[VLAN]: Propagate selected feature bits to VLAN devices

Propagate feature bits from the NETDEV_FEAT_CHANGE notifier. For now
only TSO is propagated for devices that announce their ability to
support TSO in combination with VLAN accel by setting the NETIF_F_VLAN_TSO
flag.

Signed-off-by: Patrick McHardy <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/netdevice.h

···
 #define NETIF_F_NETNS_LOCAL	8192	/* Does not change network namespaces */
 #define NETIF_F_MULTI_QUEUE	16384	/* Has multiple TX/RX queues */
 #define NETIF_F_LRO		32768	/* large receive offload */
+#define NETIF_F_VLAN_TSO	65536	/* Supports TSO for VLANs */
+#define NETIF_F_VLAN_CSUM	131072	/* Supports TX checksumming for VLANs */
 
 	/* Segmentation offload features */
-#define NETIF_F_GSO_SHIFT	16
-#define NETIF_F_GSO_MASK	0xffff0000
+#define NETIF_F_GSO_SHIFT	20
+#define NETIF_F_GSO_MASK	0xfff00000
 #define NETIF_F_TSO		(SKB_GSO_TCPV4 << NETIF_F_GSO_SHIFT)
 #define NETIF_F_UFO		(SKB_GSO_UDP << NETIF_F_GSO_SHIFT)
 #define NETIF_F_GSO_ROBUST	(SKB_GSO_DODGY << NETIF_F_GSO_SHIFT)

net/8021q/vlan.c

···
 	memcpy(vlan->real_dev_addr, dev->dev_addr, ETH_ALEN);
 }
 
+static void vlan_transfer_features(struct net_device *dev,
+				   struct net_device *vlandev)
+{
+	unsigned long old_features = vlandev->features;
+
+	if (dev->features & NETIF_F_VLAN_TSO) {
+		vlandev->features &= ~VLAN_TSO_FEATURES;
+		vlandev->features |= dev->features & VLAN_TSO_FEATURES;
+	}
+	if (dev->features & NETIF_F_VLAN_CSUM) {
+		vlandev->features &= ~NETIF_F_ALL_CSUM;
+		vlandev->features |= dev->features & NETIF_F_ALL_CSUM;
+	}
+
+	if (old_features != vlandev->features)
+		netdev_features_change(vlandev);
+}
+
 static void __vlan_device_event(struct net_device *dev, unsigned long event)
 {
 	switch (event) {
···
 
 			vlan_sync_address(dev, vlandev);
 		}
+		break;
+
+	case NETDEV_FEAT_CHANGE:
+		/* Propagate device features to underlying device */
+		for (i = 0; i < VLAN_GROUP_ARRAY_LEN; i++) {
+			vlandev = vlan_group_get_device(grp, i);
+			if (!vlandev)
+				continue;
+
+			vlan_transfer_features(dev, vlandev);
+		}
+
 		break;
 
 	case NETDEV_DOWN:

net/8021q/vlan.h

···
 #define VLAN_GRP_HASH_SIZE	(1 << VLAN_GRP_HASH_SHIFT)
 #define VLAN_GRP_HASH_MASK	(VLAN_GRP_HASH_SIZE - 1)
 
+#define VLAN_TSO_FEATURES	(NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_SG)
+
 /*  Find a VLAN device by the MAC address of its Ethernet device, and
  *  it's VLAN ID.  The default configuration is to have VLAN's scope
  *  to be box-wide, so the MAC will be ignored.  The mac will only be

net/8021q/vlan_dev.c

···
 					  (1<<__LINK_STATE_DORMANT))) |
 		      (1<<__LINK_STATE_PRESENT);
 
+	if (real_dev->features & NETIF_F_VLAN_TSO)
+		dev->features |= real_dev->features & VLAN_TSO_FEATURES;
+	if (real_dev->features & NETIF_F_VLAN_CSUM)
+		dev->features |= real_dev->features & NETIF_F_ALL_CSUM;
+
 	/* ipv6 shared card related stuff */
 	dev->dev_id = real_dev->dev_id;