| Message ID | 1398871386-27311-1-git-send-email-will.deacon@arm.com |
|---|---|
| State | New |
| Headers | show |
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)
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> --- arch/arm64/include/asm/cmpxchg.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)