GenWQE: Fix problem when reading HSI and Retc

This patch fixes a problem we found during debug on PPC64 when
reading HSI status and Retc.

Signed-off-by: Eberhard S. Amann <esa@linux.vnet.ibm.com>
Signed-off-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/misc/genwqe/card_ddcb.c b/drivers/misc/genwqe/card_ddcb.c
index f10575000180..51480e4f8054 100644
--- a/drivers/misc/genwqe/card_ddcb.c
+++ b/drivers/misc/genwqe/card_ddcb.c
@@ -390,8 +390,9 @@ static int genwqe_check_ddcb_queue(struct genwqe_dev *cd,
                     0x00000000)
                         goto go_home; /* not completed, continue waiting */
 
-                /* Note: DDCB could be purged */
+                wmb();  /*  Add sync to decouple prev. read operations */
 
+                /* Note: DDCB could be purged */
                 req = queue->ddcb_req[queue->ddcb_act];
                 if (req == NULL) {
                         /* this occurs if DDCB is purged, not an error */