mac80211: add an intermediate software queue implementation

This allows drivers to request per-vif and per-sta-tid queues from which
they can pull frames. This makes it easier to keep the hardware queues
short, and to improve fairness between clients and vifs.

The task of scheduling packet transmission is left up to the driver -
queueing is controlled by mac80211. Drivers can only dequeue packets by
calling ieee80211_tx_dequeue. This makes it possible to add active queue
management later without changing drivers using this code.

This can also be used as a starting point to implement A-MSDU
aggregation in a way that does not add artificially induced latency.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
[resolved minor context conflict, minor changes, endian annotations]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c
index 20522492d8cc..cce9d425c718 100644
--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -188,6 +188,43 @@ ieee80211_wake_queue_agg(struct ieee80211_sub_if_data *sdata, int tid)
 	__release(agg_queue);
 }
 
+static void
+ieee80211_agg_stop_txq(struct sta_info *sta, int tid)
+{
+	struct ieee80211_txq *txq = sta->sta.txq[tid];
+	struct txq_info *txqi;
+
+	if (!txq)
+		return;
+
+	txqi = to_txq_info(txq);
+
+	/* Lock here to protect against further seqno updates on dequeue */
+	spin_lock_bh(&txqi->queue.lock);
+	set_bit(IEEE80211_TXQ_STOP, &txqi->flags);
+	spin_unlock_bh(&txqi->queue.lock);
+}
+
+static void
+ieee80211_agg_start_txq(struct sta_info *sta, int tid, bool enable)
+{
+	struct ieee80211_txq *txq = sta->sta.txq[tid];
+	struct txq_info *txqi;
+
+	if (!txq)
+		return;
+
+	txqi = to_txq_info(txq);
+
+	if (enable)
+		set_bit(IEEE80211_TXQ_AMPDU, &txqi->flags);
+	else
+		clear_bit(IEEE80211_TXQ_AMPDU, &txqi->flags);
+
+	clear_bit(IEEE80211_TXQ_STOP, &txqi->flags);
+	drv_wake_tx_queue(sta->sdata->local, txqi);
+}
+
 /*
  * splice packets from the STA's pending to the local pending,
  * requires a call to ieee80211_agg_splice_finish later
@@ -247,6 +284,7 @@ static void ieee80211_remove_tid_tx(struct sta_info *sta, int tid)
 	ieee80211_assign_tid_tx(sta, tid, NULL);
 
 	ieee80211_agg_splice_finish(sta->sdata, tid);
+	ieee80211_agg_start_txq(sta, tid, false);
 
 	kfree_rcu(tid_tx, rcu_head);
 }
@@ -418,6 +456,8 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid)
 	 */
 	clear_bit(HT_AGG_STATE_WANT_START, &tid_tx->state);
 
+	ieee80211_agg_stop_txq(sta, tid);
+
 	/*
 	 * Make sure no packets are being processed. This ensures that
 	 * we have a valid starting sequence number and that in-flight
@@ -440,6 +480,8 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid)
 		ieee80211_agg_splice_finish(sdata, tid);
 		spin_unlock_bh(&sta->lock);
 
+		ieee80211_agg_start_txq(sta, tid, false);
+
 		kfree_rcu(tid_tx, rcu_head);
 		return;
 	}
@@ -669,6 +711,8 @@ static void ieee80211_agg_tx_operational(struct ieee80211_local *local,
 	ieee80211_agg_splice_finish(sta->sdata, tid);
 
 	spin_unlock_bh(&sta->lock);
+
+	ieee80211_agg_start_txq(sta, tid, true);
 }
 
 void ieee80211_start_tx_ba_cb(struct ieee80211_vif *vif, u8 *ra, u16 tid)