[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/tulip/de2104x.c b/drivers/net/tulip/de2104x.c
index dd357dd8c370..fc353e348f9a 100644
--- a/drivers/net/tulip/de2104x.c
+++ b/drivers/net/tulip/de2104x.c
@@ -446,13 +446,13 @@ static void de_rx (struct de_private *de)
 
 			mapping =
 			de->rx_skb[rx_tail].mapping =
-				pci_map_single(de->pdev, copy_skb->tail,
+				pci_map_single(de->pdev, copy_skb->data,
 					       buflen, PCI_DMA_FROMDEVICE);
 			de->rx_skb[rx_tail].skb = copy_skb;
 		} else {
 			pci_dma_sync_single_for_cpu(de->pdev, mapping, len, PCI_DMA_FROMDEVICE);
 			skb_reserve(copy_skb, RX_OFFSET);
-			memcpy(skb_put(copy_skb, len), skb->tail, len);
+			memcpy(skb_put(copy_skb, len), skb->data, len);
 
 			pci_dma_sync_single_for_device(de->pdev, mapping, len, PCI_DMA_FROMDEVICE);
 
@@ -1269,7 +1269,7 @@ static int de_refill_rx (struct de_private *de)
 		skb->dev = de->dev;
 
 		de->rx_skb[i].mapping = pci_map_single(de->pdev,
-			skb->tail, de->rx_buf_sz, PCI_DMA_FROMDEVICE);
+			skb->data, de->rx_buf_sz, PCI_DMA_FROMDEVICE);
 		de->rx_skb[i].skb = skb;
 
 		de->rx_ring[i].opts1 = cpu_to_le32(DescOwn);