linux-kernel - [PATCH] cmpxchg: Discard unnecessary cast to volatile

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Date:	Wed,  1 Oct 2014 13:57:27 -0400
From:	Pranith Kumar <bobby.prani@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	x86@...nel.org (maintainer:X86 ARCHITECTURE...),
	Borislav Petkov <bp@...e.de>,
	linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE...)
Subject: [PATCH] cmpxchg: Discard unnecessary cast to volatile

Generating a volatile pointer is really not necessary here. This is the only
location where a volatile pointer is being generated for use in asm.

This commit removes the unnecessary volatile pointer being created.

Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
---
 arch/x86/include/asm/cmpxchg.h | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
index 99c105d7..f0baea8 100644
--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -90,36 +90,32 @@ extern void __add_wrong_size(void)
 	switch (size) {							\
 	case __X86_CASE_B:						\
 	{								\
-		volatile u8 *__ptr = (volatile u8 *)(ptr);		\
 		asm volatile(lock "cmpxchgb %2,%1"			\
-			     : "=a" (__ret), "+m" (*__ptr)		\
+			     : "=a" (__ret), "+m" (*ptr)		\
 			     : "q" (__new), "0" (__old)			\
 			     : "memory");				\
 		break;							\
 	}								\
 	case __X86_CASE_W:						\
 	{								\
-		volatile u16 *__ptr = (volatile u16 *)(ptr);		\
 		asm volatile(lock "cmpxchgw %2,%1"			\
-			     : "=a" (__ret), "+m" (*__ptr)		\
+			     : "=a" (__ret), "+m" (*ptr)		\
 			     : "r" (__new), "0" (__old)			\
 			     : "memory");				\
 		break;							\
 	}								\
 	case __X86_CASE_L:						\
 	{								\
-		volatile u32 *__ptr = (volatile u32 *)(ptr);		\
 		asm volatile(lock "cmpxchgl %2,%1"			\
-			     : "=a" (__ret), "+m" (*__ptr)		\
+			     : "=a" (__ret), "+m" (*ptr)		\
 			     : "r" (__new), "0" (__old)			\
 			     : "memory");				\
 		break;							\
 	}								\
 	case __X86_CASE_Q:						\
 	{								\
-		volatile u64 *__ptr = (volatile u64 *)(ptr);		\
 		asm volatile(lock "cmpxchgq %2,%1"			\
-			     : "=a" (__ret), "+m" (*__ptr)		\
+			     : "=a" (__ret), "+m" (*ptr)		\
 			     : "r" (__new), "0" (__old)			\
 			     : "memory");				\
 		break;							\
-- 
1.9.1

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