[PATCH 7/8] staging: unisys: stop device registration before visorbus registration

[Benjamin Romer]

In cases where visorbus is compiled directly into the kernel, if
visorbus registration fails for any reason, it is still possible for
other drivers to call visorbus_register_visor_driver(), which could
cause an oops. Prevent this by returning an error code when the bus
hasn't been registered.

Signed-off-by: Benjamin Romer <benjamin.romer at unisys.com>
---
 drivers/staging/unisys/visorbus/visorbus_main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/unisys/visorbus/visorbus_main.c b/drivers/staging/unisys/visorbus/visorbus_main.c
index 7905ea9..ad2b1ac 100644
--- a/drivers/staging/unisys/visorbus/visorbus_main.c
+++ b/drivers/staging/unisys/visorbus/visorbus_main.c
@@ -863,6 +863,9 @@ int visorbus_register_visor_driver(struct visor_driver *drv)
 {
 	int rc = 0;
 
+	if (!visorbus_type.p)
+		return -ENODEV; /*can't register on a nonexistent bus*/
+
 	drv->driver.name = drv->name;
 	drv->driver.bus = &visorbus_type;
 	drv->driver.probe = visordriver_probe_device;
-- 
2.1.4