[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/3c59x.c b/drivers/net/3c59x.c
index 80ec9aa575bb..07746b95fd83 100644
--- a/drivers/net/3c59x.c
+++ b/drivers/net/3c59x.c
@@ -1802,7 +1802,7 @@ vortex_open(struct net_device *dev)
                                 break;                  /* Bad news!  */
                         skb->dev = dev;                 /* Mark as being used by this device. */
                         skb_reserve(skb, 2);    /* Align IP on 16 byte boundaries */
-                        vp->rx_ring[i].addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->tail, PKT_BUF_SZ, PCI_DMA_FROMDEVICE));
+                        vp->rx_ring[i].addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->data, PKT_BUF_SZ, PCI_DMA_FROMDEVICE));
                 }
                 if (i != RX_RING_SIZE) {
                         int j;
@@ -2632,7 +2632,7 @@ boomerang_rx(struct net_device *dev)
                                 pci_dma_sync_single_for_cpu(VORTEX_PCI(vp), dma, PKT_BUF_SZ, PCI_DMA_FROMDEVICE);
                                 /* 'skb_put()' points to the start of sk_buff data area. */
                                 memcpy(skb_put(skb, pkt_len),
-                                           vp->rx_skbuff[entry]->tail,
+                                           vp->rx_skbuff[entry]->data,
                                            pkt_len);
                                 pci_dma_sync_single_for_device(VORTEX_PCI(vp), dma, PKT_BUF_SZ, PCI_DMA_FROMDEVICE);
                                 vp->rx_copy++;
@@ -2678,7 +2678,7 @@ boomerang_rx(struct net_device *dev)
                         }
                         skb->dev = dev;                 /* Mark as being used by this device. */
                         skb_reserve(skb, 2);    /* Align IP on 16 byte boundaries */
-                        vp->rx_ring[entry].addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->tail, PKT_BUF_SZ, PCI_DMA_FROMDEVICE));
+                        vp->rx_ring[entry].addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->data, PKT_BUF_SZ, PCI_DMA_FROMDEVICE));
                         vp->rx_skbuff[entry] = skb;
                 }
                 vp->rx_ring[entry].status = 0;  /* Clear complete bit. */