hv_netvsc: track memory allocation failures in ethtool stats

When skb can not be allocated, update ethtool statisitics
rather than rx_dropped which is intended for netif_receive.
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/hyperv_net.h

@@ -705,6 +705,7 @@ struct netvsc_ethtool_stats {
 	unsigned long tx_busy;
 	unsigned long tx_send_full;
 	unsigned long rx_comp_busy;
+	unsigned long rx_no_memory;
 	unsigned long stop_queue;
 	unsigned long wake_queue;
 };

drivers/net/hyperv/netvsc_drv.c

@@ -773,8 +773,8 @@ int netvsc_recv_callback(struct net_device *net,
 	skb = netvsc_alloc_recv_skb(net, &nvchan->napi,
 				    csum_info, vlan, data, len);
 	if (unlikely(!skb)) {
+		++net_device_ctx->eth_stats.rx_no_memory;
 drop:
-		++net->stats.rx_dropped;
 		rcu_read_unlock();
 		return NVSP_STAT_FAIL;
 	}
@@ -1131,6 +1131,7 @@ static const struct {
 	{ "tx_busy",	  offsetof(struct netvsc_ethtool_stats, tx_busy) },
 	{ "tx_send_full", offsetof(struct netvsc_ethtool_stats, tx_send_full) },
 	{ "rx_comp_busy", offsetof(struct netvsc_ethtool_stats, rx_comp_busy) },
+	{ "rx_no_memory", offsetof(struct netvsc_ethtool_stats, rx_no_memory) },
 	{ "stop_queue", offsetof(struct netvsc_ethtool_stats, stop_queue) },
 	{ "wake_queue", offsetof(struct netvsc_ethtool_stats, wake_queue) },
 }, vf_stats[] = {