Re: [net PATCH v3 3/5] virtio_net: factor out xdp handler for readability

Jason Wang
2017-01-13T07:51:22Z

On 2017年01月13日 10:51, John Fastabend wrote:
> At this point the do_xdp_prog is mostly if/else branches handling
> the different modes of virtio_net. So remove it and handle running
> the program in the per mode handlers.
>
> Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
> ---
> drivers/net/virtio_net.c | 76 +++++++++++++++++-----------------------------
> 1 file changed, 28 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 43cb2e0..ec54644 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -388,49 +388,6 @@ static void virtnet_xdp_xmit(struct virtnet_info *vi,
> virtqueue_kick(sq->vq);
> }
>

[...]

>
> /* This happens when rx buffer size is underestimated */
> @@ -598,8 +570,10 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> if (unlikely(hdr->hdr.gso_type))
> goto err_xdp;
>
> - act = do_xdp_prog(vi, rq, xdp_prog,
> - page_address(xdp_page) + offset, len);
> + data = page_address(xdp_page) + offset;
> + xdp.data = data + desc_room;
> + xdp.data_end = xdp.data + (len - vi->hdr_len);

It looks desc_room is always vi->hdr_len.

> + act = bpf_prog_run_xdp(xdp_prog, &xdp);
> switch (act) {
> case XDP_PASS:
> /* We can only create skb based on xdp_page. */
> @@ -613,13 +587,19 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> }
> break;
> case XDP_TX:
> + qp = vi->curr_queue_pairs -
> + vi->xdp_queue_pairs +
> + smp_processor_id();
> + virtnet_xdp_xmit(vi, rq, &vi->sq[qp], &xdp, data);
> ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);
> if (unlikely(xdp_page != page))
> goto err_xdp;
> rcu_read_unlock();
> goto xdp_xmit;
> - case XDP_DROP:
> default:
> + bpf_warn_invalid_xdp_action(act);
> + case XDP_ABORTED:
> + case XDP_DROP:
> if (unlikely(xdp_page != page))
> __free_pages(xdp_page, 0);
> ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);
>