[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/typhoon.c b/drivers/net/typhoon.c
index 8f33929..0b5ca25 100644
--- a/drivers/net/typhoon.c
+++ b/drivers/net/typhoon.c
@@ -1661,7 +1661,7 @@ typhoon_alloc_rx_skb(struct typhoon *tp, u32 idx)
 #endif
 
 	skb->dev = tp->dev;
-	dma_addr = pci_map_single(tp->pdev, skb->tail,
+	dma_addr = pci_map_single(tp->pdev, skb->data,
 				  PKT_BUF_SZ, PCI_DMA_FROMDEVICE);
 
 	/* Since no card does 64 bit DAC, the high bits will never
@@ -1721,7 +1721,7 @@ typhoon_rx(struct typhoon *tp, struct basic_ring *rxRing, volatile u32 * ready,
 			pci_dma_sync_single_for_cpu(tp->pdev, dma_addr,
 						    PKT_BUF_SZ,
 						    PCI_DMA_FROMDEVICE);
-			eth_copy_and_sum(new_skb, skb->tail, pkt_len, 0);
+			eth_copy_and_sum(new_skb, skb->data, pkt_len, 0);
 			pci_dma_sync_single_for_device(tp->pdev, dma_addr,
 						       PKT_BUF_SZ,
 						       PCI_DMA_FROMDEVICE);