pidns: Wait in zap_pid_ns_processes until pid_ns->nr_hashed == 1

Looking at pid_ns->nr_hashed is a bit simpler and it works for
disjoint process trees that an unshare or a join of a pid_namespace
may create.

Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

1 files changed, 0 insertions, 12 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 346616c0092c..d7fe58db4527 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -72,18 +72,6 @@ static void __unhash_process(struct task_struct *p, bool group_dead)
                 list_del_rcu(&p->tasks);
                 list_del_init(&p->sibling);
                 __this_cpu_dec(process_counts);
-                /*
-                 * If we are the last child process in a pid namespace to be
-                 * reaped, notify the reaper sleeping zap_pid_ns_processes().
-                 */
-                if (IS_ENABLED(CONFIG_PID_NS)) {
-                        struct task_struct *parent = p->real_parent;
-
-                        if ((task_active_pid_ns(parent)->child_reaper == parent) &&
-                            list_empty(&parent->children) &&
-                            (parent->flags & PF_EXITING))
-                                wake_up_process(parent);
-                }
         }
         list_del_rcu(&p->thread_group);
 }