1 files changed, 1005 insertions, 0 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
new file mode 100644
index 00000000..3ff633e8
--- /dev/null
+++ b/net/mac80211/sta_info.c
@@ -0,0 +1,1005 @@
+/*
+ * Copyright 2002-2005, Instant802 Networks, Inc.
+ * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/netdevice.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/skbuff.h>
+#include <linux/if_arp.h>
+#include <linux/timer.h>
+#include <linux/rtnetlink.h>
+
+#include <net/mac80211.h>
+#include "ieee80211_i.h"
+#include "driver-ops.h"
+#include "rate.h"
+#include "sta_info.h"
+#include "debugfs_sta.h"
+#include "mesh.h"
+
+/**
+ * DOC: STA information lifetime rules
+ *
+ * STA info structures (&struct sta_info) are managed in a hash table
+ * for faster lookup and a list for iteration. They are managed using
+ * RCU, i.e. access to the list and hash table is protected by RCU.
+ *
+ * Upon allocating a STA info structure with sta_info_alloc(), the caller
+ * owns that structure. It must then 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()!
+ *
+ * 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 association response from the AP. For IBSS this occurs when
+ * get to know about a peer on the same IBSS. For WDS we add the sta for
+ * the peer immediately upon device open. When using AP mode we add stations
+ * for each respective station upon request from userspace through nl80211.
+ *
+ * In order to remove a STA info structure, various sta_info_destroy_*()
+ * calls are available.
+ *
+ * There is no concept of ownership on a STA entry, each structure is
+ * owned by the global hash table/list until it is removed. All users of
+ * the structure need to be RCU protected so that the structure won't be
+ * freed before they are done using it.
+ */
+
+/* Caller must hold local->sta_lock */
+static int sta_info_hash_del(struct ieee80211_local *local,
+			     struct sta_info *sta)
+{
+	struct sta_info *s;
+
+	s = rcu_dereference_protected(local->sta_hash[STA_HASH(sta->sta.addr)],
+				      lockdep_is_held(&local->sta_lock));
+	if (!s)
+		return -ENOENT;
+	if (s == sta) {
+		rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)],
+				   s->hnext);
+		return 0;
+	}
+
+	while (rcu_access_pointer(s->hnext) &&
+	       rcu_access_pointer(s->hnext) != sta)
+		s = rcu_dereference_protected(s->hnext,
+					lockdep_is_held(&local->sta_lock));
+	if (rcu_access_pointer(s->hnext)) {
+		rcu_assign_pointer(s->hnext, sta->hnext);
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+/* protected by RCU */
+struct sta_info *sta_info_get(struct ieee80211_sub_if_data *sdata,
+			      const u8 *addr)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
+
+	sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
+				    rcu_read_lock_held() ||
+				    lockdep_is_held(&local->sta_lock) ||
+				    lockdep_is_held(&local->sta_mtx));
+	while (sta) {
+		if (sta->sdata == sdata &&
+		    memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
+			break;
+		sta = rcu_dereference_check(sta->hnext,
+					    rcu_read_lock_held() ||
+					    lockdep_is_held(&local->sta_lock) ||
+					    lockdep_is_held(&local->sta_mtx));
+	}
+	return sta;
+}
+
+/*
+ * Get sta info either from the specified interface
+ * or from one of its vlans
+ */
+struct sta_info *sta_info_get_bss(struct ieee80211_sub_if_data *sdata,
+				  const u8 *addr)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
+
+	sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)],
+				    rcu_read_lock_held() ||
+				    lockdep_is_held(&local->sta_lock) ||
+				    lockdep_is_held(&local->sta_mtx));
+	while (sta) {
+		if ((sta->sdata == sdata ||
+		     (sta->sdata->bss && sta->sdata->bss == sdata->bss)) &&
+		    memcmp(sta->sta.addr, addr, ETH_ALEN) == 0)
+			break;
+		sta = rcu_dereference_check(sta->hnext,
+					    rcu_read_lock_held() ||
+					    lockdep_is_held(&local->sta_lock) ||
+					    lockdep_is_held(&local->sta_mtx));
+	}
+	return sta;
+}
+
+struct sta_info *sta_info_get_by_idx(struct ieee80211_sub_if_data *sdata,
+				     int idx)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
+	int i = 0;
+
+	list_for_each_entry_rcu(sta, &local->sta_list, list) {
+		if (sdata != sta->sdata)
+			continue;
+		if (i < idx) {
+			++i;
+			continue;
+		}
+		return sta;
+	}
+
+	return NULL;
+}
+
+/**
+ * __sta_info_free - internal STA free helper
+ *
+ * @local: pointer to the global information
+ * @sta: STA info to free
+ *
+ * This function must undo everything done by sta_info_alloc()
+ * that may happen before sta_info_insert().
+ */
+static void __sta_info_free(struct ieee80211_local *local,
+			    struct sta_info *sta)
+{
+	if (sta->rate_ctrl) {
+		rate_control_free_sta(sta);
+		rate_control_put(sta->rate_ctrl);
+	}
+
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+	wiphy_debug(local->hw.wiphy, "Destroyed STA %pM\n", sta->sta.addr);
+#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
+
+	kfree(sta);
+}
+
+/* Caller must hold local->sta_lock */
+static void sta_info_hash_add(struct ieee80211_local *local,
+			      struct sta_info *sta)
+{
+	sta->hnext = local->sta_hash[STA_HASH(sta->sta.addr)];
+	rcu_assign_pointer(local->sta_hash[STA_HASH(sta->sta.addr)], sta);
+}
+
+static void sta_unblock(struct work_struct *wk)
+{
+	struct sta_info *sta;
+
+	sta = container_of(wk, struct sta_info, drv_unblock_wk);
+
+	if (sta->dead)
+		return;
+
+	if (!test_sta_flags(sta, WLAN_STA_PS_STA))
+		ieee80211_sta_ps_deliver_wakeup(sta);
+	else if (test_and_clear_sta_flags(sta, WLAN_STA_PSPOLL)) {
+		clear_sta_flags(sta, WLAN_STA_PS_DRIVER);
+		ieee80211_sta_ps_deliver_poll_response(sta);
+	} else
+		clear_sta_flags(sta, WLAN_STA_PS_DRIVER);
+}
+
+static int sta_prepare_rate_control(struct ieee80211_local *local,
+				    struct sta_info *sta, gfp_t gfp)
+{
+	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
+		return 0;
+
+	sta->rate_ctrl = rate_control_get(local->rate_ctrl);
+	sta->rate_ctrl_priv = rate_control_alloc_sta(sta->rate_ctrl,
+						     &sta->sta, gfp);
+	if (!sta->rate_ctrl_priv) {
+		rate_control_put(sta->rate_ctrl);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
+				u8 *addr, gfp_t gfp)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta;
+	struct timespec uptime;
+	int i;
+
+	sta = kzalloc(sizeof(*sta) + local->hw.sta_data_size, gfp);
+	if (!sta)
+		return NULL;
+
+	spin_lock_init(&sta->lock);
+	spin_lock_init(&sta->flaglock);
+	INIT_WORK(&sta->drv_unblock_wk, sta_unblock);
+	INIT_WORK(&sta->ampdu_mlme.work, ieee80211_ba_session_work);
+	mutex_init(&sta->ampdu_mlme.mtx);
+
+	memcpy(sta->sta.addr, addr, ETH_ALEN);
+	sta->local = local;
+	sta->sdata = sdata;
+	sta->last_rx = jiffies;
+
+	do_posix_clock_monotonic_gettime(&uptime);
+	sta->last_connected = uptime.tv_sec;
+	ewma_init(&sta->avg_signal, 1024, 8);
+
+	if (sta_prepare_rate_control(local, sta, gfp)) {
+		kfree(sta);
+		return NULL;
+	}
+
+	for (i = 0; i < STA_TID_NUM; i++) {
+		/*
+		 * timer_to_tid must be initialized with identity mapping
+		 * to enable session_timer's data differentiation. See
+		 * sta_rx_agg_session_timer_expired for usage.
+		 */
+		sta->timer_to_tid[i] = i;
+	}
+	skb_queue_head_init(&sta->ps_tx_buf);
+	skb_queue_head_init(&sta->tx_filtered);
+
+	for (i = 0; i < NUM_RX_DATA_QUEUES; i++)
+		sta->last_seq_ctrl[i] = cpu_to_le16(USHRT_MAX);
+
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+	wiphy_debug(local->hw.wiphy, "Allocated STA %pM\n", sta->sta.addr);
+#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
+
+#ifdef CONFIG_MAC80211_MESH
+	sta->plink_state = NL80211_PLINK_LISTEN;
+	init_timer(&sta->plink_timer);
+#endif
+
+	return 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;
+	struct station_info sinfo;
+	unsigned long flags;
+	int err = 0;
+
+	lockdep_assert_held(&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)
+			wiphy_debug(local->hw.wiphy,
+				    "Finished adding IBSS STA %pM\n",
+				    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);
+
+	memset(&sinfo, 0, sizeof(sinfo));
+	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
+	 * and another CPU turns off the net device.
+	 */
+	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
+		wiphy_debug(local->hw.wiphy, "Added IBSS STA %pM\n",
+			    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_bss(sdata, sta->sta.addr)) {
+		spin_unlock_irqrestore(&local->sta_lock, flags);
+		mutex_unlock(&local->sta_mtx);
+		rcu_read_lock();
+		err = -EEXIST;
+		goto out_free;
+	}
+
+	spin_unlock_irqrestore(&local->sta_lock, flags);
+
+	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
+	wiphy_debug(local->hw.wiphy, "Inserted STA %pM\n", sta->sta.addr);
+#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
+
+	/* 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);
+
+	return 0;
+ out_free:
+	BUG_ON(!err);
+	__sta_info_free(local, 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)
+{
+	/*
+	 * This format has been mandated by the IEEE specifications,
+	 * so this line may not be changed to use the __set_bit() format.
+	 */
+	bss->tim[aid / 8] |= (1 << (aid % 8));
+}
+
+static inline void __bss_tim_clear(struct ieee80211_if_ap *bss, u16 aid)
+{
+	/*
+	 * This format has been mandated by the IEEE specifications,
+	 * so this line may not be changed to use the __clear_bit() format.
+	 */
+	bss->tim[aid / 8] &= ~(1 << (aid % 8));
+}
+
+static void __sta_info_set_tim_bit(struct ieee80211_if_ap *bss,
+				   struct sta_info *sta)
+{
+	BUG_ON(!bss);
+
+	__bss_tim_set(bss, sta->sta.aid);
+
+	if (sta->local->ops->set_tim) {
+		sta->local->tim_in_locked_section = true;
+		drv_set_tim(sta->local, &sta->sta, true);
+		sta->local->tim_in_locked_section = false;
+	}
+}
+
+void sta_info_set_tim_bit(struct sta_info *sta)
+{
+	unsigned long flags;
+
+	BUG_ON(!sta->sdata->bss);
+
+	spin_lock_irqsave(&sta->local->sta_lock, flags);
+	__sta_info_set_tim_bit(sta->sdata->bss, sta);
+	spin_unlock_irqrestore(&sta->local->sta_lock, flags);
+}
+
+static void __sta_info_clear_tim_bit(struct ieee80211_if_ap *bss,
+				     struct sta_info *sta)
+{
+	BUG_ON(!bss);
+
+	__bss_tim_clear(bss, sta->sta.aid);
+
+	if (sta->local->ops->set_tim) {
+		sta->local->tim_in_locked_section = true;
+		drv_set_tim(sta->local, &sta->sta, false);
+		sta->local->tim_in_locked_section = false;
+	}
+}
+
+void sta_info_clear_tim_bit(struct sta_info *sta)
+{
+	unsigned long flags;
+
+	BUG_ON(!sta->sdata->bss);
+
+	spin_lock_irqsave(&sta->local->sta_lock, flags);
+	__sta_info_clear_tim_bit(sta->sdata->bss, sta);
+	spin_unlock_irqrestore(&sta->local->sta_lock, flags);
+}
+
+static int sta_info_buffer_expired(struct sta_info *sta,
+				   struct sk_buff *skb)
+{
+	struct ieee80211_tx_info *info;
+	int timeout;
+
+	if (!skb)
+		return 0;
+
+	info = IEEE80211_SKB_CB(skb);
+
+	/* Timeout: (2 * listen_interval * beacon_int * 1024 / 1000000) sec */
+	timeout = (sta->listen_interval *
+		   sta->sdata->vif.bss_conf.beacon_int *
+		   32 / 15625) * HZ;
+	if (timeout < STA_TX_BUFFER_EXPIRE)
+		timeout = STA_TX_BUFFER_EXPIRE;
+	return time_after(jiffies, info->control.jiffies + timeout);
+}
+
+
+static bool sta_info_cleanup_expire_buffered(struct ieee80211_local *local,
+					     struct sta_info *sta)
+{
+	unsigned long flags;
+	struct sk_buff *skb;
+
+	if (skb_queue_empty(&sta->ps_tx_buf))
+		return false;
+
+	for (;;) {
+		spin_lock_irqsave(&sta->ps_tx_buf.lock, flags);
+		skb = skb_peek(&sta->ps_tx_buf);
+		if (sta_info_buffer_expired(sta, skb))
+			skb = __skb_dequeue(&sta->ps_tx_buf);
+		else
+			skb = NULL;
+		spin_unlock_irqrestore(&sta->ps_tx_buf.lock, flags);
+
+		if (!skb)
+			break;
+
+		local->total_ps_buffered--;
+#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
+		printk(KERN_DEBUG "Buffered frame expired (STA %pM)\n",
+		       sta->sta.addr);
+#endif
+		dev_kfree_skb(skb);
+
+		if (skb_queue_empty(&sta->ps_tx_buf) &&
+		    !test_sta_flags(sta, WLAN_STA_PS_DRIVER_BUF))
+			sta_info_clear_tim_bit(sta);
+	}
+
+	return true;
+}
+
+static int __must_check __sta_info_destroy(struct sta_info *sta)
+{
+	struct ieee80211_local *local;
+	struct ieee80211_sub_if_data *sdata;
+	struct sk_buff *skb;
+	unsigned long flags;
+	int ret, i;
+
+	might_sleep();
+
+	if (!sta)
+		return -ENOENT;
+
+	local = sta->local;
+	sdata = sta->sdata;
+
+	/*
+	 * Before removing the station from the driver and
+	 * rate control, it might still start new aggregation
+	 * sessions -- block that to make sure the tear-down
+	 * will be sufficient.
+	 */
+	set_sta_flags(sta, WLAN_STA_BLOCK_BA);
+	ieee80211_sta_tear_down_BA_sessions(sta, true);
+
+	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;
+
+	mutex_lock(&local->key_mtx);
+	for (i = 0; i < NUM_DEFAULT_KEYS; i++)
+		__ieee80211_key_free(key_mtx_dereference(local, sta->gtk[i]));
+	if (sta->ptk)
+		__ieee80211_key_free(key_mtx_dereference(local, sta->ptk));
+	mutex_unlock(&local->key_mtx);
+
+	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(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;
+	}
+
+	/*
+	 * At this point, after we wait for an RCU grace period,
+	 * neither mac80211 nor the driver can reference this
+	 * sta struct any more except by still existing timers
+	 * associated with this station that we clean up below.
+	 */
+	synchronize_rcu();
+
+#ifdef CONFIG_MAC80211_MESH
+	if (ieee80211_vif_is_mesh(&sdata->vif))
+		mesh_accept_plinks_update(sdata);
+#endif
+
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+	wiphy_debug(local->hw.wiphy, "Removed STA %pM\n", sta->sta.addr);
+#endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
+	cancel_work_sync(&sta->drv_unblock_wk);
+
+	cfg80211_del_sta(sdata->dev, sta->sta.addr, GFP_KERNEL);
+
+	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);
+
+	__sta_info_free(local, sta);
+
+	return 0;
+}
+
+int sta_info_destroy_addr(struct ieee80211_sub_if_data *sdata, const u8 *addr)
+{
+	struct sta_info *sta;
+	int ret;
+
+	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;
+}
+
+int sta_info_destroy_addr_bss(struct ieee80211_sub_if_data *sdata,
+			      const u8 *addr)
+{
+	struct sta_info *sta;
+	int ret;
+
+	mutex_lock(&sdata->local->sta_mtx);
+	sta = sta_info_get_bss(sdata, addr);
+	ret = __sta_info_destroy(sta);
+	mutex_unlock(&sdata->local->sta_mtx);
+
+	return ret;
+}
+
+static void sta_info_cleanup(unsigned long data)
+{
+	struct ieee80211_local *local = (struct ieee80211_local *) data;
+	struct sta_info *sta;
+	bool timer_needed = false;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sta, &local->sta_list, list)
+		if (sta_info_cleanup_expire_buffered(local, sta))
+			timer_needed = true;
+	rcu_read_unlock();
+
+	if (local->quiescing)
+		return;
+
+	if (!timer_needed)
+		return;
+
+	mod_timer(&local->sta_cleanup,
+		  round_jiffies(jiffies + STA_INFO_CLEANUP_INTERVAL));
+}
+
+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);
+}
+
+void sta_info_stop(struct ieee80211_local *local)
+{
+	del_timer(&local->sta_cleanup);
+	sta_info_flush(local, NULL);
+}
+
+/**
+ * sta_info_flush - flush matching STA entries from the STA table
+ *
+ * Returns the number of removed STA entries.
+ *
+ * @local: local interface data
+ * @sdata: matching rule for the net device (sta->dev) or %NULL to match all STAs
+ */
+int sta_info_flush(struct ieee80211_local *local,
+		   struct ieee80211_sub_if_data *sdata)
+{
+	struct sta_info *sta, *tmp;
+	int ret = 0;
+
+	might_sleep();
+
+	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)
+			WARN_ON(__sta_info_destroy(sta));
+	}
+	mutex_unlock(&local->sta_mtx);
+
+	return ret;
+}
+
+void ieee80211_sta_expire(struct ieee80211_sub_if_data *sdata,
+			  unsigned long exp_time)
+{
+	struct ieee80211_local *local = sdata->local;
+	struct sta_info *sta, *tmp;
+
+	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
+			WARN_ON(__sta_info_destroy(sta));
+		}
+	mutex_unlock(&local->sta_mtx);
+}
+
+struct ieee80211_sta *ieee80211_find_sta_by_ifaddr(struct ieee80211_hw *hw,
+					       const u8 *addr,
+					       const u8 *localaddr)
+{
+	struct sta_info *sta, *nxt;
+
+	/*
+	 * Just return a random station if localaddr is NULL
+	 * ... first in list.
+	 */
+	for_each_sta_info(hw_to_local(hw), addr, sta, nxt) {
+		if (localaddr &&
+		    compare_ether_addr(sta->sdata->vif.addr, localaddr) != 0)
+			continue;
+		if (!sta->uploaded)
+			return NULL;
+		return &sta->sta;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(ieee80211_find_sta_by_ifaddr);
+
+struct ieee80211_sta *ieee80211_find_sta(struct ieee80211_vif *vif,
+					 const u8 *addr)
+{
+	struct sta_info *sta;
+
+	if (!vif)
+		return NULL;
+
+	sta = sta_info_get_bss(vif_to_sdata(vif), addr);
+	if (!sta)
+		return NULL;
+
+	if (!sta->uploaded)
+		return NULL;
+
+	return &sta->sta;
+}
+EXPORT_SYMBOL(ieee80211_find_sta);
+
+static void clear_sta_ps_flags(void *_sta)
+{
+	struct sta_info *sta = _sta;
+
+	clear_sta_flags(sta, WLAN_STA_PS_DRIVER | WLAN_STA_PS_STA);
+}
+
+/* powersave support code */
+void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
+{
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+	struct ieee80211_local *local = sdata->local;
+	int sent, buffered;
+
+	clear_sta_flags(sta, WLAN_STA_PS_DRIVER_BUF);
+	if (!(local->hw.flags & IEEE80211_HW_AP_LINK_PS))
+		drv_sta_notify(local, sdata, STA_NOTIFY_AWAKE, &sta->sta);
+
+	if (!skb_queue_empty(&sta->ps_tx_buf))
+		sta_info_clear_tim_bit(sta);
+
+	/* Send all buffered frames to the station */
+	sent = ieee80211_add_pending_skbs(local, &sta->tx_filtered);
+	buffered = ieee80211_add_pending_skbs_fn(local, &sta->ps_tx_buf,
+						 clear_sta_ps_flags, sta);
+	sent += buffered;
+	local->total_ps_buffered -= buffered;
+
+#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
+	printk(KERN_DEBUG "%s: STA %pM aid %d sending %d filtered/%d PS frames "
+	       "since STA not sleeping anymore\n", sdata->name,
+	       sta->sta.addr, sta->sta.aid, sent - buffered, buffered);
+#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
+}
+
+void ieee80211_sta_ps_deliver_poll_response(struct sta_info *sta)
+{
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+	struct ieee80211_local *local = sdata->local;
+	struct sk_buff *skb;
+	int no_pending_pkts;
+
+	skb = skb_dequeue(&sta->tx_filtered);
+	if (!skb) {
+		skb = skb_dequeue(&sta->ps_tx_buf);
+		if (skb)
+			local->total_ps_buffered--;
+	}
+	no_pending_pkts = skb_queue_empty(&sta->tx_filtered) &&
+		skb_queue_empty(&sta->ps_tx_buf);
+
+	if (skb) {
+		struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+		struct ieee80211_hdr *hdr =
+			(struct ieee80211_hdr *) skb->data;
+
+		/*
+		 * Tell TX path to send this frame even though the STA may
+		 * still remain is PS mode after this frame exchange.
+		 */
+		info->flags |= IEEE80211_TX_CTL_PSPOLL_RESPONSE;
+
+#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
+		printk(KERN_DEBUG "STA %pM aid %d: PS Poll (entries after %d)\n",
+		       sta->sta.addr, sta->sta.aid,
+		       skb_queue_len(&sta->ps_tx_buf));
+#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
+
+		/* Use MoreData flag to indicate whether there are more
+		 * buffered frames for this STA */
+		if (no_pending_pkts)
+			hdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_MOREDATA);
+		else
+			hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_MOREDATA);
+
+		ieee80211_add_pending_skb(local, skb);
+
+		if (no_pending_pkts)
+			sta_info_clear_tim_bit(sta);
+#ifdef CONFIG_MAC80211_VERBOSE_PS_DEBUG
+	} else {
+		/*
+		 * FIXME: This can be the result of a race condition between
+		 *	  us expiring a frame and the station polling for it.
+		 *	  Should we send it a null-func frame indicating we
+		 *	  have nothing buffered for it?
+		 */
+		printk(KERN_DEBUG "%s: STA %pM sent PS Poll even "
+		       "though there are no buffered frames for it\n",
+		       sdata->name, sta->sta.addr);
+#endif /* CONFIG_MAC80211_VERBOSE_PS_DEBUG */
+	}
+}
+
+void ieee80211_sta_block_awake(struct ieee80211_hw *hw,
+			       struct ieee80211_sta *pubsta, bool block)
+{
+	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
+
+	trace_api_sta_block_awake(sta->local, pubsta, block);
+
+	if (block)
+		set_sta_flags(sta, WLAN_STA_PS_DRIVER);
+	else if (test_sta_flags(sta, WLAN_STA_PS_DRIVER))
+		ieee80211_queue_work(hw, &sta->drv_unblock_wk);
+}
+EXPORT_SYMBOL(ieee80211_sta_block_awake);
+
+void ieee80211_sta_set_tim(struct ieee80211_sta *pubsta)
+{
+	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
+
+	set_sta_flags(sta, WLAN_STA_PS_DRIVER_BUF);
+	sta_info_set_tim_bit(sta);
+}
+EXPORT_SYMBOL(ieee80211_sta_set_tim);