Re: RFC tips-for-maintainers.txt (was Re: [GIT PULL] platform-drivers-x86 for 4.6-3)

[Darren Hart]

On Thu, Apr 28, 2016 at 02:25:00PM +1000, Michael Ellerman wrote:
> On Wed, 2016-04-27 at 09:57 -0700, Darren Hart wrote:
> > On Wed, Apr 27, 2016 at 09:08:01AM -0700, Linus Torvalds wrote:
> > > On Tue, Apr 26, 2016 at 10:02 PM, Darren Hart <dvhart@xxxxxxxxxxxxx> wrote:
> > > >
> > > > Found myself not wanting to send a one patch pull request, but not wanting to
> > > > wait until RC6 and possibly miss 4.6.
> > > >
> > > > Do you have a preference during the RC cycle in terms of balance between patch
> > > > count and frequency for a small subsystem like platform-driver-x86?
> > >
> > > Once a week like this is fine, even if it's just a single trivial
> > > one-liner change.
> ...
> 
> > Very helpful, thank you Linus. I believe I just inherited a TODO to find the
> > right spot in the documentation to record this.
> 
> Actually I've been meaning to do that for ages, and I have a few more collected
> in my notes.
> 
> How do these look?
> 

Wow, thanks for doing this!

> 
>   Git pulls should start "[GIT PULL]":
> 
>       http://lkml.kernel.org/r/CA+55aFxURVwV4NZcPsVzQ-Ui9Nmn2vdXVw==S5RKhXC1y4b8og@xxxxxxxxxxxxxx
> 
>        just for your information: this pull request doesn't show up with my
>       normal merge-window search pattern of "git pull", because you never
>       actually say "pull" anywhere.
> 
>       Please use a subject with "[GIT PULL]" prefix (preferred), or just
>       change the body of the email to have a "please pull" in it or
>       something.  I get too much email, and particularly during the merge
>       window it really helps if I can keep my pull emails separate from
>       other stuff by just having them match a simple pattern.

I would suggest we extract and consolidate the direction we receive from Linus
and write it up in our own words, rather than using quotes and having the reader
piece them together.

Linus has said he does not like to be prescriptive, he'd rather say "don't do
this" than "everyone must do this". However, I think our documentation should
include guidelines and known good methods. So for this subject, perhaps:

--
Git pull requests should include the "[GIT PULL]" prefix in the subject and
contains "please pull" somewhere in the body. The "git request-pull" command
will generate an acceptable email message body.

http://lkml.kernel.org/r/CA+55aFxURVwV4NZcPsVzQ-Ui9Nmn2vdXVw==S5RKhXC1y4b8og@xxxxxxxxxxxxxx
--

In my opinion, this tool should be more robust and generate the full email body
using parameters, which is why I (and many other maintainers) use wrapper
scripts. We could include an example here, but that's probably best left to some
kind of a tooling repository or updates to git itself.

> 
> 
>   Linus generally likes to see merge conflicts himself, for subtle conflicts
>   you can provide a separate tree with the result of your merge:
> 
>       http://lkml.kernel.org/r/CA+55aFwM2e9sTVtYjrnPjh5RsZafBXbJ5FFYkYi730ojOn+8-w@xxxxxxxxxxxxxx
> 
>       On Sat, Sep 5, 2015 at 2:37 AM, Neil Brown <neil@xxxxxxxxxx> wrote:
>       >
>       > Please pull these updates.  I've already merged with the 'block' tree
>       > to resolve a few simple conflicts.
> 
>       So for the future, I actually prefer to see and handle the conflicts myself.
> 
>       I really just prefer knowing what's going on, and merge conflicts are
>       an indication of cross-maintainer issues which are *exactly* the kinds
>       of things I want to be aware of.
> 
>       However, in this case I was "ok, I've already done several other merge
>       resolutions with the wbole damn bio_endio error handling changes", so
>       I felt I was aware enough about how that ended up being a
>       cross-subsystem conflict, and just took your pre-merged version.
> 
>       If you feel that the conflicts are particularly subtle, or just
>       generally worry about the merge, or just because you want to do some
>       merge-testing, what some people end up doing is to send me their
>       unmerged branch, and then send me a separate ".. and here's the merge
>       I did". I'll then do the merge myself anyway, but then after doing the
>       merge I'll switch to a temporary testing branch and re-do the  merge
>       with the pre-merged state just to verify. Generally the end result is
>       identical, but when it isn't, that's actually usually interesting
>       (sometimes it's just a ordering difference, but sometimes it's a merge
>       error - and so far I think most merge errors have come from
>       sub-maintainers, for the simple reason that they generally aren't as
>       used to merging as I am - so even if they know the code better, I
>       sometimes catch merge gotcha's better).
> 

Similar comments for this one. Also s/tree/branch/

All the above really can be condensed into something like this:

--
Send your pull requests based off the Linux master branch and leave the merging
to Linus as he prefers to see the conflicts. If the merge is complex, or
contains some domain specific gotchas, send a separate message or a note in the
pull request, pointing to a separate branch which contains your merge.

http://lkml.kernel.org/r/CA+55aFwM2e9sTVtYjrnPjh5RsZafBXbJ5FFYkYi730ojOn+8-w@xxxxxxxxxxxxxx
--

Ideally this wouldn't be Linus-specific in my opinion, but instead embody
best-practices we've built up over the years.


>   Don't rebase your tree between linux-next and requesting a pull unless you
>   absolutely must:
> 
>       http://lkml.kernel.org/r/CA+55aFyrep8hMApzYA4DyFgEoHc8o8KATTV=Jqf6-FgtLsqFOQ@xxxxxxxxxxxxxx
> 
>       Just stop [rebasing]. I'll handle the merge issues. If there are
>       complicated merge problems that you really worry about, what you can do
>       is
> 
>        (a) make a test-merge just to check
> 
>        (b) do NOT send me that test-merge
> 
>        (c) as part of the pull request, tell me that "there's a conflict
>       because xyz, and this is how we think it should be handled".


This is largely duplicating the above. This is a good example of why I think we
should consolidate and reference, rather than use lots of quotes.

My comments on the following are similar. These are a great collection of notes,
but I think they need to be converted into concise language to be part of
linux/Documentation

I'd like to hear Jon's thoughts before I spend any more time nit-picking though.

--
Darren

> 
>       ...
> 
>       There are valid reasons to rebase, but those are along the line of "we
>       messed up catastrophically, and we _have_ to clean up the history".
> 
>       A simple merge conflict due to a trivial duplicated commit is not a reason.
> 
>   Linus likes signed tags with a short blurb:
> 
>       http://lkml.kernel.org/r/CA+55aFwa9b5=aYKXNKfCaQN27PFY8GChuhCK+pkrqCfGn6FpKQ@xxxxxxxxxxxxxx
> 
>       .. the above is a tag, but it's not signed, nor even annotated. So it
>       has no message about what the fixes are in it, it's just the plain
>       SHA1 id.
> 
>       Now, I don't really require signed tags from kernel.org, but it would
>       still be nice. And I *do* want a little blurb about the fixes, even if
>       it doesn't have to be all that exhaustive. Putting that in the tag is
>       convenient, but I'm ok with it being just in the email message too,
>       like you usually do.
> 
>   Linus really wants signed tags when pulling from non-kernel.org, even if your
>   key is not (yet) signed by other kernel devs:
> 
>       http://lkml.kernel.org/r/CA+55aFzXUoh6ktJ+wWmwdg6ERjHJWbvrKQ5CoRCy-Sw620Ex+g@xxxxxxxxxxxxxx
> 
>       I really want to see signed tags when pulling from non-kernel.org places.
> 
>       Even if you don't have signatures I can check on your keys, I want to
>       see your key used for signing anyway, so that when your next pull
>       request comes in I see that it's the same key (and hopefully you
>       _will_ have signatures on your key eventually).
> 
>       And: CA+55aFw0f9bojYF4_NGXE7ZgPn4oOoWELBnyJRVRjfX3cuJBag@xxxxxxxxxxxxxx
> 
>   Sending a weekly pull request during the rc period is a good pattern, but
>   more frequent is fine as long as there is a reason:
> 
>       http://lkml.kernel.org/r/CA+55aFwtirweH2pwo9T5=CtrHeEYtLyYtCZXmOOefo3e24tFdA@xxxxxxxxxxxxxx
> 
>       I don't mind small pull requests at all, and I don't see "just one
>       tiny commit" as being a bad thing. Quite the reverse. Those pull
>       requests are easy, and it just makes me feel "good, that subsystem is
>       calm and quiet, but not because the maintainer is not responding to
>       people".
> 
>       In fact, getting small pull requests more often that once a week is
>       also perfectly fine, although at that point there should be some
>       _reason_ for it. But there are lots of valid reasons ("this is urgent
>       because X", but also obviously things like "I maintain five different
>       topic branches, this fourth pull request this week is for that other
>       topic").
> 
>       The thing to avoid is a pattern of lots of pointless small pull
>       requests, and in particular "oh, we found a problem in the last
>       hurried pull requests, so here's _another_ half-arsed hurried pull
>       request to fix that". At that point, I'd much rather just see the
>       maintainer keep the commits in his tree for longer, and test them
>       better, and just let them cook a bit more. So I _will_ complain if I
>       notice that there's commits that are very recent and they look dodgy.
> 
>   And: http://lkml.kernel.org/r/CA+55aFyv0i7x5ZcHK6VnUdkbRtzQPPUxYUm_s1DMoPBqf0n=Mg@xxxxxxxxxxxxxx
> 
>       One pattern that is _very_ clear here is how the pull requests I get
>       are bunched up at the end of the week. More than half of all my pulls
>       were done Friday and particularly Saturday. I'm not complaining, I
>       think it's just a sign of how there weren't any particularly urgent
>       things going on this week, and so people send in their pull requests
>       at the end of the work-week and/or just knowing that the rc is coming
>       up.
> 
> cheers
> 
> 

-- 
Darren Hart
Intel Open Source Technology Center