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From:   "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To:     linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Cc:     mingo@kernel.org, stern@rowland.harvard.edu,
        parri.andrea@gmail.com, will.deacon@arm.com, peterz@infradead.org,
        boqun.feng@gmail.com, npiggin@gmail.com, dhowells@redhat.com,
        j.alglave@ucl.ac.uk, luc.maranget@inria.fr, akiyks@gmail.com,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH RFC tools/memory-model 5/5] EXP tools/memory-model: Flag "cumulativity" and "propagation" tests
Date:   Mon, 16 Apr 2018 09:22:51 -0700
In-Reply-To: <20180416162228.GA18167@linux.vnet.ibm.com>
References: <20180416162228.GA18167@linux.vnet.ibm.com>
Message-Id: <1523895771-19224-5-git-send-email-paulmck@linux.vnet.ibm.com>
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This commit flags WRC+pooncerelease+rmbonceonce+Once.litmus as being
forbidden by LKMM cumulativity and IRIW+mbonceonces+OnceOnce.litmus as
being forbidden by LKMM propagation.

Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Suggested-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Updated wording as suggested by Alan Stern. ]
---
 tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus | 2 +-
 tools/memory-model/litmus-tests/README                           | 9 ++++++---
 .../litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus       | 4 +++-
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus b/tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus
index 50d5db9ea983..98a3716efa37 100644
--- a/tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus
+++ b/tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus
@@ -7,7 +7,7 @@ C IRIW+mbonceonces+OnceOnce
  * between each pairs of reads.  In other words, is smp_mb() sufficient to
  * cause two different reading processes to agree on the order of a pair
  * of writes, where each write is to a different variable by a different
- * process?
+ * process?  This litmus test exercises LKMM's "propagation" rule.
  *)
 
 {}
diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
index 6919909bbd0f..17eb9a8c222d 100644
--- a/tools/memory-model/litmus-tests/README
+++ b/tools/memory-model/litmus-tests/README
@@ -23,7 +23,8 @@ IRIW+mbonceonces+OnceOnce.litmus
 	between each pairs of reads.  In other words, is smp_mb()
 	sufficient to cause two different reading processes to agree on
 	the order of a pair of writes, where each write is to a different
-	variable by a different process?
+	variable by a different process?  This litmus test is forbidden
+	by LKMM's propagation rule.
 
 IRIW+poonceonces+OnceOnce.litmus
 	Test of independent reads from independent writes with nothing
@@ -119,8 +120,10 @@ S+wmbonceonce+poacquireonce.litmus
 
 WRC+poonceonces+Once.litmus
 WRC+pooncerelease+rmbonceonce+Once.litmus
-	These two are members of an extension of the MP litmus-test class
-	in which the first write is moved to a separate process.
+	These two are members of an extension of the MP litmus-test
+	class in which the first write is moved to a separate process.
+	The second is forbidden because smp_store_release() is
+	A-cumulative in LKMM.
 
 Z6.0+pooncelock+pooncelock+pombonce.litmus
 	Is the ordering provided by a spin_unlock() and a subsequent
diff --git a/tools/memory-model/litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus b/tools/memory-model/litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus
index 97fcbffde9a0..ad3448b941e6 100644
--- a/tools/memory-model/litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus
+++ b/tools/memory-model/litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus
@@ -5,7 +5,9 @@ C WRC+pooncerelease+rmbonceonce+Once
  *
  * This litmus test is an extension of the message-passing pattern, where
  * the first write is moved to a separate process.  Because it features
- * a release and a read memory barrier, it should be forbidden.
+ * a release and a read memory barrier, it should be forbidden.  More
+ * specifically, this litmus test is forbidden because smp_store_release()
+ * is A-cumulative in LKMM.
  *)
 
 {}
-- 
2.5.2