hv_netvsc: enable multicast if necessary

My recent change to netvsc drive in how receive flags are handled broke multicast. The Hyper-v/Azure virtual interface there is not a multicast filter list, filtering is only all or none. The driver must enable all multicast if any multicast address is present.

---
 drivers/net/hyperv/rndis_filter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 00ec80c23fe5..8799b0590adc 100644
@@ -864,7 +864,7 @@ static void rndis_set_multicast(struct work_struct *w)
 	if (flags & IFF_PROMISC) {
 		filter = NDIS_PACKET_TYPE_PROMISCUOUS;
 	} else {
-		if (flags & IFF_ALLMULTI)
+		if (!netdev_mc_empty(rdev->ndev) || (flags & IFF_ALLMULTI))
 			filter |= NDIS_PACKET_TYPE_ALL_MULTICAST;
 		if (flags & IFF_BROADCAST)
 			filter |= NDIS_PACKET_TYPE_BROADCAST;

2.16.2

From: Stephen Hemminger <[email protected]>
Date: Tue, 27 Mar 2018 11:28:48 -0700

Applied, thanks Stephen.