Message-ID: <CACGkMEvU+nhC=Qaj_gWGi3osGgTYdwVDav4-1fs2BrbvDOEpyg@mail.gmail.com>
Date: Thu, 19 Oct 2023 12:23:48 +0800
From: Jason Wang <jasowang@...hat.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	"Michael S. Tsirkin" <mst@...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 v1 02/19] virtio_net: unify the code for
 recycling the xmit ptr

On Mon, Oct 16, 2023 at 8:00 PM Xuan Zhuo <xuanzhuo@...ux.alibaba.com> wrote:
>
> There are two completely similar and independent implementations. This
> is inconvenient for the subsequent addition of new types. So extract a
> function from this piece of code and call this function uniformly to
> recover old xmit ptr.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>

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

Thanks

> ---
>  drivers/net/virtio_net.c | 76 +++++++++++++++++-----------------------
>  1 file changed, 33 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 3d87386d8220..6cf77b6acdab 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -352,6 +352,30 @@ static struct xdp_frame *ptr_to_xdp(void *ptr)
>         return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG);
>  }
>
> +static void __free_old_xmit(struct send_queue *sq, bool in_napi,
> +                           struct virtnet_sq_stats *stats)
> +{
> +       unsigned int len;
> +       void *ptr;
> +
> +       while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
> +               if (!is_xdp_frame(ptr)) {
> +                       struct sk_buff *skb = ptr;
> +
> +                       pr_debug("Sent skb %p\n", skb);
> +
> +                       stats->bytes += skb->len;
> +                       napi_consume_skb(skb, in_napi);
> +               } else {
> +                       struct xdp_frame *frame = ptr_to_xdp(ptr);
> +
> +                       stats->bytes += xdp_get_frame_len(frame);
> +                       xdp_return_frame(frame);
> +               }
> +               stats->packets++;
> +       }
> +}
> +
>  /* Converting between virtqueue no. and kernel tx/rx queue no.
>   * 0:rx0 1:tx0 2:rx1 3:tx1 ... 2N:rxN 2N+1:txN 2N+2:cvq
>   */
> @@ -746,37 +770,19 @@ static void virtnet_rq_set_premapped(struct virtnet_info *vi)
>
>  static void free_old_xmit(struct send_queue *sq, bool in_napi)
>  {
> -       unsigned int len;
> -       unsigned int packets = 0;
> -       unsigned int bytes = 0;
> -       void *ptr;
> +       struct virtnet_sq_stats stats = {};
>
> -       while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
> -               if (likely(!is_xdp_frame(ptr))) {
> -                       struct sk_buff *skb = ptr;
> -
> -                       pr_debug("Sent skb %p\n", skb);
> -
> -                       bytes += skb->len;
> -                       napi_consume_skb(skb, in_napi);
> -               } else {
> -                       struct xdp_frame *frame = ptr_to_xdp(ptr);
> -
> -                       bytes += xdp_get_frame_len(frame);
> -                       xdp_return_frame(frame);
> -               }
> -               packets++;
> -       }
> +       __free_old_xmit(sq, in_napi, &stats);
>
>         /* Avoid overhead when no packets have been processed
>          * happens when called speculatively from start_xmit.
>          */
> -       if (!packets)
> +       if (!stats.packets)
>                 return;
>
>         u64_stats_update_begin(&sq->stats.syncp);
> -       sq->stats.bytes += bytes;
> -       sq->stats.packets += packets;
> +       sq->stats.bytes += stats.bytes;
> +       sq->stats.packets += stats.packets;
>         u64_stats_update_end(&sq->stats.syncp);
>  }
>
> @@ -915,15 +921,12 @@ static int virtnet_xdp_xmit(struct net_device *dev,
>                             int n, struct xdp_frame **frames, u32 flags)
>  {
>         struct virtnet_info *vi = netdev_priv(dev);
> +       struct virtnet_sq_stats stats = {};
>         struct receive_queue *rq = vi->rq;
>         struct bpf_prog *xdp_prog;
>         struct send_queue *sq;
> -       unsigned int len;
> -       int packets = 0;
> -       int bytes = 0;
>         int nxmit = 0;
>         int kicks = 0;
> -       void *ptr;
>         int ret;
>         int i;
>
> @@ -942,20 +945,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
>         }
>
>         /* Free up any pending old buffers before queueing new ones. */
> -       while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
> -               if (likely(is_xdp_frame(ptr))) {
> -                       struct xdp_frame *frame = ptr_to_xdp(ptr);
> -
> -                       bytes += xdp_get_frame_len(frame);
> -                       xdp_return_frame(frame);
> -               } else {
> -                       struct sk_buff *skb = ptr;
> -
> -                       bytes += skb->len;
> -                       napi_consume_skb(skb, false);
> -               }
> -               packets++;
> -       }
> +       __free_old_xmit(sq, false, &stats);
>
>         for (i = 0; i < n; i++) {
>                 struct xdp_frame *xdpf = frames[i];
> @@ -975,8 +965,8 @@ static int virtnet_xdp_xmit(struct net_device *dev,
>         }
>  out:
>         u64_stats_update_begin(&sq->stats.syncp);
> -       sq->stats.bytes += bytes;
> -       sq->stats.packets += packets;
> +       sq->stats.bytes += stats.bytes;
> +       sq->stats.packets += stats.packets;
>         sq->stats.xdp_tx += n;
>         sq->stats.xdp_tx_drops += n - nxmit;
>         sq->stats.kicks += kicks;
> --
> 2.32.0.3.g01195cf9f
>

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