linux-kernel - [PATCH RFC v2 11/22] cpuset: introduce local_partition

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Message-Id: <20251025064844.495525-12-chenridong@huaweicloud.com>
Date: Sat, 25 Oct 2025 06:48:33 +0000
From: Chen Ridong <chenridong@...weicloud.com>
To: longman@...hat.com,
	tj@...nel.org,
	hannes@...xchg.org,
	mkoutny@...e.com
Cc: cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	lujialin4@...wei.com,
	chenridong@...wei.com
Subject: [PATCH RFC v2 11/22] cpuset: introduce local_partition_disable()

From: Chen Ridong <chenridong@...wei.com>

The partition_disable() function introduced earlier can be extended to
handle local partition disablement.

The local_partition_disable() functions is introduced, which extracts the
local partition disable logic from update_parent_effective_cpumask(). It
calls partition_disable() to complete the disablement process.

This refactoring establishes a clear separation between local and remote
partition operations while promoting code reuse through the shared
partition_disable() infrastructure.

Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
 kernel/cgroup/cpuset.c | 55 ++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 16 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index b308d9f80eef..f36d17a4d8cd 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1877,6 +1877,43 @@ static int local_partition_enable(struct cpuset *cs,
 	return 0;
 }
 
+/**
+ * local_partition_disable - Disable a local partition
+ * @cs: Target cpuset (local partition root) to disable
+ * @part_error: partition error when @cs is disabled
+ * @tmp: Temporary masks for CPU calculations
+ */
+static void local_partition_disable(struct cpuset *cs, enum prs_errcode part_error,
+				    struct tmpmasks *tmp)
+{
+	struct cpuset *parent = parent_cs(cs);
+	bool cpumask_updated = false;
+	int new_prs;
+
+	lockdep_assert_held(&cpuset_mutex);
+	WARN_ON_ONCE(is_remote_partition(cs));	/* For local partition only */
+
+	if (!is_partition_valid(cs))
+		return;
+
+	new_prs = part_error ? -cs->partition_root_state : 0;
+	/*
+	 * May need to add cpus back to parent's effective_cpus
+	 * (and maybe removed from subpartitions_cpus/isolated_cpus)
+	 * for valid partition root. xcpus may contain CPUs that
+	 * shouldn't be removed from the two global cpumasks.
+	 */
+	if (is_partition_valid(parent))
+		cpumask_updated = !cpumask_empty(cs->effective_xcpus);
+
+	partition_disable(cs, parent, new_prs, part_error);
+
+	if (cpumask_updated) {
+		cpuset_update_tasks_cpumask(parent, tmp->addmask);
+		update_sibling_cpumasks(parent, cs, tmp);
+	}
+}
+
 /**
  * update_parent_effective_cpumask - update effective_cpus mask of parent cpuset
  * @cs:      The cpuset that requests change in partition root state
@@ -1967,19 +2004,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
 
 	nocpu = tasks_nocpu_error(parent, cs, xcpus);
 
-	if (cmd == partcmd_disable) {
-		/*
-		 * May need to add cpus back to parent's effective_cpus
-		 * (and maybe removed from subpartitions_cpus/isolated_cpus)
-		 * for valid partition root. xcpus may contain CPUs that
-		 * shouldn't be removed from the two global cpumasks.
-		 */
-		if (is_partition_valid(cs)) {
-			cpumask_copy(tmp->addmask, cs->effective_xcpus);
-			adding = true;
-		}
-		new_prs = PRS_MEMBER;
-	} else if (newmask) {
+	if (newmask) {
 		/*
 		 * Empty cpumask is not allowed
 		 */
@@ -3110,9 +3135,7 @@ static int update_prstate(struct cpuset *cs, int new_prs)
 		if (is_remote_partition(cs))
 			remote_partition_disable(cs, &tmpmask);
 		else
-			update_parent_effective_cpumask(cs, partcmd_disable,
-							NULL, &tmpmask);
-
+			local_partition_disable(cs, PERR_NONE, &tmpmask);
 		/*
 		 * Invalidation of child partitions will be done in
 		 * update_cpumasks_hier().
-- 
2.34.1