diff -r 595ef1ab007c -r 2089b7edcada linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
--- a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c	Tue Nov 15 14:44:59 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c	Tue Nov 15 16:43:02 2005
@@ -299,8 +299,8 @@
 
 	DPRINTK("state is %d, %s, %s",
 		state, dev->otherend_watch.node, vec[XS_WATCH_PATH]);
-
-	drv->otherend_changed(dev, state);
+	if (drv->otherend_changed)
+		drv->otherend_changed(dev, state);
 }