[PATCH v2] mac80211: make ieee80211_schedule_txq schedule empty TXQs

[PATCH v2] mac80211: make ieee80211_schedule_txq schedule empty TXQs

[Felix Fietkau]

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

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 include/net/mac80211.h | 17 ++++++++++++++---
 net/mac80211/tx.c      | 10 ++++++----
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 0de0aba580eb..630941e5a20e 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -6291,15 +6291,26 @@ static inline void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac)
 {
 }
 
+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()
@@ -6310,7 +6321,7 @@ void ieee80211_schedule_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq);
 static inline void
 ieee80211_return_txq(struct ieee80211_hw *hw, struct ieee80211_txq *txq)
 {
-	ieee80211_schedule_txq(hw, txq);
+	__ieee80211_schedule_txq(hw, txq, false);
 }
 
 /**
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index f85344c9af62..72279fb318e0 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3706,8 +3706,9 @@ struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw, u8 ac)
 }
 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);
@@ -3715,7 +3716,8 @@ void ieee80211_schedule_txq(struct ieee80211_hw *hw,
 	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
@@ -3735,7 +3737,7 @@ void ieee80211_schedule_txq(struct ieee80211_hw *hw,
 
 	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)
-- 
2.17.0

Re: [PATCH v2] mac80211: make ieee80211_schedule_txq schedule empty TXQs

[Toke Høiland-Jørgensen]

Felix Fietkau <nbd@nbd.name> writes:

> 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
>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  include/net/mac80211.h | 17 ++++++++++++++---
>  net/mac80211/tx.c      | 10 ++++++----
>  2 files changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
> index 0de0aba580eb..630941e5a20e 100644
> --- a/include/net/mac80211.h
> +++ b/include/net/mac80211.h
> @@ -6291,15 +6291,26 @@ static inline void ieee80211_txq_schedule_end(struct ieee80211_hw *hw, u8 ac)
>  {
>  }
>  
> +void __ieee80211_schedule_txq(struct ieee80211_hw *hw,
> +			      struct ieee80211_txq *txq, bool force);
> +

So are you planning to also change return_txq() to take the 'force'
argument and wrap __ieee80211_schedule_txq()? Since that was the context
we originally started discussing this :)

-Toke