iwlwifi: dvm: handle FLUSH ampdu actions from mac80211

Until now we didn't handle properly the FLUSH ampdu action
coming from mac80211. This could result in SCD queue leak:
mac80211 would STOP_FLUSH an AMPDU Tx session and remove
the station. If we had still packets on the ring, we
wouldn't deallocate the SCD queue and wait for it to be
empty.
The indication of the queue being empty comes from the Tx
response flow which relies on the tid_data structure. The
problem is that this structure has been cleared when the
station has been removed.
In order to solve this issue, block in the STOP_FLUSH
ampdu_action until the SCD queue is flushed, and only then,
let mac80211 move forward to remove the station.
iwlagn_txfifo_flush had to be enhanced to allow this.

The bug fixed here caused the "txq_id mismatch: 12 0" print.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/iwlwifi/dvm/agn.h

@@ -178,7 +178,7 @@ int iwlagn_hw_valid_rtc_data_addr(u32 addr);
 /* lib */
 int iwlagn_send_tx_power(struct iwl_priv *priv);
 void iwlagn_temperature(struct iwl_priv *priv);
-int iwlagn_txfifo_flush(struct iwl_priv *priv);
+int iwlagn_txfifo_flush(struct iwl_priv *priv, u32 scd_q_msk);
 void iwlagn_dev_txfifo_flush(struct iwl_priv *priv);
 int iwlagn_send_beacon_cmd(struct iwl_priv *priv);
 int iwl_send_statistics_request(struct iwl_priv *priv,
@@ -212,6 +212,8 @@ int iwlagn_tx_agg_oper(struct iwl_priv *priv, struct ieee80211_vif *vif,
 			struct ieee80211_sta *sta, u16 tid, u8 buf_size);
 int iwlagn_tx_agg_stop(struct iwl_priv *priv, struct ieee80211_vif *vif,
 		       struct ieee80211_sta *sta, u16 tid);
+int iwlagn_tx_agg_flush(struct iwl_priv *priv, struct ieee80211_vif *vif,
+			struct ieee80211_sta *sta, u16 tid);
 int iwlagn_rx_reply_compressed_ba(struct iwl_priv *priv,
 				   struct iwl_rx_cmd_buffer *rxb,
 				   struct iwl_device_cmd *cmd);

drivers/net/wireless/iwlwifi/dvm/lib.c

@@ -136,7 +136,7 @@ int iwlagn_manage_ibss_station(struct iwl_priv *priv,
  *  1. acquire mutex before calling
  *  2. make sure rf is on and not in exit state
  */
-int iwlagn_txfifo_flush(struct iwl_priv *priv)
+int iwlagn_txfifo_flush(struct iwl_priv *priv, u32 scd_q_msk)
 {
 	struct iwl_txfifo_flush_cmd flush_cmd;
 	struct iwl_host_cmd cmd = {
@@ -162,6 +162,9 @@ int iwlagn_txfifo_flush(struct iwl_priv *priv)
 	if (priv->nvm_data->sku_cap_11n_enable)
 		flush_cmd.queue_control |= IWL_AGG_TX_QUEUE_MSK;
 
+	if (scd_q_msk)
+		flush_cmd.queue_control = cpu_to_le32(scd_q_msk);
+
 	IWL_DEBUG_INFO(priv, "queue control: 0x%x\n",
 		       flush_cmd.queue_control);
 	flush_cmd.flush_control = cpu_to_le16(IWL_DROP_ALL);
@@ -173,7 +176,7 @@ void iwlagn_dev_txfifo_flush(struct iwl_priv *priv)
 {
 	mutex_lock(&priv->mutex);
 	ieee80211_stop_queues(priv->hw);
-	if (iwlagn_txfifo_flush(priv)) {
+	if (iwlagn_txfifo_flush(priv, 0)) {
 		IWL_ERR(priv, "flush request fail\n");
 		goto done;
 	}

drivers/net/wireless/iwlwifi/dvm/mac80211.c

@@ -777,9 +777,12 @@ static int iwlagn_mac_ampdu_action(struct ieee80211_hw *hw,
 		IWL_DEBUG_HT(priv, "start Tx\n");
 		ret = iwlagn_tx_agg_start(priv, vif, sta, tid, ssn);
 		break;
-	case IEEE80211_AMPDU_TX_STOP_CONT:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH:
 	case IEEE80211_AMPDU_TX_STOP_FLUSH_CONT:
+		IWL_DEBUG_HT(priv, "Flush Tx\n");
+		ret = iwlagn_tx_agg_flush(priv, vif, sta, tid);
+		break;
+	case IEEE80211_AMPDU_TX_STOP_CONT:
 		IWL_DEBUG_HT(priv, "stop Tx\n");
 		ret = iwlagn_tx_agg_stop(priv, vif, sta, tid);
 		if ((ret == 0) && (priv->agg_tids_count > 0)) {
@@ -1122,7 +1125,7 @@ static void iwlagn_mac_flush(struct ieee80211_hw *hw, u32 queues, bool drop)
 	 */
 	if (drop) {
 		IWL_DEBUG_MAC80211(priv, "send flush command\n");
-		if (iwlagn_txfifo_flush(priv)) {
+		if (iwlagn_txfifo_flush(priv, 0)) {
 			IWL_ERR(priv, "flush request fail\n");
 			goto done;
 		}

drivers/net/wireless/iwlwifi/dvm/tx.c

@@ -674,6 +674,51 @@ int iwlagn_tx_agg_start(struct iwl_priv *priv, struct ieee80211_vif *vif,
 	return ret;
 }
 
+int iwlagn_tx_agg_flush(struct iwl_priv *priv, struct ieee80211_vif *vif,
+			struct ieee80211_sta *sta, u16 tid)
+{
+	struct iwl_tid_data *tid_data;
+	enum iwl_agg_state agg_state;
+	int sta_id, txq_id;
+	sta_id = iwl_sta_id(sta);
+
+	/*
+	 * First set the agg state to OFF to avoid calling
+	 * ieee80211_stop_tx_ba_cb in iwlagn_check_ratid_empty.
+	 */
+	spin_lock_bh(&priv->sta_lock);
+
+	tid_data = &priv->tid_data[sta_id][tid];
+	txq_id = tid_data->agg.txq_id;
+	agg_state = tid_data->agg.state;
+	IWL_DEBUG_TX_QUEUES(priv, "Flush AGG: sta %d tid %d q %d state %d\n",
+			    sta_id, tid, txq_id, tid_data->agg.state);
+
+	tid_data->agg.state = IWL_AGG_OFF;
+
+	spin_unlock_bh(&priv->sta_lock);
+
+	if (iwlagn_txfifo_flush(priv, BIT(txq_id)))
+		IWL_ERR(priv, "Couldn't flush the AGG queue\n");
+
+	if (test_bit(txq_id, priv->agg_q_alloc)) {
+		/*
+		 * If the transport didn't know that we wanted to start
+		 * agreggation, don't tell it that we want to stop them.
+		 * This can happen when we don't get the addBA response on
+		 * time, or we hadn't time to drain the AC queues.
+		 */
+		if (agg_state == IWL_AGG_ON)
+			iwl_trans_txq_disable(priv->trans, txq_id);
+		else
+			IWL_DEBUG_TX_QUEUES(priv, "Don't disable tx agg: %d\n",
+					    agg_state);
+		iwlagn_dealloc_agg_txq(priv, txq_id);
+	}
+
+	return 0;
+}
+
 int iwlagn_tx_agg_oper(struct iwl_priv *priv, struct ieee80211_vif *vif,
 			struct ieee80211_sta *sta, u16 tid, u8 buf_size)
 {