Re: [PATCH 05/11] fs/resctrl: Use accurate type for rdt_resource::rid

Reinette Chatre
2026-03-17T17:35:13Z

Hi Ben,

On 3/17/26 4:23 AM, Ben Horgan wrote:
> Hi Reinette,
>
> On 3/2/26 18:46, Reinette Chatre wrote:
>> Every resctrl resource has a unique ID described by enum resctrl_res_level.
>> enum resctrl_res_level is used in all resource ID initializations and all
>> resource ID comparisons. All functions consuming the resource ID expects an
>> enum resctrl_res_level. Of the four structures that contain a resource ID
>> (struct mon_data, struct mon_evt, struct rdt_domain_hdr, and struct
>> rdt_resource) only struct rdt_resource does not use enum resctrl_res_level.
>>
>> Switch the type of rdt_resource::rid to be enum resctrl_res_level to make
>> it obvious what values are valid, match the type everywhere this member is
>> used, and obtain benefits from tools that can flag any enum misuse.
>>
>> Move define of RDT_NUM_RESOURCES outside the enum to enable tools to catch
>> when a switch() on the resource ID does not handle all the resources and
>> thus help flag which switch statements need an update when a new resource
>> is added.
>>
>> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
>> ---
>> include/linux/resctrl.h | 8 ++++----
>> 1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
>> index 006e57fd7ca5..48e95f273fb3 100644
>> --- a/include/linux/resctrl.h
>> +++ b/include/linux/resctrl.h
>> @@ -54,11 +54,11 @@ enum resctrl_res_level {
>> RDT_RESOURCE_MBA,
>> RDT_RESOURCE_SMBA,
>> RDT_RESOURCE_PERF_PKG,
>> -
>> - /* Must be the last */
>> - RDT_NUM_RESOURCES,
>> + /* Additions to enum need to update RDT_NUM_RESOURCES. */
>> };>
>> +#define RDT_NUM_RESOURCES (RDT_RESOURCE_PERF_PKG + 1)
>
> Would it be clearer to have RDT_RESOURCE_LAST = RDT_RESOURCE_PERF_PKG in the enum
> and use RDT_RESOURCE_LAST instead of RDT_RESOURCE_PERF_PKG here?

It would. Thank you very much for the suggestion. To have resctrl code be consistent
I'll add another patch that also switches enum resctrl_conf_type to use this pattern.

Reinette