1 files changed, 61 insertions, 0 deletions

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index d6ed725f36d9..eed92ed624e5 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -5832,3 +5832,64 @@ int cgroup_bpf_update(struct cgroup *cgrp, struct bpf_prog *prog,
         return ret;
 }
 #endif /* CONFIG_CGROUP_BPF */
+
+#ifdef CONFIG_SYSFS
+static ssize_t show_delegatable_files(struct cftype *files, char *buf,
+                                      ssize_t size, const char *prefix)
+{
+        struct cftype *cft;
+        ssize_t ret = 0;
+
+        for (cft = files; cft && cft->name[0] != '\0'; cft++) {
+                if (!(cft->flags & CFTYPE_NS_DELEGATABLE))
+                        continue;
+
+                if (prefix)
+                        ret += snprintf(buf + ret, size - ret, "%s.", prefix);
+
+                ret += snprintf(buf + ret, size - ret, "%s\n", cft->name);
+
+                if (unlikely(ret >= size)) {
+                        WARN_ON(1);
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+static ssize_t delegate_show(struct kobject *kobj, struct kobj_attribute *attr,
+                              char *buf)
+{
+        struct cgroup_subsys *ss;
+        int ssid;
+        ssize_t ret = 0;
+
+        ret = show_delegatable_files(cgroup_base_files, buf, PAGE_SIZE - ret,
+                                     NULL);
+
+        for_each_subsys(ss, ssid)
+                ret += show_delegatable_files(ss->dfl_cftypes, buf + ret,
+                                              PAGE_SIZE - ret,
+                                              cgroup_subsys_name[ssid]);
+
+        return ret;
+}
+static struct kobj_attribute cgroup_delegate_attr = __ATTR_RO(delegate);
+
+static struct attribute *cgroup_sysfs_attrs[] = {
+        &cgroup_delegate_attr.attr,
+        NULL,
+};
+
+static const struct attribute_group cgroup_sysfs_attr_group = {
+        .attrs = cgroup_sysfs_attrs,
+        .name = "cgroup",
+};
+
+static int __init cgroup_sysfs_init(void)
+{
+        return sysfs_create_group(kernel_kobj, &cgroup_sysfs_attr_group);
+}
+subsys_initcall(cgroup_sysfs_init);
+#endif /* CONFIG_SYSFS */