linux-kernel - [PATCH -next 02/21] cpuset: generalize the validate

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Message-Id: <20251117024627.1128037-3-chenridong@huaweicloud.com>
Date: Mon, 17 Nov 2025 02:46:08 +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 -next 02/21] cpuset: generalize the validate_partition() interface

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

Refactor validate_partition() to accept a more generic parameter set,
making the interface flexible enough to handle both local and remote
partition validation scenarios. Additionally, a check for whether
isolated CPUs can be updated has been added to validate_partition().

Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
 kernel/cgroup/cpuset.c | 87 +++++++++++++++++++-----------------------
 1 file changed, 40 insertions(+), 47 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 0b7545ca4c18..392a0436a19d 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1603,6 +1603,41 @@ static inline bool is_local_partition(struct cpuset *cs)
 	return is_partition_valid(cs) && !is_remote_partition(cs);
 }
 
+/**
+ * validate_partition - Validate a cpuset partition configuration
+ * @cs: The cpuset to validate
+ * @new_prs: The proposed new partition root state
+ * @new_excpus: The new effective exclusive CPUs mask to validate
+ * @add: exclusive CPUs to be added
+ * @del: exclusive CPUs to be deleted
+ *
+ * Return: PRS error code (0 if valid, non-zero error code if invalid)
+ */
+static enum prs_errcode validate_partition(struct cpuset *cs, int new_prs,
+	struct cpumask *new_excpus, struct cpumask *add, struct cpumask *del)
+{
+	struct cpuset *parent = parent_cs(cs);
+	int parent_prs = parent->partition_root_state;
+
+	if (new_prs == PRS_MEMBER)
+		return PERR_NONE;
+
+	if (cpumask_empty(new_excpus))
+		return PERR_INVCPUS;
+
+	if (prstate_housekeeping_conflict(new_prs, new_excpus))
+		return PERR_HKEEPING;
+
+	if ((new_prs == PRS_ISOLATED) && (new_prs != parent_prs) &&
+	    !isolated_cpus_can_update(add, del))
+		return PERR_HKEEPING;
+
+	if (tasks_nocpu_error(parent, cs, new_excpus))
+		return PERR_NOCPUS;
+
+	return PERR_NONE;
+}
+
 /*
  * remote_partition_enable - Enable current cpuset as a remote partition root
  * @cs: the cpuset to update
@@ -1872,22 +1907,9 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
 			WARN_ON_ONCE(!cpumask_empty(cs->exclusive_cpus));
 		new_prs = (cmd == partcmd_enable) ? PRS_ROOT : PRS_ISOLATED;
 
-		/*
-		 * Enabling partition root is not allowed if its
-		 * effective_xcpus is empty.
-		 */
-		if (cpumask_empty(xcpus))
-			return PERR_INVCPUS;
-
-		if (prstate_housekeeping_conflict(new_prs, xcpus))
-			return PERR_HKEEPING;
-
-		if ((new_prs == PRS_ISOLATED) && (new_prs != parent_prs) &&
-		    !isolated_cpus_can_update(xcpus, NULL))
-			return PERR_HKEEPING;
-
-		if (tasks_nocpu_error(parent, cs, xcpus))
-			return PERR_NOCPUS;
+		part_error = validate_partition(cs, new_prs, xcpus, xcpus, NULL);
+		if (part_error)
+			return part_error;
 
 		/*
 		 * This function will only be called when all the preliminary
@@ -2448,36 +2470,6 @@ static int parse_cpuset_cpulist(const char *buf, struct cpumask *out_mask)
 	return 0;
 }
 
-/**
- * validate_partition - Validate a cpuset partition configuration
- * @cs: The cpuset to validate
- * @trialcs: The trial cpuset containing proposed configuration changes
- *
- * If any validation check fails, the appropriate error code is set in the
- * cpuset's prs_err field.
- *
- * Return: PRS error code (0 if valid, non-zero error code if invalid)
- */
-static enum prs_errcode validate_partition(struct cpuset *cs, struct cpuset *trialcs)
-{
-	struct cpuset *parent = parent_cs(cs);
-
-	if (cs_is_member(trialcs))
-		return PERR_NONE;
-
-	if (cpumask_empty(trialcs->effective_xcpus))
-		return PERR_INVCPUS;
-
-	if (prstate_housekeeping_conflict(trialcs->partition_root_state,
-					  trialcs->effective_xcpus))
-		return PERR_HKEEPING;
-
-	if (tasks_nocpu_error(parent, cs, trialcs->effective_xcpus))
-		return PERR_NOCPUS;
-
-	return PERR_NONE;
-}
-
 static int cpus_allowed_validate_change(struct cpuset *cs, struct cpuset *trialcs,
 					struct tmpmasks *tmp)
 {
@@ -2532,7 +2524,8 @@ static void partition_cpus_change(struct cpuset *cs, struct cpuset *trialcs,
 	if (cs_is_member(cs))
 		return;
 
-	prs_err = validate_partition(cs, trialcs);
+	prs_err = validate_partition(cs, trialcs->partition_root_state,
+			trialcs->effective_xcpus, trialcs->effective_xcpus, NULL);
 	if (prs_err)
 		trialcs->prs_err = cs->prs_err = prs_err;
 
-- 
2.34.1