Changes in README

c438b7d8 - tools/memory-model: litmus: Add two tests for unlock(A)+lock(B) ordering

Mon, 25 Oct 2021 14:54:16 +0000

tools/memory-model: litmus: Add two tests for unlock(A)+lock(B) orderingThe memory model has been updated to provide a stronger orderingguarantee for unlock(A)+lock(B) on the same CPU/thread. Therefore addtwo litmus tests describing this new guarantee, these tests are simpleyet can clearly show the usage of the new guarantee, also they can serveas the self tests for the modification in the model.Co-developed-by: Alan Stern Signed-off-by: Alan Stern Signed-off-by: Boqun Feng Acked-by: Peter Zijlstra (Intel) Signed-off-by: Paul E. McKenney List of files: /linux-6.15/tools/memory-model/litmus-tests/README

37c600a3 - tools/memory-model: Do not use "herd" to refer to "herd7"

Tue, 19 Feb 2019 22:55:23 +0000

tools/memory-model: Do not use "herd" to refer to "herd7"Use "herd7" in each such reference.Signed-off-by: Andrea Parri Cc: Will Deacon Cc: Peter Zijlstra Cc: Boqun Feng Cc: Nicholas Piggin Cc: David Howells Cc: Jade Alglave Cc: Luc Maranget Cc: "Paul E. McKenney" Cc: Akira Yokosawa Cc: Daniel Lustig Acked-by: Alan Stern Signed-off-by: Paul E. McKenney List of files: /linux-6.15/tools/memory-model/litmus-tests/README

c4f790f2 - tools/memory-model: Add litmus-test naming scheme

Wed, 26 Sep 2018 18:29:16 +0000

tools/memory-model: Add litmus-test naming schemeThis commit documents the scheme used to generate the names for thelitmus tests.[ paulmck: Apply feedback from Andrea Parri and Will Deacon. ]Signed-off-by: Paul E. McKenney Acked-by: Will Deacon Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: akiyks@gmail.comCc: boqun.feng@gmail.comCc: dhowells@redhat.comCc: j.alglave@ucl.ac.ukCc: linux-arch@vger.kernel.orgCc: luc.maranget@inria.frCc: npiggin@gmail.comCc: parri.andrea@gmail.comCc: stern@rowland.harvard.eduLink: http://lkml.kernel.org/r/20180926182920.27644-1-paulmck@linux.ibm.comSigned-off-by: Ingo Molnar List of files: /linux-6.15/tools/memory-model/litmus-tests/README

71b7ff5e - tools/memory-model: Rename litmus tests to comply to norm7

Mon, 16 Jul 2018 18:06:05 +0000

tools/memory-model: Rename litmus tests to comply to norm7norm7 produces the 'normalized' name of a litmus test, when the testcan be generated from a single cycle that passes through each processexactly once. The commit renames such tests in order to comply to thenaming scheme implemented by this tool.Signed-off-by: Andrea Parri Signed-off-by: Paul E. McKenney Acked-by: Alan Stern Cc: Akira Yokosawa Cc: Boqun Feng Cc: David Howells Cc: Jade Alglave Cc: Linus Torvalds Cc: Luc Maranget Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-arch@vger.kernel.orgCc: parri.andrea@gmail.comLink: http://lkml.kernel.org/r/20180716180605.16115-14-paulmck@linux.vnet.ibm.comSigned-off-by: Ingo Molnar List of files: /linux-6.15/tools/memory-model/litmus-tests/README

b4648189 - tools/memory-model: Add litmus test for full multicopy atomicity

Mon, 16 Jul 2018 18:05:52 +0000

tools/memory-model: Add litmus test for full multicopy atomicityThis commit adds a litmus test suggested by Alan Stern that is forbiddenon fully multicopy atomic systems, but allowed on other-multicopy andon non-multicopy atomic systems. For reference, s390 is fully multicopyatomic, x86 and ARMv8 are other-multicopy atomic, and ARMv7 and powerpcare non-multicopy atomic.Suggested-by: Alan Stern Signed-off-by: Paul E. McKenney Acked-by: Alan Stern Acked-by: Andrea Parri Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: akiyks@gmail.comCc: boqun.feng@gmail.comCc: dhowells@redhat.comCc: j.alglave@ucl.ac.ukCc: linux-arch@vger.kernel.orgCc: luc.maranget@inria.frCc: npiggin@gmail.comCc: parri.andrea@gmail.comCc: will.deacon@arm.comLink: http://lkml.kernel.org/r/20180716180605.16115-1-paulmck@linux.vnet.ibm.comSigned-off-by: Ingo Molnar List of files: /linux-6.15/tools/memory-model/litmus-tests/README

1bd37420 - tools/memory-model: Flag "cumulativity" and "propagation" tests

Mon, 14 May 2018 23:33:49 +0000

tools/memory-model: Flag "cumulativity" and "propagation" testsThis commit flags WRC+pooncerelease+rmbonceonce+Once.litmusas being forbidden by smp_store_release() A-cumulativity andIRIW+mbonceonces+OnceOnce.litmus as being forbidden by the LKMMpropagation rule.Suggested-by: Andrea Parri Reported-by: Paolo Bonzini [ paulmck: Updated wording as suggested by Alan Stern. ]Signed-off-by: Paul E. McKenney Acked-by: Alan Stern Cc: Andrew Morton Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: akiyks@gmail.comCc: boqun.feng@gmail.comCc: dhowells@redhat.comCc: j.alglave@ucl.ac.ukCc: linux-arch@vger.kernel.orgCc: luc.maranget@inria.frCc: npiggin@gmail.comCc: parri.andrea@gmail.comLink: http://lkml.kernel.org/r/1526340837-12222-11-git-send-email-paulmck@linux.vnet.ibm.comSigned-off-by: Ingo Molnar List of files: /linux-6.15/tools/memory-model/litmus-tests/README

15553dcb - tools/memory-model: Add model support for spin_is_locked()

Mon, 14 May 2018 23:33:48 +0000

tools/memory-model: Add model support for spin_is_locked()This commit first adds a trivial macro for spin_is_locked() tolinux-kernel.def.It also adds cat code for enumerating all possible matches of lockwrite events (set LKW) with islocked events returning true (set RL,for Read from Lock), and unlock write events (set UL) with islockedevents returning false (set RU, for Read from Unlock). Note that thisintentionally does not model uniprocessor kernels (CONFIG_SMP=n) builtwith CONFIG_DEBUG_SPINLOCK=n, in which spin_is_locked() unconditionallyreturns zero.It also adds a pair of litmus tests demonstrating the minimal orderingprovided by spin_is_locked() in conjunction with spin_lock(). Will Deaconnoted that this minimal ordering happens on ARMv8:https://lkml.kernel.org/r/20180226162426.GB17158@arm.comNotice that herd7 installations strictly older than version 7.49do not handle the new constructs.Signed-off-by: Luc Maranget Signed-off-by: Paul E. McKenney Reviewed-by: Alan Stern Cc: Akira Yokosawa Cc: Andrea Parri Cc: Andrew Morton Cc: Boqun Feng Cc: David Howells Cc: Jade Alglave Cc: Linus Torvalds Cc: Luc Maranget Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-arch@vger.kernel.orgLink: http://lkml.kernel.org/r/1526340837-12222-10-git-send-email-paulmck@linux.vnet.ibm.comSigned-off-by: Ingo Molnar List of files: /linux-6.15/tools/memory-model/litmus-tests/README

ff1fe5e0 - tools/memory-model: Add documentation of new litmus test

Wed, 07 Mar 2018 17:27:39 +0000

tools/memory-model: Add documentation of new litmus testThe litmus-tests/README file lacks any mention of the new litmus testISA2+pooncelock+pooncelock+pombonce.litmus. This commit thereforeadds a description of this test.Reported-by: Alan Stern Signed-off-by: Paul E. McKenney Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: akiyks@gmail.comCc: boqun.feng@gmail.comCc: dhowells@redhat.comCc: j.alglave@ucl.ac.ukCc: linux-arch@vger.kernel.orgCc: luc.maranget@inria.frCc: npiggin@gmail.comCc: parri.andrea@gmail.comCc: will.deacon@arm.comLink: http://lkml.kernel.org/r/1520443660-16858-3-git-send-email-paulmck@linux.vnet.ibm.comSigned-off-by: Ingo Molnar List of files: /linux-6.15/tools/memory-model/litmus-tests/README

62155147 - README: Fix a couple of punctuation errors

Tue, 20 Feb 2018 23:25:05 +0000

README: Fix a couple of punctuation errorsSigned-off-by: Paul E. McKenney Acked-by: Peter Zijlstra Cc: Linus Torvalds Cc: Thomas Gleixner Cc: akiyks@gmail.comCc: boqun.feng@gmail.comCc: dhowells@redhat.comCc: j.alglave@ucl.ac.ukCc: linux-arch@vger.kernel.orgCc: luc.maranget@inria.frCc: nborisov@suse.comCc: npiggin@gmail.comCc: parri.andrea@gmail.comCc: stern@rowland.harvard.eduCc: will.deacon@arm.comLink: http://lkml.kernel.org/r/1519169112-20593-5-git-send-email-paulmck@linux.vnet.ibm.comSigned-off-by: Ingo Molnar List of files: /linux-6.15/tools/memory-model/litmus-tests/README

1c27b644 - Automate memory-barriers.txt; provide Linux-kernel memory model

Fri, 19 Jan 2018 03:58:55 +0000

Automate memory-barriers.txt; provide Linux-kernel memory modelThere is some reason to believe that Documentation/memory-barriers.txtcould use some help, and a major purpose of this patch is to providethat help in the form of a design-time tool that can produce all validexecutions of a small fragment of concurrent Linux-kernel code, which iscalled a "litmus test". This tool's functionality is roughly similar toa full state-space search. Please note that this is a design-time tool,not useful for regression testing. However, we hope that the underlyingLinux-kernel memory model will be incorporated into other tools capableof analyzing large bodies of code for regression-testing purposes.The main tool is herd7, together with the linux-kernel.bell,linux-kernel.cat, linux-kernel.cfg, linux-kernel.def, and lock.cat filesadded by this patch. The herd7 executable takes the other files as input,and all of these files collectively define the Linux-kernel memory memorymodel. A brief description of each of these other files is providedin the README file. Although this tool does have its limitations,which are documented in the README file, it does improve on the versionreported on in the LWN series (https://lwn.net/Articles/718628/ andhttps://lwn.net/Articles/720550/) by supporting locking and arithmetic,including a much wider variety of read-modify-write atomic operations.Please note that herd7 is not part of this submission, but is freelyavailable from http://diy.inria.fr/sources/index.html (and via "git"at https://github.com/herd/herdtools7).A second tool is klitmus7, which converts litmus tests to loadablekernel modules for direct testing. As with herd7, the klitmus7code is freely available from http://diy.inria.fr/sources/index.html(and via "git" at https://github.com/herd/herdtools7).Of course, litmus tests are not always the best way to fully understand amemory model, so this patch also includes Documentation/explanation.txt,which describes the memory model in detail. In addition,Documentation/recipes.txt provides example known-good and known-bad usecases for those who prefer working by example.This patch also includes a few sample litmus tests, and a great manymore litmus tests are available at https://github.com/paulmckrcu/litmus.This patch was the result of a most excellent collaboration foundedby Jade Alglave and also including Alan Stern, Andrea Parri, and LucMaranget. For more details on the history of this collaboration, pleaserefer to the Linux-kernel memory model presentations at 2016 LinuxCon EU,2016 Kernel Summit, 2016 Linux Plumbers Conference, 2017 linux.conf.au,or 2017 Linux Plumbers Conference microconference. However, one aspectof the history does bear repeating due to weak copyright tracking earlierin this project, which extends back to early 2015. This weakness cameto light in late 2017 after an LKMM presentation by Paul in which anaudience member noted the similarity of some LKMM code to code in earlypublished papers. This prompted a copyright review.From Alan Stern: To say that the model was mine is not entirely accurate. Pieces of it (especially the Scpv and Atomic axioms) were taken directly from Jade's models. And of course the Happens-before and Propagation relations and axioms were heavily based on Jade and Luc's work, even though they weren't identical to the earlier versions. Only the RCU portion was completely original. . . . One can make a much better case that I wrote the bulk of lock.cat. However, it was inspired by Luc's earlier version (and still shares some elements in common), and of course it benefited from feedback and testing from all members of our group.The model prior to Alan's was Luc Maranget's. From Luc: I totally agree on Alan Stern's account of the linux kernel model genesis. I thank him for his acknowledgments of my participation to previous model drafts. I'd like to complete Alan Stern's statement: any bell cat code I have written has its roots in discussions with Jade Alglave and Paul McKenney. Moreover I have borrowed cat and bell code written by Jade Alglave freely.This copyright review therefore resulted in late adds to the copyrightstatements of several files.Discussion of v1 has raised several issues, which we do not believe shouldblock acceptance given that this level of change will be ongoing, justas it has been with memory-barriers.txt:o Under what conditions should ordering provided by pure locking be seen by CPUs not holding the relevant lock(s)? In particular, should the message-passing pattern be forbidden?o Should examples involving C11 release sequences be forbidden? Note that this C11 is still a moving target for this issue: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0735r0.htmlo Some details of the handling of internal dependencies for atomic read-modify-write atomic operations are still subject to debate.o Changes recently accepted into mainline greatly reduce the need to handle DEC Alpha as a special case. These changes add an smp_read_barrier_depends() to READ_ONCE(), thus causing Alpha to respect ordering of dependent reads. If these changes stick, the memory model can be simplified accordingly.o Will changes be required to accommodate RISC-V?Differences from v1: (http://lkml.kernel.org/r/20171113184031.GA26302@linux.vnet.ibm.com)o Add SPDX notations to .bell and .cat files, replacing textual license statements.o Add reference to upcoming ASPLOS paper to .bell and .cat files.o Updated identifier names in .bell and .cat files to match those used in the ASPLOS paper.o Updates to READMEs and other documentation based on review feedback.o Added a memory-ordering cheatsheet.o Update sigs to new Co-Developed-by and add acks and reviewed-bys.o Simplify rules detecting nested RCU read-side critical sections.o Update copyright statements as noted above.Co-Developed-by: Alan Stern Co-Developed-by: Andrea Parri Co-Developed-by: Jade Alglave Co-Developed-by: Luc Maranget Co-Developed-by: "Paul E. McKenney" Signed-off-by: Alan Stern Signed-off-by: Andrea Parri Signed-off-by: Jade Alglave Signed-off-by: Luc Maranget Signed-off-by: "Paul E. McKenney" Reviewed-by: Boqun Feng Acked-by: Will Deacon Acked-by: Peter Zijlstra Acked-by: Nicholas Piggin Acked-by: David Howells Acked-by: "Reshetova, Elena" Acked-by: Michal Hocko Acked-by: Akira Yokosawa Cc: List of files: /linux-6.15/tools/memory-model/litmus-tests/README