pidns: make create_pid_namespace() accept parent pidns

create_pid_namespace() creates everything, but caller has to assign parent
pidns by hand, which is unnatural.  At the moment of call new ->level has
to be taken from somewhere and parent pidns is already available.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 2d1001b4858de568515ea1f8fce0540afd4a103a..495d5dea22b2a5e94fcab5bba21e60a71266fa50 100644 (file)
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -67,9 +67,10 @@ err_alloc:
        return NULL;
 }
 
-static struct pid_namespace *create_pid_namespace(unsigned int level)
+static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns)
 {
        struct pid_namespace *ns;
+       unsigned int level = parent_pid_ns->level + 1;
        int i;
 
        ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
@@ -86,6 +87,7 @@ static struct pid_namespace *create_pid_namespace(unsigned int level)
 
        kref_init(&ns->kref);
        ns->level = level;
+       ns->parent = get_pid_ns(parent_pid_ns);
 
        set_bit(0, ns->pidmap[0].page);
        atomic_set(&ns->pidmap[0].nr_free, BITS_PER_PAGE - 1);
@@ -125,9 +127,7 @@ struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old
        if (flags & CLONE_THREAD)
                goto out_put;
 
-       new_ns = create_pid_namespace(old_ns->level + 1);
-       if (!IS_ERR(new_ns))
-               new_ns->parent = get_pid_ns(old_ns);
+       new_ns = create_pid_namespace(old_ns);
 
 out_put:
        put_pid_ns(old_ns);