License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

18 files changed, 18 insertions, 0 deletions

diff --git a/include/net/netns/can.h b/include/net/netns/can.h
index b106e6ae2e5b..ecf238b8862c 100644
--- a/include/net/netns/can.h
+++ b/include/net/netns/can.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * can in net namespaces
  */
diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
index 17724c62de97..9795d628a127 100644
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_CONNTRACK_H
 #define __NETNS_CONNTRACK_H
 
diff --git a/include/net/netns/core.h b/include/net/netns/core.h
index 78eb1ff75475..0ad4d0c71228 100644
--- a/include/net/netns/core.h
+++ b/include/net/netns/core.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_CORE_H__
 #define __NETNS_CORE_H__
 
diff --git a/include/net/netns/dccp.h b/include/net/netns/dccp.h
index 98d2a7ce1f71..cdbc4f5b8390 100644
--- a/include/net/netns/dccp.h
+++ b/include/net/netns/dccp.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_DCCP_H__
 #define __NETNS_DCCP_H__
 
diff --git a/include/net/netns/generic.h b/include/net/netns/generic.h
index f15daaa89385..8a1ab47c3fb3 100644
--- a/include/net/netns/generic.h
+++ b/include/net/netns/generic.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * generic net pointers
  */
diff --git a/include/net/netns/hash.h b/include/net/netns/hash.h
index 69a6715d9f3f..24c78183a4c2 100644
--- a/include/net/netns/hash.h
+++ b/include/net/netns/hash.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NET_NS_HASH_H__
 #define __NET_NS_HASH_H__
 
diff --git a/include/net/netns/ieee802154_6lowpan.h b/include/net/netns/ieee802154_6lowpan.h
index 8170f8d7052b..736aeac52f56 100644
--- a/include/net/netns/ieee802154_6lowpan.h
+++ b/include/net/netns/ieee802154_6lowpan.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * ieee802154 6lowpan in net namespaces
  */
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 20d061c805e3..8fcff2837484 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * ipv4 in net namespaces
  */
diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index 2544f9760a42..dc825a5ddd7f 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * ipv6 in net namespaces
  */
diff --git a/include/net/netns/mib.h b/include/net/netns/mib.h
index d542a4b28cca..830bdf345b17 100644
--- a/include/net/netns/mib.h
+++ b/include/net/netns/mib.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_MIB_H__
 #define __NETNS_MIB_H__
 
diff --git a/include/net/netns/mpls.h b/include/net/netns/mpls.h
index 6608b3693385..a7bdcfbb0b28 100644
--- a/include/net/netns/mpls.h
+++ b/include/net/netns/mpls.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * mpls in net namespaces
  */
diff --git a/include/net/netns/netfilter.h b/include/net/netns/netfilter.h
index 72d66c8763d0..cc00af2ac2d7 100644
--- a/include/net/netns/netfilter.h
+++ b/include/net/netns/netfilter.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_NETFILTER_H
 #define __NETNS_NETFILTER_H
 
diff --git a/include/net/netns/nftables.h b/include/net/netns/nftables.h
index c80781146019..4109b5f3010f 100644
--- a/include/net/netns/nftables.h
+++ b/include/net/netns/nftables.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _NETNS_NFTABLES_H_
 #define _NETNS_NFTABLES_H_
 
diff --git a/include/net/netns/packet.h b/include/net/netns/packet.h
index 17ec2b95c062..aae69bb43cde 100644
--- a/include/net/netns/packet.h
+++ b/include/net/netns/packet.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Packet network namespace
  */
diff --git a/include/net/netns/sctp.h b/include/net/netns/sctp.h
index b7871d018354..ebc813277662 100644
--- a/include/net/netns/sctp.h
+++ b/include/net/netns/sctp.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_SCTP_H__
 #define __NETNS_SCTP_H__
 
diff --git a/include/net/netns/unix.h b/include/net/netns/unix.h
index 284649d4dfb4..91a3d7e39198 100644
--- a/include/net/netns/unix.h
+++ b/include/net/netns/unix.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Unix network namespace
  */
diff --git a/include/net/netns/x_tables.h b/include/net/netns/x_tables.h
index c8a7681efa6a..9bc5a12fdbb0 100644
--- a/include/net/netns/x_tables.h
+++ b/include/net/netns/x_tables.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_X_TABLES_H
 #define __NETNS_X_TABLES_H
 
diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index 611521646dd4..9991e5ef52cc 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __NETNS_XFRM_H
 #define __NETNS_XFRM_H