On 2011-08-26 20:07, Gilles Chanteperdrix wrote:
> On 08/26/2011 03:05 PM, Jan Kiszka wrote:
>> On 2011-08-26 14:34, Gilles Chanteperdrix wrote:
>>>
>>> Hi,
>>>
>>> I think it is about time we release Xenomai 2.6.0. Has anyone anything
>>> pending (maybe Alex)? Should we release an -rc first?
>>
>> No patches ATM, but [1] is still an open bug - a bug that affects the ABI.
>>
>> Jan
>>
>> [1] http://thread.gmane.org/gmane.linux.real-time.xenomai.devel/8343
>>
> 
> I had forgotten about this one. So, the only real problem is if a
> SCHED_NOTOTHER thread switches to SCHED_OTHER, this appears to be a
> corner case, so, I wonder if you should not simply add a special
> treatment, only for this corner case.
> 
> What I have in mind is keeping a list of xnsynch in kernel-space (this
> basically means having an xnholder_t more in the xnsynch structure), and
> when we trip the corner case (thread with SCHED_FIFO switches to
> SCHED_OTHER), walk the list to find how many xnsynch the thread is the
> owner, we have that info in kernel-space, and set the refcnt accordingly.
> 
> Or does it still sound overkill?
> 

Mmh, need to think about it. Yeah, we do not support
PTHREAD_MUTEX_INITIALIZER, so we do not share that part of the problem
with futexes.

If we have all objects and can explore ownership, we can also implement
robust mutexes this way, i.e. waiter signaling when the owner dies.

Jan

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

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