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Commit 728697cd authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
Browse files

mips: lock bitops 



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

Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c8f30ae5

include/asm-mips/bitops.h

+96 −1
Original line number Diff line number Diff line
@@ -171,6 +171,20 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr) 
	}

}



/*

 * clear_bit_unlock - Clears a bit in memory

 * @nr: Bit to clear

 * @addr: Address to start counting from

 *

 * clear_bit() is atomic and implies release semantics before the memory

 * operation. It can be used for an unlock.

 */

static inline void clear_bit_unlock(unsigned long nr, volatile unsigned long *addr)

{

	smp_mb__before_clear_bit();

	clear_bit(nr, addr);

}



/*

 * change_bit - Toggle a bit in memory

 * @nr: Bit to change
@@ -296,6 +310,73 @@ static inline int test_and_set_bit(unsigned long nr, 
	return res != 0;

}



/*

 * test_and_set_bit_lock - Set a bit and return its old value

 * @nr: Bit to set

 * @addr: Address to count from

 *

 * This operation is atomic and implies acquire ordering semantics

 * after the memory operation.

 */

static inline int test_and_set_bit_lock(unsigned long nr,

	volatile unsigned long *addr)

{

	unsigned short bit = nr & SZLONG_MASK;

	unsigned long res;



	if (cpu_has_llsc && R10000_LLSC_WAR) {

		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);

		unsigned long temp;



		__asm__ __volatile__(

		"	.set	mips3					\n"

		"1:	" __LL "%0, %1		# test_and_set_bit	\n"

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

		"	" __SC	"%2, %1					\n"

		"	beqzl	%2, 1b					\n"

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

		"	.set	mips0					\n"

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

		: "r" (1UL << bit), "m" (*m)

		: "memory");

	} else if (cpu_has_llsc) {

		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);

		unsigned long temp;



		__asm__ __volatile__(

		"	.set	push					\n"

		"	.set	noreorder				\n"

		"	.set	mips3					\n"

		"1:	" __LL "%0, %1		# test_and_set_bit	\n"

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

		"	" __SC	"%2, %1					\n"

		"	beqz	%2, 2f					\n"

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

		"	.subsection 2					\n"

		"2:	b	1b					\n"

		"	 nop						\n"

		"	.previous					\n"

		"	.set	pop					\n"

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

		: "r" (1UL << bit), "m" (*m)

		: "memory");

	} else {

		volatile unsigned long *a = addr;

		unsigned long mask;

		unsigned long flags;



		a += nr >> SZLONG_LOG;

		mask = 1UL << bit;

		raw_local_irq_save(flags);

		res = (mask & *a);

		*a |= mask;

		raw_local_irq_restore(flags);

	}



	smp_llsc_mb();



	return res != 0;

}

/*

 * test_and_clear_bit - Clear a bit and return its old value

 * @nr: Bit to clear
@@ -458,6 +539,21 @@ static inline int test_and_change_bit(unsigned long nr, 


#include <asm-generic/bitops/non-atomic.h>



/*

 * __clear_bit_unlock - Clears a bit in memory

 * @nr: Bit to clear

 * @addr: Address to start counting from

 *

 * __clear_bit() is non-atomic and implies release semantics before the memory

 * operation. It can be used for an unlock if no other CPUs can concurrently

 * modify other bits in the word.

 */

static inline void __clear_bit_unlock(unsigned long nr, volatile unsigned long *addr)

{

	smp_mb();

	__clear_bit(nr, addr);

}



/*

 * Return the bit position (0..63) of the most significant 1 bit in a word

 * Returns -1 if no 1 bit exists
@@ -562,7 +658,6 @@ static inline int ffs(int word) 


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

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

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

#include <asm-generic/bitops/ext2-non-atomic.h>

#include <asm-generic/bitops/ext2-atomic.h>

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