#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;
struct fs_struct;

/*
* A structure to contain pointers to all per-process
* namespaces - fs (mount), uts, network, sysvipc, etc.
*
* The pid namespace is an exception -- it's accessed using
* task_active_pid_ns. The pid namespace here is the
* namespace that children will use.
*
* '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_for_children;
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 cred *, struct fs_struct *);
int __init nsproxy_cache_init(void);

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);
}

#endif