+#ifdef CONFIG_CGROUP_DEBUG
+static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
+ struct cgroup *cont)
+{
+ struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
+
+ if (!css)
+ return ERR_PTR(-ENOMEM);
+
+ return css;
+}
+
+static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ kfree(cont->subsys[debug_subsys_id]);
+}
+
+static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
+{
+ return atomic_read(&cont->count);
+}
+
+static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft)
+{
+ return cgroup_task_count(cont);
+}
+
+static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
+{
+ return (u64)(unsigned long)current->cgroups;
+}
+
+static u64 current_css_set_refcount_read(struct cgroup *cont,
+ struct cftype *cft)
+{
+ u64 count;
+
+ rcu_read_lock();
+ count = atomic_read(¤t->cgroups->refcount);
+ rcu_read_unlock();
+ return count;
+}
+
+static int current_css_set_cg_links_read(struct cgroup *cont,
+ struct cftype *cft,
+ struct seq_file *seq)
+{
+ struct cg_cgroup_link *link;
+ struct css_set *cg;
+
+ read_lock(&css_set_lock);
+ rcu_read_lock();
+ cg = rcu_dereference(current->cgroups);
+ list_for_each_entry(link, &cg->cg_links, cg_link_list) {
+ struct cgroup *c = link->cgrp;
+ const char *name;
+
+ if (c->dentry)
+ name = c->dentry->d_name.name;
+ else
+ name = "?";
+ seq_printf(seq, "Root %d group %s\n",
+ c->root->hierarchy_id, name);
+ }
+ rcu_read_unlock();
+ read_unlock(&css_set_lock);
+ return 0;
+}
+
+#define MAX_TASKS_SHOWN_PER_CSS 25
+static int cgroup_css_links_read(struct cgroup *cont,
+ struct cftype *cft,
+ struct seq_file *seq)
+{
+ struct cg_cgroup_link *link;
+
+ read_lock(&css_set_lock);
+ list_for_each_entry(link, &cont->css_sets, cgrp_link_list) {
+ struct css_set *cg = link->cg;
+ struct task_struct *task;
+ int count = 0;
+ seq_printf(seq, "css_set %p\n", cg);
+ list_for_each_entry(task, &cg->tasks, cg_list) {
+ if (count++ > MAX_TASKS_SHOWN_PER_CSS) {
+ seq_puts(seq, " ...\n");
+ break;
+ } else {
+ seq_printf(seq, " task %d\n",
+ task_pid_vnr(task));
+ }
+ }
+ }
+ read_unlock(&css_set_lock);
+ return 0;
+}
+
+static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
+{
+ return test_bit(CGRP_RELEASABLE, &cgrp->flags);
+}
+
+static struct cftype debug_files[] = {
+ {
+ .name = "cgroup_refcount",
+ .read_u64 = cgroup_refcount_read,
+ },
+ {
+ .name = "taskcount",
+ .read_u64 = debug_taskcount_read,
+ },
+
+ {
+ .name = "current_css_set",
+ .read_u64 = current_css_set_read,
+ },
+
+ {
+ .name = "current_css_set_refcount",
+ .read_u64 = current_css_set_refcount_read,
+ },
+
+ {
+ .name = "current_css_set_cg_links",
+ .read_seq_string = current_css_set_cg_links_read,
+ },
+
+ {
+ .name = "cgroup_css_links",
+ .read_seq_string = cgroup_css_links_read,
+ },
+
+ {
+ .name = "releasable",
+ .read_u64 = releasable_read,
+ },
+};
+
+static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
+{
+ return cgroup_add_files(cont, ss, debug_files,
+ ARRAY_SIZE(debug_files));
+}
+
+struct cgroup_subsys debug_subsys = {
+ .name = "debug",
+ .create = debug_create,
+ .destroy = debug_destroy,
+ .populate = debug_populate,
+ .subsys_id = debug_subsys_id,
+};
+#endif /* CONFIG_CGROUP_DEBUG */