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net:stmmac: Add check if mdiobus is registered in stmmac_mdio_unregister

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This patch adds a basic check in stmmac_mdio_unregister to see if mdio
bus registeration for this driver was actually sucessfull or not.

Use case here is, if BSP considers using mdio-gpio bus along with stmmac
driver by passing mdio_bus_data as NULL in platform data.
Call to stmmac_mdio_register with mdio_bus_data as NULL returns 0, which
is a considered sucessfull call form stmmac. Then again when we unload
the driver we just call stmmac_mdio_unregister, this is were the actual
problem is stmmac-mdio code dont really know at this instance of calling
that stmmac_mdio_register was actually successful.

So Adding a check in stmmac_mdio_unregister is always safe.

Without this patch stmmac driver calls stmmac_mdio_register from
stmmac_release which Segfaults as mii bus was never registered at the
first point.

Originally the this bug was found when unloading an stmmac driver
instance which uses mdio-gpio for smi access.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Srinivas Kandagatla 2012-08-30 05:49:58 +00:00 committed by David S. Miller
parent fcb118491b
commit a5cf5ce92e
1 changed files with 3 additions and 0 deletions
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3
drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
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@ -258,6 +258,9 @@ int stmmac_mdio_unregister(struct net_device *ndev)
{
struct stmmac_priv *priv = netdev_priv(ndev);
if (!priv->mii)
return 0;
mdiobus_unregister(priv->mii);
priv->mii->priv = NULL;
mdiobus_free(priv->mii);