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necessary because the channel is rescinded.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>

drivers/hv/channel_mgmt.c

@@ -517,6 +517,8 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
 		/* Just return here, no channel found */
 		return;
 
+	channel->rescind = true;
+
 	/* work is initialized for vmbus_process_rescind_offer() from
 	 * vmbus_process_offer() where the channel got created */
 	queue_work(channel->controlwq, &channel->work);

drivers/net/hyperv/netvsc.c

@@ -764,6 +764,9 @@ int netvsc_send(struct hv_device *device,
 		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,

drivers/net/hyperv/rndis_filter.c

@@ -958,6 +958,9 @@ static int rndis_filter_close_device(struct rndis_device *dev)
 		return 0;
 
 	ret = rndis_filter_set_packet_filter(dev, 0);
+	if (ret == -ENODEV)
+		ret = 0;
+
 	if (ret == 0)
 		dev->state = RNDIS_DEV_INITIALIZED;
 

include/linux/hyperv.h

@@ -650,6 +650,8 @@ struct vmbus_channel {
 	u8 monitor_grp;
 	u8 monitor_bit;
 
+	bool rescind; /* got rescind msg */
+
 	u32 ringbuffer_gpadlhandle;
 
 	/* Allocated memory for ring buffer */