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kernel/watchdog.c: fix race between proc_watchdog_thresh() and watchdog_timer_fn()

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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@redhat.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ulrich Obergfell 2015-11-05 18:44:56 -08:00 committed by Linus Torvalds
parent a2a45b85ec
commit 39d2da2161
1 changed files with 1 additions and 1 deletions
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kernel/watchdog.c
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@ -289,7 +289,7 @@ static int is_softlockup(unsigned long touch_ts)
{
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;