linux-kernel - [PATCH UPDATED 04/16] x86: Use local variable to cache smp_processor_id() in setup_local

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Date:	Tue, 30 Nov 2010 17:17:19 +0100
From:	Tejun Heo <tj@...nel.org>
To:	Cyrill Gorcunov <gorcunov@...il.com>
CC:	linux-kernel@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
	hpa@...or.com, x86@...nel.org, eric.dumazet@...il.com,
	yinghai@...nel.org, brgerst@...il.com, gorcunov@...il.com,
	penberg@...nel.org
Subject: [PATCH UPDATED 04/16] x86: Use local variable to cache smp_processor_id()
 in setup_local_APIC()

Subject: x86: Use local variable to cache smp_processor_id() in setup_local_APIC()

This is a trivial clean up.

* Move initialization of @cpu inside preemption disabled region as
  suggested by Cyrill Gorcunov.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Yinghai Lu <yinghai@...nel.org>
Cc: Cyrill Gorcunov <gorcunov@...il.com>
---
Updated as suggested.  Git tree updated too.

Thanks.

 arch/x86/kernel/apic/apic.c |   15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

Index: work/arch/x86/kernel/apic/apic.c
===================================================================
--- work.orig/arch/x86/kernel/apic/apic.c
+++ work/arch/x86/kernel/apic/apic.c
@@ -1202,7 +1202,7 @@ static void __cpuinit lapic_setup_esr(vo
 void __cpuinit setup_local_APIC(void)
 {
 	unsigned int value, queued;
-	int i, j, acked = 0;
+	int cpu, i, j, acked = 0;
 	unsigned long long tsc = 0, ntsc;
 	long long max_loops = cpu_khz;

@@ -1226,6 +1226,7 @@ void __cpuinit setup_local_APIC(void)
 	perf_events_lapic_init();

 	preempt_disable();
+	cpu = smp_processor_id();

 	/*
 	 * Double-check whether this APIC is really registered.
@@ -1342,21 +1343,19 @@ void __cpuinit setup_local_APIC(void)
 	 * TODO: set up through-local-APIC from through-I/O-APIC? --macro
 	 */
 	value = apic_read(APIC_LVT0) & APIC_LVT_MASKED;
-	if (!smp_processor_id() && (pic_mode || !value)) {
+	if (!cpu && (pic_mode || !value)) {
 		value = APIC_DM_EXTINT;
-		apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n",
-				smp_processor_id());
+		apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n", cpu);
 	} else {
 		value = APIC_DM_EXTINT | APIC_LVT_MASKED;
-		apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n",
-				smp_processor_id());
+		apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n", cpu);
 	}
 	apic_write(APIC_LVT0, value);

 	/*
 	 * only the BP should see the LINT1 NMI signal, obviously.
 	 */
-	if (!smp_processor_id())
+	if (!cpu)
 		value = APIC_DM_NMI;
 	else
 		value = APIC_DM_NMI | APIC_LVT_MASKED;
@@ -1368,7 +1367,7 @@ void __cpuinit setup_local_APIC(void)

 #ifdef CONFIG_X86_MCE_INTEL
 	/* Recheck CMCI information after local APIC is up on CPU #0 */
-	if (smp_processor_id() == 0)
+	if (cpu == 0)
 		cmci_recheck();
 #endif
 }
--
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