82576 + NETMAP + VLAN

Giuseppe Lettieri g.lettieri at iet.unipi.it
Tue Feb 16 10:17:32 UTC 2016

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.


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
> - 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

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