Date: Tue, 16 Feb 2016 13:30:28 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Giuseppe Lettieri <g.lettieri@iet.unipi.it> Cc: Luigi Rizzo <rizzo@iet.unipi.it>, Adrian Chadd <adrian.chadd@gmail.com>, "stable@freebsd.org" <stable@freebsd.org> Subject: Re: 82576 + NETMAP + VLAN Message-ID: <20160216103028.GG68298@zxy.spb.ru> In-Reply-To: <56C2F898.2010203@iet.unipi.it> 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>
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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
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