From: Igor Maravic <igorm@etf.rs>
Date: Mon, 5 Mar 2012 00:01:25 +0100
Subject: r8169: add byte queue limit support.

commit 036dafa28da1e2565a8529de2ae663c37b7a0060 upstream.

Nothing fancy:
- sent bytes count is notified in the start_xmit path right before
  updating the owner bit in the hardware Tx descriptor (E. Dumazet)
- avoid useless tp->dev dereferencing in start_xmit (E. Dumazet)

Use of netdev_reset_queue is favored over proper accounting in
rtl8169_tx_clear_range since the latter would need more work for the
same result (nb: said accounting degenerates to nothing in xmit_frags).

Signed-off-by: Igor Maravic <igorm@etf.rs>
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
[bwh: Backported to 3.2:
 - Adjust context
 - Don't use 64-bit stats]
---
--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -5340,6 +5340,7 @@
 {
 	rtl8169_tx_clear_range(tp, tp->dirty_tx, NUM_TX_DESC);
 	tp->cur_tx = tp->dirty_tx = 0;
+	netdev_reset_queue(tp->dev);
 }
 
 static void rtl8169_schedule_work(struct net_device *dev, work_func_t task)
@@ -5552,6 +5553,8 @@
 
 	txd->opts2 = cpu_to_le32(opts[1]);
 
+	netdev_sent_queue(dev, skb->len);
+
 	wmb();
 
 	/* Anti gcc 2.95.3 bugware (sic) */
@@ -5644,11 +5647,17 @@
 	rtl8169_schedule_work(dev, rtl8169_reinit_task);
 }
 
+struct rtl_txc {
+	int packets;
+	int bytes;
+};
+
 static void rtl8169_tx_interrupt(struct net_device *dev,
 				 struct rtl8169_private *tp,
 				 void __iomem *ioaddr)
 {
 	unsigned int dirty_tx, tx_left;
+	struct rtl_txc txc = { 0, 0 };
 
 	dirty_tx = tp->dirty_tx;
 	smp_rmb();
@@ -5667,15 +5676,22 @@
 		rtl8169_unmap_tx_skb(&tp->pci_dev->dev, tx_skb,
 				     tp->TxDescArray + entry);
 		if (status & LastFrag) {
-			dev->stats.tx_packets++;
-			dev->stats.tx_bytes += tx_skb->skb->len;
-			dev_kfree_skb(tx_skb->skb);
+			struct sk_buff *skb = tx_skb->skb;
+
+			txc.packets++;
+			txc.bytes += skb->len;
+			dev_kfree_skb(skb);
 			tx_skb->skb = NULL;
 		}
 		dirty_tx++;
 		tx_left--;
 	}
 
+	dev->stats.tx_packets += txc.packets;
+	dev->stats.tx_bytes += txc.bytes;
+
+	netdev_completed_queue(dev, txc.packets, txc.bytes);
+
 	if (tp->dirty_tx != dirty_tx) {
 		tp->dirty_tx = dirty_tx;
 		/* Sync with rtl8169_start_xmit: