From: Felix Fietkau <nbd@nbd.name>
Date: Sun, 17 Mar 2019 14:26:59 +0100
Subject: [PATCH] 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: 89cea7493a346 ("ath9k: Switch to mac80211 TXQ scheduling and airtime APIs")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -6090,26 +6090,42 @@ static inline void ieee80211_txq_schedul
 {
 }
 
+void __ieee80211_schedule_txq(struct ieee80211_hw *hw,
+			      struct ieee80211_txq *txq, bool force);
+
 /**
  * ieee80211_schedule_txq - schedule a TXQ for transmission
  *
  * @hw: pointer as obtained from ieee80211_alloc_hw()
  * @txq: pointer obtained from station or virtual interface
  *
- * Schedules a TXQ for transmission if it is not already scheduled.
+ * Schedules a TXQ for transmission if it is not already scheduled,
+ * even if mac80211 does not have any packets buffered.
+ *
+ * The driver may call this function if it has buffered packets for
+ * this TXQ internally.
  */
-void ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq);
+static inline void
+ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq)
+{
+	__ieee80211_schedule_txq(hw, txq, true);
+}
 
 /**
  * ieee80211_return_txq - return a TXQ previously acquired by ieee80211_next_txq()
  *
  * @hw: pointer as obtained from ieee80211_alloc_hw()
  * @txq: pointer obtained from station or virtual interface
+ * @force: schedule txq even if mac80211 does not have any buffered packets.
+ *
+ * The driver may set force=true if it has buffered packets for this TXQ
+ * internally.
  */
 static inline void
-ieee80211_return_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq)
+ieee80211_return_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq,
+		     bool force)
 {
-	ieee80211_schedule_txq(hw, txq);
+	__ieee80211_schedule_txq(hw, txq, force);
 }
 
 /**
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3655,8 +3655,9 @@ out:
 }
 EXPORT_SYMBOL(ieee80211_next_txq);
 
-void ieee80211_schedule_txq(struct ieee80211_hw *hw,
-			    struct ieee80211_txq *txq)
+void __ieee80211_schedule_txq(struct ieee80211_hw *hw,
+			      struct ieee80211_txq *txq,
+			      bool force)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct txq_info *txqi = to_txq_info(txq);
@@ -3664,7 +3665,8 @@ void ieee80211_schedule_txq(struct ieee8
 	spin_lock_bh(&local->active_txq_lock[txq->ac]);
 
 	if (list_empty(&txqi->schedule_order) &&
-	    (!skb_queue_empty(&txqi->frags) || txqi->tin.backlog_packets)) {
+	    (force || !skb_queue_empty(&txqi->frags) ||
+	     txqi->tin.backlog_packets)) {
 		/* If airtime accounting is active, always enqueue STAs at the
 		 * head of the list to ensure that they only get moved to the
 		 * back by the airtime DRR scheduler once they have a negative
@@ -3684,7 +3686,7 @@ void ieee80211_schedule_txq(struct ieee8
 
 	spin_unlock_bh(&local->active_txq_lock[txq->ac]);
 }
-EXPORT_SYMBOL(ieee80211_schedule_txq);
+EXPORT_SYMBOL(__ieee80211_schedule_txq);
 
 bool ieee80211_txq_may_transmit(struct ieee80211_hw *hw,
 				struct ieee80211_txq *txq)