netdev - Re: race in skb_splice

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Message-Id: <200805281820.02143.opurdila@ixiacom.com>
Date:	Wed, 28 May 2008 18:20:02 +0300
From:	Octavian Purdila <opurdila@...acom.com>
To:	Evgeniy Polyakov <johnpol@....mipt.ru>
Cc:	Ben Hutchings <bhutchings@...arflare.com>, netdev@...r.kernel.org,
	davem@...emloft.net
Subject: Re: race in skb_splice_bits?

On Wednesday 28 May 2008, Evgeniy Polyakov wrote:

> > > I preserved old semantic, when we free skb
> > > only if we read it whole or in case of fin. With your changes we can
> > > also free skb, if it was partially consumed
> >
> > If the skb was partially consumed then tcp_recv_skb(seq-1) will return
> > the same skb and the offset +1 != skb->len, thus we will not free it.
>
> I understand now, please correct me if I got your idea wrong.
> We only ned to search for the skb again only in case we processed it and
> it was possible that socket lock was dropped. So, the only needed place
> to put tcp_recv_skb() is where you pointed. Next, to find current skb we
<snip>

Yes, that is correct. 

> So yes, your patch is simpler and faster than mine so you should push it
> upstream. Fortunately David Miller is in copy and will (David, will
> you?) pick it up and push, likely it is also needed for stable?
>

OK, will clean it up and post a proper patch soon. Which tree should I base it 
on?

Thanks,
tavi
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