linux-kernel - Re: [PATCH] drivers/acpi/video: fix brightness allocation

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Message-ID: <8265cb9e0806130405m340a314fm6935f388653e9e6a@mail.gmail.com>
Date:	Fri, 13 Jun 2008 12:05:40 +0100
From:	"Julia Jomantaite" <julia.jomantaite@...il.com>
To:	"Andrew Morton" <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	rui.zhang@...el.com
Subject: Re: [PATCH] drivers/acpi/video: fix brightness allocation

On Fri, Jun 13, 2008 at 2:00 AM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Thu, 12 Jun 2008 17:47:09 +0100
> "Julia Jomantaite" <julia.jomantaite@...il.com> wrote:
>
>> ACPI Video Driver module (drivers/acpi/video.c) produces Oops message
>> after pressing one of two Fn+<key> combinations responsible for switching
>> the brightness level on my laptop.
>>
>> The source of this problem is in the function acpi_video_switch_brightness
>> which can access device->brightness when it is not allocated. Function
>> "acpi_video_device_find_cap" which is responsible for allocating
>> device->brightness can leave it unallocated in some cases.
>>
>> Function acpi_video_switch_brightness isn't called if modules's parameter
>> "brightness_switch_enabled" is equal to zero so i've decided to add
>> zeroing of this parameter to the part of the code where unsuccessfull
>> allocation of device->brightness was handled.
>>
>> Also i've moved initialization of brightness to a separate function
>> "acpi_video_init_brightness" to improve readability of the code and
>> to simplify error handling.
>>
>
> (cc's added)
>
> Thanks.  Which kernel version were you running?

This patch is for the latest version of kernel from git  (linux-2.6),
but the similar allocation problem exists on earlier versions of
kernel ( for example 2.6.22 and 2.6.23).

> The patch was a bit wordwrapped.  Here's the fixed up version:

Thank you.
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