On Tue, 24 Apr 2018 23:39:20 +0900
Toshiaki Makita <[email protected]> wrote:
> +static int veth_xdp_xmit(struct net_device *dev, struct xdp_frame *frame)
> +{
> + struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
> + int headroom = frame->data - (void *)frame;
> + struct net_device *rcv;
> + int err = 0;
> +
> + rcv = rcu_dereference(priv->peer);
> + if (unlikely(!rcv))
> + return -ENXIO;
> +
> + rcv_priv = netdev_priv(rcv);
> + /* xdp_ring is initialized on receive side? */
> + if (rcu_access_pointer(rcv_priv->xdp_prog)) {
> + err = xdp_ok_fwd_dev(rcv, frame->len);
> + if (unlikely(err))
> + return err;
> +
> + err = veth_xdp_enqueue(rcv_priv, veth_xdp_to_ptr(frame));
> + } else {
> + struct sk_buff *skb;
> +
> + skb = veth_build_skb(frame, headroom, frame->len, 0);
> + if (unlikely(!skb))
> + return -ENOMEM;
> +
> + /* Get page ref in case skb is dropped in netif_rx.
> + * The caller is responsible for freeing the page on error.
> + */
> + get_page(virt_to_page(frame->data));
I'm not sure you can make this assumption, that xdp_frames coming from
another device driver uses a refcnt based memory model. But maybe I'm
confused, as this looks like an SKB receive path, but in the
ndo_xdp_xmit().
> + if (unlikely(veth_forward_skb(rcv, skb, false) !=
> NET_RX_SUCCESS))
> + return -ENXIO;
> +
> + /* Put page ref on success */
> + page_frag_free(frame->data);
> + }
> +
> + return err;
> +}
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
