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phy: add proper phy struct device refcounting

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Take a refcount on the phy struct device when the phy device is attached
to a network device, and drop it after it's detached.  This ensures that
a refcount is held on the phy device while the device is being used by
a network device, thereby preventing the phy_device from being
unexpectedly kfree()'d by phy_device_release().

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Russell King 2015-09-24 20:36:08 +01:00 committed by David S. Miller
parent 3e3aaf6494
commit 7322967bc1
1 changed files with 12 additions and 0 deletions
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12
drivers/net/phy/phy_device.c
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@ -578,6 +578,7 @@ EXPORT_SYMBOL(phy_init_hw);
* generic driver is used. The phy_device is given a ptr to * generic driver is used. The phy_device is given a ptr to
* the attaching device, and given a callback for link status * the attaching device, and given a callback for link status
* change. The phy_device is returned to the attaching driver. * 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, int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
u32 flags, phy_interface_t interface) u32 flags, phy_interface_t interface)
@ -591,6 +592,8 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
return -EIO; return -EIO;
} }
get_device(d);
/* Assume that if there is no driver, that it doesn't /* Assume that if there is no driver, that it doesn't
* exist, and we should use the genphy driver. * exist, and we should use the genphy driver.
*/ */
@ -636,6 +639,7 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
return err; return err;
error: error:
put_device(d);
module_put(bus->owner); module_put(bus->owner);
return err; return err;
} }
@ -679,6 +683,9 @@ EXPORT_SYMBOL(phy_attach);
/** /**
* phy_detach - detach a PHY device from its network device * phy_detach - detach a PHY device from its network device
* @phydev: target phy_device struct * @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) void phy_detach(struct phy_device *phydev)
{ {
@ -701,8 +708,13 @@ void phy_detach(struct phy_device *phydev)
} }
} }
/*
* 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; bus = phydev->bus;
put_device(&phydev->dev);
module_put(bus->owner); module_put(bus->owner);
} }
EXPORT_SYMBOL(phy_detach); EXPORT_SYMBOL(phy_detach);