linux-kernel - Re: [PATCH v3 08/18] iio: adc: stm32: Simplify with dev_err

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Date:   Thu, 10 Sep 2020 08:58:57 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Peter Rosin <peda@...ntia.se>, Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Tomasz Duszynski <tomasz.duszynski@...akon.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        "linux-amlogic@...ts.infradead.org" 
        <linux-amlogic@...ts.infradead.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v3 08/18] iio: adc: stm32: Simplify with dev_err_probe()

On Thu, 10 Sep 2020 at 08:52, Andy Shevchenko <andy.shevchenko@...il.com> wrote:
>
>
>
> On Thursday, September 10, 2020, Peter Rosin <peda@...ntia.se> wrote:
>>
>> Hi!
>>
>> On 2020-09-09 21:57, Krzysztof Kozlowski wrote:
>> > On Wed, 9 Sep 2020 at 20:36, Jonathan Cameron <jic23@...nel.org> wrote:
>> >>
>> >> On Sat, 29 Aug 2020 08:47:16 +0200
>> >> Krzysztof Kozlowski <krzk@...nel.org> wrote:
>> >>
>> >>> Common pattern of handling deferred probe can be simplified with
>> >>> dev_err_probe().  Less code and also it prints the error value.
>> >>>
>> >>> Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
>> >>> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>> >>>
>> >> I don't have the thread to hand, but this tripped a warning next
>> >> and the patch was dropped as a result. See below.
>> >
>> > Thanks for letting me know. If you mean the warning caused by:
>> > https://lore.kernel.org/lkml/20200909073716.GA560912@kroah.com/
>> > then the driver-core patch was dropped, not the iio one:
>> > https://lore.kernel.org/linux-next/20200909074130.GB561485@kroah.com/T/#t
>> >
>> > So we are good here :)
>>
>> No, we are definitely not good. See below. That means "See below", and
>> not "Please take a guess at what is being talking about".
>
>
>
>>
>> >>> @@ -596,12 +594,9 @@ static int stm32_adc_core_switches_probe(struct device *dev,
>> >>>               priv->booster = devm_regulator_get_optional(dev, "booster");
>> >>>               if (IS_ERR(priv->booster)) {
>> >>>                       ret = PTR_ERR(priv->booster);
>> >>> -                     if (ret != -ENODEV) {
>> >>> -                             if (ret != -EPROBE_DEFER)
>> >>> -                                     dev_err(dev, "can't get booster %d\n",
>> >>> -                                             ret);
>> >>> -                             return ret;
>> >>> -                     }
>> >>> +                     if (ret != -ENODEV)
>> >>> +                             dev_err_probe(dev, ret, "can't get booster\n");
>> >>
>> >> This tripped a warning and got the patch dropped because we no longer
>> >> return on error.
>>
>> As Jonathan already said, we no longer return in this hunk. I.e., you have
>> clobbered the error path.
>
>
> Exactly my point why I proposed _must_check in the first place.

That was not exactly that point as you did not mention possible errors
but only "miss the opportunity to optimize". Optimization is different
things than a mistake.

Best regards,
Krzysztof