Re: [PATCH] checkpatch: Fix bad COMPLEX_MACRO on asm volatile

[Joe Perches]

On Sat, 2026-11-07 at 15:57 +0100, Pierre-Clément Tosi wrote:
> 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").

Thanks.

Acked-by: Joe Perches <joe@xxxxxxxxxxx>

> 
> 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@xxxxxxxxxx>
> ---
>  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,