cxgb4: Disable interrupts and napi before unregistering netdev

Disable interrupts and quiesce rx before unregistering net device to avoid crash
while unloading driver when traffic is flowing through.

Based on original work by Shameem Khalid <shameem@chelsio.com>

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -934,6 +934,21 @@ static void quiesce_rx(struct adapter *adap)
 	}
 }
 
+/* Disable interrupt and napi handler */
+static void disable_interrupts(struct adapter *adap)
+{
+	if (adap->flags & FULL_INIT_DONE) {
+		t4_intr_disable(adap);
+		if (adap->flags & USING_MSIX) {
+			free_msix_queue_irqs(adap);
+			free_irq(adap->msix_info[0].vec, adap);
+		} else {
+			free_irq(adap->pdev->irq, adap);
+		}
+		quiesce_rx(adap);
+	}
+}
+
 /*
  * Enable NAPI scheduling and interrupt generation for all Rx queues.
  */
@@ -4257,19 +4272,12 @@ static int cxgb_up(struct adapter *adap)
 
 static void cxgb_down(struct adapter *adapter)
 {
-	t4_intr_disable(adapter);
 	cancel_work_sync(&adapter->tid_release_task);
 	cancel_work_sync(&adapter->db_full_task);
 	cancel_work_sync(&adapter->db_drop_task);
 	adapter->tid_release_task_busy = false;
 	adapter->tid_release_head = NULL;
 
-	if (adapter->flags & USING_MSIX) {
-		free_msix_queue_irqs(adapter);
-		free_irq(adapter->msix_info[0].vec, adapter);
-	} else
-		free_irq(adapter->pdev->irq, adapter);
-	quiesce_rx(adapter);
 	t4_sge_stop(adapter);
 	t4_free_sge_resources(adapter);
 	adapter->flags &= ~FULL_INIT_DONE;
@@ -5591,6 +5599,7 @@ static pci_ers_result_t eeh_err_detected(struct pci_dev *pdev,
 		netif_carrier_off(dev);
 	}
 	spin_unlock(&adap->stats_lock);
+	disable_interrupts(adap);
 	if (adap->flags & FULL_INIT_DONE)
 		cxgb_down(adap);
 	rtnl_unlock();
@@ -6304,6 +6313,8 @@ static void remove_one(struct pci_dev *pdev)
 		if (is_offload(adapter))
 			detach_ulds(adapter);
 
+		disable_interrupts(adapter);
+
 		for_each_port(adapter, i)
 			if (adapter->port[i]->reg_state == NETREG_REGISTERED)
 				unregister_netdev(adapter->port[i]);