| From foo@baz Wed Aug 9 11:19:16 PDT 2017 |
| From: Zefir Kurtisi <zefir.kurtisi@neratec.com> |
| Date: Fri, 6 Jan 2017 12:14:48 +0100 |
| Subject: phy state machine: failsafe leave invalid RUNNING state |
| |
| From: Zefir Kurtisi <zefir.kurtisi@neratec.com> |
| |
| |
| [ Upstream commit 811a919135b980bac8009d042acdccf10dc1ef5e ] |
| |
| 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.kurtisi@neratec.com> |
| Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Sasha Levin <alexander.levin@verizon.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/net/phy/phy.c | 9 +++++++++ |
| 1 file changed, 9 insertions(+) |
| |
| --- a/drivers/net/phy/phy.c |
| +++ b/drivers/net/phy/phy.c |
| @@ -921,6 +921,15 @@ void phy_state_machine(struct work_struc |
| if (old_link != phydev->link) |
| phydev->state = PHY_CHANGELINK; |
| } |
| + /* |
| + * Failsafe: check that nobody set phydev->link=0 between two |
| + * poll cycles, otherwise we won't leave RUNNING state as long |
| + * as link remains down. |
| + */ |
| + if (!phydev->link && phydev->state == PHY_RUNNING) { |
| + phydev->state = PHY_CHANGELINK; |
| + dev_err(&phydev->dev, "no link in PHY_RUNNING\n"); |
| + } |
| break; |
| case PHY_CHANGELINK: |
| err = phy_read_status(phydev); |