locking/atomic/x86: Use atomic_try_cmpxchg()
Better code generation:
text data bss name
10665111 4530096 843776 defconfig-build/vmlinux.3
10655703 4530096 843776 defconfig-build/vmlinux.4
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index 8410377..caa5798 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -207,16 +207,12 @@ static inline void atomic_##op(int i, atomic_t *v) \
}
#define ATOMIC_FETCH_OP(op, c_op) \
-static inline int atomic_fetch_##op(int i, atomic_t *v) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
{ \
- int old, val = atomic_read(v); \
- for (;;) { \
- old = atomic_cmpxchg(v, val, val c_op i); \
- if (old == val) \
- break; \
- val = old; \
- } \
- return old; \
+ int val = atomic_read(v); \
+ do { \
+ } while (!atomic_try_cmpxchg(v, &val, val c_op i)); \
+ return val; \
}
#define ATOMIC_OPS(op, c_op) \
@@ -242,16 +238,11 @@ ATOMIC_OPS(xor, ^)
*/
static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == (u)))
+ int c = atomic_read(v);
+ do {
+ if (unlikely(c == u))
break;
- old = atomic_cmpxchg((v), c, c + (a));
- if (likely(old == c))
- break;
- c = old;
- }
+ } while (!atomic_try_cmpxchg(v, &c, c + a));
return c;
}