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Date: Tue, 11 Dec 2007 20:59:27 +0100
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From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Subject: Re: [Xenomai-core] How to cancel a Xenomai POSIX thread
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To: Wolfgang Grandegger <wg@domain.hid>
Cc: xenomai-core <xenomai@xenomai.org>

Wolfgang Grandegger wrote:
 > Gilles Chanteperdrix wrote:
 > > On Dec 11, 2007 2:20 PM, Wolfgang Grandegger <wg@domain.hid> wrote:
 > >> Wolfgang Grandegger wrote:
 > >>> The attached test application using a more sophisticated signal handling
 > >>> works fine on my MPC5200-board running Linux 2.6.23 and Xenomai trunk.
 > >>> Going to try it tomorrow on my PC.
 > >> It works fine as well on my PC with Linux 2.6.23 and Xenomai trunk and
 > >> now also with Linux 2.4.25 and Xenomai 2.3.x :-). Just to understand it
 > >> right: The task signaled with pthread_kill() will be suspended and
 > >> switches to secondary mode if it was running in primary mode. The signal
 > >> will then be handled by Linux as usual. When the task resumes, does it
 > >> get switched back to primary mode automatically?
 > > 
 > > No, it will get swtiched back to primary mode only if it calls a
 > > service needing primary mode.
 > 
 > OK.
 > 
 > >> Great, the only open issue is why executing init_task() switches to
 > >> secondary mode resulting in period overruns in high_prio_task(). Is that
 > >> obvious to you?
 > > 
 > > init_task calls pthread_create, which needs running in secondary mode
 > > to create a thread. We can not create a task without help from
 > > secondary mode.
 > 
 > OK.
 > 
 > I was a bit quick with my assumption that it works with 2.4. It actually
 > only works, if I have a pthread_set_mode_np() in the while loop of the
 > primary task:
 > 
 >         while (1) {
 > 		pthread_set_mode_np(0, PTHREAD_PRIMARY);
 >                 count++;
 >         }
 > 
 > Without pthread_set_mode_np(), the system hangs after the following
 > output lines:
 > 
 >   bash-2.05b# ./kill_pthread2
 >   Starting high_prio_task
 >   low_prio_task: policy=1 prio=5
 >   SIGUSER1 to id_low: count=17497245, overruns=0
 > 
 > It seems to hang when the low_prio_task() calls pthread_wait_np()
 > thereafter. Any quick idea where the problem is?

I am clueless. Are you sure you recompiled the kernel after applying the
patch adding the pthread_kill syscall ?

-- 


					    Gilles Chanteperdrix.