Patch "ubi: block: Fix locking for idr_alloc/idr_remove" has been added to the 4.4-stable tree

@@ -99,6 +99,8 @@ struct ubiblock {
 
 /* Linked list of all ubiblock instances */
 static LIST_HEAD(ubiblock_devices);
+static DEFINE_IDR(ubiblock_minor_idr);
+/* Protects ubiblock_devices and ubiblock_minor_idr */
 static DEFINE_MUTEX(devices_mutex);
 static int ubiblock_major;
 

@@ -354,8 +356,6 @@ static struct blk_mq_ops ubiblock_mq_ops
 	.map_queue      = blk_mq_map_queue,
 };
 
-static DEFINE_IDR(ubiblock_minor_idr);
-
 int ubiblock_create(struct ubi_volume_info *vi)
 {
 	struct ubiblock *dev;

@@ -368,14 +368,15 @@ int ubiblock_create(struct ubi_volume_in
 	/* Check that the volume isn't already handled */
 	mutex_lock(&devices_mutex);
 	if (find_dev_nolock(vi->ubi_num, vi->vol_id)) {
-		mutex_unlock(&devices_mutex);
-		return -EEXIST;
+		ret = -EEXIST;
+		goto out_unlock;
 	}
-	mutex_unlock(&devices_mutex);
 
 	dev = kzalloc(sizeof(struct ubiblock), GFP_KERNEL);
-	if (!dev)
-		return -ENOMEM;
+	if (!dev) {
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
 
 	mutex_init(&dev->dev_mutex);
 

@@ -440,14 +441,13 @@ int ubiblock_create(struct ubi_volume_in
 		goto out_free_queue;
 	}
 
-	mutex_lock(&devices_mutex);
 	list_add_tail(&dev->list, &ubiblock_devices);
-	mutex_unlock(&devices_mutex);
 
 	/* Must be the last step: anyone can call file ops from now on */
 	add_disk(dev->gd);
 	dev_info(disk_to_dev(dev->gd), "created from ubi%d:%d(%s)",
 		 dev->ubi_num, dev->vol_id, vi->name);
+	mutex_unlock(&devices_mutex);
 	return 0;
 
 out_free_queue:

@@ -460,6 +460,8 @@ out_put_disk:
 	put_disk(dev->gd);
 out_free_dev:
 	kfree(dev);
+out_unlock:
+	mutex_unlock(&devices_mutex);
 
 	return ret;
 }

@@ -481,30 +483,36 @@ static void ubiblock_cleanup(struct ubib
 int ubiblock_remove(struct ubi_volume_info *vi)
 {
 	struct ubiblock *dev;
+	int ret;
 
 	mutex_lock(&devices_mutex);
 	dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
 	if (!dev) {
-		mutex_unlock(&devices_mutex);
-		return -ENODEV;
+		ret = -ENODEV;
+		goto out_unlock;
 	}
 
 	/* Found a device, let's lock it so we can check if it's busy */
 	mutex_lock(&dev->dev_mutex);
 	if (dev->refcnt > 0) {
-		mutex_unlock(&dev->dev_mutex);
-		mutex_unlock(&devices_mutex);
-		return -EBUSY;
+		ret = -EBUSY;
+		goto out_unlock_dev;
 	}
 
 	/* Remove from device list */
 	list_del(&dev->list);
-	mutex_unlock(&devices_mutex);
-
 	ubiblock_cleanup(dev);
 	mutex_unlock(&dev->dev_mutex);
+	mutex_unlock(&devices_mutex);
+
 	kfree(dev);
 	return 0;
+
+out_unlock_dev:
+	mutex_unlock(&dev->dev_mutex);
+out_unlock:
+	mutex_unlock(&devices_mutex);
+	return ret;
 }
 
 static int ubiblock_resize(struct ubi_volume_info *vi)

@@ -633,6 +641,7 @@ static void ubiblock_remove_all(void)
 	struct ubiblock *next;
 	struct ubiblock *dev;
 
+	mutex_lock(&devices_mutex);
 	list_for_each_entry_safe(dev, next, &ubiblock_devices, list) {
 		/* The module is being forcefully removed */
 		WARN_ON(dev->desc);

@@ -641,6 +650,7 @@ static void ubiblock_remove_all(void)
 		ubiblock_cleanup(dev);
 		kfree(dev);
 	}
+	mutex_unlock(&devices_mutex);
 }
 
 int __init ubiblock_init(void)