On Wed, Feb 10, 2021 at 02:51:34AM +0100, Andrew Lunn wrote: > This is a general comment, not a problem specific to this patch. > > There is some interesting race conditions here. The marvell driver > first checks the fibre page and gets the status of the fiber port. As > you can see from the hunk above, it clears out pause, duplex, speed, > sets port to PORT_FIBRE, and then reads the PHY registers to set these > values. If link is not detected on the fibre, it swaps page and does > it all again, but for the copper port. So once per second, > phydev->port is going to flip flop PORT_FIBER->PORT_TP, if copper has > link. > > Now, the read_status() call into the driver should be performed while > holding the phydev->lock. So to the PHY state machine, this flip/flop > does not matter, it is atomic with respect to the lock. But > phy_ethtool_ksettings_get() is not talking the lock. It could see > speed, duplex, and port while they have _UNKNOWN values, or port is > part way through a flip flop. I think we need to take the lock here. > phy_ethtool_ksettings_set() should also probably take the lock.
phy_ethtool_ksettings_get() needs to take the lock, otherwise it could read the phy_device members in the middle of an update. This is likely a long-standing phylib bug. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
