FreeBSD/Linux Kernel Cross Reference
sys/Documentation/SubmittingPatches

     
             How to Get Your Change Into the Linux Kernel
                     or
             Care And Operation Of Your Linus Torvalds
     
     
     
     For a person or company who wishes to submit a change to the Linux
     kernel, the process can sometimes be daunting if you're not familiar
    with "the system."  This text is a collection of suggestions which
    can greatly increase the chances of your change being accepted.
    
    Read Documentation/SubmitChecklist for a list of items to check
    before submitting code.  If you are submitting a driver, also read
    Documentation/SubmittingDrivers.
    
    
    
    --------------------------------------------
    SECTION 1 - CREATING AND SENDING YOUR CHANGE
    --------------------------------------------
    
    
    
    1) "diff -up"
    ------------
    
    Use "diff -up" or "diff -uprN" to create patches.
    
    All changes to the Linux kernel occur in the form of patches, as
    generated by diff(1).  When creating your patch, make sure to create it
    in "unified diff" format, as supplied by the '-u' argument to diff(1).
    Also, please use the '-p' argument which shows which C function each
    change is in - that makes the resultant diff a lot easier to read.
    Patches should be based in the root kernel source directory,
    not in any lower subdirectory.
    
    To create a patch for a single file, it is often sufficient to do:
    
            SRCTREE= linux-2.6
            MYFILE=  drivers/net/mydriver.c
    
            cd $SRCTREE
            cp $MYFILE $MYFILE.orig
            vi $MYFILE      # make your change
            cd ..
            diff -up $SRCTREE/$MYFILE{.orig,} > /tmp/patch
    
    To create a patch for multiple files, you should unpack a "vanilla",
    or unmodified kernel source tree, and generate a diff against your
    own source tree.  For example:
    
            MYSRC= /devel/linux-2.6
    
            tar xvfz linux-2.6.12.tar.gz
            mv linux-2.6.12 linux-2.6.12-vanilla
            diff -uprN -X linux-2.6.12-vanilla/Documentation/dontdiff \
                    linux-2.6.12-vanilla $MYSRC > /tmp/patch
    
    "dontdiff" is a list of files which are generated by the kernel during
    the build process, and should be ignored in any diff(1)-generated
    patch.  The "dontdiff" file is included in the kernel tree in
    2.6.12 and later.  For earlier kernel versions, you can get it
    from <http://www.xenotime.net/linux/doc/dontdiff>.
    
    Make sure your patch does not include any extra files which do not
    belong in a patch submission.  Make sure to review your patch -after-
    generated it with diff(1), to ensure accuracy.
    
    If your changes produce a lot of deltas, you may want to look into
    splitting them into individual patches which modify things in
    logical stages.  This will facilitate easier reviewing by other
    kernel developers, very important if you want your patch accepted.
    There are a number of scripts which can aid in this:
    
    Quilt:
    http://savannah.nongnu.org/projects/quilt
    
    Andrew Morton's patch scripts:
    http://userweb.kernel.org/~akpm/stuff/patch-scripts.tar.gz
    Instead of these scripts, quilt is the recommended patch management
    tool (see above).
    
    
    
    2) Describe your changes.
    
    Describe the technical detail of the change(s) your patch includes.
    
    Be as specific as possible.  The WORST descriptions possible include
    things like "update driver X", "bug fix for driver X", or "this patch
    includes updates for subsystem X.  Please apply."
    
    The maintainer will thank you if you write your patch description in a
    form which can be easily pulled into Linux's source code management
    system, git, as a "commit log".  See #15, below.
    
    If your description starts to get long, that's a sign that you probably
    need to split up your patch.  See #3, next.
   
   When you submit or resubmit a patch or patch series, include the
   complete patch description and justification for it.  Don't just
   say that this is version N of the patch (series).  Don't expect the
   patch merger to refer back to earlier patch versions or referenced
   URLs to find the patch description and put that into the patch.
   I.e., the patch (series) and its description should be self-contained.
   This benefits both the patch merger(s) and reviewers.  Some reviewers
   probably didn't even receive earlier versions of the patch.
   
   If the patch fixes a logged bug entry, refer to that bug entry by
   number and URL.
   
   
   3) Separate your changes.
   
   Separate _logical changes_ into a single patch file.
   
   For example, if your changes include both bug fixes and performance
   enhancements for a single driver, separate those changes into two
   or more patches.  If your changes include an API update, and a new
   driver which uses that new API, separate those into two patches.
   
   On the other hand, if you make a single change to numerous files,
   group those changes into a single patch.  Thus a single logical change
   is contained within a single patch.
   
   If one patch depends on another patch in order for a change to be
   complete, that is OK.  Simply note "this patch depends on patch X"
   in your patch description.
   
   If you cannot condense your patch set into a smaller set of patches,
   then only post say 15 or so at a time and wait for review and integration.
   
   
   
   4) Style check your changes.
   
   Check your patch for basic style violations, details of which can be
   found in Documentation/CodingStyle.  Failure to do so simply wastes
   the reviewers time and will get your patch rejected, probably
   without even being read.
   
   At a minimum you should check your patches with the patch style
   checker prior to submission (scripts/checkpatch.pl).  You should
   be able to justify all violations that remain in your patch.
   
   
   
   5) Select e-mail destination.
   
   Look through the MAINTAINERS file and the source code, and determine
   if your change applies to a specific subsystem of the kernel, with
   an assigned maintainer.  If so, e-mail that person.  The script
   scripts/get_maintainer.pl can be very useful at this step.
   
   If no maintainer is listed, or the maintainer does not respond, send
   your patch to the primary Linux kernel developer's mailing list,
   linux-kernel@vger.kernel.org.  Most kernel developers monitor this
   e-mail list, and can comment on your changes.
   
   
   Do not send more than 15 patches at once to the vger mailing lists!!!
   
   
   Linus Torvalds is the final arbiter of all changes accepted into the
   Linux kernel.  His e-mail address is <torvalds@linux-foundation.org>. 
   He gets a lot of e-mail, so typically you should do your best to -avoid-
   sending him e-mail. 
   
   Patches which are bug fixes, are "obvious" changes, or similarly
   require little discussion should be sent or CC'd to Linus.  Patches
   which require discussion or do not have a clear advantage should
   usually be sent first to linux-kernel.  Only after the patch is
   discussed should the patch then be submitted to Linus.
   
   
   
   6) Select your CC (e-mail carbon copy) list.
   
   Unless you have a reason NOT to do so, CC linux-kernel@vger.kernel.org.
   
   Other kernel developers besides Linus need to be aware of your change,
   so that they may comment on it and offer code review and suggestions.
   linux-kernel is the primary Linux kernel developer mailing list.
   Other mailing lists are available for specific subsystems, such as
   USB, framebuffer devices, the VFS, the SCSI subsystem, etc.  See the
   MAINTAINERS file for a mailing list that relates specifically to
   your change.
   
   Majordomo lists of VGER.KERNEL.ORG at:
           <http://vger.kernel.org/vger-lists.html>
   
   If changes affect userland-kernel interfaces, please send
   the MAN-PAGES maintainer (as listed in the MAINTAINERS file)
   a man-pages patch, or at least a notification of the change,
   so that some information makes its way into the manual pages.
   
   Even if the maintainer did not respond in step #5, make sure to ALWAYS
   copy the maintainer when you change their code.
   
   For small patches you may want to CC the Trivial Patch Monkey
   trivial@kernel.org which collects "trivial" patches. Have a look
   into the MAINTAINERS file for its current manager.
   Trivial patches must qualify for one of the following rules:
    Spelling fixes in documentation
    Spelling fixes which could break grep(1)
    Warning fixes (cluttering with useless warnings is bad)
    Compilation fixes (only if they are actually correct)
    Runtime fixes (only if they actually fix things)
    Removing use of deprecated functions/macros (eg. check_region)
    Contact detail and documentation fixes
    Non-portable code replaced by portable code (even in arch-specific,
    since people copy, as long as it's trivial)
    Any fix by the author/maintainer of the file (ie. patch monkey
    in re-transmission mode)
   
   
   
   7) No MIME, no links, no compression, no attachments.  Just plain text.
   
   Linus and other kernel developers need to be able to read and comment
   on the changes you are submitting.  It is important for a kernel
   developer to be able to "quote" your changes, using standard e-mail
   tools, so that they may comment on specific portions of your code.
   
   For this reason, all patches should be submitting e-mail "inline".
   WARNING:  Be wary of your editor's word-wrap corrupting your patch,
   if you choose to cut-n-paste your patch.
   
   Do not attach the patch as a MIME attachment, compressed or not.
   Many popular e-mail applications will not always transmit a MIME
   attachment as plain text, making it impossible to comment on your
   code.  A MIME attachment also takes Linus a bit more time to process,
   decreasing the likelihood of your MIME-attached change being accepted.
   
   Exception:  If your mailer is mangling patches then someone may ask
   you to re-send them using MIME.
   
   See Documentation/email-clients.txt for hints about configuring
   your e-mail client so that it sends your patches untouched.
   
   8) E-mail size.
   
   When sending patches to Linus, always follow step #7.
   
   Large changes are not appropriate for mailing lists, and some
   maintainers.  If your patch, uncompressed, exceeds 300 kB in size,
   it is preferred that you store your patch on an Internet-accessible
   server, and provide instead a URL (link) pointing to your patch.
   
   
   
   9) Name your kernel version.
   
   It is important to note, either in the subject line or in the patch
   description, the kernel version to which this patch applies.
   
   If the patch does not apply cleanly to the latest kernel version,
   Linus will not apply it.
   
   
   
   10) Don't get discouraged.  Re-submit.
   
   After you have submitted your change, be patient and wait.  If Linus
   likes your change and applies it, it will appear in the next version
   of the kernel that he releases.
   
   However, if your change doesn't appear in the next version of the
   kernel, there could be any number of reasons.  It's YOUR job to
   narrow down those reasons, correct what was wrong, and submit your
   updated change.
   
   It is quite common for Linus to "drop" your patch without comment.
   That's the nature of the system.  If he drops your patch, it could be
   due to
   * Your patch did not apply cleanly to the latest kernel version.
   * Your patch was not sufficiently discussed on linux-kernel.
   * A style issue (see section 2).
   * An e-mail formatting issue (re-read this section).
   * A technical problem with your change.
   * He gets tons of e-mail, and yours got lost in the shuffle.
   * You are being annoying.
   
   When in doubt, solicit comments on linux-kernel mailing list.
   
   
   
   11) Include PATCH in the subject
   
   Due to high e-mail traffic to Linus, and to linux-kernel, it is common
   convention to prefix your subject line with [PATCH].  This lets Linus
   and other kernel developers more easily distinguish patches from other
   e-mail discussions.
   
   
   
   12) Sign your work
   
   To improve tracking of who did what, especially with patches that can
   percolate to their final resting place in the kernel through several
   layers of maintainers, we've introduced a "sign-off" procedure on
   patches that are being emailed around.
   
   The sign-off is a simple line at the end of the explanation for the
   patch, which certifies that you wrote it or otherwise have the right to
   pass it on as an open-source patch.  The rules are pretty simple: if you
   can certify the below:
   
           Developer's Certificate of Origin 1.1
   
           By making a contribution to this project, I certify that:
   
           (a) The contribution was created in whole or in part by me and I
               have the right to submit it under the open source license
               indicated in the file; or
   
           (b) The contribution is based upon previous work that, to the best
               of my knowledge, is covered under an appropriate open source
               license and I have the right under that license to submit that
               work with modifications, whether created in whole or in part
               by me, under the same open source license (unless I am
               permitted to submit under a different license), as indicated
               in the file; or
   
           (c) The contribution was provided directly to me by some other
               person who certified (a), (b) or (c) and I have not modified
               it.
   
           (d) I understand and agree that this project and the contribution
               are public and that a record of the contribution (including all
               personal information I submit with it, including my sign-off) is
               maintained indefinitely and may be redistributed consistent with
               this project or the open source license(s) involved.
   
   then you just add a line saying
   
           Signed-off-by: Random J Developer <random@developer.example.org>
   
   using your real name (sorry, no pseudonyms or anonymous contributions.)
   
   Some people also put extra tags at the end.  They'll just be ignored for
   now, but you can do this to mark internal company procedures or just
   point out some special detail about the sign-off. 
   
   If you are a subsystem or branch maintainer, sometimes you need to slightly
   modify patches you receive in order to merge them, because the code is not
   exactly the same in your tree and the submitters'. If you stick strictly to
   rule (c), you should ask the submitter to rediff, but this is a totally
   counter-productive waste of time and energy. Rule (b) allows you to adjust
   the code, but then it is very impolite to change one submitter's code and
   make him endorse your bugs. To solve this problem, it is recommended that
   you add a line between the last Signed-off-by header and yours, indicating
   the nature of your changes. While there is nothing mandatory about this, it
   seems like prepending the description with your mail and/or name, all
   enclosed in square brackets, is noticeable enough to make it obvious that
   you are responsible for last-minute changes. Example :
   
           Signed-off-by: Random J Developer <random@developer.example.org>
           [lucky@maintainer.example.org: struct foo moved from foo.c to foo.h]
           Signed-off-by: Lucky K Maintainer <lucky@maintainer.example.org>
   
   This practise is particularly helpful if you maintain a stable branch and
   want at the same time to credit the author, track changes, merge the fix,
   and protect the submitter from complaints. Note that under no circumstances
   can you change the author's identity (the From header), as it is the one
   which appears in the changelog.
   
   Special note to back-porters: It seems to be a common and useful practise
   to insert an indication of the origin of a patch at the top of the commit
   message (just after the subject line) to facilitate tracking. For instance,
   here's what we see in 2.6-stable :
   
       Date:   Tue May 13 19:10:30 2008 +0000
   
           SCSI: libiscsi regression in 2.6.25: fix nop timer handling
   
           commit 4cf1043593db6a337f10e006c23c69e5fc93e722 upstream
   
   And here's what appears in 2.4 :
   
       Date:   Tue May 13 22:12:27 2008 +0200
   
           wireless, airo: waitbusy() won't delay
   
           [backport of 2.6 commit b7acbdfbd1f277c1eb23f344f899cfa4cd0bf36a]
   
   Whatever the format, this information provides a valuable help to people
   tracking your trees, and to people trying to trouble-shoot bugs in your
   tree.
   
   
   13) When to use Acked-by: and Cc:
   
   The Signed-off-by: tag indicates that the signer was involved in the
   development of the patch, or that he/she was in the patch's delivery path.
   
   If a person was not directly involved in the preparation or handling of a
   patch but wishes to signify and record their approval of it then they can
   arrange to have an Acked-by: line added to the patch's changelog.
   
   Acked-by: is often used by the maintainer of the affected code when that
   maintainer neither contributed to nor forwarded the patch.
   
   Acked-by: is not as formal as Signed-off-by:.  It is a record that the acker
   has at least reviewed the patch and has indicated acceptance.  Hence patch
   mergers will sometimes manually convert an acker's "yep, looks good to me"
   into an Acked-by:.
   
   Acked-by: does not necessarily indicate acknowledgement of the entire patch.
   For example, if a patch affects multiple subsystems and has an Acked-by: from
   one subsystem maintainer then this usually indicates acknowledgement of just
   the part which affects that maintainer's code.  Judgement should be used here.
   When in doubt people should refer to the original discussion in the mailing
   list archives.
   
   If a person has had the opportunity to comment on a patch, but has not
   provided such comments, you may optionally add a "Cc:" tag to the patch.
   This is the only tag which might be added without an explicit action by the
   person it names.  This tag documents that potentially interested parties
   have been included in the discussion
   
   
   14) Using Reported-by:, Tested-by: and Reviewed-by:
   
   If this patch fixes a problem reported by somebody else, consider adding a
   Reported-by: tag to credit the reporter for their contribution.  Please
   note that this tag should not be added without the reporter's permission,
   especially if the problem was not reported in a public forum.  That said,
   if we diligently credit our bug reporters, they will, hopefully, be
   inspired to help us again in the future.
   
   A Tested-by: tag indicates that the patch has been successfully tested (in
   some environment) by the person named.  This tag informs maintainers that
   some testing has been performed, provides a means to locate testers for
   future patches, and ensures credit for the testers.
   
   Reviewed-by:, instead, indicates that the patch has been reviewed and found
   acceptable according to the Reviewer's Statement:
   
           Reviewer's statement of oversight
   
           By offering my Reviewed-by: tag, I state that:
   
            (a) I have carried out a technical review of this patch to
                evaluate its appropriateness and readiness for inclusion into
                the mainline kernel.
   
            (b) Any problems, concerns, or questions relating to the patch
                have been communicated back to the submitter.  I am satisfied
                with the submitter's response to my comments.
   
            (c) While there may be things that could be improved with this
                submission, I believe that it is, at this time, (1) a
                worthwhile modification to the kernel, and (2) free of known
                issues which would argue against its inclusion.
   
            (d) While I have reviewed the patch and believe it to be sound, I
                do not (unless explicitly stated elsewhere) make any
                warranties or guarantees that it will achieve its stated
                purpose or function properly in any given situation.
   
   A Reviewed-by tag is a statement of opinion that the patch is an
   appropriate modification of the kernel without any remaining serious
   technical issues.  Any interested reviewer (who has done the work) can
   offer a Reviewed-by tag for a patch.  This tag serves to give credit to
   reviewers and to inform maintainers of the degree of review which has been
   done on the patch.  Reviewed-by: tags, when supplied by reviewers known to
   understand the subject area and to perform thorough reviews, will normally
   increase the likelihood of your patch getting into the kernel.
   
   
   15) The canonical patch format
   
   The canonical patch subject line is:
   
       Subject: [PATCH 001/123] subsystem: summary phrase
   
   The canonical patch message body contains the following:
   
     - A "from" line specifying the patch author.
   
     - An empty line.
   
     - The body of the explanation, which will be copied to the
       permanent changelog to describe this patch.
   
     - The "Signed-off-by:" lines, described above, which will
       also go in the changelog.
   
     - A marker line containing simply "---".
   
     - Any additional comments not suitable for the changelog.
   
     - The actual patch (diff output).
   
   The Subject line format makes it very easy to sort the emails
   alphabetically by subject line - pretty much any email reader will
   support that - since because the sequence number is zero-padded,
   the numerical and alphabetic sort is the same.
   
   The "subsystem" in the email's Subject should identify which
   area or subsystem of the kernel is being patched.
   
   The "summary phrase" in the email's Subject should concisely
   describe the patch which that email contains.  The "summary
   phrase" should not be a filename.  Do not use the same "summary
   phrase" for every patch in a whole patch series (where a "patch
   series" is an ordered sequence of multiple, related patches).
   
   Bear in mind that the "summary phrase" of your email becomes a
   globally-unique identifier for that patch.  It propagates all the way
   into the git changelog.  The "summary phrase" may later be used in
   developer discussions which refer to the patch.  People will want to
   google for the "summary phrase" to read discussion regarding that
   patch.  It will also be the only thing that people may quickly see
   when, two or three months later, they are going through perhaps
   thousands of patches using tools such as "gitk" or "git log
   --oneline".
   
   For these reasons, the "summary" must be no more than 70-75
   characters, and it must describe both what the patch changes, as well
   as why the patch might be necessary.  It is challenging to be both
   succinct and descriptive, but that is what a well-written summary
   should do.
   
   The "summary phrase" may be prefixed by tags enclosed in square
   brackets: "Subject: [PATCH tag] <summary phrase>".  The tags are not
   considered part of the summary phrase, but describe how the patch
   should be treated.  Common tags might include a version descriptor if
   the multiple versions of the patch have been sent out in response to
   comments (i.e., "v1, v2, v3"), or "RFC" to indicate a request for
   comments.  If there are four patches in a patch series the individual
   patches may be numbered like this: 1/4, 2/4, 3/4, 4/4.  This assures
   that developers understand the order in which the patches should be
   applied and that they have reviewed or applied all of the patches in
   the patch series.
   
   A couple of example Subjects:
   
       Subject: [patch 2/5] ext2: improve scalability of bitmap searching
       Subject: [PATCHv2 001/207] x86: fix eflags tracking
   
   The "from" line must be the very first line in the message body,
   and has the form:
   
           From: Original Author <author@example.com>
   
   The "from" line specifies who will be credited as the author of the
   patch in the permanent changelog.  If the "from" line is missing,
   then the "From:" line from the email header will be used to determine
   the patch author in the changelog.
   
   The explanation body will be committed to the permanent source
   changelog, so should make sense to a competent reader who has long
   since forgotten the immediate details of the discussion that might
   have led to this patch.  Including symptoms of the failure which the
   patch addresses (kernel log messages, oops messages, etc.) is
   especially useful for people who might be searching the commit logs
   looking for the applicable patch.  If a patch fixes a compile failure,
   it may not be necessary to include _all_ of the compile failures; just
   enough that it is likely that someone searching for the patch can find
   it.  As in the "summary phrase", it is important to be both succinct as
   well as descriptive.
   
   The "---" marker line serves the essential purpose of marking for patch
   handling tools where the changelog message ends.
   
   One good use for the additional comments after the "---" marker is for
   a diffstat, to show what files have changed, and the number of
   inserted and deleted lines per file.  A diffstat is especially useful
   on bigger patches.  Other comments relevant only to the moment or the
   maintainer, not suitable for the permanent changelog, should also go
   here.  A good example of such comments might be "patch changelogs"
   which describe what has changed between the v1 and v2 version of the
   patch.
   
   If you are going to include a diffstat after the "---" marker, please
   use diffstat options "-p 1 -w 70" so that filenames are listed from
   the top of the kernel source tree and don't use too much horizontal
   space (easily fit in 80 columns, maybe with some indentation).
   
   See more details on the proper patch format in the following
   references.
   
   
   16) Sending "git pull" requests  (from Linus emails)
   
   Please write the git repo address and branch name alone on the same line
   so that I can't even by mistake pull from the wrong branch, and so
   that a triple-click just selects the whole thing.
   
   So the proper format is something along the lines of:
   
           "Please pull from
   
                   git://jdelvare.pck.nerim.net/jdelvare-2.6 i2c-for-linus
   
            to get these changes:"
   
   so that I don't have to hunt-and-peck for the address and inevitably
   get it wrong (actually, I've only gotten it wrong a few times, and
   checking against the diffstat tells me when I get it wrong, but I'm
   just a lot more comfortable when I don't have to "look for" the right
   thing to pull, and double-check that I have the right branch-name).
   
   
   Please use "git diff -M --stat --summary" to generate the diffstat:
   the -M enables rename detection, and the summary enables a summary of
   new/deleted or renamed files.
   
   With rename detection, the statistics are rather different [...]
   because git will notice that a fair number of the changes are renames.
   
   -----------------------------------
   SECTION 2 - HINTS, TIPS, AND TRICKS
   -----------------------------------
   
   This section lists many of the common "rules" associated with code
   submitted to the kernel.  There are always exceptions... but you must
   have a really good reason for doing so.  You could probably call this
   section Linus Computer Science 101.
   
   
   
   1) Read Documentation/CodingStyle
   
   Nuff said.  If your code deviates too much from this, it is likely
   to be rejected without further review, and without comment.
   
   One significant exception is when moving code from one file to
   another -- in this case you should not modify the moved code at all in
   the same patch which moves it.  This clearly delineates the act of
   moving the code and your changes.  This greatly aids review of the
   actual differences and allows tools to better track the history of
   the code itself.
   
   Check your patches with the patch style checker prior to submission
   (scripts/checkpatch.pl).  The style checker should be viewed as
   a guide not as the final word.  If your code looks better with
   a violation then its probably best left alone.
   
   The checker reports at three levels:
    - ERROR: things that are very likely to be wrong
    - WARNING: things requiring careful review
    - CHECK: things requiring thought
   
   You should be able to justify all violations that remain in your
   patch.
   
   
   
   2) #ifdefs are ugly
   
   Code cluttered with ifdefs is difficult to read and maintain.  Don't do
   it.  Instead, put your ifdefs in a header, and conditionally define
   'static inline' functions, or macros, which are used in the code.
   Let the compiler optimize away the "no-op" case.
   
   Simple example, of poor code:
   
           dev = alloc_etherdev (sizeof(struct funky_private));
           if (!dev)
                   return -ENODEV;
           #ifdef CONFIG_NET_FUNKINESS
           init_funky_net(dev);
           #endif
   
   Cleaned-up example:
   
   (in header)
           #ifndef CONFIG_NET_FUNKINESS
           static inline void init_funky_net (struct net_device *d) {}
           #endif
   
   (in the code itself)
           dev = alloc_etherdev (sizeof(struct funky_private));
           if (!dev)
                   return -ENODEV;
           init_funky_net(dev);
   
   
   
   3) 'static inline' is better than a macro
   
   Static inline functions are greatly preferred over macros.
   They provide type safety, have no length limitations, no formatting
   limitations, and under gcc they are as cheap as macros.
   
   Macros should only be used for cases where a static inline is clearly
   suboptimal [there are a few, isolated cases of this in fast paths],
   or where it is impossible to use a static inline function [such as
   string-izing].
   
   'static inline' is preferred over 'static __inline__', 'extern inline',
   and 'extern __inline__'.
   
   
   
   4) Don't over-design.
   
   Don't try to anticipate nebulous future cases which may or may not
   be useful:  "Make it as simple as you can, and no simpler."
   
   
   
   ----------------------
   SECTION 3 - REFERENCES
   ----------------------
   
   Andrew Morton, "The perfect patch" (tpp).
     <http://userweb.kernel.org/~akpm/stuff/tpp.txt>
   
   Jeff Garzik, "Linux kernel patch submission format".
     <http://linux.yyz.us/patch-format.html>
   
   Greg Kroah-Hartman, "How to piss off a kernel subsystem maintainer".
     <http://www.kroah.com/log/linux/maintainer.html>
     <http://www.kroah.com/log/linux/maintainer-02.html>
     <http://www.kroah.com/log/linux/maintainer-03.html>
     <http://www.kroah.com/log/linux/maintainer-04.html>
     <http://www.kroah.com/log/linux/maintainer-05.html>
   
   NO!!!! No more huge patch bombs to linux-kernel@vger.kernel.org people!
     <http://marc.theaimsgroup.com/?l=linux-kernel&m=112112749912944&w=2>
   
   Kernel Documentation/CodingStyle:
     <http://users.sosdg.org/~qiyong/lxr/source/Documentation/CodingStyle>
   
   Linus Torvalds's mail on the canonical patch format:
     <http://lkml.org/lkml/2005/4/7/183>
   
   Andi Kleen, "On submitting kernel patches"
     Some strategies to get difficult or controversial changes in.
     http://halobates.de/on-submitting-patches.pdf
   
   --

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