Re: [PATCH v2 4/6] mtd: partitions: remove kmemdup()

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Fri,  4 Dec 2015 15:25:16 -0800
Brian Norris <computersforpeace@gmail.com> wrote:

> The use of kmemdup() complicates the error handling a bit. We don't
> actually need to allocate new memory, since this reference is treated as
> const, and it is copied into new memory by the partition registration
> code anyway. So remove it.
> 
> Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>

> ---
> New in v2
> 
>  drivers/mtd/mtdcore.c | 16 +++++++---------
>  drivers/mtd/mtdcore.h |  2 +-
>  drivers/mtd/mtdpart.c |  2 +-
>  3 files changed, 9 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
> index 62f83b050978..868ee52d5063 100644
> --- a/drivers/mtd/mtdcore.c
> +++ b/drivers/mtd/mtdcore.c
> @@ -532,7 +532,7 @@ out_error:
>  }
>  
>  static int mtd_add_device_partitions(struct mtd_info *mtd,
> -				     struct mtd_partition *real_parts,
> +				     const struct mtd_partition *real_parts,
>  				     int nbparts)
>  {
>  	int ret;
> @@ -589,16 +589,12 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
>  			      int nr_parts)
>  {
>  	int ret;
> -	struct mtd_partition *real_parts = NULL;
> +	const struct mtd_partition *real_parts = NULL;
>  
>  	ret = parse_mtd_partitions(mtd, types, &real_parts, parser_data);
>  	if (ret <= 0 && nr_parts && parts) {
> -		real_parts = kmemdup(parts, sizeof(*parts) * nr_parts,
> -				     GFP_KERNEL);
> -		if (!real_parts)
> -			ret = -ENOMEM;
> -		else
> -			ret = nr_parts;
> +		real_parts = parts;
> +		ret = nr_parts;
>  	}
>  	/* Didn't come up with either parsed OR fallback partitions */
>  	if (ret < 0) {
> @@ -628,7 +624,9 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
>  	}
>  
>  out:
> -	kfree(real_parts);
> +	/* Cleanup any parsed partitions */
> +	if (real_parts != parts)
> +		kfree(real_parts);
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(mtd_device_parse_register);
> diff --git a/drivers/mtd/mtdcore.h b/drivers/mtd/mtdcore.h
> index 7b0353399a10..537ec66f9cfd 100644
> --- a/drivers/mtd/mtdcore.h
> +++ b/drivers/mtd/mtdcore.h
> @@ -11,7 +11,7 @@ int del_mtd_device(struct mtd_info *mtd);
>  int add_mtd_partitions(struct mtd_info *, const struct mtd_partition *, int);
>  int del_mtd_partitions(struct mtd_info *);
>  int parse_mtd_partitions(struct mtd_info *master, const char * const *types,
> -			 struct mtd_partition **pparts,
> +			 const struct mtd_partition **pparts,
>  			 struct mtd_part_parser_data *data);
>  
>  int __init init_mtdchar(void);
> diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
> index c6fd4b24c822..86691a5c68b9 100644
> --- a/drivers/mtd/mtdpart.c
> +++ b/drivers/mtd/mtdpart.c
> @@ -757,7 +757,7 @@ static const char * const default_mtd_part_types[] = {
>   *   point to an array containing this number of &struct mtd_info objects.
>   */
>  int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
> -			 struct mtd_partition **pparts,
> +			 const struct mtd_partition **pparts,
>  			 struct mtd_part_parser_data *data)
>  {
>  	struct mtd_part_parser *parser;



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com