b43legacy: Avoid packet losses in the dma worker code

This patch addresses a bug in the dma worker code that keeps draining
packets even when the hardware queues are full. In such cases packets
can not be passed down to the device and are erroneusly dropped by the
code. It is based on commit bad6919469662b7c92bc6353642aaaa777b36bac,
which fixes the same problem in b43.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 67 insertions, 19 deletions

diff --git a/drivers/net/wireless/b43legacy/main.c b/drivers/net/wireless/b43legacy/main.c
index 20f02437af8c..d9185633e82f 100644
--- a/drivers/net/wireless/b43legacy/main.c
+++ b/drivers/net/wireless/b43legacy/main.c
@@ -2440,30 +2440,64 @@ static int b43legacy_rng_init(struct b43legacy_wl *wl)
 	return err;
 }
 
+static void b43legacy_tx_work(struct work_struct *work)
+{
+	struct b43legacy_wl *wl = container_of(work, struct b43legacy_wl,
+				  tx_work);
+	struct b43legacy_wldev *dev;
+	struct sk_buff *skb;
+	int queue_num;
+	int err = 0;
+
+	mutex_lock(&wl->mutex);
+	dev = wl->current_dev;
+	if (unlikely(!dev || b43legacy_status(dev) < B43legacy_STAT_STARTED)) {
+		mutex_unlock(&wl->mutex);
+		return;
+	}
+
+	for (queue_num = 0; queue_num < B43legacy_QOS_QUEUE_NUM; queue_num++) {
+		while (skb_queue_len(&wl->tx_queue[queue_num])) {
+			skb = skb_dequeue(&wl->tx_queue[queue_num]);
+			if (b43legacy_using_pio(dev))
+				err = b43legacy_pio_tx(dev, skb);
+			else
+				err = b43legacy_dma_tx(dev, skb);
+			if (err == -ENOSPC) {
+				wl->tx_queue_stopped[queue_num] = 1;
+				ieee80211_stop_queue(wl->hw, queue_num);
+				skb_queue_head(&wl->tx_queue[queue_num], skb);
+				break;
+			}
+			if (unlikely(err))
+				dev_kfree_skb(skb); /* Drop it */
+			err = 0;
+		}
+
+		if (!err)
+			wl->tx_queue_stopped[queue_num] = 0;
+	}
+
+	mutex_unlock(&wl->mutex);
+}
+
 static void b43legacy_op_tx(struct ieee80211_hw *hw,
 			    struct sk_buff *skb)
 {
 	struct b43legacy_wl *wl = hw_to_b43legacy_wl(hw);
-	struct b43legacy_wldev *dev = wl->current_dev;
-	int err = -ENODEV;
-	unsigned long flags;
 
-	if (unlikely(!dev))
-		goto out;
-	if (unlikely(b43legacy_status(dev) < B43legacy_STAT_STARTED))
-		goto out;
-	/* DMA-TX is done without a global lock. */
-	if (b43legacy_using_pio(dev)) {
-		spin_lock_irqsave(&wl->irq_lock, flags);
-		err = b43legacy_pio_tx(dev, skb);
-		spin_unlock_irqrestore(&wl->irq_lock, flags);
-	} else
-		err = b43legacy_dma_tx(dev, skb);
-out:
-	if (unlikely(err)) {
-		/* Drop the packet. */
+	if (unlikely(skb->len < 2 + 2 + 6)) {
+		/* Too short, this can't be a valid frame. */
 		dev_kfree_skb_any(skb);
+		return;
 	}
+	B43legacy_WARN_ON(skb_shinfo(skb)->nr_frags);
+
+	skb_queue_tail(&wl->tx_queue[skb->queue_mapping], skb);
+	if (!wl->tx_queue_stopped[skb->queue_mapping])
+		ieee80211_queue_work(wl->hw, &wl->tx_work);
+	else
+		ieee80211_stop_queue(wl->hw, skb->queue_mapping);
 }
 
 static int b43legacy_op_conf_tx(struct ieee80211_hw *hw,
@@ -2879,6 +2913,7 @@ static void b43legacy_wireless_core_stop(struct b43legacy_wldev *dev)
 {
 	struct b43legacy_wl *wl = dev->wl;
 	unsigned long flags;
+	int queue_num;
 
 	if (b43legacy_status(dev) < B43legacy_STAT_STARTED)
 		return;
@@ -2898,11 +2933,16 @@ static void b43legacy_wireless_core_stop(struct b43legacy_wldev *dev)
 	/* Must unlock as it would otherwise deadlock. No races here.
 	 * Cancel the possibly running self-rearming periodic work. */
 	cancel_delayed_work_sync(&dev->periodic_work);
+	cancel_work_sync(&wl->tx_work);
 	mutex_lock(&wl->mutex);
 
-	ieee80211_stop_queues(wl->hw); /* FIXME this could cause a deadlock */
+	/* Drain all TX queues. */
+	for (queue_num = 0; queue_num < B43legacy_QOS_QUEUE_NUM; queue_num++) {
+		while (skb_queue_len(&wl->tx_queue[queue_num]))
+			dev_kfree_skb(skb_dequeue(&wl->tx_queue[queue_num]));
+	}
 
-	b43legacy_mac_suspend(dev);
+b43legacy_mac_suspend(dev);
 	free_irq(dev->dev->irq, dev);
 	b43legacydbg(wl, "Wireless interface stopped\n");
 }
@@ -3748,6 +3788,7 @@ static int b43legacy_wireless_init(struct ssb_device *dev)
 	struct ieee80211_hw *hw;
 	struct b43legacy_wl *wl;
 	int err = -ENOMEM;
+	int queue_num;
 
 	b43legacy_sprom_fixup(dev->bus);
 
@@ -3782,6 +3823,13 @@ static int b43legacy_wireless_init(struct ssb_device *dev)
 	mutex_init(&wl->mutex);
 	INIT_LIST_HEAD(&wl->devlist);
 	INIT_WORK(&wl->beacon_update_trigger, b43legacy_beacon_update_trigger_work);
+	INIT_WORK(&wl->tx_work, b43legacy_tx_work);
+
+	/* Initialize queues and flags. */
+	for (queue_num = 0; queue_num < B43legacy_QOS_QUEUE_NUM; queue_num++) {
+		skb_queue_head_init(&wl->tx_queue[queue_num]);
+		wl->tx_queue_stopped[queue_num] = 0;
+	}
 
 	ssb_set_devtypedata(dev, wl);
 	b43legacyinfo(wl, "Broadcom %04X WLAN found (core revision %u)\n",