net: phy: Restore phy_resume() locking assumption

commit f5e64032a799 ("net: phy: fix resume handling") changes the
locking semantics for phy_resume() such that the caller now needs to
hold the phy mutex. Not all call sites were adopted to this new
semantic, resulting in warnings from the added
WARN_ON(!mutex_is_locked(&phydev->lock)).  Rather than change the
semantics, add a __phy_resume() and restore the old behavior of
phy_resume().

Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
Fixes: f5e64032a799 ("net: phy: fix resume handling")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy.c

@@ -819,7 +819,7 @@ void phy_start(struct phy_device *phydev)
 		break;
 	case PHY_HALTED:
 		/* if phy was suspended, bring the physical link up again */
-		phy_resume(phydev);
+		__phy_resume(phydev);
 
 		/* make sure interrupts are re-enabled for the PHY */
 		if (phy_interrupt_is_valid(phydev)) {

drivers/net/phy/phy_device.c

@@ -135,9 +135,7 @@ static int mdio_bus_phy_resume(struct device *dev)
 	if (!mdio_bus_phy_may_suspend(phydev))
 		goto no_resume;
 
-	mutex_lock(&phydev->lock);
 	ret = phy_resume(phydev);
-	mutex_unlock(&phydev->lock);
 	if (ret < 0)
 		return ret;
 
@@ -1041,9 +1039,7 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 	if (err)
 		goto error;
 
-	mutex_lock(&phydev->lock);
 	phy_resume(phydev);
-	mutex_unlock(&phydev->lock);
 	phy_led_triggers_register(phydev);
 
 	return err;
@@ -1172,7 +1168,7 @@ int phy_suspend(struct phy_device *phydev)
 }
 EXPORT_SYMBOL(phy_suspend);
 
-int phy_resume(struct phy_device *phydev)
+int __phy_resume(struct phy_device *phydev)
 {
 	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
 	int ret = 0;
@@ -1189,6 +1185,18 @@ int phy_resume(struct phy_device *phydev)
 
 	return ret;
 }
+EXPORT_SYMBOL(__phy_resume);
+
+int phy_resume(struct phy_device *phydev)
+{
+	int ret;
+
+	mutex_lock(&phydev->lock);
+	ret = __phy_resume(phydev);
+	mutex_unlock(&phydev->lock);
+
+	return ret;
+}
 EXPORT_SYMBOL(phy_resume);
 
 int phy_loopback(struct phy_device *phydev, bool enable)

include/linux/phy.h

@@ -924,6 +924,7 @@ void phy_device_remove(struct phy_device *phydev);
 int phy_init_hw(struct phy_device *phydev);
 int phy_suspend(struct phy_device *phydev);
 int phy_resume(struct phy_device *phydev);
+int __phy_resume(struct phy_device *phydev);
 int phy_loopback(struct phy_device *phydev, bool enable);
 struct phy_device *phy_attach(struct net_device *dev, const char *bus_id,
 			      phy_interface_t interface);