linux-kernel - [PATCH v18 13/17] x86/resctrl: Handle removing directories in Sub-NUMA (SNC) mode

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Date: Wed, 15 May 2024 15:23:21 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghua.yu@...el.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>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v18 13/17] x86/resctrl: Handle removing directories in Sub-NUMA (SNC) mode

In SNC mode there are multiple subdirectories in each L3 level monitor
directory (one for each SNC node). If all the CPUs in an SNC node are
taken offline, then just that SNC node directory must be removed. In
non-SNC mode, or when the last SNC node directory is removed, also
remove the L3 monitor directory.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 43 +++++++++++++++++++++-----
 1 file changed, 36 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index f0f468babdea..cac32ddd3afd 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -3011,17 +3011,46 @@ static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
  * and monitor groups with given domain id.
  */
 static void rmdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
-					   unsigned int dom_id)
+					   struct rdt_mon_domain *d)
 {
 	struct rdtgroup *prgrp, *crgrp;
+	struct rdt_mon_domain *dom;
+	bool remove_all = true;
+	struct kernfs_node *kn;
+	char subname[32];
 	char name[32];
 
+	sprintf(name, "mon_%s_%02d", r->name, d->display_id);
+	if (r->mon_scope != r->mon_display_scope) {
+		int count = 0;
+
+		list_for_each_entry(dom, &r->mon_domains, hdr.list)
+			if (d->display_id == dom->display_id)
+				count++;
+		if (count > 1) {
+			remove_all = false;
+			sprintf(subname, "mon_sub_%s_%02d", r->name, d->hdr.id);
+		}
+	}
+
 	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
-		sprintf(name, "mon_%s_%02d", r->name, dom_id);
-		kernfs_remove_by_name(prgrp->mon.mon_data_kn, name);
+		if (remove_all) {
+			kernfs_remove_by_name(prgrp->mon.mon_data_kn, name);
+		} else {
+			kn = kernfs_find_and_get_ns(prgrp->mon.mon_data_kn, name, NULL);
+			if (kn)
+				kernfs_remove_by_name(kn, subname);
+		}
 
-		list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
-			kernfs_remove_by_name(crgrp->mon.mon_data_kn, name);
+		list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list) {
+			if (remove_all) {
+				kernfs_remove_by_name(crgrp->mon.mon_data_kn, name);
+			} else {
+				kn = kernfs_find_and_get_ns(prgrp->mon.mon_data_kn, name, NULL);
+				if (kn)
+					kernfs_remove_by_name(kn, subname);
+			}
+		}
 	}
 }
 
@@ -3111,8 +3140,8 @@ static int mkdir_mondata_subdir(struct kernfs_node *parent_kn,
 static void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
 					   struct rdt_mon_domain *d)
 {
-	struct kernfs_node *parent_kn;
 	struct rdtgroup *prgrp, *crgrp;
+	struct kernfs_node *parent_kn;
 	struct list_head *head;
 
 	list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
@@ -3984,7 +4013,7 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_mon_domain *d
 	 * per domain monitor data directories.
 	 */
 	if (resctrl_mounted && resctrl_arch_mon_capable())
-		rmdir_mondata_subdir_allrdtgrp(r, d->hdr.id);
+		rmdir_mondata_subdir_allrdtgrp(r, d);
 
 	if (is_mbm_enabled())
 		cancel_delayed_work(&d->mbm_over);
-- 
2.44.0