[Linux-kernel-mentees] [PATCH RFC] checkpatch: fix multistatement macro checks

[Lukas Bulwahn]

Dwaipayan, did you checkpatch.pl your patch before sending it out?

On Wed, 30 Sep 2020, Dwaipayan Ray wrote:

> Checkpatch generates incorrect error message for certain
> macros.
> 
> When checkpatch was run on commit 4649079b9de1
> "tracing: Make ftrace packed events have align of 1"), it

brace ( is missing, checkpatch should warn you.

> generated multiple errors of the form:
>
Present tense is fine. checkpatch runs on ...,
it generates ...
 
> ERROR: Macros with multiple statements should be enclosed in a do -
> while loop
> +#define __field_packed(type, container, item)    type item;
> 
> This should certainly not be enclosed in a do - while loop.
> The problem was with the trailing semicolon. Any statement
> with trailing semicolon was marked as a multi-line macro.
> This was fixed by having a seperate rule for excluding
> single statements terminated by semicolon.
> 
> The second problem is due to while (...) {...} macros not being
> handled.
> For example, on commit fe557319aa06 ("maccess: rename probe_kernel_
> {read,write} to copy_{from,to}_kernel_nofault"), checkpatch
> generated following error:
> 
> ERROR: Macros with multiple statements should be enclosed in a do -
> while loop
> +#define copy_to_kernel_nofault_loop(dst, src, len, type, err_label) \
>  	while (len >= sizeof(type)) {
>         ....
> 
> This was fixed by having a seperate rule to match such while blocks.
>

s/seperate/separate/

If you address two different problems, make two patches not one.

Kernel developers can handle many patches...

Create two patches in a patch series, checkpatch.pl them, send them out 
here; then we will do a quick review and out they go to Joe and lkml.

Lukas
 
> Signed-off-by: Dwaipayan Ray <dwaipayanray1 at gmail.com>
> ---
>  scripts/checkpatch.pl | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 9e65d21456f1..4fb612200c27 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -5342,10 +5342,12 @@ sub process {
>  			    $dstat !~ /^\.$Ident\s*=/ &&				# .foo =
>  			    $dstat !~ /^(?:\#\s*$Ident|\#\s*$Constant)\s*$/ &&		# stringification #foo
>  			    $dstat !~ /^do\s*$Constant\s*while\s*$Constant;?$/ &&	# do {...} while (...); // do {...} while (...)
> +				$dstat !~ /^while\s*$Constant\s*$Constant$/ &&			# while (...) {...}

tab and spacing might be different than lines around it?

>  			    $dstat !~ /^for\s*$Constant$/ &&				# for (...)
>  			    $dstat !~ /^for\s*$Constant\s+(?:$Ident|-?$Constant)$/ &&	# for (...) bar()
>  			    $dstat !~ /^do\s*{/ &&					# do {...
>  			    $dstat !~ /^\(\{/ &&						# ({...
> +				$dstat !~ /;$/ &&						# statement;
>  			    $ctx !~ /^.\s*#\s*define\s+TRACE_(?:SYSTEM|INCLUDE_FILE|INCLUDE_PATH)\b/)
>  			{
>  				if ($dstat =~ /^\s*if\b/) {
> -- 
> 2.27.0
> 
>