Re: [Xenomai-core] [bug] zombie mutex owners

[Philippe Gerum <rpm@xenomai.org>]

Jan Kiszka wrote:
> Philippe Gerum wrote:
> 
>>Jan Kiszka wrote:
>>
>>>Dmitry Adamushko wrote:
>>>
>>>Indeed, this solves the issue more gracefully.
>>>
>>>Looking at this again from a different perspective and running the test
>>>case with your patch in a slightly different way, I think I
>>>misinterpreted the crash. If I modify task2 like this
>>>
>>>void task2_fnc(void *arg)
>>>{
>>>        printf("started task2\n");
>>>        if (rt_mutex_lock(&mtx, 0) < 0) {
>>>                printf("lock failed in task2\n");
>>>                return;
>>>        }
>>>//        rt_mutex_unlock(&mtx);
>>>
>>>        printf("done task2\n");
>>>}
>>>
>>>I'm also getting a crash. So the problem seems to be releasing a mutex
>>>ownership on task termination. Well, this needs further examination.
>>>
>>
>>The native skin does not implement robust mutex, indeed.
> 
> 
> Yeah, lunch opened my eyes: the skin data structure (RT_MUTEX) is not
> updated appropriately on task cleanup. What about some callback hook in
> xnsynch_t to invoke a per-skin cleanup handler when running
> xnsynch_release_all_ownerships?
> 

Yep, we need this. Added by commit #1067 (i.e. 
xnsynch_register_cleanup()) and also backported to the maintenance 
branch, so that new code may happily rely on it without too much 
portability burden.

-- 

Philippe.