find_lively_task_by_vpid(pid_t vpid)
{
	struct task_struct *task;

	rcu_read_lock();
	if (!vpid)
		task = current;
	else
		task = find_task_by_vpid(vpid);
	if (task)
		get_task_struct(task);
	rcu_read_unlock();

	if (!task)
		return ERR_PTR(-ESRCH);

	return task;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.