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

From: Luis R. Rodriguez
Date: Fri Jun 19 2009 - 13:11:07 EST

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:
>> >
>> > Â- It must fix a problem that causes a build error (but not for things
>> > Â Âmarked CONFIG_BROKEN), an oops, a hang, data corruption, a real
>> > Â Âsecurity issue, or some "oh, that's not good" issue. ÂIn short, something
>> > Â Âcritical.
>> 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>
>> ---
>> ÂDocumentation/development-process/2.Process | Â 96 ++++++++++++++++++++++++---
>> ÂDocumentation/stable_kernel_rules.txt    |  Â5 ++
>> Â2 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
>> Âprocesses to keep development happening smoothly. ÂA solid understanding of
>> Âhow 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.

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