[PATCH v2] iio: adc: ad_sigma_delta: use __free(kfree) for temporary buffers

[PATCH v2] iio: adc: ad_sigma_delta: use __free(kfree) for temporary buffers

[Adi Kadušić]

Replace manual kfree() calls with the __free(kfree) cleanup attribute.
No functional change.

Signed-off-by: Adi Kadušić <kadusicadi1@gmail.com>
---
Changes in v2:
- Keep reset_length/size declarations in ad_sd_reset() as they were,
  only declare buf with __free(kfree) at its allocation (Andy)

v1: https://lore.kernel.org/linux-iio/20261108013328.125069-1-kadusicadi1@gmail.com/T/#u

 drivers/iio/adc/ad_sigma_delta.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index 119ddc5a13e2..934c9965c69b 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -205,19 +205,15 @@ int ad_sd_reset(struct ad_sigma_delta *sigma_delta)
 {
 	unsigned int reset_length = sigma_delta->info->num_resetclks;
 	unsigned int size;
-	u8 *buf;
-	int ret;
 
 	size = BITS_TO_BYTES(reset_length);
-	buf = kcalloc(size, sizeof(*buf), GFP_KERNEL);
+	u8 *buf __free(kfree) = kcalloc(size, sizeof(*buf), GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
 	memset(buf, 0xff, size);
-	ret = spi_write(sigma_delta->spi, buf, size);
-	kfree(buf);
 
-	return ret;
+	return spi_write(sigma_delta->spi, buf, size);
 }
 EXPORT_SYMBOL_NS_GPL(ad_sd_reset, "IIO_AD_SIGMA_DELTA");
 
@@ -249,7 +245,6 @@ static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta
 {
 	bool pending_event;
 	unsigned int data_read_len = BITS_TO_BYTES(sigma_delta->info->num_resetclks);
-	u8 *data;
 	struct spi_transfer t[] = {
 		{
 			.len = 1,
@@ -317,7 +312,7 @@ static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta
 	 * shorter than the reset procedure.
 	 */
 
-	data = kzalloc(data_read_len + 1, GFP_KERNEL);
+	u8 *data __free(kfree) = kzalloc(data_read_len + 1, GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
@@ -340,11 +335,7 @@ static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta
 	memset(data + 2, 0xff, data_read_len - 1);
 	spi_message_add_tail(&t[1], &m);
 
-	ret = spi_sync_locked(sigma_delta->spi, &m);
-
-	kfree(data);
-
-	return ret;
+	return spi_sync_locked(sigma_delta->spi, &m);
 }
 
 int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
-- 
2.43.0

Re: [PATCH v2] iio: adc: ad_sigma_delta: use __free(kfree) for temporary buffers

[Joshua Crofts]

On Sun,  8 Nov 2026 21:15:22 +0100
Adi Kadušić <kadusicadi1@gmail.com> wrote:

> Replace manual kfree() calls with the __free(kfree) cleanup attribute.
> No functional change.

I think that this is a functional change :)
This can be dropped while applying though.

Reviewed-by: Joshua Crofts <crofts@kernel.org>

-- 
Kind regards,
Joshua Crofts

Re: [PATCH v2] iio: adc: ad_sigma_delta: use __free(kfree) for temporary buffers

[Nuno Sá]

On Sun, Nov 08, 2026 at 09:15:22PM +0100, Adi Kadušić wrote:
> Replace manual kfree() calls with the __free(kfree) cleanup attribute.
> No functional change.
> 
> Signed-off-by: Adi Kadušić <kadusicadi1@gmail.com>
> ---

Yeps, like the change

Reviewed-by: Nuno Sá <nuno.sa@analog.com>

> Changes in v2:
> - Keep reset_length/size declarations in ad_sd_reset() as they were,
>   only declare buf with __free(kfree) at its allocation (Andy)
> 
> v1: https://lore.kernel.org/linux-iio/20261108013328.125069-1-kadusicadi1@gmail.com/T/#u
> 
>  drivers/iio/adc/ad_sigma_delta.c | 17 ++++-------------
>  1 file changed, 4 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
> index 119ddc5a13e2..934c9965c69b 100644
> --- a/drivers/iio/adc/ad_sigma_delta.c
> +++ b/drivers/iio/adc/ad_sigma_delta.c
> @@ -205,19 +205,15 @@ int ad_sd_reset(struct ad_sigma_delta *sigma_delta)
>  {
>  	unsigned int reset_length = sigma_delta->info->num_resetclks;
>  	unsigned int size;
> -	u8 *buf;
> -	int ret;
>  
>  	size = BITS_TO_BYTES(reset_length);
> -	buf = kcalloc(size, sizeof(*buf), GFP_KERNEL);
> +	u8 *buf __free(kfree) = kcalloc(size, sizeof(*buf), GFP_KERNEL);
>  	if (!buf)
>  		return -ENOMEM;
>  
>  	memset(buf, 0xff, size);
> -	ret = spi_write(sigma_delta->spi, buf, size);
> -	kfree(buf);
>  
> -	return ret;
> +	return spi_write(sigma_delta->spi, buf, size);
>  }
>  EXPORT_SYMBOL_NS_GPL(ad_sd_reset, "IIO_AD_SIGMA_DELTA");
>  
> @@ -249,7 +245,6 @@ static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta
>  {
>  	bool pending_event;
>  	unsigned int data_read_len = BITS_TO_BYTES(sigma_delta->info->num_resetclks);
> -	u8 *data;
>  	struct spi_transfer t[] = {
>  		{
>  			.len = 1,
> @@ -317,7 +312,7 @@ static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta
>  	 * shorter than the reset procedure.
>  	 */
>  
> -	data = kzalloc(data_read_len + 1, GFP_KERNEL);
> +	u8 *data __free(kfree) = kzalloc(data_read_len + 1, GFP_KERNEL);
>  	if (!data)
>  		return -ENOMEM;
>  
> @@ -340,11 +335,7 @@ static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta
>  	memset(data + 2, 0xff, data_read_len - 1);
>  	spi_message_add_tail(&t[1], &m);
>  
> -	ret = spi_sync_locked(sigma_delta->spi, &m);
> -
> -	kfree(data);
> -
> -	return ret;
> +	return spi_sync_locked(sigma_delta->spi, &m);
>  }
>  
>  int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
> -- 
> 2.43.0
> 

Re: [PATCH v2] iio: adc: ad_sigma_delta: use __free(kfree) for temporary buffers

[Andy Shevchenko]

On Sun, Nov 08, 2026 at 09:15:22PM +0100, Adi Kadušić wrote:
> Replace manual kfree() calls with the __free(kfree) cleanup attribute.
> No functional change.

...

> -	data = kzalloc(data_read_len + 1, GFP_KERNEL);
> +	u8 *data __free(kfree) = kzalloc(data_read_len + 1, GFP_KERNEL);

Just a side note.
Would be good at some point use something from overflow.h for this.

>  	if (!data)
>  		return -ENOMEM;

-- 
With Best Regards,
Andy Shevchenko