Sub-domain filtering (1 reply)

I am using the statement is:
if ($ host! = www.mj.com|ci.mj.com) {rewrite ^ / (. *) $ http://www.mj.com/ $ 1 permanent;}
This page contains a redirect loop occurs causing the problem can not access the site, I ask you how to handle this statement to be compatible with multiple subdomains, thank you