[S390] dasd: fix refcounting.

The function dasd_device_from_cdev returns a reference to the dasd
device and increases the refcount by one. If an exception occurs,
the refcount was not decreased in all cases
e.g. in dasd_discipline_show.
Prevent the offline processing from hang by correcting two functions
to decrease the refcount even if an error occured.

Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 4cac5b54f26a..d49766f3b940 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -874,12 +874,19 @@ dasd_discipline_show(struct device *dev, struct device_attribute *attr,
         ssize_t len;
 
         device = dasd_device_from_cdev(to_ccwdev(dev));
-        if (!IS_ERR(device) && device->discipline) {
+        if (IS_ERR(device))
+                goto out;
+        else if (!device->discipline) {
+                dasd_put_device(device);
+                goto out;
+        } else {
                 len = snprintf(buf, PAGE_SIZE, "%s\n",
                                device->discipline->name);
                 dasd_put_device(device);
-        } else
-                len = snprintf(buf, PAGE_SIZE, "none\n");
+                return len;
+        }
+out:
+        len = snprintf(buf, PAGE_SIZE, "none\n");
         return len;
 }