[SPARC]: Emulate cmpxchg like parisc
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/lib/atomic32.c b/arch/sparc/lib/atomic32.c
index 559335f..617d298 100644
--- a/arch/sparc/lib/atomic32.c
+++ b/arch/sparc/lib/atomic32.c
@@ -2,6 +2,7 @@
* atomic32.c: 32-bit atomic_t implementation
*
* Copyright (C) 2004 Keith M Wesolowski
+ * Copyright (C) 2007 Kyle McMartin
*
* Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
*/
@@ -117,3 +118,17 @@
return old & mask;
}
EXPORT_SYMBOL(___change_bit);
+
+unsigned long __cmpxchg_u32(volatile u32 *ptr, u32 old, u32 new)
+{
+ unsigned long flags;
+ u32 prev;
+
+ spin_lock_irqsave(ATOMIC_HASH(addr), flags);
+ if ((prev = *ptr) == old)
+ *ptr = new;
+ spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);
+
+ return (unsigned long)prev;
+}
+EXPORT_SYMBOL(__cmpxchg_u32);