[net-next v5 1/2] net: phy: phy_device: Prevent nullptr exceptions on ISR

[Andre Werner <andre.werner@systec-electronic.com>]

If phydev->irq is set unconditionally, check
for valid interrupt handler or fall back to polling mode to prevent
nullptr exceptions in interrupt service routine.

Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
v5:
- No functional changes. Add Reviewed-by tag.

v4:
- Delete phydev_warn and comment as suggested.

v3:
- No changes to v2. Just to complete the series.

v2:
- Add changes suggested in discussion about adin1100.c driver to
  phy_attach_direct.
---
 drivers/net/phy/phy_device.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index dd778c7fde1d..52828d1c64f7 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1413,6 +1413,11 @@ int phy_sfp_probe(struct phy_device *phydev,
 }
 EXPORT_SYMBOL(phy_sfp_probe);
 
+static bool phy_drv_supports_irq(struct phy_driver *phydrv)
+{
+	return phydrv->config_intr && phydrv->handle_interrupt;
+}
+
 /**
  * phy_attach_direct - attach a network device to a given PHY device pointer
  * @dev: network device to attach
@@ -1527,6 +1532,9 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 	if (phydev->dev_flags & PHY_F_NO_IRQ)
 		phydev->irq = PHY_POLL;
 
+	if (!phy_drv_supports_irq(phydev->drv) && phy_interrupt_is_valid(phydev))
+		phydev->irq = PHY_POLL;
+
 	/* Port is set to PORT_TP by default and the actual PHY driver will set
 	 * it to different value depending on the PHY configuration. If we have
 	 * the generic PHY driver we can't figure it out, thus set the old
@@ -2992,11 +3000,6 @@ s32 phy_get_internal_delay(struct phy_device *phydev, struct device *dev,
 }
 EXPORT_SYMBOL(phy_get_internal_delay);
 
-static bool phy_drv_supports_irq(struct phy_driver *phydrv)
-{
-	return phydrv->config_intr && phydrv->handle_interrupt;
-}
-
 static int phy_led_set_brightness(struct led_classdev *led_cdev,
 				  enum led_brightness value)
 {
-- 
2.43.0