Multi master single slave replication mysql I have a scenario in which there are two masters master 1 and master 2 and i want to add slave to master 2 , so when i update in master 1 it will replicate for master 2 so how do i get slave of master 2 to update form it ? What is the  parameter to be set for it?
I am assuming you already have Master1 and Master2 acting as Slaves of each other?

The slave will be replicating from only one of the Masters.  It will get data from the other Master via that one.  But you need (and probably already have):

log_slave_updates = ON  -- on all 3 servers
server_id -- distinct values for all 3 machines