Re: [PATCH] checkpatch: disable commit log length check warning for signature tag

[Lukas Bulwahn <lukas.bulwahn@gmail.com>]

On Mon, 27 Jul 2020, Nachiket Naganure wrote:

> On Sun, Jul 26, 2020 at 11:14:42PM -0700, Joe Perches wrote:
> > On Mon, 2020-07-27 at 11:24 +0530, Nachiket Naganure wrote:
> > > Disable commit log length check in case of signature tag. If the commit
> > > log line has valid signature tags such as "Reported-and-tested-by" with
> > > more than 75 characters, suppress the long length warning.
> > > 
> > > For instance in commit ac854131d984 ("USB: core: Fix misleading driver bug
> > > report"), the corresponding patch contains a "Reported by" tag line which
> > > exceeds 75 chars. And there is no valid way to shorten the length.
> > > 
> > > Signed-off-by: Nachiket Naganure <nachiketun8@gmail.com>
> > > ---
> > >  scripts/checkpatch.pl | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > > index 197436b20288..46237e9e0550 100755
> > > --- a/scripts/checkpatch.pl
> > > +++ b/scripts/checkpatch.pl
> > > @@ -2806,6 +2806,8 @@ sub process {
> > >  					# filename then :
> > >  		      $line =~ /^\s*(?:Fixes:|Link:)/i ||
> > >  					# A Fixes: or Link: line
> > > +		      $line =~ /$signature_tags/ ||
> > > +					# Check for signature_tags
> > >  		      $commit_log_possible_stack_dump)) {
> > >  			WARN("COMMIT_LOG_LONG_LINE",
> > >  			     "Possible unwrapped commit description (prefer a maximum 75 chars per line)\n" . $herecurr);
> > 
> > OK, but the test should be:
> > 
> > 		      $line =~ /^\s*$signature_tags/ ||
> > 
> > so the line has to start with a signature and
> > it won't match on signature tags in the middle
> > of other content on the same line.
> > 
> > 
> But the suggested won't work in case of merged signatures.
> Such as "Reported-and-tested-by: user@email.com"
> 

But Joe's remark is valid; we do not want to match on signature tags in 
the middle. These cases are probably mentioning signature tags as part of 
a sentence or some explanation.

Nachiket, think about a proper solution for this issue.

The evaluation data from running checkpatch.pl on previous commits will 
provide you some guidance on which heuristics might work and which not.

Lukas