X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=include%2Flinux%2Fcgroup.h;h=8f78073d7caaa278017232112f0d3da05aa0d4c0;hb=3374cd1abd478f767aaedf2c21d109596ff0fe72;hp=a9553568118fed713c32bf3256fdecafd0d8b603;hpb=a424316ca154317367c7ddf89997d1c80e4a8051;p=safe%2Fjmp%2Flinux-2.6

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index a955356..8f78073 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -9,77 +9,192 @@
  */
 
 #include <linux/sched.h>
-#include <linux/kref.h>
 #include <linux/cpumask.h>
 #include <linux/nodemask.h>
 #include <linux/rcupdate.h>
+#include <linux/cgroupstats.h>
+#include <linux/prio_heap.h>
+#include <linux/rwsem.h>
+#include <linux/idr.h>
 
 #ifdef CONFIG_CGROUPS
 
 struct cgroupfs_root;
 struct cgroup_subsys;
 struct inode;
+struct cgroup;
+struct css_id;
 
 extern int cgroup_init_early(void);
 extern int cgroup_init(void);
-extern void cgroup_init_smp(void);
 extern void cgroup_lock(void);
+extern int cgroup_lock_is_held(void);
+extern bool cgroup_lock_live_group(struct cgroup *cgrp);
 extern void cgroup_unlock(void);
 extern void cgroup_fork(struct task_struct *p);
 extern void cgroup_fork_callbacks(struct task_struct *p);
+extern void cgroup_post_fork(struct task_struct *p);
 extern void cgroup_exit(struct task_struct *p, int run_callbacks);
+extern int cgroupstats_build(struct cgroupstats *stats,
+				struct dentry *dentry);
+extern int cgroup_load_subsys(struct cgroup_subsys *ss);
+extern void cgroup_unload_subsys(struct cgroup_subsys *ss);
 
-extern struct file_operations proc_cgroup_operations;
+extern const struct file_operations proc_cgroup_operations;
+
+/* Define the enumeration of all builtin cgroup subsystems */
+#define SUBSYS(_x) _x ## _subsys_id,
+enum cgroup_subsys_id {
+#include <linux/cgroup_subsys.h>
+	CGROUP_BUILTIN_SUBSYS_COUNT
+};
+#undef SUBSYS
+/*
+ * This define indicates the maximum number of subsystems that can be loaded
+ * at once. We limit to this many since cgroupfs_root has subsys_bits to keep
+ * track of all of them.
+ */
+#define CGROUP_SUBSYS_COUNT (BITS_PER_BYTE*sizeof(unsigned long))
 
 /* Per-subsystem/per-cgroup state maintained by the system. */
 struct cgroup_subsys_state {
-	/* The cgroup that this subsystem is attached to. Useful
+	/*
+	 * The cgroup that this subsystem is attached to. Useful
 	 * for subsystems that want to know about the cgroup
-	 * hierarchy structure */
+	 * hierarchy structure
+	 */
 	struct cgroup *cgroup;
 
-	/* State maintained by the cgroup system to allow
-	 * subsystems to be "busy". Should be accessed via css_get()
-	 * and css_put() */
+	/*
+	 * State maintained by the cgroup system to allow subsystems
+	 * to be "busy". Should be accessed via css_get(),
+	 * css_tryget() and and css_put().
+	 */
 
 	atomic_t refcnt;
 
 	unsigned long flags;
+	/* ID for this css, if possible */
+	struct css_id *id;
 };
 
 /* bits in struct cgroup_subsys_state flags field */
 enum {
 	CSS_ROOT, /* This CSS is the root of the subsystem */
+	CSS_REMOVED, /* This CSS is dead */
 };
 
+/* Caller must verify that the css is not for root cgroup */
+static inline void __css_get(struct cgroup_subsys_state *css, int count)
+{
+	atomic_add(count, &css->refcnt);
+}
+
 /*
- * Call css_get() to hold a reference on the cgroup;
- *
+ * Call css_get() to hold a reference on the css; it can be used
+ * for a reference obtained via:
+ * - an existing ref-counted reference to the css
+ * - task->cgroups for a locked task
  */
 
 static inline void css_get(struct cgroup_subsys_state *css)
 {
 	/* We don't need to reference count the root state */
 	if (!test_bit(CSS_ROOT, &css->flags))
-		atomic_inc(&css->refcnt);
+		__css_get(css, 1);
+}
+
+static inline bool css_is_removed(struct cgroup_subsys_state *css)
+{
+	return test_bit(CSS_REMOVED, &css->flags);
+}
+
+/*
+ * Call css_tryget() to take a reference on a css if your existing
+ * (known-valid) reference isn't already ref-counted. Returns false if
+ * the css has been destroyed.
+ */
+
+static inline bool css_tryget(struct cgroup_subsys_state *css)
+{
+	if (test_bit(CSS_ROOT, &css->flags))
+		return true;
+	while (!atomic_inc_not_zero(&css->refcnt)) {
+		if (test_bit(CSS_REMOVED, &css->flags))
+			return false;
+		cpu_relax();
+	}
+	return true;
 }
+
 /*
  * css_put() should be called to release a reference taken by
- * css_get()
+ * css_get() or css_tryget()
  */
 
+extern void __css_put(struct cgroup_subsys_state *css, int count);
 static inline void css_put(struct cgroup_subsys_state *css)
 {
 	if (!test_bit(CSS_ROOT, &css->flags))
-		atomic_dec(&css->refcnt);
+		__css_put(css, 1);
 }
 
+/* bits in struct cgroup flags field */
+enum {
+	/* Control Group is dead */
+	CGRP_REMOVED,
+	/*
+	 * Control Group has previously had a child cgroup or a task,
+	 * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set)
+	 */
+	CGRP_RELEASABLE,
+	/* Control Group requires release notifications to userspace */
+	CGRP_NOTIFY_ON_RELEASE,
+	/*
+	 * A thread in rmdir() is wating for this cgroup.
+	 */
+	CGRP_WAIT_ON_RMDIR,
+};
+
+/* which pidlist file are we talking about? */
+enum cgroup_filetype {
+	CGROUP_FILE_PROCS,
+	CGROUP_FILE_TASKS,
+};
+
+/*
+ * A pidlist is a list of pids that virtually represents the contents of one
+ * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
+ * a pair (one each for procs, tasks) for each pid namespace that's relevant
+ * to the cgroup.
+ */
+struct cgroup_pidlist {
+	/*
+	 * used to find which pidlist is wanted. doesn't change as long as
+	 * this particular list stays in the list.
+	 */
+	struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
+	/* array of xids */
+	pid_t *list;
+	/* how many elements the above list has */
+	int length;
+	/* how many files are using the current array */
+	int use_count;
+	/* each of these stored in a list by its cgroup */
+	struct list_head links;
+	/* pointer to the cgroup we belong to, for list removal purposes */
+	struct cgroup *owner;
+	/* protects the other fields */
+	struct rw_semaphore mutex;
+};
+
 struct cgroup {
 	unsigned long flags;		/* "unsigned long" so bitops work */
 
-	/* count users of this cgroup. >0 means busy, but doesn't
-	 * necessarily indicate the number of tasks in the
-	 * cgroup */
+	/*
+	 * count users of this cgroup. >0 means busy, but doesn't
+	 * necessarily indicate the number of tasks in the cgroup
+	 */
 	atomic_t count;
 
 	/*
@@ -89,115 +204,315 @@ struct cgroup {
 	struct list_head sibling;	/* my parent's children */
 	struct list_head children;	/* my children */
 
-	struct cgroup *parent;	/* my parent */
-	struct dentry *dentry;	  	/* cgroup fs entry */
+	struct cgroup *parent;		/* my parent */
+	struct dentry *dentry;	  	/* cgroup fs entry, RCU protected */
 
 	/* Private pointers for each registered subsystem */
 	struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
 
 	struct cgroupfs_root *root;
 	struct cgroup *top_cgroup;
+
+	/*
+	 * List of cg_cgroup_links pointing at css_sets with
+	 * tasks in this cgroup. Protected by css_set_lock
+	 */
+	struct list_head css_sets;
+
+	/*
+	 * Linked list running through all cgroups that can
+	 * potentially be reaped by the release agent. Protected by
+	 * release_list_lock
+	 */
+	struct list_head release_list;
+
+	/*
+	 * list of pidlists, up to two for each namespace (one for procs, one
+	 * for tasks); created on demand.
+	 */
+	struct list_head pidlists;
+	struct mutex pidlist_mutex;
+
+	/* For RCU-protected deletion */
+	struct rcu_head rcu_head;
+
+	/* List of events which userspace want to recieve */
+	struct list_head event_list;
+	spinlock_t event_list_lock;
 };
 
-/* struct cftype:
- *
- * The files in the cgroup filesystem mostly have a very simple read/write
- * handling, some common function will take care of it. Nevertheless some cases
- * (read tasks) are special and therefore I define this structure for every
- * kind of file.
- *
+/*
+ * A css_set is a structure holding pointers to a set of
+ * cgroup_subsys_state objects. This saves space in the task struct
+ * object and speeds up fork()/exit(), since a single inc/dec and a
+ * list_add()/del() can bump the reference count on the entire cgroup
+ * set for a task.
+ */
+
+struct css_set {
+
+	/* Reference count */
+	atomic_t refcount;
+
+	/*
+	 * List running through all cgroup groups in the same hash
+	 * slot. Protected by css_set_lock
+	 */
+	struct hlist_node hlist;
+
+	/*
+	 * List running through all tasks using this cgroup
+	 * group. Protected by css_set_lock
+	 */
+	struct list_head tasks;
+
+	/*
+	 * List of cg_cgroup_link objects on link chains from
+	 * cgroups referenced from this css_set. Protected by
+	 * css_set_lock
+	 */
+	struct list_head cg_links;
+
+	/*
+	 * Set of subsystem states, one for each subsystem. This array
+	 * is immutable after creation apart from the init_css_set
+	 * during subsystem registration (at boot time) and modular subsystem
+	 * loading/unloading.
+	 */
+	struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+
+	/* For RCU-protected deletion */
+	struct rcu_head rcu_head;
+};
+
+/*
+ * cgroup_map_cb is an abstract callback API for reporting map-valued
+ * control files
+ */
+
+struct cgroup_map_cb {
+	int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value);
+	void *state;
+};
+
+/*
+ * struct cftype: handler definitions for cgroup control files
  *
  * When reading/writing to a file:
- *	- the cgroup to use in file->f_dentry->d_parent->d_fsdata
+ *	- the cgroup to use is file->f_dentry->d_parent->d_fsdata
  *	- the 'cftype' of the file is file->f_dentry->d_fsdata
  */
 
 #define MAX_CFTYPE_NAME 64
 struct cftype {
-	/* By convention, the name should begin with the name of the
-	 * subsystem, followed by a period */
+	/*
+	 * By convention, the name should begin with the name of the
+	 * subsystem, followed by a period
+	 */
 	char name[MAX_CFTYPE_NAME];
 	int private;
-	int (*open) (struct inode *inode, struct file *file);
-	ssize_t (*read) (struct cgroup *cont, struct cftype *cft,
-			 struct file *file,
-			 char __user *buf, size_t nbytes, loff_t *ppos);
 	/*
-	 * read_uint() is a shortcut for the common case of returning a
+	 * If not 0, file mode is set to this value, otherwise it will
+	 * be figured out automatically
+	 */
+	mode_t mode;
+
+	/*
+	 * If non-zero, defines the maximum length of string that can
+	 * be passed to write_string; defaults to 64
+	 */
+	size_t max_write_len;
+
+	int (*open)(struct inode *inode, struct file *file);
+	ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
+			struct file *file,
+			char __user *buf, size_t nbytes, loff_t *ppos);
+	/*
+	 * read_u64() is a shortcut for the common case of returning a
 	 * single integer. Use it in place of read()
 	 */
-	u64 (*read_uint) (struct cgroup *cont, struct cftype *cft);
-	ssize_t (*write) (struct cgroup *cont, struct cftype *cft,
-			  struct file *file,
-			  const char __user *buf, size_t nbytes, loff_t *ppos);
+	u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft);
+	/*
+	 * read_s64() is a signed version of read_u64()
+	 */
+	s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft);
+	/*
+	 * read_map() is used for defining a map of key/value
+	 * pairs. It should call cb->fill(cb, key, value) for each
+	 * entry. The key/value pairs (and their ordering) should not
+	 * change between reboots.
+	 */
+	int (*read_map)(struct cgroup *cont, struct cftype *cft,
+			struct cgroup_map_cb *cb);
+	/*
+	 * read_seq_string() is used for outputting a simple sequence
+	 * using seqfile.
+	 */
+	int (*read_seq_string)(struct cgroup *cont, struct cftype *cft,
+			       struct seq_file *m);
+
+	ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft,
+			 struct file *file,
+			 const char __user *buf, size_t nbytes, loff_t *ppos);
 
 	/*
-	 * write_uint() is a shortcut for the common case of accepting
+	 * write_u64() is a shortcut for the common case of accepting
 	 * a single integer (as parsed by simple_strtoull) from
 	 * userspace. Use in place of write(); return 0 or error.
 	 */
-	int (*write_uint) (struct cgroup *cont, struct cftype *cft, u64 val);
+	int (*write_u64)(struct cgroup *cgrp, struct cftype *cft, u64 val);
+	/*
+	 * write_s64() is a signed version of write_u64()
+	 */
+	int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val);
 
-	int (*release) (struct inode *inode, struct file *file);
+	/*
+	 * write_string() is passed a nul-terminated kernelspace
+	 * buffer of maximum length determined by max_write_len.
+	 * Returns 0 or -ve error code.
+	 */
+	int (*write_string)(struct cgroup *cgrp, struct cftype *cft,
+			    const char *buffer);
+	/*
+	 * trigger() callback can be used to get some kick from the
+	 * userspace, when the actual string written is not important
+	 * at all. The private field can be used to determine the
+	 * kick type for multiplexing.
+	 */
+	int (*trigger)(struct cgroup *cgrp, unsigned int event);
+
+	int (*release)(struct inode *inode, struct file *file);
+
+	/*
+	 * register_event() callback will be used to add new userspace
+	 * waiter for changes related to the cftype. Implement it if
+	 * you want to provide this functionality. Use eventfd_signal()
+	 * on eventfd to send notification to userspace.
+	 */
+	int (*register_event)(struct cgroup *cgrp, struct cftype *cft,
+			struct eventfd_ctx *eventfd, const char *args);
+	/*
+	 * unregister_event() callback will be called when userspace
+	 * closes the eventfd or on cgroup removing.
+	 * This callback must be implemented, if you want provide
+	 * notification functionality.
+	 */
+	int (*unregister_event)(struct cgroup *cgrp, struct cftype *cft,
+			struct eventfd_ctx *eventfd);
 };
 
-/* Add a new file to the given cgroup directory. Should only be
- * called by subsystems from within a populate() method */
-int cgroup_add_file(struct cgroup *cont, struct cgroup_subsys *subsys,
+struct cgroup_scanner {
+	struct cgroup *cg;
+	int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
+	void (*process_task)(struct task_struct *p,
+			struct cgroup_scanner *scan);
+	struct ptr_heap *heap;
+	void *data;
+};
+
+/*
+ * Add a new file to the given cgroup directory. Should only be
+ * called by subsystems from within a populate() method
+ */
+int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
 		       const struct cftype *cft);
 
-/* Add a set of new files to the given cgroup directory. Should
- * only be called by subsystems from within a populate() method */
-int cgroup_add_files(struct cgroup *cont,
+/*
+ * Add a set of new files to the given cgroup directory. Should
+ * only be called by subsystems from within a populate() method
+ */
+int cgroup_add_files(struct cgroup *cgrp,
 			struct cgroup_subsys *subsys,
 			const struct cftype cft[],
 			int count);
 
-int cgroup_is_removed(const struct cgroup *cont);
+int cgroup_is_removed(const struct cgroup *cgrp);
 
-int cgroup_path(const struct cgroup *cont, char *buf, int buflen);
+int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
 
-int __cgroup_task_count(const struct cgroup *cont);
-static inline int cgroup_task_count(const struct cgroup *cont)
-{
-	int task_count;
-	rcu_read_lock();
-	task_count = __cgroup_task_count(cont);
-	rcu_read_unlock();
-	return task_count;
-}
+int cgroup_task_count(const struct cgroup *cgrp);
 
-/* Return true if the cgroup is a descendant of the current cgroup */
-int cgroup_is_descendant(const struct cgroup *cont);
+/* Return true if cgrp is a descendant of the task's cgroup */
+int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task);
 
-/* Control Group subsystem type. See Documentation/cgroups.txt for details */
+/*
+ * When the subsys has to access css and may add permanent refcnt to css,
+ * it should take care of racy conditions with rmdir(). Following set of
+ * functions, is for stop/restart rmdir if necessary.
+ * Because these will call css_get/put, "css" should be alive css.
+ *
+ *  cgroup_exclude_rmdir();
+ *  ...do some jobs which may access arbitrary empty cgroup
+ *  cgroup_release_and_wakeup_rmdir();
+ *
+ *  When someone removes a cgroup while cgroup_exclude_rmdir() holds it,
+ *  it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up.
+ */
+
+void cgroup_exclude_rmdir(struct cgroup_subsys_state *css);
+void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css);
+
+/*
+ * Control Group subsystem type.
+ * See Documentation/cgroups/cgroups.txt for details
+ */
 
 struct cgroup_subsys {
 	struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss,
-						  struct cgroup *cont);
-	void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cont);
-	int (*can_attach)(struct cgroup_subsys *ss,
-			  struct cgroup *cont, struct task_struct *tsk);
-	void (*attach)(struct cgroup_subsys *ss, struct cgroup *cont,
-			struct cgroup *old_cont, struct task_struct *tsk);
+						  struct cgroup *cgrp);
+	int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
+	void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
+	int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
+			  struct task_struct *tsk, bool threadgroup);
+	void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
+			  struct task_struct *tsk, bool threadgroup);
+	void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
+			struct cgroup *old_cgrp, struct task_struct *tsk,
+			bool threadgroup);
 	void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
 	void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);
 	int (*populate)(struct cgroup_subsys *ss,
-			struct cgroup *cont);
-	void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cont);
+			struct cgroup *cgrp);
+	void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
 	void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
+
 	int subsys_id;
 	int active;
+	int disabled;
 	int early_init;
+	/*
+	 * True if this subsys uses ID. ID is not available before cgroup_init()
+	 * (not available in early_init time.)
+	 */
+	bool use_id;
 #define MAX_CGROUP_TYPE_NAMELEN 32
 	const char *name;
 
-	/* Protected by RCU */
-	struct cgroupfs_root *root;
+	/*
+	 * Protects sibling/children links of cgroups in this
+	 * hierarchy, plus protects which hierarchy (or none) the
+	 * subsystem is a part of (i.e. root/sibling).  To avoid
+	 * potential deadlocks, the following operations should not be
+	 * undertaken while holding any hierarchy_mutex:
+	 *
+	 * - allocating memory
+	 * - initiating hotplug events
+	 */
+	struct mutex hierarchy_mutex;
+	struct lock_class_key subsys_key;
 
+	/*
+	 * Link to parent, and list entry in parent's children.
+	 * Protected by this->hierarchy_mutex and cgroup_lock()
+	 */
+	struct cgroupfs_root *root;
 	struct list_head sibling;
+	/* used when use_id == true */
+	struct idr idr;
+	spinlock_t id_lock;
 
-	void *private;
+	/* should be defined only by modular subsystems */
+	struct module *module;
 };
 
 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
@@ -205,15 +520,18 @@ struct cgroup_subsys {
 #undef SUBSYS
 
 static inline struct cgroup_subsys_state *cgroup_subsys_state(
-	struct cgroup *cont, int subsys_id)
+	struct cgroup *cgrp, int subsys_id)
 {
-	return cont->subsys[subsys_id];
+	return cgrp->subsys[subsys_id];
 }
 
 static inline struct cgroup_subsys_state *task_subsys_state(
 	struct task_struct *task, int subsys_id)
 {
-	return rcu_dereference(task->cgroups.subsys[subsys_id]);
+	return rcu_dereference_check(task->cgroups->subsys[subsys_id],
+				     rcu_read_lock_held() ||
+				     lockdep_is_held(&task->alloc_lock) ||
+				     cgroup_lock_is_held());
 }
 
 static inline struct cgroup* task_cgroup(struct task_struct *task,
@@ -222,21 +540,91 @@ static inline struct cgroup* task_cgroup(struct task_struct *task,
 	return task_subsys_state(task, subsys_id)->cgroup;
 }
 
-int cgroup_path(const struct cgroup *cont, char *buf, int buflen);
+int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss,
+							char *nodename);
 
-int cgroup_clone(struct task_struct *tsk, struct cgroup_subsys *ss);
+/* A cgroup_iter should be treated as an opaque object */
+struct cgroup_iter {
+	struct list_head *cg_link;
+	struct list_head *task;
+};
+
+/*
+ * To iterate across the tasks in a cgroup:
+ *
+ * 1) call cgroup_iter_start to intialize an iterator
+ *
+ * 2) call cgroup_iter_next() to retrieve member tasks until it
+ *    returns NULL or until you want to end the iteration
+ *
+ * 3) call cgroup_iter_end() to destroy the iterator.
+ *
+ * Or, call cgroup_scan_tasks() to iterate through every task in a
+ * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling
+ * the test_task() callback, but not while calling the process_task()
+ * callback.
+ */
+void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it);
+struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
+					struct cgroup_iter *it);
+void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
+int cgroup_scan_tasks(struct cgroup_scanner *scan);
+int cgroup_attach_task(struct cgroup *, struct task_struct *);
+
+/*
+ * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works
+ * if cgroup_subsys.use_id == true. It can be used for looking up and scanning.
+ * CSS ID is assigned at cgroup allocation (create) automatically
+ * and removed when subsys calls free_css_id() function. This is because
+ * the lifetime of cgroup_subsys_state is subsys's matter.
+ *
+ * Looking up and scanning function should be called under rcu_read_lock().
+ * Taking cgroup_mutex()/hierarchy_mutex() is not necessary for following calls.
+ * But the css returned by this routine can be "not populated yet" or "being
+ * destroyed". The caller should check css and cgroup's status.
+ */
+
+/*
+ * Typically Called at ->destroy(), or somewhere the subsys frees
+ * cgroup_subsys_state.
+ */
+void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css);
+
+/* Find a cgroup_subsys_state which has given ID */
+
+struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id);
+
+/*
+ * Get a cgroup whose id is greater than or equal to id under tree of root.
+ * Returning a cgroup_subsys_state or NULL.
+ */
+struct cgroup_subsys_state *css_get_next(struct cgroup_subsys *ss, int id,
+		struct cgroup_subsys_state *root, int *foundid);
+
+/* Returns true if root is ancestor of cg */
+bool css_is_ancestor(struct cgroup_subsys_state *cg,
+		     const struct cgroup_subsys_state *root);
+
+/* Get id and depth of css */
+unsigned short css_id(struct cgroup_subsys_state *css);
+unsigned short css_depth(struct cgroup_subsys_state *css);
 
 #else /* !CONFIG_CGROUPS */
 
 static inline int cgroup_init_early(void) { return 0; }
 static inline int cgroup_init(void) { return 0; }
-static inline void cgroup_init_smp(void) {}
 static inline void cgroup_fork(struct task_struct *p) {}
 static inline void cgroup_fork_callbacks(struct task_struct *p) {}
+static inline void cgroup_post_fork(struct task_struct *p) {}
 static inline void cgroup_exit(struct task_struct *p, int callbacks) {}
 
 static inline void cgroup_lock(void) {}
 static inline void cgroup_unlock(void) {}
+static inline int cgroupstats_build(struct cgroupstats *stats,
+					struct dentry *dentry)
+{
+	return -EINVAL;
+}
 
 #endif /* !CONFIG_CGROUPS */