include/linux/nsproxy.h

   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
  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  */
  24 struct nsproxy {
  25         atomic_t count;
  26         spinlock_t nslock;
  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 };
  32 extern struct nsproxy init_nsproxy;
  33
  34 struct nsproxy *dup_namespaces(struct nsproxy *orig);
  35 int copy_namespaces(int flags, struct task_struct *tsk);
  36 void get_task_namespaces(struct task_struct *tsk);
  37 void free_nsproxy(struct nsproxy *ns);
  38
  39 static inline void put_nsproxy(struct nsproxy *ns)
  40 {
  41         if (atomic_dec_and_test(&ns->count)) {
  42                 free_nsproxy(ns);
  43         }
  44 }
  45
  46 static inline void exit_task_namespaces(struct task_struct *p)
  47 {
  48         struct nsproxy *ns = p->nsproxy;
  49         if (ns) {
  50                 task_lock(p);
  51                 p->nsproxy = NULL;
  52                 task_unlock(p);
  53                 put_nsproxy(ns);
  54         }
  55 }
  56 #endif