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Subject: Re: spin_is_locked() broken for uniprocessor?
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Peter Zijlstra <peterz@infradead.org>
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Date: Thu, 27 Aug 2009 19:32:34 +1000
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Cc: Linux-Kernel List <linux-kernel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
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	Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>
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On Wed, 2009-08-19 at 11:41 +0200, Peter Zijlstra wrote:
> > > > which implies to me that spin_is_locked() will always return
> false.  Is this
> > > > expected behavior.
> > > 
> > > That's wrong. spin_is_locked should always return true on UP.
> > 
> > Surely it's not that simple?  Maybe spin_is_lock() should be
> undefined on UP.
> 
> #define spin_is_locked(l) panic()
> 
> should sort things out quickly ;-)

Not defining it would sort things out even faster and avoid nasty case
of system panic'ing when a module is loaded :-)

Cheers,
Ben.