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Date: Wed, 5 Jun 2024 10:47:03 -0400
From: Alan Stern <stern@rowland.harvard.edu>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Andrea Parri <parri.andrea@gmail.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,
  linux-kernel@vger.kernel.org, hernan.poncedeleon@huaweicloud.com,
  jonas.oberhauser@huaweicloud.com
Subject: New locking test for the paulmckrcu/litmus github archive
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Paul:

Below is a new litmus test for the manual/locked directory in your 
github archive.  It is based on a suggestion from Andrea Parri, and it 
demonstrates a bug in the current LKMM lock.cat file.  Patches to fix 
that file will be sent shortly.

Alan

---

C islocked+lock+islocked+unlock+islocked.litmus

(*
 * Result: Always
 *
 * This tests the memory model's implementation of spin_is_locked().
 *)

{}

P0(spinlock_t *x)
{
        int r0;
	int r1;
	int r2;

	r0 = spin_is_locked(x);
	spin_lock(x);
	r1 = spin_is_locked(x);
	spin_unlock(x);
	r2 = spin_is_locked(x);
}

exists (0:r0=0 /\ 0:r1=1 /\ 0:r2=0)