netdev - Re: [PATCH net-next 5/8] virtio_net: separate the logic of freeing the rest mergeable buf

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Date:   Mon, 3 Apr 2023 10:46:39 +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 5/8] virtio_net: separate the logic of freeing
 the rest mergeable buf

On Tue, Mar 28, 2023 at 8:04 PM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
>
> This patch introduce a new function that frees the rest mergeable buf.
> The subsequent patch will reuse this function.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>

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

Thanks

> ---
>  drivers/net/virtio_net.c | 36 ++++++++++++++++++++++++------------
>  1 file changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 09aed60e2f51..a3f2bcb3db27 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1076,6 +1076,28 @@ static struct sk_buff *receive_big(struct net_device *dev,
>         return NULL;
>  }
>
> +static void mergeable_buf_free(struct receive_queue *rq, int num_buf,
> +                              struct net_device *dev,
> +                              struct virtnet_rq_stats *stats)
> +{
> +       struct page *page;
> +       void *buf;
> +       int len;
> +
> +       while (num_buf-- > 1) {
> +               buf = virtqueue_get_buf(rq->vq, &len);
> +               if (unlikely(!buf)) {
> +                       pr_debug("%s: rx error: %d buffers missing\n",
> +                                dev->name, num_buf);
> +                       dev->stats.rx_length_errors++;
> +                       break;
> +               }
> +               stats->bytes += len;
> +               page = virt_to_head_page(buf);
> +               put_page(page);
> +       }
> +}
> +
>  /* Why not use xdp_build_skb_from_frame() ?
>   * XDP core assumes that xdp frags are PAGE_SIZE in length, while in
>   * virtio-net there are 2 points that do not match its requirements:
> @@ -1436,18 +1458,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>         stats->xdp_drops++;
>  err_skb:
>         put_page(page);
> -       while (num_buf-- > 1) {
> -               buf = virtqueue_get_buf(rq->vq, &len);
> -               if (unlikely(!buf)) {
> -                       pr_debug("%s: rx error: %d buffers missing\n",
> -                                dev->name, num_buf);
> -                       dev->stats.rx_length_errors++;
> -                       break;
> -               }
> -               stats->bytes += len;
> -               page = virt_to_head_page(buf);
> -               put_page(page);
> -       }
> +       mergeable_buf_free(rq, num_buf, dev, stats);
> +
>  err_buf:
>         stats->drops++;
>         dev_kfree_skb(head_skb);
> --
> 2.32.0.3.g01195cf9f
>