TX_EOP_SIZE
ndev->needed_tailroom = TX_EOP_SIZE;
(tailroom < (padlen + TX_EOP_SIZE))) {
size_t t = max((padlen + TX_EOP_SIZE) - tailroom, 0);
skb_put_data(skb, &info.eop, TX_EOP_SIZE);
skb->len - TX_EOP_SIZE - 4 - TX_OVERHEAD, 0);