82576 + NETMAP + VLAN

[Slawa Olhovchenkov]

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 at iet.unipi.it