net: phy: Avoid deadlock during phy_error()

[ Upstream commit eab127717a6af54401ba534790c793ec143cd1fc ]

phy_error() is called in the PHY state machine workqueue context, and
calls phy_trigger_machine() which does a cancel_delayed_work_sync() of
the workqueue we execute from, causing a deadlock situation.

Augment phy_trigger_machine() machine with a sync boolean indicating
whether we should use cancel_*_sync() or just cancel_*_work().

Fixes: 3c293f4e08b5 ("net: phy: Trigger state machine on state change and not polling.")
Reported-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index f424b86..201ffa5 100644 (file)
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -611,14 +611,18 @@ void phy_start_machine(struct phy_device *phydev)
  * phy_trigger_machine - trigger the state machine to run
  *
  * @phydev: the phy_device struct
+ * @sync: indicate whether we should wait for the workqueue cancelation
  *
  * Description: There has been a change in state which requires that the
  *   state machine runs.
  */
 
-static void phy_trigger_machine(struct phy_device *phydev)
+static void phy_trigger_machine(struct phy_device *phydev, bool sync)
 {
-       cancel_delayed_work_sync(&phydev->state_queue);
+       if (sync)
+               cancel_delayed_work_sync(&phydev->state_queue);
+       else
+               cancel_delayed_work(&phydev->state_queue);
        queue_delayed_work(system_power_efficient_wq, &phydev->state_queue, 0);
 }
 
@@ -655,7 +659,7 @@ static void phy_error(struct phy_device *phydev)
        phydev->state = PHY_HALTED;
        mutex_unlock(&phydev->lock);
 
-       phy_trigger_machine(phydev);
+       phy_trigger_machine(phydev, false);
 }
 
 /**
@@ -817,7 +821,7 @@ void phy_change(struct work_struct *work)
        }
 
        /* reschedule state queue work to run as soon as possible */
-       phy_trigger_machine(phydev);
+       phy_trigger_machine(phydev, true);
        return;
 
 ignore:
@@ -907,7 +911,7 @@ void phy_start(struct phy_device *phydev)
        if (do_resume)
                phy_resume(phydev);
 
-       phy_trigger_machine(phydev);
+       phy_trigger_machine(phydev, true);
 }
 EXPORT_SYMBOL(phy_start);