1 files changed, 363 insertions, 368 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index f735826f055..211c475f73c 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,