linux-kernel - Re: [PATCH v3] backlight: pwm_bl: Fix uninitialized variable

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Message-ID: <20180725052211.GA5835@dell>
Date:   Wed, 25 Jul 2018 06:22:11 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Daniel Thompson <daniel.thompson@...aro.org>
Cc:     Jingoo Han <jingoohan1@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        linux-pwm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        patches@...aro.org
Subject: Re: [PATCH v3] backlight: pwm_bl: Fix uninitialized variable

On Tue, 24 Jul 2018, Daniel Thompson wrote:

> Currently, if the DT does not define num-interpolated-steps then
> num_steps is undefined and the interpolation code will deploy randomly.
> Fix with a simple initialize to zero.
> 
> Fixes: 573fe6d1c25c ("backlight: pwm_bl: Linear interpolation between
> brightness-levels")
> Reported-by: Marcel Ziswiler <marcel.ziswiler@...adex.com>
> Signed-off-by: Daniel Thompson <daniel.thompson@...aro.org>
> Tested-by: Marcel Ziswiler <marcel.ziswiler@...adex.com>
> ---
> 
> Notes:
>     v3:
>      - Switch to the simplest fix and zero the uninitialized variable. git
>        grep indicates that ~25% of calls to of_property_read_u32() use this
>        pattern (pre-initialize optional properties with sane values and
>        ignore the return code).
>     
>     v2:
>      - Simplify SoB chain (with Marcel's permission)
>      - Separate complex if statement and make other similar calls use same
>        return code checking approach
>      - Tidy up comment formatting and fix pre-existing grammar error
> 
>  drivers/video/backlight/pwm_bl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Once the 'Fixes:' line has been repaired:

  Acked-by: Lee Jones <lee.jones@...aro.org>

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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