Re: [Xen-devel] [PATCH v2 1/3] checkpatch.pl: add missing memory barriers

["Michael S. Tsirkin" <mst@xxxxxxxxxx>]

On Sun, Jan 10, 2016 at 07:07:05AM -0800, Joe Perches wrote:
> On Sun, 2016-01-10 at 13:56 +0200, Michael S. Tsirkin wrote:
> > SMP-only barriers were missing in checkpatch.pl
> > 
> > Refactor code slightly to make adding more variants easier.
> []
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
> > @@ -5116,7 +5116,25 @@ 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 = qr{
> > +                   mb|
> > +                   rmb|
> > +                   wmb|
> > +                   read_barrier_depends
> > +           }x;
> > +           my $smp_barriers = qr{
> > +                   store_release|
> > +                   load_acquire|
> > +                   store_mb|
> > +                   ($barriers)
> > +           }x;
> 
> If I use a variable called $smp_barriers, I'd expect
> it to actually be the smp_barriers, not to have to
> prefix it with smp_ before using it.
> 
>               my $smp_barriers = qr{
>                       smp_store_release|
>                       smp_load_acquire|
>                       smp_store_mb|
>                       smp_read_barrier_depends
>               }x;
> 
> or
> 
>               my $smp_barriers = qr{
>                       
> smp_(?:store_release|load_acquire|store_mb|read_barrier_depends)
>               }x;
> 

Yes but virt barriers (added in patch 3) are same things but prefixed
with virt_.  So we need the stems without smp_ prefix. If smp_barriers is
too confusing we'll just need to give them some other name.
How about:
my $smp_barrier_stems

?

> > +           my $all_barriers = qr{
> > +                   $barriers|
> > +                   smp_($smp_barriers)
> > +           }x;
> 
> And this shouldn't have a capture group.
> 
>               my $all_barriers = qr{
>                       $barriers|
>                       $smp_barriers
>               }x;             
> > +
> > +           if ($line =~ /\b($all_barriers)\s*\(/) {
> 
> This doesn't need the capture group either (?:all_barriers)
> 
> >                     if (!ctx_has_comment($first_line, $linenr))
> > {
> >                             WARN("MEMORY_BARRIER",
> >                                  "memory barrier without
> > comment\n" . $herecurr);

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