TUN_F_CSUM
offload = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6;
if (arg & TUN_F_CSUM) {
if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
if (arg & TUN_F_CSUM) {
arg &= ~TUN_F_CSUM;
features = TUN_F_CSUM | TUN_F_UDP_TUNNEL_GSO |