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Commit a8bcccab authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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locking/atomic, arch/x86: Implement atomic{,64}_fetch_{add,sub,and,or,xor}() 



Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.

This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
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-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 1af5de9a

arch/x86/include/asm/atomic.h

+34 −3
Original line number Diff line number Diff line
@@ -171,6 +171,16 @@ static __always_inline int atomic_sub_return(int i, atomic_t *v) 
#define atomic_inc_return(v)  (atomic_add_return(1, v))

#define atomic_dec_return(v)  (atomic_sub_return(1, v))



static __always_inline int atomic_fetch_add(int i, atomic_t *v)

{

	return xadd(&v->counter, i);

}



static __always_inline int atomic_fetch_sub(int i, atomic_t *v)

{

	return xadd(&v->counter, -i);

}



static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)

{

	return cmpxchg(&v->counter, old, new);
@@ -190,10 +200,31 @@ static inline void atomic_##op(int i, atomic_t *v) \ 
			: "memory");					\

}



ATOMIC_OP(and)

ATOMIC_OP(or)

ATOMIC_OP(xor)

#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;							\

}



#define ATOMIC_OPS(op, c_op)						\

	ATOMIC_OP(op)							\

	ATOMIC_FETCH_OP(op, c_op)



#define atomic_fetch_or atomic_fetch_or



ATOMIC_OPS(and, &)

ATOMIC_OPS(or , |)

ATOMIC_OPS(xor, ^)



#undef ATOMIC_OPS

#undef ATOMIC_FETCH_OP

#undef ATOMIC_OP



/**

arch/x86/include/asm/atomic64_32.h

+22 −3
Original line number Diff line number Diff line
@@ -320,10 +320,29 @@ static inline void atomic64_##op(long long i, atomic64_t *v) \ 
		c = old;						\

}



ATOMIC64_OP(and, &)

ATOMIC64_OP(or, |)

ATOMIC64_OP(xor, ^)

#define ATOMIC64_FETCH_OP(op, c_op)					\

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

{									\

	long long old, c = 0;						\

	while ((old = atomic64_cmpxchg(v, c, c c_op i)) != c)		\

		c = old;						\

	return old;							\

}



ATOMIC64_FETCH_OP(add, +)



#define atomic64_fetch_sub(i, v)	atomic64_fetch_add(-(i), (v))



#define ATOMIC64_OPS(op, c_op)						\

	ATOMIC64_OP(op, c_op)						\

	ATOMIC64_FETCH_OP(op, c_op)



ATOMIC64_OPS(and, &)

ATOMIC64_OPS(or, |)

ATOMIC64_OPS(xor, ^)



#undef ATOMIC64_OPS

#undef ATOMIC64_FETCH_OP

#undef ATOMIC64_OP



#endif /* _ASM_X86_ATOMIC64_32_H */

arch/x86/include/asm/atomic64_64.h

+32 −3
Original line number Diff line number Diff line
@@ -158,6 +158,16 @@ static inline long atomic64_sub_return(long i, atomic64_t *v) 
	return atomic64_add_return(-i, v);

}



static inline long atomic64_fetch_add(long i, atomic64_t *v)

{

	return xadd(&v->counter, i);

}



static inline long atomic64_fetch_sub(long i, atomic64_t *v)

{

	return xadd(&v->counter, -i);

}



#define atomic64_inc_return(v)  (atomic64_add_return(1, (v)))

#define atomic64_dec_return(v)  (atomic64_sub_return(1, (v)))
@@ -229,10 +239,29 @@ static inline void atomic64_##op(long i, atomic64_t *v) \ 
			: "memory");					\

}



ATOMIC64_OP(and)

ATOMIC64_OP(or)

ATOMIC64_OP(xor)

#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;							\

}



#define ATOMIC64_OPS(op, c_op)						\

	ATOMIC64_OP(op)							\

	ATOMIC64_FETCH_OP(op, c_op)



ATOMIC64_OPS(and, &)

ATOMIC64_OPS(or, |)

ATOMIC64_OPS(xor, ^)



#undef ATOMIC64_OPS

#undef ATOMIC64_FETCH_OP

#undef ATOMIC64_OP



#endif /* _ASM_X86_ATOMIC64_64_H */