Re: [Xenomai-help] Problem with rt_queue

[Jan Kiszka <jan.kiszka@domain.hid>]

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mani bhatti wrote:
> Hi Phillipe and Jan 
> Thanks a lot for your help.I am sending the compilable
> source code so that you have an idea what wrong am i
> doing.I am sending the listeners which are listening
> to the same queue at the same time.But i dont know why
> at one time only one listener receives data from
> sender queue inspite of that i am using broadcast
> mode.Thanks a lot.I have attached files for sender and
> listener.

Well, interesting test case. It actually revealed bugs, but not where
expected.

Your problem is a simple bug in the listener tests. They both register a
task of the name "beta", only the first one succeeds (your code is a bit
hackish in this regard - when hunting problems, make sure to check ALL
return codes for potential problems!). Once fixed, your code runs fine here.

Nevertheless, queue_sender by itself uncovered a problem of
rt_queue_send in broadcast mode when no one is listening. The message
reference count got messed up and the queue ran out of memory. The
attached patch fixes it:

Jan

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Index: ksrc/skins/native/queue.c
===================================================================
--- ksrc/skins/native/queue.c	(Revision 1747)
+++ ksrc/skins/native/queue.c	(Arbeitskopie)
@@ -631,7 +631,9 @@ int rt_queue_send(RT_QUEUE *q, void *mbu
 			prependq(&q->pendq, &msg->link);
 		else
 			appendq(&q->pendq, &msg->link);
-	}
+	} else
+		/* Ownership did not change, so update reference count. */
+		msg->refcount++;
 
 	err = nrecv;
 
Index: ChangeLog
===================================================================
--- ChangeLog	(Revision 1748)
+++ ChangeLog	(Arbeitskopie)
@@ -1,3 +1,8 @@
+2006-10-26  Jan Kiszka  <jan.kiszka@domain.hid>
+
+	* ksrc/skins/native/queue.c (rt_queue_send): Track message count
+	correctly when broadcasting to a queue without listeners.
+
 2006-10-25  Jan Kiszka  <jan.kiszka@domain.hid>
 
 	* ksrc/drivers/testing/irqbench.c, doc/txt/irqbench.txt,

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