Re: [PATCH 2/2] tcp: miscounts due to tcp_fragment pcount reset

From: David Miller
Date: Thu Apr 02 2009 - 19:33:43 EST


From: "Ilpo Järvinen" <ilpo.jarvinen@xxxxxxxxxxx>
Date: Thu, 2 Apr 2009 12:18:20 +0300 (EEST)

>
> It seems that trivial reset of pcount to one was not sufficient
> in tcp_retransmit_skb. Multiple counters experience a positive
> miscount when skb's pcount gets lowered without the necessary
> adjustments (depending on skb's sacked bits which exactly), at
> worst a packets_out miscount can crash at RTO if the write queue
> is empty!
>
> Triggering this requires mss change, so bidir tcp or mtu probe or
> like.
>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxx>
> Reported-by: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>
> Tested-by: Uwe Bugla <uwe.bugla@xxxxxx>

Applied.
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