[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>

2 files changed, 25 insertions, 12 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 56df3c5ed385..302ca14a69e5 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -1003,12 +1003,20 @@ static void dasd_handle_killed_request(struct ccw_device *cdev,
                 return;
         }
 
-        device = (struct dasd_device *) cqr->startdev;
-        if (device == NULL ||
-            device != dasd_device_from_cdev_locked(cdev) ||
-            strncmp(device->discipline->ebcname, (char *) &cqr->magic, 4)) {
+        device = dasd_device_from_cdev_locked(cdev);
+        if (IS_ERR(device)) {
+                DBF_EVENT_DEVID(DBF_DEBUG, cdev, "%s",
+                                "unable to get device from cdev");
+                return;
+        }
+
+        if (!cqr->startdev ||
+            device != cqr->startdev ||
+            strncmp(cqr->startdev->discipline->ebcname,
+                    (char *) &cqr->magic, 4)) {
                 DBF_EVENT_DEVID(DBF_DEBUG, cdev, "%s",
                                 "invalid device in request");
+                dasd_put_device(device);
                 return;
         }
 
@@ -2291,11 +2299,6 @@ static void dasd_generic_auto_online(void *data, async_cookie_t cookie)
         if (ret)
                 pr_warning("%s: Setting the DASD online failed with rc=%d\n",
                            dev_name(&cdev->dev), ret);
-        else {
-                struct dasd_device *device = dasd_device_from_cdev(cdev);
-                wait_event(dasd_init_waitq, _wait_for_device(device));
-                dasd_put_device(device);
-        }
 }
 
 /*
@@ -2430,6 +2433,9 @@ int dasd_generic_set_online(struct ccw_device *cdev,
         } else
                 pr_debug("dasd_generic device %s found\n",
                                 dev_name(&cdev->dev));
+
+        wait_event(dasd_init_waitq, _wait_for_device(device));
+
         dasd_put_device(device);
         return rc;
 }
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;
 }