Bug 275146

Summary:	[tcp] odd error handling from net.inet.tcp.functions_default sysctl
Product:	Base System	Reporter:	Ed Maste <emaste>
Component:	kern	Assignee:	freebsd-net (Nobody) <net>
Status:	New ---
Severity:	Affects Only Me	CC:	asomers, tuexen
Priority:	---
Version:	14.0-RELEASE
Hardware:	Any
OS:	Any

Description Ed Maste freebsd_committer

2023-11-17 00:27:06 UTC

Setting functions_default to a nonexistent entry (because it is not loaded, or for any other reason) has odd user-facing error behaviour:

# sysctl net.inet.tcp.functions_default=rack
net.inet.tcp.functions_default: freebsd
sysctl: net.inet.tcp.functions_default=rack: No such file or directory

Some other sysctls use EINVAL which at least gives the user an understandable error:

# sysctl kern.timecounter.hardware=testing
kern.timecounter.hardware: TSC
sysctl: kern.timecounter.hardware=testing: Invalid argument

Comment 1 Ed Maste freebsd_committer

2023-11-18 18:31:41 UTC

Proposed patch from zlei in https://reviews.freebsd.org/D42647

Comment 2 Michael Tuexen freebsd_committer

2025-09-10 19:52:00 UTC

The current code now returns `ENOENT` if the requested TCP function block does not exist, `EINVAL` is returned if the requested function block cannot be the default function block.  I think returning these different error causes makes sense. It would be less informative to return `EINVAL` in both cases...

So I would vote for keeping the `errno` values as we have currently.

Comment 3 Alan Somers freebsd_committer

2025-09-10 20:04:20 UTC

I agree with Michael, too.