1#ifndef _LINUX_NSPROXY_H
 2#define _LINUX_NSPROXY_H
 3
 4#include <linux/spinlock.h>
 5#include <linux/sched.h>
 6
 7struct mnt_namespace;
 8struct uts_namespace;
 9struct ipc_namespace;
10struct pid_namespace;
11struct cgroup_namespace;
12struct 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 */
30struct 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};
39extern 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
 
 
 
 
 
67int copy_namespaces(unsigned long flags, struct task_struct *tsk);
68void exit_task_namespaces(struct task_struct *tsk);
69void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
70void free_nsproxy(struct nsproxy *ns);
71int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
72	struct cred *, struct fs_struct *);
73int __init nsproxy_cache_init(void);
74
75static inline void put_nsproxy(struct nsproxy *ns)
76{
77	if (atomic_dec_and_test(&ns->count)) {
78		free_nsproxy(ns);
79	}
80}
81
82static inline void get_nsproxy(struct nsproxy *ns)
83{
84	atomic_inc(&ns->count);
85}
86
87#endif

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