IB/iser: Handle iser_device allocation error gracefully

"iser_device" allocation failure is "handled" with a BUG_ON() right
before dereferencing the NULL-pointer - fix this!
Signed-off-by: NArne Redlich <arne.redlich@xiranet.com>
Signed-off-by: NErez Zilber <erezz@voltaire.com>

drivers/infiniband/ulp/iser/iser_verbs.c

@@ -244,7 +244,7 @@ struct iser_device *iser_device_find_by_ib_device(struct rdma_cm_id *cma_id)
 	list_for_each_entry(device, &ig.device_list, ig_list)
 		/* find if there's a match using the node GUID */
 		if (device->ib_device->node_guid == cma_id->device->node_guid)
-			goto out;
+			goto inc_refcnt;
 
 	device = kzalloc(sizeof *device, GFP_KERNEL);
 	if (device == NULL)
@@ -260,9 +260,9 @@ struct iser_device *iser_device_find_by_ib_device(struct rdma_cm_id *cma_id)
 	}
 	list_add(&device->ig_list, &ig.device_list);
 
-out:
-	BUG_ON(device == NULL);
+inc_refcnt:
 	device->refcount++;
+out:
 	mutex_unlock(&ig.device_list_mutex);
 	return device;
 }
@@ -368,6 +368,12 @@ static void iser_addr_handler(struct rdma_cm_id *cma_id)
 	int    ret;
 
 	device = iser_device_find_by_ib_device(cma_id);
+	if (!device) {
+		iser_err("device lookup/creation failed\n");
+		iser_connect_error(cma_id);
+		return;
+	}
+
 	ib_conn = (struct iser_conn *)cma_id->context;
 	ib_conn->device = device;
 
@@ -376,7 +382,6 @@ static void iser_addr_handler(struct rdma_cm_id *cma_id)
 		iser_err("resolve route failed: %d\n", ret);
 		iser_connect_error(cma_id);
 	}
-	return;
 }
 
 static void iser_route_handler(struct rdma_cm_id *cma_id)