tick: Prefer a lower rating device only if it's CPU local device

Checking the equality of cpumask for both new and old tick device doesn't
ensure that it's CPU local device. This will cause issue if a low rating
clockevent tick device is registered first followed by the registration
of higher rating clockevent tick device.

In such case, clockevents_released list will never get emptied as both
the devices get selected as preferred one and we will loop forever in
clockevents_notify_released.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: https://lkml.kernel.org/r/1525881728-4858-1-git-send-email-sudeep.holla@arm.com

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 49edc1c4f3e645894f839c40489ab81594a02398..78e598334007b627181a9e81b9ffaef5f19f86d1 100644 (file)
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -277,7 +277,8 @@ static bool tick_check_preferred(struct clock_event_device *curdev,
         */
        return !curdev ||
                newdev->rating > curdev->rating ||
-              !cpumask_equal(curdev->cpumask, newdev->cpumask);
+              (!cpumask_equal(curdev->cpumask, newdev->cpumask) &&
+               !tick_check_percpu(curdev, newdev, smp_processor_id()));
 }
 
 /*