qdev: add reference count to a device for the BusChild

Each device has a reference through the BusChild.  This reference
was not accounted for, add it now.

Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/hw/qdev.c b/hw/qdev.c
index b80b082a0091d714b56a07f51071b875f595acc7..9a8b8c162123818341010d3fbafabe7752128586 100644 (file)
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -64,7 +64,10 @@ static void bus_remove_child(BusState *bus, DeviceState *child)
 
             snprintf(name, sizeof(name), "child[%d]", kid->index);
             QTAILQ_REMOVE(&bus->children, kid, sibling);
+
+            /* This gives back ownership of kid->child back to us.  */
             object_property_del(OBJECT(bus), name, NULL);
+            object_unref(OBJECT(kid->child));
             g_free(kid);
             return;
         }
@@ -82,9 +85,11 @@ static void bus_add_child(BusState *bus, DeviceState *child)
 
     kid->index = bus->max_index++;
     kid->child = child;
+    object_ref(OBJECT(kid->child));
 
     QTAILQ_INSERT_HEAD(&bus->children, kid, sibling);
 
+    /* This transfers ownership of kid->child to the property.  */
     snprintf(name, sizeof(name), "child[%d]", kid->index);
     object_property_add_link(OBJECT(bus), name,
                              object_get_typename(OBJECT(child)),