cgroup: separate out include/linux/cgroup-defs.h

/*

 * linux/cgroup-defs.h - basic definitions for cgroup

 *

 * This file provides basic type and interface.  Include this file directly

 * only if necessary to avoid cyclic dependencies.

 */

#ifndef _LINUX_CGROUP_DEFS_H

#define _LINUX_CGROUP_DEFS_H

#include <linux/limits.h>

#include <linux/list.h>

#include <linux/idr.h>

#include <linux/wait.h>

#include <linux/mutex.h>

#include <linux/rcupdate.h>

#include <linux/percpu-refcount.h>

#include <linux/workqueue.h>

#ifdef CONFIG_CGROUPS

struct cgroup;

struct cgroup_root;

struct cgroup_subsys;

struct cgroup_taskset;

struct kernfs_node;

struct kernfs_ops;

struct kernfs_open_file;

#define MAX_CGROUP_TYPE_NAMELEN 32

#define MAX_CGROUP_ROOT_NAMELEN 64

#define MAX_CFTYPE_NAME		64

/* define the enumeration of all cgroup subsystems */

#define SUBSYS(_x) _x ## _cgrp_id,

enum cgroup_subsys_id {

#include <linux/cgroup_subsys.h>

	CGROUP_SUBSYS_COUNT,

};

#undef SUBSYS

/* bits in struct cgroup_subsys_state flags field */

enum {

	CSS_NO_REF	= (1 << 0), /* no reference counting for this css */

	CSS_ONLINE	= (1 << 1), /* between ->css_online() and ->css_offline() */

	CSS_RELEASED	= (1 << 2), /* refcnt reached zero, released */

};

/* bits in struct cgroup flags field */

enum {

	/* Control Group requires release notifications to userspace */

	CGRP_NOTIFY_ON_RELEASE,

	/*

	 * Clone the parent's configuration when creating a new child

	 * cpuset cgroup.  For historical reasons, this option can be

	 * specified at mount time and thus is implemented here.

	 */

	CGRP_CPUSET_CLONE_CHILDREN,

};

/* cgroup_root->flags */

enum {

	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 */

};

/* cftype->flags */

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_NO_PREFIX	= (1 << 3),	/* (DON'T USE FOR NEW FILES) no subsys prefix */

	/* 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 */

};

/*

 * Per-subsystem/per-cgroup state maintained by the system.  This is the

 * fundamental structural building block that controllers deal with.

 *

 * Fields marked with "PI:" are public and immutable and may be accessed

 * directly without synchronization.

 */

struct cgroup_subsys_state {

	/* PI: the cgroup that this css is attached to */

	struct cgroup *cgroup;

	/* PI: the cgroup subsystem that this css is attached to */

	struct cgroup_subsys *ss;

	/* reference count - access via css_[try]get() and css_put() */

	struct percpu_ref refcnt;

	/* PI: the parent css */

	struct cgroup_subsys_state *parent;

	/* siblings list anchored at the parent's ->children */

	struct list_head sibling;

	struct list_head children;

	/*

	 * PI: Subsys-unique ID.  0 is unused and root is always 1.  The

	 * matching css can be looked up using css_from_id().

	 */

	int id;

	unsigned int flags;

	/*

	 * Monotonically increasing unique serial number which defines a

	 * uniform order among all csses.  It's guaranteed that all

	 * ->children lists are in the ascending order of ->serial_nr and

	 * used to allow interrupting and resuming iterations.

	 */

	u64 serial_nr;

	/* percpu_ref killing and RCU release */

	struct rcu_head rcu_head;

	struct work_struct destroy_work;

};

/*

 * 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;

	/*

	 * Lists running through all tasks using this cgroup group.

	 * mg_tasks lists tasks which belong to this cset but are in the

	 * process of being migrated out or in.  Protected by

	 * css_set_rwsem, but, during migration, once tasks are moved to

	 * mg_tasks, it can be read safely while holding cgroup_mutex.

	 */

	struct list_head tasks;

	struct list_head mg_tasks;

	/*

	 * List of cgrp_cset_links pointing at cgroups referenced from this

	 * css_set.  Protected by css_set_lock.

	 */

	struct list_head cgrp_links;

	/* the default cgroup associated with this css_set */

	struct cgroup *dfl_cgrp;

	/*

	 * 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).

	 */

	struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];

	/*

	 * List of csets participating in the on-going migration either as

	 * source or destination.  Protected by cgroup_mutex.

	 */

	struct list_head mg_preload_node;

	struct list_head mg_node;

	/*

	 * If this cset is acting as the source of migration the following

	 * two fields are set.  mg_src_cgrp is the source cgroup of the

	 * on-going migration and mg_dst_cset is the destination cset the

	 * target tasks on this cset should be migrated to.  Protected by

	 * cgroup_mutex.

	 */

	struct cgroup *mg_src_cgrp;

	struct css_set *mg_dst_cset;

	/*

	 * On the default hierarhcy, ->subsys[ssid] may point to a css

	 * attached to an ancestor instead of the cgroup this css_set is

	 * associated with.  The following node is anchored at

	 * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to

	 * iterate through all css's attached to a given cgroup.

	 */

	struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];

	/* For RCU-protected deletion */

	struct rcu_head rcu_head;

};

struct cgroup {

	/* self css with NULL ->ss, points back to this cgroup */

	struct cgroup_subsys_state self;

	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;

	/*

	 * If this cgroup contains any tasks, it contributes one to

	 * populated_cnt.  All children with non-zero popuplated_cnt of

	 * their own contribute one.  The count is zero iff there's no task

	 * in this cgroup or its subtree.

	 */

	int populated_cnt;

	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.

	 * ->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 */

	struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];

	struct cgroup_root *root;

	/*

	 * List of cgrp_cset_links pointing at css_sets with tasks in this

	 * cgroup.  Protected by css_set_lock.

	 */

	struct list_head cset_links;

	/*

	 * On the default hierarchy, a css_set for a cgroup with some

	 * susbsys disabled will point to css's which are associated with

	 * the closest ancestor which has the subsys enabled.  The

	 * following lists all css_sets which point to this cgroup's css

	 * for the given subsystem.

	 */

	struct list_head e_csets[CGROUP_SUBSYS_COUNT];

	/*

	 * 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;

	/* used to wait for offlining of csses */

	wait_queue_head_t offline_waitq;

	/* used to schedule release agent */

	struct work_struct release_agent_work;

};

/*

 * A cgroup_root represents the root of a cgroup hierarchy, and may be

 * associated with a kernfs_root to form an active hierarchy.  This is

 * internal to cgroup core.  Don't access directly from controllers.

 */

struct cgroup_root {

	struct kernfs_root *kf_root;

	/* The bitmask of subsystems attached to this hierarchy */

	unsigned int subsys_mask;

	/* Unique id for this hierarchy. */

	int hierarchy_id;

	/* The root cgroup.  Root is destroyed on its release. */

	struct cgroup cgrp;

	/* Number of cgroups in the hierarchy, used only for /proc/cgroups */

	atomic_t nr_cgrps;

	/* A list running through the active hierarchies */

	struct list_head root_list;

	/* 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];

	/* The name for this hierarchy - may be empty */

	char name[MAX_CGROUP_ROOT_NAMELEN];

};

/*

 * struct cftype: handler definitions for cgroup control files

 *

 * When reading/writing to a file:

 *	- the cgroup to use is file->f_path.dentry->d_parent->d_fsdata

 *	- the 'cftype' of the file is file->f_path.dentry->d_fsdata

 */

struct cftype {

	/*

	 * By convention, the name should begin with the name of the

	 * subsystem, followed by a period.  Zero length string indicates

	 * end of cftype array.

	 */

	char name[MAX_CFTYPE_NAME];

	int private;

	/*

	 * If not 0, file mode is set to this value, otherwise it will

	 * be figured out automatically

	 */

	umode_t mode;

	/*

	 * The maximum length of string, excluding trailing nul, that can

	 * be passed to write.  If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.

	 */

	size_t max_write_len;

	/* CFTYPE_* flags */

	unsigned int flags;

	/*

	 * Fields used for internal bookkeeping.  Initialized automatically

	 * during registration.

	 */

	struct cgroup_subsys *ss;	/* NULL for cgroup core files */

	struct list_head node;		/* anchored at ss->cfts */

	struct kernfs_ops *kf_ops;

	/*

	 * read_u64() is a shortcut for the common case of returning a

	 * single integer. Use it in place of read()

	 */

	u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft);

	/*

	 * read_s64() is a signed version of read_u64()

	 */

	s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft);

	/* generic seq_file read interface */

	int (*seq_show)(struct seq_file *sf, void *v);

	/* optional ops, implement all or none */

	void *(*seq_start)(struct seq_file *sf, loff_t *ppos);

	void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);

	void (*seq_stop)(struct seq_file *sf, void *v);

	/*

	 * 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_u64)(struct cgroup_subsys_state *css, struct cftype *cft,

			 u64 val);

	/*

	 * write_s64() is a signed version of write_u64()

	 */

	int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft,

			 s64 val);

	/*

	 * write() is the generic write callback which maps directly to

	 * kernfs write operation and overrides all other operations.

	 * Maximum write size is determined by ->max_write_len.  Use

	 * of_css/cft() to access the associated css and cft.

	 */

	ssize_t (*write)(struct kernfs_open_file *of,

			 char *buf, size_t nbytes, loff_t off);

#ifdef CONFIG_DEBUG_LOCK_ALLOC

	struct lock_class_key	lockdep_key;

#endif

};

/*

 * Control Group subsystem type.

 * See Documentation/cgroups/cgroups.txt for details

 */

struct cgroup_subsys {

	struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);

	int (*css_online)(struct cgroup_subsys_state *css);

	void (*css_offline)(struct cgroup_subsys_state *css);

	void (*css_released)(struct cgroup_subsys_state *css);

	void (*css_free)(struct cgroup_subsys_state *css);

	void (*css_reset)(struct cgroup_subsys_state *css);

	void (*css_e_css_changed)(struct cgroup_subsys_state *css);

	int (*can_attach)(struct cgroup_subsys_state *css,

			  struct cgroup_taskset *tset);

	void (*cancel_attach)(struct cgroup_subsys_state *css,

			      struct cgroup_taskset *tset);

	void (*attach)(struct cgroup_subsys_state *css,

		       struct cgroup_taskset *tset);

	void (*fork)(struct task_struct *task);

	void (*exit)(struct cgroup_subsys_state *css,

		     struct cgroup_subsys_state *old_css,

		     struct task_struct *task);

	void (*bind)(struct cgroup_subsys_state *root_css);

	int disabled;

	int early_init;

	/*

	 * If %false, this subsystem is properly hierarchical -

	 * configuration, resource accounting and restriction on a parent

	 * cgroup cover those of its children.  If %true, hierarchy support

	 * is broken in some ways - some subsystems ignore hierarchy

	 * completely while others are only implemented half-way.

	 *

	 * It's now disallowed to create nested cgroups if the subsystem is

	 * broken and cgroup core will emit a warning message on such

	 * cases.  Eventually, all subsystems will be made properly

	 * hierarchical and this will go away.

	 */

	bool broken_hierarchy;

	bool warned_broken_hierarchy;

	/* the following two fields are initialized automtically during boot */

	int id;

	const char *name;

	/* link to parent, protected by cgroup_lock() */

	struct cgroup_root *root;

	/* idr for css->id */

	struct idr css_idr;

	/*

	 * List of cftypes.  Each entry is the first entry of an array

	 * terminated by zero length name.

	 */

	struct list_head cfts;

	/*

	 * 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;

};

#endif	/* CONFIG_CGROUPS */

#endif	/* _LINUX_CGROUP_DEFS_H */