Re: [PATCH 1/2] EDAC/scrub: Reduce stack usage in scrub_create_desc()

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Mon, 30 Jun 2025 17:20:33 +0100
<shiju.jose@huawei.com> wrote:

> From: Shiju Jose <shiju.jose@huawei.com>
> 
> Constructing an array on the stack can exceed the warning limit
> for per-function stack usage.
> 
> Change this to have the actual attribute array allocated statically and
> then add the instance number on the per-instance copy.
> 
> Fixes: f90b738166fe ("EDAC: Add scrub control feature")
> Suggested-by: Borislav Petkov (AMD) <bp@alien8.de>
> Signed-off-by: Shiju Jose <shiju.jose@huawei.com>

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

> ---
>  drivers/edac/scrub.c | 31 +++++++++++--------------------
>  1 file changed, 11 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/edac/scrub.c b/drivers/edac/scrub.c
> index f9d02af2fc3a..850347d274e8 100755
> --- a/drivers/edac/scrub.c
> +++ b/drivers/edac/scrub.c
> @@ -142,17 +142,14 @@ static umode_t scrub_attr_visible(struct kobject *kobj, struct attribute *a, int
>  	return 0;
>  }
>  
> -#define EDAC_SCRUB_ATTR_RO(_name, _instance)       \
> -	((struct edac_scrub_dev_attr) { .dev_attr = __ATTR_RO(_name), \
> -					.instance = _instance })
> -
> -#define EDAC_SCRUB_ATTR_WO(_name, _instance)       \
> -	((struct edac_scrub_dev_attr) { .dev_attr = __ATTR_WO(_name), \
> -					.instance = _instance })
> -
> -#define EDAC_SCRUB_ATTR_RW(_name, _instance)       \
> -	((struct edac_scrub_dev_attr) { .dev_attr = __ATTR_RW(_name), \
> -					.instance = _instance })
> +static const struct device_attribute scrub_dev_attr[] = {
> +	[SCRUB_ADDRESS]		    = __ATTR_RW(addr),
> +	[SCRUB_SIZE]		    = __ATTR_RW(size),
> +	[SCRUB_ENABLE_BACKGROUND]   = __ATTR_RW(enable_background),
> +	[SCRUB_MIN_CYCLE_DURATION]  = __ATTR_RO(min_cycle_duration),
> +	[SCRUB_MAX_CYCLE_DURATION]  = __ATTR_RO(max_cycle_duration),
> +	[SCRUB_CUR_CYCLE_DURATION]  = __ATTR_RW(current_cycle_duration)
> +};
>  
>  static int scrub_create_desc(struct device *scrub_dev,
>  			     const struct attribute_group **attr_groups, u8 instance)
> @@ -160,14 +157,6 @@ static int scrub_create_desc(struct device *scrub_dev,
>  	struct edac_scrub_context *scrub_ctx;
>  	struct attribute_group *group;
>  	int i;
> -	struct edac_scrub_dev_attr dev_attr[] = {
> -		[SCRUB_ADDRESS] = EDAC_SCRUB_ATTR_RW(addr, instance),
> -		[SCRUB_SIZE] = EDAC_SCRUB_ATTR_RW(size, instance),
> -		[SCRUB_ENABLE_BACKGROUND] = EDAC_SCRUB_ATTR_RW(enable_background, instance),
> -		[SCRUB_MIN_CYCLE_DURATION] = EDAC_SCRUB_ATTR_RO(min_cycle_duration, instance),
> -		[SCRUB_MAX_CYCLE_DURATION] = EDAC_SCRUB_ATTR_RO(max_cycle_duration, instance),
> -		[SCRUB_CUR_CYCLE_DURATION] = EDAC_SCRUB_ATTR_RW(current_cycle_duration, instance)
> -	};
>  
>  	scrub_ctx = devm_kzalloc(scrub_dev, sizeof(*scrub_ctx), GFP_KERNEL);
>  	if (!scrub_ctx)
> @@ -175,7 +164,9 @@ static int scrub_create_desc(struct device *scrub_dev,
>  
>  	group = &scrub_ctx->group;
>  	for (i = 0; i < SCRUB_MAX_ATTRS; i++) {
> -		memcpy(&scrub_ctx->scrub_dev_attr[i], &dev_attr[i], sizeof(dev_attr[i]));
> +		scrub_ctx->scrub_dev_attr[i].dev_attr = scrub_dev_attr[i];
> +		scrub_ctx->scrub_dev_attr[i].instance = instance;
> +
>  		sysfs_attr_init(&scrub_ctx->scrub_dev_attr[i].dev_attr.attr);
>  		scrub_ctx->scrub_attrs[i] = &scrub_ctx->scrub_dev_attr[i].dev_attr.attr;
>  	}