Sub-domain filtering

[ronin]

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

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,242007,242007#msg-242007