From: stephen hemminger <stephen@networkplumber.org>
Date: Wed, 9 Aug 2017 17:46:06 -0700
Patch-mainline: v4.14-rc1
Subject: netvsc: check error return when restoring channels and mtu
Git-commit: 68d715f68541d58033199eea80991394a6886eb7
References: fate#323887

If setting new values fails, and the attempt to restore original
settings fails. Then log an error and leave device down.
This should never happen, but if it does don't go down in flames.

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/netvsc_drv.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

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
@@ -845,7 +845,13 @@ static int netvsc_set_channels(struct net_device *net,
 	} else {
 		ret = PTR_ERR(nvdev);
 		device_info.num_chn = orig;
-		rndis_filter_device_add(dev, &device_info);
+		nvdev = rndis_filter_device_add(dev, &device_info);
+
+		if (IS_ERR(nvdev)) {
+			netdev_err(net, "restoring channel setting failed: %ld\n",
+				   PTR_ERR(nvdev));
+			return ret;
+		}
 	}
 
 	if (was_opened)
@@ -953,10 +959,16 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 
 		/* Attempt rollback to original MTU */
 		ndev->mtu = orig_mtu;
-		rndis_filter_device_add(hdev, &device_info);
+		nvdev = rndis_filter_device_add(hdev, &device_info);
 
 		if (vf_netdev)
 			dev_set_mtu(vf_netdev, orig_mtu);
+
+		if (IS_ERR(nvdev)) {
+			netdev_err(ndev, "restoring mtu failed: %ld\n",
+				   PTR_ERR(nvdev));
+			return ret;
+		}
 	}
 
 	if (was_opened)