Add a SUB_CALL_UNSUBSCRIBE event, to let the caller know that the
unsubscribe method should be called before destroyin the object.
enum sub_event_type {
SUB_CAN_SEND = 0x00000001, /* Schedule the tasklet when we can send more */
SUB_CAN_RECV = 0x00000002, /* Schedule the tasklet when we can recv more */
+ SUB_CALL_UNSUBSCRIBE = 0x00000004, /* The mux wants its unsubscribe() method to be called before destruction of the underlying object */
};
struct wait_event {