netdev - Re: [PATCH 16/33] virtio_net: introduce virtnet_xdp_handler() to seprate the logic of run xdp

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Date:   Fri, 3 Feb 2023 03:55:26 -0500
From:   "Michael S. Tsirkin" <mst@...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>,
        Jason Wang <jasowang@...hat.com>,
        Björn Töpel <bjorn@...nel.org>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Menglong Dong <imagedong@...cent.com>,
        Kuniyuki Iwashima <kuniyu@...zon.com>,
        Petr Machata <petrm@...dia.com>,
        virtualization@...ts.linux-foundation.org, bpf@...r.kernel.org
Subject: Re: [PATCH 16/33] virtio_net: introduce virtnet_xdp_handler() to
 seprate the logic of run xdp

On Thu, Feb 02, 2023 at 07:00:41PM +0800, Xuan Zhuo wrote:
> At present, we have two long similar logic to perform XDP Progs. And in
> the implementation of XSK, we will have this need.
> 
> Therefore, this PATCH separates the code of executing XDP, which is
> conducive to later maintenance and facilitates subsequent XSK for reuse.
> 
> Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>

So you first add a new function then move users over.
This means that it's hard during review to make sure
nothing is lost in translation.
Do the refactoring in a single patch instead.

> ---
>  drivers/net/virtio/main.c       | 53 +++++++++++++++++++++++++++++++++
>  drivers/net/virtio/virtio_net.h | 11 +++++++
>  2 files changed, 64 insertions(+)
> 
> diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
> index 5683cb576474..9d4b84b23ef7 100644
> --- a/drivers/net/virtio/main.c
> +++ b/drivers/net/virtio/main.c
> @@ -478,6 +478,59 @@ static int virtnet_xdp_xmit(struct net_device *dev,
>  	return ret;
>  }
>  
> +int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
> +			struct net_device *dev,
> +			unsigned int *xdp_xmit,
> +			struct virtnet_rq_stats *stats)
> +{
> +	struct xdp_frame *xdpf;
> +	int err;
> +	u32 act;
> +
> +	act = bpf_prog_run_xdp(xdp_prog, xdp);
> +	stats->xdp_packets++;
> +
> +	switch (act) {
> +	case XDP_PASS:
> +		return VIRTNET_XDP_RES_PASS;
> +
> +	case XDP_TX:
> +		stats->xdp_tx++;
> +		xdpf = xdp_convert_buff_to_frame(xdp);
> +		if (unlikely(!xdpf))
> +			return VIRTNET_XDP_RES_DROP;
> +
> +		err = virtnet_xdp_xmit(dev, 1, &xdpf, 0);
> +		if (unlikely(!err)) {
> +			xdp_return_frame_rx_napi(xdpf);
> +		} else if (unlikely(err < 0)) {
> +			trace_xdp_exception(dev, xdp_prog, act);
> +			return VIRTNET_XDP_RES_DROP;
> +		}
> +
> +		*xdp_xmit |= VIRTIO_XDP_TX;
> +		return VIRTNET_XDP_RES_CONSUMED;
> +
> +	case XDP_REDIRECT:
> +		stats->xdp_redirects++;
> +		err = xdp_do_redirect(dev, xdp, xdp_prog);
> +		if (err)
> +			return VIRTNET_XDP_RES_DROP;
> +
> +		*xdp_xmit |= VIRTIO_XDP_REDIR;
> +		return VIRTNET_XDP_RES_CONSUMED;
> +
> +	default:
> +		bpf_warn_invalid_xdp_action(dev, xdp_prog, act);
> +		fallthrough;
> +	case XDP_ABORTED:
> +		trace_xdp_exception(dev, xdp_prog, act);
> +		fallthrough;
> +	case XDP_DROP:
> +		return VIRTNET_XDP_RES_DROP;
> +	}
> +}
> +
>  static unsigned int virtnet_get_headroom(struct virtnet_info *vi)
>  {
>  	return vi->xdp_enabled ? VIRTIO_XDP_HEADROOM : 0;
> diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h
> index 8bf31429ae28..af3e7e817f9e 100644
> --- a/drivers/net/virtio/virtio_net.h
> +++ b/drivers/net/virtio/virtio_net.h
> @@ -22,6 +22,12 @@
>  #include <net/net_failover.h>
>  #include <net/xdp_sock_drv.h>
>  
> +enum {
> +	VIRTNET_XDP_RES_PASS,
> +	VIRTNET_XDP_RES_DROP,
> +	VIRTNET_XDP_RES_CONSUMED,
> +};
> +
>  #define VIRTIO_XDP_FLAG	BIT(0)
>  
>  struct virtnet_info {
> @@ -262,4 +268,9 @@ static void __free_old_xmit(struct send_queue *sq, bool in_napi,
>  		stats->packets++;
>  	}
>  }
> +
> +int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
> +			struct net_device *dev,
> +			unsigned int *xdp_xmit,
> +			struct virtnet_rq_stats *stats);
>  #endif
> -- 
> 2.32.0.3.g01195cf9f