iwlwifi: serialize station management actions

We are seeing some race conditions between incoming station management
requests (station add/remove) and the internal unassoc RXON command that
modifies station table. Modify these flows to require the mutex to be held
and thus serializing them.

This fixes http://bugzilla.intellinuxwireless.org/show_bug.cgi?id=2207

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>

drivers/net/wireless/iwlwifi/iwl-agn.c

@@ -3391,10 +3391,12 @@ static int iwlagn_mac_sta_add(struct ieee80211_hw *hw,
 	int ret;
 	u8 sta_id;
 
-	sta_priv->common.sta_id = IWL_INVALID_STATION;
-
 	IWL_DEBUG_INFO(priv, "received request to add station %pM\n",
 			sta->addr);
+	mutex_lock(&priv->mutex);
+	IWL_DEBUG_INFO(priv, "proceeding to add station %pM\n",
+			sta->addr);
+	sta_priv->common.sta_id = IWL_INVALID_STATION;
 
 	atomic_set(&sta_priv->pending_frames, 0);
 	if (vif->type == NL80211_IFTYPE_AP)
@@ -3406,6 +3408,7 @@ static int iwlagn_mac_sta_add(struct ieee80211_hw *hw,
 		IWL_ERR(priv, "Unable to add station %pM (%d)\n",
 			sta->addr, ret);
 		/* Should we return success if return code is EEXIST ? */
+		mutex_unlock(&priv->mutex);
 		return ret;
 	}
 
@@ -3415,6 +3418,7 @@ static int iwlagn_mac_sta_add(struct ieee80211_hw *hw,
 	IWL_DEBUG_INFO(priv, "Initializing rate scaling for station %pM\n",
 		       sta->addr);
 	iwl_rs_rate_init(priv, sta, sta_id);
+	mutex_unlock(&priv->mutex);
 
 	return 0;
 }

drivers/net/wireless/iwlwifi/iwl-sta.c

@@ -1373,10 +1373,14 @@ int iwl_mac_sta_remove(struct ieee80211_hw *hw,
 
 	IWL_DEBUG_INFO(priv, "received request to remove station %pM\n",
 			sta->addr);
+	mutex_lock(&priv->mutex);
+	IWL_DEBUG_INFO(priv, "proceeding to remove station %pM\n",
+			sta->addr);
 	ret = iwl_remove_station(priv, sta_common->sta_id, sta->addr);
 	if (ret)
 		IWL_ERR(priv, "Error removing station %pM\n",
 			sta->addr);
+	mutex_unlock(&priv->mutex);
 	return ret;
 }
 EXPORT_SYMBOL(iwl_mac_sta_remove);

drivers/net/wireless/iwlwifi/iwl3945-base.c

@@ -3437,17 +3437,21 @@ static int iwl3945_mac_sta_add(struct ieee80211_hw *hw,
 	bool is_ap = vif->type == NL80211_IFTYPE_STATION;
 	u8 sta_id;
 
-	sta_priv->common.sta_id = IWL_INVALID_STATION;
-
 	IWL_DEBUG_INFO(priv, "received request to add station %pM\n",
 			sta->addr);
+	mutex_lock(&priv->mutex);
+	IWL_DEBUG_INFO(priv, "proceeding to add station %pM\n",
+			sta->addr);
+	sta_priv->common.sta_id = IWL_INVALID_STATION;
+
 
 	ret = iwl_add_station_common(priv, sta->addr, is_ap, &sta->ht_cap,
 				     &sta_id);
 	if (ret) {
 		IWL_ERR(priv, "Unable to add station %pM (%d)\n",
 			sta->addr, ret);
 		/* Should we return success if return code is EEXIST ? */
+		mutex_unlock(&priv->mutex);
 		return ret;
 	}
 
@@ -3457,6 +3461,7 @@ static int iwl3945_mac_sta_add(struct ieee80211_hw *hw,
 	IWL_DEBUG_INFO(priv, "Initializing rate scaling for station %pM\n",
 		       sta->addr);
 	iwl3945_rs_rate_init(priv, sta, sta_id);
+	mutex_unlock(&priv->mutex);
 
 	return 0;
 }