From: Dexuan Cui <decui@microsoft.com>
Date: Tue, 8 Sep 2020 21:08:19 -0700
Patch-mainline: v5.9-rc7
Subject: hv_netvsc: Cache the current data path to avoid duplicate call and message
Git-commit: da26658c3d7005aa67a706dceff7b2807b59e123
References: bsc#1204017

The previous change "hv_netvsc: Switch the data path at the right time
during hibernation" adds the call of netvsc_vf_changed() upon
NETDEV_CHANGE, so it's necessary to avoid the duplicate call and message
when the VF is brought UP or DOWN.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Olaf Hering <ohering@suse.de>
---
 drivers/net/hyperv/hyperv_net.h |  3 ++
 drivers/net/hyperv/netvsc_drv.c | 21 ++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

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
@@ -974,6 +974,9 @@ struct net_device_context {
 	u32 vf_alloc;
 	/* Serial number of the VF to team with */
 	u32 vf_serial;
+	/* Is the current data path through the VF NIC? */
+	bool  data_path_is_vf;
+
 };
 
 /* Per channel data */
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2366,7 +2366,16 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
 	return NOTIFY_OK;
 }
 
-/* VF up/down change detected, schedule to change data path */
+/* Change the data path when VF UP/DOWN/CHANGE are detected.
+ *
+ * Typically a UP or DOWN event is followed by a CHANGE event, so
+ * net_device_ctx->data_path_is_vf is used to cache the current data path
+ * to avoid the duplicate call of netvsc_switch_datapath() and the duplicate
+ * message.
+ *
+ * During hibernation, if a VF NIC driver (e.g. mlx5) preserves the network
+ * interface, there is only the CHANGE event and no UP or DOWN event.
+ */
 static int netvsc_vf_changed(struct net_device *vf_netdev)
 {
 	struct net_device_context *net_device_ctx;
@@ -2383,6 +2392,10 @@ static int netvsc_vf_changed(struct net_device *vf_netdev)
 	if (!netvsc_dev)
 		return NOTIFY_DONE;
 
+	if (net_device_ctx->data_path_is_vf == vf_is_up)
+		return NOTIFY_OK;
+	net_device_ctx->data_path_is_vf = vf_is_up;
+
 	netvsc_switch_datapath(ndev, vf_is_up);
 	netdev_info(ndev, "Data path switched %s VF: %s\n",
 		    vf_is_up ? "to" : "from", vf_netdev->name);