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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Sasha Levin <sashal@kernel.org>,
	dave@stgolabs.net,
	josh@joshtriplett.org,
	frederic@kernel.org,
	neeraj.upadhyay@kernel.org,
	joel@joelfernandes.org,
	boqun.feng@gmail.com,
	rcu@vger.kernel.org
Subject: [PATCH AUTOSEL 6.9 07/15] rcutorture: Fix rcu_torture_one_read() pipe_count overflow comment
Date: Sun, 26 May 2024 05:41:39 -0400
Message-ID: <20240526094152.3412316-7-sashal@kernel.org>
In-Reply-To: <20240526094152.3412316-1-sashal@kernel.org>
References: <20240526094152.3412316-1-sashal@kernel.org>
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From: "Paul E. McKenney" <paulmck@kernel.org>

[ Upstream commit 8b9b443fa860276822b25057cb3ff3b28734dec0 ]

The "pipe_count > RCU_TORTURE_PIPE_LEN" check has a comment saying "Should
not happen, but...".  This is only true when testing an RCU whose grace
periods are always long enough.  This commit therefore fixes this comment.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Closes: https://lore.kernel.org/lkml/CAHk-=wi7rJ-eGq+xaxVfzFEgbL9tdf6Kc8Z89rCpfcQOKm74Tw@mail.gmail.com/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/rcu/rcutorture.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 45d6b4c3d199c..5dfea5c6de577 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1997,7 +1997,8 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
 	preempt_disable();
 	pipe_count = READ_ONCE(p->rtort_pipe_count);
 	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
-		/* Should not happen, but... */
+		// Should not happen in a correct RCU implementation,
+		// happens quite often for torture_type=busted.
 		pipe_count = RCU_TORTURE_PIPE_LEN;
 	}
 	completed = cur_ops->get_gp_seq();
-- 
2.43.0