linux-kernel - [PATCH v10 03/28] x86,fs/resctrl: Refactor domain_remove_cpu

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Message-ID: <20250912221053.11349-4-tony.luck@intel.com>
Date: Fri, 12 Sep 2025 15:10:24 -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 v10 03/28] x86,fs/resctrl: Refactor domain_remove_cpu_mon() ready for new domain types

All monitoring events are associated with the L3 resource.

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.

New telemetry events will be associated with a new package scoped
resource with new domain structures.

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

Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kernel/cpu/resctrl/core.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 055df4d406d0..b874cbe0218b 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -648,20 +648,25 @@ static void domain_remove_cpu_mon(int cpu, struct rdt_resource *r)
 		return;
 	}
 
-	if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, r->rid))
+	cpumask_clear_cpu(cpu, &hdr->cpu_mask);
+	if (!cpumask_empty(&hdr->cpu_mask))
 		return;
 
-	d = container_of(hdr, struct rdt_mon_domain, hdr);
-	hw_dom = resctrl_to_arch_mon_dom(d);
+	switch (r->rid) {
+	case RDT_RESOURCE_L3:
+		if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_L3))
+			return;
 
-	cpumask_clear_cpu(cpu, &d->hdr.cpu_mask);
-	if (cpumask_empty(&d->hdr.cpu_mask)) {
+		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);
+		list_del_rcu(&hdr->list);
 		synchronize_rcu();
 		mon_domain_free(hw_dom);
-
-		return;
+		break;
+	default:
+		pr_warn_once("Unknown resource rid=%d\n", r->rid);
+		break;
 	}
 }
 
-- 
2.51.0