Date:   Wed, 15 Nov 2017 13:29:55 +1100
From:   "Tobin C. Harding" <me@...in.cc>
To:     Jonathan Corbet <corbet@....net>
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH] docs: add submitting-pull-requests.rst

On Tue, Nov 14, 2017 at 04:48:16PM -0700, Jonathan Corbet wrote:

Awesome comments Jon, I knew there would be more to writing docs than
first met the eye.

> On Wed, 15 Nov 2017 09:54:21 +1100
> "Tobin C. Harding" <me@...in.cc> wrote:
> 
> > There is currently no documentation on how to create a pull request for
> > Linus.
> > 
> >     Anyway, this actually came up at the kernel summit / maintainer
> >     meeting a few weeks ago, in that "how do I make a good pull request
> >     to Linus" is something we need to document.
> > 
> >     Here's what I do, and it seems to work well, so maybe we should turn
> >     it into the start of the documentation for how to do it.
> > 
> > Create document from email thread on LKML (referenced in document).
> > 
> > Signed-off-by: Tobin C. Harding <me@...in.cc>
> > ---
> > 
> > Is it rude to send this during the merge window? Can resend after it closes if
> > it makes life easier.
> 
> I can handle patches during the merge window.  That said, while I welcome
> this effort and think it's a good start, there's a few things I'll
> quibble about:
> 
>  - Much of this was actually written by Greg, I believe, and some by Linus.
>    That deserves credit in the changelog, if nowhere else.

Yeah, I struggled for ages with the tense, Greg's stuff is obviously
written as him. But I didn't want to paraphrase and present it as if I'd
written it. After your comments I'm still unsure of the _best_ way to
present this material with a good flow but still giving credit where
credit is due? I didn't seem right to add their names to the document
(thereby presenting myself as them). I did not think of the changelog -
I'll go that path for v2.

>  - Putting it in Documentation/process as RST is good.  But it should be
>    added to index.rst and made part of the docs build.  I suspect you
>    haven't run it through sphinx at all yet, right?  Some things are
>    unlikely to format the way you think they might.

My bad, I knew I would botch some of the RST stuff, didn't think to run
it through sphinx (I tend to view kernel docs as the raw files ;)

> Finally, I see this as being the first installment in what, I hope, will
> someday be a nice "how to be a kernel maintainer" manual.  I wouldn't
> insist on it before taking a patch like this, but if you could see
> through to organizing it as a chapter in a bigger sub-book, that would be
> great.

Happy to do so. I'm no way qualified to produce much of the text but
perhaps can assist in getting things moving.

> Finally finally... Dan Williams [CC'd] has plans for doing some
> maintainer-level documentation.  He may have thoughts on how this fits
> into what he's scheming, and I'd suggest copying him on the next
> iteration.

Let's liaise on this Dan (if you want to).

> Finally finally finally...some specific comments on the text.  Some of
> them might be read to suggest a major expansion of the work you've done;
> please see that as me saying "that would be nice".  Doing all of this is
> not a precondition to getting this document added!

There is no rush to get merged, let's get it into shape first :)

> > +Submitting Pull Requests to Linus: a guide for maintainers
> > +==========================================================
> > +
> > +This document is aimed at kernel maintainers.  It describes a method for creating
> > +a pull request to be sent to Linus.
> 
> Limiting text widths to, say, 75 columns when possible is preferable.  Word
> has it some maintainers are still reading the docs on their adm3a
> terminals.

Got it. (idea for next doc 'column widths howto' - your canonical guide
to column widths (includes git brief, commit log, email, source code,
and docs).

I'm kidding. 75 it is.

> Most maintainers push directly to Linus, so that's an obvious best focus,
> but pull requests happen at other levels too.  One would hope that this
> information would be applicable at all levels, so it might be nice to
> describe it as such.

Oh, Greg had this, I stripped it out. Back in on next spin.

> > +Configure Git
> > +-------------
> 
> "Configure Git to use your private key"
> 
> We are, of course, missing the whole discussion on why one would want a
> keypair, how to create it, how to get it into the web of trust, etc.  All
> fodder for a separate chapter in our shiny new maintainer book :)  But it
> is worth saying at least that this is about making Git use your key so you
> can sign tags for pull requests.

Funny you should say that, I'm trying to get into the web of trust so
perhaps I can help with that document (as I work out how to do it).

> > +Since you _usually_ would use the same key for the same project, just set it
> > +once with
> 
> If you end a line like that with "::", the following indented section will
> be formatted as code by sphinx.  That's almost always what you want.
> 
> > +	git config user.signingkey "keyname"

cool.

> > +
> > +and if you use the same key for everything, just add "--global".
> > +
> > +Or just edit your .git/config or ~/.gitconfig file by hand, it's designed to be
> > +human-readable and writable, and not some garbage like XML:
> > +
> > +	[torvalds@i7 ~]$ head -4 .gitconfig
> > +	[user]
> > +		name = Linus Torvalds
> > +		email = torvalds@...ux-foundation.org
> > +		signingkey = torvalds@...ux-foundation.org
> > +
> > +You may need to tell git to use gpg2
> > +
> > +	[gpg]
> > +		program = /path/to/gpg2
> > +
> > +You may also like to tell gpg which tty to use (add to shell rc file)
> > +
> > +	export GPG_TTY=$(tty)
> > +
> > +
> > +Branch, Tag, Push
> > +-----------------
> > +
> > +Next, put your changes on a branch, hopefully one named in a semi-useful way (I
> > +use 'char-misc-next' for my char/misc driver patches to be merged into
> > +linux-next).  That is the branch you wish to tag and have Linus pull from.
> 
> Management of patches and branches would, of course, make for another nice
> chapter.

Not maintainer specific though, right? 

> > +Name the tag with something useful that you can understand if you run across it
> > +in a few weeks, and something that will be "unique".  Continuing the example of
> 
> Greg likes to put quotes in weird places, but we don't need to preserve
> that :)  Git will force the tag to be "unique", so we can just say unique. 

He also adds two spaces in between sentences, that threw me. He is
correct though, I intend on imitating.

> > +the char-misc tree, for the patches to be sent to Linus for the 4.15-rc1 merge
> > +window, I would name the tag 'char-misc-4.15-rc1':
> > +
> > +	git tag -s char-misc-4.15-rc1 char-misc-next
> > +
> > +that will create a signed tag called 'char-misc-4.15-rc1' based on the last
> > +commit in the char-misc-next branch, and sign it with your gpg key (configured
> > +above).
> > +
> > +When you run the above command, git will drop you into an editor and ask you to
> > +describe the tag.  In this case, you are describing a pull request, so outline
> > +what is contained here, why it should be merged, and what, if any, testing has
> > +happened to it.  All of this information will end up in the tag itself, and then
> > +in the merge commit that Linus makes, so write it up well, as it will be in the
> > +kernel tree for forever.
> 
> s/for//
> 
> Sphinx will format the following indented text differently, which may not
> be what you want.  I think you should really introduce it with "Linus said
> this:" perhaps with a link to the list archive.

Ok, perhaps there are examples currently in tree of how best to
quote. I'll dig around.

> > +	Anyway, at least to me, the important part is the *message*. I want to
> > +	understand what I'm pulling, and why I should pull it. I also want to
> > +	use that message as the message for the merge, so it should not just
> > +	make sense to me, but make sense as a historical record too.
> > +
> > +	Note that if there is something odd about the pull request, that
> > +	should very much be in the explanation. If you're touching files that
> > +	you don't maintain, explain _why_. I will see it in the diffstat
> > +	anyway, and if you didn't mention it, I'll just be extra suspicious.
> > +	And when you send me new stuff after the merge window (or even
> > +	bug-fixes, but ones that look scary), explain not just what they do
> > +	and why they do it, but explain the _timing_. What happened that this
> > +	didn't go through the merge window..
> > +
> > +	I will take both what you write in the email pull request _and_ in the
> > +	signed tag, so depending on your workflow, you can either describe
> > +	your work in the signed tag (which will also automatically make it
> > +	into the pull request email), or you can make the signed tag just a
> > +	placeholder with nothing interesting in it, and describe the work
> > +	later when you actually send me the pull request.
> > +
> > +	And yes, I will edit the message. Partly because I tend to do just
> > +	trivial formatting (the whole indentation and quoting etc), but partly
> > +	because part of the message may make sense for me at pull time
> > +	(describing the conflicts and your personal issues for sending it
> > +	right now), but may not make sense in the context of a merge commit
> > +	message, so I will try to make it all make sense. I will also fix any
> > +	speeling mistaeks and bad grammar I notice, particularly for
> > +	non-native speakers (but also for native ones ;^). But I may miss
> > +	some, or even add some.
> > +
> > +			Linus
> > +
> > +An example pull request of mine might look like:
> 
> Here's a change of voice back to Greg.  Be careful about appearing to put
> one person's words into another's mouth.

Agreed. (commented on above).

> Here you definitely want the :: treatment, or sphinx will whine about the
> strange (to it) indents.
> 
> > +	Char/Misc patches for 4.15-rc1
> > +
> > +	Here is the big char/misc patch set for the 4.15-rc1 merge
> > +	window.  Contained in here is the normal set of new functions
> > +	added to all of these crazy drivers, as well as the following
> > +	brand new subsystems:
> > +		- time_travel_controller: Finally a set of drivers for
> > +		  the latest time travel bus architecture that provides
> > +		  i/o to the CPU before it asked for it, allowing
> > +		  uninterrupted processing
> > +		- relativity_shifters: due to the affect that the
> > +		  time_travel_controllers have on the overall system,
> > +		  there was a need for a new set of relativity shifter
> > +		  drivers to accommodate the newly formed black holes
> > +		  that would threaten to suck CPUs into them.  This
> > +		  subsystem handles this in a way to successfully
> > +		  neutralize the problems.  There is a Kconfig option to
> > +		  force these to be enabled when needed, so problems
> > +		  should not occur.
> > +
> > +	All of these patches have been successfully tested in the latest
> > +	linux-next releases, and the original problems that it found
> > +	have all been resolved (apologies to anyone living near Canberra
> > +	for the lack of the Kconfig options in the earlier versions of
> > +	the linux-next tree creations.)
> > +
> > +	Signed-off-by: Your-name-here <your_email@...ain>
> > +
> > +
> > +The tag message format is just like a git commit id.  One line at the top for a
> > +"summary subject" and be sure to sign-off at the bottom.
> 
> FWIW, I've never formatted tag messages that way, and I'm not sure how many
> others do.  But perhaps we should all be doing it?

Hopefully the patches going in will be reviewed by other maintainers and
suggestions will flow :) 

> > +Now that you have a local signed tag, you need to push it up to where it can be
> > +retrieved by Linus:
> > +
> > +	git push origin char-misc-4.15-rc1
> > +
> > +pushes the char-misc-4.15-rc1 tag to where the 'origin' repo is located.
> > +
> > +
> > +Create Pull Request
> > +-------------------
> > +
> > +The last thing to do is create the pull request message.  Git handily will do
> > +this for you with the 'git request-pull' command, but it needs a bit of help
> > +determining what you want to pull, and what to base the pull against (to show
> > +the correct changes to be pulled and the diffstat.)
> > +
> > +The following command(s) will generate a pull request:
> > +
> > +	$TREE=git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git/
> 
> I don't believe that $ is correct

Bad Tobin, no biscuit. (read: cookie)

> > +	git request-pull master $TREE char-misc-4.15-rc1
> > +
> > +This is asking git to compare the difference from the 'char-misc-4.15-rc1' tag
> > +location, to the head of the 'master' branch (which in my case points to the
> > +last location in Linus's tree that I diverged from, usually a -rc release).
> > +
> > +Note: please use the git protocol (for justification from Linus see referenced
> > +email thread).
> 
> We need a reference to that thread.
> 
> > +If the char-misc-4.15-rc1 tag is not present in the repo that I am asking to be
> > +pulled from, git will complain saying it is not there, a handy way to remember
> > +to actually push it to a public location.
> > +
> > +The output of 'git request-pull' will contain the location of the git tree and
> > +specific tag to pull from, and the full text description of that tag (which is
> > +why you need to provide good information in that tag.)  It will also create a
> > +diffstat of the pull request, and a shortlog of the individual commits that the
> > +pull request will provide.
> > +
> > +
> > +References
> > +----------
> > +
> > +The thread that this document is based on:
> > +
> > +	https://lkml.org/lkml/2017/11/14/184
> 
> Ah, there's that reference.  I think it should be at the top before you
> first start quoting from it.

Perhaps (at start of document)

    This document was written by Tobin C. Harding (not an experienced
    maintainer) primarily from emails by Greg Kroah-Hartman and Linus
    Torvalds. Suggestions and fixes by Jonathan Corbet. Misrepresentation
    was unintentional but inevitable, please direct abuse to "Tobin
    C. Harding" <me@...in.cc>. 

    Original email thread 

        https://lkml.org/lkml/2017/11/14/184

> I think there's something missing here: what do you do with that output
> from 'git request-pull'?  There should be a little section on emailing it
> to the relevant upstream maintainer and how to decide where to copy the
> request to.  Pull requests should always be copied to a public list so that
> others know that the request has been made.  Some guidance on subject-line
> formatting would be good; as I recall, Linus filters mail that says "git"
> or "pull" specially.  I might also add something about how to know when the
> pull has happened (sign up to the commits list if nothing else).
> 
> Thanks for doing this,

Cheers Jon, nice to work with you.

Tobin.

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