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From: arno@natisbad.org (Arnaud Ebalard)
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Miller <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>, Willy Tarreau <w@1wt.eu>,
	netdev@vger.kernel.org
Subject: Question about skb_segment()
Date: Wed, 29 Jan 2014 09:12:57 +0100	[thread overview]
Message-ID: <87fvo71a0m.fsf@natisbad.org> (raw)

Hi Herbert,

I wonder if you could share some knowledge on the behaviour of
skb_segment() as it is implemented in 3.13.0: when passed a GSO
packet to be segmented, can the skb result have skb->next == NULL?

One would expect the number of segments of the result to usually match
tcp_skb_pcount() of passed packet and hence having skb->next != NULL: 
AFAICT, this what usually happens when skb_segment() is called in
tcp_gso_segment() but I noticed some cases where the number of segments
(length of chained sk_buff) is lower than the expected value and also
have two backtraces resulting from a skb delivered with a NULL skb->next. 

The whole thread leading to my question is here, in case you want to
take a look:

 http://thread.gmane.org/gmane.linux.network/301587

Thanks in advance,

a+

             reply	other threads:[~2014-01-29  8:13 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-29  8:12 Arnaud Ebalard [this message]
2014-02-09  2:42 ` Question about skb_segment() Herbert Xu

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