The patch titled
softlockup: fix a potential race condition in watchdog()
has been added to the -mm tree. Its filename is
softlockup-fix-a-potential-race-condition-in-watchdog.patch
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------------------------------------------------------
Subject: softlockup: fix a potential race condition in watchdog()
From: Dmitry Adamushko <[EMAIL PROTECTED]>
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 <[EMAIL PROTECTED]>
Cc: Ingo Molnar <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---
kernel/softlockup.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff -puN
kernel/softlockup.c~softlockup-fix-a-potential-race-condition-in-watchdog
kernel/softlockup.c
--- a/kernel/softlockup.c~softlockup-fix-a-potential-race-condition-in-watchdog
+++ a/kernel/softlockup.c
@@ -98,6 +98,7 @@ void softlockup_tick(void)
touch_softlockup_watchdog();
return;
}
+ printk(KERN_ERR "watchdog(cpu: %d) -- exit\n", this_cpu);
now = get_timestamp(this_cpu);
@@ -216,26 +217,25 @@ 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)
+ if (this_cpu == check_cpu && sysctl_hung_task_timeout_secs)
check_hung_uninterruptible_tasks(this_cpu);
+ set_current_state(TASK_INTERRUPTIBLE);
}
+ __set_current_state(TASK_RUNNING);
return 0;
}
@@ -289,6 +289,7 @@ cpu_callback(struct notifier_block *nfb,
case CPU_DEAD_FROZEN:
p = per_cpu(watchdog_task, hotcpu);
per_cpu(watchdog_task, hotcpu) = NULL;
+ printk(KERN_ERR "kthread_stop(watchdog on cpu: %d)\n", hotcpu);
kthread_stop(p);
break;
#endif /* CONFIG_HOTPLUG_CPU */
_
Patches currently in -mm which might be from [EMAIL PROTECTED] are
origin.patch
softlockup-fix-a-potential-race-condition-in-watchdog.patch
-
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