[PATCH tip/core/rcu 06/14] tools/memory-model: Add an exception for limitations on _unless() family
From: paulmck@kernel.org
Date: 2020-06-23 00:53:37
Also in:
lkml
Subsystem:
linux kernel memory consistency model (lkmm), the rest · Maintainers:
Alan Stern, Andrea Parri, Will Deacon, Peter Zijlstra, Boqun Feng, Nicholas Piggin, David Howells, Jade Alglave, Luc Maranget, "Paul E. McKenney", Linus Torvalds
From: Boqun Feng <redacted> 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) <redacted> Signed-off-by: Boqun Feng <redacted> 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