Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=5302ac5019367470e123cb91844a28d6941e6912
Commit: 5302ac5019367470e123cb91844a28d6941e6912
Parent: 97075c4b3b7fdd6a083eea075c3a4a601f0d64d8
Author: Zoltan Menyhart <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 4 15:19:16 2008 -0800
Committer: Tony Luck <[EMAIL PROTECTED]>
CommitDate: Mon Feb 4 15:19:16 2008 -0800
[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: Zoltan Menyhart, <[EMAIL PROTECTED]>
Acked-by: Nick Piggin <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Tony Luck <[EMAIL PROTECTED]>
---
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 a1b9719..953d3df 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)
-
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