net/mac80211/agg-rx.c - kernel/msm-4.9 - Gitiles

 /*
  * 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
  *
  * 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.
  */

 /**
  * DOC: RX A-MPDU aggregation
  *
  * Aggregation on the RX side requires only implementing the
  * @ampdu_action callback that is invoked to start/stop any
  * block-ack sessions for RX aggregation.
  *
  * When RX aggregation is started by the peer, the driver is
  * notified via @ampdu_action function, with the
  * %IEEE80211_AMPDU_RX_START action, and may reject the request
  * in which case a negative response is sent to the peer, if it
  * accepts it a positive response is sent.
  *
  * While the session is active, the device/driver are required
  * to de-aggregate frames and pass them up one by one to mac80211,
  * which will handle the reorder buffer.
  *
  * When the aggregation session is stopped again by the peer or
  * ourselves, the driver's @ampdu_action function will be called
  * with the action %IEEE80211_AMPDU_RX_STOP. In this case, the
  * call must not fail.
  */

 #include <linux/ieee80211.h>
 #include <linux/slab.h>
 #include <net/mac80211.h>
 #include "ieee80211_i.h"
 #include "driver-ops.h"

 static void ieee80211_free_tid_rx(struct rcu_head *h)
 {
 	struct tid_ampdu_rx *tid_rx =
 		container_of(h, struct tid_ampdu_rx, rcu_head);
 	int i;

 	for (i = 0; i < tid_rx->buf_size; i++)
 		dev_kfree_skb(tid_rx->reorder_buf[i]);
 	kfree(tid_rx->reorder_buf);
 	kfree(tid_rx->reorder_time);
 	kfree(tid_rx);
 }

 void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
 				     u16 initiator, u16 reason, bool tx)
 {
 	struct ieee80211_local *local = sta->local;
 	struct tid_ampdu_rx *tid_rx;

 	lockdep_assert_held(&sta->ampdu_mlme.mtx);

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

 	if (!tid_rx)
 		return;

 	rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], NULL);

 #ifdef CONFIG_MAC80211_HT_DEBUG
 	printk(KERN_DEBUG "Rx BA session stop requested for %pM tid %u\n",
 	       sta->sta.addr, tid);
 #endif /* CONFIG_MAC80211_HT_DEBUG */

 	if (drv_ampdu_action(local, sta->sdata, IEEE80211_AMPDU_RX_STOP,
 			     &sta->sta, tid, NULL))
 		printk(KERN_DEBUG "HW problem - can not stop rx "
 				"aggregation for tid %d\n", tid);

 	/* check if this is a self generated aggregation halt */
 	if (initiator == WLAN_BACK_RECIPIENT && tx)
 		ieee80211_send_delba(sta->sdata, sta->sta.addr,
 				     tid, 0, reason);

 	del_timer_sync(&tid_rx->session_timer);
 	del_timer_sync(&tid_rx->reorder_timer);

 	call_rcu(&tid_rx->rcu_head, ieee80211_free_tid_rx);
 }

 void __ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
 				    u16 initiator, u16 reason, bool tx)
 {
 	mutex_lock(&sta->ampdu_mlme.mtx);
 	___ieee80211_stop_rx_ba_session(sta, tid, initiator, reason, tx);
 	mutex_unlock(&sta->ampdu_mlme.mtx);
 }

 /*
  * After accepting the AddBA Request we activated a timer,
  * resetting it after each frame that arrives from the originator.
  */
 static void sta_rx_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]);

 #ifdef CONFIG_MAC80211_HT_DEBUG
 	printk(KERN_DEBUG "rx session timer expired on tid %d\n", (u16)*ptid);
 #endif
 	set_bit(*ptid, sta->ampdu_mlme.tid_rx_timer_expired);
 	ieee80211_queue_work(&sta->local->hw, &sta->ampdu_mlme.work);
 }

 static void sta_rx_agg_reorder_timer_expired(unsigned long data)
 {
 	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]);

 	rcu_read_lock();
 	ieee80211_release_reorder_timeout(sta, *ptid);
 	rcu_read_unlock();
 }

 static void ieee80211_send_addba_resp(struct ieee80211_sub_if_data *sdata, u8 *da, u16 tid,
 				      u8 dialog_token, u16 status, u16 policy,
 				      u16 buf_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) {
 		printk(KERN_DEBUG "%s: failed to allocate buffer "
 		       "for addba resp frame\n", sdata->name);
 		return;
 	}

 	skb_reserve(skb, local->hw.extra_tx_headroom);
 	mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
 	memset(mgmt, 0, 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)
 		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);

 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
 					  IEEE80211_STYPE_ACTION);

 	skb_put(skb, 1 + sizeof(mgmt->u.action.u.addba_resp));
 	mgmt->u.action.category = WLAN_CATEGORY_BACK;
 	mgmt->u.action.u.addba_resp.action_code = WLAN_ACTION_ADDBA_RESP;
 	mgmt->u.action.u.addba_resp.dialog_token = dialog_token;

 	capab = (u16)(policy << 1);	/* bit 1 aggregation policy */
 	capab |= (u16)(tid << 2); 	/* bit 5:2 TID number */
 	capab |= (u16)(buf_size << 6);	/* bit 15:6 max size of aggregation */

 	mgmt->u.action.u.addba_resp.capab = cpu_to_le16(capab);
 	mgmt->u.action.u.addba_resp.timeout = cpu_to_le16(timeout);
 	mgmt->u.action.u.addba_resp.status = cpu_to_le16(status);

 	ieee80211_tx_skb(sdata, skb);
 }

 void ieee80211_process_addba_request(struct ieee80211_local *local,
 				     struct sta_info *sta,
 				     struct ieee80211_mgmt *mgmt,
 				     size_t len)
 {
 	struct ieee80211_hw *hw = &local->hw;
 	struct ieee80211_conf *conf = &hw->conf;
 	struct tid_ampdu_rx *tid_agg_rx;
 	u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num, status;
 	u8 dialog_token;
 	int ret = -EOPNOTSUPP;

 	/* extract session parameters from addba request frame */
 	dialog_token = mgmt->u.action.u.addba_req.dialog_token;
 	timeout = le16_to_cpu(mgmt->u.action.u.addba_req.timeout);
 	start_seq_num =
 		le16_to_cpu(mgmt->u.action.u.addba_req.start_seq_num) >> 4;

 	capab = le16_to_cpu(mgmt->u.action.u.addba_req.capab);
 	ba_policy = (capab & IEEE80211_ADDBA_PARAM_POLICY_MASK) >> 1;
 	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
 	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;

 	status = WLAN_STATUS_REQUEST_DECLINED;

 	if (test_sta_flags(sta, WLAN_STA_BLOCK_BA)) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		printk(KERN_DEBUG "Suspend in progress. "
 		       "Denying ADDBA request\n");
 #endif
 		goto end_no_lock;
 	}

 	/* sanity check for incoming parameters:
 	 * check if configuration can support the BA policy
 	 * and if buffer size does not exceeds max value */
 	/* XXX: check own ht delayed BA capability?? */
 	if (((ba_policy != 1) &&
 	     (!(sta->sta.ht_cap.cap & IEEE80211_HT_CAP_DELAY_BA))) ||
 	    (buf_size > IEEE80211_MAX_AMPDU_BUF)) {
 		status = WLAN_STATUS_INVALID_QOS_PARAM;
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		if (net_ratelimit())
 			printk(KERN_DEBUG "AddBA Req with bad params from "
 				"%pM on tid %u. policy %d, buffer size %d\n",
 				mgmt->sa, tid, ba_policy,
 				buf_size);
 #endif /* CONFIG_MAC80211_HT_DEBUG */
 		goto end_no_lock;
 	}
 	/* determine default buffer size */
 	if (buf_size == 0) {
 		struct ieee80211_supported_band *sband;

 		sband = local->hw.wiphy->bands[conf->channel->band];
 		buf_size = IEEE80211_MIN_AMPDU_BUF;
 		buf_size = buf_size << sband->ht_cap.ampdu_factor;
 	}


 	/* examine state machine */
 	mutex_lock(&sta->ampdu_mlme.mtx);

 	if (sta->ampdu_mlme.tid_rx[tid]) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		if (net_ratelimit())
 			printk(KERN_DEBUG "unexpected AddBA Req from "
 				"%pM on tid %u\n",
 				mgmt->sa, tid);
 #endif /* CONFIG_MAC80211_HT_DEBUG */
 		goto end;
 	}

 	/* prepare A-MPDU MLME for Rx aggregation */
 	tid_agg_rx = kmalloc(sizeof(struct tid_ampdu_rx), GFP_KERNEL);
 	if (!tid_agg_rx) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		if (net_ratelimit())
 			printk(KERN_ERR "allocate rx mlme to tid %d failed\n",
 					tid);
 #endif
 		goto end;
 	}

 	spin_lock_init(&tid_agg_rx->reorder_lock);

 	/* rx timer */
 	tid_agg_rx->session_timer.function = sta_rx_agg_session_timer_expired;
 	tid_agg_rx->session_timer.data = (unsigned long)&sta->timer_to_tid[tid];
 	init_timer(&tid_agg_rx->session_timer);

 	/* rx reorder timer */
 	tid_agg_rx->reorder_timer.function = sta_rx_agg_reorder_timer_expired;
 	tid_agg_rx->reorder_timer.data = (unsigned long)&sta->timer_to_tid[tid];
 	init_timer(&tid_agg_rx->reorder_timer);

 	/* prepare reordering buffer */
 	tid_agg_rx->reorder_buf =
 		kcalloc(buf_size, sizeof(struct sk_buff *), GFP_KERNEL);
 	tid_agg_rx->reorder_time =
 		kcalloc(buf_size, sizeof(unsigned long), GFP_KERNEL);
 	if (!tid_agg_rx->reorder_buf || !tid_agg_rx->reorder_time) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		if (net_ratelimit())
 			printk(KERN_ERR "can not allocate reordering buffer "
 			       "to tid %d\n", tid);
 #endif
 		kfree(tid_agg_rx->reorder_buf);
 		kfree(tid_agg_rx->reorder_time);
 		kfree(tid_agg_rx);
 		goto end;
 	}

 	ret = drv_ampdu_action(local, sta->sdata, IEEE80211_AMPDU_RX_START,
 			       &sta->sta, tid, &start_seq_num);
 #ifdef CONFIG_MAC80211_HT_DEBUG
 	printk(KERN_DEBUG "Rx A-MPDU request on tid %d result %d\n", tid, ret);
 #endif /* CONFIG_MAC80211_HT_DEBUG */

 	if (ret) {
 		kfree(tid_agg_rx->reorder_buf);
 		kfree(tid_agg_rx->reorder_time);
 		kfree(tid_agg_rx);
 		goto end;
 	}

 	/* update data */
 	tid_agg_rx->dialog_token = dialog_token;
 	tid_agg_rx->ssn = start_seq_num;
 	tid_agg_rx->head_seq_num = start_seq_num;
 	tid_agg_rx->buf_size = buf_size;
 	tid_agg_rx->timeout = timeout;
 	tid_agg_rx->stored_mpdu_num = 0;
 	status = WLAN_STATUS_SUCCESS;

 	/* activate it for RX */
 	rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], tid_agg_rx);

 	if (timeout)
 		mod_timer(&tid_agg_rx->session_timer, TU_TO_EXP_TIME(timeout));

 end:
 	mutex_unlock(&sta->ampdu_mlme.mtx);

 end_no_lock:
 	ieee80211_send_addba_resp(sta->sdata, sta->sta.addr, tid,
 				  dialog_token, status, 1, buf_size, timeout);
 }
	/*
	* 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
	*
	* 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.
	*/

	/**
	* DOC: RX A-MPDU aggregation
	*
	* Aggregation on the RX side requires only implementing the
	* @ampdu_action callback that is invoked to start/stop any
	* block-ack sessions for RX aggregation.
	*
	* When RX aggregation is started by the peer, the driver is
	* notified via @ampdu_action function, with the
	* %IEEE80211_AMPDU_RX_START action, and may reject the request
	* in which case a negative response is sent to the peer, if it
	* accepts it a positive response is sent.
	*
	* While the session is active, the device/driver are required
	* to de-aggregate frames and pass them up one by one to mac80211,
	* which will handle the reorder buffer.
	*
	* When the aggregation session is stopped again by the peer or
	* ourselves, the driver's @ampdu_action function will be called
	* with the action %IEEE80211_AMPDU_RX_STOP. In this case, the
	* call must not fail.
	*/

	#include <linux/ieee80211.h>
	#include <linux/slab.h>
	#include <net/mac80211.h>
	#include "ieee80211_i.h"
	#include "driver-ops.h"

	static void ieee80211_free_tid_rx(struct rcu_head *h)
	{
	struct tid_ampdu_rx *tid_rx =
	container_of(h, struct tid_ampdu_rx, rcu_head);
	int i;

	for (i = 0; i < tid_rx->buf_size; i++)
	dev_kfree_skb(tid_rx->reorder_buf[i]);
	kfree(tid_rx->reorder_buf);
	kfree(tid_rx->reorder_time);
	kfree(tid_rx);
	}

	void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
	u16 initiator, u16 reason, bool tx)
	{
	struct ieee80211_local *local = sta->local;
	struct tid_ampdu_rx *tid_rx;

	lockdep_assert_held(&sta->ampdu_mlme.mtx);

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

	if (!tid_rx)
	return;

	rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], NULL);

	#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "Rx BA session stop requested for %pM tid %u\n",
	sta->sta.addr, tid);
	#endif /* CONFIG_MAC80211_HT_DEBUG */

	if (drv_ampdu_action(local, sta->sdata, IEEE80211_AMPDU_RX_STOP,
	&sta->sta, tid, NULL))
	printk(KERN_DEBUG "HW problem - can not stop rx "
	"aggregation for tid %d\n", tid);

	/* check if this is a self generated aggregation halt */
	if (initiator == WLAN_BACK_RECIPIENT && tx)
	ieee80211_send_delba(sta->sdata, sta->sta.addr,
	tid, 0, reason);

	del_timer_sync(&tid_rx->session_timer);
	del_timer_sync(&tid_rx->reorder_timer);

	call_rcu(&tid_rx->rcu_head, ieee80211_free_tid_rx);
	}

	void __ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
	u16 initiator, u16 reason, bool tx)
	{
	mutex_lock(&sta->ampdu_mlme.mtx);
	___ieee80211_stop_rx_ba_session(sta, tid, initiator, reason, tx);
	mutex_unlock(&sta->ampdu_mlme.mtx);
	}

	/*
	* After accepting the AddBA Request we activated a timer,
	* resetting it after each frame that arrives from the originator.
	*/
	static void sta_rx_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]);

	#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "rx session timer expired on tid %d\n", (u16)*ptid);
	#endif
	set_bit(*ptid, sta->ampdu_mlme.tid_rx_timer_expired);
	ieee80211_queue_work(&sta->local->hw, &sta->ampdu_mlme.work);
	}

	static void sta_rx_agg_reorder_timer_expired(unsigned long data)
	{
	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]);

	rcu_read_lock();
	ieee80211_release_reorder_timeout(sta, *ptid);
	rcu_read_unlock();
	}

	static void ieee80211_send_addba_resp(struct ieee80211_sub_if_data sdata, u8 da, u16 tid,
	u8 dialog_token, u16 status, u16 policy,
	u16 buf_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) {
	printk(KERN_DEBUG "%s: failed to allocate buffer "
	"for addba resp frame\n", sdata->name);
	return;
	}

	skb_reserve(skb, local->hw.extra_tx_headroom);
	mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
	memset(mgmt, 0, 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)
	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);

	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT \|
	IEEE80211_STYPE_ACTION);

	skb_put(skb, 1 + sizeof(mgmt->u.action.u.addba_resp));
	mgmt->u.action.category = WLAN_CATEGORY_BACK;
	mgmt->u.action.u.addba_resp.action_code = WLAN_ACTION_ADDBA_RESP;
	mgmt->u.action.u.addba_resp.dialog_token = dialog_token;

	capab = (u16)(policy << 1); /* bit 1 aggregation policy */
	capab \|= (u16)(tid << 2); /* bit 5:2 TID number */
	capab \|= (u16)(buf_size << 6); /* bit 15:6 max size of aggregation */

	mgmt->u.action.u.addba_resp.capab = cpu_to_le16(capab);
	mgmt->u.action.u.addba_resp.timeout = cpu_to_le16(timeout);
	mgmt->u.action.u.addba_resp.status = cpu_to_le16(status);

	ieee80211_tx_skb(sdata, skb);
	}

	void ieee80211_process_addba_request(struct ieee80211_local *local,
	struct sta_info *sta,
	struct ieee80211_mgmt *mgmt,
	size_t len)
	{
	struct ieee80211_hw *hw = &local->hw;
	struct ieee80211_conf *conf = &hw->conf;
	struct tid_ampdu_rx *tid_agg_rx;
	u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num, status;
	u8 dialog_token;
	int ret = -EOPNOTSUPP;

	/* extract session parameters from addba request frame */
	dialog_token = mgmt->u.action.u.addba_req.dialog_token;
	timeout = le16_to_cpu(mgmt->u.action.u.addba_req.timeout);
	start_seq_num =
	le16_to_cpu(mgmt->u.action.u.addba_req.start_seq_num) >> 4;

	capab = le16_to_cpu(mgmt->u.action.u.addba_req.capab);
	ba_policy = (capab & IEEE80211_ADDBA_PARAM_POLICY_MASK) >> 1;
	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;

	status = WLAN_STATUS_REQUEST_DECLINED;

	if (test_sta_flags(sta, WLAN_STA_BLOCK_BA)) {
	#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "Suspend in progress. "
	"Denying ADDBA request\n");
	#endif
	goto end_no_lock;
	}

	/* sanity check for incoming parameters:
	* check if configuration can support the BA policy
	* and if buffer size does not exceeds max value */
	/* XXX: check own ht delayed BA capability?? */
	if (((ba_policy != 1) &&
	(!(sta->sta.ht_cap.cap & IEEE80211_HT_CAP_DELAY_BA))) \|\|
	(buf_size > IEEE80211_MAX_AMPDU_BUF)) {
	status = WLAN_STATUS_INVALID_QOS_PARAM;
	#ifdef CONFIG_MAC80211_HT_DEBUG
	if (net_ratelimit())
	printk(KERN_DEBUG "AddBA Req with bad params from "
	"%pM on tid %u. policy %d, buffer size %d\n",
	mgmt->sa, tid, ba_policy,
	buf_size);
	#endif /* CONFIG_MAC80211_HT_DEBUG */
	goto end_no_lock;
	}
	/* determine default buffer size */
	if (buf_size == 0) {
	struct ieee80211_supported_band *sband;

	sband = local->hw.wiphy->bands[conf->channel->band];
	buf_size = IEEE80211_MIN_AMPDU_BUF;
	buf_size = buf_size << sband->ht_cap.ampdu_factor;
	}


	/* examine state machine */
	mutex_lock(&sta->ampdu_mlme.mtx);

	if (sta->ampdu_mlme.tid_rx[tid]) {
	#ifdef CONFIG_MAC80211_HT_DEBUG
	if (net_ratelimit())
	printk(KERN_DEBUG "unexpected AddBA Req from "
	"%pM on tid %u\n",
	mgmt->sa, tid);
	#endif /* CONFIG_MAC80211_HT_DEBUG */
	goto end;
	}

	/* prepare A-MPDU MLME for Rx aggregation */
	tid_agg_rx = kmalloc(sizeof(struct tid_ampdu_rx), GFP_KERNEL);
	if (!tid_agg_rx) {
	#ifdef CONFIG_MAC80211_HT_DEBUG
	if (net_ratelimit())
	printk(KERN_ERR "allocate rx mlme to tid %d failed\n",
	tid);
	#endif
	goto end;
	}

	spin_lock_init(&tid_agg_rx->reorder_lock);

	/* rx timer */
	tid_agg_rx->session_timer.function = sta_rx_agg_session_timer_expired;
	tid_agg_rx->session_timer.data = (unsigned long)&sta->timer_to_tid[tid];
	init_timer(&tid_agg_rx->session_timer);

	/* rx reorder timer */
	tid_agg_rx->reorder_timer.function = sta_rx_agg_reorder_timer_expired;
	tid_agg_rx->reorder_timer.data = (unsigned long)&sta->timer_to_tid[tid];
	init_timer(&tid_agg_rx->reorder_timer);

	/* prepare reordering buffer */
	tid_agg_rx->reorder_buf =
	kcalloc(buf_size, sizeof(struct sk_buff *), GFP_KERNEL);
	tid_agg_rx->reorder_time =
	kcalloc(buf_size, sizeof(unsigned long), GFP_KERNEL);
	if (!tid_agg_rx->reorder_buf \|\| !tid_agg_rx->reorder_time) {
	#ifdef CONFIG_MAC80211_HT_DEBUG
	if (net_ratelimit())
	printk(KERN_ERR "can not allocate reordering buffer "
	"to tid %d\n", tid);
	#endif
	kfree(tid_agg_rx->reorder_buf);
	kfree(tid_agg_rx->reorder_time);
	kfree(tid_agg_rx);
	goto end;
	}

	ret = drv_ampdu_action(local, sta->sdata, IEEE80211_AMPDU_RX_START,
	&sta->sta, tid, &start_seq_num);
	#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "Rx A-MPDU request on tid %d result %d\n", tid, ret);
	#endif /* CONFIG_MAC80211_HT_DEBUG */

	if (ret) {
	kfree(tid_agg_rx->reorder_buf);
	kfree(tid_agg_rx->reorder_time);
	kfree(tid_agg_rx);
	goto end;
	}

	/* update data */
	tid_agg_rx->dialog_token = dialog_token;
	tid_agg_rx->ssn = start_seq_num;
	tid_agg_rx->head_seq_num = start_seq_num;
	tid_agg_rx->buf_size = buf_size;
	tid_agg_rx->timeout = timeout;
	tid_agg_rx->stored_mpdu_num = 0;
	status = WLAN_STATUS_SUCCESS;

	/* activate it for RX */
	rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], tid_agg_rx);

	if (timeout)
	mod_timer(&tid_agg_rx->session_timer, TU_TO_EXP_TIME(timeout));

	end:
	mutex_unlock(&sta->ampdu_mlme.mtx);

	end_no_lock:
	ieee80211_send_addba_resp(sta->sdata, sta->sta.addr, tid,
	dialog_token, status, 1, buf_size, timeout);
	}