1 files changed, 44 insertions, 28 deletions

diff --git a/drivers/staging/most/mostcore/core.c b/drivers/staging/most/mostcore/core.c
index 7c619feb12d3..db0606ca9f79 100644
--- a/drivers/staging/most/mostcore/core.c
+++ b/drivers/staging/most/mostcore/core.c
@@ -33,7 +33,7 @@
 #define STRING_SIZE	80
 
 static struct class *most_class;
-static struct device *class_glue_dir;
+static struct device *core_dev;
 static struct ida mdev_id;
 static int dummy_num_buffers;
 
@@ -51,6 +51,7 @@ struct most_c_obj {
 	u16 channel_id;
 	bool is_poisoned;
 	struct mutex start_mutex;
+	struct mutex nq_mutex; /* nq thread synchronization */
 	int is_starving;
 	struct most_interface *iface;
 	struct most_inst_obj *inst;
@@ -1131,18 +1132,18 @@ static inline void trash_mbo(struct mbo *mbo)
 	spin_unlock_irqrestore(&c->fifo_lock, flags);
 }
 
-static struct mbo *get_hdm_mbo(struct most_c_obj *c)
+static bool hdm_mbo_ready(struct most_c_obj *c)
 {
-	unsigned long flags;
-	struct mbo *mbo;
+	bool empty;
 
-	spin_lock_irqsave(&c->fifo_lock, flags);
-	if (c->enqueue_halt || list_empty(&c->halt_fifo))
-		mbo = NULL;
-	else
-		mbo = list_pop_mbo(&c->halt_fifo);
-	spin_unlock_irqrestore(&c->fifo_lock, flags);
-	return mbo;
+	if (c->enqueue_halt)
+		return false;
+
+	spin_lock_irq(&c->fifo_lock);
+	empty = list_empty(&c->halt_fifo);
+	spin_unlock_irq(&c->fifo_lock);
+
+	return !empty;
 }
 
 static void nq_hdm_mbo(struct mbo *mbo)
@@ -1160,20 +1161,32 @@ static int hdm_enqueue_thread(void *data)
 {
 	struct most_c_obj *c = data;
 	struct mbo *mbo;
+	int ret;
 	typeof(c->iface->enqueue) enqueue = c->iface->enqueue;
 
 	while (likely(!kthread_should_stop())) {
 		wait_event_interruptible(c->hdm_fifo_wq,
-					 (mbo = get_hdm_mbo(c)) ||
+					 hdm_mbo_ready(c) ||
 					 kthread_should_stop());
 
-		if (unlikely(!mbo))
+		mutex_lock(&c->nq_mutex);
+		spin_lock_irq(&c->fifo_lock);
+		if (unlikely(c->enqueue_halt || list_empty(&c->halt_fifo))) {
+			spin_unlock_irq(&c->fifo_lock);
+			mutex_unlock(&c->nq_mutex);
 			continue;
+		}
+
+		mbo = list_pop_mbo(&c->halt_fifo);
+		spin_unlock_irq(&c->fifo_lock);
 
 		if (c->cfg.direction == MOST_CH_RX)
 			mbo->buffer_length = c->cfg.buffer_size;
 
-		if (unlikely(enqueue(mbo->ifp, mbo->hdm_channel_id, mbo))) {
+		ret = enqueue(mbo->ifp, mbo->hdm_channel_id, mbo);
+		mutex_unlock(&c->nq_mutex);
+
+		if (unlikely(ret)) {
 			pr_err("hdm enqueue failed\n");
 			nq_hdm_mbo(mbo);
 			c->hdm_enqueue_task = NULL;
@@ -1468,10 +1481,8 @@ static void most_read_completion(struct mbo *mbo)
 		return;
 	}
 
-	if (atomic_sub_and_test(1, &c->mbo_nq_level)) {
-		pr_info("WARN: rx device out of buffers\n");
+	if (atomic_sub_and_test(1, &c->mbo_nq_level))
 		c->is_starving = 1;
-	}
 
 	if (c->aim0.refs && c->aim0.ptr->rx_completion &&
 	    c->aim0.ptr->rx_completion(mbo) == 0)
@@ -1761,6 +1772,7 @@ struct kobject *most_register_interface(struct most_interface *iface)
 		init_completion(&c->cleanup);
 		atomic_set(&c->mbo_ref, 0);
 		mutex_init(&c->start_mutex);
+		mutex_init(&c->nq_mutex);
 		list_add_tail(&c->list, &inst->channel_list);
 	}
 	pr_info("registered new MOST device mdev%d (%s)\n",
@@ -1826,8 +1838,12 @@ void most_stop_enqueue(struct most_interface *iface, int id)
 {
 	struct most_c_obj *c = get_channel_by_iface(iface, id);
 
-	if (likely(c))
-		c->enqueue_halt = true;
+	if (!c)
+		return;
+
+	mutex_lock(&c->nq_mutex);
+	c->enqueue_halt = true;
+	mutex_unlock(&c->nq_mutex);
 }
 EXPORT_SYMBOL_GPL(most_stop_enqueue);
 
@@ -1843,9 +1859,12 @@ void most_resume_enqueue(struct most_interface *iface, int id)
 {
 	struct most_c_obj *c = get_channel_by_iface(iface, id);
 
-	if (unlikely(!c))
+	if (!c)
 		return;
+
+	mutex_lock(&c->nq_mutex);
 	c->enqueue_halt = false;
+	mutex_unlock(&c->nq_mutex);
 
 	wake_up_interruptible(&c->hdm_fifo_wq);
 }
@@ -1879,22 +1898,19 @@ static int __init most_init(void)
 		goto exit_class;
 	}
 
-	class_glue_dir =
-		device_create(most_class, NULL, 0, NULL, "mostcore");
-	if (IS_ERR(class_glue_dir)) {
-		err = PTR_ERR(class_glue_dir);
+	core_dev = device_create(most_class, NULL, 0, NULL, "mostcore");
+	if (IS_ERR(core_dev)) {
+		err = PTR_ERR(core_dev);
 		goto exit_driver;
 	}
 
-	most_aim_kset =
-		kset_create_and_add("aims", NULL, &class_glue_dir->kobj);
+	most_aim_kset = kset_create_and_add("aims", NULL, &core_dev->kobj);
 	if (!most_aim_kset) {
 		err = -ENOMEM;
 		goto exit_class_container;
 	}
 
-	most_inst_kset =
-		kset_create_and_add("devices", NULL, &class_glue_dir->kobj);
+	most_inst_kset = kset_create_and_add("devices", NULL, &core_dev->kobj);
 	if (!most_inst_kset) {
 		err = -ENOMEM;
 		goto exit_driver_kset;