From owner-freebsd-stable@freebsd.org Tue Feb 16 10:17:32 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 72D96AAA6B0 for ; Tue, 16 Feb 2016 10:17:32 +0000 (UTC) (envelope-from g.lettieri@iet.unipi.it) 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 5E4201E9B for ; Tue, 16 Feb 2016 10:17:32 +0000 (UTC) (envelope-from g.lettieri@iet.unipi.it) Received: by mailman.ysv.freebsd.org (Postfix) id 5DA6AAAA6AF; Tue, 16 Feb 2016 10:17:32 +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 5D37BAAA6AE for ; Tue, 16 Feb 2016 10:17:32 +0000 (UTC) (envelope-from g.lettieri@iet.unipi.it) Received: from smtp.unipi.it (smtp2.unipi.it [131.114.21.21]) by mx1.freebsd.org (Postfix) with ESMTP id 250331E99 for ; Tue, 16 Feb 2016 10:17:30 +0000 (UTC) (envelope-from g.lettieri@iet.unipi.it) Received: from localhost (localhost [127.0.0.1]) by smtp.unipi.it (Postfix) with ESMTP id CE5C940903; Tue, 16 Feb 2016 11:17:29 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at unipi.it Received: from [10.216.1.203] (prova.iet.unipi.it [131.114.58.86]) (Authenticated User) by smtp.unipi.it (Postfix) with ESMTPSA id BCA934146D; Tue, 16 Feb 2016 11:17:28 +0100 (CET) Subject: Re: 82576 + NETMAP + VLAN To: Slawa Olhovchenkov References: <56B9E398.1060105@iet.unipi.it> <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> Cc: Luigi Rizzo , Adrian Chadd , "stable@freebsd.org" From: Giuseppe Lettieri Message-ID: <56C2F898.2010203@iet.unipi.it> Date: Tue, 16 Feb 2016 11:23:20 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20160215214446.GE68298@zxy.spb.ru> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit 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 10:17:32 -0000 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. 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