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 17:07:57 +03:00
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// SPDX-License-Identifier: GPL-2.0
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2014-01-29 15:51:42 +04:00
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#include <linux/percpu.h>
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#include <linux/sched.h>
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2015-01-06 22:45:07 +03:00
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#include <linux/osq_lock.h>
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2014-01-29 15:51:42 +04:00
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/*
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* An MCS like lock especially tailored for optimistic spinning for sleeping
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* lock implementations (mutex, rwsem, etc).
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*
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* Using a single mcs node per CPU is safe because sleeping locks should not be
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* called from interrupt context and we have preemption disabled while
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* spinning.
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*/
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2014-07-14 21:27:48 +04:00
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node, osq_node);
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2014-01-29 15:51:42 +04:00
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2014-07-14 21:27:49 +04:00
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/*
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* We use the value 0 to represent "no CPU", thus the encoded value
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* will be the CPU number incremented by 1.
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*/
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static inline int encode_cpu(int cpu_nr)
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{
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return cpu_nr + 1;
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}
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2016-11-02 12:08:29 +03:00
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static inline int node_cpu(struct optimistic_spin_node *node)
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{
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return node->cpu - 1;
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}
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2014-07-14 21:27:49 +04:00
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static inline struct optimistic_spin_node *decode_cpu(int encoded_cpu_val)
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{
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int cpu_nr = encoded_cpu_val - 1;
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return per_cpu_ptr(&osq_node, cpu_nr);
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}
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2014-01-29 15:51:42 +04:00
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/*
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* Get a stable @node->next pointer, either for unlock() or unqueue() purposes.
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* Can return NULL in case we were the last queued and we updated @lock instead.
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*/
|
2014-07-14 21:27:48 +04:00
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static inline struct optimistic_spin_node *
|
2014-07-14 21:27:49 +04:00
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osq_wait_next(struct optimistic_spin_queue *lock,
|
2014-07-14 21:27:48 +04:00
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struct optimistic_spin_node *node,
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struct optimistic_spin_node *prev)
|
2014-01-29 15:51:42 +04:00
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{
|
2014-07-14 21:27:48 +04:00
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struct optimistic_spin_node *next = NULL;
|
2014-07-14 21:27:49 +04:00
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int curr = encode_cpu(smp_processor_id());
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int old;
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/*
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* If there is a prev node in queue, then the 'old' value will be
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* the prev node's CPU #, else it's set to OSQ_UNLOCKED_VAL since if
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* we're currently last in queue, then the queue will then become empty.
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*/
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old = prev ? prev->cpu : OSQ_UNLOCKED_VAL;
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2014-01-29 15:51:42 +04:00
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for (;;) {
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2014-07-14 21:27:49 +04:00
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if (atomic_read(&lock->tail) == curr &&
|
2015-09-14 10:37:24 +03:00
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atomic_cmpxchg_acquire(&lock->tail, curr, old) == curr) {
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2014-01-29 15:51:42 +04:00
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/*
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* We were the last queued, we moved @lock back. @prev
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* will now observe @lock and will complete its
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* unlock()/unqueue().
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*/
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break;
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}
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/*
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* We must xchg() the @node->next value, because if we were to
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* leave it in, a concurrent unlock()/unqueue() from
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* @node->next might complete Step-A and think its @prev is
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* still valid.
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*
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* If the concurrent unlock()/unqueue() wins the race, we'll
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* wait for either @lock to point to us, through its Step-B, or
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* wait for a new @node->next from its Step-C.
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*/
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if (node->next) {
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next = xchg(&node->next, NULL);
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if (next)
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break;
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}
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2016-10-25 12:03:14 +03:00
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cpu_relax();
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2014-01-29 15:51:42 +04:00
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}
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return next;
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}
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|
2014-07-14 21:27:49 +04:00
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bool osq_lock(struct optimistic_spin_queue *lock)
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2014-01-29 15:51:42 +04:00
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{
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2014-07-14 21:27:48 +04:00
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struct optimistic_spin_node *node = this_cpu_ptr(&osq_node);
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struct optimistic_spin_node *prev, *next;
|
2014-07-14 21:27:49 +04:00
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int curr = encode_cpu(smp_processor_id());
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int old;
|
2014-01-29 15:51:42 +04:00
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node->locked = 0;
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node->next = NULL;
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2014-07-14 21:27:49 +04:00
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node->cpu = curr;
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2014-01-29 15:51:42 +04:00
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2015-09-14 10:37:24 +03:00
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/*
|
2015-12-11 20:46:41 +03:00
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* We need both ACQUIRE (pairs with corresponding RELEASE in
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* unlock() uncontended, or fastpath) and RELEASE (to publish
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* the node fields we just initialised) semantics when updating
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* the lock tail.
|
2015-09-14 10:37:24 +03:00
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*/
|
2015-12-11 20:46:41 +03:00
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old = atomic_xchg(&lock->tail, curr);
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2014-07-14 21:27:49 +04:00
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if (old == OSQ_UNLOCKED_VAL)
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2014-01-29 15:51:42 +04:00
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return true;
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2014-07-14 21:27:49 +04:00
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prev = decode_cpu(old);
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node->prev = prev;
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locking/osq_lock: Fix osq_lock queue corruption
Fix ordering of link creation between node->prev and prev->next in
osq_lock(). A case in which the status of optimistic spin queue is
CPU6->CPU2 in which CPU6 has acquired the lock.
tail
v
,-. <- ,-.
|6| |2|
`-' -> `-'
At this point if CPU0 comes in to acquire osq_lock, it will update the
tail count.
CPU2 CPU0
----------------------------------
tail
v
,-. <- ,-. ,-.
|6| |2| |0|
`-' -> `-' `-'
After tail count update if CPU2 starts to unqueue itself from
optimistic spin queue, it will find an updated tail count with CPU0 and
update CPU2 node->next to NULL in osq_wait_next().
unqueue-A
tail
v
,-. <- ,-. ,-.
|6| |2| |0|
`-' `-' `-'
unqueue-B
->tail != curr && !node->next
If reordering of following stores happen then prev->next where prev
being CPU2 would be updated to point to CPU0 node:
tail
v
,-. <- ,-. ,-.
|6| |2| |0|
`-' `-' -> `-'
osq_wait_next()
node->next <- 0
xchg(node->next, NULL)
tail
v
,-. <- ,-. ,-.
|6| |2| |0|
`-' `-' `-'
unqueue-C
At this point if next instruction
WRITE_ONCE(next->prev, prev);
in CPU2 path is committed before the update of CPU0 node->prev = prev then
CPU0 node->prev will point to CPU6 node.
tail
v----------. v
,-. <- ,-. ,-.
|6| |2| |0|
`-' `-' `-'
`----------^
At this point if CPU0 path's node->prev = prev is committed resulting
in change of CPU0 prev back to CPU2 node. CPU2 node->next is NULL
currently,
tail
v
,-. <- ,-. <- ,-.
|6| |2| |0|
`-' `-' `-'
`----------^
so if CPU0 gets into unqueue path of osq_lock it will keep spinning
in infinite loop as condition prev->next == node will never be true.
Signed-off-by: Prateek Sood <prsood@codeaurora.org>
[ Added pictures, rewrote comments. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: sramana@codeaurora.org
Link: http://lkml.kernel.org/r/1500040076-27626-1-git-send-email-prsood@codeaurora.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-14 16:47:56 +03:00
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/*
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* osq_lock() unqueue
|
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*
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* node->prev = prev osq_wait_next()
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* WMB MB
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* prev->next = node next->prev = prev // unqueue-C
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*
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* Here 'node->prev' and 'next->prev' are the same variable and we need
|
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* to ensure these stores happen in-order to avoid corrupting the list.
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*/
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smp_wmb();
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|
2015-02-23 06:31:41 +03:00
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WRITE_ONCE(prev->next, node);
|
2014-01-29 15:51:42 +04:00
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/*
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* Normally @prev is untouchable after the above store; because at that
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* moment unlock can proceed and wipe the node element from stack.
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*
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* However, since our nodes are static per-cpu storage, we're
|
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* guaranteed their existence -- this allows us to apply
|
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* cmpxchg in an attempt to undo our queueing.
|
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*/
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|
2015-02-23 06:31:41 +03:00
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while (!READ_ONCE(node->locked)) {
|
2014-01-29 15:51:42 +04:00
|
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/*
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* If we need to reschedule bail... so we can block.
|
2016-11-02 12:08:29 +03:00
|
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* Use vcpu_is_preempted() to avoid waiting for a preempted
|
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* lock holder:
|
2014-01-29 15:51:42 +04:00
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*/
|
2016-11-02 12:08:29 +03:00
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if (need_resched() || vcpu_is_preempted(node_cpu(node->prev)))
|
2014-01-29 15:51:42 +04:00
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goto unqueue;
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|
2016-10-25 12:03:14 +03:00
|
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cpu_relax();
|
2014-01-29 15:51:42 +04:00
|
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}
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return true;
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unqueue:
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/*
|
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* Step - A -- stabilize @prev
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*
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* Undo our @prev->next assignment; this will make @prev's
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* unlock()/unqueue() wait for a next pointer since @lock points to us
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* (or later).
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*/
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for (;;) {
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if (prev->next == node &&
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cmpxchg(&prev->next, node, NULL) == node)
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break;
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|
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/*
|
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* We can only fail the cmpxchg() racing against an unlock(),
|
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* in which case we should observe @node->locked becomming
|
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* true.
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*/
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if (smp_load_acquire(&node->locked))
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return true;
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|
2016-10-25 12:03:14 +03:00
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cpu_relax();
|
2014-01-29 15:51:42 +04:00
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/*
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* Or we race against a concurrent unqueue()'s step-B, in which
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* case its step-C will write us a new @node->prev pointer.
|
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*/
|
2015-02-23 06:31:41 +03:00
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prev = READ_ONCE(node->prev);
|
2014-01-29 15:51:42 +04:00
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}
|
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/*
|
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* Step - B -- stabilize @next
|
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*
|
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* Similar to unlock(), wait for @node->next or move @lock from @node
|
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* back to @prev.
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*/
|
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next = osq_wait_next(lock, node, prev);
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if (!next)
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return false;
|
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/*
|
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* Step - C -- unlink
|
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*
|
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* @prev is stable because its still waiting for a new @prev->next
|
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* pointer, @next is stable because our @node->next pointer is NULL and
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* it will wait in Step-A.
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*/
|
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|
2015-02-23 06:31:41 +03:00
|
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WRITE_ONCE(next->prev, prev);
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WRITE_ONCE(prev->next, next);
|
2014-01-29 15:51:42 +04:00
|
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return false;
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}
|
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|
2014-07-14 21:27:49 +04:00
|
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void osq_unlock(struct optimistic_spin_queue *lock)
|
2014-01-29 15:51:42 +04:00
|
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{
|
2014-07-14 21:27:51 +04:00
|
|
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struct optimistic_spin_node *node, *next;
|
2014-07-14 21:27:49 +04:00
|
|
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int curr = encode_cpu(smp_processor_id());
|
2014-01-29 15:51:42 +04:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Fast path for the uncontended case.
|
|
|
|
*/
|
2015-09-14 10:37:24 +03:00
|
|
|
if (likely(atomic_cmpxchg_release(&lock->tail, curr,
|
|
|
|
OSQ_UNLOCKED_VAL) == curr))
|
2014-01-29 15:51:42 +04:00
|
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|
return;
|
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|
|
|
|
|
|
/*
|
|
|
|
* Second most likely case.
|
|
|
|
*/
|
2014-07-14 21:27:51 +04:00
|
|
|
node = this_cpu_ptr(&osq_node);
|
2014-01-29 15:51:42 +04:00
|
|
|
next = xchg(&node->next, NULL);
|
|
|
|
if (next) {
|
2015-02-23 06:31:41 +03:00
|
|
|
WRITE_ONCE(next->locked, 1);
|
2014-01-29 15:51:42 +04:00
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
next = osq_wait_next(lock, node, NULL);
|
|
|
|
if (next)
|
2015-02-23 06:31:41 +03:00
|
|
|
WRITE_ONCE(next->locked, 1);
|
2014-01-29 15:51:42 +04:00
|
|
|
}
|