[PATCH 5/5] cgroup: remove cgroup->control_kn

Tejun Heo
2014-05-06T12:44:43Z

Now that cgroup_subtree_control_write() has access to the associated
kernfs_open_file and thus the kernfs_node, there's no need to cache it
in cgroup->control_kn on creation. Remove cgroup->control_kn and use
@of->kn directly.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
include/linux/cgroup.h | 1 -
kernel/cgroup.c | 8 +++-----
2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f8cfadb..037fa80 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -179,7 +179,6 @@ struct cgroup {

struct cgroup *parent; /* my parent */
struct kernfs_node *kn; /* cgroup kernfs entry */
- struct kernfs_node *control_kn; /* kn for "cgroup.subtree_control" */
struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */

/*
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 06ad484..eeb4b62 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2578,7 +2578,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
* active_ref protection.
*/
cgroup_get(cgrp);
- kernfs_break_active_protection(cgrp->control_kn);
+ kernfs_break_active_protection(of->kn);

mutex_lock(&cgroup_tree_mutex);

@@ -2695,7 +2695,7 @@ out_unlock:
out_unlock_tree:
mutex_unlock(&cgroup_tree_mutex);
out_unbreak:
- kernfs_unbreak_active_protection(cgrp->control_kn);
+ kernfs_unbreak_active_protection(of->kn);
cgroup_put(cgrp);
return ret ?: nbytes;

@@ -2885,9 +2885,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
return ret;
}

- if (cft->seq_show == cgroup_subtree_control_show)
- cgrp->control_kn = kn;
- else if (cft->seq_show == cgroup_populated_show)
+ if (cft->seq_show == cgroup_populated_show)
cgrp->populated_kn = kn;
return 0;
}
--
1.9.0