sound: Retire pcm_veto_load

[christos]

Summary

pcm_veto_load is used to prevent pcm_register() from running if the root
feeder has not been registered yet. However, feeder_register_root() is a
SYSINIT.

Sponsored by: The FreeBSD Foundation
MFC after: 2 days

[christos]

Also note that pcm_register() does not really touch the root feeder in the first place.

sys/dev/sound/pcm/feeder.c

65

Could the M_WAITOK be a problem (i.e we sleep here and pcm_register() continues normally)?

[markj]

pcm_veto_load is used to prevent pcm_register() from running if the root feeder has not been registered yet. However, feeder_register_root() is a SYSINIT.

So are the functions which call pcm_register(), albeit indirectly. The point is probably to make sure that feeder_register_root() runs first. See the use of SI_ORDER_FIRST in the SYSINIT definition.

In D47280#1078121, @christos wrote:

Also note that pcm_register() does not really touch the root feeder in the first place.

It doesn't, but functions like pcm_addchan(), called after pcm_register(), do.

I'd at least add a comment above the SYSINIT definition explaining why this one comes first.

[christos]

Address Mark's comment.