Date: Sat, 11 Apr 2009 11:21:31 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Andrea Righi <righi.andrea@gmail.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>,
       Krzysztof Helt <krzysztof.h1@poczta.fm>,
       Eric Miao <eric.y.miao@gmail.com>, LKML <linux-kernel@vger.kernel.org>,
       Geert Uytterhoeven <geert@linux-m68k.org>,
       "Rafael J. Wysocki" <rjw@sisk.pl>,
       Andrey Borzenkov <arvidjaar@gmail.com>,
       "Antonino A. Daplas" <adaplas@gmail.com>,
       linux-fbdev-devel@lists.sourceforge.net,
       linux-pm@lists.linux-foundation.org, Dave Jones <davej@redhat.com>,
       Harvey Harrison <harvey.harrison@gmail.com>,
       Johannes Weiner <hannes@cmpxchg.org>, Pavel Roskin <proski@gnu.org>
Subject: Re: [REGRESSION] commit 66c1ca0: {fbmem: fix fb_info->lock and
 mm->mmap_sem ...} causes Xfbdev not working
Message-Id: <20090411112131.cc38dcf0.akpm@linux-foundation.org>
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On Sat, 11 Apr 2009 17:04:00 +0200 Andrea Righi <righi.andrea@gmail.com> wrote:

> fbdev: fix info->lock deadlock in fbcon_event_notify()
> 
> fb_notifier_call_chain() is called with info->lock held, i.e. in
> do_fb_ioctl() => FBIOPUT_VSCREENINFO => fb_set_var() and the some
> notifier callbacks, like fbcon_event_notify(), try to re-acquire
> info->lock again.
> 
> Remove the lock/unlock_fb_info() in all the framebuffer notifier
> callbacks' and be sure to always call fb_notifier_call_chain() with
> info->lock held.

Thanks.  So do you think we should proceed with this patch instead of
reverting 66c1ca0?
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