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[IA64] Slim-down __clear_bit_unlock

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- I removed the unnecessary barrier() from __clear_bit_unlock().
  ia64_st4_rel_nta() makes sure all the modifications are globally
  seen before the bit is seen to be off.
- I made __clear_bit() modeled after __set_bit() and __change_bit().
- I corrected some comments sating that a memory barrier is provided,
  yet in reality, it is the acquisition side of the memory barrier only.
- I corrected some comments, e.g. test_and_clear_bit() was peaking
  about "bit to set".

Signed-off-by: Zoltan Menyhart, <Zoltan.Menyhart@bull.net>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Zoltan Menyhart 2008-02-04 15:19:16 -08:00 committed by Tony Luck
parent 97075c4b3b
commit 5302ac5019
1 changed files with 28 additions and 22 deletions
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50
include/asm-ia64/bitops.h
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@ -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(). * with release semantics. See also __raw_spin_unlock().
*/ */
static __inline__ void static __inline__ void
__clear_bit_unlock(int nr, volatile void *addr) __clear_bit_unlock(int nr, void *addr)
{ {
__u32 mask, new; __u32 * const m = (__u32 *) addr + (nr >> 5);
volatile __u32 *m; __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); ia64_st4_rel_nta(m, new);
} }
/** /**
* __clear_bit - Clears a bit in memory (non-atomic version) * __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 static __inline__ void
__clear_bit (int nr, volatile void *addr) __clear_bit (int nr, volatile void *addr)
{ {
volatile __u32 *p = (__u32 *) addr + (nr >> 5); *((__u32 *) addr + (nr >> 5)) &= ~(1 << (nr & 31));
__u32 m = 1 << (nr & 31);
*p &= ~m;
} }
/** /**
* change_bit - Toggle a bit in memory * change_bit - Toggle a bit in memory
* @nr: Bit to clear * @nr: Bit to toggle
* @addr: Address to start counting from * @addr: Address to start counting from
* *
* change_bit() is atomic and may not be reordered. * 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 * __change_bit - Toggle a bit in memory
* @nr: the bit to set * @nr: the bit to toggle
* @addr: the address to start counting from * @addr: the address to start counting from
* *
* Unlike change_bit(), this function is non-atomic and may be reordered. * 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 * @addr: Address to count from
* *
* This operation is atomic and cannot be reordered. * 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 static __inline__ int
test_and_set_bit (int nr, volatile void *addr) 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 * 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 * @addr: Address to count from
* *
* This operation is atomic and cannot be reordered. * 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 static __inline__ int
test_and_clear_bit (int nr, volatile void *addr) 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 * __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 * @addr: Address to count from
* *
* This operation is non-atomic and can be reordered. * 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 * 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 * @addr: Address to count from
* *
* This operation is atomic and cannot be reordered. * 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 static __inline__ int
test_and_change_bit (int nr, volatile void *addr) 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; 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 static __inline__ int
__test_and_change_bit (int nr, void *addr) __test_and_change_bit (int nr, void *addr)