![Rafael J. Wysocki](/assets/img/avatar_default.png)
Fix oops caused by 'cat /dev/snapshot', reported by Arkadiusz Miskiewicz, and make it impossible to thaw tasks with the help of the swsusp userland interface while there is a snapshot image ready to save. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
476 lines
9.3 KiB
C
476 lines
9.3 KiB
C
/*
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* linux/kernel/power/user.c
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*
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* This file provides the user space interface for software suspend/resume.
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*
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* Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
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*
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* This file is released under the GPLv2.
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*
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*/
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#include <linux/suspend.h>
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#include <linux/syscalls.h>
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#include <linux/reboot.h>
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#include <linux/string.h>
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#include <linux/device.h>
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#include <linux/miscdevice.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/pm.h>
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#include <linux/fs.h>
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#include <linux/console.h>
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#include <linux/cpu.h>
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#include <linux/freezer.h>
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#include <asm/uaccess.h>
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#include "power.h"
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#define SNAPSHOT_MINOR 231
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static struct snapshot_data {
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struct snapshot_handle handle;
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int swap;
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int mode;
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char frozen;
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char ready;
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char platform_suspend;
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} snapshot_state;
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atomic_t snapshot_device_available = ATOMIC_INIT(1);
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static int snapshot_open(struct inode *inode, struct file *filp)
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{
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struct snapshot_data *data;
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if (!atomic_add_unless(&snapshot_device_available, -1, 0))
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return -EBUSY;
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if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
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atomic_inc(&snapshot_device_available);
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return -ENOSYS;
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}
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if(create_basic_memory_bitmaps()) {
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atomic_inc(&snapshot_device_available);
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return -ENOMEM;
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}
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nonseekable_open(inode, filp);
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data = &snapshot_state;
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filp->private_data = data;
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memset(&data->handle, 0, sizeof(struct snapshot_handle));
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if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
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data->swap = swsusp_resume_device ?
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swap_type_of(swsusp_resume_device, 0, NULL) : -1;
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data->mode = O_RDONLY;
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} else {
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data->swap = -1;
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data->mode = O_WRONLY;
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}
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data->frozen = 0;
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data->ready = 0;
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data->platform_suspend = 0;
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return 0;
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}
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static int snapshot_release(struct inode *inode, struct file *filp)
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{
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struct snapshot_data *data;
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swsusp_free();
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free_basic_memory_bitmaps();
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data = filp->private_data;
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free_all_swap_pages(data->swap);
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if (data->frozen) {
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mutex_lock(&pm_mutex);
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thaw_processes();
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mutex_unlock(&pm_mutex);
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}
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atomic_inc(&snapshot_device_available);
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return 0;
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}
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static ssize_t snapshot_read(struct file *filp, char __user *buf,
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size_t count, loff_t *offp)
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{
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struct snapshot_data *data;
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ssize_t res;
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data = filp->private_data;
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if (!data->ready)
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return -ENODATA;
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res = snapshot_read_next(&data->handle, count);
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if (res > 0) {
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if (copy_to_user(buf, data_of(data->handle), res))
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res = -EFAULT;
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else
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*offp = data->handle.offset;
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}
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return res;
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}
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static ssize_t snapshot_write(struct file *filp, const char __user *buf,
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size_t count, loff_t *offp)
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{
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struct snapshot_data *data;
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ssize_t res;
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data = filp->private_data;
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res = snapshot_write_next(&data->handle, count);
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if (res > 0) {
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if (copy_from_user(data_of(data->handle), buf, res))
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res = -EFAULT;
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else
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*offp = data->handle.offset;
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}
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return res;
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}
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static inline int platform_prepare(void)
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{
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int error = 0;
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if (hibernation_ops)
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error = hibernation_ops->prepare();
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return error;
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}
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static inline void platform_finish(void)
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{
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if (hibernation_ops)
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hibernation_ops->finish();
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}
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static inline int snapshot_suspend(int platform_suspend)
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{
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int error;
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mutex_lock(&pm_mutex);
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/* Free memory before shutting down devices. */
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error = swsusp_shrink_memory();
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if (error)
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goto Finish;
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if (platform_suspend) {
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error = platform_prepare();
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if (error)
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goto Finish;
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}
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suspend_console();
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error = device_suspend(PMSG_FREEZE);
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if (error)
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goto Resume_devices;
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error = disable_nonboot_cpus();
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if (!error) {
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in_suspend = 1;
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error = swsusp_suspend();
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}
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enable_nonboot_cpus();
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Resume_devices:
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if (platform_suspend)
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platform_finish();
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device_resume();
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resume_console();
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Finish:
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mutex_unlock(&pm_mutex);
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return error;
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}
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static inline int snapshot_restore(int platform_suspend)
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{
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int error;
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mutex_lock(&pm_mutex);
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pm_prepare_console();
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if (platform_suspend) {
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error = platform_prepare();
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if (error)
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goto Finish;
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}
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suspend_console();
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error = device_suspend(PMSG_PRETHAW);
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if (error)
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goto Resume_devices;
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error = disable_nonboot_cpus();
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if (!error)
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error = swsusp_resume();
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enable_nonboot_cpus();
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Resume_devices:
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if (platform_suspend)
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platform_finish();
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device_resume();
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resume_console();
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Finish:
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pm_restore_console();
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mutex_unlock(&pm_mutex);
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return error;
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}
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static int snapshot_ioctl(struct inode *inode, struct file *filp,
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unsigned int cmd, unsigned long arg)
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{
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int error = 0;
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struct snapshot_data *data;
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loff_t avail;
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sector_t offset;
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if (_IOC_TYPE(cmd) != SNAPSHOT_IOC_MAGIC)
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return -ENOTTY;
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if (_IOC_NR(cmd) > SNAPSHOT_IOC_MAXNR)
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return -ENOTTY;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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data = filp->private_data;
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switch (cmd) {
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case SNAPSHOT_FREEZE:
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if (data->frozen)
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break;
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mutex_lock(&pm_mutex);
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if (freeze_processes()) {
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thaw_processes();
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error = -EBUSY;
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}
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mutex_unlock(&pm_mutex);
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if (!error)
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data->frozen = 1;
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break;
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case SNAPSHOT_UNFREEZE:
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if (!data->frozen || data->ready)
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break;
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mutex_lock(&pm_mutex);
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thaw_processes();
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mutex_unlock(&pm_mutex);
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data->frozen = 0;
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break;
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case SNAPSHOT_ATOMIC_SNAPSHOT:
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if (data->mode != O_RDONLY || !data->frozen || data->ready) {
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error = -EPERM;
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break;
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}
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error = snapshot_suspend(data->platform_suspend);
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if (!error)
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error = put_user(in_suspend, (unsigned int __user *)arg);
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if (!error)
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data->ready = 1;
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break;
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case SNAPSHOT_ATOMIC_RESTORE:
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snapshot_write_finalize(&data->handle);
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if (data->mode != O_WRONLY || !data->frozen ||
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!snapshot_image_loaded(&data->handle)) {
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error = -EPERM;
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break;
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}
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error = snapshot_restore(data->platform_suspend);
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break;
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case SNAPSHOT_FREE:
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swsusp_free();
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memset(&data->handle, 0, sizeof(struct snapshot_handle));
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data->ready = 0;
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break;
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case SNAPSHOT_SET_IMAGE_SIZE:
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image_size = arg;
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break;
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case SNAPSHOT_AVAIL_SWAP:
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avail = count_swap_pages(data->swap, 1);
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avail <<= PAGE_SHIFT;
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error = put_user(avail, (loff_t __user *)arg);
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break;
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case SNAPSHOT_GET_SWAP_PAGE:
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if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
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error = -ENODEV;
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break;
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}
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offset = alloc_swapdev_block(data->swap);
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if (offset) {
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offset <<= PAGE_SHIFT;
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error = put_user(offset, (sector_t __user *)arg);
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} else {
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error = -ENOSPC;
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}
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break;
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case SNAPSHOT_FREE_SWAP_PAGES:
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if (data->swap < 0 || data->swap >= MAX_SWAPFILES) {
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error = -ENODEV;
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break;
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}
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free_all_swap_pages(data->swap);
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break;
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case SNAPSHOT_SET_SWAP_FILE:
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if (!swsusp_swap_in_use()) {
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/*
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* User space encodes device types as two-byte values,
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* so we need to recode them
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*/
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if (old_decode_dev(arg)) {
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data->swap = swap_type_of(old_decode_dev(arg),
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0, NULL);
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if (data->swap < 0)
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error = -ENODEV;
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} else {
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data->swap = -1;
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error = -EINVAL;
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}
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} else {
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error = -EPERM;
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}
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break;
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case SNAPSHOT_S2RAM:
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if (!pm_ops) {
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error = -ENOSYS;
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break;
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}
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if (!data->frozen) {
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error = -EPERM;
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break;
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}
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if (!mutex_trylock(&pm_mutex)) {
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error = -EBUSY;
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break;
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}
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if (pm_ops->prepare) {
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error = pm_ops->prepare(PM_SUSPEND_MEM);
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if (error)
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goto OutS3;
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}
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/* Put devices to sleep */
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suspend_console();
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error = device_suspend(PMSG_SUSPEND);
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if (error) {
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printk(KERN_ERR "Failed to suspend some devices.\n");
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} else {
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error = disable_nonboot_cpus();
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if (!error) {
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/* Enter S3, system is already frozen */
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suspend_enter(PM_SUSPEND_MEM);
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enable_nonboot_cpus();
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}
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/* Wake up devices */
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device_resume();
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}
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resume_console();
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if (pm_ops->finish)
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pm_ops->finish(PM_SUSPEND_MEM);
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OutS3:
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mutex_unlock(&pm_mutex);
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break;
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case SNAPSHOT_PMOPS:
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error = -EINVAL;
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switch (arg) {
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case PMOPS_PREPARE:
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if (hibernation_ops) {
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data->platform_suspend = 1;
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error = 0;
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} else {
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error = -ENOSYS;
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}
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break;
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case PMOPS_ENTER:
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if (data->platform_suspend) {
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kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
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error = hibernation_ops->enter();
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}
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break;
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case PMOPS_FINISH:
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if (data->platform_suspend)
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error = 0;
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break;
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default:
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printk(KERN_ERR "SNAPSHOT_PMOPS: invalid argument %ld\n", arg);
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}
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break;
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case SNAPSHOT_SET_SWAP_AREA:
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if (swsusp_swap_in_use()) {
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error = -EPERM;
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} else {
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struct resume_swap_area swap_area;
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dev_t swdev;
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error = copy_from_user(&swap_area, (void __user *)arg,
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sizeof(struct resume_swap_area));
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if (error) {
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error = -EFAULT;
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break;
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}
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/*
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* User space encodes device types as two-byte values,
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* so we need to recode them
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*/
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swdev = old_decode_dev(swap_area.dev);
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if (swdev) {
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offset = swap_area.offset;
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data->swap = swap_type_of(swdev, offset, NULL);
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if (data->swap < 0)
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error = -ENODEV;
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} else {
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data->swap = -1;
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error = -EINVAL;
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}
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}
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break;
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default:
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error = -ENOTTY;
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}
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return error;
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}
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static const struct file_operations snapshot_fops = {
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.open = snapshot_open,
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.release = snapshot_release,
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.read = snapshot_read,
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.write = snapshot_write,
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.llseek = no_llseek,
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.ioctl = snapshot_ioctl,
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};
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static struct miscdevice snapshot_device = {
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.minor = SNAPSHOT_MINOR,
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.name = "snapshot",
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.fops = &snapshot_fops,
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};
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static int __init snapshot_device_init(void)
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{
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return misc_register(&snapshot_device);
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};
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device_initcall(snapshot_device_init);
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