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From: Christoph Hellwig <hch@infradead.org>
To: Takao Indoh <indou.takao@soft.fujitsu.com>
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Subject: Re: [PATCH 4/4][diskdump] x86-64 support
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In-Reply-To: <9AC48F3A62CFC4indou.takao@soft.fujitsu.com>; from indou.takao@soft.fujitsu.com on Tue, Aug 31, 2004 at 06:10:40PM +0900
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On Tue, Aug 31, 2004 at 06:10:40PM +0900, Takao Indoh wrote:
> >a spin_trylock would be safe.  hd can't be NULL.
> 
> Could you explain to me why spin_is_locked is not safe?

it's inherently racy.  Also it's always return 0 on UP systems which
makes it totally useless there.