spapr_drc: fix realize and unrealize

If object_property_add_alias() returns an error in realize(), we should
propagate it to the caller and certainly not unref the DRC.

Same thing goes for unrealize(). Since object_property_del() is the last
call, we can even get rid of the intermediate Error *.

And finally, unrealize() should undo all registrations performed by
realize().
Signed-off-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr_drc.c

@@ -506,11 +506,11 @@ static void realize(DeviceState *d, Error **errp)
     trace_spapr_drc_realize_child(spapr_drc_index(drc), child_name);
     object_property_add_alias(root_container, link_name,
                               drc->owner, child_name, &err);
+    g_free(child_name);
     if (err) {
-        error_report_err(err);
-        object_unref(OBJECT(drc));
+        error_propagate(errp, err);
+        return;
     }
-    g_free(child_name);
     vmstate_register(DEVICE(drc), spapr_drc_index(drc), &vmstate_spapr_drc,
                      drc);
     qemu_register_reset(drc_reset, drc);
@@ -522,16 +522,13 @@ static void unrealize(DeviceState *d, Error **errp)
     sPAPRDRConnector *drc = SPAPR_DR_CONNECTOR(d);
     Object *root_container;
     char name[256];
-    Error *err = NULL;
 
     trace_spapr_drc_unrealize(spapr_drc_index(drc));
+    qemu_unregister_reset(drc_reset, drc);
+    vmstate_unregister(DEVICE(drc), &vmstate_spapr_drc, drc);
     root_container = container_get(object_get_root(), DRC_CONTAINER_PATH);
     snprintf(name, sizeof(name), "%x", spapr_drc_index(drc));
-    object_property_del(root_container, name, &err);
-    if (err) {
-        error_report_err(err);
-        object_unref(OBJECT(drc));
-    }
+    object_property_del(root_container, name, errp);
 }
 
 sPAPRDRConnector *spapr_dr_connector_new(Object *owner, const char *type,