[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, 5 insertions, 5 deletions

diff --git a/drivers/net/tulip/interrupt.c b/drivers/net/tulip/interrupt.c
index afb5cda9d8e1..bb3558164a5b 100644
--- a/drivers/net/tulip/interrupt.c
+++ b/drivers/net/tulip/interrupt.c
@@ -78,7 +78,7 @@ int tulip_refill_rx(struct net_device *dev)
                         if (skb == NULL)
                                 break;
 
-                        mapping = pci_map_single(tp->pdev, skb->tail, PKT_BUF_SZ,
+                        mapping = pci_map_single(tp->pdev, skb->data, PKT_BUF_SZ,
                                                  PCI_DMA_FROMDEVICE);
                         tp->rx_buffers[entry].mapping = mapping;
 
@@ -199,12 +199,12 @@ int tulip_poll(struct net_device *dev, int *budget)
                                                                    tp->rx_buffers[entry].mapping,
                                                                    pkt_len, PCI_DMA_FROMDEVICE);
 #if ! defined(__alpha__)
-                                       eth_copy_and_sum(skb, tp->rx_buffers[entry].skb->tail,
+                                       eth_copy_and_sum(skb, tp->rx_buffers[entry].skb->data,
                                                         pkt_len, 0);
                                        skb_put(skb, pkt_len);
 #else
                                        memcpy(skb_put(skb, pkt_len),
-                                              tp->rx_buffers[entry].skb->tail,
+                                              tp->rx_buffers[entry].skb->data,
                                               pkt_len);
 #endif
                                        pci_dma_sync_single_for_device(tp->pdev,
@@ -423,12 +423,12 @@ static int tulip_rx(struct net_device *dev)
                                                             tp->rx_buffers[entry].mapping,
                                                             pkt_len, PCI_DMA_FROMDEVICE);
 #if ! defined(__alpha__)
-                                eth_copy_and_sum(skb, tp->rx_buffers[entry].skb->tail,
+                                eth_copy_and_sum(skb, tp->rx_buffers[entry].skb->data,
                                                  pkt_len, 0);
                                 skb_put(skb, pkt_len);
 #else
                                 memcpy(skb_put(skb, pkt_len),
-                                       tp->rx_buffers[entry].skb->tail,
+                                       tp->rx_buffers[entry].skb->data,
                                        pkt_len);
 #endif
                                 pci_dma_sync_single_for_device(tp->pdev,