Re: [Xenomai-help] rt_task_delete() question

[Jan Kiszka <jan.kiszka@domain.hid>]

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Sean McGranaghan wrote:
> Hello all,
> 
> I am posting this for a co-worker who is having problems with killing a 
> real-time task. (He is joining the email list shortly but for now I will pass 
> responses on to him.) Here is the scenario:
> 
> 1. A Linux process starts up and detaches from the tty (daemon)
> 2. The daemon creates a xeno message queue
> 2. The daemon spawns a xeno task
> 3. The xeno task on startup binds to the queue rt_queue_bind()
> 4. The xeno task waits on the queue recv with infinite timeout
> 5. The daemon process goes to sleep in a join, waiting for the task to exit
> 6. Some time later another program starts
> 7. The other non-realtime program looks up the xeno task name via rt_task_bind()
> 8. The other non-realtime program attempts to delete the task via rt_task_delete()
>         Failed Attempt #1 - Non-realtime program calls rt_task_delete() and gets
>                             a segmentation fault
>         Failed Attempt #2 - Non-realtime program spawns a realtime task which
>                             binds to original task and tries rt_task_delete().
>                             Also gets segmentation fault.
> 
> The was attempted one a system running the latest Xenomai 2.1 release.
> 
> What is the preferred method to start/join threads from a non-realtime context?
> 
> Any help is appreciated.
> 

rt_task_delete is not supposed to work across processes (Hmm, is this
detail documented somewhere?).

Use a normal Linux signal (e.g. SIGTERM) to terminate the daemon
process. For a clean termination, you should install a signal handler in
the daemon process which triggers an organised clean-up (all
RT-resources except tasks have to be released explicitly).

Jan


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