Canceling execution of parent method

I'm trying to write sort of a short-and-sweet authentication
permissions system. As it is right now, I know how I think I want it
to work but I'm having trouble making it escape the controller action
that was running if validation fails.

Controller in some action:
      if belongs_to_current_user?(@article)
        # User must have permission to edit their own article
        permission_required("article", "edit")
      else
        # User must have permission to edit other's articles
        permission_required("article", "edit-a")
      end

Application controller:
  # Denies access to unauthorized users.
  def permission_required(cont, code)
    unless permission?(cont, code)
      flash[:warning] = "You don't have the permission required for
access to this function"
      redirect_to home_url
      return false
    end
  end

The "return false" I have there, I want it cancel processing from the
action in my controller but it only cancels processing from the rest
of the permission_required method.

I'm at a loss as to how to put code safely after calling
permission_required in my controller, without worrying about it
getting executed anyway after the user is redirected.