static int vfio_group_get_device_fd()

in vfio.c [1333:1409]

• 56 lines of code
• 16 McCabe index (conditional complexity)

static int vfio_group_get_device_fd(struct vfio_group *group, char *buf)
{
	struct vfio_device *device;
	struct file *filep;
	int fdno;
	int ret = 0;

	if (0 == atomic_read(&group->container_users) ||
	    !group->container->iommu_driver || !vfio_group_viable(group))
		return -EINVAL;

	if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO))
		return -EPERM;

	device = vfio_device_get_from_name(group, buf);
	if (IS_ERR(device))
		return PTR_ERR(device);

	if (!try_module_get(device->dev->driver->owner)) {
		ret = -ENODEV;
		goto err_device_put;
	}

	mutex_lock(&device->dev_set->lock);
	device->open_count++;
	if (device->open_count == 1 && device->ops->open_device) {
		ret = device->ops->open_device(device);
		if (ret)
			goto err_undo_count;
	}
	mutex_unlock(&device->dev_set->lock);

	/*
	 * We can't use anon_inode_getfd() because we need to modify
	 * the f_mode flags directly to allow more than just ioctls
	 */
	fdno = ret = get_unused_fd_flags(O_CLOEXEC);
	if (ret < 0)
		goto err_close_device;

	filep = anon_inode_getfile("[vfio-device]", &vfio_device_fops,
				   device, O_RDWR);
	if (IS_ERR(filep)) {
		ret = PTR_ERR(filep);
		goto err_fd;
	}

	/*
	 * TODO: add an anon_inode interface to do this.
	 * Appears to be missing by lack of need rather than
	 * explicitly prevented.  Now there's need.
	 */
	filep->f_mode |= (FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);

	atomic_inc(&group->container_users);

	fd_install(fdno, filep);

	if (group->type == VFIO_NO_IOMMU)
		dev_warn(device->dev, "vfio-noiommu device opened by user "
			 "(%s:%d)\n", current->comm, task_pid_nr(current));
	return fdno;

err_fd:
	put_unused_fd(fdno);
err_close_device:
	mutex_lock(&device->dev_set->lock);
	if (device->open_count == 1 && device->ops->close_device)
		device->ops->close_device(device);
err_undo_count:
	device->open_count--;
	mutex_unlock(&device->dev_set->lock);
	module_put(device->dev->driver->owner);
err_device_put:
	vfio_device_put(device);
	return ret;
}