net: Call netdev_features_change() from netdev_update_features()

Issue FEAT_CHANGE notification when features are changed by
netdev_update_features().  This will allow changes made by extra constraints
on e.g. MTU change to be properly propagated like changes via ethtool.
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -2550,6 +2550,7 @@ static inline u32 netdev_get_wanted_features(struct net_device *dev)
 }
 u32 netdev_increment_features(u32 all, u32 one, u32 mask);
 u32 netdev_fix_features(struct net_device *dev, u32 features);
+int __netdev_update_features(struct net_device *dev);
 void netdev_update_features(struct net_device *dev);
 
 void netif_stacked_transfer_operstate(const struct net_device *rootdev,

net/core/dev.c

@@ -5236,7 +5236,7 @@ u32 netdev_fix_features(struct net_device *dev, u32 features)
 }
 EXPORT_SYMBOL(netdev_fix_features);
 
-void netdev_update_features(struct net_device *dev)
+int __netdev_update_features(struct net_device *dev)
 {
 	u32 features;
 	int err = 0;
@@ -5250,7 +5250,7 @@ void netdev_update_features(struct net_device *dev)
 	features = netdev_fix_features(dev, features);
 
 	if (dev->features == features)
-		return;
+		return 0;
 
 	netdev_info(dev, "Features changed: 0x%08x -> 0x%08x\n",
 		dev->features, features);
@@ -5258,12 +5258,23 @@ void netdev_update_features(struct net_device *dev)
 	if (dev->netdev_ops->ndo_set_features)
 		err = dev->netdev_ops->ndo_set_features(dev, features);
 
-	if (!err)
-		dev->features = features;
-	else if (err < 0)
+	if (unlikely(err < 0)) {
 		netdev_err(dev,
 			"set_features() failed (%d); wanted 0x%08x, left 0x%08x\n",
 			err, features, dev->features);
+		return -1;
+	}
+
+	if (!err)
+		dev->features = features;
+
+	return 1;
+}
+
+void netdev_update_features(struct net_device *dev)
+{
+	if (__netdev_update_features(dev))
+		netdev_features_change(dev);
 }
 EXPORT_SYMBOL(netdev_update_features);
 
@@ -5430,7 +5441,7 @@ int register_netdevice(struct net_device *dev)
 		goto err_uninit;
 	dev->reg_state = NETREG_REGISTERED;
 
-	netdev_update_features(dev);
+	__netdev_update_features(dev);
 
 	/*
 	 *	Default initial state at registry is that the

net/core/ethtool.c

@@ -317,7 +317,7 @@ static int ethtool_set_features(struct net_device *dev, void __user *useraddr)
 
 	dev->wanted_features &= ~features[0].valid;
 	dev->wanted_features |= features[0].valid & features[0].requested;
-	netdev_update_features(dev);
+	__netdev_update_features(dev);
 
 	if ((dev->wanted_features ^ dev->features) & features[0].valid)
 		ret |= ETHTOOL_F_WISH;
@@ -499,7 +499,7 @@ static int ethtool_set_one_feature(struct net_device *dev,
 		else
 			dev->wanted_features &= ~mask;
 
-		netdev_update_features(dev);
+		__netdev_update_features(dev);
 		return 0;
 	}
 
@@ -551,7 +551,7 @@ int __ethtool_set_flags(struct net_device *dev, u32 data)
 	dev->wanted_features =
 		(dev->wanted_features & ~changed) | data;
 
-	netdev_update_features(dev);
+	__netdev_update_features(dev);
 
 	return 0;
 }