Date: Fri, 16 Jan 2004 14:09:33 +0000
From: Christoph Hellwig <hch@infradead.org>
To: Prashanth T <prasht@in.ibm.com>
Cc: rml@tech9.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rwlock_is_locked undefined for UP systems
Message-ID: <20040116140933.C24102@infradead.org>
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	Prashanth T <prasht@in.ibm.com>, rml@tech9.net,
	linux-kernel@vger.kernel.org
References: <4007EAE7.2030104@in.ibm.com>
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In-Reply-To: <4007EAE7.2030104@in.ibm.com>; from prasht@in.ibm.com on Fri, Jan 16, 2004 at 07:15:11PM +0530
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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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