Re: [PATCH v6] iio: chemical: scd30: Replace manual locking with RAII locking

[Maxwell Doose]

Hi Markus,

On Mon, 1 Jun 2026 17:38:44 +0200
Markus Elfring <Markus.Elfring@xxxxxx> wrote:

> > scd30_core.c currently uses manual mutex_lock() and mutex_unlock()
> > calls. Replace them with the newer guard(mutex)() for cleaner RAII
> > patterns and to improve maintainability.  
> …
> > In addition, small refactor to replace "?:" operator with regular
> > if/else returns.  
> 
> How does such an information fit to a known patch requirement?
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v7.1-rc5#n81
> 

Good point. However, I think that it's such a small change that nobody
is going to care that much. We'll see what Jonathan has to say, I
suppose.

> 
> …
> > +++ b/drivers/iio/chemical/scd30_core.c
> > @@ -368,11 +368,13 @@ static ssize_t calibration_auto_enable_show(struct device *dev, struct device_at
> >  	int ret;
> >  	u16 val;
> >  
> > -	mutex_lock(&state->lock);
> > -	ret = scd30_command_read(state, CMD_ASC, &val);
> > -	mutex_unlock(&state->lock);
> > +	guard(mutex)(&state->lock);
> >  
> > -	return ret ?: sysfs_emit(buf, "%d\n", val);  
> …
> 
> How do you think about to preserve lock scopes by using scoped_guard() calls?
> 

Generally scoped_guard() (at least in my experience in iio) is frowned
upon because of the hidden for loop that can make normal things (e.g.,
break, continue) really weird, plus guard()() with {} is also (in my
experience) more popular over scoped_guard(). In the past helpers have
also been liked over both as well.

-- 
best regards,
max