Merge branch 'for-2.6.27' of git://linux-nfs.org/~bfields/linux

[pandora-kernel.git] / include / linux / nsproxy.h

diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 189e0dc..0e66b57 100644 (file)
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -23,16 +23,48 @@ struct pid_namespace;
  */
 struct nsproxy {
        atomic_t count;
-       spinlock_t nslock;
        struct uts_namespace *uts_ns;
        struct ipc_namespace *ipc_ns;
        struct mnt_namespace *mnt_ns;
        struct pid_namespace *pid_ns;
+       struct user_namespace *user_ns;
+       struct net           *net_ns;
 };
 extern struct nsproxy init_nsproxy;
 
-int copy_namespaces(int flags, struct task_struct *tsk);
-void get_task_namespaces(struct task_struct *tsk);
+/*
+ * 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 fs_struct *);
@@ -44,14 +76,15 @@ static inline void put_nsproxy(struct nsproxy *ns)
        }
 }
 
-static inline void exit_task_namespaces(struct task_struct *p)
+static inline void get_nsproxy(struct nsproxy *ns)
 {
-       struct nsproxy *ns = p->nsproxy;
-       if (ns) {
-               task_lock(p);
-               p->nsproxy = NULL;
-               task_unlock(p);
-               put_nsproxy(ns);
-       }
+       atomic_inc(&ns->count);
 }
+
+#ifdef CONFIG_CGROUP_NS
+int ns_cgroup_clone(struct task_struct *tsk);
+#else
+static inline int ns_cgroup_clone(struct task_struct *tsk) { return 0; }
+#endif
+
 #endif