freezer: set PF_SUSPEND_TASK flag on tasks that call freeze_processes

[deliverable/linux.git] / kernel / power / process.c

diff --git a/kernel/power/process.c b/kernel/power/process.c
index fc0df84864495f8c44261961cb6909e66d24a21e..06ec8869dbf1629f2c7cabc63f2edc96426ea87d 100644 (file)
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -109,6 +109,8 @@ 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.
  */
@@ -120,6 +122,9 @@ int freeze_processes(void)
        if (error)
                return error;
 
+       /* Make sure this task doesn't get frozen */
+       current->flags |= PF_SUSPEND_TASK;
+
        if (!pm_freezing)
                atomic_inc(&system_freezing_cnt);
 
@@ -168,6 +173,7 @@ int freeze_kernel_threads(void)
 void thaw_processes(void)
 {
        struct task_struct *g, *p;
+       struct task_struct *curr = current;
 
        if (pm_freezing)
                atomic_dec(&system_freezing_cnt);
@@ -182,10 +188,15 @@ void thaw_processes(void)
 
        read_lock(&tasklist_lock);
        do_each_thread(g, p) {
+               /* No other threads should have PF_SUSPEND_TASK set */
+               WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
                __thaw_task(p);
        } while_each_thread(g, p);
        read_unlock(&tasklist_lock);
 
+       WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
+       curr->flags &= ~PF_SUSPEND_TASK;
+
        usermodehelper_enable();
 
        schedule();