include/asm-generic/bitops/lock.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_GENERIC_BITOPS_LOCK_H_
   3 #define _ASM_GENERIC_BITOPS_LOCK_H_
   4
   5 /**
   6  * test_and_set_bit_lock - Set a bit and return its old value, for lock
   7  * @nr: Bit to set
   8  * @addr: Address to count from
   9  *
  10  * This operation is atomic and provides acquire barrier semantics if
  11  * the returned value is 0.
  12  * It can be used to implement bit locks.
  13  */
  14 #define test_and_set_bit_lock(nr, addr) test_and_set_bit(nr, addr)
  15
  16 /**
  17  * clear_bit_unlock - Clear a bit in memory, for unlock
  18  * @nr: the bit to set
  19  * @addr: the address to start counting from
  20  *
  21  * This operation is atomic and provides release barrier semantics.
  22  */
  23 #define clear_bit_unlock(nr, addr)      \
  24 do {                                    \
  25         smp_mb__before_atomic();        \
  26         clear_bit(nr, addr);            \
  27 } while (0)
  28
  29 /**
  30  * __clear_bit_unlock - Clear a bit in memory, for unlock
  31  * @nr: the bit to set
  32  * @addr: the address to start counting from
  33  *
  34  * A weaker form of clear_bit_unlock() as used by __bit_lock_unlock(). If all
  35  * the bits in the word are protected by this lock some archs can use weaker
  36  * ops to safely unlock.
  37  *
  38  * See for example x86's implementation.
  39  */
  40 #define __clear_bit_unlock(nr, addr)    \
  41 do {                                    \
  42         smp_mb__before_atomic();        \
  43         clear_bit(nr, addr);            \
  44 } while (0)
  45
  46 #endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
  47