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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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4
drivers/net/r8169.c
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@@ -1876,7 +1876,7 @@ static int rtl8169_alloc_rx_skb(struct pci_dev *pdev, struct sk_buff **sk_buff,
skb_reserve(skb, NET_IP_ALIGN);
*sk_buff = skb;
mapping = pci_map_single(pdev, skb->tail, rx_buf_sz,
mapping = pci_map_single(pdev, skb->data, rx_buf_sz,
PCI_DMA_FROMDEVICE);
rtl8169_map_to_asic(desc, mapping, rx_buf_sz);
@@ -2336,7 +2336,7 @@ static inline int rtl8169_try_rx_copy(struct sk_buff **sk_buff, int pkt_size,
skb = dev_alloc_skb(pkt_size + NET_IP_ALIGN);
if (skb) {
skb_reserve(skb, NET_IP_ALIGN);
eth_copy_and_sum(skb, sk_buff[0]->tail, pkt_size, 0);
eth_copy_and_sum(skb, sk_buff[0]->data, pkt_size, 0);
*sk_buff = skb;
rtl8169_mark_to_asic(desc, rx_buf_sz);
ret = 0;