Re: [PATCH net-next] net: fec: add XDP_TX feature support

[Alexander Lobakin]

From: Wei Fang <wei.fang@xxxxxxx>
Date: Mon, 17 Jul 2023 18:37:09 +0800

> The XDP_TX feature is not supported before, and all the frames
> which are deemed to do XDP_TX action actually do the XDP_DROP
> action. So this patch adds the XDP_TX support to FEC driver.

[...]

> @@ -3897,6 +3923,29 @@ static int fec_enet_txq_xmit_frame(struct fec_enet_private *fep,
>  	return 0;
>  }
>  
> +static int fec_enet_xdp_tx_xmit(struct net_device *ndev,
> +				struct xdp_buff *xdp)
> +{
> +	struct xdp_frame *xdpf = xdp_convert_buff_to_frame(xdp);

Have you tried avoid converting buff to frame in case of XDP_TX? It
would save you a bunch of CPU cycles.

> +	struct fec_enet_private *fep = netdev_priv(ndev);
> +	struct fec_enet_priv_tx_q *txq;
> +	int cpu = smp_processor_id();
> +	struct netdev_queue *nq;
> +	int queue, ret;
> +
> +	queue = fec_enet_xdp_get_tx_queue(fep, cpu);
> +	txq = fep->tx_queue[queue];
> +	nq = netdev_get_tx_queue(fep->netdev, queue);
> +
> +	__netif_tx_lock(nq, cpu);
> +
> +	ret = fec_enet_txq_xmit_frame(fep, txq, xdpf, false);
> +
> +	__netif_tx_unlock(nq);
> +
> +	return ret;
> +}
> +
>  static int fec_enet_xdp_xmit(struct net_device *dev,
>  			     int num_frames,
>  			     struct xdp_frame **frames,
> @@ -3917,7 +3966,7 @@ static int fec_enet_xdp_xmit(struct net_device *dev,
>  	__netif_tx_lock(nq, cpu);
>  
>  	for (i = 0; i < num_frames; i++) {
> -		if (fec_enet_txq_xmit_frame(fep, txq, frames[i]) < 0)
> +		if (fec_enet_txq_xmit_frame(fep, txq, frames[i], true) < 0)
>  			break;
>  		sent_frames++;
>  	}

Thanks,
Olek