1 files changed, 49 insertions, 51 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b604c7e0cfc6..e66b9ee5ecc1 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -338,16 +338,24 @@ struct cgrp_cset_link {
         struct list_head        cgrp_link;
 };
 
-/* The default css_set - used by init and its children prior to any
+/*
+ * The default css_set - used by init and its children prior to any
  * hierarchies being mounted. It contains a pointer to the root state
  * for each subsystem. Also used to anchor the list of css_sets. Not
  * reference-counted, to improve performance when child cgroups
  * haven't been created.
  */
+static struct css_set init_css_set = {
+        .refcount               = ATOMIC_INIT(1),
+        .cgrp_links             = LIST_HEAD_INIT(init_css_set.cgrp_links),
+        .tasks                  = LIST_HEAD_INIT(init_css_set.tasks),
+        .mg_tasks               = LIST_HEAD_INIT(init_css_set.mg_tasks),
+        .mg_preload_node        = LIST_HEAD_INIT(init_css_set.mg_preload_node),
+        .mg_node                = LIST_HEAD_INIT(init_css_set.mg_node),
+};
 
-static struct css_set init_css_set;
 static struct cgrp_cset_link init_cgrp_cset_link;
-static int css_set_count;
+static int css_set_count        = 1;    /* 1 for init_css_set */
 
 /*
  * hash table for cgroup groups. This improves the performance to find
@@ -1352,7 +1360,8 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
         cgrp->dummy_css.cgroup = cgrp;
 }
 
-static void init_cgroup_root(struct cgroupfs_root *root)
+static void init_cgroup_root(struct cgroupfs_root *root,
+                             struct cgroup_sb_opts *opts)
 {
         struct cgroup *cgrp = &root->top_cgroup;
 
@@ -1361,20 +1370,6 @@ static void init_cgroup_root(struct cgroupfs_root *root)
         cgrp->root = root;
         init_cgroup_housekeeping(cgrp);
         idr_init(&root->cgroup_idr);
-}
-
-static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
-{
-        struct cgroupfs_root *root;
-
-        if (!opts->subsys_mask && !opts->none)
-                return ERR_PTR(-EINVAL);
-
-        root = kzalloc(sizeof(*root), GFP_KERNEL);
-        if (!root)
-                return ERR_PTR(-ENOMEM);
-
-        init_cgroup_root(root);
 
         root->flags = opts->flags;
         if (opts->release_agent)
@@ -1383,7 +1378,6 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts)
                 strcpy(root->name, opts->name);
         if (opts->cpuset_clone_children)
                 set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags);
-        return root;
 }
 
 static int cgroup_setup_root(struct cgroupfs_root *root, unsigned long ss_mask)
@@ -1548,13 +1542,24 @@ retry:
                 goto out_unlock;
         }
 
-        /* no such thing, create a new one */
-        root = cgroup_root_from_opts(&opts);
-        if (IS_ERR(root)) {
-                ret = PTR_ERR(root);
+        /*
+         * No such thing, create a new one.  name= matching without subsys
+         * specification is allowed for already existing hierarchies but we
+         * can't create new one without subsys specification.
+         */
+        if (!opts.subsys_mask && !opts.none) {
+                ret = -EINVAL;
+                goto out_unlock;
+        }
+
+        root = kzalloc(sizeof(*root), GFP_KERNEL);
+        if (!root) {
+                ret = -ENOMEM;
                 goto out_unlock;
         }
 
+        init_cgroup_root(root, &opts);
+
         ret = cgroup_setup_root(root, opts.subsys_mask);
         if (ret)
                 cgroup_free_root(root);
@@ -4030,26 +4035,13 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
  */
 int __init cgroup_init_early(void)
 {
+        static struct cgroup_sb_opts __initdata opts = { };
         struct cgroup_subsys *ss;
         int i;
 
-        atomic_set(&init_css_set.refcount, 1);
-        INIT_LIST_HEAD(&init_css_set.cgrp_links);
-        INIT_LIST_HEAD(&init_css_set.tasks);
-        INIT_LIST_HEAD(&init_css_set.mg_tasks);
-        INIT_LIST_HEAD(&init_css_set.mg_preload_node);
-        INIT_LIST_HEAD(&init_css_set.mg_node);
-        INIT_HLIST_NODE(&init_css_set.hlist);
-        css_set_count = 1;
-        init_cgroup_root(&cgroup_dummy_root);
-        cgroup_root_count = 1;
+        init_cgroup_root(&cgroup_dummy_root, &opts);
         RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
 
-        init_cgrp_cset_link.cset = &init_css_set;
-        init_cgrp_cset_link.cgrp = cgroup_dummy_top;
-        list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links);
-        list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links);
-
         for_each_subsys(ss, i) {
                 WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
                      "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n",
@@ -4077,22 +4069,10 @@ int __init cgroup_init(void)
 {
         struct cgroup_subsys *ss;
         unsigned long key;
-        int i, err;
+        int ssid, err;
 
         BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
 
-        for_each_subsys(ss, i) {
-                if (!ss->early_init)
-                        cgroup_init_subsys(ss);
-
-                /*
-                 * cftype registration needs kmalloc and can't be done
-                 * during early_init.  Register base cftypes separately.
-                 */
-                if (ss->base_cftypes)
-                        WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes));
-        }
-
         /* allocate id for the dummy hierarchy */
         mutex_lock(&cgroup_mutex);
 
@@ -4106,8 +4086,26 @@ int __init cgroup_init(void)
                         0, 1, GFP_KERNEL);
         BUG_ON(err < 0);
 
+        cgroup_root_count = 1;
+        init_cgrp_cset_link.cset = &init_css_set;
+        init_cgrp_cset_link.cgrp = cgroup_dummy_top;
+        list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links);
+        list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links);
+
         mutex_unlock(&cgroup_mutex);
 
+        for_each_subsys(ss, ssid) {
+                if (!ss->early_init)
+                        cgroup_init_subsys(ss);
+
+                /*
+                 * cftype registration needs kmalloc and can't be done
+                 * during early_init.  Register base cftypes separately.
+                 */
+                if (ss->base_cftypes)
+                        WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes));
+        }
+
         cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
         if (!cgroup_kobj)
                 return -ENOMEM;