linux-kernel - [PATCH 3.12 039/124] arm64: cmpxchg: update macros to prevent warnings

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Message-Id: <12c55b60a6b63fe05b2e1b9a9ba2f05aaf53e13f.1438076484.git.jslaby@suse.cz>
Date:	Tue, 28 Jul 2015 11:42:53 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Mark Hambleton <mahamble@...adcom.com>,
	Mark Brown <broonie@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 039/124] arm64: cmpxchg: update macros to prevent warnings

From: Mark Hambleton <mahamble@...adcom.com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 60010e508111b2fd3d73de56f3b2c2bfc0f9eba1 upstream.

Make sure the value we are going to return is referenced in order to
avoid warnings from newer GCCs such as:

arch/arm64/include/asm/cmpxchg.h:162:3: warning: value computed is not used [-Wunused-value]
  ((__typeof__(*(ptr)))__cmpxchg_mb((ptr),   \
   ^
net/netfilter/nf_conntrack_core.c:674:2: note: in expansion of macro ‘cmpxchg’
  cmpxchg(&nf_conntrack_hash_rnd, 0, rand);

[Modified to use the current underlying implementation as current
mainline for both cmpxchg() and cmpxchg_local() does -- broonie]

Signed-off-by: Mark Hambleton <mahamble@...adcom.com>
Signed-off-by: Mark Brown <broonie@...aro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/arm64/include/asm/cmpxchg.h | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
index 7b4aaf067a48..a03583d47b34 100644
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -163,17 +163,23 @@ static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
 	return ret;
 }
 
-#define cmpxchg(ptr,o,n)						\
-	((__typeof__(*(ptr)))__cmpxchg_mb((ptr),			\
-					  (unsigned long)(o),		\
-					  (unsigned long)(n),		\
-					  sizeof(*(ptr))))
-
-#define cmpxchg_local(ptr,o,n)						\
-	((__typeof__(*(ptr)))__cmpxchg((ptr),				\
-				       (unsigned long)(o),		\
-				       (unsigned long)(n),		\
-				       sizeof(*(ptr))))
+#define cmpxchg(ptr, o, n) \
+({ \
+	__typeof__(*(ptr)) __ret; \
+	__ret = (__typeof__(*(ptr))) \
+		__cmpxchg_mb((ptr), (unsigned long)(o), (unsigned long)(n), \
+			     sizeof(*(ptr))); \
+	__ret; \
+})
+
+#define cmpxchg_local(ptr, o, n) \
+({ \
+	__typeof__(*(ptr)) __ret; \
+	__ret = (__typeof__(*(ptr))) \
+		__cmpxchg((ptr), (unsigned long)(o), \
+			  (unsigned long)(n), sizeof(*(ptr))); \
+	__ret; \
+})
 
 #define cmpxchg64(ptr,o,n)		cmpxchg((ptr),(o),(n))
 #define cmpxchg64_local(ptr,o,n)	cmpxchg_local((ptr),(o),(n))
-- 
2.4.6

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