pidns: call pid_ns_prepare_proc() from create_pid_namespace()

Reorganize proc_get_sb() so it can be called before the struct pid of the
first process is allocated.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 9 insertions, 8 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 17aed4378eda..457fff2e17e0 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1187,12 +1187,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                 pid = alloc_pid(p->nsproxy->pid_ns);
                 if (!pid)
                         goto bad_fork_cleanup_io;
-
-                if (clone_flags & CLONE_NEWPID) {
-                        retval = pid_ns_prepare_proc(p->nsproxy->pid_ns);
-                        if (retval < 0)
-                                goto bad_fork_free_pid;
-                }
         }
 
         p->pid = pid_nr(pid);
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index a5aff94e1f0b..e9c9adc84ca6 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -14,6 +14,7 @@
 #include <linux/err.h>
 #include <linux/acct.h>
 #include <linux/slab.h>
+#include <linux/proc_fs.h>
 
 #define BITS_PER_PAGE           (PAGE_SIZE*8)
 
@@ -72,7 +73,7 @@ static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_p
 {
         struct pid_namespace *ns;
         unsigned int level = parent_pid_ns->level + 1;
-        int i;
+        int i, err = -ENOMEM;
 
         ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
         if (ns == NULL)
@@ -96,14 +97,20 @@ static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_p
         for (i = 1; i < PIDMAP_ENTRIES; i++)
                 atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
 
+        err = pid_ns_prepare_proc(ns);
+        if (err)
+                goto out_put_parent_pid_ns;
+
         return ns;
 
+out_put_parent_pid_ns:
+        put_pid_ns(parent_pid_ns);
 out_free_map:
         kfree(ns->pidmap[0].page);
 out_free:
         kmem_cache_free(pid_ns_cachep, ns);
 out:
-        return ERR_PTR(-ENOMEM);
+        return ERR_PTR(err);
 }
 
 static void destroy_pid_namespace(struct pid_namespace *ns)