linux-kernel - [PATCH 3/3] cgroup/cpuset: Remove the unnecessary css_get/put() in cpuset_partition

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Message-ID: <20250806172430.1155133-4-longman@redhat.com>
Date: Wed,  6 Aug 2025 13:24:30 -0400
From: Waiman Long <longman@...hat.com>
To: Tejun Heo <tj@...nel.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Koutný <mkoutny@...e.com>
Cc: cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	Waiman Long <longman@...hat.com>
Subject: [PATCH 3/3] cgroup/cpuset: Remove the unnecessary css_get/put() in cpuset_partition_write()

The css_get/put() calls in cpuset_partition_write() are unnecessary as
an active reference of the kernfs node will be taken which will prevent
its removal and guarantee the existence of the css. Only the online
check is needed.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 kernel/cgroup/cpuset.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index d993e058a663..27adb04df675 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3358,14 +3358,12 @@ static ssize_t cpuset_partition_write(struct kernfs_open_file *of, char *buf,
 	else
 		return -EINVAL;
 
-	css_get(&cs->css);
 	cpus_read_lock();
 	mutex_lock(&cpuset_mutex);
 	if (is_cpuset_online(cs))
 		retval = update_prstate(cs, val);
 	mutex_unlock(&cpuset_mutex);
 	cpus_read_unlock();
-	css_put(&cs->css);
 	return retval ?: nbytes;
 }
 
-- 
2.50.0