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Linux/Documentation/SubmittingPatches

  1 
  2         How to Get Your Change Into the Linux Kernel
  3                 or
  4         Care And Operation Of Your Linus Torvalds
  5 
  6 
  7 
  8 For a person or company who wishes to submit a change to the Linux
  9 kernel, the process can sometimes be daunting if you're not familiar
 10 with "the system."  This text is a collection of suggestions which
 11 can greatly increase the chances of your change being accepted.
 12 
 13 Read Documentation/SubmitChecklist for a list of items to check
 14 before submitting code.  If you are submitting a driver, also read
 15 Documentation/SubmittingDrivers.
 16 
 17 Many of these steps describe the default behavior of the git version
 18 control system; if you use git to prepare your patches, you'll find much
 19 of the mechanical work done for you, though you'll still need to prepare
 20 and document a sensible set of patches.
 21 
 22 --------------------------------------------
 23 SECTION 1 - CREATING AND SENDING YOUR CHANGE
 24 --------------------------------------------
 25 
 26 
 27 
 28 1) "diff -up"
 29 ------------
 30 
 31 Use "diff -up" or "diff -uprN" to create patches.  git generates patches
 32 in this form by default; if you're using git, you can skip this section
 33 entirely.
 34 
 35 All changes to the Linux kernel occur in the form of patches, as
 36 generated by diff(1).  When creating your patch, make sure to create it
 37 in "unified diff" format, as supplied by the '-u' argument to diff(1).
 38 Also, please use the '-p' argument which shows which C function each
 39 change is in - that makes the resultant diff a lot easier to read.
 40 Patches should be based in the root kernel source directory,
 41 not in any lower subdirectory.
 42 
 43 To create a patch for a single file, it is often sufficient to do:
 44 
 45         SRCTREE= linux-2.6
 46         MYFILE=  drivers/net/mydriver.c
 47 
 48         cd $SRCTREE
 49         cp $MYFILE $MYFILE.orig
 50         vi $MYFILE      # make your change
 51         cd ..
 52         diff -up $SRCTREE/$MYFILE{.orig,} > /tmp/patch
 53 
 54 To create a patch for multiple files, you should unpack a "vanilla",
 55 or unmodified kernel source tree, and generate a diff against your
 56 own source tree.  For example:
 57 
 58         MYSRC= /devel/linux-2.6
 59 
 60         tar xvfz linux-2.6.12.tar.gz
 61         mv linux-2.6.12 linux-2.6.12-vanilla
 62         diff -uprN -X linux-2.6.12-vanilla/Documentation/dontdiff \
 63                 linux-2.6.12-vanilla $MYSRC > /tmp/patch
 64 
 65 "dontdiff" is a list of files which are generated by the kernel during
 66 the build process, and should be ignored in any diff(1)-generated
 67 patch.  The "dontdiff" file is included in the kernel tree in
 68 2.6.12 and later.
 69 
 70 Make sure your patch does not include any extra files which do not
 71 belong in a patch submission.  Make sure to review your patch -after-
 72 generated it with diff(1), to ensure accuracy.
 73 
 74 If your changes produce a lot of deltas, you need to split them into
 75 individual patches which modify things in logical stages; see section
 76 #3.  This will facilitate easier reviewing by other kernel developers,
 77 very important if you want your patch accepted.
 78 
 79 If you're using git, "git rebase -i" can help you with this process.  If
 80 you're not using git, quilt <http://savannah.nongnu.org/projects/quilt>
 81 is another popular alternative.
 82 
 83 
 84 
 85 2) Describe your changes.
 86 
 87 Describe the technical detail of the change(s) your patch includes.
 88 
 89 Be as specific as possible.  The WORST descriptions possible include
 90 things like "update driver X", "bug fix for driver X", or "this patch
 91 includes updates for subsystem X.  Please apply."
 92 
 93 The maintainer will thank you if you write your patch description in a
 94 form which can be easily pulled into Linux's source code management
 95 system, git, as a "commit log".  See #15, below.
 96 
 97 If your description starts to get long, that's a sign that you probably
 98 need to split up your patch.  See #3, next.
 99 
100 When you submit or resubmit a patch or patch series, include the
101 complete patch description and justification for it.  Don't just
102 say that this is version N of the patch (series).  Don't expect the
103 patch merger to refer back to earlier patch versions or referenced
104 URLs to find the patch description and put that into the patch.
105 I.e., the patch (series) and its description should be self-contained.
106 This benefits both the patch merger(s) and reviewers.  Some reviewers
107 probably didn't even receive earlier versions of the patch.
108 
109 Describe your changes in imperative mood, e.g. "make xyzzy do frotz"
110 instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy
111 to do frotz", as if you are giving orders to the codebase to change
112 its behaviour.
113 
114 If the patch fixes a logged bug entry, refer to that bug entry by
115 number and URL.  If the patch follows from a mailing list discussion,
116 give a URL to the mailing list archive; use the https://lkml.kernel.org/
117 redirector with a Message-Id, to ensure that the links cannot become
118 stale.
119 
120 However, try to make your explanation understandable without external
121 resources.  In addition to giving a URL to a mailing list archive or
122 bug, summarize the relevant points of the discussion that led to the
123 patch as submitted.
124 
125 If you want to refer to a specific commit, don't just refer to the
126 SHA-1 ID of the commit. Please also include the oneline summary of
127 the commit, to make it easier for reviewers to know what it is about.
128 Example:
129 
130         Commit e21d2170f36602ae2708 ("video: remove unnecessary
131         platform_set_drvdata()") removed the unnecessary
132         platform_set_drvdata(), but left the variable "dev" unused,
133         delete it.
134 
135 
136 3) Separate your changes.
137 
138 Separate _logical changes_ into a single patch file.
139 
140 For example, if your changes include both bug fixes and performance
141 enhancements for a single driver, separate those changes into two
142 or more patches.  If your changes include an API update, and a new
143 driver which uses that new API, separate those into two patches.
144 
145 On the other hand, if you make a single change to numerous files,
146 group those changes into a single patch.  Thus a single logical change
147 is contained within a single patch.
148 
149 If one patch depends on another patch in order for a change to be
150 complete, that is OK.  Simply note "this patch depends on patch X"
151 in your patch description.
152 
153 If you cannot condense your patch set into a smaller set of patches,
154 then only post say 15 or so at a time and wait for review and integration.
155 
156 
157 
158 4) Style check your changes.
159 
160 Check your patch for basic style violations, details of which can be
161 found in Documentation/CodingStyle.  Failure to do so simply wastes
162 the reviewers time and will get your patch rejected, probably
163 without even being read.
164 
165 At a minimum you should check your patches with the patch style
166 checker prior to submission (scripts/checkpatch.pl).  You should
167 be able to justify all violations that remain in your patch.
168 
169 
170 
171 5) Select e-mail destination.
172 
173 Look through the MAINTAINERS file and the source code, and determine
174 if your change applies to a specific subsystem of the kernel, with
175 an assigned maintainer.  If so, e-mail that person.  The script
176 scripts/get_maintainer.pl can be very useful at this step.
177 
178 If no maintainer is listed, or the maintainer does not respond, send
179 your patch to the primary Linux kernel developer's mailing list,
180 linux-kernel@vger.kernel.org.  Most kernel developers monitor this
181 e-mail list, and can comment on your changes.
182 
183 
184 Do not send more than 15 patches at once to the vger mailing lists!!!
185 
186 
187 Linus Torvalds is the final arbiter of all changes accepted into the
188 Linux kernel.  His e-mail address is <torvalds@linux-foundation.org>. 
189 He gets a lot of e-mail, so typically you should do your best to -avoid-
190 sending him e-mail. 
191 
192 Patches which are bug fixes, are "obvious" changes, or similarly
193 require little discussion should be sent or CC'd to Linus.  Patches
194 which require discussion or do not have a clear advantage should
195 usually be sent first to linux-kernel.  Only after the patch is
196 discussed should the patch then be submitted to Linus.
197 
198 
199 
200 6) Select your CC (e-mail carbon copy) list.
201 
202 Unless you have a reason NOT to do so, CC linux-kernel@vger.kernel.org.
203 
204 Other kernel developers besides Linus need to be aware of your change,
205 so that they may comment on it and offer code review and suggestions.
206 linux-kernel is the primary Linux kernel developer mailing list.
207 Other mailing lists are available for specific subsystems, such as
208 USB, framebuffer devices, the VFS, the SCSI subsystem, etc.  See the
209 MAINTAINERS file for a mailing list that relates specifically to
210 your change.
211 
212 Majordomo lists of VGER.KERNEL.ORG at:
213         <http://vger.kernel.org/vger-lists.html>
214 
215 If changes affect userland-kernel interfaces, please send
216 the MAN-PAGES maintainer (as listed in the MAINTAINERS file)
217 a man-pages patch, or at least a notification of the change,
218 so that some information makes its way into the manual pages.
219 
220 Even if the maintainer did not respond in step #5, make sure to ALWAYS
221 copy the maintainer when you change their code.
222 
223 For small patches you may want to CC the Trivial Patch Monkey
224 trivial@kernel.org which collects "trivial" patches. Have a look
225 into the MAINTAINERS file for its current manager.
226 Trivial patches must qualify for one of the following rules:
227  Spelling fixes in documentation
228  Spelling fixes which could break grep(1)
229  Warning fixes (cluttering with useless warnings is bad)
230  Compilation fixes (only if they are actually correct)
231  Runtime fixes (only if they actually fix things)
232  Removing use of deprecated functions/macros (eg. check_region)
233  Contact detail and documentation fixes
234  Non-portable code replaced by portable code (even in arch-specific,
235  since people copy, as long as it's trivial)
236  Any fix by the author/maintainer of the file (ie. patch monkey
237  in re-transmission mode)
238 
239 
240 
241 7) No MIME, no links, no compression, no attachments.  Just plain text.
242 
243 Linus and other kernel developers need to be able to read and comment
244 on the changes you are submitting.  It is important for a kernel
245 developer to be able to "quote" your changes, using standard e-mail
246 tools, so that they may comment on specific portions of your code.
247 
248 For this reason, all patches should be submitting e-mail "inline".
249 WARNING:  Be wary of your editor's word-wrap corrupting your patch,
250 if you choose to cut-n-paste your patch.
251 
252 Do not attach the patch as a MIME attachment, compressed or not.
253 Many popular e-mail applications will not always transmit a MIME
254 attachment as plain text, making it impossible to comment on your
255 code.  A MIME attachment also takes Linus a bit more time to process,
256 decreasing the likelihood of your MIME-attached change being accepted.
257 
258 Exception:  If your mailer is mangling patches then someone may ask
259 you to re-send them using MIME.
260 
261 See Documentation/email-clients.txt for hints about configuring
262 your e-mail client so that it sends your patches untouched.
263 
264 8) E-mail size.
265 
266 When sending patches to Linus, always follow step #7.
267 
268 Large changes are not appropriate for mailing lists, and some
269 maintainers.  If your patch, uncompressed, exceeds 300 kB in size,
270 it is preferred that you store your patch on an Internet-accessible
271 server, and provide instead a URL (link) pointing to your patch.
272 
273 
274 
275 9) Name your kernel version.
276 
277 It is important to note, either in the subject line or in the patch
278 description, the kernel version to which this patch applies.
279 
280 If the patch does not apply cleanly to the latest kernel version,
281 Linus will not apply it.
282 
283 
284 
285 10) Don't get discouraged.  Re-submit.
286 
287 After you have submitted your change, be patient and wait.  If Linus
288 likes your change and applies it, it will appear in the next version
289 of the kernel that he releases.
290 
291 However, if your change doesn't appear in the next version of the
292 kernel, there could be any number of reasons.  It's YOUR job to
293 narrow down those reasons, correct what was wrong, and submit your
294 updated change.
295 
296 It is quite common for Linus to "drop" your patch without comment.
297 That's the nature of the system.  If he drops your patch, it could be
298 due to
299 * Your patch did not apply cleanly to the latest kernel version.
300 * Your patch was not sufficiently discussed on linux-kernel.
301 * A style issue (see section 2).
302 * An e-mail formatting issue (re-read this section).
303 * A technical problem with your change.
304 * He gets tons of e-mail, and yours got lost in the shuffle.
305 * You are being annoying.
306 
307 When in doubt, solicit comments on linux-kernel mailing list.
308 
309 
310 
311 11) Include PATCH in the subject
312 
313 Due to high e-mail traffic to Linus, and to linux-kernel, it is common
314 convention to prefix your subject line with [PATCH].  This lets Linus
315 and other kernel developers more easily distinguish patches from other
316 e-mail discussions.
317 
318 
319 
320 12) Sign your work
321 
322 To improve tracking of who did what, especially with patches that can
323 percolate to their final resting place in the kernel through several
324 layers of maintainers, we've introduced a "sign-off" procedure on
325 patches that are being emailed around.
326 
327 The sign-off is a simple line at the end of the explanation for the
328 patch, which certifies that you wrote it or otherwise have the right to
329 pass it on as an open-source patch.  The rules are pretty simple: if you
330 can certify the below:
331 
332         Developer's Certificate of Origin 1.1
333 
334         By making a contribution to this project, I certify that:
335 
336         (a) The contribution was created in whole or in part by me and I
337             have the right to submit it under the open source license
338             indicated in the file; or
339 
340         (b) The contribution is based upon previous work that, to the best
341             of my knowledge, is covered under an appropriate open source
342             license and I have the right under that license to submit that
343             work with modifications, whether created in whole or in part
344             by me, under the same open source license (unless I am
345             permitted to submit under a different license), as indicated
346             in the file; or
347 
348         (c) The contribution was provided directly to me by some other
349             person who certified (a), (b) or (c) and I have not modified
350             it.
351 
352         (d) I understand and agree that this project and the contribution
353             are public and that a record of the contribution (including all
354             personal information I submit with it, including my sign-off) is
355             maintained indefinitely and may be redistributed consistent with
356             this project or the open source license(s) involved.
357 
358 then you just add a line saying
359 
360         Signed-off-by: Random J Developer <random@developer.example.org>
361 
362 using your real name (sorry, no pseudonyms or anonymous contributions.)
363 
364 Some people also put extra tags at the end.  They'll just be ignored for
365 now, but you can do this to mark internal company procedures or just
366 point out some special detail about the sign-off. 
367 
368 If you are a subsystem or branch maintainer, sometimes you need to slightly
369 modify patches you receive in order to merge them, because the code is not
370 exactly the same in your tree and the submitters'. If you stick strictly to
371 rule (c), you should ask the submitter to rediff, but this is a totally
372 counter-productive waste of time and energy. Rule (b) allows you to adjust
373 the code, but then it is very impolite to change one submitter's code and
374 make him endorse your bugs. To solve this problem, it is recommended that
375 you add a line between the last Signed-off-by header and yours, indicating
376 the nature of your changes. While there is nothing mandatory about this, it
377 seems like prepending the description with your mail and/or name, all
378 enclosed in square brackets, is noticeable enough to make it obvious that
379 you are responsible for last-minute changes. Example :
380 
381         Signed-off-by: Random J Developer <random@developer.example.org>
382         [lucky@maintainer.example.org: struct foo moved from foo.c to foo.h]
383         Signed-off-by: Lucky K Maintainer <lucky@maintainer.example.org>
384 
385 This practise is particularly helpful if you maintain a stable branch and
386 want at the same time to credit the author, track changes, merge the fix,
387 and protect the submitter from complaints. Note that under no circumstances
388 can you change the author's identity (the From header), as it is the one
389 which appears in the changelog.
390 
391 Special note to back-porters: It seems to be a common and useful practise
392 to insert an indication of the origin of a patch at the top of the commit
393 message (just after the subject line) to facilitate tracking. For instance,
394 here's what we see in 2.6-stable :
395 
396     Date:   Tue May 13 19:10:30 2008 +0000
397 
398         SCSI: libiscsi regression in 2.6.25: fix nop timer handling
399 
400         commit 4cf1043593db6a337f10e006c23c69e5fc93e722 upstream
401 
402 And here's what appears in 2.4 :
403 
404     Date:   Tue May 13 22:12:27 2008 +0200
405 
406         wireless, airo: waitbusy() won't delay
407 
408         [backport of 2.6 commit b7acbdfbd1f277c1eb23f344f899cfa4cd0bf36a]
409 
410 Whatever the format, this information provides a valuable help to people
411 tracking your trees, and to people trying to trouble-shoot bugs in your
412 tree.
413 
414 
415 13) When to use Acked-by: and Cc:
416 
417 The Signed-off-by: tag indicates that the signer was involved in the
418 development of the patch, or that he/she was in the patch's delivery path.
419 
420 If a person was not directly involved in the preparation or handling of a
421 patch but wishes to signify and record their approval of it then they can
422 arrange to have an Acked-by: line added to the patch's changelog.
423 
424 Acked-by: is often used by the maintainer of the affected code when that
425 maintainer neither contributed to nor forwarded the patch.
426 
427 Acked-by: is not as formal as Signed-off-by:.  It is a record that the acker
428 has at least reviewed the patch and has indicated acceptance.  Hence patch
429 mergers will sometimes manually convert an acker's "yep, looks good to me"
430 into an Acked-by:.
431 
432 Acked-by: does not necessarily indicate acknowledgement of the entire patch.
433 For example, if a patch affects multiple subsystems and has an Acked-by: from
434 one subsystem maintainer then this usually indicates acknowledgement of just
435 the part which affects that maintainer's code.  Judgement should be used here.
436 When in doubt people should refer to the original discussion in the mailing
437 list archives.
438 
439 If a person has had the opportunity to comment on a patch, but has not
440 provided such comments, you may optionally add a "Cc:" tag to the patch.
441 This is the only tag which might be added without an explicit action by the
442 person it names.  This tag documents that potentially interested parties
443 have been included in the discussion
444 
445 
446 14) Using Reported-by:, Tested-by:, Reviewed-by: and Suggested-by:
447 
448 If this patch fixes a problem reported by somebody else, consider adding a
449 Reported-by: tag to credit the reporter for their contribution.  Please
450 note that this tag should not be added without the reporter's permission,
451 especially if the problem was not reported in a public forum.  That said,
452 if we diligently credit our bug reporters, they will, hopefully, be
453 inspired to help us again in the future.
454 
455 A Tested-by: tag indicates that the patch has been successfully tested (in
456 some environment) by the person named.  This tag informs maintainers that
457 some testing has been performed, provides a means to locate testers for
458 future patches, and ensures credit for the testers.
459 
460 Reviewed-by:, instead, indicates that the patch has been reviewed and found
461 acceptable according to the Reviewer's Statement:
462 
463         Reviewer's statement of oversight
464 
465         By offering my Reviewed-by: tag, I state that:
466 
467          (a) I have carried out a technical review of this patch to
468              evaluate its appropriateness and readiness for inclusion into
469              the mainline kernel.
470 
471          (b) Any problems, concerns, or questions relating to the patch
472              have been communicated back to the submitter.  I am satisfied
473              with the submitter's response to my comments.
474 
475          (c) While there may be things that could be improved with this
476              submission, I believe that it is, at this time, (1) a
477              worthwhile modification to the kernel, and (2) free of known
478              issues which would argue against its inclusion.
479 
480          (d) While I have reviewed the patch and believe it to be sound, I
481              do not (unless explicitly stated elsewhere) make any
482              warranties or guarantees that it will achieve its stated
483              purpose or function properly in any given situation.
484 
485 A Reviewed-by tag is a statement of opinion that the patch is an
486 appropriate modification of the kernel without any remaining serious
487 technical issues.  Any interested reviewer (who has done the work) can
488 offer a Reviewed-by tag for a patch.  This tag serves to give credit to
489 reviewers and to inform maintainers of the degree of review which has been
490 done on the patch.  Reviewed-by: tags, when supplied by reviewers known to
491 understand the subject area and to perform thorough reviews, will normally
492 increase the likelihood of your patch getting into the kernel.
493 
494 A Suggested-by: tag indicates that the patch idea is suggested by the person
495 named and ensures credit to the person for the idea. Please note that this
496 tag should not be added without the reporter's permission, especially if the
497 idea was not posted in a public forum. That said, if we diligently credit our
498 idea reporters, they will, hopefully, be inspired to help us again in the
499 future.
500 
501 
502 15) The canonical patch format
503 
504 The canonical patch subject line is:
505 
506     Subject: [PATCH 001/123] subsystem: summary phrase
507 
508 The canonical patch message body contains the following:
509 
510   - A "from" line specifying the patch author.
511 
512   - An empty line.
513 
514   - The body of the explanation, which will be copied to the
515     permanent changelog to describe this patch.
516 
517   - The "Signed-off-by:" lines, described above, which will
518     also go in the changelog.
519 
520   - A marker line containing simply "---".
521 
522   - Any additional comments not suitable for the changelog.
523 
524   - The actual patch (diff output).
525 
526 The Subject line format makes it very easy to sort the emails
527 alphabetically by subject line - pretty much any email reader will
528 support that - since because the sequence number is zero-padded,
529 the numerical and alphabetic sort is the same.
530 
531 The "subsystem" in the email's Subject should identify which
532 area or subsystem of the kernel is being patched.
533 
534 The "summary phrase" in the email's Subject should concisely
535 describe the patch which that email contains.  The "summary
536 phrase" should not be a filename.  Do not use the same "summary
537 phrase" for every patch in a whole patch series (where a "patch
538 series" is an ordered sequence of multiple, related patches).
539 
540 Bear in mind that the "summary phrase" of your email becomes a
541 globally-unique identifier for that patch.  It propagates all the way
542 into the git changelog.  The "summary phrase" may later be used in
543 developer discussions which refer to the patch.  People will want to
544 google for the "summary phrase" to read discussion regarding that
545 patch.  It will also be the only thing that people may quickly see
546 when, two or three months later, they are going through perhaps
547 thousands of patches using tools such as "gitk" or "git log
548 --oneline".
549 
550 For these reasons, the "summary" must be no more than 70-75
551 characters, and it must describe both what the patch changes, as well
552 as why the patch might be necessary.  It is challenging to be both
553 succinct and descriptive, but that is what a well-written summary
554 should do.
555 
556 The "summary phrase" may be prefixed by tags enclosed in square
557 brackets: "Subject: [PATCH tag] <summary phrase>".  The tags are not
558 considered part of the summary phrase, but describe how the patch
559 should be treated.  Common tags might include a version descriptor if
560 the multiple versions of the patch have been sent out in response to
561 comments (i.e., "v1, v2, v3"), or "RFC" to indicate a request for
562 comments.  If there are four patches in a patch series the individual
563 patches may be numbered like this: 1/4, 2/4, 3/4, 4/4.  This assures
564 that developers understand the order in which the patches should be
565 applied and that they have reviewed or applied all of the patches in
566 the patch series.
567 
568 A couple of example Subjects:
569 
570     Subject: [patch 2/5] ext2: improve scalability of bitmap searching
571     Subject: [PATCHv2 001/207] x86: fix eflags tracking
572 
573 The "from" line must be the very first line in the message body,
574 and has the form:
575 
576         From: Original Author <author@example.com>
577 
578 The "from" line specifies who will be credited as the author of the
579 patch in the permanent changelog.  If the "from" line is missing,
580 then the "From:" line from the email header will be used to determine
581 the patch author in the changelog.
582 
583 The explanation body will be committed to the permanent source
584 changelog, so should make sense to a competent reader who has long
585 since forgotten the immediate details of the discussion that might
586 have led to this patch.  Including symptoms of the failure which the
587 patch addresses (kernel log messages, oops messages, etc.) is
588 especially useful for people who might be searching the commit logs
589 looking for the applicable patch.  If a patch fixes a compile failure,
590 it may not be necessary to include _all_ of the compile failures; just
591 enough that it is likely that someone searching for the patch can find
592 it.  As in the "summary phrase", it is important to be both succinct as
593 well as descriptive.
594 
595 The "---" marker line serves the essential purpose of marking for patch
596 handling tools where the changelog message ends.
597 
598 One good use for the additional comments after the "---" marker is for
599 a diffstat, to show what files have changed, and the number of
600 inserted and deleted lines per file.  A diffstat is especially useful
601 on bigger patches.  Other comments relevant only to the moment or the
602 maintainer, not suitable for the permanent changelog, should also go
603 here.  A good example of such comments might be "patch changelogs"
604 which describe what has changed between the v1 and v2 version of the
605 patch.
606 
607 If you are going to include a diffstat after the "---" marker, please
608 use diffstat options "-p 1 -w 70" so that filenames are listed from
609 the top of the kernel source tree and don't use too much horizontal
610 space (easily fit in 80 columns, maybe with some indentation).  (git
611 generates appropriate diffstats by default.)
612 
613 See more details on the proper patch format in the following
614 references.
615 
616 
617 16) Sending "git pull" requests  (from Linus emails)
618 
619 Please write the git repo address and branch name alone on the same line
620 so that I can't even by mistake pull from the wrong branch, and so
621 that a triple-click just selects the whole thing.
622 
623 So the proper format is something along the lines of:
624 
625         "Please pull from
626 
627                 git://jdelvare.pck.nerim.net/jdelvare-2.6 i2c-for-linus
628 
629          to get these changes:"
630 
631 so that I don't have to hunt-and-peck for the address and inevitably
632 get it wrong (actually, I've only gotten it wrong a few times, and
633 checking against the diffstat tells me when I get it wrong, but I'm
634 just a lot more comfortable when I don't have to "look for" the right
635 thing to pull, and double-check that I have the right branch-name).
636 
637 
638 Please use "git diff -M --stat --summary" to generate the diffstat:
639 the -M enables rename detection, and the summary enables a summary of
640 new/deleted or renamed files.
641 
642 With rename detection, the statistics are rather different [...]
643 because git will notice that a fair number of the changes are renames.
644 
645 -----------------------------------
646 SECTION 2 - HINTS, TIPS, AND TRICKS
647 -----------------------------------
648 
649 This section lists many of the common "rules" associated with code
650 submitted to the kernel.  There are always exceptions... but you must
651 have a really good reason for doing so.  You could probably call this
652 section Linus Computer Science 101.
653 
654 
655 
656 1) Read Documentation/CodingStyle
657 
658 Nuff said.  If your code deviates too much from this, it is likely
659 to be rejected without further review, and without comment.
660 
661 One significant exception is when moving code from one file to
662 another -- in this case you should not modify the moved code at all in
663 the same patch which moves it.  This clearly delineates the act of
664 moving the code and your changes.  This greatly aids review of the
665 actual differences and allows tools to better track the history of
666 the code itself.
667 
668 Check your patches with the patch style checker prior to submission
669 (scripts/checkpatch.pl).  The style checker should be viewed as
670 a guide not as the final word.  If your code looks better with
671 a violation then its probably best left alone.
672 
673 The checker reports at three levels:
674  - ERROR: things that are very likely to be wrong
675  - WARNING: things requiring careful review
676  - CHECK: things requiring thought
677 
678 You should be able to justify all violations that remain in your
679 patch.
680 
681 
682 
683 2) #ifdefs are ugly
684 
685 Code cluttered with ifdefs is difficult to read and maintain.  Don't do
686 it.  Instead, put your ifdefs in a header, and conditionally define
687 'static inline' functions, or macros, which are used in the code.
688 Let the compiler optimize away the "no-op" case.
689 
690 Simple example, of poor code:
691 
692         dev = alloc_etherdev (sizeof(struct funky_private));
693         if (!dev)
694                 return -ENODEV;
695         #ifdef CONFIG_NET_FUNKINESS
696         init_funky_net(dev);
697         #endif
698 
699 Cleaned-up example:
700 
701 (in header)
702         #ifndef CONFIG_NET_FUNKINESS
703         static inline void init_funky_net (struct net_device *d) {}
704         #endif
705 
706 (in the code itself)
707         dev = alloc_etherdev (sizeof(struct funky_private));
708         if (!dev)
709                 return -ENODEV;
710         init_funky_net(dev);
711 
712 
713 
714 3) 'static inline' is better than a macro
715 
716 Static inline functions are greatly preferred over macros.
717 They provide type safety, have no length limitations, no formatting
718 limitations, and under gcc they are as cheap as macros.
719 
720 Macros should only be used for cases where a static inline is clearly
721 suboptimal [there are a few, isolated cases of this in fast paths],
722 or where it is impossible to use a static inline function [such as
723 string-izing].
724 
725 'static inline' is preferred over 'static __inline__', 'extern inline',
726 and 'extern __inline__'.
727 
728 
729 
730 4) Don't over-design.
731 
732 Don't try to anticipate nebulous future cases which may or may not
733 be useful:  "Make it as simple as you can, and no simpler."
734 
735 
736 
737 ----------------------
738 SECTION 3 - REFERENCES
739 ----------------------
740 
741 Andrew Morton, "The perfect patch" (tpp).
742   <http://www.ozlabs.org/~akpm/stuff/tpp.txt>
743 
744 Jeff Garzik, "Linux kernel patch submission format".
745   <http://linux.yyz.us/patch-format.html>
746 
747 Greg Kroah-Hartman, "How to piss off a kernel subsystem maintainer".
748   <http://www.kroah.com/log/linux/maintainer.html>
749   <http://www.kroah.com/log/linux/maintainer-02.html>
750   <http://www.kroah.com/log/linux/maintainer-03.html>
751   <http://www.kroah.com/log/linux/maintainer-04.html>
752   <http://www.kroah.com/log/linux/maintainer-05.html>
753 
754 NO!!!! No more huge patch bombs to linux-kernel@vger.kernel.org people!
755   <https://lkml.org/lkml/2005/7/11/336>
756 
757 Kernel Documentation/CodingStyle:
758   <http://users.sosdg.org/~qiyong/lxr/source/Documentation/CodingStyle>
759 
760 Linus Torvalds's mail on the canonical patch format:
761   <http://lkml.org/lkml/2005/4/7/183>
762 
763 Andi Kleen, "On submitting kernel patches"
764   Some strategies to get difficult or controversial changes in.
765   http://halobates.de/on-submitting-patches.pdf
766 
767 --

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