diff mbox

arm64: cmpxchg: update macros to prevent warnings

Message ID 1387543334-14036-1-git-send-email-broonie@kernel.org (mailing list archive)
State New, archived
Headers show

Commit Message

Mark Brown Dec. 20, 2013, 12:42 p.m. UTC 
From: Mark Hambleton <mahamble@broadcom.com>

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@broadcom.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
---
 arch/arm64/include/asm/cmpxchg.h | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

Comments

Catalin Marinas Dec. 20, 2013, 2:10 p.m. UTC | #1 
On Fri, Dec 20, 2013 at 12:42:14PM +0000, Mark Brown wrote:
> From: Mark Hambleton <mahamble@broadcom.com>
> 
> 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@broadcom.com>
> Signed-off-by: Mark Brown <broonie@linaro.org>

I merged the previous one (should be in -next as of last night), I guess
it's the same since the patch doesn't have a version number. But I
wonder whether uses of cmpxchg without checking the return value are
sane.
Mark Brown Dec. 20, 2013, 4:02 p.m. UTC | #2 
On Fri, Dec 20, 2013 at 02:10:02PM +0000, Catalin Marinas wrote:

> I merged the previous one (should be in -next as of last night), I guess
> it's the same since the patch doesn't have a version number. But I

It's the same patch, I was resending it because it had been a while with
no response.

> wonder whether uses of cmpxchg without checking the return value are
> sane.

IIRC it was used as part of another macro which did have some reasonable
uses without checking the return value.
diff mbox

Patch

diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
index 3914c0dcd09c..c558da59989e 100644
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -158,17 +158,23 @@  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))