netdev - Is it a possible bug in dev_gro

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Date:	Fri, 30 Jul 2010 09:54:15 +0800
From:	Xin Xiaohui <xiaohui.xin@...el.com>
To:	netdev@...r.kernel.org, herbert@...dor.apana.org.au,
	davem@...emloft.net
Cc:	Xin Xiaohui <xiaohui.xin@...el.com>
Subject: Is it a possible bug in dev_gro_receive()?

I looked into the code dev_gro_receive(), found the code here:
if the frags[0] is pulled to 0, then the page will be released,
and memmove() frags left.
Is that right? I'm not sure if memmove do right or not, but
frags[0].size is never set after memove at least. what I think
a simple way is not to do anything if we found frags[0].size == 0.
The patch is as followed.

Or am I missing something here?

---
 net/core/dev.c |    7 -------
 1 files changed, 0 insertions(+), 7 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 264137f..28cdbbf 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2730,13 +2730,6 @@ pull:
 
 		skb_shinfo(skb)->frags[0].page_offset += grow;
 		skb_shinfo(skb)->frags[0].size -= grow;
-
-		if (unlikely(!skb_shinfo(skb)->frags[0].size)) {
-			put_page(skb_shinfo(skb)->frags[0].page);
-			memmove(skb_shinfo(skb)->frags,
-				skb_shinfo(skb)->frags + 1,
-				--skb_shinfo(skb)->nr_frags);
-		}
 	}
 
 ok:
-- 
1.5.4.4

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