On Sun, Feb 16, 2020 at 11:16:50AM -0500, Alan Stern wrote: > On Sun, 16 Feb 2020, Paul E. McKenney wrote: > > > On Sun, Feb 16, 2020 at 01:43:45PM +0800, Boqun Feng wrote: > > > On Sat, Feb 15, 2020 at 07:25:50AM -0800, Paul E. McKenney wrote: > > > > On Fri, Feb 14, 2020 at 10:27:44AM -0500, Alan Stern wrote: > > > > > On Fri, 14 Feb 2020, Boqun Feng wrote: > > > > > > > > > > > A recent discussion raises up the requirement for having test cases for > > > > > > atomic APIs: > > > > > > > > > > > > https://lore.kernel.org/lkml/20200213085849.GL14897@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > > > > > > > > > > > , and since we already have a way to generate a test module from a > > > > > > litmus test with klitmus[1]. It makes sense that we add more litmus > > > > > > tests for atomic APIs into memory-model. > > > > > > > > > > It might be worth discussing this point a little more fully. The > > > > > set of tests in tools/memory-model/litmus-tests/ is deliberately rather > > > > > limited. Paul has a vastly more expansive set of litmus tests in a > > > > > GitHub repository, and I am doubtful about how many new tests we want > > > > > to keep in the kernel source. > > > > > > > > Indeed, the current view is that the litmus tests in the kernel source > > > > tree are intended to provide examples of C-litmus-test-language features > > > > and functions, as opposed to exercising the full cross-product of > > > > Linux-kernel synchronization primitives. > > > > > > > > For a semi-reasonable subset of that cross-product, as Alan says, please > > > > see https://github.com/paulmckrcu/litmus. > > > > > > > > For a list of the Linux-kernel synchronization primitives currently > > > > supported by LKMM, please see tools/memory-model/linux-kernel.def. > > > > > > > > > > So how about I put those atomic API tests into a separate directory, say > > > Documentation/atomic/ ? > > > > > > The problem I want to solve here is that people (usually who implements > > > the atomic APIs for new archs) may want some examples, which can help > > > them understand the API requirements and test the implementation. And > > > litmus tests are the perfect tool here (given that them can be > > > translated to test modules with klitmus). And I personally really think > > > this is something the LKMM group should maintain, that's why I put them > > > in the tools/memory-model/litmus-tests/. But I'm OK if we end up > > > deciding those should be put outside that directory. > > > > Good point! > > > > However, we should dicuss this with the proposed beneficiaries, namely > > the architecture maintainers. Do they want it? If so, where would > > they like it to be? How should it be organized? > > Paul, Well, I was simply motivated by the discuss on microblaze's atomic implementation (which I pasted the link in this cover letter): https://lore.kernel.org/lkml/20200213085849.GL14897@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ , please see the last paragraph, Michal asking Peter for some tests. So I think there is at least some one wanting this ;-) > > In the meantime, I am more than happy to accept litmus tests into the > > github archive. > > Thanks ;-) > > So how would you like to proceed? I think we are still at the discussion stage, so I'm happy to see suggestions on where to put the litmus tests and which litmus tests should be included. > > I think it makes sense to put Boqun's tests under Documentation/ rather > than tools/. After all, their point is to document the memory model's > requirements for operations on atomic_t's. They aren't meant to be > examples or demos showing how to use herd or write litmus tests. > Alan, Got it. I will create the Documentation/atomic directory and put the litmus tests there in the next version. Thank you both! Regards, Boqun > Alan >
