firmware: arm_ffa: Ensure drivers provide a probe function

The bus probe callback calls the driver callback without further
checking. Better be safe than sorry and refuse registration of a driver
without a probe function to prevent a NULL pointer exception.

Link: https://lore.kernel.org/r/20210621201652.127611-1-u.kleine-koenig@pengutronix.de
Fixes: e781858488b9 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_ffa/bus.c b/drivers/firmware/arm_ffa/bus.c
index 83166e0..d2cc243 100644 (file)
--- a/drivers/firmware/arm_ffa/bus.c
+++ b/drivers/firmware/arm_ffa/bus.c
@@ -99,6 +99,9 @@ int ffa_driver_register(struct ffa_driver *driver, struct module *owner,
 {
        int ret;
 
+       if (!driver->probe)
+               return -EINVAL;
+
        driver->driver.bus = &ffa_bus_type;
        driver->driver.name = driver->name;
        driver->driver.owner = owner;