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Date: Wed, 03 Dec 2008 19:32:25 +0100
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-help] pthread cancelation and scheduling magics
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To: Wolfgang Grandegger <wg@domain.hid>
Cc: xenomai-help <xenomai@xenomai.org>

Wolfgang Grandegger wrote:
> Gilles Chanteperdrix wrote:
>> Wolfgang Grandegger wrote:
>>> Running under gdb shows:
>>>
>>>   Program received signal SIGSEGV, Segmentation fault.
>>>   [Switching to Thread 0x4885d4b0 (LWP 1127)]
>>>   0x0ff49100 in pthread_cancel () from /lib/libpthread.so.0
>>>   (gdb) where
>>>   #0  0x0ff49100 in pthread_cancel () from /lib/libpthread.so.0
>>>   #1  0x10001d64 in ctrl_func (parm=0x0) at cancel-test.c:104
>>>   #2  0x0ffa98e4 in __pthread_trampoline ()
>>>      from /home/wolf/xenomai/lib/libpthread_rt.so.1
>>>   #3  0x0ff42a6c in start_thread () from /lib/libpthread.so.0
>>>   #4  0x0fdd18a0 in clone () from /lib/libc.so.6
>>>   Backtrace stopped: previous frame inner to this frame (corrupt stack?)
>>>
>>> Is pthread_cancel used from the Linux pthread library? And
>>> pthread_testcancel() as well?
>> Yes, and I guess, as you said, that it happens because calc_func is dead
>> when you try and cancel it.
> 
> Yep, but it should not crash.

The spec says:
The pthread_cancel() function may fail if:

[ESRCH]
    No thread could be found corresponding to that specified by the
given thread ID.


So, it is a "may", returning ESRCH, as Xenomai does in kernel-space, is
not mandatory.

-- 
                                                 Gilles.