emac_rx_skb_size
int rx_skb_size = emac_rx_skb_size(new_mtu);
if (emac_rx_skb_size(ndev->mtu) != emac_rx_skb_size(new_mtu))
dev->rx_skb_size = emac_rx_skb_size(new_mtu);
dev->rx_skb_size = emac_rx_skb_size(ndev->mtu);