The kernel will acquire if_serializer when making
ifp->if_ioctl() calls.
-tsleep Low level drivers sometimes call tsleep() to wait for
- an interrupt driven event to wake them up. In these
- cases the interrupt will be blocked on the wlan
+{t,lk}sleep Low level drivers sometimes call {t,lk}sleep() to
+ wait for an interrupt driven event to wake them up. In
+ these cases the interrupt will be blocked on the wlan
serializer and the tsleep will timeout. To fix the
problem use zsleep() to release the &wlan_global_serializer
across the sleep operation.