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From: Arnd Bergmann <arnd@arndb.de>
To: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 2/3, RFC] watchdog dev BKL pushdown
Date: Tue, 20 May 2008 10:30:11 +0200
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Cc: Jonathan Corbet <corbet@lwn.net>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>,
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       Alexander Viro <viro@ftp.linux.org.uk>, linux-kernel@vger.kernel.org,
       Wim Van Sebroeck <wim@iguana.be>
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On Tuesday 20 May 2008, Christoph Hellwig wrote:
> On Tue, May 20, 2008 at 01:14:23AM +0200, Arnd Bergmann wrote:
> > The Big Kernel Lock has been pushed down from chardev_open
> > to misc_open, this change moves it to the individual watchdog
> > driver open functions.
> > 
> > As before, the change was purely mechanical, most drivers
> > should actually not need the BKL.
> 
> Actually I'd prefer to fix this for real.  This single open stuff aswell
> as same set of ioctls are duplicated all over the watchdog drivers.  We'd
> be much better off introducing a simple watchdog layer that handles this
> plus proper locking and convert drivers over to it gradually.

I fully agree, I thought the same thing when I did the patches. I remember
that Wim had a git tree doing this, which is still active at
http://git.kernel.org/?p=linux/kernel/git/wim/linux-2.6-watchdog-experimental.git;a=commitdiff;h=732c54027e6c866f98857c4a6d1c6c466459dcd5

Unfortunately, it hasn't seen much activitity over the last two years, and
the number of watchdog drivers seems to have exploded: I count 67 of them,
including some outside of drivers/watchdog.

Wim, was there anything preventing you from integrating the generic
watchdog layer back then?

	Arnd <><