linux-kernel - [PATCH] avoid second smp_processor_id() call in __touch

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Date:	Wed, 22 Sep 2010 12:00:12 +0300
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Don Zickus <dzickus@...hat.com>,
	Cyrill Gorcunov <gorcunov@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH] avoid second smp_processor_id() call in __touch_watchdog

Hello,

Per our previous conversation:

Andrew Morton wrote:
> Fair enough, although strictly speaking this should be done in a
> separate and later patch.
> 


Avoid double smp_processor_id() call in __touch_watchdog (smp_processor_id() 
itself and later call in __get_cpu_var())

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>

---

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 7f9c3c5..03d97c5 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -116,8 +116,7 @@ static unsigned long get_sample_period(void)
 static void __touch_watchdog(void)
 {
 	int this_cpu = smp_processor_id();
-
-	__get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu);
+	per_cpu(watchdog_touch_ts, this_cpu) = get_timestamp(this_cpu);
 }
 
 void touch_softlockup_watchdog(void)

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