- rcu_read_lock();
- parent = rcu_dereference(p->real_parent);
- ret = task_tgid_nr_ns(parent, pid_ns);
- rcu_read_unlock();
+ if (pid_ns) {
+ rcu_read_lock();
+ parent = rcu_dereference(p->real_parent);
+ ret = task_tgid_nr_ns(parent, pid_ns);
+ rcu_read_unlock();
+ }