ftrace: add UNINTERRUPTIBLE state for kftraced on disable

When dynamic ftrace fails and sets itself disabled, the ftraced daemon
will go back to sleep everytime it wakes up. The setting of the
ftraced state to UNINTERRUPTIBLE is skipped in this process, and the
daemon takes up 100% of the CPU.  This patch makes sure the ftraced daemon
sets itself to UNINTERRUPTIBLE in that loop.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/trace/ftrace.c

@@ -630,10 +630,10 @@ static int ftraced(void *ignore)
 {
 	unsigned long usecs;
 
-	set_current_state(TASK_INTERRUPTIBLE);
-
 	while (!kthread_should_stop()) {
 
+		set_current_state(TASK_INTERRUPTIBLE);
+
 		/* check once a second */
 		schedule_timeout(HZ);
 
@@ -667,8 +667,6 @@ static int ftraced(void *ignore)
 		wake_up_interruptible(&ftraced_waiters);
 
 		ftrace_shutdown_replenish();
-
-		set_current_state(TASK_INTERRUPTIBLE);
 	}
 	__set_current_state(TASK_RUNNING);
 	return 0;