Commit 39d2da21 authored Nov 05, 2015 by Ulrich Obergfell Committed by Linus Torvalds Nov 05, 2015

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@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>

parent a2a45b85

kernel/watchdog.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;

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