[PATCH 4/4] locking/locktorture: Fix incorrect use of ww_acquire_ctx in ww_mutex test

Waiman Long
2021-03-16T15:33:20Z

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@redhat.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