[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/via-velocity.c b/drivers/net/via-velocity.c
index 15e710283493..abc5cee6eedc 100644
--- a/drivers/net/via-velocity.c
+++ b/drivers/net/via-velocity.c
@@ -1335,7 +1335,7 @@ static inline int velocity_rx_copy(struct sk_buff **rx_skb, int pkt_size,
                         if (vptr->flags & VELOCITY_FLAGS_IP_ALIGN)
                                 skb_reserve(new_skb, 2);
 
-                        memcpy(new_skb->data, rx_skb[0]->tail, pkt_size);
+                        memcpy(new_skb->data, rx_skb[0]->data, pkt_size);
                         *rx_skb = new_skb;
                         ret = 0;
                 }
@@ -1456,9 +1456,9 @@ static int velocity_alloc_rx_buf(struct velocity_info *vptr, int idx)
          *      Do the gymnastics to get the buffer head for data at
          *      64byte alignment.
          */
-        skb_reserve(rd_info->skb, (unsigned long) rd_info->skb->tail & 63);
+        skb_reserve(rd_info->skb, (unsigned long) rd_info->skb->data & 63);
         rd_info->skb->dev = vptr->dev;
-        rd_info->skb_dma = pci_map_single(vptr->pdev, rd_info->skb->tail, vptr->rx_buf_sz, PCI_DMA_FROMDEVICE);
+        rd_info->skb_dma = pci_map_single(vptr->pdev, rd_info->skb->data, vptr->rx_buf_sz, PCI_DMA_FROMDEVICE);
         
         /*
          *      Fill in the descriptor to match