The patch titled
Subject: kernel/watchdog.c: fix race between proc_watchdog_thresh() and watchdog_timer_fn()
has been added to the -mm tree. Its filename is
watchdog-fix-race-between-proc_watchdog_thresh-and-watchdog_timer_fn.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/watchdog-fix-race-between-proc_watchdog_thresh-and-watchdog_timer_fn.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/watchdog-fix-race-between-proc_watchdog_thresh-and-watchdog_timer_fn.patch
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------------------------------------------------------
From: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Subject: kernel/watchdog.c: fix race between proc_watchdog_thresh() and watchdog_timer_fn()
Theoretically it is possible that the watchdog timer expires right at the
time when a user sets 'watchdog_thresh' to zero (note: this disables the
lockup detectors). In this scenario, the is_softlockup() function - which
is called by the timer - could produce a false positive.
Fix this by checking the current value of 'watchdog_thresh'.
Signed-off-by: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Aaron Tomlin <atomlin@xxxxxxxxxx>
Cc: Ulrich Obergfell <uobergfe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/watchdog.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN kernel/watchdog.c~watchdog-fix-race-between-proc_watchdog_thresh-and-watchdog_timer_fn kernel/watchdog.c
--- a/kernel/watchdog.c~watchdog-fix-race-between-proc_watchdog_thresh-and-watchdog_timer_fn
+++ a/kernel/watchdog.c
@@ -289,7 +289,7 @@ static int is_softlockup(unsigned long t
{
unsigned long now = get_timestamp();
- if (watchdog_enabled & SOFT_WATCHDOG_ENABLED) {
+ if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){
/* Warn about unreasonable delays. */
if (time_after(now, touch_ts + get_softlockup_thresh()))
return now - touch_ts;
_
Patches currently in -mm which might be from uobergfe@xxxxxxxxxx are
watchdog-fix-error-handling-in-proc_watchdog_thresh.patch
watchdog-move-watchdog_disable_all_cpus-outside-of-ifdef.patch
watchdog-implement-error-handling-in-update_watchdog_all_cpus-and-callers.patch
watchdog-implement-error-handling-in-lockup_detector_suspend.patch
watchdog-do-not-unpark-threads-in-watchdog_park_threads-on-error.patch
watchdog-avoid-race-between-lockup-detector-suspend-resume-and-cpu-hotplug.patch
watchdog-avoid-races-between-proc-handlers-and-cpu-hotplug.patch
watchdog-remove-getput_online_cpus-from-watchdog_parkunpark_threads.patch
watchdog-fix-race-between-proc_watchdog_thresh-and-watchdog_timer_fn.patch
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