Index: refcount.h
===================================================================
RCS file: /usr/repo/src/sys/sys/refcount.h,v
retrieving revision 1.1
diff -u -p -r1.1 refcount.h
--- refcount.h	27 Sep 2005 18:01:33 -0000	1.1
+++ refcount.h	25 May 2008 22:10:26 -0000
@@ -32,6 +32,7 @@
 #ifndef __SYS_REFCOUNT_H__
 #define __SYS_REFCOUNT_H__
 
+#include <sys/systm.h>
 #include <machine/atomic.h>
 
 static __inline void
@@ -51,9 +52,12 @@ refcount_acquire(volatile u_int *count)
 static __inline int
 refcount_release(volatile u_int *count)
 {
+	u_int old;
 
 	/* XXX: Should this have a rel membar? */
-	return (atomic_fetchadd_int(count, -1) == 1);
+	old = atomic_fetchadd_int(count, -1);
+	KASSERT(old > 0, ("nagative refcount %p", count));
+	return (old == 1);
 }
 
 #endif	/* ! __SYS_REFCOUNT_H__ */