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| author | Will Deacon <will.deacon@arm.com> | 2014-04-30 16:23:06 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2014-05-09 17:00:00 +0100 |
| commit | e1dfda9ced9bea1413a736f0d578f8218a7788ec (patch) | |
| tree | f78c6b760a585d8efacaff2249105f73ed60d90a | |
| parent | 206a2a73a62d37c8b8f6ddd3180c202b2e7298ab (diff) | |
| download | linux-e1dfda9ced9bea1413a736f0d578f8218a7788ec.tar.bz2 | |
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>
| -rw-r--r-- | arch/arm64/include/asm/cmpxchg.h | 7 |
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) |