linux-kernel - [PATCH] i386 tsc: remove xtime_lock'ing around cpufreq notifier

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Message-Id: <20070411162904.232696302@mvista.com>
Date:	Wed, 11 Apr 2007 09:29:04 -0700
From:	Daniel Walker <dwalker@...sta.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org, johnstul@...ibm.com, tglx@...utronix.de
Subject: [PATCH] i386 tsc: remove xtime_lock'ing around cpufreq notifier

The locking of the xtime_lock around the cpu notifier is unessesary now. At one
time the tsc was used after a frequency change for timekeeping, but the re-write
of timekeeping no longer uses the TSC unless the frequency is constant. 

The variables that are changed in this section of code had also once been used
for timekeeping, but not any longer ..

Signed-Off-By: Daniel Walker <dwalker@...sta.com>

---
 arch/i386/kernel/tsc.c |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

Index: linux-2.6.20/arch/i386/kernel/tsc.c
===================================================================
--- linux-2.6.20.orig/arch/i386/kernel/tsc.c
+++ linux-2.6.20/arch/i386/kernel/tsc.c
@@ -200,13 +200,10 @@ time_cpufreq_notifier(struct notifier_bl
 {
 	struct cpufreq_freqs *freq = data;
 
-	if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
-		write_seqlock_irq(&xtime_lock);
-
 	if (!ref_freq) {
 		if (!freq->old){
 			ref_freq = freq->new;
-			goto end;
+			return 0;
 		}
 		ref_freq = freq->old;
 		loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy;
@@ -237,9 +234,6 @@ time_cpufreq_notifier(struct notifier_bl
 			}
 		}
 	}
-end:
-	if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE)
-		write_sequnlock_irq(&xtime_lock);
 
 	return 0;
 }
-- 

-- 
-
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