[PATCH 22/23] cgroup: Add cgroup namespaces into ns_idr

[Kirill Tkhai]

Now they are exposed in /proc/namespace/ directory.

Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
 include/linux/cgroup.h    |    1 +
 kernel/cgroup/namespace.c |   23 +++++++++++++++++++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 451c2d26a5db..38913d91fa92 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -858,6 +858,7 @@ struct cgroup_namespace {
        struct user_namespace   *user_ns;
        struct ucounts          *ucounts;
        struct css_set          *root_cset;
+       struct rcu_head         rcu;
 };
 
 extern struct cgroup_namespace init_cgroup_ns;
diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c
index f5e8828c109c..64393bbafb2c 100644
--- a/kernel/cgroup/namespace.c
+++ b/kernel/cgroup/namespace.c
@@ -39,11 +39,12 @@ static struct cgroup_namespace *alloc_cgroup_ns(void)
 
 void free_cgroup_ns(struct cgroup_namespace *ns)
 {
+       ns_idr_unregister(&ns->ns);
        put_css_set(ns->root_cset);
        dec_cgroup_namespaces(ns->ucounts);
        put_user_ns(ns->user_ns);
        ns_free_inum(&ns->ns);
-       kfree(ns);
+       kfree_rcu(ns, rcu);
 }
 EXPORT_SYMBOL(free_cgroup_ns);
 
@@ -54,6 +55,7 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
        struct cgroup_namespace *new_ns;
        struct ucounts *ucounts;
        struct css_set *cset;
+       int err;
 
        BUG_ON(!old_ns);
 
@@ -78,16 +80,28 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
 
        new_ns = alloc_cgroup_ns();
        if (IS_ERR(new_ns)) {
-               put_css_set(cset);
-               dec_cgroup_namespaces(ucounts);
-               return new_ns;
+               err = PTR_ERR(new_ns);
+               goto err_put_css_set;
        }
 
        new_ns->user_ns = get_user_ns(user_ns);
        new_ns->ucounts = ucounts;
        new_ns->root_cset = cset;
 
+       err = ns_idr_register(&new_ns->ns);
+       if (err < 0)
+               goto err_put_user_ns;
+
        return new_ns;
+
+err_put_user_ns:
+       put_user_ns(new_ns->user_ns);
+       ns_free_inum(&new_ns->ns);
+       kfree(new_ns);
+err_put_css_set:
+       put_css_set(cset);
+       dec_cgroup_namespaces(ucounts);
+       return ERR_PTR(err);
 }
 
 static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
@@ -152,6 +166,7 @@ const struct proc_ns_operations cgroupns_operations = {
 
 static __init int cgroup_namespaces_init(void)
 {
+       WARN_ON(ns_idr_register(&init_cgroup_ns.ns) < 0);
        return 0;
 }
 subsys_initcall(cgroup_namespaces_init);