Pull locking updates from Ingo Molnar:
"The main changes in the locking subsystem in this cycle were:
- Add the Linux Kernel Memory Consistency Model (LKMM) subsystem,
which is an an array of tools in tools/memory-model/ that formally
describe the Linux memory coherency model (a.k.a.
Documentation/memory-barriers.txt), and also produce 'litmus tests'
in form of kernel code which can be directly executed and tested.
Here's a high level background article about an earlier version of
this work on LWN.net:
https://lwn.net/Articles/718628/
The design principles:
"There is reason to believe that Documentation/memory-barriers.txt
could use some help, and a major purpose of this patch is to
provide that help in the form of a design-time tool that can
produce all valid executions of a small fragment of concurrent
Linux-kernel code, which is called a "litmus test". This tool's
functionality is roughly similar to a full state-space search.
Please note that this is a design-time tool, not useful for
regression testing. However, we hope that the underlying
Linux-kernel memory model will be incorporated into other tools
capable of analyzing large bodies of code for regression-testing
purposes."
[...]
"A second tool is klitmus7, which converts litmus tests to
loadable kernel modules for direct testing. As with herd7, the
klitmus7 code is freely available from
http://diy.inria.fr/sources/index.html
(and via "git" at https://github.com/herd/herdtools7)"
[...]
Credits go to:
"This patch was the result of a most excellent collaboration
founded by Jade Alglave and also including Alan Stern, Andrea
Parri, and Luc Maranget."
... and to the gents listed in the MAINTAINERS entry:
LINUX KERNEL MEMORY CONSISTENCY MODEL (LKMM)
M: Alan Stern <stern@rowland.harvard.edu>
M: Andrea Parri <parri.andrea@gmail.com>
M: Will Deacon <will.deacon@arm.com>
M: Peter Zijlstra <peterz@infradead.org>
M: Boqun Feng <boqun.feng@gmail.com>
M: Nicholas Piggin <npiggin@gmail.com>
M: David Howells <dhowells@redhat.com>
M: Jade Alglave <j.alglave@ucl.ac.uk>
M: Luc Maranget <luc.maranget@inria.fr>
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
The LKMM project already found several bugs in Linux locking
primitives and improved the understanding and the documentation of
the Linux memory model all around.
- Add KASAN instrumentation to atomic APIs (Dmitry Vyukov)
- Add RWSEM API debugging and reorganize the lock debugging Kconfig
(Waiman Long)
- ... misc cleanups and other smaller changes"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
locking/Kconfig: Restructure the lock debugging menu
locking/Kconfig: Add LOCK_DEBUGGING_SUPPORT to make it more readable
locking/rwsem: Add DEBUG_RWSEMS to look for lock/unlock mismatches
lockdep: Make the lock debug output more useful
locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter()
locking/atomic, asm-generic, x86: Add comments for atomic instrumentation
locking/atomic, asm-generic: Add KASAN instrumentation to atomic operations
locking/atomic/x86: Switch atomic.h to use atomic-instrumented.h
locking/atomic, asm-generic: Add asm-generic/atomic-instrumented.h
locking/xchg/alpha: Remove superfluous memory barriers from the _local() variants
tools/memory-model: Finish the removal of rb-dep, smp_read_barrier_depends(), and lockless_dereference()
tools/memory-model: Add documentation of new litmus test
tools/memory-model: Remove mention of docker/gentoo image
locking/memory-barriers: De-emphasize smp_read_barrier_depends() some more
locking/lockdep: Show unadorned pointers
mutex: Drop linkage.h from mutex.h
tools/memory-model: Remove rb-dep, smp_read_barrier_depends, and lockless_dereference
tools/memory-model: Convert underscores to hyphens
tools/memory-model: Add a S lock-based external-view litmus test
tools/memory-model: Add required herd7 version to README file
...
Linus Torvalds
701f3b3149