Re: kernel deadlock on fstchg with vnd

[mlelstv%serpens.de@localhost (Michael van Elst)]

campbell+netbsd-current-users%mumble.net@localhost (Taylor R Campbell) writes:

>This would need to be integrated into autoconf/specfs to avoid races
>in config_pseudo_spawn, sc->sc_configured, and config_pseudo_unspawn,

vnd is peculiar in that it spawns a unit whenever it is opened and
removes it again when it is closed.

VNDIOCSET for the same unit marks it VNF_INITED on success, and then
it persists.

VNDIOCSET for a different unit spawns that unit first and then marks
it VNF_INITED.

It would be simpler if there were a static dedicated control unit that
is used only for creating / purging other units.