Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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;
11
12/*
13 * A structure to contain pointers to all per-process
14 * namespaces - fs (mount), uts, network, sysvipc, etc.
15 *
16 * 'count' is the number of tasks holding a reference.
17 * The count for each namespace, then, will be the number
18 * of nsproxies pointing to it, not the number of tasks.
19 *
20 * The nsproxy is shared by tasks which share all namespaces.
21 * As soon as a single namespace is cloned or unshared, the
22 * nsproxy is copied.
23 */
24struct nsproxy {
25 atomic_t count;
26 struct uts_namespace *uts_ns;
27 struct ipc_namespace *ipc_ns;
28 struct mnt_namespace *mnt_ns;
29 struct pid_namespace *pid_ns;
30 struct net *net_ns;
31};
32extern struct nsproxy init_nsproxy;
33
34/*
35 * the namespaces access rules are:
36 *
37 * 1. only current task is allowed to change tsk->nsproxy pointer or
38 * any pointer on the nsproxy itself
39 *
40 * 2. when accessing (i.e. reading) current task's namespaces - no
41 * precautions should be taken - just dereference the pointers
42 *
43 * 3. the access to other task namespaces is performed like this
44 * rcu_read_lock();
45 * nsproxy = task_nsproxy(tsk);
46 * if (nsproxy != NULL) {
47 * / *
48 * * work with the namespaces here
49 * * e.g. get the reference on one of them
50 * * /
51 * } / *
52 * * NULL task_nsproxy() means that this task is
53 * * almost dead (zombie)
54 * * /
55 * rcu_read_unlock();
56 *
57 */
58
59static inline struct nsproxy *task_nsproxy(struct task_struct *tsk)
60{
61 return rcu_dereference(tsk->nsproxy);
62}
63
64int copy_namespaces(unsigned long flags, struct task_struct *tsk);
65void exit_task_namespaces(struct task_struct *tsk);
66void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new);
67void free_nsproxy(struct nsproxy *ns);
68int unshare_nsproxy_namespaces(unsigned long, struct nsproxy **,
69 struct fs_struct *);
70
71static inline void put_nsproxy(struct nsproxy *ns)
72{
73 if (atomic_dec_and_test(&ns->count)) {
74 free_nsproxy(ns);
75 }
76}
77
78static inline void get_nsproxy(struct nsproxy *ns)
79{
80 atomic_inc(&ns->count);
81}
82
83#ifdef CONFIG_CGROUP_NS
84int ns_cgroup_clone(struct task_struct *tsk, struct pid *pid);
85#else
86static inline int ns_cgroup_clone(struct task_struct *tsk, struct pid *pid)
87{
88 return 0;
89}
90#endif
91
92#endif