if_fxp.c vs mpd vs netgraph

I am now using fxp_c before backing out the atomic operations.
fxp does not hang using userland pppoe, it only freezes with kernel pppoe, 
which uses netgraph, so the atomic freeze might be related to netgraph somehow?
Perhaps ng_ether?

Jiawei
-- 
"Without the userland, the kernel is useless."
                                     --inspired by The Tao of Programming