ttydev_cdevsw has no d_purge

[Ed Schouten]

Hi Hans,

2012/8/8 Hans Petter Selasky <hselasky at c2i.net>:
> Are you sure that the new softc won't be used in any callbacks when
> tty_rel_gone() is called, except for tsw_free() ?

Yes. Otherwise you would have already seen a kernel panic. See
/sys/sys/ttydevsw.h; it has assertions on the locking.

> It is like a drain state, where a unit is collected for free, and then
> committed to free state when the tsw_free() is called. In the [unlocked] time
> in between the unit cannot be re-used.

How is this different from calling alloc/free directly? Why would it
need to go through this `drain' state?

-- 
Ed Schouten <ed at 80386.nl>