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

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>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/net/yellowfin.c b/drivers/net/yellowfin.c
index 9da925430109..1c2506535f7e 100644
--- a/drivers/net/yellowfin.c
+++ b/drivers/net/yellowfin.c
@@ -786,7 +786,7 @@ static void yellowfin_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. */
                 yp->rx_ring[i].addr = cpu_to_le32(pci_map_single(yp->pci_dev,
-                        skb->tail, yp->rx_buf_sz, PCI_DMA_FROMDEVICE));
+                        skb->data, yp->rx_buf_sz, PCI_DMA_FROMDEVICE));
         }
         yp->rx_ring[i-1].dbdma_cmd = cpu_to_le32(CMD_STOP);
         yp->dirty_rx = (unsigned int)(i - RX_RING_SIZE);
@@ -1111,7 +1111,7 @@ static int yellowfin_rx(struct net_device *dev)
                 pci_dma_sync_single_for_cpu(yp->pci_dev, desc->addr,
                         yp->rx_buf_sz, PCI_DMA_FROMDEVICE);
                 desc_status = le32_to_cpu(desc->result_status) >> 16;
-                buf_addr = rx_skb->tail;
+                buf_addr = rx_skb->data;
                 data_size = (le32_to_cpu(desc->dbdma_cmd) - 
                         le32_to_cpu(desc->result_status)) & 0xffff;
                 frame_status = le16_to_cpu(get_unaligned((s16*)&(buf_addr[data_size - 2])));
@@ -1185,7 +1185,7 @@ static int yellowfin_rx(struct net_device *dev)
                                         break;
                                 skb->dev = dev;
                                 skb_reserve(skb, 2);    /* 16 byte align the IP header */
-                                eth_copy_and_sum(skb, rx_skb->tail, pkt_len, 0);
+                                eth_copy_and_sum(skb, rx_skb->data, pkt_len, 0);
                                 skb_put(skb, pkt_len);
                                 pci_dma_sync_single_for_device(yp->pci_dev, desc->addr,
                                                                                            yp->rx_buf_sz,
@@ -1211,7 +1211,7 @@ static int yellowfin_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 */
                         yp->rx_ring[entry].addr = cpu_to_le32(pci_map_single(yp->pci_dev,
-                                skb->tail, yp->rx_buf_sz, PCI_DMA_FROMDEVICE));
+                                skb->data, yp->rx_buf_sz, PCI_DMA_FROMDEVICE));
                 }
                 yp->rx_ring[entry].dbdma_cmd = cpu_to_le32(CMD_STOP);
                 yp->rx_ring[entry].result_status = 0;   /* Clear complete bit. */