Re: [RFC] Documentation: add documentation for rc-series and merge window

From: Justin Mattock
Date: Fri Jun 19 2009 - 13:42:27 EST

On Fri, Jun 19, 2009 at 10:10 AM, Luis R.
Rodriguez<lrodriguez@xxxxxxxxxxx> wrote:
> On Fri, Jun 19, 2009 at 8:00 AM, Pavel Machek<pavel@xxxxxx> wrote:
>> On Tue 2009-06-16 11:17:05, Luis R. Rodriguez wrote:
>>> On Tue, Jun 16, 2009 at 02:34:01AM -0700, Jouni Malinen wrote:
>>> > On Mon, Jun 15, 2009 at 09:21:14PM -0700, Luis R. Rodriguez wrote:
>>> >
>>> > > +2.0.2: RC-SERIES RULES
>>> > > +
>>> > > +Rules on what kind of patches are accepted after the merge window closes.
>>> > > +These are patches targeted for the kernel rc-series of a kernel prior
>>> > > +to its release.
>>> > > +
>>> > > + - it must fix a reported regression
>>> > > + - if must fix a reported security hole
>>> > > + - if must fix a reported oops/kernel hang
>>> >
>>> >
>>> > s/if/it/ twice..
>>> Thanks, fixed.
>>> > Is there a good reason for documenting different rules for rc-series and
>>> > -stable releases? These three rules look stricter than the ones
>>> > described in stable_kernel_rules.txt:
>>> >
>>> >  - It must fix a problem that causes a build error (but not for things
>>> >    marked CONFIG_BROKEN), an oops, a hang, data corruption, a real
>>> >    security issue, or some "oh, that's not good" issue.  In short, something
>>> >    critical.
>>> The rc-series rules this patch adds are a summary, so they do indeed appear to be
>>> stricter but I do think new vendor/device ids should be welcomed as well AFAICT,
>>> for instance.
>>> What may be best is to merge these two somehow and refer to the common rules for
>>> both and try to differentiate between them in their respective documentation
>>> section.
>>> But I also think good judgement can be applied, good judgement being defined as
>>> that of a subsystem maintainer, which allows us to simply tell developers to
>>> focus on development and send patches up and the respective maintainer routes
>>> the fixes accordingly.
>>> The spirit of writig this summary is to be clear that rules do exist and that
>>> we cannot simply suggest to read stable_kernel_rules.txt as there are items there
>>> which do not apply.
>>> Reason for trying to add more documentation for this is today there are a lot
>>> companies are working upstream and a better sense of what can get into specific
>>> kernel releases becomes more important and you also have more responsible
>>> developers looking out to ensure their fixes get propagated to the right trees.
>>> So leaving some of these things undocumented, implied or in the dark can turn
>>> out to not be as healthy and IMHO is what lead to the original issue from which
>>> I extracted information to create this summary.
>>> > For example, a fix for data corruption that users can hit relatively
>>> > easily sounds like a good example of something that should really be
>>> > accepted during the rc-phase even if it is not really a regression or
>>> > does not cause a kernel oops/hang.
>>> Agreed.
>>> > "oh, that's not good" issue is somewhat more difficult to comment on,
>>> > but I would expect that there could be some critical issues that really
>>> > would benefit from an exception. What exactly would qualify is something
>>> > that may be not be easily described in a sentence or two, though.
>>> >
>>> >
>>> > The main problem I see with having a very hard line on not allowing
>>> > critical fixes (however that would be defined) during the rc-phase is
>>> > that it will take quite a long time to get the fix eventually out. As an
>>> > example, a driver could have a bug that prevents it from working with
>>> > certain subset of devices, but this is noticed only couple of kernel
>>> > releases after the initial driver merge (e.g., for hardware that was not
>>> > yet available for end users at the time the driver was initially
>>> > submitted).
>>> I believe it makes sense to send fixes for new hardware on an old
>>> driver if it is known the fix cannot regress as it does not affect older
>>> hardware.
>>> > In other words, the issue would not be a regression, not a
>>> > security hole, and not an oops/kernel hang. However, it could make the
>>> > driver unusable to large number of users (once the affected hardware
>>> > model becomes available; say in a new laptop).
>>> Agreed. But I think that would fall under the new driver category.
>>> > If an issue is fixed just before a start of the next merge window the
>>> > patch may not have had enough time to go through the maintainers and end
>>> > up in linux-2.6.git in time before the merge window closes. If it
>>> > weren't now allowed in during the rc-phase, it may not go into a stable
>>> > release either (assuming the rc/stable rules are more or less the same)
>>> > and we would be looking something like five month time until the fix
>>> > would actually be released in a proper kernel release. Sure,
>>> > users/distros could take in some additional patches to fix issues they
>>> > care about, but worst case scenarios of close to half a year to fix an
>>> > issue in a kernel release does not sound quite ideal.
>>> Agreed. In the end it seems to come down to the specifics of the patch and
>>> only the maintainer can really be a good judge of whether it should go in
>>> or not. Of course properly documenting each patch helps, and I believe that
>>> in itself may be good enough to address the grey areas.
>>> Here's a new patch with the fix you noted. Also added a little stub about
>>> maintainers judgement, etc.
>>> From: Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx>
>>> Subject: [PATCH] Documentation: add documentation summary for rc-series and merge window
>>> This is losely based on previous discussions on linux-kernel [1][2].
>>> Lets also refer people reading the stable rules to
>>> Documentation/development-process/.
>>> Also add the number of days it has taken between releases,
>>> and provide the average for the last 10 releases: 86.0 days.
>>> [1]
>>> [2]
>>> Signed-off-by: Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx>
>>> ---
>>>  Documentation/development-process/2.Process |   96 ++++++++++++++++++++++++---
>>>  Documentation/stable_kernel_rules.txt       |    5 ++
>>>  2 files changed, 91 insertions(+), 10 deletions(-)
>>> diff --git a/Documentation/development-process/2.Process b/Documentation/development-process/2.Process
>>> index d750321..c220646 100644
>>> --- a/Documentation/development-process/2.Process
>>> +++ b/Documentation/development-process/2.Process
>>> @@ -7,20 +7,96 @@ course of one year, the kernel has since had to evolve a number of
>>>  processes to keep development happening smoothly.  A solid understanding of
>>>  how the process works is required in order to be an effective part of it.
>>> +2.0:SUMMARY
>>> +
>>> +This section provides a brief summary of the kernel release rules.
>>> +
>>> +
>>> +Stable kernels are released when they are ready! This means there are
>>> +absolutely no strict guidelines for sticking to specific dates for a
>>> +kernel release.
>>> +
>>> +2.0.1: MERGE WINDOW
>>> +
>>> +The merge window opens up after the next stable kernel is released.
>>> +The merge window is when maintainers of different subsystem send pull
>>> +requests to Linus for code they have been queuing up for the next
>>> +stable kernel. This is typically now done through respective
>>> +foo-next-2.6.git trees where foo is your subsystem. Each maintainer
>>> +queues up patches for the next kernel cycle in this foo-next-2.6.git
>>> +tree. After the merge window the kernel is worked on through the
>>> +rc-series of the kernel release. The merge window closes at the first
>>> +rc-series release.
>>> +
>>> +After a maintainer has sent his pull request to Linus during the merge
>>> +window no further new development will be accepted for that tree and
>>> +as such it marks the closure of development for that subsystem for that
>>> +kernel cycle. Developers wishing to target deadlines should simply work
>>> +on their development without regards or consideration for inclusion to
>>> +a specific kernel release. Once development is done it should simply be
>>> +posted. If you insist on targeting a kernel release for deadlines you can
>>> +try to be aware of the current rc cycle development and how soon it seems
>>> +the next stable kernel release will be made. When Linus notes the last rc
>>> +cycle released may be the last -- that is a good sign you should already
>>> +have all your development done and merged in the respective development
>>> +tree. If your code is not ready and merged into the respective maintainers
>>> +tree prior to the announced last potential rc kernel release chances are
>>> +you missed getting your code in for the next kernel merge window.
>>> +Exemptions here are new drivers, covered below.
>>> +
>>> +2.0.2: RC-SERIES RULES
>>> +
>>> +Rules on what kind of patches are accepted after the merge window closes.
>>> +These are patches targeted for the kernel rc-series of a kernel prior
>>> +to its release.
>>> +
>>> + - it must fix a reported regression
>>> + - it must fix a reported security hole
>>> + - it must fix a reported oops/kernel hang
>> - it must fix a bug.
> Well that's for certain, but there is a difference between a general
> notion of a bug and the type of bug fixes that should go in during the
> rc-series. This documentation patch highlights the difference.
>> I do not think the 'reported' requirement is there in -rc,
> Well if its not reported how else would you find out about it during
> the rc-series? And if its something easily triggerable that should
> have been fixed earlier, not late in the rc-series.
>> and yes,
>> compile-fixes etc are welcome.
> Sure, but what are these doing so late in the rc-series?
>> Non-intrusive bugfixes too, afaict.
> It really depends on what you mean but generally no, and this is why I
> think this clarification is important.
>  Luis
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well, this answers my question about merge window
times and, what types of patches belong where.

Justin P. Mattock
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