[NET]: Fix neighbour destructor handling.

->neigh_destructor() is killed (not used), replaced with
->neigh_cleanup(), which is called when neighbor entry goes to dead
state. At this point everything is still valid: neigh->dev,
neigh->parms etc.

The device should guarantee that dead neighbor entries (neigh->dead !=
0) do not get private part initialized, otherwise nobody will cleanup
it.

I think this is enough for ipoib which is the only user of this thing.
Initialization private part of neighbor entries happens in ipib
start_xmit routine, which is not reached when device is down.  But it
would be better to add explicit test for neigh->dead in any case.
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/infiniband/ulp/ipoib/ipoib_main.c

@@ -814,7 +814,7 @@ static void ipoib_set_mcast_list(struct net_device *dev)
 	queue_work(ipoib_workqueue, &priv->restart_task);
 }
 
-static void ipoib_neigh_destructor(struct neighbour *n)
+static void ipoib_neigh_cleanup(struct neighbour *n)
 {
 	struct ipoib_neigh *neigh;
 	struct ipoib_dev_priv *priv = netdev_priv(n->dev);
@@ -822,7 +822,7 @@ static void ipoib_neigh_destructor(struct neighbour *n)
 	struct ipoib_ah *ah = NULL;
 
 	ipoib_dbg(priv,
-		  "neigh_destructor for %06x " IPOIB_GID_FMT "\n",
+		  "neigh_cleanup for %06x " IPOIB_GID_FMT "\n",
 		  IPOIB_QPN(n->ha),
 		  IPOIB_GID_RAW_ARG(n->ha + 4));
 
@@ -874,7 +874,7 @@ void ipoib_neigh_free(struct net_device *dev, struct ipoib_neigh *neigh)
 
 static int ipoib_neigh_setup_dev(struct net_device *dev, struct neigh_parms *parms)
 {
-	parms->neigh_destructor = ipoib_neigh_destructor;
+	parms->neigh_cleanup = ipoib_neigh_cleanup;
 
 	return 0;
 }

include/net/neighbour.h

@@ -36,7 +36,7 @@ struct neigh_parms
 	struct net_device *dev;
 	struct neigh_parms *next;
 	int	(*neigh_setup)(struct neighbour *);
-	void	(*neigh_destructor)(struct neighbour *);
+	void	(*neigh_cleanup)(struct neighbour *);
 	struct neigh_table *tbl;
 
 	void	*sysctl_table;

net/atm/clip.c

@@ -261,14 +261,6 @@ static void clip_pop(struct atm_vcc *vcc, struct sk_buff *skb)
 	spin_unlock_irqrestore(&PRIV(dev)->xoff_lock, flags);
 }
 
-static void clip_neigh_destroy(struct neighbour *neigh)
-{
-	DPRINTK("clip_neigh_destroy (neigh %p)\n", neigh);
-	if (NEIGH2ENTRY(neigh)->vccs)
-		printk(KERN_CRIT "clip_neigh_destroy: vccs != NULL !!!\n");
-	NEIGH2ENTRY(neigh)->vccs = (void *) NEIGHBOR_DEAD;
-}
-
 static void clip_neigh_solicit(struct neighbour *neigh, struct sk_buff *skb)
 {
 	DPRINTK("clip_neigh_solicit (neigh %p, skb %p)\n", neigh, skb);
@@ -342,7 +334,6 @@ static struct neigh_table clip_tbl = {
 	/* parameters are copied from ARP ... */
 	.parms = {
 		.tbl 			= &clip_tbl,
-		.neigh_destructor	= clip_neigh_destroy,
 		.base_reachable_time 	= 30 * HZ,
 		.retrans_time 		= 1 * HZ,
 		.gc_staletime 		= 60 * HZ,

net/core/neighbour.c

@@ -140,6 +140,8 @@ static int neigh_forced_gc(struct neigh_table *tbl)
 				n->dead = 1;
 				shrunk	= 1;
 				write_unlock(&n->lock);
+				if (n->parms->neigh_cleanup)
+					n->parms->neigh_cleanup(n);
 				neigh_release(n);
 				continue;
 			}
@@ -211,6 +213,8 @@ static void neigh_flush_dev(struct neigh_table *tbl, struct net_device *dev)
 				NEIGH_PRINTK2("neigh %p is stray.\n", n);
 			}
 			write_unlock(&n->lock);
+			if (n->parms->neigh_cleanup)
+				n->parms->neigh_cleanup(n);
 			neigh_release(n);
 		}
 	}
@@ -582,9 +586,6 @@ void neigh_destroy(struct neighbour *neigh)
 			kfree(hh);
 	}
 
-	if (neigh->parms->neigh_destructor)
-		(neigh->parms->neigh_destructor)(neigh);
-
 	skb_queue_purge(&neigh->arp_queue);
 
 	dev_put(neigh->dev);
@@ -675,6 +676,8 @@ static void neigh_periodic_timer(unsigned long arg)
 			*np = n->next;
 			n->dead = 1;
 			write_unlock(&n->lock);
+			if (n->parms->neigh_cleanup)
+				n->parms->neigh_cleanup(n);
 			neigh_release(n);
 			continue;
 		}
@@ -2088,10 +2091,13 @@ void __neigh_for_each_release(struct neigh_table *tbl,
 			} else
 				np = &n->next;
 			write_unlock(&n->lock);
-			if (release)
+			if (release) {
+				if (n->parms->neigh_cleanup)
+					n->parms->neigh_cleanup(n);
 				neigh_release(n);
 			}
 		}
+	}
 }
 EXPORT_SYMBOL(__neigh_for_each_release);