How should a driver shutdown a taskqueue on detach?

[Ryan Stone]

I'm trying to figure out how a driver is supposed to shut down its
interrupt-handling taskqueue when it detaches.  taskqueue(9) recommends
disabling interrupts, draining each task and then freeing the taskqueue.
The problem that I have is the interrupt-handling tasks will sometimes
re-enable interrupts on the device.  Is there a better way than using some
kind of flag internally in the driver to note that a detach is in progress
that the interrupt handlers will have to check before enabling interrupts?