| #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_atomic(); \ |
| 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_ */ |
| |
