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Commit 5302ac50 authored by Zoltan Menyhart's avatar Zoltan Menyhart Committed by Tony Luck
Browse files

[IA64] Slim-down __clear_bit_unlock 



- 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: default avatarZoltan Menyhart, <Zoltan.Menyhart@bull.net>
Acked-by: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 97075c4b

include/asm-ia64/bitops.h

+28 −22
Original line number Diff line number Diff line
@@ -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)