Merge tag 'vfio-v4.2-rc5' of git://github.com/awilliam/linux-vfio

Pull VFIO fix from Alex Williamson:
 "Fix a lockdep reported deadlock in device open error path"

* tag 'vfio-v4.2-rc5' of git://github.com/awilliam/linux-vfio:
  vfio: Fix lockdep issue

drivers/vfio/vfio.c

@@ -689,6 +689,23 @@ struct vfio_device *vfio_device_get_from_dev(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(vfio_device_get_from_dev);
 
+static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
+						     char *buf)
+{
+	struct vfio_device *device;
+
+	mutex_lock(&group->device_lock);
+	list_for_each_entry(device, &group->device_list, group_next) {
+		if (!strcmp(dev_name(device->dev), buf)) {
+			vfio_device_get(device);
+			break;
+		}
+	}
+	mutex_unlock(&group->device_lock);
+
+	return device;
+}
+
 /*
  * Caller must hold a reference to the vfio_device
  */
@@ -1198,20 +1215,22 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 {
 	struct vfio_device *device;
 	struct file *filep;
-	int ret = -ENODEV;
+	int ret;
 
 	if (0 == atomic_read(&group->container_users) ||
 	    !group->container->iommu_driver || !vfio_group_viable(group))
 		return -EINVAL;
 
-	mutex_lock(&group->device_lock);
-	list_for_each_entry(device, &group->device_list, group_next) {
-		if (strcmp(dev_name(device->dev), buf))
-			continue;
+	device = vfio_device_get_from_name(group, buf);
+	if (!device)
+		return -ENODEV;
 
 	ret = device->ops->open(device->device_data);
-		if (ret)
-			break;
+	if (ret) {
+		vfio_device_put(device);
+		return ret;
+	}
+
 	/*
 	 * We can't use anon_inode_getfd() because we need to modify
 	 * the f_mode flags directly to allow more than just ioctls
@@ -1219,7 +1238,8 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 	ret = get_unused_fd_flags(O_CLOEXEC);
 	if (ret < 0) {
 		device->ops->release(device->device_data);
-			break;
+		vfio_device_put(device);
+		return ret;
 	}
 
 	filep = anon_inode_getfile("[vfio-device]", &vfio_device_fops,
@@ -1228,7 +1248,8 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 		put_unused_fd(ret);
 		ret = PTR_ERR(filep);
 		device->ops->release(device->device_data);
-			break;
+		vfio_device_put(device);
+		return ret;
 	}
 
 	/*
@@ -1238,13 +1259,9 @@ static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
 	 */
 	filep->f_mode |= (FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
 
-		vfio_device_get(device);
 	atomic_inc(&group->container_users);
 
 	fd_install(ret, filep);
-		break;
-	}
-	mutex_unlock(&group->device_lock);
 
 	return ret;
 }