Date: Tue, 9 Jun 2015 12:05:57 +0200 (CEST)
From: Julia Lawall <julia.lawall@lip6.fr>
To: Paul Bolle <pebolle@tiscali.nl>
cc: monstr@monstr.eu, Julia Lawall <julia.lawall@lip6.fr>,
        Kedareswara rao Appana <appana.durga.rao@xilinx.com>,
        dan.j.williams@intel.com, vinod.koul@intel.com,
        michal.simek@xilinx.com, soren.brinkmann@xilinx.com,
        appanad@xilinx.com, punnaia@xilinx.com, dmaengine@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Srikanth Thokala <sthokal@xilinx.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Joe Perches <joe@perches.com>, Fengguang Wu <fengguang.wu@intel.com>
Subject: Re: [PATCH v4 2/2] dma: Add Xilinx AXI Central Direct Memory Access
 Engine driver support
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On Tue, 9 Jun 2015, Paul Bolle wrote:

> On Tue, 2015-06-09 at 09:09 +0200, Michal Simek wrote:
> > On 06/09/2015 08:10 AM, Julia Lawall wrote:
> > > On Tue, 9 Jun 2015, Michal Simek wrote:
> > >> Also sort of checking for this will be great. Julia?
> > >
> > > If this requires checking the contents of comment, Coccinelle currently
> > > can't help with that.  Perhaps an idea would be to just do a grep on the
> > > file.  So if I find MODULE_LICENSE("GPL v2") and then grepping for "either
> > > vresion 2" gives success, then there is a problem?  It's obviously not
> > > foolproof, but perhaps it could be helpful.
> >
> > Having some sort of checking somewhere will be great. checkpatch?
> > zero-day testing system?
>
> Mistakes I've seen made since I started checking this stuff (a few
> months ago):
> - typos in the license ident, say "GPLv2", "GPL V2", or "BSD": generates
> a warning when module is loaded and taints kernel. People still get this
> wrong. A test in checkpatch for these typos was submitted a while ago,
> but it never got added;
> - not adding MODULE_LICENSE() to a module: also generates a warning when
> module is loaded and taints kernel. People still get this wrong;
> - adding MODULE_LICENSE() to built-in only code: pointless at best, and
> annoying for reviewers ("Hey, did the submitter intend to write built-in
> only code or modular code?");
> - using "Dual BSD/GPL" but not a trace of the BSD license blurb in
> sight, while adding that blurb is one of the very few requirements this
> license actually has;
> - license mismatch, say comment blurb states "GPL v2 (or later)" but
> MODULE_LICENSE() ident states "GPL v2" only (or vice versa): very easy
> mistake to make, happens once or twice a week.
>
> Did I miss anything in that list?
>
> I'm afraid that most of the above can only be caught reliably by
> attention to detail by submitters and reviewers. That's a pity, because
> checking for that stuff is about as boring as it gets. (What does that
> say about me?)

There has been some research in this direction:

A sentence-matching method for automatic license identification of source
code files
Daniel M. German, Yuki Manabe, Katsuro Inoue

The reuse of free and open source software (FOSS) components is becoming
more prevalent. One of the major challenges in finding the right component
is finding one that has a license that is e for its intended use. The
license of a FOSS component is determined by the licenses of its source
code files. In this paper, we describe the challenges of identifying the
license under which source code is made available, and propose a
sentence-based matching algorithm to automatically do it. We demonstrate
the feasibility of our approach by implementing a tool named Ninka. We
performed an evaluation that shows that Ninka outperforms other methods of
license identification in precision and speed. We also performed an
empirical study on 0.8 million source code files of Debian that highlight
interesting facts about the manner in which licenses are used by FOSS.

If you google for the paper title, you come across a pdf of the paper.

There seems to be a tool available as well:

http://ninka.turingmachine.org/

julia
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