[deliverable/linux.git] / include / linux / nsproxy.h

#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 cgroup_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;
	struct cgroup_namespace *cgroup_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.  Current must hold the task_lock
 *     when changing tsk->nsproxy.
 *
 *  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
 *     task_lock(task);
 *     nsproxy = task->nsproxy;
 *     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)
 *         * /
 *     task_unlock(task);
 *
 */

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
Commit	Line	Data
	1	#ifndef _LINUX_NSPROXY_H
	2	#define _LINUX_NSPROXY_H
	3
	4	#include <linux/spinlock.h>
	5	#include <linux/sched.h>
	6
	7	struct mnt_namespace;
	8	struct uts_namespace;
	9	struct ipc_namespace;
	10	struct pid_namespace;
	11	struct cgroup_namespace;
	12	struct fs_struct;
	13
	14	/*
	15	* A structure to contain pointers to all per-process
	16	* namespaces - fs (mount), uts, network, sysvipc, etc.
	17	*
	18	* The pid namespace is an exception -- it's accessed using
	19	* task_active_pid_ns. The pid namespace here is the
	20	* namespace that children will use.
	21	*
	22	* 'count' is the number of tasks holding a reference.
	23	* The count for each namespace, then, will be the number
	24	* of nsproxies pointing to it, not the number of tasks.
	25	*
	26	* The nsproxy is shared by tasks which share all namespaces.
	27	* As soon as a single namespace is cloned or unshared, the
	28	* nsproxy is copied.
	29	*/
	30	struct nsproxy {
	31	atomic_t count;
	32	struct uts_namespace *uts_ns;
	33	struct ipc_namespace *ipc_ns;
	34	struct mnt_namespace *mnt_ns;
	35	struct pid_namespace *pid_ns_for_children;
	36	struct net *net_ns;
	37	struct cgroup_namespace *cgroup_ns;
	38	};
	39	extern struct nsproxy init_nsproxy;
	40
	41	/*
	42	* the namespaces access rules are:
	43	*
	44	* 1. only current task is allowed to change tsk->nsproxy pointer or
	45	* any pointer on the nsproxy itself. Current must hold the task_lock
	46	* when changing tsk->nsproxy.
	47	*
	48	* 2. when accessing (i.e. reading) current task's namespaces - no
	49	* precautions should be taken - just dereference the pointers
	50	*
	51	* 3. the access to other task namespaces is performed like this
	52	* task_lock(task);
	53	* nsproxy = task->nsproxy;
	54	* if (nsproxy != NULL) {
	55	* / *
	56	* * work with the namespaces here
	57	* * e.g. get the reference on one of them
	58	* * /
	59	* } / *
	60	* * NULL task->nsproxy means that this task is
	61	* * almost dead (zombie)
	62	* * /
	63	* task_unlock(task);
	64	*
	65	*/
	66
	67	int copy_namespaces(unsigned long flags, struct task_struct *tsk);
	68	void exit_task_namespaces(struct task_struct *tsk);
	69	void switch_task_namespaces(struct task_struct tsk, struct nsproxy new);
	70	void free_nsproxy(struct nsproxy *ns);
	71	int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
	72	struct cred , struct fs_struct );
	73	int __init nsproxy_cache_init(void);
	74
	75	static inline void put_nsproxy(struct nsproxy *ns)
	76	{
	77	if (atomic_dec_and_test(&ns->count)) {
	78	free_nsproxy(ns);
	79	}
	80	}
	81
	82	static inline void get_nsproxy(struct nsproxy *ns)
	83	{
	84	atomic_inc(&ns->count);
	85	}
	86
	87	#endif