82576 + NETMAP + VLAN

Giuseppe Lettieri g.lettieri at iet.unipi.it
Mon Feb 15 15:04:48 UTC 2016

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?


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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: notxpoll.patch
Type: text/x-patch
Size: 519 bytes
Desc: not available
URL: <http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20160215/00b2ca02/attachment.bin>

More information about the freebsd-stable mailing list