rx.c 69.2 KB
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/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2005-2006, Devicescape Software, Inc.
 * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
 * Copyright 2007	Johannes Berg <johannes@sipsolutions.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

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

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

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

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

	return skb;
}

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static inline int should_drop_frame(struct sk_buff *skb,
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				    int present_fcs_len,
				    int radiotap_len)
{
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	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
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	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
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	if (status->flag & (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
		return 1;
	if (unlikely(skb->len < 16 + present_fcs_len + radiotap_len))
		return 1;
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	if (ieee80211_is_ctl(hdr->frame_control) &&
	    !ieee80211_is_pspoll(hdr->frame_control) &&
	    !ieee80211_is_back_req(hdr->frame_control))
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		return 1;
	return 0;
}

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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;
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	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
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		len += 1;
	if (local->hw.flags & IEEE80211_HW_NOISE_DBM)
		len += 1;

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

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

	return len;
}

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/*
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 * 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)
{
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	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
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	struct ieee80211_radiotap_header *rthdr;
	unsigned char *pos;

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

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

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

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

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

	/* IEEE80211_RADIOTAP_FLAGS */
	if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
		*pos |= IEEE80211_RADIOTAP_F_FCS;
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	if (status->flag & (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))
		*pos |= IEEE80211_RADIOTAP_F_BADFCS;
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	if (status->flag & RX_FLAG_SHORTPRE)
		*pos |= IEEE80211_RADIOTAP_F_SHORTPRE;
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	pos++;

	/* IEEE80211_RADIOTAP_RATE */
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	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;
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	} else {
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		rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_RATE);
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		*pos = rate->bitrate / 5;
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	}
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	pos++;

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

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

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

	/* IEEE80211_RADIOTAP_LOCK_QUALITY is missing */

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

	/* IEEE80211_RADIOTAP_DB_ANTNOISE is not used */

	/* IEEE80211_RADIOTAP_RX_FLAGS */
	/* ensure 2 byte alignment for the 2 byte field as required */
	if ((pos - (unsigned char *)rthdr) & 1)
		pos++;
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	if (status->flag & RX_FLAG_FAILED_PLCP_CRC)
		*(__le16 *)pos |= cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADPLCP);
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	pos += 2;
}

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/*
 * 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,
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		     struct ieee80211_rate *rate)
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{
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	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(origskb);
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	struct ieee80211_sub_if_data *sdata;
	int needed_headroom = 0;
	struct sk_buff *skb, *skb2;
	struct net_device *prev_dev = NULL;
	int present_fcs_len = 0;
	int rtap_len = 0;

	/*
	 * First, we may need to make a copy of the skb because
	 *  (1) we need to modify it for radiotap (if not present), and
	 *  (2) the other RX handlers will modify the skb we got.
	 *
	 * We don't need to, of course, if we aren't going to return
	 * the SKB because it has a bad FCS/PLCP checksum.
	 */
	if (status->flag & RX_FLAG_RADIOTAP)
		rtap_len = ieee80211_get_radiotap_len(origskb->data);
	else
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		/* room for the radiotap header based on driver features */
		needed_headroom = ieee80211_rx_radiotap_len(local, status);
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	if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)
		present_fcs_len = FCS_LEN;

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

		return remove_monitor_info(local, origskb, rtap_len);
	}

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	if (should_drop_frame(origskb, present_fcs_len, rtap_len)) {
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		/* 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 &&
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		    pskb_expand_head(skb, needed_headroom, 0, GFP_ATOMIC)) {
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			dev_kfree_skb(skb);
			return NULL;
		}
	} else {
		/*
		 * Need to make a copy and possibly remove radiotap header
		 * and FCS from the original.
		 */
		skb = skb_copy_expand(origskb, needed_headroom, 0, GFP_ATOMIC);

		origskb = remove_monitor_info(local, origskb, rtap_len);

		if (!skb)
			return origskb;
	}

	/* if necessary, prepend radiotap information */
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	if (!(status->flag & RX_FLAG_RADIOTAP))
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		ieee80211_add_rx_radiotap_header(local, skb, rate,
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						 needed_headroom);
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	skb_reset_mac_header(skb);
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	skb->ip_summed = CHECKSUM_UNNECESSARY;
	skb->pkt_type = PACKET_OTHERHOST;
	skb->protocol = htons(ETH_P_802_2);

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

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

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

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

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

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

	return origskb;
}


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

	/* does the frame have a qos control field? */
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	if (ieee80211_is_data_qos(hdr->frame_control)) {
		u8 *qc = ieee80211_get_qos_ctl(hdr);
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		/* frame has qos control */
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		tid = *qc & IEEE80211_QOS_CTL_TID_MASK;
		if (*qc & IEEE80211_QOS_CONTROL_A_MSDU_PRESENT)
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			rx->flags |= IEEE80211_RX_AMSDU;
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		else
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			rx->flags &= ~IEEE80211_RX_AMSDU;
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	} else {
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		/*
		 * 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;
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	}
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	rx->queue = tid;
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	/* 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;
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}
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/**
 * 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).
 *
 * 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)
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{
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	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
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	int hdrlen;

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#ifndef CONFIG_MAC80211_DEBUG_PACKET_ALIGNMENT
	return;
#endif

	if (WARN_ONCE((unsigned long)rx->skb->data & 1,
		      "unaligned packet at 0x%p\n", rx->skb->data))
		return;

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

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	hdrlen = ieee80211_hdrlen(hdr->frame_control);
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	if (rx->flags & IEEE80211_RX_AMSDU)
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		hdrlen += ETH_HLEN;
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	WARN_ONCE(((unsigned long)(rx->skb->data + hdrlen)) & 3,
		  "unaligned IP payload at 0x%p\n", rx->skb->data + hdrlen);
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}

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/* rx handlers */

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

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

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

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	return RX_CONTINUE;
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}

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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);
}


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static ieee80211_rx_result
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ieee80211_rx_mesh_check(struct ieee80211_rx_data *rx)
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{
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	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
	unsigned int hdrlen = ieee80211_hdrlen(hdr->frame_control);
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	if (ieee80211_is_data(hdr->frame_control)) {
		if (!ieee80211_has_a4(hdr->frame_control))
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			return RX_DROP_MONITOR;
		if (memcmp(hdr->addr4, rx->dev->dev_addr, ETH_ALEN) == 0)
			return RX_DROP_MONITOR;
	}

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

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	if (!rx->sta || sta_plink_state(rx->sta) != PLINK_ESTAB) {
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		struct ieee80211_mgmt *mgmt;
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		if (!ieee80211_is_mgmt(hdr->frame_control))
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			return RX_DROP_MONITOR;

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

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		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) &&
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	    mesh_rmc_check(hdr->addr4, msh_h_get(hdr, hdrlen), rx->sdata))
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		return RX_DROP_MONITOR;
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#undef msh_h_get
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	return RX_CONTINUE;
}
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static ieee80211_rx_result debug_noinline
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ieee80211_rx_h_check(struct ieee80211_rx_data *rx)
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{
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	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
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	/* Drop duplicate 802.11 retransmissions (IEEE 802.11 Chap. 9.2.9) */
	if (rx->sta && !is_multicast_ether_addr(hdr->addr1)) {
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		if (unlikely(ieee80211_has_retry(hdr->frame_control) &&
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			     rx->sta->last_seq_ctrl[rx->queue] ==
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			     hdr->seq_ctrl)) {
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			if (rx->flags & IEEE80211_RX_RA_MATCH) {
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				rx->local->dot11FrameDuplicateCount++;
				rx->sta->num_duplicates++;
			}
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			return RX_DROP_MONITOR;
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		} else
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			rx->sta->last_seq_ctrl[rx->queue] = hdr->seq_ctrl;
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	}

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

	/* Drop disallowed frame classes based on STA auth/assoc state;
	 * IEEE 802.11, Chap 5.5.
	 *
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	 * mac80211 filters only based on association state, i.e. it drops
	 * Class 3 frames from not associated stations. hostapd sends
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	 * deauth/disassoc frames when needed. In addition, hostapd is
	 * responsible for filtering on both auth and assoc states.
	 */
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	if (ieee80211_vif_is_mesh(&rx->sdata->vif))
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		return ieee80211_rx_mesh_check(rx);

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

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		return RX_DROP_MONITOR;
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	}

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	return RX_CONTINUE;
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}


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static ieee80211_rx_result debug_noinline
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ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
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{
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	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
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	int keyidx;
	int hdrlen;
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	ieee80211_rx_result result = RX_DROP_UNUSABLE;
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	struct ieee80211_key *stakey = NULL;
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	int mmie_keyidx = -1;
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	/*
	 * Key selection 101
	 *
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	 * There are four types of keys:
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	 *  - GTK (group keys)
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	 *  - IGTK (group keys for management frames)
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	 *  - 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
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	 * 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.
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	 *
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	 * 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.
	 *
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	 * There is also a slight problem in IBSS mode: GTKs are negotiated
	 * with each station, that is something we don't currently handle.
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	 * The spec seems to expect that one negotiates the same key with
	 * every station but there's no such requirement; VLANs could be
	 * possible.
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	 */

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

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

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	if (!is_multicast_ether_addr(hdr->addr1) && stakey) {
		rx->key = stakey;
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		/* Skip decryption if the frame is not protected. */
		if (!ieee80211_has_protected(hdr->frame_control))
			return RX_CONTINUE;
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	} else if (mmie_keyidx >= 0) {
		/* Broadcast/multicast robust management frame / BIP */
		if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
		    (rx->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 */
		rx->key = rcu_dereference(rx->sdata->keys[mmie_keyidx]);
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	} else if (!ieee80211_has_protected(hdr->frame_control)) {
		/*
		 * 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;
		if (ieee80211_is_mgmt(hdr->frame_control) &&
		    is_multicast_ether_addr(hdr->addr1) &&
		    (key = rcu_dereference(rx->sdata->default_mgmt_key)))
			rx->key = key;
		else if ((key = rcu_dereference(rx->sdata->default_key)))
			rx->key = key;
		return RX_CONTINUE;
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	} else {
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		/*
		 * 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?
		 */
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		if ((rx->status->flag & RX_FLAG_DECRYPTED) &&
		    (rx->status->flag & RX_FLAG_IV_STRIPPED))
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			return RX_CONTINUE;
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		hdrlen = ieee80211_hdrlen(hdr->frame_control);
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		if (rx->skb->len < 8 + hdrlen)
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			return RX_DROP_UNUSABLE; /* TODO: count this? */
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		/*
		 * no need to call ieee80211_wep_get_keyidx,
		 * it verifies a bunch of things we've done already
		 */
		keyidx = rx->skb->data[hdrlen + 3] >> 6;

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		rx->key = rcu_dereference(rx->sdata->keys[keyidx]);
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		/*
		 * 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.
		 */
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		if (rx->key && rx->key->conf.alg != ALG_WEP &&
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		    !is_multicast_ether_addr(hdr->addr1))
			rx->key = NULL;
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	}

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

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

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	switch (rx->key->conf.alg) {
	case ALG_WEP:
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		result = ieee80211_crypto_wep_decrypt(rx);
		break;
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	case ALG_TKIP:
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		result = ieee80211_crypto_tkip_decrypt(rx);
		break;
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	case ALG_CCMP:
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		result = ieee80211_crypto_ccmp_decrypt(rx);
		break;
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	case ALG_AES_CMAC:
		result = ieee80211_crypto_aes_cmac_decrypt(rx);
		break;
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	}

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

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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;
}

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static void ap_sta_ps_start(struct sta_info *sta)
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{
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	struct ieee80211_sub_if_data *sdata = sta->sdata;
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	struct ieee80211_local *local = sdata->local;
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	atomic_inc(&sdata->bss->num_sta_ps);
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	set_and_clear_sta_flags(sta, WLAN_STA_PS, WLAN_STA_PSPOLL);
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	drv_sta_notify(local, &sdata->vif, STA_NOTIFY_SLEEP, &sta->sta);
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#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
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	printk(KERN_DEBUG "%s: STA %pM aid %d enters power save mode\n",
	       sdata->dev->name, sta->sta.addr, sta->sta.aid);
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#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
}

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static int ap_sta_ps_end(struct sta_info *sta)
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{
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	struct ieee80211_sub_if_data *sdata = sta->sdata;
	struct ieee80211_local *local = sdata->local;
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	int sent, buffered;
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	atomic_dec(&sdata->bss->num_sta_ps);
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	clear_sta_flags(sta, WLAN_STA_PS | WLAN_STA_PSPOLL);
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	drv_sta_notify(local, &sdata->vif, STA_NOTIFY_AWAKE, &sta->sta);
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	if (!skb_queue_empty(&sta->ps_tx_buf))
		sta_info_clear_tim_bit(sta);

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#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
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	printk(KERN_DEBUG "%s: STA %pM aid %d exits power save mode\n",
	       sdata->dev->name, sta->sta.addr, sta->sta.aid);
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#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
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	/* Send all buffered frames to the station */
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	sent = ieee80211_add_pending_skbs(local, &sta->tx_filtered);
	buffered = ieee80211_add_pending_skbs(local, &sta->ps_tx_buf);
	sent += buffered;
	local->total_ps_buffered -= buffered;

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#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
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	printk(KERN_DEBUG "%s: STA %pM aid %d sending %d filtered/%d PS frames "
	       "since STA not sleeping anymore\n", sdata->dev->name,
	       sta->sta.addr, sta->sta.aid, sent - buffered, buffered);
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#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */

	return sent;
}

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static ieee80211_rx_result debug_noinline
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ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
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{
	struct sta_info *sta = rx->sta;
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	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
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	if (!sta)
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		return RX_CONTINUE;
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	/* Update last_rx only for IBSS packets which are for the current
	 * BSSID to avoid keeping the current IBSS network alive in cases where
	 * other STAs are using different BSSID. */
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	if (rx->sdata->vif.type == NL80211_IFTYPE_ADHOC) {
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		u8 *bssid = ieee80211_get_bssid(hdr, rx->skb->len,
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						NL80211_IFTYPE_ADHOC);
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		if (compare_ether_addr(bssid, rx->sdata->u.ibss.bssid) == 0)
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			sta->last_rx = jiffies;
	} else
	if (!is_multicast_ether_addr(hdr->addr1) ||
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	    rx->sdata->vif.type == NL80211_IFTYPE_STATION) {
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		/* Update last_rx only for unicast frames in order to prevent
		 * the Probe Request frames (the only broadcast frames from a
		 * STA in infrastructure mode) from keeping a connection alive.
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		 * Mesh beacons will update last_rx when if they are found to
		 * match the current local configuration when processed.
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		 */
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		if (rx->sdata->vif.type == NL80211_IFTYPE_STATION &&
		    ieee80211_is_beacon(hdr->frame_control)) {
			rx->sdata->u.mgd.last_beacon = jiffies;
		} else
			sta->last_rx = jiffies;
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	}

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	if (!(rx->flags & IEEE80211_RX_RA_MATCH))
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		return RX_CONTINUE;
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	if (rx->sdata->vif.type == NL80211_IFTYPE_STATION)
		ieee80211_sta_rx_notify(rx->sdata, hdr);

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	sta->rx_fragments++;
	sta->rx_bytes += rx->skb->len;
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	sta->last_signal = rx->status->signal;
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	sta->last_qual = rx->status->qual;
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	sta->last_noise = rx->status->noise;
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	/*
	 * Change STA power saving mode only at the end of a frame
	 * exchange sequence.
	 */
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	if (!ieee80211_has_morefrags(hdr->frame_control) &&
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	    (rx->sdata->vif.type == NL80211_IFTYPE_AP ||
	     rx->sdata->vif.type == NL80211_IFTYPE_AP_VLAN)) {
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		if (test_sta_flags(sta, WLAN_STA_PS)) {
			/*
			 * 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))
				rx->sent_ps_buffered += ap_sta_ps_end(sta);
		} else {
			if (ieee80211_has_pm(hdr->frame_control))
				ap_sta_ps_start(sta);
		}
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	}

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

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	return RX_CONTINUE;
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} /* 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)) {
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#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
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		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 "
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		       "addr1=%pM addr2=%pM\n",
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		       sdata->dev->name, idx,
		       jiffies - entry->first_frag_time, entry->seq,
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		       entry->last_frag, hdr->addr1, hdr->addr2);
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#endif
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		__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,
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			  unsigned int frag, unsigned int seq,
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			  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;

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		f_hdr = (struct ieee80211_hdr *)entry->skb_list.next->data;
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		/*
		 * Check ftype and addresses are equal, else check next fragment
		 */
		if (((hdr->frame_control ^ f_hdr->frame_control) &
		     cpu_to_le16(IEEE80211_FCTL_FTYPE)) ||
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		    compare_ether_addr(hdr->addr1, f_hdr->addr1) != 0 ||
		    compare_ether_addr(hdr->addr2, f_hdr->addr2) != 0)
			continue;

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

	return NULL;
}

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

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

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

	seq = (sc & IEEE80211_SCTL_SEQ) >> 4;

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

	/* 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.
	 */
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	entry = ieee80211_reassemble_find(rx->sdata, frag, seq, rx->queue, hdr);
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	if (!entry) {
		I802_DEBUG_INC(rx->local->rx_handlers_drop_defrag);
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		return RX_DROP_MONITOR;
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	}

	/* 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;
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		if (!rx->key || rx->key->conf.alg != ALG_CCMP)
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			return RX_DROP_UNUSABLE;
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		memcpy(pn, entry->last_pn, CCMP_PN_LEN);
		for (i = CCMP_PN_LEN - 1; i >= 0; i--) {
			pn[i]++;
			if (pn[i])
				break;
		}
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		rpn = rx->key->u.ccmp.rx_pn[rx->queue];
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		if (memcmp(pn, rpn, CCMP_PN_LEN))
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			return RX_DROP_UNUSABLE;
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		memcpy(entry->last_pn, pn, CCMP_PN_LEN);
	}

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

	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);
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			return RX_DROP_UNUSABLE;
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		}
	}
	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 */
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	rx->flags |= IEEE80211_RX_FRAGMENTED;
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 out:
	if (rx->sta)
		rx->sta->rx_packets++;
	if (is_multicast_ether_addr(hdr->addr1))
		rx->local->dot11MulticastReceivedFrameCount++;
	else
		ieee80211_led_rx(rx->local);
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	return RX_CONTINUE;
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}

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static ieee80211_rx_result debug_noinline
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ieee80211_rx_h_ps_poll(struct ieee80211_rx_data *rx)
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{
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	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(rx->dev);
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	struct sk_buff *skb;
	int no_pending_pkts;
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	__le16 fc = ((struct ieee80211_hdr *)rx->skb->data)->frame_control;
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	if (likely(!rx->sta || !ieee80211_is_pspoll(fc) ||
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		   !(rx->flags & IEEE80211_RX_RA_MATCH)))
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		return RX_CONTINUE;
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	if ((sdata->vif.type != NL80211_IFTYPE_AP) &&
	    (sdata->vif.type != NL80211_IFTYPE_AP_VLAN))
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		return RX_DROP_UNUSABLE;
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	skb = skb_dequeue(&rx->sta->tx_filtered);
	if (!skb) {
		skb = skb_dequeue(&rx->sta->ps_tx_buf);
		if (skb)
			rx->local->total_ps_buffered--;
	}
	no_pending_pkts = skb_queue_empty(&rx->sta->tx_filtered) &&
		skb_queue_empty(&rx->sta->ps_tx_buf);

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

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		/*
		 * Tell TX path to send one frame even though the STA may
		 * still remain is PS mode after this frame exchange.
		 */
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		set_sta_flags(rx->sta, WLAN_STA_PSPOLL);
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#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
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		printk(KERN_DEBUG "STA %pM aid %d: PS Poll (entries after %d)\n",
		       rx->sta->sta.addr, rx->sta->sta.aid,
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		       skb_queue_len(&rx->sta->ps_tx_buf));
#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */

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

		dev_queue_xmit(skb);

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

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

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	return RX_QUEUED;
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}

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static ieee80211_rx_result debug_noinline
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ieee80211_rx_h_remove_qos_control(struct ieee80211_rx_data *rx)
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{
	u8 *data = rx->skb->data;
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	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)data;
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	if (!ieee80211_is_data_qos(hdr->frame_control))
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		return RX_CONTINUE;
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	/* remove the qos control field, update frame type and meta-data */