[PATCH 2/2] clocksource: sanity check watchdog clocksource

[Shaohua Li <shli@fb.com>]

Add a sanity check to make sure watchdog clocksource doesn't wrap too
quickly.

Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
---
 kernel/time/clocksource.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 8417c83..64e4629 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -327,7 +327,8 @@ static void clocksource_enqueue_watchdog(struct clocksource *cs)
 		if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
 			cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
 		/* Pick the best watchdog. */
-		if (!watchdog || cs->rating > watchdog->rating) {
+		if (cs->max_idle_ns > WATCHDOG_MAX_INTERVAL_NS &&
+		    (!watchdog || cs->rating > watchdog->rating)) {
 			watchdog = cs;
 			/* Reset watchdog cycles */
 			clocksource_reset_watchdog();
-- 
1.8.5.6