/*
   * HT handling
   *
   * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
   * Copyright 2002-2005, Instant802 Networks, Inc.
   * Copyright 2005-2006, Devicescape Software, Inc.
   * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
   * Copyright 2007, Michael Wu <flamingice@sourmilk.net>

   * Copyright 2007-2010, Intel Corporation

   * Copyright(c) 2015-2017 Intel Deutschland GmbH

   * Copyright (C) 2018 Intel Corporation

   *
   * 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/ieee80211.h>

  #include <linux/slab.h>

  #include <linux/export.h>

  #include <net/mac80211.h>
  #include "ieee80211_i.h"

  #include "driver-ops.h"

  #include "wme.h"

  /**

   * DOC: TX A-MPDU aggregation

   *
   * Aggregation on the TX side requires setting the hardware flag

   * %IEEE80211_HW_AMPDU_AGGREGATION. The driver will then be handed
   * packets with a flag indicating A-MPDU aggregation. The driver
   * or device is responsible for actually aggregating the frames,
   * as well as deciding how many and which to aggregate.

   *

   * When TX aggregation is started by some subsystem (usually the rate
   * control algorithm would be appropriate) by calling the
   * ieee80211_start_tx_ba_session() function, the driver will be
   * notified via its @ampdu_action function, with the
   * %IEEE80211_AMPDU_TX_START action.

   *
   * In response to that, the driver is later required to call the

   * ieee80211_start_tx_ba_cb_irqsafe() function, which will really
   * start the aggregation session after the peer has also responded.
   * If the peer responds negatively, the session will be stopped
   * again right away. Note that it is possible for the aggregation
   * session to be stopped before the driver has indicated that it
   * is done setting it up, in which case it must not indicate the
   * setup completion.

   *

   * Also note that, since we also need to wait for a response from
   * the peer, the driver is notified of the completion of the
   * handshake by the %IEEE80211_AMPDU_TX_OPERATIONAL action to the
   * @ampdu_action callback.
   *
   * Similarly, when the aggregation session is stopped by the peer
   * or something calling ieee80211_stop_tx_ba_session(), the driver's
   * @ampdu_action function will be called with the action
   * %IEEE80211_AMPDU_TX_STOP. In this case, the call must not fail,
   * and the driver must later call ieee80211_stop_tx_ba_cb_irqsafe().

   * Note that the sta can get destroyed before the BA tear down is
   * complete.

   */

  static void ieee80211_send_addba_request(struct ieee80211_sub_if_data *sdata,
  					 const u8 *da, u16 tid,
  					 u8 dialog_token, u16 start_seq_num,
  					 u16 agg_size, u16 timeout)
  {
  	struct ieee80211_local *local = sdata->local;

  	struct sk_buff *skb;
  	struct ieee80211_mgmt *mgmt;
  	u16 capab;
  
  	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);

  	if (!skb)

  		return;

  	skb_reserve(skb, local->hw.extra_tx_headroom);

  	mgmt = skb_put_zero(skb, 24);

  	memcpy(mgmt->da, da, ETH_ALEN);

  	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);

  	if (sdata->vif.type == NL80211_IFTYPE_AP ||

  	    sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
  	    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)

  		memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);

  	else if (sdata->vif.type == NL80211_IFTYPE_STATION)
  		memcpy(mgmt->bssid, sdata->u.mgd.bssid, ETH_ALEN);

  	else if (sdata->vif.type == NL80211_IFTYPE_ADHOC)
  		memcpy(mgmt->bssid, sdata->u.ibss.bssid, ETH_ALEN);

  
  	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
  					  IEEE80211_STYPE_ACTION);
  
  	skb_put(skb, 1 + sizeof(mgmt->u.action.u.addba_req));
  
  	mgmt->u.action.category = WLAN_CATEGORY_BACK;
  	mgmt->u.action.u.addba_req.action_code = WLAN_ACTION_ADDBA_REQ;
  
  	mgmt->u.action.u.addba_req.dialog_token = dialog_token;

  	capab = (u16)(1 << 0);		/* bit 0 A-MSDU support */
  	capab |= (u16)(1 << 1);		/* bit 1 aggregation policy */

  	capab |= (u16)(tid << 2); 	/* bit 5:2 TID number */
  	capab |= (u16)(agg_size << 6);	/* bit 15:6 max size of aggergation */
  
  	mgmt->u.action.u.addba_req.capab = cpu_to_le16(capab);
  
  	mgmt->u.action.u.addba_req.timeout = cpu_to_le16(timeout);
  	mgmt->u.action.u.addba_req.start_seq_num =
  					cpu_to_le16(start_seq_num << 4);

  	ieee80211_tx_skb(sdata, skb);

  }

  void ieee80211_send_bar(struct ieee80211_vif *vif, u8 *ra, u16 tid, u16 ssn)

  {

  	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);

  	struct ieee80211_local *local = sdata->local;
  	struct sk_buff *skb;
  	struct ieee80211_bar *bar;
  	u16 bar_control = 0;
  
  	skb = dev_alloc_skb(sizeof(*bar) + local->hw.extra_tx_headroom);

  	if (!skb)

  		return;

  	skb_reserve(skb, local->hw.extra_tx_headroom);

  	bar = skb_put_zero(skb, sizeof(*bar));

  	bar->frame_control = cpu_to_le16(IEEE80211_FTYPE_CTL |
  					 IEEE80211_STYPE_BACK_REQ);
  	memcpy(bar->ra, ra, ETH_ALEN);

  	memcpy(bar->ta, sdata->vif.addr, ETH_ALEN);

  	bar_control |= (u16)IEEE80211_BAR_CTRL_ACK_POLICY_NORMAL;
  	bar_control |= (u16)IEEE80211_BAR_CTRL_CBMTID_COMPRESSED_BA;

  	bar_control |= (u16)(tid << IEEE80211_BAR_CTRL_TID_INFO_SHIFT);

  	bar->control = cpu_to_le16(bar_control);
  	bar->start_seq_num = cpu_to_le16(ssn);

  	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |
  					IEEE80211_TX_CTL_REQ_TX_STATUS;

  	ieee80211_tx_skb_tid(sdata, skb, tid);

  }

  EXPORT_SYMBOL(ieee80211_send_bar);

  void ieee80211_assign_tid_tx(struct sta_info *sta, int tid,
  			     struct tid_ampdu_tx *tid_tx)
  {
  	lockdep_assert_held(&sta->ampdu_mlme.mtx);
  	lockdep_assert_held(&sta->lock);
  	rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], tid_tx);
  }

  /*
   * When multiple aggregation sessions on multiple stations
   * are being created/destroyed simultaneously, we need to
   * refcount the global queue stop caused by that in order
   * to not get into a situation where one of the aggregation
   * setup or teardown re-enables queues before the other is
   * ready to handle that.
   *
   * These two functions take care of this issue by keeping
   * a global "agg_queue_stop" refcount.
   */
  static void __acquires(agg_queue)
  ieee80211_stop_queue_agg(struct ieee80211_sub_if_data *sdata, int tid)
  {
  	int queue = sdata->vif.hw_queue[ieee80211_ac_from_tid(tid)];

  	/* we do refcounting here, so don't use the queue reason refcounting */

  	if (atomic_inc_return(&sdata->local->agg_queue_stop[queue]) == 1)
  		ieee80211_stop_queue_by_reason(
  			&sdata->local->hw, queue,

  			IEEE80211_QUEUE_STOP_REASON_AGGREGATION,
  			false);

  	__acquire(agg_queue);
  }
  
  static void __releases(agg_queue)
  ieee80211_wake_queue_agg(struct ieee80211_sub_if_data *sdata, int tid)
  {
  	int queue = sdata->vif.hw_queue[ieee80211_ac_from_tid(tid)];
  
  	if (atomic_dec_return(&sdata->local->agg_queue_stop[queue]) == 0)
  		ieee80211_wake_queue_by_reason(
  			&sdata->local->hw, queue,

  			IEEE80211_QUEUE_STOP_REASON_AGGREGATION,
  			false);

  	__release(agg_queue);
  }

  static void
  ieee80211_agg_stop_txq(struct sta_info *sta, int tid)
  {
  	struct ieee80211_txq *txq = sta->sta.txq[tid];

  	struct ieee80211_sub_if_data *sdata;
  	struct fq *fq;

  	struct txq_info *txqi;
  
  	if (!txq)
  		return;
  
  	txqi = to_txq_info(txq);

  	sdata = vif_to_sdata(txq->vif);
  	fq = &sdata->local->fq;

  
  	/* Lock here to protect against further seqno updates on dequeue */

  	spin_lock_bh(&fq->lock);

  	set_bit(IEEE80211_TXQ_STOP, &txqi->flags);

  	spin_unlock_bh(&fq->lock);

  }
  
  static void
  ieee80211_agg_start_txq(struct sta_info *sta, int tid, bool enable)
  {
  	struct ieee80211_txq *txq = sta->sta.txq[tid];
  	struct txq_info *txqi;
  
  	if (!txq)
  		return;
  
  	txqi = to_txq_info(txq);
  
  	if (enable)
  		set_bit(IEEE80211_TXQ_AMPDU, &txqi->flags);
  	else
  		clear_bit(IEEE80211_TXQ_AMPDU, &txqi->flags);
  
  	clear_bit(IEEE80211_TXQ_STOP, &txqi->flags);

  	local_bh_disable();
  	rcu_read_lock();

  	drv_wake_tx_queue(sta->sdata->local, txqi);

  	rcu_read_unlock();
  	local_bh_enable();

  }

  /*
   * splice packets from the STA's pending to the local pending,
   * requires a call to ieee80211_agg_splice_finish later
   */
  static void __acquires(agg_queue)
  ieee80211_agg_splice_packets(struct ieee80211_sub_if_data *sdata,
  			     struct tid_ampdu_tx *tid_tx, u16 tid)
  {
  	struct ieee80211_local *local = sdata->local;
  	int queue = sdata->vif.hw_queue[ieee80211_ac_from_tid(tid)];
  	unsigned long flags;
  
  	ieee80211_stop_queue_agg(sdata, tid);
  
  	if (WARN(!tid_tx,
  		 "TID %d gone but expected when splicing aggregates from the pending queue
  ",
  		 tid))
  		return;
  
  	if (!skb_queue_empty(&tid_tx->pending)) {
  		spin_lock_irqsave(&local->queue_stop_reason_lock, flags);
  		/* copy over remaining packets */
  		skb_queue_splice_tail_init(&tid_tx->pending,
  					   &local->pending[queue]);
  		spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);
  	}
  }
  
  static void __releases(agg_queue)
  ieee80211_agg_splice_finish(struct ieee80211_sub_if_data *sdata, u16 tid)
  {
  	ieee80211_wake_queue_agg(sdata, tid);
  }
  
  static void ieee80211_remove_tid_tx(struct sta_info *sta, int tid)
  {
  	struct tid_ampdu_tx *tid_tx;
  
  	lockdep_assert_held(&sta->ampdu_mlme.mtx);
  	lockdep_assert_held(&sta->lock);
  
  	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
  
  	/*
  	 * When we get here, the TX path will not be lockless any more wrt.
  	 * aggregation, since the OPERATIONAL bit has long been cleared.
  	 * Thus it will block on getting the lock, if it occurs. So if we
  	 * stop the queue now, we will not get any more packets, and any
  	 * that might be being processed will wait for us here, thereby
  	 * guaranteeing that no packets go to the tid_tx pending queue any
  	 * more.
  	 */
  
  	ieee80211_agg_splice_packets(sta->sdata, tid_tx, tid);
  
  	/* future packets must not find the tid_tx struct any more */
  	ieee80211_assign_tid_tx(sta, tid, NULL);
  
  	ieee80211_agg_splice_finish(sta->sdata, tid);

  	ieee80211_agg_start_txq(sta, tid, false);

  
  	kfree_rcu(tid_tx, rcu_head);
  }

  int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,

  				    enum ieee80211_agg_stop_reason reason)

  {

  	struct ieee80211_local *local = sta->local;

  	struct tid_ampdu_tx *tid_tx;

  	struct ieee80211_ampdu_params params = {
  		.sta = &sta->sta,
  		.tid = tid,
  		.buf_size = 0,
  		.amsdu = false,
  		.timeout = 0,
  		.ssn = 0,
  	};

  	int ret;

  	lockdep_assert_held(&sta->ampdu_mlme.mtx);

  	switch (reason) {
  	case AGG_STOP_DECLINED:
  	case AGG_STOP_LOCAL_REQUEST:
  	case AGG_STOP_PEER_REQUEST:

  		params.action = IEEE80211_AMPDU_TX_STOP_CONT;

  		break;
  	case AGG_STOP_DESTROY_STA:

  		params.action = IEEE80211_AMPDU_TX_STOP_FLUSH;

  		break;
  	default:
  		WARN_ON_ONCE(1);
  		return -EINVAL;
  	}

  	spin_lock_bh(&sta->lock);

  	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
  	if (!tid_tx) {
  		spin_unlock_bh(&sta->lock);
  		return -ENOENT;
  	}

  	/*
  	 * if we're already stopping ignore any new requests to stop
  	 * unless we're destroying it in which case notify the driver
  	 */

  	if (test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
  		spin_unlock_bh(&sta->lock);

  		if (reason != AGG_STOP_DESTROY_STA)
  			return -EALREADY;

  		params.action = IEEE80211_AMPDU_TX_STOP_FLUSH_CONT;
  		ret = drv_ampdu_action(local, sta->sdata, &params);

  		WARN_ON_ONCE(ret);

  		return 0;

  	}

  	if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state)) {
  		/* not even started yet! */

  		ieee80211_assign_tid_tx(sta, tid, NULL);

  		spin_unlock_bh(&sta->lock);

  		kfree_rcu(tid_tx, rcu_head);

  		return 0;
  	}

  	set_bit(HT_AGG_STATE_STOPPING, &tid_tx->state);

  	spin_unlock_bh(&sta->lock);

  	ht_dbg(sta->sdata, "Tx BA session stop requested for %pM tid %u
  ",
  	       sta->sta.addr, tid);

  	del_timer_sync(&tid_tx->addba_resp_timer);

  	del_timer_sync(&tid_tx->session_timer);

  	/*
  	 * After this packets are no longer handed right through
  	 * to the driver but are put onto tid_tx->pending instead,
  	 * with locking to ensure proper access.
  	 */
  	clear_bit(HT_AGG_STATE_OPERATIONAL, &tid_tx->state);

  	/*
  	 * There might be a few packets being processed right now (on
  	 * another CPU) that have already gotten past the aggregation
  	 * check when it was still OPERATIONAL and consequently have
  	 * IEEE80211_TX_CTL_AMPDU set. In that case, this code might
  	 * call into the driver at the same time or even before the
  	 * TX paths calls into it, which could confuse the driver.
  	 *
  	 * Wait for all currently running TX paths to finish before
  	 * telling the driver. New packets will not go through since
  	 * the aggregation session is no longer OPERATIONAL.
  	 */
  	synchronize_net();

  	tid_tx->stop_initiator = reason == AGG_STOP_PEER_REQUEST ?
  					WLAN_BACK_RECIPIENT :
  					WLAN_BACK_INITIATOR;
  	tid_tx->tx_stop = reason == AGG_STOP_LOCAL_REQUEST;

  	ret = drv_ampdu_action(local, sta->sdata, &params);

  
  	/* HW shall not deny going back to legacy */
  	if (WARN_ON(ret)) {

  		/*
  		 * We may have pending packets get stuck in this case...
  		 * Not bothering with a workaround for now.
  		 */

  	}

  	/*
  	 * In the case of AGG_STOP_DESTROY_STA, the driver won't
  	 * necessarily call ieee80211_stop_tx_ba_cb(), so this may
  	 * seem like we can leave the tid_tx data pending forever.
  	 * This is true, in a way, but "forever" is only until the
  	 * station struct is actually destroyed. In the meantime,
  	 * leaving it around ensures that we don't transmit packets
  	 * to the driver on this TID which might confuse it.
  	 */

  
  	return 0;

  }

  /*
   * After sending add Block Ack request we activated a timer until
   * add Block Ack response will arrive from the recipient.
   * If this timer expires sta_addba_resp_timer_expired will be executed.
   */
  static void sta_addba_resp_timer_expired(unsigned long data)
  {
  	/* not an elegant detour, but there is no choice as the timer passes
  	 * only one argument, and both sta_info and TID are needed, so init
  	 * flow in sta_info_create gives the TID as data, while the timer_to_id
  	 * array gives the sta through container_of */
  	u16 tid = *(u8 *)data;

  	struct sta_info *sta = container_of((void *)data,

  		struct sta_info, timer_to_tid[tid]);

  	struct tid_ampdu_tx *tid_tx;

  	/* check if the TID waits for addBA response */

  	rcu_read_lock();
  	tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[tid]);

  	if (!tid_tx ||
  	    test_bit(HT_AGG_STATE_RESPONSE_RECEIVED, &tid_tx->state)) {

  		rcu_read_unlock();

  		ht_dbg(sta->sdata,

  		       "timer expired on %pM tid %d not expecting addBA response
  ",

  		       sta->sta.addr, tid);

  		return;

  	}

  	ht_dbg(sta->sdata, "addBA response timer expired on %pM tid %d
  ",
  	       sta->sta.addr, tid);

  	ieee80211_stop_tx_ba_session(&sta->sta, tid);
  	rcu_read_unlock();

  }

  void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid)

  {

  	struct tid_ampdu_tx *tid_tx;

  	struct ieee80211_local *local = sta->local;
  	struct ieee80211_sub_if_data *sdata = sta->sdata;

  	struct ieee80211_ampdu_params params = {
  		.sta = &sta->sta,
  		.action = IEEE80211_AMPDU_TX_START,
  		.tid = tid,
  		.buf_size = 0,
  		.amsdu = false,
  		.timeout = 0,
  	};

  	int ret;

  	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

  	/*

  	 * Start queuing up packets for this aggregation session.
  	 * We're going to release them once the driver is OK with
  	 * that.

  	 */

  	clear_bit(HT_AGG_STATE_WANT_START, &tid_tx->state);

  	ieee80211_agg_stop_txq(sta, tid);

  	/*

  	 * Make sure no packets are being processed. This ensures that
  	 * we have a valid starting sequence number and that in-flight
  	 * packets have been flushed out and no packets for this TID
  	 * will go into the driver during the ampdu_action call.

  	 */

  	synchronize_net();

  	params.ssn = sta->tid_seq[tid] >> 4;
  	ret = drv_ampdu_action(local, sdata, &params);

  	if (ret) {

  		ht_dbg(sdata,

  		       "BA request denied - HW unavailable for %pM tid %d
  ",
  		       sta->sta.addr, tid);

  		spin_lock_bh(&sta->lock);

  		ieee80211_agg_splice_packets(sdata, tid_tx, tid);

  		ieee80211_assign_tid_tx(sta, tid, NULL);

  		ieee80211_agg_splice_finish(sdata, tid);

  		spin_unlock_bh(&sta->lock);

  		ieee80211_agg_start_txq(sta, tid, false);

  		kfree_rcu(tid_tx, rcu_head);

  		return;
  	}

  	/* activate the timer for the recipient's addBA response */
  	mod_timer(&tid_tx->addba_resp_timer, jiffies + ADDBA_RESP_INTERVAL);

  	ht_dbg(sdata, "activated addBA response timer on %pM tid %d
  ",
  	       sta->sta.addr, tid);

  	spin_lock_bh(&sta->lock);

  	sta->ampdu_mlme.last_addba_req_time[tid] = jiffies;

  	sta->ampdu_mlme.addba_req_num[tid]++;

  	spin_unlock_bh(&sta->lock);

  
  	/* send AddBA request */
  	ieee80211_send_addba_request(sdata, sta->sta.addr, tid,

  				     tid_tx->dialog_token, params.ssn,

  				     IEEE80211_MAX_AMPDU_BUF,

  				     tid_tx->timeout);

  }

  /*
   * After accepting the AddBA Response we activated a timer,
   * resetting it after each frame that we send.
   */
  static void sta_tx_agg_session_timer_expired(unsigned long data)
  {
  	/* not an elegant detour, but there is no choice as the timer passes
  	 * only one argument, and various sta_info are needed here, so init
  	 * flow in sta_info_create gives the TID as data, while the timer_to_id
  	 * array gives the sta through container_of */
  	u8 *ptid = (u8 *)data;
  	u8 *timer_to_id = ptid - *ptid;
  	struct sta_info *sta = container_of(timer_to_id, struct sta_info,
  					 timer_to_tid[0]);

  	struct tid_ampdu_tx *tid_tx;
  	unsigned long timeout;

  	rcu_read_lock();
  	tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[*ptid]);
  	if (!tid_tx || test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
  		rcu_read_unlock();

  		return;

  	}

  
  	timeout = tid_tx->last_tx + TU_TO_JIFFIES(tid_tx->timeout);
  	if (time_is_after_jiffies(timeout)) {
  		mod_timer(&tid_tx->session_timer, timeout);

  		rcu_read_unlock();

  		return;
  	}

  	rcu_read_unlock();

  	ht_dbg(sta->sdata, "tx session timer expired on %pM tid %d
  ",
  	       sta->sta.addr, (u16)*ptid);

  
  	ieee80211_stop_tx_ba_session(&sta->sta, *ptid);
  }

  int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid,
  				  u16 timeout)

  {

  	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
  	struct ieee80211_sub_if_data *sdata = sta->sdata;
  	struct ieee80211_local *local = sdata->local;

  	struct tid_ampdu_tx *tid_tx;

  	int ret = 0;

  	trace_api_start_tx_ba_session(pubsta, tid);

  	if (WARN(sta->reserved_tid == tid,
  		 "Requested to start BA session on reserved tid=%d", tid))
  		return -EINVAL;

  	if (!pubsta->ht_cap.ht_supported)
  		return -EINVAL;

  	if (WARN_ON_ONCE(!local->ops->ampdu_action))

  		return -EINVAL;

  	if ((tid >= IEEE80211_NUM_TIDS) ||

  	    !ieee80211_hw_check(&local->hw, AMPDU_AGGREGATION) ||
  	    ieee80211_hw_check(&local->hw, TX_AMPDU_SETUP_IN_HW))

  		return -EINVAL;

  	if (WARN_ON(tid >= IEEE80211_FIRST_TSPEC_TSID))
  		return -EINVAL;

  	ht_dbg(sdata, "Open BA session requested for %pM tid %u
  ",
  	       pubsta->addr, tid);

  	if (sdata->vif.type != NL80211_IFTYPE_STATION &&

  	    sdata->vif.type != NL80211_IFTYPE_MESH_POINT &&

  	    sdata->vif.type != NL80211_IFTYPE_AP_VLAN &&

  	    sdata->vif.type != NL80211_IFTYPE_AP &&
  	    sdata->vif.type != NL80211_IFTYPE_ADHOC)

  		return -EINVAL;

  	if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) {

  		ht_dbg(sdata,

  		       "BA sessions blocked - Denying BA session request %pM tid %d
  ",
  		       sta->sta.addr, tid);

  		return -EINVAL;

  	}

  	/*
  	 * 802.11n-2009 11.5.1.1: If the initiating STA is an HT STA, is a
  	 * member of an IBSS, and has no other existing Block Ack agreement
  	 * with the recipient STA, then the initiating STA shall transmit a
  	 * Probe Request frame to the recipient STA and shall not transmit an
  	 * ADDBA Request frame unless it receives a Probe Response frame
  	 * from the recipient within dot11ADDBAFailureTimeout.
  	 *
  	 * The probe request mechanism for ADDBA is currently not implemented,
  	 * but we only build up Block Ack session with HT STAs. This information
  	 * is set when we receive a bss info from a probe response or a beacon.
  	 */
  	if (sta->sdata->vif.type == NL80211_IFTYPE_ADHOC &&
  	    !sta->sta.ht_cap.ht_supported) {

  		ht_dbg(sdata,
  		       "BA request denied - IBSS STA %pM does not advertise HT support
  ",
  		       pubsta->addr);

  		return -EINVAL;
  	}

  	spin_lock_bh(&sta->lock);
  
  	/* we have tried too many times, receiver does not want A-MPDU */
  	if (sta->ampdu_mlme.addba_req_num[tid] > HT_AGG_MAX_RETRIES) {
  		ret = -EBUSY;

  		goto err_unlock_sta;
  	}
  
  	/*
  	 * if we have tried more than HT_AGG_BURST_RETRIES times we
  	 * will spread our requests in time to avoid stalling connection
  	 * for too long
  	 */
  	if (sta->ampdu_mlme.addba_req_num[tid] > HT_AGG_BURST_RETRIES &&
  	    time_before(jiffies, sta->ampdu_mlme.last_addba_req_time[tid] +
  			HT_AGG_RETRIES_PERIOD)) {

  		ht_dbg(sdata,

  		       "BA request denied - %d failed requests on %pM tid %u
  ",

  		       sta->ampdu_mlme.addba_req_num[tid], sta->sta.addr, tid);

  		ret = -EBUSY;

  		goto err_unlock_sta;
  	}

  	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

  	/* check if the TID is not in aggregation flow already */

  	if (tid_tx || sta->ampdu_mlme.tid_start_tx[tid]) {

  		ht_dbg(sdata,

  		       "BA request denied - session is not idle on %pM tid %u
  ",
  		       sta->sta.addr, tid);

  		ret = -EAGAIN;
  		goto err_unlock_sta;
  	}
  
  	/* prepare A-MPDU MLME for Tx aggregation */

  	tid_tx = kzalloc(sizeof(struct tid_ampdu_tx), GFP_ATOMIC);
  	if (!tid_tx) {

  		ret = -ENOMEM;

  		goto err_unlock_sta;

  	}

  	skb_queue_head_init(&tid_tx->pending);

  	__set_bit(HT_AGG_STATE_WANT_START, &tid_tx->state);

  	tid_tx->timeout = timeout;

  	/* response timer */

  	setup_timer(&tid_tx->addba_resp_timer,
  		    sta_addba_resp_timer_expired,
  		    (unsigned long)&sta->timer_to_tid[tid]);

  	/* tx timer */

  	setup_deferrable_timer(&tid_tx->session_timer,
  			       sta_tx_agg_session_timer_expired,
  			       (unsigned long)&sta->timer_to_tid[tid]);

  	/* assign a dialog token */

  	sta->ampdu_mlme.dialog_token_allocator++;

  	tid_tx->dialog_token = sta->ampdu_mlme.dialog_token_allocator;

  	/*
  	 * Finally, assign it to the start array; the work item will
  	 * collect it and move it to the normal array.
  	 */
  	sta->ampdu_mlme.tid_start_tx[tid] = tid_tx;

  	ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);

  	/* this flow continues off the work */

   err_unlock_sta:

  	spin_unlock_bh(&sta->lock);

  	return ret;
  }
  EXPORT_SYMBOL(ieee80211_start_tx_ba_session);

  static void ieee80211_agg_tx_operational(struct ieee80211_local *local,
  					 struct sta_info *sta, u16 tid)
  {

  	struct tid_ampdu_tx *tid_tx;

  	struct ieee80211_ampdu_params params = {
  		.sta = &sta->sta,
  		.action = IEEE80211_AMPDU_TX_OPERATIONAL,
  		.tid = tid,
  		.timeout = 0,
  		.ssn = 0,
  	};

  	lockdep_assert_held(&sta->ampdu_mlme.mtx);

  	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

  	params.buf_size = tid_tx->buf_size;
  	params.amsdu = tid_tx->amsdu;

  	ht_dbg(sta->sdata, "Aggregation is on for %pM tid %d
  ",
  	       sta->sta.addr, tid);

  	drv_ampdu_action(local, sta->sdata, &params);

  
  	/*
  	 * synchronize with TX path, while splicing the TX path
  	 * should block so it won't put more packets onto pending.
  	 */
  	spin_lock_bh(&sta->lock);

  	ieee80211_agg_splice_packets(sta->sdata, tid_tx, tid);

  	/*

  	 * Now mark as operational. This will be visible
  	 * in the TX path, and lets it go lock-free in
  	 * the common case.

  	 */

  	set_bit(HT_AGG_STATE_OPERATIONAL, &tid_tx->state);

  	ieee80211_agg_splice_finish(sta->sdata, tid);

  	spin_unlock_bh(&sta->lock);

  
  	ieee80211_agg_start_txq(sta, tid, true);

  }

  void ieee80211_start_tx_ba_cb(struct sta_info *sta, int tid,
  			      struct tid_ampdu_tx *tid_tx)

  {

  	struct ieee80211_sub_if_data *sdata = sta->sdata;

  	struct ieee80211_local *local = sdata->local;

  	if (WARN_ON(test_and_set_bit(HT_AGG_STATE_DRV_READY, &tid_tx->state)))
  		return;
  
  	if (test_bit(HT_AGG_STATE_RESPONSE_RECEIVED, &tid_tx->state))
  		ieee80211_agg_tx_operational(local, sta, tid);
  }
  
  static struct tid_ampdu_tx *
  ieee80211_lookup_tid_tx(struct ieee80211_sub_if_data *sdata,
  			const u8 *ra, u16 tid, struct sta_info **sta)
  {
  	struct tid_ampdu_tx *tid_tx;

  	if (tid >= IEEE80211_NUM_TIDS) {

  		ht_dbg(sdata, "Bad TID value: tid = %d (>= %d)
  ",

  		       tid, IEEE80211_NUM_TIDS);

  		return NULL;

  	}

  	*sta = sta_info_get_bss(sdata, ra);
  	if (!*sta) {

  		ht_dbg(sdata, "Could not find station: %pM
  ", ra);

  		return NULL;

  	}

  	tid_tx = rcu_dereference((*sta)->ampdu_mlme.tid_tx[tid]);

  	if (WARN_ON(!tid_tx))

  		ht_dbg(sdata, "addBA was not requested!
  ");

  	return tid_tx;

  }

  void ieee80211_start_tx_ba_cb_irqsafe(struct ieee80211_vif *vif,

  				      const u8 *ra, u16 tid)
  {

  	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
  	struct ieee80211_local *local = sdata->local;

  	struct sta_info *sta;
  	struct tid_ampdu_tx *tid_tx;

  	trace_api_start_tx_ba_cb(sdata, ra, tid);

  	rcu_read_lock();
  	tid_tx = ieee80211_lookup_tid_tx(sdata, ra, tid, &sta);
  	if (!tid_tx)
  		goto out;

  	set_bit(HT_AGG_STATE_START_CB, &tid_tx->state);
  	ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);
   out:
  	rcu_read_unlock();

  }
  EXPORT_SYMBOL(ieee80211_start_tx_ba_cb_irqsafe);

  int __ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,

  				   enum ieee80211_agg_stop_reason reason)

  {

  	int ret;

  	mutex_lock(&sta->ampdu_mlme.mtx);

  	ret = ___ieee80211_stop_tx_ba_session(sta, tid, reason);

  	mutex_unlock(&sta->ampdu_mlme.mtx);

  	return ret;
  }

  int ieee80211_stop_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid)

  {

  	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
  	struct ieee80211_sub_if_data *sdata = sta->sdata;
  	struct ieee80211_local *local = sdata->local;

  	struct tid_ampdu_tx *tid_tx;
  	int ret = 0;

  	trace_api_stop_tx_ba_session(pubsta, tid);

  	if (!local->ops->ampdu_action)

  		return -EINVAL;

  	if (tid >= IEEE80211_NUM_TIDS)

  		return -EINVAL;

  	spin_lock_bh(&sta->lock);

  	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

  
  	if (!tid_tx) {
  		ret = -ENOENT;
  		goto unlock;
  	}

  	WARN(sta->reserved_tid == tid,
  	     "Requested to stop BA session on reserved tid=%d", tid);

  	if (test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
  		/* already in progress stopping it */
  		ret = 0;
  		goto unlock;
  	}
  
  	set_bit(HT_AGG_STATE_WANT_STOP, &tid_tx->state);
  	ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);
  
   unlock:
  	spin_unlock_bh(&sta->lock);
  	return ret;

  }
  EXPORT_SYMBOL(ieee80211_stop_tx_ba_session);

  void ieee80211_stop_tx_ba_cb(struct sta_info *sta, int tid,
  			     struct tid_ampdu_tx *tid_tx)

  {

  	struct ieee80211_sub_if_data *sdata = sta->sdata;

  	bool send_delba = false;

  	ht_dbg(sdata, "Stopping Tx BA session for %pM tid %d
  ",
  	       sta->sta.addr, tid);

  	spin_lock_bh(&sta->lock);

  	if (!test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {

  		ht_dbg(sdata,
  		       "unexpected callback to A-MPDU stop for %pM tid %d
  ",
  		       sta->sta.addr, tid);

  		goto unlock_sta;

  	}

  	if (tid_tx->stop_initiator == WLAN_BACK_INITIATOR && tid_tx->tx_stop)

  		send_delba = true;

  	ieee80211_remove_tid_tx(sta, tid);

   unlock_sta:

  	spin_unlock_bh(&sta->lock);

  
  	if (send_delba)

  		ieee80211_send_delba(sdata, sta->sta.addr, tid,

  			WLAN_BACK_INITIATOR, WLAN_REASON_QSTA_NOT_USE);

  }

  void ieee80211_stop_tx_ba_cb_irqsafe(struct ieee80211_vif *vif,

  				     const u8 *ra, u16 tid)
  {

  	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
  	struct ieee80211_local *local = sdata->local;

  	struct sta_info *sta;
  	struct tid_ampdu_tx *tid_tx;

  	trace_api_stop_tx_ba_cb(sdata, ra, tid);

  	rcu_read_lock();
  	tid_tx = ieee80211_lookup_tid_tx(sdata, ra, tid, &sta);
  	if (!tid_tx)
  		goto out;

  	set_bit(HT_AGG_STATE_STOP_CB, &tid_tx->state);
  	ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);
   out:
  	rcu_read_unlock();

  }
  EXPORT_SYMBOL(ieee80211_stop_tx_ba_cb_irqsafe);

  void ieee80211_process_addba_resp(struct ieee80211_local *local,
  				  struct sta_info *sta,
  				  struct ieee80211_mgmt *mgmt,
  				  size_t len)
  {

  	struct tid_ampdu_tx *tid_tx;

  	struct ieee80211_txq *txq;

  	u16 capab, tid;

  	u8 buf_size;

  	bool amsdu;

  
  	capab = le16_to_cpu(mgmt->u.action.u.addba_resp.capab);

  	amsdu = capab & IEEE80211_ADDBA_PARAM_AMSDU_MASK;

  	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;

  	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;

  	buf_size = min(buf_size, local->hw.max_tx_aggregation_subframes);

  	txq = sta->sta.txq[tid];
  	if (!amsdu && txq)
  		set_bit(IEEE80211_TXQ_NO_AMSDU, &to_txq_info(txq)->flags);

  	mutex_lock(&sta->ampdu_mlme.mtx);

  	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

  	if (!tid_tx)

  		goto out;

  	if (mgmt->u.action.u.addba_resp.dialog_token != tid_tx->dialog_token) {

  		ht_dbg(sta->sdata, "wrong addBA response token, %pM tid %d
  ",
  		       sta->sta.addr, tid);

  		goto out;

  	}

  	del_timer_sync(&tid_tx->addba_resp_timer);

  	ht_dbg(sta->sdata, "switched off addBA timer for %pM tid %d
  ",
  	       sta->sta.addr, tid);

  
  	/*
  	 * addba_resp_timer may have fired before we got here, and
  	 * caused WANT_STOP to be set. If the stop then was already
  	 * processed further, STOPPING might be set.
  	 */
  	if (test_bit(HT_AGG_STATE_WANT_STOP, &tid_tx->state) ||
  	    test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {

  		ht_dbg(sta->sdata,

  		       "got addBA resp for %pM tid %d but we already gave up
  ",
  		       sta->sta.addr, tid);

  		goto out;
  	}

  	/*
  	 * IEEE 802.11-2007 7.3.1.14:
  	 * In an ADDBA Response frame, when the Status Code field
  	 * is set to 0, the Buffer Size subfield is set to a value
  	 * of at least 1.
  	 */

  	if (le16_to_cpu(mgmt->u.action.u.addba_resp.status)

  			== WLAN_STATUS_SUCCESS && buf_size) {

  		if (test_and_set_bit(HT_AGG_STATE_RESPONSE_RECEIVED,
  				     &tid_tx->state)) {
  			/* ignore duplicate response */
  			goto out;
  		}

  		tid_tx->buf_size = buf_size;

  		tid_tx->amsdu = amsdu;

  		if (test_bit(HT_AGG_STATE_DRV_READY, &tid_tx->state))

  			ieee80211_agg_tx_operational(local, sta, tid);

  		sta->ampdu_mlme.addba_req_num[tid] = 0;

  		tid_tx->timeout =
  			le16_to_cpu(mgmt->u.action.u.addba_resp.timeout);

  		if (tid_tx->timeout) {

  			mod_timer(&tid_tx->session_timer,
  				  TU_TO_EXP_TIME(tid_tx->timeout));

  			tid_tx->last_tx = jiffies;
  		}

  	} else {

  		___ieee80211_stop_tx_ba_session(sta, tid, AGG_STOP_DECLINED);

  	}

   out:

  	mutex_unlock(&sta->ampdu_mlme.mtx);

  }