On 07/16/2015 11:32 AM, Will Deacon wrote:
By defining our SMP atomics in terms of relaxed operations, we gain
a small reduction in code size and have acquire/release/fence variants
generated automatically by the core code.
Signed-off-by: Will Deacon<[email protected]>
---
arch/arm/include/asm/atomic.h | 37 ++++++++++++++-------------------
arch/arm/include/asm/cmpxchg.h | 47 +++++++-----------------------------------
2 files changed, 24 insertions(+), 60 deletions(-)
-#define xchg(ptr, x) ({
\
+#define xchg_relaxed(ptr, x) ({
\
(__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), \
sizeof(*(ptr))); \
})
@@ -117,6 +115,8 @@ static inline unsigned long __xchg(unsigned long x,
volatile void *ptr, int size
#error "SMP is not supported on this platform"
#endif
+#define xchg xchg_relaxed
Is that a typo? I think xchg() needs to be a full memory barrier.
Cheers,
Longman
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