linux-kernel - Re: [PATCH v3 3/6] virtio: allow finalize

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Date:	Tue, 9 Dec 2014 11:46:59 +0100
From:	Cornelia Huck <cornelia.huck@...ibm.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	linux-kernel@...r.kernel.org, dahi@...ux.vnet.ibm.com,
	rusty@...tcorp.com.au, Ohad Ben-Cohen <ohad@...ery.com>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	linux390@...ibm.com, Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Sudeep Dutt <sudeep.dutt@...el.com>,
	Siva Yerramreddy <yshivakrishna@...il.com>,
	lguest@...ts.ozlabs.org, linux-s390@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v3 3/6] virtio: allow finalize_features to fail

On Mon, 8 Dec 2014 15:05:58 +0200
"Michael S. Tsirkin" <mst@...hat.com> wrote:

> This will make it easy for transports to validate features and return
> failure.
> 
> Signed-off-by: Michael S. Tsirkin <mst@...hat.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,

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