Re: [PATCH net-next v6 7/7] net: bcmgenet: reject MTU changes incompatible with XDP

[Mohsin Bashir <mohsin.bashr@gmail.com>]

>   
> +static int bcmgenet_change_mtu(struct net_device *dev, int new_mtu)
> +{
> +	struct bcmgenet_priv *priv = netdev_priv(dev);
> +
> +	if (priv->xdp_prog && new_mtu > PAGE_SIZE - GENET_RX_HEADROOM -
> +	    SKB_DATA_ALIGN(sizeof(struct skb_shared_info))) {
> +		netdev_warn(dev, "MTU too large for single-page XDP buffer\n");
> +		return -EINVAL;
> +	}
> +
> +	WRITE_ONCE(dev->mtu, new_mtu);
> +	return 0;
> +}
> +
>   static const struct net_device_ops bcmgenet_netdev_ops = {
>   	.ndo_open		= bcmgenet_open,
>   	.ndo_stop		= bcmgenet_close,
> @@ -4102,6 +4116,7 @@ static const struct net_device_ops bcmgenet_netdev_ops = {
>   	.ndo_eth_ioctl		= phy_do_ioctl_running,
>   	.ndo_set_features	= bcmgenet_set_features,
>   	.ndo_get_stats64	= bcmgenet_get_stats64,
> +	.ndo_change_mtu		= bcmgenet_change_mtu,
>   	.ndo_change_carrier	= bcmgenet_change_carrier,
>   	.ndo_bpf		= bcmgenet_xdp,
>   	.ndo_xdp_xmit		= bcmgenet_xdp_xmit,

Reviewed-by: Mohsin Bashir <hmohsin@meta.com>