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-rw-r--r--include/linux/nsproxy.h50
1 files changed, 41 insertions, 9 deletions
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
index 033a648709b..0e66b57631f 100644
--- a/include/linux/nsproxy.h
+++ b/include/linux/nsproxy.h
@@ -32,8 +32,39 @@ struct nsproxy {
};
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
+ *
+ * 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 get_task_namespaces(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 *);
@@ -45,14 +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