linux-kernel - [tip:locking/core] tools/memory-model: Flag "cumulativity" and "propagation" tests

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Message-ID: <tip-1bd3742043fa44dd0ec25770abdcdfe1f6e8681e@git.kernel.org>
Date:   Mon, 14 May 2018 23:32:17 -0700
From:   "tip-bot for Paul E. McKenney" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, will.deacon@....com,
        torvalds@...ux-foundation.org, andrea.parri@...rulasolutions.com,
        linux-kernel@...r.kernel.org, stern@...land.harvard.edu,
        paulmck@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
        pbonzini@...hat.com, hpa@...or.com, tglx@...utronix.de,
        peterz@...radead.org
Subject: [tip:locking/core] tools/memory-model: Flag "cumulativity" and
 "propagation" tests

Commit-ID:  1bd3742043fa44dd0ec25770abdcdfe1f6e8681e
Gitweb:     https://git.kernel.org/tip/1bd3742043fa44dd0ec25770abdcdfe1f6e8681e
Author:     Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
AuthorDate: Mon, 14 May 2018 16:33:49 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 15 May 2018 08:11:17 +0200

tools/memory-model: Flag "cumulativity" and "propagation" tests

This commit flags WRC+pooncerelease+rmbonceonce+Once.litmus
as being forbidden by smp_store_release() A-cumulativity and
IRIW+mbonceonces+OnceOnce.litmus as being forbidden by the LKMM
propagation rule.

Suggested-by: Andrea Parri <andrea.parri@...rulasolutions.com>
Reported-by: Paolo Bonzini <pbonzini@...hat.com>
[ paulmck: Updated wording as suggested by Alan Stern. ]
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Acked-by: Alan Stern <stern@...land.harvard.edu>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Will Deacon <will.deacon@....com>
Cc: akiyks@...il.com
Cc: boqun.feng@...il.com
Cc: dhowells@...hat.com
Cc: j.alglave@....ac.uk
Cc: linux-arch@...r.kernel.org
Cc: luc.maranget@...ia.fr
Cc: npiggin@...il.com
Cc: parri.andrea@...il.com
Link: http://lkml.kernel.org/r/1526340837-12222-11-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 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.
  *)
 
 {}