1 files changed, 48 insertions, 14 deletions

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index c0f211127274..f761288abe66 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -384,6 +384,24 @@ int phy_device_register(struct phy_device *phydev)
 EXPORT_SYMBOL(phy_device_register);
 
 /**
+ * phy_device_remove - Remove a previously registered phy device from the MDIO bus
+ * @phydev: phy_device structure to remove
+ *
+ * This doesn't free the phy_device itself, it merely reverses the effects
+ * of phy_device_register(). Use phy_device_free() to free the device
+ * after calling this function.
+ */
+void phy_device_remove(struct phy_device *phydev)
+{
+	struct mii_bus *bus = phydev->bus;
+	int addr = phydev->addr;
+
+	device_del(&phydev->dev);
+	bus->phy_map[addr] = NULL;
+}
+EXPORT_SYMBOL(phy_device_remove);
+
+/**
  * phy_find_first - finds the first PHY device on the bus
  * @bus: the target MII bus
  */
@@ -578,14 +596,22 @@ EXPORT_SYMBOL(phy_init_hw);
  *     generic driver is used.  The phy_device is given a ptr to
  *     the attaching device, and given a callback for link status
  *     change.  The phy_device is returned to the attaching driver.
+ *     This function takes a reference on the phy device.
  */
 int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 		      u32 flags, phy_interface_t interface)
 {
+	struct mii_bus *bus = phydev->bus;
 	struct device *d = &phydev->dev;
-	struct module *bus_module;
 	int err;
 
+	if (!try_module_get(bus->owner)) {
+		dev_err(&dev->dev, "failed to get the bus module\n");
+		return -EIO;
+	}
+
+	get_device(d);
+
 	/* Assume that if there is no driver, that it doesn't
 	 * exist, and we should use the genphy driver.
 	 */
@@ -600,20 +626,13 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 			err = device_bind_driver(d);
 
 		if (err)
-			return err;
+			goto error;
 	}
 
 	if (phydev->attached_dev) {
 		dev_err(&dev->dev, "PHY already attached\n");
-		return -EBUSY;
-	}
-
-	/* Increment the bus module reference count */
-	bus_module = phydev->bus->dev.driver ?
-		     phydev->bus->dev.driver->owner : NULL;
-	if (!try_module_get(bus_module)) {
-		dev_err(&dev->dev, "failed to get the bus module\n");
-		return -EIO;
+		err = -EBUSY;
+		goto error;
 	}
 
 	phydev->attached_dev = dev;
@@ -636,6 +655,11 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 		phy_resume(phydev);
 
 	return err;
+
+error:
+	put_device(d);
+	module_put(bus->owner);
+	return err;
 }
 EXPORT_SYMBOL(phy_attach_direct);
 
@@ -677,14 +701,15 @@ EXPORT_SYMBOL(phy_attach);
 /**
  * phy_detach - detach a PHY device from its network device
  * @phydev: target phy_device struct
+ *
+ * This detaches the phy device from its network device and the phy
+ * driver, and drops the reference count taken in phy_attach_direct().
  */
 void phy_detach(struct phy_device *phydev)
 {
+	struct mii_bus *bus;
 	int i;
 
-	if (phydev->bus->dev.driver)
-		module_put(phydev->bus->dev.driver->owner);
-
 	phydev->attached_dev->phydev = NULL;
 	phydev->attached_dev = NULL;
 	phy_suspend(phydev);
@@ -700,6 +725,15 @@ void phy_detach(struct phy_device *phydev)
 			break;
 		}
 	}
+
+	/*
+	 * The phydev might go away on the put_device() below, so avoid
+	 * a use-after-free bug by reading the underlying bus first.
+	 */
+	bus = phydev->bus;
+
+	put_device(&phydev->dev);
+	module_put(bus->owner);
 }
 EXPORT_SYMBOL(phy_detach);