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| author | Shakeel Butt <shakeelb@google.com> | 2021-10-24 23:19:15 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2021-10-25 07:24:03 -1000 |
| commit | bb758421416fd8af2267a8e07d53fb8328b07c4e (patch) | |
| tree | 9b7bf563e49231c6e4a77611a572277a07f1faa0 /kernel/cgroup | |
| parent | be288169712f3dea0bc6b50c00b3ab53d85f1435 (diff) | |
| download | lwn-bb758421416fd8af2267a8e07d53fb8328b07c4e.tar.gz lwn-bb758421416fd8af2267a8e07d53fb8328b07c4e.zip | |
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 <shakeelb@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup')
| -rw-r--r-- | kernel/cgroup/cgroup-v1.c | 7 |
1 files 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; } |