Re: RFC: using supersedes: trailer to indicate patch/series revision flow

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Han-Wen,

On Fri, Nov 8, 2019 at 9:31 AM Han-Wen Nienhuys <hanwen@google.com> wrote:
> On Fri, Nov 8, 2019 at 12:45 AM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > > 2. Should supersedes: link to the previous version of the patch, or the
> > >     first ever version of the patch? I am leaning towards the latter,
> >
> > And then how do you know that version 2 was superseded by version 3?
>
> You throw the message ID into a search engine, and see what it returns.
>
> The advantage of keeping the patch series ID stable is that you can
> consider a patchseries as a document and then easily index it inside a
> service (say, patchwork) using Lucene, ElasticSearch or some other
> common technology.
>
> If you make the "supersedes" refer to specific versions, a workflow
> service will be more susceptible to errors if messages were lost, and
> the service has to work harder to aggregate the different versions of
> a patchseries together.
>
> Is it common for different authors to superseed each other's patch
> series? If yes, "superseeds: precise version" is more precise, if not,
> you get the same information from the timestamp of the cover letter.

All/most of the above applies only to versioning of patch series that
implement a fixed feature, with a fixed scope.
So Vn+1 is really an improved version of Vn, and nothing more or less.

But this does not apply to many patch series in Linux kernel development.
Patch series may
  - grow (more patches added),
  - shrink (some patches rejected, or already applied independently),
  - be split in multiple series,
  - dropped but some parts reused in other series (possibly by someone
    else),
  - ...
That's the hard work in patch tracking.

So series IDs do not cope well with this, and "superseded" really should
apply to individual patches, not series, too.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds