net_device: add support for network device groups

Net devices can now be grouped, enabling simpler manipulation from
userspace. This patch adds a group field to the net_device structure, as
well as rtnetlink support to query and modify it.

Signed-off-by: Vlad Dogaru <[e-mail]>
Acked-by: Jamal Hadi Salim <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/if_link.h

···
 	IFLA_VF_PORTS,
 	IFLA_PORT_SELF,
 	IFLA_AF_SPEC,
+	IFLA_GROUP,		/* Group the device belongs to */
 	__IFLA_MAX
 };
 

include/linux/netdevice.h

···
 #define NET_RX_SUCCESS		0	/* keep 'em coming, baby */
 #define NET_RX_DROP		1	/* packet dropped */
 
+/* Initial net device group. All devices belong to group 0 by default. */
+#define INIT_NETDEV_GROUP	0
+
 /*
  * Transmit return codes: transmit return codes originate from three different
  * namespaces:
···
 
 	/* phy device may attach itself for hardware timestamping */
 	struct phy_device *phydev;
+
+	/* group the device belongs to */
+	int group;
 };
 #define to_net_dev(d) container_of(d, struct net_device, dev)
 
···
 extern int		dev_change_net_namespace(struct net_device *,
 						 struct net *, const char *);
 extern int		dev_set_mtu(struct net_device *, int);
+extern void		dev_set_group(struct net_device *, int);
 extern int		dev_set_mac_address(struct net_device *,
 					    struct sockaddr *);
 extern int		dev_hard_start_xmit(struct sk_buff *skb,

net/core/dev.c

···
 EXPORT_SYMBOL(dev_set_mtu);
 
 /**
+ *	dev_set_group - Change group this device belongs to
+ *	@dev: device
+ *	@new_group: group this device should belong to
+ */
+void dev_set_group(struct net_device *dev, int new_group)
+{
+	dev->group = new_group;
+}
+EXPORT_SYMBOL(dev_set_group);
+
+/**
  *	dev_set_mac_address - Change Media Access Control Address
  *	@dev: device
  *	@sa: new address
···
 	dev->priv_flags = IFF_XMIT_DST_RELEASE;
 	setup(dev);
 	strcpy(dev->name, name);
+	dev->group = INIT_NETDEV_GROUP;
 	return dev;
 
 free_pcpu:

net/core/rtnetlink.c

···
 		   netif_running(dev) ? dev->operstate : IF_OPER_DOWN);
 	NLA_PUT_U8(skb, IFLA_LINKMODE, dev->link_mode);
 	NLA_PUT_U32(skb, IFLA_MTU, dev->mtu);
+	NLA_PUT_U32(skb, IFLA_GROUP, dev->group);
 
 	if (dev->ifindex != dev->iflink)
 		NLA_PUT_U32(skb, IFLA_LINK, dev->iflink);
···
 		err = dev_set_mtu(dev, nla_get_u32(tb[IFLA_MTU]));
 		if (err < 0)
 			goto errout;
+		modified = 1;
+	}
+
+	if (tb[IFLA_GROUP]) {
+		dev_set_group(dev, nla_get_u32(tb[IFLA_GROUP]));
 		modified = 1;
 	}