LXR linux/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)      \
  22do {                                    \
  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 * A weaker form of clear_bit_unlock() as used by __bit_lock_unlock(). If all
  33 * the bits in the word are protected by this lock some archs can use weaker
  34 * ops to safely unlock.
  35 *
  36 * See for example x86's implementation.
  37 */
  38#define __clear_bit_unlock(nr, addr)    \
  39do {                                    \
  40        smp_mb__before_atomic();        \
  41        clear_bit(nr, addr);            \
  42} while (0)
  43
  44#endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
  45
  46