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SubjectRe: Prototype patch for Linux-kernel memory model
On Mon, Nov 13, 2017 at 10:40:31AM -0800, Paul E. McKenney wrote:
> commit 82a1431549b4eae531e83298fd72cd0acea08540
> Author: Paul E. McKenney <>
> Date: Mon Nov 13 10:30:07 2017 -0800
> tools: Automate memory-barriers.txt; provide Linux-kernel memory model
> There is some 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.
> The main tool is herd7, together with the linux-kernel.bell,
>, linux-kernel.cfg, linux-kernel.def, and files
> added by this patch. The herd7 executable takes the other files as input,
> and all of these files collectively define the Linux-kernel memory memory
> model. A brief description of each of these other files is provided
> in the README file. Although this tool does have its limitations,
> which are documented in the README file, it does improve on the version
> reported on in the LWN series ( and
> 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 freely
> available from (and via "git"
> at
> 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
> (and via "git" at
> Of course, litmus tests are not always the best way to fully understand a
> memory 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 use
> cases for those who prefer working by example.
> This patch also includes a few sample litmus tests, and a great many
> more litmus tests are available at
> Signed-off-by: Alan Stern <>
> Signed-off-by: Andrea Parri <>
> Signed-off-by: Will Deacon <>
> Signed-off-by: Peter Zijlstra <>
> Signed-off-by: Boqun Feng <>
> Signed-off-by: Nicholas Piggin <>
> Signed-off-by: David Howells <>
> Signed-off-by: Jade Alglave <>
> Signed-off-by: Luc Maranget <>
> Signed-off-by: "Paul E. McKenney" <>
> Cc: <>

So I think that SoB chains like that are utter crap. I think you meant
to have all but the one from you be an Ack or similar.

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