[PATCH 07/26] pidns: Improve the error handling in alloc_pid

[Eric W. Biederman]

Cause any failure to allocate pid 1 to permanently disable pid
allocations for the pid namespace.

Before the pid becomes pid 1 there ns->last_pid and other state
remains unchanged so it is safe to try again...

Signed-off-by: "Eric W. Biederman" <ebied...@xmission.com>
---
 kernel/pid.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/pid.c b/kernel/pid.c
index fd1cde1e4576..f4fb1a84109b 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -321,10 +321,8 @@ struct pid *alloc_pid(struct pid_namespace *ns)
        }
 
        if (unlikely(is_child_reaper(pid))) {
-               if (pid_ns_prepare_proc(ns)) {
-                       disable_pid_allocation(ns);
+               if (pid_ns_prepare_proc(ns))
                        goto out_free;
-               }
        }
 
        get_pid_ns(ns);
@@ -350,6 +348,10 @@ struct pid *alloc_pid(struct pid_namespace *ns)
        put_pid_ns(ns);
 
 out_free:
+       /* Ensure everything stops if allocation of pid 1 failed */
+       if ((i < ns->level) && (pid->numbers[ns->level].nr == 1))
+               disable_pid_allocation(ns);
+
        while (++i <= ns->level)
                free_pidmap(pid->numbers + i);
 
-- 
2.10.1