linux-kernel - [PATCH 3/8] x86, i387.c: thread xstate is initialized only on BSP once

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Date:	Wed,  5 Oct 2011 09:39:14 -0700
From:	"Fenghua Yu" <fenghua.yu@...el.com>
To:	"Ingo Molnar" <mingo@...e.hu>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"H Peter Anvin" <hpa@...or.com>,
	"Zwane Mwaikambo" <zwane@....linux.org.uk>,
	"Tony Luck" <tony.luck@...el.com>,
	"Asit K Mallick" <asit.k.mallick@...el.com>,
	"Suresh B Siddha" <suresh.b.siddha@...el.com>,
	"Len Brown" <lenb@...nel.org>
Cc:	"linux-kernel" <linux-kernel@...r.kernel.org>,
	"Fenghua Yu" <fenghua.yu@...el.com>
Subject: [PATCH 3/8] x86, i387.c: thread xstate is initialized only on BSP once

From: Fenghua Yu <fenghua.yu@...el.com>

init_thread_xstate() is only called on BSP once to avoid to override
xstate_size.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
---
 arch/x86/kernel/i387.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 739d859..de2b48a 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -93,6 +93,7 @@ void __cpuinit fpu_init(void)
 {
 	unsigned long cr0;
 	unsigned long cr4_mask = 0;
+	static int once;
 
 	if (cpu_has_fxsr)
 		cr4_mask |= X86_CR4_OSFXSR;
@@ -107,8 +108,14 @@ void __cpuinit fpu_init(void)
 		cr0 |= X86_CR0_EM;
 	write_cr0(cr0);
 
-	if (!smp_processor_id())
+	/*
+	 * init_thread_xstate is only called on BSP once to avoid to override
+	 * xstate_size.
+	 */
+	if (!smp_processor_id() && once) {
+		once = 0;
 		init_thread_xstate();
+	}
 
 	mxcsr_feature_mask_init();
 	/* clean state in init */
-- 
1.6.0.3

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