linux-kernel - [PATCH 3/4] [msr driver] Simplify smp_call_function

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Date:	Sat, 21 Jul 2007 17:57:56 +0300
From:	Avi Kivity <avi@...ranet.com>
To:	Andrew Morton <akpm@...l.org>
Cc:	linux-kernel@...r.kernel.org, Avi Kivity <avi@...ranet.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH 3/4] [msr driver] Simplify smp_call_function_single() call sequence

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

diff --git a/arch/i386/lib/msr-on-cpu.c b/arch/i386/lib/msr-on-cpu.c
index 7767962..57d043f 100644
--- a/arch/i386/lib/msr-on-cpu.c
+++ b/arch/i386/lib/msr-on-cpu.c
@@ -26,27 +26,18 @@ static void __rdmsr_safe_on_cpu(void *info)
 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 *info)
 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;
 }
 
-- 
1.5.2.4

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