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/include/asm-generic/bitops/lock.h

https://bitbucket.org/thekraven/iscream_thunderc-2.6.35
C++ Header | 45 lines | 14 code | 5 blank | 26 comment | 2 complexity | db2a1cd391d358f7ee5944b17c347a66 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
 1#ifndef _ASM_GENERIC_BITOPS_LOCK_H_
 2#define _ASM_GENERIC_BITOPS_LOCK_H_
 3
 4/**
 5 * test_and_set_bit_lock - Set a bit and return its old value, for lock
 6 * @nr: Bit to set
 7 * @addr: Address to count from
 8 *
 9 * This operation is atomic and provides acquire barrier semantics.
10 * It can be used to implement bit locks.
11 */
12#define test_and_set_bit_lock(nr, addr)	test_and_set_bit(nr, addr)
13
14/**
15 * clear_bit_unlock - Clear a bit in memory, for unlock
16 * @nr: the bit to set
17 * @addr: the address to start counting from
18 *
19 * This operation is atomic and provides release barrier semantics.
20 */
21#define clear_bit_unlock(nr, addr)	\
22do {					\
23	smp_mb__before_clear_bit();	\
24	clear_bit(nr, addr);		\
25} while (0)
26
27/**
28 * __clear_bit_unlock - Clear a bit in memory, for unlock
29 * @nr: the bit to set
30 * @addr: the address to start counting from
31 *
32 * This operation is like clear_bit_unlock, however it is not atomic.
33 * It does provide release barrier semantics so it can be used to unlock
34 * a bit lock, however it would only be used if no other CPU can modify
35 * any bits in the memory until the lock is released (a good example is
36 * if the bit lock itself protects access to the other bits in the word).
37 */
38#define __clear_bit_unlock(nr, addr)	\
39do {					\
40	smp_mb();			\
41	__clear_bit(nr, addr);		\
42} while (0)
43
44#endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
45