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Date: Wed, 19 Aug 2009 00:24:02 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Kumar Gala <galak@kernel.crashing.org>
cc: Linux-Kernel List <linux-kernel@vger.kernel.org>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       linuxppc-dev list <linuxppc-dev@ozlabs.org>,
       Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <peterz@infradead.org>,
       Steven Rostedt <rostedt@goodmis.org>
Subject: Re: spin_is_locked() broken for uniprocessor?
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On Tue, 18 Aug 2009, Kumar Gala wrote:
> I just want to validate that what I'm seeing (for UP, non-debug features):
> 
> spin_is_locked() is defined as:
> 
> include/linux/spinlock.h:#define spin_is_locked(lock)
> __raw_spin_is_locked(&(lock)->raw_lock)
> 
> for UP that should get us:
> 
> include/linux/spinlock_up.h:#define __raw_spin_is_locked(lock)  ((void)(lock),
> 0)
> 
> 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.

Thanks,

	tglx