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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Aaron Lu <aaron.lu@intel.com>
Cc: Kui Zhang <kuizhang@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        ACPI Devel Mailing List <linux-acpi@vger.kernel.org>,
        Zhang Rui <rui.zhang@intel.com>
Subject: Re: rmmod thermal, unable to handle kernel NULL pointer dereference
Date: Mon, 26 May 2014 14:53:16 +0200
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On Wednesday, May 21, 2014 04:22:58 PM Aaron Lu wrote:
> On 05/21/2014 01:57 PM, Kui Zhang wrote:
> > Hello,
> > 
> > I get following error when rmmod thermal.
> > 
> > rmmod  thermal
> > Killed
> 
> Thanks for the report. Here is a fix patch that should solve this
> problem.
> 
> From: Aaron Lu <aaron.lu@intel.com>
> Date: Wed, 21 May 2014 16:00:42 +0800
> Subject: [PATCH] ACPI / thermal: fix workqueue destroy order
> 
> When the thermal module is to be removed, we should destroy the wq
> acpi_thermal_pm_queue after the ACPI driver's remove callback is
> executed as we will need to flush the workqueue there, or a NULL pointer
> access will be hit.
> 
> Reported-by: Kui Zhang <kuizhang@gmail.com>
> Reference: http://www.spinics.net/lists/kernel/msg1747251.html
> Cc: All applicable <stable@vger.kernel.org>
> Signed-off-by: Aaron Lu <aaron.lu@intel.com>

I'm going to push this as a fix for 3.15, thanks!

> ---
>  drivers/acpi/thermal.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
> index c1e31a41f949..25bbc55dca89 100644
> --- a/drivers/acpi/thermal.c
> +++ b/drivers/acpi/thermal.c
> @@ -1278,8 +1278,8 @@ static int __init acpi_thermal_init(void)
>  
>  static void __exit acpi_thermal_exit(void)
>  {
> -	destroy_workqueue(acpi_thermal_pm_queue);
>  	acpi_bus_unregister_driver(&acpi_thermal_driver);
> +	destroy_workqueue(acpi_thermal_pm_queue);
>  
>  	return;
>  }
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.