Re: [Xenomai-help] pthread cancelation and scheduling magics

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Gilles Chanteperdrix wrote:
>>> Now, the question is, do you realistically plan to write an application
>>> which makes no syscall in its real-time loop?
>> Unlikely, but it may happen in case of programming errors. Anyhow, the
>> pthreads will run legacy code and it would be a pain to add
>> pthread_testcancel where necessary. But maybe there is a more elegant
>> and simple solution to do a defined exit/abort.
> 
> In case of programming error, enable the xenomai watchdog, it will
> forcibly kill the problematic thread.

To give you a more complete answer: most blocking functions are
cancellation points in the PTHREAD_CANCEL_DEFERRED case, so, you
probably do not need to add pthread_testcancel at all. The only
exception is pthread_mutex_lock: this way, cancellation happens for well
defined mutex states, and you may install cleanup handlers with
pthread_cleanup_push/pthread_cleanup_pop if ever a thread may be
destroyed while holding a mutex. With PTHREAD_CANCEL_ASYNCHRONOUS, the
situation is not that clean.

-- 
                                                 Gilles.