From: Zefir Kurtisi <zefir.kurt...@neratec.com> Date: Fri, 6 Jan 2017 12:14:48 +0100
> While in RUNNING state, phy_state_machine() checks for link changes by > comparing phydev->link before and after calling phy_read_status(). > This works as long as it is guaranteed that phydev->link is never > changed outside the phy_state_machine(). > > If in some setups this happens, it causes the state machine to miss > a link loss and remain RUNNING despite phydev->link being 0. > > This has been observed running a dsa setup with a process continuously > polling the link states over ethtool each second (SNMPD RFC-1213 > agent). Disconnecting the link on a phy followed by a ETHTOOL_GSET > causes dsa_slave_get_settings() / dsa_slave_get_link_ksettings() to > call phy_read_status() and with that modify the link status - and > with that bricking the phy state machine. > > This patch adds a fail-safe check while in RUNNING, which causes to > move to CHANGELINK when the link is gone and we are still RUNNING. > > Signed-off-by: Zefir Kurtisi <zefir.kurt...@neratec.com> > --- > Changes to v1: > * fix kbuild test robot error: use phydev_err instead of dev_warn > (adapt to changed struct phy_device after 4.4.21) Florian and Andrew, please provide some feedback on this. Thank you.
