[SK_BUFF]: Convert skb->tail to sk_buff_data_t

So that it is also an offset from skb->head, reduces its size from 8 to 4 bytes
on 64bit architectures, allowing us to combine the 4 bytes hole left by the
layer headers conversion, reducing struct sk_buff size to 256 bytes, i.e. 4
64byte cachelines, and since the sk_buff slab cache is SLAB_HWCACHE_ALIGN...
:-)

Many calculations that previously required that skb->{transport,network,
mac}_header be first converted to a pointer now can be done directly, being
meaningful as offsets or pointers.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 3 deletions

diff --git a/drivers/net/tulip/uli526x.c b/drivers/net/tulip/uli526x.c
index 9a5850fa644a..e46f4cb02c15 100644
--- a/drivers/net/tulip/uli526x.c
+++ b/drivers/net/tulip/uli526x.c
@@ -829,7 +829,9 @@ static void uli526x_rx_packet(struct net_device *dev, struct uli526x_board_info
                                         != NULL) ) {
                                         /* size less than COPY_SIZE, allocate a rxlen SKB */
                                         skb_reserve(skb, 2); /* 16byte align */
-                                        memcpy(skb_put(skb, rxlen), rxptr->rx_skb_ptr->tail, rxlen);
+                                        memcpy(skb_put(skb, rxlen),
+                                               skb_tail_pointer(rxptr->rx_skb_ptr),
+                                               rxlen);
                                         uli526x_reuse_skb(db, rxptr->rx_skb_ptr);
                                 } else
                                         skb_put(skb, rxlen);
@@ -1175,7 +1177,10 @@ static void uli526x_reuse_skb(struct uli526x_board_info *db, struct sk_buff * sk
 
         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_tail_pointer(skb),
+                                                          RX_ALLOC_SIZE,
+                                                          PCI_DMA_FROMDEVICE));
                 wmb();
                 rxptr->rdes0 = cpu_to_le32(0x80000000);
                 db->rx_avail_cnt++;
@@ -1339,7 +1344,10 @@ static void allocate_rx_buffer(struct uli526x_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_tail_pointer(skb),
+                                                          RX_ALLOC_SIZE,
+                                                          PCI_DMA_FROMDEVICE));
                 wmb();
                 rxptr->rdes0 = cpu_to_le32(0x80000000);
                 rxptr = rxptr->next_rx_desc;