Re: [PATCH v5 03/40] x86/resctrl: Remove fflags from struct rdt_resource
From: Reinette Chatre
Date: Wed Oct 23 2024 - 17:04:56 EST
Hi James,
On 10/4/24 11:03 AM, James Morse wrote:
> The resctrl arch code specifies whether a resource controls a cache or
> memory using the fflags field. This field is then used by resctrl to
> determine which files should be exposed in the filesystem.
>
> Allowing the architecture to pick this value means the RFTYPE_
> flags have to be in a shared header, and allows an architecture
> to create a combination that resctrl does not support.
>
> Remove the fflags field, and pick the value based on the resource
> id.
>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Tested-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
> ---
> Changes since v4:
> * Removed an extra space
Looks like this fixup was squashed into the next patch instead.
> * Fixed a typo
> ---
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 6225d0b7e9ee..2abe17574407 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2160,6 +2160,20 @@ static int rdtgroup_mkdir_info_resdir(void *priv, char *name,
> return ret;
> }
>
> +static u32 fflags_from_resource(struct rdt_resource *r)
What is motivation for the return type of u32? I am trying to understand why this is needed
considering the value returned, variable it is assigned to, and the functions that use it
(rdtgroup_mkdir_info_resdir() and rdtgroup_add_files()) all use unsigned long.
> +{
> + switch (r->rid) {
> + case RDT_RESOURCE_L3:
> + case RDT_RESOURCE_L2:
> + return RFTYPE_RES_CACHE;
> + case RDT_RESOURCE_MBA:
> + case RDT_RESOURCE_SMBA:
> + return RFTYPE_RES_MB;
> + }
> +
> + return WARN_ON_ONCE(1);
> +}
> +
> static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
> {
> struct resctrl_schema *s;
> @@ -2180,14 +2194,14 @@ static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
> /* loop over enabled controls, these are all alloc_capable */
> list_for_each_entry(s, &resctrl_schema_all, list) {
> r = s->res;
> - fflags = r->fflags | RFTYPE_CTRL_INFO;
> + fflags = fflags_from_resource(r) | RFTYPE_CTRL_INFO;
> ret = rdtgroup_mkdir_info_resdir(s, s->name, fflags);
> if (ret)
> goto out_destroy;
> }
>
> for_each_mon_capable_rdt_resource(r) {
> - fflags = r->fflags | RFTYPE_MON_INFO;
> + fflags = fflags_from_resource(r) | RFTYPE_MON_INFO;
Fixup did not make it here.
Reinette