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Documentation / networking / netdev-FAQ.txt




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Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.

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.  You may also check the following
68	   website for the current status:
69	
70	        http://vger.kernel.org/~davem/net-next.html
71	
72	   The "net" tree continues to collect fixes for the vX.Y content, and
73	   is fed back to Linus at regular (~weekly) intervals.  Meaning that the
74	   focus for "net" is on stabilization and bugfixes.
75	
76	   Finally, the vX.Y gets released, and the whole cycle starts over.
77	
78	Q: So where are we now in this cycle?
79	
80	A: Load the mainline (Linus) page here:
81	
82		https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
83	
84	   and note the top of the "tags" section.  If it is rc1, it is early
85	   in the dev cycle.  If it was tagged rc7 a week ago, then a release
86	   is probably imminent.
87	
88	Q: How do I indicate which tree (net vs. net-next) my patch should be in?
89	
90	A: Firstly, think whether you have a bug fix or new "next-like" content.
91	   Then once decided, assuming that you use git, use the prefix flag, i.e.
92	
93		git format-patch --subject-prefix='PATCH net-next' start..finish
94	
95	   Use "net" instead of "net-next" (always lower case) in the above for
96	   bug-fix net content.  If you don't use git, then note the only magic in
97	   the above is just the subject text of the outgoing e-mail, and you can
98	   manually change it yourself with whatever MUA you are comfortable with.
99	
100	Q: I sent a patch and I'm wondering what happened to it.  How can I tell
101	   whether it got merged?
102	
103	A: Start by looking at the main patchworks queue for netdev:
104	
105		http://patchwork.ozlabs.org/project/netdev/list/
106	
107	   The "State" field will tell you exactly where things are at with
108	   your patch.
109	
110	Q: The above only says "Under Review".  How can I find out more?
111	
112	A: Generally speaking, the patches get triaged quickly (in less than 48h).
113	   So be patient.  Asking the maintainer for status updates on your
114	   patch is a good way to ensure your patch is ignored or pushed to
115	   the bottom of the priority list.
116	
117	Q: I submitted multiple versions of the patch series, should I directly update
118	   patchwork for the previous versions of these patch series?
119	
120	A: No, please don't interfere with the patch status on patchwork, leave it to
121	   the maintainer to figure out what is the most recent and current version that
122	   should be applied. If there is any doubt, the maintainer will reply and ask
123	   what should be done.
124	
125	Q: How can I tell what patches are queued up for backporting to the
126	   various stable releases?
127	
128	A: Normally Greg Kroah-Hartman collects stable commits himself, but
129	   for networking, Dave collects up patches he deems critical for the
130	   networking subsystem, and then hands them off to Greg.
131	
132	   There is a patchworks queue that you can see here:
133		http://patchwork.ozlabs.org/bundle/davem/stable/?state=*
134	
135	   It contains the patches which Dave has selected, but not yet handed
136	   off to Greg.  If Greg already has the patch, then it will be here:
137		https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git
138	
139	   A quick way to find whether the patch is in this stable-queue is
140	   to simply clone the repo, and then git grep the mainline commit ID, e.g.
141	
142		stable-queue$ git grep -l 284041ef21fdf2e
143		releases/3.0.84/ipv6-fix-possible-crashes-in-ip6_cork_release.patch
144		releases/3.4.51/ipv6-fix-possible-crashes-in-ip6_cork_release.patch
145		releases/3.9.8/ipv6-fix-possible-crashes-in-ip6_cork_release.patch
146		stable/stable-queue$
147	
148	Q: I see a network patch and I think it should be backported to stable.
149	   Should I request it via "stable@vger.kernel.org" like the references in
150	   the kernel's Documentation/process/stable-kernel-rules.rst file say?
151	
152	A: No, not for networking.  Check the stable queues as per above 1st to see
153	   if it is already queued.  If not, then send a mail to netdev, listing
154	   the upstream commit ID and why you think it should be a stable candidate.
155	
156	   Before you jump to go do the above, do note that the normal stable rules
157	   in Documentation/process/stable-kernel-rules.rst still apply.  So you need to
158	   explicitly indicate why it is a critical fix and exactly what users are
159	   impacted.  In addition, you need to convince yourself that you _really_
160	   think it has been overlooked, vs. having been considered and rejected.
161	
162	   Generally speaking, the longer it has had a chance to "soak" in mainline,
163	   the better the odds that it is an OK candidate for stable.  So scrambling
164	   to request a commit be added the day after it appears should be avoided.
165	
166	Q: I have created a network patch and I think it should be backported to
167	   stable.  Should I add a "Cc: stable@vger.kernel.org" like the references
168	   in the kernel's Documentation/ directory say?
169	
170	A: No.  See above answer.  In short, if you think it really belongs in
171	   stable, then ensure you write a decent commit log that describes who
172	   gets impacted by the bugfix and how it manifests itself, and when the
173	   bug was introduced.  If you do that properly, then the commit will
174	   get handled appropriately and most likely get put in the patchworks
175	   stable queue if it really warrants it.
176	
177	   If you think there is some valid information relating to it being in
178	   stable that does _not_ belong in the commit log, then use the three
179	   dash marker line as described in Documentation/process/submitting-patches.rst to
180	   temporarily embed that information into the patch that you send.
181	
182	Q: Someone said that the comment style and coding convention is different
183	   for the networking content.  Is this true?
184	
185	A: Yes, in a largely trivial way.  Instead of this:
186	
187		/*
188		 * foobar blah blah blah
189		 * another line of text
190		 */
191	
192	   it is requested that you make it look like this:
193	
194		/* foobar blah blah blah
195		 * another line of text
196		 */
197	
198	Q: I am working in existing code that has the former comment style and not the
199	   latter.  Should I submit new code in the former style or the latter?
200	
201	A: Make it the latter style, so that eventually all code in the domain of
202	   netdev is of this format.
203	
204	Q: I found a bug that might have possible security implications or similar.
205	   Should I mail the main netdev maintainer off-list?
206	
207	A: No. The current netdev maintainer has consistently requested that people
208	   use the mailing lists and not reach out directly.  If you aren't OK with
209	   that, then perhaps consider mailing "security@kernel.org" or reading about
210	   http://oss-security.openwall.org/wiki/mailing-lists/distros
211	   as possible alternative mechanisms.
212	
213	Q: What level of testing is expected before I submit my change?
214	
215	A: If your changes are against net-next, the expectation is that you
216	   have tested by layering your changes on top of net-next.  Ideally you
217	   will have done run-time testing specific to your change, but at a
218	   minimum, your changes should survive an "allyesconfig" and an
219	   "allmodconfig" build without new warnings or failures.
220	
221	Q: Any other tips to help ensure my net/net-next patch gets OK'd?
222	
223	A: Attention to detail.  Re-read your own work as if you were the
224	   reviewer.  You can start with using checkpatch.pl, perhaps even
225	   with the "--strict" flag.  But do not be mindlessly robotic in
226	   doing so.  If your change is a bug-fix, make sure your commit log
227	   indicates the end-user visible symptom, the underlying reason as
228	   to why it happens, and then if necessary, explain why the fix proposed
229	   is the best way to get things done.   Don't mangle whitespace, and as
230	   is common, don't mis-indent function arguments that span multiple lines.
231	   If it is your first patch, mail it to yourself so you can test apply
232	   it to an unpatched tree to confirm infrastructure didn't mangle it.
233	
234	   Finally, go back and read Documentation/process/submitting-patches.rst to be
235	   sure you are not repeating some common mistake documented there.
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