lock.h
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#ifndef _ASM_GENERIC_BITOPS_LOCK_H_
#define _ASM_GENERIC_BITOPS_LOCK_H_
/**
* test_and_set_bit_lock - Set a bit and return its old value, for lock
* @nr: Bit to set
* @addr: Address to count from
*
* This operation is atomic and provides acquire barrier semantics.
* It can be used to implement bit locks.
*/
#define test_and_set_bit_lock(nr, addr) test_and_set_bit(nr, addr)
/**
* clear_bit_unlock - Clear a bit in memory, for unlock
* @nr: the bit to set
* @addr: the address to start counting from
*
* This operation is atomic and provides release barrier semantics.
*/
#define clear_bit_unlock(nr, addr) \
do { \
smp_mb__before_clear_bit(); \
clear_bit(nr, addr); \
} while (0)
/**
* __clear_bit_unlock - Clear a bit in memory, for unlock
* @nr: the bit to set
* @addr: the address to start counting from
*
* This operation is like clear_bit_unlock, however it is not atomic.
* It does provide release barrier semantics so it can be used to unlock
* a bit lock, however it would only be used if no other CPU can modify
* any bits in the memory until the lock is released (a good example is
* if the bit lock itself protects access to the other bits in the word).
*/
#define __clear_bit_unlock(nr, addr) \
do { \
smp_mb(); \
__clear_bit(nr, addr); \
} while (0)
#endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */