Unofficial e1000e patch for Kernel 5.4.13.

_Unofficial_ e1000e 'disconnect' patch for Kernel 5.4.13, created/modified from earlier patch on linux/netdev, and tested with Kernel 5.4.13.
Usual disclaimers apply, use at your own risk.  RG.  January 21, 2020.

-------------------------- CUT HERE -------------------------------------------------------
diff --git a/drivers/net/ethernet/intel/e1000e/e1000.h b/drivers/net/ethernet/intel/e1000e/e1000.h
--- a/drivers/net/ethernet/intel/e1000e/e1000.h
+++ b/drivers/net/ethernet/intel/e1000e/e1000.h
@@ -185,13 +185,12 @@

 /* board specific private data structure */
 struct e1000_adapter {
+	struct timer_list watchdog_timer;
 	struct timer_list phy_info_timer;
 	struct timer_list blink_timer;

 	struct work_struct reset_task;
-	struct delayed_work watchdog_task;
-
-	struct workqueue_struct *e1000_workqueue;
+	struct work_struct watchdog_task;

 	const struct e1000_info *ei;

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -1780,8 +1780,7 @@
 		}
 		/* guard against interrupt when we're going down */
 		if (!test_bit(__E1000_DOWN, &adapter->state))
-			mod_delayed_work(adapter->e1000_workqueue,
-					 &adapter->watchdog_task, HZ);
+			mod_timer(&adapter->watchdog_timer, jiffies + 1);
 	}

 	/* Reset on uncorrectable ECC error */
@@ -1861,8 +1860,7 @@
 		}
 		/* guard against interrupt when we're going down */
 		if (!test_bit(__E1000_DOWN, &adapter->state))
-			mod_delayed_work(adapter->e1000_workqueue,
-					 &adapter->watchdog_task, HZ);
+			mod_timer(&adapter->watchdog_timer, jiffies + 1);
 	}

 	/* Reset on uncorrectable ECC error */
@@ -1907,8 +1905,7 @@
 		hw->mac.get_link_status = true;
 		/* guard against interrupt when we're going down */
 		if (!test_bit(__E1000_DOWN, &adapter->state))
-			mod_delayed_work(adapter->e1000_workqueue,
-					 &adapter->watchdog_task, HZ);
+			mod_timer(&adapter->watchdog_timer, jiffies + 1);
 	}

 	if (!test_bit(__E1000_DOWN, &adapter->state))
@@ -4281,6 +4278,7 @@

 	napi_synchronize(&adapter->napi);

+	del_timer_sync(&adapter->watchdog_timer);
 	del_timer_sync(&adapter->phy_info_timer);

 	spin_lock(&adapter->stats64_lock);
@@ -5152,11 +5150,25 @@
 	}
 }

+/**
+ * e1000_watchdog - Timer Call-back
+ * @data: pointer to adapter cast into an unsigned long
+ **/
+static void e1000_watchdog(struct timer_list *t)
+{
+	struct e1000_adapter *adapter = from_timer(adapter, t, watchdog_timer);
+
+	/* Do the rest outside of interrupt context */
+	schedule_work(&adapter->watchdog_task);
+
+	/* TODO: make this use queue_delayed_work() */
+}
+
 static void e1000_watchdog_task(struct work_struct *work)
 {
 	struct e1000_adapter *adapter = container_of(work,
 						     struct e1000_adapter,
-						     watchdog_task.work);
+						     watchdog_task);
 	struct net_device *netdev = adapter->netdev;
 	struct e1000_mac_info *mac = &adapter->hw.mac;
 	struct e1000_phy_info *phy = &adapter->hw.phy;
@@ -5404,9 +5416,8 @@

 	/* Reset the timer */
 	if (!test_bit(__E1000_DOWN, &adapter->state))
-		queue_delayed_work(adapter->e1000_workqueue,
-				   &adapter->watchdog_task,
-				   round_jiffies(2 * HZ));
+		mod_timer(&adapter->watchdog_timer,
+			  round_jiffies(jiffies + 2 * HZ));
 }

 #define E1000_TX_FLAGS_CSUM		0x00000001
@@ -7259,21 +7270,11 @@
 		goto err_eeprom;
 	}

-	adapter->e1000_workqueue = alloc_workqueue("%s", WQ_MEM_RECLAIM, 0,
-						   e1000e_driver_name);
-
-	if (!adapter->e1000_workqueue) {
-		err = -ENOMEM;
-		goto err_workqueue;
-	}
-
-	INIT_DELAYED_WORK(&adapter->watchdog_task, e1000_watchdog_task);
-	queue_delayed_work(adapter->e1000_workqueue, &adapter->watchdog_task,
-			   0);
-
+	timer_setup(&adapter->watchdog_timer, e1000_watchdog, 0);
 	timer_setup(&adapter->phy_info_timer, e1000_update_phy_info, 0);

 	INIT_WORK(&adapter->reset_task, e1000_reset_task);
+	INIT_WORK(&adapter->watchdog_task, e1000_watchdog_task);
 	INIT_WORK(&adapter->downshift_task, e1000e_downshift_workaround);
 	INIT_WORK(&adapter->update_phy_task, e1000e_update_phy_task);
 	INIT_WORK(&adapter->print_hang_task, e1000_print_hw_hang);
@@ -7367,9 +7368,6 @@
 	return 0;

 err_register:
-	flush_workqueue(adapter->e1000_workqueue);
-	destroy_workqueue(adapter->e1000_workqueue);
-err_workqueue:
 	if (!(adapter->flags & FLAG_HAS_AMT))
 		e1000e_release_hw_control(adapter);
 err_eeprom:
@@ -7416,17 +7414,15 @@
 	 */
 	if (!down)
 		set_bit(__E1000_DOWN, &adapter->state);
+    del_timer_sync(&adapter->watchdog_timer);
 	del_timer_sync(&adapter->phy_info_timer);

 	cancel_work_sync(&adapter->reset_task);
+    cancel_work_sync(&adapter->watchdog_task);
 	cancel_work_sync(&adapter->downshift_task);
 	cancel_work_sync(&adapter->update_phy_task);
 	cancel_work_sync(&adapter->print_hang_task);

-	cancel_delayed_work(&adapter->watchdog_task);
-	flush_workqueue(adapter->e1000_workqueue);
-	destroy_workqueue(adapter->e1000_workqueue);
-
 	if (adapter->flags & FLAG_HAS_HW_TIMESTAMP) {
 		cancel_work_sync(&adapter->tx_hwtstamp_work);
 		if (adapter->tx_hwtstamp_skb) {