From owner-freebsd-net@FreeBSD.ORG Wed Jan 8 19:18:43 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 02300B8D for ; Wed, 8 Jan 2014 19:18:43 +0000 (UTC) Received: from mail-pa0-x233.google.com (mail-pa0-x233.google.com [IPv6:2607:f8b0:400e:c03::233]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id AF493183A for ; Wed, 8 Jan 2014 19:18:42 +0000 (UTC) Received: by mail-pa0-f51.google.com with SMTP id fa1so2264678pad.10 for ; Wed, 08 Jan 2014 11:18:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wemm.org; s=google; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type:content-transfer-encoding; bh=wO7PlkoKP7FqMbG3VSl1TjwqEfVwiFZt9BU82Bx+JcE=; b=1SCkax6QAj9fz9DEVf+m3u/cY972NZu2T3su6/rSX9QxCY57HlT+6yWSkbqvu0iVgd NxErsNqGRr9KdWOXbRi9fwQ6jD6B3FRxrHZGOx420CLsyXY6aEj+MtJiJtwvwfjGJ85a WmtSvdmOfnsRvymGjpf8Qwn0Dp+9PretWqDOQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :subject:references:in-reply-to:content-type :content-transfer-encoding; bh=wO7PlkoKP7FqMbG3VSl1TjwqEfVwiFZt9BU82Bx+JcE=; b=aXAayf+0ZEtrkMuIMWcIheb//ffk4t5ZIDbwmkfKEzTVyobaNrCXgZv8NARRsO/AbF qzfiYOvjYwmxqwrb5msCmH9tyKWHi/gAEU8xqj+Vdtv+Nih+WySIuKBKAPNJ52OSdNg8 /QY50Ty/yxRGA1vh+Pg1CjSVQK5mN2AdFcCAC5K7L+I6/2MHvNZ7H5vnv0BTxay5jOJM NNWMivsyO9OyPbU0Lp9x7rjpFg19zH0YxfrL1lmB5oSgaxlqxAbKxCZ5qN5hzqP+WLrF 3uD2DhoV6eMWnId8eqRRDcH+itittxlaiLSSjRy/+tnl43ckb6m3L07psgkMIDpKT2sn ra5Q== X-Gm-Message-State: ALoCoQkRJ3Aqfu57nu+VLTfV4e5x1EJ3ZffzsgobbQyCYluEedr83bxMAOgi5qRNxy3vNk+BTRQC X-Received: by 10.66.232.40 with SMTP id tl8mr15134556pac.137.1389208722104; Wed, 08 Jan 2014 11:18:42 -0800 (PST) Received: from hater-dm.corp.yahoo.com (nat-dip4.cfw-a-gci.corp.yahoo.com. [209.131.62.113]) by mx.google.com with ESMTPSA id sg1sm4374635pbb.16.2014.01.08.11.18.40 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 08 Jan 2014 11:18:41 -0800 (PST) Message-ID: <52CDA490.5060002@wemm.org> Date: Wed, 08 Jan 2014 11:18:40 -0800 From: Peter Wemm User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Mike Tancsa , freebsd-net@freebsd.org, eadler@freebsd.org, rrs@freebsd.org Subject: Re: TCP question: Is this simultaneous close handling broken? References: <52CB3AE9.3030107@wemm.org> <52CC5F2E.5030201@wemm.org> <52CC8246.7080609@wemm.org> <52CC903C.5090706@sentex.net> <52CCC0DF.1020007@wemm.org> In-Reply-To: <52CCC0DF.1020007@wemm.org> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 08 Jan 2014 19:18:43 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 1/7/14, 7:07 PM, Peter Wemm wrote: > On 1/7/14, 3:39 PM, Mike Tancsa wrote: >> On 1/7/2014 5:40 PM, Peter Wemm wrote: >> >>> The packet may be dropped without processing the FIN flag. >> >>> MFC after: never >> >> Hi, Are there any potential side effects to this fix ? The original >> author said they were not going to MFC due to possible regressions. >> I know you probably see more FreeBSD traffic then most at Y!, and so >> are very sensitive to this, but thought I would ask for >> clarification. >> >> ---Mike > > Actually, I'm very troubled by that entire chunk of code. I think the correct fix is to back out r239672 from rrs, and modify r258821 from the PR so that it understands that that it applies to only the first FIN packet we get. I slightly moved the test for clarity and for room to comment. http://people.freebsd.org/~peter/tcp_input.c.diff I believe that eadler's r258821 interferes with normal cc operation for a small window after the remote has sent a FIN. Rev r258821 also turns r239672 into dead code. - -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI6FJV UTF-8: for when a ' just won\342\200\231t do. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (Darwin) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlLNpI4ACgkQFRKuUnJ3cX9yHwCfUVVXcsfHtKRfsCeQ1OVksAYW FskAn3PuJozJw0kVKpfJuaEoHBOClTdY =63Li -----END PGP SIGNATURE-----