[PATCH v7 19/46] KVM: s390 allow virtio_ccw status writes to fail

Michael S. Tsirkin
2014-11-30T15:11:13Z

Gracefully handle failure to write device status.
We really should handle other errors as well, but this one is needed for
virtio 1.0 compliance.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
drivers/s390/kvm/virtio_ccw.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 1c21c08..45ab269 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -862,7 +862,9 @@ static u8 virtio_ccw_get_status(struct virtio_device *vdev)
static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
{
struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+ u8 old_status = *vcdev->status;
struct ccw1 *ccw;
+ int ret;

ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
if (!ccw)
@@ -874,7 +876,10 @@ static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
ccw->flags = 0;
ccw->count = sizeof(status);
ccw->cda = (__u32)(unsigned long)vcdev->status;
- ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_STATUS);
+ ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_STATUS);
+ /* Write failed? We assume status is unchanged. */
+ if (ret)
+ *vcdev->status = old_status;
kfree(ccw);
}

--
MST