greybus: svc: refactor interface-route destruction

Add interface-route-destroy helper to tear down the route and release
the interface device id.

Note that we currently need to grab a reference to the interface to
prevent it from being deallocated before tearing down the route.
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Jeffrey Carlyle <jcarlyle@google.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/svc.c

@@ -518,21 +518,23 @@ static int gb_svc_interface_route_create(struct gb_svc *svc,
 	return ret;
 }
 
-static void gb_svc_intf_remove(struct gb_svc *svc, struct gb_interface *intf)
+static void gb_svc_interface_route_destroy(struct gb_svc *svc,
+						struct gb_interface *intf)
 {
-	u8 intf_id = intf->interface_id;
-	u8 device_id = intf->device_id;
+	gb_svc_route_destroy(svc, svc->ap_intf_id, intf->interface_id);
+	ida_simple_remove(&svc->device_id_map, intf->device_id);
+}
 
+static void gb_svc_intf_remove(struct gb_svc *svc, struct gb_interface *intf)
+{
 	intf->disconnected = true;
 
-	gb_interface_remove(intf);
+	get_device(&intf->dev);
 
-	/*
-	 * Destroy the two-way route between the AP and the interface.
-	 */
-	gb_svc_route_destroy(svc, svc->ap_intf_id, intf_id);
+	gb_interface_remove(intf);
+	gb_svc_interface_route_destroy(svc, intf);
 
-	ida_simple_remove(&svc->device_id_map, device_id);
+	put_device(&intf->dev);
 }
 
 static void gb_svc_process_intf_hotplug(struct gb_operation *operation)
@@ -630,8 +632,7 @@ static void gb_svc_process_intf_hotplug(struct gb_operation *operation)
 	return;
 
 destroy_route:
-	gb_svc_route_destroy(svc, svc->ap_intf_id, intf_id);
-	ida_simple_remove(&svc->device_id_map, intf->device_id);
+	gb_svc_interface_route_destroy(svc, intf);
 destroy_interface:
 	gb_interface_remove(intf);
 }