static ssize_t vduse_dev_read_iter()

in vdpa_user/vduse_dev.c [298:340]

• 37 lines of code
• 7 McCabe index (conditional complexity)

static ssize_t vduse_dev_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
	struct file *file = iocb->ki_filp;
	struct vduse_dev *dev = file->private_data;
	struct vduse_dev_msg *msg;
	int size = sizeof(struct vduse_dev_request);
	ssize_t ret;

	if (iov_iter_count(to) < size)
		return -EINVAL;

	spin_lock(&dev->msg_lock);
	while (1) {
		msg = vduse_dequeue_msg(&dev->send_list);
		if (msg)
			break;

		ret = -EAGAIN;
		if (file->f_flags & O_NONBLOCK)
			goto unlock;

		spin_unlock(&dev->msg_lock);
		ret = wait_event_interruptible_exclusive(dev->waitq,
					!list_empty(&dev->send_list));
		if (ret)
			return ret;

		spin_lock(&dev->msg_lock);
	}
	spin_unlock(&dev->msg_lock);
	ret = copy_to_iter(&msg->req, size, to);
	spin_lock(&dev->msg_lock);
	if (ret != size) {
		ret = -EFAULT;
		vduse_enqueue_msg(&dev->send_list, msg);
		goto unlock;
	}
	vduse_enqueue_msg(&dev->recv_list, msg);
unlock:
	spin_unlock(&dev->msg_lock);

	return ret;
}