[Q] vhost: returning misconfigured buffers

[Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>]

Hi,

Many vhost drivers follow a common process to obtain and verify 
received buffers:

head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov), &out, &in,...);
if (head < 0) {
	return ret;
}
if (head == vq->num) {
	/* no buffer */
	return 0; /* or -EAGAIN or whatever */
}
if (out != EXPECTED_OUT_BUFFERS || in != EXPECTED_IN_BUFFERS) {
	return -EINVAL;
}
/* all good, use buffers */
vhost_add_used(...);

Which seems to me to be leaking buffers in the last error case - 
if the buffer configuration was unexpected. Shouldn't drivers in 
such cases also use vhost_add_used() to return the buffer?

Thanks
Guennadi