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>

diff --git a/kernel/softlockup.c b/kernel/softlockup.c
index 7c2da88..01b6522 100644 (file)
--- 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;
 }