[netdrvr e1000] 82547 interrupt assert/de-assert re-ordering

* 82547 needs interrupt disable/enable to keep interrupt assertion
  state synced between 82547 and APIC.  82547 will re-order
  assert and de-assert messages if hub link bus is busy (heavy
  traffic).  Disabling interrupt on device works around re-
  order issue.  Note: this is a re-patch.  We backed out the
  patch because of a report on a system with a 8086:1019 device
  would lock up with this patch.  Turns out that system was a
  pre-production sample.

drivers/net/e1000/e1000_main.c

@@ -2124,10 +2124,26 @@ e1000_intr(int irq, void *data, struct pt_regs *regs)
 		__netif_rx_schedule(netdev);
 	}
 #else
+        /* Writing IMC and IMS is needed for 82547.
+	   Due to Hub Link bus being occupied, an interrupt 
+	   de-assertion message is not able to be sent. 
+	   When an interrupt assertion message is generated later,
+	   two messages are re-ordered and sent out.
+	   That causes APIC to think 82547 is in de-assertion
+	   state, while 82547 is in assertion state, resulting 
+	   in dead lock. Writing IMC forces 82547 into 
+	   de-assertion state.
+        */
+	if(hw->mac_type == e1000_82547 || hw->mac_type == e1000_82547_rev_2)
+		e1000_irq_disable(adapter);
+
 	for(i = 0; i < E1000_MAX_INTR; i++)
 		if(!e1000_clean_rx_irq(adapter) &
 		   !e1000_clean_tx_irq(adapter))
 			break;
+
+	if(hw->mac_type == e1000_82547 || hw->mac_type == e1000_82547_rev_2)
+		e1000_irq_enable(adapter);
 #endif
 
 	return IRQ_HANDLED;