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Commit 44086d52 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
Browse files

alpha: lock bitops 



Alpha can avoid one mb when acquiring a lock with test_and_set_bit_lock.

[bunk@kernel.org: alpha bitops.h must #include <asm/barrier.h>]
Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: default avatarAdrian Bunk <bunk@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7c29ca5b

include/asm-alpha/bitops.h

+42 −1
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#define _ALPHA_BITOPS_H



#include <asm/compiler.h>

#include <asm/barrier.h>



/*

 * Copyright 1994, Linus Torvalds.
@@ -69,6 +70,13 @@ clear_bit(unsigned long nr, volatile void * addr) 
	:"Ir" (1UL << (nr & 31)), "m" (*m));

}



static inline void

clear_bit_unlock(unsigned long nr, volatile void * addr)

{

	smp_mb();

	clear_bit(nr, addr);

}



/*

 * WARNING: non atomic version.

 */
@@ -80,6 +88,13 @@ __clear_bit(unsigned long nr, volatile void * addr) 
	*m &= ~(1 << (nr & 31));

}



static inline void

__clear_bit_unlock(unsigned long nr, volatile void * addr)

{

	smp_mb();

	__clear_bit(nr, addr);

}



static inline void

change_bit(unsigned long nr, volatile void * addr)

{
@@ -139,6 +154,33 @@ test_and_set_bit(unsigned long nr, volatile void *addr) 
	return oldbit != 0;

}



static inline int

test_and_set_bit_lock(unsigned long nr, volatile void *addr)

{

	unsigned long oldbit;

	unsigned long temp;

	int *m = ((int *) addr) + (nr >> 5);



	__asm__ __volatile__(

	"1:	ldl_l %0,%4\n"

	"	and %0,%3,%2\n"

	"	bne %2,2f\n"

	"	xor %0,%3,%0\n"

	"	stl_c %0,%1\n"

	"	beq %0,3f\n"

	"2:\n"

#ifdef CONFIG_SMP

	"	mb\n"

#endif

	".subsection 2\n"

	"3:	br 1b\n"

	".previous"

	:"=&r" (temp), "=m" (*m), "=&r" (oldbit)

	:"Ir" (1UL << (nr & 31)), "m" (*m) : "memory");



	return oldbit != 0;

}



/*

 * WARNING: non atomic version.

 */
@@ -376,7 +418,6 @@ static inline unsigned int hweight8(unsigned int w) 
#else

#include <asm-generic/bitops/hweight.h>

#endif

#include <asm-generic/bitops/lock.h>



#endif /* __KERNEL__ */