include/asm-generic/bitops/lock.h

   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)      \
  22 do {                                    \
  23         smp_mb__before_atomic();        \
  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)    \
  39 do {                                    \
  40         smp_mb();                       \
  41         __clear_bit(nr, addr);          \
  42 } while (0)
  43
  44 #endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
  45