Use guard(mutex) from cleanup.h to remove most of the gotos and to make
the code simpler and less likely to fail due to forgetting to unlock
the resources.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
 drivers/iio/adc/ad7768-1.c | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index f73b9aec8b0f..cd1b08053105 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -5,6 +5,7 @@
  * Copyright 2017 Analog Devices Inc.
  */
 #include <linux/bitfield.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -257,20 +258,12 @@ static int ad7768_reg_access(struct iio_dev *indio_dev,
 			     unsigned int *readval)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
-	int ret;
 
-	mutex_lock(&st->lock);
-	if (readval) {
-		ret = ad7768_spi_reg_read(st, reg, readval, 1);
-		if (ret < 0)
-			goto err_unlock;
-	} else {
-		ret = ad7768_spi_reg_write(st, reg, writeval);
-	}
-err_unlock:
-	mutex_unlock(&st->lock);
+	guard(mutex)(&st->lock);
+	if (readval)
+		return ad7768_spi_reg_read(st, reg, readval, 1);
 
-	return ret;
+	return ad7768_spi_reg_write(st, reg, writeval);
 }
 
 static int ad7768_set_dig_fil(struct ad7768_state *st,
@@ -484,7 +477,7 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
 	struct ad7768_state *st = iio_priv(indio_dev);
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 
 	ret = spi_read(st->spi, &st->data.scan.chan, 3);
 	if (ret < 0)
@@ -495,7 +488,6 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
 
 err_unlock:
 	iio_trigger_notify_done(indio_dev->trig);
-	mutex_unlock(&st->lock);
 
 	return IRQ_HANDLED;
 }
-- 
2.34.1

On 1/7/25 9:25 AM, Jonathan Santos wrote:
> Use guard(mutex) from cleanup.h to remove most of the gotos and to make
> the code simpler and less likely to fail due to forgetting to unlock
> the resources.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---

...

> @@ -484,7 +477,7 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
>  	struct ad7768_state *st = iio_priv(indio_dev);
>  	int ret;
>  
> -	mutex_lock(&st->lock);
> +	guard(mutex)(&st->lock);
>  
>  	ret = spi_read(st->spi, &st->data.scan.chan, 3);
>  	if (ret < 0)
> @@ -495,7 +488,6 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
>  
>  err_unlock:

nit: also rename the label since it is no longer unlocking

>  	iio_trigger_notify_done(indio_dev->trig);
> -	mutex_unlock(&st->lock);
>  
>  	return IRQ_HANDLED;
>  }

I'm also wondering if we should just drop this lock. It is only protecting
a triggered buffer SPI xfer and debugfs register access from happening at the
same time.

Since we have to write a magic value to exit conversion mode, reading registers
during a buffered read is going to cause problems anyway. So we could just
remove the mutex lock and use iio_device_claim_direct_mode() instead in
ad7768_reg_access().

On 01/07, David Lechner wrote:
> On 1/7/25 9:25 AM, Jonathan Santos wrote:
> > Use guard(mutex) from cleanup.h to remove most of the gotos and to make
> > the code simpler and less likely to fail due to forgetting to unlock
> > the resources.
> > 
> > Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> > ---
> 
> ...
> 
> > @@ -484,7 +477,7 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
> >  	struct ad7768_state *st = iio_priv(indio_dev);
> >  	int ret;
> >  
> > -	mutex_lock(&st->lock);
> > +	guard(mutex)(&st->lock);
> >  
> >  	ret = spi_read(st->spi, &st->data.scan.chan, 3);
> >  	if (ret < 0)
> > @@ -495,7 +488,6 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
> >  
> >  err_unlock:
> 
> nit: also rename the label since it is no longer unlocking
> 
> >  	iio_trigger_notify_done(indio_dev->trig);
> > -	mutex_unlock(&st->lock);
> >  
> >  	return IRQ_HANDLED;
> >  }
> 
> I'm also wondering if we should just drop this lock. It is only protecting
> a triggered buffer SPI xfer and debugfs register access from happening at the
> same time.
> 
> Since we have to write a magic value to exit conversion mode, reading registers
> during a buffered read is going to cause problems anyway. So we could just
> remove the mutex lock and use iio_device_claim_direct_mode() instead in
> ad7768_reg_access().
>
Ok, that makes sense. I will change in the next version.