Re: [Qemu-devel] [PATCH v4 8/9] virtio: fix virtio-blk child refcount in transports

[Peter Crosthwaite]

On Wed, Jun 18, 2014 at 7:58 PM, Stefan Hajnoczi <address@hidden> wrote:
> object_initialize() leaves the object with a refcount of 1.
> object_property_add_child() adds its own reference which is dropped
> again when the property is deleted.
>
> The upshot of this is that we always have a refcount >= 1.  Upon hot
> unplug the virtio-blk child is not finalized!
>
> Drop our reference after the child property has been added to the
> parent.
>
> Signed-off-by: Stefan Hajnoczi <address@hidden>

Still not a fan, but I can't see a better way without more core QOM or
hotplug plumbing and that's not going to happen inside 2.1. So

Reviewed-by: Peter Crosthwaite <address@hidden>

Regards,
Peter

> ---
>  hw/s390x/s390-virtio-bus.c | 1 +
>  hw/s390x/virtio-ccw.c      | 1 +
>  hw/virtio/virtio-pci.c     | 1 +
>  3 files changed, 3 insertions(+)
>
> diff --git a/hw/s390x/s390-virtio-bus.c b/hw/s390x/s390-virtio-bus.c
> index 38984ab..3438a88 100644
> --- a/hw/s390x/s390-virtio-bus.c
> +++ b/hw/s390x/s390-virtio-bus.c
> @@ -179,6 +179,7 @@ static void s390_virtio_blk_instance_init(Object *obj)
>      VirtIOBlkS390 *dev = VIRTIO_BLK_S390(obj);
>      object_initialize(&dev->vdev, sizeof(dev->vdev), TYPE_VIRTIO_BLK);
>      object_property_add_child(obj, "virtio-backend", OBJECT(&dev->vdev), 
> NULL);
> +    object_unref(OBJECT(&dev->vdev));
>      qdev_alias_all_properties(DEVICE(&dev->vdev), obj);
>  }
>
> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> index 9fa6f32..0553fea 100644
> --- a/hw/s390x/virtio-ccw.c
> +++ b/hw/s390x/virtio-ccw.c
> @@ -813,6 +813,7 @@ static void virtio_ccw_blk_instance_init(Object *obj)
>      VirtIOBlkCcw *dev = VIRTIO_BLK_CCW(obj);
>      object_initialize(&dev->vdev, sizeof(dev->vdev), TYPE_VIRTIO_BLK);
>      object_property_add_child(obj, "virtio-backend", OBJECT(&dev->vdev), 
> NULL);
> +    object_unref(OBJECT(&dev->vdev));
>      qdev_alias_all_properties(DEVICE(&dev->vdev), obj);
>  }
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 3bb782f..abf05a9 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1102,6 +1102,7 @@ static void virtio_blk_pci_instance_init(Object *obj)
>      VirtIOBlkPCI *dev = VIRTIO_BLK_PCI(obj);
>      object_initialize(&dev->vdev, sizeof(dev->vdev), TYPE_VIRTIO_BLK);
>      object_property_add_child(obj, "virtio-backend", OBJECT(&dev->vdev), 
> NULL);
> +    object_unref(OBJECT(&dev->vdev));
>      qdev_alias_all_properties(DEVICE(&dev->vdev), obj);
>  }
>
> --
> 1.9.3
>
>