From bb758421416fd8af2267a8e07d53fb8328b07c4e Mon Sep 17 00:00:00 2001 From: Shakeel Butt Date: Sun, 24 Oct 2021 23:19:15 -0700 Subject: cgroup: remove cgroup_mutex from cgroupstats_build The function cgroupstats_build extracts cgroup from the kernfs_node's priv pointer which is a RCU pointer. So, there is no need to grab cgroup_mutex. Just get the reference on the cgroup before using and remove the cgroup_mutex altogether. Signed-off-by: Shakeel Butt Signed-off-by: Tejun Heo --- kernel/cgroup/cgroup-v1.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'kernel/cgroup') diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index f6cc5f8484dc..fd14a60379c1 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -698,8 +698,6 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) kernfs_type(kn) != KERNFS_DIR) return -EINVAL; - mutex_lock(&cgroup_mutex); - /* * We aren't being called from kernfs and there's no guarantee on * @kn->priv's validity. For this and css_tryget_online_from_dir(), @@ -707,9 +705,8 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) */ rcu_read_lock(); cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv); - if (!cgrp || cgroup_is_dead(cgrp)) { + if (!cgrp || !cgroup_tryget(cgrp)) { rcu_read_unlock(); - mutex_unlock(&cgroup_mutex); return -ENOENT; } rcu_read_unlock(); @@ -737,7 +734,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) } css_task_iter_end(&it); - mutex_unlock(&cgroup_mutex); + cgroup_put(cgrp); return 0; } -- cgit v1.2.3