[PATCH 13/28] [PREP 13/14] Miscellaneous preparations in pid namespaces

[Pavel Emelianov]

The most important one is moving exit_task_namespaces behind exit_notify
in do_exit() to make it possible to see the task's pid namespace to
properly notify the parent.

The other important change is redefining child_reaper(). It turned out
that all the places that use it pass current task and thus it is safe
to dereference task->nsproxy pointer.

Signed-off-by: Pavel Emelianov <xemul at openvz.org>

---

 include/linux/pid_namespace.h |    7 ++++++-
 kernel/exit.c                 |    2 +-
 kernel/pid.c                  |    2 ++
 3 files changed, 9 insertions(+), 2 deletions(-)

--- ./include/linux/pid_namespace.h.nsmiscprep	2007-06-15 15:12:25.000000000 +0400
+++ ./include/linux/pid_namespace.h	2007-06-15 15:13:07.000000000 +0400
@@ -29,7 +29,9 @@ extern struct pid_namespace init_pid_ns;
 
 static inline void get_pid_ns(struct pid_namespace *ns)
 {
+#ifdef CONFIG_PID_NS
 	kref_get(&ns->kref);
+#endif
 }
 
 extern struct pid_namespace *copy_pid_ns(int flags, struct pid_namespace *ns);
@@ -37,12 +39,15 @@ extern void free_pid_ns(struct kref *kre
 
 static inline void put_pid_ns(struct pid_namespace *ns)
 {
+#ifdef CONFIG_PID_NS
 	kref_put(&ns->kref, free_pid_ns);
+#endif
 }
 
 static inline struct task_struct *child_reaper(struct task_struct *tsk)
 {
-	return init_pid_ns.child_reaper;
+	BUG_ON(tsk != current);
+	return tsk->nsproxy->pid_ns->child_reaper;
 }
 
 #endif /* _LINUX_PID_NS_H */
--- ./kernel/exit.c.nsmiscprep	2007-06-15 15:03:10.000000000 +0400
+++ ./kernel/exit.c	2007-06-15 15:13:07.000000000 +0400
@@ -955,8 +955,8 @@ fastcall NORET_TYPE void do_exit(long co
 
 	tsk->exit_code = code;
 	proc_exit_connector(tsk);
-	exit_task_namespaces(tsk);
 	exit_notify(tsk);
+	exit_task_namespaces(tsk);
 #ifdef CONFIG_NUMA
 	mpol_free(tsk->mempolicy);
 	tsk->mempolicy = NULL;
--- ./kernel/pid.c.nsmiscprep	2007-06-15 15:11:14.000000000 +0400
+++ ./kernel/pid.c	2007-06-15 15:13:07.000000000 +0400
@@ -82,6 +82,8 @@ struct pid_namespace init_pid_ns = {
 	.child_reaper = &init_task
 };
 
+EXPORT_SYMBOL_GPL(init_pid_ns);
+
 /*
  * Note: disable interrupts while the pidmap_lock is held as an
  * interrupt might come in and do read_lock(&tasklist_lock).