Subject: Re: [PATCH 1/3] checkpatch.pl: add missing memory barriers

From: "Michael S. Tsirkin" <[email-masked]>
Date: Mon, 4 Jan 2016 22:45:19 +0200

On Mon, Jan 04, 2016 at 08:07:40AM -0800, Joe Perches wrote:
> On Mon, 2016-01-04 at 13:36 +0200, Michael S. Tsirkin wrote:
> > SMP-only barriers were missing in checkpatch.pl
> > 
> > Refactor code slightly to make adding more variants easier.
> > 
> > Signed-off-by: Michael S. Tsirkin <[email-masked]>
> > ---
> >  scripts/checkpatch.pl | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > index 2b3c228..0245bbe 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -5116,7 +5116,14 @@ sub process {
> >  			}
> >  		}
> >  # check for memory barriers without a comment.
> > -		if ($line =~ /\b(mb|rmb|wmb|read_barrier_depends|smp_mb|smp_rmb|smp_wmb|smp_read_barrier_depends)\(/) {
> > +
> > +		my @barriers = ('mb', 'rmb', 'wmb', 'read_barrier_depends');
> > +		my @smp_barriers = ('smp_store_release', 'smp_load_acquire', 'smp_store_mb');
> > +
> > +		@smp_barriers = (@smp_barriers, map {"smp_" . $_} @barriers);
> 
> I think using map, which so far checkpatch doesn't use,
> makes smp_barriers harder to understand and it'd be
> better to enumerate them.

Okay - I'll rewrite using foreach.

> > +		my $all_barriers = join('|', (@barriers, @smp_barriers));
> > +
> > +		if ($line =~ /\b($all_barriers)\(/) {
> 
> It would be better to use /\b$all_barriers\s*\(/
> as there's no reason for the capture and there
> could be a space between the function and the
> open parenthesis.

That's the way it was - space before ( will trigger other
warnings. But sure, ok.

> 
> >  			if (!ctx_has_comment($first_line, $linenr)) {
> >  				WARN("MEMORY_BARRIER",
> >  				     "memory barrier without comment\n" . $herecurr);