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

Cornelia Huck
2014-12-09T10:46:59Z

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:

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,