cgroup: drop cgroup__DEVEL__legacy_files_on_dfl

Now that interfaces for the major three controllers - cpu, memory, io
- are shaping up, there's no reason to have an option to force legacy
files to show up on the unified hierarchy for testing.  Drop it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>

2 files changed, 2 insertions, 34 deletions

diff --git a/Documentation/cgroups/unified-hierarchy.txt b/Documentation/cgroups/unified-hierarchy.txt
index 6932453d37a2..0cd27a4e0055 100644
--- a/Documentation/cgroups/unified-hierarchy.txt
+++ b/Documentation/cgroups/unified-hierarchy.txt
@@ -107,12 +107,6 @@ root of unified hierarchy can be bound to other hierarchies.  This
 allows mixing unified hierarchy with the traditional multiple
 hierarchies in a fully backward compatible way.
 
-For development purposes, the following boot parameter makes all
-controllers to appear on the unified hierarchy whether supported or
-not.
-
- cgroup__DEVEL__legacy_files_on_dfl
-
 A controller can be moved across hierarchies only after the controller
 is no longer referenced in its current hierarchy.  Because per-cgroup
 controller states are destroyed asynchronously and controllers may
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 74daeefa2d30..4f4fc538cb1b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -173,12 +173,6 @@ EXPORT_SYMBOL_GPL(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 unsigned long cgrp_dfl_root_inhibit_ss_mask;
 
@@ -3553,17 +3547,8 @@ int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 {
         struct cftype *cft;
 
-        /*
-         * If legacy_flies_on_dfl, we want to show the legacy files on the
-         * dfl hierarchy but iff the target subsystem hasn't been updated
-         * for the dfl hierarchy yet.
-         */
-        if (!cgroup_legacy_files_on_dfl ||
-            ss->dfl_cftypes != ss->legacy_cftypes) {
-                for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
-                        cft->flags |= __CFTYPE_NOT_ON_DFL;
-        }
-
+        for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+                cft->flags |= __CFTYPE_NOT_ON_DFL;
         return cgroup_add_cftypes(ss, cfts);
 }
 
@@ -5287,9 +5272,6 @@ int __init cgroup_init(void)
 
                 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)
                         cgrp_dfl_root_inhibit_ss_mask |= 1 << ss->id;
 
@@ -5729,14 +5711,6 @@ 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