skbuff: remove unused dma_head & dma_maps fields

[ Upstream commit 03e6d819c2cb2cc8ce5642669a0a7c72336ee7a2 ]

The dma map fields in the skb_shared_info structure no longer has any users
and can be dropped since it is making the skb_shared_info unecessarily larger.

Running slabtop show that we were using 4K slabs for the skb->head on x86_64 w/
an allocation size of 1522.  It turns out that the dma_head and dma_maps array
made skb_shared large enough that we had crossed over the 2k boundary with
standard frames and as such we were using 4k blocks of memory for all skbs.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 0 insertions, 6 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index ec226a2156a6..28a961739b14 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -190,9 +190,6 @@ struct skb_shared_info {
         atomic_t        dataref;
         unsigned short  nr_frags;
         unsigned short  gso_size;
-#ifdef CONFIG_HAS_DMA
-        dma_addr_t      dma_head;
-#endif
         /* Warning: this field is not always filled in (UFO)! */
         unsigned short  gso_segs;
         unsigned short  gso_type;
@@ -201,9 +198,6 @@ struct skb_shared_info {
         struct sk_buff  *frag_list;
         struct skb_shared_hwtstamps hwtstamps;
         skb_frag_t      frags[MAX_SKB_FRAGS];
-#ifdef CONFIG_HAS_DMA
-        dma_addr_t      dma_maps[MAX_SKB_FRAGS];
-#endif
         /* Intermediate layers must ensure that destructor_arg
          * remains valid until skb destructor */
         void *          destructor_arg;