ethtool: add CHANNELS_NTF notification

Send ETHTOOL_MSG_CHANNELS_NTF notification whenever channel counts of
a network device are modified using ETHTOOL_MSG_CHANNELS_SET netlink
message or ETHTOOL_SCHANNELS ioctl request.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ethtool/channels.c b/net/ethtool/channels.c
index ee232c1..8dc5485 100644
--- a/net/ethtool/channels.c
+++ b/net/ethtool/channels.c
@@ -213,6 +213,9 @@ int ethnl_set_channels(struct sk_buff *skb, struct genl_info *info)
 		}
 
 	ret = dev->ethtool_ops->set_channels(dev, &channels);
+	if (ret < 0)
+		goto out_ops;
+	ethtool_notify(dev, ETHTOOL_MSG_CHANNELS_NTF, NULL);
 
 out_ops:
 	ethnl_ops_complete(dev);