linux-kernel - Re: [PATCH RFC] raw: Remove the BKL from raw

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Message-Id: <200910190627.13368.arnd@arndb.de>
Date:	Mon, 19 Oct 2009 06:27:13 +0200
From:	Arnd Bergmann <arndbergmann@...glemail.com>
To:	John Kacur <jkacur@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Arnd Bergmann <arndbergmann@...glemail.com>,
	Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jonathan Corbet <corbet@....net>
Subject: Re: [PATCH RFC] raw: Remove the BKL from raw_open

On Sunday 18 October 2009, John Kacur wrote:
> The BKL was pushed into raw_open with
> commit c0bed680f0ca603864375ed5f9fed4296a53aa62
> 
> Jonathan's comments were " Put explicit lock_kernel() calls into raw_open(),
> even though the existing locking looks adequate."
> 
> I have to agree, the raw_mutex should provide all the protection needed here.

The raw driver uses the BKL in both the ioctl and the llseek function, so
I think you have to look if there is any interaction between those and the
open method, ideally removing it from all of them at the same time.

An unrelated bug I spotted while looking at your patch is that there is no
compat_ioctl method in the raw file_operations, which is really needed here
if you want any of the block ioctls to work on a compat task.

Whatever that tells us...

	Arnd <><
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