staging: wfx: change the way to choose frame to send

The current code computes itself the QoS policy to choose which frame
should be sent. However, firmware already do that job. Firmware would
prefer to have packets in every queues and be able to choose itself
which queue to use.

So, this patch sort the queues from the emptiest to the fulliest (thanks
to the pending frames counter introduced a few commits earlier). It send
frame to the least full queue.

However, we continue to be careful with frames that have to be sent
after a dtim ("cab": Content After (DTIM) Beacon).

So, this patch splits AC queues in two skb_queues: one for normal frames
and another for cab frames. It cares to send frames from CAB skb_queue
if appropriate.
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200401110405.80282-23-Jerome.Pouiller@silabs.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wfx/queue.c

@@ -83,13 +83,20 @@ void wfx_tx_queues_wait_empty_vif(struct wfx_vif *wvif)
 		wfx_tx_lock_flush(wdev);
 		for (i = 0; i < IEEE80211_NUM_ACS && done; ++i) {
 			queue = &wdev->tx_queue[i];
-			spin_lock_bh(&queue->queue.lock);
-			skb_queue_walk(&queue->queue, item) {
-				hif = (struct hif_msg *) item->data;
+			spin_lock_bh(&queue->normal.lock);
+			skb_queue_walk(&queue->normal, item) {
+				hif = (struct hif_msg *)item->data;
 				if (hif->interface == wvif->id)
 					done = false;
 			}
-			spin_unlock_bh(&queue->queue.lock);
+			spin_unlock_bh(&queue->normal.lock);
+			spin_lock_bh(&queue->cab.lock);
+			skb_queue_walk(&queue->cab, item) {
+				hif = (struct hif_msg *)item->data;
+				if (hif->interface == wvif->id)
+					done = false;
+			}
+			spin_unlock_bh(&queue->cab.lock);
 		}
 		if (!done) {
 			wfx_tx_unlock(wdev);
@@ -103,7 +110,9 @@ static void wfx_tx_queue_clear(struct wfx_dev *wdev, struct wfx_queue *queue,
 {
 	struct sk_buff *item;
 
-	while ((item = skb_dequeue(&queue->queue)) != NULL)
+	while ((item = skb_dequeue(&queue->normal)) != NULL)
+		skb_queue_head(gc_list, item);
+	while ((item = skb_dequeue(&queue->cab)) != NULL)
 		skb_queue_head(gc_list, item);
 }
 
@@ -131,8 +140,10 @@ void wfx_tx_queues_init(struct wfx_dev *wdev)
 	skb_queue_head_init(&wdev->tx_queue_stats.pending);
 	init_waitqueue_head(&wdev->tx_queue_stats.wait_link_id_empty);
 
-	for (i = 0; i < IEEE80211_NUM_ACS; ++i)
-		skb_queue_head_init(&wdev->tx_queue[i].queue);
+	for (i = 0; i < IEEE80211_NUM_ACS; ++i) {
+		skb_queue_head_init(&wdev->tx_queue[i].normal);
+		skb_queue_head_init(&wdev->tx_queue[i].cab);
+	}
 }
 
 void wfx_tx_queues_deinit(struct wfx_dev *wdev)
@@ -141,57 +152,15 @@ void wfx_tx_queues_deinit(struct wfx_dev *wdev)
 	wfx_tx_queues_clear(wdev);
 }
 
-int wfx_tx_queue_get_num_queued(struct wfx_queue *queue)
-{
-	struct ieee80211_tx_info *tx_info;
-	struct sk_buff *skb;
-	int ret = 0;
-
-	spin_lock_bh(&queue->queue.lock);
-	skb_queue_walk(&queue->queue, skb) {
-		tx_info = IEEE80211_SKB_CB(skb);
-		if (!(tx_info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM))
-			ret++;
-	}
-	spin_unlock_bh(&queue->queue.lock);
-	return ret;
-}
-
 void wfx_tx_queue_put(struct wfx_dev *wdev, struct wfx_queue *queue,
 		      struct sk_buff *skb)
 {
-	skb_queue_tail(&queue->queue, skb);
-}
-
-static struct sk_buff *wfx_tx_queue_get(struct wfx_dev *wdev,
-					struct wfx_queue *queue,
-					bool mcast)
-{
-	struct wfx_queue_stats *stats = &wdev->tx_queue_stats;
-	struct ieee80211_tx_info *tx_info;
-	struct sk_buff *item, *skb = NULL;
-	struct wfx_tx_priv *tx_priv;
+	struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb);
 
-	spin_lock_bh(&queue->queue.lock);
-	skb_queue_walk(&queue->queue, item) {
-		tx_info = IEEE80211_SKB_CB(item);
-		if (mcast == !!(tx_info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM)) {
-			skb = item;
-			break;
-		}
-	}
-	spin_unlock_bh(&queue->queue.lock);
-	if (skb) {
-		skb_unlink(skb, &queue->queue);
-		atomic_inc(&queue->pending_frames);
-		tx_priv = wfx_skb_tx_priv(skb);
-		tx_priv->xmit_timestamp = ktime_get();
-		skb_queue_tail(&stats->pending, skb);
-		if (skb_queue_empty(&queue->queue))
-			wake_up(&stats->wait_link_id_empty);
-		return skb;
-	}
-	return skb;
+	if (tx_info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM)
+		skb_queue_tail(&queue->cab, skb);
+	else
+		skb_queue_tail(&queue->normal, skb);
 }
 
 int wfx_pending_requeue(struct wfx_dev *wdev, struct sk_buff *skb)
@@ -204,7 +173,7 @@ int wfx_pending_requeue(struct wfx_dev *wdev, struct sk_buff *skb)
 
 	atomic_dec(&queue->pending_frames);
 	skb_unlink(skb, &stats->pending);
-	skb_queue_tail(&queue->queue, skb);
+	wfx_tx_queue_put(wdev, queue, skb);
 	return 0;
 }
 
@@ -282,20 +251,15 @@ unsigned int wfx_pending_get_pkt_us_delay(struct wfx_dev *wdev,
 bool wfx_tx_queues_has_cab(struct wfx_vif *wvif)
 {
 	struct wfx_dev *wdev = wvif->wdev;
-	struct ieee80211_tx_info *tx_info;
-	struct hif_msg *hif;
-	struct sk_buff *skb;
 	int i;
 
-	for (i = 0; i < IEEE80211_NUM_ACS; ++i) {
-		skb_queue_walk(&wdev->tx_queue[i].queue, skb) {
-			tx_info = IEEE80211_SKB_CB(skb);
-			hif = (struct hif_msg *)skb->data;
-			if ((tx_info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM) &&
-			    (hif->interface == wvif->id))
+	if (wvif->vif->type != NL80211_IFTYPE_AP)
+		return false;
+	for (i = 0; i < IEEE80211_NUM_ACS; ++i)
+		// Note: since only AP can have mcast frames in queue and only
+		// one vif can be AP, all queued frames has same interface id
+		if (!skb_queue_empty_lockless(&wdev->tx_queue[i].cab))
 			return true;
-		}
-	}
 	return false;
 }
 
@@ -304,7 +268,8 @@ bool wfx_tx_queues_empty(struct wfx_dev *wdev)
 	int i;
 
 	for (i = 0; i < IEEE80211_NUM_ACS; i++)
-		if (!skb_queue_empty_lockless(&wdev->tx_queue[i].queue))
+		if (!skb_queue_empty_lockless(&wdev->tx_queue[i].normal) ||
+		    !skb_queue_empty_lockless(&wdev->tx_queue[i].cab))
 			return false;
 	return true;
 }
@@ -350,95 +315,76 @@ static bool wfx_handle_tx_data(struct wfx_dev *wdev, struct sk_buff *skb)
 	}
 }
 
-static struct wfx_queue *wfx_tx_queue_mask_get(struct wfx_vif *wvif)
+static struct sk_buff *wfx_tx_queues_get_skb(struct wfx_dev *wdev)
 {
-	const struct ieee80211_tx_queue_params *edca;
-	unsigned int score, best = -1;
-	int winner = -1;
-	int i;
-
-	/* search for a winner using edca params */
-	for (i = 0; i < IEEE80211_NUM_ACS; ++i) {
-		int queued;
-
-		edca = &wvif->edca_params[i];
-		queued = wfx_tx_queue_get_num_queued(&wvif->wdev->tx_queue[i]);
-		if (!queued)
-			continue;
-		score = ((edca->aifs + edca->cw_min) << 16) +
-			((edca->cw_max - edca->cw_min) *
-			 (get_random_int() & 0xFFFF));
-		if (score < best && (winner < 0 || i != 3)) {
-			best = score;
-			winner = i;
-		}
-	}
-
-	if (winner < 0)
-		return NULL;
-	return &wvif->wdev->tx_queue[winner];
-}
-
-struct hif_msg *wfx_tx_queues_get(struct wfx_dev *wdev)
-{
-	struct sk_buff *skb;
-	struct hif_msg *hif = NULL;
-	struct wfx_queue *queue = NULL;
-	struct wfx_queue *vif_queue = NULL;
+	struct wfx_queue *sorted_queues[IEEE80211_NUM_ACS];
 	struct wfx_vif *wvif;
-	int i;
-
-	if (atomic_read(&wdev->tx_lock))
-		return NULL;
-
+	struct hif_msg *hif;
+	struct sk_buff *skb;
+	int i, j;
+
+	// bubble sort
+	for (i = 0; i < IEEE80211_NUM_ACS; i++) {
+		sorted_queues[i] = &wdev->tx_queue[i];
+		for (j = i; j > 0; j--)
+			if (atomic_read(&sorted_queues[j]->pending_frames) >
+			    atomic_read(&sorted_queues[j - 1]->pending_frames))
+				swap(sorted_queues[j - 1], sorted_queues[j]);
+	}
 	wvif = NULL;
 	while ((wvif = wvif_iterate(wdev, wvif)) != NULL) {
-		if (wvif->after_dtim_tx_allowed) {
-			for (i = 0; i < IEEE80211_NUM_ACS; ++i) {
-				skb = wfx_tx_queue_get(wvif->wdev,
-						       &wdev->tx_queue[i],
-						       true);
-				if (skb) {
+		if (!wvif->after_dtim_tx_allowed)
+			continue;
+		for (i = 0; i < IEEE80211_NUM_ACS; i++) {
+			skb = skb_dequeue(&sorted_queues[i]->cab);
+			if (!skb)
+				continue;
+			// Note: since only AP can have mcast frames in queue
+			// and only one vif can be AP, all queued frames has
+			// same interface id
 			hif = (struct hif_msg *)skb->data;
-					// Cannot happen since only one vif can
-					// be AP at time
-					WARN_ON(wvif->id != hif->interface);
-					return hif;
-				}
+			WARN_ON(hif->interface != wvif->id);
+			WARN_ON(sorted_queues[i] !=
+				&wdev->tx_queue[skb_get_queue_mapping(skb)]);
+			atomic_inc(&sorted_queues[i]->pending_frames);
+			return skb;
 		}
 		// No more multicast to sent
 		wvif->after_dtim_tx_allowed = false;
 		schedule_work(&wvif->update_tim_work);
 	}
-	}
-
-	for (;;) {
-		int ret = -ENOENT;
-		int queue_num;
-
-		wvif = NULL;
-		while ((wvif = wvif_iterate(wdev, wvif)) != NULL) {
-			vif_queue = wfx_tx_queue_mask_get(wvif);
-			if (vif_queue) {
-				if (queue && queue != vif_queue)
-					dev_info(wdev->dev, "vifs disagree about queue priority\n");
-				queue = vif_queue;
-				ret = 0;
+	for (i = 0; i < IEEE80211_NUM_ACS; i++) {
+		skb = skb_dequeue(&sorted_queues[i]->normal);
+		if (skb) {
+			WARN_ON(sorted_queues[i] !=
+				&wdev->tx_queue[skb_get_queue_mapping(skb)]);
+			atomic_inc(&sorted_queues[i]->pending_frames);
+			return skb;
 		}
 	}
-
-		if (ret)
 	return NULL;
+}
+
+struct hif_msg *wfx_tx_queues_get(struct wfx_dev *wdev)
+{
+	struct wfx_tx_priv *tx_priv;
+	struct sk_buff *skb;
 
-		queue_num = queue - wdev->tx_queue;
+	if (atomic_read(&wdev->tx_lock))
+		return NULL;
 
-		skb = wfx_tx_queue_get(wdev, queue, false);
+	for (;;) {
+		skb = wfx_tx_queues_get_skb(wdev);
 		if (!skb)
-			continue;
-
+			return NULL;
+		skb_queue_tail(&wdev->tx_queue_stats.pending, skb);
+		if (wfx_tx_queues_empty(wdev))
+			wake_up(&wdev->tx_queue_stats.wait_link_id_empty);
+		// FIXME: is it useful?
 		if (wfx_handle_tx_data(wdev, skb))
-			continue;  /* Handled by WSM */
-
+			continue;
+		tx_priv = wfx_skb_tx_priv(skb);
+		tx_priv->xmit_timestamp = ktime_get();
 		return (struct hif_msg *)skb->data;
 	}
 }

drivers/staging/wfx/queue.h

@@ -20,7 +20,8 @@ struct wfx_dev;
 struct wfx_vif;
 
 struct wfx_queue {
-	struct sk_buff_head	queue;
+	struct sk_buff_head	normal;
+	struct sk_buff_head	cab; // Content After (DTIM) Beacon
 	atomic_t		pending_frames;
 };
 
@@ -44,7 +45,6 @@ struct hif_msg *wfx_tx_queues_get(struct wfx_dev *wdev);
 
 void wfx_tx_queue_put(struct wfx_dev *wdev, struct wfx_queue *queue,
 		      struct sk_buff *skb);
-int wfx_tx_queue_get_num_queued(struct wfx_queue *queue);
 
 struct sk_buff *wfx_pending_get(struct wfx_dev *wdev, u32 packet_id);
 int wfx_pending_remove(struct wfx_dev *wdev, struct sk_buff *skb);