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Commit e6790e4b authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter 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: default avatarIngo Molnar <mingo@kernel.org>
parent b78c0d47

arch/x86/include/asm/atomic.h

+9 −18
Original line number Diff line number Diff line
@@ -209,14 +209,10 @@ 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)			\

{									\

	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;

}

arch/x86/include/asm/atomic64_64.h

+13 −27
Original line number Diff line number Diff line
@@ -198,17 +198,12 @@ static inline long atomic64_xchg(atomic64_t *v, long new) 
 */

static inline bool atomic64_add_unless(atomic64_t *v, long a, long u)

{

	long c, old;

	c = atomic64_read(v);

	for (;;) {

		if (unlikely(c == (u)))

			break;

		old = atomic64_cmpxchg((v), c, c + (a));

		if (likely(old == c))

			break;

		c = old;

	}

	return c != (u);

	long c = atomic64_read(v);

	do {

		if (unlikely(c == u))

			return false;

	} while (!atomic64_try_cmpxchg(v, &c, c + a));

	return true;

}



#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
@@ -222,17 +217,12 @@ static inline bool atomic64_add_unless(atomic64_t *v, long a, long u) 
 */

static inline long atomic64_dec_if_positive(atomic64_t *v)

{

	long c, old, dec;

	c = atomic64_read(v);

	for (;;) {

	long dec, c = atomic64_read(v);

	do {

		dec = c - 1;

		if (unlikely(dec < 0))

			break;

		old = atomic64_cmpxchg((v), c, dec);

		if (likely(old == c))

			break;

		c = old;

	}

	} while (!atomic64_try_cmpxchg(v, &c, dec));

	return dec;

}
@@ -248,14 +238,10 @@ static inline void atomic64_##op(long i, atomic64_t *v) \ 
#define ATOMIC64_FETCH_OP(op, c_op)					\

static inline long atomic64_fetch_##op(long i, atomic64_t *v)		\

{									\

	long old, val = atomic64_read(v);				\

	for (;;) {							\

		old = atomic64_cmpxchg(v, val, val c_op i);		\

		if (old == val)						\

			break;						\

		val = old;						\

	}								\

	return old;							\

	long val = atomic64_read(v);					\

	do {								\

	} while (!atomic64_try_cmpxchg(v, &val, val c_op i));		\

	return val;							\

}



#define ATOMIC64_OPS(op, c_op)						\