NETIF_F_V4_CSUM 149 include/linux/netdev_features.h #define NETIF_F_ALL_CSUM (NETIF_F_V4_CSUM | NETIF_F_V6_CSUM) NETIF_F_V4_CSUM 3451 include/linux/netdevice.h ((features & NETIF_F_V4_CSUM) &&