mac80211: use station mutex in configuration

There's no need to use RCU here, we can just lock
the station mutex instead. This allows the code
to sleep, which is necessary for later patches.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/cfg.c

@@ -954,11 +954,11 @@ static int ieee80211_change_station(struct wiphy *wiphy,
 	struct sta_info *sta;
 	struct ieee80211_sub_if_data *vlansdata;
 
-	rcu_read_lock();
+	mutex_lock(&local->sta_mtx);
 
 	sta = sta_info_get_bss(sdata, mac);
 	if (!sta) {
-		rcu_read_unlock();
+		mutex_unlock(&local->sta_mtx);
 		return -ENOENT;
 	}
 
@@ -966,7 +966,7 @@ static int ieee80211_change_station(struct wiphy *wiphy,
 	if (sdata->vif.type == NL80211_IFTYPE_STATION &&
 	    params->supported_rates &&
 	    !test_sta_flag(sta, WLAN_STA_TDLS_PEER)) {
-		rcu_read_unlock();
+		mutex_unlock(&local->sta_mtx);
 		return -EINVAL;
 	}
 
@@ -975,13 +975,13 @@ static int ieee80211_change_station(struct wiphy *wiphy,
 
 		if (vlansdata->vif.type != NL80211_IFTYPE_AP_VLAN &&
 		    vlansdata->vif.type != NL80211_IFTYPE_AP) {
-			rcu_read_unlock();
+			mutex_unlock(&local->sta_mtx);
 			return -EINVAL;
 		}
 
 		if (params->vlan->ieee80211_ptr->use_4addr) {
 			if (vlansdata->u.vlan.sta) {
-				rcu_read_unlock();
+				mutex_unlock(&local->sta_mtx);
 				return -EBUSY;
 			}
 
@@ -997,7 +997,7 @@ static int ieee80211_change_station(struct wiphy *wiphy,
 	if (test_sta_flag(sta, WLAN_STA_TDLS_PEER) && params->supported_rates)
 		rate_control_rate_init(sta);
 
-	rcu_read_unlock();
+	mutex_unlock(&local->sta_mtx);
 
 	if (sdata->vif.type == NL80211_IFTYPE_STATION &&
 	    params->sta_flags_mask & BIT(NL80211_STA_FLAG_AUTHORIZED))