linux-kernel - [PATCH] x86: fix atomic64_xxx

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Date:	Tue, 03 Jan 2012 17:35:40 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jan Beulich <JBeulich@...e.com>
Cc:	mingo@...e.hu, tglx@...utronix.de,
	Christoph Lameter <cl@...ux.com>, linux-kernel@...r.kernel.org,
	netdev <netdev@...r.kernel.org>, hpa@...or.com
Subject: [PATCH] x86: fix atomic64_xxx_cx8() functions

It appears about all functions in arch/x86/lib/atomic64_cx8_32.S are
wrong in case cmpxchg8b must be restarted, because LOCK_PREFIX macro
defines a label "1" clashing with other local labels :

1:
	some_instructions
	LOCK_PREFIX
	cmpxchg8b (%ebp)
	jne 1b  / jumps to beginning of LOCK_PREFIX !

A possible fix is to use a magic label "672" in LOCK_PREFIX asm
definition, similar to the "671" one we defined in LOCK_PREFIX_HERE. 

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
Acked-by: Jan Beulich <JBeulich@...e.com>
CC: Christoph Lameter <cl@...ux.com>
CC: Ingo Molnar <mingo@...e.hu>
CC: H. Peter Anvin <hpa@...or.com>
Cc: stable@...r.kernel.org  [2.6.35+]
---
 arch/x86/include/asm/alternative-asm.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h
index 091508b..952bd01 100644
--- a/arch/x86/include/asm/alternative-asm.h
+++ b/arch/x86/include/asm/alternative-asm.h
@@ -4,10 +4,10 @@
 
 #ifdef CONFIG_SMP
 	.macro LOCK_PREFIX
-1:	lock
+672:	lock
 	.section .smp_locks,"a"
 	.balign 4
-	.long 1b - .
+	.long 672b - .
 	.previous
 	.endm
 #else


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