scsi: zfcp: Fix a double put in zfcp_port_enqueue()

When device_register() fails, zfcp_port_release() will be called after
put_device(). As a result, zfcp_ccw_adapter_put() will be called twice: one
in zfcp_port_release() and one in the error path after device_register().
So the reference on the adapter object is doubly put, which may lead to a
premature free. Fix this by adjusting the error tag after
device_register().

Fixes: f3450c7 ("[SCSI] zfcp: Replace local reference counting with common kref")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Link: https://lore.kernel.org/r/20230923103723.10320-1-dinghao.liu@zju.edu.cn
Acked-by: Benjamin Block <bblock@linux.ibm.com>
Cc: stable@vger.kernel.org # v2.6.33+
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: dinghaoliu

drivers/s390/scsi/zfcp_aux.c

@@ -518,12 +518,12 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
 	if (port) {
 		put_device(&port->dev);
 		retval = -EEXIST;
-		goto err_out;
+		goto err_put;
 	}
 
 	port = kzalloc(sizeof(struct zfcp_port), GFP_KERNEL);
 	if (!port)
-		goto err_out;
+		goto err_put;
 
 	rwlock_init(&port->unit_list_lock);
 	INIT_LIST_HEAD(&port->unit_list);
@@ -546,7 +546,7 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
 
 	if (dev_set_name(&port->dev, "0x%016llx", (unsigned long long)wwpn)) {
 		kfree(port);
-		goto err_out;
+		goto err_put;
 	}
 	retval = -EINVAL;
 
@@ -563,7 +563,8 @@ struct zfcp_port *zfcp_port_enqueue(struct zfcp_adapter *adapter, u64 wwpn,
 
 	return port;
 
-err_out:
+err_put:
 	zfcp_ccw_adapter_put(adapter);
+err_out:
 	return ERR_PTR(retval);
 }