igb: Report link status in ethtool when interface is down

With this change ethtool will correctly report link status when
the interface is down. Currently ethtool reports the link as not
detected when the interface is down.
Signed-off-by: Nicholas Nunley <nicholasx.d.nunley@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/igb/igb.h

@@ -356,6 +356,7 @@ extern void igb_unmap_and_free_tx_resource(struct igb_ring *,
 					   struct igb_buffer *);
 extern void igb_alloc_rx_buffers_adv(struct igb_ring *, int);
 extern void igb_update_stats(struct igb_adapter *);
+extern bool igb_has_link(struct igb_adapter *adapter);
 extern void igb_set_ethtool_ops(struct net_device *);
 
 static inline s32 igb_reset_phy(struct e1000_hw *hw)

drivers/net/igb/igb_ethtool.c

@@ -234,6 +234,24 @@ static int igb_set_settings(struct net_device *netdev, struct ethtool_cmd *ecmd)
 	return 0;
 }
 
+static u32 igb_get_link(struct net_device *netdev)
+{
+	struct igb_adapter *adapter = netdev_priv(netdev);
+	struct e1000_mac_info *mac = &adapter->hw.mac;
+
+	/*
+	 * If the link is not reported up to netdev, interrupts are disabled,
+	 * and so the physical link state may have changed since we last
+	 * looked. Set get_link_status to make sure that the true link
+	 * state is interrogated, rather than pulling a cached and possibly
+	 * stale link state from the driver.
+	 */
+	if (!netif_carrier_ok(netdev))
+		mac->get_link_status = 1;
+
+	return igb_has_link(adapter);
+}
+
 static void igb_get_pauseparam(struct net_device *netdev,
 			       struct ethtool_pauseparam *pause)
 {
@@ -2077,7 +2095,7 @@ static const struct ethtool_ops igb_ethtool_ops = {
 	.get_msglevel           = igb_get_msglevel,
 	.set_msglevel           = igb_set_msglevel,
 	.nway_reset             = igb_nway_reset,
-	.get_link               = ethtool_op_get_link,
+	.get_link               = igb_get_link,
 	.get_eeprom_len         = igb_get_eeprom_len,
 	.get_eeprom             = igb_get_eeprom,
 	.set_eeprom             = igb_set_eeprom,

drivers/net/igb/igb_main.c

@@ -3020,7 +3020,7 @@ static void igb_update_phy_info(unsigned long data)
  * igb_has_link - check shared code for link and determine up/down
  * @adapter: pointer to driver private info
  **/
-static bool igb_has_link(struct igb_adapter *adapter)
+bool igb_has_link(struct igb_adapter *adapter)
 {
 	struct e1000_hw *hw = &adapter->hw;
 	bool link_active = false;