From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Tue, 23 Apr 2013 14:18:17 +0200
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Xenomai] Sporadic freeze using RTnet
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To: Kai Bollue <mlist1@bollue.de>
Cc: xenomai@xenomai.org

On 2013-04-22 19:50, Kai Bollue wrote:
> Hello,
> 
> after having used Xenomai with RTnet for quite some time, we switched to
> new hardware and now experience sporadic freezes when communicating over
> RTnet. (To trigger the problem, it is sufficient to call rtping in a
> loop.) After several minutes (up to about an hour), the system stops
> responding. Output over a serial console while this happens is
> 

Does sysrq still work then? sysrq-l would be interesting e.g.

> - Either nothing at all, or
> 
> -
> [  481.189349] INFO: rcu_bh detected stalls on CPUs/tasks: { 2}
> (detected by 0, t=60042 jiffies)
> [  481.291572] INFO: Stall ended before state dump start
> [  541.224383] INFO: rcu_preempt detected stalls on CPUs/tasks: { 2}
> (detected by 0, t=60002 jiffies)
> [  541.331818] INFO: Stall ended before state dump start
> (repeated), or
> 
> -
> [ 2333.757994] Xenomai: Unbalanced lock/unlock

Ah, here's where the problem start.

CONFIG_IPIPE_TRACE_PANIC may provide further information. Enable it via
the I-pipe tracer. Then, before triggering the lockup, increase the
backtrace points to, say, 2000:

echo 2000 > /proc/ipipe/trace/back_trace_points

Jan

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