net/mac80211/agg-rx.c - kernel/msm - 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 2007-2008, 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 <net/mac80211.h>
 #include "ieee80211_i.h"

 void __ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
 				    u16 initiator, u16 reason)
 {
 	struct ieee80211_local *local = sta->local;
 	struct ieee80211_hw *hw = &local->hw;
 	int i;

 	/* check if TID is in operational state */
 	spin_lock_bh(&sta->lock);
 	if (sta->ampdu_mlme.tid_state_rx[tid] != HT_AGG_STATE_OPERATIONAL) {
 		spin_unlock_bh(&sta->lock);
 		return;
 	}

 	sta->ampdu_mlme.tid_state_rx[tid] =
 		HT_AGG_STATE_REQ_STOP_BA_MSK |
 		(initiator << HT_AGG_STATE_INITIATOR_SHIFT);
 	spin_unlock_bh(&sta->lock);

 #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 (local->ops->ampdu_action(hw, IEEE80211_AMPDU_RX_STOP,
 				     &sta->sta, tid, NULL))
 		printk(KERN_DEBUG "HW problem - can not stop rx "
 				"aggregation for tid %d\n", tid);

 	/* shutdown timer has not expired */
 	if (initiator != WLAN_BACK_TIMER)
 		del_timer_sync(&sta->ampdu_mlme.tid_rx[tid]->session_timer);

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

 	/* free the reordering buffer */
 	for (i = 0; i < sta->ampdu_mlme.tid_rx[tid]->buf_size; i++) {
 		if (sta->ampdu_mlme.tid_rx[tid]->reorder_buf[i]) {
 			/* release the reordered frames */
 			dev_kfree_skb(sta->ampdu_mlme.tid_rx[tid]->reorder_buf[i]);
 			sta->ampdu_mlme.tid_rx[tid]->stored_mpdu_num--;
 			sta->ampdu_mlme.tid_rx[tid]->reorder_buf[i] = NULL;
 		}
 	}

 	spin_lock_bh(&sta->lock);
 	/* free resources */
 	kfree(sta->ampdu_mlme.tid_rx[tid]->reorder_buf);

 	if (!sta->ampdu_mlme.tid_rx[tid]->shutdown) {
 		kfree(sta->ampdu_mlme.tid_rx[tid]);
 		sta->ampdu_mlme.tid_rx[tid] = NULL;
 	}

 	sta->ampdu_mlme.tid_state_rx[tid] = HT_AGG_STATE_IDLE;
 	spin_unlock_bh(&sta->lock);
 }

 void ieee80211_sta_stop_rx_ba_session(struct ieee80211_sub_if_data *sdata, u8 *ra, u16 tid,
 					u16 initiator, u16 reason)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta;

 	/* stop HW Rx aggregation. ampdu_action existence
 	 * already verified in session init so we add the BUG_ON */
 	BUG_ON(!local->ops->ampdu_action);

 	rcu_read_lock();

 	sta = sta_info_get(local, ra);
 	if (!sta) {
 		rcu_read_unlock();
 		return;
 	}

 	__ieee80211_stop_rx_ba_session(sta, tid, initiator, reason);

 	rcu_read_unlock();
 }

 /*
  * After accepting the AddBA Request we activated a timer,
  * resetting it after each frame that arrives from the originator.
  * if this timer expires ieee80211_sta_stop_rx_ba_session will be executed.
  */
 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
 	ieee80211_sta_stop_rx_ba_session(sta->sdata, sta->sta.addr,
 					 (u16)*ptid, WLAN_BACK_TIMER,
 					 WLAN_REASON_QSTA_TIMEOUT);
 }

 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_if_sta *ifsta = &sdata->u.sta;
 	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->dev->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->dev->dev_addr, ETH_ALEN);
 	if (sdata->vif.type == NL80211_IFTYPE_AP ||
 	    sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 		memcpy(mgmt->bssid, sdata->dev->dev_addr, ETH_ALEN);
 	else
 		memcpy(mgmt->bssid, ifsta->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, 1);
 }

 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;

 	/* 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 */
 	spin_lock_bh(&sta->lock);

 	if (sta->ampdu_mlme.tid_state_rx[tid] != HT_AGG_STATE_IDLE) {
 #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 */
 	sta->ampdu_mlme.tid_rx[tid] =
 			kmalloc(sizeof(struct tid_ampdu_rx), GFP_ATOMIC);
 	if (!sta->ampdu_mlme.tid_rx[tid]) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		if (net_ratelimit())
 			printk(KERN_ERR "allocate rx mlme to tid %d failed\n",
 					tid);
 #endif
 		goto end;
 	}
 	/* rx timer */
 	sta->ampdu_mlme.tid_rx[tid]->session_timer.function =
 				sta_rx_agg_session_timer_expired;
 	sta->ampdu_mlme.tid_rx[tid]->session_timer.data =
 				(unsigned long)&sta->timer_to_tid[tid];
 	init_timer(&sta->ampdu_mlme.tid_rx[tid]->session_timer);

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

 	/* prepare reordering buffer */
 	tid_agg_rx->reorder_buf =
 		kcalloc(buf_size, sizeof(struct sk_buff *), GFP_ATOMIC);
 	if (!tid_agg_rx->reorder_buf) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		if (net_ratelimit())
 			printk(KERN_ERR "can not allocate reordering buffer "
 			       "to tid %d\n", tid);
 #endif
 		kfree(sta->ampdu_mlme.tid_rx[tid]);
 		goto end;
 	}

 	if (local->ops->ampdu_action)
 		ret = local->ops->ampdu_action(hw, 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);
 		sta->ampdu_mlme.tid_rx[tid] = NULL;
 		goto end;
 	}

 	/* change state and send addba resp */
 	sta->ampdu_mlme.tid_state_rx[tid] = HT_AGG_STATE_OPERATIONAL;
 	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;
 end:
 	spin_unlock_bh(&sta->lock);

 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 2007-2008, 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 <net/mac80211.h>
	#include "ieee80211_i.h"

	void __ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
	u16 initiator, u16 reason)
	{
	struct ieee80211_local *local = sta->local;
	struct ieee80211_hw *hw = &local->hw;
	int i;

	/* check if TID is in operational state */
	spin_lock_bh(&sta->lock);
	if (sta->ampdu_mlme.tid_state_rx[tid] != HT_AGG_STATE_OPERATIONAL) {
	spin_unlock_bh(&sta->lock);
	return;
	}

	sta->ampdu_mlme.tid_state_rx[tid] =
	HT_AGG_STATE_REQ_STOP_BA_MSK \|
	(initiator << HT_AGG_STATE_INITIATOR_SHIFT);
	spin_unlock_bh(&sta->lock);

	#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 (local->ops->ampdu_action(hw, IEEE80211_AMPDU_RX_STOP,
	&sta->sta, tid, NULL))
	printk(KERN_DEBUG "HW problem - can not stop rx "
	"aggregation for tid %d\n", tid);

	/* shutdown timer has not expired */
	if (initiator != WLAN_BACK_TIMER)
	del_timer_sync(&sta->ampdu_mlme.tid_rx[tid]->session_timer);

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

	/* free the reordering buffer */
	for (i = 0; i < sta->ampdu_mlme.tid_rx[tid]->buf_size; i++) {
	if (sta->ampdu_mlme.tid_rx[tid]->reorder_buf[i]) {
	/* release the reordered frames */
	dev_kfree_skb(sta->ampdu_mlme.tid_rx[tid]->reorder_buf[i]);
	sta->ampdu_mlme.tid_rx[tid]->stored_mpdu_num--;
	sta->ampdu_mlme.tid_rx[tid]->reorder_buf[i] = NULL;
	}
	}

	spin_lock_bh(&sta->lock);
	/* free resources */
	kfree(sta->ampdu_mlme.tid_rx[tid]->reorder_buf);

	if (!sta->ampdu_mlme.tid_rx[tid]->shutdown) {
	kfree(sta->ampdu_mlme.tid_rx[tid]);
	sta->ampdu_mlme.tid_rx[tid] = NULL;
	}

	sta->ampdu_mlme.tid_state_rx[tid] = HT_AGG_STATE_IDLE;
	spin_unlock_bh(&sta->lock);
	}

	void ieee80211_sta_stop_rx_ba_session(struct ieee80211_sub_if_data sdata, u8 ra, u16 tid,
	u16 initiator, u16 reason)
	{
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;

	/* stop HW Rx aggregation. ampdu_action existence
	* already verified in session init so we add the BUG_ON */
	BUG_ON(!local->ops->ampdu_action);

	rcu_read_lock();

	sta = sta_info_get(local, ra);
	if (!sta) {
	rcu_read_unlock();
	return;
	}

	__ieee80211_stop_rx_ba_session(sta, tid, initiator, reason);

	rcu_read_unlock();
	}

	/*
	* After accepting the AddBA Request we activated a timer,
	* resetting it after each frame that arrives from the originator.
	* if this timer expires ieee80211_sta_stop_rx_ba_session will be executed.
	*/
	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
	ieee80211_sta_stop_rx_ba_session(sta->sdata, sta->sta.addr,
	(u16)*ptid, WLAN_BACK_TIMER,
	WLAN_REASON_QSTA_TIMEOUT);
	}

	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_if_sta *ifsta = &sdata->u.sta;
	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->dev->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->dev->dev_addr, ETH_ALEN);
	if (sdata->vif.type == NL80211_IFTYPE_AP \|\|
	sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
	memcpy(mgmt->bssid, sdata->dev->dev_addr, ETH_ALEN);
	else
	memcpy(mgmt->bssid, ifsta->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, 1);
	}

	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;

	/* 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 */
	spin_lock_bh(&sta->lock);

	if (sta->ampdu_mlme.tid_state_rx[tid] != HT_AGG_STATE_IDLE) {
	#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 */
	sta->ampdu_mlme.tid_rx[tid] =
	kmalloc(sizeof(struct tid_ampdu_rx), GFP_ATOMIC);
	if (!sta->ampdu_mlme.tid_rx[tid]) {
	#ifdef CONFIG_MAC80211_HT_DEBUG
	if (net_ratelimit())
	printk(KERN_ERR "allocate rx mlme to tid %d failed\n",
	tid);
	#endif
	goto end;
	}
	/* rx timer */
	sta->ampdu_mlme.tid_rx[tid]->session_timer.function =
	sta_rx_agg_session_timer_expired;
	sta->ampdu_mlme.tid_rx[tid]->session_timer.data =
	(unsigned long)&sta->timer_to_tid[tid];
	init_timer(&sta->ampdu_mlme.tid_rx[tid]->session_timer);

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

	/* prepare reordering buffer */
	tid_agg_rx->reorder_buf =
	kcalloc(buf_size, sizeof(struct sk_buff *), GFP_ATOMIC);
	if (!tid_agg_rx->reorder_buf) {
	#ifdef CONFIG_MAC80211_HT_DEBUG
	if (net_ratelimit())
	printk(KERN_ERR "can not allocate reordering buffer "
	"to tid %d\n", tid);
	#endif
	kfree(sta->ampdu_mlme.tid_rx[tid]);
	goto end;
	}

	if (local->ops->ampdu_action)
	ret = local->ops->ampdu_action(hw, 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);
	sta->ampdu_mlme.tid_rx[tid] = NULL;
	goto end;
	}

	/* change state and send addba resp */
	sta->ampdu_mlme.tid_state_rx[tid] = HT_AGG_STATE_OPERATIONAL;
	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;
	end:
	spin_unlock_bh(&sta->lock);

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