[S390] cio: Device status validity.

Only accumulate device status field in irb if it is valid.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/s390/cio/device_status.c b/drivers/s390/cio/device_status.c
index 6b1caea622ea..25d99bd28089 100644
--- a/drivers/s390/cio/device_status.c
+++ b/drivers/s390/cio/device_status.c
@@ -263,7 +263,11 @@ ccw_device_accumulate_irb(struct ccw_device *cdev, struct irb *irb)
                 cdev_irb->scsw.cpa = irb->scsw.cpa;
         /* Accumulate device status, but not the device busy flag. */
         cdev_irb->scsw.dstat &= ~DEV_STAT_BUSY;
-        cdev_irb->scsw.dstat |= irb->scsw.dstat;
+        /* dstat is not always valid. */
+        if (irb->scsw.stctl &
+            (SCSW_STCTL_PRIM_STATUS | SCSW_STCTL_SEC_STATUS
+             | SCSW_STCTL_INTER_STATUS | SCSW_STCTL_ALERT_STATUS))
+                cdev_irb->scsw.dstat |= irb->scsw.dstat;
         /* Accumulate subchannel status. */
         cdev_irb->scsw.cstat |= irb->scsw.cstat;
         /* Copy residual count if it is valid. */