+ ndev->needed_headroom = local->tx_headroom +
+ 4*6 /* four MAC addresses */
+ + 2 + 2 + 2 + 2 /* ctl, dur, seq, qos */
+ + 6 /* mesh */
+ + 8 /* rfc1042/bridge tunnel */
+ - ETH_HLEN /* ethernet hard_header_len */
+ + IEEE80211_ENCRYPT_HEADROOM;
+ ndev->needed_tailroom = IEEE80211_ENCRYPT_TAILROOM;
+