Hi,
Sorry for the late reply.

> First explain:
>
> - which situations does checkpatch.pl currently complain about?
>
Currently, checkpatch complains whenever the author mail is not
found in any signed-off-by block in the patch.


> - for which situation do you want to have more refined checks?
>
The situations where author might have signed off using a different
email. I believe multiple mail addresses isn't uncommon.


> - why does that actually improve checkpatch.pl?

It shall significantly reduce the number of author_sign_off warnings. I have
not yet created a statistical count, but looking at the data I found several
such instances. This is certainly a false positive due to a condition which
checkpatch was not programmed to handle.
The avoidance of warnings on such known cases might also save the 
committer and the maintainers some time.


> Checkpatch.pl should complain when developers do something wrong.
>
> To really understand what is wrong behavior and what is not, you probably
> need to create some statistics on who authors and signs off with which
> names and email addresses.
>
> Maybe we can collect all the previous instances where we know that
> frequent developers, e.g., with more >100 commits, use multiple email
> addresses interchangeably. If we add that list to the repository and
> let others know how to maintain it, checkpatch.pl can make use of that.
>
> With that extended check, we can warn newbies that just have a broken git
> and sign-off setup and still reduce the false positives for the
> experienced developers that might just have good reasons to have the
> setup they have, i.e., they have this setup for many years and want to
> keep it that way.

This seems like a great idea. I can load the mailmap data into checkpatch
and form some kind of map between names and mail addresses. 
If two mail addresses belong to same user then the warning can be ignored
totally.

I know that the kernel community is strict about such changes. So will this be
acceptible? I can generate a proof of concept patch with the data at hand
if it seems like a good thing to work on.


> You can try to work that through or look for another case of potential
> checkpatch.pl improvement in your evaluation data.

I haven't found anything substantial yet. I will continue looking. 
Earlier, you had told if I would like to take the task from Ayush to
fix checkpatch with git ranges. I would like to know about the task
and take it up if possible.

Thanks,
Dwaipayan.