[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/starfire.c b/drivers/net/starfire.c
index 12e2b68..88b89dc 100644
--- a/drivers/net/starfire.c
+++ b/drivers/net/starfire.c
@@ -1286,7 +1286,7 @@
np->rx_info[i].skb = skb;
if (skb == NULL)
break;
- np->rx_info[i].mapping = pci_map_single(np->pci_dev, skb->tail, np->rx_buf_sz, PCI_DMA_FROMDEVICE);
+ np->rx_info[i].mapping = pci_map_single(np->pci_dev, skb->data, np->rx_buf_sz, PCI_DMA_FROMDEVICE);
skb->dev = dev; /* Mark as being used by this device. */
/* Grrr, we cannot offset to correctly align the IP header. */
np->rx_ring[i].rxaddr = cpu_to_dma(np->rx_info[i].mapping | RxDescValid);
@@ -1572,7 +1572,7 @@
pci_dma_sync_single_for_cpu(np->pci_dev,
np->rx_info[entry].mapping,
pkt_len, PCI_DMA_FROMDEVICE);
- eth_copy_and_sum(skb, np->rx_info[entry].skb->tail, pkt_len, 0);
+ eth_copy_and_sum(skb, np->rx_info[entry].skb->data, pkt_len, 0);
pci_dma_sync_single_for_device(np->pci_dev,
np->rx_info[entry].mapping,
pkt_len, PCI_DMA_FROMDEVICE);
@@ -1696,7 +1696,7 @@
if (skb == NULL)
break; /* Better luck next round. */
np->rx_info[entry].mapping =
- pci_map_single(np->pci_dev, skb->tail, np->rx_buf_sz, PCI_DMA_FROMDEVICE);
+ pci_map_single(np->pci_dev, skb->data, np->rx_buf_sz, PCI_DMA_FROMDEVICE);
skb->dev = dev; /* Mark as being used by this device. */
np->rx_ring[entry].rxaddr =
cpu_to_dma(np->rx_info[entry].mapping | RxDescValid);