On Wed, 2024-07-24 at 22:09 -0400, Julian Sun wrote: > Joe Perches <joe@xxxxxxxxxxx> 于2024年7月24日周三 09:30写道： > > > > On Tue, 2024-07-23 at 05:11 -0400, Julian Sun wrote: > > > Hi, > > > > > > Recently, I saw a patch[1] on the ext4 mailing list regarding > > > the correction of a macro definition error. Jan mentioned > > > that "The bug in the macro is a really nasty trap...". > > > Because existing compilers are unable to detect > > > unused parameters in macro definitions. This inspired me > > > to write a script to check for unused parameters in > > > macro definitions and to run it. > > > > > > > checkpatch has a similar test: > > > > https://lkml.kernel.org/r/20240507032757.146386-3-21cnbao@xxxxxxxxx > > > > $ git log --format=email -1 b1be5844c1a0124a49a30a20a189d0a53aa10578 > > From b1be5844c1a0124a49a30a20a189d0a53aa10578 Mon Sep 17 00:00:00 2001 > > From: Xining Xu <mac.xxn@xxxxxxxxxxx> > > Date: Tue, 7 May 2024 15:27:57 +1200 > > Subject: [PATCH] scripts: checkpatch: check unused parameters for > > function-like macro > > > > 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 > > > > > > > Link: https://lkml.kernel.org/r/20240507032757.146386-3-21cnbao@xxxxxxxxx > Yeah, I noticted the test. The difference between checkpatch and > macro_checker is that checkpatch only checks the patch files, instead > of the entire source files, which results in the inability to check > all macros in source files. Another possibility: $ git ls-files -- '*.[ch]' | \ xargs ./scripts/checkpatch -f --terse --no-summary --types=MACRO_ARG_UNUSED Though I agree the addition of a test for "do {} while (0)" and no content would be also be useful for unused macro args tests. --- scripts/checkpatch.pl | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 39032224d504f..285d29b3e9010 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6060,7 +6060,9 @@ sub process { } # check if this is an unused argument - if ($define_stmt !~ /\b$arg\b/) { + if ($define_stmt !~ /\b$arg\b/ && + $define_stmt !~ /^$/ && + $define_stmt !~ /^do\s*\{\s*\}\s*while\s*\(\s*0\s*\)$/) { WARN("MACRO_ARG_UNUSED", "Argument '$arg' is not used in function-like macro\n" . "$herectx"); }
