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Date: Mon, 21 Jan 2013 12:30:19 +0100
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Xenomai] [CRITICAL PATCH] ipipe: Re-read domain context after
	IRQ processing
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To: Philippe Gerum <rpm@xenomai.org>
Cc: Xenomai <xenomai@xenomai.org>

On 2013-01-18 21:09, Jan Kiszka wrote:
> On 2013-01-18 20:04, Jan Kiszka wrote:
>> On 2013-01-18 18:04, Jan Kiszka wrote:
>>> On 2013-01-18 17:37, Philippe Gerum wrote:
>>>> On 01/18/2013 04:38 PM, Jan Kiszka wrote:
>>>>> This fixes a nasty bug on SMP boxes: We may migrate to root in the
>>>>> context of an IRQ handler, and then also to a different CPU. Therefore,
>>>>> we must not use domain contexts read before the invocation but update
>>>>> them afterward or use stable information like the domain reference.
>>>>
>>>> Ack.
>>>>
>>>>>
>>>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>>> ---
>>>>>
>>>>> We are still facing stalled, unkillable RT processes despite this fix,
>>>>
>>>> Is TASK_HARDENING still lingering in task->state despite the recent 
>>>> switch_tail fix, or is this something different?
>>>
>>> Patch is applied, but I didn't check this detail yet.
>>>
>>> I just found a potential SMP race in schedule_linux_call, patch follows.
>>> But now I triggered XENO_BUGON(NUCLEUS, need_resched == 0); for unknown
>>> reasons...
>>
>> Probably found the problem - or at least another one: XNINLOCK must be
>> used with xnsched::lflags, not status. It is set/cleared by the RTDM
>> spin locks outside nklock. Will patch that and retest.
> 
> Wasn't able to run all tests yet, but it looked promising so far. Will
> finish this on Monday.

Looks stable now according to the testers.

Jan

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