ath9k: use software queueing for multicast traffic

Create a per-vif dummy node entry for keeping the multicast software
queues. This helps in setups with a lot of mulitcast traffic that could
otherwise potentially drown out unicast traffic to stations.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 252497a..911744f 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -963,6 +963,8 @@
 	struct ath_softc *sc = hw->priv;
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath_common *common = ath9k_hw_common(ah);
+	struct ath_vif *avp = (void *)vif->drv_priv;
+	struct ath_node *an = &avp->mcast_node;
 
 	mutex_lock(&sc->mutex);
 
@@ -976,6 +978,12 @@
 	if (ath9k_uses_beacons(vif->type))
 		ath9k_beacon_assign_slot(sc, vif);
 
+	an->sc = sc;
+	an->sta = NULL;
+	an->vif = vif;
+	an->no_ps_filter = true;
+	ath_tx_node_init(sc, an);
+
 	mutex_unlock(&sc->mutex);
 	return 0;
 }
@@ -1013,6 +1021,7 @@
 {
 	struct ath_softc *sc = hw->priv;
 	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
+	struct ath_vif *avp = (void *)vif->drv_priv;
 
 	ath_dbg(common, CONFIG, "Detach Interface\n");
 
@@ -1027,6 +1036,8 @@
 	ath9k_calculate_summary_state(hw, NULL);
 	ath9k_ps_restore(sc);
 
+	ath_tx_node_cleanup(sc, &avp->mcast_node);
+
 	mutex_unlock(&sc->mutex);
 }