[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>

6 files changed, 19 insertions, 19 deletions

diff --git a/drivers/net/tulip/de2104x.c b/drivers/net/tulip/de2104x.c
index dd357dd..fc353e3 100644
--- a/drivers/net/tulip/de2104x.c
+++ b/drivers/net/tulip/de2104x.c
@@ -446,13 +446,13 @@ static void de_rx (struct de_private *de)
 
 			mapping =
 			de->rx_skb[rx_tail].mapping =
-				pci_map_single(de->pdev, copy_skb->tail,
+				pci_map_single(de->pdev, copy_skb->data,
 					       buflen, PCI_DMA_FROMDEVICE);
 			de->rx_skb[rx_tail].skb = copy_skb;
 		} else {
 			pci_dma_sync_single_for_cpu(de->pdev, mapping, len, PCI_DMA_FROMDEVICE);
 			skb_reserve(copy_skb, RX_OFFSET);
-			memcpy(skb_put(copy_skb, len), skb->tail, len);
+			memcpy(skb_put(copy_skb, len), skb->data, len);
 
 			pci_dma_sync_single_for_device(de->pdev, mapping, len, PCI_DMA_FROMDEVICE);
 
@@ -1269,7 +1269,7 @@ static int de_refill_rx (struct de_private *de)
 		skb->dev = de->dev;
 
 		de->rx_skb[i].mapping = pci_map_single(de->pdev,
-			skb->tail, de->rx_buf_sz, PCI_DMA_FROMDEVICE);
+			skb->data, de->rx_buf_sz, PCI_DMA_FROMDEVICE);
 		de->rx_skb[i].skb = skb;
 
 		de->rx_ring[i].opts1 = cpu_to_le32(DescOwn);
diff --git a/drivers/net/tulip/dmfe.c b/drivers/net/tulip/dmfe.c
index 7b89970..74e9075 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;
diff --git a/drivers/net/tulip/interrupt.c b/drivers/net/tulip/interrupt.c
index afb5cda..bb35581 100644
--- a/drivers/net/tulip/interrupt.c
+++ b/drivers/net/tulip/interrupt.c
@@ -78,7 +78,7 @@ int tulip_refill_rx(struct net_device *dev)
 			if (skb == NULL)
 				break;
 
-			mapping = pci_map_single(tp->pdev, skb->tail, PKT_BUF_SZ,
+			mapping = pci_map_single(tp->pdev, skb->data, PKT_BUF_SZ,
 						 PCI_DMA_FROMDEVICE);
 			tp->rx_buffers[entry].mapping = mapping;
 
@@ -199,12 +199,12 @@ int tulip_poll(struct net_device *dev, int *budget)
 								   tp->rx_buffers[entry].mapping,
 								   pkt_len, PCI_DMA_FROMDEVICE);
 #if ! defined(__alpha__)
-                                       eth_copy_and_sum(skb, tp->rx_buffers[entry].skb->tail,
+                                       eth_copy_and_sum(skb, tp->rx_buffers[entry].skb->data,
                                                         pkt_len, 0);
                                        skb_put(skb, pkt_len);
 #else
                                        memcpy(skb_put(skb, pkt_len),
-                                              tp->rx_buffers[entry].skb->tail,
+                                              tp->rx_buffers[entry].skb->data,
                                               pkt_len);
 #endif
                                        pci_dma_sync_single_for_device(tp->pdev,
@@ -423,12 +423,12 @@ static int tulip_rx(struct net_device *dev)
 							    tp->rx_buffers[entry].mapping,
 							    pkt_len, PCI_DMA_FROMDEVICE);
 #if ! defined(__alpha__)
-				eth_copy_and_sum(skb, tp->rx_buffers[entry].skb->tail,
+				eth_copy_and_sum(skb, tp->rx_buffers[entry].skb->data,
 						 pkt_len, 0);
 				skb_put(skb, pkt_len);
 #else
 				memcpy(skb_put(skb, pkt_len),
-				       tp->rx_buffers[entry].skb->tail,
+				       tp->rx_buffers[entry].skb->data,
 				       pkt_len);
 #endif
 				pci_dma_sync_single_for_device(tp->pdev,
diff --git a/drivers/net/tulip/tulip_core.c b/drivers/net/tulip/tulip_core.c
index 08e0f80..d45d8f5 100644
--- a/drivers/net/tulip/tulip_core.c
+++ b/drivers/net/tulip/tulip_core.c
@@ -625,7 +625,7 @@ static void tulip_init_ring(struct net_device *dev)
 		tp->rx_buffers[i].skb = skb;
 		if (skb == NULL)
 			break;
-		mapping = pci_map_single(tp->pdev, skb->tail,
+		mapping = pci_map_single(tp->pdev, skb->data,
 					 PKT_BUF_SZ, PCI_DMA_FROMDEVICE);
 		tp->rx_buffers[i].mapping = mapping;
 		skb->dev = dev;			/* Mark as being used by this device. */
diff --git a/drivers/net/tulip/winbond-840.c b/drivers/net/tulip/winbond-840.c
index db4b32c..5b1af39 100644
--- a/drivers/net/tulip/winbond-840.c
+++ b/drivers/net/tulip/winbond-840.c
@@ -849,7 +849,7 @@ static void init_rxtx_rings(struct net_device *dev)
 		if (skb == NULL)
 			break;
 		skb->dev = dev;			/* Mark as being used by this device. */
-		np->rx_addr[i] = pci_map_single(np->pci_dev,skb->tail,
+		np->rx_addr[i] = pci_map_single(np->pci_dev,skb->data,
 					skb->len,PCI_DMA_FROMDEVICE);
 
 		np->rx_ring[i].buffer1 = np->rx_addr[i];
@@ -1269,7 +1269,7 @@ static int netdev_rx(struct net_device *dev)
 				pci_dma_sync_single_for_cpu(np->pci_dev,np->rx_addr[entry],
 							    np->rx_skbuff[entry]->len,
 							    PCI_DMA_FROMDEVICE);
-				eth_copy_and_sum(skb, np->rx_skbuff[entry]->tail, pkt_len, 0);
+				eth_copy_and_sum(skb, np->rx_skbuff[entry]->data, pkt_len, 0);
 				skb_put(skb, pkt_len);
 				pci_dma_sync_single_for_device(np->pci_dev,np->rx_addr[entry],
 							       np->rx_skbuff[entry]->len,
@@ -1315,7 +1315,7 @@ static int netdev_rx(struct net_device *dev)
 				break;			/* Better luck next round. */
 			skb->dev = dev;			/* Mark as being used by this device. */
 			np->rx_addr[entry] = pci_map_single(np->pci_dev,
-							skb->tail,
+							skb->data,
 							skb->len, PCI_DMA_FROMDEVICE);
 			np->rx_ring[entry].buffer1 = np->rx_addr[entry];
 		}
diff --git a/drivers/net/tulip/xircom_tulip_cb.c b/drivers/net/tulip/xircom_tulip_cb.c
index b8a9b39..887d724 100644
--- a/drivers/net/tulip/xircom_tulip_cb.c
+++ b/drivers/net/tulip/xircom_tulip_cb.c
@@ -899,7 +899,7 @@ static void xircom_init_ring(struct net_device *dev)
 			break;
 		skb->dev = dev;			/* Mark as being used by this device. */
 		tp->rx_ring[i].status = Rx0DescOwned;	/* Owned by Xircom chip */
-		tp->rx_ring[i].buffer1 = virt_to_bus(skb->tail);
+		tp->rx_ring[i].buffer1 = virt_to_bus(skb->data);
 	}
 	tp->dirty_rx = (unsigned int)(i - RX_RING_SIZE);
 
@@ -1291,7 +1291,7 @@ xircom_rx(struct net_device *dev)
 			if (skb == NULL)
 				break;
 			skb->dev = dev;			/* Mark as being used by this device. */
-			tp->rx_ring[entry].buffer1 = virt_to_bus(skb->tail);
+			tp->rx_ring[entry].buffer1 = virt_to_bus(skb->data);
 			work_done++;
 		}
 		tp->rx_ring[entry].status = Rx0DescOwned;