sound: Remove redundant KASSERTs from unit.c

[christos]

Summary

All functions in unit.c have a KASSERT testing whether snd_unit has been
initialized (i.e snd_unit_init() has been called). However,
snd_unit_init() is called unconditionally upon sound(4) load in
dsp_sysinit(), so the KASSERTs will never fail.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

[christos]

Remove copyright update.

[emaste]

sys/dev/sound/unit.c

163–164

We'd first need to make sure this case cannot happen (e.g. turning this into a KASSERT that we're not called twice)

[christos]

Address Ed's comment.

sys/dev/sound/unit.c

163–164

Although it should most likely not be a problem to remove this check, I will keep it for now to make sure nothing has went off my radar.

[markj]

However, snd_unit_init() is called unconditionally upon sound(4) load in dsp_sysinit(), so the KASSERTs will never fail.

But the sound module can have multiple sysinits, and some of them might run before dsp_sysinit(). If that happens and they use these accessors, you'll end up with a confusing bug.

I don't object to the change, but the argument for making the change isn't really correct as I understand it. As a middle ground you could at least simplify the macro and just use a plain KASSERT everywhere, I think that's good enough. It's up to you.

[christos]

Abandoning since I will be submitting a patch which eventually gets rid of unit.* completely.