change a post status when users update posts?

Question

Is there an efficient way to change a post status from 'published' to 'draft' when a user of a certain type tries to update their posts. I tried something along these lines

function change_post_status($post_id)
{
  if(current_user_can('rolename'))
  {
    $current_post = get_post( $post_id, 'ARRAY_A' );
    $current_post['post_status'] = 'draft';
    wp_update_post($current_post);
  }
}

add_action('pre_post_update','change_post_status'); 

The code looks good to me but for some reason it doesnt work properly and I think it creates an endless loop(forcing me to restart my SQL server).