[PATCH] checkpatch: Avoid declaration spacing checks for asm statements

[Jia Wang <wangjia@ultrarisc.com>]

The declaration spacing check uses C-oriented heuristics. In headers
that contain assembler code, those heuristics can mistake instructions
with comma-separated operands for declarations.

Assembler headers across architectures can contain operand shapes that
look like C declarations, and inline block comments can contain
punctuation that should not prevent an assembler statement from being
recognized.

Teach the check to recognize assembler statement shapes in files that
can contain assembler code, after ignoring inline block comments, and
skip only this declaration spacing test for those lines. Normal C
declaration spacing checks are unchanged.

Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
---
checkpatch's declaration spacing check uses C-oriented heuristics and can
mistake assembler instructions with comma-separated operands for C
declarations. This can trigger false LINE_SPACING warnings in headers
that contain assembler code.

Avoid the false positive by recognizing assembler statement shapes in
files that may contain assembler code. Strip inline block comments before
matching so punctuation inside comments does not prevent an assembler
statement from being recognized. Only this declaration spacing test is
skipped for matching assembler lines; normal C declaration spacing checks
are unchanged.

Validation covered the original asm-header reproducer, cross-architecture
assembler operand samples, C declaration regression samples, and inline
block comment cases. The HEAD patch passes:

  perl -c scripts/checkpatch.pl
  git format-patch -1 --stdout HEAD | scripts/checkpatch.pl --strict -
---
 scripts/checkpatch.pl | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 2b7a42bbdd94..bb307d49fc86 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1141,6 +1141,21 @@ sub deparenthesize {
 	return $string;
 }
 
+sub is_asm_statement {
+	my ($realfile, $line) = @_;
+
+	return 0 if (!defined($line));
+	return 0 if ($realfile !~ /\.(?:h|s|S)$/);
+
+	$line =~ s/^[\+ ]\s*//;
+	$line =~ s@/\*.*?\*/@@g;
+
+	return 0 if ($line =~ /[;{}]/);
+	return 1 if ($line =~ /^(?:[A-Za-z_.\$][\w.\$]*:\s*)?\.?[A-Za-z_][\w.]*\s+[^,]+,\s*.+$/);
+
+	return 0;
+}
+
 sub seed_camelcase_file {
 	my ($file) = @_;
 
@@ -4186,6 +4201,8 @@ sub process {
 			     $pl =~ /^\+\s+$Ident(?:\s+|\s*\*\s*)$Ident\s*[=,;\[]/ ||
 			# known declaration macros
 			     $pl =~ /^\+\s+$declaration_macros/) &&
+			# assembler statements can look like declarations
+			    !is_asm_statement($realfile, $prevrawline) &&
 			# for "else if" which can look like "$Ident $Ident"
 			    !($pl =~ /^\+\s+$c90_Keywords\b/ ||
 			# other possible extensions of declaration lines

---
base-commit: 58717b2a1365d06c8c64b72aa948541b53fe31eb
change-id: 20260716-checkpatch-47daa5fa23cb

Best regards,
--  
Jia Wang <wangjia@ultrarisc.com>