docs: netdev: move the netdev-FAQ to the process pages

The documentation for the tip tree is really in quite a similar
spirit to the netdev-FAQ. Move the netdev-FAQ to the process docs
as well.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 285 insertions, 0 deletions

diff --git a/Documentation/process/maintainer-netdev.rst b/Documentation/process/maintainer-netdev.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+.. _netdev-FAQ:
+
+==========
+netdev FAQ
+==========
+
+What is netdev?
+---------------
+It is a mailing list for all network-related Linux stuff.  This
+includes anything found under net/ (i.e. core code like IPv6) and
+drivers/net (i.e. hardware specific drivers) in the Linux source tree.
+
+Note that some subsystems (e.g. wireless drivers) which have a high
+volume of traffic have their own specific mailing lists.
+
+The netdev list is managed (like many other Linux mailing lists) through
+VGER (http://vger.kernel.org/) with archives available at
+https://lore.kernel.org/netdev/
+
+Aside from subsystems like those mentioned above, all network-related
+Linux development (i.e. RFC, review, comments, etc.) takes place on
+netdev.
+
+How do the changes posted to netdev make their way into Linux?
+--------------------------------------------------------------
+There are always two trees (git repositories) in play.  Both are
+driven by David Miller, the main network maintainer.  There is the
+``net`` tree, and the ``net-next`` tree.  As you can probably guess from
+the names, the ``net`` tree is for fixes to existing code already in the
+mainline tree from Linus, and ``net-next`` is where the new code goes
+for the future release.  You can find the trees here:
+
+- https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
+- https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
+
+How do I indicate which tree (net vs. net-next) my patch should be in?
+----------------------------------------------------------------------
+To help maintainers and CI bots you should explicitly mark which tree
+your patch is targeting. Assuming that you use git, use the prefix
+flag::
+
+  git format-patch --subject-prefix='PATCH net-next' start..finish
+
+Use ``net`` instead of ``net-next`` (always lower case) in the above for
+bug-fix ``net`` content.
+
+How often do changes from these trees make it to the mainline Linus tree?
+-------------------------------------------------------------------------
+To understand this, you need to know a bit of background information on
+the cadence of Linux development.  Each new release starts off with a
+two week "merge window" where the main maintainers feed their new stuff
+to Linus for merging into the mainline tree.  After the two weeks, the
+merge window is closed, and it is called/tagged ``-rc1``.  No new
+features get mainlined after this -- only fixes to the rc1 content are
+expected.  After roughly a week of collecting fixes to the rc1 content,
+rc2 is released.  This repeats on a roughly weekly basis until rc7
+(typically; sometimes rc6 if things are quiet, or rc8 if things are in a
+state of churn), and a week after the last vX.Y-rcN was done, the
+official vX.Y is released.
+
+Relating that to netdev: At the beginning of the 2-week merge window,
+the ``net-next`` tree will be closed - no new changes/features.  The
+accumulated new content of the past ~10 weeks will be passed onto
+mainline/Linus via a pull request for vX.Y -- at the same time, the
+``net`` tree will start accumulating fixes for this pulled content
+relating to vX.Y
+
+An announcement indicating when ``net-next`` has been closed is usually
+sent to netdev, but knowing the above, you can predict that in advance.
+
+.. warning::
+  Do not send new ``net-next`` content to netdev during the
+  period during which ``net-next`` tree is closed.
+
+RFC patches sent for review only are obviously welcome at any time
+(use ``--subject-prefix='RFC net-next'`` with ``git format-patch``).
+
+Shortly after the two weeks have passed (and vX.Y-rc1 is released), the
+tree for ``net-next`` reopens to collect content for the next (vX.Y+1)
+release.
+
+If you aren't subscribed to netdev and/or are simply unsure if
+``net-next`` has re-opened yet, simply check the ``net-next`` git
+repository link above for any new networking-related commits.  You may
+also check the following website for the current status:
+
+  http://vger.kernel.org/~davem/net-next.html
+
+The ``net`` tree continues to collect fixes for the vX.Y content, and is
+fed back to Linus at regular (~weekly) intervals.  Meaning that the
+focus for ``net`` is on stabilization and bug fixes.
+
+Finally, the vX.Y gets released, and the whole cycle starts over.
+
+So where are we now in this cycle?
+----------------------------------
+
+Load the mainline (Linus) page here:
+
+  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+
+and note the top of the "tags" section.  If it is rc1, it is early in
+the dev cycle.  If it was tagged rc7 a week ago, then a release is
+probably imminent. If the most recent tag is a final release tag
+(without an ``-rcN`` suffix) - we are most likely in a merge window
+and ``net-next`` is closed.
+
+How can I tell the status of a patch I've sent?
+-----------------------------------------------
+Start by looking at the main patchworks queue for netdev:
+
+  https://patchwork.kernel.org/project/netdevbpf/list/
+
+The "State" field will tell you exactly where things are at with your
+patch. Patches are indexed by the ``Message-ID`` header of the emails
+which carried them so if you have trouble finding your patch append
+the value of ``Message-ID`` to the URL above.
+
+How long before my patch is accepted?
+-------------------------------------
+Generally speaking, the patches get triaged quickly (in less than
+48h). But be patient, if your patch is active in patchwork (i.e. it's
+listed on the project's patch list) the chances it was missed are close to zero.
+Asking the maintainer for status updates on your
+patch is a good way to ensure your patch is ignored or pushed to the
+bottom of the priority list.
+
+Should I directly update patchwork state of my own patches?
+-----------------------------------------------------------
+It may be tempting to help the maintainers and update the state of your
+own patches when you post a new version or spot a bug. Please do not do that.
+Interfering with the patch status on patchwork will only cause confusion. Leave
+it to the maintainer to figure out what is the most recent and current
+version that should be applied. If there is any doubt, the maintainer
+will reply and ask what should be done.
+
+I made changes to only a few patches in a patch series should I resend only those changed?
+------------------------------------------------------------------------------------------
+No, please resend the entire patch series and make sure you do number your
+patches such that it is clear this is the latest and greatest set of patches
+that can be applied.
+
+I have received review feedback, when should I post a revised version of the patches?
+-------------------------------------------------------------------------------------
+Allow at least 24 hours to pass between postings. This will ensure reviewers
+from all geographical locations have a chance to chime in. Do not wait
+too long (weeks) between postings either as it will make it harder for reviewers
+to recall all the context.
+
+Make sure you address all the feedback in your new posting. Do not post a new
+version of the code if the discussion about the previous version is still
+ongoing, unless directly instructed by a reviewer.
+
+I submitted multiple versions of a patch series and it looks like a version other than the last one has been accepted, what should I do?
+----------------------------------------------------------------------------------------------------------------------------------------
+There is no revert possible, once it is pushed out, it stays like that.
+Please send incremental versions on top of what has been merged in order to fix
+the patches the way they would look like if your latest patch series was to be
+merged.
+
+Are there special rules regarding stable submissions on netdev?
+---------------------------------------------------------------
+While it used to be the case that netdev submissions were not supposed
+to carry explicit ``CC: stable@vger.kernel.org`` tags that is no longer
+the case today. Please follow the standard stable rules in
+:ref:`Documentation/process/stable-kernel-rules.rst <stable_kernel_rules>`,
+and make sure you include appropriate Fixes tags!
+
+Is the comment style convention different for the networking content?
+---------------------------------------------------------------------
+Yes, in a largely trivial way.  Instead of this::
+
+  /*
+   * foobar blah blah blah
+   * another line of text
+   */
+
+it is requested that you make it look like this::
+
+  /* foobar blah blah blah
+   * another line of text
+   */
+
+I am working in existing code which uses non-standard formatting. Which formatting should I use?
+------------------------------------------------------------------------------------------------
+Make your code follow the most recent guidelines, so that eventually all code
+in the domain of netdev is in the preferred format.
+
+I found a bug that might have possible security implications or similar. Should I mail the main netdev maintainer off-list?
+---------------------------------------------------------------------------------------------------------------------------
+No. The current netdev maintainer has consistently requested that
+people use the mailing lists and not reach out directly.  If you aren't
+OK with that, then perhaps consider mailing security@kernel.org or
+reading about http://oss-security.openwall.org/wiki/mailing-lists/distros
+as possible alternative mechanisms.
+
+What level of testing is expected before I submit my change?
+------------------------------------------------------------
+At the very minimum your changes must survive an ``allyesconfig`` and an
+``allmodconfig`` build with ``W=1`` set without new warnings or failures.
+
+Ideally you will have done run-time testing specific to your change,
+and the patch series contains a set of kernel selftest for
+``tools/testing/selftests/net`` or using the KUnit framework.
+
+You are expected to test your changes on top of the relevant networking
+tree (``net`` or ``net-next``) and not e.g. a stable tree or ``linux-next``.
+
+How do I post corresponding changes to user space components?
+-------------------------------------------------------------
+User space code exercising kernel features should be posted
+alongside kernel patches. This gives reviewers a chance to see
+how any new interface is used and how well it works.
+
+When user space tools reside in the kernel repo itself all changes
+should generally come as one series. If series becomes too large
+or the user space project is not reviewed on netdev include a link
+to a public repo where user space patches can be seen.
+
+In case user space tooling lives in a separate repository but is
+reviewed on netdev  (e.g. patches to ``iproute2`` tools) kernel and
+user space patches should form separate series (threads) when posted
+to the mailing list, e.g.::
+
+  [PATCH net-next 0/3] net: some feature cover letter
+   └─ [PATCH net-next 1/3] net: some feature prep
+   └─ [PATCH net-next 2/3] net: some feature do it
+   └─ [PATCH net-next 3/3] selftest: net: some feature
+
+  [PATCH iproute2-next] ip: add support for some feature
+
+Posting as one thread is discouraged because it confuses patchwork
+(as of patchwork 2.2.2).
+
+Can I reproduce the checks from patchwork on my local machine?
+--------------------------------------------------------------
+
+Checks in patchwork are mostly simple wrappers around existing kernel
+scripts, the sources are available at:
+
+https://github.com/kuba-moo/nipa/tree/master/tests
+
+Running all the builds and checks locally is a pain, can I post my patches and have the patchwork bot validate them?
+--------------------------------------------------------------------------------------------------------------------
+
+No, you must ensure that your patches are ready by testing them locally
+before posting to the mailing list. The patchwork build bot instance
+gets overloaded very easily and netdev@vger really doesn't need more
+traffic if we can help it.
+
+netdevsim is great, can I extend it for my out-of-tree tests?
+-------------------------------------------------------------
+
+No, ``netdevsim`` is a test vehicle solely for upstream tests.
+(Please add your tests under ``tools/testing/selftests/``.)
+
+We also give no guarantees that ``netdevsim`` won't change in the future
+in a way which would break what would normally be considered uAPI.
+
+Is netdevsim considered a "user" of an API?
+-------------------------------------------
+
+Linux kernel has a long standing rule that no API should be added unless
+it has a real, in-tree user. Mock-ups and tests based on ``netdevsim`` are
+strongly encouraged when adding new APIs, but ``netdevsim`` in itself
+is **not** considered a use case/user.
+
+Any other tips to help ensure my net/net-next patch gets OK'd?
+--------------------------------------------------------------
+Attention to detail.  Re-read your own work as if you were the
+reviewer.  You can start with using ``checkpatch.pl``, perhaps even with
+the ``--strict`` flag.  But do not be mindlessly robotic in doing so.
+If your change is a bug fix, make sure your commit log indicates the
+end-user visible symptom, the underlying reason as to why it happens,
+and then if necessary, explain why the fix proposed is the best way to
+get things done.  Don't mangle whitespace, and as is common, don't
+mis-indent function arguments that span multiple lines.  If it is your
+first patch, mail it to yourself so you can test apply it to an
+unpatched tree to confirm infrastructure didn't mangle it.
+
+Finally, go back and read
+:ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
+to be sure you are not repeating some common mistake documented there.