1 files changed, 26 insertions, 11 deletions

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 98088e0e71e8..06ec8869dbf1 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -30,9 +30,10 @@ static int try_to_freeze_tasks(bool user_only)
         unsigned int todo;
         bool wq_busy = false;
         struct timeval start, end;
-        u64 elapsed_csecs64;
-        unsigned int elapsed_csecs;
+        u64 elapsed_msecs64;
+        unsigned int elapsed_msecs;
         bool wakeup = false;
+        int sleep_usecs = USEC_PER_MSEC;
 
         do_gettimeofday(&start);
 
@@ -68,22 +69,25 @@ static int try_to_freeze_tasks(bool user_only)
 
                 /*
                  * We need to retry, but first give the freezing tasks some
-                 * time to enter the refrigerator.
+                 * time to enter the refrigerator.  Start with an initial
+                 * 1 ms sleep followed by exponential backoff until 8 ms.
                  */
-                msleep(10);
+                usleep_range(sleep_usecs / 2, sleep_usecs);
+                if (sleep_usecs < 8 * USEC_PER_MSEC)
+                        sleep_usecs *= 2;
         }
 
         do_gettimeofday(&end);
-        elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
-        do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
-        elapsed_csecs = elapsed_csecs64;
+        elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
+        do_div(elapsed_msecs64, NSEC_PER_MSEC);
+        elapsed_msecs = elapsed_msecs64;
 
         if (todo) {
                 printk("\n");
-                printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
+                printk(KERN_ERR "Freezing of tasks %s after %d.%03d seconds "
                        "(%d tasks refusing to freeze, wq_busy=%d):\n",
                        wakeup ? "aborted" : "failed",
-                       elapsed_csecs / 100, elapsed_csecs % 100,
+                       elapsed_msecs / 1000, elapsed_msecs % 1000,
                        todo - wq_busy, wq_busy);
 
                 if (!wakeup) {
@@ -96,8 +100,8 @@ static int try_to_freeze_tasks(bool user_only)
                         read_unlock(&tasklist_lock);
                 }
         } else {
-                printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
-                        elapsed_csecs % 100);
+                printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000,
+                        elapsed_msecs % 1000);
         }
 
         return todo ? -EBUSY : 0;
@@ -105,6 +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.
  */
@@ -116,6 +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);
 
@@ -164,6 +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);
@@ -178,10 +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();