在ieee80211_register_hw函数中，实现了无线网络设备的的注册，网络接口的注册和建立主要由ieee80211_if_add 函数来完成，即：
result = ieee80211_if_add(local, "wlan%d", NULL, NL80211_IFTYPE_STATION, NULL);一般注册生成wlan0，函数ieee80211_if_add的内容如下：
int ieee80211_if_add(struct ieee80211_local *local, const char *name, struct wireless_dev **new_wdev, enum nl80211_iftype type, struct vif_params *params) { struct net_device *ndev = NULL; struct ieee80211_sub_if_data *sdata = NULL; int ret, i; int txqs = 1; ASSERT_RTNL(); if (type == NL80211_IFTYPE_P2P_DEVICE) { struct wireless_dev *wdev; sdata = kzalloc(sizeof(*sdata) + local->hw.vif_data_size, GFP_KERNEL); if (!sdata) return -ENOMEM; wdev = &sdata->wdev; sdata->dev = NULL; strlcpy(sdata->name, name, IFNAMSIZ); ieee80211_assign_perm_addr(local, wdev->address, type); memcpy(sdata->vif.addr, wdev->address, ETH_ALEN); } else { if (local->hw.queues >= IEEE80211_NUM_ACS) txqs = IEEE80211_NUM_ACS; ndev = alloc_netdev_mqs(sizeof(*sdata) + local->hw.vif_data_size, name, ieee80211_if_setup, txqs, 1); if (!ndev) return -ENOMEM; dev_net_set(ndev, wiphy_net(local->hw.wiphy)); 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; ret = dev_alloc_name(ndev, ndev->name); if (ret < 0) { free_netdev(ndev); return ret; } ieee80211_assign_perm_addr(local, ndev->perm_addr, type); memcpy(ndev->dev_addr, ndev->perm_addr, ETH_ALEN); SET_NETDEV_DEV(ndev, wiphy_dev(local->hw.wiphy)); /* don't use IEEE80211_DEV_TO_SUB_IF -- it checks too much */ sdata = netdev_priv(ndev); ndev->ieee80211_ptr = &sdata->wdev; memcpy(sdata->vif.addr, ndev->dev_addr, ETH_ALEN); memcpy(sdata->name, ndev->name, IFNAMSIZ); sdata->dev = ndev; } /* initialise type-independent data */ sdata->wdev.wiphy = local->hw.wiphy; sdata->local = local; for (i = 0; i < IEEE80211_FRAGMENT_MAX; i++) skb_queue_head_init(&sdata->fragments[i].skb_list); INIT_LIST_HEAD(&sdata->key_list); INIT_DELAYED_WORK(&sdata->dfs_cac_timer_work, ieee80211_dfs_cac_timer_work); INIT_DELAYED_WORK(&sdata->dec_tailroom_needed_wk, ieee80211_delayed_tailroom_dec); for (i = 0; i < IEEE80211_NUM_BANDS; i++) { struct ieee80211_supported_band *sband; sband = local->hw.wiphy->bands[i]; sdata->rc_rateidx_mask[i] = sband ? (1 << sband->n_bitrates) - 1 : 0; if (sband) memcpy(sdata->rc_rateidx_mcs_mask[i], sband->ht_cap.mcs.rx_mask, sizeof(sdata->rc_rateidx_mcs_mask[i])); else memset(sdata->rc_rateidx_mcs_mask[i], 0, sizeof(sdata->rc_rateidx_mcs_mask[i])); } ieee80211_set_default_queues(sdata); sdata->ap_power_level = IEEE80211_UNSET_POWER_LEVEL; sdata->user_power_level = local->user_power_level; sdata->encrypt_headroom = IEEE80211_ENCRYPT_HEADROOM; /* setup type-dependent data */ ieee80211_setup_sdata(sdata, type); if (ndev) { if (params) { ndev->ieee80211_ptr->use_4addr = params->use_4addr; if (type == NL80211_IFTYPE_STATION) sdata->u.mgd.use_4addr = params->use_4addr; } ndev->features |= local->hw.netdev_features; ret = register_netdevice(ndev); if (ret) { free_netdev(ndev); return ret; } } mutex_lock(&local->iflist_mtx); list_add_tail_rcu(&sdata->list, &local->interfaces); mutex_unlock(&local->iflist_mtx); if (new_wdev) *new_wdev = &sdata->wdev; return 0; }其中使用alloc_netdev_mqs 分配了网络设备的私有数据，并用setup函数建立网络接口，即ieee80211_if_setup 函数，该函数内容如下:
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 = ieee80211_if_free; }可以看到，这里分配的net_device的网络接口操作结构体netdev_ops=&ieee80211_dataif_ops, 其中ieee80211_dataif_ops定义如下：
static const struct net_device_ops ieee80211_dataif_ops = { .ndo_open = ieee80211_open, .ndo_stop = ieee80211_stop, .ndo_uninit = ieee80211_uninit, .ndo_start_xmit = ieee80211_subif_start_xmit, .ndo_set_rx_mode = ieee80211_set_multicast_list, .ndo_change_mtu = ieee80211_change_mtu, .ndo_set_mac_address = ieee80211_change_mac, .ndo_select_queue = ieee80211_netdev_select_queue, .ndo_get_stats64 = ieee80211_get_stats64, };然后ieee80211_if_add函数中继续初始化网络设备和sdata，使用ieee80211_setup_sdata函数建立网络接口依赖的data，内容如下：
/* * Helper function to initialise an interface to a specific type. */ static void ieee80211_setup_sdata(struct ieee80211_sub_if_data *sdata, enum nl80211_iftype type) { /* clear type-dependent union */ memset(&sdata->u, 0, sizeof(sdata->u)); /* and set some type-dependent values */ sdata->vif.type = type; sdata->vif.p2p = false; sdata->wdev.iftype = type; sdata->control_port_protocol = cpu_to_be16(ETH_P_PAE); sdata->control_port_no_encrypt = false; sdata->encrypt_headroom = IEEE80211_ENCRYPT_HEADROOM; sdata->noack_map = 0; /* only monitor/p2p-device differ */ if (sdata->dev) { sdata->dev->netdev_ops = &ieee80211_dataif_ops; sdata->dev->type = ARPHRD_ETHER; } skb_queue_head_init(&sdata->skb_queue); INIT_WORK(&sdata->work, ieee80211_iface_work); INIT_WORK(&sdata->recalc_smps, ieee80211_recalc_smps_work); INIT_WORK(&sdata->csa_finalize_work, ieee80211_csa_finalize_work); INIT_LIST_HEAD(&sdata->assigned_chanctx_list); INIT_LIST_HEAD(&sdata->reserved_chanctx_list); switch (type) { case NL80211_IFTYPE_P2P_GO: type = NL80211_IFTYPE_AP; sdata->vif.type = type; sdata->vif.p2p = true; /* fall through */ case NL80211_IFTYPE_AP: skb_queue_head_init(&sdata->u.ap.ps.bc_buf); INIT_LIST_HEAD(&sdata->u.ap.vlans); INIT_WORK(&sdata->u.ap.request_smps_work, ieee80211_request_smps_ap_work); sdata->vif.bss_conf.bssid = sdata->vif.addr; sdata->u.ap.req_smps = IEEE80211_SMPS_OFF; break; case NL80211_IFTYPE_P2P_CLIENT: type = NL80211_IFTYPE_STATION; sdata->vif.type = type; sdata->vif.p2p = true; /* fall through */ case NL80211_IFTYPE_STATION: sdata->vif.bss_conf.bssid = sdata->u.mgd.bssid; ieee80211_sta_setup_sdata(sdata); break; case NL80211_IFTYPE_ADHOC: sdata->vif.bss_conf.bssid = sdata->u.ibss.bssid; ieee80211_ibss_setup_sdata(sdata); break; case NL80211_IFTYPE_MESH_POINT: if (ieee80211_vif_is_mesh(&sdata->vif)) ieee80211_mesh_init_sdata(sdata); break; case NL80211_IFTYPE_MONITOR: sdata->dev->type = ARPHRD_IEEE80211_RADIOTAP; sdata->dev->netdev_ops = &ieee80211_monitorif_ops; sdata->u.mntr_flags = MONITOR_FLAG_CONTROL | MONITOR_FLAG_OTHER_BSS; break; case NL80211_IFTYPE_WDS: sdata->vif.bss_conf.bssid = NULL; break; case NL80211_IFTYPE_AP_VLAN: case NL80211_IFTYPE_P2P_DEVICE: sdata->vif.bss_conf.bssid = sdata->vif.addr; break; case NL80211_IFTYPE_UNSPECIFIED: case NUM_NL80211_IFTYPES: BUG(); break; } ieee80211_debugfs_add_netdev(sdata); }经过一些列分配和初始化之后，调用register_netdevice函数将网络设备接口进行注册。
最后通过：
list_add_tail_rcu(&sdata->list, &local->interfaces);把sdata对象加入local->interfaces，完成接口创建。
删除接口由用户空间通过nl80211发起，调用cfg80211_ops中的del_virtual_intf, 即ieee80211_del_iface函数，
static int ieee80211_del_iface(struct wiphy *wiphy, struct wireless_dev *wdev) { ieee80211_if_remove(IEEE80211_WDEV_TO_SUB_IF(wdev)); return 0; }ieee80211_if_remove函数：
void ieee80211_if_remove(struct ieee80211_sub_if_data *sdata) { ASSERT_RTNL(); mutex_lock(&sdata->local->iflist_mtx); list_del_rcu(&sdata->list); mutex_unlock(&sdata->local->iflist_mtx); synchronize_rcu(); if (sdata->dev) { unregister_netdevice(sdata->dev); } else { cfg80211_unregister_wdev(&sdata->wdev); ieee80211_teardown_sdata(sdata); kfree(sdata); } }把sdata对象从local->interfaces移除 ，然后注册网络接口，实现删除。
