Re: Xenomai 3: Wierd problem resuming task

["Mauro S." <mau.salvi@tin.it>]

Il 16/07/21 11:47, Jan Kiszka ha scritto:
> On 16.07.21 11:45, Mauro S. via Xenomai wrote:
>> Hi,
>>
>> I'm using Xenomai3 (master branch, commit
>> bca41678742be80c3a0d5a01935c671c385a95a1) on a X86_64bit Intel Atom
>> x5-E8000 with 2GB RAM, using kernel from Xenomai repos, in Cobalt
>> coniguration. SMI workaround is enabled and all latency tests are good.
>>
>> I'm facing with a very weird problem in my application. I have some
>> tasks with priority < 90 that call rt_task_suspend() on themselves.
>> Then, I have a task with priority 99 that resumes all other tasks with
>> rt_task_resume(), when they are suspended.
>>
>> Sometimes a task does not get resumed.
>>
>> In /proc/xenomai/sched/stat I have this status for my suspendend task:
>>
>> CPU  PID    MSW        CSW        XSC        PF    STAT       %CPU  NAME
>>    1  620    3          8          13         0     00048041    0.0  t12
>>
>> Analizing the scenario attaching gdb to the application, I observe that
>> the not-resuming task has this backtrace:
>>
>> #0  0x00007f0ec14c9b38 in __cobalt_kill (pid=620, sig=65) at signal.c:100
>> 100    signal.c: No such file or directory.
>> (gdb) bt
>> #0  0x00007f0ec14c9b38 in __cobalt_kill (pid=620, sig=65) at signal.c:100
>> #1  0x00007f0ec14eb379 in threadobj_suspend
>> (thobj=thobj@entry=0x7f0ec06bfcd0) at threadobj.c:335
>> #2  0x00007f0ec15013dc in rt_task_suspend (task=task@entry=0x0) at
>> task.c:1154
>>
>> that seems to me OK. If I understood correctly, it is locked in its
>> SIGSUSP handler, that calls sigsuspend() waiting SIGRESM to "restart".
>>
>> Then, I placed some breakpoints where rt_task_resume() were called, and
>> in rt_task_resume() itself. I set tcb->suspends=1 with GDB and followed
>> the subsequent call of threadobj_resume(). Then, I placed some
>> breakpoints in threadobj_resume, I forced __THREAD_S_SUSPENDED bit in
>> thobj->status, and I observed that __RT(kill(thobj->pid, SIGRESM)) got
>> called, with a retval 0. thobj->pid has the right value.
>>
>> But the suspended task does not get resumed.
>>
>> Any idea/suggestion?
>>
> 
> Can you derive a sharable simple test case from this? That will ensure
> we are not misinterpreting what you code actually does.
> 
> Jan
> 


I will try to reduce the application code to a simple test, but I'm not 
sure to succeed.
I will get back to you anyway.

Thanks.

--
Mauro