[PATCH 08/28] hazptrtorture: Add slowpath and lockdep scenarios

[Kunwu Chan <kunwu.chan@gmail.com>]

Add SLOWPATH and LOCKDEP configs: SLOWPATH enables
CONFIG_HAZPTR_ACQUIRE_FORCE_SLOWPATH for slow-path stress; LOCKDEP
combines PROVE_LOCKING with wq_churn=1 so each alloc_workqueue/
destroy_workqueue pair exercises the lockdep hazptr paths.

Suggested-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Kunwu Chan <kunwu.chan@gmail.com>
---
 kernel/rcu/hazptrtorture.c                    | 48 ++++++++++++++++++-
 .../rcutorture/configs/hazptr/LOCKDEP         | 16 +++++++
 .../rcutorture/configs/hazptr/LOCKDEP.boot    |  1 +
 .../rcutorture/configs/hazptr/SLOWPATH        | 16 +++++++
 4 files changed, 79 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP
 create mode 100644 tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP.boot
 create mode 100644 tools/testing/selftests/rcutorture/configs/hazptr/SLOWPATH

diff --git a/kernel/rcu/hazptrtorture.c b/kernel/rcu/hazptrtorture.c
index c8b7c208775b..fe09280d063c 100644
--- a/kernel/rcu/hazptrtorture.c
+++ b/kernel/rcu/hazptrtorture.c
@@ -23,6 +23,7 @@
 #include <linux/torture.h>
 #include <linux/hazptr.h>
 #include <linux/rcupdate.h>
+#include <linux/workqueue.h>
 
 #include "rcu.h"
 
@@ -51,6 +52,8 @@ torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s");
 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
+torture_param(bool, wq_churn, false,
+	      "Churn workqueues to exercise lockdep dynamic keys");
 
 static char *torture_type = "hazptr";
 module_param(torture_type, charp, 0444);
@@ -62,6 +65,7 @@ static struct task_struct *preempt_task;
 static struct task_struct **reader_tasks;
 static struct task_struct *do_pending_task;
 static struct task_struct *stats_task;
+static struct task_struct *wq_churn_task;
 
 #define HAZPTR_TORTURE_PIPE_LEN 10
 
@@ -83,6 +87,7 @@ static atomic_t n_hazptr_torture_alloc;
 static atomic_t n_hazptr_torture_alloc_fail;
 static atomic_t n_hazptr_torture_free;
 static atomic_t n_hazptr_torture_error;
+static atomic_t n_hazptr_torture_wq_churn;
 static DEFINE_PER_CPU(atomic_long_t, hazptr_torture_acquires);
 static DEFINE_PER_CPU(atomic_long_t, hazptr_torture_releases);
 static DEFINE_PER_CPU(atomic_long_t, hazptr_torture_acquires_irq);
@@ -668,13 +673,14 @@ hazptr_torture_stats_print(void)
 		atomic_read(&n_hazptr_torture_alloc_fail),
 		atomic_read(&n_hazptr_torture_free));
 	torture_onoff_stats();
-	pr_cont("acq: %lld rel: %lld acqirq: %lld relirq: %lld reldefer: %lld relundefer %lld\n",
+	pr_cont("acq: %lld rel: %lld acqirq: %lld relirq: %lld reldefer: %lld relundefer %lld wqchurn: %d\n",
 		torture_sum_pcpu_atomic_long(&hazptr_torture_acquires),
 		torture_sum_pcpu_atomic_long(&hazptr_torture_releases),
 		torture_sum_pcpu_atomic_long(&hazptr_torture_acquires_irq),
 		torture_sum_pcpu_atomic_long(&hazptr_torture_releases_irq),
 		torture_sum_pcpu_atomic_long(&hazptr_torture_releases_defer),
-		torture_sum_pcpu_atomic_long(&hazptr_torture_releases_undefer));
+		torture_sum_pcpu_atomic_long(&hazptr_torture_releases_undefer),
+		atomic_read(&n_hazptr_torture_wq_churn));
 
 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
 	if (i > 1) {
@@ -788,6 +794,38 @@ static int hazptr_torture_preempt(void *unused)
 	return 0;
 }
 
+static void hazptr_torture_wq_churn_fn(struct work_struct *work)
+{
+}
+
+/*
+ * Repeatedly create and destroy workqueues.  Each workqueue creation
+ * registers a lockdep dynamic key and each destruction unregisters it,
+ * which exercises both is_dynamic_key() and lockdep_unregister_key().
+ */
+static int hazptr_torture_wq_churn(void *unused)
+{
+	VERBOSE_TOROUT_STRING("hazptr_torture_wq_churn task started");
+	do {
+		struct workqueue_struct *wq;
+		struct work_struct churn_work;
+
+		wq = alloc_workqueue("hazptr-torture-churn", WQ_PERCPU, 1);
+		if (!wq) {
+			torture_hrtimeout_ms(10, 10, NULL);
+			continue;
+		}
+		INIT_WORK(&churn_work, hazptr_torture_wq_churn_fn);
+		queue_work(wq, &churn_work);
+		flush_work(&churn_work);
+		destroy_workqueue(wq);
+		atomic_inc(&n_hazptr_torture_wq_churn);
+		stutter_wait("hazptr_torture_wq_churn");
+	} while (!torture_must_stop());
+	torture_kthread_stopping("hazptr_torture_wq_churn");
+	return 0;
+}
+
 static void
 hazptr_torture_cleanup(void)
 {
@@ -880,6 +918,7 @@ static int __init hazptr_torture_init(void)
 	atomic_set(&n_hazptr_torture_alloc_fail, 0);
 	atomic_set(&n_hazptr_torture_free, 0);
 	atomic_set(&n_hazptr_torture_error, 0);
+	atomic_set(&n_hazptr_torture_wq_churn, 0);
 	for (i = 0; i < HAZPTR_TORTURE_PIPE_LEN + 1; i++)
 		atomic_set(&hazptr_torture_wcount[i], 0);
 	for_each_possible_cpu(cpu) {
@@ -960,6 +999,11 @@ static int __init hazptr_torture_init(void)
 		if (torture_init_error(firsterr))
 			goto unwind;
 	}
+	if (wq_churn) {
+		firsterr = torture_create_kthread(hazptr_torture_wq_churn, NULL, wq_churn_task);
+		if (torture_init_error(firsterr))
+			goto unwind;
+	}
 
 	torture_init_end();
 	return 0;
diff --git a/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP b/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP
new file mode 100644
index 000000000000..f0ff29925a54
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP
@@ -0,0 +1,16 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=16
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+CONFIG_HZ_PERIODIC=n
+CONFIG_NO_HZ_IDLE=y
+CONFIG_NO_HZ_FULL=n
+CONFIG_HOTPLUG_CPU=y
+CONFIG_SUSPEND=n
+CONFIG_HIBERNATION=n
+CONFIG_DEBUG_LOCK_ALLOC=y
+CONFIG_PROVE_LOCKING=y
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_DEBUG_KERNEL=y
+CONFIG_HAZPTR_DEBUG=y
diff --git a/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP.boot b/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP.boot
new file mode 100644
index 000000000000..7b16720214bd
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP.boot
@@ -0,0 +1 @@
+hazptrtorture.wq_churn=1
diff --git a/tools/testing/selftests/rcutorture/configs/hazptr/SLOWPATH b/tools/testing/selftests/rcutorture/configs/hazptr/SLOWPATH
new file mode 100644
index 000000000000..4d13028ca84c
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/hazptr/SLOWPATH
@@ -0,0 +1,16 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=16
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+CONFIG_HZ_PERIODIC=n
+CONFIG_NO_HZ_IDLE=y
+CONFIG_NO_HZ_FULL=n
+CONFIG_HOTPLUG_CPU=y
+CONFIG_SUSPEND=n
+CONFIG_HIBERNATION=n
+CONFIG_PROVE_LOCKING=n
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_DEBUG_KERNEL=y
+CONFIG_HAZPTR_DEBUG=y
+CONFIG_HAZPTR_ACQUIRE_FORCE_SLOWPATH=y
-- 
2.43.0