netinet: Promote IFP_TO_IA() from macro to function in_ifprimaryaddr().

[bms]

Summary

in_primaryaddr() exists only to support IPv4 multicast usage. Since the
adoption of epoch tracking, ifa_ref() is no longer required in its body.

Add a comment that IFP_TO_IA() is now deprecated. We cannot use
__deprecated1() from <sys/cdefs.h> as it is a macro, and not a function.

[pouria]

LGTM

[glebius]

sys/netinet/in.c

300

Since it operates in the scope of a single interface, let's name it with in_ifnet_ prefix, to match existing in_ifnet_broadcast and separate from other primitives that operator on global scope. Possible names are: in_ifnet_firstaddr, in_ifnet_primaryaddr, in_ifnet_primary.

302–311

Let's iterate over this interface address list instead of global list. Should be better for a host with many interfaces and addresses. This also will make the function not requiring VNET context to be set.

sys/netinet/in_var.h

155–167

Let's just remove it completely. There is no out of tree code that uses it. If there existed any, it would be broken numerous times, most recently with the epoch changes.

[pouria]

sys/netinet/in_var.h

155–167

Let's just remove it completely. There is no out of tree code that uses it. If there existed any, it would be broken numerous times, most recently with the epoch changes.

+1
I think this should be done in D55345.

[bms]

Rebase

[bms]

This comment was removed by bms.

[glebius]

P.S. I would suggest to retitle to netinet: introduce in_ifprimaryaddr() to lookup first IPv4 address of an ifnet. IMHO, there is not reason to reference a macro that is about to go away.