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

[Dwaipayan Ray <dwaipayanray1@gmail.com>]

On Thu, Oct 1, 2020 at 12:40 AM Lukas Bulwahn <lukas.bulwahn@gmail.com> wrote:
>
>
> Dwaipayan, did you checkpatch.pl your patch before sending it out?
>

Oh right! I goofed up! Sorry about that.

> 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.
>

Again, I may have been too hasty in sending out the patch :(

> > 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.
>

Sure, I will do that.

> Lukas
>
> > Signed-off-by: Dwaipayan Ray <dwaipayanray1@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?

Weirdly, the other lines had 4 spaces instead of one
of the tabs.  Will correct that.

>
> >                           $dstat !~ /^for\s*$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
> >
> >
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