cgroup: distinguish the default and legacy hierarchies when handling cftypes

[mirror_ubuntu-artful-kernel.git] / kernel / cgroup.c

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c275aa439a6fb9045e47463b25a556376040344a..374ebdf74f3505babcc8b3a58710fab70d1a6694 100644 (file)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -149,6 +149,12 @@ struct cgroup_root cgrp_dfl_root;
  */
 static bool cgrp_dfl_root_visible;
 
+/*
+ * Set by the boot param of the same name and makes subsystems with NULL
+ * ->dfl_files to use ->legacy_files on the default hierarchy.
+ */
+static bool cgroup_legacy_files_on_dfl;
+
 /* some controllers are not supported in the default hierarchy */
 static const unsigned int cgrp_dfl_root_inhibit_ss_mask = 0
 #ifdef CONFIG_CGROUP_DEBUG
@@ -3085,6 +3091,9 @@ static void cgroup_exit_cftypes(struct cftype *cfts)
                        kfree(cft->kf_ops);
                cft->kf_ops = NULL;
                cft->ss = NULL;
+
+               /* revert flags set by cgroup core while adding @cfts */
+               cft->flags &= ~(CFTYPE_ONLY_ON_DFL | CFTYPE_INSANE);
        }
 }
 
@@ -3195,8 +3204,37 @@ static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
        return ret;
 }
 
+/**
+ * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Similar to cgroup_add_cftypes() but the added files are only used for
+ * the default hierarchy.
+ */
+int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+       struct cftype *cft;
+
+       for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+               cft->flags |= CFTYPE_ONLY_ON_DFL;
+       return cgroup_add_cftypes(ss, cfts);
+}
+
+/**
+ * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Similar to cgroup_add_cftypes() but the added files are only used for
+ * the legacy hierarchies.
+ */
 int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 {
+       struct cftype *cft;
+
+       for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+               cft->flags |= CFTYPE_INSANE;
        return cgroup_add_cftypes(ss, cfts);
 }
 
@@ -4893,9 +4931,19 @@ int __init cgroup_init(void)
                 * disabled flag and cftype registration needs kmalloc,
                 * both of which aren't available during early_init.
                 */
-               if (!ss->disabled) {
-                       cgrp_dfl_root.subsys_mask |= 1 << ss->id;
-                       WARN_ON(cgroup_add_cftypes(ss, ss->legacy_cftypes));
+               if (ss->disabled)
+                       continue;
+
+               cgrp_dfl_root.subsys_mask |= 1 << ss->id;
+
+               if (cgroup_legacy_files_on_dfl && !ss->dfl_cftypes)
+                       ss->dfl_cftypes = ss->legacy_cftypes;
+
+               if (ss->dfl_cftypes == ss->legacy_cftypes) {
+                       WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
+               } else {
+                       WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
+                       WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
                }
        }
 
@@ -5291,6 +5339,14 @@ static int __init cgroup_disable(char *str)
 }
 __setup("cgroup_disable=", cgroup_disable);
 
+static int __init cgroup_set_legacy_files_on_dfl(char *str)
+{
+       printk("cgroup: using legacy files on the default hierarchy\n");
+       cgroup_legacy_files_on_dfl = true;
+       return 0;
+}
+__setup("cgroup__DEVEL__legacy_files_on_dfl", cgroup_set_legacy_files_on_dfl);
+
 /**
  * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
  * @dentry: directory dentry of interest