linux-kernel - Re: [PATCH] checkpatch: warn if changed lines exceeds a maximum size

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Date:   Tue, 30 Jan 2018 18:04:18 +0000
From:   "Brown, Nicholas" <nb930b@...l.att.com>
To:     "joe@...ches.com" <joe@...ches.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "apw@...onical.com" <apw@...onical.com>
Subject: Re: [PATCH] checkpatch: warn if changed lines exceeds a maximum size

On Tue, 2018-01-30 at 08:10 -0800, Joe Perches wrote:
> On Tue, 2018-01-30 at 15:57 +0000, Brown, Nicholas wrote:
> > Changed lines is the total of inserted and deleted lines.
> > By default there is no limit, --max-changed-lines may be used to
> > set a
> > value. Some users may wish to encourage that patches are split into
> > smaller parts using this.
> > See Documentation/process/submitting-patches.rst#split-changes
> 
> (This patch seems whitespace damaged)
> 
> I don't care for this much as is either.
> 
> This patch doesn't add help text and it

I'll look to add some help text.

> should probably add a check for
> 	"if (!$file"
> so new files aren't size limited.
> 
> Also, it double counts lines that are
> added and deleted so doing things like
> refactoring a block of code into a new
> separate function would potentially trip
> this.

These were both intentional. Large new files are just as equal a
potential target for splitting as a large change to a file, and could
for example add basic infra/stubs in an initial patch, and then flesh
out implementation in follow up patches.
Similarly it counts both insertions and deletions, as it's the
cumulative total that's a better measure of change, as compared
(insertions - deletions) which could be for example 0 while cumulative
total is large.
By making the --max-changed-lines completely user defined, with no
default, it's left to individual developers/maintainers to determine
what they consider a meaningful value is to represent a "large change"
to warn on for splitting a patch.

Thanks,
Nick


> 
> > Signed-off-by: Nicholas Brown <nick.brown@....com>
> > ---
> >  scripts/checkpatch.pl | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> > 
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > index 31031f10fe56..1217d782b6bb 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -49,6 +49,7 @@ my @ignore = ();
> >  my $help = 0;
> >  my $configuration_file = ".checkpatch.conf";
> >  my $max_line_length = 80;
> > +my $max_changed_lines; # undef = no max
> >  my $ignore_perl_version = 0;
> >  my $minimum_perl_version = 5.10.0;
> >  my $min_conf_desc_length = 4;
> > @@ -209,6 +210,7 @@ GetOptions(
> >         'show-types!'   => \$show_types,
> >         'list-types!'   => \$list_types,
> >         'max-line-length=i' => \$max_line_length,
> > +       'max-changed-lines=i' => \$max_changed_lines,
> >         'min-conf-desc-length=i' => \$min_conf_desc_length,
> >         'root=s'        => \$root,
> >         'summary!'      => \$summary,
> > @@ -2165,6 +2167,8 @@ sub process {
> >         my $filename = shift;
> >  
> >         my $linenr=0;
> > +       my $inserted_lines_total=0;
> > +       my $deleted_lines_total=0;
> >         my $prevline="";
> >         my $prevrawline="";
> >         my $stashline="";
> > @@ -2233,6 +2237,14 @@ sub process {
> >  
> >                 push(@fixed, $rawline) if ($fix);
> >  
> > +               if ($rawline=~/^\+/) {
> > +                 $inserted_lines_total++
> > +               }
> > +
> > +               if ($rawline=~/^-/) {
> > +                 $deleted_lines_total++
> > +               }
> > +
> >                 if ($rawline=~/^\+\+\+\s+(\S+)/) {
> >                         $setup_docs = 0;
> >                         if ($1 =~ m@...umentation/admin-
> > guide/kernel-parameters.rst$@) {
> > @@ -2306,6 +2318,11 @@ sub process {
> >  
> >         $prefix = '';
> >  
> > +       if (defined $max_changed_lines &&
> > +           ($inserted_lines_total+$deleted_lines_total >
> > $max_changed_lines)) {
> > +         WARN("MAX_CHANGED_LINES", "please split the change into
> > smaller parts\n");
> > +       }
> > +
> >         $realcnt = 0;
> >         $linenr = 0;
> >         $fixlinenr = -1;
> > -- 
> > 2.14.1