Date: Wed, 14 Oct 2009 17:12:49 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org,
       gregkh@suse.de, tglx@linutronix.de
Cc: tglx@linutronix.de, linux-tip-commits@vger.kernel.org,
       linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com,
       gregkh@suse.de
Subject: Re: [tip:bkl/drivers] drivers: Remove BKL from misc_open
Message-ID: <20091014171249.57dcdcfc@lxorguk.ukuu.org.uk>
In-Reply-To: <tip-40b798efe3460797a4ac928ee2e038774e2758eb@git.kernel.org>
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	<tip-40b798efe3460797a4ac928ee2e038774e2758eb@git.kernel.org>
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On Wed, 14 Oct 2009 15:47:39 GMT
tip-bot for Thomas Gleixner <tglx@linutronix.de> wrote:

> Commit-ID:  40b798efe3460797a4ac928ee2e038774e2758eb
> Gitweb:     http://git.kernel.org/tip/40b798efe3460797a4ac928ee2e038774e2758eb
> Author:     Thomas Gleixner <tglx@linutronix.de>
> AuthorDate: Sat, 10 Oct 2009 15:35:43 +0000
> Committer:  Thomas Gleixner <tglx@linutronix.de>
> CommitDate: Wed, 14 Oct 2009 17:33:32 +0200
> 
> drivers: Remove BKL from misc_open
> 
> misc_open() is already serialized with misc_mtx. Remove the BKL
> locking which got there via the BKL pushdown.

NAK.

You can't simply assume the mutex is enough - you have to either push it
down or review *every* possible called point below the lock_kernel take.

In this case the open method of the misc devices below sometimes uses the
BKL.
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