Did you by any chance use an automated tool of any sort to find this issue or
generate the fix?

I don't think this is actually necessary here, you're in the same context as the
updater of the stats, you don't need any protection.
You can remove u64_stats_update_begin() / end() (in net-next, there's no bug).

I won't comment on implications of calling dim_update_sample() in a loop.

Please make sure you answer my "did you use a tool" question, I'm really
curious.

I have no tool, I find this when I investigating a DIM related issue.

Thanks