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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2005-04-17 02:20:36 +04:00
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/* rwsem-spinlock.c: R/W semaphores: contention handling functions for
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* generic spinlock implementation
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*
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* Copyright (c) 2001 David Howells (dhowells@redhat.com).
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* - Derived partially from idea by Andrea Arcangeli <andrea@suse.de>
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* - Derived also from comments by Linus
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*/
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#include <linux/rwsem.h>
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2017-02-02 21:15:33 +03:00
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#include <linux/sched/signal.h>
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2017-02-08 20:51:35 +03:00
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#include <linux/sched/debug.h>
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2011-11-17 06:29:17 +04:00
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#include <linux/export.h>
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2005-04-17 02:20:36 +04:00
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2013-05-07 17:45:49 +04:00
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enum rwsem_waiter_type {
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RWSEM_WAITING_FOR_WRITE,
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RWSEM_WAITING_FOR_READ
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};
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2005-04-17 02:20:36 +04:00
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struct rwsem_waiter {
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struct list_head list;
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struct task_struct *task;
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2013-05-07 17:45:49 +04:00
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enum rwsem_waiter_type type;
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2005-04-17 02:20:36 +04:00
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};
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2009-12-15 05:00:21 +03:00
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int rwsem_is_locked(struct rw_semaphore *sem)
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{
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int ret = 1;
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unsigned long flags;
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2010-02-24 11:54:54 +03:00
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if (raw_spin_trylock_irqsave(&sem->wait_lock, flags)) {
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2014-07-16 16:54:55 +04:00
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ret = (sem->count != 0);
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2010-02-24 11:54:54 +03:00
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raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
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2009-12-15 05:00:21 +03:00
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}
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return ret;
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}
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EXPORT_SYMBOL(rwsem_is_locked);
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2005-04-17 02:20:36 +04:00
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/*
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* initialise the semaphore
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*/
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2006-07-03 11:24:53 +04:00
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void __init_rwsem(struct rw_semaphore *sem, const char *name,
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struct lock_class_key *key)
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2005-04-17 02:20:36 +04:00
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{
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2006-07-03 11:24:53 +04:00
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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/*
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* Make sure we are not reinitializing a held semaphore:
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*/
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debug_check_no_locks_freed((void *)sem, sizeof(*sem));
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2006-10-11 09:45:14 +04:00
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lockdep_init_map(&sem->dep_map, name, key, 0);
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2006-07-03 11:24:53 +04:00
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#endif
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2014-07-16 16:54:55 +04:00
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sem->count = 0;
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2010-02-24 11:54:54 +03:00
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raw_spin_lock_init(&sem->wait_lock);
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2005-04-17 02:20:36 +04:00
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INIT_LIST_HEAD(&sem->wait_list);
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}
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2009-12-15 05:00:20 +03:00
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EXPORT_SYMBOL(__init_rwsem);
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2005-04-17 02:20:36 +04:00
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/*
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* handle the lock release when processes blocked on it that can now run
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* - if we come here, then:
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* - the 'active count' _reached_ zero
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* - the 'waiting count' is non-zero
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* - the spinlock must be held by the caller
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* - woken process blocks are discarded from the list after having task zeroed
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* - writers are only woken if wakewrite is non-zero
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*/
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static inline struct rw_semaphore *
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__rwsem_do_wake(struct rw_semaphore *sem, int wakewrite)
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{
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struct rwsem_waiter *waiter;
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struct task_struct *tsk;
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int woken;
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waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
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2013-05-07 17:45:49 +04:00
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if (waiter->type == RWSEM_WAITING_FOR_WRITE) {
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2013-05-07 17:45:58 +04:00
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if (wakewrite)
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/* Wake up a writer. Note that we do not grant it the
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* lock - it will have to acquire it when it runs. */
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wake_up_process(waiter->task);
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2005-04-17 02:20:36 +04:00
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goto out;
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}
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/* grant an infinite number of read locks to the front of the queue */
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woken = 0;
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2013-05-07 17:45:58 +04:00
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do {
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2005-04-17 02:20:36 +04:00
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struct list_head *next = waiter->list.next;
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list_del(&waiter->list);
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tsk = waiter->task;
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2015-01-30 12:14:24 +03:00
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/*
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* Make sure we do not wakeup the next reader before
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* setting the nil condition to grant the next reader;
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* otherwise we could miss the wakeup on the other
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* side and end up sleeping again. See the pairing
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* in rwsem_down_read_failed().
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*/
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2005-05-01 19:58:47 +04:00
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smp_mb();
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2005-04-17 02:20:36 +04:00
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waiter->task = NULL;
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wake_up_process(tsk);
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put_task_struct(tsk);
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woken++;
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2013-05-07 17:45:58 +04:00
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if (next == &sem->wait_list)
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2005-04-17 02:20:36 +04:00
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break;
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waiter = list_entry(next, struct rwsem_waiter, list);
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2013-05-07 17:45:58 +04:00
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} while (waiter->type != RWSEM_WAITING_FOR_WRITE);
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2005-04-17 02:20:36 +04:00
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2014-07-16 16:54:55 +04:00
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sem->count += woken;
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2005-04-17 02:20:36 +04:00
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out:
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return sem;
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}
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/*
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* wake a single writer
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*/
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static inline struct rw_semaphore *
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__rwsem_wake_one_writer(struct rw_semaphore *sem)
|
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{
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struct rwsem_waiter *waiter;
|
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waiter = list_entry(sem->wait_list.next, struct rwsem_waiter, list);
|
2013-02-01 14:59:16 +04:00
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wake_up_process(waiter->task);
|
2005-04-17 02:20:36 +04:00
|
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return sem;
|
|
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|
}
|
|
|
|
|
|
|
|
/*
|
|
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* get a read lock on the semaphore
|
|
|
|
*/
|
locking/rwsem-spinlock: Add killable versions of __down_read()
Rename __down_read() in __down_read_common() and teach it
to abort waiting in case of pending signals and killable
state argument passed.
Note, that we shouldn't wake anybody up in EINTR path, as:
We check for signal_pending_state() after (!waiter.task)
test and under spinlock. So, current task wasn't able to
be woken up. It may be in two cases: a writer is owner
of the sem, or a writer is a first waiter of the sem.
If a writer is owner of the sem, no one else may work
with it in parallel. It will wake somebody, when it
call up_write() or downgrade_write().
If a writer is the first waiter, it will be woken up,
when the last active reader releases the sem, and
sem->count became 0.
Also note, that set_current_state() may be moved down
to schedule() (after !waiter.task check), as all
assignments in this type of semaphore (including wake_up),
occur under spinlock, so we can't miss anything.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
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: arnd@arndb.de
Cc: avagin@virtuozzo.com
Cc: davem@davemloft.net
Cc: fenghua.yu@intel.com
Cc: gorcunov@virtuozzo.com
Cc: heiko.carstens@de.ibm.com
Cc: hpa@zytor.com
Cc: ink@jurassic.park.msu.ru
Cc: mattst88@gmail.com
Cc: rth@twiddle.net
Cc: schwidefsky@de.ibm.com
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/149789533283.9059.9829416940494747182.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-19 21:02:12 +03:00
|
|
|
int __sched __down_read_common(struct rw_semaphore *sem, int state)
|
2005-04-17 02:20:36 +04:00
|
|
|
{
|
|
|
|
struct rwsem_waiter waiter;
|
2010-04-07 22:52:46 +04:00
|
|
|
unsigned long flags;
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2014-07-16 16:54:55 +04:00
|
|
|
if (sem->count >= 0 && list_empty(&sem->wait_list)) {
|
2005-04-17 02:20:36 +04:00
|
|
|
/* granted */
|
2014-07-16 16:54:55 +04:00
|
|
|
sem->count++;
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
goto out;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* set up my own style of waitqueue */
|
2017-01-04 00:43:13 +03:00
|
|
|
waiter.task = current;
|
2013-05-07 17:45:49 +04:00
|
|
|
waiter.type = RWSEM_WAITING_FOR_READ;
|
2017-01-04 00:43:13 +03:00
|
|
|
get_task_struct(current);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
|
|
|
list_add_tail(&waiter.list, &sem->wait_list);
|
|
|
|
|
|
|
|
/* wait to be given the lock */
|
|
|
|
for (;;) {
|
|
|
|
if (!waiter.task)
|
|
|
|
break;
|
locking/rwsem-spinlock: Add killable versions of __down_read()
Rename __down_read() in __down_read_common() and teach it
to abort waiting in case of pending signals and killable
state argument passed.
Note, that we shouldn't wake anybody up in EINTR path, as:
We check for signal_pending_state() after (!waiter.task)
test and under spinlock. So, current task wasn't able to
be woken up. It may be in two cases: a writer is owner
of the sem, or a writer is a first waiter of the sem.
If a writer is owner of the sem, no one else may work
with it in parallel. It will wake somebody, when it
call up_write() or downgrade_write().
If a writer is the first waiter, it will be woken up,
when the last active reader releases the sem, and
sem->count became 0.
Also note, that set_current_state() may be moved down
to schedule() (after !waiter.task check), as all
assignments in this type of semaphore (including wake_up),
occur under spinlock, so we can't miss anything.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
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: arnd@arndb.de
Cc: avagin@virtuozzo.com
Cc: davem@davemloft.net
Cc: fenghua.yu@intel.com
Cc: gorcunov@virtuozzo.com
Cc: heiko.carstens@de.ibm.com
Cc: hpa@zytor.com
Cc: ink@jurassic.park.msu.ru
Cc: mattst88@gmail.com
Cc: rth@twiddle.net
Cc: schwidefsky@de.ibm.com
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/149789533283.9059.9829416940494747182.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-19 21:02:12 +03:00
|
|
|
if (signal_pending_state(state, current))
|
|
|
|
goto out_nolock;
|
|
|
|
set_current_state(state);
|
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
schedule();
|
locking/rwsem-spinlock: Add killable versions of __down_read()
Rename __down_read() in __down_read_common() and teach it
to abort waiting in case of pending signals and killable
state argument passed.
Note, that we shouldn't wake anybody up in EINTR path, as:
We check for signal_pending_state() after (!waiter.task)
test and under spinlock. So, current task wasn't able to
be woken up. It may be in two cases: a writer is owner
of the sem, or a writer is a first waiter of the sem.
If a writer is owner of the sem, no one else may work
with it in parallel. It will wake somebody, when it
call up_write() or downgrade_write().
If a writer is the first waiter, it will be woken up,
when the last active reader releases the sem, and
sem->count became 0.
Also note, that set_current_state() may be moved down
to schedule() (after !waiter.task check), as all
assignments in this type of semaphore (including wake_up),
occur under spinlock, so we can't miss anything.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
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: arnd@arndb.de
Cc: avagin@virtuozzo.com
Cc: davem@davemloft.net
Cc: fenghua.yu@intel.com
Cc: gorcunov@virtuozzo.com
Cc: heiko.carstens@de.ibm.com
Cc: hpa@zytor.com
Cc: ink@jurassic.park.msu.ru
Cc: mattst88@gmail.com
Cc: rth@twiddle.net
Cc: schwidefsky@de.ibm.com
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/149789533283.9059.9829416940494747182.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-19 21:02:12 +03:00
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
}
|
|
|
|
|
locking/rwsem-spinlock: Add killable versions of __down_read()
Rename __down_read() in __down_read_common() and teach it
to abort waiting in case of pending signals and killable
state argument passed.
Note, that we shouldn't wake anybody up in EINTR path, as:
We check for signal_pending_state() after (!waiter.task)
test and under spinlock. So, current task wasn't able to
be woken up. It may be in two cases: a writer is owner
of the sem, or a writer is a first waiter of the sem.
If a writer is owner of the sem, no one else may work
with it in parallel. It will wake somebody, when it
call up_write() or downgrade_write().
If a writer is the first waiter, it will be woken up,
when the last active reader releases the sem, and
sem->count became 0.
Also note, that set_current_state() may be moved down
to schedule() (after !waiter.task check), as all
assignments in this type of semaphore (including wake_up),
occur under spinlock, so we can't miss anything.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
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: arnd@arndb.de
Cc: avagin@virtuozzo.com
Cc: davem@davemloft.net
Cc: fenghua.yu@intel.com
Cc: gorcunov@virtuozzo.com
Cc: heiko.carstens@de.ibm.com
Cc: hpa@zytor.com
Cc: ink@jurassic.park.msu.ru
Cc: mattst88@gmail.com
Cc: rth@twiddle.net
Cc: schwidefsky@de.ibm.com
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/149789533283.9059.9829416940494747182.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-19 21:02:12 +03:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
out:
|
locking/rwsem-spinlock: Add killable versions of __down_read()
Rename __down_read() in __down_read_common() and teach it
to abort waiting in case of pending signals and killable
state argument passed.
Note, that we shouldn't wake anybody up in EINTR path, as:
We check for signal_pending_state() after (!waiter.task)
test and under spinlock. So, current task wasn't able to
be woken up. It may be in two cases: a writer is owner
of the sem, or a writer is a first waiter of the sem.
If a writer is owner of the sem, no one else may work
with it in parallel. It will wake somebody, when it
call up_write() or downgrade_write().
If a writer is the first waiter, it will be woken up,
when the last active reader releases the sem, and
sem->count became 0.
Also note, that set_current_state() may be moved down
to schedule() (after !waiter.task check), as all
assignments in this type of semaphore (including wake_up),
occur under spinlock, so we can't miss anything.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
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: arnd@arndb.de
Cc: avagin@virtuozzo.com
Cc: davem@davemloft.net
Cc: fenghua.yu@intel.com
Cc: gorcunov@virtuozzo.com
Cc: heiko.carstens@de.ibm.com
Cc: hpa@zytor.com
Cc: ink@jurassic.park.msu.ru
Cc: mattst88@gmail.com
Cc: rth@twiddle.net
Cc: schwidefsky@de.ibm.com
Cc: tony.luck@intel.com
Link: http://lkml.kernel.org/r/149789533283.9059.9829416940494747182.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-19 21:02:12 +03:00
|
|
|
return 0;
|
|
|
|
|
|
|
|
out_nolock:
|
|
|
|
/*
|
|
|
|
* We didn't take the lock, so that there is a writer, which
|
|
|
|
* is owner or the first waiter of the sem. If it's a waiter,
|
|
|
|
* it will be woken by current owner. Not need to wake anybody.
|
|
|
|
*/
|
|
|
|
list_del(&waiter.list);
|
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
|
|
|
return -EINTR;
|
|
|
|
}
|
|
|
|
|
|
|
|
void __sched __down_read(struct rw_semaphore *sem)
|
|
|
|
{
|
|
|
|
__down_read_common(sem, TASK_UNINTERRUPTIBLE);
|
|
|
|
}
|
|
|
|
|
|
|
|
int __sched __down_read_killable(struct rw_semaphore *sem)
|
|
|
|
{
|
|
|
|
return __down_read_common(sem, TASK_KILLABLE);
|
2005-04-17 02:20:36 +04:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* trylock for reading -- returns 1 if successful, 0 if contention
|
|
|
|
*/
|
2008-02-08 15:19:55 +03:00
|
|
|
int __down_read_trylock(struct rw_semaphore *sem)
|
2005-04-17 02:20:36 +04:00
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
int ret = 0;
|
|
|
|
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2014-07-16 16:54:55 +04:00
|
|
|
if (sem->count >= 0 && list_empty(&sem->wait_list)) {
|
2005-04-17 02:20:36 +04:00
|
|
|
/* granted */
|
2014-07-16 16:54:55 +04:00
|
|
|
sem->count++;
|
2005-04-17 02:20:36 +04:00
|
|
|
ret = 1;
|
|
|
|
}
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* get a write lock on the semaphore
|
|
|
|
*/
|
2016-04-07 18:12:26 +03:00
|
|
|
int __sched __down_write_common(struct rw_semaphore *sem, int state)
|
2005-04-17 02:20:36 +04:00
|
|
|
{
|
|
|
|
struct rwsem_waiter waiter;
|
2010-04-07 22:52:46 +04:00
|
|
|
unsigned long flags;
|
2016-04-07 18:12:26 +03:00
|
|
|
int ret = 0;
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
|
|
|
/* set up my own style of waitqueue */
|
2017-01-04 00:43:13 +03:00
|
|
|
waiter.task = current;
|
2013-05-07 17:45:49 +04:00
|
|
|
waiter.type = RWSEM_WAITING_FOR_WRITE;
|
2005-04-17 02:20:36 +04:00
|
|
|
list_add_tail(&waiter.list, &sem->wait_list);
|
|
|
|
|
2013-02-01 14:59:16 +04:00
|
|
|
/* wait for someone to release the lock */
|
2005-04-17 02:20:36 +04:00
|
|
|
for (;;) {
|
2013-02-01 14:59:16 +04:00
|
|
|
/*
|
|
|
|
* That is the key to support write lock stealing: allows the
|
|
|
|
* task already on CPU to get the lock soon rather than put
|
|
|
|
* itself into sleep and waiting for system woke it or someone
|
|
|
|
* else in the head of the wait list up.
|
|
|
|
*/
|
2014-07-16 16:54:55 +04:00
|
|
|
if (sem->count == 0)
|
2005-04-17 02:20:36 +04:00
|
|
|
break;
|
2017-02-25 03:17:53 +03:00
|
|
|
if (signal_pending_state(state, current))
|
|
|
|
goto out_nolock;
|
|
|
|
|
sched/core: Remove set_task_state()
This is a nasty interface and setting the state of a foreign task must
not be done. As of the following commit:
be628be0956 ("bcache: Make gc wakeup sane, remove set_task_state()")
... everyone in the kernel calls set_task_state() with current, allowing
the helper to be removed.
However, as the comment indicates, it is still around for those archs
where computing current is more expensive than using a pointer, at least
in theory. An important arch that is affected is arm64, however this has
been addressed now [1] and performance is up to par making no difference
with either calls.
Of all the callers, if any, it's the locking bits that would care most
about this -- ie: we end up passing a tsk pointer to a lot of the lock
slowpath, and setting ->state on that. The following numbers are based
on two tests: a custom ad-hoc microbenchmark that just measures
latencies (for ~65 million calls) between get_task_state() vs
get_current_state().
Secondly for a higher overview, an unlink microbenchmark was used,
which pounds on a single file with open, close,unlink combos with
increasing thread counts (up to 4x ncpus). While the workload is quite
unrealistic, it does contend a lot on the inode mutex or now rwsem.
[1] https://lkml.kernel.org/r/1483468021-8237-1-git-send-email-mark.rutland@arm.com
== 1. x86-64 ==
Avg runtime set_task_state(): 601 msecs
Avg runtime set_current_state(): 552 msecs
vanilla dirty
Hmean unlink1-processes-2 36089.26 ( 0.00%) 38977.33 ( 8.00%)
Hmean unlink1-processes-5 28555.01 ( 0.00%) 29832.55 ( 4.28%)
Hmean unlink1-processes-8 37323.75 ( 0.00%) 44974.57 ( 20.50%)
Hmean unlink1-processes-12 43571.88 ( 0.00%) 44283.01 ( 1.63%)
Hmean unlink1-processes-21 34431.52 ( 0.00%) 38284.45 ( 11.19%)
Hmean unlink1-processes-30 34813.26 ( 0.00%) 37975.17 ( 9.08%)
Hmean unlink1-processes-48 37048.90 ( 0.00%) 39862.78 ( 7.59%)
Hmean unlink1-processes-79 35630.01 ( 0.00%) 36855.30 ( 3.44%)
Hmean unlink1-processes-110 36115.85 ( 0.00%) 39843.91 ( 10.32%)
Hmean unlink1-processes-141 32546.96 ( 0.00%) 35418.52 ( 8.82%)
Hmean unlink1-processes-172 34674.79 ( 0.00%) 36899.21 ( 6.42%)
Hmean unlink1-processes-203 37303.11 ( 0.00%) 36393.04 ( -2.44%)
Hmean unlink1-processes-224 35712.13 ( 0.00%) 36685.96 ( 2.73%)
== 2. ppc64le ==
Avg runtime set_task_state(): 938 msecs
Avg runtime set_current_state: 940 msecs
vanilla dirty
Hmean unlink1-processes-2 19269.19 ( 0.00%) 30704.50 ( 59.35%)
Hmean unlink1-processes-5 20106.15 ( 0.00%) 21804.15 ( 8.45%)
Hmean unlink1-processes-8 17496.97 ( 0.00%) 17243.28 ( -1.45%)
Hmean unlink1-processes-12 14224.15 ( 0.00%) 17240.21 ( 21.20%)
Hmean unlink1-processes-21 14155.66 ( 0.00%) 15681.23 ( 10.78%)
Hmean unlink1-processes-30 14450.70 ( 0.00%) 15995.83 ( 10.69%)
Hmean unlink1-processes-48 16945.57 ( 0.00%) 16370.42 ( -3.39%)
Hmean unlink1-processes-79 15788.39 ( 0.00%) 14639.27 ( -7.28%)
Hmean unlink1-processes-110 14268.48 ( 0.00%) 14377.40 ( 0.76%)
Hmean unlink1-processes-141 14023.65 ( 0.00%) 16271.69 ( 16.03%)
Hmean unlink1-processes-172 13417.62 ( 0.00%) 16067.55 ( 19.75%)
Hmean unlink1-processes-203 15293.08 ( 0.00%) 15440.40 ( 0.96%)
Hmean unlink1-processes-234 13719.32 ( 0.00%) 16190.74 ( 18.01%)
Hmean unlink1-processes-265 16400.97 ( 0.00%) 16115.22 ( -1.74%)
Hmean unlink1-processes-296 14388.60 ( 0.00%) 16216.13 ( 12.70%)
Hmean unlink1-processes-320 15771.85 ( 0.00%) 15905.96 ( 0.85%)
x86-64 (known to be fast for get_current()/this_cpu_read_stable() caching)
and ppc64 (with paca) show similar improvements in the unlink microbenches.
The small delta for ppc64 (2ms), does not represent the gains on the unlink
runs. In the case of x86, there was a decent amount of variation in the
latency runs, but always within a 20 to 50ms increase), ppc was more constant.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: mark.rutland@arm.com
Link: http://lkml.kernel.org/r/1483479794-14013-5-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-04 00:43:14 +03:00
|
|
|
set_current_state(state);
|
2013-02-01 14:59:16 +04:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
|
|
|
schedule();
|
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
}
|
2013-02-01 14:59:16 +04:00
|
|
|
/* got the lock */
|
2014-07-16 16:54:55 +04:00
|
|
|
sem->count = -1;
|
2013-02-01 14:59:16 +04:00
|
|
|
list_del(&waiter.list);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2013-02-01 14:59:16 +04:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2016-04-07 18:12:26 +03:00
|
|
|
|
|
|
|
return ret;
|
2017-02-25 03:17:53 +03:00
|
|
|
|
|
|
|
out_nolock:
|
|
|
|
list_del(&waiter.list);
|
locking/rwsem-spinlock: Fix EINTR branch in __down_write_common()
If a writer could been woken up, the above branch
if (sem->count == 0)
break;
would have moved us to taking the sem. So, it's
not the time to wake a writer now, and only readers
are allowed now. Thus, 0 must be passed to __rwsem_do_wake().
Next, __rwsem_do_wake() wakes readers unconditionally.
But we mustn't do that if the sem is owned by writer
in the moment. Otherwise, writer and reader own the sem
the same time, which leads to memory corruption in
callers.
rwsem-xadd.c does not need that, as:
1) the similar check is made lockless there,
2) in __rwsem_mark_wake::try_reader_grant we test,
that sem is not owned by writer.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Niklas Cassel <niklas.cassel@axis.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 17fcbd590d0c "locking/rwsem: Fix down_write_killable() for CONFIG_RWSEM_GENERIC_SPINLOCK=y"
Link: http://lkml.kernel.org/r/149762063282.19811.9129615532201147826.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-16 16:44:34 +03:00
|
|
|
if (!list_empty(&sem->wait_list) && sem->count >= 0)
|
|
|
|
__rwsem_do_wake(sem, 0);
|
2017-02-25 03:17:53 +03:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
|
|
|
|
|
|
|
return -EINTR;
|
2016-04-07 18:12:26 +03:00
|
|
|
}
|
|
|
|
|
|
|
|
void __sched __down_write(struct rw_semaphore *sem)
|
|
|
|
{
|
|
|
|
__down_write_common(sem, TASK_UNINTERRUPTIBLE);
|
|
|
|
}
|
|
|
|
|
|
|
|
int __sched __down_write_killable(struct rw_semaphore *sem)
|
|
|
|
{
|
|
|
|
return __down_write_common(sem, TASK_KILLABLE);
|
2005-04-17 02:20:36 +04:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* trylock for writing -- returns 1 if successful, 0 if contention
|
|
|
|
*/
|
2008-02-08 15:19:55 +03:00
|
|
|
int __down_write_trylock(struct rw_semaphore *sem)
|
2005-04-17 02:20:36 +04:00
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
int ret = 0;
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2014-07-16 16:54:55 +04:00
|
|
|
if (sem->count == 0) {
|
2013-02-01 14:59:16 +04:00
|
|
|
/* got the lock */
|
2014-07-16 16:54:55 +04:00
|
|
|
sem->count = -1;
|
2005-04-17 02:20:36 +04:00
|
|
|
ret = 1;
|
|
|
|
}
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* release a read lock on the semaphore
|
|
|
|
*/
|
2008-02-08 15:19:55 +03:00
|
|
|
void __up_read(struct rw_semaphore *sem)
|
2005-04-17 02:20:36 +04:00
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2014-07-16 16:54:55 +04:00
|
|
|
if (--sem->count == 0 && !list_empty(&sem->wait_list))
|
2005-04-17 02:20:36 +04:00
|
|
|
sem = __rwsem_wake_one_writer(sem);
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* release a write lock on the semaphore
|
|
|
|
*/
|
2008-02-08 15:19:55 +03:00
|
|
|
void __up_write(struct rw_semaphore *sem)
|
2005-04-17 02:20:36 +04:00
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2014-07-16 16:54:55 +04:00
|
|
|
sem->count = 0;
|
2005-04-17 02:20:36 +04:00
|
|
|
if (!list_empty(&sem->wait_list))
|
|
|
|
sem = __rwsem_do_wake(sem, 1);
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* downgrade a write lock into a read lock
|
|
|
|
* - just wake up any readers at the front of the queue
|
|
|
|
*/
|
2008-02-08 15:19:55 +03:00
|
|
|
void __downgrade_write(struct rw_semaphore *sem)
|
2005-04-17 02:20:36 +04:00
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_lock_irqsave(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
|
2014-07-16 16:54:55 +04:00
|
|
|
sem->count = 1;
|
2005-04-17 02:20:36 +04:00
|
|
|
if (!list_empty(&sem->wait_list))
|
|
|
|
sem = __rwsem_do_wake(sem, 0);
|
|
|
|
|
2010-02-24 11:54:54 +03:00
|
|
|
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
|
2005-04-17 02:20:36 +04:00
|
|
|
}
|
|
|
|
|