Hi Joe,
any further comment for this ? May this patch get your reviewed / acked?
On Thu, Apr 4, 2024 at 6:43 AM Barry Song <21cnbao@xxxxxxxxx> wrote:
>
> From: Xining Xu <mac.xxn@xxxxxxxxxxx>
>
> If function-like macros do not utilize a parameter, it might result in a
> build warning. In our coding style guidelines, we advocate for utilizing
> static inline functions to replace such macros. This patch verifies
> compliance with the new rule.
>
> For a macro such as the one below,
>
> #define test(a) do { } while (0)
>
> The test result is as follows.
>
> WARNING: Argument 'a' is not used in function-like macro
> #21: FILE: mm/init-mm.c:20:
> +#define test(a) do { } while (0)
>
> total: 0 errors, 1 warnings, 8 lines checked
>
> Signed-off-by: Xining Xu <mac.xxn@xxxxxxxxxxx>
> Tested-by: Barry Song <v-songbaohua@xxxxxxxx>
> Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
> Cc: Chris Zankel <chris@xxxxxxxxxx>
> Cc: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Cc: Mark Brown <broonie@xxxxxxxxxx>
> Cc: Andy Whitcroft <apw@xxxxxxxxxxxxx>
> Cc: Dwaipayan Ray <dwaipayanray1@xxxxxxxxx>
> Cc: Joe Perches <joe@xxxxxxxxxxx>
> Cc: Jonathan Corbet <corbet@xxxxxxx>
> Cc: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
> Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
> Cc: Jeff Johnson <quic_jjohnson@xxxxxxxxxxx>
> Cc: Charlemagne Lasse <charlemagnelasse@xxxxxxxxx>
> ---
> Documentation/dev-tools/checkpatch.rst | 14 ++++++++++++++
> scripts/checkpatch.pl | 6 ++++++
> 2 files changed, 20 insertions(+)
>
> 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..9895d7e38a9f 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
> --
> 2.34.1
>
Thanks
Barry
