xref: /openbmc/linux/net/mac80211/sta_info.c (revision 6ef307bc561911c8cdda98ef3896b5982b602a43)
1 /*
2  * Copyright 2002-2005, Instant802 Networks, Inc.
3  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  */
9 
10 #include <linux/module.h>
11 #include <linux/init.h>
12 #include <linux/netdevice.h>
13 #include <linux/types.h>
14 #include <linux/slab.h>
15 #include <linux/skbuff.h>
16 #include <linux/if_arp.h>
17 #include <linux/timer.h>
18 #include <linux/rtnetlink.h>
19 
20 #include <net/mac80211.h>
21 #include "ieee80211_i.h"
22 #include "rate.h"
23 #include "sta_info.h"
24 #include "debugfs_sta.h"
25 #include "mesh.h"
26 
27 /**
28  * DOC: STA information lifetime rules
29  *
30  * STA info structures (&struct sta_info) are managed in a hash table
31  * for faster lookup and a list for iteration. They are managed using
32  * RCU, i.e. access to the list and hash table is protected by RCU.
33  *
34  * Upon allocating a STA info structure with sta_info_alloc(), the caller owns
35  * that structure. It must then either destroy it using sta_info_destroy()
36  * (which is pretty useless) or insert it into the hash table using
37  * sta_info_insert() which demotes the reference from ownership to a regular
38  * RCU-protected reference; if the function is called without protection by an
39  * RCU critical section the reference is instantly invalidated. Note that the
40  * caller may not do much with the STA info before inserting it, in particular,
41  * it may not start any mesh peer link management or add encryption keys.
42  *
43  * When the insertion fails (sta_info_insert()) returns non-zero), the
44  * structure will have been freed by sta_info_insert()!
45  *
46  * Because there are debugfs entries for each station, and adding those
47  * must be able to sleep, it is also possible to "pin" a station entry,
48  * that means it can be removed from the hash table but not be freed.
49  * See the comment in __sta_info_unlink() for more information, this is
50  * an internal capability only.
51  *
52  * In order to remove a STA info structure, the caller needs to first
53  * unlink it (sta_info_unlink()) from the list and hash tables and
54  * then destroy it; sta_info_destroy() will wait for an RCU grace period
55  * to elapse before actually freeing it. Due to the pinning and the
56  * possibility of multiple callers trying to remove the same STA info at
57  * the same time, sta_info_unlink() can clear the STA info pointer it is
58  * passed to indicate that the STA info is owned by somebody else now.
59  *
60  * If sta_info_unlink() did not clear the pointer then the caller owns
61  * the STA info structure now and is responsible of destroying it with
62  * a call to sta_info_destroy().
63  *
64  * In all other cases, there is no concept of ownership on a STA entry,
65  * each structure is owned by the global hash table/list until it is
66  * removed. All users of the structure need to be RCU protected so that
67  * the structure won't be freed before they are done using it.
68  */
69 
70 /* Caller must hold local->sta_lock */
71 static int sta_info_hash_del(struct ieee80211_local *local,
72 			     struct sta_info *sta)
73 {
74 	struct sta_info *s;
75 
76 	s = local->sta_hash[STA_HASH(sta->addr)];
77 	if (!s)
78 		return -ENOENT;
79 	if (s == sta) {
80 		rcu_assign_pointer(local->sta_hash[STA_HASH(sta->addr)],
81 				   s->hnext);
82 		return 0;
83 	}
84 
85 	while (s->hnext && s->hnext != sta)
86 		s = s->hnext;
87 	if (s->hnext) {
88 		rcu_assign_pointer(s->hnext, sta->hnext);
89 		return 0;
90 	}
91 
92 	return -ENOENT;
93 }
94 
95 /* protected by RCU */
96 static struct sta_info *__sta_info_find(struct ieee80211_local *local,
97 					u8 *addr)
98 {
99 	struct sta_info *sta;
100 
101 	sta = rcu_dereference(local->sta_hash[STA_HASH(addr)]);
102 	while (sta) {
103 		if (compare_ether_addr(sta->addr, addr) == 0)
104 			break;
105 		sta = rcu_dereference(sta->hnext);
106 	}
107 	return sta;
108 }
109 
110 struct sta_info *sta_info_get(struct ieee80211_local *local, u8 *addr)
111 {
112 	return __sta_info_find(local, addr);
113 }
114 EXPORT_SYMBOL(sta_info_get);
115 
116 struct sta_info *sta_info_get_by_idx(struct ieee80211_local *local, int idx,
117 				     struct net_device *dev)
118 {
119 	struct sta_info *sta;
120 	int i = 0;
121 
122 	list_for_each_entry_rcu(sta, &local->sta_list, list) {
123 		if (dev && dev != sta->sdata->dev)
124 			continue;
125 		if (i < idx) {
126 			++i;
127 			continue;
128 		}
129 		return sta;
130 	}
131 
132 	return NULL;
133 }
134 
135 /**
136  * __sta_info_free - internal STA free helper
137  *
138  * @local: pointer to the global information
139  * @sta: STA info to free
140  *
141  * This function must undo everything done by sta_info_alloc()
142  * that may happen before sta_info_insert().
143  */
144 static void __sta_info_free(struct ieee80211_local *local,
145 			    struct sta_info *sta)
146 {
147 	DECLARE_MAC_BUF(mbuf);
148 
149 	rate_control_free_sta(sta->rate_ctrl, sta->rate_ctrl_priv);
150 	rate_control_put(sta->rate_ctrl);
151 
152 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
153 	printk(KERN_DEBUG "%s: Destroyed STA %s\n",
154 	       wiphy_name(local->hw.wiphy), print_mac(mbuf, sta->addr));
155 #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
156 
157 	kfree(sta);
158 }
159 
160 void sta_info_destroy(struct sta_info *sta)
161 {
162 	struct ieee80211_local *local;
163 	struct sk_buff *skb;
164 	int i;
165 
166 	might_sleep();
167 
168 	if (!sta)
169 		return;
170 
171 	local = sta->local;
172 
173 	rate_control_remove_sta_debugfs(sta);
174 	ieee80211_sta_debugfs_remove(sta);
175 
176 #ifdef CONFIG_MAC80211_MESH
177 	if (ieee80211_vif_is_mesh(&sta->sdata->vif))
178 		mesh_plink_deactivate(sta);
179 #endif
180 
181 	/*
182 	 * We have only unlinked the key, and actually destroying it
183 	 * may mean it is removed from hardware which requires that
184 	 * the key->sta pointer is still valid, so flush the key todo
185 	 * list here.
186 	 *
187 	 * ieee80211_key_todo() will synchronize_rcu() so after this
188 	 * nothing can reference this sta struct any more.
189 	 */
190 	ieee80211_key_todo();
191 
192 #ifdef CONFIG_MAC80211_MESH
193 	if (ieee80211_vif_is_mesh(&sta->sdata->vif))
194 		del_timer_sync(&sta->plink_timer);
195 #endif
196 
197 	while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
198 		local->total_ps_buffered--;
199 		dev_kfree_skb_any(skb);
200 	}
201 
202 	while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL)
203 		dev_kfree_skb_any(skb);
204 
205 	for (i = 0; i <  STA_TID_NUM; i++) {
206 		spin_lock_bh(&sta->lock);
207 		if (sta->ampdu_mlme.tid_rx[i])
208 		  del_timer_sync(&sta->ampdu_mlme.tid_rx[i]->session_timer);
209 		if (sta->ampdu_mlme.tid_tx[i])
210 		  del_timer_sync(&sta->ampdu_mlme.tid_tx[i]->addba_resp_timer);
211 		spin_unlock_bh(&sta->lock);
212 	}
213 
214 	__sta_info_free(local, sta);
215 }
216 
217 
218 /* Caller must hold local->sta_lock */
219 static void sta_info_hash_add(struct ieee80211_local *local,
220 			      struct sta_info *sta)
221 {
222 	sta->hnext = local->sta_hash[STA_HASH(sta->addr)];
223 	rcu_assign_pointer(local->sta_hash[STA_HASH(sta->addr)], sta);
224 }
225 
226 struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
227 				u8 *addr, gfp_t gfp)
228 {
229 	struct ieee80211_local *local = sdata->local;
230 	struct sta_info *sta;
231 	int i;
232 	DECLARE_MAC_BUF(mbuf);
233 
234 	sta = kzalloc(sizeof(*sta), gfp);
235 	if (!sta)
236 		return NULL;
237 
238 	spin_lock_init(&sta->lock);
239 	spin_lock_init(&sta->flaglock);
240 
241 	memcpy(sta->addr, addr, ETH_ALEN);
242 	sta->local = local;
243 	sta->sdata = sdata;
244 
245 	sta->rate_ctrl = rate_control_get(local->rate_ctrl);
246 	sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl,
247 						     gfp);
248 	if (!sta->rate_ctrl_priv) {
249 		rate_control_put(sta->rate_ctrl);
250 		kfree(sta);
251 		return NULL;
252 	}
253 
254 	for (i = 0; i < STA_TID_NUM; i++) {
255 		/* timer_to_tid must be initialized with identity mapping to
256 		 * enable session_timer's data differentiation. refer to
257 		 * sta_rx_agg_session_timer_expired for useage */
258 		sta->timer_to_tid[i] = i;
259 		/* tid to tx queue: initialize according to HW (0 is valid) */
260 		sta->tid_to_tx_q[i] = ieee80211_num_queues(&local->hw);
261 		/* rx */
262 		sta->ampdu_mlme.tid_state_rx[i] = HT_AGG_STATE_IDLE;
263 		sta->ampdu_mlme.tid_rx[i] = NULL;
264 		/* tx */
265 		sta->ampdu_mlme.tid_state_tx[i] = HT_AGG_STATE_IDLE;
266 		sta->ampdu_mlme.tid_tx[i] = NULL;
267 		sta->ampdu_mlme.addba_req_num[i] = 0;
268 	}
269 	skb_queue_head_init(&sta->ps_tx_buf);
270 	skb_queue_head_init(&sta->tx_filtered);
271 
272 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
273 	printk(KERN_DEBUG "%s: Allocated STA %s\n",
274 	       wiphy_name(local->hw.wiphy), print_mac(mbuf, sta->addr));
275 #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
276 
277 #ifdef CONFIG_MAC80211_MESH
278 	sta->plink_state = PLINK_LISTEN;
279 	init_timer(&sta->plink_timer);
280 #endif
281 
282 	return sta;
283 }
284 
285 int sta_info_insert(struct sta_info *sta)
286 {
287 	struct ieee80211_local *local = sta->local;
288 	struct ieee80211_sub_if_data *sdata = sta->sdata;
289 	unsigned long flags;
290 	int err = 0;
291 	DECLARE_MAC_BUF(mac);
292 
293 	/*
294 	 * Can't be a WARN_ON because it can be triggered through a race:
295 	 * something inserts a STA (on one CPU) without holding the RTNL
296 	 * and another CPU turns off the net device.
297 	 */
298 	if (unlikely(!netif_running(sdata->dev))) {
299 		err = -ENETDOWN;
300 		goto out_free;
301 	}
302 
303 	if (WARN_ON(compare_ether_addr(sta->addr, sdata->dev->dev_addr) == 0 ||
304 	            is_multicast_ether_addr(sta->addr))) {
305 		err = -EINVAL;
306 		goto out_free;
307 	}
308 
309 	spin_lock_irqsave(&local->sta_lock, flags);
310 	/* check if STA exists already */
311 	if (__sta_info_find(local, sta->addr)) {
312 		spin_unlock_irqrestore(&local->sta_lock, flags);
313 		err = -EEXIST;
314 		goto out_free;
315 	}
316 	list_add(&sta->list, &local->sta_list);
317 	local->num_sta++;
318 	sta_info_hash_add(local, sta);
319 
320 	/* notify driver */
321 	if (local->ops->sta_notify) {
322 		if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN)
323 			sdata = sdata->u.vlan.ap;
324 
325 		local->ops->sta_notify(local_to_hw(local), &sdata->vif,
326 				       STA_NOTIFY_ADD, sta->addr);
327 	}
328 
329 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
330 	printk(KERN_DEBUG "%s: Inserted STA %s\n",
331 	       wiphy_name(local->hw.wiphy), print_mac(mac, sta->addr));
332 #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
333 
334 	spin_unlock_irqrestore(&local->sta_lock, flags);
335 
336 #ifdef CONFIG_MAC80211_DEBUGFS
337 	/*
338 	 * Debugfs entry adding might sleep, so schedule process
339 	 * context task for adding entry for STAs that do not yet
340 	 * have one.
341 	 * NOTE: due to auto-freeing semantics this may only be done
342 	 *       if the insertion is successful!
343 	 */
344 	schedule_work(&local->sta_debugfs_add);
345 #endif
346 
347 	if (ieee80211_vif_is_mesh(&sdata->vif))
348 		mesh_accept_plinks_update(sdata);
349 
350 	return 0;
351  out_free:
352 	BUG_ON(!err);
353 	__sta_info_free(local, sta);
354 	return err;
355 }
356 
357 static inline void __bss_tim_set(struct ieee80211_if_ap *bss, u16 aid)
358 {
359 	/*
360 	 * This format has been mandated by the IEEE specifications,
361 	 * so this line may not be changed to use the __set_bit() format.
362 	 */
363 	bss->tim[aid / 8] |= (1 << (aid % 8));
364 }
365 
366 static inline void __bss_tim_clear(struct ieee80211_if_ap *bss, u16 aid)
367 {
368 	/*
369 	 * This format has been mandated by the IEEE specifications,
370 	 * so this line may not be changed to use the __clear_bit() format.
371 	 */
372 	bss->tim[aid / 8] &= ~(1 << (aid % 8));
373 }
374 
375 static void __sta_info_set_tim_bit(struct ieee80211_if_ap *bss,
376 				   struct sta_info *sta)
377 {
378 	if (bss)
379 		__bss_tim_set(bss, sta->aid);
380 	if (sta->local->ops->set_tim) {
381 		sta->local->tim_in_locked_section = true;
382 		sta->local->ops->set_tim(local_to_hw(sta->local), sta->aid, 1);
383 		sta->local->tim_in_locked_section = false;
384 	}
385 }
386 
387 void sta_info_set_tim_bit(struct sta_info *sta)
388 {
389 	unsigned long flags;
390 
391 	spin_lock_irqsave(&sta->local->sta_lock, flags);
392 	__sta_info_set_tim_bit(sta->sdata->bss, sta);
393 	spin_unlock_irqrestore(&sta->local->sta_lock, flags);
394 }
395 
396 static void __sta_info_clear_tim_bit(struct ieee80211_if_ap *bss,
397 				     struct sta_info *sta)
398 {
399 	if (bss)
400 		__bss_tim_clear(bss, sta->aid);
401 	if (sta->local->ops->set_tim) {
402 		sta->local->tim_in_locked_section = true;
403 		sta->local->ops->set_tim(local_to_hw(sta->local), sta->aid, 0);
404 		sta->local->tim_in_locked_section = false;
405 	}
406 }
407 
408 void sta_info_clear_tim_bit(struct sta_info *sta)
409 {
410 	unsigned long flags;
411 
412 	spin_lock_irqsave(&sta->local->sta_lock, flags);
413 	__sta_info_clear_tim_bit(sta->sdata->bss, sta);
414 	spin_unlock_irqrestore(&sta->local->sta_lock, flags);
415 }
416 
417 void __sta_info_unlink(struct sta_info **sta)
418 {
419 	struct ieee80211_local *local = (*sta)->local;
420 	struct ieee80211_sub_if_data *sdata = (*sta)->sdata;
421 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
422 	DECLARE_MAC_BUF(mbuf);
423 #endif
424 	/*
425 	 * pull caller's reference if we're already gone.
426 	 */
427 	if (sta_info_hash_del(local, *sta)) {
428 		*sta = NULL;
429 		return;
430 	}
431 
432 	if ((*sta)->key) {
433 		ieee80211_key_free((*sta)->key);
434 		WARN_ON((*sta)->key);
435 	}
436 
437 	list_del(&(*sta)->list);
438 
439 	if (test_and_clear_sta_flags(*sta, WLAN_STA_PS)) {
440 		if (sdata->bss)
441 			atomic_dec(&sdata->bss->num_sta_ps);
442 		__sta_info_clear_tim_bit(sdata->bss, *sta);
443 	}
444 
445 	local->num_sta--;
446 
447 	if (local->ops->sta_notify) {
448 		if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN)
449 			sdata = sdata->u.vlan.ap;
450 
451 		local->ops->sta_notify(local_to_hw(local), &sdata->vif,
452 				       STA_NOTIFY_REMOVE, (*sta)->addr);
453 	}
454 
455 	if (ieee80211_vif_is_mesh(&sdata->vif)) {
456 		mesh_accept_plinks_update(sdata);
457 #ifdef CONFIG_MAC80211_MESH
458 		del_timer(&(*sta)->plink_timer);
459 #endif
460 	}
461 
462 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
463 	printk(KERN_DEBUG "%s: Removed STA %s\n",
464 	       wiphy_name(local->hw.wiphy), print_mac(mbuf, (*sta)->addr));
465 #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
466 
467 	/*
468 	 * Finally, pull caller's reference if the STA is pinned by the
469 	 * task that is adding the debugfs entries. In that case, we
470 	 * leave the STA "to be freed".
471 	 *
472 	 * The rules are not trivial, but not too complex either:
473 	 *  (1) pin_status is only modified under the sta_lock
474 	 *  (2) STAs may only be pinned under the RTNL so that
475 	 *	sta_info_flush() is guaranteed to actually destroy
476 	 *	all STAs that are active for a given interface, this
477 	 *	is required for correctness because otherwise we
478 	 *	could notify a driver that an interface is going
479 	 *	away and only after that (!) notify it about a STA
480 	 *	on that interface going away.
481 	 *  (3) sta_info_debugfs_add_work() will set the status
482 	 *	to PINNED when it found an item that needs a new
483 	 *	debugfs directory created. In that case, that item
484 	 *	must not be freed although all *RCU* users are done
485 	 *	with it. Hence, we tell the caller of _unlink()
486 	 *	that the item is already gone (as can happen when
487 	 *	two tasks try to unlink/destroy at the same time)
488 	 *  (4) We set the pin_status to DESTROY here when we
489 	 *	find such an item.
490 	 *  (5) sta_info_debugfs_add_work() will reset the pin_status
491 	 *	from PINNED to NORMAL when it is done with the item,
492 	 *	but will check for DESTROY before resetting it in
493 	 *	which case it will free the item.
494 	 */
495 	if ((*sta)->pin_status == STA_INFO_PIN_STAT_PINNED) {
496 		(*sta)->pin_status = STA_INFO_PIN_STAT_DESTROY;
497 		*sta = NULL;
498 		return;
499 	}
500 }
501 
502 void sta_info_unlink(struct sta_info **sta)
503 {
504 	struct ieee80211_local *local = (*sta)->local;
505 	unsigned long flags;
506 
507 	spin_lock_irqsave(&local->sta_lock, flags);
508 	__sta_info_unlink(sta);
509 	spin_unlock_irqrestore(&local->sta_lock, flags);
510 }
511 
512 static inline int sta_info_buffer_expired(struct ieee80211_local *local,
513 					  struct sta_info *sta,
514 					  struct sk_buff *skb)
515 {
516 	struct ieee80211_tx_info *info;
517 	int timeout;
518 
519 	if (!skb)
520 		return 0;
521 
522 	info = IEEE80211_SKB_CB(skb);
523 
524 	/* Timeout: (2 * listen_interval * beacon_int * 1024 / 1000000) sec */
525 	timeout = (sta->listen_interval * local->hw.conf.beacon_int * 32 /
526 		   15625) * HZ;
527 	if (timeout < STA_TX_BUFFER_EXPIRE)
528 		timeout = STA_TX_BUFFER_EXPIRE;
529 	return time_after(jiffies, info->control.jiffies + timeout);
530 }
531 
532 
533 static void sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
534 					     struct sta_info *sta)
535 {
536 	unsigned long flags;
537 	struct sk_buff *skb;
538 	struct ieee80211_sub_if_data *sdata;
539 	DECLARE_MAC_BUF(mac);
540 
541 	if (skb_queue_empty(&sta->ps_tx_buf))
542 		return;
543 
544 	for (;;) {
545 		spin_lock_irqsave(&sta->ps_tx_buf.lock, flags);
546 		skb = skb_peek(&sta->ps_tx_buf);
547 		if (sta_info_buffer_expired(local, sta, skb))
548 			skb = __skb_dequeue(&sta->ps_tx_buf);
549 		else
550 			skb = NULL;
551 		spin_unlock_irqrestore(&sta->ps_tx_buf.lock, flags);
552 
553 		if (!skb)
554 			break;
555 
556 		sdata = sta->sdata;
557 		local->total_ps_buffered--;
558 #ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
559 		printk(KERN_DEBUG "Buffered frame expired (STA "
560 		       "%s)\n", print_mac(mac, sta->addr));
561 #endif
562 		dev_kfree_skb(skb);
563 
564 		if (skb_queue_empty(&sta->ps_tx_buf))
565 			sta_info_clear_tim_bit(sta);
566 	}
567 }
568 
569 
570 static void sta_info_cleanup(unsigned long data)
571 {
572 	struct ieee80211_local *local = (struct ieee80211_local *) data;
573 	struct sta_info *sta;
574 
575 	rcu_read_lock();
576 	list_for_each_entry_rcu(sta, &local->sta_list, list)
577 		sta_info_cleanup_expire_buffered(local, sta);
578 	rcu_read_unlock();
579 
580 	local->sta_cleanup.expires =
581 		round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
582 	add_timer(&local->sta_cleanup);
583 }
584 
585 #ifdef CONFIG_MAC80211_DEBUGFS
586 /*
587  * See comment in __sta_info_unlink,
588  * caller must hold local->sta_lock.
589  */
590 static void __sta_info_pin(struct sta_info *sta)
591 {
592 	WARN_ON(sta->pin_status != STA_INFO_PIN_STAT_NORMAL);
593 	sta->pin_status = STA_INFO_PIN_STAT_PINNED;
594 }
595 
596 /*
597  * See comment in __sta_info_unlink, returns sta if it
598  * needs to be destroyed.
599  */
600 static struct sta_info *__sta_info_unpin(struct sta_info *sta)
601 {
602 	struct sta_info *ret = NULL;
603 	unsigned long flags;
604 
605 	spin_lock_irqsave(&sta->local->sta_lock, flags);
606 	WARN_ON(sta->pin_status != STA_INFO_PIN_STAT_DESTROY &&
607 		sta->pin_status != STA_INFO_PIN_STAT_PINNED);
608 	if (sta->pin_status == STA_INFO_PIN_STAT_DESTROY)
609 		ret = sta;
610 	sta->pin_status = STA_INFO_PIN_STAT_NORMAL;
611 	spin_unlock_irqrestore(&sta->local->sta_lock, flags);
612 
613 	return ret;
614 }
615 
616 static void sta_info_debugfs_add_work(struct work_struct *work)
617 {
618 	struct ieee80211_local *local =
619 		container_of(work, struct ieee80211_local, sta_debugfs_add);
620 	struct sta_info *sta, *tmp;
621 	unsigned long flags;
622 
623 	/* We need to keep the RTNL across the whole pinned status. */
624 	rtnl_lock();
625 	while (1) {
626 		sta = NULL;
627 
628 		spin_lock_irqsave(&local->sta_lock, flags);
629 		list_for_each_entry(tmp, &local->sta_list, list) {
630 			if (!tmp->debugfs.dir) {
631 				sta = tmp;
632 				__sta_info_pin(sta);
633 				break;
634 			}
635 		}
636 		spin_unlock_irqrestore(&local->sta_lock, flags);
637 
638 		if (!sta)
639 			break;
640 
641 		ieee80211_sta_debugfs_add(sta);
642 		rate_control_add_sta_debugfs(sta);
643 
644 		sta = __sta_info_unpin(sta);
645 		sta_info_destroy(sta);
646 	}
647 	rtnl_unlock();
648 }
649 #endif
650 
651 static void __ieee80211_run_pending_flush(struct ieee80211_local *local)
652 {
653 	struct sta_info *sta;
654 	unsigned long flags;
655 
656 	ASSERT_RTNL();
657 
658 	spin_lock_irqsave(&local->sta_lock, flags);
659 	while (!list_empty(&local->sta_flush_list)) {
660 		sta = list_first_entry(&local->sta_flush_list,
661 				       struct sta_info, list);
662 		list_del(&sta->list);
663 		spin_unlock_irqrestore(&local->sta_lock, flags);
664 		sta_info_destroy(sta);
665 		spin_lock_irqsave(&local->sta_lock, flags);
666 	}
667 	spin_unlock_irqrestore(&local->sta_lock, flags);
668 }
669 
670 static void ieee80211_sta_flush_work(struct work_struct *work)
671 {
672 	struct ieee80211_local *local =
673 		container_of(work, struct ieee80211_local, sta_flush_work);
674 
675 	rtnl_lock();
676 	__ieee80211_run_pending_flush(local);
677 	rtnl_unlock();
678 }
679 
680 void sta_info_init(struct ieee80211_local *local)
681 {
682 	spin_lock_init(&local->sta_lock);
683 	INIT_LIST_HEAD(&local->sta_list);
684 	INIT_LIST_HEAD(&local->sta_flush_list);
685 	INIT_WORK(&local->sta_flush_work, ieee80211_sta_flush_work);
686 
687 	setup_timer(&local->sta_cleanup, sta_info_cleanup,
688 		    (unsigned long)local);
689 	local->sta_cleanup.expires =
690 		round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
691 
692 #ifdef CONFIG_MAC80211_DEBUGFS
693 	INIT_WORK(&local->sta_debugfs_add, sta_info_debugfs_add_work);
694 #endif
695 }
696 
697 int sta_info_start(struct ieee80211_local *local)
698 {
699 	add_timer(&local->sta_cleanup);
700 	return 0;
701 }
702 
703 void sta_info_stop(struct ieee80211_local *local)
704 {
705 	del_timer(&local->sta_cleanup);
706 	cancel_work_sync(&local->sta_flush_work);
707 #ifdef CONFIG_MAC80211_DEBUGFS
708 	/*
709 	 * Make sure the debugfs adding work isn't pending after this
710 	 * because we're about to be destroyed. It doesn't matter
711 	 * whether it ran or not since we're going to flush all STAs
712 	 * anyway.
713 	 */
714 	cancel_work_sync(&local->sta_debugfs_add);
715 #endif
716 
717 	rtnl_lock();
718 	sta_info_flush(local, NULL);
719 	__ieee80211_run_pending_flush(local);
720 	rtnl_unlock();
721 }
722 
723 /**
724  * sta_info_flush - flush matching STA entries from the STA table
725  *
726  * Returns the number of removed STA entries.
727  *
728  * @local: local interface data
729  * @sdata: matching rule for the net device (sta->dev) or %NULL to match all STAs
730  */
731 int sta_info_flush(struct ieee80211_local *local,
732 		    struct ieee80211_sub_if_data *sdata)
733 {
734 	struct sta_info *sta, *tmp;
735 	LIST_HEAD(tmp_list);
736 	int ret = 0;
737 	unsigned long flags;
738 
739 	might_sleep();
740 	ASSERT_RTNL();
741 
742 	spin_lock_irqsave(&local->sta_lock, flags);
743 	list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
744 		if (!sdata || sdata == sta->sdata) {
745 			__sta_info_unlink(&sta);
746 			if (sta) {
747 				list_add_tail(&sta->list, &tmp_list);
748 				ret++;
749 			}
750 		}
751 	}
752 	spin_unlock_irqrestore(&local->sta_lock, flags);
753 
754 	list_for_each_entry_safe(sta, tmp, &tmp_list, list)
755 		sta_info_destroy(sta);
756 
757 	return ret;
758 }
759 
760 /**
761  * sta_info_flush_delayed - flush matching STA entries from the STA table
762  *
763  * This function unlinks all stations for a given interface and queues
764  * them for freeing. Note that the workqueue function scheduled here has
765  * to run before any new keys can be added to the system to avoid set_key()
766  * callback ordering issues.
767  *
768  * @sdata: the interface
769  */
770 void sta_info_flush_delayed(struct ieee80211_sub_if_data *sdata)
771 {
772 	struct ieee80211_local *local = sdata->local;
773 	struct sta_info *sta, *tmp;
774 	unsigned long flags;
775 	bool work = false;
776 
777 	spin_lock_irqsave(&local->sta_lock, flags);
778 	list_for_each_entry_safe(sta, tmp, &local->sta_list, list) {
779 		if (sdata == sta->sdata) {
780 			__sta_info_unlink(&sta);
781 			if (sta) {
782 				list_add_tail(&sta->list,
783 					      &local->sta_flush_list);
784 				work = true;
785 			}
786 		}
787 	}
788 	if (work)
789 		schedule_work(&local->sta_flush_work);
790 	spin_unlock_irqrestore(&local->sta_lock, flags);
791 }
792