On Sat, Mar 25, 2017 at 11:34:32AM -0700, Linus Torvalds wrote:
> On Sat, Mar 25, 2017 at 11:28 AM, Linus Torvalds
> <torva...@linux-foundation.org> wrote:
> >
> > Hmm. Sad. The label approach looked like it would match the semantics
> > of cmpxchg perfectly, but it's not as optimal as it superficially
> > would have seemed.
>
> Oh, I just noticed that at least your other one didn't mark "success"
> as being likely.
10730509 4540256 843776 16114541 f5e36d defconfig-build/vmlinux
---
arch/x86/include/asm/cmpxchg.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
index fb961db..d347abc 100644
--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -212,8 +212,9 @@ extern void __add_wrong_size(void)
default: \
__cmpxchg_wrong_size(); \
} \
+ if (unlikely(!success)) \
*_old = __old; \
- success; \
+ likely(success); \
})
#define __try_cmpxchg(ptr, pold, new, size) \
