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#ifndef _LINUX_NSPROXY_H

#define _LINUX_NSPROXY_H

#include <linux/spinlock.h>

#include <linux/sched.h>

struct mnt_namespace;

struct uts_namespace;

struct ipc_namespace;

struct pid_namespace;

/*

 * A structure to contain pointers to all per-process

 * namespaces - fs (mount), uts, network, sysvipc, etc.

 *

 * 'count' is the number of tasks holding a reference.

 * The count for each namespace, then, will be the number

 * of nsproxies pointing to it, not the number of tasks.

 *

 * The nsproxy is shared by tasks which share all namespaces.

 * As soon as a single namespace is cloned or unshared, the

 * nsproxy is copied.

 */

struct nsproxy {

        atomic_t count;

        struct uts_namespace *uts_ns;

        struct ipc_namespace *ipc_ns;

        struct mnt_namespace *mnt_ns;

        struct pid_namespace *pid_ns;

        struct user_namespace *user_ns;

        struct net           *net_ns;

};

extern struct nsproxy init_nsproxy;

/*

 * the namespaces access rules are:

 *

 *  1. only current task is allowed to change tsk->nsproxy pointer or

 *     any pointer on the nsproxy itself

 *

 *  2. when accessing (i.e. reading) current task's namespaces - no

 *     precautions should be taken - just dereference the pointers

 *

 *  3. the access to other task namespaces is performed like this

 *     rcu_read_lock();

 *     nsproxy = task_nsproxy(tsk);

 *     if (nsproxy != NULL) {

 *             / *

 *               * work with the namespaces here

 *               * e.g. get the reference on one of them

 *               * /

 *     } / *

 *         * NULL task_nsproxy() means that this task is

 *         * almost dead (zombie)

 *         * /

 *     rcu_read_unlock();

 *

 */

static inline struct nsproxy *task_nsproxy(struct task_struct *tsk)

{

        return rcu_dereference(tsk->nsproxy);

}

int copy_namespaces(unsigned long flags, struct task_struct *tsk);

void exit_task_namespaces(struct task_struct *tsk);

void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);

void free_nsproxy(struct nsproxy *ns);

int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,

        struct fs_struct *);

static inline void put_nsproxy(struct nsproxy *ns)

{

        if (atomic_dec_and_test(&ns->count)) {

                free_nsproxy(ns);

        }

}

static inline void get_nsproxy(struct nsproxy *ns)

{

        atomic_inc(&ns->count);

}

#ifdef CONFIG_CGROUP_NS

int ns_cgroup_clone(struct task_struct *tsk);

#else

static inline int ns_cgroup_clone(struct task_struct *tsk) { return 0; }

#endif

#endif