[PATCH v2 net] net: phy: Restore phy_resume() locking assumption

[Andrew Lunn]

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 <hkallwe...@gmail.com>
Fixes: f5e64032a799 ("net: phy: fix resume handling")
Signed-off-by: Andrew Lunn <and...@lunn.ch>
---
v2: Fix type in phy_resume() calling itself
---
 drivers/net/phy/phy.c        |  2 +-
 drivers/net/phy/phy_device.c | 18 +++++++++++++-----
 include/linux/phy.h          |  1 +
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index e3e29c2b028b..a6f924fee584 100644
--- a/drivers/net/phy/phy.c
+++ b/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)) {
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index d39ae77707ef..478405e544cc 100644
--- a/drivers/net/phy/phy_device.c
+++ b/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)
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 5a0c3e53e7c2..d7069539f351 100644
--- a/include/linux/phy.h
+++ b/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);
-- 
2.16.2