Documentation/networking/netdev-FAQ.txt

   1
   2 Information you need to know about netdev
   3 -----------------------------------------
   4
   5 Q: What is netdev?
   6
   7 A: It is a mailing list for all network-related Linux stuff.  This includes
   8    anything found under net/  (i.e. core code like IPv6) and drivers/net
   9    (i.e. hardware specific drivers) in the Linux source tree.
  10
  11    Note that some subsystems (e.g. wireless drivers) which have a high volume
  12    of traffic have their own specific mailing lists.
  13
  14    The netdev list is managed (like many other Linux mailing lists) through
  15    VGER ( http://vger.kernel.org/ ) and archives can be found below:
  16
  17         http://marc.info/?l=linux-netdev
  18         http://www.spinics.net/lists/netdev/
  19
  20    Aside from subsystems like that mentioned above, all network-related Linux
  21    development (i.e. RFC, review, comments, etc.) takes place on netdev.
  22
  23 Q: How do the changes posted to netdev make their way into Linux?
  24
  25 A: There are always two trees (git repositories) in play.  Both are driven
  26    by David Miller, the main network maintainer.  There is the "net" tree,
  27    and the "net-next" tree.  As you can probably guess from the names, the
  28    net tree is for fixes to existing code already in the mainline tree from
  29    Linus, and net-next is where the new code goes for the future release.
  30    You can find the trees here:
  31
  32         https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git
  33         https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
  34
  35 Q: How often do changes from these trees make it to the mainline Linus tree?
  36
  37 A: To understand this, you need to know a bit of background information
  38    on the cadence of Linux development.  Each new release starts off with
  39    a two week "merge window" where the main maintainers feed their new
  40    stuff to Linus for merging into the mainline tree.  After the two weeks,
  41    the merge window is closed, and it is called/tagged "-rc1".  No new
  42    features get mainlined after this -- only fixes to the rc1 content
  43    are expected.  After roughly a week of collecting fixes to the rc1
  44    content, rc2 is released.  This repeats on a roughly weekly basis
  45    until rc7 (typically; sometimes rc6 if things are quiet, or rc8 if
  46    things are in a state of churn), and a week after the last vX.Y-rcN
  47    was done, the official "vX.Y" is released.
  48
  49    Relating that to netdev:  At the beginning of the 2-week merge window,
  50    the net-next tree will be closed - no new changes/features.  The
  51    accumulated new content of the past ~10 weeks will be passed onto
  52    mainline/Linus via a pull request for vX.Y -- at the same time,
  53    the "net" tree will start accumulating fixes for this pulled content
  54    relating to vX.Y
  55
  56    An announcement indicating when net-next has been closed is usually
  57    sent to netdev, but knowing the above, you can predict that in advance.
  58
  59    IMPORTANT:  Do not send new net-next content to netdev during the
  60    period during which net-next tree is closed.
  61
  62    Shortly after the two weeks have passed (and vX.Y-rc1 is released), the
  63    tree for net-next reopens to collect content for the next (vX.Y+1) release.
  64
  65    If you aren't subscribed to netdev and/or are simply unsure if net-next
  66    has re-opened yet, simply check the net-next git repository link above for
  67    any new networking-related commits.
  68
  69    The "net" tree continues to collect fixes for the vX.Y content, and
  70    is fed back to Linus at regular (~weekly) intervals.  Meaning that the
  71    focus for "net" is on stabilization and bugfixes.
  72
  73    Finally, the vX.Y gets released, and the whole cycle starts over.
  74
  75 Q: So where are we now in this cycle?
  76
  77 A: Load the mainline (Linus) page here:
  78
  79         https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
  80
  81    and note the top of the "tags" section.  If it is rc1, it is early
  82    in the dev cycle.  If it was tagged rc7 a week ago, then a release
  83    is probably imminent.
  84
  85 Q: How do I indicate which tree (net vs. net-next) my patch should be in?
  86
  87 A: Firstly, think whether you have a bug fix or new "next-like" content.
  88    Then once decided, assuming that you use git, use the prefix flag, i.e.
  89
  90         git format-patch --subject-prefix='PATCH net-next' start..finish
  91
  92    Use "net" instead of "net-next" (always lower case) in the above for
  93    bug-fix net content.  If you don't use git, then note the only magic in
  94    the above is just the subject text of the outgoing e-mail, and you can
  95    manually change it yourself with whatever MUA you are comfortable with.
  96
  97 Q: I sent a patch and I'm wondering what happened to it.  How can I tell
  98    whether it got merged?
  99
 100 A: Start by looking at the main patchworks queue for netdev:
 101
 102         http://patchwork.ozlabs.org/project/netdev/list/
 103
 104    The "State" field will tell you exactly where things are at with
 105    your patch.
 106
 107 Q: The above only says "Under Review".  How can I find out more?
 108
 109 A: Generally speaking, the patches get triaged quickly (in less than 48h).
 110    So be patient.  Asking the maintainer for status updates on your
 111    patch is a good way to ensure your patch is ignored or pushed to
 112    the bottom of the priority list.
 113
 114 Q: I submitted multiple versions of the patch series, should I directly update
 115    patchwork for the previous versions of these patch series?
 116
 117 A: No, please don't interfere with the patch status on patchwork, leave it to
 118    the maintainer to figure out what is the most recent and current version that
 119    should be applied. If there is any doubt, the maintainer will reply and ask
 120    what should be done.
 121
 122 Q: How can I tell what patches are queued up for backporting to the
 123    various stable releases?
 124
 125 A: Normally Greg Kroah-Hartman collects stable commits himself, but
 126    for networking, Dave collects up patches he deems critical for the
 127    networking subsystem, and then hands them off to Greg.
 128
 129    There is a patchworks queue that you can see here:
 130         http://patchwork.ozlabs.org/bundle/davem/stable/?state=*
 131
 132    It contains the patches which Dave has selected, but not yet handed
 133    off to Greg.  If Greg already has the patch, then it will be here:
 134         https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git
 135
 136    A quick way to find whether the patch is in this stable-queue is
 137    to simply clone the repo, and then git grep the mainline commit ID, e.g.
 138
 139         stable-queue$ git grep -l 284041ef21fdf2e
 140         releases/3.0.84/ipv6-fix-possible-crashes-in-ip6_cork_release.patch
 141         releases/3.4.51/ipv6-fix-possible-crashes-in-ip6_cork_release.patch
 142         releases/3.9.8/ipv6-fix-possible-crashes-in-ip6_cork_release.patch
 143         stable/stable-queue$
 144
 145 Q: I see a network patch and I think it should be backported to stable.
 146    Should I request it via "stable@vger.kernel.org" like the references in
 147    the kernel's Documentation/process/stable-kernel-rules.rst file say?
 148
 149 A: No, not for networking.  Check the stable queues as per above 1st to see
 150    if it is already queued.  If not, then send a mail to netdev, listing
 151    the upstream commit ID and why you think it should be a stable candidate.
 152
 153    Before you jump to go do the above, do note that the normal stable rules
 154    in Documentation/process/stable-kernel-rules.rst still apply.  So you need to
 155    explicitly indicate why it is a critical fix and exactly what users are
 156    impacted.  In addition, you need to convince yourself that you _really_
 157    think it has been overlooked, vs. having been considered and rejected.
 158
 159    Generally speaking, the longer it has had a chance to "soak" in mainline,
 160    the better the odds that it is an OK candidate for stable.  So scrambling
 161    to request a commit be added the day after it appears should be avoided.
 162
 163 Q: I have created a network patch and I think it should be backported to
 164    stable.  Should I add a "Cc: stable@vger.kernel.org" like the references
 165    in the kernel's Documentation/ directory say?
 166
 167 A: No.  See above answer.  In short, if you think it really belongs in
 168    stable, then ensure you write a decent commit log that describes who
 169    gets impacted by the bugfix and how it manifests itself, and when the
 170    bug was introduced.  If you do that properly, then the commit will
 171    get handled appropriately and most likely get put in the patchworks
 172    stable queue if it really warrants it.
 173
 174    If you think there is some valid information relating to it being in
 175    stable that does _not_ belong in the commit log, then use the three
 176    dash marker line as described in Documentation/process/submitting-patches.rst to
 177    temporarily embed that information into the patch that you send.
 178
 179 Q: Someone said that the comment style and coding convention is different
 180    for the networking content.  Is this true?
 181
 182 A: Yes, in a largely trivial way.  Instead of this:
 183
 184         /*
 185          * foobar blah blah blah
 186          * another line of text
 187          */
 188
 189    it is requested that you make it look like this:
 190
 191         /* foobar blah blah blah
 192          * another line of text
 193          */
 194
 195 Q: I am working in existing code that has the former comment style and not the
 196    latter.  Should I submit new code in the former style or the latter?
 197
 198 A: Make it the latter style, so that eventually all code in the domain of
 199    netdev is of this format.
 200
 201 Q: I found a bug that might have possible security implications or similar.
 202    Should I mail the main netdev maintainer off-list?
 203
 204 A: No. The current netdev maintainer has consistently requested that people
 205    use the mailing lists and not reach out directly.  If you aren't OK with
 206    that, then perhaps consider mailing "security@kernel.org" or reading about
 207    http://oss-security.openwall.org/wiki/mailing-lists/distros
 208    as possible alternative mechanisms.
 209
 210 Q: What level of testing is expected before I submit my change?
 211
 212 A: If your changes are against net-next, the expectation is that you
 213    have tested by layering your changes on top of net-next.  Ideally you
 214    will have done run-time testing specific to your change, but at a
 215    minimum, your changes should survive an "allyesconfig" and an
 216    "allmodconfig" build without new warnings or failures.
 217
 218 Q: Any other tips to help ensure my net/net-next patch gets OK'd?
 219
 220 A: Attention to detail.  Re-read your own work as if you were the
 221    reviewer.  You can start with using checkpatch.pl, perhaps even
 222    with the "--strict" flag.  But do not be mindlessly robotic in
 223    doing so.  If your change is a bug-fix, make sure your commit log
 224    indicates the end-user visible symptom, the underlying reason as
 225    to why it happens, and then if necessary, explain why the fix proposed
 226    is the best way to get things done.   Don't mangle whitespace, and as
 227    is common, don't mis-indent function arguments that span multiple lines.
 228    If it is your first patch, mail it to yourself so you can test apply
 229    it to an unpatched tree to confirm infrastructure didn't mangle it.
 230
 231    Finally, go back and read Documentation/process/submitting-patches.rst to be
 232    sure you are not repeating some common mistake documented there.