1 files changed, 363 insertions, 368 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index f735826f055c..211c475f73c6 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -32,49 +32,33 @@
  * 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.
+ * Upon allocating a STA info structure with sta_info_alloc(), the caller
+ * owns that structure. It must then insert it into the hash table using
+ * either sta_info_insert() or sta_info_insert_rcu(); only in the latter
+ * case (which acquires an rcu read section but must not be called from
+ * within one) will the pointer still be valid after the call. 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
+ * Station 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.
+ * get to know about a peer on the same IBSS. 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, various sta_info_destroy_*()
+ * calls are available.
  *
- * 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.
+ * 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 */
@@ -185,101 +169,6 @@ static void __sta_info_free(struct ieee80211_local *local,
 	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;
-
-	cancel_work_sync(&sta->drv_unblock_wk);
-
-	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)
@@ -376,7 +265,7 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
 	return sta;
 }
 
-int sta_info_insert(struct sta_info *sta)
+static int sta_info_finish_insert(struct sta_info *sta, bool async)
 {
 	struct ieee80211_local *local = sta->local;
 	struct ieee80211_sub_if_data *sdata = sta->sdata;
@@ -384,6 +273,91 @@ int sta_info_insert(struct sta_info *sta)
 	unsigned long flags;
 	int err = 0;
 
+	WARN_ON(!mutex_is_locked(&local->sta_mtx));
+
+	/* notify driver */
+	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
+		sdata = container_of(sdata->bss,
+				     struct ieee80211_sub_if_data,
+				     u.ap);
+	err = drv_sta_add(local, sdata, &sta->sta);
+	if (err) {
+		if (!async)
+			return err;
+		printk(KERN_DEBUG "%s: failed to add IBSS STA %pM to driver (%d)"
+				  " - keeping it anyway.\n",
+		       sdata->name, sta->sta.addr, err);
+	} else {
+		sta->uploaded = true;
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+		if (async)
+			printk(KERN_DEBUG "%s: Finished adding IBSS STA %pM\n",
+			       wiphy_name(local->hw.wiphy), sta->sta.addr);
+#endif
+	}
+
+	sdata = sta->sdata;
+
+	if (!async) {
+		local->num_sta++;
+		local->sta_generation++;
+		smp_mb();
+
+		/* make the station visible */
+		spin_lock_irqsave(&local->sta_lock, flags);
+		sta_info_hash_add(local, sta);
+		spin_unlock_irqrestore(&local->sta_lock, flags);
+	}
+
+	list_add(&sta->list, &local->sta_list);
+
+	ieee80211_sta_debugfs_add(sta);
+	rate_control_add_sta_debugfs(sta);
+
+	sinfo.filled = 0;
+	sinfo.generation = local->sta_generation;
+	cfg80211_new_sta(sdata->dev, sta->sta.addr, &sinfo, GFP_KERNEL);
+
+
+	return 0;
+}
+
+static void sta_info_finish_pending(struct ieee80211_local *local)
+{
+	struct sta_info *sta;
+	unsigned long flags;
+
+	spin_lock_irqsave(&local->sta_lock, flags);
+	while (!list_empty(&local->sta_pending_list)) {
+		sta = list_first_entry(&local->sta_pending_list,
+				       struct sta_info, list);
+		list_del(&sta->list);
+		spin_unlock_irqrestore(&local->sta_lock, flags);
+
+		sta_info_finish_insert(sta, true);
+
+		spin_lock_irqsave(&local->sta_lock, flags);
+	}
+	spin_unlock_irqrestore(&local->sta_lock, flags);
+}
+
+static void sta_info_finish_work(struct work_struct *work)
+{
+	struct ieee80211_local *local =
+		container_of(work, struct ieee80211_local, sta_finish_work);
+
+	mutex_lock(&local->sta_mtx);
+	sta_info_finish_pending(local);
+	mutex_unlock(&local->sta_mtx);
+}
+
+int sta_info_insert_rcu(struct sta_info *sta) __acquires(RCU)
+{
+	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
@@ -391,36 +365,87 @@ int sta_info_insert(struct sta_info *sta)
 	 */
 	if (unlikely(!ieee80211_sdata_running(sdata))) {
 		err = -ENETDOWN;
+		rcu_read_lock();
 		goto out_free;
 	}
 
 	if (WARN_ON(compare_ether_addr(sta->sta.addr, sdata->vif.addr) == 0 ||
 		    is_multicast_ether_addr(sta->sta.addr))) {
 		err = -EINVAL;
+		rcu_read_lock();
 		goto out_free;
 	}
 
+	/*
+	 * In ad-hoc mode, we sometimes need to insert stations
+	 * from tasklet context from the RX path. To avoid races,
+	 * always do so in that case -- see the comment below.
+	 */
+	if (sdata->vif.type == NL80211_IFTYPE_ADHOC) {
+		spin_lock_irqsave(&local->sta_lock, flags);
+		/* check if STA exists already */
+		if (sta_info_get_bss(sdata, sta->sta.addr)) {
+			spin_unlock_irqrestore(&local->sta_lock, flags);
+			rcu_read_lock();
+			err = -EEXIST;
+			goto out_free;
+		}
+
+		local->num_sta++;
+		local->sta_generation++;
+		smp_mb();
+		sta_info_hash_add(local, sta);
+
+		list_add_tail(&sta->list, &local->sta_pending_list);
+
+		rcu_read_lock();
+		spin_unlock_irqrestore(&local->sta_lock, flags);
+
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+		printk(KERN_DEBUG "%s: Added IBSS STA %pM\n",
+		       wiphy_name(local->hw.wiphy), sta->sta.addr);
+#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
+
+		ieee80211_queue_work(&local->hw, &local->sta_finish_work);
+
+		return 0;
+	}
+
+	/*
+	 * On first glance, this will look racy, because the code
+	 * below this point, which inserts a station with sleeping,
+	 * unlocks the sta_lock between checking existence in the
+	 * hash table and inserting into it.
+	 *
+	 * However, it is not racy against itself because it keeps
+	 * the mutex locked. It still seems to race against the
+	 * above code that atomically inserts the station... That,
+	 * however, is not true because the above code can only
+	 * be invoked for IBSS interfaces, and the below code will
+	 * not be -- and the two do not race against each other as
+	 * the hash table also keys off the interface.
+	 */
+
+	might_sleep();
+
+	mutex_lock(&local->sta_mtx);
+
 	spin_lock_irqsave(&local->sta_lock, flags);
 	/* check if STA exists already */
-	if (sta_info_get(sdata, sta->sta.addr)) {
+	if (sta_info_get_bss(sdata, sta->sta.addr)) {
 		spin_unlock_irqrestore(&local->sta_lock, flags);
+		rcu_read_lock();
 		err = -EEXIST;
 		goto out_free;
 	}
-	list_add(&sta->list, &local->sta_list);
-	local->sta_generation++;
-	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);
+	spin_unlock_irqrestore(&local->sta_lock, flags);
 
-		drv_sta_notify(local, sdata, STA_NOTIFY_ADD, &sta->sta);
-		sdata = sta->sdata;
+	err = sta_info_finish_insert(sta, false);
+	if (err) {
+		mutex_unlock(&local->sta_mtx);
+		rcu_read_lock();
+		goto out_free;
 	}
 
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
@@ -428,22 +453,9 @@ int sta_info_insert(struct sta_info *sta)
 	       wiphy_name(local->hw.wiphy), sta->sta.addr);
 #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
 
-	spin_unlock_irqrestore(&local->sta_lock, flags);
-
-	sinfo.filled = 0;
-	sinfo.generation = local->sta_generation;
-	cfg80211_new_sta(sdata->dev, sta->sta.addr, &sinfo, GFP_ATOMIC);
-
-#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
+	/* move reference to rcu-protected */
+	rcu_read_lock();
+	mutex_unlock(&local->sta_mtx);
 
 	if (ieee80211_vif_is_mesh(&sdata->vif))
 		mesh_accept_plinks_update(sdata);
@@ -455,6 +467,15 @@ int sta_info_insert(struct sta_info *sta)
 	return err;
 }
 
+int sta_info_insert(struct sta_info *sta)
+{
+	int err = sta_info_insert_rcu(sta);
+
+	rcu_read_unlock();
+
+	return err;
+}
+
 static inline void __bss_tim_set(struct ieee80211_if_ap *bss, u16 aid)
 {
 	/*
@@ -523,108 +544,6 @@ void sta_info_clear_tim_bit(struct sta_info *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);
-	(*sta)->dead = true;
-
-	if (test_and_clear_sta_flags(*sta,
-				WLAN_STA_PS_STA | WLAN_STA_PS_DRIVER)) {
-		BUG_ON(!sdata->bss);
-
-		atomic_dec(&sdata->bss->num_sta_ps);
-		__sta_info_clear_tim_bit(sdata->bss, *sta);
-	}
-
-	local->num_sta--;
-	local->sta_generation++;
-
-	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
-		rcu_assign_pointer(sdata->u.vlan.sta, NULL);
-
-	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, STA_NOTIFY_REMOVE,
-			       &(*sta)->sta);
-		sdata = (*sta)->sdata;
-	}
-
-	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)
 {
@@ -681,109 +600,209 @@ static void sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
 	}
 }
 
-
-static void sta_info_cleanup(unsigned long data)
+static int __must_check __sta_info_destroy(struct sta_info *sta)
 {
-	struct ieee80211_local *local = (struct ieee80211_local *) data;
-	struct sta_info *sta;
+	struct ieee80211_local *local;
+	struct ieee80211_sub_if_data *sdata;
+	struct sk_buff *skb;
+	unsigned long flags;
+	int ret, i;
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(sta, &local->sta_list, list)
-		sta_info_cleanup_expire_buffered(local, sta);
-	rcu_read_unlock();
+	might_sleep();
 
-	if (local->quiescing)
-		return;
+	if (!sta)
+		return -ENOENT;
 
-	local->sta_cleanup.expires =
-		round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
-	add_timer(&local->sta_cleanup);
-}
+	local = sta->local;
+	sdata = sta->sdata;
 
-#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;
+	spin_lock_irqsave(&local->sta_lock, flags);
+	ret = sta_info_hash_del(local, sta);
+	/* this might still be the pending list ... which is fine */
+	if (!ret)
+		list_del(&sta->list);
+	spin_unlock_irqrestore(&local->sta_lock, flags);
+	if (ret)
+		return ret;
+
+	if (sta->key) {
+		ieee80211_key_free(sta->key);
+		/*
+		 * 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();
+
+		WARN_ON(sta->key);
+	}
+
+	sta->dead = true;
+
+	if (test_and_clear_sta_flags(sta,
+				WLAN_STA_PS_STA | WLAN_STA_PS_DRIVER)) {
+		BUG_ON(!sdata->bss);
+
+		atomic_dec(&sdata->bss->num_sta_ps);
+		__sta_info_clear_tim_bit(sdata->bss, sta);
+	}
+
+	local->num_sta--;
+	local->sta_generation++;
+
+	if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
+		rcu_assign_pointer(sdata->u.vlan.sta, NULL);
+
+	if (sta->uploaded) {
+		if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
+			sdata = container_of(sdata->bss,
+					     struct ieee80211_sub_if_data,
+					     u.ap);
+		drv_sta_remove(local, sdata, &sta->sta);
+		sdata = sta->sdata;
+	}
+
+#ifdef CONFIG_MAC80211_MESH
+	if (ieee80211_vif_is_mesh(&sdata->vif)) {
+		mesh_accept_plinks_update(sdata);
+		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 */
+	cancel_work_sync(&sta->drv_unblock_wk);
+
+	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);
+		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);
+
+	return 0;
 }
 
-/*
- * 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)
+int sta_info_destroy_addr(struct ieee80211_sub_if_data *sdata, const u8 *addr)
 {
-	struct sta_info *ret = NULL;
-	unsigned long flags;
+	struct sta_info *sta;
+	int ret;
 
-	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);
+	mutex_lock(&sdata->local->sta_mtx);
+	sta = sta_info_get(sdata, addr);
+	ret = __sta_info_destroy(sta);
+	mutex_unlock(&sdata->local->sta_mtx);
 
 	return ret;
 }
 
-static void sta_info_debugfs_add_work(struct work_struct *work)
+int sta_info_destroy_addr_bss(struct ieee80211_sub_if_data *sdata,
+			      const u8 *addr)
 {
-	struct ieee80211_local *local =
-		container_of(work, struct ieee80211_local, sta_debugfs_add);
-	struct sta_info *sta, *tmp;
-	unsigned long flags;
+	struct sta_info *sta;
+	int ret;
 
-	/* We need to keep the RTNL across the whole pinned status. */
-	rtnl_lock();
-	while (1) {
-		sta = NULL;
+	mutex_lock(&sdata->local->sta_mtx);
+	sta = sta_info_get_bss(sdata, addr);
+	ret = __sta_info_destroy(sta);
+	mutex_unlock(&sdata->local->sta_mtx);
 
-		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);
+	return ret;
+}
 
-		if (!sta)
-			break;
+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();
 
-		ieee80211_sta_debugfs_add(sta);
-		rate_control_add_sta_debugfs(sta);
+	if (local->quiescing)
+		return;
 
-		sta = __sta_info_unpin(sta);
-		sta_info_destroy(sta);
-	}
-	rtnl_unlock();
+	local->sta_cleanup.expires =
+		round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
+	add_timer(&local->sta_cleanup);
 }
-#endif
 
 void sta_info_init(struct ieee80211_local *local)
 {
 	spin_lock_init(&local->sta_lock);
+	mutex_init(&local->sta_mtx);
 	INIT_LIST_HEAD(&local->sta_list);
+	INIT_LIST_HEAD(&local->sta_pending_list);
+	INIT_WORK(&local->sta_finish_work, sta_info_finish_work);
 
 	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)
@@ -795,16 +814,6 @@ int sta_info_start(struct ieee80211_local *local)
 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);
 }
 
@@ -820,26 +829,19 @@ 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);
+	mutex_lock(&local->sta_mtx);
+
+	sta_info_finish_pending(local);
+
 	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++;
-			}
-		}
+		if (!sdata || sdata == sta->sdata)
+			WARN_ON(__sta_info_destroy(sta));
 	}
-	spin_unlock_irqrestore(&local->sta_lock, flags);
-
-	list_for_each_entry_safe(sta, tmp, &tmp_list, list)
-		sta_info_destroy(sta);
+	mutex_unlock(&local->sta_mtx);
 
 	return ret;
 }
@@ -849,24 +851,17 @@ void ieee80211_sta_expire(struct ieee80211_sub_if_data *sdata,
 {
 	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);
+	mutex_lock(&local->sta_mtx);
 	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->name, sta->sta.addr);
 #endif
-			__sta_info_unlink(&sta);
-			if (sta)
-				list_add(&sta->list, &tmp_list);
+			WARN_ON(__sta_info_destroy(sta));
 		}
-	spin_unlock_irqrestore(&local->sta_lock, flags);
-
-	list_for_each_entry_safe(sta, tmp, &tmp_list, list)
-		sta_info_destroy(sta);
+	mutex_unlock(&local->sta_mtx);
 }
 
 struct ieee80211_sta *ieee80211_find_sta_by_hw(struct ieee80211_hw *hw,