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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
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>
602 lines
16 KiB
C
602 lines
16 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_SEQLOCK_H
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#define __LINUX_SEQLOCK_H
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/*
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* Reader/writer consistent mechanism without starving writers. This type of
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* lock for data where the reader wants a consistent set of information
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* and is willing to retry if the information changes. There are two types
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* of readers:
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* 1. Sequence readers which never block a writer but they may have to retry
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* if a writer is in progress by detecting change in sequence number.
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* Writers do not wait for a sequence reader.
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* 2. Locking readers which will wait if a writer or another locking reader
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* is in progress. A locking reader in progress will also block a writer
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* from going forward. Unlike the regular rwlock, the read lock here is
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* exclusive so that only one locking reader can get it.
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*
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* This is not as cache friendly as brlock. Also, this may not work well
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* for data that contains pointers, because any writer could
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* invalidate a pointer that a reader was following.
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*
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* Expected non-blocking reader usage:
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* do {
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* seq = read_seqbegin(&foo);
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* ...
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* } while (read_seqretry(&foo, seq));
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*
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*
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* On non-SMP the spin locks disappear but the writer still needs
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* to increment the sequence variables because an interrupt routine could
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* change the state of the data.
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*
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* Based on x86_64 vsyscall gettimeofday
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* by Keith Owens and Andrea Arcangeli
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*/
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#include <linux/spinlock.h>
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#include <linux/preempt.h>
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#include <linux/lockdep.h>
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#include <linux/compiler.h>
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#include <asm/processor.h>
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/*
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* Version using sequence counter only.
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* This can be used when code has its own mutex protecting the
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* updating starting before the write_seqcountbeqin() and ending
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* after the write_seqcount_end().
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*/
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typedef struct seqcount {
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unsigned sequence;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lockdep_map dep_map;
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#endif
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} seqcount_t;
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static inline void __seqcount_init(seqcount_t *s, const char *name,
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struct lock_class_key *key)
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{
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/*
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* Make sure we are not reinitializing a held lock:
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*/
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lockdep_init_map(&s->dep_map, name, key, 0);
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s->sequence = 0;
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}
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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# define SEQCOUNT_DEP_MAP_INIT(lockname) \
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.dep_map = { .name = #lockname } \
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# define seqcount_init(s) \
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do { \
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static struct lock_class_key __key; \
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__seqcount_init((s), #s, &__key); \
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} while (0)
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static inline void seqcount_lockdep_reader_access(const seqcount_t *s)
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{
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seqcount_t *l = (seqcount_t *)s;
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unsigned long flags;
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local_irq_save(flags);
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seqcount_acquire_read(&l->dep_map, 0, 0, _RET_IP_);
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seqcount_release(&l->dep_map, 1, _RET_IP_);
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local_irq_restore(flags);
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}
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#else
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# define SEQCOUNT_DEP_MAP_INIT(lockname)
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# define seqcount_init(s) __seqcount_init(s, NULL, NULL)
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# define seqcount_lockdep_reader_access(x)
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#endif
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#define SEQCNT_ZERO(lockname) { .sequence = 0, SEQCOUNT_DEP_MAP_INIT(lockname)}
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/**
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* __read_seqcount_begin - begin a seq-read critical section (without barrier)
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* @s: pointer to seqcount_t
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* Returns: count to be passed to read_seqcount_retry
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*
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* __read_seqcount_begin is like read_seqcount_begin, but has no smp_rmb()
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* barrier. Callers should ensure that smp_rmb() or equivalent ordering is
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* provided before actually loading any of the variables that are to be
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* protected in this critical section.
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*
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* Use carefully, only in critical code, and comment how the barrier is
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* provided.
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*/
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static inline unsigned __read_seqcount_begin(const seqcount_t *s)
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{
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unsigned ret;
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repeat:
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ret = READ_ONCE(s->sequence);
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if (unlikely(ret & 1)) {
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cpu_relax();
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goto repeat;
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}
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return ret;
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}
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/**
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* raw_read_seqcount - Read the raw seqcount
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* @s: pointer to seqcount_t
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* Returns: count to be passed to read_seqcount_retry
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*
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* raw_read_seqcount opens a read critical section of the given
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* seqcount without any lockdep checking and without checking or
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* masking the LSB. Calling code is responsible for handling that.
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*/
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static inline unsigned raw_read_seqcount(const seqcount_t *s)
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{
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unsigned ret = READ_ONCE(s->sequence);
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smp_rmb();
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return ret;
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}
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/**
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* raw_read_seqcount_begin - start seq-read critical section w/o lockdep
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* @s: pointer to seqcount_t
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* Returns: count to be passed to read_seqcount_retry
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*
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* raw_read_seqcount_begin opens a read critical section of the given
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* seqcount, but without any lockdep checking. Validity of the critical
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* section is tested by checking read_seqcount_retry function.
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*/
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static inline unsigned raw_read_seqcount_begin(const seqcount_t *s)
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{
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unsigned ret = __read_seqcount_begin(s);
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smp_rmb();
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return ret;
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}
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/**
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* read_seqcount_begin - begin a seq-read critical section
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* @s: pointer to seqcount_t
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* Returns: count to be passed to read_seqcount_retry
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*
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* read_seqcount_begin opens a read critical section of the given seqcount.
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* Validity of the critical section is tested by checking read_seqcount_retry
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* function.
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*/
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static inline unsigned read_seqcount_begin(const seqcount_t *s)
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{
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seqcount_lockdep_reader_access(s);
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return raw_read_seqcount_begin(s);
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}
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/**
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* raw_seqcount_begin - begin a seq-read critical section
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* @s: pointer to seqcount_t
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* Returns: count to be passed to read_seqcount_retry
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*
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* raw_seqcount_begin opens a read critical section of the given seqcount.
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* Validity of the critical section is tested by checking read_seqcount_retry
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* function.
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*
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* Unlike read_seqcount_begin(), this function will not wait for the count
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* to stabilize. If a writer is active when we begin, we will fail the
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* read_seqcount_retry() instead of stabilizing at the beginning of the
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* critical section.
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*/
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static inline unsigned raw_seqcount_begin(const seqcount_t *s)
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{
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unsigned ret = READ_ONCE(s->sequence);
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smp_rmb();
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return ret & ~1;
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}
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/**
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* __read_seqcount_retry - end a seq-read critical section (without barrier)
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* @s: pointer to seqcount_t
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* @start: count, from read_seqcount_begin
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* Returns: 1 if retry is required, else 0
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*
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* __read_seqcount_retry is like read_seqcount_retry, but has no smp_rmb()
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* barrier. Callers should ensure that smp_rmb() or equivalent ordering is
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* provided before actually loading any of the variables that are to be
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* protected in this critical section.
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*
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* Use carefully, only in critical code, and comment how the barrier is
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* provided.
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*/
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static inline int __read_seqcount_retry(const seqcount_t *s, unsigned start)
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{
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return unlikely(s->sequence != start);
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}
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/**
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* read_seqcount_retry - end a seq-read critical section
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* @s: pointer to seqcount_t
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* @start: count, from read_seqcount_begin
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* Returns: 1 if retry is required, else 0
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*
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* read_seqcount_retry closes a read critical section of the given seqcount.
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* If the critical section was invalid, it must be ignored (and typically
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* retried).
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*/
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static inline int read_seqcount_retry(const seqcount_t *s, unsigned start)
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{
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smp_rmb();
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return __read_seqcount_retry(s, start);
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}
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static inline void raw_write_seqcount_begin(seqcount_t *s)
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{
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s->sequence++;
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smp_wmb();
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}
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static inline void raw_write_seqcount_end(seqcount_t *s)
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{
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smp_wmb();
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s->sequence++;
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}
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/**
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* raw_write_seqcount_barrier - do a seq write barrier
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* @s: pointer to seqcount_t
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*
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* This can be used to provide an ordering guarantee instead of the
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* usual consistency guarantee. It is one wmb cheaper, because we can
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* collapse the two back-to-back wmb()s.
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*
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* seqcount_t seq;
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* bool X = true, Y = false;
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*
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* void read(void)
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* {
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* bool x, y;
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*
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* do {
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* int s = read_seqcount_begin(&seq);
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*
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* x = X; y = Y;
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*
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* } while (read_seqcount_retry(&seq, s));
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*
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* BUG_ON(!x && !y);
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* }
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*
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* void write(void)
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* {
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* Y = true;
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*
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* raw_write_seqcount_barrier(seq);
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*
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* X = false;
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* }
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*/
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static inline void raw_write_seqcount_barrier(seqcount_t *s)
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{
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s->sequence++;
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smp_wmb();
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s->sequence++;
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}
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static inline int raw_read_seqcount_latch(seqcount_t *s)
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{
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int seq = READ_ONCE(s->sequence);
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/* Pairs with the first smp_wmb() in raw_write_seqcount_latch() */
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smp_read_barrier_depends();
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return seq;
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}
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/**
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* raw_write_seqcount_latch - redirect readers to even/odd copy
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* @s: pointer to seqcount_t
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*
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* The latch technique is a multiversion concurrency control method that allows
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* queries during non-atomic modifications. If you can guarantee queries never
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* interrupt the modification -- e.g. the concurrency is strictly between CPUs
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* -- you most likely do not need this.
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*
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* Where the traditional RCU/lockless data structures rely on atomic
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* modifications to ensure queries observe either the old or the new state the
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* latch allows the same for non-atomic updates. The trade-off is doubling the
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* cost of storage; we have to maintain two copies of the entire data
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* structure.
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*
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* Very simply put: we first modify one copy and then the other. This ensures
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* there is always one copy in a stable state, ready to give us an answer.
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*
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* The basic form is a data structure like:
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*
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* struct latch_struct {
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* seqcount_t seq;
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* struct data_struct data[2];
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* };
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*
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* Where a modification, which is assumed to be externally serialized, does the
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* following:
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*
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* void latch_modify(struct latch_struct *latch, ...)
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* {
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* smp_wmb(); <- Ensure that the last data[1] update is visible
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* latch->seq++;
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* smp_wmb(); <- Ensure that the seqcount update is visible
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*
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* modify(latch->data[0], ...);
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*
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* smp_wmb(); <- Ensure that the data[0] update is visible
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* latch->seq++;
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* smp_wmb(); <- Ensure that the seqcount update is visible
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*
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* modify(latch->data[1], ...);
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* }
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*
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* The query will have a form like:
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*
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* struct entry *latch_query(struct latch_struct *latch, ...)
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* {
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* struct entry *entry;
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* unsigned seq, idx;
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*
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* do {
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* seq = raw_read_seqcount_latch(&latch->seq);
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*
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* idx = seq & 0x01;
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* entry = data_query(latch->data[idx], ...);
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*
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* smp_rmb();
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* } while (seq != latch->seq);
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*
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* return entry;
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* }
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*
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* So during the modification, queries are first redirected to data[1]. Then we
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* modify data[0]. When that is complete, we redirect queries back to data[0]
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* and we can modify data[1].
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*
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* NOTE: The non-requirement for atomic modifications does _NOT_ include
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* the publishing of new entries in the case where data is a dynamic
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* data structure.
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*
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* An iteration might start in data[0] and get suspended long enough
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* to miss an entire modification sequence, once it resumes it might
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* observe the new entry.
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*
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* NOTE: When data is a dynamic data structure; one should use regular RCU
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* patterns to manage the lifetimes of the objects within.
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*/
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static inline void raw_write_seqcount_latch(seqcount_t *s)
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{
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smp_wmb(); /* prior stores before incrementing "sequence" */
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s->sequence++;
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smp_wmb(); /* increment "sequence" before following stores */
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}
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/*
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* Sequence counter only version assumes that callers are using their
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* own mutexing.
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*/
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static inline void write_seqcount_begin_nested(seqcount_t *s, int subclass)
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{
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raw_write_seqcount_begin(s);
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seqcount_acquire(&s->dep_map, subclass, 0, _RET_IP_);
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}
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static inline void write_seqcount_begin(seqcount_t *s)
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{
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write_seqcount_begin_nested(s, 0);
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}
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static inline void write_seqcount_end(seqcount_t *s)
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{
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seqcount_release(&s->dep_map, 1, _RET_IP_);
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raw_write_seqcount_end(s);
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}
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/**
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* write_seqcount_invalidate - invalidate in-progress read-side seq operations
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* @s: pointer to seqcount_t
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*
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* After write_seqcount_invalidate, no read-side seq operations will complete
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* successfully and see data older than this.
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*/
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static inline void write_seqcount_invalidate(seqcount_t *s)
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{
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smp_wmb();
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s->sequence+=2;
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}
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typedef struct {
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struct seqcount seqcount;
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spinlock_t lock;
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} seqlock_t;
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/*
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* These macros triggered gcc-3.x compile-time problems. We think these are
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* OK now. Be cautious.
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*/
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#define __SEQLOCK_UNLOCKED(lockname) \
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{ \
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.seqcount = SEQCNT_ZERO(lockname), \
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.lock = __SPIN_LOCK_UNLOCKED(lockname) \
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}
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#define seqlock_init(x) \
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do { \
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seqcount_init(&(x)->seqcount); \
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spin_lock_init(&(x)->lock); \
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} while (0)
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|
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#define DEFINE_SEQLOCK(x) \
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seqlock_t x = __SEQLOCK_UNLOCKED(x)
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|
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/*
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* Read side functions for starting and finalizing a read side section.
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|
*/
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static inline unsigned read_seqbegin(const seqlock_t *sl)
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|
{
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return read_seqcount_begin(&sl->seqcount);
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|
}
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|
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static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start)
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|
{
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|
return read_seqcount_retry(&sl->seqcount, start);
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|
}
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|
|
|
/*
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* Lock out other writers and update the count.
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|
* Acts like a normal spin_lock/unlock.
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|
* Don't need preempt_disable() because that is in the spin_lock already.
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|
*/
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|
static inline void write_seqlock(seqlock_t *sl)
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|
{
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|
spin_lock(&sl->lock);
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write_seqcount_begin(&sl->seqcount);
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|
}
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|
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|
static inline void write_sequnlock(seqlock_t *sl)
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|
{
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|
write_seqcount_end(&sl->seqcount);
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|
spin_unlock(&sl->lock);
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|
}
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|
|
|
static inline void write_seqlock_bh(seqlock_t *sl)
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|
{
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|
spin_lock_bh(&sl->lock);
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|
write_seqcount_begin(&sl->seqcount);
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|
}
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|
|
|
static inline void write_sequnlock_bh(seqlock_t *sl)
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|
{
|
|
write_seqcount_end(&sl->seqcount);
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|
spin_unlock_bh(&sl->lock);
|
|
}
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|
|
|
static inline void write_seqlock_irq(seqlock_t *sl)
|
|
{
|
|
spin_lock_irq(&sl->lock);
|
|
write_seqcount_begin(&sl->seqcount);
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|
}
|
|
|
|
static inline void write_sequnlock_irq(seqlock_t *sl)
|
|
{
|
|
write_seqcount_end(&sl->seqcount);
|
|
spin_unlock_irq(&sl->lock);
|
|
}
|
|
|
|
static inline unsigned long __write_seqlock_irqsave(seqlock_t *sl)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&sl->lock, flags);
|
|
write_seqcount_begin(&sl->seqcount);
|
|
return flags;
|
|
}
|
|
|
|
#define write_seqlock_irqsave(lock, flags) \
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|
do { flags = __write_seqlock_irqsave(lock); } while (0)
|
|
|
|
static inline void
|
|
write_sequnlock_irqrestore(seqlock_t *sl, unsigned long flags)
|
|
{
|
|
write_seqcount_end(&sl->seqcount);
|
|
spin_unlock_irqrestore(&sl->lock, flags);
|
|
}
|
|
|
|
/*
|
|
* A locking reader exclusively locks out other writers and locking readers,
|
|
* but doesn't update the sequence number. Acts like a normal spin_lock/unlock.
|
|
* Don't need preempt_disable() because that is in the spin_lock already.
|
|
*/
|
|
static inline void read_seqlock_excl(seqlock_t *sl)
|
|
{
|
|
spin_lock(&sl->lock);
|
|
}
|
|
|
|
static inline void read_sequnlock_excl(seqlock_t *sl)
|
|
{
|
|
spin_unlock(&sl->lock);
|
|
}
|
|
|
|
/**
|
|
* read_seqbegin_or_lock - begin a sequence number check or locking block
|
|
* @lock: sequence lock
|
|
* @seq : sequence number to be checked
|
|
*
|
|
* First try it once optimistically without taking the lock. If that fails,
|
|
* take the lock. The sequence number is also used as a marker for deciding
|
|
* whether to be a reader (even) or writer (odd).
|
|
* N.B. seq must be initialized to an even number to begin with.
|
|
*/
|
|
static inline void read_seqbegin_or_lock(seqlock_t *lock, int *seq)
|
|
{
|
|
if (!(*seq & 1)) /* Even */
|
|
*seq = read_seqbegin(lock);
|
|
else /* Odd */
|
|
read_seqlock_excl(lock);
|
|
}
|
|
|
|
static inline int need_seqretry(seqlock_t *lock, int seq)
|
|
{
|
|
return !(seq & 1) && read_seqretry(lock, seq);
|
|
}
|
|
|
|
static inline void done_seqretry(seqlock_t *lock, int seq)
|
|
{
|
|
if (seq & 1)
|
|
read_sequnlock_excl(lock);
|
|
}
|
|
|
|
static inline void read_seqlock_excl_bh(seqlock_t *sl)
|
|
{
|
|
spin_lock_bh(&sl->lock);
|
|
}
|
|
|
|
static inline void read_sequnlock_excl_bh(seqlock_t *sl)
|
|
{
|
|
spin_unlock_bh(&sl->lock);
|
|
}
|
|
|
|
static inline void read_seqlock_excl_irq(seqlock_t *sl)
|
|
{
|
|
spin_lock_irq(&sl->lock);
|
|
}
|
|
|
|
static inline void read_sequnlock_excl_irq(seqlock_t *sl)
|
|
{
|
|
spin_unlock_irq(&sl->lock);
|
|
}
|
|
|
|
static inline unsigned long __read_seqlock_excl_irqsave(seqlock_t *sl)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&sl->lock, flags);
|
|
return flags;
|
|
}
|
|
|
|
#define read_seqlock_excl_irqsave(lock, flags) \
|
|
do { flags = __read_seqlock_excl_irqsave(lock); } while (0)
|
|
|
|
static inline void
|
|
read_sequnlock_excl_irqrestore(seqlock_t *sl, unsigned long flags)
|
|
{
|
|
spin_unlock_irqrestore(&sl->lock, flags);
|
|
}
|
|
|
|
static inline unsigned long
|
|
read_seqbegin_or_lock_irqsave(seqlock_t *lock, int *seq)
|
|
{
|
|
unsigned long flags = 0;
|
|
|
|
if (!(*seq & 1)) /* Even */
|
|
*seq = read_seqbegin(lock);
|
|
else /* Odd */
|
|
read_seqlock_excl_irqsave(lock, flags);
|
|
|
|
return flags;
|
|
}
|
|
|
|
static inline void
|
|
done_seqretry_irqrestore(seqlock_t *lock, int seq, unsigned long flags)
|
|
{
|
|
if (seq & 1)
|
|
read_sequnlock_excl_irqrestore(lock, flags);
|
|
}
|
|
#endif /* __LINUX_SEQLOCK_H */
|