Re: [Xenomai-core] [bug] user memory leakage on rt_task_delete

[Philippe Gerum <rpm@xenomai.org>]

Jan Kiszka wrote:
> Hi all,
> 
> during my ongoing search for the init/cleanup issue of shadow threads, I
> stumbled over another problem: Deleting a userspace native thread that
> is blocked in primary mode does not let the NPTL clean up all resources
> allocated in userspace. If you plan to do some rt_task_create/delete in
> a loop, you will soon run out of memory (and Mr. oom-killer will show
> up...).
> 
> I haven't found a solution for this beyond letting a rt-task always
> terminate itself (or terminate the whole program after forced
> deletions). If there is no solution, we should at least document this
> fact somewhere.
> 
> Again, it's not a common use case, but it's also not an expectable
> behaviour of the native skin.
> 

I see no possible workaround to allow a shadow thread deletion from 
kernel space while still leaving the opportunity for the NPTL thread to 
perform some user-space cleanups; recycling a previous Xenomai context 
to unwind a Linux context would lead to some terminally broken 
situation, so the nucleus must reap the terminated shadow at kernel 
level asap. However, the rt_task_delete() wrapper from the user-space 
support library might preferably pthread_kill() the thread, instead of 
asking the nucleus for that purpose.

-- 

Philippe.