unlock:
	203	unlock_system_sleep(sleep_flags);
	204
	205	return res;
	206	}
	207
	208	struct compat_resume_swap_area {
	209	compat_loff_t offset;
	210	u32 dev;
	211	} __packed;
	212
	213	static int snapshot_set_swap_area(struct snapshot_data *data,
	214	void __user *argp)
	215	{
	216	sector_t offset;
	217	dev_t swdev;
	218
	219	if (swsusp_swap_in_use())
	220	return -EPERM;
	221
	222	if (in_compat_syscall()) {
	223	struct compat_resume_swap_area swap_area;
	224
	225	if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
	226	return -EFAULT;
	227	swdev = new_decode_dev(swap_area.dev);
	228	offset = swap_area.offset;
	229	} else {
	230	struct resume_swap_area swap_area;
	231
	232	if (copy_from_user(&swap_area, argp, sizeof(swap_area)))
	233	return -EFAULT;
	234	swdev = new_decode_dev(swap_area.dev);
	235	offset = swap_area.offset;
	236	}
	237
	238	/*
	239	* User space encodes device types as two-byte values,
	240	* so we need to recode them
	241	*/
	242	data->swap = swap_type_of(swdev, offset);
	243	if (data->swap < 0)
	244	return swdev ? -ENODEV : -EINVAL;
	245	data->dev = swdev;
	246	return 0;
	247	}
	248
	249	static long snapshot_ioctl(struct file *filp, unsigned int cmd,
	250	unsigned long arg)
	251	{
	252	int error = 0;
	253	struct snapshot_data *data;
	254	loff_t size;
	255	sector_t offset;
	256
	257	if (need_wait) {
	258	wait_for_device_probe();
	259	need_wait = false;
	260	}
	261
	262	if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
	263	return -ENOTTY;
	264	if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
	265	return -ENOTTY;
	266	if (!capable(CAP_SYS_ADMIN))
	267	return -EPERM;
	268
	269	if (!mutex_trylock(&system_transition_mutex))
	270	return -EBUSY;
	271
	272	lock_device_hotplug();
	273	data = filp->private_data;
	274
	275	switch (cmd) {
	276
	277	case SNAPSHOT_FREEZE:
	278	if (data->frozen)
	279	break;
	280
	281	ksys_sync_helper();
	282
	283	error = freeze_processes();
	284	if (error)
	285	break;
	286
	287	error = create_basic_memory_bitmaps();
	288	if (error)
	289	thaw_processes();
	290	else
	291	data->frozen = true;
	292
	293	break;
	294
	295	case SNAPSHOT_UNFREEZE:
	296	if (!data->frozen \|\| data->ready)
	297	break;
	298	pm_restore_gfp_mask();
	299	free_basic_memory_bitmaps();
	300	data->free_bitmaps = false;
	301	thaw_processes();
	302	data->frozen = false;
	303	break;
	304
	305	case SNAPSHOT_CREATE_IMAGE:
	306	if (data->mode != O_RDONLY \|\| !data->frozen \|\| data->ready) {
	307	error = -EPERM;
	308	break;
	309	}
	310	pm_restore_gfp_mask();
	311	error = hibernation_snapshot(data->platform_support);
	312	if (!error) {
	313	error = put_user(in_suspend, (int __user *)arg);
	314	data->ready = !freezer_test_done && !error;
	315	freezer_test_done = false;
	316	}
	317	break;
	318
	319	case SNAPSHOT_ATOMIC_RESTORE:
	320	error = snapshot_write_finalize(&data->handle);
	321	if (error)
	322	break;
	323	if (data->mode != O_WRONLY \|\| !data->frozen \|\|
	324	!snapshot_image_loaded(&data->handle)) {
	325	error = -EPERM;
	326	break;
	327	}
	328	error = hibernation_restore(data->platform_support);
	329	break;
	330
	331	case SNAPSHOT_FREE:
	332	swsusp_free();
	333	memset(&data->handle, 0, sizeof(struct snapshot_handle));
	334	data->ready = false;
	335	/*
	336	* It is necessary to thaw kernel threads here, because
	337	* SNAPSHOT_CREATE_IMAGE may be invoked directly after
	338	* SNAPSHOT_FREE. In that case, if kernel threads were not
	339	* thawed, the preallocation of memory carried out by
	340	* hibernation_snapshot() might run into problems (i.e. it
	341	* might fail or even deadlock).
	342	*/
	343	thaw_kernel_threads();
	344	break;
	345
	346	case SNAPSHOT_PREF_IMAGE_SIZE:
	347	image_size = arg;
	348	break;
	349
	350	case SNAPSHOT_GET_IMAGE_SIZE:
	351	if (!data->ready) {
	352	error = -ENODATA;
	353	break;
	354	}
	355	size = snapshot_get_image_size();
	356	size <<= PAGE_SHIFT;
	357	error = put_user(size, (loff_t __user *)arg);
	358	break;
	359
	360	case SNAPSHOT_AVAIL_SWAP_SIZE:
	361	size = count_swap_pages(data->swap, 1);
	362	size <<= PAGE_SHIFT;
	363	error = put_user(size, (loff_t __user *)arg);
	364	break;
	365
	366	case SNAPSHOT_ALLOC_SWAP_PAGE:
	367	if (data->swap < 0 \|\| data->swap >= MAX_SWAPFILES) {
	368	error = -ENODEV;
	369	break;
	370	}
	371	offset = alloc_swapdev_block(data->swap);
	372	if (offset) {
	373	offset <<= PAGE_SHIFT;
	374	error = put_user(offset, (loff_t __user *)arg);
	375	} else {
	376	error = -ENOSPC;
	377	}
	378	break;
	379
	380	case SNAPSHOT_FREE_SWAP_PAGES:
	381	if (data->swap < 0 \|\| data->swap >= MAX_SWAPFILES) {
	382	error = -ENODEV;
	383	break;
	384	}
	385	free_all_swap_pages(data->swap);
	386	break;
	387
	388	case SNAPSHOT_S2RAM:
	389	if (!data->frozen) {
	390	error = -EPERM;
	391	break;
	392	}
	393	/*
	394	* Tasks are frozen and the notifiers have been called with
	395	* PM_HIBERNATION_PREPARE
	396	*/
	397	error = suspend_devices_and_enter(PM_SUSPEND_MEM);
	398	data->ready = false;
	399	break;
	400
	401	case SNAPSHOT_PLATFORM_SUPPORT:
	402	data->platform_support = !!arg;
	403	break;
	404
	405	case SNAPSHOT_POWER_OFF:
	406	if (data->platform_support)
	407	error = hibernation_platform_enter();
	408	break;
	409
	410	case SNAPSHOT_SET_SWAP_AREA:
	411	error = snapshot_set_swap_area(data, (void __user *)arg);
	412	break;
	413
	414	default:
	415	error = -ENOTTY;
	416
	417	}
	418
	419	unlock_device_hotplug();
	420	mutex_unlock(&system_transition_mutex);
	421
	422	return error;
	423	}
	424
	425	#ifdef CONFIG_COMPAT
	426	static long
	427	snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	428	{
	429	BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
	430
	431	switch (cmd) {
	432	case SNAPSHOT_GET_IMAGE_SIZE:
	433	case SNAPSHOT_AVAIL_SWAP_SIZE:
	434	case SNAPSHOT_ALLOC_SWAP_PAGE:
	435	case SNAPSHOT_CREATE_IMAGE:
	436	case SNAPSHOT_SET_SWAP_AREA:
	437	return snapshot_ioctl(file, cmd,
	438	(unsigned long) compat_ptr(arg));
	439	default:
	440	return snapshot_ioctl(file, cmd, arg);
	441	}
	442	}
	443	#endif /* CONFIG_COMPAT */
	444
	445	static const struct file_operations snapshot_fops = {
	446	.open = snapshot_open,
	447	.release = snapshot_release,
	448	.read = snapshot_read,
	449	.write = snapshot_write,
	450	.unlocked_ioctl = snapshot_ioctl,
	451	#ifdef CONFIG_COMPAT
	452	.compat_ioctl = snapshot_compat_ioctl,
	453	#endif
	454	};
	455
	456	static struct miscdevice snapshot_device = {
	457	.minor = SNAPSHOT_MINOR,
	458	.name = "snapshot",
	459	.fops = &snapshot_fops,
	460	};
	461
	462	static int __init snapshot_device_init(void)
	463	{
	464	return misc_register(&snapshot_device);
	465	};
	466
	467	device_initcall(snapshot_device_init);