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Commit 1a6eafac authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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locking/atomic, arch/avr32: Implement atomic_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>
Acked-by: default avatarHans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
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 2efe95fe

arch/avr32/include/asm/atomic.h

+51 −5
Original line number Diff line number Diff line
@@ -41,21 +41,51 @@ static inline int __atomic_##op##_return(int i, atomic_t *v) \ 
	return result;							\

}



#define ATOMIC_FETCH_OP(op, asm_op, asm_con)				\

static inline int __atomic_fetch_##op(int i, atomic_t *v)		\

{									\

	int result, val;						\

									\

	asm volatile(							\

		"/* atomic_fetch_" #op " */\n"				\

		"1:	ssrf	5\n"					\

		"	ld.w	%0, %3\n"				\

		"	mov	%1, %0\n"				\

		"	" #asm_op "	%1, %4\n"			\

		"	stcond	%2, %1\n"				\

		"	brne	1b"					\

		: "=&r" (result), "=&r" (val), "=o" (v->counter)	\

		: "m" (v->counter), #asm_con (i)			\

		: "cc");						\

									\

	return result;							\

}



ATOMIC_OP_RETURN(sub, sub, rKs21)

ATOMIC_OP_RETURN(add, add, r)

ATOMIC_FETCH_OP (sub, sub, rKs21)

ATOMIC_FETCH_OP (add, add, r)



#define atomic_fetch_or atomic_fetch_or



#define ATOMIC_OP(op, asm_op)						\

#define ATOMIC_OPS(op, asm_op)						\

ATOMIC_OP_RETURN(op, asm_op, r)						\

static inline void atomic_##op(int i, atomic_t *v)			\

{									\

	(void)__atomic_##op##_return(i, v);				\

}									\

ATOMIC_FETCH_OP(op, asm_op, r)						\

static inline int atomic_fetch_##op(int i, atomic_t *v)		\

{									\

	return __atomic_fetch_##op(i, v);				\

}



ATOMIC_OP(and, and)

ATOMIC_OP(or, or)

ATOMIC_OP(xor, eor)

ATOMIC_OPS(and, and)

ATOMIC_OPS(or, or)

ATOMIC_OPS(xor, eor)



#undef ATOMIC_OP

#undef ATOMIC_OPS

#undef ATOMIC_FETCH_OP

#undef ATOMIC_OP_RETURN



/*
@@ -87,6 +117,14 @@ static inline int atomic_add_return(int i, atomic_t *v) 
	return __atomic_add_return(i, v);

}



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

{

	if (IS_21BIT_CONST(i))

		return __atomic_fetch_sub(-i, v);



	return __atomic_fetch_add(i, v);

}



/*

 * atomic_sub_return - subtract the atomic variable

 * @i: integer value to subtract
@@ -102,6 +140,14 @@ static inline int atomic_sub_return(int i, atomic_t *v) 
	return __atomic_add_return(-i, v);

}



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

{

	if (IS_21BIT_CONST(i))

		return __atomic_fetch_sub(i, v);



	return __atomic_fetch_add(-i, v);

}



/*

 * __atomic_add_unless - add unless the number is a given value

 * @v: pointer of type atomic_t