skb: Drop bad code from pskb_expand_head

The fast-path for pskb_expand_head contains a check where the size plus the
unaligned size of skb_shared_info is compared against the size of the data
buffer.  This code path has two issues.  First is the fact that after the
recent changes by Eric Dumazet to __alloc_skb and build_skb the shared info
is always placed in the optimal spot for a buffer size making this check
unnecessary.  The second issue is the fact that the check doesn't take into
account the aligned size of shared info.  As a result the code burns cycles
doing a memcpy with nothing actually being shifted.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 12 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c199aa428c6d..4d085d454285 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -951,17 +951,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
                 fastpath = atomic_read(&skb_shinfo(skb)->dataref) == delta;
         }
 
-        if (fastpath && !skb->head_frag &&
-            size + sizeof(struct skb_shared_info) <= ksize(skb->head)) {
-                memmove(skb->head + size, skb_shinfo(skb),
-                        offsetof(struct skb_shared_info,
-                                 frags[skb_shinfo(skb)->nr_frags]));
-                memmove(skb->head + nhead, skb->head,
-                        skb_tail_pointer(skb) - skb->head);
-                off = nhead;
-                goto adjust_others;
-        }
-
         data = kmalloc(size + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)),
                        gfp_mask);
         if (!data)
@@ -997,7 +986,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 
         skb->head     = data;
         skb->head_frag = 0;
-adjust_others:
         skb->data    += off;
 #ifdef NET_SKBUFF_DATA_USES_OFFSET
         skb->end      = size;