Re: [PATCH] ACPI: NFIT: Fix flexible_array.cocci warnings

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Tue, 2021-01-05 at 13:03 -0800, Dan Williams wrote:
> Julia and 0day report:
> 
>     Zero-length and one-element arrays are deprecated, see
>     Documentation/process/deprecated.rst
>     Flexible-array members should be used instead.
> 
> However, a straight conversion to flexible arrays yields:
> 
>     drivers/acpi/nfit/core.c:2276:4: error: flexible array member in a struct with no named members
>     drivers/acpi/nfit/core.c:2287:4: error: flexible array member in a struct with no named members
> 
> Instead, just use plain arrays not embedded a flexible arrays.

This reads a bit awkwardly, maybe:

  "Just use plain arrays instead of embedded flexible arrays."

Other than that, the patch looks looks good:
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>

> 
> Cc: Denis Efremov <efremov@linux.com>
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Julia Lawall <julia.lawall@inria.fr>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/acpi/nfit/core.c |   75 +++++++++++++++++-----------------------------
>  1 file changed, 28 insertions(+), 47 deletions(-)
> 
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index b11b08a60684..8c5dde628405 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -2269,40 +2269,24 @@ static const struct attribute_group *acpi_nfit_region_attribute_groups[] = {
>  
> 
> 
> 
>  /* enough info to uniquely specify an interleave set */
>  struct nfit_set_info {
> -	struct nfit_set_info_map {
> -		u64 region_offset;
> -		u32 serial_number;
> -		u32 pad;
> -	} mapping[0];
> +	u64 region_offset;
> +	u32 serial_number;
> +	u32 pad;
>  };
>  
> 
> 
> 
>  struct nfit_set_info2 {
> -	struct nfit_set_info_map2 {
> -		u64 region_offset;
> -		u32 serial_number;
> -		u16 vendor_id;
> -		u16 manufacturing_date;
> -		u8  manufacturing_location;
> -		u8  reserved[31];
> -	} mapping[0];
> +	u64 region_offset;
> +	u32 serial_number;
> +	u16 vendor_id;
> +	u16 manufacturing_date;
> +	u8 manufacturing_location;
> +	u8 reserved[31];
>  };
>  
> 
> 
> 
> -static size_t sizeof_nfit_set_info(int num_mappings)
> -{
> -	return sizeof(struct nfit_set_info)
> -		+ num_mappings * sizeof(struct nfit_set_info_map);
> -}
> -
> -static size_t sizeof_nfit_set_info2(int num_mappings)
> -{
> -	return sizeof(struct nfit_set_info2)
> -		+ num_mappings * sizeof(struct nfit_set_info_map2);
> -}
> -
>  static int cmp_map_compat(const void *m0, const void *m1)
>  {
> -	const struct nfit_set_info_map *map0 = m0;
> -	const struct nfit_set_info_map *map1 = m1;
> +	const struct nfit_set_info *map0 = m0;
> +	const struct nfit_set_info *map1 = m1;
>  
> 
> 
> 
>  	return memcmp(&map0->region_offset, &map1->region_offset,
>  			sizeof(u64));
> @@ -2310,8 +2294,8 @@ static int cmp_map_compat(const void *m0, const void *m1)
>  
> 
> 
> 
>  static int cmp_map(const void *m0, const void *m1)
>  {
> -	const struct nfit_set_info_map *map0 = m0;
> -	const struct nfit_set_info_map *map1 = m1;
> +	const struct nfit_set_info *map0 = m0;
> +	const struct nfit_set_info *map1 = m1;
>  
> 
> 
> 
>  	if (map0->region_offset < map1->region_offset)
>  		return -1;
> @@ -2322,8 +2306,8 @@ static int cmp_map(const void *m0, const void *m1)
>  
> 
> 
> 
>  static int cmp_map2(const void *m0, const void *m1)
>  {
> -	const struct nfit_set_info_map2 *map0 = m0;
> -	const struct nfit_set_info_map2 *map1 = m1;
> +	const struct nfit_set_info2 *map0 = m0;
> +	const struct nfit_set_info2 *map1 = m1;
>  
> 
> 
> 
>  	if (map0->region_offset < map1->region_offset)
>  		return -1;
> @@ -2361,22 +2345,22 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  		return -ENOMEM;
>  	import_guid(&nd_set->type_guid, spa->range_guid);
>  
> 
> 
> 
> -	info = devm_kzalloc(dev, sizeof_nfit_set_info(nr), GFP_KERNEL);
> +	info = devm_kcalloc(dev, nr, sizeof(*info), GFP_KERNEL);
>  	if (!info)
>  		return -ENOMEM;
>  
> 
> 
> 
> -	info2 = devm_kzalloc(dev, sizeof_nfit_set_info2(nr), GFP_KERNEL);
> +	info2 = devm_kcalloc(dev, nr, sizeof(*info2), GFP_KERNEL);
>  	if (!info2)
>  		return -ENOMEM;
>  
> 
> 
> 
>  	for (i = 0; i < nr; i++) {
>  		struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
> -		struct nfit_set_info_map *map = &info->mapping[i];
> -		struct nfit_set_info_map2 *map2 = &info2->mapping[i];
>  		struct nvdimm *nvdimm = mapping->nvdimm;
>  		struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);
> -		struct acpi_nfit_memory_map *memdev = memdev_from_spa(acpi_desc,
> -				spa->range_index, i);
> +		struct nfit_set_info *map = &info[i];
> +		struct nfit_set_info2 *map2 = &info2[i];
> +		struct acpi_nfit_memory_map *memdev =
> +			memdev_from_spa(acpi_desc, spa->range_index, i);
>  		struct acpi_nfit_control_region *dcr = nfit_mem->dcr;
>  
> 
> 
> 
>  		if (!memdev || !nfit_mem->dcr) {
> @@ -2395,23 +2379,20 @@ static int acpi_nfit_init_interleave_set(struct acpi_nfit_desc *acpi_desc,
>  	}
>  
> 
> 
> 
>  	/* v1.1 namespaces */
> -	sort(&info->mapping[0], nr, sizeof(struct nfit_set_info_map),
> -			cmp_map, NULL);
> -	nd_set->cookie1 = nd_fletcher64(info, sizeof_nfit_set_info(nr), 0);
> +	sort(info, nr, sizeof(*info), cmp_map, NULL);
> +	nd_set->cookie1 = nd_fletcher64(info, sizeof(*info) * nr, 0);
>  
> 
> 
> 
>  	/* v1.2 namespaces */
> -	sort(&info2->mapping[0], nr, sizeof(struct nfit_set_info_map2),
> -			cmp_map2, NULL);
> -	nd_set->cookie2 = nd_fletcher64(info2, sizeof_nfit_set_info2(nr), 0);
> +	sort(info2, nr, sizeof(*info2), cmp_map2, NULL);
> +	nd_set->cookie2 = nd_fletcher64(info2, sizeof(*info2) * nr, 0);
>  
> 
> 
> 
>  	/* support v1.1 namespaces created with the wrong sort order */
> -	sort(&info->mapping[0], nr, sizeof(struct nfit_set_info_map),
> -			cmp_map_compat, NULL);
> -	nd_set->altcookie = nd_fletcher64(info, sizeof_nfit_set_info(nr), 0);
> +	sort(info, nr, sizeof(*info), cmp_map_compat, NULL);
> +	nd_set->altcookie = nd_fletcher64(info, sizeof(*info) * nr, 0);
>  
> 
> 
> 
>  	/* record the result of the sort for the mapping position */
>  	for (i = 0; i < nr; i++) {
> -		struct nfit_set_info_map2 *map2 = &info2->mapping[i];
> +		struct nfit_set_info2 *map2 = &info2[i];
>  		int j;
>  
> 
> 
> 
>  		for (j = 0; j < nr; j++) {
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