Re: [Xenomai-core] [RFC][PATCH] nucleus: Prevent rescheduling while in xntbase_tick

[Philippe Gerum <rpm@xenomai.org>]

On Fri, 2011-06-17 at 14:11 +0200, Jan Kiszka wrote:
> On 2011-06-17 13:58, Philippe Gerum wrote:
> > On Fri, 2011-06-17 at 13:03 +0200, Jan Kiszka wrote:
> >> On 2011-06-17 12:58, Gilles Chanteperdrix wrote:
> >>> On 06/17/2011 11:27 AM, Jan Kiszka wrote:
> >>>> Based on code inspection, it looks like a timer handler triggering a
> >>>> reschedule in the path xntbase_tick -> xntimer_tick_aperiodic /
> >>>> xntimer_tick_periodic_inner -> handler can cause problems, e.g. a
> >>>> reschedule before all expired timers were processed. The timer core is
> >>>> usually run atomically from an interrupt handler, so better emulate an
> >>>> IRQ context inside xntbase_tick by setting XNINIRQ.
> >>>
> >>> I do not understand this one either: if we are inside
> >>> xntimer_tick_aperiodic, XNINIRQ is already set.
> >>
> >> Not if you come via xntbase_tick, called by the mentioned skins also
> >> outside a timer IRQ (at least based on my understanding of that skin
> >> APIs). But I might be wrong, I just came across this while checking for
> >> potentially invalid cached xnpod_current_sched values.
> > 
> > That is ok, ui_timer(), tickAnnounce() and tm_tick() are designed by the
> > respective RTOS to be called from IRQ context.
> 
> Fine. Should we add a XENO_ASSERT to set this in stone and for
> documentation purposes?

I think so.

> 
> Jan
> 

-- 
Philippe.