net/mac80211/agg-rx.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * 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
  */

 /**
  * 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 <linux/export.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++)
 		__skb_queue_purge(&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;
 	struct ieee80211_ampdu_params params = {
 		.sta = &sta->sta,
 		.action = IEEE80211_AMPDU_RX_STOP,
 		.tid = tid,
 		.amsdu = false,
 		.timeout = 0,
 		.ssn = 0,
 	};

 	lockdep_assert_held(&sta->ampdu_mlme.mtx);

 	tid_rx = rcu_dereference_protected(sta->ampdu_mlme.tid_rx[tid],
 					lockdep_is_held(&sta->ampdu_mlme.mtx));

 	if (!test_bit(tid, sta->ampdu_mlme.agg_session_valid))
 		return;

 	RCU_INIT_POINTER(sta->ampdu_mlme.tid_rx[tid], NULL);
 	__clear_bit(tid, sta->ampdu_mlme.agg_session_valid);

 	ht_dbg(sta->sdata,
 	       "Rx BA session stop requested for %pM tid %u %s reason: %d\n",
 	       sta->sta.addr, tid,
 	       initiator == WLAN_BACK_RECIPIENT ? "recipient" : "initiator",
 	       (int)reason);

 	if (drv_ampdu_action(local, sta->sdata, &params))
 		sdata_info(sta->sdata,
 			   "HW problem - can not stop rx aggregation for %pM tid %d\n",
 			   sta->sta.addr, 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, WLAN_BACK_RECIPIENT, reason);

 	/*
 	 * return here in case tid_rx is not assigned - which will happen if
 	 * IEEE80211_HW_SUPPORTS_REORDERING_BUFFER is set.
 	 */
 	if (!tid_rx)
 		return;

 	del_timer_sync(&tid_rx->session_timer);

 	/* make sure ieee80211_sta_reorder_release() doesn't re-arm the timer */
 	spin_lock_bh(&tid_rx->reorder_lock);
 	tid_rx->removed = true;
 	spin_unlock_bh(&tid_rx->reorder_lock);
 	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);
 }

 void ieee80211_stop_rx_ba_session(struct ieee80211_vif *vif, u16 ba_rx_bitmap,
 				  const u8 *addr)
 {
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 	struct sta_info *sta;
 	int i;

 	rcu_read_lock();
 	sta = sta_info_get_bss(sdata, addr);
 	if (!sta) {
 		rcu_read_unlock();
 		return;
 	}

 	for (i = 0; i < IEEE80211_NUM_TIDS; i++)
 		if (ba_rx_bitmap & BIT(i))
 			set_bit(i, sta->ampdu_mlme.tid_rx_stop_requested);

 	ieee80211_queue_work(&sta->local->hw, &sta->ampdu_mlme.work);
 	rcu_read_unlock();
 }
 EXPORT_SYMBOL(ieee80211_stop_rx_ba_session);

 /*
  * 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(struct timer_list *t)
 {
 	struct tid_ampdu_rx *tid_rx = from_timer(tid_rx, t, session_timer);
 	struct sta_info *sta = tid_rx->sta;
 	u8 tid = tid_rx->tid;
 	unsigned long timeout;

 	timeout = tid_rx->last_rx + TU_TO_JIFFIES(tid_rx->timeout);
 	if (time_is_after_jiffies(timeout)) {
 		mod_timer(&tid_rx->session_timer, timeout);
 		return;
 	}

 	ht_dbg(sta->sdata, "RX session timer expired on %pM tid %d\n",
 	       sta->sta.addr, tid);

 	set_bit(tid, 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(struct timer_list *t)
 {
 	struct tid_ampdu_rx *tid_rx = from_timer(tid_rx, t, reorder_timer);

 	rcu_read_lock();
 	ieee80211_release_reorder_timeout(tid_rx->sta, tid_rx->tid);
 	rcu_read_unlock();
 }

 static void ieee80211_add_addbaext(struct ieee80211_sub_if_data *sdata,
 				   struct sk_buff *skb,
 				   const struct ieee80211_addba_ext_ie *req)
 {
 	struct ieee80211_supported_band *sband;
 	struct ieee80211_addba_ext_ie *resp;
 	const struct ieee80211_sta_he_cap *he_cap;
 	u8 frag_level, cap_frag_level;
 	u8 *pos;

 	sband = ieee80211_get_sband(sdata);
 	if (!sband)
 		return;
 	he_cap = ieee80211_get_he_iftype_cap(sband, sdata->vif.type);
 	if (!he_cap)
 		return;

 	pos = skb_put_zero(skb, 2 + sizeof(struct ieee80211_addba_ext_ie));
 	*pos++ = WLAN_EID_ADDBA_EXT;
 	*pos++ = sizeof(struct ieee80211_addba_ext_ie);
 	resp = (struct ieee80211_addba_ext_ie *)pos;
 	resp->data = req->data & IEEE80211_ADDBA_EXT_NO_FRAG;

 	frag_level = u32_get_bits(req->data,
 				  IEEE80211_ADDBA_EXT_FRAG_LEVEL_MASK);
 	cap_frag_level = u32_get_bits(he_cap->he_cap_elem.mac_cap_info[0],
 				      IEEE80211_HE_MAC_CAP0_DYNAMIC_FRAG_MASK);
 	if (frag_level > cap_frag_level)
 		frag_level = cap_frag_level;
 	resp->data |= u8_encode_bits(frag_level,
 				     IEEE80211_ADDBA_EXT_FRAG_LEVEL_MASK);
 }

 static void ieee80211_send_addba_resp(struct sta_info *sta, u8 *da, u16 tid,
 				      u8 dialog_token, u16 status, u16 policy,
 				      u16 buf_size, u16 timeout,
 				      const struct ieee80211_addba_ext_ie *addbaext)
 {
 	struct ieee80211_sub_if_data *sdata = sta->sdata;
 	struct ieee80211_local *local = sdata->local;
 	struct sk_buff *skb;
 	struct ieee80211_mgmt *mgmt;
 	bool amsdu = ieee80211_hw_check(&local->hw, SUPPORTS_AMSDU_IN_AMPDU);
 	u16 capab;

 	skb = dev_alloc_skb(sizeof(*mgmt) +
 		    2 + sizeof(struct ieee80211_addba_ext_ie) +
 		    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_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)(amsdu << 0);	/* bit 0 A-MSDU support */
 	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);

 	if (sta->sta.he_cap.has_he && addbaext)
 		ieee80211_add_addbaext(sdata, skb, addbaext);

 	ieee80211_tx_skb(sdata, skb);
 }

 void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
 				      u8 dialog_token, u16 timeout,
 				      u16 start_seq_num, u16 ba_policy, u16 tid,
 				      u16 buf_size, bool tx, bool auto_seq,
 				      const struct ieee80211_addba_ext_ie *addbaext)
 {
 	struct ieee80211_local *local = sta->sdata->local;
 	struct tid_ampdu_rx *tid_agg_rx;
 	struct ieee80211_ampdu_params params = {
 		.sta = &sta->sta,
 		.action = IEEE80211_AMPDU_RX_START,
 		.tid = tid,
 		.amsdu = false,
 		.timeout = timeout,
 		.ssn = start_seq_num,
 	};
 	int i, ret = -EOPNOTSUPP;
 	u16 status = WLAN_STATUS_REQUEST_DECLINED;
 	u16 max_buf_size;

 	if (tid >= IEEE80211_FIRST_TSPEC_TSID) {
 		ht_dbg(sta->sdata,
 		       "STA %pM requests BA session on unsupported tid %d\n",
 		       sta->sta.addr, tid);
 		goto end;
 	}

 	if (!sta->sta.ht_cap.ht_supported) {
 		ht_dbg(sta->sdata,
 		       "STA %pM erroneously requests BA session on tid %d w/o QoS\n",
 		       sta->sta.addr, tid);
 		/* send a response anyway, it's an error case if we get here */
 		goto end;
 	}

 	if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) {
 		ht_dbg(sta->sdata,
 		       "Suspend in progress - Denying ADDBA request (%pM tid %d)\n",
 		       sta->sta.addr, tid);
 		goto end;
 	}

 	if (sta->sta.he_cap.has_he)
 		max_buf_size = IEEE80211_MAX_AMPDU_BUF;
 	else
 		max_buf_size = IEEE80211_MAX_AMPDU_BUF_HT;

 	/* 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 > max_buf_size)) {
 		status = WLAN_STATUS_INVALID_QOS_PARAM;
 		ht_dbg_ratelimited(sta->sdata,
 				   "AddBA Req with bad params from %pM on tid %u. policy %d, buffer size %d\n",
 				   sta->sta.addr, tid, ba_policy, buf_size);
 		goto end;
 	}
 	/* determine default buffer size */
 	if (buf_size == 0)
 		buf_size = max_buf_size;

 	/* make sure the size doesn't exceed the maximum supported by the hw */
 	if (buf_size > sta->sta.max_rx_aggregation_subframes)
 		buf_size = sta->sta.max_rx_aggregation_subframes;
 	params.buf_size = buf_size;

 	ht_dbg(sta->sdata, "AddBA Req buf_size=%d for %pM\n",
 	       buf_size, sta->sta.addr);

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

 	if (test_bit(tid, sta->ampdu_mlme.agg_session_valid)) {
 		if (sta->ampdu_mlme.tid_rx_token[tid] == dialog_token) {
 			struct tid_ampdu_rx *tid_rx;

 			ht_dbg_ratelimited(sta->sdata,
 					   "updated AddBA Req from %pM on tid %u\n",
 					   sta->sta.addr, tid);
 			/* We have no API to update the timeout value in the
 			 * driver so reject the timeout update if the timeout
 			 * changed. If if did not change, i.e., no real update,
 			 * just reply with success.
 			 */
 			rcu_read_lock();
 			tid_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
 			if (tid_rx && tid_rx->timeout == timeout)
 				status = WLAN_STATUS_SUCCESS;
 			else
 				status = WLAN_STATUS_REQUEST_DECLINED;
 			rcu_read_unlock();
 			goto end;
 		}

 		ht_dbg_ratelimited(sta->sdata,
 				   "unexpected AddBA Req from %pM on tid %u\n",
 				   sta->sta.addr, tid);

 		/* delete existing Rx BA session on the same tid */
 		___ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_RECIPIENT,
 						WLAN_STATUS_UNSPECIFIED_QOS,
 						false);
 	}

 	if (ieee80211_hw_check(&local->hw, SUPPORTS_REORDERING_BUFFER)) {
 		ret = drv_ampdu_action(local, sta->sdata, &params);
 		ht_dbg(sta->sdata,
 		       "Rx A-MPDU request on %pM tid %d result %d\n",
 		       sta->sta.addr, tid, ret);
 		if (!ret)
 			status = WLAN_STATUS_SUCCESS;
 		goto end;
 	}

 	/* prepare A-MPDU MLME for Rx aggregation */
 	tid_agg_rx = kzalloc(sizeof(*tid_agg_rx), GFP_KERNEL);
 	if (!tid_agg_rx)
 		goto end;

 	spin_lock_init(&tid_agg_rx->reorder_lock);

 	/* rx timer */
 	timer_setup(&tid_agg_rx->session_timer,
 		    sta_rx_agg_session_timer_expired, TIMER_DEFERRABLE);

 	/* rx reorder timer */
 	timer_setup(&tid_agg_rx->reorder_timer,
 		    sta_rx_agg_reorder_timer_expired, 0);

 	/* prepare reordering buffer */
 	tid_agg_rx->reorder_buf =
 		kcalloc(buf_size, sizeof(struct sk_buff_head), 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) {
 		kfree(tid_agg_rx->reorder_buf);
 		kfree(tid_agg_rx->reorder_time);
 		kfree(tid_agg_rx);
 		goto end;
 	}

 	for (i = 0; i < buf_size; i++)
 		__skb_queue_head_init(&tid_agg_rx->reorder_buf[i]);

 	ret = drv_ampdu_action(local, sta->sdata, &params);
 	ht_dbg(sta->sdata, "Rx A-MPDU request on %pM tid %d result %d\n",
 	       sta->sta.addr, tid, ret);
 	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->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;
 	tid_agg_rx->auto_seq = auto_seq;
 	tid_agg_rx->started = false;
 	tid_agg_rx->reorder_buf_filtered = 0;
 	tid_agg_rx->tid = tid;
 	tid_agg_rx->sta = sta;
 	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));
 		tid_agg_rx->last_rx = jiffies;
 	}

 end:
 	if (status == WLAN_STATUS_SUCCESS) {
 		__set_bit(tid, sta->ampdu_mlme.agg_session_valid);
 		__clear_bit(tid, sta->ampdu_mlme.unexpected_agg);
 		sta->ampdu_mlme.tid_rx_token[tid] = dialog_token;
 	}

 	if (tx)
 		ieee80211_send_addba_resp(sta, sta->sta.addr, tid,
 					  dialog_token, status, 1, buf_size,
 					  timeout, addbaext);
 }

 static void __ieee80211_start_rx_ba_session(struct sta_info *sta,
 					    u8 dialog_token, u16 timeout,
 					    u16 start_seq_num, u16 ba_policy,
 					    u16 tid, u16 buf_size, bool tx,
 					    bool auto_seq,
 					    const struct ieee80211_addba_ext_ie *addbaext)
 {
 	mutex_lock(&sta->ampdu_mlme.mtx);
 	___ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
 					 start_seq_num, ba_policy, tid,
 					 buf_size, tx, auto_seq, addbaext);
 	mutex_unlock(&sta->ampdu_mlme.mtx);
 }

 void ieee80211_process_addba_request(struct ieee80211_local *local,
 				     struct sta_info *sta,
 				     struct ieee80211_mgmt *mgmt,
 				     size_t len)
 {
 	u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num;
 	struct ieee802_11_elems elems = { 0 };
 	u8 dialog_token;
 	int ies_len;

 	/* 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;

 	ies_len = len - offsetof(struct ieee80211_mgmt,
 				 u.action.u.addba_req.variable);
 	if (ies_len) {
 		ieee802_11_parse_elems(mgmt->u.action.u.addba_req.variable,
                                 ies_len, true, &elems, mgmt->bssid, NULL);
 		if (elems.parse_error)
 			return;
 	}

 	__ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
 					start_seq_num, ba_policy, tid,
 					buf_size, true, false,
 					elems.addba_ext_ie);
 }

 void ieee80211_manage_rx_ba_offl(struct ieee80211_vif *vif,
 				 const u8 *addr, unsigned int tid)
 {
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta;

 	rcu_read_lock();
 	sta = sta_info_get_bss(sdata, addr);
 	if (!sta)
 		goto unlock;

 	set_bit(tid, sta->ampdu_mlme.tid_rx_manage_offl);
 	ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);
  unlock:
 	rcu_read_unlock();
 }
 EXPORT_SYMBOL(ieee80211_manage_rx_ba_offl);

 void ieee80211_rx_ba_timer_expired(struct ieee80211_vif *vif,
 				   const u8 *addr, unsigned int tid)
 {
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta;

 	rcu_read_lock();
 	sta = sta_info_get_bss(sdata, addr);
 	if (!sta)
 		goto unlock;

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

  unlock:
 	rcu_read_unlock();
 }
 EXPORT_SYMBOL(ieee80211_rx_ba_timer_expired);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* 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
	*/

	/**
	* 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 <linux/export.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++)
	__skb_queue_purge(&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;
	struct ieee80211_ampdu_params params = {
	.sta = &sta->sta,
	.action = IEEE80211_AMPDU_RX_STOP,
	.tid = tid,
	.amsdu = false,
	.timeout = 0,
	.ssn = 0,
	};

	lockdep_assert_held(&sta->ampdu_mlme.mtx);

	tid_rx = rcu_dereference_protected(sta->ampdu_mlme.tid_rx[tid],
	lockdep_is_held(&sta->ampdu_mlme.mtx));

	if (!test_bit(tid, sta->ampdu_mlme.agg_session_valid))
	return;

	RCU_INIT_POINTER(sta->ampdu_mlme.tid_rx[tid], NULL);
	__clear_bit(tid, sta->ampdu_mlme.agg_session_valid);

	ht_dbg(sta->sdata,
	"Rx BA session stop requested for %pM tid %u %s reason: %d\n",
	sta->sta.addr, tid,
	initiator == WLAN_BACK_RECIPIENT ? "recipient" : "initiator",
	(int)reason);

	if (drv_ampdu_action(local, sta->sdata, &params))
	sdata_info(sta->sdata,
	"HW problem - can not stop rx aggregation for %pM tid %d\n",
	sta->sta.addr, 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, WLAN_BACK_RECIPIENT, reason);

	/*
	* return here in case tid_rx is not assigned - which will happen if
	* IEEE80211_HW_SUPPORTS_REORDERING_BUFFER is set.
	*/
	if (!tid_rx)
	return;

	del_timer_sync(&tid_rx->session_timer);

	/* make sure ieee80211_sta_reorder_release() doesn't re-arm the timer */
	spin_lock_bh(&tid_rx->reorder_lock);
	tid_rx->removed = true;
	spin_unlock_bh(&tid_rx->reorder_lock);
	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);
	}

	void ieee80211_stop_rx_ba_session(struct ieee80211_vif *vif, u16 ba_rx_bitmap,
	const u8 *addr)
	{
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	struct sta_info *sta;
	int i;

	rcu_read_lock();
	sta = sta_info_get_bss(sdata, addr);
	if (!sta) {
	rcu_read_unlock();
	return;
	}

	for (i = 0; i < IEEE80211_NUM_TIDS; i++)
	if (ba_rx_bitmap & BIT(i))
	set_bit(i, sta->ampdu_mlme.tid_rx_stop_requested);

	ieee80211_queue_work(&sta->local->hw, &sta->ampdu_mlme.work);
	rcu_read_unlock();
	}
	EXPORT_SYMBOL(ieee80211_stop_rx_ba_session);

	/*
	* 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(struct timer_list *t)
	{
	struct tid_ampdu_rx *tid_rx = from_timer(tid_rx, t, session_timer);
	struct sta_info *sta = tid_rx->sta;
	u8 tid = tid_rx->tid;
	unsigned long timeout;

	timeout = tid_rx->last_rx + TU_TO_JIFFIES(tid_rx->timeout);
	if (time_is_after_jiffies(timeout)) {
	mod_timer(&tid_rx->session_timer, timeout);
	return;
	}

	ht_dbg(sta->sdata, "RX session timer expired on %pM tid %d\n",
	sta->sta.addr, tid);

	set_bit(tid, 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(struct timer_list *t)
	{
	struct tid_ampdu_rx *tid_rx = from_timer(tid_rx, t, reorder_timer);

	rcu_read_lock();
	ieee80211_release_reorder_timeout(tid_rx->sta, tid_rx->tid);
	rcu_read_unlock();
	}

	static void ieee80211_add_addbaext(struct ieee80211_sub_if_data *sdata,
	struct sk_buff *skb,
	const struct ieee80211_addba_ext_ie *req)
	{
	struct ieee80211_supported_band *sband;
	struct ieee80211_addba_ext_ie *resp;
	const struct ieee80211_sta_he_cap *he_cap;
	u8 frag_level, cap_frag_level;
	u8 *pos;

	sband = ieee80211_get_sband(sdata);
	if (!sband)
	return;
	he_cap = ieee80211_get_he_iftype_cap(sband, sdata->vif.type);
	if (!he_cap)
	return;

	pos = skb_put_zero(skb, 2 + sizeof(struct ieee80211_addba_ext_ie));
	*pos++ = WLAN_EID_ADDBA_EXT;
	*pos++ = sizeof(struct ieee80211_addba_ext_ie);
	resp = (struct ieee80211_addba_ext_ie *)pos;
	resp->data = req->data & IEEE80211_ADDBA_EXT_NO_FRAG;

	frag_level = u32_get_bits(req->data,
	IEEE80211_ADDBA_EXT_FRAG_LEVEL_MASK);
	cap_frag_level = u32_get_bits(he_cap->he_cap_elem.mac_cap_info[0],
	IEEE80211_HE_MAC_CAP0_DYNAMIC_FRAG_MASK);
	if (frag_level > cap_frag_level)
	frag_level = cap_frag_level;
	resp->data \|= u8_encode_bits(frag_level,
	IEEE80211_ADDBA_EXT_FRAG_LEVEL_MASK);
	}

	static void ieee80211_send_addba_resp(struct sta_info sta, u8 da, u16 tid,
	u8 dialog_token, u16 status, u16 policy,
	u16 buf_size, u16 timeout,
	const struct ieee80211_addba_ext_ie *addbaext)
	{
	struct ieee80211_sub_if_data *sdata = sta->sdata;
	struct ieee80211_local *local = sdata->local;
	struct sk_buff *skb;
	struct ieee80211_mgmt *mgmt;
	bool amsdu = ieee80211_hw_check(&local->hw, SUPPORTS_AMSDU_IN_AMPDU);
	u16 capab;

	skb = dev_alloc_skb(sizeof(*mgmt) +
	2 + sizeof(struct ieee80211_addba_ext_ie) +
	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_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)(amsdu << 0); /* bit 0 A-MSDU support */
	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);

	if (sta->sta.he_cap.has_he && addbaext)
	ieee80211_add_addbaext(sdata, skb, addbaext);

	ieee80211_tx_skb(sdata, skb);
	}

	void ___ieee80211_start_rx_ba_session(struct sta_info *sta,
	u8 dialog_token, u16 timeout,
	u16 start_seq_num, u16 ba_policy, u16 tid,
	u16 buf_size, bool tx, bool auto_seq,
	const struct ieee80211_addba_ext_ie *addbaext)
	{
	struct ieee80211_local *local = sta->sdata->local;
	struct tid_ampdu_rx *tid_agg_rx;
	struct ieee80211_ampdu_params params = {
	.sta = &sta->sta,
	.action = IEEE80211_AMPDU_RX_START,
	.tid = tid,
	.amsdu = false,
	.timeout = timeout,
	.ssn = start_seq_num,
	};
	int i, ret = -EOPNOTSUPP;
	u16 status = WLAN_STATUS_REQUEST_DECLINED;
	u16 max_buf_size;

	if (tid >= IEEE80211_FIRST_TSPEC_TSID) {
	ht_dbg(sta->sdata,
	"STA %pM requests BA session on unsupported tid %d\n",
	sta->sta.addr, tid);
	goto end;
	}

	if (!sta->sta.ht_cap.ht_supported) {
	ht_dbg(sta->sdata,
	"STA %pM erroneously requests BA session on tid %d w/o QoS\n",
	sta->sta.addr, tid);
	/* send a response anyway, it's an error case if we get here */
	goto end;
	}

	if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) {
	ht_dbg(sta->sdata,
	"Suspend in progress - Denying ADDBA request (%pM tid %d)\n",
	sta->sta.addr, tid);
	goto end;
	}

	if (sta->sta.he_cap.has_he)
	max_buf_size = IEEE80211_MAX_AMPDU_BUF;
	else
	max_buf_size = IEEE80211_MAX_AMPDU_BUF_HT;

	/* 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 > max_buf_size)) {
	status = WLAN_STATUS_INVALID_QOS_PARAM;
	ht_dbg_ratelimited(sta->sdata,
	"AddBA Req with bad params from %pM on tid %u. policy %d, buffer size %d\n",
	sta->sta.addr, tid, ba_policy, buf_size);
	goto end;
	}
	/* determine default buffer size */
	if (buf_size == 0)
	buf_size = max_buf_size;

	/* make sure the size doesn't exceed the maximum supported by the hw */
	if (buf_size > sta->sta.max_rx_aggregation_subframes)
	buf_size = sta->sta.max_rx_aggregation_subframes;
	params.buf_size = buf_size;

	ht_dbg(sta->sdata, "AddBA Req buf_size=%d for %pM\n",
	buf_size, sta->sta.addr);

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

	if (test_bit(tid, sta->ampdu_mlme.agg_session_valid)) {
	if (sta->ampdu_mlme.tid_rx_token[tid] == dialog_token) {
	struct tid_ampdu_rx *tid_rx;

	ht_dbg_ratelimited(sta->sdata,
	"updated AddBA Req from %pM on tid %u\n",
	sta->sta.addr, tid);
	/* We have no API to update the timeout value in the
	* driver so reject the timeout update if the timeout
	* changed. If if did not change, i.e., no real update,
	* just reply with success.
	*/
	rcu_read_lock();
	tid_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
	if (tid_rx && tid_rx->timeout == timeout)
	status = WLAN_STATUS_SUCCESS;
	else
	status = WLAN_STATUS_REQUEST_DECLINED;
	rcu_read_unlock();
	goto end;
	}

	ht_dbg_ratelimited(sta->sdata,
	"unexpected AddBA Req from %pM on tid %u\n",
	sta->sta.addr, tid);

	/* delete existing Rx BA session on the same tid */
	___ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_RECIPIENT,
	WLAN_STATUS_UNSPECIFIED_QOS,
	false);
	}

	if (ieee80211_hw_check(&local->hw, SUPPORTS_REORDERING_BUFFER)) {
	ret = drv_ampdu_action(local, sta->sdata, &params);
	ht_dbg(sta->sdata,
	"Rx A-MPDU request on %pM tid %d result %d\n",
	sta->sta.addr, tid, ret);
	if (!ret)
	status = WLAN_STATUS_SUCCESS;
	goto end;
	}

	/* prepare A-MPDU MLME for Rx aggregation */
	tid_agg_rx = kzalloc(sizeof(*tid_agg_rx), GFP_KERNEL);
	if (!tid_agg_rx)
	goto end;

	spin_lock_init(&tid_agg_rx->reorder_lock);

	/* rx timer */
	timer_setup(&tid_agg_rx->session_timer,
	sta_rx_agg_session_timer_expired, TIMER_DEFERRABLE);

	/* rx reorder timer */
	timer_setup(&tid_agg_rx->reorder_timer,
	sta_rx_agg_reorder_timer_expired, 0);

	/* prepare reordering buffer */
	tid_agg_rx->reorder_buf =
	kcalloc(buf_size, sizeof(struct sk_buff_head), 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) {
	kfree(tid_agg_rx->reorder_buf);
	kfree(tid_agg_rx->reorder_time);
	kfree(tid_agg_rx);
	goto end;
	}

	for (i = 0; i < buf_size; i++)
	__skb_queue_head_init(&tid_agg_rx->reorder_buf[i]);

	ret = drv_ampdu_action(local, sta->sdata, &params);
	ht_dbg(sta->sdata, "Rx A-MPDU request on %pM tid %d result %d\n",
	sta->sta.addr, tid, ret);
	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->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;
	tid_agg_rx->auto_seq = auto_seq;
	tid_agg_rx->started = false;
	tid_agg_rx->reorder_buf_filtered = 0;
	tid_agg_rx->tid = tid;
	tid_agg_rx->sta = sta;
	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));
	tid_agg_rx->last_rx = jiffies;
	}

	end:
	if (status == WLAN_STATUS_SUCCESS) {
	__set_bit(tid, sta->ampdu_mlme.agg_session_valid);
	__clear_bit(tid, sta->ampdu_mlme.unexpected_agg);
	sta->ampdu_mlme.tid_rx_token[tid] = dialog_token;
	}

	if (tx)
	ieee80211_send_addba_resp(sta, sta->sta.addr, tid,
	dialog_token, status, 1, buf_size,
	timeout, addbaext);
	}

	static void __ieee80211_start_rx_ba_session(struct sta_info *sta,
	u8 dialog_token, u16 timeout,
	u16 start_seq_num, u16 ba_policy,
	u16 tid, u16 buf_size, bool tx,
	bool auto_seq,
	const struct ieee80211_addba_ext_ie *addbaext)
	{
	mutex_lock(&sta->ampdu_mlme.mtx);
	___ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
	start_seq_num, ba_policy, tid,
	buf_size, tx, auto_seq, addbaext);
	mutex_unlock(&sta->ampdu_mlme.mtx);
	}

	void ieee80211_process_addba_request(struct ieee80211_local *local,
	struct sta_info *sta,
	struct ieee80211_mgmt *mgmt,
	size_t len)
	{
	u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num;
	struct ieee802_11_elems elems = { 0 };
	u8 dialog_token;
	int ies_len;

	/* 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;

	ies_len = len - offsetof(struct ieee80211_mgmt,
	u.action.u.addba_req.variable);
	if (ies_len) {
	ieee802_11_parse_elems(mgmt->u.action.u.addba_req.variable,
	ies_len, true, &elems, mgmt->bssid, NULL);
	if (elems.parse_error)
	return;
	}

	__ieee80211_start_rx_ba_session(sta, dialog_token, timeout,
	start_seq_num, ba_policy, tid,
	buf_size, true, false,
	elems.addba_ext_ie);
	}

	void ieee80211_manage_rx_ba_offl(struct ieee80211_vif *vif,
	const u8 *addr, unsigned int tid)
	{
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;

	rcu_read_lock();
	sta = sta_info_get_bss(sdata, addr);
	if (!sta)
	goto unlock;

	set_bit(tid, sta->ampdu_mlme.tid_rx_manage_offl);
	ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);
	unlock:
	rcu_read_unlock();
	}
	EXPORT_SYMBOL(ieee80211_manage_rx_ba_offl);

	void ieee80211_rx_ba_timer_expired(struct ieee80211_vif *vif,
	const u8 *addr, unsigned int tid)
	{
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;

	rcu_read_lock();
	sta = sta_info_get_bss(sdata, addr);
	if (!sta)
	goto unlock;

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

	unlock:
	rcu_read_unlock();
	}
	EXPORT_SYMBOL(ieee80211_rx_ba_timer_expired);