cxgb3: Correct comparisons and calculations using skb->tail and skb-transport_header

This corrects an regression introduced by "net: Use 16bits for *_headers
fields of struct skbuff" when NET_SKBUFF_DATA_USES_OFFSET is not set. In
that case skb->tail will be a pointer whereas skb->transport_header
will be an offset from head. This is corrected by using wrappers that
ensure that comparisons and calculations are always made using pointers.

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 6 deletions

diff --git a/drivers/net/ethernet/chelsio/cxgb3/sge.c b/drivers/net/ethernet/chelsio/cxgb3/sge.c
index 2fd773e267dc..46d1efc17527 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/sge.c
@@ -1584,9 +1584,8 @@ static void deferred_unmap_destructor(struct sk_buff *skb)
         p = dui->addr;
 
         if (skb->tail - skb->transport_header)
-                pci_unmap_single(dui->pdev, *p++,
-                                 skb->tail - skb->transport_header,
-                                 PCI_DMA_TODEVICE);
+                pci_unmap_single(dui->pdev, *p++, skb_tail_pointer(skb) -
+                                 skb_transport_header(skb), PCI_DMA_TODEVICE);
 
         si = skb_shinfo(skb);
         for (i = 0; i < si->nr_frags; i++)
@@ -1647,8 +1646,8 @@ 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 = write_sgl(skb, sgp, skb_transport_header(skb),
-                             skb->tail - skb->transport_header,
-                             addr);
+                             skb_tail_pointer(skb) -
+                             skb_transport_header(skb), addr);
         if (need_skb_unmap()) {
                 setup_deferred_unmapping(skb, adap->pdev, sgp, sgl_flits);
                 skb->destructor = deferred_unmap_destructor;
@@ -1674,7 +1673,7 @@ static inline unsigned int calc_tx_descs_ofld(const struct sk_buff *skb)
 
         flits = skb_transport_offset(skb) / 8;  /* headers */
         cnt = skb_shinfo(skb)->nr_frags;
-        if (skb->tail != skb->transport_header)
+        if (skb_tail_pointer(skb) != skb_transport_header(skb))
                 cnt++;
         return flits_to_desc(flits + sgl_len(cnt));
 }