From mboxrd@z Thu Jan 1 00:00:00 1970 From: William Allen Simpson Subject: Re: [PATCH v2 1/8] Only parse time stamp TCP option in time wait sock Date: Wed, 21 Oct 2009 14:59:59 -0400 Message-ID: <4ADF5A2F.9010309@gmail.com> References: <1256115421-12714-1-git-send-email-gilad@codefidence.com> <1256115421-12714-2-git-send-email-gilad@codefidence.com> <4ADED915.7000107@gmail.com> <4ADEDD65.6070802@codefidence.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from gv-out-0910.google.com ([216.239.58.186]:27071 "EHLO gv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754111AbZJUTH4 (ORCPT ); Wed, 21 Oct 2009 15:07:56 -0400 Received: by gv-out-0910.google.com with SMTP id r4so841407gve.37 for ; Wed, 21 Oct 2009 12:08:00 -0700 (PDT) In-Reply-To: <4ADEDD65.6070802@codefidence.com> Sender: netdev-owner@vger.kernel.org List-ID: Gilad Ben-Yossef wrote: > William Allen Simpson wrote: > >> Gilad Ben-Yossef wrote: >>> A time wait socket is established - we already know if time stamp >>> option is called for or not. >>> >> Not so sure about this. A timewait sock isn't actually established, >> and new/changed options could appear. There's all sorts of edge cases. > If you examine the specific context where tcp_parse_options is being > called here, > the only TCP option which is of interest is the time stamp option, and > this code path > is only being taken when we already know that the original socket had > used the time stamp option. > > So while I agree that in general you are right, I do believe that in the > specific context > of this patch we should call tcp_parse_options with the established flag > on and let it > know we are expecting to see a time stamp option, which is what I was > referring to. > No, a major reason for time-wait is rebooted systems. We don't "know" anything about them, and they certainly don't know anything about us. As I mentioned, this is about edge cases. >> >> There's also some current work to note: >> >> http://tools.ietf.org/html/draft-ietf-tcpm-1323bis >> >> http://tools.ietf.org/html/draft-gont-tcpm-tcp-timestamps > > Very interesting, thank you. > > As I noted above, my comment about > TIME WAIT sockets being "established" should really only be considered > in the context of the specific call to tcp_parse_options() and the > "established" > parameter of that function. > My suggestion, as this patch is not essential to the other patches in the series, is to separate it. As I'm relatively new to this list, I don't know the best practice. But I'd like to support the others and delay this for further consideration.