netvsc: make sure napi enabled before vmbus_open

This fixes a race where vmbus callback for new packet arriving
could occur before NAPI is initialized.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/netvsc.c

@@ -1322,23 +1322,25 @@ int netvsc_device_add(struct hv_device *device,
 		nvchan->channel = device->channel;
 	}
 
+	/* Enable NAPI handler before init callbacks */
+	netif_napi_add(ndev, &net_device->chan_table[0].napi,
+		       netvsc_poll, NAPI_POLL_WEIGHT);
+
 	/* Open the channel */
 	ret = vmbus_open(device->channel, ring_size * PAGE_SIZE,
 			 ring_size * PAGE_SIZE, NULL, 0,
 			 netvsc_channel_cb,
 			 net_device->chan_table);
 
 	if (ret != 0) {
+		netif_napi_del(&net_device->chan_table[0].napi);
 		netdev_err(ndev, "unable to open channel: %d\n", ret);
 		goto cleanup;
 	}
 
 	/* Channel is opened */
 	netdev_dbg(ndev, "hv_netvsc channel opened successfully\n");
 
-	/* Enable NAPI handler for init callbacks */
-	netif_napi_add(ndev, &net_device->chan_table[0].napi,
-		       netvsc_poll, NAPI_POLL_WEIGHT);
 	napi_enable(&net_device->chan_table[0].napi);
 
 	/* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is

drivers/net/hyperv/rndis_filter.c

@@ -1018,7 +1018,7 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
 	if (ret == 0)
 		napi_enable(&nvchan->napi);
 	else
-		netdev_err(ndev, "sub channel open failed (%d)\n", ret);
+		netif_napi_del(&nvchan->napi);
 
 	if (refcount_dec_and_test(&nvscdev->sc_offered))
 		complete(&nvscdev->channel_init_wait);