linux-kernel - [PATCH tip/core/rcu 7/9] rcuperf: Fix cleanup path for invalid perf

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Date:   Tue, 26 Mar 2019 16:31:16 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>
Subject: [PATCH tip/core/rcu 7/9] rcuperf: Fix cleanup path for invalid perf_type strings

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@...ux.ibm.com>
---
 kernel/rcu/rcuperf.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index c29761152874..7a6890b23c5f 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -494,6 +494,10 @@ 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++)
@@ -614,6 +618,7 @@ rcu_perf_init(void)
 		pr_cont("\n");
 		WARN_ON(!IS_MODULE(CONFIG_RCU_PERF_TEST));
 		firsterr = -EINVAL;
+		cur_ops = NULL;
 		goto unwind;
 	}
 	if (cur_ops->init)
-- 
2.17.1