[PATCH] arm64: cmpxchg: update macros to prevent warnings

[PATCH] arm64: cmpxchg: update macros to prevent warnings

[Mark Brown]

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(-)

diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
index 3914c0dcd09c..3f75fdb59447 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((ptr), (unsigned long)(o), (unsigned long)(n), \
+		sizeof(*(ptr))); \
+	__ret; \
+})
+
+#define cmpxchg_local(ptr, o, n) \
+({ \
+	__typeof__(*(ptr)) __ret; \
+	__ret = (__typeof__(*(ptr))) \
+	__cmpxchg_local((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))
-- 
1.8.5

[PATCH] arm64: cmpxchg: update macros to prevent warnings

[Mark Brown]

On Tue, Dec 03, 2013 at 07:15:27PM +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:

Sorry, I was missing a commit --amend here - resent with the correction
made.
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[PATCH] arm64: cmpxchg: update macros to prevent warnings

[Will Deacon]

On Tue, Dec 03, 2013 at 07:15:27PM +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>
> ---
>  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 3914c0dcd09c..3f75fdb59447 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((ptr), (unsigned long)(o), (unsigned long)(n), \
> +		sizeof(*(ptr))); \
> +	__ret; \
> +})
> +
> +#define cmpxchg_local(ptr, o, n) \
> +({ \
> +	__typeof__(*(ptr)) __ret; \
> +	__ret = (__typeof__(*(ptr))) \
> +	__cmpxchg_local((ptr), (unsigned long)(o), \
> +		(unsigned long)(n), sizeof(*(ptr))); \
> +	__ret; \
> +})

NAK.

This removes barrier semantics from cmpxchg and makes cmpxchg_local refer to
something which isn't defined anywhere, so the kernel doesn't even build.

Will

[PATCH] arm64: cmpxchg: update macros to prevent warnings

[Mark Brown]

On Wed, Dec 04, 2013 at 07:29:38PM +0000, Will Deacon wrote:

> This removes barrier semantics from cmpxchg and makes cmpxchg_local refer to
> something which isn't defined anywhere, so the kernel doesn't even build.

Yes, see the followup I sent to this last night (and the fixed version)
- I forgot to do the git add before I did the commit --amend to fix
them.
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[PATCH] arm64: cmpxchg: update macros to prevent warnings

[Mark Brown]

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(-)

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))
-- 
1.8.5

[PATCH] arm64: cmpxchg: update macros to prevent warnings

[Mark Brown]

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(-)

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))
-- 
1.8.5.2

[PATCH] arm64: cmpxchg: update macros to prevent warnings

[Catalin Marinas]

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.

-- 
Catalin

[PATCH] arm64: cmpxchg: update macros to prevent warnings

[Mark Brown]

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.
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