[PATCH] atomic: cmpxchg
Introduce an atomic_cmpxchg operation.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-arm26/atomic.h b/include/asm-arm26/atomic.h
index 4a88235..54b24ea 100644
--- a/include/asm-arm26/atomic.h
+++ b/include/asm-arm26/atomic.h
@@ -62,6 +62,20 @@
return val;
}
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+ int ret;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ ret = v->counter;
+ if (likely(ret == old))
+ v->counter = new;
+ local_irq_restore(flags);
+
+ return ret;
+}
+
static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
{
unsigned long flags;