Date:   Tue, 16 Mar 2021 11:31:19 -0400
From:   Waiman Long <longman@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Boqun Feng <boqun.feng@...il.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Davidlohr Bueso <dave@...olabs.net>
Cc:     linux-kernel@...r.kernel.org, Juri Lelli <juri.lelli@...hat.com>,
        Waiman Long <longman@...hat.com>
Subject: [PATCH 4/4] locking/locktorture: Fix incorrect use of ww_acquire_ctx in ww_mutex test

The ww_acquire_ctx structure for ww_mutex needs to persist for a complete
lock/unlock cycle. In the ww_mutex test in locktorture, however, both
ww_acquire_init() and ww_acquire_fini() are called within the lock
function only. This causes a lockdep splat of "WARNING: Nested lock
was not taken" when lockdep is enabled in the kernel.

To fix this problem, we need to move the ww_acquire_fini() after the
ww_mutex_unlock() in torture_ww_mutex_unlock(). In other word, we need
to pass state information from the lock function to the unlock function.
Change the writelock and writeunlock function prototypes to allow that
and change the torture_ww_mutex_lock() and torture_ww_mutex_unlock()
accordingly.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 kernel/locking/locktorture.c | 86 +++++++++++++++++++++++-------------
 1 file changed, 56 insertions(+), 30 deletions(-)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 0ab94e1f1276..782925dcf5d9 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -76,10 +76,10 @@ static void lock_torture_cleanup(void);
 struct lock_torture_ops {
 	void (*init)(void);
 	void (*exit)(void);
-	int (*writelock)(void);
+	int (*writelock)(void **parg);
 	void (*write_delay)(struct torture_random_state *trsp);
 	void (*task_boost)(struct torture_random_state *trsp);
-	void (*writeunlock)(void);
+	void (*writeunlock)(void *arg);
 	int (*readlock)(void);
 	void (*read_delay)(struct torture_random_state *trsp);
 	void (*readunlock)(void);
@@ -105,7 +105,7 @@ static struct lock_torture_cxt cxt = { 0, 0, false, false,
  * Definitions for lock torture testing.
  */
 
-static int torture_lock_busted_write_lock(void)
+static int torture_lock_busted_write_lock(void **parg __maybe_unused)
 {
 	return 0;  /* BUGGY, do not use in real life!!! */
 }
@@ -122,7 +122,7 @@ static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
 
-static void torture_lock_busted_write_unlock(void)
+static void torture_lock_busted_write_unlock(void *arg __maybe_unused)
 {
 	  /* BUGGY, do not use in real life!!! */
 }
@@ -145,7 +145,8 @@ static struct lock_torture_ops lock_busted_ops = {
 
 static DEFINE_SPINLOCK(torture_spinlock);
 
-static int torture_spin_lock_write_lock(void) __acquires(torture_spinlock)
+static int torture_spin_lock_write_lock(void **parg __maybe_unused)
+__acquires(torture_spinlock)
 {
 	spin_lock(&torture_spinlock);
 	return 0;
@@ -169,7 +170,8 @@ static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
 
-static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
+static void torture_spin_lock_write_unlock(void *arg __maybe_unused)
+__releases(torture_spinlock)
 {
 	spin_unlock(&torture_spinlock);
 }
@@ -185,7 +187,7 @@ static struct lock_torture_ops spin_lock_ops = {
 	.name		= "spin_lock"
 };
 
-static int torture_spin_lock_write_lock_irq(void)
+static int torture_spin_lock_write_lock_irq(void **parg __maybe_unused)
 __acquires(torture_spinlock)
 {
 	unsigned long flags;
@@ -195,7 +197,7 @@ __acquires(torture_spinlock)
 	return 0;
 }
 
-static void torture_lock_spin_write_unlock_irq(void)
+static void torture_lock_spin_write_unlock_irq(void *arg __maybe_unused)
 __releases(torture_spinlock)
 {
 	spin_unlock_irqrestore(&torture_spinlock, cxt.cur_ops->flags);
@@ -214,7 +216,8 @@ static struct lock_torture_ops spin_lock_irq_ops = {
 
 static DEFINE_RWLOCK(torture_rwlock);
 
-static int torture_rwlock_write_lock(void) __acquires(torture_rwlock)
+static int torture_rwlock_write_lock(void **parg __maybe_unused)
+__acquires(torture_rwlock)
 {
 	write_lock(&torture_rwlock);
 	return 0;
@@ -235,7 +238,8 @@ static void torture_rwlock_write_delay(struct torture_random_state *trsp)
 		udelay(shortdelay_us);
 }
 
-static void torture_rwlock_write_unlock(void) __releases(torture_rwlock)
+static void torture_rwlock_write_unlock(void *arg __maybe_unused)
+__releases(torture_rwlock)
 {
 	write_unlock(&torture_rwlock);
 }
@@ -277,7 +281,8 @@ static struct lock_torture_ops rw_lock_ops = {
 	.name		= "rw_lock"
 };
 
-static int torture_rwlock_write_lock_irq(void) __acquires(torture_rwlock)
+static int torture_rwlock_write_lock_irq(void **parg __maybe_unused)
+__acquires(torture_rwlock)
 {
 	unsigned long flags;
 
@@ -286,7 +291,7 @@ static int torture_rwlock_write_lock_irq(void) __acquires(torture_rwlock)
 	return 0;
 }
 
-static void torture_rwlock_write_unlock_irq(void)
+static void torture_rwlock_write_unlock_irq(void *arg __maybe_unused)
 __releases(torture_rwlock)
 {
 	write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
@@ -320,7 +325,8 @@ static struct lock_torture_ops rw_lock_irq_ops = {
 
 static DEFINE_MUTEX(torture_mutex);
 
-static int torture_mutex_lock(void) __acquires(torture_mutex)
+static int torture_mutex_lock(void **parg __maybe_unused)
+__acquires(torture_mutex)
 {
 	mutex_lock(&torture_mutex);
 	return 0;
@@ -340,7 +346,8 @@ static void torture_mutex_delay(struct torture_random_state *trsp)
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
 
-static void torture_mutex_unlock(void) __releases(torture_mutex)
+static void torture_mutex_unlock(void *arg __maybe_unused)
+__releases(torture_mutex)
 {
 	mutex_unlock(&torture_mutex);
 }
@@ -362,7 +369,7 @@ static DEFINE_WW_MUTEX(torture_ww_mutex_0, &torture_ww_class);
 static DEFINE_WW_MUTEX(torture_ww_mutex_1, &torture_ww_class);
 static DEFINE_WW_MUTEX(torture_ww_mutex_2, &torture_ww_class);
 
-static int torture_ww_mutex_lock(void)
+static int torture_ww_mutex_lock(void **parg)
 __acquires(torture_ww_mutex_0)
 __acquires(torture_ww_mutex_1)
 __acquires(torture_ww_mutex_2)
@@ -372,7 +379,12 @@ __acquires(torture_ww_mutex_2)
 		struct list_head link;
 		struct ww_mutex *lock;
 	} locks[3], *ll, *ln;
-	struct ww_acquire_ctx ctx;
+	struct ww_acquire_ctx *ctx;
+
+	ctx = kmalloc(sizeof(struct ww_acquire_ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+	*parg = ctx;
 
 	locks[0].lock = &torture_ww_mutex_0;
 	list_add(&locks[0].link, &list);
@@ -383,12 +395,12 @@ __acquires(torture_ww_mutex_2)
 	locks[2].lock = &torture_ww_mutex_2;
 	list_add(&locks[2].link, &list);
 
-	ww_acquire_init(&ctx, &torture_ww_class);
+	ww_acquire_init(ctx, &torture_ww_class);
 
 	list_for_each_entry(ll, &list, link) {
 		int err;
 
-		err = ww_mutex_lock(ll->lock, &ctx);
+		err = ww_mutex_lock(ll->lock, ctx);
 		if (!err)
 			continue;
 
@@ -399,22 +411,28 @@ __acquires(torture_ww_mutex_2)
 		if (err != -EDEADLK)
 			return err;
 
-		ww_mutex_lock_slow(ll->lock, &ctx);
+		ww_mutex_lock_slow(ll->lock, ctx);
 		list_move(&ll->link, &list);
 	}
 
-	ww_acquire_fini(&ctx);
 	return 0;
 }
 
-static void torture_ww_mutex_unlock(void)
+static void torture_ww_mutex_unlock(void *arg)
 __releases(torture_ww_mutex_0)
 __releases(torture_ww_mutex_1)
 __releases(torture_ww_mutex_2)
 {
+	struct ww_acquire_ctx *ctx = arg;
+
+	if (!ctx)
+		return;
+
 	ww_mutex_unlock(&torture_ww_mutex_0);
 	ww_mutex_unlock(&torture_ww_mutex_1);
 	ww_mutex_unlock(&torture_ww_mutex_2);
+	ww_acquire_fini(ctx);
+	kfree(ctx);
 }
 
 static struct lock_torture_ops ww_mutex_lock_ops = {
@@ -431,7 +449,8 @@ static struct lock_torture_ops ww_mutex_lock_ops = {
 #ifdef CONFIG_RT_MUTEXES
 static DEFINE_RT_MUTEX(torture_rtmutex);
 
-static int torture_rtmutex_lock(void) __acquires(torture_rtmutex)
+static int torture_rtmutex_lock(void **parg __maybe_unused)
+__acquires(torture_rtmutex)
 {
 	rt_mutex_lock(&torture_rtmutex);
 	return 0;
@@ -487,7 +506,8 @@ static void torture_rtmutex_delay(struct torture_random_state *trsp)
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
 
-static void torture_rtmutex_unlock(void) __releases(torture_rtmutex)
+static void torture_rtmutex_unlock(void *arg __maybe_unused)
+__releases(torture_rtmutex)
 {
 	rt_mutex_unlock(&torture_rtmutex);
 }
@@ -505,7 +525,8 @@ static struct lock_torture_ops rtmutex_lock_ops = {
 #endif
 
 static DECLARE_RWSEM(torture_rwsem);
-static int torture_rwsem_down_write(void) __acquires(torture_rwsem)
+static int torture_rwsem_down_write(void **parg __maybe_unused)
+__acquires(torture_rwsem)
 {
 	down_write(&torture_rwsem);
 	return 0;
@@ -525,7 +546,8 @@ static void torture_rwsem_write_delay(struct torture_random_state *trsp)
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
 
-static void torture_rwsem_up_write(void) __releases(torture_rwsem)
+static void torture_rwsem_up_write(void *arg __maybe_unused)
+__releases(torture_rwsem)
 {
 	up_write(&torture_rwsem);
 }
@@ -579,13 +601,15 @@ static void torture_percpu_rwsem_exit(void)
 	percpu_free_rwsem(&pcpu_rwsem);
 }
 
-static int torture_percpu_rwsem_down_write(void) __acquires(pcpu_rwsem)
+static int torture_percpu_rwsem_down_write(void **parg __maybe_unused)
+__acquires(pcpu_rwsem)
 {
 	percpu_down_write(&pcpu_rwsem);
 	return 0;
 }
 
-static void torture_percpu_rwsem_up_write(void) __releases(pcpu_rwsem)
+static void torture_percpu_rwsem_up_write(void *arg __maybe_unused)
+__releases(pcpu_rwsem)
 {
 	percpu_up_write(&pcpu_rwsem);
 }
@@ -618,7 +642,7 @@ static struct lock_torture_ops percpu_rwsem_lock_ops = {
  * Lock torture writer kthread.  Repeatedly acquires and releases
  * the lock, checking for duplicate acquisitions.
  */
-static int lock_torture_writer(void *arg)
+static int lock_torture_writer(void *arg __maybe_unused)
 {
 	struct lock_stress_stats *lwsp = arg;
 	DEFINE_TORTURE_RANDOM(rand);
@@ -627,11 +651,13 @@ static int lock_torture_writer(void *arg)
 	set_user_nice(current, MAX_NICE);
 
 	do {
+		void *arg = NULL;
+
 		if ((torture_random(&rand) & 0xfffff) == 0)
 			schedule_timeout_uninterruptible(1);
 
 		cxt.cur_ops->task_boost(&rand);
-		cxt.cur_ops->writelock();
+		cxt.cur_ops->writelock(&arg);
 		if (WARN_ON_ONCE(lock_is_write_held))
 			lwsp->n_lock_fail++;
 		lock_is_write_held = true;
@@ -642,7 +668,7 @@ static int lock_torture_writer(void *arg)
 		cxt.cur_ops->write_delay(&rand);
 		lock_is_write_held = false;
 		WRITE_ONCE(last_lock_release, jiffies);
-		cxt.cur_ops->writeunlock();
+		cxt.cur_ops->writeunlock(arg);
 
 		stutter_wait("lock_torture_writer");
 	} while (!torture_must_stop());
-- 
2.18.1

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