[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, 3 insertions, 3 deletions

diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
index 610e4769efa4..c5faf1380e15 100644
--- a/drivers/net/cxgb3/sge.c
+++ b/drivers/net/cxgb3/sge.c
@@ -1325,13 +1325,13 @@ static void write_ofld_wr(struct adapter *adap, struct sk_buff *skb,
         flits = skb_transport_offset(skb) / 8;
         sgp = ndesc == 1 ? (struct sg_ent *)&d->flit[flits] : sgl;
         sgl_flits = make_sgl(skb, sgp, skb_transport_header(skb),
-                             skb->tail - skb_transport_header(skb),
+                             skb->tail - skb->transport_header,
                              adap->pdev);
         if (need_skb_unmap()) {
                 setup_deferred_unmapping(skb, adap->pdev, sgp, sgl_flits);
                 skb->destructor = deferred_unmap_destructor;
                 ((struct unmap_info *)skb->cb)->len = (skb->tail -
-                                                       skb_transport_header(skb));
+                                                       skb->transport_header);
         }
 
         write_wr_hdr_sgl(ndesc, skb, d, pidx, q, sgl, flits, sgl_flits,
@@ -1353,7 +1353,7 @@ static inline unsigned int calc_tx_descs_ofld(const struct sk_buff *skb)
                 return 1;       /* packet fits as immediate data */
 
         flits = skb_transport_offset(skb) / 8;  /* headers */
-        if (skb->tail != skb_transport_header(skb))
+        if (skb->tail != skb->transport_header)
                 cnt++;
         return flits_to_desc(flits + sgl_len(cnt));
 }