Date: Sun, 11 Oct 2009 16:54:08 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Arjan van de Ven <arjan@infradead.org>
Cc: John Kacur <jkacur@redhat.com>, linux-kernel@vger.kernel.org,
       Thomas Gleixner <tglx@linutronix.de>,
       Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Christoph Hellwig <hch@infradead.org>, Jonathan Corbet <corbet@lwn.net>,
       Andrew Morton <akpm@linux-foundation.org>,
       Vincent Sanders <vince@simtec.co.uk>, linux-scsi@vger.kernel.org
Subject: Re: [PATCH RFC] [PATCH] drivers/scsi/ch.c: Remove BKL in ch_open
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> > I'm not so sure. In fact there are some quite umm interesting
> > questions about this code, and some of them are shared with other
> > modules too.
> > 
> > Consider the following sequence
> > 
> > 		CPU1				CPU2
> > 	register_chrdev
> > 		ok
> > 						open device
> > 						takes lock
> 
> 
> but open does not take the BKL, so the BKL is not protecting you at
> all against this..

But module load/unload does - so while the change doesn't appear to cause
any problems there is an underlying problem here that wants looking at.
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