Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6

[linux-2.6] / net / mac80211 / rx.c

/*
 * 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>
 *
 * 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/jiffies.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/rcupdate.h>
#include <net/mac80211.h>
#include <net/ieee80211_radiotap.h>

#include "ieee80211_i.h"
#include "led.h"
#include "mesh.h"
#include "wep.h"
#include "wpa.h"
#include "tkip.h"
#include "wme.h"

static u8 ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw,
                                           struct tid_ampdu_rx *tid_agg_rx,
                                           struct sk_buff *skb,
                                           u16 mpdu_seq_num,
                                           int bar_req);
/*
 * monitor mode reception
 *
 * This function cleans up the SKB, i.e. it removes all the stuff
 * only useful for monitoring.
 */
static struct sk_buff *remove_monitor_info(struct ieee80211_local *local,
                                           struct sk_buff *skb,
                                           int rtap_len)
{
        skb_pull(skb, rtap_len);

        if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) {
                if (likely(skb->len > FCS_LEN))
                        skb_trim(skb, skb->len - FCS_LEN);
                else {
                        /* driver bug */
                        WARN_ON(1);
                        dev_kfree_skb(skb);
                        skb = NULL;
                }
        }

        return skb;
}

static inline int should_drop_frame(struct ieee80211_rx_status *status,
                                    struct sk_buff *skb,
                                    int present_fcs_len,
                                    int radiotap_len)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;

        if (status->flag & (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
                return 1;
        if (unlikely(skb->len < 16 + present_fcs_len + radiotap_len))
                return 1;
        if (ieee80211_is_ctl(hdr->frame_control) &&
            !ieee80211_is_pspoll(hdr->frame_control) &&
            !ieee80211_is_back_req(hdr->frame_control))
                return 1;
        return 0;
}

static int
ieee80211_rx_radiotap_len(struct ieee80211_local *local,
                          struct ieee80211_rx_status *status)
{
        int len;

        /* always present fields */
        len = sizeof(struct ieee80211_radiotap_header) + 9;

        if (status->flag & RX_FLAG_TSFT)
                len += 8;
        if (local->hw.flags & IEEE80211_HW_SIGNAL_DB ||
            local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
                len += 1;
        if (local->hw.flags & IEEE80211_HW_NOISE_DBM)
                len += 1;

        if (len & 1) /* padding for RX_FLAGS if necessary */
                len++;

        /* make sure radiotap starts at a naturally aligned address */
        if (len % 8)
                len = roundup(len, 8);

        return len;
}

/**
 * ieee80211_add_rx_radiotap_header - add radiotap header
 *
 * add a radiotap header containing all the fields which the hardware provided.
 */
static void
ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
                                 struct sk_buff *skb,
                                 struct ieee80211_rx_status *status,
                                 struct ieee80211_rate *rate,
                                 int rtap_len)
{
        struct ieee80211_radiotap_header *rthdr;
        unsigned char *pos;

        rthdr = (struct ieee80211_radiotap_header *)skb_push(skb, rtap_len);
        memset(rthdr, 0, rtap_len);

        /* radiotap header, set always present flags */
        rthdr->it_present =
                cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
                            (1 << IEEE80211_RADIOTAP_RATE) |
                            (1 << IEEE80211_RADIOTAP_CHANNEL) |
                            (1 << IEEE80211_RADIOTAP_ANTENNA) |
                            (1 << IEEE80211_RADIOTAP_RX_FLAGS));
        rthdr->it_len = cpu_to_le16(rtap_len);

        pos = (unsigned char *)(rthdr+1);

        /* the order of the following fields is important */

        /* IEEE80211_RADIOTAP_TSFT */
        if (status->flag & RX_FLAG_TSFT) {
                *(__le64 *)pos = cpu_to_le64(status->mactime);
                rthdr->it_present |=
                        cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT);
                pos += 8;
        }

        /* IEEE80211_RADIOTAP_FLAGS */
        if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
                *pos |= IEEE80211_RADIOTAP_F_FCS;
        if (status->flag & RX_FLAG_SHORTPRE)
                *pos |= IEEE80211_RADIOTAP_F_SHORTPRE;
        pos++;

        /* IEEE80211_RADIOTAP_RATE */
        *pos = rate->bitrate / 5;
        pos++;

        /* IEEE80211_RADIOTAP_CHANNEL */
        *(__le16 *)pos = cpu_to_le16(status->freq);
        pos += 2;
        if (status->band == IEEE80211_BAND_5GHZ)
                *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_OFDM |
                                             IEEE80211_CHAN_5GHZ);
        else if (rate->flags & IEEE80211_RATE_ERP_G)
                *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_OFDM |
                                             IEEE80211_CHAN_2GHZ);
        else
                *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_CCK |
                                             IEEE80211_CHAN_2GHZ);
        pos += 2;

        /* IEEE80211_RADIOTAP_DBM_ANTSIGNAL */
        if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM) {
                *pos = status->signal;
                rthdr->it_present |=
                        cpu_to_le32(1 << IEEE80211_RADIOTAP_DBM_ANTSIGNAL);
                pos++;
        }

        /* IEEE80211_RADIOTAP_DBM_ANTNOISE */
        if (local->hw.flags & IEEE80211_HW_NOISE_DBM) {
                *pos = status->noise;
                rthdr->it_present |=
                        cpu_to_le32(1 << IEEE80211_RADIOTAP_DBM_ANTNOISE);
                pos++;
        }

        /* IEEE80211_RADIOTAP_LOCK_QUALITY is missing */

        /* IEEE80211_RADIOTAP_ANTENNA */
        *pos = status->antenna;
        pos++;

        /* IEEE80211_RADIOTAP_DB_ANTSIGNAL */
        if (local->hw.flags & IEEE80211_HW_SIGNAL_DB) {
                *pos = status->signal;
                rthdr->it_present |=
                        cpu_to_le32(1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL);
                pos++;
        }

        /* IEEE80211_RADIOTAP_DB_ANTNOISE is not used */

        /* IEEE80211_RADIOTAP_RX_FLAGS */
        /* ensure 2 byte alignment for the 2 byte field as required */
        if ((pos - (unsigned char *)rthdr) & 1)
                pos++;
        /* FIXME: when radiotap gets a 'bad PLCP' flag use it here */
        if (status->flag & (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
                *(__le16 *)pos |= cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADFCS);
        pos += 2;
}

/*
 * This function copies a received frame to all monitor interfaces and
 * returns a cleaned-up SKB that no longer includes the FCS nor the
 * radiotap header the driver might have added.
 */
static struct sk_buff *
ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
                     struct ieee80211_rx_status *status,
                     struct ieee80211_rate *rate)
{
        struct ieee80211_sub_if_data *sdata;
        int needed_headroom = 0;
        struct sk_buff *skb, *skb2;
        struct net_device *prev_dev = NULL;
        int present_fcs_len = 0;
        int rtap_len = 0;

        /*
         * First, we may need to make a copy of the skb because
         *  (1) we need to modify it for radiotap (if not present), and
         *  (2) the other RX handlers will modify the skb we got.
         *
         * We don't need to, of course, if we aren't going to return
         * the SKB because it has a bad FCS/PLCP checksum.
         */
        if (status->flag & RX_FLAG_RADIOTAP)
                rtap_len = ieee80211_get_radiotap_len(origskb->data);
        else
                /* room for the radiotap header based on driver features */
                needed_headroom = ieee80211_rx_radiotap_len(local, status);

        if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
                present_fcs_len = FCS_LEN;

        if (!local->monitors) {
                if (should_drop_frame(status, origskb, present_fcs_len,
                                      rtap_len)) {
                        dev_kfree_skb(origskb);
                        return NULL;
                }

                return remove_monitor_info(local, origskb, rtap_len);
        }

        if (should_drop_frame(status, origskb, present_fcs_len, rtap_len)) {
                /* only need to expand headroom if necessary */
                skb = origskb;
                origskb = NULL;

                /*
                 * This shouldn't trigger often because most devices have an
                 * RX header they pull before we get here, and that should
                 * be big enough for our radiotap information. We should
                 * probably export the length to drivers so that we can have
                 * them allocate enough headroom to start with.
                 */
                if (skb_headroom(skb) < needed_headroom &&
                    pskb_expand_head(skb, needed_headroom, 0, GFP_ATOMIC)) {
                        dev_kfree_skb(skb);
                        return NULL;
                }
        } else {
                /*
                 * Need to make a copy and possibly remove radiotap header
                 * and FCS from the original.
                 */
                skb = skb_copy_expand(origskb, needed_headroom, 0, GFP_ATOMIC);

                origskb = remove_monitor_info(local, origskb, rtap_len);

                if (!skb)
                        return origskb;
        }

        /* if necessary, prepend radiotap information */
        if (!(status->flag & RX_FLAG_RADIOTAP))
                ieee80211_add_rx_radiotap_header(local, skb, status, rate,
                                                 needed_headroom);

        skb_reset_mac_header(skb);
        skb->ip_summed = CHECKSUM_UNNECESSARY;
        skb->pkt_type = PACKET_OTHERHOST;
        skb->protocol = htons(ETH_P_802_2);

        list_for_each_entry_rcu(sdata, &local->interfaces, list) {
                if (!netif_running(sdata->dev))
                        continue;

                if (sdata->vif.type != NL80211_IFTYPE_MONITOR)
                        continue;

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

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

                prev_dev = sdata->dev;
                sdata->dev->stats.rx_packets++;
                sdata->dev->stats.rx_bytes += skb->len;
        }

        if (prev_dev) {
                skb->dev = prev_dev;
                netif_rx(skb);
        } else
                dev_kfree_skb(skb);

        return origskb;
}


static void ieee80211_parse_qos(struct ieee80211_rx_data *rx)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
        int tid;

        /* does the frame have a qos control field? */
        if (ieee80211_is_data_qos(hdr->frame_control)) {
                u8 *qc = ieee80211_get_qos_ctl(hdr);
                /* frame has qos control */
                tid = *qc & IEEE80211_QOS_CTL_TID_MASK;
                if (*qc & IEEE80211_QOS_CONTROL_A_MSDU_PRESENT)
                        rx->flags |= IEEE80211_RX_AMSDU;
                else
                        rx->flags &= ~IEEE80211_RX_AMSDU;
        } else {
                /*
                 * IEEE 802.11-2007, 7.1.3.4.1 ("Sequence Number field"):
                 *
                 *      Sequence numbers for management frames, QoS data
                 *      frames with a broadcast/multicast address in the
                 *      Address 1 field, and all non-QoS data frames sent
                 *      by QoS STAs are assigned using an additional single
                 *      modulo-4096 counter, [...]
                 *
                 * We also use that counter for non-QoS STAs.
                 */
                tid = NUM_RX_DATA_QUEUES - 1;
        }

        rx->queue = tid;
        /* Set skb->priority to 1d tag if highest order bit of TID is not set.
         * For now, set skb->priority to 0 for other cases. */
        rx->skb->priority = (tid > 7) ? 0 : tid;
}

static void ieee80211_verify_ip_alignment(struct ieee80211_rx_data *rx)
{
#ifdef CONFIG_MAC80211_DEBUG_PACKET_ALIGNMENT
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
        int hdrlen;

        if (!ieee80211_is_data_present(hdr->frame_control))
                return;

        /*
         * Drivers are required to align the payload data in a way that
         * guarantees that the contained IP header is aligned to a four-
         * byte boundary. In the case of regular frames, this simply means
         * aligning the payload to a four-byte boundary (because either
         * the IP header is directly contained, or IV/RFC1042 headers that
         * have a length divisible by four are in front of it.
         *
         * With A-MSDU frames, however, the payload data address must
         * yield two modulo four because there are 14-byte 802.3 headers
         * within the A-MSDU frames that push the IP header further back
         * to a multiple of four again. Thankfully, the specs were sane
         * enough this time around to require padding each A-MSDU subframe
         * to a length that is a multiple of four.
         *
         * Padding like atheros hardware adds which is inbetween the 802.11
         * header and the payload is not supported, the driver is required
         * to move the 802.11 header further back in that case.
         */
        hdrlen = ieee80211_hdrlen(hdr->frame_control);
        if (rx->flags & IEEE80211_RX_AMSDU)
                hdrlen += ETH_HLEN;
        WARN_ON_ONCE(((unsigned long)(rx->skb->data + hdrlen)) & 3);
#endif
}


/* rx handlers */

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_passive_scan(struct ieee80211_rx_data *rx)
{
        struct ieee80211_local *local = rx->local;
        struct sk_buff *skb = rx->skb;

        if (unlikely(local->hw_scanning))
                return ieee80211_scan_rx(rx->sdata, skb, rx->status);

        if (unlikely(local->sw_scanning)) {
                /* drop all the other packets during a software scan anyway */
                if (ieee80211_scan_rx(rx->sdata, skb, rx->status)
                    != RX_QUEUED)
                        dev_kfree_skb(skb);
                return RX_QUEUED;
        }

        if (unlikely(rx->flags & IEEE80211_RX_IN_SCAN)) {
                /* scanning finished during invoking of handlers */
                I802_DEBUG_INC(local->rx_handlers_drop_passive_scan);
                return RX_DROP_UNUSABLE;
        }

        return RX_CONTINUE;
}

static ieee80211_rx_result
ieee80211_rx_mesh_check(struct ieee80211_rx_data *rx)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
        unsigned int hdrlen = ieee80211_hdrlen(hdr->frame_control);

        if (ieee80211_is_data(hdr->frame_control)) {
                if (!ieee80211_has_a4(hdr->frame_control))
                        return RX_DROP_MONITOR;
                if (memcmp(hdr->addr4, rx->dev->dev_addr, ETH_ALEN) == 0)
                        return RX_DROP_MONITOR;
        }

        /* If there is not an established peer link and this is not a peer link
         * establisment frame, beacon or probe, drop the frame.
         */

        if (!rx->sta || sta_plink_state(rx->sta) != PLINK_ESTAB) {
                struct ieee80211_mgmt *mgmt;

                if (!ieee80211_is_mgmt(hdr->frame_control))
                        return RX_DROP_MONITOR;

                if (ieee80211_is_action(hdr->frame_control)) {
                        mgmt = (struct ieee80211_mgmt *)hdr;
                        if (mgmt->u.action.category != PLINK_CATEGORY)
                                return RX_DROP_MONITOR;
                        return RX_CONTINUE;
                }

                if (ieee80211_is_probe_req(hdr->frame_control) ||
                    ieee80211_is_probe_resp(hdr->frame_control) ||
                    ieee80211_is_beacon(hdr->frame_control))
                        return RX_CONTINUE;

                return RX_DROP_MONITOR;

        }

#define msh_h_get(h, l) ((struct ieee80211s_hdr *) ((u8 *)h + l))

        if (ieee80211_is_data(hdr->frame_control) &&
            is_multicast_ether_addr(hdr->addr1) &&
            mesh_rmc_check(hdr->addr4, msh_h_get(hdr, hdrlen), rx->sdata))
                return RX_DROP_MONITOR;
#undef msh_h_get

        return RX_CONTINUE;
}


static ieee80211_rx_result debug_noinline
ieee80211_rx_h_check(struct ieee80211_rx_data *rx)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;

        /* Drop duplicate 802.11 retransmissions (IEEE 802.11 Chap. 9.2.9) */
        if (rx->sta && !is_multicast_ether_addr(hdr->addr1)) {
                if (unlikely(ieee80211_has_retry(hdr->frame_control) &&
                             rx->sta->last_seq_ctrl[rx->queue] ==
                             hdr->seq_ctrl)) {
                        if (rx->flags & IEEE80211_RX_RA_MATCH) {
                                rx->local->dot11FrameDuplicateCount++;
                                rx->sta->num_duplicates++;
                        }
                        return RX_DROP_MONITOR;
                } else
                        rx->sta->last_seq_ctrl[rx->queue] = hdr->seq_ctrl;
        }

        if (unlikely(rx->skb->len < 16)) {
                I802_DEBUG_INC(rx->local->rx_handlers_drop_short);
                return RX_DROP_MONITOR;
        }

        /* Drop disallowed frame classes based on STA auth/assoc state;
         * IEEE 802.11, Chap 5.5.
         *
         * mac80211 filters only based on association state, i.e. it drops
         * Class 3 frames from not associated stations. hostapd sends
         * deauth/disassoc frames when needed. In addition, hostapd is
         * responsible for filtering on both auth and assoc states.
         */

        if (ieee80211_vif_is_mesh(&rx->sdata->vif))
                return ieee80211_rx_mesh_check(rx);

        if (unlikely((ieee80211_is_data(hdr->frame_control) ||
                      ieee80211_is_pspoll(hdr->frame_control)) &&
                     rx->sdata->vif.type != NL80211_IFTYPE_ADHOC &&
                     (!rx->sta || !test_sta_flags(rx->sta, WLAN_STA_ASSOC)))) {
                if ((!ieee80211_has_fromds(hdr->frame_control) &&
                     !ieee80211_has_tods(hdr->frame_control) &&
                     ieee80211_is_data(hdr->frame_control)) ||
                    !(rx->flags & IEEE80211_RX_RA_MATCH)) {
                        /* Drop IBSS frames and frames for other hosts
                         * silently. */
                        return RX_DROP_MONITOR;
                }

                return RX_DROP_MONITOR;
        }

        return RX_CONTINUE;
}


static ieee80211_rx_result debug_noinline
ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
        int keyidx;
        int hdrlen;
        ieee80211_rx_result result = RX_DROP_UNUSABLE;
        struct ieee80211_key *stakey = NULL;

        /*
         * Key selection 101
         *
         * There are three types of keys:
         *  - GTK (group keys)
         *  - PTK (pairwise keys)
         *  - STK (station-to-station pairwise keys)
         *
         * When selecting a key, we have to distinguish between multicast
         * (including broadcast) and unicast frames, the latter can only
         * use PTKs and STKs while the former always use GTKs. Unless, of
         * course, actual WEP keys ("pre-RSNA") are used, then unicast
         * frames can also use key indizes like GTKs. Hence, if we don't
         * have a PTK/STK we check the key index for a WEP key.
         *
         * Note that in a regular BSS, multicast frames are sent by the
         * AP only, associated stations unicast the frame to the AP first
         * which then multicasts it on their behalf.
         *
         * There is also a slight problem in IBSS mode: GTKs are negotiated
         * with each station, that is something we don't currently handle.
         * The spec seems to expect that one negotiates the same key with
         * every station but there's no such requirement; VLANs could be
         * possible.
         */

        if (!ieee80211_has_protected(hdr->frame_control))
                return RX_CONTINUE;

        /*
         * No point in finding a key and decrypting if the frame is neither
         * addressed to us nor a multicast frame.
         */
        if (!(rx->flags & IEEE80211_RX_RA_MATCH))
                return RX_CONTINUE;

        if (rx->sta)
                stakey = rcu_dereference(rx->sta->key);

        if (!is_multicast_ether_addr(hdr->addr1) && stakey) {
                rx->key = stakey;
        } else {
                /*
                 * The device doesn't give us the IV so we won't be
                 * able to look up the key. That's ok though, we
                 * don't need to decrypt the frame, we just won't
                 * be able to keep statistics accurate.
                 * Except for key threshold notifications, should
                 * we somehow allow the driver to tell us which key
                 * the hardware used if this flag is set?
                 */
                if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
                    (rx->status->flag & RX_FLAG_IV_STRIPPED))
                        return RX_CONTINUE;

                hdrlen = ieee80211_hdrlen(hdr->frame_control);

                if (rx->skb->len < 8 + hdrlen)
                        return RX_DROP_UNUSABLE; /* TODO: count this? */

                /*
                 * no need to call ieee80211_wep_get_keyidx,
                 * it verifies a bunch of things we've done already
                 */
                keyidx = rx->skb->data[hdrlen + 3] >> 6;

                rx->key = rcu_dereference(rx->sdata->keys[keyidx]);

                /*
                 * RSNA-protected unicast frames should always be sent with
                 * pairwise or station-to-station keys, but for WEP we allow
                 * using a key index as well.
                 */
                if (rx->key && rx->key->conf.alg != ALG_WEP &&
                    !is_multicast_ether_addr(hdr->addr1))
                        rx->key = NULL;
        }

        if (rx->key) {
                rx->key->tx_rx_count++;
                /* TODO: add threshold stuff again */
        } else {
                return RX_DROP_MONITOR;
        }

        /* Check for weak IVs if possible */
        if (rx->sta && rx->key->conf.alg == ALG_WEP &&
            ieee80211_is_data(hdr->frame_control) &&
            (!(rx->status->flag & RX_FLAG_IV_STRIPPED) ||
             !(rx->status->flag & RX_FLAG_DECRYPTED)) &&
            ieee80211_wep_is_weak_iv(rx->skb, rx->key))
                rx->sta->wep_weak_iv_count++;

        switch (rx->key->conf.alg) {
        case ALG_WEP:
                result = ieee80211_crypto_wep_decrypt(rx);
                break;
        case ALG_TKIP:
                result = ieee80211_crypto_tkip_decrypt(rx);
                break;
        case ALG_CCMP:
                result = ieee80211_crypto_ccmp_decrypt(rx);
                break;
        }

        /* either the frame has been decrypted or will be dropped */
        rx->status->flag |= RX_FLAG_DECRYPTED;

        return result;
}

static void ap_sta_ps_start(struct sta_info *sta)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;

        atomic_inc(&sdata->bss->num_sta_ps);
        set_and_clear_sta_flags(sta, WLAN_STA_PS, WLAN_STA_PSPOLL);
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
        printk(KERN_DEBUG "%s: STA %pM aid %d enters power save mode\n",
               sdata->dev->name, sta->sta.addr, sta->sta.aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
}

static int ap_sta_ps_end(struct sta_info *sta)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        struct ieee80211_local *local = sdata->local;
        struct sk_buff *skb;
        int sent = 0;

        atomic_dec(&sdata->bss->num_sta_ps);

        clear_sta_flags(sta, WLAN_STA_PS | WLAN_STA_PSPOLL);

        if (!skb_queue_empty(&sta->ps_tx_buf))
                sta_info_clear_tim_bit(sta);

#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
        printk(KERN_DEBUG "%s: STA %pM aid %d exits power save mode\n",
               sdata->dev->name, sta->sta.addr, sta->sta.aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */

        /* Send all buffered frames to the station */
        while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL) {
                sent++;
                skb->requeue = 1;
                dev_queue_xmit(skb);
        }
        while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
                local->total_ps_buffered--;
                sent++;
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
                printk(KERN_DEBUG "%s: STA %pM aid %d send PS frame "
                       "since STA not sleeping anymore\n", sdata->dev->name,
                       sta->sta.addr, sta->sta.aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
                skb->requeue = 1;
                dev_queue_xmit(skb);
        }

        return sent;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
{
        struct sta_info *sta = rx->sta;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;

        if (!sta)
                return RX_CONTINUE;

        /* Update last_rx only for IBSS packets which are for the current
         * BSSID to avoid keeping the current IBSS network alive in cases where
         * other STAs are using different BSSID. */
        if (rx->sdata->vif.type == NL80211_IFTYPE_ADHOC) {
                u8 *bssid = ieee80211_get_bssid(hdr, rx->skb->len,
                                                NL80211_IFTYPE_ADHOC);
                if (compare_ether_addr(bssid, rx->sdata->u.sta.bssid) == 0)
                        sta->last_rx = jiffies;
        } else
        if (!is_multicast_ether_addr(hdr->addr1) ||
            rx->sdata->vif.type == NL80211_IFTYPE_STATION) {
                /* Update last_rx only for unicast frames in order to prevent
                 * the Probe Request frames (the only broadcast frames from a
                 * STA in infrastructure mode) from keeping a connection alive.
                 * Mesh beacons will update last_rx when if they are found to
                 * match the current local configuration when processed.
                 */
                sta->last_rx = jiffies;
        }

        if (!(rx->flags & IEEE80211_RX_RA_MATCH))
                return RX_CONTINUE;

        sta->rx_fragments++;
        sta->rx_bytes += rx->skb->len;
        sta->last_signal = rx->status->signal;
        sta->last_qual = rx->status->qual;
        sta->last_noise = rx->status->noise;

        if (!ieee80211_has_morefrags(hdr->frame_control) &&
            (rx->sdata->vif.type == NL80211_IFTYPE_AP ||
             rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN)) {
                /* Change STA power saving mode only in the end of a frame
                 * exchange sequence */
                if (test_sta_flags(sta, WLAN_STA_PS) &&
                    !ieee80211_has_pm(hdr->frame_control))
                        rx->sent_ps_buffered += ap_sta_ps_end(sta);
                else if (!test_sta_flags(sta, WLAN_STA_PS) &&
                         ieee80211_has_pm(hdr->frame_control))
                        ap_sta_ps_start(sta);
        }

        /* Drop data::nullfunc frames silently, since they are used only to
         * control station power saving mode. */
        if (ieee80211_is_nullfunc(hdr->frame_control)) {
                I802_DEBUG_INC(rx->local->rx_handlers_drop_nullfunc);
                /* Update counter and free packet here to avoid counting this
                 * as a dropped packed. */
                sta->rx_packets++;
                dev_kfree_skb(rx->skb);
                return RX_QUEUED;
        }

        return RX_CONTINUE;
} /* ieee80211_rx_h_sta_process */

static inline struct ieee80211_fragment_entry *
ieee80211_reassemble_add(struct ieee80211_sub_if_data *sdata,
                         unsigned int frag, unsigned int seq, int rx_queue,
                         struct sk_buff **skb)
{
        struct ieee80211_fragment_entry *entry;
        int idx;

        idx = sdata->fragment_next;
        entry = &sdata->fragments[sdata->fragment_next++];
        if (sdata->fragment_next >= IEEE80211_FRAGMENT_MAX)
                sdata->fragment_next = 0;

        if (!skb_queue_empty(&entry->skb_list)) {
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
                struct ieee80211_hdr *hdr =
                        (struct ieee80211_hdr *) entry->skb_list.next->data;
                printk(KERN_DEBUG "%s: RX reassembly removed oldest "
                       "fragment entry (idx=%d age=%lu seq=%d last_frag=%d "
                       "addr1=%pM addr2=%pM\n",
                       sdata->dev->name, idx,
                       jiffies - entry->first_frag_time, entry->seq,
                       entry->last_frag, hdr->addr1, hdr->addr2);
#endif
                __skb_queue_purge(&entry->skb_list);
        }

        __skb_queue_tail(&entry->skb_list, *skb); /* no need for locking */
        *skb = NULL;
        entry->first_frag_time = jiffies;
        entry->seq = seq;
        entry->rx_queue = rx_queue;
        entry->last_frag = frag;
        entry->ccmp = 0;
        entry->extra_len = 0;

        return entry;
}

static inline struct ieee80211_fragment_entry *
ieee80211_reassemble_find(struct ieee80211_sub_if_data *sdata,
                          unsigned int frag, unsigned int seq,
                          int rx_queue, struct ieee80211_hdr *hdr)
{
        struct ieee80211_fragment_entry *entry;
        int i, idx;

        idx = sdata->fragment_next;
        for (i = 0; i < IEEE80211_FRAGMENT_MAX; i++) {
                struct ieee80211_hdr *f_hdr;

                idx--;
                if (idx < 0)
                        idx = IEEE80211_FRAGMENT_MAX - 1;

                entry = &sdata->fragments[idx];
                if (skb_queue_empty(&entry->skb_list) || entry->seq != seq ||
                    entry->rx_queue != rx_queue ||
                    entry->last_frag + 1 != frag)
                        continue;

                f_hdr = (struct ieee80211_hdr *)entry->skb_list.next->data;

                /*
                 * Check ftype and addresses are equal, else check next fragment
                 */
                if (((hdr->frame_control ^ f_hdr->frame_control) &
                     cpu_to_le16(IEEE80211_FCTL_FTYPE)) ||
                    compare_ether_addr(hdr->addr1, f_hdr->addr1) != 0 ||
                    compare_ether_addr(hdr->addr2, f_hdr->addr2) != 0)
                        continue;

                if (time_after(jiffies, entry->first_frag_time + 2 * HZ)) {
                        __skb_queue_purge(&entry->skb_list);
                        continue;
                }
                return entry;
        }

        return NULL;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
{
        struct ieee80211_hdr *hdr;
        u16 sc;
        __le16 fc;
        unsigned int frag, seq;
        struct ieee80211_fragment_entry *entry;
        struct sk_buff *skb;

        hdr = (struct ieee80211_hdr *)rx->skb->data;
        fc = hdr->frame_control;
        sc = le16_to_cpu(hdr->seq_ctrl);
        frag = sc & IEEE80211_SCTL_FRAG;

        if (likely((!ieee80211_has_morefrags(fc) && frag == 0) ||
                   (rx->skb)->len < 24 ||
                   is_multicast_ether_addr(hdr->addr1))) {
                /* not fragmented */
                goto out;
        }
        I802_DEBUG_INC(rx->local->rx_handlers_fragments);

        seq = (sc & IEEE80211_SCTL_SEQ) >> 4;

        if (frag == 0) {
                /* This is the first fragment of a new frame. */
                entry = ieee80211_reassemble_add(rx->sdata, frag, seq,
                                                 rx->queue, &(rx->skb));
                if (rx->key && rx->key->conf.alg == ALG_CCMP &&
                    ieee80211_has_protected(fc)) {
                        /* Store CCMP PN so that we can verify that the next
                         * fragment has a sequential PN value. */
                        entry->ccmp = 1;
                        memcpy(entry->last_pn,
                               rx->key->u.ccmp.rx_pn[rx->queue],
                               CCMP_PN_LEN);
                }
                return RX_QUEUED;
        }

        /* This is a fragment for a frame that should already be pending in
         * fragment cache. Add this fragment to the end of the pending entry.
         */
        entry = ieee80211_reassemble_find(rx->sdata, frag, seq, rx->queue, hdr);
        if (!entry) {
                I802_DEBUG_INC(rx->local->rx_handlers_drop_defrag);
                return RX_DROP_MONITOR;
        }

        /* Verify that MPDUs within one MSDU have sequential PN values.
         * (IEEE 802.11i, 8.3.3.4.5) */
        if (entry->ccmp) {
                int i;
                u8 pn[CCMP_PN_LEN], *rpn;
                if (!rx->key || rx->key->conf.alg != ALG_CCMP)
                        return RX_DROP_UNUSABLE;
                memcpy(pn, entry->last_pn, CCMP_PN_LEN);
                for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
                        pn[i]++;
                        if (pn[i])
                                break;
                }
                rpn = rx->key->u.ccmp.rx_pn[rx->queue];
                if (memcmp(pn, rpn, CCMP_PN_LEN))
                        return RX_DROP_UNUSABLE;
                memcpy(entry->last_pn, pn, CCMP_PN_LEN);
        }

        skb_pull(rx->skb, ieee80211_hdrlen(fc));
        __skb_queue_tail(&entry->skb_list, rx->skb);
        entry->last_frag = frag;
        entry->extra_len += rx->skb->len;
        if (ieee80211_has_morefrags(fc)) {
                rx->skb = NULL;
                return RX_QUEUED;
        }

        rx->skb = __skb_dequeue(&entry->skb_list);
        if (skb_tailroom(rx->skb) < entry->extra_len) {
                I802_DEBUG_INC(rx->local->rx_expand_skb_head2);
                if (unlikely(pskb_expand_head(rx->skb, 0, entry->extra_len,
                                              GFP_ATOMIC))) {
                        I802_DEBUG_INC(rx->local->rx_handlers_drop_defrag);
                        __skb_queue_purge(&entry->skb_list);
                        return RX_DROP_UNUSABLE;
                }
        }
        while ((skb = __skb_dequeue(&entry->skb_list))) {
                memcpy(skb_put(rx->skb, skb->len), skb->data, skb->len);
                dev_kfree_skb(skb);
        }

        /* Complete frame has been reassembled - process it now */
        rx->flags |= IEEE80211_RX_FRAGMENTED;

 out:
        if (rx->sta)
                rx->sta->rx_packets++;
        if (is_multicast_ether_addr(hdr->addr1))
                rx->local->dot11MulticastReceivedFrameCount++;
        else
                ieee80211_led_rx(rx->local);
        return RX_CONTINUE;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_ps_poll(struct ieee80211_rx_data *rx)
{
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(rx->dev);
        struct sk_buff *skb;
        int no_pending_pkts;
        __le16 fc = ((struct ieee80211_hdr *)rx->skb->data)->frame_control;

        if (likely(!rx->sta || !ieee80211_is_pspoll(fc) ||
                   !(rx->flags & IEEE80211_RX_RA_MATCH)))
                return RX_CONTINUE;

        if ((sdata->vif.type != NL80211_IFTYPE_AP) &&
            (sdata->vif.type != NL80211_IFTYPE_AP_VLAN))
                return RX_DROP_UNUSABLE;

        skb = skb_dequeue(&rx->sta->tx_filtered);
        if (!skb) {
                skb = skb_dequeue(&rx->sta->ps_tx_buf);
                if (skb)
                        rx->local->total_ps_buffered--;
        }
        no_pending_pkts = skb_queue_empty(&rx->sta->tx_filtered) &&
                skb_queue_empty(&rx->sta->ps_tx_buf);

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

                /*
                 * Tell TX path to send one frame even though the STA may
                 * still remain is PS mode after this frame exchange.
                 */
                set_sta_flags(rx->sta, WLAN_STA_PSPOLL);

#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
                printk(KERN_DEBUG "STA %pM aid %d: PS Poll (entries after %d)\n",
                       rx->sta->sta.addr, rx->sta->sta.aid,
                       skb_queue_len(&rx->sta->ps_tx_buf));
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */

                /* Use MoreData flag to indicate whether there are more
                 * buffered frames for this STA */
                if (no_pending_pkts)
                        hdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_MOREDATA);
                else
                        hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_MOREDATA);

                dev_queue_xmit(skb);

                if (no_pending_pkts)
                        sta_info_clear_tim_bit(rx->sta);
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
        } else if (!rx->sent_ps_buffered) {
                /*
                 * FIXME: This can be the result of a race condition between
                 *        us expiring a frame and the station polling for it.
                 *        Should we send it a null-func frame indicating we
                 *        have nothing buffered for it?
                 */
                printk(KERN_DEBUG "%s: STA %pM sent PS Poll even "
                       "though there are no buffered frames for it\n",
                       rx->dev->name, rx->sta->sta.addr);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
        }

        /* Free PS Poll skb here instead of returning RX_DROP that would
         * count as an dropped frame. */
        dev_kfree_skb(rx->skb);

        return RX_QUEUED;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_remove_qos_control(struct ieee80211_rx_data *rx)
{
        u8 *data = rx->skb->data;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)data;

        if (!ieee80211_is_data_qos(hdr->frame_control))
                return RX_CONTINUE;

        /* remove the qos control field, update frame type and meta-data */
        memmove(data + IEEE80211_QOS_CTL_LEN, data,
                ieee80211_hdrlen(hdr->frame_control) - IEEE80211_QOS_CTL_LEN);
        hdr = (struct ieee80211_hdr *)skb_pull(rx->skb, IEEE80211_QOS_CTL_LEN);
        /* change frame type to non QOS */
        hdr->frame_control &= ~cpu_to_le16(IEEE80211_STYPE_QOS_DATA);

        return RX_CONTINUE;
}

static int
ieee80211_802_1x_port_control(struct ieee80211_rx_data *rx)
{
        if (unlikely(!rx->sta ||
            !test_sta_flags(rx->sta, WLAN_STA_AUTHORIZED)))
                return -EACCES;

        return 0;
}

static int
ieee80211_drop_unencrypted(struct ieee80211_rx_data *rx, __le16 fc)
{
        /*
         * Pass through unencrypted frames if the hardware has
         * decrypted them already.
         */
        if (rx->status->flag & RX_FLAG_DECRYPTED)
                return 0;

        /* Drop unencrypted frames if key is set. */
        if (unlikely(!ieee80211_has_protected(fc) &&
                     !ieee80211_is_nullfunc(fc) &&
                     (rx->key || rx->sdata->drop_unencrypted)))
                return -EACCES;

        return 0;
}

static int
ieee80211_data_to_8023(struct ieee80211_rx_data *rx)
{
        struct net_device *dev = rx->dev;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) rx->skb->data;
        u16 hdrlen, ethertype;
        u8 *payload;
        u8 dst[ETH_ALEN];
        u8 src[ETH_ALEN] __aligned(2);
        struct sk_buff *skb = rx->skb;
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);

        if (unlikely(!ieee80211_is_data_present(hdr->frame_control)))
                return -1;

        hdrlen = ieee80211_hdrlen(hdr->frame_control);

        /* convert IEEE 802.11 header + possible LLC headers into Ethernet
         * header
         * IEEE 802.11 address fields:
         * ToDS FromDS Addr1 Addr2 Addr3 Addr4
         *   0     0   DA    SA    BSSID n/a
         *   0     1   DA    BSSID SA    n/a
         *   1     0   BSSID SA    DA    n/a
         *   1     1   RA    TA    DA    SA
         */
        memcpy(dst, ieee80211_get_DA(hdr), ETH_ALEN);
        memcpy(src, ieee80211_get_SA(hdr), ETH_ALEN);

        switch (hdr->frame_control &
                cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
        case __constant_cpu_to_le16(IEEE80211_FCTL_TODS):
                if (unlikely(sdata->vif.type != NL80211_IFTYPE_AP &&
                             sdata->vif.type != NL80211_IFTYPE_AP_VLAN))
                        return -1;
                break;
        case __constant_cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS):
                if (unlikely(sdata->vif.type != NL80211_IFTYPE_WDS &&
                             sdata->vif.type != NL80211_IFTYPE_MESH_POINT))
                        return -1;
                if (ieee80211_vif_is_mesh(&sdata->vif)) {
                        struct ieee80211s_hdr *meshdr = (struct ieee80211s_hdr *)
                                (skb->data + hdrlen);
                        hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
                        if (meshdr->flags & MESH_FLAGS_AE_A5_A6) {
                                memcpy(dst, meshdr->eaddr1, ETH_ALEN);
                                memcpy(src, meshdr->eaddr2, ETH_ALEN);
                        }
                }
                break;
        case __constant_cpu_to_le16(IEEE80211_FCTL_FROMDS):
                if (sdata->vif.type != NL80211_IFTYPE_STATION ||
                    (is_multicast_ether_addr(dst) &&
                     !compare_ether_addr(src, dev->dev_addr)))
                        return -1;
                break;
        case __constant_cpu_to_le16(0):
                if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
                        return -1;
                break;
        }

        if (unlikely(skb->len - hdrlen < 8))
                return -1;

        payload = skb->data + hdrlen;
        ethertype = (payload[6] << 8) | payload[7];

        if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
                    ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
                   compare_ether_addr(payload, bridge_tunnel_header) == 0)) {
                /* remove RFC1042 or Bridge-Tunnel encapsulation and
                 * replace EtherType */
                skb_pull(skb, hdrlen + 6);
                memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
                memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
        } else {
                struct ethhdr *ehdr;
                __be16 len;

                skb_pull(skb, hdrlen);
                len = htons(skb->len);
                ehdr = (struct ethhdr *) skb_push(skb, sizeof(struct ethhdr));
                memcpy(ehdr->h_dest, dst, ETH_ALEN);
                memcpy(ehdr->h_source, src, ETH_ALEN);
                ehdr->h_proto = len;
        }
        return 0;
}

/*
 * requires that rx->skb is a frame with ethernet header
 */
static bool ieee80211_frame_allowed(struct ieee80211_rx_data *rx, __le16 fc)
{
        static const u8 pae_group_addr[ETH_ALEN] __aligned(2)
                = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x03 };
        struct ethhdr *ehdr = (struct ethhdr *) rx->skb->data;

        /*
         * Allow EAPOL frames to us/the PAE group address regardless
         * of whether the frame was encrypted or not.
         */
        if (ehdr->h_proto == htons(ETH_P_PAE) &&
            (compare_ether_addr(ehdr->h_dest, rx->dev->dev_addr) == 0 ||
             compare_ether_addr(ehdr->h_dest, pae_group_addr) == 0))
                return true;

        if (ieee80211_802_1x_port_control(rx) ||
            ieee80211_drop_unencrypted(rx, fc))
                return false;

        return true;
}

/*
 * requires that rx->skb is a frame with ethernet header
 */
static void
ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
{
        struct net_device *dev = rx->dev;
        struct ieee80211_local *local = rx->local;
        struct sk_buff *skb, *xmit_skb;
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
        struct ethhdr *ehdr = (struct ethhdr *) rx->skb->data;
        struct sta_info *dsta;

        skb = rx->skb;
        xmit_skb = NULL;

        if ((sdata->vif.type == NL80211_IFTYPE_AP ||
             sdata->vif.type == NL80211_IFTYPE_AP_VLAN) &&
            !(sdata->flags & IEEE80211_SDATA_DONT_BRIDGE_PACKETS) &&
            (rx->flags & IEEE80211_RX_RA_MATCH)) {
                if (is_multicast_ether_addr(ehdr->h_dest)) {
                        /*
                         * send multicast frames both to higher layers in
                         * local net stack and back to the wireless medium
                         */
                        xmit_skb = skb_copy(skb, GFP_ATOMIC);
                        if (!xmit_skb && net_ratelimit())
                                printk(KERN_DEBUG "%s: failed to clone "
                                       "multicast frame\n", dev->name);
                } else {
                        dsta = sta_info_get(local, skb->data);
                        if (dsta && dsta->sdata->dev == dev) {
                                /*
                                 * The destination station is associated to
                                 * this AP (in this VLAN), so send the frame
                                 * directly to it and do not pass it to local
                                 * net stack.
                                 */
                                xmit_skb = skb;
                                skb = NULL;
                        }
                }
        }

        if (skb) {
                /* deliver to local stack */
                skb->protocol = eth_type_trans(skb, dev);
                memset(skb->cb, 0, sizeof(skb->cb));
                netif_rx(skb);
        }

        if (xmit_skb) {
                /* send to wireless media */
                xmit_skb->protocol = htons(ETH_P_802_3);
                skb_reset_network_header(xmit_skb);
                skb_reset_mac_header(xmit_skb);
                dev_queue_xmit(xmit_skb);
        }
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_amsdu(struct ieee80211_rx_data *rx)
{
        struct net_device *dev = rx->dev;
        struct ieee80211_local *local = rx->local;
        u16 ethertype;
        u8 *payload;
        struct sk_buff *skb = rx->skb, *frame = NULL;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        __le16 fc = hdr->frame_control;
        const struct ethhdr *eth;
        int remaining, err;
        u8 dst[ETH_ALEN];
        u8 src[ETH_ALEN];

        if (unlikely(!ieee80211_is_data(fc)))
                return RX_CONTINUE;

        if (unlikely(!ieee80211_is_data_present(fc)))
                return RX_DROP_MONITOR;

        if (!(rx->flags & IEEE80211_RX_AMSDU))
                return RX_CONTINUE;

        err = ieee80211_data_to_8023(rx);
        if (unlikely(err))
                return RX_DROP_UNUSABLE;

        skb->dev = dev;

        dev->stats.rx_packets++;
        dev->stats.rx_bytes += skb->len;

        /* skip the wrapping header */
        eth = (struct ethhdr *) skb_pull(skb, sizeof(struct ethhdr));
        if (!eth)
                return RX_DROP_UNUSABLE;

        while (skb != frame) {
                u8 padding;
                __be16 len = eth->h_proto;
                unsigned int subframe_len = sizeof(struct ethhdr) + ntohs(len);

                remaining = skb->len;
                memcpy(dst, eth->h_dest, ETH_ALEN);
                memcpy(src, eth->h_source, ETH_ALEN);

                padding = ((4 - subframe_len) & 0x3);
                /* the last MSDU has no padding */
                if (subframe_len > remaining)
                        return RX_DROP_UNUSABLE;

                skb_pull(skb, sizeof(struct ethhdr));
                /* if last subframe reuse skb */
                if (remaining <= subframe_len + padding)
                        frame = skb;
                else {
                        frame = dev_alloc_skb(local->hw.extra_tx_headroom +
                                              subframe_len);

                        if (frame == NULL)
                                return RX_DROP_UNUSABLE;

                        skb_reserve(frame, local->hw.extra_tx_headroom +
                                    sizeof(struct ethhdr));
                        memcpy(skb_put(frame, ntohs(len)), skb->data,
                                ntohs(len));

                        eth = (struct ethhdr *) skb_pull(skb, ntohs(len) +
                                                        padding);
                        if (!eth) {
                                dev_kfree_skb(frame);
                                return RX_DROP_UNUSABLE;
                        }
                }

                skb_reset_network_header(frame);
                frame->dev = dev;
                frame->priority = skb->priority;
                rx->skb = frame;

                payload = frame->data;
                ethertype = (payload[6] << 8) | payload[7];

                if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
                            ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
                           compare_ether_addr(payload,
                                              bridge_tunnel_header) == 0)) {
                        /* remove RFC1042 or Bridge-Tunnel
                         * encapsulation and replace EtherType */
                        skb_pull(frame, 6);
                        memcpy(skb_push(frame, ETH_ALEN), src, ETH_ALEN);
                        memcpy(skb_push(frame, ETH_ALEN), dst, ETH_ALEN);
                } else {
                        memcpy(skb_push(frame, sizeof(__be16)),
                               &len, sizeof(__be16));
                        memcpy(skb_push(frame, ETH_ALEN), src, ETH_ALEN);
                        memcpy(skb_push(frame, ETH_ALEN), dst, ETH_ALEN);
                }

                if (!ieee80211_frame_allowed(rx, fc)) {
                        if (skb == frame) /* last frame */
                                return RX_DROP_UNUSABLE;
                        dev_kfree_skb(frame);
                        continue;
                }

                ieee80211_deliver_skb(rx);
        }

        return RX_QUEUED;
}

#ifdef CONFIG_MAC80211_MESH
static ieee80211_rx_result
ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
{
        struct ieee80211_hdr *hdr;
        struct ieee80211s_hdr *mesh_hdr;
        unsigned int hdrlen;
        struct sk_buff *skb = rx->skb, *fwd_skb;

        hdr = (struct ieee80211_hdr *) skb->data;
        hdrlen = ieee80211_hdrlen(hdr->frame_control);
        mesh_hdr = (struct ieee80211s_hdr *) (skb->data + hdrlen);

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

        if (!mesh_hdr->ttl)
                /* illegal frame */
                return RX_DROP_MONITOR;

        if (mesh_hdr->flags & MESH_FLAGS_AE_A5_A6){
                struct ieee80211_sub_if_data *sdata;
                struct mesh_path *mppath;

                sdata = IEEE80211_DEV_TO_SUB_IF(rx->dev);
                rcu_read_lock();
                mppath = mpp_path_lookup(mesh_hdr->eaddr2, sdata);
                if (!mppath) {
                        mpp_path_add(mesh_hdr->eaddr2, hdr->addr4, sdata);
                } else {
                        spin_lock_bh(&mppath->state_lock);
                        mppath->exp_time = jiffies;
                        if (compare_ether_addr(mppath->mpp, hdr->addr4) != 0)
                                memcpy(mppath->mpp, hdr->addr4, ETH_ALEN);
                        spin_unlock_bh(&mppath->state_lock);
                }
                rcu_read_unlock();
        }

        if (compare_ether_addr(rx->dev->dev_addr, hdr->addr3) == 0)
                return RX_CONTINUE;

        mesh_hdr->ttl--;

        if (rx->flags & IEEE80211_RX_RA_MATCH) {
                if (!mesh_hdr->ttl)
                        IEEE80211_IFSTA_MESH_CTR_INC(&rx->sdata->u.mesh,
                                                     dropped_frames_ttl);
                else {
                        struct ieee80211_hdr *fwd_hdr;
                        fwd_skb = skb_copy(skb, GFP_ATOMIC);

                        if (!fwd_skb && net_ratelimit())
                                printk(KERN_DEBUG "%s: failed to clone mesh frame\n",
                                                   rx->dev->name);

                        fwd_hdr =  (struct ieee80211_hdr *) fwd_skb->data;
                        /*
                         * Save TA to addr1 to send TA a path error if a
                         * suitable next hop is not found
                         */
                        memcpy(fwd_hdr->addr1, fwd_hdr->addr2, ETH_ALEN);
                        memcpy(fwd_hdr->addr2, rx->dev->dev_addr, ETH_ALEN);
                        fwd_skb->dev = rx->local->mdev;
                        fwd_skb->iif = rx->dev->ifindex;
                        dev_queue_xmit(fwd_skb);
                }
        }

        if (is_multicast_ether_addr(hdr->addr3) ||
            rx->dev->flags & IFF_PROMISC)
                return RX_CONTINUE;
        else
                return RX_DROP_MONITOR;
}
#endif

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_data(struct ieee80211_rx_data *rx)
{
        struct net_device *dev = rx->dev;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
        __le16 fc = hdr->frame_control;
        int err;

        if (unlikely(!ieee80211_is_data(hdr->frame_control)))
                return RX_CONTINUE;

        if (unlikely(!ieee80211_is_data_present(hdr->frame_control)))
                return RX_DROP_MONITOR;

        err = ieee80211_data_to_8023(rx);
        if (unlikely(err))
                return RX_DROP_UNUSABLE;

        if (!ieee80211_frame_allowed(rx, fc))
                return RX_DROP_MONITOR;

        rx->skb->dev = dev;

        dev->stats.rx_packets++;
        dev->stats.rx_bytes += rx->skb->len;

        ieee80211_deliver_skb(rx);

        return RX_QUEUED;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_ctrl(struct ieee80211_rx_data *rx)
{
        struct ieee80211_local *local = rx->local;
        struct ieee80211_hw *hw = &local->hw;
        struct sk_buff *skb = rx->skb;
        struct ieee80211_bar *bar = (struct ieee80211_bar *)skb->data;
        struct tid_ampdu_rx *tid_agg_rx;
        u16 start_seq_num;
        u16 tid;

        if (likely(!ieee80211_is_ctl(bar->frame_control)))
                return RX_CONTINUE;

        if (ieee80211_is_back_req(bar->frame_control)) {
                if (!rx->sta)
                        return RX_CONTINUE;
                tid = le16_to_cpu(bar->control) >> 12;
                if (rx->sta->ampdu_mlme.tid_state_rx[tid]
                                        != HT_AGG_STATE_OPERATIONAL)
                        return RX_CONTINUE;
                tid_agg_rx = rx->sta->ampdu_mlme.tid_rx[tid];

                start_seq_num = le16_to_cpu(bar->start_seq_num) >> 4;

                /* reset session timer */
                if (tid_agg_rx->timeout) {
                        unsigned long expires =
                                jiffies + (tid_agg_rx->timeout / 1000) * HZ;
                        mod_timer(&tid_agg_rx->session_timer, expires);
                }

                /* manage reordering buffer according to requested */
                /* sequence number */
                rcu_read_lock();
                ieee80211_sta_manage_reorder_buf(hw, tid_agg_rx, NULL,
                                                 start_seq_num, 1);
                rcu_read_unlock();
                return RX_DROP_UNUSABLE;
        }

        return RX_CONTINUE;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_action(struct ieee80211_rx_data *rx)
{
        struct ieee80211_local *local = rx->local;
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(rx->dev);
        struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
        int len = rx->skb->len;

        if (!ieee80211_is_action(mgmt->frame_control))
                return RX_CONTINUE;

        if (!rx->sta)
                return RX_DROP_MONITOR;

        if (!(rx->flags & IEEE80211_RX_RA_MATCH))
                return RX_DROP_MONITOR;

        /* all categories we currently handle have action_code */
        if (len < IEEE80211_MIN_ACTION_SIZE + 1)
                return RX_DROP_MONITOR;

        switch (mgmt->u.action.category) {
        case WLAN_CATEGORY_BACK:
                switch (mgmt->u.action.u.addba_req.action_code) {
                case WLAN_ACTION_ADDBA_REQ:
                        if (len < (IEEE80211_MIN_ACTION_SIZE +
                                   sizeof(mgmt->u.action.u.addba_req)))
                                return RX_DROP_MONITOR;
                        ieee80211_process_addba_request(local, rx->sta, mgmt, len);
                        break;
                case WLAN_ACTION_ADDBA_RESP:
                        if (len < (IEEE80211_MIN_ACTION_SIZE +
                                   sizeof(mgmt->u.action.u.addba_resp)))
                                return RX_DROP_MONITOR;
                        ieee80211_process_addba_resp(local, rx->sta, mgmt, len);
                        break;
                case WLAN_ACTION_DELBA:
                        if (len < (IEEE80211_MIN_ACTION_SIZE +
                                   sizeof(mgmt->u.action.u.delba)))
                                return RX_DROP_MONITOR;
                        ieee80211_process_delba(sdata, rx->sta, mgmt, len);
                        break;
                }
                break;
        case WLAN_CATEGORY_SPECTRUM_MGMT:
                if (local->hw.conf.channel->band != IEEE80211_BAND_5GHZ)
                        return RX_DROP_MONITOR;
                switch (mgmt->u.action.u.measurement.action_code) {
                case WLAN_ACTION_SPCT_MSR_REQ:
                        if (len < (IEEE80211_MIN_ACTION_SIZE +
                                   sizeof(mgmt->u.action.u.measurement)))
                                return RX_DROP_MONITOR;
                        ieee80211_process_measurement_req(sdata, mgmt, len);
                        break;
                }
                break;
        default:
                return RX_CONTINUE;
        }

        rx->sta->rx_packets++;
        dev_kfree_skb(rx->skb);
        return RX_QUEUED;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_mgmt(struct ieee80211_rx_data *rx)
{
        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(rx->dev);

        if (!(rx->flags & IEEE80211_RX_RA_MATCH))
                return RX_DROP_MONITOR;

        if (ieee80211_vif_is_mesh(&sdata->vif))
                return ieee80211_mesh_rx_mgmt(sdata, rx->skb, rx->status);

        if (sdata->vif.type != NL80211_IFTYPE_STATION &&
            sdata->vif.type != NL80211_IFTYPE_ADHOC)
                return RX_DROP_MONITOR;

        if (sdata->flags & IEEE80211_SDATA_USERSPACE_MLME)
                return RX_DROP_MONITOR;

        ieee80211_sta_rx_mgmt(sdata, rx->skb, rx->status);
        return RX_QUEUED;
}

static void ieee80211_rx_michael_mic_report(struct net_device *dev,
                                            struct ieee80211_hdr *hdr,
                                            struct ieee80211_rx_data *rx)
{
        int keyidx;
        unsigned int hdrlen;

        hdrlen = ieee80211_hdrlen(hdr->frame_control);
        if (rx->skb->len >= hdrlen + 4)
                keyidx = rx->skb->data[hdrlen + 3] >> 6;
        else
                keyidx = -1;

        if (!rx->sta) {
                /*
                 * Some hardware seem to generate incorrect Michael MIC
                 * reports; ignore them to avoid triggering countermeasures.
                 */
                goto ignore;
        }

        if (!ieee80211_has_protected(hdr->frame_control))
                goto ignore;

        if (rx->sdata->vif.type == NL80211_IFTYPE_AP && keyidx) {
                /*
                 * APs with pairwise keys should never receive Michael MIC
                 * errors for non-zero keyidx because these are reserved for
                 * group keys and only the AP is sending real multicast
                 * frames in the BSS.
                 */
                goto ignore;
        }

        if (!ieee80211_is_data(hdr->frame_control) &&
            !ieee80211_is_auth(hdr->frame_control))
                goto ignore;

        mac80211_ev_michael_mic_failure(rx->sdata, keyidx, hdr);
 ignore:
        dev_kfree_skb(rx->skb);
        rx->skb = NULL;
}

/* TODO: use IEEE80211_RX_FRAGMENTED */
static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx)
{
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_local *local = rx->local;
        struct ieee80211_rtap_hdr {
                struct ieee80211_radiotap_header hdr;
                u8 flags;
                u8 rate;
                __le16 chan_freq;
                __le16 chan_flags;
        } __attribute__ ((packed)) *rthdr;
        struct sk_buff *skb = rx->skb, *skb2;
        struct net_device *prev_dev = NULL;
        struct ieee80211_rx_status *status = rx->status;

        if (rx->flags & IEEE80211_RX_CMNTR_REPORTED)
                goto out_free_skb;

        if (skb_headroom(skb) < sizeof(*rthdr) &&
            pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC))
                goto out_free_skb;

        rthdr = (void *)skb_push(skb, sizeof(*rthdr));
        memset(rthdr, 0, sizeof(*rthdr));
        rthdr->hdr.it_len = cpu_to_le16(sizeof(*rthdr));
        rthdr->hdr.it_present =
                cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
                            (1 << IEEE80211_RADIOTAP_RATE) |
                            (1 << IEEE80211_RADIOTAP_CHANNEL));

        rthdr->rate = rx->rate->bitrate / 5;
        rthdr->chan_freq = cpu_to_le16(status->freq);

        if (status->band == IEEE80211_BAND_5GHZ)
                rthdr->chan_flags = cpu_to_le16(IEEE80211_CHAN_OFDM |
                                                IEEE80211_CHAN_5GHZ);
        else
                rthdr->chan_flags = cpu_to_le16(IEEE80211_CHAN_DYN |
                                                IEEE80211_CHAN_2GHZ);

        skb_set_mac_header(skb, 0);
        skb->ip_summed = CHECKSUM_UNNECESSARY;
        skb->pkt_type = PACKET_OTHERHOST;
        skb->protocol = htons(ETH_P_802_2);

        list_for_each_entry_rcu(sdata, &local->interfaces, list) {
                if (!netif_running(sdata->dev))
                        continue;

                if (sdata->vif.type != NL80211_IFTYPE_MONITOR ||
                    !(sdata->u.mntr_flags & MONITOR_FLAG_COOK_FRAMES))
                        continue;

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

                prev_dev = sdata->dev;
                sdata->dev->stats.rx_packets++;
                sdata->dev->stats.rx_bytes += skb->len;
        }

        if (prev_dev) {
                skb->dev = prev_dev;
                netif_rx(skb);
                skb = NULL;
        } else
                goto out_free_skb;

        rx->flags |= IEEE80211_RX_CMNTR_REPORTED;
        return;

 out_free_skb:
        dev_kfree_skb(skb);
}


static void ieee80211_invoke_rx_handlers(struct ieee80211_sub_if_data *sdata,
                                         struct ieee80211_rx_data *rx,
                                         struct sk_buff *skb)
{
        ieee80211_rx_result res = RX_DROP_MONITOR;

        rx->skb = skb;
        rx->sdata = sdata;
        rx->dev = sdata->dev;

#define CALL_RXH(rxh)                   \
        do {                            \
                res = rxh(rx);          \
                if (res != RX_CONTINUE) \
                        goto rxh_done;  \
        } while (0);

        CALL_RXH(ieee80211_rx_h_passive_scan)
        CALL_RXH(ieee80211_rx_h_check)
        CALL_RXH(ieee80211_rx_h_decrypt)
        CALL_RXH(ieee80211_rx_h_sta_process)
        CALL_RXH(ieee80211_rx_h_defragment)
        CALL_RXH(ieee80211_rx_h_ps_poll)
        CALL_RXH(ieee80211_rx_h_michael_mic_verify)
        /* must be after MMIC verify so header is counted in MPDU mic */
        CALL_RXH(ieee80211_rx_h_remove_qos_control)
        CALL_RXH(ieee80211_rx_h_amsdu)
#ifdef CONFIG_MAC80211_MESH
        if (ieee80211_vif_is_mesh(&sdata->vif))
                CALL_RXH(ieee80211_rx_h_mesh_fwding);
#endif
        CALL_RXH(ieee80211_rx_h_data)
        CALL_RXH(ieee80211_rx_h_ctrl)
        CALL_RXH(ieee80211_rx_h_action)
        CALL_RXH(ieee80211_rx_h_mgmt)

#undef CALL_RXH

 rxh_done:
        switch (res) {
        case RX_DROP_MONITOR:
                I802_DEBUG_INC(sdata->local->rx_handlers_drop);
                if (rx->sta)
                        rx->sta->rx_dropped++;
                /* fall through */
        case RX_CONTINUE:
                ieee80211_rx_cooked_monitor(rx);
                break;
        case RX_DROP_UNUSABLE:
                I802_DEBUG_INC(sdata->local->rx_handlers_drop);
                if (rx->sta)
                        rx->sta->rx_dropped++;
                dev_kfree_skb(rx->skb);
                break;
        case RX_QUEUED:
                I802_DEBUG_INC(sdata->local->rx_handlers_queued);
                break;
        }
}

/* main receive path */

static int prepare_for_handlers(struct ieee80211_sub_if_data *sdata,
                                u8 *bssid, struct ieee80211_rx_data *rx,
                                struct ieee80211_hdr *hdr)
{
        int multicast = is_multicast_ether_addr(hdr->addr1);

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_STATION:
                if (!bssid)
                        return 0;
                if (!ieee80211_bssid_match(bssid, sdata->u.sta.bssid)) {
                        if (!(rx->flags & IEEE80211_RX_IN_SCAN))
                                return 0;
                        rx->flags &= ~IEEE80211_RX_RA_MATCH;
                } else if (!multicast &&
                           compare_ether_addr(sdata->dev->dev_addr,
                                              hdr->addr1) != 0) {
                        if (!(sdata->dev->flags & IFF_PROMISC))
                                return 0;
                        rx->flags &= ~IEEE80211_RX_RA_MATCH;
                }
                break;
        case NL80211_IFTYPE_ADHOC:
                if (!bssid)
                        return 0;
                if (ieee80211_is_beacon(hdr->frame_control)) {
                        return 1;
                }
                else if (!ieee80211_bssid_match(bssid, sdata->u.sta.bssid)) {
                        if (!(rx->flags & IEEE80211_RX_IN_SCAN))
                                return 0;
                        rx->flags &= ~IEEE80211_RX_RA_MATCH;
                } else if (!multicast &&
                           compare_ether_addr(sdata->dev->dev_addr,
                                              hdr->addr1) != 0) {
                        if (!(sdata->dev->flags & IFF_PROMISC))
                                return 0;
                        rx->flags &= ~IEEE80211_RX_RA_MATCH;
                } else if (!rx->sta)
                        rx->sta = ieee80211_ibss_add_sta(sdata, rx->skb,
                                                bssid, hdr->addr2,
                                                BIT(rx->status->rate_idx));
                break;
        case NL80211_IFTYPE_MESH_POINT:
                if (!multicast &&
                    compare_ether_addr(sdata->dev->dev_addr,
                                       hdr->addr1) != 0) {
                        if (!(sdata->dev->flags & IFF_PROMISC))
                                return 0;

                        rx->flags &= ~IEEE80211_RX_RA_MATCH;
                }
                break;
        case NL80211_IFTYPE_AP_VLAN:
        case NL80211_IFTYPE_AP:
                if (!bssid) {
                        if (compare_ether_addr(sdata->dev->dev_addr,
                                               hdr->addr1))
                                return 0;
                } else if (!ieee80211_bssid_match(bssid,
                                        sdata->dev->dev_addr)) {
                        if (!(rx->flags & IEEE80211_RX_IN_SCAN))
                                return 0;
                        rx->flags &= ~IEEE80211_RX_RA_MATCH;
                }
                break;
        case NL80211_IFTYPE_WDS:
                if (bssid || !ieee80211_is_data(hdr->frame_control))
                        return 0;
                if (compare_ether_addr(sdata->u.wds.remote_addr, hdr->addr2))
                        return 0;
                break;
        case NL80211_IFTYPE_MONITOR:
                /* take everything */
                break;
        case NL80211_IFTYPE_UNSPECIFIED:
        case __NL80211_IFTYPE_AFTER_LAST:
                /* should never get here */
                WARN_ON(1);
                break;
        }

        return 1;
}

/*
 * This is the actual Rx frames handler. as it blongs to Rx path it must
 * be called with rcu_read_lock protection.
 */
static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
                                         struct sk_buff *skb,
                                         struct ieee80211_rx_status *status,
                                         struct ieee80211_rate *rate)
{
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_hdr *hdr;
        struct ieee80211_rx_data rx;
        int prepares;
        struct ieee80211_sub_if_data *prev = NULL;
        struct sk_buff *skb_new;
        u8 *bssid;

        hdr = (struct ieee80211_hdr *)skb->data;
        memset(&rx, 0, sizeof(rx));
        rx.skb = skb;
        rx.local = local;

        rx.status = status;
        rx.rate = rate;

        if (ieee80211_is_data(hdr->frame_control) || ieee80211_is_mgmt(hdr->frame_control))
                local->dot11ReceivedFragmentCount++;

        rx.sta = sta_info_get(local, hdr->addr2);
        if (rx.sta) {
                rx.sdata = rx.sta->sdata;
                rx.dev = rx.sta->sdata->dev;
        }

        if ((status->flag & RX_FLAG_MMIC_ERROR)) {
                ieee80211_rx_michael_mic_report(local->mdev, hdr, &rx);
                return;
        }

        if (unlikely(local->sw_scanning || local->hw_scanning))
                rx.flags |= IEEE80211_RX_IN_SCAN;

        ieee80211_parse_qos(&rx);
        ieee80211_verify_ip_alignment(&rx);

        skb = rx.skb;

        list_for_each_entry_rcu(sdata, &local->interfaces, list) {
                if (!netif_running(sdata->dev))
                        continue;

                if (sdata->vif.type == NL80211_IFTYPE_MONITOR)
                        continue;

                bssid = ieee80211_get_bssid(hdr, skb->len, sdata->vif.type);
                rx.flags |= IEEE80211_RX_RA_MATCH;
                prepares = prepare_for_handlers(sdata, bssid, &rx, hdr);

                if (!prepares)
                        continue;

                /*
                 * frame is destined for this interface, but if it's not
                 * also for the previous one we handle that after the
                 * loop to avoid copying the SKB once too much
                 */

                if (!prev) {
                        prev = sdata;
                        continue;
                }

                /*
                 * frame was destined for the previous interface
                 * so invoke RX handlers for it
                 */

                skb_new = skb_copy(skb, GFP_ATOMIC);
                if (!skb_new) {
                        if (net_ratelimit())
                                printk(KERN_DEBUG "%s: failed to copy "
                                       "multicast frame for %s\n",
                                       wiphy_name(local->hw.wiphy),
                                       prev->dev->name);
                        continue;
                }
                ieee80211_invoke_rx_handlers(prev, &rx, skb_new);
                prev = sdata;
        }
        if (prev)
                ieee80211_invoke_rx_handlers(prev, &rx, skb);
        else
                dev_kfree_skb(skb);
}

#define SEQ_MODULO 0x1000
#define SEQ_MASK   0xfff

static inline int seq_less(u16 sq1, u16 sq2)
{
        return ((sq1 - sq2) & SEQ_MASK) > (SEQ_MODULO >> 1);
}

static inline u16 seq_inc(u16 sq)
{
        return (sq + 1) & SEQ_MASK;
}

static inline u16 seq_sub(u16 sq1, u16 sq2)
{
        return (sq1 - sq2) & SEQ_MASK;
}


/*
 * As it function blongs to Rx path it must be called with
 * the proper rcu_read_lock protection for its flow.
 */
static u8 ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw,
                                           struct tid_ampdu_rx *tid_agg_rx,
                                           struct sk_buff *skb,
                                           u16 mpdu_seq_num,
                                           int bar_req)
{
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_rx_status status;
        u16 head_seq_num, buf_size;
        int index;
        struct ieee80211_supported_band *sband;
        struct ieee80211_rate *rate;

        buf_size = tid_agg_rx->buf_size;
        head_seq_num = tid_agg_rx->head_seq_num;

        /* frame with out of date sequence number */
        if (seq_less(mpdu_seq_num, head_seq_num)) {
                dev_kfree_skb(skb);
                return 1;
        }

        /* if frame sequence number exceeds our buffering window size or
         * block Ack Request arrived - release stored frames */
        if ((!seq_less(mpdu_seq_num, head_seq_num + buf_size)) || (bar_req)) {
                /* new head to the ordering buffer */
                if (bar_req)
                        head_seq_num = mpdu_seq_num;
                else
                        head_seq_num =
                                seq_inc(seq_sub(mpdu_seq_num, buf_size));
                /* release stored frames up to new head to stack */
                while (seq_less(tid_agg_rx->head_seq_num, head_seq_num)) {
                        index = seq_sub(tid_agg_rx->head_seq_num,
                                tid_agg_rx->ssn)
                                % tid_agg_rx->buf_size;

                        if (tid_agg_rx->reorder_buf[index]) {
                                /* release the reordered frames to stack */
                                memcpy(&status,
                                        tid_agg_rx->reorder_buf[index]->cb,
                                        sizeof(status));
                                sband = local->hw.wiphy->bands[status.band];
                                rate = &sband->bitrates[status.rate_idx];
                                __ieee80211_rx_handle_packet(hw,
                                        tid_agg_rx->reorder_buf[index],
                                        &status, rate);
                                tid_agg_rx->stored_mpdu_num--;
                                tid_agg_rx->reorder_buf[index] = NULL;
                        }
                        tid_agg_rx->head_seq_num =
                                seq_inc(tid_agg_rx->head_seq_num);
                }
                if (bar_req)
                        return 1;
        }

        /* now the new frame is always in the range of the reordering */
        /* buffer window */
        index = seq_sub(mpdu_seq_num, tid_agg_rx->ssn)
                                % tid_agg_rx->buf_size;
        /* check if we already stored this frame */
        if (tid_agg_rx->reorder_buf[index]) {
                dev_kfree_skb(skb);
                return 1;
        }

        /* if arrived mpdu is in the right order and nothing else stored */
        /* release it immediately */
        if (mpdu_seq_num == tid_agg_rx->head_seq_num &&
                        tid_agg_rx->stored_mpdu_num == 0) {
                tid_agg_rx->head_seq_num =
                        seq_inc(tid_agg_rx->head_seq_num);
                return 0;
        }

        /* put the frame in the reordering buffer */
        tid_agg_rx->reorder_buf[index] = skb;
        tid_agg_rx->stored_mpdu_num++;
        /* release the buffer until next missing frame */
        index = seq_sub(tid_agg_rx->head_seq_num, tid_agg_rx->ssn)
                                                % tid_agg_rx->buf_size;
        while (tid_agg_rx->reorder_buf[index]) {
                /* release the reordered frame back to stack */
                memcpy(&status, tid_agg_rx->reorder_buf[index]->cb,
                        sizeof(status));
                sband = local->hw.wiphy->bands[status.band];
                rate = &sband->bitrates[status.rate_idx];
                __ieee80211_rx_handle_packet(hw, tid_agg_rx->reorder_buf[index],
                                             &status, rate);
                tid_agg_rx->stored_mpdu_num--;
                tid_agg_rx->reorder_buf[index] = NULL;
                tid_agg_rx->head_seq_num = seq_inc(tid_agg_rx->head_seq_num);
                index = seq_sub(tid_agg_rx->head_seq_num,
                        tid_agg_rx->ssn) % tid_agg_rx->buf_size;
        }
        return 1;
}

static u8 ieee80211_rx_reorder_ampdu(struct ieee80211_local *local,
                                     struct sk_buff *skb)
{
        struct ieee80211_hw *hw = &local->hw;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        struct sta_info *sta;
        struct tid_ampdu_rx *tid_agg_rx;
        u16 sc;
        u16 mpdu_seq_num;
        u8 ret = 0;
        int tid;

        sta = sta_info_get(local, hdr->addr2);
        if (!sta)
                return ret;

        /* filter the QoS data rx stream according to
         * STA/TID and check if this STA/TID is on aggregation */
        if (!ieee80211_is_data_qos(hdr->frame_control))
                goto end_reorder;

        tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;

        if (sta->ampdu_mlme.tid_state_rx[tid] != HT_AGG_STATE_OPERATIONAL)
                goto end_reorder;

        tid_agg_rx = sta->ampdu_mlme.tid_rx[tid];

        /* qos null data frames are excluded */
        if (unlikely(hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_NULLFUNC)))
                goto end_reorder;

        /* new un-ordered ampdu frame - process it */

        /* reset session timer */
        if (tid_agg_rx->timeout) {
                unsigned long expires =
                        jiffies + (tid_agg_rx->timeout / 1000) * HZ;
                mod_timer(&tid_agg_rx->session_timer, expires);
        }

        /* if this mpdu is fragmented - terminate rx aggregation session */
        sc = le16_to_cpu(hdr->seq_ctrl);
        if (sc & IEEE80211_SCTL_FRAG) {
                ieee80211_sta_stop_rx_ba_session(sta->sdata, sta->sta.addr,
                        tid, 0, WLAN_REASON_QSTA_REQUIRE_SETUP);
                ret = 1;
                goto end_reorder;
        }

        /* according to mpdu sequence number deal with reordering buffer */
        mpdu_seq_num = (sc & IEEE80211_SCTL_SEQ) >> 4;
        ret = ieee80211_sta_manage_reorder_buf(hw, tid_agg_rx, skb,
                                                mpdu_seq_num, 0);
 end_reorder:
        return ret;
}

/*
 * This is the receive path handler. It is called by a low level driver when an
 * 802.11 MPDU is received from the hardware.
 */
void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
                    struct ieee80211_rx_status *status)
{
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_rate *rate = NULL;
        struct ieee80211_supported_band *sband;

        if (status->band < 0 ||
            status->band >= IEEE80211_NUM_BANDS) {
                WARN_ON(1);
                return;
        }

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

        if (!sband ||
            status->rate_idx < 0 ||
            status->rate_idx >= sband->n_bitrates) {
                WARN_ON(1);
                return;
        }

        rate = &sband->bitrates[status->rate_idx];

        /*
         * key references and virtual interfaces are protected using RCU
         * and this requires that we are in a read-side RCU section during
         * receive processing
         */
        rcu_read_lock();

        /*
         * Frames with failed FCS/PLCP checksum are not returned,
         * all other frames are returned without radiotap header
         * if it was previously present.
         * Also, frames with less than 16 bytes are dropped.
         */
        skb = ieee80211_rx_monitor(local, skb, status, rate);
        if (!skb) {
                rcu_read_unlock();
                return;
        }

        if (!ieee80211_rx_reorder_ampdu(local, skb))
                __ieee80211_rx_handle_packet(hw, skb, status, rate);

        rcu_read_unlock();
}
EXPORT_SYMBOL(__ieee80211_rx);

/* This is a version of the rx handler that can be called from hard irq
 * context. Post the skb on the queue and schedule the tasklet */
void ieee80211_rx_irqsafe(struct ieee80211_hw *hw, struct sk_buff *skb,
                          struct ieee80211_rx_status *status)
{
        struct ieee80211_local *local = hw_to_local(hw);

        BUILD_BUG_ON(sizeof(struct ieee80211_rx_status) > sizeof(skb->cb));

        skb->dev = local->mdev;
        /* copy status into skb->cb for use by tasklet */
        memcpy(skb->cb, status, sizeof(*status));
        skb->pkt_type = IEEE80211_RX_MSG;
        skb_queue_tail(&local->skb_queue, skb);
        tasklet_schedule(&local->tasklet);
}
EXPORT_SYMBOL(ieee80211_rx_irqsafe);