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How to Submit Patches for Open vSwitch

Send changes to Open vSwitch as patches to [email protected]. One patch per email, please. More details are included below.

If you are using Git, then git format-patch takes care of most of the mechanics described below for you.

Before You Start

Before you send patches at all, make sure that each patch makes sense. In particular:

  • A given patch should not break anything, even if later patches fix the problems that it causes. The source tree should still build and work after each patch is applied. (This enables git bisect to work best.)

  • A patch should make one logical change. Don't make multiple, logically unconnected changes to disparate subsystems in a single patch.

  • A patch that adds or removes user-visible features should also update the appropriate user documentation or manpages. Check "Feature Deprecation Guidelines" section in this document if you intend to remove user-visible feature.

Testing is also important:

  • A patch that modifies existing code should be tested with make check before submission.

  • A patch that adds or deletes files should also be tested with make distcheck before submission.

  • A patch that modifies Linux kernel code should be at least build-tested on various Linux kernel versions before submission. I suggest versions 2.6.32 and whatever the current latest release version is at the time.

  • A patch that modifies the ofproto or vswitchd code should be tested in at least simple cases before submission.

  • A patch that modifies xenserver code should be tested on XenServer before submission.

If you are using GitHub, then you may utilize the travis-ci.org CI build system by linking your GitHub repository to it. This will run some of the above tests automatically when you push changes to your repository. See the "Continuous Integration with Travis-CI" in the INSTALL.md file for details on how to set it up.

Email Subject

The subject line of your email should be in the following format: [PATCH <n>/<m>] <area>: <summary>

  • [PATCH <n>/<m>] indicates that this is the nth of a series of m patches. It helps reviewers to read patches in the correct order. You may omit this prefix if you are sending only one patch.

  • <area>: indicates the area of the Open vSwitch to which the change applies (often the name of a source file or a directory). You may omit it if the change crosses multiple distinct pieces of code.

  • <summary> briefly describes the change.

The subject, minus the [PATCH <n>/<m>] prefix, becomes the first line of the commit's change log message.

Description

The body of the email should start with a more thorough description of the change. This becomes the body of the commit message, following the subject. There is no need to duplicate the summary given in the subject.

Please limit lines in the description to 79 characters in width.

The description should include:

  • The rationale for the change.

  • Design description and rationale (but this might be better added as code comments).

  • Testing that you performed (or testing that should be done but you could not for whatever reason).

  • Tags (see below).

There is no need to describe what the patch actually changed, if the reader can see it for himself.

If the patch refers to a commit already in the Open vSwitch repository, please include both the commit number and the subject of the patch, e.g. 'commit 632d136c (vswitch: Remove restriction on datapath names.)'.

If you, the person sending the patch, did not write the patch yourself, then the very first line of the body should take the form From: <author name> <author email>, followed by a blank line. This will automatically cause the named author to be credited with authorship in the repository.

Tags

The description ends with a series of tags, written one to a line as the last paragraph of the email. Each tag indicates some property of the patch in an easily machine-parseable manner.

Examples of common tags follow.

Signed-off-by: Author Name <[email protected]...>

    Informally, this indicates that Author Name is the author or
    submitter of a patch and has the authority to submit it under
    the terms of the license.  The formal meaning is to agree to
    the Developer's Certificate of Origin (see below).

    If the author and submitter are different, each must sign off.
    If the patch has more than one author, all must sign off.

    Signed-off-by: Author Name <[email protected]...>
    Signed-off-by: Submitter Name <[email protected]...>

Co-authored-by: Author Name <[email protected]...>

    Git can only record a single person as the author of a given
    patch.  In the rare event that a patch has multiple authors,
    one must be given the credit in Git and the others must be
    credited via Co-authored-by: tags.  (All co-authors must also
    sign off.)

Acked-by: Reviewer Name <[email protected]...>

    Reviewers will often give an Acked-by: tag to code of which
    they approve.  It is polite for the submitter to add the tag
    before posting the next version of the patch or applying the
    patch to the repository.  Quality reviewing is hard work, so
    this gives a small amount of credit to the reviewer.

    Not all reviewers give Acked-by: tags when they provide
    positive reviews.  It's customary only to add tags from
    reviewers who actually provide them explicitly.

Tested-by: Tester Name <[email protected]...>

    When someone tests a patch, it is customary to add a
    Tested-by: tag indicating that.  It's rare for a tester to
    actually provide the tag; usually the patch submitter makes
    the tag himself in response to an email indicating successful
    testing results.

Tested-at: <URL>

    When a test report is publicly available, this provides a way
    to reference it.  Typical <URL>s would be build logs from
    autobuilders or references to mailing list archives.

    Some autobuilders only retain their logs for a limited amount
    of time.  It is less useful to cite these because they may be
    dead links for a developer reading the commit message months
    or years later.

Reported-by: Reporter Name <[email protected]...>

    When a patch fixes a bug reported by some person, please
    credit the reporter in the commit log in this fashion.  Please
    also add the reporter's name and email address to the list of
    people who provided helpful bug reports in the AUTHORS file at
    the top of the source tree.

    Fairly often, the reporter of a bug also tests the fix.
    Occasionally one sees a combined "Reported-and-tested-by:" tag
    used to indicate this.  It is also acceptable, and more
    common, to include both tags separately.

    (If a bug report is received privately, it might not always be
    appropriate to publicly credit the reporter.  If in doubt,
    please ask the reporter.)

Requested-by: Requester Name <[email protected]...>
Suggested-by: Suggester Name <[email protected]...>

    When a patch implements a request or a suggestion made by some
    person, please credit that person in the commit log in this
    fashion.  For a helpful suggestion, please also add the
    person's name and email address to the list of people who
    provided suggestions in the AUTHORS file at the top of the
    source tree.

    (If a suggestion or a request is received privately, it might
    not always be appropriate to publicly give credit.  If in
    doubt, please ask.)

Reported-at: <URL>

    If a patch fixes or is otherwise related to a bug reported in
    a public bug tracker, please include a reference to the bug in
    the form of a URL to the specific bug, e.g.:

    Reported-at: https://bugs.debian.org/743635

    This is also an appropriate way to refer to bug report emails
    in public email archives, e.g.:

    Reported-at: http://openvswitch.org/pipermail/dev/2014-June/040952.html

VMware-BZ: #1234567
ONF-JIRA: EXT-12345

    If a patch fixes or is otherwise related to a bug reported in
    a private bug tracker, you may include some tracking ID for
    the bug for your own reference.  Please include some
    identifier to make the origin clear, e.g. "VMware-BZ" refers
    to VMware's internal Bugzilla instance and "ONF-JIRA" refers
    to the Open Networking Foundation's JIRA bug tracker.

Bug #1234567.
Issue: 1234567

    These are obsolete forms of VMware-BZ: that can still be seen
    in old change log entries.  (They are obsolete because they do
    not tell the reader what bug tracker is referred to.)

Developer's Certificate of Origin

To help track the author of a patch as well as the submission chain, and be clear that the developer has authority to submit a patch for inclusion in openvswitch please sign off your work. The sign off certifies the following:

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.

Feature Deprecation Guidelines

Open vSwitch is intended to be user friendly. This means that under normal circumstances we don't abruptly remove features from OVS that some users might still be using. Otherwise, if we would, then we would possibly break our user setup when they upgrade and would receive bug reports.

Typical process to deprecate a feature in Open vSwitch is to:

(a) Mention deprecation of a feature in the NEWS file.  Also, mention
    expected release or absolute time when this feature would be removed
    from OVS altogether.  Don't use relative time (e.g. "in 6 months")
    because that is not clearly interpretable.

(b) If Open vSwitch is configured to use deprecated feature it should print
    a warning message to the log files clearly indicating that feature is
    deprecated and that use of it should be avoided.

(c) If this feature is mentioned in man pages, then add "Deprecated" keyword
    to it.

Also, if there is alternative feature to the one that is about to be marked as deprecated, then mention it in (a), (b) and (c) as well.

Remember to followup and actually remove the feature from OVS codebase once deprecation grace period has expired and users had opportunity to use at least one OVS release that would have informed them about feature deprecation!

Comments

If you want to include any comments in your email that should not be part of the commit's change log message, put them after the description, separated by a line that contains just ---. It may be helpful to include a diffstat here for changes that touch multiple files.

Patch

The patch should be in the body of the email following the description, separated by a blank line.

Patches should be in diff -up format. We recommend that you use Git to produce your patches, in which case you should use the -M -C options to git diff (or other Git tools) if your patch renames or copies files. Quilt (http://savannah.nongnu.org/projects/quilt) might be useful if you do not want to use Git.

Patches should be inline in the email message. Some email clients corrupt white space or wrap lines in patches. There are hints on how to configure many email clients to avoid this problem at: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob_plain;f=Documentation/email-clients.txt If you cannot convince your email client not to mangle patches, then sending the patch as an attachment is a second choice.

Please follow the style used in the code that you are modifying. The CodingStyle.md file describes the coding style used in most of Open vSwitch. Use Linux kernel coding style for Linux kernel code.

Example

From fa29a1c2c17682879e79a21bb0cdd5bbe67fa7c0 Mon Sep 17 00:00:00 2001
From: Jesse Gross <[email protected]>
Date: Thu, 8 Dec 2011 13:17:24 -0800
Subject: [PATCH] datapath: Alphabetize include/net/ipv6.h compat header.

Signed-off-by: Jesse Gross <[email protected]>
---
 datapath/linux/Modules.mk |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/datapath/linux/Modules.mk b/datapath/linux/Modules.mk
index fdd952e..f6cb88e 100644
--- a/datapath/linux/Modules.mk
+++ b/datapath/linux/Modules.mk
@@ -56,11 +56,11 @@ openvswitch_headers += \
 	linux/compat/include/net/dst.h \
 	linux/compat/include/net/genetlink.h \
 	linux/compat/include/net/ip.h \
+	linux/compat/include/net/ipv6.h \
 	linux/compat/include/net/net_namespace.h \
 	linux/compat/include/net/netlink.h \
 	linux/compat/include/net/protocol.h \
 	linux/compat/include/net/route.h \
-	linux/compat/include/net/ipv6.h \
 	linux/compat/genetlink.inc
 
 both_modules += brcompat
-- 
1.7.7.3