[{_id:1,ips:[{addr:"127.0.0.1",count:1}]},{_id:2,ips:[{addr:"127.0.0.1",count:100},{addr:"192.168.0.1",count:50}]}]

db.collection.update({/** include user ID for the filter* _id: 1,*/"ips.addr":"127.0.0.1"},{$inc:{"ips.$.count":1}},{multi:true})