1. Patchew
  2. linux
  3. View series

[PATCH v4] iio: chemical: sps30: Replace manual locking with RAII locking

Maxwell Doose posted 1 patch 5 days, 2 hours ago
There is a newer version of this series
drivers/iio/chemical/sps30.c | 25 +++++++++++--------------
1 file changed, 11 insertions(+), 14 deletions(-)
[PATCH v4] iio: chemical: sps30: Replace manual locking with RAII locking
Posted by Maxwell Doose 5 days, 2 hours ago 
Replace manual mutex_lock() and mutex_unlock() calls with the much newer
guard(mutex)() and scoped_guard() macros to enable RAII patterns,
modernize the driver, and to increase readability.

Add guard(mutex)() into sps30_do_meas() as every caller locks it's call.

Signed-off-by: Maxwell Doose <m32285159@gmail.com>
---
 drivers/iio/chemical/sps30.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/chemical/sps30.c b/drivers/iio/chemical/sps30.c
index a934bf0298dd..c10026509e9c 100644
--- a/drivers/iio/chemical/sps30.c
+++ b/drivers/iio/chemical/sps30.c
@@ -5,6 +5,7 @@
  * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
  */
 
+#include <linux/cleanup.h>
 #include <linux/crc8.h>
 #include <linux/delay.h>
 #include <linux/i2c.h>
@@ -69,6 +70,8 @@ static int sps30_do_meas(struct sps30_state *state, s32 *data, int size)
 {
 	int i, ret;
 
+	guard(mutex)(&state->lock);
+
 	if (state->state == RESET) {
 		ret = state->ops->start_meas(state);
 		if (ret)
@@ -111,9 +114,7 @@ static irqreturn_t sps30_trigger_handler(int irq, void *p)
 		aligned_s64 ts;
 	} scan;
 
-	mutex_lock(&state->lock);
 	ret = sps30_do_meas(state, scan.data, ARRAY_SIZE(scan.data));
-	mutex_unlock(&state->lock);
 	if (ret)
 		goto err;
 
@@ -136,7 +137,6 @@ static int sps30_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_PROCESSED:
 		switch (chan->type) {
 		case IIO_MASSCONCENTRATION:
-			mutex_lock(&state->lock);
 			/* read up to the number of bytes actually needed */
 			switch (chan->channel2) {
 			case IIO_MOD_PM1:
@@ -152,7 +152,6 @@ static int sps30_read_raw(struct iio_dev *indio_dev,
 				ret = sps30_do_meas(state, data, 4);
 				break;
 			}
-			mutex_unlock(&state->lock);
 			if (ret)
 				return ret;
 
@@ -160,6 +159,7 @@ static int sps30_read_raw(struct iio_dev *indio_dev,
 			*val2 = (data[chan->address] % 100) * 10000;
 
 			return IIO_VAL_INT_PLUS_MICRO;
+
 		default:
 			return -EINVAL;
 		}
@@ -197,9 +197,9 @@ static ssize_t start_cleaning_store(struct device *dev,
 	if (kstrtoint(buf, 0, &val) || val != 1)
 		return -EINVAL;
 
-	mutex_lock(&state->lock);
+	guard(mutex)(&state->lock);
+
 	ret = state->ops->clean_fan(state);
-	mutex_unlock(&state->lock);
 	if (ret)
 		return ret;
 
@@ -215,9 +215,9 @@ static ssize_t cleaning_period_show(struct device *dev,
 	__be32 val;
 	int ret;
 
-	mutex_lock(&state->lock);
+	guard(mutex)(&state->lock);
+
 	ret = state->ops->read_cleaning_period(state, &val);
-	mutex_unlock(&state->lock);
 	if (ret)
 		return ret;
 
@@ -238,12 +238,11 @@ static ssize_t cleaning_period_store(struct device *dev, struct device_attribute
 	    (val > SPS30_AUTO_CLEANING_PERIOD_MAX))
 		return -EINVAL;
 
-	mutex_lock(&state->lock);
+	guard(mutex)(&state->lock);
+
 	ret = state->ops->write_cleaning_period(state, cpu_to_be32(val));
-	if (ret) {
-		mutex_unlock(&state->lock);
+	if (ret)
 		return ret;
-	}
 
 	msleep(20);
 
@@ -256,8 +255,6 @@ static ssize_t cleaning_period_store(struct device *dev, struct device_attribute
 		dev_warn(dev,
 			 "period changed but reads will return the old value\n");
 
-	mutex_unlock(&state->lock);
-
 	return len;
 }
 
-- 
2.54.0
Re: [PATCH v4] iio: chemical: sps30: Replace manual locking with RAII locking
Posted by Stepan Ionichev 4 days, 12 hours ago 
The hunk in sps30_read_raw() adds an empty line before "default:" in
the switch, which is unrelated to the RAII conversion and probably
worth dropping.

Also, moving guard(mutex) into sps30_do_meas() changes its contract:
previously callers had to hold state->lock around the call, now the
function takes it itself. A line in the commit log would help future
readers avoid the obvious "I'll just wrap it in mutex_lock()" pitfall.

Stepan
Re: [PATCH v4] iio: chemical: sps30: Replace manual locking with RAII locking
Posted by Maxwell Doose 4 days, 7 hours ago 
On Wed, May 20, 2026 at 7:22 AM Stepan Ionichev <sozdayvek@gmail.com> wrote:
>
> The hunk in sps30_read_raw() adds an empty line before "default:" in
> the switch, which is unrelated to the RAII conversion and probably
> worth dropping.
>

First one is a stray change, my bad.


> Also, moving guard(mutex) into sps30_do_meas() changes its contract:
> previously callers had to hold state->lock around the call, now the
> function takes it itself. A line in the commit log would help future
> readers avoid the obvious "I'll just wrap it in mutex_lock()" pitfall.
>
> Stepan

See:
>> Add guard(mutex)() into sps30_do_meas() as every caller locks it's call.

Basic but still denotes that sps30_do_meas() holds the lock.

best regards,
max
Re: [PATCH v4] iio: chemical: sps30: Replace manual locking with RAII locking
Posted by Jonathan Cameron 4 days, 5 hours ago 
On Wed, 20 May 2026 11:49:33 -0500
Maxwell Doose <m32285159@gmail.com> wrote:

> On Wed, May 20, 2026 at 7:22 AM Stepan Ionichev <sozdayvek@gmail.com> wrote:
> >
> > The hunk in sps30_read_raw() adds an empty line before "default:" in
> > the switch, which is unrelated to the RAII conversion and probably
> > worth dropping.
> >  
> 
> First one is a stray change, my bad.
> 
> 
> > Also, moving guard(mutex) into sps30_do_meas() changes its contract:
> > previously callers had to hold state->lock around the call, now the
> > function takes it itself. A line in the commit log would help future
> > readers avoid the obvious "I'll just wrap it in mutex_lock()" pitfall.
> >
> > Stepan  
> 
> See:
> >> Add guard(mutex)() into sps30_do_meas() as every caller locks it's call.  
> 
> Basic but still denotes that sps30_do_meas() holds the lock.

I'd tweak to something a tiny bit more detailed like

Move mutex locking (and switch to guard()) into sps30_do_meas() as every
caller takes the lock just for this call.

> 
> best regards,
> max
>
Re: [PATCH v4] iio: chemical: sps30: Replace manual locking with RAII locking
Posted by Maxwell Doose 4 days, 4 hours ago 
On Wed, May 20, 2026 at 2:04 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Wed, 20 May 2026 11:49:33 -0500
> Maxwell Doose <m32285159@gmail.com> wrote:
>
> > On Wed, May 20, 2026 at 7:22 AM Stepan Ionichev <sozdayvek@gmail.com> wrote:
> > >
> > > The hunk in sps30_read_raw() adds an empty line before "default:" in
> > > the switch, which is unrelated to the RAII conversion and probably
> > > worth dropping.
> > >
> >
> > First one is a stray change, my bad.
> >
> >
> > > Also, moving guard(mutex) into sps30_do_meas() changes its contract:
> > > previously callers had to hold state->lock around the call, now the
> > > function takes it itself. A line in the commit log would help future
> > > readers avoid the obvious "I'll just wrap it in mutex_lock()" pitfall.
> > >
> > > Stepan
> >
> > See:
> > >> Add guard(mutex)() into sps30_do_meas() as every caller locks it's call.
> >
> > Basic but still denotes that sps30_do_meas() holds the lock.
>
> I'd tweak to something a tiny bit more detailed like
>
> Move mutex locking (and switch to guard()) into sps30_do_meas() as every
> caller takes the lock just for this call.
>

Will do, while I'm at it I'll also fix the stray whitespace.

best regards,
max



> >
> > best regards,
> > max
> >
>

Patchew 2.1-devel-ea86937

© 2016 - 2026 Red Hat, Inc.