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

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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>
This commit is contained in:
Heiner Kallweit 2019-10-16 21:53:31 +02:00 committed by David S. Miller
parent 2fb079a28a
commit f86854a2e7
1 changed files with 6 additions and 0 deletions
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6
drivers/net/phy/phy-core.c
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@ -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);
}