[PATCH tip/core/rcu 06/14] tools/memory-model: Add an exception for limitations on _unless() family

paulmck
2020-06-23T00:52:34Z

From: Boqun Feng <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>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
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 fc07b52..b9c562e 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
--
2.9.5