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From: Boqun Feng <boqun.feng@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Alan Stern <stern@rowland.harvard.edu>,
	Andrea Parri <parri.andrea@gmail.com>,
	Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	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>,
	Akira Yokosawa <akiyks@gmail.com>,
	Daniel Lustig <dlustig@nvidia.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Rob Herring <robh@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	linux-arch@vger.kernel.org, linux-doc@vger.kernel.org
Subject: [PATCH v3 1/5] tools/memory-model: Add an exception for limitations on _unless() family
Date: Thu, 27 Feb 2020 08:40:45 +0800	[thread overview]
Message-ID: <20200227004049.6853-2-boqun.feng@gmail.com> (raw)
In-Reply-To: <20200227004049.6853-1-boqun.feng@gmail.com>

According to Luc, atomic_add_unless() is directly provided by herd7,
therefore it can be used in litmus tests. So change the limitation
section in README to unlimit the use of atomic_add_unless().

Cc: Luc Maranget <luc.maranget@inria.fr>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
 tools/memory-model/README | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/memory-model/README b/tools/memory-model/README
index fc07b52f2028..409211b1c544 100644
--- a/tools/memory-model/README
+++ b/tools/memory-model/README
@@ -207,11 +207,15 @@ The Linux-kernel memory model (LKMM) has the following limitations:
 		case as a store release.
 
 	b.	The "unless" RMW operations are not currently modeled:
-		atomic_long_add_unless(), atomic_add_unless(),
-		atomic_inc_unless_negative(), and
-		atomic_dec_unless_positive().  These can be emulated
+		atomic_long_add_unless(), atomic_inc_unless_negative(),
+		and atomic_dec_unless_positive().  These can be emulated
 		in litmus tests, for example, by using atomic_cmpxchg().
 
+		One exception of this limitation is atomic_add_unless(),
+		which is provided directly by herd7 (so no corresponding
+		definition in linux-kernel.def). atomic_add_unless() is
+		modeled by herd7 therefore it can be used in litmus tests.
+
 	c.	The call_rcu() function is not modeled.  It can be
 		emulated in litmus tests by adding another process that
 		invokes synchronize_rcu() and the body of the callback
-- 
2.25.0


  reply	other threads:[~2020-02-27  0:41 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-27  0:40 [PATCH v3 0/5] Documentation/locking/atomic: Add litmus tests for atomic APIs Boqun Feng
2020-02-27  0:40 ` Boqun Feng [this message]
2020-02-27 16:32   ` [PATCH v3 1/5] tools/memory-model: Add an exception for limitations on _unless() family Alan Stern
2020-02-27 16:49     ` Luc Maranget
2020-02-27 18:16       ` Alan Stern
2020-02-27 17:52   ` Andrea Parri
2020-02-27  0:40 ` [PATCH v3 2/5] Documentation/locking/atomic: Fix atomic-set litmus test Boqun Feng
2020-02-27 16:34   ` Alan Stern
2020-02-28  6:30     ` Boqun Feng
2020-02-27  0:40 ` [PATCH v3 3/5] Documentation/locking/atomic: Introduce atomic-tests directory Boqun Feng
2020-02-27 16:36   ` Alan Stern
2020-02-27  0:40 ` [PATCH v3 4/5] Documentation/locking/atomic: Add a litmus test for atomic_set() Boqun Feng
2020-02-27 16:37   ` Alan Stern
2020-02-27 17:43   ` Andrea Parri
2020-02-27  0:40 ` [PATCH v3 5/5] Documentation/locking/atomic: Add a litmus test smp_mb__after_atomic() Boqun Feng
2020-02-27 16:38   ` Alan Stern
2020-02-27 15:47 ` [PATCH v3 0/5] Documentation/locking/atomic: Add litmus tests for atomic APIs Paul E. McKenney
2020-02-27 17:54 ` Andrea Parri
2020-02-28  6:12   ` Boqun Feng

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