mac80211: serialize rx path workers

[deliverable/linux.git] / 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 2007-2010  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/jiffies.h>
#include <linux/slab.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 "driver-ops.h"
#include "led.h"
#include "mesh.h"
#include "wep.h"
#include "wpa.h"
#include "tkip.h"
#include "wme.h"

/*
 * 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)
{
        if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) {
                if (likely(skb->len > FCS_LEN))
                        __pskb_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 sk_buff *skb,
                                    int present_fcs_len)
{
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
        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))
                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_DBM)
                len += 1;

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

        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_rate *rate,
                                 int rtap_len)
{
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
        struct ieee80211_radiotap_header *rthdr;
        unsigned char *pos;
        u16 rx_flags = 0;

        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_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) {
                put_unaligned_le64(status->mactime, pos);
                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_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
                *pos |= IEEE80211_RADIOTAP_F_BADFCS;
        if (status->flag & RX_FLAG_SHORTPRE)
                *pos |= IEEE80211_RADIOTAP_F_SHORTPRE;
        pos++;

        /* IEEE80211_RADIOTAP_RATE */
        if (status->flag & RX_FLAG_HT) {
                /*
                 * TODO: add following information into radiotap header once
                 * suitable fields are defined for it:
                 * - MCS index (status->rate_idx)
                 * - HT40 (status->flag & RX_FLAG_40MHZ)
                 * - short-GI (status->flag & RX_FLAG_SHORT_GI)
                 */
                *pos = 0;
        } else {
                rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_RATE);
                *pos = rate->bitrate / 5;
        }
        pos++;

        /* IEEE80211_RADIOTAP_CHANNEL */
        put_unaligned_le16(status->freq, pos);
        pos += 2;
        if (status->band == IEEE80211_BAND_5GHZ)
                put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ,
                                   pos);
        else if (status->flag & RX_FLAG_HT)
                put_unaligned_le16(IEEE80211_CHAN_DYN | IEEE80211_CHAN_2GHZ,
                                   pos);
        else if (rate->flags & IEEE80211_RATE_ERP_G)
                put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ,
                                   pos);
        else
                put_unaligned_le16(IEEE80211_CHAN_CCK | IEEE80211_CHAN_2GHZ,
                                   pos);
        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_LOCK_QUALITY is missing */

        /* IEEE80211_RADIOTAP_ANTENNA */
        *pos = status->antenna;
        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 - (u8 *)rthdr) & 1)
                pos++;
        if (status->flag & RX_FLAG_FAILED_PLCP_CRC)
                rx_flags |= IEEE80211_RADIOTAP_F_RX_BADPLCP;
        put_unaligned_le16(rx_flags, pos);
        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_rate *rate)
{
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(origskb);
        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;

        /*
         * 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.
         */

        /* 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;

        /* make sure hdr->frame_control is on the linear part */
        if (!pskb_may_pull(origskb, 2)) {
                dev_kfree_skb(origskb);
                return NULL;
        }

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

                return remove_monitor_info(local, origskb);
        }

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

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

                origskb = remove_monitor_info(local, origskb);

                if (!skb)
                        return origskb;
        }

        /* prepend radiotap information */
        ieee80211_add_rx_radiotap_header(local, skb, rate, needed_headroom);

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

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

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

                if (!ieee80211_sdata_running(sdata))
                        continue;

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

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

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

        return origskb;
}


static void ieee80211_parse_qos(struct ieee80211_rx_data *rx)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
        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)
                        status->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;
}

/**
 * DOC: Packet alignment
 *
 * Drivers always need to pass packets that are aligned to two-byte boundaries
 * to the stack.
 *
 * Additionally, should, if possible, 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).  If the payload data is not properly aligned and the
 * architecture doesn't support efficient unaligned operations, mac80211
 * will align the data.
 *
 * 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 to be directly in front of the payload in that case.
 */
static void ieee80211_verify_alignment(struct ieee80211_rx_data *rx)
{
#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
        WARN_ONCE((unsigned long)rx->skb->data & 1,
                  "unaligned packet at 0x%p\n", rx->skb->data);
#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 ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
        struct sk_buff *skb = rx->skb;

        if (likely(!(status->rx_flags & IEEE80211_RX_IN_SCAN)))
                return RX_CONTINUE;

        if (test_bit(SCAN_HW_SCANNING, &local->scanning))
                return ieee80211_scan_rx(rx->sdata, skb);

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

        /* scanning finished during invoking of handlers */
        I802_DEBUG_INC(local->rx_handlers_drop_passive_scan);
        return RX_DROP_UNUSABLE;
}


static int ieee80211_is_unicast_robust_mgmt_frame(struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;

        if (skb->len < 24 || is_multicast_ether_addr(hdr->addr1))
                return 0;

        return ieee80211_is_robust_mgmt_frame(hdr);
}


static int ieee80211_is_multicast_robust_mgmt_frame(struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;

        if (skb->len < 24 || !is_multicast_ether_addr(hdr->addr1))
                return 0;

        return ieee80211_is_robust_mgmt_frame(hdr);
}


/* Get the BIP key index from MMIE; return -1 if this is not a BIP frame */
static int ieee80211_get_mmie_keyidx(struct sk_buff *skb)
{
        struct ieee80211_mgmt *hdr = (struct ieee80211_mgmt *) skb->data;
        struct ieee80211_mmie *mmie;

        if (skb->len < 24 + sizeof(*mmie) ||
            !is_multicast_ether_addr(hdr->da))
                return -1;

        if (!ieee80211_is_robust_mgmt_frame((struct ieee80211_hdr *) hdr))
                return -1; /* not a robust management frame */

        mmie = (struct ieee80211_mmie *)
                (skb->data + skb->len - sizeof(*mmie));
        if (mmie->element_id != WLAN_EID_MMIE ||
            mmie->length != sizeof(*mmie) - 2)
                return -1;

        return le16_to_cpu(mmie->key_id);
}


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);
        char *dev_addr = rx->sdata->vif.addr;

        if (ieee80211_is_data(hdr->frame_control)) {
                if (is_multicast_ether_addr(hdr->addr1)) {
                        if (ieee80211_has_tods(hdr->frame_control) ||
                                !ieee80211_has_fromds(hdr->frame_control))
                                return RX_DROP_MONITOR;
                        if (memcmp(hdr->addr3, dev_addr, ETH_ALEN) == 0)
                                return RX_DROP_MONITOR;
                } else {
                        if (!ieee80211_has_a4(hdr->frame_control))
                                return RX_DROP_MONITOR;
                        if (memcmp(hdr->addr4, 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 != WLAN_CATEGORY_MESH_PLINK)
                                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->addr3, msh_h_get(hdr, hdrlen), rx->sdata))
                return RX_DROP_MONITOR;
#undef msh_h_get

        return RX_CONTINUE;
}

#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;
}


static void ieee80211_release_reorder_frame(struct ieee80211_hw *hw,
                                            struct tid_ampdu_rx *tid_agg_rx,
                                            int index)
{
        struct ieee80211_local *local = hw_to_local(hw);
        struct sk_buff *skb = tid_agg_rx->reorder_buf[index];
        struct ieee80211_rx_status *status;

        lockdep_assert_held(&tid_agg_rx->reorder_lock);

        if (!skb)
                goto no_frame;

        /* release the frame from the reorder ring buffer */
        tid_agg_rx->stored_mpdu_num--;
        tid_agg_rx->reorder_buf[index] = NULL;
        status = IEEE80211_SKB_RXCB(skb);
        status->rx_flags |= IEEE80211_RX_DEFERRED_RELEASE;
        skb_queue_tail(&local->rx_skb_queue, skb);

no_frame:
        tid_agg_rx->head_seq_num = seq_inc(tid_agg_rx->head_seq_num);
}

static void ieee80211_release_reorder_frames(struct ieee80211_hw *hw,
                                             struct tid_ampdu_rx *tid_agg_rx,
                                             u16 head_seq_num)
{
        int index;

        lockdep_assert_held(&tid_agg_rx->reorder_lock);

        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;
                ieee80211_release_reorder_frame(hw, tid_agg_rx, index);
        }
}

/*
 * Timeout (in jiffies) for skb's that are waiting in the RX reorder buffer. If
 * the skb was added to the buffer longer than this time ago, the earlier
 * frames that have not yet been received are assumed to be lost and the skb
 * can be released for processing. This may also release other skb's from the
 * reorder buffer if there are no additional gaps between the frames.
 *
 * Callers must hold tid_agg_rx->reorder_lock.
 */
#define HT_RX_REORDER_BUF_TIMEOUT (HZ / 10)

static void ieee80211_sta_reorder_release(struct ieee80211_hw *hw,
                                          struct tid_ampdu_rx *tid_agg_rx)
{
        int index, j;

        lockdep_assert_held(&tid_agg_rx->reorder_lock);

        /* 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;
        if (!tid_agg_rx->reorder_buf[index] &&
            tid_agg_rx->stored_mpdu_num > 1) {
                /*
                 * No buffers ready to be released, but check whether any
                 * frames in the reorder buffer have timed out.
                 */
                int skipped = 1;
                for (j = (index + 1) % tid_agg_rx->buf_size; j != index;
                     j = (j + 1) % tid_agg_rx->buf_size) {
                        if (!tid_agg_rx->reorder_buf[j]) {
                                skipped++;
                                continue;
                        }
                        if (!time_after(jiffies, tid_agg_rx->reorder_time[j] +
                                        HT_RX_REORDER_BUF_TIMEOUT))
                                goto set_release_timer;

#ifdef CONFIG_MAC80211_HT_DEBUG
                        if (net_ratelimit())
                                wiphy_debug(hw->wiphy,
                                            "release an RX reorder frame due to timeout on earlier frames\n");
#endif
                        ieee80211_release_reorder_frame(hw, tid_agg_rx, j);

                        /*
                         * Increment the head seq# also for the skipped slots.
                         */
                        tid_agg_rx->head_seq_num =
                                (tid_agg_rx->head_seq_num + skipped) & SEQ_MASK;
                        skipped = 0;
                }
        } else while (tid_agg_rx->reorder_buf[index]) {
                ieee80211_release_reorder_frame(hw, tid_agg_rx, index);
                index = seq_sub(tid_agg_rx->head_seq_num, tid_agg_rx->ssn) %
                                                        tid_agg_rx->buf_size;
        }

        /*
         * Disable the reorder release timer for now.
         *
         * The current implementation lacks a proper locking scheme
         * which would protect vital statistic and debug counters
         * from being updated by two different but concurrent BHs.
         *
         * More information about the topic is available from:
         * - thread: http://marc.info/?t=128635927000001
         *
         * What was wrong:
         * =>  http://marc.info/?l=linux-wireless&m=128636170811964
         * "Basically the thing is that until your patch, the data
         *  in the struct didn't actually need locking because it
         *  was accessed by the RX path only which is not concurrent."
         *
         * List of what needs to be fixed:
         * => http://marc.info/?l=linux-wireless&m=128656352920957
         *

        if (tid_agg_rx->stored_mpdu_num) {
                j = index = seq_sub(tid_agg_rx->head_seq_num,
                                    tid_agg_rx->ssn) % tid_agg_rx->buf_size;

                for (; j != (index - 1) % tid_agg_rx->buf_size;
                     j = (j + 1) % tid_agg_rx->buf_size) {
                        if (tid_agg_rx->reorder_buf[j])
                                break;
                }

 set_release_timer:

                mod_timer(&tid_agg_rx->reorder_timer,
                          tid_agg_rx->reorder_time[j] +
                          HT_RX_REORDER_BUF_TIMEOUT);
        } else {
                del_timer(&tid_agg_rx->reorder_timer);
        }
        */

set_release_timer:
        return;
}

/*
 * As this function belongs to the RX path it must be under
 * rcu_read_lock protection. It returns false if the frame
 * can be processed immediately, true if it was consumed.
 */
static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw,
                                             struct tid_ampdu_rx *tid_agg_rx,
                                             struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        u16 sc = le16_to_cpu(hdr->seq_ctrl);
        u16 mpdu_seq_num = (sc & IEEE80211_SCTL_SEQ) >> 4;
        u16 head_seq_num, buf_size;
        int index;
        bool ret = true;

        spin_lock(&tid_agg_rx->reorder_lock);

        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);
                goto out;
        }

        /*
         * If frame the sequence number exceeds our buffering window
         * size release some previous frames to make room for this one.
         */
        if (!seq_less(mpdu_seq_num, head_seq_num + buf_size)) {
                head_seq_num = seq_inc(seq_sub(mpdu_seq_num, buf_size));
                /* release stored frames up to new head to stack */
                ieee80211_release_reorder_frames(hw, tid_agg_rx, head_seq_num);
        }

        /* Now the new frame is always in the range of the reordering buffer */

        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);
                goto out;
        }

        /*
         * If the current MPDU is in the right order and nothing else
         * is stored we can process it directly, no need to buffer it.
         */
        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);
                ret = false;
                goto out;
        }

        /* put the frame in the reordering buffer */
        tid_agg_rx->reorder_buf[index] = skb;
        tid_agg_rx->reorder_time[index] = jiffies;
        tid_agg_rx->stored_mpdu_num++;
        ieee80211_sta_reorder_release(hw, tid_agg_rx);

 out:
        spin_unlock(&tid_agg_rx->reorder_lock);
        return ret;
}

/*
 * Reorder MPDUs from A-MPDUs, keeping them on a buffer. Returns
 * true if the MPDU was buffered, false if it should be processed.
 */
static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx)
{
        struct sk_buff *skb = rx->skb;
        struct ieee80211_local *local = rx->local;
        struct ieee80211_hw *hw = &local->hw;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
        struct sta_info *sta = rx->sta;
        struct tid_ampdu_rx *tid_agg_rx;
        u16 sc;
        int tid;

        if (!ieee80211_is_data_qos(hdr->frame_control))
                goto dont_reorder;

        /*
         * filter the QoS data rx stream according to
         * STA/TID and check if this STA/TID is on aggregation
         */

        if (!sta)
                goto dont_reorder;

        tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;

        tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
        if (!tid_agg_rx)
                goto dont_reorder;

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

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

        /* reset session timer */
        if (tid_agg_rx->timeout)
                mod_timer(&tid_agg_rx->session_timer,
                          TU_TO_EXP_TIME(tid_agg_rx->timeout));

        /* if this mpdu is fragmented - terminate rx aggregation session */
        sc = le16_to_cpu(hdr->seq_ctrl);
        if (sc & IEEE80211_SCTL_FRAG) {
                skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
                skb_queue_tail(&rx->sdata->skb_queue, skb);
                ieee80211_queue_work(&local->hw, &rx->sdata->work);
                return;
        }

        /*
         * No locking needed -- we will only ever process one
         * RX packet at a time, and thus own tid_agg_rx. All
         * other code manipulating it needs to (and does) make
         * sure that we cannot get to it any more before doing
         * anything with it.
         */
        if (ieee80211_sta_manage_reorder_buf(hw, tid_agg_rx, skb))
                return;

 dont_reorder:
        skb_queue_tail(&local->rx_skb_queue, skb);
}

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;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

        /* 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 (status->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->sdata->vif.type != NL80211_IFTYPE_WDS &&
                     (!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)) ||
                    !(status->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 sk_buff *skb = rx->skb;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        int keyidx;
        int hdrlen;
        ieee80211_rx_result result = RX_DROP_UNUSABLE;
        struct ieee80211_key *sta_ptk = NULL;
        int mmie_keyidx = -1;
        __le16 fc;

        /*
         * Key selection 101
         *
         * There are four types of keys:
         *  - GTK (group keys)
         *  - IGTK (group keys for management frames)
         *  - 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 and IGTKs.
         * Unless, of course, actual WEP keys ("pre-RSNA") are used, then
         * unicast frames can also use key indices 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.
         */

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

        /* start without a key */
        rx->key = NULL;

        if (rx->sta)
                sta_ptk = rcu_dereference(rx->sta->ptk);

        fc = hdr->frame_control;

        if (!ieee80211_has_protected(fc))
                mmie_keyidx = ieee80211_get_mmie_keyidx(rx->skb);

        if (!is_multicast_ether_addr(hdr->addr1) && sta_ptk) {
                rx->key = sta_ptk;
                if ((status->flag & RX_FLAG_DECRYPTED) &&
                    (status->flag & RX_FLAG_IV_STRIPPED))
                        return RX_CONTINUE;
                /* Skip decryption if the frame is not protected. */
                if (!ieee80211_has_protected(fc))
                        return RX_CONTINUE;
        } else if (mmie_keyidx >= 0) {
                /* Broadcast/multicast robust management frame / BIP */
                if ((status->flag & RX_FLAG_DECRYPTED) &&
                    (status->flag & RX_FLAG_IV_STRIPPED))
                        return RX_CONTINUE;

                if (mmie_keyidx < NUM_DEFAULT_KEYS ||
                    mmie_keyidx >= NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS)
                        return RX_DROP_MONITOR; /* unexpected BIP keyidx */
                if (rx->sta)
                        rx->key = rcu_dereference(rx->sta->gtk[mmie_keyidx]);
                if (!rx->key)
                        rx->key = rcu_dereference(rx->sdata->keys[mmie_keyidx]);
        } else if (!ieee80211_has_protected(fc)) {
                /*
                 * The frame was not protected, so skip decryption. However, we
                 * need to set rx->key if there is a key that could have been
                 * used so that the frame may be dropped if encryption would
                 * have been expected.
                 */
                struct ieee80211_key *key = NULL;
                struct ieee80211_sub_if_data *sdata = rx->sdata;
                int i;

                if (ieee80211_is_mgmt(fc) &&
                    is_multicast_ether_addr(hdr->addr1) &&
                    (key = rcu_dereference(rx->sdata->default_mgmt_key)))
                        rx->key = key;
                else {
                        if (rx->sta) {
                                for (i = 0; i < NUM_DEFAULT_KEYS; i++) {
                                        key = rcu_dereference(rx->sta->gtk[i]);
                                        if (key)
                                                break;
                                }
                        }
                        if (!key) {
                                for (i = 0; i < NUM_DEFAULT_KEYS; i++) {
                                        key = rcu_dereference(sdata->keys[i]);
                                        if (key)
                                                break;
                                }
                        }
                        if (key)
                                rx->key = key;
                }
                return RX_CONTINUE;
        } else {
                u8 keyid;
                /*
                 * 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 ((status->flag & RX_FLAG_DECRYPTED) &&
                    (status->flag & RX_FLAG_IV_STRIPPED))
                        return RX_CONTINUE;

                hdrlen = ieee80211_hdrlen(fc);

                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
                 */
                skb_copy_bits(rx->skb, hdrlen + 3, &keyid, 1);
                keyidx = keyid >> 6;

                /* check per-station GTK first, if multicast packet */
                if (is_multicast_ether_addr(hdr->addr1) && rx->sta)
                        rx->key = rcu_dereference(rx->sta->gtk[keyidx]);

                /* if not found, try default key */
                if (!rx->key) {
                        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.cipher != WLAN_CIPHER_SUITE_WEP40 &&
                            rx->key->conf.cipher != WLAN_CIPHER_SUITE_WEP104 &&
                            !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;
        }

        if (skb_linearize(rx->skb))
                return RX_DROP_UNUSABLE;
        /* the hdr variable is invalid now! */

        switch (rx->key->conf.cipher) {
        case WLAN_CIPHER_SUITE_WEP40:
        case WLAN_CIPHER_SUITE_WEP104:
                /* Check for weak IVs if possible */
                if (rx->sta && ieee80211_is_data(fc) &&
                    (!(status->flag & RX_FLAG_IV_STRIPPED) ||
                     !(status->flag & RX_FLAG_DECRYPTED)) &&
                    ieee80211_wep_is_weak_iv(rx->skb, rx->key))
                        rx->sta->wep_weak_iv_count++;

                result = ieee80211_crypto_wep_decrypt(rx);
                break;
        case WLAN_CIPHER_SUITE_TKIP:
                result = ieee80211_crypto_tkip_decrypt(rx);
                break;
        case WLAN_CIPHER_SUITE_CCMP:
                result = ieee80211_crypto_ccmp_decrypt(rx);
                break;
        case WLAN_CIPHER_SUITE_AES_CMAC:
                result = ieee80211_crypto_aes_cmac_decrypt(rx);
                break;
        default:
                /*
                 * We can reach here only with HW-only algorithms
                 * but why didn't it decrypt the frame?!
                 */
                return RX_DROP_UNUSABLE;
        }

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

        return result;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_check_more_data(struct ieee80211_rx_data *rx)
{
        struct ieee80211_local *local;
        struct ieee80211_hdr *hdr;
        struct sk_buff *skb;

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

        if (!local->pspolling)
                return RX_CONTINUE;

        if (!ieee80211_has_fromds(hdr->frame_control))
                /* this is not from AP */
                return RX_CONTINUE;

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

        if (!ieee80211_has_moredata(hdr->frame_control)) {
                /* AP has no more frames buffered for us */
                local->pspolling = false;
                return RX_CONTINUE;
        }

        /* more data bit is set, let's request a new frame from the AP */
        ieee80211_send_pspoll(local, rx->sdata);

        return RX_CONTINUE;
}

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

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

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

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

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

        if (test_sta_flags(sta, WLAN_STA_PS_DRIVER)) {
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
                printk(KERN_DEBUG "%s: STA %pM aid %d driver-ps-blocked\n",
                       sdata->name, sta->sta.addr, sta->sta.aid);
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
                return;
        }

        ieee80211_sta_ps_deliver_wakeup(sta);
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
{
        struct sta_info *sta = rx->sta;
        struct sk_buff *skb = rx->skb;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)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 start 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.ibss.bssid) == 0)
                        sta->last_rx = jiffies;
        } else if (!is_multicast_ether_addr(hdr->addr1)) {
                /*
                 * Mesh beacons will update last_rx when if they are found to
                 * match the current local configuration when processed.
                 */
                sta->last_rx = jiffies;
        }

        if (!(status->rx_flags & IEEE80211_RX_RA_MATCH))
                return RX_CONTINUE;

        if (rx->sdata->vif.type == NL80211_IFTYPE_STATION)
                ieee80211_sta_rx_notify(rx->sdata, hdr);

        sta->rx_fragments++;
        sta->rx_bytes += rx->skb->len;
        sta->last_signal = status->signal;
        ewma_add(&sta->avg_signal, -status->signal);

        /*
         * Change STA power saving mode only at the end of a frame
         * exchange sequence.
         */
        if (!ieee80211_has_morefrags(hdr->frame_control) &&
            !(status->rx_flags & IEEE80211_RX_DEFERRED_RELEASE) &&
            (rx->sdata->vif.type == NL80211_IFTYPE_AP ||
             rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN)) {
                if (test_sta_flags(sta, WLAN_STA_PS_STA)) {
                        /*
                         * Ignore doze->wake transitions that are
                         * indicated by non-data frames, the standard
                         * is unclear here, but for example going to
                         * PS mode and then scanning would cause a
                         * doze->wake transition for the probe request,
                         * and that is clearly undesirable.
                         */
                        if (ieee80211_is_data(hdr->frame_control) &&
                            !ieee80211_has_pm(hdr->frame_control))
                                ap_sta_ps_end(sta);
                } else {
                        if (ieee80211_has_pm(hdr->frame_control))
                                ap_sta_ps_start(sta);
                }
        }

        /*
         * Drop (qos-)data::nullfunc frames silently, since they
         * are used only to control station power saving mode.
         */
        if (ieee80211_is_nullfunc(hdr->frame_control) ||
            ieee80211_is_qos_nullfunc(hdr->frame_control)) {
                I802_DEBUG_INC(rx->local->rx_handlers_drop_nullfunc);

                /*
                 * If we receive a 4-addr nullfunc frame from a STA
                 * that was not moved to a 4-addr STA vlan yet, drop
                 * the frame to the monitor interface, to make sure
                 * that hostapd sees it
                 */
                if (ieee80211_has_a4(hdr->frame_control) &&
                    (rx->sdata->vif.type == NL80211_IFTYPE_AP ||
                     (rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
                      !rx->sdata->u.vlan.sta)))
                        return RX_DROP_MONITOR;
                /*
                 * 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->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;
        struct ieee80211_rx_status *status;

        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);

        if (skb_linearize(rx->skb))
                return RX_DROP_UNUSABLE;

        /*
         *  skb_linearize() might change the skb->data and
         *  previously cached variables (in this case, hdr) need to
         *  be refreshed with the new data.
         */
        hdr = (struct ieee80211_hdr *)rx->skb->data;
        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.cipher == WLAN_CIPHER_SUITE_CCMP &&
                    ieee80211_has_protected(fc)) {
                        int queue = ieee80211_is_mgmt(fc) ?
                                NUM_RX_DATA_QUEUES : rx->queue;
                        /* 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[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;
                int queue;
                if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_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;
                }
                queue = ieee80211_is_mgmt(fc) ?
                        NUM_RX_DATA_QUEUES : rx->queue;
                rpn = rx->key->u.ccmp.rx_pn[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 */
        status = IEEE80211_SKB_RXCB(rx->skb);
        status->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 = rx->sdata;
        __le16 fc = ((struct ieee80211_hdr *)rx->skb->data)->frame_control;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

        if (likely(!rx->sta || !ieee80211_is_pspoll(fc) ||
                   !(status->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;

        if (!test_sta_flags(rx->sta, WLAN_STA_PS_DRIVER))
                ieee80211_sta_ps_deliver_poll_response(rx->sta);
        else
                set_sta_flags(rx->sta, WLAN_STA_PSPOLL);

        /* 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)
{
        struct sk_buff *skb = rx->skb;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);

        /*
         * Pass through unencrypted frames if the hardware has
         * decrypted them already.
         */
        if (status->flag & RX_FLAG_DECRYPTED)
                return 0;

        /* Drop unencrypted frames if key is set. */
        if (unlikely(!ieee80211_has_protected(fc) &&
                     !ieee80211_is_nullfunc(fc) &&
                     ieee80211_is_data(fc) &&
                     (rx->key || rx->sdata->drop_unencrypted)))
                return -EACCES;

        return 0;
}

static int
ieee80211_drop_unencrypted_mgmt(struct ieee80211_rx_data *rx)
{
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
        __le16 fc = hdr->frame_control;

        /*
         * Pass through unencrypted frames if the hardware has
         * decrypted them already.
         */
        if (status->flag & RX_FLAG_DECRYPTED)
                return 0;

        if (rx->sta && test_sta_flags(rx->sta, WLAN_STA_MFP)) {
                if (unlikely(!ieee80211_has_protected(fc) &&
                             ieee80211_is_unicast_robust_mgmt_frame(rx->skb) &&
                             rx->key)) {
                        if (ieee80211_is_deauth(fc))
                                cfg80211_send_unprot_deauth(rx->sdata->dev,
                                                            rx->skb->data,
                                                            rx->skb->len);
                        else if (ieee80211_is_disassoc(fc))
                                cfg80211_send_unprot_disassoc(rx->sdata->dev,
                                                              rx->skb->data,
                                                              rx->skb->len);
                        return -EACCES;
                }
                /* BIP does not use Protected field, so need to check MMIE */
                if (unlikely(ieee80211_is_multicast_robust_mgmt_frame(rx->skb) &&
                             ieee80211_get_mmie_keyidx(rx->skb) < 0)) {
                        if (ieee80211_is_deauth(fc))
                                cfg80211_send_unprot_deauth(rx->sdata->dev,
                                                            rx->skb->data,
                                                            rx->skb->len);
                        else if (ieee80211_is_disassoc(fc))
                                cfg80211_send_unprot_disassoc(rx->sdata->dev,
                                                              rx->skb->data,
                                                              rx->skb->len);
                        return -EACCES;
                }
                /*
                 * When using MFP, Action frames are not allowed prior to
                 * having configured keys.
                 */
                if (unlikely(ieee80211_is_action(fc) && !rx->key &&
                             ieee80211_is_robust_mgmt_frame(
                                     (struct ieee80211_hdr *) rx->skb->data)))
                        return -EACCES;
        }

        return 0;
}

static int
__ieee80211_data_to_8023(struct ieee80211_rx_data *rx)
{
        struct ieee80211_sub_if_data *sdata = rx->sdata;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;

        if (ieee80211_has_a4(hdr->frame_control) &&
            sdata->vif.type == NL80211_IFTYPE_AP_VLAN && !sdata->u.vlan.sta)
                return -1;

        if (is_multicast_ether_addr(hdr->addr1) &&
            ((sdata->vif.type == NL80211_IFTYPE_AP_VLAN && sdata->u.vlan.sta) ||
             (sdata->vif.type == NL80211_IFTYPE_STATION && sdata->u.mgd.use_4addr)))
                return -1;

        return ieee80211_data_to_8023(rx->skb, sdata->vif.addr, sdata->vif.type);
}

/*
 * 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 == rx->sdata->control_port_protocol &&
            (compare_ether_addr(ehdr->h_dest, rx->sdata->vif.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 ieee80211_sub_if_data *sdata = rx->sdata;
        struct net_device *dev = sdata->dev;
        struct sk_buff *skb, *xmit_skb;
        struct ethhdr *ehdr = (struct ethhdr *) rx->skb->data;
        struct sta_info *dsta;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

        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) &&
            (status->rx_flags & IEEE80211_RX_RA_MATCH) &&
            (sdata->vif.type != NL80211_IFTYPE_AP_VLAN || !sdata->u.vlan.sta)) {
                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(sdata, skb->data);
                        if (dsta) {
                                /*
                                 * 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) {
                int align __maybe_unused;

#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
                /*
                 * 'align' will only take the values 0 or 2 here
                 * since all frames are required to be aligned
                 * to 2-byte boundaries when being passed to
                 * mac80211. That also explains the __skb_push()
                 * below.
                 */
                align = ((unsigned long)(skb->data + sizeof(struct ethhdr))) & 3;
                if (align) {
                        if (WARN_ON(skb_headroom(skb) < 3)) {
                                dev_kfree_skb(skb);
                                skb = NULL;
                        } else {
                                u8 *data = skb->data;
                                size_t len = skb_headlen(skb);
                                skb->data -= align;
                                memmove(skb->data, data, len);
                                skb_set_tail_pointer(skb, len);
                        }
                }
#endif

                if (skb) {
                        /* deliver to local stack */
                        skb->protocol = eth_type_trans(skb, dev);
                        memset(skb->cb, 0, sizeof(skb->cb));
                        netif_receive_skb(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->sdata->dev;
        struct sk_buff *skb = rx->skb;
        struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
        __le16 fc = hdr->frame_control;
        struct sk_buff_head frame_list;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

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

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

        if (!(status->rx_flags & IEEE80211_RX_AMSDU))
                return RX_CONTINUE;

        if (ieee80211_has_a4(hdr->frame_control) &&
            rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
            !rx->sdata->u.vlan.sta)
                return RX_DROP_UNUSABLE;

        if (is_multicast_ether_addr(hdr->addr1) &&
            ((rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN &&
              rx->sdata->u.vlan.sta) ||
             (rx->sdata->vif.type == NL80211_IFTYPE_STATION &&
              rx->sdata->u.mgd.use_4addr)))
                return RX_DROP_UNUSABLE;

        skb->dev = dev;
        __skb_queue_head_init(&frame_list);

        if (skb_linearize(skb))
                return RX_DROP_UNUSABLE;

        ieee80211_amsdu_to_8023s(skb, &frame_list, dev->dev_addr,
                                 rx->sdata->vif.type,
                                 rx->local->hw.extra_tx_headroom);

        while (!skb_queue_empty(&frame_list)) {
                rx->skb = __skb_dequeue(&frame_list);

                if (!ieee80211_frame_allowed(rx, fc)) {
                        dev_kfree_skb(rx->skb);
                        continue;
                }
                dev->stats.rx_packets++;
                dev->stats.rx_bytes += rx->skb->len;

                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;
        struct ieee80211_local *local = rx->local;
        struct ieee80211_sub_if_data *sdata = rx->sdata;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(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) {
                struct mesh_path *mppath;
                char *proxied_addr;
                char *mpp_addr;

                if (is_multicast_ether_addr(hdr->addr1)) {
                        mpp_addr = hdr->addr3;
                        proxied_addr = mesh_hdr->eaddr1;
                } else {
                        mpp_addr = hdr->addr4;
                        proxied_addr = mesh_hdr->eaddr2;
                }

                rcu_read_lock();
                mppath = mpp_path_lookup(proxied_addr, sdata);
                if (!mppath) {
                        mpp_path_add(proxied_addr, mpp_addr, sdata);
                } else {
                        spin_lock_bh(&mppath->state_lock);
                        if (compare_ether_addr(mppath->mpp, mpp_addr) != 0)
                                memcpy(mppath->mpp, mpp_addr, ETH_ALEN);
                        spin_unlock_bh(&mppath->state_lock);
                }
                rcu_read_unlock();
        }

        /* Frame has reached destination.  Don't forward */
        if (!is_multicast_ether_addr(hdr->addr1) &&
            compare_ether_addr(sdata->vif.addr, hdr->addr3) == 0)
                return RX_CONTINUE;

        mesh_hdr->ttl--;

        if (status->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;
                        struct ieee80211_tx_info *info;

                        fwd_skb = skb_copy(skb, GFP_ATOMIC);

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

                        fwd_hdr =  (struct ieee80211_hdr *) fwd_skb->data;
                        memcpy(fwd_hdr->addr2, sdata->vif.addr, ETH_ALEN);
                        info = IEEE80211_SKB_CB(fwd_skb);
                        memset(info, 0, sizeof(*info));
                        info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
                        info->control.vif = &rx->sdata->vif;
                        skb_set_queue_mapping(skb,
                                ieee80211_select_queue(rx->sdata, fwd_skb));
                        ieee80211_set_qos_hdr(local, skb);
                        if (is_multicast_ether_addr(fwd_hdr->addr1))
                                IEEE80211_IFSTA_MESH_CTR_INC(&sdata->u.mesh,
                                                                fwded_mcast);
                        else {
                                int err;
                                /*
                                 * 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);
                                err = mesh_nexthop_lookup(fwd_skb, sdata);
                                /* Failed to immediately resolve next hop:
                                 * fwded frame was dropped or will be added
                                 * later to the pending skb queue.  */
                                if (err)
                                        return RX_DROP_MONITOR;

                                IEEE80211_IFSTA_MESH_CTR_INC(&sdata->u.mesh,
                                                                fwded_unicast);
                        }
                        IEEE80211_IFSTA_MESH_CTR_INC(&sdata->u.mesh,
                                                     fwded_frames);
                        ieee80211_add_pending_skb(local, fwd_skb);
                }
        }

        if (is_multicast_ether_addr(hdr->addr1) ||
            sdata->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 ieee80211_sub_if_data *sdata = rx->sdata;
        struct ieee80211_local *local = rx->local;
        struct net_device *dev = sdata->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;

        /*
         * Allow the cooked monitor interface of an AP to see 4-addr frames so
         * that a 4-addr station can be detected and moved into a separate VLAN
         */
        if (ieee80211_has_a4(hdr->frame_control) &&
            sdata->vif.type == NL80211_IFTYPE_AP)
                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;

        if (local->ps_sdata && local->hw.conf.dynamic_ps_timeout > 0 &&
            !is_multicast_ether_addr(((struct ethhdr *)rx->skb->data)->h_dest)) {
                        mod_timer(&local->dynamic_ps_timer, jiffies +
                         msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
        }

        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)) {
                struct {
                        __le16 control, start_seq_num;
                } __packed bar_data;

                if (!rx->sta)
                        return RX_DROP_MONITOR;

                if (skb_copy_bits(skb, offsetof(struct ieee80211_bar, control),
                                  &bar_data, sizeof(bar_data)))
                        return RX_DROP_MONITOR;

                tid = le16_to_cpu(bar_data.control) >> 12;

                tid_agg_rx = rcu_dereference(rx->sta->ampdu_mlme.tid_rx[tid]);
                if (!tid_agg_rx)
                        return RX_DROP_MONITOR;

                start_seq_num = le16_to_cpu(bar_data.start_seq_num) >> 4;

                /* reset session timer */
                if (tid_agg_rx->timeout)
                        mod_timer(&tid_agg_rx->session_timer,
                                  TU_TO_EXP_TIME(tid_agg_rx->timeout));

                spin_lock(&tid_agg_rx->reorder_lock);
                /* release stored frames up to start of BAR */
                ieee80211_release_reorder_frames(hw, tid_agg_rx, start_seq_num);
                spin_unlock(&tid_agg_rx->reorder_lock);

                kfree_skb(skb);
                return RX_QUEUED;
        }

        /*
         * After this point, we only want management frames,
         * so we can drop all remaining control frames to
         * cooked monitor interfaces.
         */
        return RX_DROP_MONITOR;
}

static void ieee80211_process_sa_query_req(struct ieee80211_sub_if_data *sdata,
                                           struct ieee80211_mgmt *mgmt,
                                           size_t len)
{
        struct ieee80211_local *local = sdata->local;
        struct sk_buff *skb;
        struct ieee80211_mgmt *resp;

        if (compare_ether_addr(mgmt->da, sdata->vif.addr) != 0) {
                /* Not to own unicast address */
                return;
        }

        if (compare_ether_addr(mgmt->sa, sdata->u.mgd.bssid) != 0 ||
            compare_ether_addr(mgmt->bssid, sdata->u.mgd.bssid) != 0) {
                /* Not from the current AP or not associated yet. */
                return;
        }

        if (len < 24 + 1 + sizeof(resp->u.action.u.sa_query)) {
                /* Too short SA Query request frame */
                return;
        }

        skb = dev_alloc_skb(sizeof(*resp) + local->hw.extra_tx_headroom);
        if (skb == NULL)
                return;

        skb_reserve(skb, local->hw.extra_tx_headroom);
        resp = (struct ieee80211_mgmt *) skb_put(skb, 24);
        memset(resp, 0, 24);
        memcpy(resp->da, mgmt->sa, ETH_ALEN);
        memcpy(resp->sa, sdata->vif.addr, ETH_ALEN);
        memcpy(resp->bssid, sdata->u.mgd.bssid, ETH_ALEN);
        resp->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                          IEEE80211_STYPE_ACTION);
        skb_put(skb, 1 + sizeof(resp->u.action.u.sa_query));
        resp->u.action.category = WLAN_CATEGORY_SA_QUERY;
        resp->u.action.u.sa_query.action = WLAN_ACTION_SA_QUERY_RESPONSE;
        memcpy(resp->u.action.u.sa_query.trans_id,
               mgmt->u.action.u.sa_query.trans_id,
               WLAN_SA_QUERY_TR_ID_LEN);

        ieee80211_tx_skb(sdata, skb);
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_mgmt_check(struct ieee80211_rx_data *rx)
{
        struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

        /*
         * From here on, look only at management frames.
         * Data and control frames are already handled,
         * and unknown (reserved) frames are useless.
         */
        if (rx->skb->len < 24)
                return RX_DROP_MONITOR;

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

        if (!(status->rx_flags & IEEE80211_RX_RA_MATCH))
                return RX_DROP_MONITOR;

        if (ieee80211_drop_unencrypted_mgmt(rx))
                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 = rx->sdata;
        struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
        int len = rx->skb->len;

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

        /* drop too small frames */
        if (len < IEEE80211_MIN_ACTION_SIZE)
                return RX_DROP_UNUSABLE;

        if (!rx->sta && mgmt->u.action.category != WLAN_CATEGORY_PUBLIC)
                return RX_DROP_UNUSABLE;

        if (!(status->rx_flags & IEEE80211_RX_RA_MATCH))
                return RX_DROP_UNUSABLE;

        switch (mgmt->u.action.category) {
        case WLAN_CATEGORY_BACK:
                /*
                 * The aggregation code is not prepared to handle
                 * anything but STA/AP due to the BSSID handling;
                 * IBSS could work in the code but isn't supported
                 * by drivers or the standard.
                 */
                if (sdata->vif.type != NL80211_IFTYPE_STATION &&
                    sdata->vif.type != NL80211_IFTYPE_AP_VLAN &&
                    sdata->vif.type != NL80211_IFTYPE_AP)
                        break;

                /* verify action_code is present */
                if (len < IEEE80211_MIN_ACTION_SIZE + 1)
                        break;

                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)))
                                goto invalid;
                        break;
                case WLAN_ACTION_ADDBA_RESP:
                        if (len < (IEEE80211_MIN_ACTION_SIZE +
                                   sizeof(mgmt->u.action.u.addba_resp)))
                                goto invalid;
                        break;
                case WLAN_ACTION_DELBA:
                        if (len < (IEEE80211_MIN_ACTION_SIZE +
                                   sizeof(mgmt->u.action.u.delba)))
                                goto invalid;
                        break;
                default:
                        goto invalid;
                }

                goto queue;
        case WLAN_CATEGORY_SPECTRUM_MGMT:
                if (local->hw.conf.channel->band != IEEE80211_BAND_5GHZ)
                        break;

                if (sdata->vif.type != NL80211_IFTYPE_STATION)
                        break;

                /* verify action_code is present */
                if (len < IEEE80211_MIN_ACTION_SIZE + 1)
                        break;

                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)))
                                break;
                        ieee80211_process_measurement_req(sdata, mgmt, len);
                        goto handled;
                case WLAN_ACTION_SPCT_CHL_SWITCH:
                        if (len < (IEEE80211_MIN_ACTION_SIZE +
                                   sizeof(mgmt->u.action.u.chan_switch)))
                                break;

                        if (sdata->vif.type != NL80211_IFTYPE_STATION)
                                break;

                        if (memcmp(mgmt->bssid, sdata->u.mgd.bssid, ETH_ALEN))
                                break;

                        goto queue;
                }
                break;
        case WLAN_CATEGORY_SA_QUERY:
                if (len < (IEEE80211_MIN_ACTION_SIZE +
                           sizeof(mgmt->u.action.u.sa_query)))
                        break;

                switch (mgmt->u.action.u.sa_query.action) {
                case WLAN_ACTION_SA_QUERY_REQUEST:
                        if (sdata->vif.type != NL80211_IFTYPE_STATION)
                                break;
                        ieee80211_process_sa_query_req(sdata, mgmt, len);
                        goto handled;
                }
                break;
        case WLAN_CATEGORY_MESH_PLINK:
                if (!ieee80211_vif_is_mesh(&sdata->vif))
                        break;
                goto queue;
        case WLAN_CATEGORY_MESH_PATH_SEL:
                if (!mesh_path_sel_is_hwmp(sdata))
                        break;
                goto queue;
        }

        return RX_CONTINUE;

 invalid:
        status->rx_flags |= IEEE80211_RX_MALFORMED_ACTION_FRM;
        /* will return in the next handlers */
        return RX_CONTINUE;

 handled:
        if (rx->sta)
                rx->sta->rx_packets++;
        dev_kfree_skb(rx->skb);
        return RX_QUEUED;

 queue:
        rx->skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
        skb_queue_tail(&sdata->skb_queue, rx->skb);
        ieee80211_queue_work(&local->hw, &sdata->work);
        if (rx->sta)
                rx->sta->rx_packets++;
        return RX_QUEUED;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_userspace_mgmt(struct ieee80211_rx_data *rx)
{
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

        /* skip known-bad action frames and return them in the next handler */
        if (status->rx_flags & IEEE80211_RX_MALFORMED_ACTION_FRM)
                return RX_CONTINUE;

        /*
         * Getting here means the kernel doesn't know how to handle
         * it, but maybe userspace does ... include returned frames
         * so userspace can register for those to know whether ones
         * it transmitted were processed or returned.
         */

        if (cfg80211_rx_mgmt(rx->sdata->dev, status->freq,
                             rx->skb->data, rx->skb->len,
                             GFP_ATOMIC)) {
                if (rx->sta)
                        rx->sta->rx_packets++;
                dev_kfree_skb(rx->skb);
                return RX_QUEUED;
        }


        return RX_CONTINUE;
}

static ieee80211_rx_result debug_noinline
ieee80211_rx_h_action_return(struct ieee80211_rx_data *rx)
{
        struct ieee80211_local *local = rx->local;
        struct ieee80211_mgmt *mgmt = (struct ieee80211_mgmt *) rx->skb->data;
        struct sk_buff *nskb;
        struct ieee80211_sub_if_data *sdata = rx->sdata;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);

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

        /*
         * For AP mode, hostapd is responsible for handling any action
         * frames that we didn't handle, including returning unknown
         * ones. For all other modes we will return them to the sender,
         * setting the 0x80 bit in the action category, as required by
         * 802.11-2007 7.3.1.11.
         * Newer versions of hostapd shall also use the management frame
         * registration mechanisms, but older ones still use cooked
         * monitor interfaces so push all frames there.
         */
        if (!(status->rx_flags & IEEE80211_RX_MALFORMED_ACTION_FRM) &&
            (sdata->vif.type == NL80211_IFTYPE_AP ||
             sdata->vif.type == NL80211_IFTYPE_AP_VLAN))
                return RX_DROP_MONITOR;

        /* do not return rejected action frames */
        if (mgmt->u.action.category & 0x80)
                return RX_DROP_UNUSABLE;

        nskb = skb_copy_expand(rx->skb, local->hw.extra_tx_headroom, 0,
                               GFP_ATOMIC);
        if (nskb) {
                struct ieee80211_mgmt *nmgmt = (void *)nskb->data;

                nmgmt->u.action.category |= 0x80;
                memcpy(nmgmt->da, nmgmt->sa, ETH_ALEN);
                memcpy(nmgmt->sa, rx->sdata->vif.addr, ETH_ALEN);

                memset(nskb->cb, 0, sizeof(nskb->cb));

                ieee80211_tx_skb(rx->sdata, nskb);
        }
        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 = rx->sdata;
        ieee80211_rx_result rxs;
        struct ieee80211_mgmt *mgmt = (void *)rx->skb->data;
        __le16 stype;

        rxs = ieee80211_work_rx_mgmt(rx->sdata, rx->skb);
        if (rxs != RX_CONTINUE)
                return rxs;

        stype = mgmt->frame_control & cpu_to_le16(IEEE80211_FCTL_STYPE);

        if (!ieee80211_vif_is_mesh(&sdata->vif) &&
            sdata->vif.type != NL80211_IFTYPE_ADHOC &&
            sdata->vif.type != NL80211_IFTYPE_STATION)
                return RX_DROP_MONITOR;

        switch (stype) {
        case cpu_to_le16(IEEE80211_STYPE_BEACON):
        case cpu_to_le16(IEEE80211_STYPE_PROBE_RESP):
                /* process for all: mesh, mlme, ibss */
                break;
        case cpu_to_le16(IEEE80211_STYPE_DEAUTH):
        case cpu_to_le16(IEEE80211_STYPE_DISASSOC):
                if (is_multicast_ether_addr(mgmt->da) &&
                    !is_broadcast_ether_addr(mgmt->da))
                        return RX_DROP_MONITOR;

                /* process only for station */
                if (sdata->vif.type != NL80211_IFTYPE_STATION)
                        return RX_DROP_MONITOR;
                break;
        case cpu_to_le16(IEEE80211_STYPE_PROBE_REQ):
        case cpu_to_le16(IEEE80211_STYPE_AUTH):
                /* process only for ibss */
                if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
                        return RX_DROP_MONITOR;
                break;
        default:
                return RX_DROP_MONITOR;
        }

        /* queue up frame and kick off work to process it */
        rx->skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
        skb_queue_tail(&sdata->skb_queue, rx->skb);
        ieee80211_queue_work(&rx->local->hw, &sdata->work);
        if (rx->sta)
                rx->sta->rx_packets++;

        return RX_QUEUED;
}

static void ieee80211_rx_michael_mic_report(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.
                 */
                return;
        }

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

        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.
                 */
                return;
        }

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

        mac80211_ev_michael_mic_failure(rx->sdata, keyidx, hdr, NULL,
                                        GFP_ATOMIC);
}

/* TODO: use IEEE80211_RX_FRAGMENTED */
static void ieee80211_rx_cooked_monitor(struct ieee80211_rx_data *rx,
                                        struct ieee80211_rate *rate)
{
        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_or_pad;
                __le16 chan_freq;
                __le16 chan_flags;
        } __packed *rthdr;
        struct sk_buff *skb = rx->skb, *skb2;
        struct net_device *prev_dev = NULL;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);

        /*
         * If cooked monitor has been processed already, then
         * don't do it again. If not, set the flag.
         */
        if (rx->flags & IEEE80211_RX_CMNTR)
                goto out_free_skb;
        rx->flags |= IEEE80211_RX_CMNTR;

        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_CHANNEL));

        if (rate) {
                rthdr->rate_or_pad = rate->bitrate / 5;
                rthdr->hdr.it_present |=
                        cpu_to_le32(1 << IEEE80211_RADIOTAP_RATE);
        }
        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 (!ieee80211_sdata_running(sdata))
                        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_receive_skb(skb2);
                        }
                }

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

        if (prev_dev) {
                skb->dev = prev_dev;
                netif_receive_skb(skb);
                return;
        }

 out_free_skb:
        dev_kfree_skb(skb);
}

static void ieee80211_rx_handlers_result(struct ieee80211_rx_data *rx,
                                         ieee80211_rx_result res)
{
        switch (res) {
        case RX_DROP_MONITOR:
                I802_DEBUG_INC(rx->sdata->local->rx_handlers_drop);
                if (rx->sta)
                        rx->sta->rx_dropped++;
                /* fall through */
        case RX_CONTINUE: {
                struct ieee80211_rate *rate = NULL;
                struct ieee80211_supported_band *sband;
                struct ieee80211_rx_status *status;

                status = IEEE80211_SKB_RXCB((rx->skb));

                sband = rx->local->hw.wiphy->bands[status->band];
                if (!(status->flag & RX_FLAG_HT))
                        rate = &sband->bitrates[status->rate_idx];

                ieee80211_rx_cooked_monitor(rx, rate);
                break;
                }
        case RX_DROP_UNUSABLE:
                I802_DEBUG_INC(rx->sdata->local->rx_handlers_drop);
                if (rx->sta)
                        rx->sta->rx_dropped++;
                dev_kfree_skb(rx->skb);
                break;
        case RX_QUEUED:
                I802_DEBUG_INC(rx->sdata->local->rx_handlers_queued);
                break;
        }
}

static void ieee80211_rx_handlers(struct ieee80211_rx_data *rx)
{
        ieee80211_rx_result res = RX_DROP_MONITOR;
        struct sk_buff *skb;

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

        spin_lock(&rx->local->rx_skb_queue.lock);
        if (rx->local->running_rx_handler)
                goto unlock;

        rx->local->running_rx_handler = true;

        while ((skb = __skb_dequeue(&rx->local->rx_skb_queue))) {
                spin_unlock(&rx->local->rx_skb_queue.lock);

                /*
                 * all the other fields are valid across frames
                 * that belong to an aMPDU since they are on the
                 * same TID from the same station
                 */
                rx->skb = skb;
                rx->flags = 0;

                CALL_RXH(ieee80211_rx_h_decrypt)
                CALL_RXH(ieee80211_rx_h_check_more_data)
                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(&rx->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_mgmt_check)
                CALL_RXH(ieee80211_rx_h_action)
                CALL_RXH(ieee80211_rx_h_userspace_mgmt)
                CALL_RXH(ieee80211_rx_h_action_return)
                CALL_RXH(ieee80211_rx_h_mgmt)

 rxh_next:
                ieee80211_rx_handlers_result(rx, res);
                spin_lock(&rx->local->rx_skb_queue.lock);
#undef CALL_RXH
        }

        rx->local->running_rx_handler = false;

 unlock:
        spin_unlock(&rx->local->rx_skb_queue.lock);
}

static void ieee80211_invoke_rx_handlers(struct ieee80211_rx_data *rx)
{
        ieee80211_rx_result res = RX_DROP_MONITOR;

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

        CALL_RXH(ieee80211_rx_h_passive_scan)
        CALL_RXH(ieee80211_rx_h_check)

        ieee80211_rx_reorder_ampdu(rx);

        ieee80211_rx_handlers(rx);
        return;

 rxh_next:
        ieee80211_rx_handlers_result(rx, res);

#undef CALL_RXH
}

/*
 * This function makes calls into the RX path, therefore
 * it has to be invoked under RCU read lock.
 */
void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid)
{
        struct ieee80211_rx_data rx = {
                .sta = sta,
                .sdata = sta->sdata,
                .local = sta->local,
                .queue = tid,
        };
        struct tid_ampdu_rx *tid_agg_rx;

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

        spin_lock(&tid_agg_rx->reorder_lock);
        ieee80211_sta_reorder_release(&sta->local->hw, tid_agg_rx);
        spin_unlock(&tid_agg_rx->reorder_lock);

        ieee80211_rx_handlers(&rx);
}

/* main receive path */

static int prepare_for_handlers(struct ieee80211_rx_data *rx,
                                struct ieee80211_hdr *hdr)
{
        struct ieee80211_sub_if_data *sdata = rx->sdata;
        struct sk_buff *skb = rx->skb;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
        u8 *bssid = ieee80211_get_bssid(hdr, skb->len, sdata->vif.type);
        int multicast = is_multicast_ether_addr(hdr->addr1);

        switch (sdata->vif.type) {
        case NL80211_IFTYPE_STATION:
                if (!bssid && !sdata->u.mgd.use_4addr)
                        return 0;
                if (!multicast &&
                    compare_ether_addr(sdata->vif.addr, hdr->addr1) != 0) {
                        if (!(sdata->dev->flags & IFF_PROMISC))
                                return 0;
                        status->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.ibss.bssid)) {
                        if (!(status->rx_flags & IEEE80211_RX_IN_SCAN))
                                return 0;
                        status->rx_flags &= ~IEEE80211_RX_RA_MATCH;
                } else if (!multicast &&
                           compare_ether_addr(sdata->vif.addr,
                                              hdr->addr1) != 0) {
                        if (!(sdata->dev->flags & IFF_PROMISC))
                                return 0;
                        status->rx_flags &= ~IEEE80211_RX_RA_MATCH;
                } else if (!rx->sta) {
                        int rate_idx;
                        if (status->flag & RX_FLAG_HT)
                                rate_idx = 0; /* TODO: HT rates */
                        else
                                rate_idx = status->rate_idx;
                        rx->sta = ieee80211_ibss_add_sta(sdata, bssid,
                                        hdr->addr2, BIT(rate_idx), GFP_ATOMIC);
                }
                break;
        case NL80211_IFTYPE_MESH_POINT:
                if (!multicast &&
                    compare_ether_addr(sdata->vif.addr,
                                       hdr->addr1) != 0) {
                        if (!(sdata->dev->flags & IFF_PROMISC))
                                return 0;

                        status->rx_flags &= ~IEEE80211_RX_RA_MATCH;
                }
                break;
        case NL80211_IFTYPE_AP_VLAN:
        case NL80211_IFTYPE_AP:
                if (!bssid) {
                        if (compare_ether_addr(sdata->vif.addr,
                                               hdr->addr1))
                                return 0;
                } else if (!ieee80211_bssid_match(bssid,
                                        sdata->vif.addr)) {
                        if (!(status->rx_flags & IEEE80211_RX_IN_SCAN))
                                return 0;
                        status->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;
        default:
                /* should never get here */
                WARN_ON(1);
                break;
        }

        return 1;
}

/*
 * This function returns whether or not the SKB
 * was destined for RX processing or not, which,
 * if consume is true, is equivalent to whether
 * or not the skb was consumed.
 */
static bool ieee80211_prepare_and_rx_handle(struct ieee80211_rx_data *rx,
                                            struct sk_buff *skb, bool consume)
{
        struct ieee80211_local *local = rx->local;
        struct ieee80211_sub_if_data *sdata = rx->sdata;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
        struct ieee80211_hdr *hdr = (void *)skb->data;
        int prepares;

        rx->skb = skb;
        status->rx_flags |= IEEE80211_RX_RA_MATCH;
        prepares = prepare_for_handlers(rx, hdr);

        if (!prepares)
                return false;

        if (status->flag & RX_FLAG_MMIC_ERROR) {
                if (status->rx_flags & IEEE80211_RX_RA_MATCH)
                        ieee80211_rx_michael_mic_report(hdr, rx);
                return false;
        }

        if (!consume) {
                skb = skb_copy(skb, GFP_ATOMIC);
                if (!skb) {
                        if (net_ratelimit())
                                wiphy_debug(local->hw.wiphy,
                                        "failed to copy multicast frame for %s\n",
                                        sdata->name);
                        return true;
                }

                rx->skb = skb;
        }

        ieee80211_invoke_rx_handlers(rx);
        return true;
}

/*
 * 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 = IEEE80211_SKB_RXCB(skb);
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_sub_if_data *sdata;
        struct ieee80211_hdr *hdr;
        __le16 fc;
        struct ieee80211_rx_data rx;
        struct ieee80211_sub_if_data *prev;
        struct sta_info *sta, *tmp, *prev_sta;
        int err = 0;

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

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

        if (unlikely(test_bit(SCAN_HW_SCANNING, &local->scanning) ||
                     test_bit(SCAN_OFF_CHANNEL, &local->scanning)))
                status->rx_flags |= IEEE80211_RX_IN_SCAN;

        if (ieee80211_is_mgmt(fc))
                err = skb_linearize(skb);
        else
                err = !pskb_may_pull(skb, ieee80211_hdrlen(fc));

        if (err) {
                dev_kfree_skb(skb);
                return;
        }

        hdr = (struct ieee80211_hdr *)skb->data;
        ieee80211_parse_qos(&rx);
        ieee80211_verify_alignment(&rx);

        if (ieee80211_is_data(fc)) {
                prev_sta = NULL;

                for_each_sta_info(local, hdr->addr2, sta, tmp) {
                        if (!prev_sta) {
                                prev_sta = sta;
                                continue;
                        }

                        rx.sta = prev_sta;
                        rx.sdata = prev_sta->sdata;
                        ieee80211_prepare_and_rx_handle(&rx, skb, false);

                        prev_sta = sta;
                }

                if (prev_sta) {
                        rx.sta = prev_sta;
                        rx.sdata = prev_sta->sdata;

                        if (ieee80211_prepare_and_rx_handle(&rx, skb, true))
                                return;
                        goto out;
                }
        }

        prev = NULL;

        list_for_each_entry_rcu(sdata, &local->interfaces, list) {
                if (!ieee80211_sdata_running(sdata))
                        continue;

                if (sdata->vif.type == NL80211_IFTYPE_MONITOR ||
                    sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
                        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;
                }

                rx.sta = sta_info_get_bss(prev, hdr->addr2);
                rx.sdata = prev;
                ieee80211_prepare_and_rx_handle(&rx, skb, false);

                prev = sdata;
        }

        if (prev) {
                rx.sta = sta_info_get_bss(prev, hdr->addr2);
                rx.sdata = prev;

                if (ieee80211_prepare_and_rx_handle(&rx, skb, true))
                        return;
        }

 out:
        dev_kfree_skb(skb);
}

/*
 * This is the receive path handler. It is called by a low level driver when an
 * 802.11 MPDU is received from the hardware.
 */
void ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb)
{
        struct ieee80211_local *local = hw_to_local(hw);
        struct ieee80211_rate *rate = NULL;
        struct ieee80211_supported_band *sband;
        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);

        WARN_ON_ONCE(softirq_count() == 0);

        if (WARN_ON(status->band < 0 ||
                    status->band >= IEEE80211_NUM_BANDS))
                goto drop;

        sband = local->hw.wiphy->bands[status->band];
        if (WARN_ON(!sband))
                goto drop;

        /*
         * If we're suspending, it is possible although not too likely
         * that we'd be receiving frames after having already partially
         * quiesced the stack. We can't process such frames then since
         * that might, for example, cause stations to be added or other
         * driver callbacks be invoked.
         */
        if (unlikely(local->quiescing || local->suspended))
                goto drop;

        /*
         * The same happens when we're not even started,
         * but that's worth a warning.
         */
        if (WARN_ON(!local->started))
                goto drop;

        if (likely(!(status->flag & RX_FLAG_FAILED_PLCP_CRC))) {
                /*
                 * Validate the rate, unless a PLCP error means that
                 * we probably can't have a valid rate here anyway.
                 */

                if (status->flag & RX_FLAG_HT) {
                        /*
                         * rate_idx is MCS index, which can be [0-76]
                         * as documented on:
                         *
                         * http://wireless.kernel.org/en/developers/Documentation/ieee80211/802.11n
                         *
                         * Anything else would be some sort of driver or
                         * hardware error. The driver should catch hardware
                         * errors.
                         */
                        if (WARN((status->rate_idx < 0 ||
                                 status->rate_idx > 76),
                                 "Rate marked as an HT rate but passed "
                                 "status->rate_idx is not "
                                 "an MCS index [0-76]: %d (0x%02x)\n",
                                 status->rate_idx,
                                 status->rate_idx))
                                goto drop;
                } else {
                        if (WARN_ON(status->rate_idx < 0 ||
                                    status->rate_idx >= sband->n_bitrates))
                                goto drop;
                        rate = &sband->bitrates[status->rate_idx];
                }
        }

        status->rx_flags = 0;

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

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

        __ieee80211_rx_handle_packet(hw, skb);

        rcu_read_unlock();

        return;
 drop:
        kfree_skb(skb);
}
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_local *local = hw_to_local(hw);

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

        skb->pkt_type = IEEE80211_RX_MSG;
        skb_queue_tail(&local->skb_queue, skb);
        tasklet_schedule(&local->tasklet);
}
EXPORT_SYMBOL(ieee80211_rx_irqsafe);