From mboxrd@z Thu Jan 1 00:00:00 1970 From: Darren Hart Subject: Re: [RFC] Any value in having a netdev FAQ? Date: Tue, 16 Jul 2013 13:32:05 -0700 Message-ID: <1374006725.12825.112.camel@envy.home> References: <20130716025954.GC26761@windriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , Greg Kroah-Hartman , netdev@vger.kernel.org To: Paul Gortmaker Return-path: Received: from mga02.intel.com ([134.134.136.20]:31650 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933606Ab3GPUcG (ORCPT ); Tue, 16 Jul 2013 16:32:06 -0400 In-Reply-To: <20130716025954.GC26761@windriver.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2013-07-15 at 22:59 -0400, Paul Gortmaker wrote: > Hi Dave, > > I was wondering if you think there is value in having a netdev-faq type > document available -- perhaps as a vger mailout to new subscribers or > similar? For example, I have lost count of the number of times that you > have had to tell people that net-next is closed during the merge window. > But you would probably be right in telling me that those same people don't > read documentation. Well, that aside, I suppose answering my question > is easier when there is a proposed starting point for content. > > To that end, I've tried to collect a starting point based on repeated > questions/corrections that I've seen over the years. I've added Greg to > the Cc: in order to ensure I've captured the netdev-stable interaction > correctly, and I've thrown Darren under the bus as a random content > reviewer, since he has expressed an interest in documentation recently. And I'm going to learn how to properly interract on netdev while I'm at it. It's a win win :-) > > Below is a possible starting point for content. Many answers I have > written are from memory, long after losing links to netdev threads that > served as evidence for the answers, so apologies in advance if I have > failed to recall correctly the specific details in which you would like > to see things done. > > Thanks, > Paul. > -- > > Information you need to know about netdev > ----------------------------------------- > > Q: What is netdev? > > A: 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/ ) and archives can be found below: > > http://marc.info/?l=linux-netdev > http://www.spinics.net/lists/netdev/ > > Aside from subsystems like that mentioned above, all network related linux > development (i.e. RFC, review, comments, etc) takes place on netdev. > Should LKML be Cc'd? I assume so... > Q: How do the changes posted to netdev make their way into linux? > > A: 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: > > http://git.kernel.org/?p=linux/kernel/git/davem/net.git > http://git.kernel.org/?p=linux/kernel/git/davem/net-next.git > > Q: How often do changes from these trees make it to the mainline Linus tree? > > A: 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 2wk merge window, Best not to abbreviate, we can spare the 3 bytes for " week" :-) > 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. > > IMPORTANT: Do not send new net-next content to netdev during the > period during which net-next tree is closed. It would be handy to have a netdev-next bot that responded to "~/^ \[PATCH/" email (off list) during the merge window with a reminder of this point. Not everyone is active enough in kernel development be always aware of where we are in the cycle. Greg has a bot deal with common mistakes, so there is precedent. > > 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. > > 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 stablilization and bugfixes. > > Finally, the vX.Y gets released, and the whole cycle starts over. > > Q: So where are we now in this cycle? > > A: Load the mainline (Linus) page here: > > http://git.kernel.org/?p=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. > How does one determine if we are in the merge window? I wonder if we could have DEV_CYCLE file in the linux git repository which read: MERGE WINDOW BUG FIX ONLY (-rc1+) CRITICAL FIXES ONLY (-rc4+) That would make it trivial to know from right there in the sources where we are. > Q: How do I indicate which tree (net vs. net-next) my patch should be in? > > A: Firstly, think whether you have a bug fix or new "next-like" content. > Then once decided, assuming that you use git, use the prefix flag, i.e. > > git format-patch --subject-prefix='PATCH net-next' start..finish > > Use "net" instead of "net-next" in the above for bug-fix net content. > If you don't use git, then note the only magic in the above is just > the subject text of the outgoing e-mail, and you can manually change > it yourself with whatever MUA you are comfortable with. > > Q: I sent a patch and I'm wondering what happened to it. How can I tell > whether it got merged? > > A: Start by looking at the main patchworks queue for netdev: > > http://patchwork.ozlabs.org/project/netdev/list/ > > The "State" field will tell you exactly where things are at with > your patch. > > Q: The above only says "Under Review". How can I find out more? > > A: Generally speaking, the patches get triaged quickly (in less than 48h). > So be patient. 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. > > Q: How can I tell what patches are queued up for backporting to the > various stable releases? > > A: Normally Greg Kroah-Hartman collects stable commits himself, but > for networking, Dave collects up patches he deems critical for the > networking subsystem, and then hands them off to Greg. > > There is a patchworks queue that you can see here: > http://patchwork.ozlabs.org/bundle/davem/stable/?state=* > > It contains the patches which Dave has selected, but not yet handed > off to Greg. If Greg already has the patch, then it will be here: > http://git.kernel.org/cgit/linux/kernel/git/stable/stable-queue.git > > A quick way to find whether the patch is in this stable-queue is > to simply clone the repo, and then git grep the mainline commit ID, e.g. > > stable-queue$ git grep -l 284041ef21fdf2e > releases/3.0.84/ipv6-fix-possible-crashes-in-ip6_cork_release.patch > releases/3.4.51/ipv6-fix-possible-crashes-in-ip6_cork_release.patch > releases/3.9.8/ipv6-fix-possible-crashes-in-ip6_cork_release.patch > stable/stable-queue$ > This needs a reference to stable_kernel_rules.txt IMO, and possibly less content here. > Q: I see a network patch and I think it should be backported to stable. > Should I request it via "stable@vger.kernel.org" like the references in > the kernel's Documentation/ directory say? stable_kernel_rules.txt specifically > > A: No, not for networking. Check the stable queues as per above 1st to see > if it is already queued. If not, then send a mail to netdev, listing > the upstream commit ID and why you think it should be a stable candidate. I had no idea as an infrequent contributor to netdev! stable_kernel_rules.txt needs some exceptions noted and a reference to this. > > Before you jump to go do the above, do note that the normal stable rules > in Documentation/stable_kernel_rules.txt still apply. So you need to > explicitly indicate why it is a critical fix and exactly what users are > impacted. In addition, you need to convince yourself that you _really_ > think it has been overlooked, vs. having been considered and rejected. > > Generally speaking, the longer it has had a chance to "soak" in mainline, > the better the odds that it is an OK candidate for stable. So scrambling > to request a commit be added the day after it appears should be avoided. > > Q: I have created a network patch and I think it should be backported to > stable. Should I add a "Cc: stable@vger.kernel.org" like the references > in the kernel's Documentation/ directory say? > > A: No. See above answer. In short, if you think it really belongs in > stable, then ensure you write a decent commit log that describes who > gets impacted by the bugfix and how it manifests itself, and when the > bug was introduced. If you do that properly, then the commit will > get handled appropriately and most likely get put in the patchworks > stable queue if it really warrants it. > > If you think there is some valid information relating to it being in > stable that does _not_ belong in the commit log, then use the three > dash marker line as described in Documentation/SubmittingPatches to > temporarily embed that information into the patch that you send. > > Q: Someone said that the comment style and coding convention is different > for the networing content. Is this true? networking > > A: 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 > */ This is.... unfortunate. I see the warnings from checkpatch.pl and I have to choose between adhering to that or keeping a file which is in complete violation to that consistent. I risk flaming either way. Do we really need different coding styles for different sub directories of the same source tree? I won't say anything more on this or try to argue the point, it isn't my call. Just seems.... strange to me. > > Q: I am working in existing code that has the former comment style and not the > latter. Should I submit new code in the former style or the latter? > > A: Make it the latter style, so that eventually all code in the domain of > netdev is of this format. :-) OK > > Q: I found a bug that might have possible security implications or similar. > Should I mail the main netdev maintainer off-list? > > A: 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 using "security@kernel.org" instead. > > Q: What level of testing is expected before I submit my change? > > A: If your changes are against net-next, then the expectation is that s/then// > you have tested by layering your changes on top of net-next. Ideally > you will have done run-time testing specific to your change, but > at a minimum, your changes should survive an "allyesconfig" and an > "allmodconfig" build without new warnings or failures. > > Q: Any other tips to help ensure my net/net-next patch gets OK'd? > > A: Attention to detail. You can start with checkpatch.pl, but do not > be mindlessly robotic in doing so. Re-read your own work as if you were > the reviewer. 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. This needs a reference to SubmittingPatches This is great Paul, thank you for taking the time. -- Darren Hart Intel Open Source Technology Center Yocto Project - Linux Kernel