Based on kernel version 2.6.33. Page generated on 2010-02-24 15:37 EST.
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 18 19 -------------------------------------------- 20 SECTION 1 - CREATING AND SENDING YOUR CHANGE 21 -------------------------------------------- 22 23 24 25 1) "diff -up" 26 ------------ 27 28 Use "diff -up" or "diff -uprN" to create patches. 29 30 All changes to the Linux kernel occur in the form of patches, as 31 generated by diff(1). When creating your patch, make sure to create it 32 in "unified diff" format, as supplied by the '-u' argument to diff(1). 33 Also, please use the '-p' argument which shows which C function each 34 change is in - that makes the resultant diff a lot easier to read. 35 Patches should be based in the root kernel source directory, 36 not in any lower subdirectory. 37 38 To create a patch for a single file, it is often sufficient to do: 39 40 SRCTREE= linux-2.6 41 MYFILE= drivers/net/mydriver.c 42 43 cd $SRCTREE 44 cp $MYFILE $MYFILE.orig 45 vi $MYFILE # make your change 46 cd .. 47 diff -up $SRCTREE/$MYFILE{.orig,} > /tmp/patch 48 49 To create a patch for multiple files, you should unpack a "vanilla", 50 or unmodified kernel source tree, and generate a diff against your 51 own source tree. For example: 52 53 MYSRC= /devel/linux-2.6 54 55 tar xvfz linux-2.6.12.tar.gz 56 mv linux-2.6.12 linux-2.6.12-vanilla 57 diff -uprN -X linux-2.6.12-vanilla/Documentation/dontdiff \ 58 linux-2.6.12-vanilla $MYSRC > /tmp/patch 59 60 "dontdiff" is a list of files which are generated by the kernel during 61 the build process, and should be ignored in any diff(1)-generated 62 patch. The "dontdiff" file is included in the kernel tree in 63 2.6.12 and later. For earlier kernel versions, you can get it 64 from <http://www.xenotime.net/linux/doc/dontdiff>. 65 66 Make sure your patch does not include any extra files which do not 67 belong in a patch submission. Make sure to review your patch -after- 68 generated it with diff(1), to ensure accuracy. 69 70 If your changes produce a lot of deltas, you may want to look into 71 splitting them into individual patches which modify things in 72 logical stages. This will facilitate easier reviewing by other 73 kernel developers, very important if you want your patch accepted. 74 There are a number of scripts which can aid in this: 75 76 Quilt: 77 http://savannah.nongnu.org/projects/quilt 78 79 Andrew Morton's patch scripts: 80 http://userweb.kernel.org/~akpm/stuff/patch-scripts.tar.gz 81 Instead of these scripts, quilt is the recommended patch management 82 tool (see above). 83 84 85 86 2) Describe your changes. 87 88 Describe the technical detail of the change(s) your patch includes. 89 90 Be as specific as possible. The WORST descriptions possible include 91 things like "update driver X", "bug fix for driver X", or "this patch 92 includes updates for subsystem X. Please apply." 93 94 The maintainer will thank you if you write your patch description in a 95 form which can be easily pulled into Linux's source code management 96 system, git, as a "commit log". See #15, below. 97 98 If your description starts to get long, that's a sign that you probably 99 need to split up your patch. See #3, next. 100 101 102 103 3) Separate your changes. 104 105 Separate _logical changes_ into a single patch file. 106 107 For example, if your changes include both bug fixes and performance 108 enhancements for a single driver, separate those changes into two 109 or more patches. If your changes include an API update, and a new 110 driver which uses that new API, separate those into two patches. 111 112 On the other hand, if you make a single change to numerous files, 113 group those changes into a single patch. Thus a single logical change 114 is contained within a single patch. 115 116 If one patch depends on another patch in order for a change to be 117 complete, that is OK. Simply note "this patch depends on patch X" 118 in your patch description. 119 120 If you cannot condense your patch set into a smaller set of patches, 121 then only post say 15 or so at a time and wait for review and integration. 122 123 124 125 4) Style check your changes. 126 127 Check your patch for basic style violations, details of which can be 128 found in Documentation/CodingStyle. Failure to do so simply wastes 129 the reviewers time and will get your patch rejected, probably 130 without even being read. 131 132 At a minimum you should check your patches with the patch style 133 checker prior to submission (scripts/checkpatch.pl). You should 134 be able to justify all violations that remain in your patch. 135 136 137 138 5) Select e-mail destination. 139 140 Look through the MAINTAINERS file and the source code, and determine 141 if your change applies to a specific subsystem of the kernel, with 142 an assigned maintainer. If so, e-mail that person. 143 144 If no maintainer is listed, or the maintainer does not respond, send 145 your patch to the primary Linux kernel developer's mailing list, 146 linux-kernel[AT]vger.kernel.org[DOT] Most kernel developers monitor this 147 e-mail list, and can comment on your changes. 148 149 150 Do not send more than 15 patches at once to the vger mailing lists!!! 151 152 153 Linus Torvalds is the final arbiter of all changes accepted into the 154 Linux kernel. His e-mail address is <torvalds[AT]linux-foundation.org>[DOT] 155 He gets a lot of e-mail, so typically you should do your best to -avoid- 156 sending him e-mail. 157 158 Patches which are bug fixes, are "obvious" changes, or similarly 159 require little discussion should be sent or CC'd to Linus. Patches 160 which require discussion or do not have a clear advantage should 161 usually be sent first to linux-kernel. Only after the patch is 162 discussed should the patch then be submitted to Linus. 163 164 165 166 6) Select your CC (e-mail carbon copy) list. 167 168 Unless you have a reason NOT to do so, CC linux-kernel[AT]vger.kernel.org[DOT] 169 170 Other kernel developers besides Linus need to be aware of your change, 171 so that they may comment on it and offer code review and suggestions. 172 linux-kernel is the primary Linux kernel developer mailing list. 173 Other mailing lists are available for specific subsystems, such as 174 USB, framebuffer devices, the VFS, the SCSI subsystem, etc. See the 175 MAINTAINERS file for a mailing list that relates specifically to 176 your change. 177 178 Majordomo lists of VGER.KERNEL.ORG at: 179 <http://vger.kernel.org/vger-lists.html> 180 181 If changes affect userland-kernel interfaces, please send 182 the MAN-PAGES maintainer (as listed in the MAINTAINERS file) 183 a man-pages patch, or at least a notification of the change, 184 so that some information makes its way into the manual pages. 185 186 Even if the maintainer did not respond in step #5, make sure to ALWAYS 187 copy the maintainer when you change their code. 188 189 For small patches you may want to CC the Trivial Patch Monkey 190 trivial[AT]kernel.org which collects "trivial" patches[DOT] Have a look 191 into the MAINTAINERS file for its current manager. 192 Trivial patches must qualify for one of the following rules: 193 Spelling fixes in documentation 194 Spelling fixes which could break grep(1) 195 Warning fixes (cluttering with useless warnings is bad) 196 Compilation fixes (only if they are actually correct) 197 Runtime fixes (only if they actually fix things) 198 Removing use of deprecated functions/macros (eg. check_region) 199 Contact detail and documentation fixes 200 Non-portable code replaced by portable code (even in arch-specific, 201 since people copy, as long as it's trivial) 202 Any fix by the author/maintainer of the file (ie. patch monkey 203 in re-transmission mode) 204 205 206 207 7) No MIME, no links, no compression, no attachments. Just plain text. 208 209 Linus and other kernel developers need to be able to read and comment 210 on the changes you are submitting. It is important for a kernel 211 developer to be able to "quote" your changes, using standard e-mail 212 tools, so that they may comment on specific portions of your code. 213 214 For this reason, all patches should be submitting e-mail "inline". 215 WARNING: Be wary of your editor's word-wrap corrupting your patch, 216 if you choose to cut-n-paste your patch. 217 218 Do not attach the patch as a MIME attachment, compressed or not. 219 Many popular e-mail applications will not always transmit a MIME 220 attachment as plain text, making it impossible to comment on your 221 code. A MIME attachment also takes Linus a bit more time to process, 222 decreasing the likelihood of your MIME-attached change being accepted. 223 224 Exception: If your mailer is mangling patches then someone may ask 225 you to re-send them using MIME. 226 227 See Documentation/email-clients.txt for hints about configuring 228 your e-mail client so that it sends your patches untouched. 229 230 8) E-mail size. 231 232 When sending patches to Linus, always follow step #7. 233 234 Large changes are not appropriate for mailing lists, and some 235 maintainers. If your patch, uncompressed, exceeds 300 kB in size, 236 it is preferred that you store your patch on an Internet-accessible 237 server, and provide instead a URL (link) pointing to your patch. 238 239 240 241 9) Name your kernel version. 242 243 It is important to note, either in the subject line or in the patch 244 description, the kernel version to which this patch applies. 245 246 If the patch does not apply cleanly to the latest kernel version, 247 Linus will not apply it. 248 249 250 251 10) Don't get discouraged. Re-submit. 252 253 After you have submitted your change, be patient and wait. If Linus 254 likes your change and applies it, it will appear in the next version 255 of the kernel that he releases. 256 257 However, if your change doesn't appear in the next version of the 258 kernel, there could be any number of reasons. It's YOUR job to 259 narrow down those reasons, correct what was wrong, and submit your 260 updated change. 261 262 It is quite common for Linus to "drop" your patch without comment. 263 That's the nature of the system. If he drops your patch, it could be 264 due to 265 * Your patch did not apply cleanly to the latest kernel version. 266 * Your patch was not sufficiently discussed on linux-kernel. 267 * A style issue (see section 2). 268 * An e-mail formatting issue (re-read this section). 269 * A technical problem with your change. 270 * He gets tons of e-mail, and yours got lost in the shuffle. 271 * You are being annoying. 272 273 When in doubt, solicit comments on linux-kernel mailing list. 274 275 276 277 11) Include PATCH in the subject 278 279 Due to high e-mail traffic to Linus, and to linux-kernel, it is common 280 convention to prefix your subject line with [PATCH]. This lets Linus 281 and other kernel developers more easily distinguish patches from other 282 e-mail discussions. 283 284 285 286 12) Sign your work 287 288 To improve tracking of who did what, especially with patches that can 289 percolate to their final resting place in the kernel through several 290 layers of maintainers, we've introduced a "sign-off" procedure on 291 patches that are being emailed around. 292 293 The sign-off is a simple line at the end of the explanation for the 294 patch, which certifies that you wrote it or otherwise have the right to 295 pass it on as a open-source patch. The rules are pretty simple: if you 296 can certify the below: 297 298 Developer's Certificate of Origin 1.1 299 300 By making a contribution to this project, I certify that: 301 302 (a) The contribution was created in whole or in part by me and I 303 have the right to submit it under the open source license 304 indicated in the file; or 305 306 (b) The contribution is based upon previous work that, to the best 307 of my knowledge, is covered under an appropriate open source 308 license and I have the right under that license to submit that 309 work with modifications, whether created in whole or in part 310 by me, under the same open source license (unless I am 311 permitted to submit under a different license), as indicated 312 in the file; or 313 314 (c) The contribution was provided directly to me by some other 315 person who certified (a), (b) or (c) and I have not modified 316 it. 317 318 (d) I understand and agree that this project and the contribution 319 are public and that a record of the contribution (including all 320 personal information I submit with it, including my sign-off) is 321 maintained indefinitely and may be redistributed consistent with 322 this project or the open source license(s) involved. 323 324 then you just add a line saying 325 326 Signed-off-by: Random J Developer <random[AT]developer.example[DOT]org> 327 328 using your real name (sorry, no pseudonyms or anonymous contributions.) 329 330 Some people also put extra tags at the end. They'll just be ignored for 331 now, but you can do this to mark internal company procedures or just 332 point out some special detail about the sign-off. 333 334 If you are a subsystem or branch maintainer, sometimes you need to slightly 335 modify patches you receive in order to merge them, because the code is not 336 exactly the same in your tree and the submitters'. If you stick strictly to 337 rule (c), you should ask the submitter to rediff, but this is a totally 338 counter-productive waste of time and energy. Rule (b) allows you to adjust 339 the code, but then it is very impolite to change one submitter's code and 340 make him endorse your bugs. To solve this problem, it is recommended that 341 you add a line between the last Signed-off-by header and yours, indicating 342 the nature of your changes. While there is nothing mandatory about this, it 343 seems like prepending the description with your mail and/or name, all 344 enclosed in square brackets, is noticeable enough to make it obvious that 345 you are responsible for last-minute changes. Example : 346 347 Signed-off-by: Random J Developer <random[AT]developer.example[DOT]org> 348 [lucky[AT]maintainer.example.org: struct foo moved from foo.c to foo[DOT]h] 349 Signed-off-by: Lucky K Maintainer <lucky[AT]maintainer.example[DOT]org> 350 351 This practise is particularly helpful if you maintain a stable branch and 352 want at the same time to credit the author, track changes, merge the fix, 353 and protect the submitter from complaints. Note that under no circumstances 354 can you change the author's identity (the From header), as it is the one 355 which appears in the changelog. 356 357 Special note to back-porters: It seems to be a common and useful practise 358 to insert an indication of the origin of a patch at the top of the commit 359 message (just after the subject line) to facilitate tracking. For instance, 360 here's what we see in 2.6-stable : 361 362 Date: Tue May 13 19:10:30 2008 +0000 363 364 SCSI: libiscsi regression in 2.6.25: fix nop timer handling 365 366 commit 4cf1043593db6a337f10e006c23c69e5fc93e722 upstream 367 368 And here's what appears in 2.4 : 369 370 Date: Tue May 13 22:12:27 2008 +0200 371 372 wireless, airo: waitbusy() won't delay 373 374 [backport of 2.6 commit b7acbdfbd1f277c1eb23f344f899cfa4cd0bf36a] 375 376 Whatever the format, this information provides a valuable help to people 377 tracking your trees, and to people trying to trouble-shoot bugs in your 378 tree. 379 380 381 13) When to use Acked-by: and Cc: 382 383 The Signed-off-by: tag indicates that the signer was involved in the 384 development of the patch, or that he/she was in the patch's delivery path. 385 386 If a person was not directly involved in the preparation or handling of a 387 patch but wishes to signify and record their approval of it then they can 388 arrange to have an Acked-by: line added to the patch's changelog. 389 390 Acked-by: is often used by the maintainer of the affected code when that 391 maintainer neither contributed to nor forwarded the patch. 392 393 Acked-by: is not as formal as Signed-off-by:. It is a record that the acker 394 has at least reviewed the patch and has indicated acceptance. Hence patch 395 mergers will sometimes manually convert an acker's "yep, looks good to me" 396 into an Acked-by:. 397 398 Acked-by: does not necessarily indicate acknowledgement of the entire patch. 399 For example, if a patch affects multiple subsystems and has an Acked-by: from 400 one subsystem maintainer then this usually indicates acknowledgement of just 401 the part which affects that maintainer's code. Judgement should be used here. 402 When in doubt people should refer to the original discussion in the mailing 403 list archives. 404 405 If a person has had the opportunity to comment on a patch, but has not 406 provided such comments, you may optionally add a "Cc:" tag to the patch. 407 This is the only tag which might be added without an explicit action by the 408 person it names. This tag documents that potentially interested parties 409 have been included in the discussion 410 411 412 14) Using Reported-by:, Tested-by: and Reviewed-by: 413 414 If this patch fixes a problem reported by somebody else, consider adding a 415 Reported-by: tag to credit the reporter for their contribution. Please 416 note that this tag should not be added without the reporter's permission, 417 especially if the problem was not reported in a public forum. That said, 418 if we diligently credit our bug reporters, they will, hopefully, be 419 inspired to help us again in the future. 420 421 A Tested-by: tag indicates that the patch has been successfully tested (in 422 some environment) by the person named. This tag informs maintainers that 423 some testing has been performed, provides a means to locate testers for 424 future patches, and ensures credit for the testers. 425 426 Reviewed-by:, instead, indicates that the patch has been reviewed and found 427 acceptable according to the Reviewer's Statement: 428 429 Reviewer's statement of oversight 430 431 By offering my Reviewed-by: tag, I state that: 432 433 (a) I have carried out a technical review of this patch to 434 evaluate its appropriateness and readiness for inclusion into 435 the mainline kernel. 436 437 (b) Any problems, concerns, or questions relating to the patch 438 have been communicated back to the submitter. I am satisfied 439 with the submitter's response to my comments. 440 441 (c) While there may be things that could be improved with this 442 submission, I believe that it is, at this time, (1) a 443 worthwhile modification to the kernel, and (2) free of known 444 issues which would argue against its inclusion. 445 446 (d) While I have reviewed the patch and believe it to be sound, I 447 do not (unless explicitly stated elsewhere) make any 448 warranties or guarantees that it will achieve its stated 449 purpose or function properly in any given situation. 450 451 A Reviewed-by tag is a statement of opinion that the patch is an 452 appropriate modification of the kernel without any remaining serious 453 technical issues. Any interested reviewer (who has done the work) can 454 offer a Reviewed-by tag for a patch. This tag serves to give credit to 455 reviewers and to inform maintainers of the degree of review which has been 456 done on the patch. Reviewed-by: tags, when supplied by reviewers known to 457 understand the subject area and to perform thorough reviews, will normally 458 increase the likelihood of your patch getting into the kernel. 459 460 461 15) The canonical patch format 462 463 The canonical patch subject line is: 464 465 Subject: [PATCH 001/123] subsystem: summary phrase 466 467 The canonical patch message body contains the following: 468 469 - A "from" line specifying the patch author. 470 471 - An empty line. 472 473 - The body of the explanation, which will be copied to the 474 permanent changelog to describe this patch. 475 476 - The "Signed-off-by:" lines, described above, which will 477 also go in the changelog. 478 479 - A marker line containing simply "---". 480 481 - Any additional comments not suitable for the changelog. 482 483 - The actual patch (diff output). 484 485 The Subject line format makes it very easy to sort the emails 486 alphabetically by subject line - pretty much any email reader will 487 support that - since because the sequence number is zero-padded, 488 the numerical and alphabetic sort is the same. 489 490 The "subsystem" in the email's Subject should identify which 491 area or subsystem of the kernel is being patched. 492 493 The "summary phrase" in the email's Subject should concisely 494 describe the patch which that email contains. The "summary 495 phrase" should not be a filename. Do not use the same "summary 496 phrase" for every patch in a whole patch series (where a "patch 497 series" is an ordered sequence of multiple, related patches). 498 499 Bear in mind that the "summary phrase" of your email becomes a 500 globally-unique identifier for that patch. It propagates all the way 501 into the git changelog. The "summary phrase" may later be used in 502 developer discussions which refer to the patch. People will want to 503 google for the "summary phrase" to read discussion regarding that 504 patch. It will also be the only thing that people may quickly see 505 when, two or three months later, they are going through perhaps 506 thousands of patches using tools such as "gitk" or "git log 507 --oneline". 508 509 For these reasons, the "summary" must be no more than 70-75 510 characters, and it must describe both what the patch changes, as well 511 as why the patch might be necessary. It is challenging to be both 512 succinct and descriptive, but that is what a well-written summary 513 should do. 514 515 The "summary phrase" may be prefixed by tags enclosed in square 516 brackets: "Subject: [PATCH tag] <summary phrase>". The tags are not 517 considered part of the summary phrase, but describe how the patch 518 should be treated. Common tags might include a version descriptor if 519 the multiple versions of the patch have been sent out in response to 520 comments (i.e., "v1, v2, v3"), or "RFC" to indicate a request for 521 comments. If there are four patches in a patch series the individual 522 patches may be numbered like this: 1/4, 2/4, 3/4, 4/4. This assures 523 that developers understand the order in which the patches should be 524 applied and that they have reviewed or applied all of the patches in 525 the patch series. 526 527 A couple of example Subjects: 528 529 Subject: [patch 2/5] ext2: improve scalability of bitmap searching 530 Subject: [PATCHv2 001/207] x86: fix eflags tracking 531 532 The "from" line must be the very first line in the message body, 533 and has the form: 534 535 From: Original Author <author[AT]example[DOT]com> 536 537 The "from" line specifies who will be credited as the author of the 538 patch in the permanent changelog. If the "from" line is missing, 539 then the "From:" line from the email header will be used to determine 540 the patch author in the changelog. 541 542 The explanation body will be committed to the permanent source 543 changelog, so should make sense to a competent reader who has long 544 since forgotten the immediate details of the discussion that might 545 have led to this patch. Including symptoms of the failure which the 546 patch addresses (kernel log messages, oops messages, etc.) is 547 especially useful for people who might be searching the commit logs 548 looking for the applicable patch. If a patch fixes a compile failure, 549 it may not be necessary to include _all_ of the compile failures; just 550 enough that it is likely that someone searching for the patch can find 551 it. As in the "summary phrase", it is important to be both succinct as 552 well as descriptive. 553 554 The "---" marker line serves the essential purpose of marking for patch 555 handling tools where the changelog message ends. 556 557 One good use for the additional comments after the "---" marker is for 558 a diffstat, to show what files have changed, and the number of 559 inserted and deleted lines per file. A diffstat is especially useful 560 on bigger patches. Other comments relevant only to the moment or the 561 maintainer, not suitable for the permanent changelog, should also go 562 here. A good example of such comments might be "patch changelogs" 563 which describe what has changed between the v1 and v2 version of the 564 patch. 565 566 If you are going to include a diffstat after the "---" marker, please 567 use diffstat options "-p 1 -w 70" so that filenames are listed from 568 the top of the kernel source tree and don't use too much horizontal 569 space (easily fit in 80 columns, maybe with some indentation). 570 571 See more details on the proper patch format in the following 572 references. 573 574 575 16) Sending "git pull" requests (from Linus emails) 576 577 Please write the git repo address and branch name alone on the same line 578 so that I can't even by mistake pull from the wrong branch, and so 579 that a triple-click just selects the whole thing. 580 581 So the proper format is something along the lines of: 582 583 "Please pull from 584 585 git://jdelvare.pck.nerim.net/jdelvare-2.6 i2c-for-linus 586 587 to get these changes:" 588 589 so that I don't have to hunt-and-peck for the address and inevitably 590 get it wrong (actually, I've only gotten it wrong a few times, and 591 checking against the diffstat tells me when I get it wrong, but I'm 592 just a lot more comfortable when I don't have to "look for" the right 593 thing to pull, and double-check that I have the right branch-name). 594 595 596 Please use "git diff -M --stat --summary" to generate the diffstat: 597 the -M enables rename detection, and the summary enables a summary of 598 new/deleted or renamed files. 599 600 With rename detection, the statistics are rather different [...] 601 because git will notice that a fair number of the changes are renames. 602 603 ----------------------------------- 604 SECTION 2 - HINTS, TIPS, AND TRICKS 605 ----------------------------------- 606 607 This section lists many of the common "rules" associated with code 608 submitted to the kernel. There are always exceptions... but you must 609 have a really good reason for doing so. You could probably call this 610 section Linus Computer Science 101. 611 612 613 614 1) Read Documentation/CodingStyle 615 616 Nuff said. If your code deviates too much from this, it is likely 617 to be rejected without further review, and without comment. 618 619 One significant exception is when moving code from one file to 620 another -- in this case you should not modify the moved code at all in 621 the same patch which moves it. This clearly delineates the act of 622 moving the code and your changes. This greatly aids review of the 623 actual differences and allows tools to better track the history of 624 the code itself. 625 626 Check your patches with the patch style checker prior to submission 627 (scripts/checkpatch.pl). The style checker should be viewed as 628 a guide not as the final word. If your code looks better with 629 a violation then its probably best left alone. 630 631 The checker reports at three levels: 632 - ERROR: things that are very likely to be wrong 633 - WARNING: things requiring careful review 634 - CHECK: things requiring thought 635 636 You should be able to justify all violations that remain in your 637 patch. 638 639 640 641 2) #ifdefs are ugly 642 643 Code cluttered with ifdefs is difficult to read and maintain. Don't do 644 it. Instead, put your ifdefs in a header, and conditionally define 645 'static inline' functions, or macros, which are used in the code. 646 Let the compiler optimize away the "no-op" case. 647 648 Simple example, of poor code: 649 650 dev = alloc_etherdev (sizeof(struct funky_private)); 651 if (!dev) 652 return -ENODEV; 653 #ifdef CONFIG_NET_FUNKINESS 654 init_funky_net(dev); 655 #endif 656 657 Cleaned-up example: 658 659 (in header) 660 #ifndef CONFIG_NET_FUNKINESS 661 static inline void init_funky_net (struct net_device *d) {} 662 #endif 663 664 (in the code itself) 665 dev = alloc_etherdev (sizeof(struct funky_private)); 666 if (!dev) 667 return -ENODEV; 668 init_funky_net(dev); 669 670 671 672 3) 'static inline' is better than a macro 673 674 Static inline functions are greatly preferred over macros. 675 They provide type safety, have no length limitations, no formatting 676 limitations, and under gcc they are as cheap as macros. 677 678 Macros should only be used for cases where a static inline is clearly 679 suboptimal [there are a few, isolated cases of this in fast paths], 680 or where it is impossible to use a static inline function [such as 681 string-izing]. 682 683 'static inline' is preferred over 'static __inline__', 'extern inline', 684 and 'extern __inline__'. 685 686 687 688 4) Don't over-design. 689 690 Don't try to anticipate nebulous future cases which may or may not 691 be useful: "Make it as simple as you can, and no simpler." 692 693 694 695 ---------------------- 696 SECTION 3 - REFERENCES 697 ---------------------- 698 699 Andrew Morton, "The perfect patch" (tpp). 700 <http://userweb.kernel.org/~akpm/stuff/tpp.txt> 701 702 Jeff Garzik, "Linux kernel patch submission format". 703 <http://linux.yyz.us/patch-format.html> 704 705 Greg Kroah-Hartman, "How to piss off a kernel subsystem maintainer". 706 <http://www.kroah.com/log/2005/03/31/> 707 <http://www.kroah.com/log/2005/07/08/> 708 <http://www.kroah.com/log/2005/10/19/> 709 <http://www.kroah.com/log/2006/01/11/> 710 711 NO!!!! No more huge patch bombs to linux-kernel[AT]vger.kernel[DOT]org people! 712 <http://marc.theaimsgroup.com/?l=linux-kernel&m=112112749912944&w=2> 713 714 Kernel Documentation/CodingStyle: 715 <http://users.sosdg.org/~qiyong/lxr/source/Documentation/CodingStyle> 716 717 Linus Torvalds's mail on the canonical patch format: 718 <http://lkml.org/lkml/2005/4/7/183> 719 720 Andi Kleen, "On submitting kernel patches" 721 Some strategies to get difficult or controversal changes in. 722 http://halobates.de/on-submitting-patches.pdf 723 724 --