Gilles Chanteperdrix wrote:
> Wolfgang Grandegger wrote:
> > Gilles Chanteperdrix wrote:
> > > Wolfgang Grandegger wrote:
> > > > Gilles Chanteperdrix wrote:
> > > > > On Dec 11, 2007 2:20 PM, Wolfgang Grandegger <[EMAIL PROTECTED]>
> 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 ?
> >
> > Well, I tried with v2.3.2, v2.3.x and also trunk, which does not require
> > the patch. Unfortunately, all versions show the same behavior.
>
> Did you check all the system call return values to see if one of them is
> not failing ?
pthread_kill() returns always 0, or what do you exactly mean. I also
checked with printk() that ksrc/skins/posix/signal.c:pthread_kill() gets
called. I realized the following behaviour if I call a printf after a
certain count value:
void* low_prio_task(void* dummy)
{
while (1) {
count++;
if (count == 100000000)
printf("Wakeup\n");
}
return 0;
}
Then the program goes on when the above count value is reached:
Starting high_prio_task
low_prio_task: policy=1 prio=5
SIGUSER1 to id_low: count=13819079, overruns=0
... blocks for a while ...
SIGUSER2 to id_low: count=27681649, overruns=0
suspend signal handler
resume signal handler
SIGUSER1 to id_low: count=100000000, overruns=0
SIGUSER2 to id_low: count=100000000, overruns=0
resume signal handler
suspend signal handler
SIGUSER1 to id_low: count=100000000, overruns=0
SIGUSER2 to id_low: count=100000000, overruns=0
...
This shows that the task did not get suspended before the printf is
executed. And thereafter it never really resumes.
Wolfgang.
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