From: Arnd Bergmann <arnd@arndb.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [GIT PULL v2] Preparation for BKL'ed ioctl removal
Date: Sat, 24 Apr 2010 21:54:02 +0200
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Cc: Frederic Weisbecker <fweisbec@gmail.com>,
       LKML <linux-kernel@vger.kernel.org>,
       Thomas Gleixner <tglx@linutronix.de>, Al Viro <viro@zeniv.linux.org.uk>,
       Jan Blunck <jblunck@suse.de>, Ingo Molnar <mingo@elte.hu>,
       John Kacur <jkacur@redhat.com>
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On Saturday 24 April 2010 20:47:17 Linus Torvalds wrote:
> On Sat, 24 Apr 2010, Linus Torvalds wrote:
> >
> > I don't see the point, frankly. Especially not outside the merge window, 
> > but quite frankly, I don't see it in general. The whole thing seems to be 
> > designed to be inconvenient, and to have a config option that I 
> > fundamentally don't believe in (CONFIG_BKL).
> 
> More detail: it still leaves that old "ioctl" function pointer that needs 
> the BKL and is ungreppable. So the whole and only point of the patch is to 
> make our current mess even more complex, with three different cases. No, 
> thank you.
> 
> Quite frankly, if you want to get rid of the BKL in ioctl's and make them 
> easily greppable, then I would suggest a simple renaming: rename the 
> current '->ioctl()' thing to '->bkl_ioctl()', and mark it deprecated. No 
> new config options, no new games. Just rename it. No need to mark things 
> with CONFIG_BKL, when you can just see it by virtue of them using 
> 'bkl_ioctl'.

We want to do the rename in the next merge window and remove the old
->ioctl(), this patch is just a preparation for this so we can start
queuing the patches for the rename in maintainer trees.
The addition of the deprecated_ioctl() helper is not essential but
let's us move all BKL users into loadable modules next.

The CONFIG_BKL stuff is not a requirement for doing this, but something
we /also/ want to do in the next merge window, i.e. mark all BKL users
as CONFIG_BKL, not just the ones that use the locked_ioctl (or bkl_ioctl).

I agree that it's now a bit late for this, but when I initially suggested
this (before -rc3, IIRC), that would have given us the chance to queue up
all the patches with a dependency on this for the next merge window.
Now the current outlook is probably that we do a lot of the preparation
work like this patch in 2.6.35-rc1, which moves the merge of the interesting
parts out to the 2.6.36 timeframe.

	Arnd
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