Spurious task resume due to SIGSHADOW

I'm currently debugging an issue on a very old Xenomai system, while
reading the source I noticed that the very same issue could also exist
on recent Xenomai releases.

What I see is the following:
- A task gets suspended and unblocked using rt_task_suspend() and
rt_task_unblock()
- In some cases it happens that the task resumes to execute
- It resumes because a Linux signal is pending, being SIGSHADOW

Since SIGSHADOW is internally used to suspend a task, this alerted me.
So, I suspect the following issue:
When xnthread_suspend() fires SIGSHADOW using
__xnthread_signal(thread, SIGSHADOW, SIGSHADOW_ACTION_HARDEN); nothing
seems to prevent the case where the target task enters the primary
domain right before it sees SIGSHADOW. In the next step
do_sigwake_event() causes it to resume instead of sleeping.

Hmm?

-- 
Thanks,
//richard