标签：add setup header lis struct flags code 网卡 against
在bond初始化的时候，我们可以看到如下属性：
static void loopback_setup(struct net_device *dev) { dev->mtu = 64 * 1024; dev->hard_header_len = ETH_HLEN; /* 14 */ dev->addr_len = ETH_ALEN; /* 6 */ dev->type = ARPHRD_LOOPBACK; /* 0x0001*/ dev->flags = IFF_LOOPBACK; dev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_NO_QUEUE; netif_keep_dst(dev); dev->hw_features = NETIF_F_GSO_SOFTWARE; dev->features = NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_GSO_SOFTWARE | NETIF_F_HW_CSUM | NETIF_F_RXCSUM | NETIF_F_SCTP_CRC | NETIF_F_HIGHDMA | NETIF_F_LLTX | NETIF_F_NETNS_LOCAL | NETIF_F_VLAN_CHALLENGED | NETIF_F_LOOPBACK; dev->ethtool_ops = &loopback_ethtool_ops; dev->header_ops = ð_header_ops; dev->netdev_ops = &loopback_ops; dev->destructor = loopback_dev_free; }
NETIF_F_LLTX 属性代表的是，我们在发包的时候，不需要获取锁。
而对于非虚拟设备，如实际网卡，则这个属性一般是不设置的，也就是需要获取TX的锁。
不过，也有注释说后面的驱动最好不要用这个特性：
* LLTX driver (deprecated for hardware drivers) NETIF_F_LLTX should be set in drivers that implement their own locking in transmit path or don‘t need locking at all (e.g. software tunnels). In ndo_start_xmit, it is recommended to use a try_lock and return NETDEV_TX_LOCKED when the spin lock fails. The locking should also properly protect against other callbacks (the rules you need to find out). Don‘t use it for new drivers.
标签：add setup header lis struct flags code 网卡 against
原文地址：https://www.cnblogs.com/10087622blog/p/9571055.html
