Re: [Intel-gfx] [PATCH v2 12/15] drm/edid: do invalid block filtering in-place

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Jun 08, 2022 at 10:50:42AM +0300, Jani Nikula wrote:
> Rewrite edid_filter_invalid_blocks() to filter invalid blocks
> in-place. The main motivation is to not rely on passed in information on
> invalid block count or the allocation size, which will be helpful in
> follow-up work on HF-EEODB.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/drm_edid.c | 43 ++++++++++++++++++++------------------
>  1 file changed, 23 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 4e788c5cbf25..77ec5b0e436d 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2020,33 +2020,37 @@ bool drm_edid_is_valid(struct edid *edid)
>  }
>  EXPORT_SYMBOL(drm_edid_is_valid);
>  
> -static struct edid *edid_filter_invalid_blocks(const struct edid *edid,
> -					       int invalid_blocks,
> +static struct edid *edid_filter_invalid_blocks(struct edid *edid,
>  					       size_t *alloc_size)
>  {
> -	struct edid *new, *dest_block;
> -	int valid_extensions = edid->extensions - invalid_blocks;
> -	int i;
> +	struct edid *new;
> +	int i, valid_blocks = 0;
>  
> -	*alloc_size = edid_size_by_blocks(valid_extensions + 1);
> +	for (i = 0; i < edid_block_count(edid); i++) {
> +		const void *src_block = edid_block_data(edid, i);
>  
> -	new = kmalloc(*alloc_size, GFP_KERNEL);
> -	if (!new)
> -		goto out;
> +		if (edid_block_valid(src_block, i == 0)) {
> +			void *dst_block = (void *)edid_block_data(edid, valid_blocks);
>  
> -	dest_block = new;
> -	for (i = 0; i < edid_block_count(edid); i++) {
> -		const void *block = edid_block_data(edid, i);
> +			memmove(dst_block, src_block, EDID_LENGTH);
> +			valid_blocks++;
> +		}
> +	}
>  
> -		if (edid_block_valid(block, i == 0))
> -			memcpy(dest_block++, block, EDID_LENGTH);
> +	/* We already trusted the base block to be valid here... */
> +	if (WARN_ON(!valid_blocks)) {
> +		kfree(edid);
> +		return NULL;
>  	}
>  
> -	new->extensions = valid_extensions;
> -	new->checksum = edid_block_compute_checksum(new);
> +	edid->extensions = valid_blocks - 1;
> +	edid->checksum = edid_block_compute_checksum(edid);
>  
> -out:
> -	kfree(edid);
> +	*alloc_size = edid_size_by_blocks(valid_blocks);
> +
> +	new = krealloc(edid, *alloc_size, GFP_KERNEL);
> +	if (!new)
> +		kfree(edid);
>  
>  	return new;
>  }
> @@ -2290,8 +2294,7 @@ static struct edid *_drm_do_get_edid(struct drm_connector *connector,
>  	if (invalid_blocks) {
>  		connector_bad_edid(connector, edid, edid_block_count(edid));
>  
> -		edid = edid_filter_invalid_blocks(edid, invalid_blocks,
> -						  &alloc_size);
> +		edid = edid_filter_invalid_blocks(edid, &alloc_size);
>  	}
>  
>  ok:
> -- 
> 2.30.2

-- 
Ville Syrjälä
Intel