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[PATCH v2] iio: chemical: scd30: Use devm_mutex_init() over non-devm mutex_init()

Maxwell Doose posted 1 patch 3 days, 18 hours ago
There is a newer version of this series
drivers/iio/chemical/scd30_core.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
[PATCH v2] iio: chemical: scd30: Use devm_mutex_init() over non-devm mutex_init()
Posted by Maxwell Doose 3 days, 18 hours ago 
The current code uses mutex_init() instead of devm_mutex_init(), which
is incorrect as the rest of the file uses the devm automatic resource
management API. Fix this so that the mutex is set up in the same way as
the rest of the device data structure.

Signed-off-by: Maxwell Doose <m32285159@gmail.com>
---
 v2:
 - Drop fixes tag per Jonathan's suggestion.
 - Replace dev_err_probe() with return -ENOMEM per Jonathan and Andy's
   suggestions.

 drivers/iio/chemical/scd30_core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c
index db5cc295aeab..198add58affd 100644
--- a/drivers/iio/chemical/scd30_core.c
+++ b/drivers/iio/chemical/scd30_core.c
@@ -714,7 +714,10 @@ int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
 	state->pressure_comp = SCD30_PRESSURE_COMP_DEFAULT;
 	state->meas_interval = SCD30_MEAS_INTERVAL_DEFAULT;
 	state->command = command;
-	mutex_init(&state->lock);
+	ret = devm_mutex_init(dev, &state->lock);
+	if (ret)
+		return -ENOMEM;
+
 	init_completion(&state->meas_ready);
 
 	dev_set_drvdata(dev, indio_dev);
-- 
2.54.0
Re: [PATCH v2] iio: chemical: scd30: Use devm_mutex_init() over non-devm mutex_init()
Posted by David Lechner 3 days, 15 hours ago 
On Thu, Jun 4, 2026 at 3:17 PM Maxwell Doose <m32285159@gmail.com> wrote:
>
> The current code uses mutex_init() instead of devm_mutex_init(), which
> is incorrect as the rest of the file uses the devm automatic resource
> management API. Fix this so that the mutex is set up in the same way as
> the rest of the device data structure.
>
> Signed-off-by: Maxwell Doose <m32285159@gmail.com>
> ---
>  v2:
>  - Drop fixes tag per Jonathan's suggestion.
>  - Replace dev_err_probe() with return -ENOMEM per Jonathan and Andy's
>    suggestions.
>
>  drivers/iio/chemical/scd30_core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c
> index db5cc295aeab..198add58affd 100644
> --- a/drivers/iio/chemical/scd30_core.c
> +++ b/drivers/iio/chemical/scd30_core.c
> @@ -714,7 +714,10 @@ int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
>         state->pressure_comp = SCD30_PRESSURE_COMP_DEFAULT;
>         state->meas_interval = SCD30_MEAS_INTERVAL_DEFAULT;
>         state->command = command;
> -       mutex_init(&state->lock);
> +       ret = devm_mutex_init(dev, &state->lock);
> +       if (ret)
> +               return -ENOMEM;

Why are we ignoring ret?

I would expect:

              return ret;

> +
>         init_completion(&state->meas_ready);
>
>         dev_set_drvdata(dev, indio_dev);
> --
> 2.54.0
>
Re: [PATCH v2] iio: chemical: scd30: Use devm_mutex_init() over non-devm mutex_init()
Posted by Maxwell Doose 3 days, 15 hours ago 
On Thu, Jun 4, 2026 at 11:20 AM David Lechner <dlechner@baylibre.com> wrote:
>
> On Thu, Jun 4, 2026 at 3:17 PM Maxwell Doose <m32285159@gmail.com> wrote:
> >
> > The current code uses mutex_init() instead of devm_mutex_init(), which
> > is incorrect as the rest of the file uses the devm automatic resource
> > management API. Fix this so that the mutex is set up in the same way as
> > the rest of the device data structure.
> >
> > Signed-off-by: Maxwell Doose <m32285159@gmail.com>
> > ---
> >  v2:
> >  - Drop fixes tag per Jonathan's suggestion.
> >  - Replace dev_err_probe() with return -ENOMEM per Jonathan and Andy's
> >    suggestions.
> >
> >  drivers/iio/chemical/scd30_core.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c
> > index db5cc295aeab..198add58affd 100644
> > --- a/drivers/iio/chemical/scd30_core.c
> > +++ b/drivers/iio/chemical/scd30_core.c
> > @@ -714,7 +714,10 @@ int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
> >         state->pressure_comp = SCD30_PRESSURE_COMP_DEFAULT;
> >         state->meas_interval = SCD30_MEAS_INTERVAL_DEFAULT;
> >         state->command = command;
> > -       mutex_init(&state->lock);
> > +       ret = devm_mutex_init(dev, &state->lock);
> > +       if (ret)
> > +               return -ENOMEM;
>
> Why are we ignoring ret?
>
> I would expect:
>
>               return ret;
>

Gah, I must've Jonathan's + Andy's comments get to my head (He said it
should likely only return -ENOMEM) :(
I don't know if he'll want to tweak while applying or if I should just
go back and resubmit.
Re: [PATCH v2] iio: chemical: scd30: Use devm_mutex_init() over non-devm mutex_init()
Posted by Jonathan Cameron 2 days, 19 hours ago 
On Thu, 4 Jun 2026 11:21:07 -0500
Maxwell Doose <m32285159@gmail.com> wrote:

> On Thu, Jun 4, 2026 at 11:20 AM David Lechner <dlechner@baylibre.com> wrote:
> >
> > On Thu, Jun 4, 2026 at 3:17 PM Maxwell Doose <m32285159@gmail.com> wrote:  
> > >
> > > The current code uses mutex_init() instead of devm_mutex_init(), which
> > > is incorrect as the rest of the file uses the devm automatic resource
> > > management API. Fix this so that the mutex is set up in the same way as
> > > the rest of the device data structure.
> > >
> > > Signed-off-by: Maxwell Doose <m32285159@gmail.com>
> > > ---
> > >  v2:
> > >  - Drop fixes tag per Jonathan's suggestion.
> > >  - Replace dev_err_probe() with return -ENOMEM per Jonathan and Andy's
> > >    suggestions.
> > >
> > >  drivers/iio/chemical/scd30_core.c | 5 ++++-
> > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/iio/chemical/scd30_core.c b/drivers/iio/chemical/scd30_core.c
> > > index db5cc295aeab..198add58affd 100644
> > > --- a/drivers/iio/chemical/scd30_core.c
> > > +++ b/drivers/iio/chemical/scd30_core.c
> > > @@ -714,7 +714,10 @@ int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
> > >         state->pressure_comp = SCD30_PRESSURE_COMP_DEFAULT;
> > >         state->meas_interval = SCD30_MEAS_INTERVAL_DEFAULT;
> > >         state->command = command;
> > > -       mutex_init(&state->lock);
> > > +       ret = devm_mutex_init(dev, &state->lock);
> > > +       if (ret)
> > > +               return -ENOMEM;  
> >
> > Why are we ignoring ret?
> >
> > I would expect:
> >
> >               return ret;
> >  
> 
> Gah, I must've Jonathan's + Andy's comments get to my head (He said it
> should likely only return -ENOMEM) :(
> I don't know if he'll want to tweak while applying or if I should just
> go back and resubmit.

IIO is effectively closed for this cycle so plenty of time and I'm lazy
so please send a v3.

Jonathan
Re: [PATCH v2] iio: chemical: scd30: Use devm_mutex_init() over non-devm mutex_init()
Posted by Andy Shevchenko 3 days, 10 hours ago 
On Thu, Jun 04, 2026 at 11:21:07AM -0500, Maxwell Doose wrote:
> On Thu, Jun 4, 2026 at 11:20 AM David Lechner <dlechner@baylibre.com> wrote:
> > On Thu, Jun 4, 2026 at 3:17 PM Maxwell Doose <m32285159@gmail.com> wrote:

...

> > > +       ret = devm_mutex_init(dev, &state->lock);
> > > +       if (ret)
> > > +               return -ENOMEM;
> >
> > Why are we ignoring ret?
> >
> > I would expect:
> >
> >               return ret;
> 
> Gah, I must've Jonathan's + Andy's comments get to my head (He said it
> should likely only return -ENOMEM) :(
> I don't know if he'll want to tweak while applying or if I should just
> go back and resubmit.

What we meant is that:

- devm_mutex_init() may return only -ENOMEM as of today
- dev_err_probe() will ignore (print nothing) when err == -ENOMEM

It has nothing to do with the caller, we explained how callee do.
TL;DR: it should be simple return ret; as Jonathan said already.

-- 
With Best Regards,
Andy Shevchenko
Re: [PATCH v2] iio: chemical: scd30: Use devm_mutex_init() over non-devm mutex_init()
Posted by Joshua Crofts 3 days, 17 hours ago 
On Thu, 4 Jun 2026 at 15:27, Maxwell Doose <m32285159@gmail.com> wrote:
>
> The current code uses mutex_init() instead of devm_mutex_init(), which
> is incorrect as the rest of the file uses the devm automatic resource
> management API. Fix this so that the mutex is set up in the same way as
> the rest of the device data structure.
>
> Signed-off-by: Maxwell Doose <m32285159@gmail.com>
> ---

Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>

Patchew 2.1-devel-ea86937

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