[PATCH 1/2] iio: buffer: Save a few cycles in 'iio_scan_mask_set()'

[PATCH 1/2] iio: buffer: Save a few cycles in 'iio_scan_mask_set()'

[Christophe JAILLET]

Use 'bitmap_alloc()' instead of 'bitmap_zalloc()' because the bitmap
is fully overridden by a 'bitmap_copy()' call just after its allocation.

While at it, fix the style of a NULL check.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/iio/industrialio-buffer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index fdd623407b96..6d4776a7f002 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -354,8 +354,8 @@ static int iio_scan_mask_set(struct iio_dev *indio_dev,
 	const unsigned long *mask;
 	unsigned long *trialmask;
 
-	trialmask = bitmap_zalloc(indio_dev->masklength, GFP_KERNEL);
-	if (trialmask == NULL)
+	trialmask = bitmap_alloc(indio_dev->masklength, GFP_KERNEL);
+	if (!trialmask)
 		return -ENOMEM;
 	if (!indio_dev->masklength) {
 		WARN(1, "Trying to set scanmask prior to registering buffer\n");
-- 
2.30.2

[PATCH 2/2] iio: buffer: Move a sanity check at the beginning of 'iio_scan_mask_set()'

[Christophe JAILLET]

This is more standard to have sanity checks at the entry of a function,
instead of allocating some memory first and having to free it if a
condition is not met.

Shuffle code a bit to check 'masklength' before calling 'bitmap_alloc()'

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/iio/industrialio-buffer.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 6d4776a7f002..a95cc2da56be 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -354,13 +354,14 @@ static int iio_scan_mask_set(struct iio_dev *indio_dev,
 	const unsigned long *mask;
 	unsigned long *trialmask;
 
-	trialmask = bitmap_alloc(indio_dev->masklength, GFP_KERNEL);
-	if (!trialmask)
-		return -ENOMEM;
 	if (!indio_dev->masklength) {
 		WARN(1, "Trying to set scanmask prior to registering buffer\n");
-		goto err_invalid_mask;
+		return -EINVAL;
 	}
+
+	trialmask = bitmap_alloc(indio_dev->masklength, GFP_KERNEL);
+	if (!trialmask)
+		return -ENOMEM;
 	bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
 	set_bit(bit, trialmask);
 
-- 
2.30.2

Re: [PATCH 1/2] iio: buffer: Save a few cycles in 'iio_scan_mask_set()'

[Jonathan Cameron]

On Wed, 14 Jul 2021 13:14:41 +0200
Christophe JAILLET <christophe.jaillet@wanadoo.fr> wrote:

> Use 'bitmap_alloc()' instead of 'bitmap_zalloc()' because the bitmap
> is fully overridden by a 'bitmap_copy()' call just after its allocation.
> 
> While at it, fix the style of a NULL check.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Applied to the togreg branch of iio.git and pushed out as testing for the autobuilders
to poke at it.

Thanks,

Jonathan

> ---
>  drivers/iio/industrialio-buffer.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index fdd623407b96..6d4776a7f002 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -354,8 +354,8 @@ static int iio_scan_mask_set(struct iio_dev *indio_dev,
>  	const unsigned long *mask;
>  	unsigned long *trialmask;
>  
> -	trialmask = bitmap_zalloc(indio_dev->masklength, GFP_KERNEL);
> -	if (trialmask == NULL)
> +	trialmask = bitmap_alloc(indio_dev->masklength, GFP_KERNEL);
> +	if (!trialmask)
>  		return -ENOMEM;
>  	if (!indio_dev->masklength) {
>  		WARN(1, "Trying to set scanmask prior to registering buffer\n");

Re: [PATCH 2/2] iio: buffer: Move a sanity check at the beginning of 'iio_scan_mask_set()'

[Jonathan Cameron]

On Wed, 14 Jul 2021 13:14:51 +0200
Christophe JAILLET <christophe.jaillet@wanadoo.fr> wrote:

> This is more standard to have sanity checks at the entry of a function,
> instead of allocating some memory first and having to free it if a
> condition is not met.

Indeed this is silly.  I'd guess result of code evolution, but perhaps
I was crazy in the first place :)

Applied,

Thanks,

Jonathan

> 
> Shuffle code a bit to check 'masklength' before calling 'bitmap_alloc()'
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
>  drivers/iio/industrialio-buffer.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index 6d4776a7f002..a95cc2da56be 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -354,13 +354,14 @@ static int iio_scan_mask_set(struct iio_dev *indio_dev,
>  	const unsigned long *mask;
>  	unsigned long *trialmask;
>  
> -	trialmask = bitmap_alloc(indio_dev->masklength, GFP_KERNEL);
> -	if (!trialmask)
> -		return -ENOMEM;
>  	if (!indio_dev->masklength) {
>  		WARN(1, "Trying to set scanmask prior to registering buffer\n");
> -		goto err_invalid_mask;
> +		return -EINVAL;
>  	}
> +
> +	trialmask = bitmap_alloc(indio_dev->masklength, GFP_KERNEL);
> +	if (!trialmask)
> +		return -ENOMEM;
>  	bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
>  	set_bit(bit, trialmask);
>