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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, "Paul E. McKenney" <paulmck@linux.ibm.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 115/128] rcuperf: Fix cleanup path for invalid perf_type strings
Date:   Wed, 29 May 2019 20:07:27 -0700
Message-Id: <20190530030455.194275136@linuxfoundation.org>
In-Reply-To: <20190530030432.977908967@linuxfoundation.org>
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[ Upstream commit ad092c027713a68a34168942a5ef422e42e039f4 ]

If the specified rcuperf.perf_type is not in the rcu_perf_init()
function's perf_ops[] array, rcuperf prints some console messages and
then invokes rcu_perf_cleanup() to set state so that a future torture
test can run.  However, rcu_perf_cleanup() also attempts to end the
test that didn't actually start, and in doing so relies on the value
of cur_ops, a value that is not particularly relevant in this case.
This can result in confusing output or even follow-on failures due to
attempts to use facilities that have not been properly initialized.

This commit therefore sets the value of cur_ops to NULL in this case and
inserts a check near the beginning of rcu_perf_cleanup(), thus avoiding
relying on an irrelevant cur_ops value.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/rcu/rcuperf.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 123ccbd224492..2b8579d5a5445 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -453,6 +453,10 @@ rcu_perf_cleanup(void)
 
 	if (torture_cleanup_begin())
 		return;
+	if (!cur_ops) {
+		torture_cleanup_end();
+		return;
+	}
 
 	if (reader_tasks) {
 		for (i = 0; i < nrealreaders; i++)
@@ -574,6 +578,7 @@ rcu_perf_init(void)
 			pr_alert(" %s", perf_ops[i]->name);
 		pr_alert("\n");
 		firsterr = -EINVAL;
+		cur_ops = NULL;
 		goto unwind;
 	}
 	if (cur_ops->init)
-- 
2.20.1