Using a separated mdio bus driver with mvmdio, phy_detach on network device
removal will not stop the phy and finally lead to NULL pointer dereference
in mvmdio due to non-existent network device. Use phy_disconnect instead
to properly stop phy device from accessing network device prior removal of
the network device.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
---
Note: I observed this behavior when removing a modular mv643xx_eth driver
after attaching it to a phy handled by (also modular) mvmdio. The mvmdio
conversion has been done in

commit c3a07134e6aa5b93a37f72ffa3d11fadf72bf757
 ("mv643xx_eth: convert to use the Marvell Orion MDIO driver")

and should go back any -stable version with that commit (propably only 3.9)

@David: I am not sure if the above description is sufficient for a -stable
patch, if you need more, like actual kernel failure, I am sure I can reproduce
it.

Cc: David Miller <davem@davemloft.net>
Cc: Lennert Buytenhek <redacted>
Cc: Jason Cooper <redacted>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: netdev@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/net/ethernet/marvell/mv643xx_eth.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c
index d0afeea..ef3454c 100644
--- a/drivers/net/ethernet/marvell/mv643xx_eth.c
+++ b/drivers/net/ethernet/marvell/mv643xx_eth.c

@@ -2805,7 +2805,7 @@ static int mv643xx_eth_remove(struct platform_device *pdev)
 
 	unregister_netdev(mp->dev);
 	if (mp->phy != NULL)
-		phy_detach(mp->phy);
+		phy_disconnect(mp->phy);
 	cancel_work_sync(&mp->tx_timeout_task);
 
 	if (!IS_ERR(mp->clk))

-- 
1.7.10.4