gianfar: Add support for byte queue limits.

Add support for byte queue limits (BQL), based on the similar
modifications made to intel/igb/igb_main.c from Eric Dumazet
in commit bdbc0631
	"igb: Add support for byte queue limits."

A local variable for tx_queue->qindex was introduced in
gfar_clean_tx_ring, since it is now used often enough to warrant it,
and it cleans up the readability somewhat as well.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

drivers/net/ethernet/freescale/gianfar.c

@@ -1755,9 +1755,12 @@ static void free_skb_resources(struct gfar_private *priv)
 
 	/* Go through all the buffer descriptors and free their data buffers */
 	for (i = 0; i < priv->num_tx_queues; i++) {
+		struct netdev_queue *txq;
 		tx_queue = priv->tx_queue[i];
+		txq = netdev_get_tx_queue(tx_queue->dev, tx_queue->qindex);
 		if(tx_queue->tx_skbuff)
 			free_skb_tx_queue(tx_queue);
+		netdev_tx_reset_queue(txq);
 	}
 
 	for (i = 0; i < priv->num_rx_queues; i++) {
@@ -2217,6 +2220,8 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		lstatus |= BD_LFLAG(TXBD_CRC | TXBD_READY) | skb_headlen(skb);
 	}
 
+	netdev_tx_sent_queue(txq, skb->len);
+
 	/*
 	 * We can work in parallel with gfar_clean_tx_ring(), except
 	 * when modifying num_txbdfree. Note that we didn't grab the lock
@@ -2460,6 +2465,7 @@ static void gfar_align_skb(struct sk_buff *skb)
 static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
 {
 	struct net_device *dev = tx_queue->dev;
+	struct netdev_queue *txq;
 	struct gfar_private *priv = netdev_priv(dev);
 	struct gfar_priv_rx_q *rx_queue = NULL;
 	struct txbd8 *bdp, *next = NULL;
@@ -2471,10 +2477,13 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
 	int frags = 0, nr_txbds = 0;
 	int i;
 	int howmany = 0;
+	int tqi = tx_queue->qindex;
+	unsigned int bytes_sent = 0;
 	u32 lstatus;
 	size_t buflen;
 
-	rx_queue = priv->rx_queue[tx_queue->qindex];
+	rx_queue = priv->rx_queue[tqi];
+	txq = netdev_get_tx_queue(dev, tqi);
 	bdp = tx_queue->dirty_tx;
 	skb_dirtytx = tx_queue->skb_dirtytx;
 
@@ -2533,6 +2542,8 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
 			bdp = next_txbd(bdp, base, tx_ring_size);
 		}
 
+		bytes_sent += skb->len;
+
 		/*
 		 * If there's room in the queue (limit it to rx_buffer_size)
 		 * we add this skb back into the pool, if it's the right size
@@ -2557,13 +2568,15 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
 	}
 
 	/* If we freed a buffer, we can restart transmission, if necessary */
-	if (__netif_subqueue_stopped(dev, tx_queue->qindex) && tx_queue->num_txbdfree)
-		netif_wake_subqueue(dev, tx_queue->qindex);
+	if (__netif_subqueue_stopped(dev, tqi) && tx_queue->num_txbdfree)
+		netif_wake_subqueue(dev, tqi);
 
 	/* Update dirty indicators */
 	tx_queue->skb_dirtytx = skb_dirtytx;
 	tx_queue->dirty_tx = bdp;
 
+	netdev_tx_completed_queue(txq, howmany, bytes_sent);
+
 	return howmany;
 }