linux-kernel - [PATCH net-next resubmit] skbuff: optimize the pull_pages code in __pskb_pull

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Message-Id: <1500258126-11235-1-git-send-email-xiaolou4617@gmail.com>
Date:   Mon, 17 Jul 2017 10:22:06 +0800
From:   Lin Zhang <xiaolou4617@...il.com>
To:     davem@...emloft.net
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Lin Zhang <xiaolou4617@...il.com>
Subject: [PATCH net-next resubmit] skbuff: optimize the pull_pages code in __pskb_pull_tail()

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 <xiaolou4617@...il.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