Patch series "codingstyle: avoid unused parameters for a function-like
macro", v7.
A function-like macro could result in build warnings such as "unused
variable." This patchset updates the guidance to recommend always using a
static inline function instead and also provides checkpatch support for
this new rule.
This patch (of 2):
Recent commit 77292bb8ca ("crypto: scomp - remove memcpy if
sg_nents is 1 and pages are lowmem") leads to warnings on xtensa
and loongarch,
In file included from crypto/scompress.c:12:
include/crypto/scatterwalk.h: In function 'scatterwalk_pagedone':
include/crypto/scatterwalk.h:76:30: warning: variable 'page' set but not used [-Wunused-but-set-variable]
76 | struct page *page;
| ^~~~
crypto/scompress.c: In function 'scomp_acomp_comp_decomp':
>> crypto/scompress.c:174:38: warning: unused variable 'dst_page' [-Wunused-variable]
174 | struct page *dst_page = sg_page(req->dst);
|
The reason is that flush_dcache_page() is implemented as a noop
macro on these platforms as below,
#define flush_dcache_page(page) do { } while (0)
The driver code, for itself, seems be quite innocent and placing
maybe_unused seems pointless,
struct page *dst_page = sg_page(req->dst);
for (i = 0; i < nr_pages; i++)
flush_dcache_page(dst_page + i);
And it should be independent of architectural implementation
differences.
Let's provide guidance on coding style for requesting parameter
evaluation or proposing the migration to a static inline
function.
Link: https://lkml.kernel.org/r/20240507032757.146386-1-21cnbao@gmail.com
Link: https://lkml.kernel.org/r/20240507032757.146386-2-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Suggested-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Joe Perches <joe@perches.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Xining Xu <mac.xxn@outlook.com>
Cc: Charlemagne Lasse <charlemagnelasse@gmail.com>
Cc: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
EditorConfig is a specification to define the most basic code formatting
stuff, and it's supported by many editors and IDEs, either directly or
via plugins, including VSCode/VSCodium, Vim, emacs and more.
It allows to define formatting style related to indentation, charset,
end of lines and trailing whitespaces. It also allows to apply different
formats for different files based on wildcards, so for example it is
possible to apply different configs to *.{c,h}, *.py and *.rs.
In linux project, defining a .editorconfig might help to those people
that work on different projects with different indentation styles, so
they cannot define a global style. Now they will directly see the
correct indentation on every fresh clone of the project.
See https://editorconfig.org
Co-developed-by: Danny Lin <danny@kdrag0n.dev>
Signed-off-by: Danny Lin <danny@kdrag0n.dev>
Signed-off-by: Íñigo Huguet <ihuguet@redhat.com>
Acked-by: Mickaël Salaün <mic@digikod.net>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Tested-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Linus notes [1] that the introduction of new code that uses VM_BUG_ON()
is just as bad as BUG_ON(), because it will crash the kernel on
distributions that enable CONFIG_DEBUG_VM (like Fedora):
VM_BUG_ON() has the exact same semantics as BUG_ON. It is literally
no different, the only difference is "we can make the code smaller
because these are less important". [2]
This resulted in a more generic discussion about usage of BUG() and
friends. While there might be corner cases that still deserve a BUG_ON(),
most BUG_ON() cases should simply use WARN_ON_ONCE() and implement a
recovery path if reasonable:
The only possible case where BUG_ON can validly be used is "I have
some fundamental data corruption and cannot possibly return an
error". [2]
As a very good approximation is the general rule:
"absolutely no new BUG_ON() calls _ever_" [2]
... not even if something really shouldn't ever happen and is merely for
documenting that an invariant always has to hold. However, there are sill
exceptions where BUG_ON() may be used:
If you have a "this is major internal corruption, there's no way we can
continue", then BUG_ON() is appropriate. [3]
There is only one good BUG_ON():
Now, that said, there is one very valid sub-form of BUG_ON():
BUILD_BUG_ON() is absolutely 100% fine. [2]
While WARN will also crash the machine with panic_on_warn set, that's
exactly to be expected:
So we have two very different cases: the "virtual machine with good
logging where a dead machine is fine" - use 'panic_on_warn'. And
the actual real hardware with real drivers, running real loads by
users. [4]
The basic idea is that warnings will similarly get reported by users
and be found during testing. However, in contrast to a BUG(), there is a
way to actually influence the expected behavior (e.g., panic_on_warn)
and to eventually keep the machine alive to extract some debug info.
Ingo notes that not all WARN_ON_ONCE cases need recovery. If we don't ever
expect this code to trigger in any case, recovery code is not really
helpful.
I'd prefer to keep all these warnings 'simple' - i.e. no attempted
recovery & control flow, unless we ever expect these to trigger.
[5]
There have been different rules floating around that were never properly
documented. Let's try to clarify.
[1] https://lkml.kernel.org/r/CAHk-=wiEAH+ojSpAgx_Ep=NKPWHU8AdO3V56BXcCsU97oYJ1EA@mail.gmail.com
[2] https://lore.kernel.org/r/CAHk-=wg40EAZofO16Eviaj7mfqDhZ2gVEbvfsMf6gYzspRjYvw@mail.gmail.com
[3] https://lkml.kernel.org/r/CAHk-=wit-DmhMfQErY29JSPjFgebx_Ld+pnerc4J2Ag990WwAA@mail.gmail.com
[4] https://lore.kernel.org/r/CAHk-=wgF7K2gSSpy=m_=K3Nov4zaceUX9puQf1TjkTJLA2XC_g@mail.gmail.com
[5] https://lore.kernel.org/r/YwIW+mVeZoTOxn%2F4@gmail.com
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20220923113426.52871-2-david@redhat.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The dev_printk()-like functions moved to include/linux/dev_print.h in
commit af628aae86 ("device.h: move dev_printk()-like functions to
dev_printk.h").
Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20210423184012.39300-1-twoerner@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
while to come. Changes include:
- Some new Chinese translations
- Progress on the battle against double words words and non-HTTPS URLs
- Some block-mq documentation
- More RST conversions from Mauro. At this point, that task is
essentially complete, so we shouldn't see this kind of churn again for a
while. Unless we decide to switch to asciidoc or something...:)
- Lots of typo fixes, warning fixes, and more.
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Merge tag 'docs-5.9' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"It's been a busy cycle for documentation - hopefully the busiest for a
while to come. Changes include:
- Some new Chinese translations
- Progress on the battle against double words words and non-HTTPS
URLs
- Some block-mq documentation
- More RST conversions from Mauro. At this point, that task is
essentially complete, so we shouldn't see this kind of churn again
for a while. Unless we decide to switch to asciidoc or
something...:)
- Lots of typo fixes, warning fixes, and more"
* tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits)
scripts/kernel-doc: optionally treat warnings as errors
docs: ia64: correct typo
mailmap: add entry for <alobakin@marvell.com>
doc/zh_CN: add cpu-load Chinese version
Documentation/admin-guide: tainted-kernels: fix spelling mistake
MAINTAINERS: adjust kprobes.rst entry to new location
devices.txt: document rfkill allocation
PCI: correct flag name
docs: filesystems: vfs: correct flag name
docs: filesystems: vfs: correct sync_mode flag names
docs: path-lookup: markup fixes for emphasis
docs: path-lookup: more markup fixes
docs: path-lookup: fix HTML entity mojibake
CREDITS: Replace HTTP links with HTTPS ones
docs: process: Add an example for creating a fixes tag
doc/zh_CN: add Chinese translation prefer section
doc/zh_CN: add clearing-warn-once Chinese version
doc/zh_CN: add admin-guide index
doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label
futex: MAINTAINERS: Re-add selftests directory
...
Linux maintains a coding-style and its own idiomatic set of terminology.
Update the style guidelines to recommend replacements for the terms
master/slave and blacklist/whitelist.
Link: http://lore.kernel.org/r/159389297140.2210796.13590142254668787525.stgit@dwillia2-desk3.amr.corp.intel.com
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: SeongJae Park <sjpark@amazon.de>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Laura Abbott <laura@labbott.name>
Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.
Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Link: https://lore.kernel.org/r/20200621133630.46435-1-grandmaster@al2klimov.de
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The improved paragraph about line lengths contains a sentence with a
duplicate word: there is one "are" at the end of a line, followed by a
second one at the beginning of the next line.
Drop the first one, as that one is part of the longest line.
Fixes: bdc48fa11e ("checkpatch/coding-style: deprecate 80-column warning")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yes, staying withing 80 columns is certainly still _preferred_. But
it's not the hard limit that the checkpatch warnings imply, and other
concerns can most certainly dominate.
Increase the default limit to 100 characters. Not because 100
characters is some hard limit either, but that's certainly a "what are
you doing" kind of value and less likely to be about the occasional
slightly longer lines.
Miscellanea:
- to avoid unnecessary whitespace changes in files, checkpatch will no
longer emit a warning about line length when scanning files unless
--strict is also used
- Add a bit to coding-style about alignment to open parenthesis
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The guide to the kernel dev process documentation, for example, contains
references to older kernels and their timelines. In addition, one of the
"long term support kernels" listed have since reached EOL, and a new one
has been named. This patch brings information/tables up to date.
Additionally, some very trivial grammatical errors, unclear sentences,
and potentially unsavory diction have been edited.
Signed-off-by: Tony Fischetti <tony.fischetti@gmail.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Replace all the occurrences of FIELD_SIZEOF() with sizeof_field() except
at places where these are defined. Later patches will remove the unused
definition of FIELD_SIZEOF().
This patch is generated using following script:
EXCLUDE_FILES="include/linux/stddef.h|include/linux/kernel.h"
git grep -l -e "\bFIELD_SIZEOF\b" | while read file;
do
if [[ "$file" =~ $EXCLUDE_FILES ]]; then
continue
fi
sed -i -e 's/\bFIELD_SIZEOF\b/sizeof_field/g' $file;
done
Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
Link: https://lore.kernel.org/r/20190924105839.110713-3-pankaj.laxminarayan.bharadiya@intel.com
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: David Miller <davem@davemloft.net> # for net
Describe the fallthrough pseudo-keyword.
Convert the coding-style.rst example to the keyword style.
Add description and links to deprecated.rst.
Miguel Ojeda comments on the eventual [[fallthrough]] syntax:
"Note that C17/C18 does not have [[fallthrough]].
C++17 introduced it, as it is mentioned above. I would keep the
__attribute__((fallthrough)) -> [[fallthrough]] change you did,
though, since that is indeed the standard syntax (given the paragraph
references C++17).
I was told by Aaron Ballman (who is proposing them for C) that it is
more or less likely that it becomes standardized in C2x. However, it
is still not added to the draft (other attributes are already,
though). See N2268 and N2269:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2268.pdf (fallthrough)
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2269.pdf (attributes in general)"
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kbuild documentation clearly shows that the documents
there are written at different times: some use markdown,
some use their own peculiar logic to split sections.
Convert everything to ReST without affecting too much
the author's style and avoiding adding uneeded markups.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Generic allocation functions already emit a dump_stack()
so additional error logging isn't useful.
Document it as such and add a reference to the allocation
API.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
There has been some confusion since checkpatch started warning about bool
use in structures, and people have been avoiding using it.
Many people feel there is still a legitimate place for bool in structures,
so provide some guidance on bool usage derived from the entire thread that
spawned the checkpatch warning.
Link: https://lkml.kernel.org/r/CA+55aFwVZk1OfB9T2v014PTAKFhtVan_Zj2dOjnCy3x6E4UJfA@mail.gmail.com
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Joe Perches <joe@perches.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Joey Pabalinas <joeypabalinas@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Fix Sphinx warning in coding-style.rst:
Documentation/process/coding-style.rst:446: WARNING: Inline interpreted text or phrase reference start-string without end-string.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
In emacs 23.1 support for directory-local variables was added (see also
https://lists.gnu.org/archive/html/info-gnu-emacs/2009-07/msg00000.html).
Simplify the settings in coding-style.rst by using that feature.
Additionally, do not inherit any settings from emacs' linux coding style
to minimize dependencies on the version of emacs that is being used.
I have verified with several large and nontrivial kernel source files
that the new settings format code according to what checkpatch expects.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Alison Chaiken <alison@she-devel.com>
Cc: Joe Perches <joe@perches.com>
Cc: Federico Vaga <federico.vaga@vaga.pv.it>
Cc: Geyslan G. Bem <geyslan@gmail.com>
Cc: Tiago Natel de Moura <tiago4orion@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
`extern' with function prototypes makes lines longer and creates more
characters on the screen.
Do not bug people with checkpatch.pl warnings for now as fallout can be
devastating.
Link: http://lkml.kernel.org/r/20181101134153.GA29267@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some documents are refering to others without links. With this
patch I add those missing links.
This patch affects only documents under process/ and labels where
necessary.
Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
clang-format is a tool to format C/C++/... code according to a set of
rules and heuristics. Like most tools, it is not perfect nor covers
every single case, but it is good enough to be helpful.
In particular, it is useful for quickly re-formatting blocks of code
automatically, for reviewing full files in order to spot coding style
mistakes, typos and possible improvements. It is also handy for sorting
``#includes``, for aligning variables and macros, for reflowing text and
other similar tasks. It also serves as a teaching tool/guide for
newcomers.
The tool itself has been already included in the repositories of popular
Linux distributions for a long time. The rules in this file are
intended for clang-format >= 4, which is easily available in most
distributions.
This commit adds the configuration file that contains the rules that the
tool uses to know how to format the code according to the kernel coding
style. This gives us several advantages:
* clang-format works out of the box with reasonable defaults;
avoiding that everyone has to re-do the configuration.
* Everyone agrees (eventually) on what is the most useful default
configuration for most of the kernel.
* If it becomes commonplace among kernel developers, clang-format
may feel compelled to support us better. They already recognize
the Linux kernel and its style in their documentation and in one
of the style sub-options.
Some of clang-format's features relevant for the kernel are:
* Uses clang's tooling support behind the scenes to parse and rewrite
the code. It is not based on ad-hoc regexps.
* Supports reasonably well the Linux kernel coding style.
* Fast enough to be used at the press of a key.
* There are already integrations (either built-in or third-party)
for many common editors used by kernel developers (e.g. vim,
emacs, Sublime, Atom...) that allow you to format an entire file
or, more usefully, just your selection.
* Able to parse unified diffs -- you can, for instance, reformat
only the lines changed by a git commit.
* Able to reflow text comments as well.
* Widely supported and used by hundreds of developers in highly
complex projects and organizations (e.g. the LLVM project itself,
Chromium, WebKit, Google, Mozilla...). Therefore, it will be
supported for a long time.
See more information about the tool at:
https://clang.llvm.org/docs/ClangFormat.htmlhttps://clang.llvm.org/docs/ClangFormatStyleOptions.html
Link: http://lkml.kernel.org/r/20180318171632.qfkemw3mwbcukth6@gmail.com
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add another example of required braces when using a compound statement in
a loop.
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The "\n\t" sequence needs to be quoted or it will not render properly.
[jc: no signoff from the author, but it's trivial]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Having the kernel-documentation at the topmost level doesn't
allow generating a separate PDF file for it. Also, makes harder
to add extra contents. So, place it on a sub-dir.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Commit 865a1caa4b ("CodingStyle: Clarify and complete chapter 7")
renamed the label "out_buffer" to "out_free_buffer", but missed to
change this line.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The previous patch renamed several files that are cross-referenced
along the Kernel documentation. Adjust the links to point to
the right places.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Add several documents to the development-process ReST book.
As we don't want renames, use symlinks instead, keeping those
documents on their original place.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Barry Song