From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Wed, 01 Feb 2006 19:23:52 +0100
From: Philippe Gerum <rpm@xenomai.org>
MIME-Version: 1.0
Subject: Re: [Xenomai-core] [PATCH] fix pthread cancellation in native skin
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: xenomai-core <xenomai@xenomai.org>

Gilles Chanteperdrix wrote:
> Gilles Chanteperdrix wrote:
>  > This is not the only situation where a thread with a nucleus suspension
>  > bit need to run shortly in secondary mode: it also occurs when
>  > suspending with xnpod_suspend_thread() a thread running in secondary
>  > mode; the thread receives the SIGCHLD signal and need to execute shortly
>  > with the suspension bit set in order to cause a migration to primary
>  > mode.
>  > 
>  > So, the only case when we are sure that a user-space thread can not be
>  > scheduled by Linux seems to be when this thread does not have the
>  > XNRELAX bit.
> 
> From all the bits in XNTHREAD_BLOCK_BITS, only when the XNPEND bit is
> set, a thread can not be running in secondary mode. Hence the proposed
> patch.
> 

Almost ok, but XNDELAY might also be set alone, indicating a purely timed wait 
state (i.e. without sync object to pend on, so XNPEND is off).

> 
> 
> ------------------------------------------------------------------------
> 
> Index: ksrc/nucleus/shadow.c
> ===================================================================
> --- ksrc/nucleus/shadow.c	(revision 507)
> +++ ksrc/nucleus/shadow.c	(working copy)
> @@ -1543,14 +1543,25 @@
>  
>  #ifdef CONFIG_XENO_OPT_DEBUG
>  	{
> -	xnflags_t status = threadin->status & ~XNRELAX;
> +	xnflags_t status = threadin->status;
>  	int sigpending = signal_pending(next);
>  
> -        if (!(next->ptrace & PT_PTRACED) &&
> +        if (!testbits(status, XNRELAX))
> +            {
> +            show_stack(xnthread_user_task(threadin),NULL);
> +            xnpod_fatal("Hardened thread %s[%d] running in Linux domain?! (status=0x%lx, sig=%d, prev=%s[%d])",
> +			threadin->name,
> +			next->pid,
> +			status,
> +			sigpending,
> +			prev->comm,
> +			prev->pid);
> +	    }
> +        else if (!(next->ptrace & PT_PTRACED) &&
>  	    /* Allow ptraced threads to run shortly in order to
>  	       properly recover from a stopped state. */
>  	    testbits(status,XNSTARTED) &&
> -	    testbits(status,XNTHREAD_BLOCK_BITS))
> +	    testbits(status,XNPEND))
>  	    {
>  	    show_stack(xnthread_user_task(threadin),NULL);
>              xnpod_fatal("blocked thread %s[%d] rescheduled?! (status=0x%lx, sig=%d, prev=%s[%d])",
> 
> 
> ------------------------------------------------------------------------
> 
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-- 

Philippe.