hv_netvsc: Fix the packet free when it is in skb headroom

In the two places changed, we now use netvsc_xmit_completion() which properly
frees hv_netvsc_packet in or not in skb headroom.
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/hyperv_net.h

@@ -188,6 +188,7 @@ int netvsc_send(struct hv_device *device,
 		struct hv_netvsc_packet *packet);
 void netvsc_linkstatus_callback(struct hv_device *device_obj,
 				struct rndis_message *resp);
+void netvsc_xmit_completion(void *context);
 int netvsc_recv_callback(struct hv_device *device_obj,
 			struct hv_netvsc_packet *packet,
 			struct ndis_tcp_ip_checksum_info *csum_info);

drivers/net/hyperv/netvsc.c

@@ -878,7 +878,9 @@ int netvsc_send(struct hv_device *device,
 		packet->send_buf_index = section_index;
 		packet->total_data_buflen += msd_len;
 
-		kfree(msdp->pkt);
+		if (msdp->pkt)
+			netvsc_xmit_completion(msdp->pkt);
+
 		if (packet->xmit_more) {
 			msdp->pkt = packet;
 			msdp->count++;
@@ -902,7 +904,7 @@ int netvsc_send(struct hv_device *device,
 		if (m_ret != 0) {
 			netvsc_free_send_slot(net_device,
 					      msd_send->send_buf_index);
-			kfree(msd_send);
+			netvsc_xmit_completion(msd_send);
 		}
 	}
 

drivers/net/hyperv/netvsc_drv.c

@@ -229,7 +229,7 @@ static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb,
 	return q_idx;
 }
 
-static void netvsc_xmit_completion(void *context)
+void netvsc_xmit_completion(void *context)
 {
 	struct hv_netvsc_packet *packet = (struct hv_netvsc_packet *)context;
 	struct sk_buff *skb = (struct sk_buff *)