linux-kernel - [PATCH 3.2 10/62] s390/dasd: prevent incorrect length error under z/VM after PAV changes

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Message-ID: <lsq.1459279102.281975057@decadent.org.uk>
Date:	Tue, 29 Mar 2016 20:18:22 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Stefan Haberland" <stefan.haberland@...ibm.com>,
	"Martin Schwidefsky" <schwidefsky@...ibm.com>
Subject: [PATCH 3.2 10/62] s390/dasd: prevent incorrect length error under
 z/VM after PAV changes

3.2.79-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Haberland <stefan.haberland@...ibm.com>

commit 020bf042e5b397479c1174081b935d0ff15d1a64 upstream.

The channel checks the specified length and the provided amount of
data for CCWs and provides an incorrect length error if the size does
not match. Under z/VM with simulation activated the length may get
changed. Having the suppress length indication bit set is stated as
good CCW coding practice and avoids errors under z/VM.

Signed-off-by: Stefan Haberland <stefan.haberland@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/s390/block/dasd_alias.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/s390/block/dasd_alias.c
+++ b/drivers/s390/block/dasd_alias.c
@@ -749,7 +749,7 @@ static int reset_summary_unit_check(stru
 	ASCEBC((char *) &cqr->magic, 4);
 	ccw = cqr->cpaddr;
 	ccw->cmd_code = DASD_ECKD_CCW_RSCK;
-	ccw->flags = 0 ;
+	ccw->flags = CCW_FLAG_SLI;
 	ccw->count = 16;
 	ccw->cda = (__u32)(addr_t) cqr->data;
 	((char *)cqr->data)[0] = reason;