[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/ns83820.c b/drivers/net/ns83820.c
index cc796527..e64df4d 100644
--- a/drivers/net/ns83820.c
+++ b/drivers/net/ns83820.c
@@ -574,7 +574,7 @@
dev->rx_info.next_empty = (next_empty + 1) % NR_RX_DESC;
cmdsts = REAL_RX_BUF_SIZE | CMDSTS_INTR;
- buf = pci_map_single(dev->pci_dev, skb->tail,
+ buf = pci_map_single(dev->pci_dev, skb->data,
REAL_RX_BUF_SIZE, PCI_DMA_FROMDEVICE);
build_rx_desc(dev, sg, 0, buf, cmdsts, 0);
/* update link of previous rx */
@@ -604,7 +604,7 @@
if (unlikely(!skb))
break;
- res = (long)skb->tail & 0xf;
+ res = (long)skb->data & 0xf;
res = 0x10 - res;
res &= 0xf;
skb_reserve(skb, res);