The net.inet.tcp.rack.measure.wma_divisor sysctl is the divisor
of the goodput weighted moving average used when the dynamic
goodput multiplier is enabled.
Setting it to 0 panics the kernel. A negative value makes the
update subtract new samples from the average.
Add a sysctl handler that rejects values <= 0 with EINVAL.
MFC after: 1 month
Found with: Claude Code Opus 5.5