Linux Wireless架构总结

1. 无线网络驱动(ath9k_htc)

ath9k_htc是一个基于USB接口的SoftMAC无线网络适配器。为了其驱动能正常工作，首先必须调用usb_register来注册驱动定义的usb_driver，以借助USB Core的力量来处理与USB协议相关的事件。其代码如下：

static struct usb_driver ath9k_hif_usb_driver = { .name = KBUILD_MODNAME, .probe = ath9k_hif_usb_probe, .disconnect = ath9k_hif_usb_disconnect,#ifdef CONFIG_PM .suspend = ath9k_hif_usb_suspend, .resume = ath9k_hif_usb_resume, .reset_resume = ath9k_hif_usb_resume,#endif .id_table = ath9k_hif_usb_ids, .soft_unbind = 1,};

2. 关键数据结构

1) struct ieee80211_hw: 它包含802.11 PHY的配置和硬件信息。

Linux Wireless架构总结

2.1 各层间关键数据接口

Linux Wireless架构总结

3. USB无线适配器枚举过程

当此基于USB接口的无线网络适配器被枚举时，ath9k_hif_usb_probe将被调用。其调用流程如下图所示：

Linux Wireless架构总结

3.1 struct ieee80211_ops 实例 ath9k_htc_ops(驱动实现)

ath9k_htc_ops: mac80211通过这些回调函数回调driver的处理函数。ath9k_htc为了接受mac80211的管理，它必须首先向mac80211注册，以申明自己的存在，从而可以接受mac80211的调用。

struct ieee80211_ops ath9k_htc_ops = { .tx                 = ath9k_htc_tx,  // 发送mac80211要求发送的帧 .start              = ath9k_htc_start, // 第一个被attach到此硬件的net_device被enable之前被调用,之后，可以接收帧数据 .stop               = ath9k_htc_stop,  // 最后一个被attach到此硬件的net_device被disable之后被调用,之后，不可以接收帧数据 .add_interface      = ath9k_htc_add_interface, // 当一个被attach到此硬件的net_device被enable时被调用 .remove_interface   = ath9k_htc_remove_interface, // 通知driver一个接口将要going down .config             = ath9k_htc_config,           // mac802.11调用它修改硬件配置 .configure_filter   = ath9k_htc_configure_filter, // 配置设备的接收过滤器 .sta_add            = ath9k_htc_sta_add, .sta_remove         = ath9k_htc_sta_remove, .conf_tx            = ath9k_htc_conf_tx, .bss_info_changed   = ath9k_htc_bss_info_changed, .set_key            = ath9k_htc_set_key, .get_tsf            = ath9k_htc_get_tsf, .set_tsf            = ath9k_htc_set_tsf, .reset_tsf          = ath9k_htc_reset_tsf, .ampdu_action       = ath9k_htc_ampdu_action, .sw_scan_start      = ath9k_htc_sw_scan_start, .sw_scan_complete   = ath9k_htc_sw_scan_complete, .set_rts_threshold  = ath9k_htc_set_rts_threshold, .rfkill_poll        = ath9k_htc_rfkill_poll_state, .set_coverage_class = ath9k_htc_set_coverage_class, .set_bitrate_mask   = ath9k_htc_set_bitrate_mask,};

3.2 struct cfg80211_ops 实例 mac80211_config_ops(mac80211实现)

cfg80211_ops定义了无线配置的操作，在它的增加虚拟接口(ieee80211_add_iface)中，它将创建并注册net_device。在mac80211中，其定义如下所示：

struct cfg80211_ops mac80211_config_ops = { .add_virtual_intf = ieee80211_add_iface, //使用给定的名字创建一个"虚拟接口",在wiphy的命名空间中创建net_device并返回 .del_virtual_intf = ieee80211_del_iface, //删除由ifindex指定的"虚拟接口" .change_virtual_intf = ieee80211_change_iface, .add_key = ieee80211_add_key, .del_key = ieee80211_del_key, .get_key = ieee80211_get_key, .set_default_key = ieee80211_config_default_key, .set_default_mgmt_key = ieee80211_config_default_mgmt_key, .add_beacon = ieee80211_add_beacon, .set_beacon = ieee80211_set_beacon, .del_beacon = ieee80211_del_beacon, .add_station = ieee80211_add_station, .del_station = ieee80211_del_station, .change_station = ieee80211_change_station, .get_station = ieee80211_get_station, .dump_station = ieee80211_dump_station, .dump_survey = ieee80211_dump_survey,#ifdef CONFIG_MAC80211_MESH .add_mpath = ieee80211_add_mpath, .del_mpath = ieee80211_del_mpath, .change_mpath = ieee80211_change_mpath, .get_mpath = ieee80211_get_mpath, .dump_mpath = ieee80211_dump_mpath, .update_mesh_config = ieee80211_update_mesh_config, .get_mesh_config = ieee80211_get_mesh_config, .join_mesh = ieee80211_join_mesh, .leave_mesh = ieee80211_leave_mesh,#endif .change_bss = ieee80211_change_bss, .set_txq_params = ieee80211_set_txq_params, .set_channel = ieee80211_set_channel, .suspend = ieee80211_suspend, .resume = ieee80211_resume, .scan = ieee80211_scan, .sched_scan_start = ieee80211_sched_scan_start, .sched_scan_stop = ieee80211_sched_scan_stop, .auth = ieee80211_auth, .assoc = ieee80211_assoc, .deauth = ieee80211_deauth, .disassoc = ieee80211_disassoc, .join_ibss = ieee80211_join_ibss, .leave_ibss = ieee80211_leave_ibss, .set_wiphy_params = ieee80211_set_wiphy_params, .set_tx_power = ieee80211_set_tx_power, .get_tx_power = ieee80211_get_tx_power, .set_wds_peer = ieee80211_set_wds_peer, .rfkill_poll = ieee80211_rfkill_poll, CFG80211_TESTMODE_CMD(ieee80211_testmode_cmd) .set_power_mgmt = ieee80211_set_power_mgmt, .set_bitrate_mask = ieee80211_set_bitrate_mask, .remain_on_channel = ieee80211_remain_on_channel, .cancel_remain_on_channel = ieee80211_cancel_remain_on_channel, .mgmt_tx = ieee80211_mgmt_tx, .mgmt_tx_cancel_wait = ieee80211_mgmt_tx_cancel_wait, .set_cqm_rssi_config = ieee80211_set_cqm_rssi_config, .mgmt_frame_register = ieee80211_mgmt_frame_register, .set_antenna = ieee80211_set_antenna, .get_antenna = ieee80211_get_antenna, .set_ringparam = ieee80211_set_ringparam, .get_ringparam = ieee80211_get_ringparam,}

3.3 struct iw_handler_def 实例 cfg80211_wext_handler(wireless实现)

cfg80211_wext_handler实现了wext要求的ioctl操作，将通过net_device->wireless_handlers->standard[ioctl cmd- SIOCIWFIRST]来进行调用。在net/wireless/wext-compat.c中的定义如下所示：

static const iw_handler cfg80211_handlers[] = { [IW_IOCTL_IDX(SIOCGIWNAME)] = (iw_handler) cfg80211_wext_giwname, [IW_IOCTL_IDX(SIOCSIWFREQ)] = (iw_handler) cfg80211_wext_siwfreq, [IW_IOCTL_IDX(SIOCGIWFREQ)] = (iw_handler) cfg80211_wext_giwfreq, [IW_IOCTL_IDX(SIOCSIWMODE)] = (iw_handler) cfg80211_wext_siwmode, [IW_IOCTL_IDX(SIOCGIWMODE)] = (iw_handler) cfg80211_wext_giwmode, [IW_IOCTL_IDX(SIOCGIWRANGE)] = (iw_handler) cfg80211_wext_giwrange, [IW_IOCTL_IDX(SIOCSIWAP)] = (iw_handler) cfg80211_wext_siwap, [IW_IOCTL_IDX(SIOCGIWAP)] = (iw_handler) cfg80211_wext_giwap, [IW_IOCTL_IDX(SIOCSIWMLME)] = (iw_handler) cfg80211_wext_siwmlme, [IW_IOCTL_IDX(SIOCSIWSCAN)] = (iw_handler) cfg80211_wext_siwscan, [IW_IOCTL_IDX(SIOCGIWSCAN)] = (iw_handler) cfg80211_wext_giwscan, [IW_IOCTL_IDX(SIOCSIWESSID)] = (iw_handler) cfg80211_wext_siwessid, [IW_IOCTL_IDX(SIOCGIWESSID)] = (iw_handler) cfg80211_wext_giwessid, [IW_IOCTL_IDX(SIOCSIWRATE)] = (iw_handler) cfg80211_wext_siwrate, [IW_IOCTL_IDX(SIOCGIWRATE)] = (iw_handler) cfg80211_wext_giwrate, [IW_IOCTL_IDX(SIOCSIWRTS)] = (iw_handler) cfg80211_wext_siwrts, [IW_IOCTL_IDX(SIOCGIWRTS)] = (iw_handler) cfg80211_wext_giwrts, [IW_IOCTL_IDX(SIOCSIWFRAG)] = (iw_handler) cfg80211_wext_siwfrag, [IW_IOCTL_IDX(SIOCGIWFRAG)] = (iw_handler) cfg80211_wext_giwfrag, [IW_IOCTL_IDX(SIOCSIWTXPOW)] = (iw_handler) cfg80211_wext_siwtxpower, [IW_IOCTL_IDX(SIOCGIWTXPOW)] = (iw_handler) cfg80211_wext_giwtxpower, [IW_IOCTL_IDX(SIOCSIWRETRY)] = (iw_handler) cfg80211_wext_siwretry, [IW_IOCTL_IDX(SIOCGIWRETRY)] = (iw_handler) cfg80211_wext_giwretry, [IW_IOCTL_IDX(SIOCSIWENCODE)] = (iw_handler) cfg80211_wext_siwencode, [IW_IOCTL_IDX(SIOCGIWENCODE)] = (iw_handler) cfg80211_wext_giwencode, [IW_IOCTL_IDX(SIOCSIWPOWER)] = (iw_handler) cfg80211_wext_siwpower, [IW_IOCTL_IDX(SIOCGIWPOWER)] = (iw_handler) cfg80211_wext_giwpower, [IW_IOCTL_IDX(SIOCSIWGENIE)] = (iw_handler) cfg80211_wext_siwgenie, [IW_IOCTL_IDX(SIOCSIWAUTH)] = (iw_handler) cfg80211_wext_siwauth, [IW_IOCTL_IDX(SIOCGIWAUTH)] = (iw_handler) cfg80211_wext_giwauth, [IW_IOCTL_IDX(SIOCSIWENCODEEXT)]= (iw_handler) cfg80211_wext_siwencodeext, [IW_IOCTL_IDX(SIOCSIWPMKSA)] = (iw_handler) cfg80211_wext_siwpmksa,  [IW_IOCTL_IDX(SIOCSIWPRIV)] = (iw_handler)cfg80211_wext_setpriv};const struct iw_handler_def cfg80211_wext_handler = { .num_standard  = ARRAY_SIZE(cfg80211_handlers), .standard  = cfg80211_handlers, .get_wireless_stats = cfg80211_wireless_stats,}

4. 创建并注册net_device

当执行mac80211_config_ops-> ieee80211_add_iface时，它将创建net_device和对应的ieee80211_sub_if_data, 然后主要做了以下几件事：

1) 把net_device对应的名字增加到/sys/class/net/目录下

2) 把新创建的net_device插入到init_net->dev_base_head中

3) 通知上层协议，有一个新的net_device出现了，大家可以使用它了

4) 把新创建的ieee80211_sub_if_data增加到ieee80211_local的interfaces列表中

其流程如下图所示：

Linux Wireless架构总结

mac80211中定义的net_device_ops ieee80211_dataif_ops，以下这些方法，都有一个struct net_device参数。其具体定义如下：

static const struct net_device_ops ieee80211_dataif_ops = { .ndo_open  = ieee80211_open,              // net_device变换到 UP 时被调用 .ndo_stop  = ieee80211_stop,              // net_device变换到 Down 时被调用 .ndo_uninit  = ieee80211_teardown_sdata,    // 取消注册或注册失败时调用 .ndo_start_xmit  = ieee80211_subif_start_xmit,  // 需要发送包时被调用 .ndo_set_multicast_list = ieee80211_set_multicast_list,// 多播地址列表变化时被调用 .ndo_change_mtu  = ieee80211_change_mtu,        // 当用户想改变一个设备的MTU时被调用 .ndo_set_mac_address  = ieee80211_change_mac,        // mac地址需要改变时被调用 .ndo_select_queue = ieee80211_netdev_select_queue, //当net_device支持多个发送队列时，用来决定使用哪个队列};

mac80211中初始化net_device->netdev_ops:

static void ieee80211_if_setup(struct net_device *dev){ ether_setup(dev); dev->priv_flags &= ~IFF_TX_SKB_SHARING; dev->netdev_ops = &ieee80211_dataif_ops; dev->destructor = free_netdev;}

5. 数据接收(Data RX)流程

数据接收流程如下图所示：

Linux Wireless架构总结

IP层与TCP/UDP层接口定义如下：

static const struct net_protocol tcp_protocol = { .handler = tcp_v4_rcv, .err_handler = tcp_v4_err, .gso_send_check = tcp_v4_gso_send_check, .gso_segment = tcp_tso_segment, .gro_receive = tcp4_gro_receive, .gro_complete = tcp4_gro_complete, .no_policy = 1, .netns_ok = 1,};static const struct net_protocol udp_protocol = { .handler = udp_rcv, .err_handler = udp_err, .gso_send_check = udp4_ufo_send_check, .gso_segment = udp4_ufo_fragment, .no_policy = 1, .netns_ok = 1,};static const struct net_protocol icmp_protocol = { .handler = icmp_rcv, .err_handler = ping_err, .no_policy = 1, .netns_ok = 1,};

IP层与net/core层接口定义如下：

static struct packet_type ip_packet_type __read_mostly = { .type = cpu_to_be16(ETH_P_IP), .func = ip_rcv, .gso_send_check = inet_gso_send_check, .gso_segment = inet_gso_segment, .gro_receive = inet_gro_receive, .gro_complete = inet_gro_complete,};

Linux Wireless架构总结

接收下半部stack如下所示：

[  336.646628] [<c07d8b24>] (tcp_rcv_established+0x648/0x9b0) from [<c07e04cc>] (tcp_v4_do_rcv+0x74/0x2a8)[  336.646661] [<c07e04cc>] (tcp_v4_do_rcv+0x74/0x2a8) from [<c07e0c40>] (tcp_v4_rcv+0x540/0x908)[  336.646678] [<c07e0c40>] (tcp_v4_rcv+0x540/0x908) from [<c07c23d4>] (ip_local_deliver_finish+0x158/0x318)[  336.646694] [<c07c23d4>] (ip_local_deliver_finish+0x158/0x318) from [<c07c1e44>] (ip_rcv_finish+0x420/0x440)[  336.646715] [<c07c1e44>] (ip_rcv_finish+0x420/0x440) from [<c0772dcc>] (__netif_receive_skb+0x4d0/0x534)[  336.646730] [<c0772dcc>] (__netif_receive_skb+0x4d0/0x534) from [<c0774434>] (netif_receive_skb+0x9c/0xb4)[  336.646752] [<c0774434>] (netif_receive_skb+0x9c/0xb4) from [<c08b8e6c>] (ieee80211_deliver_skb+0x134/0x164)[  336.646769] [<c08b8e6c>] (ieee80211_deliver_skb+0x134/0x164) from [<c08b9ed8>] (ieee80211_rx_handlers+0x103c/0x1978)[  336.646785] [<c08b9ed8>] (ieee80211_rx_handlers+0x103c/0x1978) from [<c08baf10>] (ieee80211_prepare_and_rx_handle+0x6fc/0x788)[  336.646802] [<c08baf10>] (ieee80211_prepare_and_rx_handle+0x6fc/0x788) from [<c08bb920>] (ieee80211_rx+0x908/0x988)[  336.646819] [<c08bb920>] (ieee80211_rx+0x908/0x988) from [<c068a578>] (ath9k_rx_tasklet+0x4e4/0x54c)[  336.646835] [<c068a578>] (ath9k_rx_tasklet+0x4e4/0x54c) from [<c0467d98>] (tasklet_action+0xa8/0x14c)[  336.646850] [<c0467d98>] (tasklet_action+0xa8/0x14c) from [<c0468144>] (__do_softirq+0x88/0x158)[  336.646863] [<c0468144>] (__do_softirq+0x88/0x158) from [<c0468414>] (irq_exit+0x48/0xac)[  336.646882] [<c0468414>] (irq_exit+0x48/0xac) from [<c04313c0>] (do_local_timer+0x50/0x80)[  336.646898] [<c04313c0>] (do_local_timer+0x50/0x80) from [<c0436708>] (__irq_svc+0x48/0xe0)

6. 数据发送(Data TX)流珵

数据发送流程如下图所示：

Linux Wireless架构总结

上半部分涉及到的相关代码如下所示（以上流程主要通过dump_stack获取）：

net/socket.c
net/ipv4/af_net.c
net/ipv4/tcp.c
net/ipv4/tcp_output.c
net/ipv4/ip_output.c
net/core/neighbour.c
net/core/dev.c

7. INET初始化

INET为Linux OS实现了TCP/IP协议集，它使用BSD Socket接口作为与User通讯的方式。其初始化代码如下所示：

代码位于：net/ipv4/af_inet.c。

static int __init inet_init(void){ struct sk_buff *dummy_skb; struct inet_protosw *q; struct list_head *r; int rc = -EINVAL; BUILD_BUG_ON(sizeof(struct inet_skb_parm) > sizeof(dummy_skb->cb)); sysctl_local_reserved_ports = kzalloc(65536 / 8, GFP_KERNEL); if (!sysctl_local_reserved_ports)  goto out; rc = proto_register(&tcp_prot, 1); if (rc)  goto out_free_reserved_ports; rc = proto_register(&udp_prot, 1); if (rc)  goto out_unregister_tcp_proto; rc = proto_register(&raw_prot, 1); if (rc)  goto out_unregister_udp_proto; rc = proto_register(&ping_prot, 1); if (rc)  goto out_unregister_raw_proto; /*  * Tell SOCKET that we are alive...  */ (void)sock_register(&inet_family_ops);#ifdef CONFIG_SYSCTL ip_static_sysctl_init();#endif /*  * Add all the base protocols.  */ if (inet_add_protocol(&icmp_protocol, IPPROTO_ICMP) < 0)  printk(KERN_CRIT "inet_init: Cannot add ICMP protocol\n"); if (inet_add_protocol(&udp_protocol, IPPROTO_UDP) < 0)  printk(KERN_CRIT "inet_init: Cannot add UDP protocol\n"); if (inet_add_protocol(&tcp_protocol, IPPROTO_TCP) < 0)  printk(KERN_CRIT "inet_init: Cannot add TCP protocol\n");#ifdef CONFIG_IP_MULTICAST if (inet_add_protocol(&igmp_protocol, IPPROTO_IGMP) < 0)  printk(KERN_CRIT "inet_init: Cannot add IGMP protocol\n");#endif /* Register the socket-side information for inet_create. */ for (r = &inetsw[0]; r < &inetsw[SOCK_MAX]; ++r)  INIT_LIST_HEAD(r); for (q = inetsw_array; q < &inetsw_array[INETSW_ARRAY_LEN]; ++q)  inet_register_protosw(q); /*  * Set the ARP module up  */ arp_init(); /*  * Set the IP module up  */ ip_init(); tcp_v4_init(); /* Setup TCP slab cache for open requests. */ tcp_init(); /* Setup UDP memory threshold */ udp_init(); /* Add UDP-Lite (RFC 3828) */ udplite4_register(); ping_init(); /*  * Set the ICMP layer up  */ if (icmp_init() < 0)  panic("Failed to create the ICMP control socket.\n"); /*  * Initialise the multicast router  */#if defined(CONFIG_IP_MROUTE) if (ip_mr_init())  printk(KERN_CRIT "inet_init: Cannot init ipv4 mroute\n");#endif /*  * Initialise per-cpu ipv4 mibs  */ if (init_ipv4_mibs())  printk(KERN_CRIT "inet_init: Cannot init ipv4 mibs\n"); ipv4_proc_init(); ipfrag_init(); dev_add_pack(&ip_packet_type); rc = 0;out: return rc;out_unregister_raw_proto: proto_unregister(&raw_prot);out_unregister_udp_proto: proto_unregister(&udp_prot);out_unregister_tcp_proto: proto_unregister(&tcp_prot);out_free_reserved_ports: kfree(sysctl_local_reserved_ports); goto out;}