IF_HANDOFF vs. IFQ_HANDOFF

[John Polstra]

Can somebody explain why there is both an IF_HANDOFF macro and an
IFQ_HANDOFF macro?  Except for a slight difference in parameters,
they both seem to do roughly the same thing using completely distinct
blocks of code.  Is IF_HANDOFF supposed to be used only when the
target queue is not the interface's if_snd queue?  That seems
likely, but a few pieces of code (e.g., ng_fec.c) use IF_HANDOFF to
put a packet into the if_snd queue.

Thanks,
John