linux-kernel - Re: [PATCH] fb: Rework locking to fix lock ordering on takeover

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Message-ID: <CA+5PVA6nKNZY70UoeDUhQo9Rj4Ck+k+XTHL++gwErgzqAdy6Aw@mail.gmail.com>
Date:	Wed, 21 Nov 2012 07:45:45 -0500
From:	Josh Boyer <jwboyer@...il.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	linux-kernel@...r.kernel.org, florianschandinat@....de
Subject: Re: [PATCH] fb: Rework locking to fix lock ordering on takeover

On Fri, Nov 16, 2012 at 2:27 PM, Alan Cox <alan@...rguk.ukuu.org.uk> wrote:
>
> [The fb maintainer appears to be absent at the moment].
>
> This is needed to fix a pile of lockdep splats that now show up because console_lock()
> is being properly audited. Hugh Dickins and Sasha Levin have tested it and both reports
> all looks good. This is probably not the whole story - the entire fb layer has locking
> confusion problems that were previously hidden but it seems to get the ones people hit
> in testing. This hopefully explains a few of the weird fb hangs that have been floating
> around forever.
>
> From: Alan Cox <alan@...ux.intel.com>
>
> Adjust the console layer to allow a take over call where the caller already
> holds the locks. Make the fb layer lock in order.
>
> This s partly a band aid, the fb layer is terminally confused about the
> locking rules it uses for its notifiers it seems.
>
> Signed-off-by: Alan Cox <alan@...ux.intel.com>

Should this eventually get into the stable trees?

josh
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