netdev - Re: [PATCH net-next v3 13/15] virtio_net: small: remove skip

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Date:   Wed, 26 Apr 2023 11:13:31 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc:     netdev@...r.kernel.org, "Michael S. Tsirkin" <mst@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        virtualization@...ts.linux-foundation.org, bpf@...r.kernel.org
Subject: Re: [PATCH net-next v3 13/15] virtio_net: small: remove skip_xdp

On Sun, Apr 23, 2023 at 6:58 PM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
>
> now, the process of xdp is simple, we can remove the skip_xdp.

I would say the reason why xdp is simple, I think it is because the
skb build path is not shared between XDP and non-XDP case.

Other than this

Acked-by: Jason Wang <jasowang@...hat.com>

Thanks


>
> Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> ---
>  drivers/net/virtio_net.c | 26 ++++++++++++--------------
>  1 file changed, 12 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 601c0e7fc32b..d2973c8fa48c 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1028,13 +1028,12 @@ static struct sk_buff *receive_small(struct net_device *dev,
>                                      unsigned int *xdp_xmit,
>                                      struct virtnet_rq_stats *stats)
>  {
> -       struct sk_buff *skb;
> -       struct bpf_prog *xdp_prog;
>         unsigned int xdp_headroom = (unsigned long)ctx;
>         struct page *page = virt_to_head_page(buf);
>         unsigned int header_offset;
>         unsigned int headroom;
>         unsigned int buflen;
> +       struct sk_buff *skb;
>
>         len -= vi->hdr_len;
>         stats->bytes += len;
> @@ -1046,22 +1045,21 @@ static struct sk_buff *receive_small(struct net_device *dev,
>                 goto err;
>         }
>
> -       if (likely(!vi->xdp_enabled)) {
> -               xdp_prog = NULL;
> -               goto skip_xdp;
> -       }
> +       if (unlikely(vi->xdp_enabled)) {
> +               struct bpf_prog *xdp_prog;
>
> -       rcu_read_lock();
> -       xdp_prog = rcu_dereference(rq->xdp_prog);
> -       if (xdp_prog) {
> -               skb = receive_small_xdp(dev, vi, rq, xdp_prog, buf, xdp_headroom,
> -                                       len, xdp_xmit, stats);
> +               rcu_read_lock();
> +               xdp_prog = rcu_dereference(rq->xdp_prog);
> +               if (xdp_prog) {
> +                       skb = receive_small_xdp(dev, vi, rq, xdp_prog, buf,
> +                                               xdp_headroom, len, xdp_xmit,
> +                                               stats);
> +                       rcu_read_unlock();
> +                       return skb;
> +               }
>                 rcu_read_unlock();
> -               return skb;
>         }
> -       rcu_read_unlock();
>
> -skip_xdp:
>         header_offset = VIRTNET_RX_PAD + xdp_headroom;
>         headroom = vi->hdr_len + header_offset;
>         buflen = SKB_DATA_ALIGN(GOOD_PACKET_LEN + headroom) +
> --
> 2.32.0.3.g01195cf9f
>