KVM: s390: virtio_ccw: reset errors for new I/O.

ccw_io_helper neglected to reset vcdev->err after a new channel
program had been successfully started, resulting in stale errors
delivered after one I/O failed. Reset the error after a new
channel program has been successfully started with no old I/O
pending.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 42d507c4e06b..5948f2a7b080 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -133,8 +133,11 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev,
         do {
                 spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
                 ret = ccw_device_start(vcdev->cdev, ccw, intparm, 0, 0);
-                if (!ret)
+                if (!ret) {
+                        if (!vcdev->curr_io)
+                                vcdev->err = 0;
                         vcdev->curr_io |= flag;
+                }
                 spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
                 cpu_relax();
         } while (ret == -EBUSY);