[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/3c515.c b/drivers/net/3c515.c
index d272ea36a578..91d1c4c24d9b 100644
--- a/drivers/net/3c515.c
+++ b/drivers/net/3c515.c
@@ -822,7 +822,7 @@ static int corkscrew_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 = isa_virt_to_bus(skb->tail);
+                        vp->rx_ring[i].addr = isa_virt_to_bus(skb->data);
                 }
                 vp->rx_ring[i - 1].next = isa_virt_to_bus(&vp->rx_ring[0]);     /* Wrap the ring. */
                 outl(isa_virt_to_bus(&vp->rx_ring[0]), ioaddr + UpListPtr);
@@ -1406,7 +1406,7 @@ static int boomerang_rx(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[entry].addr = isa_virt_to_bus(skb->tail);
+                        vp->rx_ring[entry].addr = isa_virt_to_bus(skb->data);
                         vp->rx_skbuff[entry] = skb;
                 }
                 vp->rx_ring[entry].status = 0;  /* Clear complete bit. */