From owner-freebsd-stable@freebsd.org Wed Oct 12 12:13:32 2016 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 49930C0EF35 for ; Wed, 12 Oct 2016 12:13:32 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from zxy.spb.ru (zxy.spb.ru [195.70.199.98]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 04671BCB; Wed, 12 Oct 2016 12:13:32 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from slw by zxy.spb.ru with local (Exim 4.86 (FreeBSD)) (envelope-from ) id 1buIPS-000Mec-Q8; Wed, 12 Oct 2016 15:13:22 +0300 Date: Wed, 12 Oct 2016 15:13:22 +0300 From: Slawa Olhovchenkov To: Julien Charbon Cc: Konstantin Belousov , freebsd-stable@FreeBSD.org, hiren panchasara Subject: Re: 11.0 stuck on high network load Message-ID: <20161012121322.GB57876@zxy.spb.ru> References: <20161010173531.GI6177@zxy.spb.ru> <8143cd8f-c007-2378-b004-b2b037402d03@freebsd.org> <20161011121145.GJ6177@zxy.spb.ru> <20161012084045.GA57714@zxy.spb.ru> <20161012092945.GB57714@zxy.spb.ru> <4b0d4b58-6d13-3cd5-6991-27163f27acca@freebsd.org> <20161012095233.GC57714@zxy.spb.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: slw@zxy.spb.ru X-SA-Exim-Scanned: No (on zxy.spb.ru); SAEximRunCond expanded to false X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 12 Oct 2016 12:13:32 -0000 On Wed, Oct 12, 2016 at 02:06:59PM +0200, Julien Charbon wrote: > >>>>> sofree() call tcp_usr_detach() and in tcp_usr_detach() we have > >>>>> unexpected INP_TIMEWAIT. > >>>> > >>>> I see, thus just for the context: The TCP stack in sys/dev/cxgb* is a > >>>> TOE (TCP Offload Engine?) TCP stack for Chelsio NICs, it is a > >>>> separate/side TCP stack that is used only with TCP_OFFLOAD option. > >>>> > >>>> This TOE TCP stack actually has its own set of detach()/input() > >>>> functions and seems to check INP_DROPPED flag properly. I guess @np > >>>> check fixes in socket TCP stack and decides which one can also impact > >>>> the Chelsio TOE TCP stack. Some bugs are only in socket TCP stack, some > >>>> are only in TOE TCP stack. > >>> > >>> I am fear about other direction -- setting INP_TIMEWAIT in Chelsio TOE > >>> TCP stack and impact this to > >>> tcp_timer_2msl()/tcp_close()/sofree()/tcp_usr_detach() path. > >> > >> I see, I expect no problem on this side as tcp_timer_2msl() checks the > >> INP_TIMEWAIT flag and do not call tcp_close() if set. > > > > I am about case when at time of first INP_WUNLOCK() tcp_timer_2msl() > > don't see INP_TIMEWAIT, call tcp_close(), tcp_close() do INP_WUNLOCK() > > and now Chelsio TOE take INP_WLOCK, do tcp_twstart() and set > > INP_TIMEWAIT. After this tcp_timer_2msl resume and have unexpected > > INP_TIMEWAIT in tcp_usr_detach(). > > Sure, basically the same bug that in classic TCP stack. If you think > it can happen, send an email describing that to np@ and he will check > and fix that. He is a TOE TCP stack expert and I am not. In all cases, > if this issue is possible in TOE TCP stack context, the patch will be > straightforward: If the INP_DROPPED flag is set do not call tcp_twstart(). > > The current patch focuses only on the classic TCP stack. May be current workaround (with logging) in tcp_usr_detach() is good solutuion for preventing system lockout by similar bugs?