linux/tools/memory-model, branch v5.9

Merge tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-08-03T21:39:35Z

Pull locking updates from Ingo Molnar: - LKMM updates: mostly documentation changes, but also some new litmus tests for atomic ops. - KCSAN updates: the most important change is that GCC 11 now has all fixes in place to support KCSAN, so GCC support can be enabled again. Also more annotations. - futex updates: minor cleanups and simplifications - seqlock updates: merge preparatory changes/cleanups for the 'associated locks' facilities. - lockdep updates: - simplify IRQ trace event handling - add various new debug checks - simplify header dependencies, split out , decouple lockdep from other low level headers some more - fix NMI handling - misc cleanups and smaller fixes * tag 'locking-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) kcsan: Improve IRQ state trace reporting lockdep: Refactor IRQ trace events fields into struct seqlock: lockdep assert non-preemptibility on seqcount_t write lockdep: Add preemption enabled/disabled assertion APIs seqlock: Implement raw_seqcount_begin() in terms of raw_read_seqcount() seqlock: Add kernel-doc for seqcount_t and seqlock_t APIs seqlock: Reorder seqcount_t and seqlock_t API definitions seqlock: seqcount_t latch: End read sections with read_seqcount_retry() seqlock: Properly format kernel-doc code samples Documentation: locking: Describe seqlock design and usage locking/qspinlock: Do not include atomic.h from qspinlock_types.h locking/atomic: Move ATOMIC_INIT into linux/types.h lockdep: Move list.h inclusion into lockdep.h locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIs futex: Remove unused or redundant includes futex: Consistently use fshared as boolean futex: Remove needless goto's futex: Remove put_futex_key() rwsem: fix commas in initialisation docs: locking: Replace HTTP links with HTTPS ones ...

tools/memory-model: Remove smp_read_barrier_depends() from informal doc

2020-07-21T09:50:37Z

smp_read_barrier_depends() has gone the way of mmiowb() and so many esoteric memory barriers before it. Drop the two mentions of this deceased barrier from the LKMM informal explanation document. Acked-by: Peter Zijlstra (Intel) Acked-by: Alan Stern Acked-by: Paul E. McKenney Signed-off-by: Will Deacon

tools/memory-model/README: Mention herdtools7 7.56 in compatibility table

2020-06-29T19:05:18Z

herdtools7 7.56 is going to be released in the week of 22 Jun 2020. This commit therefore adds the exact version in the compatibility table. Acked-by: Andrea Parri Signed-off-by: Akira Yokosawa Signed-off-by: Paul E. McKenney

tools/memory-model/README: Expand dependency of klitmus7

2020-06-29T19:05:18Z

klitmus7 is independent of the memory model but depends on the build-target kernel release. It occasionally lost compatibility due to kernel API changes [1, 2, 3]. It was remedied in a backwards-compatible manner respectively [4, 5, 6]. Reflect this fact in README. [1]: b899a850431e ("compiler.h: Remove ACCESS_ONCE()") [2]: 0bb95f80a38f ("Makefile: Globally enable VLA warning") [3]: d56c0d45f0e2 ("proc: decouple proc from VFS with "struct proc_ops"") [4]: https://github.com/herd/herdtools7/commit/e87d7f9287d1 ("klitmus: Use WRITE_ONCE and READ_ONCE in place of deprecated ACCESS_ONCE") [5]: https://github.com/herd/herdtools7/commit/a0cbb10d02be ("klitmus: Avoid variable length array") [6]: https://github.com/herd/herdtools7/commit/46b9412d3a58 ("klitmus: Linux kernel v5.6.x compat") NOTE: [5] was ahead of herdtools7 7.53, which did not make an official release. Code generated by klitmus7 without [5] can still be built targeting Linux 4.20--5.5 if you don't care VLA warnings. Acked-by: Andrea Parri Signed-off-by: Akira Yokosawa Signed-off-by: Paul E. McKenney

tools/memory-model: Fix reference to litmus test in recipes.txt

2020-06-29T19:05:18Z

The name of litmus test doesn't match the one described below. Fix the name of litmus test. Acked-by: Andrea Parri Acked-by: Joel Fernandes (Google) Signed-off-by: Akira Yokosawa Signed-off-by: Paul E. McKenney

tools/memory-model: Add an exception for limitations on _unless() family

2020-06-29T19:05:18Z

According to Luc, atomic_add_unless() is directly provided by herd7, therefore it can be used in litmus tests. So change the limitation section in README to unlimit the use of atomic_add_unless(). Cc: Luc Maranget Acked-by: Andrea Parri Reviewed-by: Joel Fernandes (Google) Signed-off-by: Boqun Feng Signed-off-by: Paul E. McKenney

tools/memory-model: Fix "conflict" definition

2020-06-29T19:05:17Z

The definition of "conflict" should not include the type of access nor whether the accesses are concurrent or not, which this patch addresses. The definition of "data race" remains unchanged. The definition of "conflict" as we know it and is cited by various papers on memory consistency models appeared in [1]: "Two accesses to the same variable conflict if at least one is a write; two operations conflict if they execute conflicting accesses." The LKMM as well as the C11 memory model are adaptations of data-race-free, which are based on the work in [2]. Necessarily, we need both conflicting data operations (plain) and synchronization operations (marked). For example, C11's definition is based on [3], which defines a "data race" as: "Two memory operations conflict if they access the same memory location, and at least one of them is a store, atomic store, or atomic read-modify-write operation. In a sequentially consistent execution, two memory operations from different threads form a type 1 data race if they conflict, at least one of them is a data operation, and they are adjacent in Co-developed-by: Alan Stern Signed-off-by: Alan Stern Acked-by: Andrea Parri Signed-off-by: Paul E. McKenney

tools/memory-model: Add recent references

2020-06-29T19:05:17Z

This commit updates the list of LKMM-related publications in Documentation/references.txt. Signed-off-by: Paul E. McKenney Acked-by: Andrea Parri

.gitignore: add SPDX License Identifier

2020-03-25T10:50:48Z

Add SPDX License Identifier to all .gitignore files. Signed-off-by: Masahiro Yamada Signed-off-by: Greg Kroah-Hartman

tools/memory-model/Documentation: Add plain accesses and data races to explanation.txt

2019-10-05T18:59:44Z

This patch updates the Linux Kernel Memory Model's explanation.txt file by adding a section devoted to the model's handling of plain accesses and data-race detection. Signed-off-by: Alan Stern Acked-by: Andrea Parri Signed-off-by: Paul E. McKenney