[SR-Users] gruu and dead-lock in registrar module

[Daniel-Constantin Mierla]

Hello,

what version are you playing with? To look in the right branch when 
troubleshooting first time, then look at the others that might be 
affected...

Cheers,
Daniel

On 4/30/13 5:07 PM, Andreas Granig wrote:
> Hi,
>
> We're hitting an issue in a deployment where all udp receivers are 
> sitting in FUTEX_WAIT caused by save() -> lock_udomain() and seem to 
> have deadlocked themselves every couple of days.
>
> Looking at the code, enable_gruu in registrar is active by default, 
> and in lookup there is a code path
>
>     /* temp-gruu lookup */
>     res = ul.get_urecord_by_ruid(_d, ahash, &inst, &r, &ptr);
>
> but no lock_udomain is obtained. However, when the execution falls 
> through to the "done:" marker, it does
>
>     ul.unlock_udomain(_d, &aor);
>
> without having called ul.lock_udomain first.
>
> 1.) Could someone please review this part? Looks a bit suspicious, 
> although I don't know what implicitly happens in this case. If it were 
> a semaphore and you decrease it to -1 by decrementing it without prior 
> increment, it's essentially causing a dead-lock, but the current 
> locking implementation might work completely different.
>
> 2.) Since I have no clue how gruu is supposed to work in detail, and 
> since in our config we don't explicitly handle gruu (no lookup in 
> loose-route, but gruu is enabled by default in registrar and we don't 
> explicitly turned it off), I'm not even sure if we ever hit this code 
> path. I only see that the ruid column in the location table is filled, 
> but in order to get to this part, the ";gr" flag needs to be set in 
> the R-URI for a lookup(), which I don't know whether that happened 
> somehow in some call flows (we only log $ru, which I don't think logs 
> these parameters, right?).
>
> Some input is highly appreciated!
>
> Andreas
>
> _______________________________________________
> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
> sr-users at lists.sip-router.org
> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, San Francisco, USA - June 24-27, 2013
   * http://asipto.com/u/katu *