82576 + NETMAP + VLAN

Giuseppe Lettieri
2016-02-15T15:10:30Z

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
have not been able to reproduce it locally (I have not tried that hard,
to be honest). I am pretty sure that there is a lock inversion - one
that may cause real deadlocks - when you use netmap pipes+kqueue and you
don't pass NETMAP_NO_TX_POLL at NIOCREGIF time. The attached patch
should solve this particular problem, but there may be others. May you
please try it?

Cheers,
Giuseppe

Il 11/02/2016 14:34, Slawa Olhovchenkov ha scritto:
> On Thu, Feb 11, 2016 at 10:11:59AM +0100, Giuseppe Lettieri wrote:
>
>> Il 10/02/2016 14:53, Slawa Olhovchenkov ha scritto:
>>> On Wed, Feb 10, 2016 at 02:33:20PM +0100, Giuseppe Lettieri wrote:
>>>
>>>> Il 10/02/2016 12:59, Slawa Olhovchenkov ha scritto:
>>>>> Can you look also on second issue?
>>>>>
>>>>> PS: What need from me? May be open PR?
>>>>
>>>> May you provide some example code that triggers the issue?
>>>
>>> This is about 700 lines of code (not very clear), may be I can
describe it?
>>
>> I just need some code to trigger the problem locally. Don't worry
about
>> the clarity and the line count, unless you cannot share the code for
>> other reasons.
>
> I am attach source.
> run as "prog if1 if2"
> Got `acquiring duplicate lock of same type: "nm_kn_lock"`
immediatly
> after start.
> Dead locking may be occur immediatly after start or may be need
> traffic flooding.
>


--
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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