Re: Introducing localcount(9)

[Chuck Silvers <chuq%chuq.com@localhost>]

hi paul,

is the intent that in the long term everything should be converted to use
the new interfaces and that the non-"acquire" interfaces be removed?
(that would be my preference, as well as keeping the original names...
the new names are long enough that they make it harder to read the code,
at least for me.)

if so, is the reason that you aren't converting everything now just that
you wanted to keep this change to a managable size?  I could help with
converting the rest of the drivers now if that would be useful.

a couple more suggestions:

rather than require every driver to use the "DEVSW_MODULE_INIT" hack
when defining a devsw structure, it would be better to have bdevsw_attach()
and cdevsw_attach() take care of the localcount details without the
driver author needing to be aware of them.  I'd also think it would be
better to have the d_localcount field be the actual "struct localcount"
rather than a pointer to one, since you already enforce that the d_localcount
pointer is non-NULL and not shared between structures.

device_acquire() seems of dubious value... it's only safe to use when one
already holds a reference on the device_t, so having it as an interface
is just inviting people to try to do fancy (and probably wrong) things
with the reference counting.  in your branch, you only use it in ld.c
(where it's either unnecessary or you're using it unsafely) and in fss.c
(which is just working around the fact that config_attach_pseudo()
returns a device_t with no reference, and it would seem better to fix
config_attach_pseudo() rather than work around that in the fss driver.)
I think it would be better to not have a device_acquire() interface
exposed to drivers.

-Chuck