Commit f86854a2 authored Oct 16, 2019 by Heiner Kallweit Committed by David S. Miller Oct 18, 2019

net: phy: avoid NPE if read_page/write_page callbacks are not available

Currently there's a bug in the module subsystem [0] preventing load of
the PHY driver module on certain systems (as one symptom).
This results in a NPE on such systems for the following reason:
Instead of the correct PHY driver the genphy driver is loaded that
doesn't implement the read_page/write_page callbacks. Every call to
phy_read_paged() et al will result in a NPE therefore.

In parallel to fixing the root cause we should make sure that this one
and maybe similar issues in other subsystems don't result in a NPE
in phylib. So let's check for the callbacks before using them and warn
once if they are not available.

[0] https://marc.info/?t=157072642100001&r=1&w=2



Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 2fb079a2

drivers/net/phy/phy-core.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -697,11 +697,17 @@ EXPORT_SYMBOL_GPL(phy_modify_mmd);

		static int __phy_read_page(struct phy_device *phydev)
		{
		if (WARN_ONCE(!phydev->drv->read_page, "read_page callback not available, PHY driver not loaded?\n"))
		return -EOPNOTSUPP;

		return phydev->drv->read_page(phydev);
		}

		static int __phy_write_page(struct phy_device *phydev, int page)
		{
		if (WARN_ONCE(!phydev->drv->write_page, "write_page callback not available, PHY driver not loaded?\n"))
		return -EOPNOTSUPP;

		return phydev->drv->write_page(phydev, page);
		}

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