e1000/e1000e/igb/ixgb: don't txhang after link down

after the recent changes to wired drivers to use only
netif_carrier_off the driver can have outstanding tx work to
complete that will never complete once link is down.  Since the
intel hardware will hold this tx work forever, the driver
notices a tx timeout condition internally and might try
to instigate printk and reset of the part with a
netif_stop_queue, which doesn't work because link is down.

Don't bother arming to tx hang detection when link is down.
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/e1000/e1000_main.c

@@ -2646,6 +2646,8 @@ static void e1000_watchdog(unsigned long data)
 			 * (Do the reset outside of interrupt context). */
 			adapter->tx_timeout_count++;
 			schedule_work(&adapter->reset_task);
+			/* return immediately since reset is imminent */
+			return;
 		}
 	}
 

drivers/net/e1000e/netdev.c

@@ -3651,6 +3651,8 @@ static void e1000_watchdog_task(struct work_struct *work)
 			 */
 			adapter->tx_timeout_count++;
 			schedule_work(&adapter->reset_task);
+			/* return immediately since reset is imminent */
+			return;
 		}
 	}
 

drivers/net/igb/igb_main.c

@@ -2711,6 +2711,8 @@ static void igb_watchdog_task(struct work_struct *work)
 			 * (Do the reset outside of interrupt context). */
 			adapter->tx_timeout_count++;
 			schedule_work(&adapter->reset_task);
+			/* return immediately since reset is imminent */
+			return;
 		}
 	}
 

drivers/net/ixgb/ixgb_main.c

@@ -1140,6 +1140,8 @@ ixgb_watchdog(unsigned long data)
 			 * to get done, so reset controller to flush Tx.
 			 * (Do the reset outside of interrupt context). */
 			schedule_work(&adapter->tx_timeout_task);
+			/* return immediately since reset is imminent */
+			return;
 		}
 	}