summaryrefslogtreecommitdiffstats
path: root/net/mac80211/sta_info.c
blob: a360bceeba59461d8d83e20220a60aba06fe693d (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
/*
 * Copyright 2002-2005, Instant802 Networks, Inc.
 * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
 *
 * 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/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/timer.h>
#include <linux/rtnetlink.h>

#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "driver-ops.h"
#include "rate.h"
#include "sta_info.h"
#include "debugfs_sta.h"
#include "mesh.h"

/**
 * DOC: STA information lifetime rules
 *
 * STA info structures (&struct sta_info) are managed in a hash table
 * for faster lookup and a list for iteration. They are managed using
 * RCU, i.e. access to the list and hash table is protected by RCU.
 *
 * Upon allocating a STA info structure with sta_info_alloc(), the caller owns
 * that structure. It must then either destroy it using sta_info_destroy()
 * (which is pretty useless) or insert it into the hash table using
 * sta_info_insert() which demotes the reference from ownership to a regular
 * RCU-protected reference; if the function is called without protection by an
 * RCU critical section the reference is instantly invalidated. Note that the
 * caller may not do much with the STA info before inserting it, in particular,
 * it may not start any mesh peer link management or add encryption keys.
 *
 * When the insertion fails (sta_info_insert()) returns non-zero), the
 * structure will have been freed by sta_info_insert()!
 *
 * sta entries are added by mac80211 when you establish a link with a
 * peer. This means different things for the different type of interfaces
 * we support. For a regular station this mean we add the AP sta when we
 * receive an assocation response from the AP. For IBSS this occurs when
 * we receive a probe response or a beacon from target IBSS network. For
 * WDS we add the sta for the peer imediately upon device open. When using
 * AP mode we add stations for each respective station upon request from
 * userspace through nl80211.
 *
 * Because there are debugfs entries for each station, and adding those
 * must be able to sleep, it is also possible to "pin" a station entry,
 * that means it can be removed from the hash table but not be freed.
 * See the comment in __sta_info_unlink() for more information, this is
 * an internal capability only.
 *
 * In order to remove a STA info structure, the caller needs to first
 * unlink it (sta_info_unlink()) from the list and hash tables and
 * then destroy it; sta_info_destroy() will wait for an RCU grace period
 * to elapse before actually freeing it. Due to the pinning and the
 * possibility of multiple callers trying to remove the same STA info at
 * the same time, sta_info_unlink() can clear the STA info pointer it is
 * passed to indicate that the STA info is owned by somebody else now.
 *
 * If sta_info_unlink() did not clear the pointer then the caller owns
 * the STA info structure now and is responsible of destroying it with
 * a call to sta_info_destroy().
 *
 * In all other cases, there is no concept of ownership on a STA entry,
 * each structure is owned by the global hash table/list until it is
 * removed. All users of the structure need to be RCU protected so that
 * the structure won't be freed before they are done using it.
 */

/* Caller must hold local->sta_lock */
static int sta_info_hash_del(struct ieee80211_local *local,
			     struct sta_info *sta)
{
	struct sta_info *s;

	s = local->sta_hash[STA_HASH(sta->sta.addr)];
	if (!s)
		return -ENOENT;
	if (s == sta) {
		rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)],
				   s->hnext);
		return 0;
	}

	while (s->hnext && s->hnext != sta)
		s = s->hnext;
	if (s->hnext) {
		rcu_assign_pointer(s->hnext, sta->hnext);
		return 0;
	}

	return -ENOENT;
}

/* protected by RCU */
struct sta_info *sta_info_get(struct ieee80211_local *local, const u8 *addr)
{
	struct sta_info *sta;

	sta = rcu_dereference(local->sta_hash[STA_HASH(addr)]);
	while (sta) {
		if (memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
			break;
		sta = rcu_dereference(sta->hnext);
	}
	return sta;
}

struct sta_info *sta_info_get_by_idx(struct ieee80211_local *local, int idx,
				     struct net_device *dev)
{
	struct sta_info *sta;
	int i = 0;

	list_for_each_entry_rcu(sta, &local->sta_list, list) {
		if (dev && dev != sta->sdata->dev)
			continue;
		if (i < idx) {
			++i;
			continue;
		}
		return sta;
	}

	return NULL;
}

/**
 * __sta_info_free - internal STA free helper
 *
 * @local: pointer to the global information
 * @sta: STA info to free
 *
 * This function must undo everything done by sta_info_alloc()
 * that may happen before sta_info_insert().
 */
static void __sta_info_free(struct ieee80211_local *local,
			    struct sta_info *sta)
{
	rate_control_free_sta(sta);
	rate_control_put(sta->rate_ctrl);

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
	printk(KERN_DEBUG "%s: Destroyed STA %pM\n",
	       wiphy_name(local->hw.wiphy), sta->sta.addr);
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */

	kfree(sta);
}

void sta_info_destroy(struct sta_info *sta)
{
	struct ieee80211_local *local;
	struct sk_buff *skb;
	int i;

	might_sleep();

	if (!sta)
		return;

	local = sta->local;

	rate_control_remove_sta_debugfs(sta);
	ieee80211_sta_debugfs_remove(sta);

#ifdef CONFIG_MAC80211_MESH
	if (ieee80211_vif_is_mesh(&sta->sdata->vif))
		mesh_plink_deactivate(sta);
#endif

	/*
	 * We have only unlinked the key, and actually destroying it
	 * may mean it is removed from hardware which requires that
	 * the key->sta pointer is still valid, so flush the key todo
	 * list here.
	 *
	 * ieee80211_key_todo() will synchronize_rcu() so after this
	 * nothing can reference this sta struct any more.
	 */
	ieee80211_key_todo();

#ifdef CONFIG_MAC80211_MESH
	if (ieee80211_vif_is_mesh(&sta->sdata->vif))
		del_timer_sync(&sta->plink_timer);
#endif

	while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
		local->total_ps_buffered--;
		dev_kfree_skb_any(skb);
	}

	while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL)
		dev_kfree_skb_any(skb);

	for (i = 0; i <  STA_TID_NUM; i++) {
		struct tid_ampdu_rx *tid_rx;
		struct tid_ampdu_tx *tid_tx;

		spin_lock_bh(&sta->lock);
		tid_rx = sta->ampdu_mlme.tid_rx[i];
		/* Make sure timer won't free the tid_rx struct, see below */
		if (tid_rx)
			tid_rx->shutdown = true;

		spin_unlock_bh(&sta->lock);

		/*
		 * Outside spinlock - shutdown is true now so that the timer
		 * won't free tid_rx, we have to do that now. Can't let the
		 * timer do it because we have to sync the timer outside the
		 * lock that it takes itself.
		 */
		if (tid_rx) {
			del_timer_sync(&tid_rx->session_timer);
			kfree(tid_rx);
		}

		/*
		 * No need to do such complications for TX agg sessions, the
		 * path leading to freeing the tid_tx struct goes via a call
		 * from the driver, and thus needs to look up the sta struct
		 * again, which cannot be found when we get here. Hence, we
		 * just need to delete the timer and free the aggregation
		 * info; we won't be telling the peer about it then but that
		 * doesn't matter if we're not talking to it again anyway.
		 */
		tid_tx = sta->ampdu_mlme.tid_tx[i];
		if (tid_tx) {
			del_timer_sync(&tid_tx->addba_resp_timer);
			/*
			 * STA removed while aggregation session being
			 * started? Bit odd, but purge frames anyway.
			 */
			skb_queue_purge(&tid_tx->pending);
			kfree(tid_tx);
		}
	}

	__sta_info_free(local, sta);
}


/* Caller must hold local->sta_lock */
static void sta_info_hash_add(struct ieee80211_local *local,
			      struct sta_info *sta)
{
	sta->hnext = local->sta_hash[STA_HASH(sta->sta.addr)];
	rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)], sta);
}

struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
				u8 *addr, gfp_t gfp)
{
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta;
	int i;

	sta = kzalloc(sizeof(*sta) + local->hw.sta_data_size, gfp);
	if (!sta)
		return NULL;

	spin_lock_init(&sta->lock);
	spin_lock_init(&sta->flaglock);

	memcpy(sta->sta.addr, addr, ETH_ALEN);
	sta->local = local;
	sta->sdata = sdata;

	sta->rate_ctrl = rate_control_get(local->rate_ctrl);
	sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl,
						     &sta->sta, gfp);
	if (!sta->rate_ctrl_priv) {
		rate_control_put(sta->rate_ctrl);
		kfree(sta);
		return NULL;
	}

	for (i = 0; i < STA_TID_NUM; i++) {
		/* timer_to_tid must be initialized with identity mapping to
		 * enable session_timer's data differentiation. refer to
		 * sta_rx_agg_session_timer_expired for useage */
		sta->timer_to_tid[i] = i;
		/* rx */
		sta->ampdu_mlme.tid_state_rx[i] = HT_AGG_STATE_IDLE;
		sta->ampdu_mlme.tid_rx[i] = NULL;
		/* tx */
		sta->ampdu_mlme.tid_state_tx[i] = HT_AGG_STATE_IDLE;
		sta->ampdu_mlme.tid_tx[i] = NULL;
		sta->ampdu_mlme.addba_req_num[i] = 0;
	}
	skb_queue_head_init(&sta->ps_tx_buf);
	skb_queue_head_init(&sta->tx_filtered);

	for (i = 0; i < NUM_RX_DATA_QUEUES; i++)
		sta->last_seq_ctrl[i] = cpu_to_le16(USHORT_MAX);

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
	printk(KERN_DEBUG "%s: Allocated STA %pM\n",
	       wiphy_name(local->hw.wiphy), sta->sta.addr);
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */

#ifdef CONFIG_MAC80211_MESH
	sta->plink_state = PLINK_LISTEN;
	init_timer(&sta->plink_timer);
#endif

	return sta;
}

int sta_info_insert(struct sta_info *sta)
{
	struct ieee80211_local *local = sta->local;
	struct ieee80211_sub_if_data *sdata = sta->sdata;
	unsigned long flags;
	int err = 0;

	/*
	 * Can't be a WARN_ON because it can be triggered through a race:
	 * something inserts a STA (on one CPU) without holding the RTNL
	 * and another CPU turns off the net device.
	 */
	if (unlikely(!netif_running(sdata->dev))) {
		err = -ENETDOWN;
		goto out_free;
	}

	if (WARN_ON(compare_ether_addr(sta->sta.addr, sdata->dev->dev_addr) == 0 ||
		    is_multicast_ether_addr(sta->sta.addr))) {
		err = -EINVAL;
		goto out_free;
	}

	spin_lock_irqsave(&local->sta_lock, flags);
	/* check if STA exists already */
	if (sta_info_get(local, sta->sta.addr)) {
		spin_unlock_irqrestore(&local->sta_lock, flags);
		err = -EEXIST;
		goto out_free;
	}
	list_add(&sta->list, &local->sta_list);
	local->num_sta++;
	sta_info_hash_add(local, sta);

	/* notify driver */
	if (local->ops->sta_notify) {
		if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
			sdata = container_of(sdata->bss,
					     struct ieee80211_sub_if_data,
					     u.ap);

		drv_sta_notify(local, &sdata->vif, STA_NOTIFY_ADD, &sta->sta);
	}

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
	printk(KERN_DEBUG "%s: Inserted STA %pM\n",
	       wiphy_name(local->hw.wiphy), sta->sta.addr);
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */

	spin_unlock_irqrestore(&local->sta_lock, flags);

#ifdef CONFIG_MAC80211_DEBUGFS
	/*
	 * Debugfs entry adding might sleep, so schedule process
	 * context task for adding entry for STAs that do not yet
	 * have one.
	 * NOTE: due to auto-freeing semantics this may only be done
	 *       if the insertion is successful!
	 */
	schedule_work(&local->sta_debugfs_add);
#endif

	if (ieee80211_vif_is_mesh(&sdata->vif))
		mesh_accept_plinks_update(sdata);

	return 0;
 out_free:
	BUG_ON(!err);
	__sta_info_free(local, sta);
	return err;
}

static inline void __bss_tim_set(struct ieee80211_if_ap *bss, u16 aid)
{
	/*
	 * This format has been mandated by the IEEE specifications,
	 * so this line may not be changed to use the __set_bit() format.
	 */
	bss->tim[aid / 8] |= (1 << (aid % 8));
}

static inline void __bss_tim_clear(struct ieee80211_if_ap *bss, u16 aid)
{
	/*
	 * This format has been mandated by the IEEE specifications,
	 * so this line may not be changed to use the __clear_bit() format.
	 */
	bss->tim[aid / 8] &= ~(1 << (aid % 8));
}

static void __sta_info_set_tim_bit(struct ieee80211_if_ap *bss,
				   struct sta_info *sta)
{
	BUG_ON(!bss);

	__bss_tim_set(bss, sta->sta.aid);

	if (sta->local->ops->set_tim) {
		sta->local->tim_in_locked_section = true;
		drv_set_tim(sta->local, &sta->sta, true);
		sta->local->tim_in_locked_section = false;
	}
}

void sta_info_set_tim_bit(struct sta_info *sta)
{
	unsigned long flags;

	BUG_ON(!sta->sdata->bss);

	spin_lock_irqsave(&sta->local->sta_lock, flags);
	__sta_info_set_tim_bit(sta->sdata->bss, sta);
	spin_unlock_irqrestore(&sta->local->sta_lock, flags);
}

static void __sta_info_clear_tim_bit(struct ieee80211_if_ap *bss,
				     struct sta_info *sta)
{
	BUG_ON(!bss);

	__bss_tim_clear(bss, sta->sta.aid);

	if (sta->local->ops->set_tim) {
		sta->local->tim_in_locked_section = true;
		drv_set_tim(sta->local, &sta->sta, false);
		sta->local->tim_in_locked_section = false;
	}
}

void sta_info_clear_tim_bit(struct sta_info *sta)
{
	unsigned long flags;

	BUG_ON(!sta->sdata->bss);

	spin_lock_irqsave(&sta->local->sta_lock, flags);
	__sta_info_clear_tim_bit(sta->sdata->bss, sta);
	spin_unlock_irqrestore(&sta->local->sta_lock, flags);
}

static void __sta_info_unlink(struct sta_info **sta)
{
	struct ieee80211_local *local = (*sta)->local;
	struct ieee80211_sub_if_data *sdata = (*sta)->sdata;
	/*
	 * pull caller's reference if we're already gone.
	 */
	if (sta_info_hash_del(local, *sta)) {
		*sta = NULL;
		return;
	}

	if ((*sta)->key) {
		ieee80211_key_free((*sta)->key);
		WARN_ON((*sta)->key);
	}

	list_del(&(*sta)->list);

	if (test_and_clear_sta_flags(*sta, WLAN_STA_PS)) {
		BUG_ON(!sdata->bss);

		atomic_dec(&sdata->bss->num_sta_ps);
		__sta_info_clear_tim_bit(sdata->bss, *sta);
	}

	local->num_sta--;

	if (local->ops->sta_notify) {
		if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
			sdata = container_of(sdata->bss,
					     struct ieee80211_sub_if_data,
					     u.ap);

		drv_sta_notify(local, &sdata->vif, STA_NOTIFY_REMOVE,
			       &(*sta)->sta);
	}

	if (ieee80211_vif_is_mesh(&sdata->vif)) {
		mesh_accept_plinks_update(sdata);
#ifdef CONFIG_MAC80211_MESH
		del_timer(&(*sta)->plink_timer);
#endif
	}

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
	printk(KERN_DEBUG "%s: Removed STA %pM\n",
	       wiphy_name(local->hw.wiphy), (*sta)->sta.addr);
#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */

	/*
	 * Finally, pull caller's reference if the STA is pinned by the
	 * task that is adding the debugfs entries. In that case, we
	 * leave the STA "to be freed".
	 *
	 * The rules are not trivial, but not too complex either:
	 *  (1) pin_status is only modified under the sta_lock
	 *  (2) STAs may only be pinned under the RTNL so that
	 *	sta_info_flush() is guaranteed to actually destroy
	 *	all STAs that are active for a given interface, this
	 *	is required for correctness because otherwise we
	 *	could notify a driver that an interface is going
	 *	away and only after that (!) notify it about a STA
	 *	on that interface going away.
	 *  (3) sta_info_debugfs_add_work() will set the status
	 *	to PINNED when it found an item that needs a new
	 *	debugfs directory created. In that case, that item
	 *	must not be freed although all *RCU* users are done
	 *	with it. Hence, we tell the caller of _unlink()
	 *	that the item is already gone (as can happen when
	 *	two tasks try to unlink/destroy at the same time)
	 *  (4) We set the pin_status to DESTROY here when we
	 *	find such an item.
	 *  (5) sta_info_debugfs_add_work() will reset the pin_status
	 *	from PINNED to NORMAL when it is done with the item,
	 *	but will check for DESTROY before resetting it in
	 *	which case it will free the item.
	 */
	if ((*sta)->pin_status == STA_INFO_PIN_STAT_PINNED) {
		(*sta)->pin_status = STA_INFO_PIN_STAT_DESTROY;
		*sta = NULL;
		return;
	}
}

void sta_info_unlink(struct sta_info **sta)
{
	struct ieee80211_local *local = (*sta)->local;
	unsigned long flags;

	spin_lock_irqsave(&local->sta_lock, flags);
	__sta_info_unlink(sta);
	spin_unlock_irqrestore(&local->sta_lock, flags);
}

static int sta_info_buffer_expired(struct sta_info *sta,
				   struct sk_buff *skb)
{
	struct ieee80211_tx_info *info;
	int timeout;

	if (!skb)
		return 0;

	info = IEEE80211_SKB_CB(skb);

	/* Timeout: (2 * listen_interval * beacon_int * 1024 / 1000000) sec */
	timeout = (sta->listen_interval *
		   sta->sdata->vif.bss_conf.beacon_int *
		   32 / 15625) * HZ;
	if (timeout < STA_TX_BUFFER_EXPIRE)
		timeout = STA_TX_BUFFER_EXPIRE;
	return time_after(jiffies, info->control.jiffies + timeout);
}


static void sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
					     struct sta_info *sta)
{
	unsigned long flags;
	struct sk_buff *skb;
	struct ieee80211_sub_if_data *sdata;

	if (skb_queue_empty(&sta->ps_tx_buf))
		return;

	for (;;) {
		spin_lock_irqsave(&sta->ps_tx_buf.lock, flags);
		skb = skb_peek(&sta->ps_tx_buf);
		if (sta_info_buffer_expired(sta, skb))
			skb = __skb_dequeue(&sta->ps_tx_buf);
		else
			skb = NULL;
		spin_unlock_irqrestore(&sta->ps_tx_buf.lock, flags);

		if (!skb)
			break;

		sdata = sta->sdata;
		local->total_ps_buffered--;
#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
		printk(KERN_DEBUG "Buffered frame expired (STA %pM)\n",
		       sta->sta.addr);
#endif
		dev_kfree_skb(skb);

		if (skb_queue_empty(&sta->ps_tx_buf))
			sta_info_clear_tim_bit(sta);
	}
}


static void sta_info_cleanup(unsigned long data)
{
	struct ieee80211_local *local = (struct ieee80211_local *) data;
	struct sta_info *sta;

	rcu_read_lock();
	list_for_each_entry_rcu(sta, &local->sta_list, list)
		sta_info_cleanup_expire_buffered(local, sta);
	rcu_read_unlock();

	if (local->quiescing)
		return;

	local->sta_cleanup.expires =
		round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
	add_timer(&local->sta_cleanup);
}

#ifdef CONFIG_MAC80211_DEBUGFS
/*
 * See comment in __sta_info_unlink,
 * caller must hold local->sta_lock.
 */
static void __sta_info_pin(struct sta_info *sta)
{
	WARN_ON(sta->pin_status != STA_INFO_PIN_STAT_NORMAL);
	sta->pin_status = STA_INFO_PIN_STAT_PINNED;
}

/*
 * See comment in __sta_info_unlink, returns sta if it
 * needs to be destroyed.
 */
static struct sta_info *__sta_info_unpin(struct sta_info *sta)
{
	struct sta_info *ret = NULL;
	unsigned long flags;

	spin_lock_irqsave(&sta->local->sta_lock, flags);
	WARN_ON(sta->pin_status != STA_INFO_PIN_STAT_DESTROY &&
		sta->pin_status != STA_INFO_PIN_STAT_PINNED);
	if (sta->pin_status == STA_INFO_PIN_STAT_DESTROY)
		ret = sta;
	sta->pin_status = STA_INFO_PIN_STAT_NORMAL;
	spin_unlock_irqrestore(&sta->local->sta_lock, flags);

	return ret;
}

static void sta_info_debugfs_add_work(struct work_struct *work)
{
	struct ieee80211_local *local =
		container_of(work, struct ieee80211_local, sta_debugfs_add);
	struct sta_info *sta, *tmp;
	unsigned long flags;

	/* We need to keep the RTNL across the whole pinned status. */
	rtnl_lock();
	while (1) {
		sta = NULL;

		spin_lock_irqsave(&local->sta_lock, flags);
		list_for_each_entry(tmp, &local->sta_list, list) {
			/*
			 * debugfs.add_has_run will be set by
			 * ieee80211_sta_debugfs_add regardless
			 * of what else it does.
			 */
			if (!tmp->debugfs.add_has_run) {
				sta = tmp;
				__sta_info_pin(sta);
				break;
			}
		}
		spin_unlock_irqrestore(&local->sta_lock, flags);

		if (!sta)
			break;

		ieee80211_sta_debugfs_add(sta);
		rate_control_add_sta_debugfs(sta);

		sta = __sta_info_unpin(sta);
		sta_info_destroy(sta);
	}
	rtnl_unlock();
}
#endif

void sta_info_init(struct ieee80211_local *local)
{
	spin_lock_init(&local->sta_lock);
	INIT_LIST_HEAD(&local->sta_list);

	setup_timer(&local->sta_cleanup, sta_info_cleanup,
		    (unsigned long)local);
	local->sta_cleanup.expires =
		round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);

#ifdef CONFIG_MAC80211_DEBUGFS
	INIT_WORK(&local->sta_debugfs_add, sta_info_debugfs_add_work);
#endif
}

int sta_info_start(struct ieee80211_local *local)
{
	add_timer(&local->sta_cleanup);
	return 0;
}

void sta_info_stop(struct ieee80211_local *local)
{
	del_timer(&local->sta_cleanup);
#ifdef CONFIG_MAC80211_DEBUGFS
	/*
	 * Make sure the debugfs adding work isn't pending after this
	 * because we're about to be destroyed. It doesn't matter
	 * whether it ran or not since we're going to flush all STAs
	 * anyway.
	 */
	cancel_work_sync(&local->sta_debugfs_add);
#endif

	sta_info_flush(local, NULL);
}

/**
 * sta_info_flush - flush matching STA entries from the STA table
 *
 * Returns the number of removed STA entries.
 *
 * @local: local interface data
 * @sdata: matching rule for the net device (sta->dev) or %NULL to match all STAs
 */
int sta_info_flush(struct ieee80211_local *local,
		   struct ieee80211_sub_if_data *sdata)
{
	struct sta_info *sta, *tmp;
	LIST_HEAD(tmp_list);
	int ret = 0;
	unsigned long flags;

	might_sleep();

	spin_lock_irqsave(&local->sta_lock, flags);
	list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
		if (!sdata || sdata == sta->sdata) {
			__sta_info_unlink(&sta);
			if (sta) {
				list_add_tail(&sta->list, &tmp_list);
				ret++;
			}
		}
	}
	spin_unlock_irqrestore(&local->sta_lock, flags);

	list_for_each_entry_safe(sta, tmp, &tmp_list, list)
		sta_info_destroy(sta);

	return ret;
}

void ieee80211_sta_expire(struct ieee80211_sub_if_data *sdata,
			  unsigned long exp_time)
{
	struct ieee80211_local *local = sdata->local;
	struct sta_info *sta, *tmp;
	LIST_HEAD(tmp_list);
	unsigned long flags;

	spin_lock_irqsave(&local->sta_lock, flags);
	list_for_each_entry_safe(sta, tmp, &local->sta_list, list)
		if (time_after(jiffies, sta->last_rx + exp_time)) {
#ifdef CONFIG_MAC80211_IBSS_DEBUG
			printk(KERN_DEBUG "%s: expiring inactive STA %pM\n",
			       sdata->dev->name, sta->sta.addr);
#endif
			__sta_info_unlink(&sta);
			if (sta)
				list_add(&sta->list, &tmp_list);
		}
	spin_unlock_irqrestore(&local->sta_lock, flags);

	list_for_each_entry_safe(sta, tmp, &tmp_list, list)
		sta_info_destroy(sta);
}

struct ieee80211_sta *ieee80211_find_sta(struct ieee80211_hw *hw,
					 const u8 *addr)
{
	struct sta_info *sta = sta_info_get(hw_to_local(hw), addr);

	if (!sta)
		return NULL;
	return &sta->sta;
}
EXPORT_SYMBOL(ieee80211_find_sta);