[PATCH] checkpatch: Fix bad COMPLEX_MACRO on asm volatile

[PATCH] checkpatch: Fix bad COMPLEX_MACRO on asm volatile

[Pierre-Clément Tosi]

Commit 42e152931deb ("checkpatch: exclude asm volatile from complex macro
check") added a substitution converting "asm volatile" into "asm_volatile"
so that macros expanding to an asm volatile statement would be treated like
a single function call and excluded from the COMPLEX_MACRO error ("Macros
with complex values should be enclosed in parentheses").

However, that substitution was placed after the loop that flattens
parenthesized expressions into "1u" (originally "1"). For a macro without
whitespace between "volatile" and "(", such as:

    #define foo(x) asm volatile("..." : : "r" (x))

flattening the parenthesized argument list first turns the statement into
"asm volatile1u". Because "1u" starts with a word character, the trailing
word boundary (\b) in /\b_*asm_*\s+_*volatile_*\b/ no longer matches after
"volatile", leaving the space between "asm" and "volatile1u" intact and
causing the macro to still fail the single-lvalue check and trigger a
false-positive COMPLEX_MACRO error.

Move the "asm volatile" to "asm_volatile" substitution before the
parenthesis-flattening loop so that "asm volatile(...)" is first rewritten
to "asm_volatile(...)" and then flattened to "asm_volatile1u" as intended.

Fixes: 42e152931deb ("checkpatch: exclude asm volatile from complex macro check")
Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
---
 scripts/checkpatch.pl | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index b8b64f720191..5319a8ecec50 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6050,6 +6050,9 @@ sub process {
 			$dstat =~ s/^\s*//s;
 			$dstat =~ s/\s*$//s;
 
+			# Make asm volatile uses seem like a generic function
+			$dstat =~ s/\b_*asm_*\s+_*volatile_*\b/asm_volatile/g;
+
 			# Flatten any parentheses and braces
 			while ($dstat =~ s/\([^\(\)]*\)/1u/ ||
 			       $dstat =~ s/\{[^\{\}]*\}/1u/ ||
@@ -6063,9 +6066,6 @@ sub process {
 			{
 			}
 
-			# Make asm volatile uses seem like a generic function
-			$dstat =~ s/\b_*asm_*\s+_*volatile_*\b/asm_volatile/g;
-
 			my $exceptions = qr{
 				$Declare|
 				# named exceptions

---
base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
change-id: 20261107-checkpatch-asm-complex_macro-75ee815da528

Best regards,
-- 
Pierre-Clément Tosi <ptosi@google.com>