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Commit 6dc25876 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

locking/atomic, arch/xtensa: 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>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
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
Cc: linux-xtensa@linux-xtensa.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a8bcccab

arch/xtensa/include/asm/atomic.h

+50 −4
Original line number Diff line number Diff line
@@ -98,6 +98,26 @@ static inline int atomic_##op##_return(int i, atomic_t * v) \ 
	return result;							\

}



#define ATOMIC_FETCH_OP(op)						\

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

{									\

	unsigned long tmp;						\

	int result;							\

									\

	__asm__ __volatile__(						\

			"1:     l32i    %1, %3, 0\n"			\

			"       wsr     %1, scompare1\n"		\

			"       " #op " %0, %1, %2\n"			\

			"       s32c1i  %0, %3, 0\n"			\

			"       bne     %0, %1, 1b\n"			\

			: "=&a" (result), "=&a" (tmp)			\

			: "a" (i), "a" (v)				\

			: "memory"					\

			);						\

									\

	return result;							\

}



#else /* XCHAL_HAVE_S32C1I */



#define ATOMIC_OP(op)							\
@@ -138,18 +158,44 @@ static inline int atomic_##op##_return(int i, atomic_t * v) \ 
	return vval;							\

}



#define ATOMIC_FETCH_OP(op)						\

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

{									\

	unsigned int tmp, vval;						\

									\

	__asm__ __volatile__(						\

			"       rsil    a15,"__stringify(TOPLEVEL)"\n"	\

			"       l32i    %0, %3, 0\n"			\

			"       " #op " %1, %0, %2\n"			\

			"       s32i    %1, %3, 0\n"			\

			"       wsr     a15, ps\n"			\

			"       rsync\n"				\

			: "=&a" (vval), "=&a" (tmp)			\

			: "a" (i), "a" (v)				\

			: "a15", "memory"				\

			);						\

									\

	return vval;							\

}



#endif /* XCHAL_HAVE_S32C1I */



#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)

#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op) ATOMIC_OP_RETURN(op)



ATOMIC_OPS(add)

ATOMIC_OPS(sub)



ATOMIC_OP(and)

ATOMIC_OP(or)

ATOMIC_OP(xor)

#undef ATOMIC_OPS

#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(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_RETURN

#undef ATOMIC_OP