From owner-freebsd-stable@freebsd.org Tue Feb 16 10:30:32 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 B0BE7AAAC21 for ; Tue, 16 Feb 2016 10:30:32 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 9D2E314A5 for ; Tue, 16 Feb 2016 10:30:32 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: by mailman.ysv.freebsd.org (Postfix) id 9A974AAAC20; Tue, 16 Feb 2016 10:30:32 +0000 (UTC) Delivered-To: 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 9A449AAAC1F for ; Tue, 16 Feb 2016 10:30:32 +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 5B2C614A4 for ; Tue, 16 Feb 2016 10:30:32 +0000 (UTC) (envelope-from slw@zxy.spb.ru) Received: from slw by zxy.spb.ru with local (Exim 4.86 (FreeBSD)) (envelope-from ) id 1aVcto-000KYN-FW; Tue, 16 Feb 2016 13:30:28 +0300 Date: Tue, 16 Feb 2016 13:30:28 +0300 From: Slawa Olhovchenkov To: Giuseppe Lettieri Cc: Luigi Rizzo , Adrian Chadd , "stable@freebsd.org" Subject: Re: 82576 + NETMAP + VLAN Message-ID: <20160216103028.GG68298@zxy.spb.ru> References: <20160210115937.GA37895@zxy.spb.ru> <56BB3C20.600@iet.unipi.it> <20160210135318.GL68298@zxy.spb.ru> <56BC505F.7080309@iet.unipi.it> <20160211133428.GM68298@zxy.spb.ru> <56C1EA66.807@iet.unipi.it> <20160215151318.GQ68298@zxy.spb.ru> <56C1F69C.5010004@iet.unipi.it> <20160215214446.GE68298@zxy.spb.ru> <56C2F898.2010203@iet.unipi.it> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56C2F898.2010203@iet.unipi.it> 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: 2.1.20 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Feb 2016 10:30:32 -0000 On Tue, Feb 16, 2016 at 11:23:20AM +0100, Giuseppe Lettieri wrote: > I am sorry, I did not participate to the implementation of kqueue > support and I am not able to comment. Luigi and Adrian should know, however. Thanks! > Cheers, > Giuseppe > > Il 15/02/2016 22:44, Slawa Olhovchenkov ha scritto: > > On Mon, Feb 15, 2016 at 05:02:36PM +0100, Giuseppe Lettieri wrote: > > > >> Il 15/02/2016 16:13, Slawa Olhovchenkov ha scritto: > >>> On Mon, Feb 15, 2016 at 04:10:30PM +0100, Giuseppe Lettieri wrote: > >>> > >>>> Hi Slawa, > >>>> > >>>> I think WITNESS is seeing a false positive, since those two are always > >>>> different mutexes. > >>>> > >>>> The actual deadlock you experience should be caused by something else. I > >>> > >>> Are you sure? When deadlock occur I am see threads waiting on nm_kn_lock. > >> > >> The deadlock I mentioned still involves nm_kn_locks, sorry if I was not > >> clear about that. I am just saying that we never try to take the same > >> lock that we already holding. > >> > >> Nonetheless, there are indeed problems in the path that WITNESS has > >> seen. The problem is that pipes have to notify the other end while > >> called by kevent. kevent holds the nm_kn_lock on the TX src ring and the > >> notification takes the nm_kn_lock on the RX dst ring. > > > > Can you comment other issuses? Is this by design or is this bug? > > > > - with kevent sync for transmiting need first register > > EVFILT_WRITE/EV_DISABLE and after every write > > EVFILT_WRITE/EV_DISPATCH > > > > - with kevent sync all opening /dev/netmap and registering need do > > from same thread as kevent using for sinc (unless no RX/TX). > > > > > > > -- > Dr. Ing. Giuseppe Lettieri > Dipartimento di Ingegneria della Informazione > Universita' di Pisa > Largo Lucio Lazzarino 1, 56122 Pisa - Italy > Ph. : (+39) 050-2217.649 (direct) .599 (switch) > Fax : (+39) 050-2217.600 > e-mail: g.lettieri@iet.unipi.it