hyperv: Add support for vNIC hot removal

This patch adds proper handling of the vNIC hot removal event, which includes
a rescind-channel-offer message from the host side that triggers vNIC close and
removal. In this case, the notices to the host during close and removal is not
necessary because the channel is rescinded. This patch blocks these unnecessary
messages, and lets vNIC removal process complete normally.

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>
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 6fc834e..dd867e6 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -764,6 +764,9 @@
 		out_channel = device->channel;
 	packet->channel = out_channel;
 
+	if (out_channel->rescind)
+		return -ENODEV;
+
 	if (packet->page_buf_cnt) {
 		ret = vmbus_sendpacket_pagebuffer(out_channel,
 						  packet->page_buf,
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 7b2c5d1..ec0c40a 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -958,6 +958,9 @@
 		return 0;
 
 	ret = rndis_filter_set_packet_filter(dev, 0);
+	if (ret == -ENODEV)
+		ret = 0;
+
 	if (ret == 0)
 		dev->state = RNDIS_DEV_INITIALIZED;