Re: [PATCH v4 7/7] x86/resctrl: Add debug files when mounted with debug option

Ilpo Järvinen
2023-04-19T13:21:14Z

On Mon, 17 Apr 2023, Babu Moger wrote:

> Add the debug files to the resctrl hierarchy.
>
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---
> arch/x86/kernel/cpu/resctrl/internal.h | 1 +
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 54 +++++++++++++++++++++++++++++++-
> 2 files changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 1eac07ebc31b..855109abb480 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -288,6 +288,7 @@ struct rdtgroup {
> #define RFTYPE_TOP BIT(4)
> #define RFTYPE_RES_CACHE BIT(5)
> #define RFTYPE_RES_MB BIT(6)
> +#define RFTYPE_DEBUG BIT(7)
> #define RFTYPE_CTRL_INFO (RFTYPE_INFO | RFTYPE_CTRL)
> #define RFTYPE_MON_INFO (RFTYPE_INFO | RFTYPE_MON)
> #define RFTYPE_TOP_INFO (RFTYPE_INFO | RFTYPE_TOP)
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 15ded0dd5b09..1ec4359348c2 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -1880,6 +1880,7 @@ static struct rftype res_common_files[] = {
> .mode = 0444,
> .kf_ops = &rdtgroup_kf_single_ops,
> .seq_show = rdtgroup_rmid_show,
> + .fflags = RFTYPE_BASE | RFTYPE_DEBUG,
> },
> {
> .name = "schemata",
> @@ -1909,6 +1910,7 @@ static struct rftype res_common_files[] = {
> .mode = 0444,
> .kf_ops = &rdtgroup_kf_single_ops,
> .seq_show = rdtgroup_closid_show,
> + .fflags = RFTYPE_CTRL_BASE | RFTYPE_DEBUG,
> },
>
> };
> @@ -2420,6 +2422,49 @@ static int mkdir_mondata_all(struct kernfs_node *parent_kn,
> struct rdtgroup *prgrp,
> struct kernfs_node **mon_data_kn);
>
> +static void resctrl_add_debug_files(void)
> +{
> + struct rftype *rfts, *rft;
> + int len;
> +
> + rfts = res_common_files;
> + len = ARRAY_SIZE(res_common_files);
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + for (rft = rfts; rft < rfts + len; rft++) {
> + if (rft->fflags & RFTYPE_DEBUG) {
> + rft->fflags &= ~RFTYPE_DEBUG;

I don't fully follow why you need to play with ->fflags like this.

Is it for the ->fflags test in rdtgroup_add_files()? Can't you just do
some extra masking there for RFTYPE_DEBUG based on resctrl_debug which
you already keep?

> + rdtgroup_add_file(rdtgroup_default.kn, rft);
> + }
> + }
> +
> + kernfs_activate(rdtgroup_default.kn);
> +}
> +
> +static void resctrl_remove_debug_files(void)
> +{
> + struct rftype *rfts, *rft;
> + int len;
> +
> + rfts = res_common_files;
> + len = ARRAY_SIZE(res_common_files);
> +
> + lockdep_assert_held(&rdtgroup_mutex);
> +
> + for (rft = rfts; rft < rfts + len; rft++) {
> + if (!strcmp(rft->name, "mon_hw_id")) {
> + rft->fflags |= RFTYPE_DEBUG;
> + kernfs_remove_by_name(rdtgroup_default.kn, rft->name);
> + } else if (!strcmp(rft->name, "ctrl_hw_id")) {
> + rft->fflags |= RFTYPE_DEBUG;
> + kernfs_remove_by_name(rdtgroup_default.kn, rft->name);
> + }
> + }
> +
> + kernfs_activate(rdtgroup_default.kn);
> +}
> +
> static int rdt_enable_ctx(struct rdt_fs_context *ctx)
> {
> int ret = 0;
> @@ -2433,8 +2478,10 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
> if (!ret && ctx->enable_mba_mbps)
> ret = set_mba_sc(true);
>
> - if (!ret && ctx->enable_debug)
> + if (!ret && ctx->enable_debug) {
> resctrl_debug = true;
> + resctrl_add_debug_files();
> + }
>
> return ret;
> }
> @@ -2851,6 +2898,11 @@ static void rdt_kill_sb(struct super_block *sb)
>
> set_mba_sc(false);
>
> + if (resctrl_debug) {
> + resctrl_remove_debug_files();
> + resctrl_debug = false;

Logically, this false assignment belongs to the earlier patch.

--
i.