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[NET]: Remove gratuitous use of skb->tail in network drivers.

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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>
This commit is contained in:
David S. Miller
2005-06-28 15:25:31 -07:00
parent f835e471b5
commit 689be43945
31 changed files with 95 additions and 97 deletions
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8
drivers/net/fealnx.c
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@@ -1107,7 +1107,7 @@ static void allocate_rx_buffers(struct net_device *dev)
skb->dev = dev; /* Mark as being used by this device. */
np->lack_rxbuf->skbuff = skb;
np->lack_rxbuf->buffer = pci_map_single(np->pci_dev, skb->tail,
np->lack_rxbuf->buffer = pci_map_single(np->pci_dev, skb->data,
np->rx_buf_sz, PCI_DMA_FROMDEVICE);
np->lack_rxbuf->status = RXOWN;
++np->really_rx_count;
@@ -1300,7 +1300,7 @@ static void init_ring(struct net_device *dev)
++np->really_rx_count;
np->rx_ring[i].skbuff = skb;
skb->dev = dev; /* Mark as being used by this device. */
np->rx_ring[i].buffer = pci_map_single(np->pci_dev, skb->tail,
np->rx_ring[i].buffer = pci_map_single(np->pci_dev, skb->data,
np->rx_buf_sz, PCI_DMA_FROMDEVICE);
np->rx_ring[i].status = RXOWN;
np->rx_ring[i].control |= RXIC;
@@ -1737,11 +1737,11 @@ static int netdev_rx(struct net_device *dev)
#if ! defined(__alpha__)
eth_copy_and_sum(skb,
np->cur_rx->skbuff->tail, pkt_len, 0);
np->cur_rx->skbuff->data, pkt_len, 0);
skb_put(skb, pkt_len);
#else
memcpy(skb_put(skb, pkt_len),
np->cur_rx->skbuff->tail, pkt_len);
np->cur_rx->skbuff->data, pkt_len);
#endif
pci_dma_sync_single_for_device(np->pci_dev,
np->cur_rx->buffer,