On Mon, May 11, 2020 at 10:33:48AM -0700, Paul E. McKenney wrote:
> On Sun, May 10, 2020 at 04:21:02PM +0900, Akira Yokosawa wrote:
> > On Sat, 9 May 2020 12:43:30 +0900, Akira Yokosawa wrote:
> > > 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@xxxxxxxxxxxxxxxxx>
> > >>
> > >> ---
> > >> Cc: vpillai@xxxxxxxxxxxxxxxx
> > >>
> > >> 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?
> >
> > So something like this?
> >
> > Patch 1/3 is an independent typo fix in recipes.txt.
> > Patch 2/3 reverts the MP+onceassign+derefonce relocation.
> > Patch 3/3 merges atomic's README into the top-level one.
> >
> > This is relative to -rcu's lkmm branch.
> >
> > Thoughts?
>
> Looks plausible to me, and thank you for reviewing this.
>
> Joel, thoughts?
Sorry for the delays (OSPM conference in progress). I'm Ok with moving it
back to tools/memory-model/.
I think on top of this patch, I'd like to add a reference to the to the
litmus test in tools/memory-model/ from Documentation/rcu/.
Just to mention my rationale for Documentation/litmus-tests/rcu/, I was
basically looking for a central place for RCU related litmus tests in the
kernel sources and the idea of this new directory came up.
For Akira's series,
Acked-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
And could we add the following patch on top of Akira's series so we still
maintain a reference to the moved RCU test?
---8<-----------------------
>From 52fdb57551cc769d8bd690f4f2b22de36ddece99 Mon Sep 17 00:00:00 2001
From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Date: Mon, 11 May 2020 22:06:46 -0400
Subject: [PATCH] docs: litmus-tests: Clarify about the RCU pre-initialization
test
Since this test was moved to tools/memory-model/, make sure that it is
at least referenced from Documentation/litmus-tests/'s README.
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
Documentation/litmus-tests/README | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/Documentation/litmus-tests/README b/Documentation/litmus-tests/README
index ac0b270b456c1..53f09e74734a4 100644
--- a/Documentation/litmus-tests/README
+++ b/Documentation/litmus-tests/README
@@ -11,7 +11,6 @@ tools/memory-model/README.
atomic (/atomic derectory)
--------------------------
-
Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus
Test that an atomic RMW followed by a smp_mb__after_atomic() is
stronger than a normal acquire: both the read and write parts of
@@ -23,8 +22,11 @@ Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus
RCU (/rcu directory)
--------------------
-
RCU+sync+read.litmus
RCU+sync+free.litmus
Both the above litmus tests demonstrate the RCU grace period guarantee
that an RCU read-side critical section can never span a grace period.
+
+MP+onceassign+derefonce.litmus (moved to tools/memory-model/litmus-tests/)
+ Demonstrates that rcu_assign_pointer() and rcu_dereference() to
+ ensure that an RCU reader will not see pre-initialization garbage.
--
2.26.2.645.ge9eca65c58-goog
