Re: [Qemu-devel] [RFC PATCH v5 6/6] virtio-blk : Refactor virtio-blk.

[Peter Maydell]

On 4 December 2012 14:35,  <address@hidden> wrote:
> From: KONRAD Frederic <address@hidden>
>
> Create virtio-blk which extends virtio-device, so it can be connected on
> virtio-bus.
>
> Signed-off-by: KONRAD Frederic <address@hidden>
> ---
>  hw/virtio-blk.c | 170 
> ++++++++++++++++++++++++++++++++++++++++++++++++--------
>  hw/virtio-blk.h |   4 ++
>  2 files changed, 150 insertions(+), 24 deletions(-)
>
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index e25cc96..ee1ea8b 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -21,24 +21,42 @@
>  #ifdef __linux__
>  # include <scsi/sg.h>
>  #endif
> +#include "virtio-bus.h"
>
> +/* Take this structure as our device structure. */
>  typedef struct VirtIOBlock
>  {
> +    /*
> +     * Adding parent_obj breaks to_virtio_blk cast function,
> +     * and virtio_blk_init.
> +     */
> +    DeviceState parent_obj;
> +    /*
> +     * We don't need that anymore, as we'll use QOM cast to get the
> +     * VirtIODevice. Just temporary keep it, for not breaking functionality.
> +     */
>      VirtIODevice vdev;

This doesn't make sense. After your previous patch, VirtIODevice
is-a DeviceState, and VirtIOBlock already is-a VirtIODevice,
so there's nothing to do here. Adding this parent_obj field
here is just breaking things (it would make the VirtIOBlock
into a direct child of DeviceState, which isn't what we want).

>      BlockDriverState *bs;
>      VirtQueue *vq;
>      void *rq;
>      QEMUBH *bh;
>      BlockConf *conf;
> -    VirtIOBlkConf *blk;
> +    /*
> +     * We can't use pointer with properties.
> +     */
> +    VirtIOBlkConf blk;
>      unsigned short sector_mask;
>      DeviceState *qdev;
>  } VirtIOBlock;
>
> -static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
> -{
> -    return (VirtIOBlock *)vdev;
> -}
> +/*
> + * Use the QOM cast, so we don't need that anymore.
> + *
> + * static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
> + * {
> + *     return (VirtIOBlock *)vdev;
> + * }
> + */

If we don't need it, just delete it.

-- PMM