Comment by Aloisius

There does appear to be a bug, but it's not what the blog describes.

If tcp_now stops updating at <= 2^32 - 30000 milliseconds, then TSTMP_GEQ(tcp_now, timer) will always fail since timer is tcp_now + 30000 which won't wrap.

This does look like it is possible since calculate_tcp_clock() which updates tcp_now only runs when there's TCP traffic. So if at 49 days uptime you halted all TCP traffic and waited about a day, tcp_now would be stuck at the value before you halted TCP traffic.

In cases where tcp_now gets stuck at > 2^32 - 30000, it looks like TCP sockets in the TIME_WAIT will end up being closed immediately instead of waiting 30 seconds, which isn't great either.