linux-kernel - Re: [PATCH RFC 5/6] iio: health: max30102: Use cleanup.h for IIO locks

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Message-Id: <DEPMCPWLO4FO.2B2OXMF2CZ1G@gmail.com>
Date: Thu, 04 Dec 2025 12:47:08 -0500
From: "Kurt Borja" <kuurtb@...il.com>
To: "David Lechner" <dlechner@...libre.com>, "Kurt Borja"
 <kuurtb@...il.com>, "Andy Shevchenko" <andriy.shevchenko@...el.com>,
 "Lars-Peter Clausen" <lars@...afoo.de>, "Michael Hennerich"
 <Michael.Hennerich@...log.com>, "Jonathan Cameron" <jic23@...nel.org>,
 "Benson Leung" <bleung@...omium.org>, "Antoniu Miclaus"
 <antoniu.miclaus@...log.com>, "Gwendal Grignou" <gwendal@...omium.org>,
 "Shrikant Raskar" <raskar.shree97@...il.com>, "Per-Daniel Olsson"
 <perdaniel.olsson@...s.com>
Cc: Nuno Sá <nuno.sa@...log.com>, "Andy Shevchenko"
 <andy@...nel.org>, "Guenter Roeck" <groeck@...omium.org>, "Jonathan
 Cameron" <Jonathan.Cameron@...wei.com>, <linux-iio@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>, <chrome-platform@...ts.linux.dev>
Subject: Re: [PATCH RFC 5/6] iio: health: max30102: Use cleanup.h for IIO
 locks

On Thu Dec 4, 2025 at 12:35 PM -05, David Lechner wrote:
> On 12/4/25 11:07 AM, Kurt Borja wrote:
>> On Wed Dec 3, 2025 at 4:52 PM -05, David Lechner wrote:
>>> On 12/3/25 1:18 PM, Kurt Borja wrote:
>
> ...
>
>>> I would write the whole function like this:
>>>
>>> static int max30102_read_raw(struct iio_dev *indio_dev,
>>> 			     struct iio_chan_spec const *chan,
>>> 			     int *val, int *val2, long mask)
>>> {
>>> 	struct max30102_data *data = iio_priv(indio_dev);
>>> 	int ret;
>>>
>>> 	switch (mask) {
>>> 	case IIO_CHAN_INFO_RAW: {
>>> 		/*
>>> 		 * Temperature reading can only be acquired when not in
>>> 		 * shutdown; leave shutdown briefly when buffer not running
>>> 		 */
>>> 		guard(iio_device_claim)(indio_dev);
>> 
>> AFAIK you can't guard() inside switch-case blocks. I don't know the
>> exact reason, but it has to be scoped_guard().
>
> You can. You just need the braces like I showed in my suggestion.
>
> The reason is that guard() is declaring local variables and some
> compilers like LLVM don't like declaring local variables in a
> switch case. By adding the { } scope, the variables are limited
> to that scope and the issue goes away.

Ah - You're right. I dind't see the braces.

Now it is overly complicated. In this case I see why guard() isn't
really an improvement.


-- 
 ~ Kurt