[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, 5 insertions, 5 deletions

diff --git a/drivers/net/tulip/dmfe.c b/drivers/net/tulip/dmfe.c
index 7b899702ceb9..74e9075d9c48 100644
--- a/drivers/net/tulip/dmfe.c
+++ b/drivers/net/tulip/dmfe.c
@@ -945,8 +945,8 @@ static void dmfe_rx_packet(struct DEVICE *dev, struct dmfe_board_info * db)
 
                                 /* Received Packet CRC check need or not */
                                 if ( (db->dm910x_chk_mode & 1) &&
-                                        (cal_CRC(skb->tail, rxlen, 1) !=
-                                        (*(u32 *) (skb->tail+rxlen) ))) { /* FIXME (?) */
+                                        (cal_CRC(skb->data, rxlen, 1) !=
+                                        (*(u32 *) (skb->data+rxlen) ))) { /* FIXME (?) */
                                         /* Found a error received packet */
                                         dmfe_reuse_skb(db, rxptr->rx_skb_ptr);
                                         db->dm910x_chk_mode = 3;
@@ -959,7 +959,7 @@ static void dmfe_rx_packet(struct DEVICE *dev, struct dmfe_board_info * db)
                                                 /* size less than COPY_SIZE, allocate a rxlen SKB */
                                                 skb->dev = dev;
                                                 skb_reserve(skb, 2); /* 16byte align */
-                                                memcpy(skb_put(skb, rxlen), rxptr->rx_skb_ptr->tail, rxlen);
+                                                memcpy(skb_put(skb, rxlen), rxptr->rx_skb_ptr->data, rxlen);
                                                 dmfe_reuse_skb(db, rxptr->rx_skb_ptr);
                                         } else {
                                                 skb->dev = dev;
@@ -1252,7 +1252,7 @@ static void dmfe_reuse_skb(struct dmfe_board_info *db, struct sk_buff * skb)
 
         if (!(rxptr->rdes0 & cpu_to_le32(0x80000000))) {
                 rxptr->rx_skb_ptr = skb;
-                rxptr->rdes2 = cpu_to_le32( pci_map_single(db->pdev, skb->tail, RX_ALLOC_SIZE, PCI_DMA_FROMDEVICE) );
+                rxptr->rdes2 = cpu_to_le32( pci_map_single(db->pdev, skb->data, RX_ALLOC_SIZE, PCI_DMA_FROMDEVICE) );
                 wmb();
                 rxptr->rdes0 = cpu_to_le32(0x80000000);
                 db->rx_avail_cnt++;
@@ -1463,7 +1463,7 @@ static void allocate_rx_buffer(struct dmfe_board_info *db)
                 if ( ( skb = dev_alloc_skb(RX_ALLOC_SIZE) ) == NULL )
                         break;
                 rxptr->rx_skb_ptr = skb; /* FIXME (?) */
-                rxptr->rdes2 = cpu_to_le32( pci_map_single(db->pdev, skb->tail, RX_ALLOC_SIZE, PCI_DMA_FROMDEVICE) );
+                rxptr->rdes2 = cpu_to_le32( pci_map_single(db->pdev, skb->data, RX_ALLOC_SIZE, PCI_DMA_FROMDEVICE) );
                 wmb();
                 rxptr->rdes0 = cpu_to_le32(0x80000000);
                 rxptr = rxptr->next_rx_desc;