linux-kernel - [PATCH 1/2] Revert "tick: Prefer a lower rating device only if it's CPU local device"

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Date:   Mon,  9 Jul 2018 16:45:35 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kevin Hilman <khilman@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: [PATCH 1/2] Revert "tick: Prefer a lower rating device only if it's CPU local device"

This reverts commit 1332a90558013ae4242e3dd7934bdcdeafb06c0d.

The original issue was not because of incorrect checking of cpumask for
both new and old tick device. It was incorrectly analysed was due to the
misunderstanding of the comment and misinterpretation of the return
value from tick_check_preferred. The main issue is with the clockevent
driver that sets the cpumask to cpu_all_mask instead of cpu_possible_mask.

Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
---
 kernel/time/tick-common.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Hi Thomas,

As mentioned in the other thread, this needs to be reverted. Sorry for
the misunderstanding the original issue and producing wrong fix.

Regards,
Sudeep

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index b7005dd21ec1..14de3727b18e 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -277,8 +277,7 @@ static bool tick_check_preferred(struct clock_event_device *curdev,
 	 */
 	return !curdev ||
 		newdev->rating > curdev->rating ||
-	       (!cpumask_equal(curdev->cpumask, newdev->cpumask) &&
-	        !tick_check_percpu(curdev, newdev, smp_processor_id()));
+	       !cpumask_equal(curdev->cpumask, newdev->cpumask);
 }

 /*
--
2.7.4