[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, 4 insertions, 4 deletions

diff --git a/drivers/net/fealnx.c b/drivers/net/fealnx.c
index 9e0303f6d73c..55dbe9a3fd56 100644
--- a/drivers/net/fealnx.c
+++ b/drivers/net/fealnx.c
@@ -1107,7 +1107,7 @@ static void allocate_rx_buffers(struct net_device *dev)
 
                 skb->dev = dev; /* Mark as being used by this device. */
                 np->lack_rxbuf->skbuff = skb;
-                np->lack_rxbuf->buffer = pci_map_single(np->pci_dev, skb->tail,
+                np->lack_rxbuf->buffer = pci_map_single(np->pci_dev, skb->data,
                         np->rx_buf_sz, PCI_DMA_FROMDEVICE);
                 np->lack_rxbuf->status = RXOWN;
                 ++np->really_rx_count;
@@ -1300,7 +1300,7 @@ static void init_ring(struct net_device *dev)
                 ++np->really_rx_count;
                 np->rx_ring[i].skbuff = skb;
                 skb->dev = dev; /* Mark as being used by this device. */
-                np->rx_ring[i].buffer = pci_map_single(np->pci_dev, skb->tail,
+                np->rx_ring[i].buffer = pci_map_single(np->pci_dev, skb->data,
                         np->rx_buf_sz, PCI_DMA_FROMDEVICE);
                 np->rx_ring[i].status = RXOWN;
                 np->rx_ring[i].control |= RXIC;
@@ -1737,11 +1737,11 @@ static int netdev_rx(struct net_device *dev)
 
 #if ! defined(__alpha__)
                                 eth_copy_and_sum(skb, 
-                                        np->cur_rx->skbuff->tail, pkt_len, 0);
+                                        np->cur_rx->skbuff->data, pkt_len, 0);
                                 skb_put(skb, pkt_len);
 #else
                                 memcpy(skb_put(skb, pkt_len),
-                                        np->cur_rx->skbuff->tail, pkt_len);
+                                        np->cur_rx->skbuff->data, pkt_len);
 #endif
                                 pci_dma_sync_single_for_device(np->pci_dev,
                                                                np->cur_rx->buffer,