netdev - Re: [PATCH v2] tcp: fix MSG

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Date:	Sun, 17 May 2009 15:41:37 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	ilpo.jarvinen@...sinki.fi
Cc:	elendil@...net.nl, matthias.andree@....de, netdev@...r.kernel.org
Subject: Re: [PATCH v2] tcp: fix MSG_PEEK race check

From: "Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
Date: Mon, 11 May 2009 09:32:34 +0300 (EEST)

> [PATCH v2] tcp: fix MSG_PEEK race check
> 
> Commit 518a09ef11 (tcp: Fix recvmsg MSG_PEEK influence of
> blocking behavior) lets the loop run longer than the race check
> did previously expect, so we need to be more careful with this
> check and consider the work we have been doing.
> 
> I tried my best to deal with urg hole madness too which happens
> here:
> 	if (!sock_flag(sk, SOCK_URGINLINE)) {
> 		++*seq;
> 		...
> by using additional offset by one but I certainly have very
> little interest in testing that part.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...sinki.fi>
> Tested-by: Frans Pop <elendil@...net.nl>

Ok, now that I've looked at this, the urg_hole part of this change has
to be removed.

That case being accounted for with urg_hole is exactly what the
debugging message is trying to catch, where we are doing MSG_PEEK and
tcp_check_urg() advances ->copied_seq on us during one of those
"release_sock();/lock_sock();" sequences (which thus invoke TCP input
processing).

Could you please respin this patch with the URG bits removed?

Thanks!
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