status.c

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/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2008-2010  Johannes Berg <johannes@sipsolutions.net>
 *
 * 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.
 */

#include <linux/export.h>
#include <linux/etherdevice.h>
#include <net/mac80211.h>
#include <asm/unaligned.h>
#include "ieee80211_i.h"
#include "rate.h"
#include "mesh.h"
#include "led.h"
#include "wme.h"


void ieee80211_tx_status_irqsafe(struct ieee80211_hw *hw,
                                 struct sk_buff *skb)
{
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        int tmp;

        skb->pkt_type = IEEE80211_TX_STATUS_MSG;
        skb_queue_tail(info->flags & IEEE80211_TX_CTL_REQ_TX_STATUS ?
                       &local->skb_queue : &local->skb_queue_unreliable, skb);
        tmp = skb_queue_len(&local->skb_queue) +
                skb_queue_len(&local->skb_queue_unreliable);
        while (tmp > IEEE80211_IRQSAFE_QUEUE_LIMIT &&
               (skb = skb_dequeue(&local->skb_queue_unreliable))) {
                dev_kfree_skb_irq(skb);
                tmp--;
                I802_DEBUG_INC(local->tx_status_drop);
        }
        tasklet_schedule(&local->tasklet);
}
EXPORT_SYMBOL(ieee80211_tx_status_irqsafe);

static void ieee80211_handle_filtered_frame(struct ieee80211_local *local,
                                            struct sta_info *sta,
                                            struct sk_buff *skb)
{
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_hdr *hdr = (void *)skb->data;
        int ac;

        /*
         * This skb 'survived' a round-trip through the driver, and
         * hopefully the driver didn't mangle it too badly. However,
         * we can definitely not rely on the control information
         * being correct. Clear it so we don't get junk there, and
         * indicate that it needs new processing, but must not be
         * modified/encrypted again.
         */
        memset(&info->control, 0, sizeof(info->control));

        info->control.jiffies = jiffies;
        info->control.vif = &sta->sdata->vif;
        info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING |
                       IEEE80211_TX_INTFL_RETRANSMISSION;
        info->flags &= ~IEEE80211_TX_TEMPORARY_FLAGS;

        sta->tx_filtered_count++;

        /*
         * Clear more-data bit on filtered frames, it might be set
         * but later frames might time out so it might have to be
         * clear again ... It's all rather unlikely (this frame
         * should time out first, right?) but let's not confuse
         * peers unnecessarily.
         */
        if (hdr->frame_control & cpu_to_le16(IEEE80211_FCTL_MOREDATA))
                hdr->frame_control &= ~cpu_to_le16(IEEE80211_FCTL_MOREDATA);

        if (ieee80211_is_data_qos(hdr->frame_control)) {
                u8 *p = ieee80211_get_qos_ctl(hdr);
                int tid = *p & IEEE80211_QOS_CTL_TID_MASK;

                /*
                 * Clear EOSP if set, this could happen e.g.
                 * if an absence period (us being a P2P GO)
                 * shortens the SP.
                 */
                if (*p & IEEE80211_QOS_CTL_EOSP)
                        *p &= ~IEEE80211_QOS_CTL_EOSP;
                ac = ieee802_1d_to_ac[tid & 7];
        } else {
                ac = IEEE80211_AC_BE;
        }

        /*
         * Clear the TX filter mask for this STA when sending the next
         * packet. If the STA went to power save mode, this will happen
         * when it wakes up for the next time.
         */
        set_sta_flag(sta, WLAN_STA_CLEAR_PS_FILT);

        /*
         * This code races in the following way:
         *
         *  (1) STA sends frame indicating it will go to sleep and does so
         *  (2) hardware/firmware adds STA to filter list, passes frame up
         *  (3) hardware/firmware processes TX fifo and suppresses a frame
         *  (4) we get TX status before having processed the frame and
         *      knowing that the STA has gone to sleep.
         *
         * This is actually quite unlikely even when both those events are
         * processed from interrupts coming in quickly after one another or
         * even at the same time because we queue both TX status events and
         * RX frames to be processed by a tasklet and process them in the
         * same order that they were received or TX status last. Hence, there
         * is no race as long as the frame RX is processed before the next TX
         * status, which drivers can ensure, see below.
         *
         * Note that this can only happen if the hardware or firmware can
         * actually add STAs to the filter list, if this is done by the
         * driver in response to set_tim() (which will only reduce the race
         * this whole filtering tries to solve, not completely solve it)
         * this situation cannot happen.
         *
         * To completely solve this race drivers need to make sure that they
         *  (a) don't mix the irq-safe/not irq-safe TX status/RX processing
         *      functions and
         *  (b) always process RX events before TX status events if ordering
         *      can be unknown, for example with different interrupt status
         *      bits.
         *  (c) if PS mode transitions are manual (i.e. the flag
         *      %IEEE80211_HW_AP_LINK_PS is set), always process PS state
         *      changes before calling TX status events if ordering can be
         *      unknown.
         */
        if (test_sta_flag(sta, WLAN_STA_PS_STA) &&
            skb_queue_len(&sta->tx_filtered[ac]) < STA_MAX_TX_BUFFER) {
                skb_queue_tail(&sta->tx_filtered[ac], skb);
                sta_info_recalc_tim(sta);

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

        if (!test_sta_flag(sta, WLAN_STA_PS_STA) &&
            !(info->flags & IEEE80211_TX_INTFL_RETRIED)) {
                /* Software retry the packet once */
                info->flags |= IEEE80211_TX_INTFL_RETRIED;
                ieee80211_add_pending_skb(local, skb);
                return;
        }

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
        if (net_ratelimit())
                wiphy_debug(local->hw.wiphy,
                            "dropped TX filtered frame, queue_len=%d PS=%d @%lu\n",
                            skb_queue_len(&sta->tx_filtered[ac]),
                            !!test_sta_flag(sta, WLAN_STA_PS_STA), jiffies);
#endif
        dev_kfree_skb(skb);
}

static void ieee80211_check_pending_bar(struct sta_info *sta, u8 *addr, u8 tid)
{
        struct tid_ampdu_tx *tid_tx;

        tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[tid]);
        if (!tid_tx || !tid_tx->bar_pending)
                return;

        tid_tx->bar_pending = false;
        ieee80211_send_bar(&sta->sdata->vif, addr, tid, tid_tx->failed_bar_ssn);
}

static void ieee80211_frame_acked(struct sta_info *sta, struct sk_buff *skb)
{
        struct ieee80211_mgmt *mgmt = (void *) skb->data;
        struct ieee80211_local *local = sta->local;
        struct ieee80211_sub_if_data *sdata = sta->sdata;

        if (ieee80211_is_data_qos(mgmt->frame_control)) {
                struct ieee80211_hdr *hdr = (void *) skb->data;
                u8 *qc = ieee80211_get_qos_ctl(hdr);
                u16 tid = qc[0] & 0xf;

                ieee80211_check_pending_bar(sta, hdr->addr1, tid);
        }

        if (ieee80211_is_action(mgmt->frame_control) &&
            sdata->vif.type == NL80211_IFTYPE_STATION &&
            mgmt->u.action.category == WLAN_CATEGORY_HT &&
            mgmt->u.action.u.ht_smps.action == WLAN_HT_ACTION_SMPS) {
                /*
                 * This update looks racy, but isn't -- if we come
                 * here we've definitely got a station that we're
                 * talking to, and on a managed interface that can
                 * only be the AP. And the only other place updating
                 * this variable is before we're associated.
                 */
                switch (mgmt->u.action.u.ht_smps.smps_control) {
                case WLAN_HT_SMPS_CONTROL_DYNAMIC:
                        sta->sdata->u.mgd.ap_smps = IEEE80211_SMPS_DYNAMIC;
                        break;
                case WLAN_HT_SMPS_CONTROL_STATIC:
                        sta->sdata->u.mgd.ap_smps = IEEE80211_SMPS_STATIC;
                        break;
                case WLAN_HT_SMPS_CONTROL_DISABLED:
                default: /* shouldn't happen since we don't send that */
                        sta->sdata->u.mgd.ap_smps = IEEE80211_SMPS_OFF;
                        break;
                }

                ieee80211_queue_work(&local->hw, &local->recalc_smps);
        }
}

static void ieee80211_set_bar_pending(struct sta_info *sta, u8 tid, u16 ssn)
{
        struct tid_ampdu_tx *tid_tx;

        tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[tid]);
        if (!tid_tx)
                return;

        tid_tx->failed_bar_ssn = ssn;
        tid_tx->bar_pending = true;
}

static int ieee80211_tx_radiotap_len(struct ieee80211_tx_info *info)
{
        int len = sizeof(struct ieee80211_radiotap_header);

        /* IEEE80211_RADIOTAP_RATE rate */
        if (info->status.rates[0].idx >= 0 &&
            !(info->status.rates[0].flags & IEEE80211_TX_RC_MCS))
                len += 2;

        /* IEEE80211_RADIOTAP_TX_FLAGS */
        len += 2;

        /* IEEE80211_RADIOTAP_DATA_RETRIES */
        len += 1;

        /* IEEE80211_TX_RC_MCS */
        if (info->status.rates[0].idx >= 0 &&
            info->status.rates[0].flags & IEEE80211_TX_RC_MCS)
                len += 3;

        return len;
}

static void ieee80211_add_tx_radiotap_header(struct ieee80211_supported_band
                                             *sband, struct sk_buff *skb,
                                             int retry_count, int rtap_len)
{
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        struct ieee80211_radiotap_header *rthdr;
        unsigned char *pos;
        u16 txflags;

        rthdr = (struct ieee80211_radiotap_header *) skb_push(skb, rtap_len);

        memset(rthdr, 0, rtap_len);
        rthdr->it_len = cpu_to_le16(rtap_len);
        rthdr->it_present =
                cpu_to_le32((1 << IEEE80211_RADIOTAP_TX_FLAGS) |
                            (1 << IEEE80211_RADIOTAP_DATA_RETRIES));
        pos = (unsigned char *)(rthdr + 1);

        /*
         * XXX: Once radiotap gets the bitmap reset thing the vendor
         *      extensions proposal contains, we can actually report
         *      the whole set of tries we did.
         */

        /* IEEE80211_RADIOTAP_RATE */
        if (info->status.rates[0].idx >= 0 &&
            !(info->status.rates[0].flags & IEEE80211_TX_RC_MCS)) {
                rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_RATE);
                *pos = sband->bitrates[info->status.rates[0].idx].bitrate / 5;
                /* padding for tx flags */
                pos += 2;
        }

        /* IEEE80211_RADIOTAP_TX_FLAGS */
        txflags = 0;
        if (!(info->flags & IEEE80211_TX_STAT_ACK) &&
            !is_multicast_ether_addr(hdr->addr1))
                txflags |= IEEE80211_RADIOTAP_F_TX_FAIL;

        if ((info->status.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS) ||
            (info->status.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT))
                txflags |= IEEE80211_RADIOTAP_F_TX_CTS;
        else if (info->status.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS)
                txflags |= IEEE80211_RADIOTAP_F_TX_RTS;

        put_unaligned_le16(txflags, pos);
        pos += 2;

        /* IEEE80211_RADIOTAP_DATA_RETRIES */
        /* for now report the total retry_count */
        *pos = retry_count;
        pos++;

        /* IEEE80211_TX_RC_MCS */
        if (info->status.rates[0].idx >= 0 &&
            info->status.rates[0].flags & IEEE80211_TX_RC_MCS) {
                rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_MCS);
                pos[0] = IEEE80211_RADIOTAP_MCS_HAVE_MCS |
                         IEEE80211_RADIOTAP_MCS_HAVE_GI |
                         IEEE80211_RADIOTAP_MCS_HAVE_BW;
                if (info->status.rates[0].flags & IEEE80211_TX_RC_SHORT_GI)
                        pos[1] |= IEEE80211_RADIOTAP_MCS_SGI;
                if (info->status.rates[0].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
                        pos[1] |= IEEE80211_RADIOTAP_MCS_BW_40;
                if (info->status.rates[0].flags & IEEE80211_TX_RC_GREEN_FIELD)
                        pos[1] |= IEEE80211_RADIOTAP_MCS_FMT_GF;
                pos[2] = info->status.rates[0].idx;
                pos += 3;
        }

}

/*
 * Use a static threshold for now, best value to be determined
 * by testing ...
 * Should it depend on:
 *  - on # of retransmissions
 *  - current throughput (higher value for higher tpt)?
 */
#define STA_LOST_PKT_THRESHOLD  50

void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb)
{
        struct sk_buff *skb2;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
        __le16 fc;
        struct ieee80211_supported_band *sband;
        struct ieee80211_sub_if_data *sdata;
        struct net_device *prev_dev = NULL;
        struct sta_info *sta, *tmp;
        int retry_count = -1, i;
        int rates_idx = -1;
        bool send_to_cooked;
        bool acked;
        struct ieee80211_bar *bar;
        int rtap_len;

        for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
                if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
                    !(info->flags & IEEE80211_TX_STAT_AMPDU)) {
                        /* just the first aggr frame carry status info */
                        info->status.rates[i].idx = -1;
                        info->status.rates[i].count = 0;
                        break;
                } else if (info->status.rates[i].idx < 0) {
                        break;
                } else if (i >= hw->max_report_rates) {
                        /* the HW cannot have attempted that rate */
                        info->status.rates[i].idx = -1;
                        info->status.rates[i].count = 0;
                        break;
                }

                retry_count += info->status.rates[i].count;
        }
        rates_idx = i - 1;

        if (retry_count < 0)
                retry_count = 0;

        rcu_read_lock();

        sband = local->hw.wiphy->bands[info->band];
        fc = hdr->frame_control;

        for_each_sta_info(local, hdr->addr1, sta, tmp) {
                /* skip wrong virtual interface */
                if (!ether_addr_equal(hdr->addr2, sta->sdata->vif.addr))
                        continue;

                if (info->flags & IEEE80211_TX_STATUS_EOSP)
                        clear_sta_flag(sta, WLAN_STA_SP);

                acked = !!(info->flags & IEEE80211_TX_STAT_ACK);
                if (!acked && test_sta_flag(sta, WLAN_STA_PS_STA)) {
                        /*
                         * The STA is in power save mode, so assume
                         * that this TX packet failed because of that.
                         */
                        ieee80211_handle_filtered_frame(local, sta, skb);
                        rcu_read_unlock();
                        return;
                }

                if ((local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) &&
                    (rates_idx != -1))
                        sta->last_tx_rate = info->status.rates[rates_idx];

                if ((info->flags & IEEE80211_TX_STAT_AMPDU_NO_BACK) &&
                    (ieee80211_is_data_qos(fc))) {
                        u16 tid, ssn;
                        u8 *qc;

                        qc = ieee80211_get_qos_ctl(hdr);
                        tid = qc[0] & 0xf;
                        ssn = ((le16_to_cpu(hdr->seq_ctrl) + 0x10)
                                                & IEEE80211_SCTL_SEQ);
                        ieee80211_send_bar(&sta->sdata->vif, hdr->addr1,
                                           tid, ssn);
                }

                if (!acked && ieee80211_is_back_req(fc)) {
                        u16 tid, control;

                        /*
                         * BAR failed, store the last SSN and retry sending
                         * the BAR when the next unicast transmission on the
                         * same TID succeeds.
                         */
                        bar = (struct ieee80211_bar *) skb->data;
                        control = le16_to_cpu(bar->control);
                        if (!(control & IEEE80211_BAR_CTRL_MULTI_TID)) {
                                u16 ssn = le16_to_cpu(bar->start_seq_num);

                                tid = (control &
                                       IEEE80211_BAR_CTRL_TID_INFO_MASK) >>
                                      IEEE80211_BAR_CTRL_TID_INFO_SHIFT;

                                ieee80211_set_bar_pending(sta, tid, ssn);
                        }
                }

                if (info->flags & IEEE80211_TX_STAT_TX_FILTERED) {
                        ieee80211_handle_filtered_frame(local, sta, skb);
                        rcu_read_unlock();
                        return;
                } else {
                        if (!acked)
                                sta->tx_retry_failed++;
                        sta->tx_retry_count += retry_count;
                }

                rate_control_tx_status(local, sband, sta, skb);
                if (ieee80211_vif_is_mesh(&sta->sdata->vif))
                        ieee80211s_update_metric(local, sta, skb);

                if (!(info->flags & IEEE80211_TX_CTL_INJECTED) && acked)
                        ieee80211_frame_acked(sta, skb);

                if ((sta->sdata->vif.type == NL80211_IFTYPE_STATION) &&
                    (local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS))
                        ieee80211_sta_tx_notify(sta->sdata, (void *) skb->data, acked);

                if (local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) {
                        if (info->flags & IEEE80211_TX_STAT_ACK) {
                                if (sta->lost_packets)
                                        sta->lost_packets = 0;
                        } else if (++sta->lost_packets >= STA_LOST_PKT_THRESHOLD) {
                                cfg80211_cqm_pktloss_notify(sta->sdata->dev,
                                                            sta->sta.addr,
                                                            sta->lost_packets,
                                                            GFP_ATOMIC);
                                sta->lost_packets = 0;
                        }
                }
        }

        rcu_read_unlock();

        ieee80211_led_tx(local, 0);

        /* SNMP counters
         * Fragments are passed to low-level drivers as separate skbs, so these
         * are actually fragments, not frames. Update frame counters only for
         * the first fragment of the frame. */
        if (info->flags & IEEE80211_TX_STAT_ACK) {
                if (ieee80211_is_first_frag(hdr->seq_ctrl)) {
                        local->dot11TransmittedFrameCount++;
                        if (is_multicast_ether_addr(hdr->addr1))
                                local->dot11MulticastTransmittedFrameCount++;
                        if (retry_count > 0)
                                local->dot11RetryCount++;
                        if (retry_count > 1)
                                local->dot11MultipleRetryCount++;
                }

                /* This counter shall be incremented for an acknowledged MPDU
                 * with an individual address in the address 1 field or an MPDU
                 * with a multicast address in the address 1 field of type Data
                 * or Management. */
                if (!is_multicast_ether_addr(hdr->addr1) ||
                    ieee80211_is_data(fc) ||
                    ieee80211_is_mgmt(fc))
                        local->dot11TransmittedFragmentCount++;
        } else {
                if (ieee80211_is_first_frag(hdr->seq_ctrl))
                        local->dot11FailedCount++;
        }

        if (ieee80211_is_nullfunc(fc) && ieee80211_has_pm(fc) &&
            (local->hw.flags & IEEE80211_HW_REPORTS_TX_ACK_STATUS) &&
            !(info->flags & IEEE80211_TX_CTL_INJECTED) &&
            local->ps_sdata && !(local->scanning)) {
                if (info->flags & IEEE80211_TX_STAT_ACK) {
                        local->ps_sdata->u.mgd.flags |=
                                        IEEE80211_STA_NULLFUNC_ACKED;
                } else
                        mod_timer(&local->dynamic_ps_timer, jiffies +
                                        msecs_to_jiffies(10));
        }

        if (info->flags & IEEE80211_TX_INTFL_NL80211_FRAME_TX) {
                u64 cookie = (unsigned long)skb;

                if (ieee80211_is_nullfunc(hdr->frame_control) ||
                    ieee80211_is_qos_nullfunc(hdr->frame_control)) {
                        acked = info->flags & IEEE80211_TX_STAT_ACK;

                        cfg80211_probe_status(skb->dev, hdr->addr1,
                                              cookie, acked, GFP_ATOMIC);
                } else {
                        struct ieee80211_work *wk;

                        rcu_read_lock();
                        list_for_each_entry_rcu(wk, &local->work_list, list) {
                                if (wk->type != IEEE80211_WORK_OFFCHANNEL_TX)
                                        continue;
                                if (wk->offchan_tx.frame != skb)
                                        continue;
                                wk->offchan_tx.status = true;
                                break;
                        }
                        rcu_read_unlock();
                        if (local->hw_roc_skb_for_status == skb) {
                                cookie = local->hw_roc_cookie ^ 2;
                                local->hw_roc_skb_for_status = NULL;
                        }

                        cfg80211_mgmt_tx_status(
                                skb->dev, cookie, skb->data, skb->len,
                                !!(info->flags & IEEE80211_TX_STAT_ACK),
                                GFP_ATOMIC);
                }
        }

        if (unlikely(info->ack_frame_id)) {
                struct sk_buff *ack_skb;
                unsigned long flags;

                spin_lock_irqsave(&local->ack_status_lock, flags);
                ack_skb = idr_find(&local->ack_status_frames,
                                   info->ack_frame_id);
                if (ack_skb)
                        idr_remove(&local->ack_status_frames,
                                   info->ack_frame_id);
                spin_unlock_irqrestore(&local->ack_status_lock, flags);

                /* consumes ack_skb */
                if (ack_skb)
                        skb_complete_wifi_ack(ack_skb,
                                info->flags & IEEE80211_TX_STAT_ACK);
        }

        /* this was a transmitted frame, but now we want to reuse it */
        skb_orphan(skb);

        /* Need to make a copy before skb->cb gets cleared */
        send_to_cooked = !!(info->flags & IEEE80211_TX_CTL_INJECTED) ||
                         !(ieee80211_is_data(fc));

        /*
         * This is a bit racy but we can avoid a lot of work
         * with this test...
         */
        if (!local->monitors && (!send_to_cooked || !local->cooked_mntrs)) {
                dev_kfree_skb(skb);
                return;
        }

        /* send frame to monitor interfaces now */
        rtap_len = ieee80211_tx_radiotap_len(info);
        if (WARN_ON_ONCE(skb_headroom(skb) < rtap_len)) {
                printk(KERN_ERR "ieee80211_tx_status: headroom too small\n");
                dev_kfree_skb(skb);
                return;
        }
        ieee80211_add_tx_radiotap_header(sband, skb, retry_count, rtap_len);

        /* XXX: is this sufficient for BPF? */
        skb_set_mac_header(skb, 0);
        skb->ip_summed = CHECKSUM_UNNECESSARY;
        skb->pkt_type = PACKET_OTHERHOST;
        skb->protocol = htons(ETH_P_802_2);
        memset(skb->cb, 0, sizeof(skb->cb));

        rcu_read_lock();
        list_for_each_entry_rcu(sdata, &local->interfaces, list) {
                if (sdata->vif.type == NL80211_IFTYPE_MONITOR) {
                        if (!ieee80211_sdata_running(sdata))
                                continue;

                        if ((sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES) &&
                            !send_to_cooked)
                                continue;

                        if (prev_dev) {
                                skb2 = skb_clone(skb, GFP_ATOMIC);
                                if (skb2) {
                                        skb2->dev = prev_dev;
                                        netif_rx(skb2);
                                }
                        }

                        prev_dev = sdata->dev;
                }
        }
        if (prev_dev) {
                skb->dev = prev_dev;
                netif_rx(skb);
                skb = NULL;
        }
        rcu_read_unlock();
        dev_kfree_skb(skb);
}
EXPORT_SYMBOL(ieee80211_tx_status);

void ieee80211_report_low_ack(struct ieee80211_sta *pubsta, u32 num_packets)
{
        struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
        cfg80211_cqm_pktloss_notify(sta->sdata->dev, sta->sta.addr,
                                    num_packets, GFP_ATOMIC);
}
EXPORT_SYMBOL(ieee80211_report_low_ack);

void ieee80211_free_txskb(struct ieee80211_hw *hw, struct sk_buff *skb)
{
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

        if (unlikely(info->ack_frame_id)) {
                struct sk_buff *ack_skb;
                unsigned long flags;

                spin_lock_irqsave(&local->ack_status_lock, flags);
                ack_skb = idr_find(&local->ack_status_frames,
                                   info->ack_frame_id);
                if (ack_skb)
                        idr_remove(&local->ack_status_frames,
                                   info->ack_frame_id);
                spin_unlock_irqrestore(&local->ack_status_lock, flags);

                /* consumes ack_skb */
                if (ack_skb)
                        dev_kfree_skb_any(ack_skb);
        }

        dev_kfree_skb_any(skb);
}
EXPORT_SYMBOL(ieee80211_free_txskb);