To configure a driver as being MT SAFE, initialize the cb_ops(9S) and dev_ops(9S) data structures. This code must be in the header section of your module. For more information, see Example 12–1, and dev_ops(9S).
The driver is configured to be MT SAFE by setting the cb_flag to D_MP. It also specifies any MT STREAMS perimeters by setting flags in the cb_flag field. (See mt-streams(9F).)