[linux-2.6-microblaze.git] / 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/percpu-rwsem.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;
struct seq_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;
};

extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem;

/**
 * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups
 * @tsk: target task
 *
 * Called from threadgroup_change_begin() and allows cgroup operations to
 * synchronize against threadgroup changes using a percpu_rw_semaphore.
 */
static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)
{
        percpu_down_read(&cgroup_threadgroup_rwsem);
}

/**
 * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups
 * @tsk: target task
 *
 * Called from threadgroup_change_end().  Counterpart of
 * cgroup_threadcgroup_change_begin().
 */
static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)
{
        percpu_up_read(&cgroup_threadgroup_rwsem);
}

#else   /* CONFIG_CGROUPS */

#define CGROUP_SUBSYS_COUNT 0

static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}
static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}

#endif  /* CONFIG_CGROUPS */

#endif  /* _LINUX_CGROUP_DEFS_H */