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>
2017-11-01 14:07:57 +00:00
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/* SPDX-License-Identifier: GPL-2.0 */
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2015-05-27 01:39:37 +00:00
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/*
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* Latched RB-trees
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*
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* Copyright (C) 2015 Intel Corp., Peter Zijlstra <peterz@infradead.org>
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*
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* Since RB-trees have non-atomic modifications they're not immediately suited
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* for RCU/lockless queries. Even though we made RB-tree lookups non-fatal for
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* lockless lookups; we cannot guarantee they return a correct result.
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*
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* The simplest solution is a seqlock + RB-tree, this will allow lockless
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* lookups; but has the constraint (inherent to the seqlock) that read sides
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* cannot nest in write sides.
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*
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* If we need to allow unconditional lookups (say as required for NMI context
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* usage) we need a more complex setup; this data structure provides this by
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* employing the latch technique -- see @raw_write_seqcount_latch -- to
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* implement a latched RB-tree which does allow for unconditional lookups by
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* virtue of always having (at least) one stable copy of the tree.
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*
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* However, while we have the guarantee that there is at all times one stable
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* copy, this does not guarantee an iteration will not observe modifications.
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* What might have been a stable copy at the start of the iteration, need not
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* remain so for the duration of the iteration.
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*
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* Therefore, this does require a lockless RB-tree iteration to be non-fatal;
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* see the comment in lib/rbtree.c. Note however that we only require the first
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* condition -- not seeing partial stores -- because the latch thing isolates
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* us from loops. If we were to interrupt a modification the lookup would be
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* pointed at the stable tree and complete while the modification was halted.
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*/
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#ifndef RB_TREE_LATCH_H
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#define RB_TREE_LATCH_H
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#include <linux/rbtree.h>
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#include <linux/seqlock.h>
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struct latch_tree_node {
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struct rb_node node[2];
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};
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struct latch_tree_root {
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seqcount_t seq;
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struct rb_root tree[2];
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};
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/**
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* latch_tree_ops - operators to define the tree order
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* @less: used for insertion; provides the (partial) order between two elements.
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* @comp: used for lookups; provides the order between the search key and an element.
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*
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* The operators are related like:
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*
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* comp(a->key,b) < 0 := less(a,b)
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* comp(a->key,b) > 0 := less(b,a)
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* comp(a->key,b) == 0 := !less(a,b) && !less(b,a)
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*
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* If these operators define a partial order on the elements we make no
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* guarantee on which of the elements matching the key is found. See
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* latch_tree_find().
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*/
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struct latch_tree_ops {
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bool (*less)(struct latch_tree_node *a, struct latch_tree_node *b);
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int (*comp)(void *key, struct latch_tree_node *b);
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};
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static __always_inline struct latch_tree_node *
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__lt_from_rb(struct rb_node *node, int idx)
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{
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return container_of(node, struct latch_tree_node, node[idx]);
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}
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static __always_inline void
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__lt_insert(struct latch_tree_node *ltn, struct latch_tree_root *ltr, int idx,
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bool (*less)(struct latch_tree_node *a, struct latch_tree_node *b))
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{
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struct rb_root *root = <r->tree[idx];
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struct rb_node **link = &root->rb_node;
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struct rb_node *node = <n->node[idx];
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struct rb_node *parent = NULL;
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struct latch_tree_node *ltp;
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while (*link) {
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parent = *link;
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ltp = __lt_from_rb(parent, idx);
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if (less(ltn, ltp))
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link = &parent->rb_left;
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else
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link = &parent->rb_right;
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}
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rb_link_node_rcu(node, parent, link);
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rb_insert_color(node, root);
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}
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static __always_inline void
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__lt_erase(struct latch_tree_node *ltn, struct latch_tree_root *ltr, int idx)
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{
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rb_erase(<n->node[idx], <r->tree[idx]);
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}
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static __always_inline struct latch_tree_node *
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__lt_find(void *key, struct latch_tree_root *ltr, int idx,
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int (*comp)(void *key, struct latch_tree_node *node))
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{
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struct rb_node *node = rcu_dereference_raw(ltr->tree[idx].rb_node);
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struct latch_tree_node *ltn;
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int c;
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while (node) {
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ltn = __lt_from_rb(node, idx);
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c = comp(key, ltn);
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if (c < 0)
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node = rcu_dereference_raw(node->rb_left);
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else if (c > 0)
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node = rcu_dereference_raw(node->rb_right);
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else
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return ltn;
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}
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return NULL;
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}
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/**
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* latch_tree_insert() - insert @node into the trees @root
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* @node: nodes to insert
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* @root: trees to insert @node into
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* @ops: operators defining the node order
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*
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* It inserts @node into @root in an ordered fashion such that we can always
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* observe one complete tree. See the comment for raw_write_seqcount_latch().
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*
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* The inserts use rcu_assign_pointer() to publish the element such that the
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* tree structure is stored before we can observe the new @node.
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*
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* All modifications (latch_tree_insert, latch_tree_remove) are assumed to be
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* serialized.
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*/
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static __always_inline void
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latch_tree_insert(struct latch_tree_node *node,
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struct latch_tree_root *root,
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const struct latch_tree_ops *ops)
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{
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raw_write_seqcount_latch(&root->seq);
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__lt_insert(node, root, 0, ops->less);
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raw_write_seqcount_latch(&root->seq);
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__lt_insert(node, root, 1, ops->less);
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}
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/**
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* latch_tree_erase() - removes @node from the trees @root
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* @node: nodes to remote
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* @root: trees to remove @node from
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* @ops: operators defining the node order
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*
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* Removes @node from the trees @root in an ordered fashion such that we can
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* always observe one complete tree. See the comment for
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* raw_write_seqcount_latch().
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*
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* It is assumed that @node will observe one RCU quiescent state before being
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* reused of freed.
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*
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* All modifications (latch_tree_insert, latch_tree_remove) are assumed to be
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* serialized.
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*/
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static __always_inline void
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latch_tree_erase(struct latch_tree_node *node,
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struct latch_tree_root *root,
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const struct latch_tree_ops *ops)
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{
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raw_write_seqcount_latch(&root->seq);
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__lt_erase(node, root, 0);
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raw_write_seqcount_latch(&root->seq);
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__lt_erase(node, root, 1);
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}
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/**
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* latch_tree_find() - find the node matching @key in the trees @root
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* @key: search key
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* @root: trees to search for @key
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* @ops: operators defining the node order
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*
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* Does a lockless lookup in the trees @root for the node matching @key.
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*
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* It is assumed that this is called while holding the appropriate RCU read
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* side lock.
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*
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* If the operators define a partial order on the elements (there are multiple
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* elements which have the same key value) it is undefined which of these
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* elements will be found. Nor is it possible to iterate the tree to find
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* further elements with the same key value.
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*
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* Returns: a pointer to the node matching @key or NULL.
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*/
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static __always_inline struct latch_tree_node *
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latch_tree_find(void *key, struct latch_tree_root *root,
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const struct latch_tree_ops *ops)
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{
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struct latch_tree_node *node;
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unsigned int seq;
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do {
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seq = raw_read_seqcount_latch(&root->seq);
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node = __lt_find(key, root, seq & 1, ops->comp);
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} while (read_seqcount_retry(&root->seq, seq));
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return node;
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}
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#endif /* RB_TREE_LATCH_H */
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