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| -rw-r--r-- | Documentation/dev-tools/checkpatch.rst | 14 | ||||
| -rwxr-xr-x | scripts/checkpatch.pl | 6 |
2 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst index 127968995847..a9fac978a525 100644 --- a/Documentation/dev-tools/checkpatch.rst +++ b/Documentation/dev-tools/checkpatch.rst @@ -906,6 +906,20 @@ Macros, Attributes and Symbols See: https://lore.kernel.org/lkml/1399671106.2912.21.camel@joe-AO725/ + **MACRO_ARG_UNUSED** + If function-like macros do not utilize a parameter, it might result + in a build warning. We advocate for utilizing static inline functions + to replace such macros. + For example, for a macro such as the one below:: + + #define test(a) do { } while (0) + + there would be a warning like below:: + + WARNING: Argument 'a' is not used in function-like macro. + + See: https://www.kernel.org/doc/html/latest/process/coding-style.html#macros-enums-and-rtl + **SINGLE_STATEMENT_DO_WHILE_MACRO** For the multi-statement macros, it is necessary to use the do-while loop to avoid unpredictable code paths. The do-while loop helps to diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 9c4c4a61bc83..2b812210b412 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6040,6 +6040,12 @@ sub process { CHK("MACRO_ARG_PRECEDENCE", "Macro argument '$arg' may be better as '($arg)' to avoid precedence issues\n" . "$herectx"); } + +# check if this is an unused argument + if ($define_stmt !~ /\b$arg\b/) { + WARN("MACRO_ARG_UNUSED", + "Argument '$arg' is not used in function-like macro\n" . "$herectx"); + } } # check for macros with flow control, but without ## concatenation |