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clocksource: Prevent immediate watchdog rerun after a delay

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The watchdog rewrite made the clocksource check handle long intervals
between two measurements, but missed that the timer expiry needs to be
rebased after such a delay.

When a watchdog invocation is delayed by more than one interval, adding
WATCHDOG_INTERVAL to the previous expiry leaves the timer expiry in the
past. That causes an immediate second invocation. The resulting short
measurement interval can mark a clocksource unstable.

Cure this by rearming the timer based on jiffies, which places the next
expiry one full watchdog interval into the future.

Fixes: 763aacf86f ("clocksource: Rewrite watchdog code completely")
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261026010200.96371-1-kmehltretter@gmail.com
Closes: https://lore.kernel.org/r/20261010065509.72916-1-kmehltretter@gmail.com/
This commit is contained in:
Karl Mehltretter 2026-10-26 02:02:00 +01:00 committed by Thomas Gleixner
parent cbd0f65b48
commit f322d7f7ae
1 changed files with 1 additions and 1 deletions
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2
kernel/time/clocksource.c
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@ -673,7 +673,7 @@ static void clocksource_watchdog(struct timer_list *unused)
/* Could have been rearmed by a stop/start cycle */
if (!timer_pending(&watchdog_timer)) {
watchdog_timer.expires += WATCHDOG_INTERVAL;
watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
add_timer_local(&watchdog_timer);
}
}