Index: sys/sys/refcount.h
===================================================================
--- sys/sys/refcount.h
+++ sys/sys/refcount.h
@@ -77,14 +77,20 @@
 }
 
 /*
+ * This functions returns non-zero if the refcount was
+ * incremented. Else zero is returned.
+ *
  * A temporary hack until refcount_* APIs are sorted out.
  */
-static __inline int
+static __inline __result_use_check int
 refcount_acquire_if_not_zero(volatile u_int *count)
 {
 	u_int old;
 
 	old = *count;
+
+	KASSERT(old < UINT_MAX, ("refcount %p overflowed", count));
+
 	for (;;) {
 		if (old == 0)
 			return (0);
@@ -93,7 +99,7 @@
 	}
 }
 
-static __inline int
+static __inline __result_use_check int
 refcount_release_if_not_last(volatile u_int *count)
 {
 	u_int old;