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, 14 insertions, 7 deletions

diff --git a/kernel/pid.c b/kernel/pid.c
index a2b4cbbdd63d..4b17acdb862f 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -73,10 +73,20 @@ struct pid_namespace init_pid_ns = {
 };
 EXPORT_SYMBOL_GPL(init_pid_ns);
 
-int is_global_init(struct task_struct *tsk)
+int is_container_init(struct task_struct *tsk)
 {
-        return tsk == init_pid_ns.child_reaper;
+        int ret = 0;
+        struct pid *pid;
+
+        rcu_read_lock();
+        pid = task_pid(tsk);
+        if (pid != NULL && pid->numbers[pid->level].nr == 1)
+                ret = 1;
+        rcu_read_unlock();
+
+        return ret;
 }
+EXPORT_SYMBOL(is_container_init);
 
 /*
  * Note: disable interrupts while the pidmap_lock is held as an
@@ -192,8 +202,7 @@ fastcall void put_pid(struct pid *pid)
         if ((atomic_read(&pid->count) == 1) ||
              atomic_dec_and_test(&pid->count)) {
                 kmem_cache_free(ns->pid_cachep, pid);
-                if (ns != &init_pid_ns)
-                        put_pid_ns(ns);
+                put_pid_ns(ns);
         }
 }
 EXPORT_SYMBOL_GPL(put_pid);
@@ -244,9 +253,7 @@ struct pid *alloc_pid(struct pid_namespace *ns)
                 tmp = tmp->parent;
         }
 
-        if (ns != &init_pid_ns)
-                get_pid_ns(ns);
-
+        get_pid_ns(ns);
         pid->level = ns->level;
         pid->nr = pid->numbers[0].nr;
         atomic_set(&pid->count, 1);