From: Stefan Haberland <sth@linux.vnet.ibm.com>
Date: Sat, 7 Oct 2017 22:37:49 +0000 (+0000)
Subject: s390/dasd: check for device error pointer within state change interrupts
X-Git-Tag: v4.4.97~4
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4b7a35866b0ca4205ec5bacd2a5531caf19a463f;p=thirdparty%2Fkernel%2Fstable.git

s390/dasd: check for device error pointer within state change interrupts


[ Upstream commit 2202134e48a3b50320aeb9e3dd1186833e9d7e66 ]

Check if the device pointer is valid. Just a sanity check since we already
are in the int handler of the device.

Signed-off-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 84c13dffa3a8f..e7a6f12226425 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1635,8 +1635,11 @@ void dasd_int_handler(struct ccw_device *cdev, unsigned long intparm,
 	/* check for for attention message */
 	if (scsw_dstat(&irb->scsw) & DEV_STAT_ATTENTION) {
 		device = dasd_device_from_cdev_locked(cdev);
-		device->discipline->check_attention(device, irb->esw.esw1.lpum);
-		dasd_put_device(device);
+		if (!IS_ERR(device)) {
+			device->discipline->check_attention(device,
+							    irb->esw.esw1.lpum);
+			dasd_put_device(device);
+		}
 	}
 
 	if (!cqr)