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[9/9] clocksource: Sanity check watchdog clocksource

Message ID 1439844063-7957-10-git-send-email-john.stultz@linaro.org
State New
Headers show

Commit Message

John Stultz Aug. 17, 2015, 8:41 p.m. UTC 
From: Shaohua Li <shli@fb.com>

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

Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 kernel/time/clocksource.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

John Stultz Aug. 17, 2015, 10:03 p.m. UTC | #1 
On Mon, Aug 17, 2015 at 2:24 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Mon, 17 Aug 2015, John Stultz wrote:
>
>> From: Shaohua Li <shli@fb.com>
>>
>> Add a sanity check to make sure watchdog clocksource doesn't wrap too
>> quickly.
>
> Too quickly for what?

The maximum interval delay limit (which would prevent the logic from
avoiding false positives) .

I can try to expand this text and resend if you want.

Aren't you on vacation? :)
-john
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diff mbox

Patch

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();