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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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6
drivers/net/sundance.c
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@@ -1028,7 +1028,7 @@ static void init_ring(struct net_device *dev)
skb->dev = dev; /* Mark as being used by this device. */
skb_reserve(skb, 2); /* 16 byte align the IP header. */
np->rx_ring[i].frag[0].addr = cpu_to_le32(
pci_map_single(np->pci_dev, skb->tail, np->rx_buf_sz,
pci_map_single(np->pci_dev, skb->data, np->rx_buf_sz,
PCI_DMA_FROMDEVICE));
np->rx_ring[i].frag[0].length = cpu_to_le32(np->rx_buf_sz | LastFrag);
}
@@ -1341,7 +1341,7 @@ static void rx_poll(unsigned long data)
np->rx_buf_sz,
PCI_DMA_FROMDEVICE);
eth_copy_and_sum(skb, np->rx_skbuff[entry]->tail, pkt_len, 0);
eth_copy_and_sum(skb, np->rx_skbuff[entry]->data, pkt_len, 0);
pci_dma_sync_single_for_device(np->pci_dev,
desc->frag[0].addr,
np->rx_buf_sz,
@@ -1400,7 +1400,7 @@ static void refill_rx (struct net_device *dev)
skb->dev = dev; /* Mark as being used by this device. */
skb_reserve(skb, 2); /* Align IP on 16 byte boundaries */
np->rx_ring[entry].frag[0].addr = cpu_to_le32(
pci_map_single(np->pci_dev, skb->tail,
pci_map_single(np->pci_dev, skb->data,
np->rx_buf_sz, PCI_DMA_FROMDEVICE));
}
/* Perhaps we need not reset this field. */