[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/sb1250-mac.c b/drivers/net/sb1250-mac.c
index fd2e7c374906..7abd55a4fb21 100644
--- a/drivers/net/sb1250-mac.c
+++ b/drivers/net/sb1250-mac.c
@@ -963,11 +963,11 @@ static int sbdma_add_rcvbuffer(sbmacdma_t *d,struct sk_buff *sb)
         /*
          * Do not interrupt per DMA transfer.
          */
-        dsc->dscr_a = virt_to_phys(sb_new->tail) |
+        dsc->dscr_a = virt_to_phys(sb_new->data) |
                 V_DMA_DSCRA_A_SIZE(NUMCACHEBLKS(pktsize+ETHER_ALIGN)) |
                 0;
 #else
-        dsc->dscr_a = virt_to_phys(sb_new->tail) |
+        dsc->dscr_a = virt_to_phys(sb_new->data) |
                 V_DMA_DSCRA_A_SIZE(NUMCACHEBLKS(pktsize+ETHER_ALIGN)) |
                 M_DMA_DSCRA_INTERRUPT;
 #endif