From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 23 Oct 2014 19:22:33 +0200 From: Cornelia Huck Subject: Re: [PATCH RFC v4 16/17] KVM: s390 allow virtio_ccw status writes to fail Message-ID: <20141023192233.29ca143e.cornelia.huck@de.ibm.com> In-Reply-To: <1414081380-14623-17-git-send-email-mst@redhat.com> References: <1414081380-14623-1-git-send-email-mst@redhat.com> <1414081380-14623-17-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Christian Borntraeger , linux390@de.ibm.com, Martin Schwidefsky , Heiko Carstens , linux-s390@vger.kernel.org List-ID: On Thu, 23 Oct 2014 19:25:01 +0300 "Michael S. Tsirkin" wrote: > 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 > --- > 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 a994078..26e737c 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; *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; If we fail the write, ccw->cda should be unchanged; but this doesn't hurt. > kfree(ccw); > } >