mac80211: RCU-ify STA info structure access

This makes access to the STA hash table/list use RCU to protect
against freeing of items. However, it's not a true RCU, the
copy step is missing: whenever somebody changes a STA item it
is simply updated. This is an existing race condition that is
now somewhat understandable.

This patch also fixes the race key freeing vs. STA destruction
by making sure that sta_info_destroy() is always called under
RTNL and frees the key.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

23 files changed, 668 insertions, 461 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 6ac49231efa..e9ba6fcc0e4 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -136,7 +136,6 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
 	struct ieee80211_sub_if_data *sdata;
 	struct sta_info *sta = NULL;
 	enum ieee80211_key_alg alg;
-	int ret;
 	struct ieee80211_key *key;
 
 	sdata = IEEE80211_DEV_TO_SUB_IF(dev);
@@ -170,12 +169,7 @@ static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
 
 	ieee80211_key_link(key, sdata, sta);
 
-	ret = 0;
-
-	if (sta)
-		sta_info_put(sta);
-
-	return ret;
+	return 0;
 }
 
 static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
@@ -184,7 +178,6 @@ static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
 	struct ieee80211_sub_if_data *sdata;
 	struct sta_info *sta;
 	int ret;
-	struct ieee80211_key *key;
 
 	sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
@@ -195,21 +188,18 @@ static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
 
 		ret = 0;
 		if (sta->key) {
-			key = sta->key;
-			ieee80211_key_free(key);
+			ieee80211_key_free(sta->key);
 			WARN_ON(sta->key);
 		} else
 			ret = -ENOENT;
 
-		sta_info_put(sta);
 		return ret;
 	}
 
 	if (!sdata->keys[key_idx])
 		return -ENOENT;
 
-	key = sdata->keys[key_idx];
-	ieee80211_key_free(key);
+	ieee80211_key_free(sdata->keys[key_idx]);
 	WARN_ON(sdata->keys[key_idx]);
 
 	return 0;
@@ -292,8 +282,6 @@ static int ieee80211_get_key(struct wiphy *wiphy, struct net_device *dev,
 	err = 0;
 
  out:
-	if (sta)
-		sta_info_put(sta);
 	return err;
 }
 
@@ -311,7 +299,7 @@ static int ieee80211_config_default_key(struct wiphy *wiphy,
 
 static void sta_set_sinfo(struct sta_info *sta, struct station_info *sinfo)
 {
-	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
 
 	sinfo->filled = STATION_INFO_INACTIVE_TIME |
 			STATION_INFO_RX_BYTES |
@@ -340,16 +328,20 @@ static int ieee80211_dump_station(struct wiphy *wiphy, struct net_device *dev,
 {
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	struct sta_info *sta;
+	int ret = -ENOENT;
+
+	rcu_read_lock();
 
 	sta = sta_info_get_by_idx(local, idx, dev);
-	if (!sta)
-		return -ENOENT;
+	if (sta) {
+		ret = 0;
+		memcpy(mac, sta->addr, ETH_ALEN);
+		sta_set_sinfo(sta, sinfo);
+	}
 
-	memcpy(mac, sta->addr, ETH_ALEN);
-	sta_set_sinfo(sta, sinfo);
-	sta_info_put(sta);
+	rcu_read_unlock();
 
-	return 0;
+	return ret;
 }
 
 static int ieee80211_get_station(struct wiphy *wiphy, struct net_device *dev,
@@ -357,16 +349,21 @@ static int ieee80211_get_station(struct wiphy *wiphy, struct net_device *dev,
 {
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	struct sta_info *sta;
+	int ret = -ENOENT;
 
-	sta = sta_info_get(local, mac);
-	if (!sta)
-		return -ENOENT;
+	rcu_read_lock();
 
 	/* XXX: verify sta->dev == dev */
-	sta_set_sinfo(sta, sinfo);
-	sta_info_put(sta);
 
-	return 0;
+	sta = sta_info_get(local, mac);
+	if (sta) {
+		ret = 0;
+		sta_set_sinfo(sta, sinfo);
+	}
+
+	rcu_read_unlock();
+
+	return ret;
 }
 
 /*
@@ -559,8 +556,8 @@ static void ieee80211_send_layer2_update(struct sta_info *sta)
 	msg->xid_info[1] = 1;	/* LLC types/classes: Type 1 LLC */
 	msg->xid_info[2] = 0;	/* XID sender's receive window size (RW) */
 
-	skb->dev = sta->dev;
-	skb->protocol = eth_type_trans(skb, sta->dev);
+	skb->dev = sta->sdata->dev;
+	skb->protocol = eth_type_trans(skb, sta->sdata->dev);
 	memset(skb->cb, 0, sizeof(skb->cb));
 	netif_rx(skb);
 }
@@ -572,7 +569,7 @@ static void sta_apply_parameters(struct ieee80211_local *local,
 	u32 rates;
 	int i, j;
 	struct ieee80211_supported_band *sband;
-	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
 
 	if (params->station_flags & STATION_FLAG_CHANGED) {
 		sta->flags &= ~WLAN_STA_AUTHORIZED;
@@ -644,14 +641,13 @@ static int ieee80211_add_station(struct wiphy *wiphy, struct net_device *dev,
 		sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
 	if (ieee80211_vif_is_mesh(&sdata->vif))
-		sta = mesh_plink_add(mac, DEFAULT_RATES, dev);
+		sta = mesh_plink_add(mac, DEFAULT_RATES, sdata);
 	else
-		sta = sta_info_add(local, dev, mac, GFP_KERNEL);
+		sta = sta_info_add(sdata, mac);
 
 	if (IS_ERR(sta))
 		return PTR_ERR(sta);
 
-	sta->dev = sdata->dev;
 	if (sdata->vif.type == IEEE80211_IF_TYPE_VLAN ||
 	    sdata->vif.type == IEEE80211_IF_TYPE_AP)
 		ieee80211_send_layer2_update(sta);
@@ -662,15 +658,14 @@ static int ieee80211_add_station(struct wiphy *wiphy, struct net_device *dev,
 
 	rate_control_rate_init(sta, local);
 
-	sta_info_put(sta);
-
 	return 0;
 }
 
 static int ieee80211_del_station(struct wiphy *wiphy, struct net_device *dev,
 				 u8 *mac)
 {
-	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta;
 
 	if (mac) {
@@ -679,10 +674,14 @@ static int ieee80211_del_station(struct wiphy *wiphy, struct net_device *dev,
 		if (!sta)
 			return -ENOENT;
 
-		sta_info_free(sta);
-		sta_info_put(sta);
+		sta_info_unlink(&sta);
+
+		if (sta) {
+			synchronize_rcu();
+			sta_info_destroy(sta);
+		}
 	} else
-		sta_info_flush(local, dev);
+		sta_info_flush(local, sdata);
 
 	return 0;
 }
@@ -701,21 +700,19 @@ static int ieee80211_change_station(struct wiphy *wiphy,
 	if (!sta)
 		return -ENOENT;
 
-	if (params->vlan && params->vlan != sta->dev) {
+	if (params->vlan && params->vlan != sta->sdata->dev) {
 		vlansdata = IEEE80211_DEV_TO_SUB_IF(params->vlan);
 
 		if (vlansdata->vif.type != IEEE80211_IF_TYPE_VLAN ||
 		    vlansdata->vif.type != IEEE80211_IF_TYPE_AP)
 			return -EINVAL;
 
-		sta->dev = params->vlan;
+		sta->sdata = IEEE80211_DEV_TO_SUB_IF(params->vlan);
 		ieee80211_send_layer2_update(sta);
 	}
 
 	sta_apply_parameters(local, sta, params);
 
-	sta_info_put(sta);
-
 	return 0;
 }
 
@@ -735,23 +732,26 @@ static int ieee80211_add_mpath(struct wiphy *wiphy, struct net_device *dev,
 	if (sdata->vif.type != IEEE80211_IF_TYPE_MESH_POINT)
 		return -ENOTSUPP;
 
+	rcu_read_lock();
 	sta = sta_info_get(local, next_hop);
-	if (!sta)
+	if (!sta) {
+		rcu_read_unlock();
 		return -ENOENT;
+	}
 
 	err = mesh_path_add(dst, dev);
-	if (err)
+	if (err) {
+		rcu_read_unlock();
 		return err;
+	}
 
-	rcu_read_lock();
 	mpath = mesh_path_lookup(dst, dev);
 	if (!mpath) {
 		rcu_read_unlock();
-		sta_info_put(sta);
 		return -ENXIO;
 	}
 	mesh_path_fix_nexthop(mpath, sta);
-	sta_info_put(sta);
+
 	rcu_read_unlock();
 	return 0;
 }
@@ -760,7 +760,7 @@ static int ieee80211_del_mpath(struct wiphy *wiphy, struct net_device *dev,
 				 u8 *dst)
 {
 	if (dst)
-		return mesh_path_del(dst, dev);
+		return mesh_path_del(dst, dev, false);
 
 	mesh_path_flush(dev);
 	return 0;
@@ -781,20 +781,22 @@ static int ieee80211_change_mpath(struct wiphy *wiphy,
 	if (sdata->vif.type != IEEE80211_IF_TYPE_MESH_POINT)
 		return -ENOTSUPP;
 
+	rcu_read_lock();
+
 	sta = sta_info_get(local, next_hop);
-	if (!sta)
+	if (!sta) {
+		rcu_read_unlock();
 		return -ENOENT;
+	}
 
-	rcu_read_lock();
 	mpath = mesh_path_lookup(dst, dev);
 	if (!mpath) {
 		rcu_read_unlock();
-		sta_info_put(sta);
 		return -ENOENT;
 	}
 
 	mesh_path_fix_nexthop(mpath, sta);
-	sta_info_put(sta);
+
 	rcu_read_unlock();
 	return 0;
 }
diff --git a/net/mac80211/debugfs_sta.c b/net/mac80211/debugfs_sta.c
index ed7c9f3b460..73cfb4da464 100644
--- a/net/mac80211/debugfs_sta.c
+++ b/net/mac80211/debugfs_sta.c
@@ -51,7 +51,7 @@ static const struct file_operations sta_ ##name## _ops = {		\
 		STA_OPS(name)
 
 STA_FILE(aid, aid, D);
-STA_FILE(dev, dev->name, S);
+STA_FILE(dev, sdata->dev->name, S);
 STA_FILE(rx_packets, rx_packets, LU);
 STA_FILE(tx_packets, tx_packets, LU);
 STA_FILE(rx_bytes, rx_bytes, LU);
@@ -200,7 +200,7 @@ static ssize_t sta_agg_status_write(struct file *file,
 		const char __user *user_buf, size_t count, loff_t *ppos)
 {
 	struct sta_info *sta = file->private_data;
-	struct net_device *dev = sta->dev;
+	struct net_device *dev = sta->sdata->dev;
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	struct ieee80211_hw *hw = &local->hw;
 	u8 *da = sta->addr;
diff --git a/net/mac80211/debugfs_sta.h b/net/mac80211/debugfs_sta.h
index 574a1cd54b9..8b608903259 100644
--- a/net/mac80211/debugfs_sta.h
+++ b/net/mac80211/debugfs_sta.h
@@ -1,6 +1,8 @@
 #ifndef __MAC80211_DEBUGFS_STA_H
 #define __MAC80211_DEBUGFS_STA_H
 
+#include "sta_info.h"
+
 #ifdef CONFIG_MAC80211_DEBUGFS
 void ieee80211_sta_debugfs_add(struct sta_info *sta);
 void ieee80211_sta_debugfs_remove(struct sta_info *sta);
diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c
index 727af295c96..85b1391375c 100644
--- a/net/mac80211/ieee80211.c
+++ b/net/mac80211/ieee80211.c
@@ -375,15 +375,19 @@ static int ieee80211_stop(struct net_device *dev)
 
 	sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 
-	list_for_each_entry(sta, &local->sta_list, list) {
-		if (sta->dev == dev)
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(sta, &local->sta_list, list) {
+		if (sta->sdata == sdata)
 			for (i = 0; i <  STA_TID_NUM; i++)
-				ieee80211_sta_stop_rx_ba_session(sta->dev,
+				ieee80211_sta_stop_rx_ba_session(sdata->dev,
 						sta->addr, i,
 						WLAN_BACK_RECIPIENT,
 						WLAN_REASON_QSTA_LEAVE_QBSS);
 	}
 
+	rcu_read_unlock();
+
 	netif_stop_queue(dev);
 
 	/*
@@ -449,7 +453,7 @@ static int ieee80211_stop(struct net_device *dev)
 		netif_tx_unlock_bh(local->mdev);
 		break;
 	case IEEE80211_IF_TYPE_MESH_POINT:
-		sta_info_flush(local, dev);
+		sta_info_flush(local, sdata);
 		/* fall through */
 	case IEEE80211_IF_TYPE_STA:
 	case IEEE80211_IF_TYPE_IBSS:
@@ -522,9 +526,12 @@ int ieee80211_start_tx_ba_session(struct ieee80211_hw *hw, u8 *ra, u16 tid)
 				print_mac(mac, ra), tid);
 #endif /* CONFIG_MAC80211_HT_DEBUG */
 
+	rcu_read_lock();
+
 	sta = sta_info_get(local, ra);
 	if (!sta) {
 		printk(KERN_DEBUG "Could not find the station\n");
+		rcu_read_unlock();
 		return -ENOENT;
 	}
 
@@ -564,7 +571,7 @@ int ieee80211_start_tx_ba_session(struct ieee80211_hw *hw, u8 *ra, u16 tid)
 		spin_unlock_bh(&local->mdev->queue_lock);
 		goto start_ba_exit;
 	}
-	sdata = IEEE80211_DEV_TO_SUB_IF(sta->dev);
+	sdata = sta->sdata;
 
 	/* Ok, the Addba frame hasn't been sent yet, but if the driver calls the
 	 * call back right away, it must see that the flow has begun */
@@ -601,7 +608,7 @@ int ieee80211_start_tx_ba_session(struct ieee80211_hw *hw, u8 *ra, u16 tid)
 			sta->ampdu_mlme.dialog_token_allocator;
 	sta->ampdu_mlme.tid_tx[tid].ssn = start_seq_num;
 
-	ieee80211_send_addba_request(sta->dev, ra, tid,
+	ieee80211_send_addba_request(sta->sdata->dev, ra, tid,
 			 sta->ampdu_mlme.tid_tx[tid].dialog_token,
 			 sta->ampdu_mlme.tid_tx[tid].ssn,
 			 0x40, 5000);
@@ -614,7 +621,7 @@ int ieee80211_start_tx_ba_session(struct ieee80211_hw *hw, u8 *ra, u16 tid)
 
 start_ba_exit:
 	spin_unlock_bh(&sta->ampdu_mlme.ampdu_tx);
-	sta_info_put(sta);
+	rcu_read_unlock();
 	return ret;
 }
 EXPORT_SYMBOL(ieee80211_start_tx_ba_session);
@@ -637,9 +644,12 @@ int ieee80211_stop_tx_ba_session(struct ieee80211_hw *hw,
 				print_mac(mac, ra), tid);
 #endif /* CONFIG_MAC80211_HT_DEBUG */
 
+	rcu_read_lock();
 	sta = sta_info_get(local, ra);
-	if (!sta)
+	if (!sta) {
+		rcu_read_unlock();
 		return -ENOENT;
+	}
 
 	/* check if the TID is in aggregation */
 	state = &sta->ampdu_mlme.tid_tx[tid].state;
@@ -673,7 +683,7 @@ int ieee80211_stop_tx_ba_session(struct ieee80211_hw *hw,
 
 stop_BA_exit:
 	spin_unlock_bh(&sta->ampdu_mlme.ampdu_tx);
-	sta_info_put(sta);
+	rcu_read_unlock();
 	return ret;
 }
 EXPORT_SYMBOL(ieee80211_stop_tx_ba_session);
@@ -691,8 +701,10 @@ void ieee80211_start_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u16 tid)
 		return;
 	}
 
+	rcu_read_lock();
 	sta = sta_info_get(local, ra);
 	if (!sta) {
+		rcu_read_unlock();
 		printk(KERN_DEBUG "Could not find station: %s\n",
 				print_mac(mac, ra));
 		return;
@@ -705,7 +717,7 @@ void ieee80211_start_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u16 tid)
 		printk(KERN_DEBUG "addBA was not requested yet, state is %d\n",
 				*state);
 		spin_unlock_bh(&sta->ampdu_mlme.ampdu_tx);
-		sta_info_put(sta);
+		rcu_read_unlock();
 		return;
 	}
 
@@ -718,7 +730,7 @@ void ieee80211_start_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u16 tid)
 		ieee80211_wake_queue(hw, sta->tid_to_tx_q[tid]);
 	}
 	spin_unlock_bh(&sta->ampdu_mlme.ampdu_tx);
-	sta_info_put(sta);
+	rcu_read_unlock();
 }
 EXPORT_SYMBOL(ieee80211_start_tx_ba_cb);
 
@@ -739,10 +751,12 @@ void ieee80211_stop_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u8 tid)
 	printk(KERN_DEBUG "Stop a BA session requested on DA %s tid %d\n",
 				print_mac(mac, ra), tid);
 
+	rcu_read_lock();
 	sta = sta_info_get(local, ra);
 	if (!sta) {
 		printk(KERN_DEBUG "Could not find station: %s\n",
 				print_mac(mac, ra));
+		rcu_read_unlock();
 		return;
 	}
 	state = &sta->ampdu_mlme.tid_tx[tid].state;
@@ -750,13 +764,13 @@ void ieee80211_stop_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u8 tid)
 	spin_lock_bh(&sta->ampdu_mlme.ampdu_tx);
 	if ((*state & HT_AGG_STATE_REQ_STOP_BA_MSK) == 0) {
 		printk(KERN_DEBUG "unexpected callback to A-MPDU stop\n");
-		sta_info_put(sta);
 		spin_unlock_bh(&sta->ampdu_mlme.ampdu_tx);
+		rcu_read_unlock();
 		return;
 	}
 
 	if (*state & HT_AGG_STATE_INITIATOR_MSK)
-		ieee80211_send_delba(sta->dev, ra, tid,
+		ieee80211_send_delba(sta->sdata->dev, ra, tid,
 			WLAN_BACK_INITIATOR, WLAN_REASON_QSTA_NOT_USE);
 
 	agg_queue = sta->tid_to_tx_q[tid];
@@ -777,7 +791,7 @@ void ieee80211_stop_tx_ba_cb(struct ieee80211_hw *hw, u8 *ra, u8 tid)
 	sta->ampdu_mlme.tid_tx[tid].addba_req_num = 0;
 	spin_unlock_bh(&sta->ampdu_mlme.ampdu_tx);
 
-	sta_info_put(sta);
+	rcu_read_unlock();
 }
 EXPORT_SYMBOL(ieee80211_stop_tx_ba_cb);
 
@@ -887,32 +901,41 @@ int ieee80211_if_update_wds(struct net_device *dev, u8 *remote_addr)
 	struct sta_info *sta;
 	DECLARE_MAC_BUF(mac);
 
+	might_sleep();
+
 	if (compare_ether_addr(remote_addr, sdata->u.wds.remote_addr) == 0)
 		return 0;
 
+	rcu_read_lock();
+
 	/* Create STA entry for the new peer */
-	sta = sta_info_add(local, dev, remote_addr, GFP_KERNEL);
-	if (IS_ERR(sta))
+	sta = sta_info_add(sdata, remote_addr);
+	if (IS_ERR(sta)) {
+		rcu_read_unlock();
 		return PTR_ERR(sta);
+	}
 
 	sta->flags |= WLAN_STA_AUTHORIZED;
 
-	sta_info_put(sta);
-
 	/* Remove STA entry for the old peer */
 	sta = sta_info_get(local, sdata->u.wds.remote_addr);
-	if (sta) {
-		sta_info_free(sta);
-		sta_info_put(sta);
-	} else {
+	if (sta)
+		sta_info_unlink(&sta);
+	else
 		printk(KERN_DEBUG "%s: could not find STA entry for WDS link "
 		       "peer %s\n",
 		       dev->name, print_mac(mac, sdata->u.wds.remote_addr));
-	}
 
 	/* Update WDS link data */
 	memcpy(&sdata->u.wds.remote_addr, remote_addr, ETH_ALEN);
 
+	rcu_read_unlock();
+
+	if (sta) {
+		synchronize_rcu();
+		sta_info_destroy(sta);
+	}
+
 	return 0;
 }
 
@@ -1330,6 +1353,8 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
 		return;
 	}
 
+	rcu_read_lock();
+
 	if (status->excessive_retries) {
 		struct sta_info *sta;
 		sta = sta_info_get(local, hdr->addr1);
@@ -1343,10 +1368,9 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
 				status->flags |= IEEE80211_TX_STATUS_TX_FILTERED;
 				ieee80211_handle_filtered_frame(local, sta,
 								skb, status);
-				sta_info_put(sta);
+				rcu_read_unlock();
 				return;
 			}
-			sta_info_put(sta);
 		}
 	}
 
@@ -1356,12 +1380,14 @@ void ieee80211_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb,
 		if (sta) {
 			ieee80211_handle_filtered_frame(local, sta, skb,
 							status);
-			sta_info_put(sta);
+			rcu_read_unlock();
 			return;
 		}
 	} else
 		rate_control_tx_status(local->mdev, skb, status);
 
+	rcu_read_unlock();
+
 	ieee80211_led_tx(local, 0);
 
 	/* SNMP counters
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index d3b5cc57af4..8e440c5706d 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -574,6 +574,7 @@ struct ieee80211_local {
 	unsigned int filter_flags; /* FIF_* */
 	struct iw_statistics wstats;
 	u8 wstats_flags;
+	bool tim_in_locked_section; /* see ieee80211_beacon_get() */
 	int tx_headroom; /* required headroom for hardware/radiotap */
 
 	enum {
@@ -591,9 +592,15 @@ struct ieee80211_local {
 	struct sk_buff_head skb_queue;
 	struct sk_buff_head skb_queue_unreliable;
 
-	/* Station data structures */
-	rwlock_t sta_lock; /* protects STA data structures */
-	int num_sta; /* number of stations in sta_list */
+	/* Station data */
+	/*
+	 * The lock only protects the list, hash, timer and counter
+	 * against manipulation, reads are done in RCU. Additionally,
+	 * the lock protects each BSS's TIM bitmap and a few items
+	 * in a STA info structure.
+	 */
+	spinlock_t sta_lock;
+	unsigned long num_sta;
 	struct list_head sta_list;
 	struct sta_info *sta_hash[STA_HASH_SIZE];
 	struct timer_list sta_cleanup;
diff --git a/net/mac80211/ieee80211_iface.c b/net/mac80211/ieee80211_iface.c
index b0f17a2b1a4..98b22736e88 100644
--- a/net/mac80211/ieee80211_iface.c
+++ b/net/mac80211/ieee80211_iface.c
@@ -240,16 +240,21 @@ void ieee80211_if_reinit(struct net_device *dev)
 		break;
 	}
 	case IEEE80211_IF_TYPE_WDS:
+		rcu_read_lock();
 		sta = sta_info_get(local, sdata->u.wds.remote_addr);
 		if (sta) {
-			sta_info_free(sta);
-			sta_info_put(sta);
+			sta_info_unlink(&sta);
 		} else {
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
 			printk(KERN_DEBUG "%s: Someone had deleted my STA "
 			       "entry for the WDS link\n", dev->name);
 #endif /* CONFIG_MAC80211_VERBOSE_DEBUG */
 		}
+		rcu_read_unlock();
+		if (sta) {
+			synchronize_rcu();
+			sta_info_destroy(sta);
+		}
 		break;
 	case IEEE80211_IF_TYPE_MESH_POINT:
 	case IEEE80211_IF_TYPE_STA:
@@ -275,7 +280,7 @@ void ieee80211_if_reinit(struct net_device *dev)
 	}
 
 	/* remove all STAs that are bound to this virtual interface */
-	sta_info_flush(local, dev);
+	sta_info_flush(local, sdata);
 
 	memset(&sdata->u, 0, sizeof(sdata->u));
 	ieee80211_if_sdata_init(sdata);
diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c
index 38e2d83e15f..5147152b926 100644
--- a/net/mac80211/ieee80211_ioctl.c
+++ b/net/mac80211/ieee80211_ioctl.c
@@ -33,8 +33,7 @@ static int ieee80211_set_encryption(struct net_device *dev, u8 *sta_addr,
 				    size_t key_len)
 {
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
-	int ret;
-	struct sta_info *sta = NULL;
+	struct sta_info *sta;
 	struct ieee80211_key *key;
 	struct ieee80211_sub_if_data *sdata;
 
@@ -51,24 +50,23 @@ static int ieee80211_set_encryption(struct net_device *dev, u8 *sta_addr,
 			key = sdata->keys[idx];
 		} else {
 			sta = sta_info_get(local, sta_addr);
-			if (!sta) {
-				ret = -ENOENT;
-				key = NULL;
-				goto err_out;
-			}
-
+			if (!sta)
+				return -ENOENT;
 			key = sta->key;
 		}
 
 		if (!key)
-			ret = -ENOENT;
-		else
-			ret = 0;
+			return -ENOENT;
+
+		ieee80211_key_free(key);
+		return 0;
 	} else {
 		key = ieee80211_key_alloc(alg, idx, key_len, _key);
 		if (!key)
 			return -ENOMEM;
 
+		sta = NULL;
+
 		if (!is_broadcast_ether_addr(sta_addr)) {
 			set_tx_key = 0;
 			/*
@@ -78,14 +76,14 @@ static int ieee80211_set_encryption(struct net_device *dev, u8 *sta_addr,
 			 * work around this.
 			 */
 			if (idx != 0 && alg != ALG_WEP) {
-				ret = -EINVAL;
-				goto err_out;
+				ieee80211_key_free(key);
+				return -EINVAL;
 			}
 
 			sta = sta_info_get(local, sta_addr);
 			if (!sta) {
-				ret = -ENOENT;
-				goto err_out;
+				ieee80211_key_free(key);
+				return -ENOENT;
 			}
 		}
 
@@ -93,18 +91,9 @@ static int ieee80211_set_encryption(struct net_device *dev, u8 *sta_addr,
 
 		if (set_tx_key || (!sta && !sdata->default_key && key))
 			ieee80211_set_default_key(sdata, idx);
-
-		/* don't free key later */
-		key = NULL;
-
-		ret = 0;
 	}
 
- err_out:
-	if (sta)
-		sta_info_put(sta);
-	ieee80211_key_free(key);
-	return ret;
+	return 0;
 }
 
 static int ieee80211_ioctl_siwgenie(struct net_device *dev,
@@ -625,7 +614,7 @@ static int ieee80211_ioctl_giwrate(struct net_device *dev,
 	else
 		rate->value = 0;
 	rate->value *= 100000;
-	sta_info_put(sta);
+
 	return 0;
 }
 
@@ -1000,7 +989,6 @@ static struct iw_statistics *ieee80211_get_wireless_stats(struct net_device *dev
 		wstats->qual.qual = sta->last_signal;
 		wstats->qual.noise = sta->last_noise;
 		wstats->qual.updated = local->wstats_flags;
-		sta_info_put(sta);
 	}
 	return wstats;
 }
diff --git a/net/mac80211/ieee80211_rate.c b/net/mac80211/ieee80211_rate.c
index ebe29b716b2..4de06f128d9 100644
--- a/net/mac80211/ieee80211_rate.c
+++ b/net/mac80211/ieee80211_rate.c
@@ -170,9 +170,12 @@ void rate_control_get_rate(struct net_device *dev,
 	struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
 	struct rate_control_ref *ref = local->rate_ctrl;
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
-	struct sta_info *sta = sta_info_get(local, hdr->addr1);
+	struct sta_info *sta;
 	int i;
 
+	rcu_read_lock();
+	sta = sta_info_get(local, hdr->addr1);
+
 	memset(sel, 0, sizeof(struct rate_selection));
 
 	ref->ops->get_rate(ref->priv, dev, sband, skb, sel);
@@ -190,8 +193,7 @@ void rate_control_get_rate(struct net_device *dev,
 		}
 	}
 
-	if (sta)
-		sta_info_put(sta);
+	rcu_read_unlock();
 }
 
 struct rate_control_ref *rate_control_get(struct rate_control_ref *ref)
diff --git a/net/mac80211/ieee80211_rate.h b/net/mac80211/ieee80211_rate.h
index 5f9a2ca49a5..bfd0a1982e4 100644
--- a/net/mac80211/ieee80211_rate.h
+++ b/net/mac80211/ieee80211_rate.h
@@ -14,6 +14,7 @@
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>
 #include <linux/types.h>
+#include <linux/kref.h>
 #include <net/mac80211.h>
 #include "ieee80211_i.h"
 #include "sta_info.h"
diff --git a/net/mac80211/ieee80211_sta.c b/net/mac80211/ieee80211_sta.c
index 9f933aeca71..a3e96eb59eb 100644
--- a/net/mac80211/ieee80211_sta.c
+++ b/net/mac80211/ieee80211_sta.c
@@ -24,6 +24,7 @@
 #include <linux/wireless.h>
 #include <linux/random.h>
 #include <linux/etherdevice.h>
+#include <linux/rtnetlink.h>
 #include <net/iw_handler.h>
 #include <asm/types.h>
 
@@ -845,6 +846,8 @@ static void ieee80211_associated(struct net_device *dev,
 
 	ifsta->state = IEEE80211_ASSOCIATED;
 
+	rcu_read_lock();
+
 	sta = sta_info_get(local, ifsta->bssid);
 	if (!sta) {
 		printk(KERN_DEBUG "%s: No STA entry for own AP %s\n",
@@ -860,7 +863,7 @@ static void ieee80211_associated(struct net_device *dev,
 				       "range\n",
 				       dev->name, print_mac(mac, ifsta->bssid));
 				disassoc = 1;
-				sta_info_free(sta);
+				sta_info_unlink(&sta);
 			} else
 				ieee80211_send_probe_req(dev, ifsta->bssid,
 							 local->scan_ssid,
@@ -876,8 +879,17 @@ static void ieee80211_associated(struct net_device *dev,
 							 ifsta->ssid_len);
 			}
 		}
-		sta_info_put(sta);
 	}
+
+	rcu_read_unlock();
+
+	if (disassoc && sta) {
+		synchronize_rcu();
+		rtnl_lock();
+		sta_info_destroy(sta);
+		rtnl_unlock();
+	}
+
 	if (disassoc) {
 		ifsta->state = IEEE80211_DISABLED;
 		ieee80211_set_associated(dev, ifsta, 0);
@@ -1103,9 +1115,13 @@ static void ieee80211_sta_process_addba_request(struct net_device *dev,
 	int ret = -EOPNOTSUPP;
 	DECLARE_MAC_BUF(mac);
 
+	rcu_read_lock();
+
 	sta = sta_info_get(local, mgmt->sa);
-	if (!sta)
+	if (!sta) {
+		rcu_read_unlock();
 		return;
+	}
 
 	/* extract session parameters from addba request frame */
 	dialog_token = mgmt->u.action.u.addba_req.dialog_token;
@@ -1197,9 +1213,9 @@ end:
 	spin_unlock_bh(&sta->ampdu_mlme.ampdu_rx);
 
 end_no_lock:
-	ieee80211_send_addba_resp(sta->dev, sta->addr, tid, dialog_token,
-				status, 1, buf_size, timeout);
-	sta_info_put(sta);
+	ieee80211_send_addba_resp(sta->sdata->dev, sta->addr, tid,
+				  dialog_token, status, 1, buf_size, timeout);
+	rcu_read_unlock();
 }
 
 static void ieee80211_sta_process_addba_resp(struct net_device *dev,
@@ -1213,9 +1229,13 @@ static void ieee80211_sta_process_addba_resp(struct net_device *dev,
 	u16 tid;
 	u8 *state;
 
+	rcu_read_lock();
+
 	sta = sta_info_get(local, mgmt->sa);
-	if (!sta)
+	if (!sta) {
+		rcu_read_unlock();
 		return;
+	}
 
 	capab = le16_to_cpu(mgmt->u.action.u.addba_resp.capab);
 	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
@@ -1230,7 +1250,7 @@ static void ieee80211_sta_process_addba_resp(struct net_device *dev,
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		printk(KERN_DEBUG "wrong addBA response token, tid %d\n", tid);
 #endif /* CONFIG_MAC80211_HT_DEBUG */
-		sta_info_put(sta);
+		rcu_read_unlock();
 		return;
 	}
 
@@ -1244,7 +1264,7 @@ static void ieee80211_sta_process_addba_resp(struct net_device *dev,
 			spin_unlock_bh(&sta->ampdu_mlme.ampdu_tx);
 			printk(KERN_DEBUG "state not HT_ADDBA_REQUESTED_MSK:"
 				"%d\n", *state);
-			sta_info_put(sta);
+			rcu_read_unlock();
 			return;
 		}
 
@@ -1271,7 +1291,7 @@ static void ieee80211_sta_process_addba_resp(struct net_device *dev,
 		ieee80211_stop_tx_ba_session(hw, sta->addr, tid,
 					     WLAN_BACK_INITIATOR);
 	}
-	sta_info_put(sta);
+	rcu_read_unlock();
 }
 
 void ieee80211_send_delba(struct net_device *dev, const u8 *da, u16 tid,
@@ -1326,16 +1346,20 @@ void ieee80211_sta_stop_rx_ba_session(struct net_device *dev, u8 *ra, u16 tid,
 	struct sta_info *sta;
 	int ret, i;
 
+	rcu_read_lock();
+
 	sta = sta_info_get(local, ra);
-	if (!sta)
+	if (!sta) {
+		rcu_read_unlock();
 		return;
+	}
 
 	/* check if TID is in operational state */
 	spin_lock_bh(&sta->ampdu_mlme.ampdu_rx);
 	if (sta->ampdu_mlme.tid_rx[tid].state
 				!= HT_AGG_STATE_OPERATIONAL) {
 		spin_unlock_bh(&sta->ampdu_mlme.ampdu_rx);
-		sta_info_put(sta);
+		rcu_read_unlock();
 		return;
 	}
 	sta->ampdu_mlme.tid_rx[tid].state =
@@ -1374,7 +1398,7 @@ void ieee80211_sta_stop_rx_ba_session(struct net_device *dev, u8 *ra, u16 tid,
 	kfree(sta->ampdu_mlme.tid_rx[tid].reorder_buf);
 
 	sta->ampdu_mlme.tid_rx[tid].state = HT_AGG_STATE_IDLE;
-	sta_info_put(sta);
+	rcu