2 files changed, 15 insertions, 18 deletions

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index 40756dc68a1..e7e8201283a 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -1215,7 +1215,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
         struct gfar_private *priv = netdev_priv(dev);
         struct txfcb *fcb = NULL;
-        struct txbd8 *txbdp;
+        struct txbd8 *txbdp, *base;
         u16 status;
         unsigned long flags;
 
@@ -1227,6 +1227,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
         /* Point at the first free tx descriptor */
         txbdp = priv->cur_tx;
+        base = priv->tx_bd_base;
 
         /* Clear all but the WRAP status flags */
         status = txbdp->status & TXBD_WRAP;
@@ -1279,12 +1280,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
         eieio();
         txbdp->status = status;
 
-        /* If this was the last BD in the ring, the next one */
-        /* is at the beginning of the ring */
-        if (txbdp->status & TXBD_WRAP)
-                txbdp = priv->tx_bd_base;
-        else
-                txbdp++;
+        txbdp = next_bd(txbdp, base, priv->tx_ring_size);
 
         /* If the next BD still needs to be cleaned up, then the bds
            are full.  We need to tell the kernel to stop sending us stuff. */
@@ -1470,11 +1466,12 @@ static void gfar_timeout(struct net_device *dev)
 /* Interrupt Handler for Transmit complete */
 static int gfar_clean_tx_ring(struct net_device *dev)
 {
-        struct txbd8 *bdp;
+        struct txbd8 *bdp, *base;
         struct gfar_private *priv = netdev_priv(dev);
         int howmany = 0;
 
         bdp = priv->dirty_tx;
+        base = priv->tx_bd_base;
         while ((bdp->status & TXBD_READY) == 0) {
                 /* If dirty_tx and cur_tx are the same, then either the */
                 /* ring is empty or full now (it could only be full in the beginning, */
@@ -1504,11 +1501,7 @@ static int gfar_clean_tx_ring(struct net_device *dev)
                 /* Clean BD length for empty detection */
                 bdp->length = 0;
 
-                /* update bdp to point at next bd in the ring (wrapping if necessary) */
-                if (bdp->status & TXBD_WRAP)
-                        bdp = priv->tx_bd_base;
-                else
-                        bdp++;
+                bdp = next_bd(bdp, base, priv->tx_ring_size);
 
                 /* Move dirty_tx to be the next bd */
                 priv->dirty_tx = bdp;
@@ -1712,7 +1705,7 @@ static int gfar_process_frame(struct net_device *dev, struct sk_buff *skb,
  */
 int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit)
 {
-        struct rxbd8 *bdp;
+        struct rxbd8 *bdp, *base;
         struct sk_buff *skb;
         int pkt_len;
         int amount_pull;
@@ -1721,6 +1714,7 @@ int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit)
 
         /* Get the first full descriptor */
         bdp = priv->cur_rx;
+        base = priv->rx_bd_base;
 
         amount_pull = (gfar_uses_fcb(priv) ? GMAC_FCB_LEN : 0) +
                 priv->padding;
@@ -1776,10 +1770,7 @@ int gfar_clean_rx_ring(struct net_device *dev, int rx_work_limit)
                 gfar_new_rxbdp(dev, bdp, newskb);
 
                 /* Update to the next pointer */
-                if (bdp->status & RXBD_WRAP)
-                        bdp = priv->rx_bd_base;
-                else
-                        bdp++;
+                bdp = next_bd(bdp, base, priv->rx_ring_size);
 
                 /* update to point at the next skb */
                 priv->skb_currx =
diff --git a/drivers/net/gianfar.h b/drivers/net/gianfar.h
index 1bdb50c7936..1ebf7ac27a3 100644
--- a/drivers/net/gianfar.h
+++ b/drivers/net/gianfar.h
@@ -196,6 +196,12 @@ extern const char gfar_driver_version[];
 #define DEFAULT_TXIC mk_ic_value(DEFAULT_TXCOUNT, DEFAULT_TXTIME)
 #define DEFAULT_RXIC mk_ic_value(DEFAULT_RXCOUNT, DEFAULT_RXTIME)
 
+#define skip_bd(bdp, stride, base, ring_size) ({ \
+        typeof(bdp) new_bd = (bdp) + (stride); \
+        (new_bd >= (base) + (ring_size)) ? (new_bd - (ring_size)) : new_bd; })
+
+#define next_bd(bdp, base, ring_size) skip_bd(bdp, 1, base, ring_size)
+
 #define RCTRL_PAL_MASK          0x001f0000
 #define RCTRL_VLEX              0x00002000
 #define RCTRL_FILREN            0x00001000