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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/via-velocity.c
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@@ -1335,7 +1335,7 @@ static inline int velocity_rx_copy(struct sk_buff **rx_skb, int pkt_size,
if (vptr->flags & VELOCITY_FLAGS_IP_ALIGN)
skb_reserve(new_skb, 2);
memcpy(new_skb->data, rx_skb[0]->tail, pkt_size);
memcpy(new_skb->data, rx_skb[0]->data, pkt_size);
*rx_skb = new_skb;
ret = 0;
}
@@ -1456,9 +1456,9 @@ static int velocity_alloc_rx_buf(struct velocity_info *vptr, int idx)
* Do the gymnastics to get the buffer head for data at
* 64byte alignment.
*/
skb_reserve(rd_info->skb, (unsigned long) rd_info->skb->tail & 63);
skb_reserve(rd_info->skb, (unsigned long) rd_info->skb->data & 63);
rd_info->skb->dev = vptr->dev;
rd_info->skb_dma = pci_map_single(vptr->pdev, rd_info->skb->tail, vptr->rx_buf_sz, PCI_DMA_FROMDEVICE);
rd_info->skb_dma = pci_map_single(vptr->pdev, rd_info->skb->data, vptr->rx_buf_sz, PCI_DMA_FROMDEVICE);
/*
* Fill in the descriptor to match