+static inline void backend_switch_state(struct backend_info *be,
+ enum xenbus_state state)
+{
+ struct xenbus_device *dev = be->dev;
+
+ pr_debug("%s -> %s\n", dev->nodename, xenbus_strstate(state));
+ be->state = state;
+
+ /* If we are waiting for a hotplug script then defer the
+ * actual xenbus state change.
+ */
+ if (!be->have_hotplug_status_watch)
+ xenbus_switch_state(dev, state);
+}
+
+/* Handle backend state transitions:
+ *
+ * The backend state starts in InitWait and the following transitions are
+ * allowed.
+ *
+ * InitWait -> Connected
+ *
+ * ^ \ |
+ * | \ |
+ * | \ |
+ * | \ |
+ * | \ |
+ * | \ |
+ * | V V
+ *
+ * Closed <-> Closing
+ *
+ * The state argument specifies the eventual state of the backend and the
+ * function transitions to that state via the shortest path.
+ */
+static void set_backend_state(struct backend_info *be,
+ enum xenbus_state state)
+{
+ while (be->state != state) {
+ switch (be->state) {
+ case XenbusStateClosed:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateConnected:
+ pr_info("%s: prepare for reconnect\n",
+ be->dev->nodename);
+ backend_switch_state(be, XenbusStateInitWait);
+ break;
+ case XenbusStateClosing:
+ backend_switch_state(be, XenbusStateClosing);
+ break;
+ default:
+ BUG();
+ }
+ break;
+ case XenbusStateInitWait:
+ switch (state) {
+ case XenbusStateConnected:
+ backend_connect(be);
+ backend_switch_state(be, XenbusStateConnected);
+ break;
+ case XenbusStateClosing:
+ case XenbusStateClosed:
+ backend_switch_state(be, XenbusStateClosing);
+ break;
+ default:
+ BUG();
+ }
+ break;
+ case XenbusStateConnected:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateClosing:
+ case XenbusStateClosed:
+ backend_disconnect(be);
+ backend_switch_state(be, XenbusStateClosing);
+ break;
+ default:
+ BUG();
+ }
+ break;
+ case XenbusStateClosing:
+ switch (state) {
+ case XenbusStateInitWait:
+ case XenbusStateConnected:
+ case XenbusStateClosed:
+ backend_switch_state(be, XenbusStateClosed);
+ break;
+ default:
+ BUG();
+ }
+ break;
+ default:
+ BUG();
+ }