qdev: Provide qdev_get_bus_hotplug_handler()

Let's use a wrapper instead of looking it up manually. This function can
than be reused when we explicitly want to have the bus hotplug handler
(e.g. when the bus hotplug handler was overwritten by the machine
hotplug handler).
Reviewed-by: NIgor Mammedov <imammedo@redhat.com>
Signed-off-by: NDavid Hildenbrand <david@redhat.com>
Message-Id: <20190228122849.4296-4-david@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

hw/core/qdev.c

@@ -236,12 +236,20 @@ HotplugHandler *qdev_get_machine_hotplug_handler(DeviceState *dev)
     return NULL;
 }
 
+HotplugHandler *qdev_get_bus_hotplug_handler(DeviceState *dev)
+{
+    if (dev->parent_bus) {
+        return dev->parent_bus->hotplug_handler;
+    }
+    return NULL;
+}
+
 HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
 {
     HotplugHandler *hotplug_ctrl = qdev_get_machine_hotplug_handler(dev);
 
     if (hotplug_ctrl == NULL && dev->parent_bus) {
-        hotplug_ctrl = dev->parent_bus->hotplug_handler;
+        hotplug_ctrl = qdev_get_bus_hotplug_handler(dev);
     }
     return hotplug_ctrl;
 }

include/hw/qdev-core.h

@@ -281,6 +281,7 @@ DeviceState *qdev_try_create(BusState *bus, const char *name);
 void qdev_init_nofail(DeviceState *dev);
 void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
                                  int required_for_version);
+HotplugHandler *qdev_get_bus_hotplug_handler(DeviceState *dev);
 HotplugHandler *qdev_get_machine_hotplug_handler(DeviceState *dev);
 /**
  * qdev_get_hotplug_handler: Get handler responsible for device wiring