Re: [PATCH v3 3/6] virtio: allow finalize_features to fail

Michael S. Tsirkin
2014-12-09T12:07:54Z

On Tue, Dec 09, 2014 at 11:46:59AM +0100, Cornelia Huck wrote:
> On Mon, 8 Dec 2014 15:05:58 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> > This will make it easy for transports to validate features and return
> > failure.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> > include/linux/virtio_config.h | 3 ++-
> > drivers/lguest/lguest_device.c | 4 +++-
> > drivers/misc/mic/card/mic_virtio.c | 4 +++-
> > drivers/remoteproc/remoteproc_virtio.c | 4 +++-
> > drivers/s390/kvm/kvm_virtio.c | 4 +++-
> > drivers/s390/kvm/virtio_ccw.c | 6 ++++--
> > drivers/virtio/virtio.c | 21 ++++++++++++++-------
> > drivers/virtio/virtio_mmio.c | 4 +++-
> > drivers/virtio/virtio_pci.c | 4 +++-
> > 9 files changed, 38 insertions(+), 16 deletions(-)
> >
>
> > diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
> > index c792b5f..789275f 100644
> > --- a/drivers/s390/kvm/virtio_ccw.c
> > +++ b/drivers/s390/kvm/virtio_ccw.c
> > @@ -752,7 +752,7 @@ out_free:
> > return rc;
> > }
> >
> > -static void virtio_ccw_finalize_features(struct virtio_device *vdev)
> > +static int virtio_ccw_finalize_features(struct virtio_device *vdev)
> > {
> > struct virtio_ccw_device *vcdev = to_vc_device(vdev);
> > struct virtio_feature_desc *features;
> > @@ -760,7 +760,7 @@ static void virtio_ccw_finalize_features(struct virtio_device *vdev)
> >
> > ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
> > if (!ccw)
> > - return;
> > + return 0;
>
> I think we'll want to return an error in this case as well to fail
> probing. Also for the other places where something can go wrong.
> Something like this:

I guess the fact this previously failed silently is a bug in original
code?

Can you please send your S.O.B so I can add this patch on top?

We might also need to Cc stable.

> diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
> index 789275f..bc6e671 100644
> --- a/drivers/s390/kvm/virtio_ccw.c
> +++ b/drivers/s390/kvm/virtio_ccw.c
> @@ -757,15 +757,17 @@ static int virtio_ccw_finalize_features(struct virtio_device *vdev)
> struct virtio_ccw_device *vcdev = to_vc_device(vdev);
> struct virtio_feature_desc *features;
> struct ccw1 *ccw;
> + int ret;
>
> ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
> if (!ccw)
> - return 0;
> + return -ENOMEM;
>
> features = kzalloc(sizeof(*features), GFP_DMA | GFP_KERNEL);
> - if (!features)
> + if (!features) {
> + ret = -ENOMEM;
> goto out_free;
> -
> + }
> /* Give virtio_ring a chance to accept features. */
> vring_transport_features(vdev);
>
> @@ -776,7 +778,9 @@ static int virtio_ccw_finalize_features(struct virtio_device *vdev)
> ccw->flags = 0;
> ccw->count = sizeof(*features);
> ccw->cda = (__u32)(unsigned long)features;
> - ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);
> + ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);
> + if (ret)
> + goto out_free;
>
> if (vcdev->revision == 0)
> goto out_free;
> @@ -788,13 +792,13 @@ static int virtio_ccw_finalize_features(struct virtio_device *vdev)
> ccw->flags = 0;
> ccw->count = sizeof(*features);
> ccw->cda = (__u32)(unsigned long)features;
> - ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);
> + ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);
>
> out_free:
> kfree(features);
> kfree(ccw);
>
> - return 0;
> + return ret;
> }
>
> static void virtio_ccw_get_config(struct virtio_device *vdev,