[lttng-dev] baddr feature triggers deadlock in lttng-ust

[Paul_Woegerer@mentor.com (Woegerer, Paul)]

Hi Mathieu,

this is very unfortunate. I tested forks as well but couldn?t find any
issues on x86_64. Ironically, last week we found an issue that matches
your description on PowerPC but since we could not reproduce it on x86 I
blamed it on the peculiarities of that platform and worked on seemingly
higher priority issues instead.

For the sake of damage containment I just posted:
http://lists.lttng.org/pipermail/lttng-dev/2014-February/022494.html
to the list.

Not having that feature in 2.4 (at least in the experimental form
suggested above) would be a disaster for us.

Meanwhile I'm trying to think about a more fundamental solution to the
problem. But I'm afraid your comment about rethinking of the locking
strategy for the entire UST might come true.


Thanks,
Paul


On 02/27/2014 10:30 PM, Mathieu Desnoyers wrote:
> Hi Paul,
> 
> Please see http://bugs.lttng.org/issues/745, which explains a deadlock
> we just found out.
> 
> We might have to disable the baddr dump feature, since our release is
> tomorrow. We'll have to re-think our locking to protect operations
> using the dynamic loader lock against fork, clone, and daemon.
> 
> Thanks,
> 
> Mathieu
> 


-- 
Paul Woegerer, SW Development Engineer
Sourcery Analyzer <http://go.mentor.com/sourceryanalyzer>
Mentor Graphics, Embedded Software Division