[NET]: Remove gratuitous use of skb->tail in network drivers.

Many drivers use skb->tail unnecessarily.

In these situations, the code roughly looks like:

	dev = dev_alloc_skb(...);

	[optional] skb_reserve(skb, ...);

	... skb->tail ...

But even if the skb_reserve() happens, skb->data equals
skb->tail.  So it doesn't make any sense to use anything
other than skb->data in these cases.

Another case was the s2io.c driver directly mucking with
the skb->data and skb->tail pointers.  It really just wanted
to do an skb_reserve(), so that's what the code was changed
to do instead.

Another reason I'm making this change as it allows some SKB
cleanups I have planned simpler to merge.  In those cleanups,
skb->head, skb->tail, and skb->end pointers are removed, and
replaced with skb->head_room and skb->tail_room integers.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/net/sis900.c b/drivers/net/sis900.c
index 127324f014de..23b713c700b3 100644
--- a/drivers/net/sis900.c
+++ b/drivers/net/sis900.c
@@ -1154,7 +1154,7 @@ sis900_init_rx_ring(struct net_device *net_dev)
                 sis_priv->rx_skbuff[i] = skb;
                 sis_priv->rx_ring[i].cmdsts = RX_BUF_SIZE;
                 sis_priv->rx_ring[i].bufptr = pci_map_single(sis_priv->pci_dev,
-                        skb->tail, RX_BUF_SIZE, PCI_DMA_FROMDEVICE);
+                        skb->data, RX_BUF_SIZE, PCI_DMA_FROMDEVICE);
         }
         sis_priv->dirty_rx = (unsigned int) (i - NUM_RX_DESC);
 
@@ -1776,7 +1776,7 @@ static int sis900_rx(struct net_device *net_dev)
                         sis_priv->rx_skbuff[entry] = skb;
                         sis_priv->rx_ring[entry].cmdsts = RX_BUF_SIZE;
                         sis_priv->rx_ring[entry].bufptr = 
-                                pci_map_single(sis_priv->pci_dev, skb->tail, 
+                                pci_map_single(sis_priv->pci_dev, skb->data, 
                                         RX_BUF_SIZE, PCI_DMA_FROMDEVICE);
                         sis_priv->dirty_rx++;
                 }
@@ -1809,7 +1809,7 @@ static int sis900_rx(struct net_device *net_dev)
                         sis_priv->rx_skbuff[entry] = skb;
                         sis_priv->rx_ring[entry].cmdsts = RX_BUF_SIZE;
                         sis_priv->rx_ring[entry].bufptr =
-                                pci_map_single(sis_priv->pci_dev, skb->tail,
+                                pci_map_single(sis_priv->pci_dev, skb->data,
                                         RX_BUF_SIZE, PCI_DMA_FROMDEVICE);
                 }
         }