[ltt-dev] Cannot destroy trace

[jerome zh]

2010/5/11 Mathieu Desnoyers <compudj at krystal.dyndns.org>

> * jerome zh (jeromezhr at gmail.com) wrote:
> > Hi all,
> >
> > I have modified the original lttng kernel patch to fit my RT-linux
> patched
> > 2.6.30 kernel. And IMHO the kernel now works fine.
> > Everything seems OK until I run "lttctl -D trace1", the process became
> > "blocking like"(I am not sure if it is blocked).
> > The last msg printed on the screen is "lttctl: Destroying trace".
> > Then I added some debug message into the liblttctl.c file. As a result,
> the
> > process was "blocked" while executing
> > *write(fd, op, strlen(op))* in function *lttctl_sendop()*.
> >
> > Any advice? Thanks in advance.
>
> Can you try with the following patch ?
>
>
> lttng fix rt kernel teardown deadlock
>
> LTTng has a teardown bug on RT (deadlock):
>
> Deleting a timer (sync) while holding the traces mutex, and the handler
> takes
> the same mutex, which leads to a deadlock.
>
> Fix this by taking a RCU read lock in the timer (instead of the RT-specific
> fix
> using the mutex), and by doing synchronize_rcu() in addition to
> synchronize_sched() upon updates.
>
> ---
>


>
> --
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
> http://www.efficios.com
>


Thanks!
I will try this patch and let you know if it works on my board.

-- 
Regards,

Jerome
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