[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>
diff --git a/drivers/net/s2io.c b/drivers/net/s2io.c
index bb639a8..ea638b1 100644
--- a/drivers/net/s2io.c
+++ b/drivers/net/s2io.c
@@ -1699,11 +1699,9 @@
#else
ba = &nic->ba[ring_no][block_no][off];
skb_reserve(skb, BUF0_LEN);
- tmp = (unsigned long) skb->data;
- tmp += ALIGN_SIZE;
- tmp &= ~ALIGN_SIZE;
- skb->data = (void *) tmp;
- skb->tail = (void *) tmp;
+ tmp = ((unsigned long) skb->data & ALIGN_SIZE);
+ if (tmp)
+ skb_reserve(skb, (ALIGN_SIZE + 1) - tmp);
memset(rxdp, 0, sizeof(RxD_t));
rxdp->Buffer2_ptr = pci_map_single