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debug: softlockup looping fix

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

  commit 82a1fcb902
  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: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Zijlstra 2008-02-02 00:23:08 +01:00 committed by Linus Torvalds
parent aa62999269
commit ed50d6cbc3
1 changed files with 20 additions and 10 deletions
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30
kernel/softlockup.c
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@ -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);