/**
 * struct ieee80211_bss_conf - holds the BSS's changing parameters
 * 
 * This structure keeps information about a BSS (and an association
 * to that BSS) that can change during the lifetime of the BSS.
 * (省略)
 * @sync_tsf: last beacon's/probe response's TSF timestamp (could be old
 *  as it may have been received during scanning long ago). If the
 *  HW flag %IEEE80211_HW_TIMING_BEACON_ONLY is set, then this can
 *  only come from a beacon, but might not become valid until after
 *  association when a beacon is received (which is notified with the
 *  %BSS_CHANGED_DTIM flag.). See also sync_dtim_count important notice.
 * (省略)
 * @bssid: The BSSID for this BSS

struct ieee80211_bss_conf {
    const u8 *bssid;
    /* association related data */
    bool assoc, ibss_joined;
    bool ibss_creator;
    u16 aid;
    /* erp related data */
    bool use_cts_prot;
    bool use_short_preamble;
    bool use_short_slot;
    bool enable_beacon;
    u8 dtim_period;
    u16 beacon_int;
    u16 assoc_capability;
    u64 sync_tsf;
    u32 sync_device_ts;
    u8 sync_dtim_count;
    u32 basic_rates;
    struct ieee80211_rate *beacon_rate;
    int mcast_rate[NUM_NL80211_BANDS];
    u16 ht_operation_mode;
    s32 cqm_rssi_thold;
    u32 cqm_rssi_hyst;
    s32 cqm_rssi_low;
    s32 cqm_rssi_high;
    struct cfg80211_chan_def chandef;
    struct ieee80211_mu_group_data mu_group;
    __be32 arp_addr_list[IEEE80211_BSS_ARP_ADDR_LIST_LEN];
    int arp_addr_cnt;
    bool qos;
    bool idle;
    bool ps;
    u8 ssid[IEEE80211_MAX_SSID_LEN];
    size_t ssid_len;
    bool hidden_ssid;
    int txpower;
    enum nl80211_tx_power_setting txpower_type;
    struct ieee80211_p2p_noa_attr p2p_noa_attr;
    bool allow_p2p_go_ps;
    u16 max_idle_period;
    bool protected_keep_alive;
};

/**
 * struct ieee80211_rx_status - receive status
 *
 * The low-level driver should provide this information (the subset
 * supported by hardware) to the 802.11 code with each received
 * frame, in the skb's control buffer (cb).
 *
 * @mactime: value in microseconds of the 64-bit Time Synchronization Function
 *  (TSF) timer when the first data symbol (MPDU) arrived at the hardware.
 * @boottime_ns: CLOCK_BOOTTIME timestamp the frame was received at, this is
 *  needed only for beacons and probe responses that update the scan cache.
 * @device_timestamp: arbitrary timestamp for the device, mac80211 doesn't use
 *  it but can store it and pass it back to the driver for synchronisation
 * @band: the active band when this frame was received
 * @freq: frequency the radio was tuned to when receiving this frame, in MHz
 *  This field must be set for management frames, but isn't strictly needed
 *  for data (other) frames - for those it only affects radiotap reporting.
 * @signal: signal strength when receiving this frame, either in dBm, in dB or
 *  unspecified depending on the hardware capabilities flags
 *  @IEEE80211_HW_SIGNAL_*
 * @chains: bitmask of receive chains for which separate signal strength
 *  values were filled.
 * @chain_signal: per-chain signal strength, in dBm (unlike @signal, doesn't
 *  support dB or unspecified units)
 * @antenna: antenna used
 * @rate_idx: index of data rate into band's supported rates or MCS index if
 *  HT or VHT is used (%RX_FLAG_HT/%RX_FLAG_VHT)
 * @nss: number of streams (VHT and HE only)
 * @flag: %RX_FLAG_\*
 * @encoding: &enum mac80211_rx_encoding
 * @bw: &enum rate_info_bw
 * @enc_flags: uses bits from &enum mac80211_rx_encoding_flags
 * @rx_flags: internal RX flags for mac80211
 * @ampdu_reference: A-MPDU reference number, must be a different value for
 *  each A-MPDU but the same for each subframe within one A-MPDU
 * @ampdu_delimiter_crc: A-MPDU delimiter CRC
 */
struct ieee80211_rx_status {
    u64 mactime;
    u64 boottime_ns;
    u32 device_timestamp;
    u32 ampdu_reference;
    u32 flag;
    u16 freq;
    u8 enc_flags;
    u8 encoding:2, bw:3;
    u8 rate_idx;
    u8 nss;
    u8 rx_flags;
    u8 band;
    u8 antenna;
    s8 signal;
    u8 chains;
    s8 chain_signal[IEEE80211_MAX_CHAINS];
    u8 ampdu_delimiter_crc;
};

struct ieee80211_rx_data {
    struct napi_struct *napi;
    struct sk_buff *skb;
    struct ieee80211_local *local;
    struct ieee80211_sub_if_data *sdata;
    struct sta_info *sta;
    struct ieee80211_key *key;

    unsigned int flags;

    /*
     * Index into sequence numbers array, 0..16
     * since the last (16) is used for non-QoS,
     * will be 16 on non-QoS frames.
     */
    int seqno_idx;

    /*
     * Index into the security IV/PN arrays, 0..16
     * since the last (16) is used for CCMP-encrypted
     * management frames, will be set to 16 on mgmt
     * frames and 0 on non-QoS frames.
     */
    int security_idx;

    u32 tkip_iv32;
    u16 tkip_iv16;
};