linux-kernel - Re: [PATCH net-next] net: fec: add exception tracing for XDP

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Date:   Wed, 23 Aug 2023 12:44:28 -0700
From:   Jacob Keller <jacob.e.keller@...el.com>
To:     Wei Fang <wei.fang@....com>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
        <ast@...nel.org>, <daniel@...earbox.net>, <hawk@...nel.org>,
        <john.fastabend@...il.com>, <shenwei.wang@....com>,
        <xiaoning.wang@....com>, <netdev@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <bpf@...r.kernel.org>,
        <linux-imx@....com>
Subject: Re: [PATCH net-next] net: fec: add exception tracing for XDP



On 8/21/2023 11:52 PM, Wei Fang wrote:
> As we already added the exception tracing for XDP_TX, I think it is
> necessary to add the exception tracing for other XDP actions, such
> as XDP_REDIRECT, XDP_ABORTED and unknown error actions.
> 
> Signed-off-by: Wei Fang <wei.fang@....com>
> Suggested-by: Jakub Kicinski <kuba@...nel.org>
> ---

Makes sense to me, and it ends up being a bit less code.

Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>

>  drivers/net/ethernet/freescale/fec_main.c | 26 ++++++++++-------------
>  1 file changed, 11 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
> index e23a55977183..8909899e9a31 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -1583,25 +1583,18 @@ fec_enet_run_xdp(struct fec_enet_private *fep, struct bpf_prog *prog,
>  	case XDP_REDIRECT:
>  		rxq->stats[RX_XDP_REDIRECT]++;
>  		err = xdp_do_redirect(fep->netdev, xdp, prog);
> -		if (!err) {
> -			ret = FEC_ENET_XDP_REDIR;
> -		} else {
> -			ret = FEC_ENET_XDP_CONSUMED;
> -			page = virt_to_head_page(xdp->data);
> -			page_pool_put_page(rxq->page_pool, page, sync, true);
> -		}
> +		if (unlikely(err))
> +			goto xdp_err;
> +
> +		ret = FEC_ENET_XDP_REDIR;
>  		break;
>  
>  	case XDP_TX:
>  		err = fec_enet_xdp_tx_xmit(fep, cpu, xdp, sync);
> -		if (unlikely(err)) {
> -			ret = FEC_ENET_XDP_CONSUMED;
> -			page = virt_to_head_page(xdp->data);
> -			page_pool_put_page(rxq->page_pool, page, sync, true);
> -			trace_xdp_exception(fep->netdev, prog, act);
> -		} else {
> -			ret = FEC_ENET_XDP_TX;
> -		}
> +		if (unlikely(err))
> +			goto xdp_err;
> +
> +		ret = FEC_ENET_XDP_TX;
>  		break;
>  
>  	default:
> @@ -1613,9 +1606,12 @@ fec_enet_run_xdp(struct fec_enet_private *fep, struct bpf_prog *prog,
>  
>  	case XDP_DROP:
>  		rxq->stats[RX_XDP_DROP]++;
> +xdp_err:
>  		ret = FEC_ENET_XDP_CONSUMED;
>  		page = virt_to_head_page(xdp->data);
>  		page_pool_put_page(rxq->page_pool, page, sync, true);

Ok, so we handle the cleaning up of the page and such here, which is
shared for both paths now. Nice!

> +		if (act != XDP_DROP)
> +			trace_xdp_exception(fep->netdev, prog, act);
>  		break;
>  	}
>