From: Stephen Hemminger <stephen@networkplumber.org>
Date: Wed, 7 Mar 2018 13:49:10 -0800
Patch-mainline: v4.16-rc7
Subject: hv_netvsc: avoid repeated updates of packet filter
Git-commit: 7eeb4a6ee4820c4e84895d252079a797f27fc80d
References: fate#323887

The netvsc driver can get repeated calls to netvsc_rx_mode during
network setup; each of these calls ends up scheduling the lower
layers to update tha packet filter. This update requires an
request/response to the host. So avoid doing this if we already
know that the correct packet filter value is set.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Olaf Hering <ohering@suse.de>
---
 drivers/net/hyperv/hyperv_net.h   | 1 +
 drivers/net/hyperv/rndis_filter.c | 8 ++++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -173,6 +173,7 @@ struct rndis_device {
 	struct list_head req_list;
 
 	struct work_struct mcast_work;
+	u32 filter;
 
 	bool link_state;        /* 0 - link up, 1 - link down */
 
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -825,13 +825,15 @@ static int rndis_filter_set_packet_filter(struct rndis_device *dev,
 	struct rndis_set_request *set;
 	int ret;
 
+	if (dev->filter == new_filter)
+		return 0;
+
 	request = get_rndis_request(dev, RNDIS_MSG_SET,
 			RNDIS_MESSAGE_SIZE(struct rndis_set_request) +
 			sizeof(u32));
 	if (!request)
 		return -ENOMEM;
 
-
 	/* Setup the rndis set */
 	set = &request->request_msg.msg.set_req;
 	set->oid = RNDIS_OID_GEN_CURRENT_PACKET_FILTER;
@@ -842,8 +844,10 @@ static int rndis_filter_set_packet_filter(struct rndis_device *dev,
 	       &new_filter, sizeof(u32));
 
 	ret = rndis_filter_send_request(dev, request);
-	if (ret == 0)
+	if (ret == 0) {
 		wait_for_completion(&request->wait_event);
+		dev->filter = new_filter;
+	}
 
 	put_rndis_request(dev, request);