linux-kernel - [PATCH v12 20/31] fs/resctrl: Refactor mkdir_mondata

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Message-ID: <20251013223348.103390-21-tony.luck@intel.com>
Date: Mon, 13 Oct 2025 15:33:34 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>,
	Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>,
	Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v12 20/31] fs/resctrl: Refactor mkdir_mondata_subdir()

mkdir_mondata_subdir() is unreasonably complicated because of the support for
Sub-NUMA Cluster (SNC) mode.

Split out the SNC code into a helper function to make it easier to add support
for a new telemetry resource.

Suggested-by: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 fs/resctrl/rdtgroup.c | 83 +++++++++++++++++++++++++++----------------
 1 file changed, 52 insertions(+), 31 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index c9d2cc1fd8bf..b7eaa4388768 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -3196,22 +3196,16 @@ static void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
 
 static int mon_add_all_files(struct kernfs_node *kn, struct rdt_domain_hdr *hdr,
 			     struct rdt_resource *r, struct rdtgroup *prgrp,
-			     bool do_sum)
+			     int domid, bool do_sum)
 {
 	struct rmid_read rr = {0};
-	struct rdt_l3_mon_domain *d;
 	struct mon_data *priv;
 	struct mon_evt *mevt;
-	int ret, domid;
-
-	if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
-		return -EINVAL;
+	int ret;
 
-	d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
 	for_each_mon_event(mevt) {
 		if (mevt->rid != r->rid || !mevt->enabled)
 			continue;
-		domid = do_sum ? d->ci_id : d->hdr.id;
 		priv = mon_get_kn_priv(r->rid, domid, mevt, do_sum);
 		if (WARN_ON_ONCE(!priv))
 			return -EINVAL;
@@ -3227,24 +3221,20 @@ static int mon_add_all_files(struct kernfs_node *kn, struct rdt_domain_hdr *hdr,
 	return 0;
 }
 
-static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
-				struct rdt_domain_hdr *hdr,
-				struct rdt_resource *r, struct rdtgroup *prgrp)
+static int mkdir_mondata_subdir_snc(struct kernfs_node *parent_kn,
+				    struct rdt_domain_hdr *hdr,
+				    struct rdt_resource *r, struct rdtgroup *prgrp)
 {
 	struct kernfs_node *kn, *ckn;
 	struct rdt_l3_mon_domain *d;
 	char name[32];
-	bool snc_mode;
 	int ret = 0;
 
-	lockdep_assert_held(&rdtgroup_mutex);
-
 	if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
 		return -EINVAL;
 
 	d = container_of(hdr, struct rdt_l3_mon_domain, hdr);
-	snc_mode = r->mon_scope == RESCTRL_L3_NODE;
-	sprintf(name, "mon_%s_%02d", r->name, snc_mode ? d->ci_id : d->hdr.id);
+	sprintf(name, "mon_%s_%02d", r->name, d->ci_id);
 	kn = kernfs_find_and_get(parent_kn, name);
 	if (kn) {
 		/*
@@ -3260,27 +3250,58 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
 		ret = rdtgroup_kn_set_ugid(kn);
 		if (ret)
 			goto out_destroy;
-		ret = mon_add_all_files(kn, hdr, r, prgrp, snc_mode);
+		ret = mon_add_all_files(kn, hdr, r, prgrp, d->ci_id, true);
 		if (ret)
 			goto out_destroy;
 	}
 
-	if (snc_mode) {
-		sprintf(name, "mon_sub_%s_%02d", r->name, hdr->id);
-		ckn = kernfs_create_dir(kn, name, parent_kn->mode, prgrp);
-		if (IS_ERR(ckn)) {
-			ret = -EINVAL;
-			goto out_destroy;
-		}
+	sprintf(name, "mon_sub_%s_%02d", r->name, hdr->id);
+	ckn = kernfs_create_dir(kn, name, parent_kn->mode, prgrp);
+	if (IS_ERR(ckn)) {
+		ret = -EINVAL;
+		goto out_destroy;
+	}
 
-		ret = rdtgroup_kn_set_ugid(ckn);
-		if (ret)
-			goto out_destroy;
+	ret = rdtgroup_kn_set_ugid(ckn);
+	if (ret)
+		goto out_destroy;
 
-		ret = mon_add_all_files(ckn, hdr, r, prgrp, false);
-		if (ret)
-			goto out_destroy;
-	}
+	ret = mon_add_all_files(ckn, hdr, r, prgrp, hdr->id, false);
+	if (ret)
+		goto out_destroy;
+
+	kernfs_activate(kn);
+	return 0;
+
+out_destroy:
+	kernfs_remove(kn);
+	return ret;
+}
+
+static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
+				struct rdt_domain_hdr *hdr,
+				struct rdt_resource *r, struct rdtgroup *prgrp)
+{
+	struct kernfs_node *kn;
+	char name[32];
+	int ret = 0;
+
+	lockdep_assert_held(&rdtgroup_mutex);
+
+	if (r->mon_scope == RESCTRL_L3_NODE)
+		return mkdir_mondata_subdir_snc(parent_kn, hdr, r, prgrp);
+
+	sprintf(name, "mon_%s_%02d", r->name, hdr->id);
+	kn = kernfs_create_dir(parent_kn, name, parent_kn->mode, prgrp);
+	if (IS_ERR(kn))
+		return PTR_ERR(kn);
+
+	ret = rdtgroup_kn_set_ugid(kn);
+	if (ret)
+		goto out_destroy;
+	ret = mon_add_all_files(kn, hdr, r, prgrp, hdr->id, false);
+	if (ret)
+		goto out_destroy;
 
 	kernfs_activate(kn);
 	return 0;
-- 
2.51.0