[PATCH] ARM: include: asm: atomic.h: use type cast 's64' for the return value of atomic64_add_return().
From: Russell King - ARM Linux <hidden>
Date: 2013-09-24 10:27:36
On Tue, Sep 24, 2013 at 10:30:41AM +0100, Will Deacon wrote:
On Sat, Sep 21, 2013 at 12:06:47PM +0100, Chen Gang wrote:quoted
diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h index da1c77d..8cf005d 100644 --- a/arch/arm/include/asm/atomic.h +++ b/arch/arm/include/asm/atomic.h@@ -475,7 +475,7 @@ static inline int atomic64_add_unless(atomic64_t *v, u64 a, u64 u) return ret; } -#define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0) +#define atomic64_add_negative(a, v) ((s64)atomic64_add_return((a), (v)) < 0) #define atomic64_inc(v) atomic64_add(1LL, (v)) #define atomic64_inc_return(v) atomic64_add_return(1LL, (v)) #define atomic64_inc_and_test(v) (atomic64_inc_return(v) == 0)Is this the right fix? It looks more like atomic[64]_t should be signed, but some 32-bit architectures (ARM, x86, tile) are actually implementing atomic64_t as u64. Furthermore, there are discrepencies in the operands to the various atomic64_* function (long long vs u64) which probably need sorting out.
Even though our underlying type is u64, we could change the arguments to be 'long long' as per the asm-generic/atomic64.h version. Remember that this is ARM specific code, and we know that long long == 64-bit int.