Re: [Qemu-devel] [PATCH v8 2/3] qom: pass original path to unparent method

[Anthony Liguori <aliguori@us.ibm.com>]

"Michael S. Tsirkin" <mst@redhat.com> writes:

> We need to know the original path since unparenting loses this state.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/qdev.c            | 4 ++--
>  include/qom/object.h | 3 ++-
>  qom/object.c         | 4 +++-
>  3 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/hw/qdev.c b/hw/qdev.c
> index 741af96..64546cf 100644
> --- a/hw/qdev.c
> +++ b/hw/qdev.c
> @@ -436,7 +436,7 @@ static void qbus_realize(BusState *bus, DeviceState *parent, const char *name)
>      }
>  }
>  
> -static void bus_unparent(Object *obj)
> +static void bus_unparent(Object *obj, const char *path)
>  {
>      BusState *bus = BUS(obj);
>      BusChild *kid;
> @@ -756,7 +756,7 @@ static void device_class_base_init(ObjectClass *class, void *data)
>      klass->props = NULL;
>  }
>  
> -static void device_unparent(Object *obj)
> +static void device_unparent(Object *obj, const char *path)
>  {
>      DeviceState *dev = DEVICE(obj);
>      DeviceClass *dc = DEVICE_GET_CLASS(dev);
> diff --git a/include/qom/object.h b/include/qom/object.h
> index cf094e7..f0790d4 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -330,11 +330,12 @@ typedef struct ObjectProperty
>  /**
>   * ObjectUnparent:
>   * @obj: the object that is being removed from the composition tree
> + * @path: canonical path that object had if any
>   *
>   * Called when an object is being removed from the QOM composition tree.
>   * The function should remove any backlinks from children objects to @obj.
>   */
> -typedef void (ObjectUnparent)(Object *obj);
> +typedef void (ObjectUnparent)(Object *obj, const char *path);
>  
>  /**
>   * ObjectFree:
> diff --git a/qom/object.c b/qom/object.c
> index 3d638ff..21c9da4 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -362,14 +362,16 @@ static void object_property_del_child(Object *obj, Object *child, Error **errp)
>  
>  void object_unparent(Object *obj)
>  {
> +    gchar *path = object_get_canonical_path(obj);
>      object_ref(obj);
>      if (obj->parent) {
>          object_property_del_child(obj->parent, obj, NULL);
>      }
>      if (obj->class->unparent) {
> -        (obj->class->unparent)(obj);
> +        (obj->class->unparent)(obj, path);
>      }

I think you should actually just move this call above
if (obj->parent) { object_parent_del_child(...); }.

There's no harm AFAICT in doing this and it seems more logical to me to
have destruction flow start with the subclass and move up to the base
class.

This avoids needing a hack like this because the object is still in a
reasonable state when unparent is called.

Paolo, do you see anything wrong with this?  I looked at the commit you
added this in and it doesn't look like it would be a problem.

Regards,

Anthony Liguori

>      object_unref(obj);
> +    g_free(path);
>  }
>  
>  static void object_deinit(Object *obj, TypeImpl *type)
> -- 
> MST