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Date: Fri, 21 Nov 2008 16:03:15 +0100
From: Philippe Gerum <rpm@xenomai.org>
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Subject: Re: [Xenomai-core] [PATCH] Catch multiple xnshadow_map attempts
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: xenomai-core <xenomai@xenomai.org>

Philippe Gerum wrote:
> Jan Kiszka wrote:
>> Philippe Gerum wrote:
>>> Jan Kiszka wrote:
>>>> My customer managed to find another hidden door to Xenomai's hell:
>>>> Trying to create a Xenomai POSIX thread from within a native thread. A
>>>> think the other way around would "work" as well. The precise scenario
>>>> was native thread -> dlopen(libs that's linked against libpthread_rt) ->
>>>> __init_posix_interface -> __wrap_pthread_setschedparam -> oops. That
>>>> scenario revealed two more issues in fact.
>>>>
>>>> Here is a patch to remove this hell gate by catching xnshadow_map
>>>> invocations from withing already mapped shadow thread.
>>>>
>>> Any reason why the XNMAPPED predicate did not work in your case?
>> Sorry, which one? Keep in mind that the thread thrown at the second
>> xnshadow_map is a virgin one, just allocated from scratch.
>>
> 
> Ok, got it, it's the converse case, so let's deal for that:
> 
> --- ksrc/nucleus/shadow.c	(revision 4411)
> +++ ksrc/nucleus/shadow.c	(working copy)
> @@ -1331,7 +1331,7 @@
>   * case, the real-time mapping operation has failed globally, and no
>   * Xenomai resource remains attached to it.
>   *
> - * - -EINVAL is returned if the thread control block does not bear the
> + * - -EBUSY is returned if the thread control block does not bear the
>   * XNSHADOW bit, or if the thread has already been mapped.
>   *
>   * Environments:
> @@ -1354,8 +1354,8 @@
>  	if (!xnthread_test_state(thread, XNSHADOW))
>  		return -EINVAL;
> 
> -	if (xnthread_test_state(thread, XNMAPPED))
> -		return -EINVAL;
> +	if (xnshadow_thread(current) || xnthread_test_state(thread, XNMAPPED))
> +		return -EBUSY;
> 
>  	if (!access_wok(u_mode, sizeof(*u_mode)))
>  		return -EFAULT;
> 

--- ksrc/nucleus/shadow.c	(revision 4411)
+++ ksrc/nucleus/shadow.c	(working copy)
@@ -1332,8 +1332,10 @@
  * Xenomai resource remains attached to it.
  *
  * - -EINVAL is returned if the thread control block does not bear the
- * XNSHADOW bit, or if the thread has already been mapped.
+ * XNSHADOW bit.
  *
+ * - -EBUSY is returned if the thread has already been mapped.
+ *
  * Environments:

-- 
Philippe.