Re: [Qemu-devel] [PATCH v12 5/8] virtio-balloon: VIRTIO_BALLOON_F_SG

[Michael S. Tsirkin]

On Wed, Jul 12, 2017 at 08:40:18PM +0800, Wei Wang wrote:
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 28b0e96..9f27101 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -57,8 +57,28 @@ int virtqueue_add_sgs(struct virtqueue *vq,
>                     void *data,
>                     gfp_t gfp);
>  
> +/* A desc with this init id is treated as an invalid desc */
> +#define VIRTQUEUE_DESC_ID_INIT UINT_MAX
> +int virtqueue_add_chain_desc(struct virtqueue *_vq,
> +                          uint64_t addr,
> +                          uint32_t len,
> +                          unsigned int *head_id,
> +                          unsigned int *prev_id,
> +                          bool in);
> +
> +int virtqueue_add_chain(struct virtqueue *_vq,
> +                     unsigned int head,
> +                     bool indirect,
> +                     struct vring_desc *indirect_desc,
> +                     void *data,
> +                     void *ctx);
> +
>  bool virtqueue_kick(struct virtqueue *vq);
>  
> +bool virtqueue_kick_sync(struct virtqueue *vq);
> +
> +bool virtqueue_kick_async(struct virtqueue *vq, wait_queue_head_t wq);
> +
>  bool virtqueue_kick_prepare(struct virtqueue *vq);
>  
>  bool virtqueue_notify(struct virtqueue *vq);

I don't much care for this API. It does exactly what balloon needs,
but at cost of e.g. transparently busy-waiting. Unlikely to be
a good fit for anything else.

If you don't like my original _first/_next/_last, you will
need to come up with something else.

-- 
MST