mac80211解析二
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在实现无线网络设备分配时，ieee80211_register_hw关联了ieee80211_ops结构体：
ieee80211_ops结构体是mac80211到设备驱动的回调操作函数集合，定义如下：
/** * struct ieee80211_ops - callbacks from mac80211 to the driver * * This structure contains various callbacks that the driver may * handle or, in some cases, must handle, for example to configure * the hardware to a new channel or to transmit a frame. */struct ieee80211_ops { void (*tx)(struct ieee80211_hw *hw, struct ieee80211_tx_control *control, struct sk_buff *skb); int (*start)(struct ieee80211_hw *hw); void (*stop)(struct ieee80211_hw *hw);#ifdef CONFIG_PM int (*suspend)(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan); int (*resume)(struct ieee80211_hw *hw); void (*set_wakeup)(struct ieee80211_hw *hw, bool enabled);#endif int (*add_interface)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); int (*change_interface)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, enum nl80211_iftype new_type, bool p2p); void (*remove_interface)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); int (*config)(struct ieee80211_hw *hw, u32 changed); void (*bss_info_changed)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_bss_conf *info, u32 changed); int (*start_ap)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); void (*stop_ap)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); u64 (*prepare_multicast)(struct ieee80211_hw *hw, struct netdev_hw_addr_list *mc_list); void (*configure_filter)(struct ieee80211_hw *hw, unsigned int changed_flags, unsigned int *total_flags, u64 multicast); int (*set_tim)(struct ieee80211_hw *hw, struct ieee80211_sta *sta, bool set); int (*set_key)(struct ieee80211_hw *hw, enum set_key_cmd cmd, struct ieee80211_vif *vif, struct ieee80211_sta *sta, struct ieee80211_key_conf *key); void (*update_tkip_key)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_key_conf *conf, struct ieee80211_sta *sta, u32 iv32, u16 *phase1key); void (*set_rekey_data)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct cfg80211_gtk_rekey_data *data); void (*set_default_unicast_key)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, int idx); int (*hw_scan)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct cfg80211_scan_request *req); void (*cancel_hw_scan)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); int (*sched_scan_start)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct cfg80211_sched_scan_request *req, struct ieee80211_sched_scan_ies *ies); int (*sched_scan_stop)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); void (*sw_scan_start)(struct ieee80211_hw *hw); void (*sw_scan_complete)(struct ieee80211_hw *hw); int (*get_stats)(struct ieee80211_hw *hw, struct ieee80211_low_level_stats *stats); void (*get_tkip_seq)(struct ieee80211_hw *hw, u8 hw_key_idx, u32 *iv32, u16 *iv16); int (*set_frag_threshold)(struct ieee80211_hw *hw, u32 value); int (*set_rts_threshold)(struct ieee80211_hw *hw, u32 value); int (*sta_add)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_sta *sta); int (*sta_remove)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_sta *sta);#ifdef CPTCFG_MAC80211_DEBUGFS void (*sta_add_debugfs)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_sta *sta, struct dentry *dir); void (*sta_remove_debugfs)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_sta *sta, struct dentry *dir);#endif void (*sta_notify)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, enum sta_notify_cmd, struct ieee80211_sta *sta); int (*sta_state)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_sta *sta, enum ieee80211_sta_state old_state, enum ieee80211_sta_state new_state); void (*sta_pre_rcu_remove)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_sta *sta); void (*sta_rc_update)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_sta *sta, u32 changed); int (*conf_tx)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, u16 ac, const struct ieee80211_tx_queue_params *params); u64 (*get_tsf)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); void (*set_tsf)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, u64 tsf); void (*reset_tsf)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); int (*tx_last_beacon)(struct ieee80211_hw *hw); int (*ampdu_action)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, enum ieee80211_ampdu_mlme_action action, struct ieee80211_sta *sta, u16 tid, u16 *ssn, u8 buf_size); int (*get_survey)(struct ieee80211_hw *hw, int idx, struct survey_info *survey); void (*rfkill_poll)(struct ieee80211_hw *hw); void (*set_coverage_class)(struct ieee80211_hw *hw, u8 coverage_class);#ifdef CPTCFG_NL80211_TESTMODE int (*testmode_cmd)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, void *data, int len); int (*testmode_dump)(struct ieee80211_hw *hw, struct sk_buff *skb, struct netlink_callback *cb, void *data, int len);#endif void (*flush)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, u32 queues, bool drop); void (*channel_switch)(struct ieee80211_hw *hw, struct ieee80211_channel_switch *ch_switch); int (*set_antenna)(struct ieee80211_hw *hw, u32 tx_ant, u32 rx_ant); int (*get_antenna)(struct ieee80211_hw *hw, u32 *tx_ant, u32 *rx_ant); int (*remain_on_channel)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_channel *chan, int duration, enum ieee80211_roc_type type); int (*cancel_remain_on_channel)(struct ieee80211_hw *hw); int (*set_ringparam)(struct ieee80211_hw *hw, u32 tx, u32 rx); void (*get_ringparam)(struct ieee80211_hw *hw, u32 *tx, u32 *tx_max, u32 *rx, u32 *rx_max); bool (*tx_frames_pending)(struct ieee80211_hw *hw); int (*set_bitrate_mask)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, const struct cfg80211_bitrate_mask *mask); void (*rssi_callback)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, enum ieee80211_rssi_event rssi_event); void (*allow_buffered_frames)(struct ieee80211_hw *hw, struct ieee80211_sta *sta, u16 tids, int num_frames, enum ieee80211_frame_release_type reason, bool more_data); void (*release_buffered_frames)(struct ieee80211_hw *hw, struct ieee80211_sta *sta, u16 tids, int num_frames, enum ieee80211_frame_release_type reason, bool more_data); int (*get_et_sset_count)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, int sset); void (*get_et_stats)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ethtool_stats *stats, u64 *data); void (*get_et_strings)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, u32 sset, u8 *data); int (*get_rssi)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_sta *sta, s8 *rssi_dbm); void (*mgd_prepare_tx)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); int (*add_chanctx)(struct ieee80211_hw *hw, struct ieee80211_chanctx_conf *ctx); void (*remove_chanctx)(struct ieee80211_hw *hw, struct ieee80211_chanctx_conf *ctx); void (*change_chanctx)(struct ieee80211_hw *hw, struct ieee80211_chanctx_conf *ctx, u32 changed); int (*assign_vif_chanctx)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_chanctx_conf *ctx); void (*unassign_vif_chanctx)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ieee80211_chanctx_conf *ctx); void (*restart_complete)(struct ieee80211_hw *hw);#if IS_ENABLED(CONFIG_IPV6) void (*ipv6_addr_change)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct inet6_dev *idev);#endif void (*channel_switch_beacon)(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct cfg80211_chan_def *chandef); int (*join_ibss)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); void (*leave_ibss)(struct ieee80211_hw *hw, struct ieee80211_vif *vif); u32 (*get_expected_throughput)(struct ieee80211_sta *sta);};
ieee80211_register_hw 中初始化了tasklet的响应中断，如下，
tasklet_init(&local->tasklet, ieee80211_tasklet_handler, (unsigned long) local);其中中断函数ieee80211_tasklet_handler 实现网络数据的中断接收。
static void ieee80211_tasklet_handler(unsigned long data){ struct ieee80211_local *local = (struct ieee80211_local *) data; struct sk_buff *skb; while ((skb = skb_dequeue(&local->skb_queue)) || (skb = skb_dequeue(&local->skb_queue_unreliable))) { switch (skb->pkt_type) { case IEEE80211_RX_MSG: /* Clear skb->pkt_type in order to not confuse kernel * netstack. */ skb->pkt_type = 0; ieee80211_rx(&local->hw, skb); break; case IEEE80211_TX_STATUS_MSG: skb->pkt_type = 0; ieee80211_tx_status(&local->hw, skb); break; default: WARN(1, "mac80211: Packet is of unknown type %d\n", skb->pkt_type); dev_kfree_skb(skb); break; } }}经过数据包的类型判断后，调用ieee80211_rx 函数进行数据接收，
/* * This is the receive path handler. It is called by a low level driver when an * 802.11 MPDU is received from the hardware. */void ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb){ struct ieee80211_local *local = hw_to_local(hw); struct ieee80211_rate *rate = NULL; struct ieee80211_supported_band *sband; struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); WARN_ON_ONCE(softirq_count() == 0); if (WARN_ON(status->band >= IEEE80211_NUM_BANDS)) goto drop; sband = local->hw.wiphy->bands[status->band]; if (WARN_ON(!sband)) goto drop; /* * If we're suspending, it is possible although not too likely * that we'd be receiving frames after having already partially * quiesced the stack. We can't process such frames then since * that might, for example, cause stations to be added or other * driver callbacks be invoked. */ if (unlikely(local->quiescing || local->suspended)) goto drop; /* We might be during a HW reconfig, prevent Rx for the same reason */ if (unlikely(local->in_reconfig)) goto drop; /* * The same happens when we're not even started, * but that's worth a warning. */ if (WARN_ON(!local->started)) goto drop; if (likely(!(status->flag & RX_FLAG_FAILED_PLCP_CRC))) { /* * Validate the rate, unless a PLCP error means that * we probably can't have a valid rate here anyway. */ if (status->flag & RX_FLAG_HT) { /* * rate_idx is MCS index, which can be [0-76] * as documented on: * * http://wireless.kernel.org/en/developers/Documentation/ieee80211/802.11n * * Anything else would be some sort of driver or * hardware error. The driver should catch hardware * errors. */ if (WARN(status->rate_idx > 76, "Rate marked as an HT rate but passed " "status->rate_idx is not " "an MCS index [0-76]: %d (0x%02x)\n", status->rate_idx, status->rate_idx)) goto drop; } else if (status->flag & RX_FLAG_VHT) { if (WARN_ONCE(status->rate_idx > 9 || !status->vht_nss || status->vht_nss > 8, "Rate marked as a VHT rate but data is invalid: MCS: %d, NSS: %d\n", status->rate_idx, status->vht_nss)) goto drop; } else { if (WARN_ON(status->rate_idx >= sband->n_bitrates)) goto drop; rate = &sband->bitrates[status->rate_idx]; } } status->rx_flags = 0; /* * key references and virtual interfaces are protected using RCU * and this requires that we are in a read-side RCU section during * receive processing */ rcu_read_lock(); /* * Frames with failed FCS/PLCP checksum are not returned, * all other frames are returned without radiotap header * if it was previously present. * Also, frames with less than 16 bytes are dropped. */ skb = ieee80211_rx_monitor(local, skb, rate); if (!skb) { rcu_read_unlock(); return; } ieee80211_tpt_led_trig_rx(local, ((struct ieee80211_hdr *)skb->data)->frame_control, skb->len); __ieee80211_rx_handle_packet(hw, skb); rcu_read_unlock(); return; drop: kfree_skb(skb);}在ieee80211_rx()函数中调用ieee80211_rx_monitor()拷贝帧传递给所有监听接口
/* * This function copies a received frame to all monitor interfaces and * returns a cleaned-up SKB that no longer includes the FCS nor the * radiotap header the driver might have added. */static struct sk_buff *ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb, struct ieee80211_rate *rate){ struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(origskb); struct ieee80211_sub_if_data *sdata; int needed_headroom; struct sk_buff *skb, *skb2; struct net_device *prev_dev = NULL; int present_fcs_len = 0; /* * First, we may need to make a copy of the skb because * (1) we need to modify it for radiotap (if not present), and * (2) the other RX handlers will modify the skb we got. * * We don't need to, of course, if we aren't going to return * the SKB because it has a bad FCS/PLCP checksum. */ if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) present_fcs_len = FCS_LEN; /* ensure hdr->frame_control is in skb head */ if (!pskb_may_pull(origskb, 2)) { dev_kfree_skb(origskb); return NULL; } if (!local->monitors) { if (should_drop_frame(origskb, present_fcs_len)) { dev_kfree_skb(origskb); return NULL; } return remove_monitor_info(local, origskb); } /* room for the radiotap header based on driver features */ needed_headroom = ieee80211_rx_radiotap_space(local, status); if (should_drop_frame(origskb, present_fcs_len)) { /* only need to expand headroom if necessary */ skb = origskb; origskb = NULL; /* * This shouldn't trigger often because most devices have an * RX header they pull before we get here, and that should * be big enough for our radiotap information. We should * probably export the length to drivers so that we can have * them allocate enough headroom to start with. */ if (skb_headroom(skb) < needed_headroom && pskb_expand_head(skb, needed_headroom, 0, GFP_ATOMIC)) { dev_kfree_skb(skb); return NULL; } } else { /* * Need to make a copy and possibly remove radiotap header * and FCS from the original. */ skb = skb_copy_expand(origskb, needed_headroom, 0, GFP_ATOMIC); origskb = remove_monitor_info(local, origskb); if (!skb) return origskb; } /* prepend radiotap information */ ieee80211_add_rx_radiotap_header(local, skb, rate, needed_headroom, true); skb_reset_mac_header(skb); skb->ip_summed = CHECKSUM_UNNECESSARY; skb->pkt_type = PACKET_OTHERHOST; skb->protocol = htons(ETH_P_802_2); list_for_each_entry_rcu(sdata, &local->interfaces, list) { if (sdata->vif.type != NL80211_IFTYPE_MONITOR) continue; if (sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES) continue; if (!ieee80211_sdata_running(sdata)) continue; if (prev_dev) { skb2 = skb_clone(skb, GFP_ATOMIC); if (skb2) { skb2->dev = prev_dev; netif_receive_skb(skb2); } } prev_dev = sdata->dev; sdata->dev->stats.rx_packets++; sdata->dev->stats.rx_bytes += skb->len; } if (prev_dev) { skb->dev = prev_dev; netif_receive_skb(skb); } else dev_kfree_skb(skb); return origskb;}ieee80211_rx 在调用__ieee80211_rx_handle_packet进行数据帧操作，
__ieee80211_rx_handle_packet ---->ieee80211_prepare_and_rx_handle ---->ieee80211_invoke_rx_handlers ---->ieee80211_rx_handlers 经过一些列数据帧的判别，最后在ieee80211_rx_handlers中实现接收处理。
在ieee80211_register_hw注册函数中，使用了ieee80211_if_add 函数创建了网络接口，并提供了网络接口操作函数net_device_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,}; 其中ieee80211_subif_start_xmit 实现了数据的发送，
/** * ieee80211_subif_start_xmit - netif start_xmit function for Ethernet-type * subinterfaces (wlan#, WDS, and VLAN interfaces) * This function takes in an Ethernet header and encapsulates it with suitable * IEEE 802.11 header based on which interface the packet is coming in. The * encapsulated packet will then be passed to master interface, wlan#.11, for * transmission (through low-level driver). */netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb, struct net_device *dev){ struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev); struct ieee80211_local *local = sdata->local; struct ieee80211_tx_info *info; int head_need; u16 ethertype, hdrlen, meshhdrlen = 0; __le16 fc; struct ieee80211_hdr hdr; struct ieee80211s_hdr mesh_hdr __maybe_unused; struct mesh_path __maybe_unused *mppath = NULL, *mpath = NULL; const u8 *encaps_data; int encaps_len, skip_header_bytes; int nh_pos, h_pos; struct sta_info *sta = NULL; bool wme_sta = false, authorized = false, tdls_auth = false; bool tdls_direct = false; bool multicast; u32 info_flags = 0; u16 info_id = 0; struct ieee80211_chanctx_conf *chanctx_conf; struct ieee80211_sub_if_data *ap_sdata; enum ieee80211_band band; if (unlikely(skb->len < ETH_HLEN)) goto fail; /* convert Ethernet header to proper 802.11 header (based on * operation mode) */ ethertype = (skb->data[12] << 8) | skb->data[13]; fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA); rcu_read_lock(); /* Measure frame arrival for Tx latency statistics calculation */ ieee80211_tx_latency_start_msrmnt(local, skb); switch (sdata->vif.type) { case NL80211_IFTYPE_AP_VLAN: sta = rcu_dereference(sdata->u.vlan.sta); if (sta) { fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS); /* RA TA DA SA */ memcpy(hdr.addr1, sta->sta.addr, ETH_ALEN); memcpy(hdr.addr2, sdata->vif.addr, ETH_ALEN); memcpy(hdr.addr3, skb->data, ETH_ALEN); memcpy(hdr.addr4, skb->data + ETH_ALEN, ETH_ALEN); hdrlen = 30; authorized = test_sta_flag(sta, WLAN_STA_AUTHORIZED); wme_sta = test_sta_flag(sta, WLAN_STA_WME); } ap_sdata = container_of(sdata->bss, struct ieee80211_sub_if_data, u.ap); chanctx_conf = rcu_dereference(ap_sdata->vif.chanctx_conf); if (!chanctx_conf) goto fail_rcu; band = chanctx_conf->def.chan->band; if (sta) break; /* fall through */ case NL80211_IFTYPE_AP: if (sdata->vif.type == NL80211_IFTYPE_AP) chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf); if (!chanctx_conf) goto fail_rcu; fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS); /* DA BSSID SA */ memcpy(hdr.addr1, skb->data, ETH_ALEN); memcpy(hdr.addr2, sdata->vif.addr, ETH_ALEN); memcpy(hdr.addr3, skb->data + ETH_ALEN, ETH_ALEN); hdrlen = 24; band = chanctx_conf->def.chan->band; break; case NL80211_IFTYPE_WDS: fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS); /* RA TA DA SA */ memcpy(hdr.addr1, sdata->u.wds.remote_addr, ETH_ALEN); memcpy(hdr.addr2, sdata->vif.addr, ETH_ALEN); memcpy(hdr.addr3, skb->data, ETH_ALEN); memcpy(hdr.addr4, skb->data + ETH_ALEN, ETH_ALEN); hdrlen = 30; /* * This is the exception! WDS style interfaces are prohibited * when channel contexts are in used so this must be valid */ band = local->hw.conf.chandef.chan->band; break;#ifdef CPTCFG_MAC80211_MESH case NL80211_IFTYPE_MESH_POINT: if (!is_multicast_ether_addr(skb->data)) { struct sta_info *next_hop; bool mpp_lookup = true; mpath = mesh_path_lookup(sdata, skb->data); if (mpath) { mpp_lookup = false; next_hop = rcu_dereference(mpath->next_hop); if (!next_hop || !(mpath->flags & (MESH_PATH_ACTIVE | MESH_PATH_RESOLVING))) mpp_lookup = true; } if (mpp_lookup) mppath = mpp_path_lookup(sdata, skb->data); if (mppath && mpath) mesh_path_del(mpath->sdata, mpath->dst); } /* * Use address extension if it is a packet from * another interface or if we know the destination * is being proxied by a portal (i.e. portal address * differs from proxied address) */ if (ether_addr_equal(sdata->vif.addr, skb->data + ETH_ALEN) && !(mppath && !ether_addr_equal(mppath->mpp, skb->data))) { hdrlen = ieee80211_fill_mesh_addresses(&hdr, &fc, skb->data, skb->data + ETH_ALEN); meshhdrlen = ieee80211_new_mesh_header(sdata, &mesh_hdr, NULL, NULL); } else { /* DS -> MBSS (802.11-2012 13.11.3.3). * For unicast with unknown forwarding information, * destination might be in the MBSS or if that fails * forwarded to another mesh gate. In either case * resolution will be handled in ieee80211_xmit(), so * leave the original DA. This also works for mcast */ const u8 *mesh_da = skb->data; if (mppath) mesh_da = mppath->mpp; else if (mpath) mesh_da = mpath->dst; hdrlen = ieee80211_fill_mesh_addresses(&hdr, &fc, mesh_da, sdata->vif.addr); if (is_multicast_ether_addr(mesh_da)) /* DA TA mSA AE:SA */ meshhdrlen = ieee80211_new_mesh_header( sdata, &mesh_hdr, skb->data + ETH_ALEN, NULL); else /* RA TA mDA mSA AE:DA SA */ meshhdrlen = ieee80211_new_mesh_header( sdata, &mesh_hdr, skb->data, skb->data + ETH_ALEN); } chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf); if (!chanctx_conf) goto fail_rcu; band = chanctx_conf->def.chan->band; break;#endif case NL80211_IFTYPE_STATION: if (sdata->wdev.wiphy->flags & WIPHY_FLAG_SUPPORTS_TDLS) { bool tdls_peer = false; sta = sta_info_get(sdata, skb->data); if (sta) { authorized = test_sta_flag(sta, WLAN_STA_AUTHORIZED); wme_sta = test_sta_flag(sta, WLAN_STA_WME); tdls_peer = test_sta_flag(sta, WLAN_STA_TDLS_PEER); tdls_auth = test_sta_flag(sta, WLAN_STA_TDLS_PEER_AUTH); } /* * If the TDLS link is enabled, send everything * directly. Otherwise, allow TDLS setup frames * to be transmitted indirectly. */ tdls_direct = tdls_peer && (tdls_auth || !(ethertype == ETH_P_TDLS && skb->len > 14 && skb->data[14] == WLAN_TDLS_SNAP_RFTYPE)); } if (tdls_direct) { /* link during setup - throw out frames to peer */ if (!tdls_auth) goto fail_rcu; /* DA SA BSSID */ memcpy(hdr.addr1, skb->data, ETH_ALEN); memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN); memcpy(hdr.addr3, sdata->u.mgd.bssid, ETH_ALEN); hdrlen = 24; } else if (sdata->u.mgd.use_4addr && cpu_to_be16(ethertype) != sdata->control_port_protocol) { fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS); /* RA TA DA SA */ memcpy(hdr.addr1, sdata->u.mgd.bssid, ETH_ALEN); memcpy(hdr.addr2, sdata->vif.addr, ETH_ALEN); memcpy(hdr.addr3, skb->data, ETH_ALEN); memcpy(hdr.addr4, skb->data + ETH_ALEN, ETH_ALEN); hdrlen = 30; } else { fc |= cpu_to_le16(IEEE80211_FCTL_TODS); /* BSSID SA DA */ memcpy(hdr.addr1, sdata->u.mgd.bssid, ETH_ALEN); memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN); memcpy(hdr.addr3, skb->data, ETH_ALEN); hdrlen = 24; } chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf); if (!chanctx_conf) goto fail_rcu; band = chanctx_conf->def.chan->band; break; case NL80211_IFTYPE_ADHOC: /* DA SA BSSID */ memcpy(hdr.addr1, skb->data, ETH_ALEN); memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN); memcpy(hdr.addr3, sdata->u.ibss.bssid, ETH_ALEN); hdrlen = 24; chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf); if (!chanctx_conf) goto fail_rcu; band = chanctx_conf->def.chan->band; break; default: goto fail_rcu; } /* * There's no need to try to look up the destination * if it is a multicast address (which can only happen * in AP mode) */ multicast = is_multicast_ether_addr(hdr.addr1); if (!multicast) { sta = sta_info_get(sdata, hdr.addr1); if (sta) { authorized = test_sta_flag(sta, WLAN_STA_AUTHORIZED); wme_sta = test_sta_flag(sta, WLAN_STA_WME); } } /* For mesh, the use of the QoS header is mandatory */ if (ieee80211_vif_is_mesh(&sdata->vif)) wme_sta = true; /* receiver and we are QoS enabled, use a QoS type frame */ if (wme_sta && local->hw.queues >= IEEE80211_NUM_ACS) { fc |= cpu_to_le16(IEEE80211_STYPE_QOS_DATA); hdrlen += 2; } /* * Drop unicast frames to unauthorised stations unless they are * EAPOL frames from the local station. */ if (unlikely(!ieee80211_vif_is_mesh(&sdata->vif) && !multicast && !authorized && (cpu_to_be16(ethertype) != sdata->control_port_protocol || !ether_addr_equal(sdata->vif.addr, skb->data + ETH_ALEN)))) {#ifdef CPTCFG_MAC80211_VERBOSE_DEBUG net_info_ratelimited("%s: dropped frame to %pM (unauthorized port)\n", dev->name, hdr.addr1);#endif I802_DEBUG_INC(local->tx_handlers_drop_unauth_port); goto fail_rcu; }#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,3,0)) if (unlikely(!multicast && skb->sk && skb_shinfo(skb)->tx_flags & SKBTX_WIFI_STATUS)) { struct sk_buff *orig_skb = skb; skb = skb_clone(skb, GFP_ATOMIC); if (skb) { unsigned long flags; int id; spin_lock_irqsave(&local->ack_status_lock, flags); id = idr_alloc(&local->ack_status_frames, orig_skb, 1, 0x10000, GFP_ATOMIC); spin_unlock_irqrestore(&local->ack_status_lock, flags); if (id >= 0) { info_id = id; info_flags |= IEEE80211_TX_CTL_REQ_TX_STATUS; } else if (skb_shared(skb)) { kfree_skb(orig_skb); } else { kfree_skb(skb); skb = orig_skb; } } else { /* couldn't clone -- lose tx status ... */ skb = orig_skb; } }#endif /* * If the skb is shared we need to obtain our own copy. */ if (skb_shared(skb)) { struct sk_buff *tmp_skb = skb; /* can't happen -- skb is a clone if info_id != 0 */ WARN_ON(info_id); skb = skb_clone(skb, GFP_ATOMIC); kfree_skb(tmp_skb); if (!skb) goto fail_rcu; } hdr.frame_control = fc; hdr.duration_id = 0; hdr.seq_ctrl = 0; skip_header_bytes = ETH_HLEN; if (ethertype == ETH_P_AARP || ethertype == ETH_P_IPX) { encaps_data = bridge_tunnel_header; encaps_len = sizeof(bridge_tunnel_header); skip_header_bytes -= 2; } else if (ethertype >= ETH_P_802_3_MIN) { encaps_data = rfc1042_header; encaps_len = sizeof(rfc1042_header); skip_header_bytes -= 2; } else { encaps_data = NULL; encaps_len = 0; } nh_pos = skb_network_header(skb) - skb->data; h_pos = skb_transport_header(skb) - skb->data; skb_pull(skb, skip_header_bytes); nh_pos -= skip_header_bytes; h_pos -= skip_header_bytes; head_need = hdrlen + encaps_len + meshhdrlen - skb_headroom(skb); /* * So we need to modify the skb header and hence need a copy of * that. The head_need variable above doesn't, so far, include * the needed header space that we don't need right away. If we * can, then we don't reallocate right now but only after the * frame arrives at the master device (if it does...) * * If we cannot, however, then we will reallocate to include all * the ever needed space. Also, if we need to reallocate it anyway, * make it big enough for everything we may ever need. */ if (head_need > 0 || skb_cloned(skb)) { head_need += sdata->encrypt_headroom; head_need += local->tx_headroom; head_need = max_t(int, 0, head_need); if (ieee80211_skb_resize(sdata, skb, head_need, true)) { ieee80211_free_txskb(&local->hw, skb); skb = NULL; goto fail_rcu; } } if (encaps_data) { memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len); nh_pos += encaps_len; h_pos += encaps_len; }#ifdef CPTCFG_MAC80211_MESH if (meshhdrlen > 0) { memcpy(skb_push(skb, meshhdrlen), &mesh_hdr, meshhdrlen); nh_pos += meshhdrlen; h_pos += meshhdrlen; }#endif if (ieee80211_is_data_qos(fc)) { __le16 *qos_control; qos_control = (__le16 *) skb_push(skb, 2); memcpy(skb_push(skb, hdrlen - 2), &hdr, hdrlen - 2); /* * Maybe we could actually set some fields here, for now just * initialise to zero to indicate no special operation. */ *qos_control = 0; } else memcpy(skb_push(skb, hdrlen), &hdr, hdrlen); nh_pos += hdrlen; h_pos += hdrlen; dev->stats.tx_packets++; dev->stats.tx_bytes += skb->len; /* Update skb pointers to various headers since this modified frame * is going to go through Linux networking code that may potentially * need things like pointer to IP header. */ skb_set_mac_header(skb, 0); skb_set_network_header(skb, nh_pos); skb_set_transport_header(skb, h_pos); info = IEEE80211_SKB_CB(skb); memset(info, 0, sizeof(*info)); dev->trans_start = jiffies; info->flags = info_flags; info->ack_frame_id = info_id; ieee80211_xmit(sdata, skb, band); rcu_read_unlock(); return NETDEV_TX_OK; fail_rcu: rcu_read_unlock(); fail: dev_kfree_skb(skb); return NETDEV_TX_OK;}调用ieee80211_tx 进行传输数据处理，
ieee80211_tx ----->invoke_tx_handlers ----->__ieee80211_tx ----->ieee80211_tx_frags ----->drv_tx最后调用drv_tx()，把帧传递给底层驱动：
static inline void drv_tx(struct ieee80211_local *local, struct ieee80211_tx_control *control, struct sk_buff *skb){ local->ops->tx(&local->hw, control, skb);} 可以看到，调用了ieee80211_ops中的tx() 实现数据的发送。
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