locktorture: Add nested locking to rtmutex torture tests

This patch adds randomized nested locking to the rtmutex torture
tests. Additionally it adds LOCK09 config files for testing
rtmutexes with nested locking.

Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: kernel-team@android.com
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Co-developed-by: Connor O'Brien <connoro@google.com>
Signed-off-by: Connor O'Brien <connoro@google.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/locking/locktorture.c

@@ -544,6 +544,28 @@ static struct lock_torture_ops ww_mutex_lock_ops = {
 
 #ifdef CONFIG_RT_MUTEXES
 static DEFINE_RT_MUTEX(torture_rtmutex);
+static struct rt_mutex torture_nested_rtmutexes[MAX_NESTED_LOCKS];
+static struct lock_class_key nested_rtmutex_keys[MAX_NESTED_LOCKS];
+
+static void torture_rtmutex_init(void)
+{
+	int i;
+
+	for (i = 0; i < MAX_NESTED_LOCKS; i++)
+		__rt_mutex_init(&torture_nested_rtmutexes[i], __func__,
+				&nested_rtmutex_keys[i]);
+}
+
+static int torture_rtmutex_nested_lock(int tid __maybe_unused,
+				       u32 lockset)
+{
+	int i;
+
+	for (i = 0; i < nested_locks; i++)
+		if (lockset & (1 << i))
+			rt_mutex_lock(&torture_nested_rtmutexes[i]);
+	return 0;
+}
 
 static int torture_rtmutex_lock(int tid __maybe_unused)
 __acquires(torture_rtmutex)
@@ -585,11 +607,24 @@ static void torture_rt_boost_rtmutex(struct torture_random_state *trsp)
 	__torture_rt_boost(trsp);
 }
 
+static void torture_rtmutex_nested_unlock(int tid __maybe_unused,
+					  u32 lockset)
+{
+	int i;
+
+	for (i = nested_locks - 1; i >= 0; i--)
+		if (lockset & (1 << i))
+			rt_mutex_unlock(&torture_nested_rtmutexes[i]);
+}
+
 static struct lock_torture_ops rtmutex_lock_ops = {
+	.init		= torture_rtmutex_init,
+	.nested_lock	= torture_rtmutex_nested_lock,
 	.writelock	= torture_rtmutex_lock,
 	.write_delay	= torture_rtmutex_delay,
 	.task_boost     = torture_rt_boost_rtmutex,
 	.writeunlock	= torture_rtmutex_unlock,
+	.nested_unlock	= torture_rtmutex_nested_unlock,
 	.readlock       = NULL,
 	.read_delay     = NULL,
 	.readunlock     = NULL,

tools/testing/selftests/rcutorture/configs/lock/CFLIST

@@ -6,3 +6,4 @@ LOCK05
 LOCK06
 LOCK07
 LOCK08
+LOCK09

tools/testing/selftests/rcutorture/configs/lock/LOCK09

+CONFIG_SMP=y
+CONFIG_NR_CPUS=4
+CONFIG_HOTPLUG_CPU=y
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y

tools/testing/selftests/rcutorture/configs/lock/LOCK09.boot

+locktorture.torture_type=rtmutex_lock locktorture.nested_locks=8