[PATCH 1/1] vhost: fix a double fetch when dequeue offloading

[Stephen Hemminger]

On Thu, 19 Dec 2024 14:38:28 +0800
Yunjian Wang <wangyunjian at huawei.com> wrote:

> diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
> index 69901ab3b5..5c40ae7069 100644
> --- a/lib/vhost/virtio_net.c
> +++ b/lib/vhost/virtio_net.c
> @@ -2914,10 +2914,12 @@ desc_to_mbuf(struct virtio_net *dev, struct vhost_virtqueue *vq,
>  			 * in a contiguous virtual area.
>  			 */
>  			copy_vnet_hdr_from_desc(&tmp_hdr, buf_vec);
> -			hdr = &tmp_hdr;
>  		} else {
> -			hdr = (struct virtio_net_hdr *)((uintptr_t)buf_vec[0].buf_addr);
> +			rte_memcpy((void *)(uintptr_t)&tmp_hdr,
> +				(void *)(uintptr_t)buf_vec[0].buf_addr,
> +				sizeof(struct virtio_net_hdr));
>  		}
> +		hdr = &tmp_hdr;

Since this if block is just an optimization of the case where vnet header
is contiguous why not just always use copy_vnet_hdr_from_desc? and inline it?