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Date: Sat, 24 May 2014 23:17:37 +0200
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai] Question about scheduling and signals
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To: Matthias Schneider <ma30002000@yahoo.de>, "xenomai@xenomai.org" <xenomai@xenomai.org>

On 05/24/2014 10:50 PM, Matthias Schneider wrote:
> ----- Original Message -----
> 
>> From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
>> On 05/24/2014 09:55 PM, Matthias Schneider wrote:
>>>  ----- Original Message -----
>>>>  From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
> [...]
>>>
>>>  Why priMAX_COUNT + 1? Shouldnt vTaskSuspend be triggered when 
>>>  *pulCounter == priMAX_COUNT (which is actually is once task 1 gets
>>>  scheduled while task 2 is raising abort - at least my debugger tells me 
>>>  it is).
>>
>> The task1 first suspends when pulCounter == priMAX_COUNT, right?
>> Then you wake it up, so, since there is a for loop, it will do
>>
>>>>>     (*pulCounter)++;
>>>>>     if( *pulCounter >= priMAX_COUNT )
>>>>>        vTaskSuspend(NULL); // -> wait for signal SIGRESM
>>
>> So, now task 1 is suspended again, and *pulCounter == priMAX_COUNT + 1
> 
> 
> 
> You are right, I forgot to include an essential piece of code in my 
> first snippet(sorry about that):
> 
> //Task 1, prio 1 / SCHED_FIFO
> 
> vTaskSuspend(NULL); // forgot this in my first snippet
> for(;;) {
> 
>   (*pulCounter)++;
>   if( *pulCounter >= priMAX_COUNT )
>      vTaskSuspend(NULL);
> }
> 
> //Task 2, prio 0 / SCHED_OTHER
> vTaskSuspendAll();
> vTaskResume(xLimitedIncrementHandle);
> xTaskResumeAll(); 
>                  
> if (ulCounter != priMAX_COUNT)
>   raise(SIGABRT);
> 
> 
> Now task will block in the first suspend. Task 2 will do its thing,
> and when task 2's priority gets lowered, I would expect task 1 being
> scheduled right away, increasing the counter up to priMAX_COUNT, before
> task 2 is scheduled again when task 1 enters the second vTaskSuspend.
> However, ulCounter seems to be 0 when SIGABRT is raised.

Are you running an uniprocessor, or multi-processor system?

-- 
                                                                Gilles.