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Subject[PATCH] arm: cmpxchg: update macro to prevent compiler warning
Date
In kernel/acct.c we call the cmpxchg() macro without using it's
return value, so the compiler complains when compiling for ARM:

kernel/acct.c: In function 'acct_pin_kill':
arch/arm/include/asm/cmpxchg.h:205:3: warning: value computed is not used [-Wunused-value]
((__typeof__(*(ptr)))__cmpxchg_mb((ptr), \
^
kernel/acct.c:174:2: note: in expansion of macro 'cmpxchg'
cmpxchg(&acct->ns->bacct, pin, NULL);
^

Rearrange the macro along the lines of a similar patch for arm64
60010e508111 ("arm64: cmpxchg: update macros to prevent warnings")
to fix the warning.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Cc: Mark Hambleton <Mark.Hambleton@arm.com>
---
arch/arm/include/asm/cmpxchg.h | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h
index abb2c37..dc27aaf 100644
--- a/arch/arm/include/asm/cmpxchg.h
+++ b/arch/arm/include/asm/cmpxchg.h
@@ -201,11 +201,16 @@ 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(ptr, o, n) \
+({ \
+ __typeof__(*(ptr)) __ret; \
+ __ret = (__typeof__(*(ptr))) \
+ __cmpxchg_mb((ptr), \
+ (unsigned long)(o), \
+ (unsigned long)(n), \
+ sizeof(*(ptr))); \
+ __ret; \
+})

static inline unsigned long __cmpxchg_local(volatile void *ptr,
unsigned long old,
--
2.3.5


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