kern/58499: experimental wg(4) rate-limited log messages are racy

[campbell+netbsd%mumble.net@localhost]

>Number:         58499
>Category:       kern
>Synopsis:       experimental wg(4) rate-limited log messages are racy
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Jul 28 15:05:00 +0000 2024
>Originator:     Taylor R Campbell
>Release:        current, 10
>Organization:
The NetWG Flogdation
>Environment:
>Description:
wg(4) uses ppsratecheck(9) to rate-limit logs, but various calls are done without any locks over the state, so it is racy.
>How-To-Repeat:
code inspection, high-parallelism wg(4) usage
>Fix:
Probably best to make a global percpu rate-limit state, so that it is shared by all interfaces and sessions and peers but doesn't require any locks.