diff options
| -rw-r--r-- | include/asm-ia64/bitops.h | 50 |
1 files changed, 28 insertions, 22 deletions
diff --git a/include/asm-ia64/bitops.h b/include/asm-ia64/bitops.h index a1b9719f5fbb..953d3df9dd22 100644 --- a/include/asm-ia64/bitops.h +++ b/include/asm-ia64/bitops.h @@ -122,38 +122,40 @@ clear_bit_unlock (int nr, volatile void *addr) } /** - * __clear_bit_unlock - Non-atomically clear a bit with release + * __clear_bit_unlock - Non-atomically clears a bit in memory with release + * @nr: Bit to clear + * @addr: Address to start counting from * - * This is like clear_bit_unlock, but the implementation uses a store + * Similarly to clear_bit_unlock, the implementation uses a store * with release semantics. See also __raw_spin_unlock(). */ static __inline__ void -__clear_bit_unlock(int nr, volatile void *addr) +__clear_bit_unlock(int nr, void *addr) { - __u32 mask, new; - volatile __u32 *m; + __u32 * const m = (__u32 *) addr + (nr >> 5); + __u32 const new = *m & ~(1 << (nr & 31)); - m = (volatile __u32 *)addr + (nr >> 5); - mask = ~(1 << (nr & 31)); - new = *m & mask; - barrier(); ia64_st4_rel_nta(m, new); } /** * __clear_bit - Clears a bit in memory (non-atomic version) + * @nr: the bit to clear + * @addr: the address to start counting from + * + * Unlike clear_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. */ static __inline__ void __clear_bit (int nr, volatile void *addr) { - volatile __u32 *p = (__u32 *) addr + (nr >> 5); - __u32 m = 1 << (nr & 31); - *p &= ~m; + *((__u32 *) addr + (nr >> 5)) &= ~(1 << (nr & 31)); } /** * change_bit - Toggle a bit in memory - * @nr: Bit to clear + * @nr: Bit to toggle * @addr: Address to start counting from * * change_bit() is atomic and may not be reordered. @@ -178,7 +180,7 @@ change_bit (int nr, volatile void *addr) /** * __change_bit - Toggle a bit in memory - * @nr: the bit to set + * @nr: the bit to toggle * @addr: the address to start counting from * * Unlike change_bit(), this function is non-atomic and may be reordered. @@ -197,7 +199,7 @@ __change_bit (int nr, volatile void *addr) * @addr: Address to count from * * This operation is atomic and cannot be reordered. - * It also implies a memory barrier. + * It also implies the acquisition side of the memory barrier. */ static __inline__ int test_and_set_bit (int nr, volatile void *addr) @@ -247,11 +249,11 @@ __test_and_set_bit (int nr, volatile void *addr) /** * test_and_clear_bit - Clear a bit and return its old value - * @nr: Bit to set + * @nr: Bit to clear * @addr: Address to count from * * This operation is atomic and cannot be reordered. - * It also implies a memory barrier. + * It also implies the acquisition side of the memory barrier. */ static __inline__ int test_and_clear_bit (int nr, volatile void *addr) @@ -272,7 +274,7 @@ test_and_clear_bit (int nr, volatile void *addr) /** * __test_and_clear_bit - Clear a bit and return its old value - * @nr: Bit to set + * @nr: Bit to clear * @addr: Address to count from * * This operation is non-atomic and can be reordered. @@ -292,11 +294,11 @@ __test_and_clear_bit(int nr, volatile void * addr) /** * test_and_change_bit - Change a bit and return its old value - * @nr: Bit to set + * @nr: Bit to change * @addr: Address to count from * * This operation is atomic and cannot be reordered. - * It also implies a memory barrier. + * It also implies the acquisition side of the memory barrier. */ static __inline__ int test_and_change_bit (int nr, volatile void *addr) @@ -315,8 +317,12 @@ test_and_change_bit (int nr, volatile void *addr) return (old & bit) != 0; } -/* - * WARNING: non atomic version. +/** + * __test_and_change_bit - Change a bit and return its old value + * @nr: Bit to change + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. */ static __inline__ int __test_and_change_bit (int nr, void *addr) |
