static int get_rx_bufs(struct vhost_virtqueue *vq,
		       struct vring_used_elem *heads,
		       int datalen,
		       unsigned *iovcount,
		       struct vhost_log *log,
		       unsigned *log_num,
		       unsigned int quota)
{
	unsigned int out, in;
	int seg = 0;
	int headcount = 0;
	unsigned d;
	int r, nlogs = 0;
	/* len is always initialized before use since we are always called with
	 * datalen > 0.
	 */
	u32 uninitialized_var(len);

	while (datalen > 0 && headcount < quota) {
		if (unlikely(seg >= UIO_MAXIOV)) {
			r = -ENOBUFS;
			goto err;
		}
		r = vhost_get_vq_desc(vq, vq->iov + seg,
				      ARRAY_SIZE(vq->iov) - seg, &out,
				      &in, log, log_num);
		if (unlikely(r < 0))
			goto err;

		d = r;
		if (d == vq->num) {
			r = 0;
			goto err;
		}
		if (unlikely(out || in <= 0)) {
			vq_err(vq, "unexpected descriptor format for RX: "
				"out %d, in %d\n", out, in);
			r = -EINVAL;
			goto err;
		}
		if (unlikely(log)) {
			nlogs += *log_num;
			log += *log_num;
		}
		heads[headcount].id = cpu_to_vhost32(vq, d);
		len = iov_length(vq->iov + seg, in);
		heads[headcount].len = cpu_to_vhost32(vq, len);
		datalen -= len;
		++headcount;
		seg += in;
	}
	heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
	*iovcount = seg;
	if (unlikely(log))
		*log_num = nlogs;

	/* Detect overrun */
	if (unlikely(datalen > 0)) {
		r = UIO_MAXIOV + 1;
		goto err;
	}
	return headcount;
err:
	vhost_discard_vq_desc(vq, headcount);
	return r;
}
Unknown