linux-kernel - Re: [PATCH] Code clean up for percpu

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Date:	Thu, 20 Oct 2011 10:45:12 +0800
From:	"Alex,Shi" <alex.shi@...el.com>
To:	Avi Kivity <avi@...hat.com>
Cc:	Christoph Lameter <cl@...two.org>, "tj@...nel.org" <tj@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"eric.dumazet@...il.com" <eric.dumazet@...il.com>,
	"Huang, Ying" <ying.huang@...el.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"kaber@...sh.net" <kaber@...sh.net>,
	"a.p.zijlstra@...llo.nl" <a.p.zijlstra@...llo.nl>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"jeremy@...source.com" <jeremy@...source.com>
Subject: Re: [PATCH] Code clean up for percpu_xxx() functions



> All of the kvm usage is in preemption disabled contexts.

Thanks! So would you like to ack this patch? 

===
>>From 8ca7e6e40d75eab598c4fb4f8d555299b747adfa Mon Sep 17 00:00:00 2001
From: Alex Shi <alex.shi@...el.com>
Date: Thu, 20 Oct 2011 10:31:51 +0800
Subject: [PATCH 2/2] Change this_cpu_xxx to __this_cpu_xxx funcs

According to Avi, all of this_cpu_xx used in preempt disable context,
So change them to __this_cpu_xxx that without abundant preempt
protection.

Signed-off-by: Alex Shi <alex.shi@...el.com>
---
 arch/x86/kvm/x86.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5ff2516..432c4bc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5024,15 +5024,15 @@ static DEFINE_PER_CPU(struct kvm_vcpu *, current_vcpu);
 
 static int kvm_is_in_guest(void)
 {
-	return this_cpu_read(current_vcpu) != NULL;
+	return __this_cpu_read(current_vcpu) != NULL;
 }
 
 static int kvm_is_user_mode(void)
 {
 	int user_mode = 3;
 
-	if (this_cpu_read(current_vcpu))
-		user_mode = kvm_x86_ops->get_cpl(this_cpu_read(current_vcpu));
+	if (__this_cpu_read(current_vcpu))
+		user_mode = kvm_x86_ops->get_cpl(__this_cpu_read(current_vcpu));
 
 	return user_mode != 0;
 }
@@ -5041,8 +5041,8 @@ static unsigned long kvm_get_guest_ip(void)
 {
 	unsigned long ip = 0;
 
-	if (this_cpu_read(current_vcpu))
-		ip = kvm_rip_read(this_cpu_read(current_vcpu));
+	if (__this_cpu_read(current_vcpu))
+		ip = kvm_rip_read(__this_cpu_read(current_vcpu));
 
 	return ip;
 }
-- 
1.6.3.3




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