Re: [PATCH] pwm: sun4i: add NULL check on of_match_device() return value

From	"Gustavo A. R. Silva" <garsilva@embeddedor.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] pwm: sun4i: add NULL check on of_match_device() return value
Date	2017-07-10 21:30 +0200
Message-ID	<u1MxA-Ey-3@gated-at.bofh.it> (permalink)
References	<u0vfs-5W-23@gated-at.bofh.it> <u0vIt-ww-7@gated-at.bofh.it> <u0xTX-24L-5@gated-at.bofh.it>
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Hi all,

Quoting Thierry Reding <thierry.reding@gmail.com>:

> On Fri, Jul 07, 2017 at 03:16:23PM +0800, Chen-Yu Tsai wrote:
>> On Fri, Jul 7, 2017 at 2:39 PM, Gustavo A. R. Silva
>> <garsilva@embeddedor.com> wrote:
>> > Check return value from call to of_match_device()
>> > in order to prevent a NULL pointer dereference.
>> >
>> > In case of NULL print error message and return -ENODEV
>> >
>> > Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
>> > ---
>> >  drivers/pwm/pwm-sun4i.c | 4 ++++
>> >  1 file changed, 4 insertions(+)
>> >
>> > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
>> > index 1284ffa..295ca19 100644
>> > --- a/drivers/pwm/pwm-sun4i.c
>> > +++ b/drivers/pwm/pwm-sun4i.c
>> > @@ -321,6 +321,10 @@ static int sun4i_pwm_probe(struct  
>> platform_device *pdev)
>> >         const struct of_device_id *match;
>> >
>> >         match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
>>
>> AFAIK this simply can not and should not fail with a device tree
>> only driver with properly populated of_device_id tables.
>
> Technically this could happen if someone manually created the platform
> device. In that case the core will try to match by name if there is no
> device node to use for a match against the list of of_device_ids.
>
> In my opinion it's best to let things crash in this situation to make
> it really obvious that people have done something wrong.
>

I get it.

Thanks for clarifying.
--
Gustavo A. R. Silva

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[PATCH] pwm: sun4i: add NULL check on of_match_device() return value "Gustavo A. R. Silva" <garsilva@embeddedor.com> - 2017-07-07 08:50 +0200
  Re: [PATCH] pwm: sun4i: add NULL check on of_match_device() return value Chen-Yu Tsai <wens@csie.org> - 2017-07-07 09:20 +0200
    Re: [PATCH] pwm: sun4i: add NULL check on of_match_device() return  value Thierry Reding <thierry.reding@gmail.com> - 2017-07-07 11:40 +0200
      Re: [PATCH] pwm: sun4i: add NULL check on of_match_device() return  value "Gustavo A. R. Silva" <garsilva@embeddedor.com> - 2017-07-10 21:30 +0200

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