PEVENT_COUNTER
MiGetEventCounter(
  );

Routine Description:

    This function maintains a list of "events" to allow waiting
    on segment operations (deletion, creation, purging).

Arguments:

    None.

Return Value:

    Event to be used for waiting (stored into the control area) or NULL if
    no event could be allocated.

Environment:

    Kernel mode, PFN lock held.