Re: [Ksummit-discuss] Allowing something Change-Id (or something like it) in kernel commits

[Christian Brauner <christian.brauner@ubuntu.com>]

On Mon, Aug 26, 2019 at 04:11:12PM -0700, Doug Anderson wrote:
> Hi,
> 
> On Mon, Aug 26, 2019 at 4:02 PM Theodore Y. Ts'o <tytso@mit.edu> wrote:
> >
> > On Mon, Aug 26, 2019 at 02:35:33PM -0700, Doug Anderson wrote:
> > > * This requires extra tooling that I think nobody will adopt.  People
> > > today already (accidentally) adopt Change-Id in the non-discardable
> > > portion.  I think it would be easier to get everyone currently
> > > removing Change-Id to start including it again than it will be to get
> > > everyone to change their tools to move it to the discardable portion.
> >
> > The reason why people Change-Id's exist in commits today is because of
> > tooling which is distributed as part of Gerrit.  That's why people are
> > deeply suspicious of any solution that involves Change-Id in the
> > non-discarded portion --- because the majority of Gerrit servers up
> > until now are behind corporate firewalls and since Gerrit servers have
> > robots.txt files, most Change-Id tend to be useless.
> >
> > If we come up with new tooling which is more useful, people will use
> > it.  If it's not useful and doesn't makes life easier, people won't.
> 
> Unfortunately the tooling won't come up until Change-Id is there and
> Change-Id can't be there till the tooling is there.  ;-)
> 
> 
> > On Mon, Aug 26, 2019 at 03:06:43PM -0700, Doug Anderson wrote:
> > > 2. If, as I expect, Change-Id as part of the patch stays NAKed then I
> > > will modify the tools I use to post upstream (currently patman) to
> > > encode the Change-Id.  My naive proposal would be:
> > >
> > > Message-Id: ChangeId-YYYY-MMDD-HHMMSS-PatchNum
> > >
> > > If I try this and it works for me then I will post out and suggest
> > > that any other like-minded people encode Change-Id into Message-Id in
> > > a similar way.
> >
> > ... and I would expect patches with this would get NACK'ed because
> > they would be just as useless as Change-Id's are perceived to be
> > today.  People who are gaming the rules will tend not to looked upon
> > favorably; the same will apply to their patches.
> 
> Sigh.  Email is so hard to communicate over.  I'm not intending to
> include the Message-Id in the commit.  I'm intending to use the
> Change-Id _in_ the Message-Id.  The Message-Id already has a bunch of
> random characters in it.  Why not make them useful for something?
> 
> 
> > BTW, the Message-Id you've listed above is not legal, per RFC-5322.  A
> > msg-id has to look like a e-mail address (left-hand-side@example.com).
> > So something like this is legal as a message id:
> >
> > I3268f9036512c4378cde1da37e0612b43ed4d384@linux-review.googlesource.com
> 
> I think this is the same comment that Thomas Gleixner had.  I will
> certainly make sure my Message-Ids are formed correctly.  Thank you
> both for pointing this out to me.  Presumably I would have noticed it
> when actually trying to implement this but now I definitely will.
> 
> 
> > ... and indeed, that's more useful, because it tells us how to
> > interpret I3268f9036512c4378cde1da37e0612b43ed4d384 --- it's a
> > Change-Id assigned by the linux-review.googlesource.com Gerrit server.
> >
> > In contrast a bare "I3268f9036512c4378cde1da37e0612b43ed4d384" is
> > going to be presumed to be useless.  And in fact, a Google search for
> > this ID returns *nothing*.  Yet visiting the link
> > https://linux-review.googlesource.com/c/1158 actually returns
> > something useful.   That's why the latter is superior to the former.
> 
> Sure, except that in my case there is no gerrit server to provide a
> link to.  I use an upstream-first approach which means that all
> initial work is done with mailing lists.  There is no server to
> provide context to.  I think we are re-hashing old emails in this
> thread.
> 
> 
> > In summary,
> >
> > Not useful: (and will be probably nacked)
> >
> > Change-Id: I3268f9036512c4378cde1da37e0612b43ed4d384
> > Message-Id: I3268f9036512c4378cde1da37e0612b43ed4d384
> >
> > Useful:
> >
> > Link: https://linux-review.googlesource.com/c/1158
> > Link: https://lkml.kernel.org/r/20190826204407.17759-1-daniel.lezcano@linaro.org
> >
> > Not as useful: (people will prefer the Link example above)
> >
> > Message-Id: 20190826204407.17759-1-daniel.lezcano@linaro.org
> 
> Presumably all the above is because you thought I was including the
> Message-Id in the commit.  I'm not.  Locally I will have Change-Id in
> my commit.  The scripts I use to post to the mailing lists will strip
> the Change-Id out and use it to make the actual Message-Id.  I will

Hm, I've spoken in favour of the Link: approach for upstream purposes.
But I do see the point in making it possible for people to somehow have
a workflow involving change-ids that does not interfer with regular
upstream expectations, i.e. no Change-Ids in commit messages.

One thing that came up was to place stuff like Change-Id after the ---
which git format-patch would leave out. This still has the problem
though that a git merge will keep the stuff after the --- and so a git
tag followed by a git request-pull would have the stuff in there as well
afaict. So I wonder if you couldn't simply enable Gerrit to look for
stuff like Change-Ids in git notes. They wouldn't show up on merges and
pulls afaict...

Christian
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