kernel/watchdog.c: add comment to watchdog() exit path

Revelation from Peter.

Cc: Peter Zijlstra <[email protected]>
Cc: Don Zickus <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

kernel/watchdog.c

@@ -349,6 +349,10 @@ static int watchdog(void *unused)
 
 		set_current_state(TASK_INTERRUPTIBLE);
 	}
+	/*
+	 * Drop the policy/priority elevation during thread exit to avoid a
+	 * scheduling latency spike.
+	 */
 	__set_current_state(TASK_RUNNING);
 	sched_setscheduler(current, SCHED_NORMAL, &param);
 	return 0;