e1000e: test for valid check_reset_block function pointer

commit 44abd5c1 introduced NULL pointer
dereferences when attempting to access the check_reset_block function
pointer on 8257x and 80003es2lan non-copper devices.

This fix should be applied back through 3.4.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/ethtool.c

@@ -258,7 +258,8 @@ static int e1000_set_settings(struct net_device *netdev,
 	 * When SoL/IDER sessions are active, autoneg/speed/duplex
 	 * cannot be changed
 	 */
-	if (hw->phy.ops.check_reset_block(hw)) {
+	if (hw->phy.ops.check_reset_block &&
+	    hw->phy.ops.check_reset_block(hw)) {
 		e_err("Cannot change link characteristics when SoL/IDER is active.\n");
 		return -EINVAL;
 	}
@@ -1615,7 +1616,8 @@ static int e1000_loopback_test(struct e1000_adapter *adapter, u64 *data)
 	 * PHY loopback cannot be performed if SoL/IDER
 	 * sessions are active
 	 */
-	if (hw->phy.ops.check_reset_block(hw)) {
+	if (hw->phy.ops.check_reset_block &&
+	    hw->phy.ops.check_reset_block(hw)) {
 		e_err("Cannot do PHY loopback test when SoL/IDER is active.\n");
 		*data = 0;
 		goto out;

drivers/net/ethernet/intel/e1000e/mac.c

@@ -709,7 +709,7 @@ s32 e1000e_setup_link_generic(struct e1000_hw *hw)
 	 * In the case of the phy reset being blocked, we already have a link.
 	 * We do not need to set it up again.
 	 */
-	if (hw->phy.ops.check_reset_block(hw))
+	if (hw->phy.ops.check_reset_block && hw->phy.ops.check_reset_block(hw))
 		return 0;
 
 	/*

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -6237,7 +6237,7 @@ static int __devinit e1000_probe(struct pci_dev *pdev,
 		adapter->hw.phy.ms_type = e1000_ms_hw_default;
 	}
 
-	if (hw->phy.ops.check_reset_block(hw))
+	if (hw->phy.ops.check_reset_block && hw->phy.ops.check_reset_block(hw))
 		e_info("PHY reset is blocked due to SOL/IDER session.\n");
 
 	/* Set initial default active device features */
@@ -6404,7 +6404,7 @@ static int __devinit e1000_probe(struct pci_dev *pdev,
 	if (!(adapter->flags & FLAG_HAS_AMT))
 		e1000e_release_hw_control(adapter);
 err_eeprom:
-	if (!hw->phy.ops.check_reset_block(hw))
+	if (hw->phy.ops.check_reset_block && !hw->phy.ops.check_reset_block(hw))
 		e1000_phy_hw_reset(&adapter->hw);
 err_hw_init:
 	kfree(adapter->tx_ring);

drivers/net/ethernet/intel/e1000e/phy.c

@@ -2155,9 +2155,11 @@ s32 e1000e_phy_hw_reset_generic(struct e1000_hw *hw)
 	s32 ret_val;
 	u32 ctrl;
 
-	ret_val = phy->ops.check_reset_block(hw);
-	if (ret_val)
-		return 0;
+	if (phy->ops.check_reset_block) {
+		ret_val = phy->ops.check_reset_block(hw);
+		if (ret_val)
+			return 0;
+	}
 
 	ret_val = phy->ops.acquire(hw);
 	if (ret_val)