Re: [Ksummit-discuss] [MAINTAINERS SUMMIT] Pull network and Patch Acceptance Consistency

Mauro Carvalho Chehab
2019-06-14T16:05:04Z

Em Fri, 14 Jun 2019 08:49:46 -0700
James Bottomley <James.Bottomley@HansenPartnership.com> escreveu:

> On Fri, 2019-06-14 at 12:43 -0300, Mauro Carvalho Chehab wrote:
> > Em Fri, 14 Jun 2019 08:23:05 -0700
> > James Bottomley <James.Bottomley@HansenPartnership.com> escreveu:
> >
> > > On Fri, 2019-06-14 at 12:11 -0300, Mauro Carvalho Chehab wrote:
> > > [...]
> > > > If you think this is relevant to a broader audience, let me reply
> > > > with a long answer about that. I prepared it and intended to
> > > > reply to
> > > > our internal media maintainer's ML (added as c/c).
> > > >
> > > > Yet, I still think that this is media maintainer's dirty laundry
> > > > and should be discussed elsewhere ;-)
> > > >
> > > > ---
> > >
> > > So trying not to get into huge email thread, I think this is the
> > > key
> > > point:
> > >
> > > [...]
> > > > Currently, I review all accepted patches.
> > >
> > > This means you effectively have a fully flat tree.
> >
> > Yes.
> >
> > > Even if you use
> > > git, you're using it like an email transmission path. One of the
> > > points I was making about deepening the tree is that the maintainer
> > > in
> > > the middle should trust the submaintainer they pull from, so there
> > > should be no need to review all the patches because of that trust.
> >
> > It is not a matter of trust. It is just that the media subsystem is
> > a complex puzzle. Just the V4L2 API has more than 80 ioctls.
> >
> > So, the goal here is to do my best to ensure that patches will get
> > at least two reviews.
> >
> > > This is how deepening the tree helps to offload maintainers because
> > > review is one of the biggest burdens we have and deepening the tree
> > > is
> > > a way to share it. Without trust, we achieve no offloading and
> > > therefore no utility from deepening the tree.
> >
> > Yeah, I know one day this won't scale. The day it happens, I'll
> > just start picking pull requests. As we already use git, a change
> > like that would be trivial.
> >
> > > So, to get back to the original question, which was *should* we
> > > deepen
> > > the tree: why don't you feel you can let branches with patches you
> > > haven't reviewed into your tree? I've characterised it as a trust
> > > issue above, but perhaps it isn't. I think this is a key question
> > > which
> > > would help us understand whether a deeper tree model is at all
> > > possible.
> >
> > One of the aspects is that developers nowadays are specialists on a
> > subset of the media devices. Most of them are working on complex
> > camera support, with envolves a subset of the APIs we have. They
> > never worked on a driver that would use other parts of the API, like
> > DVB, Remote Controllers, TV, V4L2 streaming devices, etc.
> >
> > So, having someone with a more generalist view at the end of the
> > review process helps to identify potential problems that might
> > affect other devices, specially when there are API changes
> > involved[1].
> >
> > [1] Since when I started maintaining the subsystem, back on 2005,
> > on almost every single Kernel review there are API changes in
> > order to support new types of hardware.
>
> Actually, this leads me to the patch acceptance criteria: Is there
> value in requiring reviews? We try to do this in SCSI (usually only
> one review), but if all reviewers add a
>
> Reviewed-by:
>
> tag, which is accumulated in the tree, your pull machinery can detect
> it on all commits in the pull and give you an automated decision about
> whether to accept the pull or not. If you require two with one from a
> list of designated reviewers, it can do that as well (with a bit more
> complexity in the pull hook script).
>
> So here's the question: If I help you script this, would you be willing
> to accept pull requests in the media tree with this check in place?
> I'm happy to do this because it's an interesting experiment to see if
> we can have automation offload work currently done by humans.

We could experiment something like that, provided that people will be
aware that it can be undone if something gets wrong.

Yet, as we discussed at the Media Summit, we currently have an
issue: our infrastructure lack resources for such kind of automation.

Thanks,
Mauro