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From: Kumar Gala <galak@kernel.crashing.org>
To: Linux-Kernel List <linux-kernel@vger.kernel.org>
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Subject: spin_is_locked() broken for uniprocessor?
Date: Tue, 18 Aug 2009 17:09:56 -0500
Cc: Thomas Gleixner <tglx@linutronix.de>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       linuxppc-dev list <linuxppc-dev@ozlabs.org>
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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.

- k