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 <shakeelb@xxxxxxxxxx>
---
kernel/cgroup/cgroup-v1.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
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;
}
--
2.33.0.1079.g6e70778dc9-goog
