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diff --git a/Documentation/process/maintainer-netdev.rst b/Documentation/process/maintainer-netdev.rst new file mode 100644 index 000000000..1fa5ab875 --- /dev/null +++ b/Documentation/process/maintainer-netdev.rst @@ -0,0 +1,331 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. _netdev-FAQ: + +========== +netdev FAQ +========== + +tl;dr +----- + + - designate your patch to a tree - ``[PATCH net]`` or ``[PATCH net-next]`` + - for fixes the ``Fixes:`` tag is required, regardless of the tree + - don't post large series (> 15 patches), break them up + - don't repost your patches within one 24h period + - reverse xmas tree + +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. + +How do I divide my work into patches? +------------------------------------- + +Put yourself in the shoes of the reviewer. Each patch is read separately +and therefore should constitute a comprehensible step towards your stated +goal. + +Avoid sending series longer than 15 patches. Larger series takes longer +to review as reviewers will defer looking at it until they find a large +chunk of time. A small series can be reviewed in a short time, so Maintainers +just do it. As a result, a sequence of smaller series gets merged quicker and +with better review coverage. Re-posting large series also increases the mailing +list traffic. + +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 + */ + +What is "reverse xmas tree"? +---------------------------- + +Netdev has a convention for ordering local variables in functions. +Order the variable declaration lines longest to shortest, e.g.:: + + struct scatterlist *sg; + struct sk_buff *skb; + int err, i; + +If there are dependencies between the variables preventing the ordering +move the initialization out of line. + +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. + +My company uses peer feedback in employee performance reviews. Can I ask netdev maintainers for feedback? +--------------------------------------------------------------------------------------------------------- + +Yes, especially if you spend significant amount of time reviewing code +and go out of your way to improve shared infrastructure. + +The feedback must be requested by you, the contributor, and will always +be shared with you (even if you request for it to be submitted to your +manager). |