From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH] thinkpad-acpi: fix potential suspend blocking issue
Date: Tue, 5 Mar 2013 19:05:42 +0100
Message-ID: <20130305180542.GA12738@redhat.com>
References: <201303042055.38040.maciej.rutecki@gmail.com> <1362504883-9180-1-git-send-email-msb@chromium.org> <20130305174838.GA7276@redhat.com> <CACBanvqHRDsOQiMsQMw5_QDt1wFrb8_DRoiASSvqeA6XdFrwZQ@mail.gmail.com>
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To: Mandeep Singh Baines <msb@chromium.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-acpi@vger.kernel.org, ibm-acpi@hmh.eng.br, ibm-acpi-devel@lists.sourceforge.net, platform-driver-x86@vger.kernel.org, Aaron Lu <aaron.lu@intel.com>, Henrique de Moraes Holschuh <hmh@hmh.eng.br>, Tejun Heo <tj@kernel.org>, Andrew Morton <akpm@linux-foundation.org>
List-Id: linux-acpi@vger.kernel.org

On 03/05, Mandeep Singh Baines wrote:
>
> On Tue, Mar 5, 2013 at 9:48 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> > On 03/05, Mandeep Singh Baines wrote:
> >>
> >> @@ -2462,13 +2462,13 @@ static int hotkey_kthread(void *data)
> >>       unsigned int poll_freq;
> >>       bool was_frozen;
> >>
> >> +     set_freezable();
> >> +
> >>       mutex_lock(&hotkey_thread_mutex);
> >>
> >>       if (tpacpi_lifecycle == TPACPI_LIFE_EXITING)
> >>               goto exit;
> >>
> >> -     set_freezable();
> >> -
> >
> > I don't understand this code... but don't we have the same problem
> > with kthread_freezable_should_stop() below? It can call __refrigerator()
> > too under the same lock.
> >
>
> I don't think the lock is held at that point. There is an unlock right
> before entering the while loop and at the bottom of the loop.

Hmm... Afaics this is another lock, hotkey_thread_data_mutex. But
hotkey_thread_mutex is still held.

Oleg.