netdev - Re: [PATCH 5/5] tcp: ipv4 listen state scaled

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Message-ID: <20101027150434.GA13121@ms2.inr.ac.ru>
Date:	Wed, 27 Oct 2010 19:04:34 +0400
From:	Alexey Kuznetsov <kuznet@....inr.ac.ru>
To:	Dmitry Popov <dp@...hloadlab.com>, netdev@...r.kernel.org
Subject: Re: [PATCH 5/5] tcp: ipv4 listen state scaled

Hello!

It looks like there is at least one hole here.

You take lock, check syn table and drop lock in tcp_v4_hnd_req().
Then you immediately enter tcp_v4_conn_request() and grab lock again.
Oops, in the tiny hole while lock was dropped the request can be already
created (even funnier, the whole socket can be already created and even accepted).
So, if you drop lock, you have to restart the whole tcp_v4_rcv_listen()
(which seems to be impossible without additional tricks)

Alexey
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