1.. SPDX-License-Identifier: GPL-2.0 2 3.. _netdev-FAQ: 4 5========== 6netdev FAQ 7========== 8 9What is netdev? 10--------------- 11It is a mailing list for all network-related Linux stuff. This 12includes anything found under net/ (i.e. core code like IPv6) and 13drivers/net (i.e. hardware specific drivers) in the Linux source tree. 14 15Note that some subsystems (e.g. wireless drivers) which have a high 16volume of traffic have their own specific mailing lists. 17 18The netdev list is managed (like many other Linux mailing lists) through 19VGER (http://vger.kernel.org/) with archives available at 20https://lore.kernel.org/netdev/ 21 22Aside from subsystems like those mentioned above, all network-related 23Linux development (i.e. RFC, review, comments, etc.) takes place on 24netdev. 25 26How do the changes posted to netdev make their way into Linux? 27-------------------------------------------------------------- 28There are always two trees (git repositories) in play. Both are 29driven by David Miller, the main network maintainer. There is the 30``net`` tree, and the ``net-next`` tree. As you can probably guess from 31the names, the ``net`` tree is for fixes to existing code already in the 32mainline tree from Linus, and ``net-next`` is where the new code goes 33for the future release. You can find the trees here: 34 35- https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git 36- https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git 37 38How do I indicate which tree (net vs. net-next) my patch should be in? 39---------------------------------------------------------------------- 40To help maintainers and CI bots you should explicitly mark which tree 41your patch is targeting. Assuming that you use git, use the prefix 42flag:: 43 44 git format-patch --subject-prefix='PATCH net-next' start..finish 45 46Use ``net`` instead of ``net-next`` (always lower case) in the above for 47bug-fix ``net`` content. 48 49How often do changes from these trees make it to the mainline Linus tree? 50------------------------------------------------------------------------- 51To understand this, you need to know a bit of background information on 52the cadence of Linux development. Each new release starts off with a 53two week "merge window" where the main maintainers feed their new stuff 54to Linus for merging into the mainline tree. After the two weeks, the 55merge window is closed, and it is called/tagged ``-rc1``. No new 56features get mainlined after this -- only fixes to the rc1 content are 57expected. After roughly a week of collecting fixes to the rc1 content, 58rc2 is released. This repeats on a roughly weekly basis until rc7 59(typically; sometimes rc6 if things are quiet, or rc8 if things are in a 60state of churn), and a week after the last vX.Y-rcN was done, the 61official vX.Y is released. 62 63Relating that to netdev: At the beginning of the 2-week merge window, 64the ``net-next`` tree will be closed - no new changes/features. The 65accumulated new content of the past ~10 weeks will be passed onto 66mainline/Linus via a pull request for vX.Y -- at the same time, the 67``net`` tree will start accumulating fixes for this pulled content 68relating to vX.Y 69 70An announcement indicating when ``net-next`` has been closed is usually 71sent to netdev, but knowing the above, you can predict that in advance. 72 73.. warning:: 74 Do not send new ``net-next`` content to netdev during the 75 period during which ``net-next`` tree is closed. 76 77RFC patches sent for review only are obviously welcome at any time 78(use ``--subject-prefix='RFC net-next'`` with ``git format-patch``). 79 80Shortly after the two weeks have passed (and vX.Y-rc1 is released), the 81tree for ``net-next`` reopens to collect content for the next (vX.Y+1) 82release. 83 84If you aren't subscribed to netdev and/or are simply unsure if 85``net-next`` has re-opened yet, simply check the ``net-next`` git 86repository link above for any new networking-related commits. You may 87also check the following website for the current status: 88 89 http://vger.kernel.org/~davem/net-next.html 90 91The ``net`` tree continues to collect fixes for the vX.Y content, and is 92fed back to Linus at regular (~weekly) intervals. Meaning that the 93focus for ``net`` is on stabilization and bug fixes. 94 95Finally, the vX.Y gets released, and the whole cycle starts over. 96 97So where are we now in this cycle? 98---------------------------------- 99 100Load the mainline (Linus) page here: 101 102 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 103 104and note the top of the "tags" section. If it is rc1, it is early in 105the dev cycle. If it was tagged rc7 a week ago, then a release is 106probably imminent. If the most recent tag is a final release tag 107(without an ``-rcN`` suffix) - we are most likely in a merge window 108and ``net-next`` is closed. 109 110How can I tell the status of a patch I've sent? 111----------------------------------------------- 112Start by looking at the main patchworks queue for netdev: 113 114 https://patchwork.kernel.org/project/netdevbpf/list/ 115 116The "State" field will tell you exactly where things are at with your 117patch. Patches are indexed by the ``Message-ID`` header of the emails 118which carried them so if you have trouble finding your patch append 119the value of ``Message-ID`` to the URL above. 120 121How long before my patch is accepted? 122------------------------------------- 123Generally speaking, the patches get triaged quickly (in less than 12448h). But be patient, if your patch is active in patchwork (i.e. it's 125listed on the project's patch list) the chances it was missed are close to zero. 126Asking the maintainer for status updates on your 127patch is a good way to ensure your patch is ignored or pushed to the 128bottom of the priority list. 129 130Should I directly update patchwork state of my own patches? 131----------------------------------------------------------- 132It may be tempting to help the maintainers and update the state of your 133own patches when you post a new version or spot a bug. Please do not do that. 134Interfering with the patch status on patchwork will only cause confusion. Leave 135it to the maintainer to figure out what is the most recent and current 136version that should be applied. If there is any doubt, the maintainer 137will reply and ask what should be done. 138 139I made changes to only a few patches in a patch series should I resend only those changed? 140------------------------------------------------------------------------------------------ 141No, please resend the entire patch series and make sure you do number your 142patches such that it is clear this is the latest and greatest set of patches 143that can be applied. 144 145I have received review feedback, when should I post a revised version of the patches? 146------------------------------------------------------------------------------------- 147Allow at least 24 hours to pass between postings. This will ensure reviewers 148from all geographical locations have a chance to chime in. Do not wait 149too long (weeks) between postings either as it will make it harder for reviewers 150to recall all the context. 151 152Make sure you address all the feedback in your new posting. Do not post a new 153version of the code if the discussion about the previous version is still 154ongoing, unless directly instructed by a reviewer. 155 156I 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? 157---------------------------------------------------------------------------------------------------------------------------------------- 158There is no revert possible, once it is pushed out, it stays like that. 159Please send incremental versions on top of what has been merged in order to fix 160the patches the way they would look like if your latest patch series was to be 161merged. 162 163Are there special rules regarding stable submissions on netdev? 164--------------------------------------------------------------- 165While it used to be the case that netdev submissions were not supposed 166to carry explicit ``CC: stable@vger.kernel.org`` tags that is no longer 167the case today. Please follow the standard stable rules in 168:ref:`Documentation/process/stable-kernel-rules.rst <stable_kernel_rules>`, 169and make sure you include appropriate Fixes tags! 170 171Is the comment style convention different for the networking content? 172--------------------------------------------------------------------- 173Yes, in a largely trivial way. Instead of this:: 174 175 /* 176 * foobar blah blah blah 177 * another line of text 178 */ 179 180it is requested that you make it look like this:: 181 182 /* foobar blah blah blah 183 * another line of text 184 */ 185 186I am working in existing code which uses non-standard formatting. Which formatting should I use? 187------------------------------------------------------------------------------------------------ 188Make your code follow the most recent guidelines, so that eventually all code 189in the domain of netdev is in the preferred format. 190 191I found a bug that might have possible security implications or similar. Should I mail the main netdev maintainer off-list? 192--------------------------------------------------------------------------------------------------------------------------- 193No. The current netdev maintainer has consistently requested that 194people use the mailing lists and not reach out directly. If you aren't 195OK with that, then perhaps consider mailing security@kernel.org or 196reading about http://oss-security.openwall.org/wiki/mailing-lists/distros 197as possible alternative mechanisms. 198 199What level of testing is expected before I submit my change? 200------------------------------------------------------------ 201At the very minimum your changes must survive an ``allyesconfig`` and an 202``allmodconfig`` build with ``W=1`` set without new warnings or failures. 203 204Ideally you will have done run-time testing specific to your change, 205and the patch series contains a set of kernel selftest for 206``tools/testing/selftests/net`` or using the KUnit framework. 207 208You are expected to test your changes on top of the relevant networking 209tree (``net`` or ``net-next``) and not e.g. a stable tree or ``linux-next``. 210 211How do I post corresponding changes to user space components? 212------------------------------------------------------------- 213User space code exercising kernel features should be posted 214alongside kernel patches. This gives reviewers a chance to see 215how any new interface is used and how well it works. 216 217When user space tools reside in the kernel repo itself all changes 218should generally come as one series. If series becomes too large 219or the user space project is not reviewed on netdev include a link 220to a public repo where user space patches can be seen. 221 222In case user space tooling lives in a separate repository but is 223reviewed on netdev (e.g. patches to ``iproute2`` tools) kernel and 224user space patches should form separate series (threads) when posted 225to the mailing list, e.g.:: 226 227 [PATCH net-next 0/3] net: some feature cover letter 228 └─ [PATCH net-next 1/3] net: some feature prep 229 └─ [PATCH net-next 2/3] net: some feature do it 230 └─ [PATCH net-next 3/3] selftest: net: some feature 231 232 [PATCH iproute2-next] ip: add support for some feature 233 234Posting as one thread is discouraged because it confuses patchwork 235(as of patchwork 2.2.2). 236 237Can I reproduce the checks from patchwork on my local machine? 238-------------------------------------------------------------- 239 240Checks in patchwork are mostly simple wrappers around existing kernel 241scripts, the sources are available at: 242 243https://github.com/kuba-moo/nipa/tree/master/tests 244 245Running all the builds and checks locally is a pain, can I post my patches and have the patchwork bot validate them? 246-------------------------------------------------------------------------------------------------------------------- 247 248No, you must ensure that your patches are ready by testing them locally 249before posting to the mailing list. The patchwork build bot instance 250gets overloaded very easily and netdev@vger really doesn't need more 251traffic if we can help it. 252 253netdevsim is great, can I extend it for my out-of-tree tests? 254------------------------------------------------------------- 255 256No, ``netdevsim`` is a test vehicle solely for upstream tests. 257(Please add your tests under ``tools/testing/selftests/``.) 258 259We also give no guarantees that ``netdevsim`` won't change in the future 260in a way which would break what would normally be considered uAPI. 261 262Is netdevsim considered a "user" of an API? 263------------------------------------------- 264 265Linux kernel has a long standing rule that no API should be added unless 266it has a real, in-tree user. Mock-ups and tests based on ``netdevsim`` are 267strongly encouraged when adding new APIs, but ``netdevsim`` in itself 268is **not** considered a use case/user. 269 270Any other tips to help ensure my net/net-next patch gets OK'd? 271-------------------------------------------------------------- 272Attention to detail. Re-read your own work as if you were the 273reviewer. You can start with using ``checkpatch.pl``, perhaps even with 274the ``--strict`` flag. But do not be mindlessly robotic in doing so. 275If your change is a bug fix, make sure your commit log indicates the 276end-user visible symptom, the underlying reason as to why it happens, 277and then if necessary, explain why the fix proposed is the best way to 278get things done. Don't mangle whitespace, and as is common, don't 279mis-indent function arguments that span multiple lines. If it is your 280first patch, mail it to yourself so you can test apply it to an 281unpatched tree to confirm infrastructure didn't mangle it. 282 283Finally, go back and read 284:ref:`Documentation/process/submitting-patches.rst <submittingpatches>` 285to be sure you are not repeating some common mistake documented there. 286