cgroup: split cgroup_base_files[] into cgroup_{dfl|legacy}_base_files[]

Currently cgroup_base_files[] contains the cgroup core interface files
for both legacy and default hierarchies with each file tagged with
CFTYPE_INSANE and CFTYPE_ONLY_ON_DFL.  This is difficult to read.

Let's separate it out to two separate tables, cgroup_dfl_base_files[]
and cgroup_legacy_base_files[], and use the appropriate one in
cgroup_mkdir() depending on the hierarchy type.  This makes tagging
each file unnecessary.

This patch doesn't introduce any behavior changes.

v2: cgroup_dfl_base_files[] was missing the termination entry
    triggering WARN in cgroup_init_cftypes() for 0day kernel testing
    robot.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Jet Chen <jet.chen@intel.com>

1 files changed, 48 insertions, 28 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 28f7d47c1d4a..7e5fee5d6422 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -180,7 +180,8 @@ static u64 css_serial_nr_next = 1;
  */
 static int need_forkexit_callback __read_mostly;
 
-static struct cftype cgroup_base_files[];
+static struct cftype cgroup_dfl_base_files[];
+static struct cftype cgroup_legacy_base_files[];
 
 static void cgroup_put(struct cgroup *cgrp);
 static int rebind_subsystems(struct cgroup_root *dst_root,
@@ -1614,6 +1615,7 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned int ss_mask)
 {
         LIST_HEAD(tmp_links);
         struct cgroup *root_cgrp = &root->cgrp;
+        struct cftype *base_files;
         struct css_set *cset;
         int i, ret;
 
@@ -1651,7 +1653,12 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned int ss_mask)
         }
         root_cgrp->kn = root->kf_root->kn;
 
-        ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true);
+        if (root == &cgrp_dfl_root)
+                base_files = cgroup_dfl_base_files;
+        else
+                base_files = cgroup_legacy_base_files;
+
+        ret = cgroup_addrm_files(root_cgrp, base_files, true);
         if (ret)
                 goto destroy_root;
 
@@ -4095,7 +4102,8 @@ static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
         return 0;
 }
 
-static struct cftype cgroup_base_files[] = {
+/* cgroup core interface files for the default hierarchy */
+static struct cftype cgroup_dfl_base_files[] = {
         {
                 .name = "cgroup.procs",
                 .seq_start = cgroup_pidlist_start,
@@ -4107,46 +4115,52 @@ static struct cftype cgroup_base_files[] = {
                 .mode = S_IRUGO | S_IWUSR,
         },
         {
-                .name = "cgroup.clone_children",
-                .flags = CFTYPE_INSANE,
-                .read_u64 = cgroup_clone_children_read,
-                .write_u64 = cgroup_clone_children_write,
-        },
-        {
-                .name = "cgroup.sane_behavior",
-                .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
-                .seq_show = cgroup_sane_behavior_show,
-        },
-        {
                 .name = "cgroup.controllers",
-                .flags = CFTYPE_ONLY_ON_DFL | CFTYPE_ONLY_ON_ROOT,
+                .flags = CFTYPE_ONLY_ON_ROOT,
                 .seq_show = cgroup_root_controllers_show,
         },
         {
                 .name = "cgroup.controllers",
-                .flags = CFTYPE_ONLY_ON_DFL | CFTYPE_NOT_ON_ROOT,
+                .flags = CFTYPE_NOT_ON_ROOT,
                 .seq_show = cgroup_controllers_show,
         },
         {
                 .name = "cgroup.subtree_control",
-                .flags = CFTYPE_ONLY_ON_DFL,
                 .seq_show = cgroup_subtree_control_show,
                 .write = cgroup_subtree_control_write,
         },
         {
                 .name = "cgroup.populated",
-                .flags = CFTYPE_ONLY_ON_DFL | CFTYPE_NOT_ON_ROOT,
+                .flags = CFTYPE_NOT_ON_ROOT,
                 .seq_show = cgroup_populated_show,
         },
+        { }     /* terminate */
+};
 
-        /*
-         * Historical crazy stuff.  These don't have "cgroup."  prefix and
-         * don't exist if sane_behavior.  If you're depending on these, be
-         * prepared to be burned.
-         */
+/* cgroup core interface files for the legacy hierarchies */
+static struct cftype cgroup_legacy_base_files[] = {
+        {
+                .name = "cgroup.procs",
+                .seq_start = cgroup_pidlist_start,
+                .seq_next = cgroup_pidlist_next,
+                .seq_stop = cgroup_pidlist_stop,
+                .seq_show = cgroup_pidlist_show,
+                .private = CGROUP_FILE_PROCS,
+                .write = cgroup_procs_write,
+                .mode = S_IRUGO | S_IWUSR,
+        },
+        {
+                .name = "cgroup.clone_children",
+                .read_u64 = cgroup_clone_children_read,
+                .write_u64 = cgroup_clone_children_write,
+        },
+        {
+                .name = "cgroup.sane_behavior",
+                .flags = CFTYPE_ONLY_ON_ROOT,
+                .seq_show = cgroup_sane_behavior_show,
+        },
         {
                 .name = "tasks",
-                .flags = CFTYPE_INSANE,         /* use "procs" instead */
                 .seq_start = cgroup_pidlist_start,
                 .seq_next = cgroup_pidlist_next,
                 .seq_stop = cgroup_pidlist_stop,
@@ -4157,13 +4171,12 @@ static struct cftype cgroup_base_files[] = {
         },
         {
                 .name = "notify_on_release",
-                .flags = CFTYPE_INSANE,
                 .read_u64 = cgroup_read_notify_on_release,
                 .write_u64 = cgroup_write_notify_on_release,
         },
         {
                 .name = "release_agent",
-                .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
+                .flags = CFTYPE_ONLY_ON_ROOT,
                 .seq_show = cgroup_release_agent_show,
                 .write = cgroup_release_agent_write,
                 .max_write_len = PATH_MAX - 1,
@@ -4444,6 +4457,7 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
         struct cgroup_root *root;
         struct cgroup_subsys *ss;
         struct kernfs_node *kn;
+        struct cftype *base_files;
         int ssid, ret;
 
         parent = cgroup_kn_lock_live(parent_kn);
@@ -4514,7 +4528,12 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
         if (ret)
                 goto out_destroy;
 
-        ret = cgroup_addrm_files(cgrp, cgroup_base_files, true);
+        if (cgroup_on_dfl(cgrp))
+                base_files = cgroup_dfl_base_files;
+        else
+                base_files = cgroup_legacy_base_files;
+
+        ret = cgroup_addrm_files(cgrp, base_files, true);
         if (ret)
                 goto out_destroy;
 
@@ -4836,7 +4855,8 @@ int __init cgroup_init(void)
         unsigned long key;
         int ssid, err;
 
-        BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files));
+        BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
+        BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
 
         mutex_lock(&cgroup_mutex);