Re: [Qemu-block] [PULL 04/41] virtio: convert to use DMA api

[Paolo Bonzini]

On 10/01/2017 06:39, Michael S. Tsirkin wrote:
> -void virtqueue_map(VirtQueueElement *elem)
> +void virtqueue_map(VirtIODevice *vdev, VirtQueueElement *elem)
>  {
> -    virtqueue_map_iovec(elem->in_sg, elem->in_addr, &elem->in_num,
> -                        VIRTQUEUE_MAX_SIZE, 1);
> -    virtqueue_map_iovec(elem->out_sg, elem->out_addr, &elem->out_num,
> -                        VIRTQUEUE_MAX_SIZE, 0);
> +    virtqueue_map_iovec(vdev, elem->in_sg, elem->in_addr, &elem->in_num,
> +                        MIN(ARRAY_SIZE(elem->in_sg), 
> ARRAY_SIZE(elem->in_addr)),
> +                        1);
> +    virtqueue_map_iovec(vdev, elem->out_sg, elem->out_addr, &elem->out_num,
> +                        MIN(ARRAY_SIZE(elem->out_sg),
> +                        ARRAY_SIZE(elem->out_addr)),
> +                        0);

Coverity reports that ARRAY_SIZE(elem->out_sg) (and all the others too)
is wrong because elem->out_sg is a pointer.

However, the check is not in the right place and the max_size argument
of virtqueue_map_iovec can be removed.  The check on in_num/out_num can
be moved to qemu_get_virtqueue_element instead, before the call to
virtqueue_alloc_element.

Thanks,

Paolo