[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, 2 insertions, 2 deletions

diff --git a/drivers/net/natsemi.c b/drivers/net/natsemi.c
index babb59e146ea..9d6d2548c2d3 100644
--- a/drivers/net/natsemi.c
+++ b/drivers/net/natsemi.c
@@ -1926,7 +1926,7 @@ static void refill_rx(struct net_device *dev)
                                 break; /* Better luck next round. */
                         skb->dev = dev; /* Mark as being used by this device. */
                         np->rx_dma[entry] = pci_map_single(np->pci_dev,
-                                skb->tail, buflen, PCI_DMA_FROMDEVICE);
+                                skb->data, buflen, PCI_DMA_FROMDEVICE);
                         np->rx_ring[entry].addr = cpu_to_le32(np->rx_dma[entry]);
                 }
                 np->rx_ring[entry].cmd_status = cpu_to_le32(np->rx_buf_sz);
@@ -2280,7 +2280,7 @@ static void netdev_rx(struct net_device *dev)
                                         buflen,
                                         PCI_DMA_FROMDEVICE);
                                 eth_copy_and_sum(skb,
-                                        np->rx_skbuff[entry]->tail, pkt_len, 0);
+                                        np->rx_skbuff[entry]->data, pkt_len, 0);
                                 skb_put(skb, pkt_len);
                                 pci_dma_sync_single_for_device(np->pci_dev,
                                         np->rx_dma[entry],