"NETIF_RX_()"

This patch is for helping fully layered network interface mechanism
so that not only the send-path, but also the reception path are
wrapped with possible intermediate protocol module.

This is against 2.3.99-pre7-3

It provides a mechanism.  Person *using* it needs at device
configuration time to define that: 
  
        subdev->netif_rx = my_l2_dev_receive_routine;
  
Which also presumes that there is only one receive routine
for any given device, and that routine must do demux,   
update  skb->dev  to that (new) l2_dev, which then either
has a callback upwards, or not.  
If not, default  L3  netif_rx_() gets called.


This enables things like  bridgeNNN  which underneath has device ethNNN,
just for an example.  It would enable us to remove BRIDGE code from
present netif_rx() by moving it into a "bridge device"..
(Hmm.. back into bridge-device ?)


--- linux/include/linux/netdevice.h~	Wed May  3 14:06:46 2000
+++ linux/include/linux/netdevice.h	Wed May  3 14:17:36 2000
@@ -342,6 +342,7 @@
 	int			(*stop)(struct net_device *dev);
 	int			(*hard_start_xmit) (struct sk_buff *skb,
 						    struct net_device *dev);
+	int			(*netif_rx) (struct sk_buff *skb);
 	int			(*hard_header) (struct sk_buff *skb,
 						struct net_device *dev,
 						unsigned short type,
@@ -542,7 +543,15 @@
 
 extern void		net_call_rx_atomic(void (*fn)(void));
 #define HAVE_NETIF_RX 1
-extern void		netif_rx(struct sk_buff *skb);
+extern void		netif_rx_(struct sk_buff *skb);
+extern __inline__ void netif_rx(struct sk_buff *skb)
+{
+  if (skb->dev->netif_rx)
+    (skb->dev->netif_rx)(skb);
+  else
+    netif_rx_(skb);
+}
+
 extern int		dev_ioctl(unsigned int cmd, void *);
 extern int		dev_change_flags(struct net_device *, unsigned);
 extern void		dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev);
--- linux/net/core/dev.c~	Wed May  3 14:06:46 2000
+++ linux/net/core/dev.c	Wed May  3 14:19:17 2000
@@ -942,7 +942,7 @@
  *	protocol layers.
  */
 
-void netif_rx(struct sk_buff *skb)
+void netif_rx_(struct sk_buff *skb)
 {
 	int this_cpu = smp_processor_id();
 	struct softnet_data *queue;
--- linux/net/netsyms.c~	Mon Apr 24 23:43:05 2000
+++ linux/net/netsyms.c	Wed May  3 19:39:58 2000
@@ -498,7 +498,7 @@
 EXPORT_SYMBOL(__kfree_skb);
 EXPORT_SYMBOL(skb_clone);
 EXPORT_SYMBOL(skb_copy);
-EXPORT_SYMBOL(netif_rx);
+EXPORT_SYMBOL(netif_rx_);
 EXPORT_SYMBOL(dev_add_pack);
 EXPORT_SYMBOL(dev_remove_pack);
 EXPORT_SYMBOL(dev_get);