[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/lasi_82596.c b/drivers/net/lasi_82596.c
index 5e263fcba669..41bad07ac1ac 100644
--- a/drivers/net/lasi_82596.c
+++ b/drivers/net/lasi_82596.c
@@ -553,14 +553,14 @@ static inline void init_rx_bufs(struct net_device *dev)
 		if (skb == NULL)
 			panic("%s: alloc_skb() failed", __FILE__);
 		skb_reserve(skb, 2);
-		dma_addr = dma_map_single(lp->dev, skb->tail,PKT_BUF_SZ,
+		dma_addr = dma_map_single(lp->dev, skb->data,PKT_BUF_SZ,
 					  DMA_FROM_DEVICE);
 		skb->dev = dev;
 		rbd->v_next = rbd+1;
 		rbd->b_next = WSWAPrbd(virt_to_dma(lp,rbd+1));
 		rbd->b_addr = WSWAPrbd(virt_to_dma(lp,rbd));
 		rbd->skb = skb;
-		rbd->v_data = skb->tail;
+		rbd->v_data = skb->data;
 		rbd->b_data = WSWAPchar(dma_addr);
 		rbd->size = PKT_BUF_SZ;
 	}
@@ -783,8 +783,8 @@ static inline int i596_rx(struct net_device *dev)
 				rx_in_place = 1;
 				rbd->skb = newskb;
 				newskb->dev = dev;
-				dma_addr = dma_map_single(lp->dev, newskb->tail, PKT_BUF_SZ, DMA_FROM_DEVICE);
-				rbd->v_data = newskb->tail;
+				dma_addr = dma_map_single(lp->dev, newskb->data, PKT_BUF_SZ, DMA_FROM_DEVICE);
+				rbd->v_data = newskb->data;
 				rbd->b_data = WSWAPchar(dma_addr);
 				CHECK_WBACK_INV(rbd, sizeof(struct i596_rbd));
 			}