[XENBUS] Allow user of xenbus_read_driver_state() to distinguish

absence of state field in xenstore by returning XenbusStateUnknown
rather than XenbusStateClosed.
Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/drivers/char/tpm/tpm_xen.c

@@ -343,7 +343,6 @@ static void backend_changed(struct xenbus_device *dev,
 	case XenbusStateInitialising:
 	case XenbusStateInitWait:
 	case XenbusStateInitialised:
-	case XenbusStateUnknown:
 		break;
 
 	case XenbusStateConnected:
@@ -354,10 +353,10 @@ static void backend_changed(struct xenbus_device *dev,
 		tpmif_set_connected_state(tp, 0);
 		break;
 
+	case XenbusStateUnknown:
 	case XenbusStateClosed:
-		if (tp->is_suspended == 0) {
+		if (tp->is_suspended == 0)
 			device_unregister(&dev->dev);
-		}
 		xenbus_switch_state(dev, XenbusStateClosed);
 		break;
 	}

linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c

@@ -331,12 +331,11 @@ static void frontend_changed(struct xenbus_device *dev,
 		xenbus_switch_state(dev, XenbusStateClosing);
 		break;
 
+	case XenbusStateUnknown:
 	case XenbusStateClosed:
 		device_unregister(&dev->dev);
 		break;
 
-	case XenbusStateUnknown:
-	case XenbusStateInitWait:
 	default:
 		xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 				 frontend_state);

linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c

@@ -256,10 +256,10 @@ static void backend_changed(struct xenbus_device *dev,
 	DPRINTK("blkfront:backend_changed.\n");
 
 	switch (backend_state) {
-	case XenbusStateUnknown:
 	case XenbusStateInitialising:
 	case XenbusStateInitWait:
 	case XenbusStateInitialised:
+	case XenbusStateUnknown:
 	case XenbusStateClosed:
 		break;
 

linux-2.6-xen-sparse/drivers/xen/blktap/xenbus.c

@@ -267,12 +267,11 @@ static void tap_frontend_changed(struct xenbus_device *dev,
 		xenbus_switch_state(dev, XenbusStateClosing);
 		break;
 
+	case XenbusStateUnknown:
 	case XenbusStateClosed:
 		device_unregister(&dev->dev);
 		break;
 
-	case XenbusStateUnknown:
-	case XenbusStateInitWait:
 	default:
 		xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 				 frontend_state);

linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c

@@ -260,14 +260,13 @@ static void frontend_changed(struct xenbus_device *dev,
 		xenbus_switch_state(dev, XenbusStateClosing);
 		break;
 
+	case XenbusStateUnknown:
 	case XenbusStateClosed:
 		if (be->netif != NULL)
 			kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE);
 		device_unregister(&dev->dev);
 		break;
 
-	case XenbusStateUnknown:
-	case XenbusStateInitWait:
 	default:
 		xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 				 frontend_state);

linux-2.6-xen-sparse/drivers/xen/pciback/xenbus.c

@@ -181,6 +181,7 @@ static void pciback_frontend_changed(struct xenbus_device *xdev,
 		xenbus_switch_state(xdev, XenbusStateClosing);
 		break;
 
+	case XenbusStateUnknown:
 	case XenbusStateClosed:
 		dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 		device_unregister(&xdev->dev);

linux-2.6-xen-sparse/drivers/xen/pcifront/xenbus.c

@@ -225,6 +225,7 @@ static void pcifront_backend_changed(struct xenbus_device *xdev,
 		pcifront_try_disconnect(pdev);
 		break;
 
+	case XenbusStateUnknown:
 	case XenbusStateClosed:
 		dev_warn(&xdev->dev, "backend went away!\n");
 		pcifront_try_disconnect(pdev);

linux-2.6-xen-sparse/drivers/xen/tpmback/xenbus.c

@@ -34,7 +34,6 @@ struct backend_info
 
 	/* watch front end for changes */
 	struct xenbus_watch backend_watch;
-	enum xenbus_state frontend_state;
 };
 
 static void maybe_connect(struct backend_info *be);
@@ -143,8 +142,6 @@ static void frontend_changed(struct xenbus_device *dev,
 	struct backend_info *be = dev->dev.driver_data;
 	int err;
 
-	be->frontend_state = frontend_state;
-
 	switch (frontend_state) {
 	case XenbusStateInitialising:
 	case XenbusStateInitialised:
@@ -162,13 +159,12 @@ static void frontend_changed(struct xenbus_device *dev,
 		be->instance = -1;
 		break;
 
+	case XenbusStateUnknown:
 	case XenbusStateClosed:
 		device_unregister(&be->dev->dev);
 		tpmback_remove(dev);
 		break;
 
-	case XenbusStateUnknown:
-	case XenbusStateInitWait:
 	default:
 		xenbus_dev_fatal(dev, -EINVAL,
 				 "saw state %d at frontend",

linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_client.c

@@ -274,7 +274,7 @@ enum xenbus_state xenbus_read_driver_state(const char *path)
 	enum xenbus_state result;
 	int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
 	if (err)
-		result = XenbusStateClosed;
+		result = XenbusStateUnknown;
 
 	return result;
 }

linux-2.6-xen-sparse/include/xen/xenbus.h

@@ -274,7 +274,7 @@ int xenbus_free_evtchn(struct xenbus_device *dev, int port);
 
 /**
  * Return the state of the driver rooted at the given store path, or
- * XenbusStateClosed if no state can be read.
+ * XenbusStateUnknown if no state can be read.
  */
 enum xenbus_state xenbus_read_driver_state(const char *path);