iwlwifi: mvm: Send non offchannel traffic via AP sta

TDLS discovery response frame is a unicast direct frame to the peer.
Since we don't have a STA for this peer, this frame goes through
iwl_tx_skb_non_sta(). As the result aux_sta and some completely
arbitrary queue would be selected for this frame, resulting in a queue
hang.  Fix that by sending such frames through AP sta instead.
Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c

@@ -809,6 +809,21 @@ static void iwl_mvm_mac_tx(struct ieee80211_hw *hw,
 	    !ieee80211_is_bufferable_mmpdu(hdr->frame_control))
 		sta = NULL;
 
+	/* If there is no sta, and it's not offchannel - send through AP */
+	if (info->control.vif->type == NL80211_IFTYPE_STATION &&
+	    info->hw_queue != IWL_MVM_OFFCHANNEL_QUEUE && !sta) {
+		struct iwl_mvm_vif *mvmvif =
+			iwl_mvm_vif_from_mac80211(info->control.vif);
+		u8 ap_sta_id = READ_ONCE(mvmvif->ap_sta_id);
+
+		if (ap_sta_id < IWL_MVM_STATION_COUNT) {
+			/* mac80211 holds rcu read lock */
+			sta = rcu_dereference(mvm->fw_id_to_mac_id[ap_sta_id]);
+			if (IS_ERR_OR_NULL(sta))
+				goto drop;
+		}
+	}
+
 	if (sta) {
 		if (iwl_mvm_defer_tx(mvm, sta, skb))
 			return;