Re: [PATCH v2 1/4] Documentation: LKMM: Move MP+onceassign+derefonce to new litmus-tests/rcu/

From: Akira Yokosawa <akiyks@gmail.com>
To: "Joel Fernandes (Google)" <joel@joelfernandes.org>,
	linux-kernel@vger.kernel.org, Boqun Feng <boqun.feng@gmail.com>
Cc: vpillai@digitalocean.com, Jonathan Corbet <corbet@lwn.net>,
	Alan Stern <stern@rowland.harvard.edu>,
	Andrea Parri <parri.andrea@gmail.com>,
	Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	David Howells <dhowells@redhat.com>,
	Jade Alglave <j.alglave@ucl.ac.uk>,
	Luc Maranget <luc.maranget@inria.fr>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Daniel Lustig <dlustig@nvidia.com>,
	linux-doc@vger.kernel.org, Akira Yokosawa <akiyks@gmail.com>
Subject: Re: [PATCH v2 1/4] Documentation: LKMM: Move MP+onceassign+derefonce to new litmus-tests/rcu/
Date: Sat, 9 May 2020 12:43:30 +0900	[thread overview]
Message-ID: <7809dbfa-7a76-8663-799a-908c4ead8d30@gmail.com> (raw)
In-Reply-To: <20200323015735.236279-1-joel@joelfernandes.org>

Hi Joel,

Sorry for the late response but I've noticed some glitches.

On Sun, 22 Mar 2020 21:57:32 -0400, Joel Fernandes (Google) wrote:
> Move MP+onceassign+derefonce to the new Documentation/litmus-tests/rcu/
> directory.

MP+onceassign+derefonce.litmus is called out in
tools/memory-model/Documentation/recipes.txt as a representative example
of RCU related litmus test.

So I think it should be kept under tools/memory-model/litmus-tests.

Further RCU-related litmus tests can be added under Documentation/litmus-tests/.

IIUC, this change is not picked up by tip tree yet. So we have time to respin
the series targeting v5.9.

> 
> More RCU-related litmus tests would be added here.
> 
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> 
> ---
> Cc: vpillai@digitalocean.com
> 
>  Documentation/litmus-tests/README                        | 9 +++++++++

Please note that later patches to add atomic litmus tests under
Documentation/litmus-tests/ by Boqun put README as
Documentation/litums-tests/atomic/README.

This patch's location of RCU's README as Documentation/litmus-tests/README
looks asymmetric to me.

I'm OK with either merging atomic's README with the top-level one or
moving RCU's README to under Documentation/litmus-tests/rcu.

Joel, Boqum, can you sort out the location of README?

        Thanks, Akira

>  .../litmus-tests/rcu}/MP+onceassign+derefonce.litmus     | 0
>  tools/memory-model/litmus-tests/README                   | 3 ---
>  3 files changed, 9 insertions(+), 3 deletions(-)
>  create mode 100644 Documentation/litmus-tests/README
>  rename {tools/memory-model/litmus-tests => Documentation/litmus-tests/rcu}/MP+onceassign+derefonce.litmus (100%)
> 
> diff --git a/Documentation/litmus-tests/README b/Documentation/litmus-tests/README
> new file mode 100644
> index 0000000000000..84208bc197f2e
> --- /dev/null
> +++ b/Documentation/litmus-tests/README
> @@ -0,0 +1,9 @@
> +============
> +LITMUS TESTS
> +============
> +
> +RCU (/rcu directory)
> +--------------------
> +MP+onceassign+derefonce.litmus
> +    Demonstrates that rcu_assign_pointer() and rcu_dereference() to
> +    ensure that an RCU reader will not see pre-initialization garbage.
> diff --git a/tools/memory-model/litmus-tests/MP+onceassign+derefonce.litmus b/Documentation/litmus-tests/rcu/MP+onceassign+derefonce.litmus
> similarity index 100%
> rename from tools/memory-model/litmus-tests/MP+onceassign+derefonce.litmus
> rename to Documentation/litmus-tests/rcu/MP+onceassign+derefonce.litmus
> diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
> index 681f9067fa9ed..79e1b1ed4929a 100644
> --- a/tools/memory-model/litmus-tests/README
> +++ b/tools/memory-model/litmus-tests/README
> @@ -63,9 +63,6 @@ LB+poonceonces.litmus
>  	As above, but with store-release replaced with WRITE_ONCE()
>  	and load-acquire replaced with READ_ONCE().
>  
> -MP+onceassign+derefonce.litmus
> -	As below, but with rcu_assign_pointer() and an rcu_dereference().
> -
>  MP+polockmbonce+poacquiresilsil.litmus
>  	Protect the access with a lock and an smp_mb__after_spinlock()
>  	in one process, and use an acquire load followed by a pair of
> 