From: Eberhard S. Amann <esa@linux.vnet.ibm.com>
Date: Wed, 10 Sep 2014 14:37:52 +0000 (+0200)
Subject: GenWQE: Fix problem when reading HSI and Retc
X-Git-Tag: v3.18-rc1~126^2~32
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=08e4906cc29d092ae2da0ff089efe1488e584d3c;p=thirdparty%2Fkernel%2Flinux.git

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>
---

diff --git a/drivers/misc/genwqe/card_ddcb.c b/drivers/misc/genwqe/card_ddcb.c
index f105750001800..51480e4f80543 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 */