[PATCH net] hv_netvsc: Fix hibernation for mlx5 VF driver

[Dexuan Cui <decui@microsoft.com>]

mlx5_suspend()/resume() keep the network interface, so during hibernation
netvsc_unregister_vf() and netvsc_register_vf() are not called, and hence
netvsc_resume() should call netvsc_vf_changed() to switch the data path
back to the VF after hibernation. Similarly, netvsc_suspend() should
not call netvsc_unregister_vf().

BTW, mlx4_suspend()/resume() are differnt in that they destroy and
re-create the network device, so netvsc_register_vf() and
netvsc_unregister_vf() are automatically called. Note: mlx4 can also work
with the changes here because in netvsc_suspend()/resume()
ndev_ctx->vf_netdev is NULL for mlx4.

Fixes: 0efeea5fb153 ("hv_netvsc: Add the support of hibernation")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/net/hyperv/netvsc_drv.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 64b0a74c1523..f896059a9588 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -2587,7 +2587,7 @@ static int netvsc_remove(struct hv_device *dev)
 static int netvsc_suspend(struct hv_device *dev)
 {
 	struct net_device_context *ndev_ctx;
-	struct net_device *vf_netdev, *net;
+	struct net_device *net;
 	struct netvsc_device *nvdev;
 	int ret;
 
@@ -2604,10 +2604,6 @@ static int netvsc_suspend(struct hv_device *dev)
 		goto out;
 	}
 
-	vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
-	if (vf_netdev)
-		netvsc_unregister_vf(vf_netdev);
-
 	/* Save the current config info */
 	ndev_ctx->saved_netvsc_dev_info = netvsc_devinfo_get(nvdev);
 
@@ -2623,6 +2619,7 @@ static int netvsc_resume(struct hv_device *dev)
 	struct net_device *net = hv_get_drvdata(dev);
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device_info *device_info;
+	struct net_device *vf_netdev;
 	int ret;
 
 	rtnl_lock();
@@ -2635,6 +2632,10 @@ static int netvsc_resume(struct hv_device *dev)
 	netvsc_devinfo_put(device_info);
 	net_device_ctx->saved_netvsc_dev_info = NULL;
 
+	vf_netdev = rtnl_dereference(net_device_ctx->vf_netdev);
+	if (vf_netdev && netvsc_vf_changed(vf_netdev) != NOTIFY_OK)
+		ret = -EINVAL;
+
 	rtnl_unlock();
 
 	return ret;
-- 
2.19.1