From e97dcfd4580d33ee08b7c4edb24d73bd56b80618 Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@kernel.org>
Date: Fri, 6 Aug 2021 08:57:26 -0700
Subject: [PATCH] rcutorture: Don't cpuhp_remove_state() if cpuhp_setup_state()
 failed

References: bnc#1189998 (PREEMPT_RT prerequisite backports)
Patch-mainline: v5.16-rc1
Git-commit: fd13fe16db0d82612b260640f4e26f6d9d1e11fd

Currently, in CONFIG_RCU_BOOST kernels, if the rcu_torture_init()
function's call to cpuhp_setup_state() fails, rcu_torture_cleanup()
gamely passes nonsense to cpuhp_remove_state().  This results in
strange and misleading splats.  This commit therefore ensures that if
the rcu_torture_init() function's call to cpuhp_setup_state() fails,
rcu_torture_cleanup() avoids invoking cpuhp_remove_state().

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 kernel/rcu/rcutorture.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index fd392348299f..8b410d982990 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2843,7 +2843,7 @@ rcu_torture_cleanup(void)
 		 rcutorture_seq_diff(gp_seq, start_gp_seq));
 	torture_stop_kthread(rcu_torture_stats, stats_task);
 	torture_stop_kthread(rcu_torture_fqs, fqs_task);
-	if (rcu_torture_can_boost())
+	if (rcu_torture_can_boost() && rcutor_hp >= 0)
 		cpuhp_remove_state(rcutor_hp);
 
 	/*
@@ -3156,9 +3156,9 @@ rcu_torture_init(void)
 		firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
 					     rcutorture_booster_init,
 					     rcutorture_booster_cleanup);
+		rcutor_hp = firsterr;
 		if (torture_init_error(firsterr))
 			goto unwind;
-		rcutor_hp = firsterr;
 
 		// Testing RCU priority boosting requires rcutorture do
 		// some serious abuse.  Counter this by running ksoftirqd