> +static int aqc111_change_mtu(struct net_device *net, int new_mtu) > +{ > + struct usbnet *dev = netdev_priv(net); > + u16 reg16 = 0; > + u8 buf[5]; > + > + if (new_mtu <= 0 || new_mtu > 16334) { > + netdev_info(net, "Invalid MTU %d requested, hw max 16334", > + new_mtu); > + return -EINVAL; > + } Please set net->min_mtu, and net->max_mtu, and the core should do this checking for you. See dev_set_mtu_ext(). Andrew