mlxsw: spectrum_router: Don't reflect dead neighs

When a neighbour is considered to be dead, we should remove it from the
device's table regardless of its NUD state.

Without this patch, after setting a port to be administratively down we
get the following errors when we periodically try to update the kernel
about neighbours activity:

[  461.947268] mlxsw_spectrum 0000:03:00.0 sw1p3: Failed to find
matching neighbour for IP=192.168.100.2

Fixes: a6bf9e93 ("mlxsw: spectrum_router: Offload neighbours based on NUD state change")
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c

@@ -942,7 +942,7 @@ static void mlxsw_sp_router_neigh_update_hw(struct work_struct *work)
 	char rauht_pl[MLXSW_REG_RAUHT_LEN];
 	struct net_device *dev;
 	bool entry_connected;
-	u8 nud_state;
+	u8 nud_state, dead;
 	bool updating;
 	bool removing;
 	bool adding;
@@ -953,10 +953,11 @@ static void mlxsw_sp_router_neigh_update_hw(struct work_struct *work)
 	dip = ntohl(*((__be32 *) n->primary_key));
 	memcpy(neigh_entry->ha, n->ha, sizeof(neigh_entry->ha));
 	nud_state = n->nud_state;
+	dead = n->dead;
 	dev = n->dev;
 	read_unlock_bh(&n->lock);
 
-	entry_connected = nud_state & NUD_VALID;
+	entry_connected = nud_state & NUD_VALID && !dead;
 	adding = (!neigh_entry->offloaded) && entry_connected;
 	updating = neigh_entry->offloaded && entry_connected;
 	removing = neigh_entry->offloaded && !entry_connected;
@@ -1351,7 +1352,7 @@ static int mlxsw_sp_nexthop_init(struct mlxsw_sp *mlxsw_sp,
 	struct mlxsw_sp_neigh_entry *neigh_entry;
 	struct net_device *dev = fib_nh->nh_dev;
 	struct neighbour *n;
-	u8 nud_state;
+	u8 nud_state, dead;
 
 	/* Take a reference of neigh here ensuring that neigh would
 	 * not be detructed before the nexthop entry is finished.
@@ -1383,8 +1384,9 @@ static int mlxsw_sp_nexthop_init(struct mlxsw_sp *mlxsw_sp,
 	list_add_tail(&nh->neigh_list_node, &neigh_entry->nexthop_list);
 	read_lock_bh(&n->lock);
 	nud_state = n->nud_state;
+	dead = n->dead;
 	read_unlock_bh(&n->lock);
-	__mlxsw_sp_nexthop_neigh_update(nh, !(nud_state & NUD_VALID));
+	__mlxsw_sp_nexthop_neigh_update(nh, !(nud_state & NUD_VALID && !dead));
 
 	return 0;
 }