/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007       Johannes Berg <johannes@sipsolutions.net>
 * Copyright 2013-2014  Intel Mobile Communications GmbH
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *
 * Transmit and frame generation functions.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
#include <linux/etherdevice.h>
#include <linux/bitmap.h>
#include <linux/rcupdate.h>
#include <linux/export.h>
#include <net/net_namespace.h>
#include <net/ieee80211_radiotap.h>
#include <net/cfg80211.h>
#include <net/mac80211.h>
#include <net/codel.h>
#include <net/codel_impl.h>
#include <asm/unaligned.h>
#include <net/fq_impl.h>

#include "ieee80211_i.h"
#include "driver-ops.h"
#include "led.h"
#include "mesh.h"
#include "wep.h"
#include "wpa.h"
#include "wme.h"
#include "rate.h"

/* misc utils */

static inline void ieee80211_tx_stats(struct net_device *dev, u32 len)
{
        struct pcpu_sw_netstats *tstats = this_cpu_ptr(dev->tstats);

        u64_stats_update_begin(&tstats->syncp);
        tstats->tx_packets++;
        tstats->tx_bytes += len;
        u64_stats_update_end(&tstats->syncp);
}

static __le16 ieee80211_duration(struct ieee80211_tx_data *tx,
                                 struct sk_buff *skb, int group_addr,
                                 int next_frag_len)
{
        int rate, mrate, erp, dur, i, shift = 0;
        struct ieee80211_rate *txrate;
        struct ieee80211_local *local = tx->local;
        struct ieee80211_supported_band *sband;
        struct ieee80211_hdr *hdr;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_chanctx_conf *chanctx_conf;
        u32 rate_flags = 0;

        /* assume HW handles this */
        if (tx->rate.flags & (IEEE80211_TX_RC_MCS | IEEE80211_TX_RC_VHT_MCS))
                return 0;

        rcu_read_lock();
        chanctx_conf = rcu_dereference(tx->sdata->vif.chanctx_conf);
        if (chanctx_conf) {
                shift = ieee80211_chandef_get_shift(&chanctx_conf->def);
                rate_flags = ieee80211_chandef_rate_flags(&chanctx_conf->def);
        }
        rcu_read_unlock();

        /* uh huh? */
        if (WARN_ON_ONCE(tx->rate.idx < 0))
                return 0;

        sband = local->hw.wiphy->bands[info->band];
        txrate = &sband->bitrates[tx->rate.idx];

        erp = txrate->flags & IEEE80211_RATE_ERP_G;

        /*
         * data and mgmt (except PS Poll):
         * - during CFP: 32768
         * - during contention period:
         *   if addr1 is group address: 0
         *   if more fragments = 0 and addr1 is individual address: time to
         *      transmit one ACK plus SIFS
         *   if more fragments = 1 and addr1 is individual address: time to
         *      transmit next fragment plus 2 x ACK plus 3 x SIFS
         *
         * IEEE 802.11, 9.6:
         * - control response frame (CTS or ACK) shall be transmitted using the
         *   same rate as the immediately previous frame in the frame exchange
         *   sequence, if this rate belongs to the PHY mandatory rates, or else
         *   at the highest possible rate belonging to the PHY rates in the
         *   BSSBasicRateSet
         */
        hdr = (struct ieee80211_hdr *)skb->data;
        if (ieee80211_is_ctl(hdr->frame_control)) {
                /* TODO: These control frames are not currently sent by
                 * mac80211, but should they be implemented, this function
                 * needs to be updated to support duration field calculation.
                 *
                 * RTS: time needed to transmit pending data/mgmt frame plus
                 *    one CTS frame plus one ACK frame plus 3 x SIFS
                 * CTS: duration of immediately previous RTS minus time
                 *    required to transmit CTS and its SIFS
                 * ACK: 0 if immediately previous directed data/mgmt had
                 *    more=0, with more=1 duration in ACK frame is duration
                 *    from previous frame minus time needed to transmit ACK
                 *    and its SIFS
                 * PS Poll: BIT(15) | BIT(14) | aid
                 */
                return 0;
        }

        /* data/mgmt */
        if (0 /* FIX: data/mgmt during CFP */)
                return cpu_to_le16(32768);

        if (group_addr) /* Group address as the destination - no ACK */
                return 0;

        /* Individual destination address:
         * IEEE 802.11, Ch. 9.6 (after IEEE 802.11g changes)
         * CTS and ACK frames shall be transmitted using the highest rate in
         * basic rate set that is less than or equal to the rate of the
         * immediately previous frame and that is using the same modulation
         * (CCK or OFDM). If no basic rate set matches with these requirements,
         * the highest mandatory rate of the PHY that is less than or equal to
         * the rate of the previous frame is used.
         * Mandatory rates for IEEE 802.11g PHY: 1, 2, 5.5, 11, 6, 12, 24 Mbps
         */
        rate = -1;
        /* use lowest available if everything fails */
        mrate = sband->bitrates[0].bitrate;
        for (i = 0; i < sband->n_bitrates; i++) {
                struct ieee80211_rate *r = &sband->bitrates[i];

                if (r->bitrate > txrate->bitrate)
                        break;

                if ((rate_flags & r->flags) != rate_flags)
                        continue;

                if (tx->sdata->vif.bss_conf.basic_rates & BIT(i))
                        rate = DIV_ROUND_UP(r->bitrate, 1 << shift);

                switch (sband->band) {
                case NL80211_BAND_2GHZ: {
                        u32 flag;
                        if (tx->sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
                                flag = IEEE80211_RATE_MANDATORY_G;
                        else
                                flag = IEEE80211_RATE_MANDATORY_B;
                        if (r->flags & flag)
                                mrate = r->bitrate;
                        break;
                }
                case NL80211_BAND_5GHZ:
                        if (r->flags & IEEE80211_RATE_MANDATORY_A)
                                mrate = r->bitrate;
                        break;
                case NL80211_BAND_60GHZ:
                        /* TODO, for now fall through */
                case NUM_NL80211_BANDS:
                        WARN_ON(1);
                        break;
                }
        }
        if (rate == -1) {
                /* No matching basic rate found; use highest suitable mandatory
                 * PHY rate */
                rate = DIV_ROUND_UP(mrate, 1 << shift);
        }

        /* Don't calculate ACKs for QoS Frames with NoAck Policy set */
        if (ieee80211_is_data_qos(hdr->frame_control) &&
            *(ieee80211_get_qos_ctl(hdr)) & IEEE80211_QOS_CTL_ACK_POLICY_NOACK)
                dur = 0;
        else
                /* Time needed to transmit ACK
                 * (10 bytes + 4-byte FCS = 112 bits) plus SIFS; rounded up
                 * to closest integer */
                dur = ieee80211_frame_duration(sband->band, 10, rate, erp,
                                tx->sdata->vif.bss_conf.use_short_preamble,
                                shift);

        if (next_frag_len) {
                /* Frame is fragmented: duration increases with time needed to
                 * transmit next fragment plus ACK and 2 x SIFS. */
                dur *= 2; /* ACK + SIFS */
                /* next fragment */
                dur += ieee80211_frame_duration(sband->band, next_frag_len,
                                txrate->bitrate, erp,
                                tx->sdata->vif.bss_conf.use_short_preamble,
                                shift);
        }

        return cpu_to_le16(dur);
}

/* tx handlers */
static ieee80211_tx_result debug_noinline
ieee80211_tx_h_dynamic_ps(struct ieee80211_tx_data *tx)
{
        struct ieee80211_local *local = tx->local;
        struct ieee80211_if_managed *ifmgd;

        /* driver doesn't support power save */
        if (!ieee80211_hw_check(&local->hw, SUPPORTS_PS))
                return TX_CONTINUE;

        /* hardware does dynamic power save */
        if (ieee80211_hw_check(&local->hw, SUPPORTS_DYNAMIC_PS))
                return TX_CONTINUE;

        /* dynamic power save disabled */
        if (local->hw.conf.dynamic_ps_timeout <= 0)
                return TX_CONTINUE;

        /* we are scanning, don't enable power save */
        if (local->scanning)
                return TX_CONTINUE;

        if (!local->ps_sdata)
                return TX_CONTINUE;

        /* No point if we're going to suspend */
        if (local->quiescing)
                return TX_CONTINUE;

        /* dynamic ps is supported only in managed mode */
        if (tx->sdata->vif.type != NL80211_IFTYPE_STATION)
                return TX_CONTINUE;

        ifmgd = &tx->sdata->u.mgd;

        /*
         * Don't wakeup from power save if u-apsd is enabled, voip ac has
         * u-apsd enabled and the frame is in voip class. This effectively
         * means that even if all access categories have u-apsd enabled, in
         * practise u-apsd is only used with the voip ac. This is a
         * workaround for the case when received voip class packets do not
         * have correct qos tag for some reason, due the network or the
         * peer application.
         *
         * Note: ifmgd->uapsd_queues access is racy here. If the value is
         * changed via debugfs, user needs to reassociate manually to have
         * everything in sync.
         */
        if ((ifmgd->flags & IEEE80211_STA_UAPSD_ENABLED) &&
            (ifmgd->uapsd_queues & IEEE80211_WMM_IE_STA_QOSINFO_AC_VO) &&
            skb_get_queue_mapping(tx->skb) == IEEE80211_AC_VO)
                return TX_CONTINUE;

        if (local->hw.conf.flags & IEEE80211_CONF_PS) {
                ieee80211_stop_queues_by_reason(&local->hw,
                                                IEEE80211_MAX_QUEUE_MAP,
                                                IEEE80211_QUEUE_STOP_REASON_PS,
                                                false);
                ifmgd->flags &= ~IEEE80211_STA_NULLFUNC_ACKED;
                ieee80211_queue_work(&local->hw,
                                     &local->dynamic_ps_disable_work);
        }

        /* Don't restart the timer if we're not disassociated */
        if (!ifmgd->associated)
                return TX_CONTINUE;

        mod_timer(&local->dynamic_ps_timer, jiffies +
                  msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));

        return TX_CONTINUE;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_check_assoc(struct ieee80211_tx_data *tx)
{

        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        bool assoc = false;

        if (unlikely(info->flags & IEEE80211_TX_CTL_INJECTED))
                return TX_CONTINUE;

        if (unlikely(test_bit(SCAN_SW_SCANNING, &tx->local->scanning)) &&
            test_bit(SDATA_STATE_OFFCHANNEL, &tx->sdata->state) &&
            !ieee80211_is_probe_req(hdr->frame_control) &&
            !ieee80211_is_nullfunc(hdr->frame_control))
                /*
                 * When software scanning only nullfunc frames (to notify
                 * the sleep state to the AP) and probe requests (for the
                 * active scan) are allowed, all other frames should not be
                 * sent and we should not get here, but if we do
                 * nonetheless, drop them to avoid sending them
                 * off-channel. See the link below and
                 * ieee80211_start_scan() for more.
                 *
                 * http://article.gmane.org/gmane.linux.kernel.wireless.general/30089
                 */
                return TX_DROP;

        if (tx->sdata->vif.type == NL80211_IFTYPE_OCB)
                return TX_CONTINUE;

        if (tx->sdata->vif.type == NL80211_IFTYPE_WDS)
                return TX_CONTINUE;

        if (tx->flags & IEEE80211_TX_PS_BUFFERED)
                return TX_CONTINUE;

        if (tx->sta)
                assoc = test_sta_flag(tx->sta, WLAN_STA_ASSOC);

        if (likely(tx->flags & IEEE80211_TX_UNICAST)) {
                if (unlikely(!assoc &&
                             ieee80211_is_data(hdr->frame_control))) {
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
                        sdata_info(tx->sdata,
                                   "dropped data frame to not associated station %pM\n",
                                   hdr->addr1);
#endif
                        I802_DEBUG_INC(tx->local->tx_handlers_drop_not_assoc);
                        return TX_DROP;
                }
        } else if (unlikely(ieee80211_is_data(hdr->frame_control) &&
                            ieee80211_vif_get_num_mcast_if(tx->sdata) == 0)) {
                /*
                 * No associated STAs - no need to send multicast
                 * frames.
                 */
                return TX_DROP;
        }

        return TX_CONTINUE;
}

/* This function is called whenever the AP is about to exceed the maximum limit
 * of buffered frames for power saving STAs. This situation should not really
 * happen often during normal operation, so dropping the oldest buffered packet
 * from each queue should be OK to make some room for new frames. */
static void purge_old_ps_buffers(struct ieee80211_local *local)
{
        int total = 0, purged = 0;
        struct sk_buff *skb;
        struct ieee80211_sub_if_data *sdata;
        struct sta_info *sta;

        list_for_each_entry_rcu(sdata, &local->interfaces, list) {
                struct ps_data *ps;

                if (sdata->vif.type == NL80211_IFTYPE_AP)
                        ps = &sdata->u.ap.ps;
                else if (ieee80211_vif_is_mesh(&sdata->vif))
                        ps = &sdata->u.mesh.ps;
                else
                        continue;

                skb = skb_dequeue(&ps->bc_buf);
                if (skb) {
                        purged++;
                        ieee80211_free_txskb(&local->hw, skb);
                }
                total += skb_queue_len(&ps->bc_buf);
        }

        /*
         * Drop one frame from each station from the lowest-priority
         * AC that has frames at all.
         */
        list_for_each_entry_rcu(sta, &local->sta_list, list) {
                int ac;

                for (ac = IEEE80211_AC_BK; ac >= IEEE80211_AC_VO; ac--) {
                        skb = skb_dequeue(&sta->ps_tx_buf[ac]);
                        total += skb_queue_len(&sta->ps_tx_buf[ac]);
                        if (skb) {
                                purged++;
                                ieee80211_free_txskb(&local->hw, skb);
                                break;
                        }
                }
        }

        local->total_ps_buffered = total;
        ps_dbg_hw(&local->hw, "PS buffers full - purged %d frames\n", purged);
}

static ieee80211_tx_result
ieee80211_tx_h_multicast_ps_buf(struct ieee80211_tx_data *tx)
{
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
        struct ps_data *ps;

        /*
         * broadcast/multicast frame
         *
         * If any of the associated/peer stations is in power save mode,
         * the frame is buffered to be sent after DTIM beacon frame.
         * This is done either by the hardware or us.
         */

        /* powersaving STAs currently only in AP/VLAN/mesh mode */
        if (tx->sdata->vif.type == NL80211_IFTYPE_AP ||
            tx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
                if (!tx->sdata->bss)
                        return TX_CONTINUE;

                ps = &tx->sdata->bss->ps;
        } else if (ieee80211_vif_is_mesh(&tx->sdata->vif)) {
                ps = &tx->sdata->u.mesh.ps;
        } else {
                return TX_CONTINUE;
        }


        /* no buffering for ordered frames */
        if (ieee80211_has_order(hdr->frame_control))
                return TX_CONTINUE;

        if (ieee80211_is_probe_req(hdr->frame_control))
                return TX_CONTINUE;

        if (ieee80211_hw_check(&tx->local->hw, QUEUE_CONTROL))
                info->hw_queue = tx->sdata->vif.cab_queue;

        /* no stations in PS mode */
        if (!atomic_read(&ps->num_sta_ps))
                return TX_CONTINUE;

        info->flags |= IEEE80211_TX_CTL_SEND_AFTER_DTIM;

        /* device releases frame after DTIM beacon */
        if (!ieee80211_hw_check(&tx->local->hw, HOST_BROADCAST_PS_BUFFERING))
                return TX_CONTINUE;

        /* buffered in mac80211 */
        if (tx->local->total_ps_buffered >= TOTAL_MAX_TX_BUFFER)
                purge_old_ps_buffers(tx->local);

        if (skb_queue_len(&ps->bc_buf) >= AP_MAX_BC_BUFFER) {
                ps_dbg(tx->sdata,
                       "BC TX buffer full - dropping the oldest frame\n");
                ieee80211_free_txskb(&tx->local->hw, skb_dequeue(&ps->bc_buf));
        } else
                tx->local->total_ps_buffered++;

        skb_queue_tail(&ps->bc_buf, tx->skb);

        return TX_QUEUED;
}

static int ieee80211_use_mfp(__le16 fc, struct sta_info *sta,
                             struct sk_buff *skb)
{
        if (!ieee80211_is_mgmt(fc))
                return 0;

        if (sta == NULL || !test_sta_flag(sta, WLAN_STA_MFP))
                return 0;

        if (!ieee80211_is_robust_mgmt_frame(skb))
                return 0;

        return 1;
}

static ieee80211_tx_result
ieee80211_tx_h_unicast_ps_buf(struct ieee80211_tx_data *tx)
{
        struct sta_info *sta = tx->sta;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
        struct ieee80211_local *local = tx->local;

        if (unlikely(!sta))
                return TX_CONTINUE;

        if (unlikely((test_sta_flag(sta, WLAN_STA_PS_STA) ||
                      test_sta_flag(sta, WLAN_STA_PS_DRIVER) ||
                      test_sta_flag(sta, WLAN_STA_PS_DELIVER)) &&
                     !(info->flags & IEEE80211_TX_CTL_NO_PS_BUFFER))) {
                int ac = skb_get_queue_mapping(tx->skb);

                if (ieee80211_is_mgmt(hdr->frame_control) &&
                    !ieee80211_is_bufferable_mmpdu(hdr->frame_control)) {
                        info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER;
                        return TX_CONTINUE;
                }

                ps_dbg(sta->sdata, "STA %pM aid %d: PS buffer for AC %d\n",
                       sta->sta.addr, sta->sta.aid, ac);
                if (tx->local->total_ps_buffered >= TOTAL_MAX_TX_BUFFER)
                        purge_old_ps_buffers(tx->local);

                /* sync with ieee80211_sta_ps_deliver_wakeup */
                spin_lock(&sta->ps_lock);
                /*
                 * STA woke up the meantime and all the frames on ps_tx_buf have
                 * been queued to pending queue. No reordering can happen, go
                 * ahead and Tx the packet.
                 */
                if (!test_sta_flag(sta, WLAN_STA_PS_STA) &&
                    !test_sta_flag(sta, WLAN_STA_PS_DRIVER) &&
                    !test_sta_flag(sta, WLAN_STA_PS_DELIVER)) {
                        spin_unlock(&sta->ps_lock);
                        return TX_CONTINUE;
                }

                if (skb_queue_len(&sta->ps_tx_buf[ac]) >= STA_MAX_TX_BUFFER) {
                        struct sk_buff *old = skb_dequeue(&sta->ps_tx_buf[ac]);
                        ps_dbg(tx->sdata,
                               "STA %pM TX buffer for AC %d full - dropping oldest frame\n",
                               sta->sta.addr, ac);
                        ieee80211_free_txskb(&local->hw, old);
                } else
                        tx->local->total_ps_buffered++;

                info->control.jiffies = jiffies;
                info->control.vif = &tx->sdata->vif;
                info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
                info->flags &= ~IEEE80211_TX_TEMPORARY_FLAGS;
                skb_queue_tail(&sta->ps_tx_buf[ac], tx->skb);
                spin_unlock(&sta->ps_lock);

                if (!timer_pending(&local->sta_cleanup))
                        mod_timer(&local->sta_cleanup,
                                  round_jiffies(jiffies +
                                                STA_INFO_CLEANUP_INTERVAL));

                /*
                 * We queued up some frames, so the TIM bit might
                 * need to be set, recalculate it.
                 */
                sta_info_recalc_tim(sta);

                return TX_QUEUED;
        } else if (unlikely(test_sta_flag(sta, WLAN_STA_PS_STA))) {
                ps_dbg(tx->sdata,
                       "STA %pM in PS mode, but polling/in SP -> send frame\n",
                       sta->sta.addr);
        }

        return TX_CONTINUE;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_ps_buf(struct ieee80211_tx_data *tx)
{
        if (unlikely(tx->flags & IEEE80211_TX_PS_BUFFERED))
                return TX_CONTINUE;

        if (tx->flags & IEEE80211_TX_UNICAST)
                return ieee80211_tx_h_unicast_ps_buf(tx);
        else
                return ieee80211_tx_h_multicast_ps_buf(tx);
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_check_control_port_protocol(struct ieee80211_tx_data *tx)
{
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);

        if (unlikely(tx->sdata->control_port_protocol == tx->skb->protocol)) {
                if (tx->sdata->control_port_no_encrypt)
                        info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
                info->control.flags |= IEEE80211_TX_CTRL_PORT_CTRL_PROTO;
                info->flags |= IEEE80211_TX_CTL_USE_MINRATE;
        }

        return TX_CONTINUE;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_select_key(struct ieee80211_tx_data *tx)
{
        struct ieee80211_key *key;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;

        if (unlikely(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT))
                tx->key = NULL;
        else if (tx->sta &&
                 (key = rcu_dereference(tx->sta->ptk[tx->sta->ptk_idx])))
                tx->key = key;
        else if (ieee80211_is_group_privacy_action(tx->skb) &&
                (key = rcu_dereference(tx->sdata->default_multicast_key)))
                tx->key = key;
        else if (ieee80211_is_mgmt(hdr->frame_control) &&
                 is_multicast_ether_addr(hdr->addr1) &&
                 ieee80211_is_robust_mgmt_frame(tx->skb) &&
                 (key = rcu_dereference(tx->sdata->default_mgmt_key)))
                tx->key = key;
        else if (is_multicast_ether_addr(hdr->addr1) &&
                 (key = rcu_dereference(tx->sdata->default_multicast_key)))
                tx->key = key;
        else if (!is_multicast_ether_addr(hdr->addr1) &&
                 (key = rcu_dereference(tx->sdata->default_unicast_key)))
                tx->key = key;
        else
                tx->key = NULL;

        if (tx->key) {
                bool skip_hw = false;

                /* TODO: add threshold stuff again */

                switch (tx->key->conf.cipher) {
                case WLAN_CIPHER_SUITE_WEP40:
                case WLAN_CIPHER_SUITE_WEP104:
                case WLAN_CIPHER_SUITE_TKIP:
                        if (!ieee80211_is_data_present(hdr->frame_control))
                                tx->key = NULL;
                        break;
                case WLAN_CIPHER_SUITE_CCMP:
                case WLAN_CIPHER_SUITE_CCMP_256:
                case WLAN_CIPHER_SUITE_GCMP:
                case WLAN_CIPHER_SUITE_GCMP_256:
                        if (!ieee80211_is_data_present(hdr->frame_control) &&
                            !ieee80211_use_mfp(hdr->frame_control, tx->sta,
                                               tx->skb) &&
                            !ieee80211_is_group_privacy_action(tx->skb))
                                tx->key = NULL;
                        else
                                skip_hw = (tx->key->conf.flags &
                                           IEEE80211_KEY_FLAG_SW_MGMT_TX) &&
                                        ieee80211_is_mgmt(hdr->frame_control);
                        break;
                case WLAN_CIPHER_SUITE_AES_CMAC:
                case WLAN_CIPHER_SUITE_BIP_CMAC_256:
                case WLAN_CIPHER_SUITE_BIP_GMAC_128:
                case WLAN_CIPHER_SUITE_BIP_GMAC_256:
                        if (!ieee80211_is_mgmt(hdr->frame_control))
                                tx->key = NULL;
                        break;
                }

                if (unlikely(tx->key && tx->key->flags & KEY_FLAG_TAINTED &&
                             !ieee80211_is_deauth(hdr->frame_control)))
                        return TX_DROP;

                if (!skip_hw && tx->key &&
                    tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)
                        info->control.hw_key = &tx->key->conf;
        }

        return TX_CONTINUE;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_rate_ctrl(struct ieee80211_tx_data *tx)
{
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        struct ieee80211_hdr *hdr = (void *)tx->skb->data;
        struct ieee80211_supported_band *sband;
        u32 len;
        struct ieee80211_tx_rate_control txrc;
        struct ieee80211_sta_rates *ratetbl = NULL;
        bool assoc = false;

        memset(&txrc, 0, sizeof(txrc));

        sband = tx->local->hw.wiphy->bands[info->band];

        len = min_t(u32, tx->skb->len + FCS_LEN,
                         tx->local->hw.wiphy->frag_threshold);

        /* set up the tx rate control struct we give the RC algo */
        txrc.hw = &tx->local->hw;
        txrc.sband = sband;
        txrc.bss_conf = &tx->sdata->vif.bss_conf;
        txrc.skb = tx->skb;
        txrc.reported_rate.idx = -1;
        txrc.rate_idx_mask = tx->sdata->rc_rateidx_mask[info->band];

        if (tx->sdata->rc_has_mcs_mask[info->band])
                txrc.rate_idx_mcs_mask =
                        tx->sdata->rc_rateidx_mcs_mask[info->band];

        txrc.bss = (tx->sdata->vif.type == NL80211_IFTYPE_AP ||
                    tx->sdata->vif.type == NL80211_IFTYPE_MESH_POINT ||
                    tx->sdata->vif.type == NL80211_IFTYPE_ADHOC ||
                    tx->sdata->vif.type == NL80211_IFTYPE_OCB);

        /* set up RTS protection if desired */
        if (len > tx->local->hw.wiphy->rts_threshold) {
                txrc.rts = true;
        }

        info->control.use_rts = txrc.rts;
        info->control.use_cts_prot = tx->sdata->vif.bss_conf.use_cts_prot;

        /*
         * Use short preamble if the BSS can handle it, but not for
         * management frames unless we know the receiver can handle
         * that -- the management frame might be to a station that
         * just wants a probe response.
         */
        if (tx->sdata->vif.bss_conf.use_short_preamble &&
            (ieee80211_is_data(hdr->frame_control) ||
             (tx->sta && test_sta_flag(tx->sta, WLAN_STA_SHORT_PREAMBLE))))
                txrc.short_preamble = true;

        info->control.short_preamble = txrc.short_preamble;

        /* don't ask rate control when rate already injected via radiotap */
        if (info->control.flags & IEEE80211_TX_CTRL_RATE_INJECT)
                return TX_CONTINUE;

        if (tx->sta)
                assoc = test_sta_flag(tx->sta, WLAN_STA_ASSOC);

        /*
         * Lets not bother rate control if we're associated and cannot
         * talk to the sta. This should not happen.
         */
        if (WARN(test_bit(SCAN_SW_SCANNING, &tx->local->scanning) && assoc &&
                 !rate_usable_index_exists(sband, &tx->sta->sta),
                 "%s: Dropped data frame as no usable bitrate found while "
                 "scanning and associated. Target station: "
                 "%pM on %d GHz band\n",
                 tx->sdata->name, hdr->addr1,
                 info->band ? 5 : 2))
                return TX_DROP;

        /*
         * If we're associated with the sta at this point we know we can at
         * least send the frame at the lowest bit rate.
         */
        rate_control_get_rate(tx->sdata, tx->sta, &txrc);

        if (tx->sta && !info->control.skip_table)
                ratetbl = rcu_dereference(tx->sta->sta.rates);

        if (unlikely(info->control.rates[0].idx < 0)) {
                if (ratetbl) {
                        struct ieee80211_tx_rate rate = {
                                .idx = ratetbl->rate[0].idx,
                                .flags = ratetbl->rate[0].flags,
                                .count = ratetbl->rate[0].count
                        };

                        if (ratetbl->rate[0].idx < 0)
                                return TX_DROP;

                        tx->rate = rate;
                } else {
                        return TX_DROP;
                }
        } else {
                tx->rate = info->control.rates[0];
        }

        if (txrc.reported_rate.idx < 0) {
                txrc.reported_rate = tx->rate;
                if (tx->sta && ieee80211_is_data(hdr->frame_control))
                        tx->sta->tx_stats.last_rate = txrc.reported_rate;
        } else if (tx->sta)
                tx->sta->tx_stats.last_rate = txrc.reported_rate;

        if (ratetbl)
                return TX_CONTINUE;

        if (unlikely(!info->control.rates[0].count))
                info->control.rates[0].count = 1;

        if (WARN_ON_ONCE((info->control.rates[0].count > 1) &&
                         (info->flags & IEEE80211_TX_CTL_NO_ACK)))
                info->control.rates[0].count = 1;

        return TX_CONTINUE;
}

static __le16 ieee80211_tx_next_seq(struct sta_info *sta, int tid)
{
        u16 *seq = &sta->tid_seq[tid];
        __le16 ret = cpu_to_le16(*seq);

        /* Increase the sequence number. */
        *seq = (*seq + 0x10) & IEEE80211_SCTL_SEQ;

        return ret;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_sequence(struct ieee80211_tx_data *tx)
{
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)tx->skb->data;
        u8 *qc;
        int tid;

        /*
         * Packet injection may want to control the sequence
         * number, if we have no matching interface then we
         * neither assign one ourselves nor ask the driver to.
         */
        if (unlikely(info->control.vif->type == NL80211_IFTYPE_MONITOR))
                return TX_CONTINUE;

        if (unlikely(ieee80211_is_ctl(hdr->frame_control)))
                return TX_CONTINUE;

        if (ieee80211_hdrlen(hdr->frame_control) < 24)
                return TX_CONTINUE;

        if (ieee80211_is_qos_nullfunc(hdr->frame_control))
                return TX_CONTINUE;

        /*
         * Anything but QoS data that has a sequence number field
         * (is long enough) gets a sequence number from the global
         * counter.  QoS data frames with a multicast destination
         * also use the global counter (802.11-2012 9.3.2.10).
         */
        if (!ieee80211_is_data_qos(hdr->frame_control) ||
            is_multicast_ether_addr(hdr->addr1)) {
                /* driver should assign sequence number */
                info->flags |= IEEE80211_TX_CTL_ASSIGN_SEQ;
                /* for pure STA mode without beacons, we can do it */
                hdr->seq_ctrl = cpu_to_le16(tx->sdata->sequence_number);
                tx->sdata->sequence_number += 0x10;
                if (tx->sta)
                        tx->sta->tx_stats.msdu[IEEE80211_NUM_TIDS]++;
                return TX_CONTINUE;
        }

        /*
         * This should be true for injected/management frames only, for
         * management frames we have set the IEEE80211_TX_CTL_ASSIGN_SEQ
         * above since they are not QoS-data frames.
         */
        if (!tx->sta)
                return TX_CONTINUE;

        /* include per-STA, per-TID sequence counter */

        qc = ieee80211_get_qos_ctl(hdr);
        tid = *qc & IEEE80211_QOS_CTL_TID_MASK;
        tx->sta->tx_stats.msdu[tid]++;

        hdr->seq_ctrl = ieee80211_tx_next_seq(tx->sta, tid);

        return TX_CONTINUE;
}

static int ieee80211_fragment(struct ieee80211_tx_data *tx,
                              struct sk_buff *skb, int hdrlen,
                              int frag_threshold)
{
        struct ieee80211_local *local = tx->local;
        struct ieee80211_tx_info *info;
        struct sk_buff *tmp;
        int per_fragm = frag_threshold - hdrlen - FCS_LEN;
        int pos = hdrlen + per_fragm;
        int rem = skb->len - hdrlen - per_fragm;

        if (WARN_ON(rem < 0))
                return -EINVAL;

        /* first fragment was already added to queue by caller */

        while (rem) {
                int fraglen = per_fragm;

                if (fraglen > rem)
                        fraglen = rem;
                rem -= fraglen;
                tmp = dev_alloc_skb(local->tx_headroom +
                                    frag_threshold +
                                    tx->sdata->encrypt_headroom +
                                    IEEE80211_ENCRYPT_TAILROOM);
                if (!tmp)
                        return -ENOMEM;

                __skb_queue_tail(&tx->skbs, tmp);

                skb_reserve(tmp,
                            local->tx_headroom + tx->sdata->encrypt_headroom);

                /* copy control information */
                memcpy(tmp->cb, skb->cb, sizeof(tmp->cb));

                info = IEEE80211_SKB_CB(tmp);
                info->flags &= ~(IEEE80211_TX_CTL_CLEAR_PS_FILT |
                                 IEEE80211_TX_CTL_FIRST_FRAGMENT);

                if (rem)
                        info->flags |= IEEE80211_TX_CTL_MORE_FRAMES;

                skb_copy_queue_mapping(tmp, skb);
                tmp->priority = skb->priority;
                tmp->dev = skb->dev;

                /* copy header and data */
                skb_put_data(tmp, skb->data, hdrlen);
                skb_put_data(tmp, skb->data + pos, fraglen);

                pos += fraglen;
        }

        /* adjust first fragment's length */
        skb_trim(skb, hdrlen + per_fragm);
        return 0;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_fragment(struct ieee80211_tx_data *tx)
{
        struct sk_buff *skb = tx->skb;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_hdr *hdr = (void *)skb->data;
        int frag_threshold = tx->local->hw.wiphy->frag_threshold;
        int hdrlen;
        int fragnum;

        /* no matter what happens, tx->skb moves to tx->skbs */
        __skb_queue_tail(&tx->skbs, skb);
        tx->skb = NULL;

        if (info->flags & IEEE80211_TX_CTL_DONTFRAG)
                return TX_CONTINUE;

        if (ieee80211_hw_check(&tx->local->hw, SUPPORTS_TX_FRAG))
                return TX_CONTINUE;

        /*
         * Warn when submitting a fragmented A-MPDU frame and drop it.
         * This scenario is handled in ieee80211_tx_prepare but extra
         * caution taken here as fragmented ampdu may cause Tx stop.
         */
        if (WARN_ON(info->flags & IEEE80211_TX_CTL_AMPDU))
                return TX_DROP;

        hdrlen = ieee80211_hdrlen(hdr->frame_control);

        /* internal error, why isn't DONTFRAG set? */
        if (WARN_ON(skb->len + FCS_LEN <= frag_threshold))
                return TX_DROP;

        /*
         * Now fragment the frame. This will allocate all the fragments and
         * chain them (using skb as the first fragment) to skb->next.
         * During transmission, we will remove the successfully transmitted
         * fragments from this list. When the low-level driver rejects one
         * of the fragments then we will simply pretend to accept the skb
         * but store it away as pending.
         */
        if (ieee80211_fragment(tx, skb, hdrlen, frag_threshold))
                return TX_DROP;

        /* update duration/seq/flags of fragments */
        fragnum = 0;

        skb_queue_walk(&tx->skbs, skb) {
                const __le16 morefrags = cpu_to_le16(IEEE80211_FCTL_MOREFRAGS);

                hdr = (void *)skb->data;
                info = IEEE80211_SKB_CB(skb);

                if (!skb_queue_is_last(&tx->skbs, skb)) {
                        hdr->frame_control |= morefrags;
                        /*
                         * No multi-rate retries for fragmented frames, that
                         * would completely throw off the NAV at other STAs.
                         */
                        info->control.rates[1].idx = -1;
                        info->control.rates[2].idx = -1;
                        info->control.rates[3].idx = -1;
                        BUILD_BUG_ON(IEEE80211_TX_MAX_RATES != 4);
                        info->flags &= ~IEEE80211_TX_CTL_RATE_CTRL_PROBE;
                } else {
                        hdr->frame_control &= ~morefrags;
                }
                hdr->seq_ctrl |= cpu_to_le16(fragnum & IEEE80211_SCTL_FRAG);
                fragnum++;
        }

        return TX_CONTINUE;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_stats(struct ieee80211_tx_data *tx)
{
        struct sk_buff *skb;
        int ac = -1;

        if (!tx->sta)
                return TX_CONTINUE;

        skb_queue_walk(&tx->skbs, skb) {
                ac = skb_get_queue_mapping(skb);
                tx->sta->tx_stats.bytes[ac] += skb->len;
        }
        if (ac >= 0)
                tx->sta->tx_stats.packets[ac]++;

        return TX_CONTINUE;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_encrypt(struct ieee80211_tx_data *tx)
{
        if (!tx->key)
                return TX_CONTINUE;

        switch (tx->key->conf.cipher) {
        case WLAN_CIPHER_SUITE_WEP40:
        case WLAN_CIPHER_SUITE_WEP104:
                return ieee80211_crypto_wep_encrypt(tx);
        case WLAN_CIPHER_SUITE_TKIP:
                return ieee80211_crypto_tkip_encrypt(tx);
        case WLAN_CIPHER_SUITE_CCMP:
                return ieee80211_crypto_ccmp_encrypt(
                        tx, IEEE80211_CCMP_MIC_LEN);
        case WLAN_CIPHER_SUITE_CCMP_256:
                return ieee80211_crypto_ccmp_encrypt(
                        tx, IEEE80211_CCMP_256_MIC_LEN);
        case WLAN_CIPHER_SUITE_AES_CMAC:
                return ieee80211_crypto_aes_cmac_encrypt(tx);
        case WLAN_CIPHER_SUITE_BIP_CMAC_256:
                return ieee80211_crypto_aes_cmac_256_encrypt(tx);
        case WLAN_CIPHER_SUITE_BIP_GMAC_128:
        case WLAN_CIPHER_SUITE_BIP_GMAC_256:
                return ieee80211_crypto_aes_gmac_encrypt(tx);
        case WLAN_CIPHER_SUITE_GCMP:
        case WLAN_CIPHER_SUITE_GCMP_256:
                return ieee80211_crypto_gcmp_encrypt(tx);
        default:
                return ieee80211_crypto_hw_encrypt(tx);
        }

        return TX_DROP;
}

static ieee80211_tx_result debug_noinline
ieee80211_tx_h_calculate_duration(struct ieee80211_tx_data *tx)
{
        struct sk_buff *skb;
        struct ieee80211_hdr *hdr;
        int next_len;
        bool group_addr;

        skb_queue_walk(&tx->skbs, skb) {
                hdr = (void *) skb->data;
                if (unlikely(ieee80211_is_pspoll(hdr->frame_control)))
                        break; /* must not overwrite AID */
                if (!skb_queue_is_last(&tx->skbs, skb)) {
                        struct sk_buff *next = skb_queue_next(&tx->skbs, skb);
                        next_len = next->len;
                } else
                        next_len = 0;
                group_addr = is_multicast_ether_addr(hdr->addr1);

                hdr->duration_id =
                        ieee80211_duration(tx, skb, group_addr, next_len);
        }

        return TX_CONTINUE;
}

/* actual transmit path */

static bool ieee80211_tx_prep_agg(struct ieee80211_tx_data *tx,
                                  struct sk_buff *skb,
                                  struct ieee80211_tx_info *info,
                                  struct tid_ampdu_tx *tid_tx,
                                  int tid)
{
        bool queued = false;
        bool reset_agg_timer = false;
        struct sk_buff *purge_skb = NULL;

        if (test_bit(HT_AGG_STATE_OPERATIONAL, &tid_tx->state)) {
                info->flags |= IEEE80211_TX_CTL_AMPDU;
                reset_agg_timer = true;
        } else if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state)) {
                /*
                 * nothing -- this aggregation session is being started
                 * but that might still fail with the driver
                 */
        } else if (!tx->sta->sta.txq[tid]) {
                spin_lock(&tx->sta->lock);
                /*
                 * Need to re-check now, because we may get here
                 *
                 *  1) in the window during which the setup is actually
                 *     already done, but not marked yet because not all
                 *     packets are spliced over to the driver pending
                 *     queue yet -- if this happened we acquire the lock
                 *     either before or after the splice happens, but
                 *     need to recheck which of these cases happened.
                 *
                 *  2) during session teardown, if the OPERATIONAL bit
                 *     was cleared due to the teardown but the pointer
                 *     hasn't been assigned NULL yet (or we loaded it
                 *     before it was assigned) -- in this case it may
                 *     now be NULL which means we should just let the
                 *     packet pass through because splicing the frames
                 *     back is already done.
                 */
                tid_tx = rcu_dereference_protected_tid_tx(tx->sta, tid);

                if (!tid_tx) {
                        /* do nothing, let packet pass through */
                } else if (test_bit(HT_AGG_STATE_OPERATIONAL, &tid_tx->state)) {
                        info->flags |= IEEE80211_TX_CTL_AMPDU;
                        reset_agg_timer = true;
                } else {
                        queued = true;
                        if (info->flags & IEEE80211_TX_CTL_NO_PS_BUFFER) {
                                clear_sta_flag(tx->sta, WLAN_STA_SP);
                                ps_dbg(tx->sta->sdata,
                                       "STA %pM aid %d: SP frame queued, close the SP w/o telling the peer\n",
                                       tx->sta->sta.addr, tx->sta->sta.aid);
                        }
                        info->control.vif = &tx->sdata->vif;
                        info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
                        info->flags &= ~IEEE80211_TX_TEMPORARY_FLAGS;
                        __skb_queue_tail(&tid_tx->pending, skb);
                        if (skb_queue_len(&tid_tx->pending) > STA_MAX_TX_BUFFER)
                                purge_skb = __skb_dequeue(&tid_tx->pending);
                }
                spin_unlock(&tx->sta->lock);

                if (purge_skb)
                        ieee80211_free_txskb(&tx->local->hw, purge_skb);
        }

        /* reset session timer */
        if (reset_agg_timer && tid_tx->timeout)
                tid_tx->last_tx = jiffies;

        return queued;
}

/*
 * initialises @tx
 * pass %NULL for the station if unknown, a valid pointer if known
 * or an ERR_PTR() if the station is known not to exist
 */
static ieee80211_tx_result
ieee80211_tx_prepare(struct ieee80211_sub_if_data *sdata,
                     struct ieee80211_tx_data *tx,
                     struct sta_info *sta, struct sk_buff *skb)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_hdr *hdr;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        int tid;
        u8 *qc;

        memset(tx, 0, sizeof(*tx));
        tx->skb = skb;
        tx->local = local;
        tx->sdata = sdata;
        __skb_queue_head_init(&tx->skbs);

        /*
         * If this flag is set to true anywhere, and we get here,
         * we are doing the needed processing, so remove the flag
         * now.
         */
        info->flags &= ~IEEE80211_TX_INTFL_NEED_TXPROCESSING;

        hdr = (struct ieee80211_hdr *) skb->data;

        if (likely(sta)) {
                if (!IS_ERR(sta))
                        tx->sta = sta;
        } else {
                if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
                        tx->sta = rcu_dereference(sdata->u.vlan.sta);
                        if (!tx->sta && sdata->wdev.use_4addr)
                                return TX_DROP;
                } else if (info->flags & (IEEE80211_TX_INTFL_NL80211_FRAME_TX |
                                          IEEE80211_TX_CTL_INJECTED) ||
                           tx->sdata->control_port_protocol == tx->skb->protocol) {
                        tx->sta = sta_info_get_bss(sdata, hdr->addr1);
                }
                if (!tx->sta && !is_multicast_ether_addr(hdr->addr1))
                        tx->sta = sta_info_get(sdata, hdr->addr1);
        }

        if (tx->sta && ieee80211_is_data_qos(hdr->frame_control) &&
            !ieee80211_is_qos_nullfunc(hdr->frame_control) &&
            ieee80211_hw_check(&local->hw, AMPDU_AGGREGATION) &&
            !ieee80211_hw_check(&local->hw, TX_AMPDU_SETUP_IN_HW)) {
                struct tid_ampdu_tx *tid_tx;

                qc = ieee80211_get_qos_ctl(hdr);
                tid = *qc & IEEE80211_QOS_CTL_TID_MASK;

                tid_tx = rcu_dereference(tx->sta->ampdu_mlme.tid_tx[tid]);
                if (tid_tx) {
                        bool queued;

                        queued = ieee80211_tx_prep_agg(tx, skb, info,
                                                       tid_tx, tid);

                        if (unlikely(queued))
                                return TX_QUEUED;
                }
        }

        if (is_multicast_ether_addr(hdr->addr1)) {
                tx->flags &= ~IEEE80211_TX_UNICAST;
                info->flags |= IEEE80211_TX_CTL_NO_ACK;
        } else
                tx->flags |= IEEE80211_TX_UNICAST;

        if (!(info->flags & IEEE80211_TX_CTL_DONTFRAG)) {
                if (!(tx->flags & IEEE80211_TX_UNICAST) ||
                    skb->len + FCS_LEN <= local->hw.wiphy->frag_threshold ||
                    info->flags & IEEE80211_TX_CTL_AMPDU)
                        info->flags |= IEEE80211_TX_CTL_DONTFRAG;
        }

        if (!tx->sta)
                info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;
        else if (test_and_clear_sta_flag(tx->sta, WLAN_STA_CLEAR_PS_FILT)) {
                info->flags |= IEEE80211_TX_CTL_CLEAR_PS_FILT;
                ieee80211_check_fast_xmit(tx->sta);
        }

        info->flags |= IEEE80211_TX_CTL_FIRST_FRAGMENT;

        return TX_CONTINUE;
}

static struct txq_info *ieee80211_get_txq(struct ieee80211_local *local,
                                          struct ieee80211_vif *vif,
                                          struct sta_info *sta,
                                          struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_txq *txq = NULL;

        if ((info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM) ||
            (info->control.flags & IEEE80211_TX_CTRL_PS_RESPONSE))
                return NULL;

        if (!ieee80211_is_data(hdr->frame_control))
                return NULL;

        if (sta) {
                u8 tid = skb->priority & IEEE80211_QOS_CTL_TID_MASK;

                if (!sta->uploaded)
                        return NULL;

                txq = sta->sta.txq[tid];
        } else if (vif) {
                txq = vif->txq;
        }

        if (!txq)
                return NULL;

        return to_txq_info(txq);
}

static void ieee80211_set_skb_enqueue_time(struct sk_buff *skb)
{
        IEEE80211_SKB_CB(skb)->control.enqueue_time = codel_get_time();
}

static void ieee80211_set_skb_vif(struct sk_buff *skb, struct txq_info *txqi)
{
        IEEE80211_SKB_CB(skb)->control.vif = txqi->txq.vif;
}

static u32 codel_skb_len_func(const struct sk_buff *skb)
{
        return skb->len;
}

static codel_time_t codel_skb_time_func(const struct sk_buff *skb)
{
        const struct ieee80211_tx_info *info;

        info = (const struct ieee80211_tx_info *)skb->cb;
        return info->control.enqueue_time;
}

static struct sk_buff *codel_dequeue_func(struct codel_vars *cvars,
                                          void *ctx)
{
        struct ieee80211_local *local;
        struct txq_info *txqi;
        struct fq *fq;
        struct fq_flow *flow;

        txqi = ctx;
        local = vif_to_sdata(txqi->txq.vif)->local;
        fq = &local->fq;

        if (cvars == &txqi->def_cvars)
                flow = &txqi->def_flow;
        else
                flow = &fq->flows[cvars - local->cvars];

        return fq_flow_dequeue(fq, flow);
}

static void codel_drop_func(struct sk_buff *skb,
                            void *ctx)
{
        struct ieee80211_local *local;
        struct ieee80211_hw *hw;
        struct txq_info *txqi;

        txqi = ctx;
        local = vif_to_sdata(txqi->txq.vif)->local;
        hw = &local->hw;

        ieee80211_free_txskb(hw, skb);
}

static struct sk_buff *fq_tin_dequeue_func(struct fq *fq,
                                           struct fq_tin *tin,
                                           struct fq_flow *flow)
{
        struct ieee80211_local *local;
        struct txq_info *txqi;
        struct codel_vars *cvars;
        struct codel_params *cparams;
        struct codel_stats *cstats;

        local = container_of(fq, struct ieee80211_local, fq);
        txqi = container_of(tin, struct txq_info, tin);
        cstats = &txqi->cstats;

        if (txqi->txq.sta) {
                struct sta_info *sta = container_of(txqi->txq.sta,
                                                    struct sta_info, sta);
                cparams = &sta->cparams;
        } else {
                cparams = &local->cparams;
        }

        if (flow == &txqi->def_flow)
                cvars = &txqi->def_cvars;
        else
                cvars = &local->cvars[flow - fq->flows];

        return codel_dequeue(txqi,
                             &flow->backlog,
                             cparams,
                             cvars,
                             cstats,
                             codel_skb_len_func,
                             codel_skb_time_func,
                             codel_drop_func,
                             codel_dequeue_func);
}

static void fq_skb_free_func(struct fq *fq,
                             struct fq_tin *tin,
                             struct fq_flow *flow,
                             struct sk_buff *skb)
{
        struct ieee80211_local *local;

        local = container_of(fq, struct ieee80211_local, fq);
        ieee80211_free_txskb(&local->hw, skb);
}

static struct fq_flow *fq_flow_get_default_func(struct fq *fq,
                                                struct fq_tin *tin,
                                                int idx,
                                                struct sk_buff *skb)
{
        struct txq_info *txqi;

        txqi = container_of(tin, struct txq_info, tin);
        return &txqi->def_flow;
}

static void ieee80211_txq_enqueue(struct ieee80211_local *local,
                                  struct txq_info *txqi,
                                  struct sk_buff *skb)
{
        struct fq *fq = &local->fq;
        struct fq_tin *tin = &txqi->tin;

        ieee80211_set_skb_enqueue_time(skb);
        fq_tin_enqueue(fq, tin, skb,
                       fq_skb_free_func,
                       fq_flow_get_default_func);
}

void ieee80211_txq_init(struct ieee80211_sub_if_data *sdata,
                        struct sta_info *sta,
                        struct txq_info *txqi, int tid)
{
        fq_tin_init(&txqi->tin);
        fq_flow_init(&txqi->def_flow);
        codel_vars_init(&txqi->def_cvars);
        codel_stats_init(&txqi->cstats);
        __skb_queue_head_init(&txqi->frags);

        txqi->txq.vif = &sdata->vif;

        if (sta) {
                txqi->txq.sta = &sta->sta;
                sta->sta.txq[tid] = &txqi->txq;
                txqi->txq.tid = tid;
                txqi->txq.ac = ieee80211_ac_from_tid(tid);
        } else {
                sdata->vif.txq = &txqi->txq;
                txqi->txq.tid = 0;
                txqi->txq.ac = IEEE80211_AC_BE;
        }
}

void ieee80211_txq_purge(struct ieee80211_local *local,
                         struct txq_info *txqi)
{
        struct fq *fq = &local->fq;
        struct fq_tin *tin = &txqi->tin;

        fq_tin_reset(fq, tin, fq_skb_free_func);
        ieee80211_purge_tx_queue(&local->hw, &txqi->frags);
}

int ieee80211_txq_setup_flows(struct ieee80211_local *local)
{
        struct fq *fq = &local->fq;
        int ret;
        int i;
        bool supp_vht = false;
        enum nl80211_band band;

        if (!local->ops->wake_tx_queue)
                return 0;

        ret = fq_init(fq, 4096);
        if (ret)
                return ret;

        /*
         * If the hardware doesn't support VHT, it is safe to limit the maximum
         * queue size. 4 Mbytes is 64 max-size aggregates in 802.11n.
         */
        for (band = 0; band < NUM_NL80211_BANDS; band++) {
                struct ieee80211_supported_band *sband;

                sband = local->hw.wiphy->bands[band];
                if (!sband)
                        continue;

                supp_vht = supp_vht || sband->vht_cap.vht_supported;
        }

        if (!supp_vht)
                fq->memory_limit = 4 << 20; /* 4 Mbytes */

        codel_params_init(&local->cparams);
        local->cparams.interval = MS2TIME(100);
        local->cparams.target = MS2TIME(20);
        local->cparams.ecn = true;

        local->cvars = kcalloc(fq->flows_cnt, sizeof(local->cvars[0]),
                               GFP_KERNEL);
        if (!local->cvars) {
                spin_lock_bh(&fq->lock);
                fq_reset(fq, fq_skb_free_func);
                spin_unlock_bh(&fq->lock);
                return -ENOMEM;
        }

        for (i = 0; i < fq->flows_cnt; i++)
                codel_vars_init(&local->cvars[i]);

        return 0;
}

void ieee80211_txq_teardown_flows(struct ieee80211_local *local)
{
        struct fq *fq = &local->fq;

        if (!local->ops->wake_tx_queue)
                return;

        kfree(local->cvars);
        local->cvars = NULL;

        spin_lock_bh(&fq->lock);
        fq_reset(fq, fq_skb_free_func);
        spin_unlock_bh(&fq->lock);
}

static bool ieee80211_queue_skb(struct ieee80211_local *local,
                                struct ieee80211_sub_if_data *sdata,
                                struct sta_info *sta,
                                struct sk_buff *skb)
{
        struct fq *fq = &local->fq;
        struct ieee80211_vif *vif;
        struct txq_info *txqi;

        if (!local->ops->wake_tx_queue ||
            sdata->vif.type == NL80211_IFTYPE_MONITOR)
                return false;

        if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
                sdata = container_of(sdata->bss,
                                     struct ieee80211_sub_if_data, u.ap);

        vif = &sdata->vif;
        txqi = ieee80211_get_txq(local, vif, sta, skb);

        if (!txqi)
                return false;

        spin_lock_bh(&fq->lock);
        ieee80211_txq_enqueue(local, txqi, skb);
        spin_unlock_bh(&fq->lock);

        drv_wake_tx_queue(local, txqi);

        return true;
}

static bool ieee80211_tx_frags(struct ieee80211_local *local,
                               struct ieee80211_vif *vif,
                               struct ieee80211_sta *sta,
                               struct sk_buff_head *skbs,
                               bool txpending)
{
        struct ieee80211_tx_control control = {};
        struct sk_buff *skb, *tmp;
        unsigned long flags;

        skb_queue_walk_safe(skbs, skb, tmp) {
                struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
                int q = info->hw_queue;

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
                if (WARN_ON_ONCE(q >= local->hw.queues)) {
                        __skb_unlink(skb, skbs);
                        ieee80211_free_txskb(&local->hw, skb);
                        continue;
                }
#endif

                spin_lock_irqsave(&local->queue_stop_reason_lock, flags);
                if (local->queue_stop_reasons[q] ||
                    (!txpending && !skb_queue_empty(&local->pending[q]))) {
                        if (unlikely(info->flags &
                                     IEEE80211_TX_INTFL_OFFCHAN_TX_OK)) {
                                if (local->queue_stop_reasons[q] &
                                    ~BIT(IEEE80211_QUEUE_STOP_REASON_OFFCHANNEL)) {
                                        /*
                                         * Drop off-channel frames if queues
                                         * are stopped for any reason other
                                         * than off-channel operation. Never
                                         * queue them.
                                         */
                                        spin_unlock_irqrestore(
                                                &local->queue_stop_reason_lock,
                                                flags);
                                        ieee80211_purge_tx_queue(&local->hw,
                                                                 skbs);
                                        return true;
                                }
                        } else {

                                /*
                                 * Since queue is stopped, queue up frames for
                                 * later transmission from the tx-pending
                                 * tasklet when the queue is woken again.
                                 */
                                if (txpending)
                                        skb_queue_splice_init(skbs,
                                                              &local->pending[q]);
                                else
                                        skb_queue_splice_tail_init(skbs,
                                                                   &local->pending[q]);

                                spin_unlock_irqrestore(&local->queue_stop_reason_lock,
                                                       flags);
                                return false;
                        }
                }
                spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);

                info->control.vif = vif;
                control.sta = sta;

                __skb_unlink(skb, skbs);
                drv_tx(local, &control, skb);
        }

        return true;
}

/*
 * Returns false if the frame couldn't be transmitted but was queued instead.
 */
static bool __ieee80211_tx(struct ieee80211_local *local,
                           struct sk_buff_head *skbs, int led_len,
                           struct sta_info *sta, bool txpending)
{
        struct ieee80211_tx_info *info;
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_vif *vif;
        struct ieee80211_sta *pubsta;
        struct sk_buff *skb;
        bool result = true;
        __le16 fc;

        if (WARN_ON(skb_queue_empty(skbs)))
                return true;

        skb = skb_peek(skbs);
        fc = ((struct ieee80211_hdr *)skb->data)->frame_control;
        info = IEEE80211_SKB_CB(skb);
        sdata = vif_to_sdata(info->control.vif);
        if (sta && !sta->uploaded)
                sta = NULL;

        if (sta)
                pubsta = &sta->sta;
        else
                pubsta = NULL;

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_MONITOR:
                if (sdata->u.mntr.flags & MONITOR_FLAG_ACTIVE) {
                        vif = &sdata->vif;
                        break;
                }
                sdata = rcu_dereference(local->monitor_sdata);
                if (sdata) {
                        vif = &sdata->vif;
                        info->hw_queue =
                                vif->hw_queue[skb_get_queue_mapping(skb)];
                } else if (ieee80211_hw_check(&local->hw, QUEUE_CONTROL)) {
                        ieee80211_purge_tx_queue(&local->hw, skbs);
                        return true;
                } else
                        vif = NULL;
                break;
        case NL80211_IFTYPE_AP_VLAN:
                sdata = container_of(sdata->bss,
                                     struct ieee80211_sub_if_data, u.ap);
                /* fall through */
        default:
                vif = &sdata->vif;
                break;
        }

        result = ieee80211_tx_frags(local, vif, pubsta, skbs,
                                    txpending);

        ieee80211_tpt_led_trig_tx(local, fc, led_len);

        WARN_ON_ONCE(!skb_queue_empty(skbs));

        return result;
}

/*
 * Invoke TX handlers, return 0 on success and non-zero if the
 * frame was dropped or queued.
 *
 * The handlers are split into an early and late part. The latter is everything
 * that can be sensitive to reordering, and will be deferred to after packets
 * are dequeued from the intermediate queues (when they are enabled).
 */
static int invoke_tx_handlers_early(struct ieee80211_tx_data *tx)
{
        ieee80211_tx_result res = TX_DROP;

#define CALL_TXH(txh) \
        do {                            \
                res = txh(tx);          \
                if (res != TX_CONTINUE) \
                        goto txh_done;  \
        } while (0)

        CALL_TXH(ieee80211_tx_h_dynamic_ps);
        CALL_TXH(ieee80211_tx_h_check_assoc);
        CALL_TXH(ieee80211_tx_h_ps_buf);
        CALL_TXH(ieee80211_tx_h_check_control_port_protocol);
        CALL_TXH(ieee80211_tx_h_select_key);
        if (!ieee80211_hw_check(&tx->local->hw, HAS_RATE_CONTROL))
                CALL_TXH(ieee80211_tx_h_rate_ctrl);

 txh_done:
        if (unlikely(res == TX_DROP)) {
                I802_DEBUG_INC(tx->local->tx_handlers_drop);
                if (tx->skb)
                        ieee80211_free_txskb(&tx->local->hw, tx->skb);
                else
                        ieee80211_purge_tx_queue(&tx->local->hw, &tx->skbs);
                return -1;
        } else if (unlikely(res == TX_QUEUED)) {
                I802_DEBUG_INC(tx->local->tx_handlers_queued);
                return -1;
        }

        return 0;
}

/*
 * Late handlers can be called while the sta lock is held. Handlers that can
 * cause packets to be generated will cause deadlock!
 */
static int invoke_tx_handlers_late(struct ieee80211_tx_data *tx)
{
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
        ieee80211_tx_result res = TX_CONTINUE;

        if (unlikely(info->flags & IEEE80211_TX_INTFL_RETRANSMISSION)) {
                __skb_queue_tail(&tx->skbs, tx->skb);
                tx->skb = NULL;
                goto txh_done;
        }

        CALL_TXH(ieee80211_tx_h_michael_mic_add);
        CALL_TXH(ieee80211_tx_h_sequence);
        CALL_TXH(ieee80211_tx_h_fragment);
        /* handlers after fragment must be aware of tx info fragmentation! */
        CALL_TXH(ieee80211_tx_h_stats);
        CALL_TXH(ieee80211_tx_h_encrypt);
        if (!ieee80211_hw_check(&tx->local->hw, HAS_RATE_CONTROL))
                CALL_TXH(ieee80211_tx_h_calculate_duration);
#undef CALL_TXH

 txh_done:
        if (unlikely(res == TX_DROP)) {
                I802_DEBUG_INC(tx->local->tx_handlers_drop);
                if (tx->skb)
                        ieee80211_free_txskb(&tx->local->hw, tx->skb);
                else
                        ieee80211_purge_tx_queue(&tx->local->hw, &tx->skbs);
                return -1;
        } else if (unlikely(res == TX_QUEUED)) {
                I802_DEBUG_INC(tx->local->tx_handlers_queued);
                return -1;
        }

        return 0;
}

static int invoke_tx_handlers(struct ieee80211_tx_data *tx)
{
        int r = invoke_tx_handlers_early(tx);

        if (r)
                return r;
        return invoke_tx_handlers_late(tx);
}

bool ieee80211_tx_prepare_skb(struct ieee80211_hw *hw,
                              struct ieee80211_vif *vif, struct sk_buff *skb,
                              int band, struct ieee80211_sta **sta)
{
        struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_tx_data tx;
        struct sk_buff *skb2;

        if (ieee80211_tx_prepare(sdata, &tx, NULL, skb) == TX_DROP)
                return false;

        info->band = band;
        info->control.vif = vif;
        info->hw_queue = vif->hw_queue[skb_get_queue_mapping(skb)];

        if (invoke_tx_handlers(&tx))
                return false;

        if (sta) {
                if (tx.sta)
                        *sta = &tx.sta->sta;
                else
                        *sta = NULL;
        }

        /* this function isn't suitable for fragmented data frames */
        skb2 = __skb_dequeue(&tx.skbs);
        if (WARN_ON(skb2 != skb || !skb_queue_empty(&tx.skbs))) {
                ieee80211_free_txskb(hw, skb2);
                ieee80211_purge_tx_queue(hw, &tx.skbs);
                return false;
        }

        return true;
}
EXPORT_SYMBOL(ieee80211_tx_prepare_skb);

/*
 * Returns false if the frame couldn't be transmitted but was queued instead.
 */
static bool ieee80211_tx(struct ieee80211_sub_if_data *sdata,
                         struct sta_info *sta, struct sk_buff *skb,
                         bool txpending)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_tx_data tx;
        ieee80211_tx_result res_prepare;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        bool result = true;
        int led_len;

        if (unlikely(skb->len < 10)) {
                dev_kfree_skb(skb);
                return true;
        }

        /* initialises tx */
        led_len = skb->len;
        res_prepare = ieee80211_tx_prepare(sdata, &tx, sta, skb);

        if (unlikely(res_prepare == TX_DROP)) {
                ieee80211_free_txskb(&local->hw, skb);
                return true;
        } else if (unlikely(res_prepare == TX_QUEUED)) {
                return true;
        }

        /* set up hw_queue value early */
        if (!(info->flags & IEEE80211_TX_CTL_TX_OFFCHAN) ||
            !ieee80211_hw_check(&local->hw, QUEUE_CONTROL))
                info->hw_queue =
                        sdata->vif.hw_queue[skb_get_queue_mapping(skb)];

        if (invoke_tx_handlers_early(&tx))
                return false;

        if (ieee80211_queue_skb(local, sdata, tx.sta, tx.skb))
                return true;

        if (!invoke_tx_handlers_late(&tx))
                result = __ieee80211_tx(local, &tx.skbs, led_len,
                                        tx.sta, txpending);

        return result;
}

/* device xmit handlers */

static int ieee80211_skb_resize(struct ieee80211_sub_if_data *sdata,
                                struct sk_buff *skb,
                                int head_need, bool may_encrypt)
{
        struct ieee80211_local *local = sdata->local;
        int tail_need = 0;

        if (may_encrypt && sdata->crypto_tx_tailroom_needed_cnt) {
                tail_need = IEEE80211_ENCRYPT_TAILROOM;
                tail_need -= skb_tailroom(skb);
                tail_need = max_t(int, tail_need, 0);
        }

        if (skb_cloned(skb) &&
            (!ieee80211_hw_check(&local->hw, SUPPORTS_CLONED_SKBS) ||
             !skb_clone_writable(skb, ETH_HLEN) ||
             (may_encrypt && sdata->crypto_tx_tailroom_needed_cnt)))
                I802_DEBUG_INC(local->tx_expand_skb_head_cloned);
        else if (head_need || tail_need)
                I802_DEBUG_INC(local->tx_expand_skb_head);
        else
                return 0;

        if (pskb_expand_head(skb, head_need, tail_need, GFP_ATOMIC)) {
                wiphy_debug(local->hw.wiphy,
                            "failed to reallocate TX buffer\n");
                return -ENOMEM;
        }

        return 0;
}

void ieee80211_xmit(struct ieee80211_sub_if_data *sdata,
                    struct sta_info *sta, struct sk_buff *skb)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        int headroom;
        bool may_encrypt;

        may_encrypt = !(info->flags & IEEE80211_TX_INTFL_DONT_ENCRYPT);

        headroom = local->tx_headroom;
        if (may_encrypt)
                headroom += sdata->encrypt_headroom;
        headroom -= skb_headroom(skb);
        headroom = max_t(int, 0, headroom);

        if (ieee80211_skb_resize(sdata, skb, headroom, may_encrypt)) {
                ieee80211_free_txskb(&local->hw, skb);
                return;
        }

        hdr = (struct ieee80211_hdr *) skb->data;
        info->control.vif = &sdata->vif;

        if (ieee80211_vif_is_mesh(&sdata->vif)) {
                if (ieee80211_is_data(hdr->frame_control) &&
                    is_unicast_ether_addr(hdr->addr1)) {
                        if (mesh_nexthop_resolve(sdata, skb))
                                return; /* skb queued: don't free */
                } else {
                        ieee80211_mps_set_frame_flags(sdata, NULL, hdr);
                }
        }

        ieee80211_set_qos_hdr(sdata, skb);
        ieee80211_tx(sdata, sta, skb, false);
}

static bool ieee80211_parse_tx_radiotap(struct ieee80211_local *local,
                                        struct sk_buff *skb)
{
        struct ieee80211_radiotap_iterator iterator;
        struct ieee80211_radiotap_header *rthdr =
                (struct ieee80211_radiotap_header *) skb->data;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_supported_band *sband =
                local->hw.wiphy->bands[info->band];
        int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len,
                                                   NULL);
        u16 txflags;
        u16 rate = 0;
        bool rate_found = false;
        u8 rate_retries = 0;
        u16 rate_flags = 0;
        u8 mcs_known, mcs_flags, mcs_bw;
        u16 vht_known;
        u8 vht_mcs = 0, vht_nss = 0;
        int i;

        info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |
                       IEEE80211_TX_CTL_DONTFRAG;

        /*
         * for every radiotap entry that is present
         * (ieee80211_radiotap_iterator_next returns -ENOENT when no more
         * entries present, or -EINVAL on error)
         */

        while (!ret) {
                ret = ieee80211_radiotap_iterator_next(&iterator);

                if (ret)
                        continue;

                /* see if this argument is something we can use */
                switch (iterator.this_arg_index) {
                /*
                 * You must take care when dereferencing iterator.this_arg
                 * for multibyte types... the pointer is not aligned.  Use
                 * get_unaligned((type *)iterator.this_arg) to dereference
                 * iterator.this_arg for type "type" safely on all arches.
                */
                case IEEE80211_RADIOTAP_FLAGS:
                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FCS) {
                                /*
                                 * this indicates that the skb we have been
                                 * handed has the 32-bit FCS CRC at the end...
                                 * we should react to that by snipping it off
                                 * because it will be recomputed and added
                                 * on transmission
                                 */
                                if (skb->len < (iterator._max_length + FCS_LEN))
                                        return false;

                                skb_trim(skb, skb->len - FCS_LEN);
                        }
                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_WEP)
                                info->flags &= ~IEEE80211_TX_INTFL_DONT_ENCRYPT;
                        if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FRAG)
                                info->flags &= ~IEEE80211_TX_CTL_DONTFRAG;
                        break;

                case IEEE80211_RADIOTAP_TX_FLAGS:
                        txflags = get_unaligned_le16(iterator.this_arg);
                        if (txflags & IEEE80211_RADIOTAP_F_TX_NOACK)
                                info->flags |= IEEE80211_TX_CTL_NO_ACK;
                        break;

                case IEEE80211_RADIOTAP_RATE:
                        rate = *iterator.this_arg;

                        rate_flags = 0;
                        rate_found = true;
                        break;

                case IEEE80211_RADIOTAP_DATA_RETRIES:
                        rate_retries = *iterator.this_arg;
                        break;

                case IEEE80211_RADIOTAP_MCS:
                        mcs_known = iterator.this_arg[0];
                        mcs_flags = iterator.this_arg[1];
                        if (!(mcs_known & IEEE80211_RADIOTAP_MCS_HAVE_MCS))
                                break;

                        rate_found = true;
                        rate = iterator.this_arg[2];
                        rate_flags = IEEE80211_TX_RC_MCS;

                        if (mcs_known & IEEE80211_RADIOTAP_MCS_HAVE_GI &&
                            mcs_flags & IEEE80211_RADIOTAP_MCS_SGI)
                                rate_flags |= IEEE80211_TX_RC_SHORT_GI;

                        mcs_bw = mcs_flags & IEEE80211_RADIOTAP_MCS_BW_MASK;
                        if (mcs_known & IEEE80211_RADIOTAP_MCS_HAVE_BW &&
                            mcs_bw == IEEE80211_RADIOTAP_MCS_BW_40)
                                rate_flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
                        break;

                case IEEE80211_RADIOTAP_VHT:
                        vht_known = get_unaligned_le16(iterator.this_arg);
                        rate_found = true;

                        rate_flags = IEEE80211_TX_RC_VHT_MCS;
                        if ((vht_known & IEEE80211_RADIOTAP_VHT_KNOWN_GI) &&
                            (iterator.this_arg[2] &
                             IEEE80211_RADIOTAP_VHT_FLAG_SGI))
                                rate_flags |= IEEE80211_TX_RC_SHORT_GI;
                        if (vht_known &
                            IEEE80211_RADIOTAP_VHT_KNOWN_BANDWIDTH) {
                                if (iterator.this_arg[3] == 1)
                                        rate_flags |=
                                                IEEE80211_TX_RC_40_MHZ_WIDTH;
                                else if (iterator.this_arg[3] == 4)
                                        rate_flags |=
                                                IEEE80211_TX_RC_80_MHZ_WIDTH;
                                else if (iterator.this_arg[3] == 11)
                                        rate_flags |=
                                                IEEE80211_TX_RC_160_MHZ_WIDTH;
                        }

                        vht_mcs = iterator.this_arg[4] >> 4;
                        vht_nss = iterator.this_arg[4] & 0xF;
                        break;

                /*
                 * Please update the file
                 * Documentation/networking/mac80211-injection.txt
                 * when parsing new fields here.
                 */

                default:
                        break;
                }
        }

        if (ret != -ENOENT) /* ie, if we didn't simply run out of fields */
                return false;

        if (rate_found) {
                info->control.flags |= IEEE80211_TX_CTRL_RATE_INJECT;

                for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
                        info->control.rates[i].idx = -1;
                        info->control.rates[i].flags = 0;
                        info->control.rates[i].count = 0;
                }

                if (rate_flags & IEEE80211_TX_RC_MCS) {
                        info->control.rates[0].idx = rate;
                } else if (rate_flags & IEEE80211_TX_RC_VHT_MCS) {
                        ieee80211_rate_set_vht(info->control.rates, vht_mcs,
                                               vht_nss);
                } else {
                        for (i = 0; i < sband->n_bitrates; i++) {
                                if (rate * 5 != sband->bitrates[i].bitrate)
                                        continue;

                                info->control.rates[0].idx = i;
                                break;
                        }
                }

                if (info->control.rates[0].idx < 0)
                        info->control.flags &= ~IEEE80211_TX_CTRL_RATE_INJECT;

                info->control.rates[0].flags = rate_flags;
                info->control.rates[0].count = min_t(u8, rate_retries + 1,
                                                     local->hw.max_rate_tries);
        }

        /*
         * remove the radiotap header
         * iterator->_max_length was sanity-checked against
         * skb->len by iterator init
         */
        skb_pull(skb, iterator._max_length);

        return true;
}

netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,
                                         struct net_device *dev)
{
        struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct ieee80211_radiotap_header *prthdr =
                (struct ieee80211_radiotap_header *)skb->data;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_hdr *hdr;
        struct ieee80211_sub_if_data *tmp_sdata, *sdata;
        struct cfg80211_chan_def *chandef;
        u16 len_rthdr;
        int hdrlen;

        /* check for not even having the fixed radiotap header part */
        if (unlikely(skb->len < sizeof(struct ieee80211_radiotap_header)))
                goto fail; /* too short to be possibly valid */

        /* is it a header version we can trust to find length from? */
        if (unlikely(prthdr->it_version))
                goto fail; /* only version 0 is supported */

        /* then there must be a radiotap header with a length we can use */
        len_rthdr = ieee80211_get_radiotap_len(skb->data);

        /* does the skb contain enough to deliver on the alleged length? */
        if (unlikely(skb->len < len_rthdr))
                goto fail; /* skb too short for claimed rt header extent */

        /*
         * fix up the pointers accounting for the radiotap
         * header still being in there.  We are being given
         * a precooked IEEE80211 header so no need for
         * normal processing
         */
        skb_set_mac_header(skb, len_rthdr);
        /*
         * these are just fixed to the end of the rt area since we
         * don't have any better information and at this point, nobody cares
         */
        skb_set_network_header(skb, len_rthdr);
        skb_set_transport_header(skb, len_rthdr);

        if (skb->len < len_rthdr + 2)
                goto fail;

        hdr = (struct ieee80211_hdr *)(skb->data + len_rthdr);
        hdrlen = ieee80211_hdrlen(hdr->frame_control);

        if (skb->len < len_rthdr + hdrlen)
                goto fail;

        /*
         * Initialize skb->protocol if the injected frame is a data frame
         * carrying a rfc1042 header
         */
        if (ieee80211_is_data(hdr->frame_control) &&
            skb->len >= len_rthdr + hdrlen + sizeof(rfc1042_header) + 2) {
                u8 *payload = (u8 *)hdr + hdrlen;

                if (ether_addr_equal(payload, rfc1042_header))
                        skb->protocol = cpu_to_be16((payload[6] << 8) |
                                                    payload[7]);
        }

        memset(info, 0, sizeof(*info));

        info->flags = IEEE80211_TX_CTL_REQ_TX_STATUS |
                      IEEE80211_TX_CTL_INJECTED;

        rcu_read_lock();

        /*
         * We process outgoing injected frames that have a local address
         * we handle as though they are non-injected frames.
         * This code here isn't entirely correct, the local MAC address
         * isn't always enough to find the interface to use; for proper
         * VLAN/WDS support we will need a different mechanism (which
         * likely isn't going to be monitor interfaces).
         */
        sdata = IEEE80211_DEV_TO_SUB_IF(dev);

        list_for_each_entry_rcu(tmp_sdata, &local->interfaces, list) {
                if (!ieee80211_sdata_running(tmp_sdata))
                        continue;
                if (tmp_sdata->vif.type == NL80211_IFTYPE_MONITOR ||
                    tmp_sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
                    tmp_sdata->vif.type == NL80211_IFTYPE_WDS)
                        continue;
                if (ether_addr_equal(tmp_sdata->vif.addr, hdr->addr2)) {
                        sdata = tmp_sdata;
                        break;
                }
        }

        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
        if (!chanctx_conf) {
                tmp_sdata = rcu_dereference(local->monitor_sdata);
                if (tmp_sdata)
                        chanctx_conf =
                                rcu_dereference(tmp_sdata->vif.chanctx_conf);
        }

        if (chanctx_conf)
                chandef = &chanctx_conf->def;
        else if (!local->use_chanctx)
                chandef = &local->_oper_chandef;
        else
                goto fail_rcu;

        /*
         * Frame injection is not allowed if beaconing is not allowed
         * or if we need radar detection. Beaconing is usually not allowed when
         * the mode or operation (Adhoc, AP, Mesh) does not support DFS.
         * Passive scan is also used in world regulatory domains where
         * your country is not known and as such it should be treated as
         * NO TX unless the channel is explicitly allowed in which case
         * your current regulatory domain would not have the passive scan
         * flag.
         *
         * Since AP mode uses monitor interfaces to inject/TX management
         * frames we can make AP mode the exception to this rule once it
         * supports radar detection as its implementation can deal with
         * radar detection by itself. We can do that later by adding a
         * monitor flag interfaces used for AP support.
         */
        if (!cfg80211_reg_can_beacon(local->hw.wiphy, chandef,
                                     sdata->vif.type))
                goto fail_rcu;

        info->band = chandef->chan->band;

        /* process and remove the injection radiotap header */
        if (!ieee80211_parse_tx_radiotap(local, skb))
                goto fail_rcu;

        ieee80211_xmit(sdata, NULL, skb);
        rcu_read_unlock();

        return NETDEV_TX_OK;

fail_rcu:
        rcu_read_unlock();
fail:
        dev_kfree_skb(skb);
        return NETDEV_TX_OK; /* meaning, we dealt with the skb */
}

static inline bool ieee80211_is_tdls_setup(struct sk_buff *skb)
{
        u16 ethertype = (skb->data[12] << 8) | skb->data[13];

        return ethertype == ETH_P_TDLS &&
               skb->len > 14 &&
               skb->data[14] == WLAN_TDLS_SNAP_RFTYPE;
}

static int ieee80211_lookup_ra_sta(struct ieee80211_sub_if_data *sdata,
                                   struct sk_buff *skb,
                                   struct sta_info **sta_out)
{
        struct sta_info *sta;

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_AP_VLAN:
                sta = rcu_dereference(sdata->u.vlan.sta);
                if (sta) {
                        *sta_out = sta;
                        return 0;
                } else if (sdata->wdev.use_4addr) {
                        return -ENOLINK;
                }
                /* fall through */
        case NL80211_IFTYPE_AP:
        case NL80211_IFTYPE_OCB:
        case NL80211_IFTYPE_ADHOC:
                if (is_multicast_ether_addr(skb->data)) {
                        *sta_out = ERR_PTR(-ENOENT);
                        return 0;
                }
                sta = sta_info_get_bss(sdata, skb->data);
                break;
        case NL80211_IFTYPE_WDS:
                sta = sta_info_get(sdata, sdata->u.wds.remote_addr);
                break;
#ifdef CONFIG_MAC80211_MESH
        case NL80211_IFTYPE_MESH_POINT:
                /* determined much later */
                *sta_out = NULL;
                return 0;
#endif
        case NL80211_IFTYPE_STATION:
                if (sdata->wdev.wiphy->flags & WIPHY_FLAG_SUPPORTS_TDLS) {
                        sta = sta_info_get(sdata, skb->data);
                        if (sta && test_sta_flag(sta, WLAN_STA_TDLS_PEER)) {
                                if (test_sta_flag(sta,
                                                  WLAN_STA_TDLS_PEER_AUTH)) {
                                        *sta_out = sta;
                                        return 0;
                                }

                                /*
                                 * TDLS link during setup - throw out frames to
                                 * peer. Allow TDLS-setup frames to unauthorized
                                 * peers for the special case of a link teardown
                                 * after a TDLS sta is removed due to being
                                 * unreachable.
                                 */
                                if (!ieee80211_is_tdls_setup(skb))
                                        return -EINVAL;
                        }

                }

                sta = sta_info_get(sdata, sdata->u.mgd.bssid);
                if (!sta)
                        return -ENOLINK;
                break;
        default:
                return -EINVAL;
        }

        *sta_out = sta ?: ERR_PTR(-ENOENT);
        return 0;
}

/**
 * ieee80211_build_hdr - build 802.11 header in the given frame
 * @sdata: virtual interface to build the header for
 * @skb: the skb to build the header in
 * @info_flags: skb flags to set
 *
 * This function takes the skb with 802.3 header and reformats the header to
 * the appropriate IEEE 802.11 header based on which interface the packet is
 * being transmitted on.
 *
 * Note that this function also takes care of the TX status request and
 * potential unsharing of the SKB - this needs to be interleaved with the
 * header building.
 *
 * The function requires the read-side RCU lock held
 *
 * Returns: the (possibly reallocated) skb or an ERR_PTR() code
 */
static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
                                           struct sk_buff *skb, u32 info_flags,
                                           struct sta_info *sta)
{
        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;
        bool wme_sta = false, authorized = false;
        bool tdls_peer;
        bool multicast;
        u16 info_id = 0;
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct ieee80211_sub_if_data *ap_sdata;
        enum nl80211_band band;
        int ret;

        if (IS_ERR(sta))
                sta = NULL;

        /* 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);

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_AP_VLAN:
                if (sdata->wdev.use_4addr) {
                        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 = sta->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) {
                        ret = -ENOTCONN;
                        goto free;
                }
                band = chanctx_conf->def.chan->band;
                if (sdata->wdev.use_4addr)
                        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) {
                        ret = -ENOTCONN;
                        goto free;
                }
                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 CONFIG_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)
                                        mppath->exp_time = jiffies;
                        }

                        if (mppath && mpath)
                                mesh_path_del(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) {
                        ret = -ENOTCONN;
                        goto free;
                }
                band = chanctx_conf->def.chan->band;
                break;
#endif
        case NL80211_IFTYPE_STATION:
                /* we already did checks when looking up the RA STA */
                tdls_peer = test_sta_flag(sta, WLAN_STA_TDLS_PEER);

                if (tdls_peer) {
                        /* 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) {
                        ret = -ENOTCONN;
                        goto free;
                }
                band = chanctx_conf->def.chan->band;
                break;
        case NL80211_IFTYPE_OCB:
                /* DA SA BSSID */
                memcpy(hdr.addr1, skb->data, ETH_ALEN);
                memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
                eth_broadcast_addr(hdr.addr3);
                hdrlen = 24;
                chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
                if (!chanctx_conf) {
                        ret = -ENOTCONN;
                        goto free;
                }
                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) {
                        ret = -ENOTCONN;
                        goto free;
                }
                band = chanctx_conf->def.chan->band;
                break;
        default:
                ret = -EINVAL;
                goto free;
        }

        multicast = is_multicast_ether_addr(hdr.addr1);

        /* sta is always NULL for mesh */
        if (sta) {
                authorized = test_sta_flag(sta, WLAN_STA_AUTHORIZED);
                wme_sta = sta->sta.wme;
        } else if (ieee80211_vif_is_mesh(&sdata->vif)) {
                /* For mesh, the use of the QoS header is mandatory */
                wme_sta = true;
        }

        /* receiver does QoS (which also means we do) use it */
        if (wme_sta) {
                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) &&
                     (sdata->vif.type != NL80211_IFTYPE_OCB) &&
                     !multicast && !authorized &&
                     (cpu_to_be16(ethertype) != sdata->control_port_protocol ||
                      !ether_addr_equal(sdata->vif.addr, skb->data + ETH_ALEN)))) {
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
                net_info_ratelimited("%s: dropped frame to %pM (unauthorized port)\n",
                                    sdata->name, hdr.addr1);
#endif

                I802_DEBUG_INC(local->tx_handlers_drop_unauth_port);

                ret = -EPERM;
                goto free;
        }

        if (unlikely(!multicast && skb->sk &&
                     skb_shinfo(skb)->tx_flags & SKBTX_WIFI_STATUS)) {
                struct sk_buff *ack_skb = skb_clone_sk(skb);

                if (ack_skb) {
                        unsigned long flags;
                        int id;

                        spin_lock_irqsave(&local->ack_status_lock, flags);
                        id = idr_alloc(&local->ack_status_frames, ack_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 {
                                kfree_skb(ack_skb);
                        }
                }
        }

        /*
         * 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) {
                        ret = -ENOMEM;
                        goto free;
                }
        }

        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;
        }

        skb_pull(skb, 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;
                        return ERR_PTR(-ENOMEM);
                }
        }

        if (encaps_data)
                memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len);

#ifdef CONFIG_MAC80211_MESH
        if (meshhdrlen > 0)
                memcpy(skb_push(skb, meshhdrlen), &mesh_hdr, meshhdrlen);
#endif

        if (ieee80211_is_data_qos(fc)) {
                __le16 *qos_control;

                qos_control = 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);

        skb_reset_mac_header(skb);

        info = IEEE80211_SKB_CB(skb);
        memset(info, 0, sizeof(*info));

        info->flags = info_flags;
        info->ack_frame_id = info_id;
        info->band = band;

        return skb;
 free:
        kfree_skb(skb);
        return ERR_PTR(ret);
}

/*
 * fast-xmit overview
 *
 * The core idea of this fast-xmit is to remove per-packet checks by checking
 * them out of band. ieee80211_check_fast_xmit() implements the out-of-band
 * checks that are needed to get the sta->fast_tx pointer assigned, after which
 * much less work can be done per packet. For example, fragmentation must be
 * disabled or the fast_tx pointer will not be set. All the conditions are seen
 * in the code here.
 *
 * Once assigned, the fast_tx data structure also caches the per-packet 802.11
 * header and other data to aid packet processing in ieee80211_xmit_fast().
 *
 * The most difficult part of this is that when any of these assumptions
 * change, an external trigger (i.e. a call to ieee80211_clear_fast_xmit(),
 * ieee80211_check_fast_xmit() or friends) is required to reset the data,
 * since the per-packet code no longer checks the conditions. This is reflected
 * by the calls to these functions throughout the rest of the code, and must be
 * maintained if any of the TX path checks change.
 */

void ieee80211_check_fast_xmit(struct sta_info *sta)
{
        struct ieee80211_fast_tx build = {}, *fast_tx = NULL, *old;
        struct ieee80211_local *local = sta->local;
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        struct ieee80211_hdr *hdr = (void *)build.hdr;
        struct ieee80211_chanctx_conf *chanctx_conf;
        __le16 fc;

        if (!ieee80211_hw_check(&local->hw, SUPPORT_FAST_XMIT))
                return;

        /* Locking here protects both the pointer itself, and against concurrent
         * invocations winning data access races to, e.g., the key pointer that
         * is used.
         * Without it, the invocation of this function right after the key
         * pointer changes wouldn't be sufficient, as another CPU could access
         * the pointer, then stall, and then do the cache update after the CPU
         * that invalidated the key.
         * With the locking, such scenarios cannot happen as the check for the
         * key and the fast-tx assignment are done atomically, so the CPU that
         * modifies the key will either wait or other one will see the key
         * cleared/changed already.
         */
        spin_lock_bh(&sta->lock);
        if (ieee80211_hw_check(&local->hw, SUPPORTS_PS) &&
            !ieee80211_hw_check(&local->hw, SUPPORTS_DYNAMIC_PS) &&
            sdata->vif.type == NL80211_IFTYPE_STATION)
                goto out;

        if (!test_sta_flag(sta, WLAN_STA_AUTHORIZED))
                goto out;

        if (test_sta_flag(sta, WLAN_STA_PS_STA) ||
            test_sta_flag(sta, WLAN_STA_PS_DRIVER) ||
            test_sta_flag(sta, WLAN_STA_PS_DELIVER) ||
            test_sta_flag(sta, WLAN_STA_CLEAR_PS_FILT))
                goto out;

        if (sdata->noack_map)
                goto out;

        /* fast-xmit doesn't handle fragmentation at all */
        if (local->hw.wiphy->frag_threshold != (u32)-1 &&
            !ieee80211_hw_check(&local->hw, SUPPORTS_TX_FRAG))
                goto out;

        rcu_read_lock();
        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
        if (!chanctx_conf) {
                rcu_read_unlock();
                goto out;
        }
        build.band = chanctx_conf->def.chan->band;
        rcu_read_unlock();

        fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA);

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_ADHOC:
                /* DA SA BSSID */
                build.da_offs = offsetof(struct ieee80211_hdr, addr1);
                build.sa_offs = offsetof(struct ieee80211_hdr, addr2);
                memcpy(hdr->addr3, sdata->u.ibss.bssid, ETH_ALEN);
                build.hdr_len = 24;
                break;
        case NL80211_IFTYPE_STATION:
                if (test_sta_flag(sta, WLAN_STA_TDLS_PEER)) {
                        /* DA SA BSSID */
                        build.da_offs = offsetof(struct ieee80211_hdr, addr1);
                        build.sa_offs = offsetof(struct ieee80211_hdr, addr2);
                        memcpy(hdr->addr3, sdata->u.mgd.bssid, ETH_ALEN);
                        build.hdr_len = 24;
                        break;
                }

                if (sdata->u.mgd.use_4addr) {
                        /* non-regular ethertype cannot use the fastpath */
                        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);
                        build.da_offs = offsetof(struct ieee80211_hdr, addr3);
                        build.sa_offs = offsetof(struct ieee80211_hdr, addr4);
                        build.hdr_len = 30;
                        break;
                }
                fc |= cpu_to_le16(IEEE80211_FCTL_TODS);
                /* BSSID SA DA */
                memcpy(hdr->addr1, sdata->u.mgd.bssid, ETH_ALEN);
                build.da_offs = offsetof(struct ieee80211_hdr, addr3);
                build.sa_offs = offsetof(struct ieee80211_hdr, addr2);
                build.hdr_len = 24;
                break;
        case NL80211_IFTYPE_AP_VLAN:
                if (sdata->wdev.use_4addr) {
                        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);
                        build.da_offs = offsetof(struct ieee80211_hdr, addr3);
                        build.sa_offs = offsetof(struct ieee80211_hdr, addr4);
                        build.hdr_len = 30;
                        break;
                }
                /* fall through */
        case NL80211_IFTYPE_AP:
                fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
                /* DA BSSID SA */
                build.da_offs = offsetof(struct ieee80211_hdr, addr1);
                memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
                build.sa_offs = offsetof(struct ieee80211_hdr, addr3);
                build.hdr_len = 24;
                break;
        default:
                /* not handled on fast-xmit */
                goto out;
        }

        if (sta->sta.wme) {
                build.hdr_len += 2;
                fc |= cpu_to_le16(IEEE80211_STYPE_QOS_DATA);
        }

        /* We store the key here so there's no point in using rcu_dereference()
         * but that's fine because the code that changes the pointers will call
         * this function after doing so. For a single CPU that would be enough,
         * for multiple see the comment above.
         */
        build.key = rcu_access_pointer(sta->ptk[sta->ptk_idx]);
        if (!build.key)
                build.key = rcu_access_pointer(sdata->default_unicast_key);
        if (build.key) {
                bool gen_iv, iv_spc, mmic;

                gen_iv = build.key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV;
                iv_spc = build.key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE;
                mmic = build.key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC;

                /* don't handle software crypto */
                if (!(build.key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
                        goto out;

                switch (build.key->conf.cipher) {
                case WLAN_CIPHER_SUITE_CCMP:
                case WLAN_CIPHER_SUITE_CCMP_256:
                        /* add fixed key ID */
                        if (gen_iv) {
                                (build.hdr + build.hdr_len)[3] =
                                        0x20 | (build.key->conf.keyidx << 6);
                                build.pn_offs = build.hdr_len;
                        }
                        if (gen_iv || iv_spc)
                                build.hdr_len += IEEE80211_CCMP_HDR_LEN;
                        break;
                case WLAN_CIPHER_SUITE_GCMP:
                case WLAN_CIPHER_SUITE_GCMP_256:
                        /* add fixed key ID */
                        if (gen_iv) {
                                (build.hdr + build.hdr_len)[3] =
                                        0x20 | (build.key->conf.keyidx << 6);
                                build.pn_offs = build.hdr_len;
                        }
                        if (gen_iv || iv_spc)
                                build.hdr_len += IEEE80211_GCMP_HDR_LEN;
                        break;
                case WLAN_CIPHER_SUITE_TKIP:
                        /* cannot handle MMIC or IV generation in xmit-fast */
                        if (mmic || gen_iv)
                                goto out;
                        if (iv_spc)
                                build.hdr_len += IEEE80211_TKIP_IV_LEN;
                        break;
                case WLAN_CIPHER_SUITE_WEP40:
                case WLAN_CIPHER_SUITE_WEP104:
                        /* cannot handle IV generation in fast-xmit */
                        if (gen_iv)
                                goto out;
                        if (iv_spc)
                                build.hdr_len += IEEE80211_WEP_IV_LEN;
                        break;
                case WLAN_CIPHER_SUITE_AES_CMAC:
                case WLAN_CIPHER_SUITE_BIP_CMAC_256:
                case WLAN_CIPHER_SUITE_BIP_GMAC_128:
                case WLAN_CIPHER_SUITE_BIP_GMAC_256:
                        WARN(1,
                             "management cipher suite 0x%x enabled for data\n",
                             build.key->conf.cipher);
                        goto out;
                default:
                        /* we don't know how to generate IVs for this at all */
                        if (WARN_ON(gen_iv))
                                goto out;
                        /* pure hardware keys are OK, of course */
                        if (!(build.key->flags & KEY_FLAG_CIPHER_SCHEME))
                                break;
                        /* cipher scheme might require space allocation */
                        if (iv_spc &&
                            build.key->conf.iv_len > IEEE80211_FAST_XMIT_MAX_IV)
                                goto out;
                        if (iv_spc)
                                build.hdr_len += build.key->conf.iv_len;
                }

                fc |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
        }

        hdr->frame_control = fc;

        memcpy(build.hdr + build.hdr_len,
               rfc1042_header,  sizeof(rfc1042_header));
        build.hdr_len += sizeof(rfc1042_header);

        fast_tx = kmemdup(&build, sizeof(build), GFP_ATOMIC);
        /* if the kmemdup fails, continue w/o fast_tx */
        if (!fast_tx)
                goto out;

 out:
        /* we might have raced against another call to this function */
        old = rcu_dereference_protected(sta->fast_tx,
                                        lockdep_is_held(&sta->lock));
        rcu_assign_pointer(sta->fast_tx, fast_tx);
        if (old)
                kfree_rcu(old, rcu_head);
        spin_unlock_bh(&sta->lock);
}

void ieee80211_check_fast_xmit_all(struct ieee80211_local *local)
{
        struct sta_info *sta;

        rcu_read_lock();
        list_for_each_entry_rcu(sta, &local->sta_list, list)
                ieee80211_check_fast_xmit(sta);
        rcu_read_unlock();
}

void ieee80211_check_fast_xmit_iface(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;