[PATCH AUTOSEL 5.8 09/29] hv_netvsc: Cache the current data path to avoid duplicate call and message

Sasha Levin
2020-09-29T01:30:45Z

From: Dexuan Cui <decui@microsoft.com>

[ Upstream commit da26658c3d7005aa67a706dceff7b2807b59e123 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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
index abda736e7c7dc..a4d2dd2637e26 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -973,6 +973,9 @@ struct net_device_context {
/* 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;
+
/* Used to temporarily save the config info across hibernation */
struct netvsc_device_info *saved_netvsc_dev_info;
};
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 8309194b351a9..329eff3250b23 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2323,7 +2323,16 @@ 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;
@@ -2340,6 +2349,10 @@ 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);
@@ -2582,6 +2595,12 @@ static int netvsc_resume(struct hv_device *dev)
rtnl_lock();

net_device_ctx = netdev_priv(net);
+
+ /* Reset the data path to the netvsc NIC before re-opening the vmbus
+ * channel. Later netvsc_netdev_event() will switch the data path to
+ * the VF upon the UP or CHANGE event.
+ */
+ net_device_ctx->data_path_is_vf = false;
device_info = net_device_ctx->saved_netvsc_dev_info;

ret = netvsc_attach(net, device_info);
--
2.25.1