Re: [Xenomai-help] Suspended task resumed without rt_task_resume ?

[Philippe Gerum <rpm@xenomai.org>]

Tomas Kalibera wrote:
> Hi,
> 
> what can, besides an explicit call, resume a suspended task ? I created 
> and started a child task, then shadowed the current thread with T_SUSP 
> flag. The child was supposed to call rt_task_resume to wake-up the 
> parent and let it terminate the process, but, the parent was resumed 
> before this call. The call to rt_task_suspend in parent returned 0. The 
> program uses SIGALRM signal. Could this be the cause ?
>

Yes, but the syscall should be silently restarted by default. This patch should
fix the issue:

--- ksrc/skins/native/task.c	(revision 3698)
+++ ksrc/skins/native/task.c	(working copy)
@@ -410,11 +410,17 @@
  * A nesting count is maintained so that rt_task_suspend() and
  * rt_task_resume() must be used in pairs.
  *
+ * Receiving a Linux signal causes the suspended task to resume
+ * immediately.
+ *
  * @param task The descriptor address of the affected task. If @a task
  * is NULL, the current task is suspended.
  *
  * @return 0 is returned upon success. Otherwise:
  *
+ * - -EINTR is returned if a Linux signal has been received by the
+ * suspended task.
+ *
  * - -EINVAL is returned if @a task is not a task descriptor.
  *
  * - -EPERM is returned if the addressed @a task is not allowed to sleep
@@ -463,9 +469,12 @@
 		goto unlock_and_exit;
 	}

-	if (task->suspend_depth++ == 0)
+	if (task->suspend_depth++ == 0) {
 		xnpod_suspend_thread(&task->thread_base, XNSUSP,
 				     XN_INFINITE, XN_RELATIVE, NULL);
+		if (xnthread_test_info(task, XNBREAK))
+			err = -EINTR;
+	}

       unlock_and_exit:


-- 
Philippe.