Is this the final take on this ... or was there a newer better faster cleaner
version?
-Tony
-----Original Message-----
From: Christoph Lameter [mailto:clameter@xxxxxxx]
Sent: Friday, October 19, 2007 10:54 AM
To: Luck, Tony
Cc: linux-ia64@xxxxxxxxxxxxxxx; Zoltan Menyhart
Subject: [IA64] Effective __clear_bit_unlock V2
Avoid the use of cmpxchg in __clear_bit_unlock by calling __clear_bit.
__clear_bit uses a volatile pointer and will generate a store with
release semantics as shown by Zoltan. Add a barrier to make sure that
the compiler does not reorder instructions around it.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Acked-by: Nick Piggin <npiggin@xxxxxxx>
---
include/asm-ia64/bitops.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
Index: linux-2.6/include/asm-ia64/bitops.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/bitops.h 2007-10-19 04:05:38.000000000 -0700
+++ linux-2.6/include/asm-ia64/bitops.h 2007-10-19 10:50:34.000000000 -0700
@@ -118,14 +118,6 @@ clear_bit_unlock (int nr, volatile void
}
/**
- * __clear_bit_unlock - Non-atomically clear a bit with release
- *
- * This is like clear_bit_unlock, but the implementation may use a non-atomic
- * store (this one uses an atomic, however).
- */
-#define __clear_bit_unlock clear_bit_unlock
-
-/**
* __clear_bit - Clears a bit in memory (non-atomic version)
*/
static __inline__ void
@@ -137,6 +129,16 @@ __clear_bit (int nr, volatile void *addr
}
/**
+ * __clear_bit_unlock - Non-atomically clear a bit with release
+ */
+static __inline__ void
+__clear_bit_unlock (int nr, volatile void *addr)
+{
+ barrier();
+ __clear_bit(nr, addr);
+}
+
+/**
* change_bit - Toggle a bit in memory
* @nr: Bit to clear
* @addr: Address to start counting from
-
To unsubscribe from this list: send the line "unsubscribe linux-ia64" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|