From: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mundt <lethal@linux-sh.org>,
linux-fbdev@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Francis Moreau <francis.moro@gmail.com>
Subject: Re: Possible deadlock when suspending framebuffer
Date: Tue, 14 Jun 2011 19:04:20 +0000 [thread overview]
Message-ID: <4DF7B0B4.4060002@gmx.de> (raw)
In-Reply-To: <BANLkTimny9nzr23TufH1kMcsk57M3NXuaA@mail.gmail.com>
Hi Linus,
On 06/14/2011 06:15 PM, Linus Torvalds wrote:
> Paul, fbdev people.. Comments? This was sent to me and lkml, the right
> people probably didn't see it.
Sounds very familiar. Indeed a quick glance at my archive revealed 2
approaches/patches dealing with similar issues
http://marc.info/?l=linux-fbdev&m\x129539210207429&w=2
http://marc.info/?l=linux-fbdev&m\x129700789632450&w=2
I did not have time to verify that those do actually get those things right
everywhere but the first one looks good and should also solve this issue I think.
Regards,
Florian Tobias Schandinat
>
> I doubt it's a big problem in practice, but..
>
> Linus
>
> On Tue, Jun 14, 2011 at 6:10 AM, Francis Moreau<francis.moro@gmail.com> wrote:
>> Hello,
>>
>> I noticed that a possible deadlock can happen when the current frame
>> buffering is being suspended and a new frambuffer device is being
>> registred at the same time.
>>
>> When suspending the current frambuffer by doing : echo 1
>>> /sys/class/graphics/fb0/state, the kernel actually takes the
>> following locks in that order: console_lock, lock_fb_info (see
>> store_fbstate()).
>>
>> However when a new framebuffer is coming in, the lock sequence is:
>> lock_fb_info (taken by do_remove_conflicting_framebuffer()),
>> console_lock() (taken by unbind_console).
>>
>> I don't know how this should be fixed though...
>>
>> Thanks
>> --
>> Francis
>>
> --
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>
next prev parent reply other threads:[~2011-06-14 19:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <BANLkTiko+2AM8dq8jP5xjbTcCM63hBAK=A@mail.gmail.com>
2011-06-14 18:15 ` Possible deadlock when suspending framebuffer Linus Torvalds
2011-06-14 19:04 ` Florian Tobias Schandinat [this message]
2011-06-17 18:46 ` [PATCH] fb: avoid possible deadlock caused by fb_set_suspend Florian Tobias Schandinat
2011-06-18 8:43 ` Bruno Prémont
2011-06-18 9:19 ` Bruno Prémont
2011-09-01 15:42 ` Florian Tobias Schandinat
2011-09-01 16:28 ` Guennadi Liakhovetski
2011-09-02 16:06 ` Guennadi Liakhovetski
2011-09-02 16:46 ` Florian Tobias Schandinat
2011-09-02 17:24 ` [PATCH] fb: sh-mobile: Fix deadlock risk between lock_fb_info() and Bruno Prémont
2011-09-02 20:54 ` [PATCH] fb: sh-mobile: Fix deadlock risk between lock_fb_info() Florian Tobias Schandinat
2011-07-20 18:16 ` [PATCH] fb: avoid possible deadlock caused by fb_set_suspend Florian Tobias Schandinat
2011-07-28 22:10 ` Francis Moreau
2011-06-15 1:09 ` re:Possible deadlock when suspending framebuffer Wanlong Gao
2011-06-15 5:58 ` Possible " Bruno Prémont
2011-06-15 6:22 ` Wanlong Gao
2011-06-15 7:04 ` Américo Wang
2011-06-15 7:12 ` Francis Moreau
2011-06-15 10:20 ` Bruno Prémont
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