Request for reviewers for vlan(4) locking improvements

[Matt Joras]

Hello,

I am looking for people to give feedback on a review I've opened to
improve the locking in vlan(4). Anyone who's done a fair amount of
destroying vlan interfaces on live systems has probably run into
panics in if_vlan. This is because there is no real synchronization to
prevent a vlan interface from being destroyed while there are mbufs in
the network going through its functions. Isilon's customers have hit
panics like this, so I've reworked the locking to make destroying
vlans safe on live systems, and fixed every instance of unsafe access
I could find.

If anyone has an interest in this work please review the revision:
https://reviews.freebsd.org/D11370

Thanks,
Matt Joras