On Wed, 2024-02-28 at 19:05 +0800, Yunjian Wang wrote:
> If TUN supports AF_XDP TX zero-copy, the XDP program will enqueue
> packets to the XDP ring and wake up the vhost worker. This requires
> the vhost worker to call peek_len(), which can be used to consume
> XDP descriptors.
>
> Signed-off-by: Yunjian Wang <wangyunjian@xxxxxxxxxx>
> ---
> drivers/vhost/net.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index f2ed7167c848..077e74421558 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -207,6 +207,11 @@ static int vhost_net_buf_peek_len(void *ptr)
> return __skb_array_len_with_tag(ptr);
> }
>
> +static bool vhost_sock_xdp(struct socket *sock)
> +{
> + return sock_flag(sock->sk, SOCK_XDP);
> +}
> +
> static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
> {
> struct vhost_net_buf *rxq = &nvq->rxq;
> @@ -214,6 +219,13 @@ static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
> if (!vhost_net_buf_is_empty(rxq))
> goto out;
>
> + if (ptr_ring_empty(nvq->rx_ring)) {
> + struct socket *sock = vhost_vq_get_backend(&nvq->vq);
> + /* Call peek_len to consume XSK descriptors, when using xdp */
> + if (vhost_sock_xdp(sock) && sock->ops->peek_len)
> + sock->ops->peek_len(sock);
This really looks like a socket API misuse. Why can't you use ptr-ring
primitives to consume XSK descriptors? peek_len could be constified
some day, this code will prevent such (good) thing.
Cheers,
Paolo
