Hello,

I ran into a problem with the automatically spawned printf thread.

Short summary:
The kernel delivers signals by picking a thread that can accept a signal and 
does not mask the specific signal,
only if none is available then the signal will be queued for asynchronous 
delivery.
signalfd is asynchronous delivery, thus if one thread accepts signals then 
signalfd won't work as expected,
enter cobals printf thread.

Solutions would be:

- Mask all signals for this thread (is there any downside?)
- Mask all signals on the main thread before calling xenomai_init. This is 
ugly, as that removes most methods of interacting with a hung startup.
- Somehow mask the thread for signals later (only ugly solutions?).

The first option would be a rather small patch:

@@ -642,7 +642,11 @@ static void spawn_printer_thread(void)
 pthread_attr_t thattr;

 pthread_attr_init(&thattr);
+sigset_t sset, oset;
+sigfillset(&sset)
+sigprocmask(SIG_BLOCK, &sset, &oset);
 pthread_create(&printer_thread, &thattr, printer_loop, NULL);
+sigprocmask(SIG_SETMASK, &oset, NULL);
 }

Mit besten Grüßen / Kind regards

NORBERT LANGE
AT-DES

ANDRITZ HYDRO GmbH
Eibesbrunnergasse 20
1120 Vienna / AUSTRIA
p: +43 50805 56684
norbert.la...@andritz.com
andritz.com
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