From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <4DFB346C.6040607@domain.hid>
Date: Fri, 17 Jun 2011 13:03:08 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
MIME-Version: 1.0
References: <4DFB1E0B.1070903@domain.hid> <4DFB3346.6000405@domain.hid>
In-Reply-To: <4DFB3346.6000405@domain.hid>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Subject: Re: [Xenomai-core] [RFC][PATCH] nucleus: Prevent rescheduling while
 in	xntbase_tick
List-Id: Xenomai life and development <xenomai.xenomai.org>
List-Unsubscribe: <https://mail.gna.org/options/xenomai-core>,
	<mailto:xenomai-core-request@domain.hid>
List-Archive: </public/xenomai-core>
List-Post: <mailto:xenomai@xenomai.org>
List-Help: <mailto:xenomai-core-request@domain.hid>
List-Subscribe: <https://mail.gna.org/listinfo/xenomai-core>,
	<mailto:xenomai-core-request@domain.hid>
To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: Xenomai core <Xenomai-core@domain.hid>

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.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux