Re: [PATCH][RFC] iio: buffer: remove 'scan_el_attrs' attribute group from buffer struct

[Jonathan Cameron]

On Fri, 10 Apr 2020 12:36:07 +0300
Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> wrote:

> This field doesn't seem used. It seems that only 'buffer->attrs' was ever
> used to extend sysfs attributes for an IIO buffer.
> 
> Moving forward, it may not make sense to keep it. This patch removes the
> field and it's initialization code.
> 
> Since we want to rework IIO buffer, to be able to add more buffers per IIO
> device, we will merge [somehow] the 'buffer' & 'scan_elements' groups, and
> we will continue to add the attributes to the 'buffer' group.
> 
> Removing it here, will also make the rework here a bit smaller, since
> this code will not be present.
> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
Looks like dead code to me.  Applied to the togreg branch of iio.git and
pushed out as testing for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> 
> I have no idea whether removing this is acceptable or not.
> If it is acceptable, then this can be applied.
> I am a bit vague on how this was ever used, of if it was ever used, but
> it looks like dead code.
> 
> 
>  drivers/iio/industrialio-buffer.c | 8 --------
>  include/linux/iio/buffer_impl.h   | 6 ------
>  2 files changed, 14 deletions(-)
> 
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index e6fa1a4e135d..221157136af6 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -1283,11 +1283,6 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
>  
>  	indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
>  
> -	if (buffer->scan_el_attrs != NULL) {
> -		attr = buffer->scan_el_attrs->attrs;
> -		while (*attr++ != NULL)
> -			attrcount_orig++;
> -	}
>  	attrcount = attrcount_orig;
>  	INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
>  	channels = indio_dev->channels;
> @@ -1325,9 +1320,6 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
>  		ret = -ENOMEM;
>  		goto error_free_scan_mask;
>  	}
> -	if (buffer->scan_el_attrs)
> -		memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
> -		       sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
>  	attrn = attrcount_orig;
>  
>  	list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
> diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h
> index 1e7edf6bed96..a63dc07b7350 100644
> --- a/include/linux/iio/buffer_impl.h
> +++ b/include/linux/iio/buffer_impl.h
> @@ -94,12 +94,6 @@ struct iio_buffer {
>  	unsigned int watermark;
>  
>  	/* private: */
> -	/*
> -	 * @scan_el_attrs: Control of scan elements if that scan mode
> -	 * control method is used.
> -	 */
> -	struct attribute_group *scan_el_attrs;
> -
>  	/* @scan_timestamp: Does the scan mode include a timestamp. */
>  	bool scan_timestamp;
>