mac80211: restructure HT code

Create two new files, agg-tx.c and agg-rx.c to make it clearer
which code is common (ht.c) and which is specific (agg-*.c).
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/Makefile

@@ -8,7 +8,7 @@ mac80211-y := \
 	wep.o \
 	wpa.o \
 	scan.o \
-	ht.o \
+	ht.o agg-tx.o agg-rx.o \
 	mlme.o \
 	iface.o \
 	rate.o \

net/mac80211/agg-rx.c

+/*
+ * 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_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 ieee80211_hw *hw = &local->hw;
+	struct sta_info *sta;
+	int ret, i;
+
+	rcu_read_lock();
+
+	sta = sta_info_get(local, ra);
+	if (!sta) {
+		rcu_read_unlock();
+		return;
+	}
+
+	/* 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);
+		rcu_read_unlock();
+		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);
+
+	/* stop HW Rx aggregation. ampdu_action existence
+	 * already verified in session init so we add the BUG_ON */
+	BUG_ON(!local->ops->ampdu_action);
+
+#ifdef CONFIG_MAC80211_HT_DEBUG
+	printk(KERN_DEBUG "Rx BA session stop requested for %pM tid %u\n",
+	       ra, tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+
+	ret = local->ops->ampdu_action(hw, IEEE80211_AMPDU_RX_STOP,
+				       &sta->sta, tid, NULL);
+	if (ret)
+		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(sdata, ra, 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;
+		}
+	}
+	/* free resources */
+	kfree(sta->ampdu_mlme.tid_rx[tid]->reorder_buf);
+	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;
+
+	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)
+		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);
+}

net/mac80211/agg-tx.c

+/*
+ * 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 2007-2009, 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"
+#include "wme.h"
+
+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 ieee80211_if_sta *ifsta = &sdata->u.sta;
+	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_ERR "%s: failed to allocate buffer "
+				"for addba request 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)
+		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_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 << 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, 1);
+}
+
+void ieee80211_send_bar(struct ieee80211_sub_if_data *sdata, u8 *ra, u16 tid, u16 ssn)
+{
+	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) {
+		printk(KERN_ERR "%s: failed to allocate buffer for "
+			"bar frame\n", sdata->dev->name);
+		return;
+	}
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+	bar = (struct ieee80211_bar *)skb_put(skb, sizeof(*bar));
+	memset(bar, 0, 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->dev->dev_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 << 12);
+	bar->control = cpu_to_le16(bar_control);
+	bar->start_seq_num = cpu_to_le16(ssn);
+
+	ieee80211_tx_skb(sdata, skb, 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 *temp_sta = container_of((void *)data,
+		struct sta_info, timer_to_tid[tid]);
+
+	struct ieee80211_local *local = temp_sta->local;
+	struct ieee80211_hw *hw = &local->hw;
+	struct sta_info *sta;
+	u8 *state;
+
+	rcu_read_lock();
+
+	sta = sta_info_get(local, temp_sta->sta.addr);
+	if (!sta) {
+		rcu_read_unlock();
+		return;
+	}
+
+	state = &sta->ampdu_mlme.tid_state_tx[tid];
+	/* check if the TID waits for addBA response */
+	spin_lock_bh(&sta->lock);
+	if (!(*state & HT_ADDBA_REQUESTED_MSK)) {
+		spin_unlock_bh(&sta->lock);
+		*state = HT_AGG_STATE_IDLE;
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "timer expired on tid %d but we are not "
+				"expecting addBA response there", tid);
+#endif
+		goto timer_expired_exit;
+	}
+
+#ifdef CONFIG_MAC80211_HT_DEBUG
+	printk(KERN_DEBUG "addBA response timer expired on tid %d\n", tid);
+#endif
+
+	/* go through the state check in stop_BA_session */
+	*state = HT_AGG_STATE_OPERATIONAL;
+	spin_unlock_bh(&sta->lock);
+	ieee80211_stop_tx_ba_session(hw, temp_sta->sta.addr, tid,
+				     WLAN_BACK_INITIATOR);
+
+timer_expired_exit:
+	rcu_read_unlock();
+}
+
+int ieee80211_start_tx_ba_session(struct ieee80211_hw *hw, u8 *ra, u16 tid)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct sta_info *sta;
+	struct ieee80211_sub_if_data *sdata;
+	u16 start_seq_num;
+	u8 *state;
+	int ret = 0;
+
+	if ((tid >= STA_TID_NUM) || !(hw->flags & IEEE80211_HW_AMPDU_AGGREGATION))
+		return -EINVAL;
+
+#ifdef CONFIG_MAC80211_HT_DEBUG
+	printk(KERN_DEBUG "Open BA session requested for %pM tid %u\n",
+	       ra, tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+
+	rcu_read_lock();
+
+	sta = sta_info_get(local, ra);
+	if (!sta) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "Could not find the station\n");
+#endif
+		ret = -ENOENT;
+		goto exit;
+	}
+
+	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;
+	}
+
+	state = &sta->ampdu_mlme.tid_state_tx[tid];
+	/* check if the TID is not in aggregation flow already */
+	if (*state != HT_AGG_STATE_IDLE) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "BA request denied - session is not "
+				 "idle on tid %u\n", tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+		ret = -EAGAIN;
+		goto err_unlock_sta;
+	}
+
+	/* prepare A-MPDU MLME for Tx aggregation */
+	sta->ampdu_mlme.tid_tx[tid] =
+			kmalloc(sizeof(struct tid_ampdu_tx), GFP_ATOMIC);
+	if (!sta->ampdu_mlme.tid_tx[tid]) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		if (net_ratelimit())
+			printk(KERN_ERR "allocate tx mlme to tid %d failed\n",
+					tid);
+#endif
+		ret = -ENOMEM;
+		goto err_unlock_sta;
+	}
+	/* Tx timer */
+	sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer.function =
+			sta_addba_resp_timer_expired;
+	sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer.data =
+			(unsigned long)&sta->timer_to_tid[tid];
+	init_timer(&sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer);
+
+	if (hw->ampdu_queues) {
+		/* create a new queue for this aggregation */
+		ret = ieee80211_ht_agg_queue_add(local, sta, tid);
+
+		/* case no queue is available to aggregation
+		 * don't switch to aggregation */
+		if (ret) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+			printk(KERN_DEBUG "BA request denied - "
+			       "queue unavailable for tid %d\n", tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+			goto err_unlock_queue;
+		}
+	}
+	sdata = sta->sdata;
+
+	/* Ok, the Addba frame hasn't been sent yet, but if the driver calls the
+	 * call back right away, it must see that the flow has begun */
+	*state |= HT_ADDBA_REQUESTED_MSK;
+
+	/* This is slightly racy because the queue isn't stopped */
+	start_seq_num = sta->tid_seq[tid];
+
+	if (local->ops->ampdu_action)
+		ret = local->ops->ampdu_action(hw, IEEE80211_AMPDU_TX_START,
+					       &sta->sta, tid, &start_seq_num);
+
+	if (ret) {
+		/* No need to requeue the packets in the agg queue, since we
+		 * held the tx lock: no packet could be enqueued to the newly
+		 * allocated queue */
+		if (hw->ampdu_queues)
+			ieee80211_ht_agg_queue_remove(local, sta, tid, 0);
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "BA request denied - HW unavailable for"
+					" tid %d\n", tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+		*state = HT_AGG_STATE_IDLE;
+		goto err_unlock_queue;
+	}
+
+	/* Will put all the packets in the new SW queue */
+	if (hw->ampdu_queues)
+		ieee80211_requeue(local, ieee802_1d_to_ac[tid]);
+	spin_unlock_bh(&sta->lock);
+
+	/* send an addBA request */
+	sta->ampdu_mlme.dialog_token_allocator++;
+	sta->ampdu_mlme.tid_tx[tid]->dialog_token =
+			sta->ampdu_mlme.dialog_token_allocator;
+	sta->ampdu_mlme.tid_tx[tid]->ssn = start_seq_num;
+
+
+	ieee80211_send_addba_request(sta->sdata, ra, tid,
+			 sta->ampdu_mlme.tid_tx[tid]->dialog_token,
+			 sta->ampdu_mlme.tid_tx[tid]->ssn,
+			 0x40, 5000);
+	/* activate the timer for the recipient's addBA response */
+	sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer.expires =
+				jiffies + ADDBA_RESP_INTERVAL;
+	add_timer(&sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer);
+#ifdef CONFIG_MAC80211_HT_DEBUG
+	printk(KERN_DEBUG "activated addBA response timer on tid %d\n", tid);
+#endif
+	goto exit;
+
+err_unlock_queue:
+	kfree(sta->ampdu_mlme.tid_tx[tid]);
+	sta->ampdu_mlme.tid_tx[tid] = NULL;
+	ret = -EBUSY;
+err_unlock_sta:
+	spin_unlock_bh(&sta->lock);
+exit:
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL(ieee80211_start_tx_ba_session);
+
+void ieee80211_start_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u16 tid)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct sta_info *sta;
+	u8 *state;
+
+	if (tid >= STA_TID_NUM) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "Bad TID value: tid = %d (>= %d)\n",
+				tid, STA_TID_NUM);
+#endif
+		return;
+	}
+
+	rcu_read_lock();
+	sta = sta_info_get(local, ra);
+	if (!sta) {
+		rcu_read_unlock();
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "Could not find station: %pM\n", ra);
+#endif
+		return;
+	}
+
+	state = &sta->ampdu_mlme.tid_state_tx[tid];
+	spin_lock_bh(&sta->lock);
+
+	if (!(*state & HT_ADDBA_REQUESTED_MSK)) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "addBA was not requested yet, state is %d\n",
+				*state);
+#endif
+		spin_unlock_bh(&sta->lock);
+		rcu_read_unlock();
+		return;
+	}
+
+	WARN_ON_ONCE(*state & HT_ADDBA_DRV_READY_MSK);
+
+	*state |= HT_ADDBA_DRV_READY_MSK;
+
+	if (*state == HT_AGG_STATE_OPERATIONAL) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "Aggregation is on for tid %d \n", tid);
+#endif
+		if (hw->ampdu_queues)
+			ieee80211_wake_queue(hw, sta->tid_to_tx_q[tid]);
+	}
+	spin_unlock_bh(&sta->lock);
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(ieee80211_start_tx_ba_cb);
+
+
+int ieee80211_stop_tx_ba_session(struct ieee80211_hw *hw,
+				 u8 *ra, u16 tid,
+				 enum ieee80211_back_parties initiator)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct sta_info *sta;
+	u8 *state;
+	int ret = 0;
+
+	if (tid >= STA_TID_NUM)
+		return -EINVAL;
+
+	rcu_read_lock();
+	sta = sta_info_get(local, ra);
+	if (!sta) {
+		rcu_read_unlock();
+		return -ENOENT;
+	}
+
+	/* check if the TID is in aggregation */
+	state = &sta->ampdu_mlme.tid_state_tx[tid];
+	spin_lock_bh(&sta->lock);
+
+	if (*state != HT_AGG_STATE_OPERATIONAL) {
+		ret = -ENOENT;
+		goto stop_BA_exit;
+	}
+
+#ifdef CONFIG_MAC80211_HT_DEBUG
+	printk(KERN_DEBUG "Tx BA session stop requested for %pM tid %u\n",
+	       ra, tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+
+	if (hw->ampdu_queues)
+		ieee80211_stop_queue(hw, sta->tid_to_tx_q[tid]);
+
+	*state = HT_AGG_STATE_REQ_STOP_BA_MSK |
+		(initiator << HT_AGG_STATE_INITIATOR_SHIFT);
+
+	if (local->ops->ampdu_action)
+		ret = local->ops->ampdu_action(hw, IEEE80211_AMPDU_TX_STOP,
+					       &sta->sta, tid, NULL);
+
+	/* case HW denied going back to legacy */
+	if (ret) {
+		WARN_ON(ret != -EBUSY);
+		*state = HT_AGG_STATE_OPERATIONAL;
+		if (hw->ampdu_queues)
+			ieee80211_wake_queue(hw, sta->tid_to_tx_q[tid]);
+		goto stop_BA_exit;
+	}
+
+stop_BA_exit:
+	spin_unlock_bh(&sta->lock);
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL(ieee80211_stop_tx_ba_session);
+
+void ieee80211_stop_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u8 tid)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct sta_info *sta;
+	u8 *state;
+	int agg_queue;
+
+	if (tid >= STA_TID_NUM) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "Bad TID value: tid = %d (>= %d)\n",
+				tid, STA_TID_NUM);
+#endif
+		return;
+	}
+
+#ifdef CONFIG_MAC80211_HT_DEBUG
+	printk(KERN_DEBUG "Stopping Tx BA session for %pM tid %d\n",
+	       ra, tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+
+	rcu_read_lock();
+	sta = sta_info_get(local, ra);
+	if (!sta) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "Could not find station: %pM\n", ra);
+#endif
+		rcu_read_unlock();
+		return;
+	}
+	state = &sta->ampdu_mlme.tid_state_tx[tid];
+
+	/* NOTE: no need to use sta->lock in this state check, as
+	 * ieee80211_stop_tx_ba_session will let only one stop call to
+	 * pass through per sta/tid
+	 */
+	if ((*state & HT_AGG_STATE_REQ_STOP_BA_MSK) == 0) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "unexpected callback to A-MPDU stop\n");
+#endif
+		rcu_read_unlock();
+		return;
+	}
+
+	if (*state & HT_AGG_STATE_INITIATOR_MSK)
+		ieee80211_send_delba(sta->sdata, ra, tid,
+			WLAN_BACK_INITIATOR, WLAN_REASON_QSTA_NOT_USE);
+
+	if (hw->ampdu_queues) {
+		agg_queue = sta->tid_to_tx_q[tid];
+		ieee80211_ht_agg_queue_remove(local, sta, tid, 1);
+
+		/* We just requeued the all the frames that were in the
+		 * removed queue, and since we might miss a softirq we do
+		 * netif_schedule_queue.  ieee80211_wake_queue is not used
+		 * here as this queue is not necessarily stopped
+		 */
+		netif_schedule_queue(netdev_get_tx_queue(local->mdev,
+							 agg_queue));
+	}
+	spin_lock_bh(&sta->lock);
+	*state = HT_AGG_STATE_IDLE;
+	sta->ampdu_mlme.addba_req_num[tid] = 0;
+	kfree(sta->ampdu_mlme.tid_tx[tid]);
+	sta->ampdu_mlme.tid_tx[tid] = NULL;
+	spin_unlock_bh(&sta->lock);
+
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(ieee80211_stop_tx_ba_cb);
+
+void ieee80211_start_tx_ba_cb_irqsafe(struct ieee80211_hw *hw,
+				      const u8 *ra, u16 tid)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct ieee80211_ra_tid *ra_tid;
+	struct sk_buff *skb = dev_alloc_skb(0);
+
+	if (unlikely(!skb)) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		if (net_ratelimit())
+			printk(KERN_WARNING "%s: Not enough memory, "
+			       "dropping start BA session", skb->dev->name);
+#endif
+		return;
+	}
+	ra_tid = (struct ieee80211_ra_tid *) &skb->cb;
+	memcpy(&ra_tid->ra, ra, ETH_ALEN);
+	ra_tid->tid = tid;
+
+	skb->pkt_type = IEEE80211_ADDBA_MSG;
+	skb_queue_tail(&local->skb_queue, skb);
+	tasklet_schedule(&local->tasklet);
+}
+EXPORT_SYMBOL(ieee80211_start_tx_ba_cb_irqsafe);
+
+void ieee80211_stop_tx_ba_cb_irqsafe(struct ieee80211_hw *hw,
+				     const u8 *ra, u16 tid)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct ieee80211_ra_tid *ra_tid;
+	struct sk_buff *skb = dev_alloc_skb(0);
+
+	if (unlikely(!skb)) {
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		if (net_ratelimit())
+			printk(KERN_WARNING "%s: Not enough memory, "
+			       "dropping stop BA session", skb->dev->name);
+#endif
+		return;
+	}
+	ra_tid = (struct ieee80211_ra_tid *) &skb->cb;
+	memcpy(&ra_tid->ra, ra, ETH_ALEN);
+	ra_tid->tid = tid;
+
+	skb->pkt_type = IEEE80211_DELBA_MSG;
+	skb_queue_tail(&local->skb_queue, skb);
+	tasklet_schedule(&local->tasklet);
+}
+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 ieee80211_hw *hw = &local->hw;
+	u16 capab;
+	u16 tid, start_seq_num;
+	u8 *state;
+
+	capab = le16_to_cpu(mgmt->u.action.u.addba_resp.capab);
+	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
+
+	state = &sta->ampdu_mlme.tid_state_tx[tid];
+
+	spin_lock_bh(&sta->lock);
+
+	if (!(*state & HT_ADDBA_REQUESTED_MSK)) {
+		spin_unlock_bh(&sta->lock);
+		return;
+	}
+
+	if (mgmt->u.action.u.addba_resp.dialog_token !=
+		sta->ampdu_mlme.tid_tx[tid]->dialog_token) {
+		spin_unlock_bh(&sta->lock);
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "wrong addBA response token, tid %d\n", tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+		return;
+	}
+
+	del_timer_sync(&sta->ampdu_mlme.tid_tx[tid]->addba_resp_timer);
+#ifdef CONFIG_MAC80211_HT_DEBUG
+	printk(KERN_DEBUG "switched off addBA timer for tid %d \n", tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+	if (le16_to_cpu(mgmt->u.action.u.addba_resp.status)
+			== WLAN_STATUS_SUCCESS) {
+		*state |= HT_ADDBA_RECEIVED_MSK;
+		sta->ampdu_mlme.addba_req_num[tid] = 0;
+
+		if (*state == HT_AGG_STATE_OPERATIONAL &&
+		    local->hw.ampdu_queues)
+			ieee80211_wake_queue(hw, sta->tid_to_tx_q[tid]);
+
+		if (local->ops->ampdu_action) {
+			(void)local->ops->ampdu_action(hw,
+					       IEEE80211_AMPDU_TX_RESUME,
+					       &sta->sta, tid, &start_seq_num);
+		}
+#ifdef CONFIG_MAC80211_HT_DEBUG
+		printk(KERN_DEBUG "Resuming TX aggregation for tid %d\n", tid);
+#endif /* CONFIG_MAC80211_HT_DEBUG */
+		spin_unlock_bh(&sta->lock);
+	} else {
+		sta->ampdu_mlme.addba_req_num[tid]++;
+		/* this will allow the state check in stop_BA_session */
+		*state = HT_AGG_STATE_OPERATIONAL;
+		spin_unlock_bh(&sta->lock);
+		ieee80211_stop_tx_ba_session(hw, sta->sta.addr, tid,
+					     WLAN_BACK_INITIATOR);
+	}
+}

net/mac80211/ieee80211_i.h

@@ -987,6 +987,9 @@ u32 ieee80211_enable_ht(struct ieee80211_sub_if_data *sdata,
 			struct ieee80211_ht_info *hti,
 			u16 ap_ht_cap_flags);
 void ieee80211_send_bar(struct ieee80211_sub_if_data *sdata, u8 *ra, u16 tid, u16 ssn);
+void ieee80211_send_delba(struct ieee80211_sub_if_data *sdata,
+			  const u8 *da, u16 tid,
+			  u16 initiator, u16 reason_code);
 
 void ieee80211_sta_stop_rx_ba_session(struct ieee80211_sub_if_data *sdata, u8 *da,
 				u16 tid, u16 initiator, u16 reason);