[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/dl2k.c b/drivers/net/dl2k.c
index aa42b7a27735..430c628279b3 100644
--- a/drivers/net/dl2k.c
+++ b/drivers/net/dl2k.c
@@ -547,7 +547,7 @@ rio_timer (unsigned long data)
                                 skb_reserve (skb, 2);
                                 np->rx_ring[entry].fraginfo =
                                     cpu_to_le64 (pci_map_single
-                                         (np->pdev, skb->tail, np->rx_buf_sz,
+                                         (np->pdev, skb->data, np->rx_buf_sz,
                                           PCI_DMA_FROMDEVICE));
                         }
                         np->rx_ring[entry].fraginfo |=
@@ -618,7 +618,7 @@ alloc_list (struct net_device *dev)
                 /* Rubicon now supports 40 bits of addressing space. */
                 np->rx_ring[i].fraginfo =
                     cpu_to_le64 ( pci_map_single (
-                                  np->pdev, skb->tail, np->rx_buf_sz,
+                                  np->pdev, skb->data, np->rx_buf_sz,
                                   PCI_DMA_FROMDEVICE));
                 np->rx_ring[i].fraginfo |= cpu_to_le64 (np->rx_buf_sz) << 48;
         }
@@ -906,7 +906,7 @@ receive_packet (struct net_device *dev)
                                 /* 16 byte align the IP header */
                                 skb_reserve (skb, 2);
                                 eth_copy_and_sum (skb,
-                                                  np->rx_skbuff[entry]->tail,
+                                                  np->rx_skbuff[entry]->data,
                                                   pkt_len, 0);
                                 skb_put (skb, pkt_len);
                                 pci_dma_sync_single_for_device(np->pdev,
@@ -950,7 +950,7 @@ receive_packet (struct net_device *dev)
                         skb_reserve (skb, 2);
                         np->rx_ring[entry].fraginfo =
                             cpu_to_le64 (pci_map_single
-                                         (np->pdev, skb->tail, np->rx_buf_sz,
+                                         (np->pdev, skb->data, np->rx_buf_sz,
                                           PCI_DMA_FROMDEVICE));
                 }
                 np->rx_ring[entry].fraginfo |=