pid namespaces: miscellaneous preparations for pid namespaces

* remove pid.h from pid_namespaces.h;
* rework is_(cgroup|global)_init;
* optimize (get|put)_pid_ns for init_pid_ns;
* declare task_child_reaper to return actual reaper.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 416d4e4ce94e..0135c76c76c6 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -4,7 +4,6 @@
 #include <linux/sched.h>
 #include <linux/mm.h>
 #include <linux/threads.h>
-#include <linux/pid.h>
 #include <linux/nsproxy.h>
 #include <linux/kref.h>
 
@@ -32,7 +31,8 @@ extern struct pid_namespace init_pid_ns;
 
 static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
 {
-        kref_get(&ns->kref);
+        if (ns != &init_pid_ns)
+                kref_get(&ns->kref);
         return ns;
 }
 
@@ -41,7 +41,8 @@ extern void free_pid_ns(struct kref *kref);
 
 static inline void put_pid_ns(struct pid_namespace *ns)
 {
-        kref_put(&ns->kref, free_pid_ns);
+        if (ns != &init_pid_ns)
+                kref_put(&ns->kref, free_pid_ns);
 }
 
 static inline struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
@@ -51,7 +52,8 @@ static inline struct pid_namespace *task_active_pid_ns(struct task_struct *tsk)
 
 static inline struct task_struct *task_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 */