linux-kernel - [PATCH] [45/45] i386: simplify smp_call_function

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Date:	Fri, 21 Sep 2007 22:45:28 +0200 (CEST)
From:	Andi Kleen <ak@...e.de>
To:	avi@...ranet.com, hpa@...or.com, ak@...e.de, patches@...-64.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] [45/45] i386: simplify smp_call_function_single() call sequence


From: Avi Kivity <avi@...ranet.com>

smp_call_function_single() now knows how to call the function on the
current cpu.

Cc: H. Peter Anvin <hpa@...or.com>
Signed-off-by: Avi Kivity <avi@...ranet.com>
Signed-off-by: Andi Kleen <ak@...e.de>
Cc: Andi Kleen <ak@...e.de>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 arch/i386/lib/msr-on-cpu.c |   62 +++++++++++++++------------------------------
 1 file changed, 22 insertions(+), 40 deletions(-)

Index: linux/arch/i386/lib/msr-on-cpu.c
===================================================================
--- linux.orig/arch/i386/lib/msr-on-cpu.c
+++ linux/arch/i386/lib/msr-on-cpu.c
@@ -26,27 +26,18 @@ static void __rdmsr_safe_on_cpu(void *in
 static int _rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h, int safe)
 {
 	int err = 0;
-	preempt_disable();
-	if (smp_processor_id() == cpu)
-		if (safe)
-			err = rdmsr_safe(msr_no, l, h);
-		else
-			rdmsr(msr_no, *l, *h);
-	else {
-		struct msr_info rv;
-
-		rv.msr_no = msr_no;
-		if (safe) {
-			smp_call_function_single(cpu, __rdmsr_safe_on_cpu,
-						 &rv, 0, 1);
-			err = rv.err;
-		} else {
-			smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 0, 1);
-		}
-		*l = rv.l;
-		*h = rv.h;
+	struct msr_info rv;
+
+	rv.msr_no = msr_no;
+	if (safe) {
+		smp_call_function_single(cpu, __rdmsr_safe_on_cpu, &rv, 0, 1);
+		err = rv.err;
+	} else {
+		smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 0, 1);
 	}
-	preempt_enable();
+	*l = rv.l;
+	*h = rv.h;
+
 	return err;
 }
 
@@ -67,27 +58,18 @@ static void __wrmsr_safe_on_cpu(void *in
 static int _wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h, int safe)
 {
 	int err = 0;
-	preempt_disable();
-	if (smp_processor_id() == cpu)
-		if (safe)
-			err = wrmsr_safe(msr_no, l, h);
-		else
-			wrmsr(msr_no, l, h);
-	else {
-		struct msr_info rv;
-
-		rv.msr_no = msr_no;
-		rv.l = l;
-		rv.h = h;
-		if (safe) {
-			smp_call_function_single(cpu, __wrmsr_safe_on_cpu,
-						 &rv, 0, 1);
-			err = rv.err;
-		} else {
-			smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 0, 1);
-		}
+	struct msr_info rv;
+
+	rv.msr_no = msr_no;
+	rv.l = l;
+	rv.h = h;
+	if (safe) {
+		smp_call_function_single(cpu, __wrmsr_safe_on_cpu, &rv, 0, 1);
+		err = rv.err;
+	} else {
+		smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 0, 1);
 	}
-	preempt_enable();
+
 	return err;
 }
 
-
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