2 files changed, 87 insertions, 81 deletions

diff --git a/kernel/power/process.c b/kernel/power/process.c
index f1d0b345c9ba..5fb87652f214 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -19,9 +19,6 @@
  */
 #define TIMEOUT (20 * HZ)
 
-#define FREEZER_KERNEL_THREADS 0
-#define FREEZER_USER_SPACE 1
-
 static inline int freezeable(struct task_struct * p)
 {
         if ((p == current) ||
@@ -84,63 +81,53 @@ static void fake_signal_wake_up(struct task_struct *p)
         spin_unlock_irqrestore(&p->sighand->siglock, flags);
 }
 
-static int has_mm(struct task_struct *p)
+static inline bool should_send_signal(struct task_struct *p)
 {
-        return (p->mm && !(p->flags & PF_BORROWED_MM));
+        return !(p->flags & PF_FREEZER_NOSIG);
 }
 
 /**
  *      freeze_task - send a freeze request to given task
  *      @p: task to send the request to
- *      @with_mm_only: if set, the request will only be sent if the task has its
- *              own mm
- *      Return value: 0, if @with_mm_only is set and the task has no mm of its
- *              own or the task is frozen, 1, otherwise
+ *      @sig_only: if set, the request will only be sent if the task has the
+ *              PF_FREEZER_NOSIG flag unset
+ *      Return value: 'false', if @sig_only is set and the task has
+ *              PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
  *
- *      The freeze request is sent by seting the tasks's TIF_FREEZE flag and
+ *      The freeze request is sent by setting the tasks's TIF_FREEZE flag and
  *      either sending a fake signal to it or waking it up, depending on whether
- *      or not it has its own mm (ie. it is a user land task).  If @with_mm_only
- *      is set and the task has no mm of its own (ie. it is a kernel thread),
- *      its TIF_FREEZE flag should not be set.
- *
- *      The task_lock() is necessary to prevent races with exit_mm() or
- *      use_mm()/unuse_mm() from occuring.
+ *      or not it has PF_FREEZER_NOSIG set.  If @sig_only is set and the task
+ *      has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
+ *      TIF_FREEZE flag will not be set.
  */
-static int freeze_task(struct task_struct *p, int with_mm_only)
+static bool freeze_task(struct task_struct *p, bool sig_only)
 {
-        int ret = 1;
+        /*
+         * We first check if the task is freezing and next if it has already
+         * been frozen to avoid the race with frozen_process() which first marks
+         * the task as frozen and next clears its TIF_FREEZE.
+         */
+        if (!freezing(p)) {
+                rmb();
+                if (frozen(p))
+                        return false;
 
-        task_lock(p);
-        if (freezing(p)) {
-                if (has_mm(p)) {
-                        if (!signal_pending(p))
-                                fake_signal_wake_up(p);
-                } else {
-                        if (with_mm_only)
-                                ret = 0;
-                        else
-                                wake_up_state(p, TASK_INTERRUPTIBLE);
-                }
+                if (!sig_only || should_send_signal(p))
+                        set_freeze_flag(p);
+                else
+                        return false;
+        }
+
+        if (should_send_signal(p)) {
+                if (!signal_pending(p))
+                        fake_signal_wake_up(p);
+        } else if (sig_only) {
+                return false;
         } else {
-                rmb();
-                if (frozen(p)) {
-                        ret = 0;
-                } else {
-                        if (has_mm(p)) {
-                                set_freeze_flag(p);
-                                fake_signal_wake_up(p);
-                        } else {
-                                if (with_mm_only) {
-                                        ret = 0;
-                                } else {
-                                        set_freeze_flag(p);
-                                        wake_up_state(p, TASK_INTERRUPTIBLE);
-                                }
-                        }
-                }
+                wake_up_state(p, TASK_INTERRUPTIBLE);
         }
-        task_unlock(p);
-        return ret;
+
+        return true;
 }
 
 static void cancel_freezing(struct task_struct *p)
@@ -156,7 +143,7 @@ static void cancel_freezing(struct task_struct *p)
         }
 }
 
-static int try_to_freeze_tasks(int freeze_user_space)
+static int try_to_freeze_tasks(bool sig_only)
 {
         struct task_struct *g, *p;
         unsigned long end_time;
@@ -175,7 +162,7 @@ static int try_to_freeze_tasks(int freeze_user_space)
                         if (frozen(p) || !freezeable(p))
                                 continue;
 
-                        if (!freeze_task(p, freeze_user_space))
+                        if (!freeze_task(p, sig_only))
                                 continue;
 
                         /*
@@ -235,13 +222,13 @@ int freeze_processes(void)
         int error;
 
         printk("Freezing user space processes ... ");
-        error = try_to_freeze_tasks(FREEZER_USER_SPACE);
+        error = try_to_freeze_tasks(true);
         if (error)
                 goto Exit;
         printk("done.\n");
 
         printk("Freezing remaining freezable tasks ... ");
-        error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
+        error = try_to_freeze_tasks(false);
         if (error)
                 goto Exit;
         printk("done.");
@@ -251,7 +238,7 @@ int freeze_processes(void)
         return error;
 }
 
-static void thaw_tasks(int thaw_user_space)
+static void thaw_tasks(bool nosig_only)
 {
         struct task_struct *g, *p;
 
@@ -260,7 +247,7 @@ static void thaw_tasks(int thaw_user_space)
                 if (!freezeable(p))
                         continue;
 
-                if (!p->mm == thaw_user_space)
+                if (nosig_only && should_send_signal(p))
                         continue;
 
                 thaw_process(p);
@@ -271,8 +258,8 @@ static void thaw_tasks(int thaw_user_space)
 void thaw_processes(void)
 {
         printk("Restarting tasks ... ");
-        thaw_tasks(FREEZER_KERNEL_THREADS);
-        thaw_tasks(FREEZER_USER_SPACE);
+        thaw_tasks(true);
+        thaw_tasks(false);
         schedule();
         printk("done.\n");
 }
diff --git a/kernel/power/user.c b/kernel/power/user.c
index f5512cb3aa86..a6332a313262 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -23,6 +23,7 @@
 #include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/freezer.h>
+#include <linux/smp_lock.h>
 
 #include <asm/uaccess.h>
 
@@ -69,16 +70,22 @@ static int snapshot_open(struct inode *inode, struct file *filp)
         struct snapshot_data *data;
         int error;
 
-        if (!atomic_add_unless(&snapshot_device_available, -1, 0))
-                return -EBUSY;
+        mutex_lock(&pm_mutex);
+
+        if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
+                error = -EBUSY;
+                goto Unlock;
+        }
 
         if ((filp->f_flags & O_ACCMODE) == O_RDWR) {
                 atomic_inc(&snapshot_device_available);
-                return -ENOSYS;
+                error = -ENOSYS;
+                goto Unlock;
         }
         if(create_basic_memory_bitmaps()) {
                 atomic_inc(&snapshot_device_available);
-                return -ENOMEM;
+                error = -ENOMEM;
+                goto Unlock;
         }
         nonseekable_open(inode, filp);
         data = &snapshot_state;
@@ -98,33 +105,36 @@ static int snapshot_open(struct inode *inode, struct file *filp)
                 if (error)
                         pm_notifier_call_chain(PM_POST_HIBERNATION);
         }
-        if (error) {
+        if (error)
                 atomic_inc(&snapshot_device_available);
-                return error;
-        }
         data->frozen = 0;
         data->ready = 0;
         data->platform_support = 0;
 
-        return 0;
+ Unlock:
+        mutex_unlock(&pm_mutex);
+
+        return error;
 }
 
 static int snapshot_release(struct inode *inode, struct file *filp)
 {
         struct snapshot_data *data;
 
+        mutex_lock(&pm_mutex);
+
         swsusp_free();
         free_basic_memory_bitmaps();
         data = filp->private_data;
         free_all_swap_pages(data->swap);
-        if (data->frozen) {
-                mutex_lock(&pm_mutex);
+        if (data->frozen)
                 thaw_processes();
-                mutex_unlock(&pm_mutex);
-        }
         pm_notifier_call_chain(data->mode == O_WRONLY ?
                         PM_POST_HIBERNATION : PM_POST_RESTORE);
         atomic_inc(&snapshot_device_available);
+
+        mutex_unlock(&pm_mutex);
+
         return 0;
 }
 
@@ -134,9 +144,13 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf,
         struct snapshot_data *data;
         ssize_t res;
 
+        mutex_lock(&pm_mutex);
+
         data = filp->private_data;
-        if (!data->ready)
-                return -ENODATA;
+        if (!data->ready) {
+                res = -ENODATA;
+                goto Unlock;
+        }
         res = snapshot_read_next(&data->handle, count);
         if (res > 0) {
                 if (copy_to_user(buf, data_of(data->handle), res))
@@ -144,6 +158,10 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf,
                 else
                         *offp = data->handle.offset;
         }
+
+ Unlock:
+        mutex_unlock(&pm_mutex);
+
         return res;
 }
 
@@ -153,6 +171,8 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf,
         struct snapshot_data *data;
         ssize_t res;
 
+        mutex_lock(&pm_mutex);
+
         data = filp->private_data;
         res = snapshot_write_next(&data->handle, count);
         if (res > 0) {
@@ -161,11 +181,14 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf,
                 else
                         *offp = data->handle.offset;
         }
+
+        mutex_unlock(&pm_mutex);
+
         return res;
 }
 
-static int snapshot_ioctl(struct inode *inode, struct file *filp,
-                          unsigned int cmd, unsigned long arg)
+static long snapshot_ioctl(struct file *filp, unsigned int cmd,
+                                                        unsigned long arg)
 {
         int error = 0;
         struct snapshot_data *data;
@@ -179,6 +202,9 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
+        if (!mutex_trylock(&pm_mutex))
+                return -EBUSY;
+
         data = filp->private_data;
 
         switch (cmd) {
@@ -186,7 +212,6 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
         case SNAPSHOT_FREEZE:
                 if (data->frozen)
                         break;
-                mutex_lock(&pm_mutex);
                 printk("Syncing filesystems ... ");
                 sys_sync();
                 printk("done.\n");
@@ -194,7 +219,6 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
                 error = freeze_processes();
                 if (error)
                         thaw_processes();
-                mutex_unlock(&pm_mutex);
                 if (!error)
                         data->frozen = 1;
                 break;
@@ -202,9 +226,7 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
         case SNAPSHOT_UNFREEZE:
                 if (!data->frozen || data->ready)
                         break;
-                mutex_lock(&pm_mutex);
                 thaw_processes();
-                mutex_unlock(&pm_mutex);
                 data->frozen = 0;
                 break;
 
@@ -307,16 +329,11 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
                         error = -EPERM;
                         break;
                 }
-                if (!mutex_trylock(&pm_mutex)) {
-                        error = -EBUSY;
-                        break;
-                }
                 /*
                  * Tasks are frozen and the notifiers have been called with
                  * PM_HIBERNATION_PREPARE
                  */
                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
-                mutex_unlock(&pm_mutex);
                 break;
 
         case SNAPSHOT_PLATFORM_SUPPORT:
@@ -390,6 +407,8 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
 
         }
 
+        mutex_unlock(&pm_mutex);
+
         return error;
 }
 
@@ -399,7 +418,7 @@ static const struct file_operations snapshot_fops = {
         .read = snapshot_read,
         .write = snapshot_write,
         .llseek = no_llseek,
-        .ioctl = snapshot_ioctl,
+        .unlocked_ioctl = snapshot_ioctl,
 };
 
 static struct miscdevice snapshot_device = {