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Commit ed50d6cb authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds
Browse files

debug: softlockup looping fix 



Rafael J. Wysocki reported weird, multi-seconds delays during
suspend/resume and bisected it back to:

  commit 82a1fcb9
  Author: Ingo Molnar <mingo@elte.hu>
  Date:   Fri Jan 25 21:08:02 2008 +0100

      softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks

fix it:

 - restore the old wakeup mechanism
 - fix break usage in do_each_thread() { } while_each_thread().
 - fix the hotplug switch stmt, a fall-through case was broken.

Bisected-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Acked-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent aa629992

kernel/softlockup.c

+20 −10
Original line number Diff line number Diff line
@@ -101,6 +101,10 @@ void softlockup_tick(void) 


	now = get_timestamp(this_cpu);



	/* Wake up the high-prio watchdog task every second: */

	if (now > (touch_timestamp + 1))

		wake_up_process(per_cpu(watchdog_task, this_cpu));



	/* Warn about unreasonable delays: */

	if (now <= (touch_timestamp + softlockup_thresh))

		return;
@@ -191,11 +195,11 @@ static void check_hung_uninterruptible_tasks(int this_cpu) 
	read_lock(&tasklist_lock);

	do_each_thread(g, t) {

		if (!--max_count)

			break;

			goto unlock;

		if (t->state & TASK_UNINTERRUPTIBLE)

			check_hung_task(t, now);

	} while_each_thread(g, t);



 unlock:

	read_unlock(&tasklist_lock);

}
@@ -218,14 +222,19 @@ static int watchdog(void *__bind_cpu) 
	 * debug-printout triggers in softlockup_tick().

	 */

	while (!kthread_should_stop()) {

		set_current_state(TASK_INTERRUPTIBLE);

		touch_softlockup_watchdog();

		msleep_interruptible(10000);

		schedule();



		if (kthread_should_stop())

			break;



		if (this_cpu != check_cpu)

			continue;



		if (sysctl_hung_task_timeout_secs)

			check_hung_uninterruptible_tasks(this_cpu);



	}



	return 0;
@@ -259,13 +268,6 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) 
		wake_up_process(per_cpu(watchdog_task, hotcpu));

		break;

#ifdef CONFIG_HOTPLUG_CPU

	case CPU_UP_CANCELED:

	case CPU_UP_CANCELED_FROZEN:

		if (!per_cpu(watchdog_task, hotcpu))

			break;

		/* Unbind so it can run.  Fall thru. */

		kthread_bind(per_cpu(watchdog_task, hotcpu),

			     any_online_cpu(cpu_online_map));

	case CPU_DOWN_PREPARE:

	case CPU_DOWN_PREPARE_FROZEN:

		if (hotcpu == check_cpu) {
@@ -275,6 +277,14 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) 
			check_cpu = any_online_cpu(temp_cpu_online_map);

		}

		break;



	case CPU_UP_CANCELED:

	case CPU_UP_CANCELED_FROZEN:

		if (!per_cpu(watchdog_task, hotcpu))

			break;

		/* Unbind so it can run.  Fall thru. */

		kthread_bind(per_cpu(watchdog_task, hotcpu),

			     any_online_cpu(cpu_online_map));

	case CPU_DEAD:

	case CPU_DEAD_FROZEN:

		p = per_cpu(watchdog_task, hotcpu);