[Qemu-devel] Re: [PATCHv4 09/12] vhost: vhost net support

[Amit Shah]

On (Sat) Mar 06 2010 [21:06:35], Michael S. Tsirkin wrote:
> 
> > > +    r = vhost_virtqueue_set_addr(dev, vq, idx, dev->log_enabled);
> > > +    if (r < 0) {
> > > +        r = -errno;
> > > +        goto fail_alloc;
> > > +    }
> > > +    if (!vdev->binding->guest_notifier || !vdev->binding->host_notifier) 
> > > {
> > > +        fprintf(stderr, "binding does not support irqfd/queuefd\n");
> > > +        r = -ENOSYS;
> > > +        goto fail_alloc;
> > > +    }
> > 
> > This could be checked much earlier on in the function; so that we avoid
> > doing all that stuff above and the cleanup.
> 
> Whatever order we put checks in, we'll have to undo stuff
> done beforehand on error.

Not if you do this check before any ioctls or allocations.
!vdev->binding->guest_notifier is not dependent on anything you do above
it in this function, so just checking for this first thing in the
function will not need any cleanup.


                Amit