Re: [PATCH net-next v3 3/6] net: bcmgenet: add basic XDP support (PASS/DROP)

[Mohsin Bashir]

> +static int bcmgenet_xdp_setup(struct net_device *dev,
> +			      struct netdev_bpf *xdp)
> +{
> +	struct bcmgenet_priv *priv = netdev_priv(dev);
> +	struct bpf_prog *old_prog;
> +	struct bpf_prog *prog = xdp->prog;
> +
> +	if (prog && dev->mtu > PAGE_SIZE - GENET_RX_HEADROOM -
> +	    SKB_DATA_ALIGN(sizeof(struct skb_shared_info))) {
> +		NL_SET_ERR_MSG_MOD(xdp->extack,
> +				   "MTU too large for single-page XDP buffer");
> +		return -EOPNOTSUPP;
> +	}

The MTU check here is great. But I do not see support for 
.ndo_change_mtu. This would allow users to change MTU size AFTER the 
program is attached.