linux-kernel - [PATCH v2 -next] cgroup/cpuset: remove child_ecpus

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Message-ID: <20240724102418.2213801-1-chenridong@huawei.com>
Date: Wed, 24 Jul 2024 10:24:18 +0000
From: Chen Ridong <chenridong@...wei.com>
To: <tj@...nel.org>, <lizefan.x@...edance.com>, <hannes@...xchg.org>,
	<longman@...hat.com>, <adityakali@...gle.com>, <sergeh@...nel.org>,
	<mkoutny@...e.com>
CC: <cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 -next] cgroup/cpuset: remove child_ecpus_count

The child_ecpus_count variable was previously used to update
sibling cpumask when parent's effective_cpus is updated. However, it became
obsolete after commit e2ffe502ba45 ("cgroup/cpuset: Add
cpuset.cpus.exclusive for v2"). It should be removed.

Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
 kernel/cgroup/cpuset.c | 25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 40ec4abaf440..d4322619e59a 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -188,10 +188,8 @@ struct cpuset {
 	/*
 	 * Default hierarchy only:
 	 * use_parent_ecpus - set if using parent's effective_cpus
-	 * child_ecpus_count - # of children with use_parent_ecpus set
 	 */
 	int use_parent_ecpus;
-	int child_ecpus_count;
 
 	/*
 	 * number of SCHED_DEADLINE tasks attached to this cpuset, so that we
@@ -1512,7 +1510,6 @@ static void reset_partition_data(struct cpuset *cs)
 	if (!cpumask_and(cs->effective_cpus,
 			 parent->effective_cpus, cs->cpus_allowed)) {
 		cs->use_parent_ecpus = true;
-		parent->child_ecpus_count++;
 		cpumask_copy(cs->effective_cpus, parent->effective_cpus);
 	}
 }
@@ -1688,12 +1685,8 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs,
 	spin_lock_irq(&callback_lock);
 	isolcpus_updated = partition_xcpus_add(new_prs, NULL, tmp->new_cpus);
 	list_add(&cs->remote_sibling, &remote_children);
-	if (cs->use_parent_ecpus) {
-		struct cpuset *parent = parent_cs(cs);
-
+	if (cs->use_parent_ecpus)
 		cs->use_parent_ecpus = false;
-		parent->child_ecpus_count--;
-	}
 	spin_unlock_irq(&callback_lock);
 	update_unbound_workqueue_cpumask(isolcpus_updated);
 
@@ -2318,15 +2311,10 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
 		 */
 		if (is_in_v2_mode() && !remote && cpumask_empty(tmp->new_cpus)) {
 			cpumask_copy(tmp->new_cpus, parent->effective_cpus);
-			if (!cp->use_parent_ecpus) {
+			if (!cp->use_parent_ecpus)
 				cp->use_parent_ecpus = true;
-				parent->child_ecpus_count++;
-			}
-		} else if (cp->use_parent_ecpus) {
+		} else if (cp->use_parent_ecpus)
 			cp->use_parent_ecpus = false;
-			WARN_ON_ONCE(!parent->child_ecpus_count);
-			parent->child_ecpus_count--;
-		}
 
 		if (remote)
 			goto get_css;
@@ -4139,7 +4127,6 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
 		cpumask_copy(cs->effective_cpus, parent->effective_cpus);
 		cs->effective_mems = parent->effective_mems;
 		cs->use_parent_ecpus = true;
-		parent->child_ecpus_count++;
 	}
 	spin_unlock_irq(&callback_lock);
 
@@ -4205,12 +4192,8 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css)
 	    is_sched_load_balance(cs))
 		update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
 
-	if (cs->use_parent_ecpus) {
-		struct cpuset *parent = parent_cs(cs);
-
+	if (cs->use_parent_ecpus)
 		cs->use_parent_ecpus = false;
-		parent->child_ecpus_count--;
-	}
 
 	cpuset_dec();
 	clear_bit(CS_ONLINE, &cs->flags);
-- 
2.34.1