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netdev-FAQ.txt
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netdev-FAQ.txt
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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.
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 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.
IMPORTANT: Do not send new net-next content to netdev during the
period during which net-next tree is closed.
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.
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 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.
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" (always lower case) 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$
Q: I see a network patch and I think it should be backported to stable.
Should I request it via "[email protected]" like the references in
the kernel's Documentation/stable_kernel_rules.txt file say?
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.
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: [email protected]" 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 networking content. Is this true?
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
*/
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.
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 mailing "[email protected]" or reading about
http://oss-security.openwall.org/wiki/mailing-lists/distros
as possible alternative mechanisms.
Q: What level of testing is expected before I submit my change?
A: If your changes are against net-next, the expectation is that 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. 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 Documentation/SubmittingPatches to be
sure you are not repeating some common mistake documented there.