1 files changed, 85 insertions, 80 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 8a111dd42d7a..b5223c570eba 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -203,7 +203,15 @@ struct cgroup {
         struct kernfs_node *kn;         /* cgroup kernfs entry */
         struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
 
-        /* the bitmask of subsystems enabled on the child cgroups */
+        /*
+         * The bitmask of subsystems enabled on the child cgroups.
+         * ->subtree_control is the one configured through
+         * "cgroup.subtree_control" while ->child_subsys_mask is the
+         * effective one which may have more subsystems enabled.
+         * Controller knobs are made available iff it's enabled in
+         * ->subtree_control.
+         */
+        unsigned int subtree_control;
         unsigned int child_subsys_mask;
 
         /* Private pointers for each registered subsystem */
@@ -248,73 +256,9 @@ struct cgroup {
 
 /* cgroup_root->flags */
 enum {
-        /*
-         * Unfortunately, cgroup core and various controllers are riddled
-         * with idiosyncrasies and pointless options.  The following flag,
-         * when set, will force sane behavior - some options are forced on,
-         * others are disallowed, and some controllers will change their
-         * hierarchical or other behaviors.
-         *
-         * The set of behaviors affected by this flag are still being
-         * determined and developed and the mount option for this flag is
-         * prefixed with __DEVEL__.  The prefix will be dropped once we
-         * reach the point where all behaviors are compatible with the
-         * planned unified hierarchy, which will automatically turn on this
-         * flag.
-         *
-         * The followings are the behaviors currently affected this flag.
-         *
-         * - Mount options "noprefix", "xattr", "clone_children",
-         *   "release_agent" and "name" are disallowed.
-         *
-         * - When mounting an existing superblock, mount options should
-         *   match.
-         *
-         * - Remount is disallowed.
-         *
-         * - rename(2) is disallowed.
-         *
-         * - "tasks" is removed.  Everything should be at process
-         *   granularity.  Use "cgroup.procs" instead.
-         *
-         * - "cgroup.procs" is not sorted.  pids will be unique unless they
-         *   got recycled inbetween reads.
-         *
-         * - "release_agent" and "notify_on_release" are removed.
-         *   Replacement notification mechanism will be implemented.
-         *
-         * - "cgroup.clone_children" is removed.
-         *
-         * - "cgroup.subtree_populated" is available.  Its value is 0 if
-         *   the cgroup and its descendants contain no task; otherwise, 1.
-         *   The file also generates kernfs notification which can be
-         *   monitored through poll and [di]notify when the value of the
-         *   file changes.
-         *
-         * - If mount is requested with sane_behavior but without any
-         *   subsystem, the default unified hierarchy is mounted.
-         *
-         * - cpuset: tasks will be kept in empty cpusets when hotplug happens
-         *   and take masks of ancestors with non-empty cpus/mems, instead of
-         *   being moved to an ancestor.
-         *
-         * - cpuset: a task can be moved into an empty cpuset, and again it
-         *   takes masks of ancestors.
-         *
-         * - memcg: use_hierarchy is on by default and the cgroup file for
-         *   the flag is not created.
-         *
-         * - blkcg: blk-throttle becomes properly hierarchical.
-         *
-         * - debug: disallowed on the default hierarchy.
-         */
-        CGRP_ROOT_SANE_BEHAVIOR = (1 << 0),
-
+        CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
         CGRP_ROOT_NOPREFIX      = (1 << 1), /* mounted subsystems have no named prefix */
         CGRP_ROOT_XATTR         = (1 << 2), /* supports extended attributes */
-
-        /* mount options live below bit 16 */
-        CGRP_ROOT_OPTION_MASK   = (1 << 16) - 1,
 };
 
 /*
@@ -440,9 +384,11 @@ struct css_set {
 enum {
         CFTYPE_ONLY_ON_ROOT     = (1 << 0),     /* only create on root cgrp */
         CFTYPE_NOT_ON_ROOT      = (1 << 1),     /* don't create on root cgrp */
-        CFTYPE_INSANE           = (1 << 2),     /* don't create if sane_behavior */
         CFTYPE_NO_PREFIX        = (1 << 3),     /* (DON'T USE FOR NEW FILES) no subsys prefix */
-        CFTYPE_ONLY_ON_DFL      = (1 << 4),     /* only on default hierarchy */
+
+        /* internal flags, do not use outside cgroup core proper */
+        __CFTYPE_ONLY_ON_DFL    = (1 << 16),    /* only on default hierarchy */
+        __CFTYPE_NOT_ON_DFL     = (1 << 17),    /* not on default hierarchy */
 };
 
 #define MAX_CFTYPE_NAME         64
@@ -526,20 +472,64 @@ struct cftype {
 extern struct cgroup_root cgrp_dfl_root;
 extern struct css_set init_css_set;
 
+/**
+ * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
+ * @cgrp: the cgroup of interest
+ *
+ * The default hierarchy is the v2 interface of cgroup and this function
+ * can be used to test whether a cgroup is on the default hierarchy for
+ * cases where a subsystem should behave differnetly depending on the
+ * interface version.
+ *
+ * The set of behaviors which change on the default hierarchy are still
+ * being determined and the mount option is prefixed with __DEVEL__.
+ *
+ * List of changed behaviors:
+ *
+ * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
+ *   and "name" are disallowed.
+ *
+ * - When mounting an existing superblock, mount options should match.
+ *
+ * - Remount is disallowed.
+ *
+ * - rename(2) is disallowed.
+ *
+ * - "tasks" is removed.  Everything should be at process granularity.  Use
+ *   "cgroup.procs" instead.
+ *
+ * - "cgroup.procs" is not sorted.  pids will be unique unless they got
+ *   recycled inbetween reads.
+ *
+ * - "release_agent" and "notify_on_release" are removed.  Replacement
+ *   notification mechanism will be implemented.
+ *
+ * - "cgroup.clone_children" is removed.
+ *
+ * - "cgroup.subtree_populated" is available.  Its value is 0 if the cgroup
+ *   and its descendants contain no task; otherwise, 1.  The file also
+ *   generates kernfs notification which can be monitored through poll and
+ *   [di]notify when the value of the file changes.
+ *
+ * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
+ *   take masks of ancestors with non-empty cpus/mems, instead of being
+ *   moved to an ancestor.
+ *
+ * - cpuset: a task can be moved into an empty cpuset, and again it takes
+ *   masks of ancestors.
+ *
+ * - memcg: use_hierarchy is on by default and the cgroup file for the flag
+ *   is not created.
+ *
+ * - blkcg: blk-throttle becomes properly hierarchical.
+ *
+ * - debug: disallowed on the default hierarchy.
+ */
 static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
 {
         return cgrp->root == &cgrp_dfl_root;
 }
 
-/*
- * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details.  This
- * function can be called as long as @cgrp is accessible.
- */
-static inline bool cgroup_sane_behavior(const struct cgroup *cgrp)
-{
-        return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR;
-}
-
 /* no synchronization, the result can only be used as a hint */
 static inline bool cgroup_has_tasks(struct cgroup *cgrp)
 {
@@ -602,7 +592,8 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
 
 char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
 
-int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
+int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
+int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
 int cgroup_rm_cftypes(struct cftype *cfts);
 
 bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);
@@ -634,6 +625,7 @@ struct cgroup_subsys {
         int (*css_online)(struct cgroup_subsys_state *css);
         void (*css_offline)(struct cgroup_subsys_state *css);
         void (*css_free)(struct cgroup_subsys_state *css);
+        void (*css_reset)(struct cgroup_subsys_state *css);
 
         int (*can_attach)(struct cgroup_subsys_state *css,
                           struct cgroup_taskset *tset);
@@ -682,8 +674,21 @@ struct cgroup_subsys {
          */
         struct list_head cfts;
 
-        /* base cftypes, automatically registered with subsys itself */
-        struct cftype *base_cftypes;
+        /*
+         * Base cftypes which are automatically registered.  The two can
+         * point to the same array.
+         */
+        struct cftype *dfl_cftypes;     /* for the default hierarchy */
+        struct cftype *legacy_cftypes;  /* for the legacy hierarchies */
+
+        /*
+         * A subsystem may depend on other subsystems.  When such subsystem
+         * is enabled on a cgroup, the depended-upon subsystems are enabled
+         * together if available.  Subsystems enabled due to dependency are
+         * not visible to userland until explicitly enabled.  The following
+         * specifies the mask of subsystems that this one depends on.
+         */
+        unsigned int depends_on;
 };
 
 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;