[safe/jmp/linux-2.6] / include / linux / cgroup.h

#ifndef _LINUX_CGROUP_H
#define _LINUX_CGROUP_H
/*
 *  cgroup interface
 *
 *  Copyright (C) 2003 BULL SA
 *  Copyright (C) 2004-2006 Silicon Graphics, Inc.
 *
 */

#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>

#ifdef CONFIG_CGROUPS

struct cgroupfs_root;
struct cgroup_subsys;
struct inode;

extern int cgroup_init_early(void);
extern int cgroup_init(void);
extern void cgroup_init_smp(void);
extern void cgroup_lock(void);
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 struct file_operations proc_cgroup_operations;

/* Define the enumeration of all cgroup subsystems */
#define SUBSYS(_x) _x ## _subsys_id,
enum cgroup_subsys_id {
#include <linux/cgroup_subsys.h>
        CGROUP_SUBSYS_COUNT
};
#undef SUBSYS

/* Per-subsystem/per-cgroup state maintained by the system. */
struct cgroup_subsys_state {
        /* The cgroup that this subsystem is attached to. Useful
         * for subsystems that want to know about the cgroup
         * 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() */

        atomic_t refcnt;

        unsigned long flags;
};

/* bits in struct cgroup_subsys_state flags field */
enum {
        CSS_ROOT, /* This CSS is the root of the subsystem */
};

/*
 * Call css_get() to hold a reference on the cgroup;
 *
 */

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_put() should be called to release a reference taken by
 * css_get()
 */

extern void __css_put(struct cgroup_subsys_state *css);
static inline void css_put(struct cgroup_subsys_state *css)
{
        if (!test_bit(CSS_ROOT, &css->flags))
                __css_put(css);
}

/* 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,
};

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 */
        atomic_t count;

        /*
         * We link our 'sibling' struct into our parent's 'children'.
         * Our children link their 'sibling' into our 'children'.
         */
        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 */

        /* 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;
};

/* 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 */
        struct kref ref;

        /*
         * List running through all cgroup groups. Protected by
         * css_set_lock
         */
        struct list_head list;

        /*
         * 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).
         */
        struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];

};

/*
 * 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:
 *
 * 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.
 *
 *
 * When reading/writing to a file:
 *      - 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 */
        char name[MAX_CFTYPE_NAME];
        int private;
        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_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);

        ssize_t (*write) (struct cgroup *cgrp, struct cftype *cft,
                          struct file *file,
                          const char __user *buf, size_t nbytes, loff_t *ppos);

        /*
         * 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 *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);
};

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;
};

/* 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 *cgrp,
                        struct cgroup_subsys *subsys,
                        const struct cftype cft[],
                        int count);

int cgroup_is_removed(const struct cgroup *cgrp);

int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);

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 *cgrp);

/* Control Group subsystem type. See Documentation/cgroups.txt for details */

struct cgroup_subsys {
        struct cgroup_subsys_state *(*create)(struct cgroup_subsys *ss,
                                                  struct cgroup *cgrp);
        void (*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);
        void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
                        struct cgroup *old_cgrp, struct task_struct *tsk);
        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 *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;
#define MAX_CGROUP_TYPE_NAMELEN 32
        const char *name;

        /* Protected by RCU */
        struct cgroupfs_root *root;

        struct list_head sibling;

        void *private;
};

#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;
#include <linux/cgroup_subsys.h>
#undef SUBSYS

static inline struct cgroup_subsys_state *cgroup_subsys_state(
        struct cgroup *cgrp, int 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]);
}

static inline struct cgroup* task_cgroup(struct task_struct *task,
                                               int subsys_id)
{
        return task_subsys_state(task, subsys_id)->cgroup;
}

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 cpuset.
 *    - 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 *);

#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 */

#endif /* _LINUX_CGROUP_H */