[PATCH net-next resubmit] skbuff: optimize the pull_pages code in __pskb_pull_tail()

[Lin Zhang]

In the pull_pages code block, if the first frag size > eat,
we can end the loop in advance to avoid extra copy.

Signed-off-by: Lin Zhang <xiaolou4...@gmail.com>
---
 net/core/skbuff.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f990eb8..c00a1df 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1720,6 +1720,10 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta)
                                skb_shinfo(skb)->frags[k].page_offset += eat;
                                skb_frag_size_sub(&skb_shinfo(skb)->frags[k], 
eat);
                                eat = 0;
+                               if (!i) {
+                                       k = skb_shinfo(skb)->nr_frags;
+                                       break;
+                               }
                        }
                        k++;
                }
-- 
1.8.3.1