summaryrefslogtreecommitdiffstats
path: root/net/mac80211/agg-tx.c
blob: 9bfe28c9ab59d87d7012c73841870d7f24204418 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
/*
 * 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.
 */

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

/**
 * DOC: TX A-MPDU aggregation
 *
 * Aggregation on the TX side requires setting the hardware flag
 * %IEEE80211_HW_AMPDU_AGGREGATION. The driver will then be handed
 * packets with a flag indicating A-MPDU aggregation. The driver
 * or device is responsible for actually aggregating the frames,
 * as well as deciding how many and which to aggregate.
 *
 * When TX aggregation is started by some subsystem (usually the rate
 * control algorithm would be appropriate) by calling the
 * ieee80211_start_tx_ba_session() function, the driver will be
 * notified via its @ampdu_action function, with the
 * %IEEE80211_AMPDU_TX_START action.
 *
 * In response to that, the driver is later required to call the
 * ieee80211_start_tx_ba_cb_irqsafe() function, which will really
 * start the aggregation session after the peer has also responded.
 * If the peer responds negatively, the session will be stopped
 * again right away. Note that it is possible for the aggregation
 * session to be stopped before the driver has indicated that it
 * is done setting it up, in which case it must not indicate the
 * setup completion.
 *
 * Also note that, since we also need to wait for a response from
 * the peer, the driver is notified of the completion of the
 * handshake by the %IEEE80211_AMPDU_TX_OPERATIONAL action to the
 * @ampdu_action callback.
 *
 * Similarly, when the aggregation session is stopped by the peer
 * or something calling ieee80211_stop_tx_ba_session(), the driver's
 * @ampdu_action function will be called with the action
 * %IEEE80211_AMPDU_TX_STOP. In this case, the call must not fail,
 * and the driver must later call ieee80211_stop_tx_ba_cb_irqsafe().
 */

static void ieee80211_send_addba_request(struct ieee80211_sub_if_data *sdata,
					 const u8 *da, u16 tid,
					 u8 dialog_token, u16 start_seq_num,
					 u16 agg_size, u16 timeout)
{
	struct ieee80211_local *local = sdata->local;
	struct sk_buff *skb;
	struct ieee80211_mgmt *mgmt;
	u16 capab;

	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);

	if (!skb)
		return;

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

	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);
}

void ieee80211_send_bar(struct ieee80211_vif *vif, u8 *ra, u16 tid, u16 ssn)
{
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	struct ieee80211_local *local = sdata->local;
	struct sk_buff *skb;
	struct ieee80211_bar *bar;
	u16 bar_control = 0;

	skb = dev_alloc_skb(sizeof(*bar) + local->hw.extra_tx_headroom);
	if (!skb)
		return;

	skb_reserve(skb, local->hw.extra_tx_headroom);
	bar = (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->vif.addr, ETH_ALEN);
	bar_control |= (u16)IEEE80211_BAR_CTRL_ACK_POLICY_NORMAL;
	bar_control |= (u16)IEEE80211_BAR_CTRL_CBMTID_COMPRESSED_BA;
	bar_control |= (u16)(tid << IEEE80211_BAR_CTRL_TID_INFO_SHIFT);
	bar->control = cpu_to_le16(bar_control);
	bar->start_seq_num = cpu_to_le16(ssn);

	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
	ieee80211_tx_skb(sdata, skb);
}
EXPORT_SYMBOL(ieee80211_send_bar);

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

int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,
				    enum ieee80211_back_parties initiator,
				    bool tx)
{
	struct ieee80211_local *local = sta->local;
	struct tid_ampdu_tx *tid_tx;
	int ret;

	lockdep_assert_held(&sta->ampdu_mlme.mtx);

	spin_lock_bh(&sta->lock);

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

	/* if we're already stopping ignore any new requests to stop */
	if (test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
		spin_unlock_bh(&sta->lock);
		return -EALREADY;
	}

	if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state)) {
		/* not even started yet! */
		ieee80211_assign_tid_tx(sta, tid, NULL);
		spin_unlock_bh(&sta->lock);
		kfree_rcu(tid_tx, rcu_head);
		return 0;
	}

	set_bit(HT_AGG_STATE_STOPPING, &tid_tx->state);

	spin_unlock_bh(&sta->lock);

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

	del_timer_sync(&tid_tx->addba_resp_timer);
	del_timer_sync(&tid_tx->session_timer);

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

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

	tid_tx->stop_initiator = initiator;
	tid_tx->tx_stop = tx;

	ret = drv_ampdu_action(local, sta->sdata,
			       IEEE80211_AMPDU_TX_STOP,
			       &sta->sta, tid, NULL, 0);

	/* HW shall not deny going back to legacy */
	if (WARN_ON(ret)) {
		/*
		 * We may have pending packets get stuck in this case...
		 * Not bothering with a workaround for now.
		 */
	}

	return ret;
}

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

	/* check if the TID waits for addBA response */
	rcu_read_lock();
	tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[tid]);
	if (!tid_tx ||
	    test_bit(HT_AGG_STATE_RESPONSE_RECEIVED, &tid_tx->state)) {
		rcu_read_unlock();
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "timer expired on tid %d but we are not "
				"(or no longer) expecting addBA response there\n",
			tid);
#endif
		return;
	}

#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "addBA response timer expired on tid %d\n", tid);
#endif

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

static inline int ieee80211_ac_from_tid(int tid)
{
	return ieee802_1d_to_ac[tid & 7];
}

/*
 * When multiple aggregation sessions on multiple stations
 * are being created/destroyed simultaneously, we need to
 * refcount the global queue stop caused by that in order
 * to not get into a situation where one of the aggregation
 * setup or teardown re-enables queues before the other is
 * ready to handle that.
 *
 * These two functions take care of this issue by keeping
 * a global "agg_queue_stop" refcount.
 */
static void __acquires(agg_queue)
ieee80211_stop_queue_agg(struct ieee80211_local *local, int tid)
{
	int queue = ieee80211_ac_from_tid(tid);

	if (atomic_inc_return(&local->agg_queue_stop[queue]) == 1)
		ieee80211_stop_queue_by_reason(
			&local->hw, queue,
			IEEE80211_QUEUE_STOP_REASON_AGGREGATION);
	__acquire(agg_queue);
}

static void __releases(agg_queue)
ieee80211_wake_queue_agg(struct ieee80211_local *local, int tid)
{
	int queue = ieee80211_ac_from_tid(tid);

	if (atomic_dec_return(&local->agg_queue_stop[queue]) == 0)
		ieee80211_wake_queue_by_reason(
			&local->hw, queue,
			IEEE80211_QUEUE_STOP_REASON_AGGREGATION);
	__release(agg_queue);
}

void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid)
{
	struct tid_ampdu_tx *tid_tx;
	struct ieee80211_local *local = sta->local;
	struct ieee80211_sub_if_data *sdata = sta->sdata;
	u16 start_seq_num;
	int ret;

	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

	/*
	 * While we're asking the driver about the aggregation,
	 * stop the AC queue so that we don't have to worry
	 * about frames that came in while we were doing that,
	 * which would require us to put them to the AC pending
	 * afterwards which just makes the code more complex.
	 */
	ieee80211_stop_queue_agg(local, tid);

	clear_bit(HT_AGG_STATE_WANT_START, &tid_tx->state);

	/*
	 * make sure no packets are being processed to get
	 * valid starting sequence number
	 */
	synchronize_net();

	start_seq_num = sta->tid_seq[tid] >> 4;

	ret = drv_ampdu_action(local, sdata, IEEE80211_AMPDU_TX_START,
			       &sta->sta, tid, &start_seq_num, 0);
	if (ret) {
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "BA request denied - HW unavailable for"
					" tid %d\n", tid);
#endif
		spin_lock_bh(&sta->lock);
		ieee80211_assign_tid_tx(sta, tid, NULL);
		spin_unlock_bh(&sta->lock);

		ieee80211_wake_queue_agg(local, tid);
		kfree_rcu(tid_tx, rcu_head);
		return;
	}

	/* we can take packets again now */
	ieee80211_wake_queue_agg(local, tid);

	/* activate the timer for the recipient's addBA response */
	mod_timer(&tid_tx->addba_resp_timer, jiffies + ADDBA_RESP_INTERVAL);
#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "activated addBA response timer on tid %d\n", tid);
#endif

	spin_lock_bh(&sta->lock);
	sta->ampdu_mlme.addba_req_num[tid]++;
	spin_unlock_bh(&sta->lock);

	/* send AddBA request */
	ieee80211_send_addba_request(sdata, sta->sta.addr, tid,
				     tid_tx->dialog_token, start_seq_num,
				     local->hw.max_tx_aggregation_subframes,
				     tid_tx->timeout);
}

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

#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "tx session timer expired on tid %d\n", (u16)*ptid);
#endif

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

int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid,
				  u16 timeout)
{
	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
	struct ieee80211_sub_if_data *sdata = sta->sdata;
	struct ieee80211_local *local = sdata->local;
	struct tid_ampdu_tx *tid_tx;
	int ret = 0;

	trace_api_start_tx_ba_session(pubsta, tid);

	if (WARN_ON(!local->ops->ampdu_action))
		return -EINVAL;

	if ((tid >= STA_TID_NUM) ||
	    !(local->hw.flags & IEEE80211_HW_AMPDU_AGGREGATION) ||
	    (local->hw.flags & IEEE80211_HW_TX_AMPDU_SETUP_IN_HW))
		return -EINVAL;

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

	if (sdata->vif.type != NL80211_IFTYPE_STATION &&
	    sdata->vif.type != NL80211_IFTYPE_MESH_POINT &&
	    sdata->vif.type != NL80211_IFTYPE_AP_VLAN &&
	    sdata->vif.type != NL80211_IFTYPE_AP)
		return -EINVAL;

	if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) {
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "BA sessions blocked. "
		       "Denying BA session request\n");
#endif
		return -EINVAL;
	}

	/*
	 * 802.11n-2009 11.5.1.1: If the initiating STA is an HT STA, is a
	 * member of an IBSS, and has no other existing Block Ack agreement
	 * with the recipient STA, then the initiating STA shall transmit a
	 * Probe Request frame to the recipient STA and shall not transmit an
	 * ADDBA Request frame unless it receives a Probe Response frame
	 * from the recipient within dot11ADDBAFailureTimeout.
	 *
	 * The probe request mechanism for ADDBA is currently not implemented,
	 * but we only build up Block Ack session with HT STAs. This information
	 * is set when we receive a bss info from a probe response or a beacon.
	 */
	if (sta->sdata->vif.type == NL80211_IFTYPE_ADHOC &&
	    !sta->sta.ht_cap.ht_supported) {
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "BA request denied - IBSS STA %pM"
		       "does not advertise HT support\n", pubsta->addr);
#endif /* CONFIG_MAC80211_HT_DEBUG */
		return -EINVAL;
	}

	spin_lock_bh(&sta->lock);

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

	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
	/* check if the TID is not in aggregation flow already */
	if (tid_tx || sta->ampdu_mlme.tid_start_tx[tid]) {
#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 */
	tid_tx = kzalloc(sizeof(struct tid_ampdu_tx), GFP_ATOMIC);
	if (!tid_tx) {
		ret = -ENOMEM;
		goto err_unlock_sta;
	}

	skb_queue_head_init(&tid_tx->pending);
	__set_bit(HT_AGG_STATE_WANT_START, &tid_tx->state);

	tid_tx->timeout = timeout;

	/* response timer */
	tid_tx->addba_resp_timer.function = sta_addba_resp_timer_expired;
	tid_tx->addba_resp_timer.data = (unsigned long)&sta->timer_to_tid[tid];
	init_timer(&tid_tx->addba_resp_timer);

	/* tx timer */
	tid_tx->session_timer.function = sta_tx_agg_session_timer_expired;
	tid_tx->session_timer.data = (unsigned long)&sta->timer_to_tid[tid];
	init_timer(&tid_tx->session_timer);

	/* assign a dialog token */
	sta->ampdu_mlme.dialog_token_allocator++;
	tid_tx->dialog_token = sta->ampdu_mlme.dialog_token_allocator;

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

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

	/* this flow continues off the work */
 err_unlock_sta:
	spin_unlock_bh(&sta->lock);
	return ret;
}
EXPORT_SYMBOL(ieee80211_start_tx_ba_session);

/*
 * splice packets from the STA's pending to the local pending,
 * requires a call to ieee80211_agg_splice_finish later
 */
static void __acquires(agg_queue)
ieee80211_agg_splice_packets(struct ieee80211_local *local,
			     struct tid_ampdu_tx *tid_tx, u16 tid)
{
	int queue = ieee80211_ac_from_tid(tid);
	unsigned long flags;

	ieee80211_stop_queue_agg(local, tid);

	if (WARN(!tid_tx, "TID %d gone but expected when splicing aggregates"
			  " from the pending queue\n", tid))
		return;

	if (!skb_queue_empty(&tid_tx->pending)) {
		spin_lock_irqsave(&local->queue_stop_reason_lock, flags);
		/* copy over remaining packets */
		skb_queue_splice_tail_init(&tid_tx->pending,
					   &local->pending[queue]);
		spin_unlock_irqrestore(&local->queue_stop_reason_lock, flags);
	}
}

static void __releases(agg_queue)
ieee80211_agg_splice_finish(struct ieee80211_local *local, u16 tid)
{
	ieee80211_wake_queue_agg(local, tid);
}

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

	lockdep_assert_held(&sta->ampdu_mlme.mtx);

	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "Aggregation is on for tid %d\n", tid);
#endif

	drv_ampdu_action(local, sta->sdata,
			 IEEE80211_AMPDU_TX_OPERATIONAL,
			 &sta->sta, tid, NULL, tid_tx->buf_size);

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

	ieee80211_agg_splice_packets(local, tid_tx, tid);
	/*
	 * Now mark as operational. This will be visible
	 * in the TX path, and lets it go lock-free in
	 * the common case.
	 */
	set_bit(HT_AGG_STATE_OPERATIONAL, &tid_tx->state);
	ieee80211_agg_splice_finish(local, tid);

	spin_unlock_bh(&sta->lock);
}

void ieee80211_start_tx_ba_cb(struct ieee80211_vif *vif, u8 *ra, u16 tid)
{
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;
	struct tid_ampdu_tx *tid_tx;

	trace_api_start_tx_ba_cb(sdata, ra, tid);

	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;
	}

	mutex_lock(&local->sta_mtx);
	sta = sta_info_get_bss(sdata, ra);
	if (!sta) {
		mutex_unlock(&local->sta_mtx);
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "Could not find station: %pM\n", ra);
#endif
		return;
	}

	mutex_lock(&sta->ampdu_mlme.mtx);
	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

	if (WARN_ON(!tid_tx)) {
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "addBA was not requested!\n");
#endif
		goto unlock;
	}

	if (WARN_ON(test_and_set_bit(HT_AGG_STATE_DRV_READY, &tid_tx->state)))
		goto unlock;

	if (test_bit(HT_AGG_STATE_RESPONSE_RECEIVED, &tid_tx->state))
		ieee80211_agg_tx_operational(local, sta, tid);

 unlock:
	mutex_unlock(&sta->ampdu_mlme.mtx);
	mutex_unlock(&local->sta_mtx);
}

void ieee80211_start_tx_ba_cb_irqsafe(struct ieee80211_vif *vif,
				      const u8 *ra, u16 tid)
{
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_ra_tid *ra_tid;
	struct sk_buff *skb = dev_alloc_skb(0);

	if (unlikely(!skb))
		return;

	ra_tid = (struct ieee80211_ra_tid *) &skb->cb;
	memcpy(&ra_tid->ra, ra, ETH_ALEN);
	ra_tid->tid = tid;

	skb->pkt_type = IEEE80211_SDATA_QUEUE_AGG_START;
	skb_queue_tail(&sdata->skb_queue, skb);
	ieee80211_queue_work(&local->hw, &sdata->work);
}
EXPORT_SYMBOL(ieee80211_start_tx_ba_cb_irqsafe);

int __ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid,
				   enum ieee80211_back_parties initiator,
				   bool tx)
{
	int ret;

	mutex_lock(&sta->ampdu_mlme.mtx);

	ret = ___ieee80211_stop_tx_ba_session(sta, tid, initiator, tx);

	mutex_unlock(&sta->ampdu_mlme.mtx);

	return ret;
}

int ieee80211_stop_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid)
{
	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
	struct ieee80211_sub_if_data *sdata = sta->sdata;
	struct ieee80211_local *local = sdata->local;
	struct tid_ampdu_tx *tid_tx;
	int ret = 0;

	trace_api_stop_tx_ba_session(pubsta, tid);

	if (!local->ops->ampdu_action)
		return -EINVAL;

	if (tid >= STA_TID_NUM)
		return -EINVAL;

	spin_lock_bh(&sta->lock);
	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

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

	if (test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
		/* already in progress stopping it */
		ret = 0;
		goto unlock;
	}

	set_bit(HT_AGG_STATE_WANT_STOP, &tid_tx->state);
	ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work);

 unlock:
	spin_unlock_bh(&sta->lock);
	return ret;
}
EXPORT_SYMBOL(ieee80211_stop_tx_ba_session);

void ieee80211_stop_tx_ba_cb(struct ieee80211_vif *vif, u8 *ra, u8 tid)
{
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;
	struct tid_ampdu_tx *tid_tx;

	trace_api_stop_tx_ba_cb(sdata, ra, tid);

	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 */

	mutex_lock(&local->sta_mtx);

	sta = sta_info_get_bss(sdata, ra);
	if (!sta) {
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "Could not find station: %pM\n", ra);
#endif
		goto unlock;
	}

	mutex_lock(&sta->ampdu_mlme.mtx);
	spin_lock_bh(&sta->lock);
	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);

	if (!tid_tx || !test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "unexpected callback to A-MPDU stop\n");
#endif
		goto unlock_sta;
	}

	if (tid_tx->stop_initiator == WLAN_BACK_INITIATOR && tid_tx->tx_stop)
		ieee80211_send_delba(sta->sdata, ra, tid,
			WLAN_BACK_INITIATOR, WLAN_REASON_QSTA_NOT_USE);

	/*
	 * When we get here, the TX path will not be lockless any more wrt.
	 * aggregation, since the OPERATIONAL bit has long been cleared.
	 * Thus it will block on getting the lock, if it occurs. So if we
	 * stop the queue now, we will not get any more packets, and any
	 * that might be being processed will wait for us here, thereby
	 * guaranteeing that no packets go to the tid_tx pending queue any
	 * more.
	 */

	ieee80211_agg_splice_packets(local, tid_tx, tid);

	/* future packets must not find the tid_tx struct any more */
	ieee80211_assign_tid_tx(sta, tid, NULL);

	ieee80211_agg_splice_finish(local, tid);

	kfree_rcu(tid_tx, rcu_head);

 unlock_sta:
	spin_unlock_bh(&sta->lock);
	mutex_unlock(&sta->ampdu_mlme.mtx);
 unlock:
	mutex_unlock(&local->sta_mtx);
}

void ieee80211_stop_tx_ba_cb_irqsafe(struct ieee80211_vif *vif,
				     const u8 *ra, u16 tid)
{
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_ra_tid *ra_tid;
	struct sk_buff *skb = dev_alloc_skb(0);

	if (unlikely(!skb))
		return;

	ra_tid = (struct ieee80211_ra_tid *) &skb->cb;
	memcpy(&ra_tid->ra, ra, ETH_ALEN);
	ra_tid->tid = tid;

	skb->pkt_type = IEEE80211_SDATA_QUEUE_AGG_STOP;
	skb_queue_tail(&sdata->skb_queue, skb);
	ieee80211_queue_work(&local->hw, &sdata->work);
}
EXPORT_SYMBOL(ieee80211_stop_tx_ba_cb_irqsafe);


void ieee80211_process_addba_resp(struct ieee80211_local *local,
				  struct sta_info *sta,
				  struct ieee80211_mgmt *mgmt,
				  size_t len)
{
	struct tid_ampdu_tx *tid_tx;
	u16 capab, tid;
	u8 buf_size;

	capab = le16_to_cpu(mgmt->u.action.u.addba_resp.capab);
	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;

	mutex_lock(&sta->ampdu_mlme.mtx);

	tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
	if (!tid_tx)
		goto out;

	if (mgmt->u.action.u.addba_resp.dialog_token != tid_tx->dialog_token) {
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG "wrong addBA response token, tid %d\n", tid);
#endif
		goto out;
	}

	del_timer_sync(&tid_tx->addba_resp_timer);

#ifdef CONFIG_MAC80211_HT_DEBUG
	printk(KERN_DEBUG "switched off addBA timer for tid %d\n", tid);
#endif

	/*
	 * addba_resp_timer may have fired before we got here, and
	 * caused WANT_STOP to be set. If the stop then was already
	 * processed further, STOPPING might be set.
	 */
	if (test_bit(HT_AGG_STATE_WANT_STOP, &tid_tx->state) ||
	    test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) {
#ifdef CONFIG_MAC80211_HT_DEBUG
		printk(KERN_DEBUG
		       "got addBA resp for tid %d but we already gave up\n",
		       tid);
#endif
		goto out;
	}

	/*
	 * IEEE 802.11-2007 7.3.1.14:
	 * In an ADDBA Response frame, when the Status Code field
	 * is set to 0, the Buffer Size subfield is set to a value
	 * of at least 1.
	 */
	if (le16_to_cpu(mgmt->u.action.u.addba_resp.status)
			== WLAN_STATUS_SUCCESS && buf_size) {
		if (test_and_set_bit(HT_AGG_STATE_RESPONSE_RECEIVED,
				     &tid_tx->state)) {
			/* ignore duplicate response */
			goto out;
		}

		tid_tx->buf_size = buf_size;

		if (test_bit(HT_AGG_STATE_DRV_READY, &tid_tx->state))
			ieee80211_agg_tx_operational(local, sta, tid);

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

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

	} else {
		___ieee80211_stop_tx_ba_session(sta, tid, WLAN_BACK_INITIATOR,
						true);
	}

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