1 files changed, 240 insertions, 147 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 81c4e3392f40..ee5b66abc0f1 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -15,6 +15,7 @@
 #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"
@@ -23,14 +24,43 @@
 #include "debugfs_sta.h"
 #include "mesh.h"
 
-/* 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->addr)];
-        local->sta_hash[STA_HASH(sta->addr)] = sta;
-}
-
+/**
+ * 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.
+ *
+ * STA info structures are always "alive" when they are added with
+ * @sta_info_add() [this may be changed in the future to allow allocating
+ * outside of a critical section!], they are then added to the hash
+ * table and list. Therefore, @sta_info_add() must also be RCU protected,
+ * also, the caller of @sta_info_add() cannot assume that it owns the
+ * structure.
+ *
+ * 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.
+ *
+ * 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 wait for an RCU synchronisation before it can be freed. 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(), not before RCU synchronisation, of
+ * course. Note that sta_info_destroy() must be protected by the RTNL.
+ *
+ * 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,
@@ -42,46 +72,39 @@ static int sta_info_hash_del(struct ieee80211_local *local,
         if (!s)
                 return -ENOENT;
         if (s == sta) {
-                local->sta_hash[STA_HASH(sta->addr)] = s->hnext;
+                rcu_assign_pointer(local->sta_hash[STA_HASH(sta->addr)],
+                                   s->hnext);
                 return 0;
         }
 
         while (s->hnext && s->hnext != sta)
                 s = s->hnext;
         if (s->hnext) {
-                s->hnext = sta->hnext;
+                rcu_assign_pointer(s->hnext, sta->hnext);
                 return 0;
         }
 
         return -ENOENT;
 }
 
-/* must hold local->sta_lock */
+/* protected by RCU */
 static struct sta_info *__sta_info_find(struct ieee80211_local *local,
                                         u8 *addr)
 {
         struct sta_info *sta;
 
-        sta = local->sta_hash[STA_HASH(addr)];
+        sta = rcu_dereference(local->sta_hash[STA_HASH(addr)]);
         while (sta) {
                 if (compare_ether_addr(sta->addr, addr) == 0)
                         break;
-                sta = sta->hnext;
+                sta = rcu_dereference(sta->hnext);
         }
         return sta;
 }
 
 struct sta_info *sta_info_get(struct ieee80211_local *local, u8 *addr)
 {
-        struct sta_info *sta;
-
-        read_lock_bh(&local->sta_lock);
-        sta = __sta_info_find(local, addr);
-        if (sta)
-                __sta_info_get(sta);
-        read_unlock_bh(&local->sta_lock);
-
-        return sta;
+        return __sta_info_find(local, addr);
 }
 EXPORT_SYMBOL(sta_info_get);
 
@@ -91,81 +114,101 @@ struct sta_info *sta_info_get_by_idx(struct ieee80211_local *local, int idx,
         struct sta_info *sta;
         int i = 0;
 
-        read_lock_bh(&local->sta_lock);
-        list_for_each_entry(sta, &local->sta_list, list) {
+        list_for_each_entry_rcu(sta, &local->sta_list, list) {
                 if (i < idx) {
                         ++i;
                         continue;
-                } else if (!dev || dev == sta->dev) {
-                        __sta_info_get(sta);
-                        read_unlock_bh(&local->sta_lock);
+                } else if (!dev || dev == sta->sdata->dev) {
                         return sta;
                 }
         }
-        read_unlock_bh(&local->sta_lock);
 
         return NULL;
 }
 
-static void sta_info_release(struct kref *kref)
+void sta_info_destroy(struct sta_info *sta)
 {
-        struct sta_info *sta = container_of(kref, struct sta_info, kref);
         struct ieee80211_local *local = sta->local;
         struct sk_buff *skb;
         int i;
 
-        /* free sta structure; it has already been removed from
-         * hash table etc. external structures. Make sure that all
-         * buffered frames are release (one might have been added
-         * after sta_info_free() was called). */
+        ASSERT_RTNL();
+        might_sleep();
+
+        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
+
+        /*
+         * NOTE: This will call synchronize_rcu() internally to
+         * make sure no key references can be in use. We rely on
+         * that here for the mesh code!
+         */
+        ieee80211_key_free(sta->key);
+        WARN_ON(sta->key);
+
+#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) {
+
+        while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL)
                 dev_kfree_skb_any(skb);
-        }
+
         for (i = 0; i <  STA_TID_NUM; i++) {
                 del_timer_sync(&sta->ampdu_mlme.tid_rx[i].session_timer);
                 del_timer_sync(&sta->ampdu_mlme.tid_tx[i].addba_resp_timer);
         }
         rate_control_free_sta(sta->rate_ctrl, sta->rate_ctrl_priv);
         rate_control_put(sta->rate_ctrl);
+
         kfree(sta);
 }
 
 
-void sta_info_put(struct sta_info *sta)
+/* Caller must hold local->sta_lock */
+static void sta_info_hash_add(struct ieee80211_local *local,
+                              struct sta_info *sta)
 {
-        kref_put(&sta->kref, sta_info_release);
+        sta->hnext = local->sta_hash[STA_HASH(sta->addr)];
+        rcu_assign_pointer(local->sta_hash[STA_HASH(sta->addr)], sta);
 }
-EXPORT_SYMBOL(sta_info_put);
-
 
-struct sta_info *sta_info_add(struct ieee80211_local *local,
-                              struct net_device *dev, u8 *addr, gfp_t gfp)
+struct sta_info *sta_info_add(struct ieee80211_sub_if_data *sdata,
+                              u8 *addr)
 {
+        struct ieee80211_local *local = sdata->local;
         struct sta_info *sta;
         int i;
         DECLARE_MAC_BUF(mac);
+        unsigned long flags;
 
-        sta = kzalloc(sizeof(*sta), gfp);
+        sta = kzalloc(sizeof(*sta), GFP_ATOMIC);
         if (!sta)
                 return ERR_PTR(-ENOMEM);
 
-        kref_init(&sta->kref);
+        memcpy(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, gfp);
+        sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl,
+                                                     GFP_ATOMIC);
         if (!sta->rate_ctrl_priv) {
                 rate_control_put(sta->rate_ctrl);
                 kfree(sta);
                 return ERR_PTR(-ENOMEM);
         }
 
-        memcpy(sta->addr, addr, ETH_ALEN);
-        sta->local = local;
-        sta->dev = dev;
         spin_lock_init(&sta->ampdu_mlme.ampdu_rx);
         spin_lock_init(&sta->ampdu_mlme.ampdu_tx);
         for (i = 0; i < STA_TID_NUM; i++) {
@@ -190,29 +233,26 @@ struct sta_info *sta_info_add(struct ieee80211_local *local,
         }
         skb_queue_head_init(&sta->ps_tx_buf);
         skb_queue_head_init(&sta->tx_filtered);
-        write_lock_bh(&local->sta_lock);
-        /* mark sta as used (by caller) */
-        __sta_info_get(sta);
+        spin_lock_irqsave(&local->sta_lock, flags);
         /* check if STA exists already */
         if (__sta_info_find(local, addr)) {
-                write_unlock_bh(&local->sta_lock);
-                sta_info_put(sta);
+                spin_unlock_irqrestore(&local->sta_lock, flags);
                 return ERR_PTR(-EEXIST);
         }
         list_add(&sta->list, &local->sta_list);
         local->num_sta++;
         sta_info_hash_add(local, sta);
-        if (local->ops->sta_notify) {
-                struct ieee80211_sub_if_data *sdata;
 
-                sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+        /* notify driver */
+        if (local->ops->sta_notify) {
                 if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN)
                         sdata = sdata->u.vlan.ap;
 
                 local->ops->sta_notify(local_to_hw(local), &sdata->vif,
                                        STA_NOTIFY_ADD, addr);
         }
-        write_unlock_bh(&local->sta_lock);
+
+        spin_unlock_irqrestore(&local->sta_lock, flags);
 
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
         printk(KERN_DEBUG "%s: Added STA %s\n",
@@ -252,19 +292,20 @@ static void __sta_info_set_tim_bit(struct ieee80211_if_ap *bss,
 {
         if (bss)
                 __bss_tim_set(bss, sta->aid);
-        if (sta->local->ops->set_tim)
+        if (sta->local->ops->set_tim) {
+                sta->local->tim_in_locked_section = true;
                 sta->local->ops->set_tim(local_to_hw(sta->local), sta->aid, 1);
+                sta->local->tim_in_locked_section = false;
+        }
 }
 
 void sta_info_set_tim_bit(struct sta_info *sta)
 {
-        struct ieee80211_sub_if_data *sdata;
-
-        sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+        unsigned long flags;
 
-        read_lock_bh(&sta->local->sta_lock);
-        __sta_info_set_tim_bit(sdata->bss, sta);
-        read_unlock_bh(&sta->local->sta_lock);
+        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,
@@ -272,93 +313,135 @@ static void __sta_info_clear_tim_bit(struct ieee80211_if_ap *bss,
 {
         if (bss)
                 __bss_tim_clear(bss, sta->aid);
-        if (sta->local->ops->set_tim)
+        if (sta->local->ops->set_tim) {
+                sta->local->tim_in_locked_section = true;
                 sta->local->ops->set_tim(local_to_hw(sta->local), sta->aid, 0);
+                sta->local->tim_in_locked_section = false;
+        }
 }
 
 void sta_info_clear_tim_bit(struct sta_info *sta)
 {
-        struct ieee80211_sub_if_data *sdata;
-
-        sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+        unsigned long flags;
 
-        read_lock_bh(&sta->local->sta_lock);
-        __sta_info_clear_tim_bit(sdata->bss, sta);
-        read_unlock_bh(&sta->local->sta_lock);
+        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);
 }
 
-/* Caller must hold local->sta_lock */
-void sta_info_remove(struct sta_info *sta)
+/*
+ * See comment in __sta_info_unlink,
+ * caller must hold local->sta_lock.
+ */
+static void __sta_info_pin(struct sta_info *sta)
 {
-        struct ieee80211_local *local = sta->local;
-        struct ieee80211_sub_if_data *sdata;
+        WARN_ON(sta->pin_status != STA_INFO_PIN_STAT_NORMAL);
+        sta->pin_status = STA_INFO_PIN_STAT_PINNED;
+}
 
-        /* don't do anything if we've been removed already */
-        if (sta_info_hash_del(local, sta))
-                return;
+/*
+ * 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;
 
-        list_del(&sta->list);
-        sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
-        if (sta->flags & WLAN_STA_PS) {
-                sta->flags &= ~WLAN_STA_PS;
-                if (sdata->bss)
-                        atomic_dec(&sdata->bss->num_sta_ps);
-                __sta_info_clear_tim_bit(sdata->bss, sta);
-        }
-        local->num_sta--;
+        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);
 
-        if (ieee80211_vif_is_mesh(&sdata->vif))
-                mesh_accept_plinks_update(sdata->dev);
+        return ret;
 }
 
-void sta_info_free(struct sta_info *sta)
+static void __sta_info_unlink(struct sta_info **sta)
 {
-        struct sk_buff *skb;
-        struct ieee80211_local *local = sta->local;
-        struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
-
-        DECLARE_MAC_BUF(mac);
-
-        might_sleep();
+        struct ieee80211_local *local = (*sta)->local;
+        struct ieee80211_sub_if_data *sdata = (*sta)->sdata;
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+        DECLARE_MAC_BUF(mbuf);
+#endif
+        /*
+         * pull caller's reference if we're already gone.
+         */
+        if (sta_info_hash_del(local, *sta)) {
+                *sta = NULL;
+                return;
+        }
 
-        write_lock_bh(&local->sta_lock);
-        sta_info_remove(sta);
-        write_unlock_bh(&local->sta_lock);
+        /*
+         * Also 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) 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)
+         *  (3) We set the pin_status to DESTROY here when we
+         *      find such an item.
+         *  (4) 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;
+        }
 
-        if (ieee80211_vif_is_mesh(&sdata->vif))
-                mesh_plink_deactivate(sta);
+        list_del(&(*sta)->list);
 
-        while ((skb = skb_dequeue(&sta->ps_tx_buf)) != NULL) {
-                local->total_ps_buffered--;
-                dev_kfree_skb(skb);
-        }
-        while ((skb = skb_dequeue(&sta->tx_filtered)) != NULL) {
-                dev_kfree_skb(skb);
+        if ((*sta)->flags & WLAN_STA_PS) {
+                (*sta)->flags &= ~WLAN_STA_PS;
+                if (sdata->bss)
+                        atomic_dec(&sdata->bss->num_sta_ps);
+                __sta_info_clear_tim_bit(sdata->bss, *sta);
         }
 
-#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
-        printk(KERN_DEBUG "%s: Removed STA %s\n",
-               wiphy_name(local->hw.wiphy), print_mac(mac, sta->addr));
-#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
-
-        ieee80211_key_free(sta->key);
-        WARN_ON(sta->key);
+        local->num_sta--;
 
         if (local->ops->sta_notify) {
-
                 if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN)
                         sdata = sdata->u.vlan.ap;
 
                 local->ops->sta_notify(local_to_hw(local), &sdata->vif,
-                                       STA_NOTIFY_REMOVE, sta->addr);
+                                       STA_NOTIFY_REMOVE, (*sta)->addr);
         }
 
-        rate_control_remove_sta_debugfs(sta);
-        ieee80211_sta_debugfs_remove(sta);
+        if (ieee80211_vif_is_mesh(&sdata->vif)) {
+                mesh_accept_plinks_update(sdata);
+#ifdef CONFIG_MAC80211_MESH
+                del_timer(&(*sta)->plink_timer);
+#endif
+        }
 
-        sta_info_put(sta);
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+        printk(KERN_DEBUG "%s: Removed STA %s\n",
+               wiphy_name(local->hw.wiphy), print_mac(mbuf, (*sta)->addr));
+#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
 }
 
+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 inline int sta_info_buffer_expired(struct ieee80211_local *local,
                                           struct sta_info *sta,
@@ -404,7 +487,7 @@ static void sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
                 if (!skb)
                         break;
 
-                sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+                sdata = sta->sdata;
                 local->total_ps_buffered--;
                 printk(KERN_DEBUG "Buffered frame expired (STA "
                        "%s)\n", print_mac(mac, sta->addr));
@@ -421,13 +504,10 @@ static void sta_info_cleanup(unsigned long data)
         struct ieee80211_local *local = (struct ieee80211_local *) data;
         struct sta_info *sta;
 
-        read_lock_bh(&local->sta_lock);
-        list_for_each_entry(sta, &local->sta_list, list) {
-                __sta_info_get(sta);
+        rcu_read_lock();
+        list_for_each_entry_rcu(sta, &local->sta_list, list)
                 sta_info_cleanup_expire_buffered(local, sta);
-                sta_info_put(sta);
-        }
-        read_unlock_bh(&local->sta_lock);
+        rcu_read_unlock();
 
         local->sta_cleanup.expires =
                 round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
@@ -435,37 +515,45 @@ static void sta_info_cleanup(unsigned long data)
 }
 
 #ifdef CONFIG_MAC80211_DEBUGFS
-static void sta_info_debugfs_add_task(struct work_struct *work)
+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;
 
         while (1) {
                 sta = NULL;
-                read_lock_bh(&local->sta_lock);
+
+                spin_lock_irqsave(&local->sta_lock, flags);
                 list_for_each_entry(tmp, &local->sta_list, list) {
                         if (!tmp->debugfs.dir) {
                                 sta = tmp;
-                                __sta_info_get(sta);
+                                __sta_info_pin(sta);
                                 break;
                         }
                 }
-                read_unlock_bh(&local->sta_lock);
+                spin_unlock_irqrestore(&local->sta_lock, flags);
 
                 if (!sta)
                         break;
 
                 ieee80211_sta_debugfs_add(sta);
                 rate_control_add_sta_debugfs(sta);
-                sta_info_put(sta);
+
+                sta = __sta_info_unpin(sta);
+
+                if (sta) {
+                        synchronize_rcu();
+                        sta_info_destroy(sta);
+                }
         }
 }
 #endif
 
 void sta_info_init(struct ieee80211_local *local)
 {
-        rwlock_init(&local->sta_lock);
+        spin_lock_init(&local->sta_lock);
         INIT_LIST_HEAD(&local->sta_list);
 
         setup_timer(&local->sta_cleanup, sta_info_cleanup,
@@ -474,7 +562,7 @@ void sta_info_init(struct ieee80211_local *local)
                 round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL);
 
 #ifdef CONFIG_MAC80211_DEBUGFS
-        INIT_WORK(&local->sta_debugfs_add, sta_info_debugfs_add_task);
+        INIT_WORK(&local->sta_debugfs_add, sta_info_debugfs_add_work);
 #endif
 }
 
@@ -493,24 +581,29 @@ void sta_info_stop(struct ieee80211_local *local)
 /**
  * sta_info_flush - flush matching STA entries from the STA table
  * @local: local interface data
- * @dev: matching rule for the net device (sta->dev) or %NULL to match all STAs
+ * @sdata: matching rule for the net device (sta->dev) or %NULL to match all STAs
  */
-void sta_info_flush(struct ieee80211_local *local, struct net_device *dev)
+void sta_info_flush(struct ieee80211_local *local,
+                    struct ieee80211_sub_if_data *sdata)
 {
         struct sta_info *sta, *tmp;
         LIST_HEAD(tmp_list);
+        unsigned long flags;
 
-        write_lock_bh(&local->sta_lock);
-        list_for_each_entry_safe(sta, tmp, &local->sta_list, list)
-                if (!dev || dev == sta->dev) {
-                        __sta_info_get(sta);
-                        sta_info_remove(sta);
-                        list_add_tail(&sta->list, &tmp_list);
-                }
-        write_unlock_bh(&local->sta_lock);
+        might_sleep();
 
-        list_for_each_entry_safe(sta, tmp, &tmp_list, list) {
-                sta_info_free(sta);
-                sta_info_put(sta);
+        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);
+                }
         }
+        spin_unlock_irqrestore(&local->sta_lock, flags);
+
+        synchronize_rcu();
+
+        list_for_each_entry_safe(sta, tmp, &tmp_list, list)
+                sta_info_destroy(sta);
 }