#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_ */