[NET] core: add RFC2863 operstate

this patch adds a dormant flag to network devices, RFC2863 operstate derived
from these flags and possibility for userspace interaction. It allows drivers
to signal that a device is unusable for user traffic without disabling
queueing (and therefore the possibility for protocol establishment traffic to
flow) and a userspace supplicant (WPA, 802.1X) to mark a device unusable
without changes to the driver.

It is the result of our long discussion. However I must admit that it
represents what Jamal and I agreed on with compromises towards Krzysztof, but
Thomas and Krzysztof still disagree with some parts. Anyway I think it should
be applied.

Signed-off-by: Stefan Rompf <stefan@loplof.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if.h

@@ -33,7 +33,7 @@
 #define	IFF_LOOPBACK	0x8		/* is a loopback net		*/
 #define	IFF_POINTOPOINT	0x10		/* interface is has p-p link	*/
 #define	IFF_NOTRAILERS	0x20		/* avoid use of trailers	*/
-#define	IFF_RUNNING	0x40		/* interface running and carrier ok */
+#define	IFF_RUNNING	0x40		/* interface RFC2863 OPER_UP	*/
 #define	IFF_NOARP	0x80		/* no ARP protocol		*/
 #define	IFF_PROMISC	0x100		/* receive all packets		*/
 #define	IFF_ALLMULTI	0x200		/* receive all multicast packets*/
@@ -43,12 +43,16 @@
 
 #define IFF_MULTICAST	0x1000		/* Supports multicast		*/
 
-#define IFF_VOLATILE	(IFF_LOOPBACK|IFF_POINTOPOINT|IFF_BROADCAST|IFF_MASTER|IFF_SLAVE|IFF_RUNNING)
-
 #define IFF_PORTSEL	0x2000          /* can set media type		*/
 #define IFF_AUTOMEDIA	0x4000		/* auto media select active	*/
 #define IFF_DYNAMIC	0x8000		/* dialup device with changing addresses*/
 
+#define IFF_LOWER_UP	0x10000		/* driver signals L1 up		*/
+#define IFF_DORMANT	0x20000		/* driver signals dormant	*/
+
+#define IFF_VOLATILE	(IFF_LOOPBACK|IFF_POINTOPOINT|IFF_BROADCAST|\
+		IFF_MASTER|IFF_SLAVE|IFF_RUNNING|IFF_LOWER_UP|IFF_DORMANT)
+
 /* Private (from user) interface flags (netdevice->priv_flags). */
 #define IFF_802_1Q_VLAN 0x1             /* 802.1Q VLAN device.          */
 #define IFF_EBRIDGE	0x2		/* Ethernet bridging device.	*/
@@ -83,6 +87,22 @@
 #define IF_PROTO_FR_ETH_PVC 0x200B
 #define IF_PROTO_RAW    0x200C          /* RAW Socket                   */
 
+/* RFC 2863 operational status */
+enum {
+	IF_OPER_UNKNOWN,
+	IF_OPER_NOTPRESENT,
+	IF_OPER_DOWN,
+	IF_OPER_LOWERLAYERDOWN,
+	IF_OPER_TESTING,
+	IF_OPER_DORMANT,
+	IF_OPER_UP,
+};
+
+/* link modes */
+enum {
+	IF_LINK_MODE_DEFAULT,
+	IF_LINK_MODE_DORMANT,	/* limit upward transition to dormant */
+};
 
 /*
  *	Device mapping structure. I'd just gone off and designed a 

include/linux/netdevice.h

@@ -230,7 +230,8 @@ enum netdev_state_t
 	__LINK_STATE_SCHED,
 	__LINK_STATE_NOCARRIER,
 	__LINK_STATE_RX_SCHED,
-	__LINK_STATE_LINKWATCH_PENDING
+	__LINK_STATE_LINKWATCH_PENDING,
+	__LINK_STATE_DORMANT,
 };
 
 
@@ -335,11 +336,14 @@ struct net_device
 	 */
 
 
-	unsigned short		flags;	/* interface flags (a la BSD)	*/
+	unsigned int		flags;	/* interface flags (a la BSD)	*/
 	unsigned short		gflags;
         unsigned short          priv_flags; /* Like 'flags' but invisible to userspace. */
 	unsigned short		padded;	/* How much padding added by alloc_netdev() */
 
+	unsigned char		operstate; /* RFC2863 operstate */
+	unsigned char		link_mode; /* mapping policy to operstate */
+
 	unsigned		mtu;	/* interface MTU value		*/
 	unsigned short		type;	/* interface hardware type	*/
 	unsigned short		hard_header_len;	/* hardware hdr length	*/
@@ -714,6 +718,10 @@ static inline void dev_put(struct net_device *dev)
 /* Carrier loss detection, dial on demand. The functions netif_carrier_on
  * and _off may be called from IRQ context, but it is caller
  * who is responsible for serialization of these calls.
+ *
+ * The name carrier is inappropriate, these functions should really be
+ * called netif_lowerlayer_*() because they represent the state of any
+ * kind of lower layer not just hardware media.
  */
 
 extern void linkwatch_fire_event(struct net_device *dev);
@@ -729,6 +737,29 @@ extern void netif_carrier_on(struct net_device *dev);
 
 extern void netif_carrier_off(struct net_device *dev);
 
+static inline void netif_dormant_on(struct net_device *dev)
+{
+	if (!test_and_set_bit(__LINK_STATE_DORMANT, &dev->state))
+		linkwatch_fire_event(dev);
+}
+
+static inline void netif_dormant_off(struct net_device *dev)
+{
+	if (test_and_clear_bit(__LINK_STATE_DORMANT, &dev->state))
+		linkwatch_fire_event(dev);
+}
+
+static inline int netif_dormant(const struct net_device *dev)
+{
+	return test_bit(__LINK_STATE_DORMANT, &dev->state);
+}
+
+
+static inline int netif_oper_up(const struct net_device *dev) {
+	return (dev->operstate == IF_OPER_UP ||
+		dev->operstate == IF_OPER_UNKNOWN /* backward compat */);
+}
+
 /* Hot-plugging. */
 static inline int netif_device_present(struct net_device *dev)
 {

include/linux/rtnetlink.h

@@ -733,6 +733,8 @@ enum
 #define IFLA_MAP IFLA_MAP
 	IFLA_WEIGHT,
 #define IFLA_WEIGHT IFLA_WEIGHT
+	IFLA_OPERSTATE,
+	IFLA_LINKMODE,
 	__IFLA_MAX
 };