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authorWill Deacon <will.deacon@arm.com>2014-04-30 16:23:06 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2014-05-09 17:00:00 +0100
commite1dfda9ced9bea1413a736f0d578f8218a7788ec (patch)
treef78c6b760a585d8efacaff2249105f73ed60d90a /arch/arm64
parent206a2a73a62d37c8b8f6ddd3180c202b2e7298ab (diff)
arm64: xchg: prevent warning if return value is unused
Some users of xchg() don't bother using the return value, which results in a compiler warning like the following (from kgdb): In file included from linux/arch/arm64/include/asm/atomic.h:27:0, from include/linux/atomic.h:4, from include/linux/spinlock.h:402, from include/linux/seqlock.h:35, from include/linux/time.h:5, from include/uapi/linux/timex.h:56, from include/linux/timex.h:56, from include/linux/sched.h:19, from include/linux/pid_namespace.h:4, from kernel/debug/debug_core.c:30: kernel/debug/debug_core.c: In function ‘kgdb_cpu_enter’: linux/arch/arm64/include/asm/cmpxchg.h:75:3: warning: value computed is not used [-Wunused-value] ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr)))) ^ linux/arch/arm64/include/asm/atomic.h:132:30: note: in expansion of macro ‘xchg’ #define atomic_xchg(v, new) (xchg(&((v)->counter), new)) kernel/debug/debug_core.c:504:4: note: in expansion of macro ‘atomic_xchg’ atomic_xchg(&kgdb_active, cpu); ^ This patch makes use of the same trick as we do for cmpxchg, by assigning the return value to a dummy variable in the xchg() macro itself. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/include/asm/cmpxchg.h7
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h
index 57c0fa7bf711..ddb9d7830558 100644
--- a/arch/arm64/include/asm/cmpxchg.h
+++ b/arch/arm64/include/asm/cmpxchg.h
@@ -72,7 +72,12 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size
}
#define xchg(ptr,x) \
- ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
+({ \
+ __typeof__(*(ptr)) __ret; \
+ __ret = (__typeof__(*(ptr))) \
+ __xchg((unsigned long)(x), (ptr), sizeof(*(ptr))); \
+ __ret; \
+})
static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
unsigned long new, int size)