s390/qeth: handle failure on workqueue creation

Creating the global workqueue during driver init may fail, deal with it.
Also, destroy the created workqueue on any subsequent error.

Fixes: 0f54761d ("qeth: Support VEPA mode")
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_core_main.c

@@ -6540,10 +6540,14 @@ static int __init qeth_core_init(void)
 	mutex_init(&qeth_mod_mutex);
 
 	qeth_wq = create_singlethread_workqueue("qeth_wq");
+	if (!qeth_wq) {
+		rc = -ENOMEM;
+		goto out_err;
+	}
 
 	rc = qeth_register_dbf_views();
 	if (rc)
-		goto out_err;
+		goto dbf_err;
 	qeth_core_root_dev = root_device_register("qeth");
 	rc = PTR_ERR_OR_ZERO(qeth_core_root_dev);
 	if (rc)
@@ -6580,6 +6584,8 @@ static int __init qeth_core_init(void)
 	root_device_unregister(qeth_core_root_dev);
 register_err:
 	qeth_unregister_dbf_views();
+dbf_err:
+	destroy_workqueue(qeth_wq);
 out_err:
 	pr_err("Initializing the qeth device driver failed\n");
 	return rc;