[PATCH net v2] net: phy: phy driver features are mandatory

[Camelia Groza <camelia.groza@nxp.com>]

Since phy driver features became a link_mode bitmap, phy drivers that
don't have a list of features configured will cause the kernel to crash
when probed.

Prevent the phy driver from registering if the features field is missing.

Fixes: 719655a14971 ("net: phy: Replace phy driver features u32 with link_mode bitmap")
Reported-by: Scott Wood <oss@buserror.net>
Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
---
v2: Print the name of the driver that has missing features.

This patch should be merged to 4.20 stable.
---
 drivers/net/phy/phy_device.c | 5 +++++
 include/linux/phy.h          | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index bf3ce48..46c8672 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -2255,6 +2255,11 @@ int phy_driver_register(struct phy_driver *new_driver, struct module *owner)
 {
 	int retval;
 
+	if (WARN_ON(!new_driver->features)) {
+		pr_err("%s: Driver features are missing\n", new_driver->name);
+		return -EINVAL;
+	}
+
 	new_driver->mdiodrv.flags |= MDIO_DEVICE_IS_PHY;
 	new_driver->mdiodrv.driver.name = new_driver->name;
 	new_driver->mdiodrv.driver.bus = &mdio_bus_type;
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 5511465..ef20aee 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -469,8 +469,8 @@ struct phy_device {
  *   only works for PHYs with IDs which match this field
  * name: The friendly name of this PHY type
  * phy_id_mask: Defines the important bits of the phy_id
- * features: A list of features (speed, duplex, etc) supported
- *   by this PHY
+ * features: A mandatory list of features (speed, duplex, etc)
+ *   supported by this PHY
  * flags: A bitfield defining certain other features this PHY
  *   supports (like interrupts)
  *
-- 
1.9.1