Date: Wed, 12 Oct 2016 15:13:22 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Julien Charbon <jch@freebsd.org> Cc: Konstantin Belousov <kostikbel@gmail.com>, freebsd-stable@FreeBSD.org, hiren panchasara <hiren@strugglingcoder.info> Subject: Re: 11.0 stuck on high network load Message-ID: <20161012121322.GB57876@zxy.spb.ru> In-Reply-To: <e4f1343c-636a-0970-856b-e65955f79e1a@freebsd.org> References: <20161010173531.GI6177@zxy.spb.ru> <8143cd8f-c007-2378-b004-b2b037402d03@freebsd.org> <20161011121145.GJ6177@zxy.spb.ru> <f1d9e34e-3d85-bd02-e660-6d647e4343fb@freebsd.org> <20161012084045.GA57714@zxy.spb.ru> <f3c0e73a-5e6e-2190-aed3-499250c1764c@freebsd.org> <20161012092945.GB57714@zxy.spb.ru> <4b0d4b58-6d13-3cd5-6991-27163f27acca@freebsd.org> <20161012095233.GC57714@zxy.spb.ru> <e4f1343c-636a-0970-856b-e65955f79e1a@freebsd.org>
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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?
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