linux-kernel - [PATCH v6 07/30] x86,fs/resctrl: Refactor domain_remove_cpu

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Message-ID: <20250626164941.106341-8-tony.luck@intel.com>
Date: Thu, 26 Jun 2025 09:49:16 -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>,
	Anil Keshavamurthy <anil.s.keshavamurthy@...el.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 v6 07/30] x86,fs/resctrl: Refactor domain_remove_cpu_mon() ready for new domain types

Historically all monitoring events have been associated with the L3
resource. This will change when support for telemetry events is added.

The RDT_RESOURCE_L3 resource carries a lot of state in the domain
structures which needs to be dealt with when a domain is taken offline
by removing the last CPU in the domain.

Refactor domain_remove_cpu_mon() so all the L3 processing is separated
from general actions of clearing the CPU bit in the mask and removing
directories from mon_data.

resctrl_offline_mon_domain() will still need to remove domain specific
directories and files from the "mon_data" directories, but can skip the
L3 resource specific cleanup when called for other resource types.

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/resctrl/core.c | 17 +++++++++++------
 fs/resctrl/rdtgroup.c              |  5 ++++-
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 20b6f2bbf858..4bf264b6a333 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -648,17 +648,22 @@ static void domain_remove_cpu_mon(int cpu, struct rdt_resource *r)
 	if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, r->rid))
 		return;
 
-	d = container_of(hdr, struct rdt_mon_domain, hdr);
-	hw_dom = resctrl_to_arch_mon_dom(d);
-
 	cpumask_clear_cpu(cpu, &d->hdr.cpu_mask);
-	if (cpumask_empty(&d->hdr.cpu_mask)) {
+	if (!cpumask_empty(&d->hdr.cpu_mask))
+		return;
+
+	switch (r->rid) {
+	case RDT_RESOURCE_L3:
+		d = container_of(hdr, struct rdt_mon_domain, hdr);
+		hw_dom = resctrl_to_arch_mon_dom(d);
 		resctrl_offline_mon_domain(r, d);
 		list_del_rcu(&d->hdr.list);
 		synchronize_rcu();
 		mon_domain_free(hw_dom);
-
-		return;
+		break;
+	default:
+		pr_warn_once("Unknown resource rid=%d\n", r->rid);
+		break;
 	}
 }
 
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 77336d5e4915..05438e15e2ca 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -4047,6 +4047,9 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_mon_domain *d
 	if (resctrl_mounted && resctrl_arch_mon_capable())
 		rmdir_mondata_subdir_allrdtgrp(r, d);
 
+	if (r->rid != RDT_RESOURCE_L3)
+		goto out_unlock;
+
 	if (resctrl_is_mbm_enabled())
 		cancel_delayed_work(&d->mbm_over);
 	if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID) && has_busy_rmid(d)) {
@@ -4063,7 +4066,7 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_mon_domain *d
 	}
 
 	domain_destroy_mon_state(d);
-
+out_unlock:
 	mutex_unlock(&rdtgroup_mutex);
 }
 
-- 
2.49.0