linux-kernel - Re: [PATCH] thinkpad-acpi: fix potential suspend blocking issue

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Message-ID: <20130306201849.GA4897@thinkpad.lan>
Date:	Thu, 7 Mar 2013 00:18:49 +0400
From:	Artem Savkov <artem.savkov@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Mandeep Singh Baines <msb@...omium.org>,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	ibm-acpi@....eng.br, ibm-acpi-devel@...ts.sourceforge.net,
	platform-driver-x86@...r.kernel.org, Aaron Lu <aaron.lu@...el.com>,
	Henrique de Moraes Holschuh <hmh@....eng.br>,
	Tejun Heo <tj@...nel.org>,
	Maciej Rutecki <maciej.rutecki@...il.com>
Subject: Re: [PATCH] thinkpad-acpi: fix potential suspend blocking issue

On Wed, Mar 06, 2013 at 04:50:39PM +0100, Oleg Nesterov wrote:
> On 03/05, Andrew Morton wrote:
> >
> > Basically the same as
> > http://ozlabs.org/~akpm/mmots/broken-out/drivers-platform-x86-thinkpad_acpic-move-hotkey_thread_mutex-lock-after-set_freezable.patch.
> >  I think Artem's patch is a little better.  There doesn't appear to be
> > any locking protocol for tpacpi_lifecycle.
> 
> Which seems to have the same problem, hotkey_kthread() still calls
> kthread_freezable_should_stop() under hotkey_thread_mutex.
> 
> IOW, we have two try_to_freeze's here, the patch moves only one of
> them outside of the hotkey_thread_mutex.

It's hard for me to judge but this lock does indeed look like it has
been used to block until the thread exits. I'm trying out the "remove
hotkey_thread_mutex completely" approach and everything looks fine so
far.

-- 
Regards,
Artem
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