[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, 7 insertions, 7 deletions

diff --git a/drivers/net/82596.c b/drivers/net/82596.c
index 65f97b1..13b745b 100644
--- a/drivers/net/82596.c
+++ b/drivers/net/82596.c
@@ -546,11 +546,11 @@ static inline void init_rx_bufs(struct net_device *dev)
 		rbd->b_next = WSWAPrbd(virt_to_bus(rbd+1));
 		rbd->b_addr = WSWAPrbd(virt_to_bus(rbd));
 		rbd->skb = skb;
-		rbd->v_data = skb->tail;
-		rbd->b_data = WSWAPchar(virt_to_bus(skb->tail));
+		rbd->v_data = skb->data;
+		rbd->b_data = WSWAPchar(virt_to_bus(skb->data));
 		rbd->size = PKT_BUF_SZ;
 #ifdef __mc68000__
-		cache_clear(virt_to_phys(skb->tail), PKT_BUF_SZ);
+		cache_clear(virt_to_phys(skb->data), PKT_BUF_SZ);
 #endif
 	}
 	lp->rbd_head = lp->rbds;
@@ -816,10 +816,10 @@ static inline int i596_rx(struct net_device *dev)
 				rx_in_place = 1;
 				rbd->skb = newskb;
 				newskb->dev = dev;
-				rbd->v_data = newskb->tail;
-				rbd->b_data = WSWAPchar(virt_to_bus(newskb->tail));
+				rbd->v_data = newskb->data;
+				rbd->b_data = WSWAPchar(virt_to_bus(newskb->data));
 #ifdef __mc68000__
-				cache_clear(virt_to_phys(newskb->tail), PKT_BUF_SZ);
+				cache_clear(virt_to_phys(newskb->data), PKT_BUF_SZ);
 #endif
 			}
 			else
@@ -840,7 +840,7 @@ memory_squeeze:
 				skb->protocol=eth_type_trans(skb,dev);
 				skb->len = pkt_len;
 #ifdef __mc68000__
-				cache_clear(virt_to_phys(rbd->skb->tail),
+				cache_clear(virt_to_phys(rbd->skb->data),
 						pkt_len);
 #endif
 				netif_rx(skb);