mac80211: make ieee80211_schedule_txq schedule empty TXQs

Currently there is no way for the driver to signal to mac80211 that it should
schedule a TXQ even if there are no packets on the mac80211 part of that queue.
This is problematic if the driver has an internal retry queue to deal with
software A-MPDU retry.

This patch changes the behavior of ieee80211_schedule_txq to always schedule
the queue, as its only user (ath9k) seems to expect such behavior already:
it calls this function on tx status and on powersave wakeup whenever its
internal retry queue is not empty.

Also add an extra argument to ieee80211_return_txq to get the same behavior.

This fixes an issue on ath9k where tx queues with packets to retry (and no
new packets in mac80211) would not get serviced.

Fixes: 89cea7493a ("ath9k: Switch to mac80211 TXQ scheduling and airtime APIs")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/ath/ath10k/htt_rx.c

@@ -2728,7 +2728,7 @@ static void ath10k_htt_rx_tx_fetch_ind(struct ath10k *ar, struct sk_buff *skb)
 			num_msdus++;
 			num_bytes += ret;
 		}
-		ieee80211_return_txq(hw, txq);
+		ieee80211_return_txq(hw, txq, false);
 		ieee80211_txq_schedule_end(hw, txq->ac);
 
 		record->num_msdus = cpu_to_le16(num_msdus);

drivers/net/wireless/ath/ath10k/mac.c

@@ -4089,7 +4089,7 @@ static int ath10k_mac_schedule_txq(struct ieee80211_hw *hw, u32 ac)
 			if (ret < 0)
 				break;
 		}
-		ieee80211_return_txq(hw, txq);
+		ieee80211_return_txq(hw, txq, false);
 		ath10k_htt_tx_txq_update(hw, txq);
 		if (ret == -EBUSY)
 			break;
@@ -4374,7 +4374,7 @@ static void ath10k_mac_op_wake_tx_queue(struct ieee80211_hw *hw,
 		if (ret < 0)
 			break;
 	}
-	ieee80211_return_txq(hw, txq);
+	ieee80211_return_txq(hw, txq, false);
 	ath10k_htt_tx_txq_update(hw, txq);
 out:
 	ieee80211_txq_schedule_end(hw, ac);

drivers/net/wireless/ath/ath9k/xmit.c

@@ -1938,12 +1938,15 @@ void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq)
 		goto out;
 
 	while ((queue = ieee80211_next_txq(hw, txq->mac80211_qnum))) {
+		bool force;
+
 		tid = (struct ath_atx_tid *)queue->drv_priv;
 
 		ret = ath_tx_sched_aggr(sc, txq, tid);
 		ath_dbg(common, QUEUE, "ath_tx_sched_aggr returned %d\n", ret);
 
-		ieee80211_return_txq(hw, queue);
+		force = !skb_queue_empty(&tid->retry_q);
+		ieee80211_return_txq(hw, queue, force);
 	}
 
 out: