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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/eepro100.c
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@ -1269,7 +1269,7 @@ speedo_init_rx_ring(struct net_device *dev)
if (skb == NULL)
break; /* OK. Just initially short of Rx bufs. */
skb->dev = dev; /* Mark as being used by this device. */
rxf = (struct RxFD *)skb->tail;
rxf = (struct RxFD *)skb->data;
sp->rx_ringp[i] = rxf;
sp->rx_ring_dma[i] =
pci_map_single(sp->pdev, rxf,
@ -1661,7 +1661,7 @@ static inline struct RxFD *speedo_rx_alloc(struct net_device *dev, int entry)
sp->rx_ringp[entry] = NULL;
return NULL;
}
rxf = sp->rx_ringp[entry] = (struct RxFD *)skb->tail;
rxf = sp->rx_ringp[entry] = (struct RxFD *)skb->data;
sp->rx_ring_dma[entry] =
pci_map_single(sp->pdev, rxf,
PKT_BUF_SZ + sizeof(struct RxFD), PCI_DMA_FROMDEVICE);
@ -1808,10 +1808,10 @@ speedo_rx(struct net_device *dev)
#if 1 || USE_IP_CSUM
/* Packet is in one chunk -- we can copy + cksum. */
eth_copy_and_sum(skb, sp->rx_skbuff[entry]->tail, pkt_len, 0);
eth_copy_and_sum(skb, sp->rx_skbuff[entry]->data, pkt_len, 0);
skb_put(skb, pkt_len);
#else
memcpy(skb_put(skb, pkt_len), sp->rx_skbuff[entry]->tail,
memcpy(skb_put(skb, pkt_len), sp->rx_skbuff[entry]->data,
pkt_len);
#endif
pci_dma_sync_single_for_device(sp->pdev, sp->rx_ring_dma[entry],