linux-kernel - [PATCH -next RFC 02/16] cpuset: generalize validate

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Message-Id: <20250928071306.3797436-3-chenridong@huaweicloud.com>
Date: Sun, 28 Sep 2025 07:12:52 +0000
From: Chen Ridong <chenridong@...weicloud.com>
To: longman@...hat.com,
	tj@...nel.org,
	hannes@...xchg.org,
	mkoutny@...e.com
Cc: cgups@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	lujialin4@...wei.com,
	chenridong@...wei.com
Subject: [PATCH -next RFC 02/16] cpuset: generalize 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 local partition enablement
validation scenarios. This prepares the function for broader use cases
beyond its current validation scope while maintaining backward
compatibility with existing callers.

Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
 kernel/cgroup/cpuset.c | 77 ++++++++++++++++++------------------------
 1 file changed, 33 insertions(+), 44 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 052f9e0c7a65..0787904321a9 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1702,6 +1702,34 @@ static bool prstate_housekeeping_conflict(int prstate, struct cpumask *new_cpus)
 	return false;
 }
 
+/**
+ * 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 exclusize CPUs mask to validate
+ *
+ * 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 cpuset *parent = parent_cs(cs);
+
+	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 (tasks_nocpu_error(parent, cs, new_excpus))
+		return PERR_NOCPUS;
+
+	return PERR_NONE;
+}
+
 /**
  * update_parent_effective_cpumask - update effective_cpus mask of parent cpuset
  * @cs:      The cpuset that requests change in partition root state
@@ -1805,19 +1833,9 @@ 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 (tasks_nocpu_error(parent, cs, xcpus))
-			return PERR_NOCPUS;
-
+		part_error = validate_partition(cs, new_prs, xcpus);
+		if (part_error)
+			return part_error;
 		/*
 		 * This function will only be called when all the preliminary
 		 * checks have passed. At this point, the following condition
@@ -2367,36 +2385,6 @@ 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)
 {
@@ -2451,7 +2439,8 @@ 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);
 	if (prs_err)
 		trialcs->prs_err = cs->prs_err = prs_err;
 
-- 
2.34.1