linux-kernel - Re: [PATCH 1/4] gpiolib: check descriptors validity before use

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Date:	Thu, 14 Feb 2013 12:00:54 +0900
From:	Alexandre Courbot <gnurou@...il.com>
To:	Ryan Mallon <rmallon@...il.com>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Linus Walleij <linus.walleij@...aro.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] gpiolib: check descriptors validity before use

On Thu, Feb 14, 2013 at 7:49 AM, Ryan Mallon <rmallon@...il.com> wrote:
> Is it really useful to use the same pr_debug for the error case? Why not do:
>
>         desc = gpio_to_desc(gpio);
>         if (!desc) {
>                 pr_debug("%s - Invalid gpio %d\n", __func__, gpio);
>                 return -EINVAL;
>         }
>
>         ...
>
> At this point desc is known valid, though you could just use the gpio
> number that was passed in (assuming that it is always the same as
> desc_to_gpio).
>
>         pr_debug("%s: gpio%d status %d\n", __func__,
>                  desc_to_gpio(desc), status);
>         return status;
>
> That provides more information (the original gpio number and the reason
> for the -EINVAL) if the gpio is not valid, and removes the ugly ternary
> operator from the pr_debug. Same goes for the other functions.

That's mainly a style issue - I tried to preserve the code's behavior
as much as possible with these patches. But indeed the invalid GPIO
case is special, and on second thought identifying invalid GPIOs are
"gpio-1" is confusing. One could also say horrible.

Guess this deserves to be fixed in a v2. Thanks.

Alex.
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