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| author | Zefir Kurtisi <zefir.kurtisi@neratec.com> | 2017-01-06 12:14:48 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-01-09 15:37:44 -0500 |
| commit | 811a919135b980bac8009d042acdccf10dc1ef5e (patch) | |
| tree | ecd9432bc1b198362749ac3209770000006c6475 | |
| parent | c92f5bdc4b9ba509a93f9e386fbb1fa779d4b0d6 (diff) | |
| download | linux-811a919135b980bac8009d042acdccf10dc1ef5e.tar.bz2 | |
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>
| -rw-r--r-- | drivers/net/phy/phy.c | 9 |
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); |