linux-kernel - [PATCH 1/3] tools: memory-model: Expand definition of barrier

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Date:   Thu, 20 Jun 2019 11:55:36 -0400 (EDT)
From:   Alan Stern <stern@...land.harvard.edu>
To:     LKMM Maintainers -- Akira Yokosawa <akiyks@...il.com>,
        Andrea Parri <andrea.parri@...rulasolutions.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Daniel Lustig <dlustig@...dia.com>,
        David Howells <dhowells@...hat.com>,
        Jade Alglave <j.alglave@....ac.uk>,
        Luc Maranget <luc.maranget@...ia.fr>,
        Nicholas Piggin <npiggin@...il.com>,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will.deacon@....com>
cc:     Kernel development list <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/3] tools: memory-model: Expand definition of barrier

Commit 66be4e66a7f4 ("rcu: locking and unlocking need to always be at
least barriers") added compiler barriers back into rcu_read_lock() and
rcu_read_unlock().  Furthermore, srcu_read_lock() and
srcu_read_unlock() have always contained compiler barriers.

The Linux Kernel Memory Model ought to know about these barriers.
This patch adds them into the memory model.

Signed-off-by: Alan Stern <stern@...land.harvard.edu>

---


 tools/memory-model/linux-kernel.cat |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: usb-devel/tools/memory-model/linux-kernel.cat
===================================================================
--- usb-devel.orig/tools/memory-model/linux-kernel.cat
+++ usb-devel/tools/memory-model/linux-kernel.cat
@@ -47,7 +47,8 @@ let strong-fence = mb | gp
 let nonrw-fence = strong-fence | po-rel | acq-po
 let fence = nonrw-fence | wmb | rmb
 let barrier = fencerel(Barrier | Rmb | Wmb | Mb | Sync-rcu | Sync-srcu |
-		Before-atomic | After-atomic | Acquire | Release) |
+		Before-atomic | After-atomic | Acquire | Release |
+		Rcu-lock | Rcu-unlock | Srcu-lock | Srcu-unlock) |
 	(po ; [Release]) | ([Acquire] ; po)
 
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