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 sk_buff_head *frames)
{
	struct sk_buff *skb = tid_agg_rx->reorder_buf[index];

	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;
	__skb_queue_tail(frames, 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,
					     struct sk_buff_head *frames)
{
	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, frames);
	}
}

/*
 * 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,
					  struct sk_buff_head *frames)
{
	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, frames);

			/*
			 * 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, frames);
		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 sk_buff_head *frames)
{
	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,
						 frames);
	}

	/* 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, frames);

 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_head *frames)
{
	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, frames))
		return;

 dont_reorder:
	__skb_queue_tail(frames, 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) &&
	    (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))
			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))
			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 sk_buff_head *frames)
{
	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,
						 frames);
		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:
	case WLAN_CATEGORY_MESH_PATH_SEL:
		if (!ieee80211_vif_is_mesh(&sdata->vif))
			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,
				  struct sk_buff_head *frames)
{
	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);

	while ((skb = __skb_dequeue(frames))) {
		/*
		 * 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)

		/* special treatment -- needs the queue */
		res = ieee80211_rx_h_ctrl(rx, frames);
		if (res != RX_CONTINUE)
			goto rxh_next;

		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);

#undef CALL_RXH
	}
}

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

	__skb_queue_head_init(&reorder_release);

#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, &reorder_release);

	ieee80211_rx_handlers(rx, &reorder_release);
	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 sk_buff_head frames;
	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;

	__skb_queue_head_init(&frames);

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

	ieee80211_rx_handlers(&rx, &frames);
}

/* 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);