3 files changed, 12 insertions, 28 deletions

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 4904b1ebd1ff..63097cb243cb 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -355,16 +355,6 @@ struct cgroup {
 	unsigned long flags;		/* "unsigned long" so bitops work */
 
 	/*
-	 * idr allocated in-hierarchy ID.
-	 *
-	 * ID 0 is not used, the ID of the root cgroup is always 1, and a
-	 * new cgroup will be assigned with a smallest available ID.
-	 *
-	 * Allocating/Removing ID must be protected by cgroup_mutex.
-	 */
-	int id;
-
-	/*
 	 * The depth this cgroup is at.  The root is at depth zero and each
 	 * step down the hierarchy increments the level.  This along with
 	 * ancestor_ids[] can determine whether a given cgroup is a
@@ -488,7 +478,7 @@ struct cgroup {
 	struct cgroup_freezer_state freezer;
 
 	/* ids of the ancestors at each level including self */
-	int ancestor_ids[];
+	u64 ancestor_ids[];
 };
 
 /*
@@ -509,7 +499,7 @@ struct cgroup_root {
 	struct cgroup cgrp;
 
 	/* for cgrp->ancestor_ids[0] */
-	int cgrp_ancestor_id_storage;
+	u64 cgrp_ancestor_id_storage;
 
 	/* Number of cgroups in the hierarchy, used only for /proc/cgroups */
 	atomic_t nr_cgrps;
@@ -520,9 +510,6 @@ struct cgroup_root {
 	/* Hierarchy-specific flags */
 	unsigned int flags;
 
-	/* IDs for cgroups in this hierarchy */
-	struct idr cgroup_idr;
-
 	/* The path to use for release notifications. */
 	char release_agent_path[PATH_MAX];
 
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 815fff49d555..d7ddebd0cdec 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -304,6 +304,11 @@ void css_task_iter_end(struct css_task_iter *it);
  * Inline functions.
  */
 
+static inline u64 cgroup_id(struct cgroup *cgrp)
+{
+	return cgrp->kn->id;
+}
+
 /**
  * css_get - obtain a reference on the specified css
  * @css: target css
@@ -565,7 +570,7 @@ static inline bool cgroup_is_descendant(struct cgroup *cgrp,
 {
 	if (cgrp->root != ancestor->root || cgrp->level < ancestor->level)
 		return false;
-	return cgrp->ancestor_ids[ancestor->level] == ancestor->id;
+	return cgrp->ancestor_ids[ancestor->level] == cgroup_id(ancestor);
 }
 
 /**
@@ -687,17 +692,13 @@ static inline void cgroup_kthread_ready(void)
 	current->no_cgroup_migration = 0;
 }
 
-static inline u64 cgroup_get_kernfs_id(struct cgroup *cgrp)
-{
-	return cgrp->kn->id;
-}
-
 void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen);
 #else /* !CONFIG_CGROUPS */
 
 struct cgroup_subsys_state;
 struct cgroup;
 
+static inline u64 cgroup_id(struct cgroup *cgrp) { return 1; }
 static inline void css_get(struct cgroup_subsys_state *css) {}
 static inline void css_put(struct cgroup_subsys_state *css) {}
 static inline int cgroup_attach_task_all(struct task_struct *from,
@@ -717,10 +718,6 @@ static inline int cgroup_init_early(void) { return 0; }
 static inline int cgroup_init(void) { return 0; }
 static inline void cgroup_init_kthreadd(void) {}
 static inline void cgroup_kthread_ready(void) {}
-static inline union u64 cgroup_get_kernfs_id(struct cgroup *cgrp)
-{
-	return 0;
-}
 
 static inline struct cgroup *cgroup_parent(struct cgroup *cgrp)
 {
diff --git a/include/trace/events/cgroup.h b/include/trace/events/cgroup.h
index a566cc521476..7f42a3de59e6 100644
--- a/include/trace/events/cgroup.h
+++ b/include/trace/events/cgroup.h
@@ -66,7 +66,7 @@ DECLARE_EVENT_CLASS(cgroup,
 
 	TP_fast_assign(
 		__entry->root = cgrp->root->hierarchy_id;
-		__entry->id = cgrp->id;
+		__entry->id = cgroup_id(cgrp);
 		__entry->level = cgrp->level;
 		__assign_str(path, path);
 	),
@@ -135,7 +135,7 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
 
 	TP_fast_assign(
 		__entry->dst_root = dst_cgrp->root->hierarchy_id;
-		__entry->dst_id = dst_cgrp->id;
+		__entry->dst_id = cgroup_id(dst_cgrp);
 		__entry->dst_level = dst_cgrp->level;
 		__assign_str(dst_path, path);
 		__entry->pid = task->pid;
@@ -179,7 +179,7 @@ DECLARE_EVENT_CLASS(cgroup_event,
 
 	TP_fast_assign(
 		__entry->root = cgrp->root->hierarchy_id;
-		__entry->id = cgrp->id;
+		__entry->id = cgroup_id(cgrp);
 		__entry->level = cgrp->level;
 		__assign_str(path, path);
 		__entry->val = val;