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authorZefir Kurtisi <zefir.kurtisi@neratec.com>2017-01-06 12:14:48 +0100
committerDavid S. Miller <davem@davemloft.net>2017-01-09 15:37:44 -0500
commit811a919135b980bac8009d042acdccf10dc1ef5e (patch)
treeecd9432bc1b198362749ac3209770000006c6475 /drivers/net/phy
parentc92f5bdc4b9ba509a93f9e386fbb1fa779d4b0d6 (diff)
phy state machine: failsafe leave invalid RUNNING state
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>
Diffstat (limited to 'drivers/net/phy')
-rw-r--r--drivers/net/phy/phy.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 25f93a98863b..48da6e93c3f7 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -1065,6 +1065,15 @@ void phy_state_machine(struct work_struct *work)
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;
+ phydev_err(phydev, "no link in PHY_RUNNING\n");
+ }
break;
case PHY_CHANGELINK:
err = phy_read_status(phydev);