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hw/virtio: Use object_initialize_child for correct reference counting

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As explained in commit aff39be0ed:

  Both functions, object_initialize() and object_property_add_child()
  increase the reference counter of the new object, so one of the
  references has to be dropped afterwards to get the reference
  counting right. Otherwise the child object will not be properly
  cleaned up when the parent gets destroyed.
  Thus let's use now object_initialize_child() instead to get the
  reference counting here right.

This patch was generated using the following Coccinelle script:

 @use_object_initialize_child@
 expression parent_obj;
 expression child_ptr;
 expression child_name;
 expression child_type;
 expression child_size;
 expression errp;
 @@
 (
 -   object_initialize(child_ptr, child_size, child_type);
 +   object_initialize_child(parent_obj, child_name,  child_ptr, child_size,
 +                           child_type, &error_abort, NULL);
     ... when != parent_obj
 -   object_property_add_child(parent_obj, child_name, OBJECT(child_ptr), NULL);
     ...
 ?-  object_unref(OBJECT(child_ptr));
 |
 -   object_initialize(child_ptr, child_size, child_type);
 +   object_initialize_child(parent_obj, child_name,  child_ptr, child_size,
 +                            child_type, errp, NULL);
     ... when != parent_obj
 -   object_property_add_child(parent_obj, child_name, OBJECT(child_ptr), errp);
     ...
 ?-  object_unref(OBJECT(child_ptr));
 )

While the object_initialize() function doesn't take an
'Error *errp' argument, the object_initialize_child() does.
Since this code is used when a machine is created (and is not
yet running), we deliberately choose to use the &error_abort
argument instead of ignoring errors if an object creation failed.

Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Inspired-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190507163416.24647-4-philmd@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Philippe Mathieu-Daudé 2019-05-07 18:34:03 +02:00 committed by Eduardo Habkost
parent 954d97672f
commit 3d2fc923ec
1 changed files with 2 additions and 3 deletions
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5
hw/virtio/virtio.c
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@ -2312,9 +2312,8 @@ void virtio_instance_init_common(Object *proxy_obj, void *data,
{
DeviceState *vdev = data;
object_initialize(vdev, vdev_size, vdev_name);
object_property_add_child(proxy_obj, "virtio-backend", OBJECT(vdev), NULL);
object_unref(OBJECT(vdev));
object_initialize_child(proxy_obj, "virtio-backend", vdev, vdev_size,
vdev_name, &error_abort, NULL);
qdev_alias_all_properties(vdev, proxy_obj);
}