mac80211: Add TXQ scheduling API

This adds an API to mac80211 to handle scheduling of TXQs and changes the
interface between driver and mac80211 for TXQ handling as follows:

- The wake_tx_queue callback interface no longer includes the TXQ. Instead,
  the driver is expected to retrieve that from ieee80211_next_txq()

- Two new mac80211 functions are added: ieee80211_next_txq() and
  ieee80211_schedule_txq(). The former returns the next TXQ that should be
  scheduled, and is how the driver gets a queue to pull packets from. The
  latter is called internally by mac80211 to start scheduling a queue, and
  the driver is supposed to call it to re-schedule the TXQ after it is
  finished pulling packets from it (unless the queue emptied).

The ath9k and ath10k drivers are changed to use the new API.
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

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

@@ -2574,9 +2574,7 @@ struct ath10k *ath10k_core_create(size_t priv_size, struct device *dev,
 
 	mutex_init(&ar->conf_mutex);
 	spin_lock_init(&ar->data_lock);
-	spin_lock_init(&ar->txqs_lock);
 
-	INIT_LIST_HEAD(&ar->txqs);
 	INIT_LIST_HEAD(&ar->peers);
 	init_waitqueue_head(&ar->peer_mapping_wq);
 	init_waitqueue_head(&ar->htt.empty_tx_wq);

drivers/net/wireless/ath/ath10k/core.h

@@ -347,7 +347,6 @@ struct ath10k_peer {
 };
 
 struct ath10k_txq {
-	struct list_head list;
 	unsigned long num_fw_queued;
 	unsigned long num_push_allowed;
 };
@@ -895,10 +894,7 @@ struct ath10k {
 
 	/* protects shared structure data */
 	spinlock_t data_lock;
-	/* protects: ar->txqs, artxq->list */
-	spinlock_t txqs_lock;
 
-	struct list_head txqs;
 	struct list_head arvifs;
 	struct list_head peers;
 	struct ath10k_peer *peer_map[ATH10K_MAX_NUM_PEER_IDS];

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

@@ -3830,12 +3830,10 @@ static void ath10k_mac_txq_init(struct ieee80211_txq *txq)
 		return;
 
 	artxq = (void *)txq->drv_priv;
-	INIT_LIST_HEAD(&artxq->list);
 }
 
 static void ath10k_mac_txq_unref(struct ath10k *ar, struct ieee80211_txq *txq)
 {
-	struct ath10k_txq *artxq;
 	struct ath10k_skb_cb *cb;
 	struct sk_buff *msdu;
 	int msdu_id;
@@ -3843,12 +3841,6 @@ static void ath10k_mac_txq_unref(struct ath10k *ar, struct ieee80211_txq *txq)
 	if (!txq)
 		return;
 
-	artxq = (void *)txq->drv_priv;
-	spin_lock_bh(&ar->txqs_lock);
-	if (!list_empty(&artxq->list))
-		list_del_init(&artxq->list);
-	spin_unlock_bh(&ar->txqs_lock);
-
 	spin_lock_bh(&ar->htt.tx_lock);
 	idr_for_each_entry(&ar->htt.pending_tx, msdu, msdu_id) {
 		cb = ATH10K_SKB_CB(msdu);
@@ -3978,23 +3970,17 @@ int ath10k_mac_tx_push_txq(struct ieee80211_hw *hw,
 void ath10k_mac_tx_push_pending(struct ath10k *ar)
 {
 	struct ieee80211_hw *hw = ar->hw;
-	struct ieee80211_txq *txq;
-	struct ath10k_txq *artxq;
-	struct ath10k_txq *last;
+	struct ieee80211_txq *txq, *first = NULL;
 	int ret;
 	int max;
 
 	if (ar->htt.num_pending_tx >= (ar->htt.max_num_pending_tx / 2))
 		return;
 
-	spin_lock_bh(&ar->txqs_lock);
 	rcu_read_lock();
 
-	last = list_last_entry(&ar->txqs, struct ath10k_txq, list);
-	while (!list_empty(&ar->txqs)) {
-		artxq = list_first_entry(&ar->txqs, struct ath10k_txq, list);
-		txq = container_of((void *)artxq, struct ieee80211_txq,
-				   drv_priv);
+	txq = ieee80211_next_txq(hw);
+	while (txq) {
 
 		/* Prevent aggressive sta/tid taking over tx queue */
 		max = 16;
@@ -4005,18 +3991,21 @@ void ath10k_mac_tx_push_pending(struct ath10k *ar)
 				break;
 		}
 
-		list_del_init(&artxq->list);
 		if (ret != -ENOENT)
-			list_add_tail(&artxq->list, &ar->txqs);
+			ieee80211_schedule_txq(hw, txq);
 
 		ath10k_htt_tx_txq_update(hw, txq);
 
-		if (artxq == last || (ret < 0 && ret != -ENOENT))
+		if (first == txq || (ret < 0 && ret != -ENOENT))
 			break;
+
+		if (!first)
+			first = txq;
+
+		txq = ieee80211_next_txq(hw);
 	}
 
 	rcu_read_unlock();
-	spin_unlock_bh(&ar->txqs_lock);
 }
 
 /************/
@@ -4250,34 +4239,22 @@ static void ath10k_mac_op_tx(struct ieee80211_hw *hw,
 	}
 }
 
-static void ath10k_mac_op_wake_tx_queue(struct ieee80211_hw *hw,
-					struct ieee80211_txq *txq)
+static void ath10k_mac_op_wake_tx_queue(struct ieee80211_hw *hw)
 {
-	struct ath10k *ar = hw->priv;
-	struct ath10k_txq *artxq = (void *)txq->drv_priv;
-	struct ieee80211_txq *f_txq;
-	struct ath10k_txq *f_artxq;
+	struct ieee80211_txq *txq;
 	int ret = 0;
 	int max = 16;
 
-	spin_lock_bh(&ar->txqs_lock);
-	if (list_empty(&artxq->list))
-		list_add_tail(&artxq->list, &ar->txqs);
-
-	f_artxq = list_first_entry(&ar->txqs, struct ath10k_txq, list);
-	f_txq = container_of((void *)f_artxq, struct ieee80211_txq, drv_priv);
-	list_del_init(&f_artxq->list);
+	txq = ieee80211_next_txq(hw);
 
-	while (ath10k_mac_tx_can_push(hw, f_txq) && max--) {
-		ret = ath10k_mac_tx_push_txq(hw, f_txq);
+	while (ath10k_mac_tx_can_push(hw, txq) && max--) {
+		ret = ath10k_mac_tx_push_txq(hw, txq);
 		if (ret)
 			break;
 	}
 	if (ret != -ENOENT)
-		list_add_tail(&f_artxq->list, &ar->txqs);
-	spin_unlock_bh(&ar->txqs_lock);
+		ieee80211_schedule_txq(hw, txq);
 
-	ath10k_htt_tx_txq_update(hw, f_txq);
 	ath10k_htt_tx_txq_update(hw, txq);
 }
 

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -246,12 +246,8 @@ struct ath_atx_tid {
 	s8 bar_index;
 	bool active;
 	bool clear_ps_filter;
-	bool has_queued;
 };
 
-void __ath_tx_queue_tid(struct ath_softc *sc, struct ath_atx_tid *tid);
-void ath_tx_queue_tid(struct ath_softc *sc, struct ath_atx_tid *tid);
-
 struct ath_node {
 	struct ath_softc *sc;
 	struct ieee80211_sta *sta; /* station struct we're part of */
@@ -591,8 +587,7 @@ bool ath_drain_all_txq(struct ath_softc *sc);
 void ath_draintxq(struct ath_softc *sc, struct ath_txq *txq);
 void ath_tx_node_init(struct ath_softc *sc, struct ath_node *an);
 void ath_tx_node_cleanup(struct ath_softc *sc, struct ath_node *an);
-void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq);
-void ath_txq_schedule_all(struct ath_softc *sc);
+void ath_txq_schedule(struct ath_softc *sc);
 int ath_tx_init(struct ath_softc *sc, int nbufs);
 int ath_txq_update(struct ath_softc *sc, int qnum,
 		   struct ath9k_tx_queue_info *q);
@@ -618,7 +613,7 @@ void ath9k_release_buffered_frames(struct ieee80211_hw *hw,
 				   u16 tids, int nframes,
 				   enum ieee80211_frame_release_type reason,
 				   bool more_data);
-void ath9k_wake_tx_queue(struct ieee80211_hw *hw, struct ieee80211_txq *queue);
+void ath9k_wake_tx_queue(struct ieee80211_hw *hw);
 
 /********/
 /* VIFs */

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

@@ -266,7 +266,7 @@ static bool ath_complete_reset(struct ath_softc *sc, bool start)
 		}
 	work:
 		ath_restart_work(sc);
-		ath_txq_schedule_all(sc);
+		ath_txq_schedule(sc);
 	}
 
 	sc->gtt_cnt = 0;

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

@@ -1057,8 +1057,6 @@ static void ath_rx_count_airtime(struct ath_softc *sc,
  	if (!!(sc->airtime_flags & AIRTIME_USE_RX)) {
 		spin_lock_bh(&acq->lock);
 		an->airtime_deficit[acno] -= airtime;
-		if (an->airtime_deficit[acno] <= 0)
-			__ath_tx_queue_tid(sc, ATH_AN_2_TID(an, tidno));
 		spin_unlock_bh(&acq->lock);
 	}
 	ath_debug_airtime(sc, an, airtime, 0);

include/net/mac80211.h

@@ -105,9 +105,12 @@
  * The driver is expected to initialize its private per-queue data for stations
  * and interfaces in the .add_interface and .sta_add ops.
  *
- * The driver can't access the queue directly. To dequeue a frame, it calls
- * ieee80211_tx_dequeue(). Whenever mac80211 adds a new frame to a queue, it
- * calls the .wake_tx_queue driver op.
+ * The driver can't access the queue directly. To obtain the next queue to pull
+ * frames from, the driver calls ieee80211_next_txq(). To dequeue a frame from a
+ * txq, it calls ieee80211_tx_dequeue(). Whenever mac80211 adds a new frame to a
+ * queue, it calls the .wake_tx_queue driver op. The driver is expected to
+ * re-schedule the txq using ieee80211_schedule_txq() if it is still active
+ * after the driver has finished pulling packets from it.
  *
  * For AP powersave TIM handling, the driver only needs to indicate if it has
  * buffered packets in the driver specific data structures by calling
@@ -3731,8 +3734,7 @@ struct ieee80211_ops {
 					 struct ieee80211_vif *vif,
 					 struct ieee80211_tdls_ch_sw_params *params);
 
-	void (*wake_tx_queue)(struct ieee80211_hw *hw,
-			      struct ieee80211_txq *txq);
+	void (*wake_tx_queue)(struct ieee80211_hw *hw);
 	void (*sync_rx_queues)(struct ieee80211_hw *hw);
 
 	int (*start_nan)(struct ieee80211_hw *hw,
@@ -5883,13 +5885,36 @@ void ieee80211_unreserve_tid(struct ieee80211_sta *sta, u8 tid);
  * ieee80211_tx_dequeue - dequeue a packet from a software tx queue
  *
  * @hw: pointer as obtained from ieee80211_alloc_hw()
- * @txq: pointer obtained from station or virtual interface
+ * @txq: pointer obtained from ieee80211_next_txq()
  *
  * Returns the skb if successful, %NULL if no frame was available.
  */
 struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
 				     struct ieee80211_txq *txq);
 
+/**
+ * ieee80211_schedule_txq - add txq to scheduling loop
+ *
+ * @hw: pointer as obtained from ieee80211_alloc_hw()
+ * @txq: pointer obtained from station or virtual interface
+ *
+ * Returns %true if the txq was actually added to the scheduling,
+ * %false otherwise.
+ */
+bool ieee80211_schedule_txq(struct ieee80211_hw *hw,
+			    struct ieee80211_txq *txq);
+
+/**
+ * ieee80211_next_txq - get next tx queue to pull packets from
+ *
+ * @hw: pointer as obtained from ieee80211_alloc_hw()
+ *
+ * Returns the next txq if successful, %NULL if no queue is eligible. If a txq
+ * is returned, it will have been removed from the scheduler queue and needs to
+ * be re-scheduled with ieee80211_schedule_txq() to continue to be active.
+ */
+struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw);
+
 /**
  * ieee80211_txq_get_depth - get pending frame/byte count of given txq
  *

net/mac80211/agg-tx.c

@@ -226,9 +226,13 @@ ieee80211_agg_start_txq(struct sta_info *sta, int tid, bool enable)
 		clear_bit(IEEE80211_TXQ_AMPDU, &txqi->flags);
 
 	clear_bit(IEEE80211_TXQ_STOP, &txqi->flags);
+
+	if (!ieee80211_schedule_txq(&sta->sdata->local->hw, txq))
+		return;
+
 	local_bh_disable();
 	rcu_read_lock();
-	drv_wake_tx_queue(sta->sdata->local, txqi);
+	drv_wake_tx_queue(sta->sdata->local);
 	rcu_read_unlock();
 	local_bh_enable();
 }

net/mac80211/driver-ops.h

@@ -1158,16 +1158,10 @@ drv_tdls_recv_channel_switch(struct ieee80211_local *local,
 	trace_drv_return_void(local);
 }
 
-static inline void drv_wake_tx_queue(struct ieee80211_local *local,
-				     struct txq_info *txq)
+static inline void drv_wake_tx_queue(struct ieee80211_local *local)
 {
-	struct ieee80211_sub_if_data *sdata = vif_to_sdata(txq->txq.vif);
-
-	if (!check_sdata_in_driver(sdata))
-		return;
-
-	trace_drv_wake_tx_queue(local, sdata, txq);
-	local->ops->wake_tx_queue(&local->hw, &txq->txq);
+	trace_drv_wake_tx_queue(local);
+	local->ops->wake_tx_queue(&local->hw);
 }
 
 static inline int drv_start_nan(struct ieee80211_local *local,

net/mac80211/ieee80211_i.h

@@ -832,6 +832,7 @@ struct txq_info {
 	struct codel_vars def_cvars;
 	struct codel_stats cstats;
 	struct sk_buff_head frags;
+	struct list_head schedule_order;
 	unsigned long flags;
 
 	/* keep last! */
@@ -1122,6 +1123,10 @@ struct ieee80211_local {
 	struct codel_vars *cvars;
 	struct codel_params cparams;
 
+	/* protects active_txqs and txqi->schedule_order */
+	spinlock_t active_txq_lock;
+	struct list_head active_txqs;
+
 	const struct ieee80211_ops *ops;
 
 	/*

net/mac80211/main.c

@@ -619,6 +619,9 @@ struct ieee80211_hw *ieee80211_alloc_hw_nm(size_t priv_data_len,
 	spin_lock_init(&local->rx_path_lock);
 	spin_lock_init(&local->queue_stop_reason_lock);
 
+	INIT_LIST_HEAD(&local->active_txqs);
+	spin_lock_init(&local->active_txq_lock);
+
 	INIT_LIST_HEAD(&local->chanctx_list);
 	mutex_init(&local->chanctx_mtx);
 

net/mac80211/sta_info.c

@@ -1237,12 +1237,17 @@ void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
 		drv_sta_notify(local, sdata, STA_NOTIFY_AWAKE, &sta->sta);
 
 	if (sta->sta.txq[0]) {
+		bool wake = false;
+
 		for (i = 0; i < ARRAY_SIZE(sta->sta.txq); i++) {
 			if (!txq_has_queue(sta->sta.txq[i]))
 				continue;
 
-			drv_wake_tx_queue(local, to_txq_info(sta->sta.txq[i]));
+			if (ieee80211_schedule_txq(&local->hw, sta->sta.txq[i]))
+				wake = true;
 		}
+		if (wake)
+			drv_wake_tx_queue(local);
 	}
 
 	skb_queue_head_init(&pending);

net/mac80211/trace.h

@@ -2550,35 +2550,9 @@ TRACE_EVENT(drv_tdls_recv_channel_switch,
 	)
 );
 
-TRACE_EVENT(drv_wake_tx_queue,
-	TP_PROTO(struct ieee80211_local *local,
-		 struct ieee80211_sub_if_data *sdata,
-		 struct txq_info *txq),
-
-	TP_ARGS(local, sdata, txq),
-
-	TP_STRUCT__entry(
-		LOCAL_ENTRY
-		VIF_ENTRY
-		STA_ENTRY
-		__field(u8, ac)
-		__field(u8, tid)
-	),
-
-	TP_fast_assign(
-		struct ieee80211_sta *sta = txq->txq.sta;
-
-		LOCAL_ASSIGN;
-		VIF_ASSIGN;
-		STA_ASSIGN;
-		__entry->ac = txq->txq.ac;
-		__entry->tid = txq->txq.tid;
-	),
-
-	TP_printk(
-		LOCAL_PR_FMT  VIF_PR_FMT  STA_PR_FMT " ac:%d tid:%d",
-		LOCAL_PR_ARG, VIF_PR_ARG, STA_PR_ARG, __entry->ac, __entry->tid
-	)
+DEFINE_EVENT(local_only_evt, drv_wake_tx_queue,
+	     TP_PROTO(struct ieee80211_local *local),
+	     TP_ARGS(local)
 );
 
 #endif /* !__MAC80211_DRIVER_TRACE || TRACE_HEADER_MULTI_READ */

net/mac80211/tx.c

@@ -1439,6 +1439,7 @@ void ieee80211_txq_init(struct ieee80211_sub_if_data *sdata,
 	codel_vars_init(&txqi->def_cvars);
 	codel_stats_init(&txqi->cstats);
 	__skb_queue_head_init(&txqi->frags);
+	INIT_LIST_HEAD(&txqi->schedule_order);
 
 	txqi->txq.vif = &sdata->vif;
 
@@ -1462,6 +1463,7 @@ void ieee80211_txq_purge(struct ieee80211_local *local,
 
 	fq_tin_reset(fq, tin, fq_skb_free_func);
 	ieee80211_purge_tx_queue(&local->hw, &txqi->frags);
+	list_del_init(&txqi->schedule_order);
 }
 
 int ieee80211_txq_setup_flows(struct ieee80211_local *local)
@@ -1558,7 +1560,8 @@ static bool ieee80211_queue_skb(struct ieee80211_local *local,
 	ieee80211_txq_enqueue(local, txqi, skb);
 	spin_unlock_bh(&fq->lock);
 
-	drv_wake_tx_queue(local, txqi);
+	if (ieee80211_schedule_txq(&local->hw, &txqi->txq))
+		drv_wake_tx_queue(local);
 
 	return true;
 }
@@ -3553,6 +3556,50 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
 }
 EXPORT_SYMBOL(ieee80211_tx_dequeue);
 
+bool ieee80211_schedule_txq(struct ieee80211_hw *hw,
+			    struct ieee80211_txq *txq)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct txq_info *txqi = to_txq_info(txq);
+	bool ret = false;
+
+	spin_lock_bh(&local->active_txq_lock);
+
+	if (list_empty(&txqi->schedule_order)) {
+		list_add_tail(&txqi->schedule_order, &local->active_txqs);
+		ret = true;
+	}
+
+	spin_unlock_bh(&local->active_txq_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(ieee80211_schedule_txq);
+
+struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw)
+{
+	struct ieee80211_local *local = hw_to_local(hw);
+	struct txq_info *txqi = NULL;
+
+	spin_lock_bh(&local->active_txq_lock);
+
+	if (list_empty(&local->active_txqs))
+		goto out;
+
+	txqi = list_first_entry(&local->active_txqs,
+				struct txq_info, schedule_order);
+	list_del_init(&txqi->schedule_order);
+
+out:
+	spin_unlock_bh(&local->active_txq_lock);
+
+	if (!txqi)
+		return NULL;
+
+	return &txqi->txq;
+}
+EXPORT_SYMBOL(ieee80211_next_txq);
+
 void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 				  struct net_device *dev,
 				  u32 info_flags)