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Subject[PATCH 4.9 10/93] net: phy: Avoid deadlock during phy_error()
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Fainelli <f.fainelli@gmail.com>


[ 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>
---
drivers/net/phy/phy.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)

--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -611,14 +611,18 @@ void phy_start_machine(struct phy_device
* 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->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);


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