linux-kernel - Re: [PATCH] regulator: tps65219: fix Wextra warning

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Date:   Thu, 19 Jan 2023 09:07:38 +0100
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Mark Brown" <broonie@...nel.org>,
        "Arnd Bergmann" <arnd@...nel.org>
Cc:     "Tony Lindgren" <tony@...mide.com>,
        "Liam Girdwood" <lgirdwood@...il.com>,
        "Jerome Neanne" <jneanne@...libre.com>,
        "Axel Lin" <axel.lin@...ics.com>,
        "Yang Li" <yang.lee@...ux.alibaba.com>,
        "Yang Yingliang" <yangyingliang@...wei.com>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        linux-kernel@...r.kernel.org,
        "Randy Dunlap" <rdunlap@...radead.org>
Subject: Re: [PATCH] regulator: tps65219: fix Wextra warning

On Fri, Dec 16, 2022, at 11:18, Arnd Bergmann wrote:
> On Thu, Dec 15, 2022, at 17:48, Mark Brown wrote:
>> On Thu, Dec 15, 2022 at 05:41:28PM +0100, Arnd Bergmann wrote:
>>
>>> -		tps65219_get_rdev_by_name(irq_type->regulator_name, rdevtbl, rdev);
>>> -		if (rdev < 0) {
>>> +		error = tps65219_get_rdev_by_name(irq_type->regulator_name, rdevtbl, rdev);
>>> +		if (error) {
>>>  			dev_err(tps->dev, "Failed to get rdev for %s\n",
>>>  				irq_type->regulator_name);
>>> -			return -EINVAL;
>>> +			return error;
>>
>> This will shut up the warning but is leaving the use of the
>> uninitialised rdev (which I'm kind of disappointed the static checkers
>> didn't pick up on).  rdev needs to be passed by reference into the
>> function, or set from the return value.
>
> Right, I didn't look far enough to see what the function is
> actually trying to do here, and that it completely fails to
> do that.
>
> I see that the bug was introduced between the first [1] and
> second []2] version of the driver, but don't see why. I'll
> leave it up to Jerome to address the problem, he's still
> in the middle of posting the rest of the series that has
> not yet been merged, so it makes sense for him to test it
> all together.
>
>     Arnd
>
> [1] https://lore.kernel.org/lkml/20220719091742.3221-9-jneanne@baylibre.com/
> [2] https://lore.kernel.org/lkml/20220726103355.17684-10-jneanne@baylibre.com/

It looks like you merged another workaround from Randy Dunlap now as
commit 2bbba115c3c9 ("regulator: tps65219: use IS_ERR() to detect an error
pointer"), but I think that one is just as wrong as the one I submitted:
the 'rdev' variable still remains uninitialized, and checking its value
after it has already been used is not helpful.

      Arnd