protocols: init with standard SYSINIT(9) or VNET_SYSINIT

[glebius]

Summary

The historical BSD network stack loop that rolls over domains and
over protocols has no advantages over more modern SYSINIT(9).
While doing the sweep, split global and per-VNET initializers.

Getting rid of pr_init allows to achieve several things:
o Get rid of ifdef's that protect against double foo_init() when

both INET and INET6 are compiled in.

o Isolate initializers statically to the module they init.
o Makes code easier to understand and maintain.

[tuexen]

Can I still set transport relevant sysctl variables in /etc/sysctl.conf?

[glebius]

In D33537#757884, @tuexen wrote:

Can I still set transport relevant sysctl variables in /etc/sysctl.conf?

I don't see how could this change affect these sysctls!

[tuexen]

In D33537#757885, @glebius wrote:

In D33537#757884, @tuexen wrote:

Can I still set transport relevant sysctl variables in /etc/sysctl.conf?

I don't see how could this change affect these sysctls!

I was wondering if the initialisation happens at the same time...

[melifaro]

Really good simplification!

Worth mentioning that de-facto global protocols state will be inited in SI_ORDER_THIRD instead of SI_ORDER_SECOND and per-VNET ip[6]_init moved to SI_ORDER_FOURTH.

Nit: worth updating updating domain(9) to reflect pr_init removal,

sys/netinet/tcp_subr.c

1442

This looks like a non-virtualized variable, why do we want to assign it on per-VNET basis?
Also: maybe it's worth factoring out all hashsize calculation logic to a separate function?

[glebius]

Address Alexander's comments.

[glebius]

Worth mentioning that de-facto global protocols state will be inited in SI_ORDER_THIRD instead of SI_ORDER_SECOND and per-VNET ip[6]_init moved to SI_ORDER_FOURTH.

Can't find a good place to document that.

[pauamma_gundo.com]

Manual page change LGTM and is consistent with commit summary.

[glebius]

Committed 89128ff3e42196c8b41a3c59f7a2d95c0a4ac0ee