[PATCH 2/2] net: phy: Fix race conditions in the driver

[Kedareswara rao Appana]

This patch fixes the below race conditions in the driver.
---> Fix Opps after unload the driver as a module
---> Use spin locks where relevant.
---> Take reference on the external phy to prevent issues
when phy driver is unloaded.

Reported-by: Andrew Lunn <and...@lunn.ch>
Signed-off-by: Kedareswara rao Appana <appa...@xilinx.com>
---
 drivers/net/phy/xilinx_gmii2rgmii.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/xilinx_gmii2rgmii.c 
b/drivers/net/phy/xilinx_gmii2rgmii.c
index 7336fd0..cdd9d95 100644
--- a/drivers/net/phy/xilinx_gmii2rgmii.c
+++ b/drivers/net/phy/xilinx_gmii2rgmii.c
@@ -34,6 +34,7 @@ struct gmii2rgmii {
        struct phy_driver *phy_drv;
        struct phy_driver conv_phy_drv;
        int addr;
+       spinlock_t phy_lock;
 };
 
 static int xgmiitorgmii_read_status(struct phy_device *phydev)
@@ -55,7 +56,7 @@ static int xgmiitorgmii_read_status(struct phy_device *phydev)
                val |= BMCR_SPEED1000;
        else if (phydev->speed == SPEED_100)
                val |= BMCR_SPEED100;
-       else
+       else if (phydev->speed == SPEED_10)
                val |= BMCR_SPEED10;
 
        err = mdiobus_write(phydev->mdio.bus, priv->addr, XILINX_GMII2RGMII_REG,
@@ -71,6 +72,8 @@ int xgmiitorgmii_probe(struct mdio_device *mdiodev)
        struct device *dev = &mdiodev->dev;
        struct device_node *np = dev->of_node, *phy_node;
        struct gmii2rgmii *priv;
+       struct mii_bus *bus;
+       unsigned long flags;
 
        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
@@ -88,17 +91,43 @@ int xgmiitorgmii_probe(struct mdio_device *mdiodev)
                return -EPROBE_DEFER;
        }
 
+       spin_lock_init(&priv->phy_lock);
+
+       bus = priv->phy_dev->mdio.bus;
+       if (!try_module_get(bus->owner)) {
+               dev_err(dev, "failed to get the bus module\n");
+               return -EIO;
+       }
+
+       get_device(&priv->phy_dev->mdio.dev);
+
        priv->addr = mdiodev->addr;
        priv->phy_drv = priv->phy_dev->drv;
        memcpy(&priv->conv_phy_drv, priv->phy_dev->drv,
               sizeof(struct phy_driver));
        priv->conv_phy_drv.read_status = xgmiitorgmii_read_status;
        priv->phy_dev->priv = priv;
+       spin_lock_irqsave(&priv->phy_lock, flags);
        priv->phy_dev->drv = &priv->conv_phy_drv;
+       spin_unlock_irqrestore(&priv->phy_lock, flags);
+
+       dev_set_drvdata(dev, priv);
 
        return 0;
 }
 
+static void xgmiitorgmii_remove(struct mdio_device *mdiodev)
+{
+       struct gmii2rgmii *priv = dev_get_drvdata(&mdiodev->dev);
+       struct mii_bus *bus;
+
+       bus = priv->phy_dev->mdio.bus;
+
+       put_device(&priv->phy_dev->mdio.dev);
+       module_put(bus->owner);
+       phy_disconnect(priv->phy_dev);
+}
+
 static const struct of_device_id xgmiitorgmii_of_match[] = {
        { .compatible = "xlnx,gmii-to-rgmii-1.0" },
        {},
@@ -107,6 +136,7 @@ MODULE_DEVICE_TABLE(of, xgmiitorgmii_of_match);
 
 static struct mdio_driver xgmiitorgmii_driver = {
        .probe  = xgmiitorgmii_probe,
+       .remove = xgmiitorgmii_remove,
        .mdiodrv.driver = {
                .name = "xgmiitorgmii",
                .of_match_table = xgmiitorgmii_of_match,
-- 
2.1.2