linux-kernel - Re: [PATCH] mtd: spi-nor: stm32-quadspi: avoid unintialized return code

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Date:   Fri, 15 Sep 2017 09:59:05 +0200
From:   Ludovic BARRE <ludovic.barre@...com>
To:     Arnd Bergmann <arnd@...db.de>
CC:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        Marek Vasut <marek.vasut@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Richard Weinberger <richard@....at>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        MTD Maling List <linux-mtd@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH] mtd: spi-nor: stm32-quadspi: avoid unintialized return
 code



On 09/14/2017 11:38 PM, Arnd Bergmann wrote:
> On Thu, Sep 14, 2017 at 6:55 PM, Ludovic BARRE <ludovic.barre@...com> wrote:
>>
>>
>> On 09/14/2017 05:24 PM, Geert Uytterhoeven wrote:
>>>
>>> Hi Ludovic,
>>>
>>> On Thu, Sep 14, 2017 at 5:13 PM, Ludovic BARRE <ludovic.barre@...com>
>>> wrote:
>>>>
>>>> On 09/14/2017 03:38 PM, Geert Uytterhoeven wrote:
>>>>
>>>> hi Arnd, Geert
>>>>
>>>> sorry, I was forgot this thread while my holidays
>>>>
>>>> Geert: what do you mean like "similar bugs in the future" in "If you
>>>> initialized ret at the beginning, you lose the ability to catch newly
>>>> introduced similar bugs in the future."
>>>
>>>
>>> If you pre-initialize ret at the top, you loose the ability of the
>>> compiler
>>> to detect at compile-time if ret is never written to later. It will just
>>> return
>>> -EINVAL at runtime.
>>>
>>> With my version, if the code is modified later and another "return ret" is
>>> added, the compiler will detect if there's a code path that forgets
>>> to assign a value to ret.
>>
>> Ok, it's clear for me.
>> I favor geert's solution.
>> Arnd what do you think ?
> 
> I usually follow the same rule that Geert explained (and quote
> https://rusty.ozlabs.org/?p=232 when I do so). In this case, there
> did not seem to be much value as the variable is not used
> afterwards, and I kept the 'single return statement' guideline.
> 
> In the end, either version seems totally fine to me here, so
> please use Geert's if you prefer that.

thank Arnd for your answer, great link :-)
we take geert's patch.

Geert: I will acked your patch.

thanks everybody
> 
>          Arnd
>