linux-kernel - [PATCH 39/48] rcutorture: Remove extraneous rcu_torture_pipe_update_one() READ

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Message-Id: <20240507093530.3043-40-urezki@gmail.com>
Date: Tue,  7 May 2024 11:35:21 +0200
From: "Uladzislau Rezki (Sony)" <urezki@...il.com>
To: "Paul E . McKenney" <paulmck@...nel.org>
Cc: RCU <rcu@...r.kernel.org>,
	Neeraj upadhyay <Neeraj.Upadhyay@....com>,
	Boqun Feng <boqun.feng@...il.com>,
	Hillf Danton <hdanton@...a.com>,
	Joel Fernandes <joel@...lfernandes.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
	Frederic Weisbecker <frederic@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 39/48] rcutorture: Remove extraneous rcu_torture_pipe_update_one() READ_ONCE()

From: "Paul E. McKenney" <paulmck@...nel.org>

The rcu_torture_pipe_update_one() cannot run concurrently with any updates
of ->rtort_pipe_count, so this commit removes the extraneous READ_ONCE()
from the read from this field.

Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
Closes: https://lore.kernel.org/lkml/CAHk-=wiX_zF5Mpt8kUm_LFQpYY-mshrXJPOe+wKNwiVhEUcU9g@mail.gmail.com/
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 kernel/rcu/rcutorture.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index d8c12eba35b7..6b821a7037b0 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -461,7 +461,7 @@ rcu_torture_pipe_update_one(struct rcu_torture *rp)
 		WRITE_ONCE(rp->rtort_chkp, NULL);
 		smp_store_release(&rtrcp->rtc_ready, 1); // Pair with smp_load_acquire().
 	}
-	i = READ_ONCE(rp->rtort_pipe_count);
+	i = rp->rtort_pipe_count;
 	if (i > RCU_TORTURE_PIPE_LEN)
 		i = RCU_TORTURE_PIPE_LEN;
 	atomic_inc(&rcu_torture_wcount[i]);
-- 
2.39.2