[PATCH v4 2/4] locktorture: Add nested locking to mutex torture tests

[John Stultz <jstultz@google.com>]

This patch adds randomized nested locking to the mutex torture
tests, as well as new LOCK08 config files for testing mutexes
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>
---
v2:
* Add LOCK08 config file suggested by Paul McKenney
v3:
* Minor commit message tweaks and naming changes
  suggested by Davidlohr Bueso
v4:
* Add co-developed tag
---
 kernel/locking/locktorture.c                  | 35 +++++++++++++++++++
 .../selftests/rcutorture/configs/lock/CFLIST  |  1 +
 .../selftests/rcutorture/configs/lock/LOCK08  |  6 ++++
 .../rcutorture/configs/lock/LOCK08.boot       |  1 +
 4 files changed, 43 insertions(+)
 create mode 100644 tools/testing/selftests/rcutorture/configs/lock/LOCK08
 create mode 100644 tools/testing/selftests/rcutorture/configs/lock/LOCK08.boot

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 6fe046594868..8a08c004aa80 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -332,6 +332,28 @@ static struct lock_torture_ops rw_lock_irq_ops = {
 };
 
 static DEFINE_MUTEX(torture_mutex);
+static struct mutex torture_nested_mutexes[MAX_NESTED_LOCKS];
+static struct lock_class_key nested_mutex_keys[MAX_NESTED_LOCKS];
+
+static void torture_mutex_init(void)
+{
+	int i;
+
+	for (i = 0; i < MAX_NESTED_LOCKS; i++)
+		__mutex_init(&torture_nested_mutexes[i], __func__,
+			     &nested_mutex_keys[i]);
+}
+
+static int torture_mutex_nested_lock(int tid __maybe_unused,
+				     u32 lockset)
+{
+	int i;
+
+	for (i = 0; i < nested_locks; i++)
+		if (lockset & (1 << i))
+			mutex_lock(&torture_nested_mutexes[i]);
+	return 0;
+}
 
 static int torture_mutex_lock(int tid __maybe_unused)
 __acquires(torture_mutex)
@@ -360,11 +382,24 @@ __releases(torture_mutex)
 	mutex_unlock(&torture_mutex);
 }
 
+static void torture_mutex_nested_unlock(int tid __maybe_unused,
+					u32 lockset)
+{
+	int i;
+
+	for (i = nested_locks - 1; i >= 0; i--)
+		if (lockset & (1 << i))
+			mutex_unlock(&torture_nested_mutexes[i]);
+}
+
 static struct lock_torture_ops mutex_lock_ops = {
+	.init		= torture_mutex_init,
+	.nested_lock	= torture_mutex_nested_lock,
 	.writelock	= torture_mutex_lock,
 	.write_delay	= torture_mutex_delay,
 	.task_boost     = torture_boost_dummy,
 	.writeunlock	= torture_mutex_unlock,
+	.nested_unlock	= torture_mutex_nested_unlock,
 	.readlock       = NULL,
 	.read_delay     = NULL,
 	.readunlock     = NULL,
diff --git a/tools/testing/selftests/rcutorture/configs/lock/CFLIST b/tools/testing/selftests/rcutorture/configs/lock/CFLIST
index 41bae5824339..a48bba0d35a6 100644
--- a/tools/testing/selftests/rcutorture/configs/lock/CFLIST
+++ b/tools/testing/selftests/rcutorture/configs/lock/CFLIST
@@ -5,3 +5,4 @@ LOCK04
 LOCK05
 LOCK06
 LOCK07
+LOCK08
diff --git a/tools/testing/selftests/rcutorture/configs/lock/LOCK08 b/tools/testing/selftests/rcutorture/configs/lock/LOCK08
new file mode 100644
index 000000000000..1d1da1477fc3
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/lock/LOCK08
@@ -0,0 +1,6 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=4
+CONFIG_HOTPLUG_CPU=y
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
diff --git a/tools/testing/selftests/rcutorture/configs/lock/LOCK08.boot b/tools/testing/selftests/rcutorture/configs/lock/LOCK08.boot
new file mode 100644
index 000000000000..b8b6caebb89e
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/lock/LOCK08.boot
@@ -0,0 +1 @@
+locktorture.torture_type=mutex_lock locktorture.nested_locks=8
-- 
2.39.2.637.g21b0678d19-goog