From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Thu, 09 Jun 2011 15:34:18 +0200
From: Wolfgang Grandegger <wg@domain.hid>
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Subject: Re: [Xenomai-core] Oops with synchronous message passing support
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To: Philippe Gerum <rpm@xenomai.org>
Cc: xenomai-core <xenomai@xenomai.org>

Hi Philippe,

On 06/09/2011 03:05 PM, Philippe Gerum wrote:
> On Thu, 2011-06-09 at 14:42 +0200, Wolfgang Grandegger wrote:
>> Hello,
>>
>> I just realized a problem with synchronous message passing support. When
>> rt_task_send() send times out, I get the oops below from line:
>>
> 
> Does this help?
> 
> diff --git a/ksrc/skins/native/task.c b/ksrc/skins/native/task.c
> index b822fd0..b0e99a7 100644
> --- a/ksrc/skins/native/task.c
> +++ b/ksrc/skins/native/task.c
> @@ -1988,21 +1988,28 @@ int rt_task_receive(RT_TASK_MCB *mcb_r, RTIME timeout)
>  	}
>  
>  	/*
> -	 * Wait on our receive slot for some client to enqueue itself
> -	 * in our send queue.
> +	 * We loop to care for spurious wakeups, in case the
> +	 * client times out before we unblock.
>  	 */
> -	info = xnsynch_sleep_on(&server->mrecv, timeout, XN_RELATIVE);
> -	/*
> -	 * XNRMID cannot happen, since well, the current task would be the
> -	 * deleted object, so...
> -	 */
> -	if (info & XNTIMEO) {
> -		err = -ETIMEDOUT;	/* Timeout. */
> -		goto unlock_and_exit;
> -	} else if (info & XNBREAK) {
> -		err = -EINTR;	/* Unblocked. */
> -		goto unlock_and_exit;
> -	}
> +	do {
> +		/*
> +		 * Wait on our receive slot for some client to enqueue
> +		 * itself in our send queue.
> +		 */
> +		info = xnsynch_sleep_on(&server->mrecv, timeout, XN_RELATIVE);
> +		/*
> +		 * XNRMID cannot happen, since well, the current task
> +		 * would be the deleted object, so...
> +		 */
> +		if (info & XNTIMEO) {
> +			err = -ETIMEDOUT;	/* Timeout. */
> +			goto unlock_and_exit;
> +		}
> +		if (info & XNBREAK) {
> +			err = -EINTR;	/* Unblocked. */
> +			goto unlock_and_exit;
> +		}
> +	} while (!xnsynch_pended_p(&server->mrecv));
>  
>  	holder = getheadpq(xnsynch_wait_queue(&server->msendq));
>  	/* There must be a valid holder since we waited for it. */

Yes, it does help:

  -bash-3.2# ./oops_sender
  pre-rt_task_receive()
  rt_task_send() failed: -110 (Connection timed out)
  Killing child

No more oops, thanks for your quick help.

Wolfgang.