docs: document all error message types in checkpatch

All the error message types now have a verbose description.

Also there are two new groups of message types:

- Macros, Attributes and Symbols
- Functions and Variables

Rearrange the message types to fit these new groups as needed.

Signed-off-by: Dwaipayan Ray <dwaipayanray1@gmail.com>
Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20210322082139.33822-1-dwaipayanray1@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Dwaipayan Ray 2021-03-22 13:51:39 +05:30 коммит произвёл Jonathan Corbet
Родитель 3501c960df
Коммит 3337c3a152
1 изменённых файлов: 280 добавлений и 38 удалений

Просмотреть файл

@ -280,43 +280,12 @@ API usage
However this is not always the case (See signal.h).
This message type is emitted only for includes from arch/.
**ARRAY_SIZE**
The ARRAY_SIZE(foo) macro should be preferred over
sizeof(foo)/sizeof(foo[0]) for finding number of elements in an
array.
The macro is defined in include/linux/kernel.h::
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
**AVOID_BUG**
BUG() or BUG_ON() should be avoided totally.
Use WARN() and WARN_ON() instead, and handle the "impossible"
error condition as gracefully as possible.
See: https://www.kernel.org/doc/html/latest/process/deprecated.html#bug-and-bug-on
**AVOID_EXTERNS**
Function prototypes don't need to be declared extern in .h
files. It's assumed by the compiler and is unnecessary.
**AVOID_L_PREFIX**
Local symbol names that are prefixed with `.L` should be avoided,
as this has special meaning for the assembler; a symbol entry will
not be emitted into the symbol table. This can prevent `objtool`
from generating correct unwind info.
Symbols with STB_LOCAL binding may still be used, and `.L` prefixed
local symbol names are still generally usable within a function,
but `.L` prefixed local symbol names should not be used to denote
the beginning or end of code regions via
`SYM_CODE_START_LOCAL`/`SYM_CODE_END`
**BIT_MACRO**
Defines like: 1 << <digit> could be BIT(digit).
The BIT() macro is defined in include/linux/bitops.h::
#define BIT(nr) (1UL << (nr))
**CONSIDER_KSTRTO**
The simple_strtol(), simple_strtoll(), simple_strtoul(), and
simple_strtoull() functions explicitly ignore overflows, which
@ -325,6 +294,25 @@ API usage
correct replacements.
See: https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull
**LOCKDEP**
The lockdep_no_validate class was added as a temporary measure to
prevent warnings on conversion of device->sem to device->mutex.
It should not be used for any other purpose.
See: https://lore.kernel.org/lkml/1268959062.9440.467.camel@laptop/
**MALFORMED_INCLUDE**
The #include statement has a malformed path. This has happened
because the author has included a double slash "//" in the pathname
accidentally.
**USE_LOCKDEP**
lockdep_assert_held() annotations should be preferred over
assertions based on spin_is_locked()
See: https://www.kernel.org/doc/html/latest/locking/lockdep-design.html#annotations
**UAPI_INCLUDE**
No #include statements in include/uapi should use a uapi/ path.
Comment style
-------------
@ -353,7 +341,6 @@ Comment style
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#commenting
Commit message
--------------
@ -397,6 +384,35 @@ Commit message
source patch.
See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin
**DIFF_IN_COMMIT_MSG**
Avoid having diff content in commit message.
This causes problems when one tries to apply a file containing both
the changelog and the diff because patch(1) tries to apply the diff
which it found in the changelog.
See: https://lore.kernel.org/lkml/20150611134006.9df79a893e3636019ad2759e@linux-foundation.org/
**GERRIT_CHANGE_ID**
To be picked up by gerrit, the footer of the commit message might
have a Change-Id like::
Change-Id: Ic8aaa0728a43936cd4c6e1ed590e01ba8f0fbf5b
Signed-off-by: A. U. Thor <author@example.com>
The Change-Id line must be removed before submitting.
**GIT_COMMIT_ID**
The proper way to reference a commit id is:
commit <12+ chars of sha1> ("<title line>")
An example may be::
Commit e21d2170f36602ae2708 ("video: remove unnecessary
platform_set_drvdata()") removed the unnecessary
platform_set_drvdata(), but left the variable "dev" unused,
delete it.
See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes
Comparison style
----------------
@ -426,6 +442,147 @@ Comparison style
side of the test should be avoided.
Macros, Attributes and Symbols
------------------------------
**ARRAY_SIZE**
The ARRAY_SIZE(foo) macro should be preferred over
sizeof(foo)/sizeof(foo[0]) for finding number of elements in an
array.
The macro is defined in include/linux/kernel.h::
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
**AVOID_EXTERNS**
Function prototypes don't need to be declared extern in .h
files. It's assumed by the compiler and is unnecessary.
**AVOID_L_PREFIX**
Local symbol names that are prefixed with `.L` should be avoided,
as this has special meaning for the assembler; a symbol entry will
not be emitted into the symbol table. This can prevent `objtool`
from generating correct unwind info.
Symbols with STB_LOCAL binding may still be used, and `.L` prefixed
local symbol names are still generally usable within a function,
but `.L` prefixed local symbol names should not be used to denote
the beginning or end of code regions via
`SYM_CODE_START_LOCAL`/`SYM_CODE_END`
**BIT_MACRO**
Defines like: 1 << <digit> could be BIT(digit).
The BIT() macro is defined in include/linux/bitops.h::
#define BIT(nr) (1UL << (nr))
**CONST_READ_MOSTLY**
When a variable is tagged with the __read_mostly annotation, it is a
signal to the compiler that accesses to the variable will be mostly
reads and rarely(but NOT never) a write.
const __read_mostly does not make any sense as const data is already
read-only. The __read_mostly annotation thus should be removed.
**DATE_TIME**
It is generally desirable that building the same source code with
the same set of tools is reproducible, i.e. the output is always
exactly the same.
The kernel does *not* use the ``__DATE__`` and ``__TIME__`` macros,
and enables warnings if they are used as they can lead to
non-deterministic builds.
See: https://www.kernel.org/doc/html/latest/kbuild/reproducible-builds.html#timestamps
**DEFINE_ARCH_HAS**
The ARCH_HAS_xyz and ARCH_HAVE_xyz patterns are wrong.
For big conceptual features use Kconfig symbols instead. And for
smaller things where we have compatibility fallback functions but
want architectures able to override them with optimized ones, we
should either use weak functions (appropriate for some cases), or
the symbol that protects them should be the same symbol we use.
See: https://lore.kernel.org/lkml/CA+55aFycQ9XJvEOsiM3txHL5bjUc8CeKWJNR_H+MiicaddB42Q@mail.gmail.com/
**INIT_ATTRIBUTE**
Const init definitions should use __initconst instead of
__initdata.
Similarly init definitions without const require a separate
use of const.
**INLINE_LOCATION**
The inline keyword should sit between storage class and type.
For example, the following segment::
inline static int example_function(void)
{
...
}
should be::
static inline int example_function(void)
{
...
}
**MULTISTATEMENT_MACRO_USE_DO_WHILE**
Macros with multiple statements should be enclosed in a
do - while block. Same should also be the case for macros
starting with `if` to avoid logic defects::
#define macrofun(a, b, c) \
do { \
if (a == 5) \
do_this(b, c); \
} while (0)
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#macros-enums-and-rtl
**WEAK_DECLARATION**
Using weak declarations like __attribute__((weak)) or __weak
can have unintended link defects. Avoid using them.
Functions and Variables
-----------------------
**CAMELCASE**
Avoid CamelCase Identifiers.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#naming
**FUNCTION_WITHOUT_ARGS**
Function declarations without arguments like::
int foo()
should be::
int foo(void)
**GLOBAL_INITIALISERS**
Global variables should not be initialized explicitly to
0 (or NULL, false, etc.). Your compiler (or rather your
loader, which is responsible for zeroing out the relevant
sections) automatically does it for you.
**INITIALISED_STATIC**
Static variables should not be initialized explicitly to zero.
Your compiler (or rather your loader) automatically does
it for you.
**RETURN_PARENTHESES**
return is not a function and as such doesn't need parentheses::
return (bar);
can simply be::
return bar;
Spacing and Brackets
--------------------
@ -439,7 +596,7 @@ Spacing and Brackets
and put the closing brace first::
if (x is true) {
we do y
we do y
}
This applies for all non-functional blocks.
@ -448,7 +605,7 @@ Spacing and Brackets
int function(int x)
{
body of function
body of function
}
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
@ -485,29 +642,114 @@ Spacing and Brackets
printk(KERN_INFO "bar");
**ELSE_AFTER_BRACE**
`else {` should follow the closing block `}` on the same line.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
**LINE_SPACING**
Vertical space is wasted given the limited number of lines an
editor window can display when multiple blank lines are used.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
**OPEN_BRACE**
The opening brace should be following the function definitions on the
next line. For any non-functional block it should be on the same line
as the last construct.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
**POINTER_LOCATION**
When using pointer data or a function that returns a pointer type,
the preferred use of * is adjacent to the data name or function name
and not adjacent to the type name.
Examples::
char *linux_banner;
unsigned long long memparse(char *ptr, char **retptr);
char *match_strdup(substring_t *s);
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
**SPACING**
Whitespace style used in the kernel sources is described in kernel docs.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
**SWITCH_CASE_INDENT_LEVEL**
switch should be at the same indent as case.
Example::
switch (suffix) {
case 'G':
case 'g':
mem <<= 30;
break;
case 'M':
case 'm':
mem <<= 20;
break;
case 'K':
case 'k':
mem <<= 10;
/* fall through */
default:
break;
}
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#indentation
**TRAILING_WHITESPACE**
Trailing whitespace should always be removed.
Some editors highlight the trailing whitespace and cause visual
distractions when editing files.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
**WHILE_AFTER_BRACE**
while should follow the closing bracket on the same line::
do {
...
} while(something);
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
Others
------
**CAMELCASE**
Avoid CamelCase Identifiers.
See: https://www.kernel.org/doc/html/latest/process/coding-style.html#naming
**CONFIG_DESCRIPTION**
Kconfig symbols should have a help text which fully describes
it.
**CORRUPTED_PATCH**
The patch seems to be corrupted or lines are wrapped.
Please regenerate the patch file before sending it to the maintainer.
**DOS_LINE_ENDINGS**
For DOS-formatted patches, there are extra ^M symbols at the end of
the line. These should be removed.
**EXECUTE_PERMISSIONS**
There is no reason for source files to be executable. The executable
bit can be removed safely.
**NON_OCTAL_PERMISSIONS**
Permission bits should use 4 digit octal permissions (like 0700 or 0444).
Avoid using any other base like decimal.
**NOT_UNIFIED_DIFF**
The patch file does not appear to be in unified-diff format. Please
regenerate the patch file before sending it to the maintainer.
**PRINTF_0XDECIMAL**
Prefixing 0x with decimal output is defective and should be corrected.
**TRAILING_STATEMENTS**
Trailing statements (for example after any conditional) should be
on the next line.
Like::
if (x == y) break;
should be::
if (x == y)
break;