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From:   Jann Horn <jannh@google.com>
Date:   Mon, 8 Jul 2019 19:37:33 +0200
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Subject: Re: [PATCH v5 04/12] S.A.R.A.: generic DFA for string matching
To:     Salvatore Mesoraca <s.mesoraca16@gmail.com>
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        Kernel Hardening <kernel-hardening@lists.openwall.com>,
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On Sun, Jul 7, 2019 at 6:01 PM Salvatore Mesoraca
<s.mesoraca16@gmail.com> wrote:
> Jann Horn <jannh@google.com> wrote:
> > Throughout the series, you are adding files that both add an SPDX
> > identifier and have a description of the license in the comment block
> > at the top. The SPDX identifier already identifies the license.
>
> I added the license description because I thought it was required anyway.
> IANAL, if you tell me that SPDX it's enough I'll remove the description.

IANAL too, but Documentation/process/license-rules.rst says:

====
The common way of expressing the license of a source file is to add the
matching boilerplate text into the top comment of the file.  Due to
formatting, typos etc. these "boilerplates" are hard to validate for
tools which are used in the context of license compliance.

An alternative to boilerplate text is the use of Software Package Data
Exchange (SPDX) license identifiers in each source file.  SPDX license
identifiers are machine parsable and precise shorthands for the license
under which the content of the file is contributed.  SPDX license
identifiers are managed by the SPDX Workgroup at the Linux Foundation and
have been agreed on by partners throughout the industry, tool vendors, and
legal teams.  For further information see https://spdx.org/

The Linux kernel requires the precise SPDX identifier in all source files.
The valid identifiers used in the kernel are explained in the section
`License identifiers`_ and have been retrieved from the official SPDX
license list at https://spdx.org/licenses/ along with the license texts.
====

and there have been lots of conversion patches to replace license
boilerplate headers with SPDX identifiers, see e.g. all the "treewide:
Replace GPLv2 boilerplate/reference with SPDX" patches.