Re: [Qemu-devel] [PATCH] virtio-net: require that config size is initialized

["KONRAD Frédéric" <fred.konrad@greensocs.com>]

Hi,

I think it is not a good idea, as we wanted to make VirtIODevice 
hot-pluggable for virtio-mmio.

Maybe we can use a callback which is called by virtio-bus before 
plugging, to ensure that this
config size is computed?

On 07/05/2013 12:22, Michael S. Tsirkin wrote:
> All buses do this, and if they don't they get subtle
> bugs related to cross version migration.
> Let's add an assert to catch these bugs early.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>
> Just a cleanup so not 1.5 material.
> Seems to work fine here - any opinions?
>
>   hw/net/virtio-net.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 908e7b8..f0a9272 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1282,6 +1282,8 @@ static int virtio_net_device_init(VirtIODevice *vdev)
>       DeviceState *qdev = DEVICE(vdev);
>       VirtIONet *n = VIRTIO_NET(vdev);
>   
> +    /* Verify that config size has been initialized */
> +    assert(n->config_size != (size_t)-1);
>       virtio_init(VIRTIO_DEVICE(n), "virtio-net", VIRTIO_ID_NET,
>                                     n->config_size);
>   
> @@ -1386,10 +1388,9 @@ static void virtio_net_instance_init(Object *obj)
>       VirtIONet *n = VIRTIO_NET(obj);
>   
>       /*
> -     * The default config_size is sizeof(struct virtio_net_config).
> -     * Can be overriden with virtio_net_set_config_size.
> +     * The config_size must be set later with virtio_net_set_config_size.
>        */
> -    n->config_size = sizeof(struct virtio_net_config);
> +    n->config_size = (size_t)-1;
>   }
>   
>   static Property virtio_net_properties[] = {