|From:||Theodore Ts'o <tytso-AT-mit.edu>|
|To:||Linus Torvalds <torvalds-AT-linux-foundation.org>|
|Subject:||[PATCH] Documentation: Add "how to write a good patch summary" to SubmittingPatches|
|Date:||Thu, 16 Apr 2009 07:44:45 -0400|
|Cc:||Linux Kernel Developers List <linux-kernel-AT-vger.kernel.org>, Theodore Ts'o <tytso-AT-mit.edu>, Ingo Molnar <mingo-AT-elte.hu>|
Unfortunately many patch submissions are arriving with painfully poor patch descriptions. As a result of the discussion on LKML: http://lkml.org/lkml/2009/4/15/296 explain how to submit a better patch description, in the (perhaps vain) hope that maintainers won't end up having to rewrite the git commit logs as often as they do today. Signed-off-by: "Theodore Ts'o" <email@example.com> Cc: Ingo Molnar <firstname.lastname@example.org> --- I don't describe the "Impact: " header, since this is still somewhat controversial. But even if we don't end up standardizing on Impact:, there is good information that we should be telling people about. Also, SubmittingPatches is getting quite long. It probably needs to be split up into a couple of different files, or at least reorganized for easier reading. It's not clear to me that trying to explain how to develop a good patch, how to write a good patch submission, and issues around the Developers Certification of Origin should be smushed together all into a single documentation file. But, that reorg is for another day and another patch. Documentation/SubmittingPatches | 65 ++++++++++++++++++++++++++++++-------- 1 files changed, 51 insertions(+), 14 deletions(-) diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches index f309d3c..b6f463f 100644 --- a/Documentation/SubmittingPatches +++ b/Documentation/SubmittingPatches @@ -91,6 +91,10 @@ 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. @@ -485,12 +489,33 @@ 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. +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: @@ -510,19 +535,31 @@ 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. +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. -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). +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. -- 22.214.171.124
Copyright © 2009, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds