From: Xining Xu <ma....@outlook.com>

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.

 ERROR: Parameter 'a' is not used in function-like macro, please use static
 inline instead
 #21: FILE: mm/init-mm.c:20:
 +#define test(a) do { } while (0)

 total: 1 errors, 0 warnings, 8 lines checked

Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Chris Zankel <ch...@zankel.net>
Cc: Huacai Chen <chenhua...@loongson.cn>
Cc: Herbert Xu <herb...@gondor.apana.org.au>
Cc: Guenter Roeck <li...@roeck-us.net>
Cc: Stephen Rothwell <s...@canb.auug.org.au>
Cc: Mark Brown <broo...@kernel.org>
Signed-off-by: Xining Xu <ma....@outlook.com>
Tested-by: Barry Song <v-songbao...@oppo.com>
---
 scripts/checkpatch.pl | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 9c4c4a61bc83..6f778f3403b5 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6109,6 +6109,30 @@ sub process {
                                WARN("TRAILING_SEMICOLON",
                                     "macros should not use a trailing 
semicolon\n" . "$herectx");
                        }
+
+                       if ($dstat =~ 
/^\+\s*#\s*define\s+$Ident\s*(\((?:[^\(\)]++|(?-1))*\))\s+(\S+.*)(\/\/.*)?/) {
+                               my $params = $1 || "";
+                               my $body = $2 || "";
+
+                           # get the individual params
+                               $params =~ tr/()//d;
+                               # remove leading and trailing whitespace
+                               $params =~ s/^\s+|\s+$//g;
+
+                               $ctx =~ s/\n*$//;
+                               my $cnt = statement_rawlines($ctx);
+                               my $herectx = get_stat_here($linenr, $cnt, 
$here);
+
+                               if ($params ne "") {
+                                       my @paramList = split /,\s*/, $params;
+                                       foreach my $param(@paramList) {
+                                               if ($body !~ /\b$param\b/) {
+                                                       
ERROR("UNUSED_PARAM_IN_MACRO",
+                                                            "Parameter 
'$param' is not used in function-like macro, please use static inline 
instead\n" . "$herectx");
+                                               }
+                                       }
+                               }
+                       }
                }
 
 # check for redundant bracing round if etc
-- 
2.34.1


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