[PATCH net-next v2 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>
---
v1 -> v2:
        * no need to rewrite skb_shinfo(skb)->nr_frags, per Eric Dumazet.
---
 net/core/skbuff.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f990eb8..af61065 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1719,6 +1719,8 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta)
                        if (eat) {
                                skb_shinfo(skb)->frags[k].page_offset += eat;
                                skb_frag_size_sub(&skb_shinfo(skb)->frags[k], 
eat);
+                               if (!i)
+                                       goto end;
                                eat = 0;
                        }
                        k++;
@@ -1726,6 +1728,7 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta)
        }
        skb_shinfo(skb)->nr_frags = k;
 
+end:
        skb->tail     += delta;
        skb->data_len -= delta;
 
-- 
1.8.3.1