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Date:   Thu, 15 Jun 2023 12:53:24 +0200
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Subject: Re: [PATCH v2 5/8] rtc: isl12022: implement RTC_VL_READ ioctl
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To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc:     Alessandro Zummo <a.zummo@towertech.it>,
        devicetree@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>, linux-rtc@vger.kernel.org,
        linux-kernel@vger.kernel.org
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From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
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On 14/06/2023 17.13, Andy Shevchenko wrote:

> When reading such a code the following questions are arisen:
> 1) Can the positive return value be the case?
> 2) If so, what is the meaning of a such?
> 3) Why do we not care about it?
> 
> All this can simply gone if we use
> 
> 	ret = foo(...);
> 	if (ret)
> 		return ret;
> 
> As it's clear that whatever is non-zero we accept as something to be promoted
> to the upper layer. I hope this explains my position.

But we're in a context (in this case an ->ioctl method) where _our_
caller expects 0/-ESOMETHING, so returning something positive would be a
bug - i.e., either way of spelling that if(), the reader must know that
foo() also has those 0/-ESOMETHING semantics.

I honestly didn't think much about it, but looking at the existing code
and the stuff I add, all other places actually do 'if (ret)', so I've
updated this site for consistency.

Rasmus