linux-kernel - Re: skb_split in tcp_retransmit

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Message-ID: <20110127183327.GB4153@swordfish.minsk.epam.com>
Date:	Thu, 27 Jan 2011 20:33:28 +0200
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	Eric Dumazet <eric.dumazet@...il.com>,
	"Pekka Savola (ipv6)" <pekkas@...core.fi>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: skb_split in tcp_retransmit_skb question

On (01/27/11 17:20), Sergey Senozhatsky wrote:
> Hello,
> 
> Suppose we have the following scenario:
> 
> tcp_write_timer ->
>  tcp_retransmit_skb
> 
> in tcp_retransmit_skb we have `if (skb->len > cur_mss)' evaluted to true, which leads
> to tcp_fragment(sk, skb, cur_mss, cur_mss) call. tcp_fragment calls skb_split(skb, buff, len)
> which, in turn, calls skb_split_no_header(skb, skb1, len, pos), where we have
> `skb_shinfo(skb)->nr_frags++' while in `for (i = 0; i < nfrags; i++)' loop.

Sorry for the noise. Alexey has pointed out that we have 
skb_shinfo(skb)->nr_frags = 0 in skb_split_no_header. Have no idea how did I miss it. 

Thanks,

	Sergey

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