Date:   Sun, 29 Jan 2023 18:28:27 +0100
From:   Andrea Parri <parri.andrea@gmail.com>
To:     "Paul E. McKenney" <paulmck@kernel.org>
Cc:     Alan Stern <stern@rowland.harvard.edu>,
        Jonas Oberhauser <jonas.oberhauser@huaweicloud.com>,
        will@kernel.org, peterz@infradead.org, boqun.feng@gmail.com,
        npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk,
        luc.maranget@inria.fr, akiyks@gmail.com, dlustig@nvidia.com,
        joel@joelfernandes.org, urezki@gmail.com, quic_neeraju@quicinc.com,
        frederic@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] tools/memory-model: Make ppo a subrelation of po
Message-ID: <Y9asu0CswZZ3yyls@andrea>
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> Why can't P3's spin_lock() read from that initial write?

Mmh, sounds like you want to play with something like below?

  Andrea

diff --git a/tools/memory-model/lock.cat b/tools/memory-model/lock.cat
index 6b52f365d73ac..20c3af4511255 100644
--- a/tools/memory-model/lock.cat
+++ b/tools/memory-model/lock.cat
@@ -74,7 +74,6 @@ flag ~empty UL \ range(critical) as unmatched-unlock
 
 (* Allow up to one unmatched LKW per location; more must deadlock *)
 let UNMATCHED-LKW = LKW \ domain(critical)
-empty ([UNMATCHED-LKW] ; loc ; [UNMATCHED-LKW]) \ id as unmatched-locks
 
 (* rfi for LF events: link each LKW to the LF events in its critical section *)
 let rfi-lf = ([LKW] ; po-loc ; [LF]) \ ([LKW] ; po-loc ; [UL] ; po-loc)
@@ -120,8 +119,7 @@ let rf-ru = rfe-ru | rfi-ru
 let rf = rf | rf-lf | rf-ru
 
 (* Generate all co relations, including LKW events but not UL *)
-let co0 = co0 | ([IW] ; loc ; [LKW]) |
-	(([LKW] ; loc ; [UNMATCHED-LKW]) \ [UNMATCHED-LKW])
+let co0 = co0 | ([IW] ; loc ; [LKW])
 include "cos-opt.cat"
 let W = W | UL
 let M = R | W