Re: [PATCH] virtio-vdpa: Fix unchecked call to NULL set_vq_affinity

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, May 04, 2023 at 01:08:54PM -0400, Feng Liu wrote:
> 
> 
> On 2023-05-04 a.m.9:50, Dragos Tatulea wrote:
> > External email: Use caution opening links or attachments
> > 
> > 
> > The referenced patch calls set_vq_affinity without checking if the op is
> > valid. This patch adds the check.
> > 
> > Fixes: 3dad56823b53 ("virtio-vdpa: Support interrupt affinity spreading mechanism")
> > Reviewed-by: Gal Pressman <gal@nvidia.com>
> > Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
> > ---
> >   drivers/virtio/virtio_vdpa.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> > index eb6aee8c06b2..989e2d7184ce 100644
> > --- a/drivers/virtio/virtio_vdpa.c
> > +++ b/drivers/virtio/virtio_vdpa.c
> > @@ -385,7 +385,9 @@ static int virtio_vdpa_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
> >                          err = PTR_ERR(vqs[i]);
> >                          goto err_setup_vq;
> >                  }
> > -               ops->set_vq_affinity(vdpa, i, &masks[i]);
> > +
> > +               if (ops->set_vq_affinity)
> > +                       ops->set_vq_affinity(vdpa, i, &masks[i]);
> if ops->set_vq_affinity is NULL, should give an error code to err, and
> return err

Given we ignore return code, hardly seems like a critical thing to do.
Is it really important? affinity is an optimization isn't it?

> >          }
> > 
> >          cb.callback = virtio_vdpa_config_cb;
> > --
> > 2.40.1
> >