Message-ID: <400B7539.8080901@in.ibm.com>
Date: Mon, 19 Jan 2004 11:42:09 +0530
From: Prashanth T <prasht@in.ibm.com>
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To: Christoph Hellwig <hch@infradead.org>
CC: rml@tech9.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rwlock_is_locked undefined for UP systems
References: <4007EAE7.2030104@in.ibm.com> <20040116140933.C24102@infradead.org>
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ok....I understand that rwlock_is_locked( ) is to be protected by
CONFIG_SMP.  But I was tempted when I saw spin_is_locked( )
to be returning zero for !SMP in include/linux/spinlock.h . 
Am I seeing something wrong here?

Christoph Hellwig wrote:

>On Fri, Jan 16, 2004 at 07:15:11PM +0530, Prashanth T wrote:
>  
>
>>Hi,
>>    I had to use rwlock_is_locked( ) with linux2.6 for kdb and noticed that
>>this routine to be undefined for UP.  I have attached the patch for 2.6.1
>>below to return 0 for rwlock_is_locked( ) on UP systems.
>>Please let me know.
>>    
>>
>
>we don't implement spin_is_locked on UP either because there's no really
>usefull return value.  The lock will never be taken on !SMP && !PREEMPT,
>but OTOH it's also not needed, so any assert on will give false results.
>And the assert is probably the only thing that the _is_locked routines
>could used for sanely.
>
>
>  
>

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