| Nick Piggin | 2633357 | 2007-10-18 03:06:39 -0700 | [diff] [blame] | 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_clear_bit(); \ |
| 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 | |