softlockup: fix task state setting

kthread_stop() can be called when a 'watchdog' thread is executing after
kthread_should_stop() but before set_task_state(TASK_INTERRUPTIBLE).

Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 6 deletions

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 7c2da88db4ed..01b6522fd92b 100644
--- a/kernel/softlockup.c
+++ b/kernel/softlockup.c
@@ -216,26 +216,27 @@ static int watchdog(void *__bind_cpu)
         /* initialize timestamp */
         touch_softlockup_watchdog();
 
+        set_current_state(TASK_INTERRUPTIBLE);
         /*
          * Run briefly once per second to reset the softlockup timestamp.
          * If this gets delayed for more than 60 seconds then the
          * debug-printout triggers in softlockup_tick().
          */
         while (!kthread_should_stop()) {
-                set_current_state(TASK_INTERRUPTIBLE);
                 touch_softlockup_watchdog();
                 schedule();
 
                 if (kthread_should_stop())
                         break;
 
-                if (this_cpu != check_cpu)
-                        continue;
-
-                if (sysctl_hung_task_timeout_secs)
-                        check_hung_uninterruptible_tasks(this_cpu);
+                if (this_cpu == check_cpu) {
+                        if (sysctl_hung_task_timeout_secs)
+                                check_hung_uninterruptible_tasks(this_cpu);
+                }
 
+                set_current_state(TASK_INTERRUPTIBLE);
         }
+        __set_current_state(TASK_RUNNING);
 
         return 0;
 }