[PATCH 3.18 24/27] s390/dasd: check for device error pointer within state change interrupts

Greg Kroah-Hartman
2017-11-06T11:28:50Z

From: Stefan Haberland <sth@linux.vnet.ibm.com>

[ 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>
---
drivers/s390/block/dasd.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1672,8 +1672,11 @@ void dasd_int_handler(struct ccw_device
/* 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)