net: mdiobus: avoid BUG_ON() in mdiobus accessors

Avoid using BUG_ON() in the mdiobus accessors, prefering instead to use
WARN_ON_ONCE() and returning an error.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/mdio_bus.c

@@ -841,7 +841,8 @@ int mdiobus_read_nested(struct mii_bus *bus, int addr, u32 regnum)
 {
 	int retval;
 
-	BUG_ON(in_interrupt());
+	if (WARN_ON_ONCE(in_interrupt()))
+		return -EINVAL;
 
 	mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
 	retval = __mdiobus_read(bus, addr, regnum);
@@ -865,7 +866,8 @@ int mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
 {
 	int retval;
 
-	BUG_ON(in_interrupt());
+	if (WARN_ON_ONCE(in_interrupt()))
+		return -EINVAL;
 
 	mutex_lock(&bus->mdio_lock);
 	retval = __mdiobus_read(bus, addr, regnum);
@@ -893,7 +895,8 @@ int mdiobus_write_nested(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 {
 	int err;
 
-	BUG_ON(in_interrupt());
+	if (WARN_ON_ONCE(in_interrupt()))
+		return -EINVAL;
 
 	mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
 	err = __mdiobus_write(bus, addr, regnum, val);
@@ -918,7 +921,8 @@ int mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 {
 	int err;
 
-	BUG_ON(in_interrupt());
+	if (WARN_ON_ONCE(in_interrupt()))
+		return -EINVAL;
 
 	mutex_lock(&bus->mdio_lock);
 	err = __mdiobus_write(bus, addr, regnum, val);