Re: git: c93db4abf454 - main - udp: call UDP methods from UDP over IPv6 directly

On 17 Aug 2022, at 17:37, John Baldwin <jhb@FreeBSD.org> wrote:
> 
> On 8/17/22 9:19 AM, Gleb Smirnoff wrote:
>> John,
>> On Wed, Aug 17, 2022 at 09:04:08AM -0700, John Baldwin wrote:
>> J> > diff --git a/sys/netinet6/udp6_usrreq.c b/sys/netinet6/udp6_usrreq.c
>> J> > index a7bdfce97707..6a3ac2abd90b 100644
>> J> > --- a/sys/netinet6/udp6_usrreq.c
>> J> > +++ b/sys/netinet6/udp6_usrreq.c
>> J> > @@ -131,12 +131,18 @@ VNET_DEFINE(int, zero_checksum_port) = 0;
>> J> > SYSCTL_INT(_net_inet6_udp6, OID_AUTO, rfc6935_port, CTLFLAG_VNET | CTLFLAG_RW,
>> J> > &VNET_NAME(zero_checksum_port), 0,
>> J> > "Zero UDP checksum allowed for traffic to/from this port.");
>> J> > +
>> J> > +
>> J> > +/* netinet/udp_usrreqs.c */
>> J> > +pr_abort_t	udp_abort;
>> J> > +pr_disconnect_t	udp_disconnect;
>> J> > +pr_send_t	udp_send;
>> J> > +
>> J>
>> J> Oof, can you please put these in a header instead? <netinet/udp_var.h> would seem to be
>> J> a good candidate.
>> I actually don't want to share these functions to anybody. Sometimes we are
>> in a situation when two compilation units are historically separated,
>> while they need to call into each other functions, which by design are private.
> 
> Putting them in a header doesn't really change that. Anyone can add a local
> prototype and call it. Even better, they can add a _wrong_ prototype and
> call it with the wrong arguments. Or more likely, if the original function changes
> then previously working code breaks and the compiler won't catch this. In this
> specific case you mostly sidestep that due to using a typedef, but in general the
> wrong prototype problem is the reason to store prototypes in headers.
> 
> I'm not sure that "I don't trust other developers" is a valid reason to avoid the
> use of headers, or at least I'm not sure it outweighs "code breaks without
> the compiler noticing in the future". I'd rather signpost it in the header
> clarifying when it is allowed to be used (e.g. /* Shared between udp*_usrreq.c. */
> or the like)

Or if you really want to make it clearly signposted, add a udp_usrreq_private.h.

Jess