Re: [Xenomai-help] :: rt_printf with daemonized task

[oliver.schlenker@domain.hid]

-------- Original Message --------
Subject: Re: :: rt_printf with daemonized task (20-Okt-2009 11:33)
From:    Jan Kiszka <jan.kiszka@siemens.com>
To:      oliver.schlenker@smmotioncontrol.de

> 
> See http://thread.gmane.org/gmane.linux.real-time.xenomai.devel/6571 for
> an example of a patch that may (but need not) be generated via git. What
> counts is the format: proper title, a few lines of description, signed-off.
> 
> HTH,
> Jan
> 

ok, here is my next trial for a proper patch


Oliver


----------------------------------------------------------------------------------------------

Subject : Fork-save use of rt_print

Fork save initialisation of rt_print library, necessary child initialisation are
done via pthread_atfork() when child process is started.

Signed-off-by: Oliver Schlenker <oliver.schlenker <at> sm motion control.de>
---

--- rt_print.c.original	2008-09-10 10:36:27.000000000 +0200
+++ rt_print.c.forkonly	2009-10-16 16:19:25.949289800 +0200
                    
 	}
 }
 
-void __rt_print_init(void)
+static void spawn_printer_thread(void)
 {
 	pthread_attr_t thattr;
+
+	pthread_attr_init(&thattr);
+	pthread_attr_setstacksize(&thattr, PTHREAD_STACK_MIN);
+	pthread_create(&__printer_thread, &thattr, printer_loop, NULL);
+}
+
+static void forked_child_init(void)
+{
+	struct print_buffer *my_buffer = pthread_getspecific(__buffer_key);
+	struct print_buffer **pbuffer = &__first_buffer;
+
+	/* re-init to avoid finding it locked by some parent thread */
+	pthread_mutex_init(&__buffer_lock, NULL);
+
+	while (*pbuffer) {
+		if (*pbuffer == my_buffer)
+			pbuffer = &(*pbuffer)->next;
+		else
+			cleanup_buffer(*pbuffer);
+	}
+
+	spawn_printer_thread();
+}
+
+void __rt_print_init(void)
+{
 	const char *value_str;
 	unsigned long long period;
 
                   
 	pthread_mutex_init(&__buffer_lock, NULL);
 	pthread_key_create(&__buffer_key, (void (*)(void*))cleanup_buffer);
 
-	pthread_attr_init(&thattr);
-	pthread_attr_setstacksize(&thattr, PTHREAD_STACK_MIN);
-	pthread_create(&__printer_thread, &thattr, printer_loop, NULL);
+	spawn_printer_thread();
+	pthread_atfork(NULL, NULL, forked_child_init);
 } 




To: jan.kiszka@siemens.com
Cc: gilles.chanteperdrix@xenomai.org
    xenomai-help@gna.org