From: Ido Schimmel <idosch@mellanox.com>
Date: Thu, 3 Aug 2017 13:28:21 +0200
Subject: ipv6: fib: Don't assume only nodes hold a reference on routes
Patch-mainline: v4.14-rc1
Git-commit: c5b12410fa591acb1d48e167b9bd0d2a7a38498d
References: bsc#1138732

The code currently assumes that only FIB nodes can hold a reference on
routes. Therefore, after fib6_purge_rt() has run and the route is no
longer present in any intermediate nodes, it's assumed that its
reference count would be 1 - taken by the node where it's currently
stored.

However, we're going to allow users other than the FIB to take a
reference on a route, so this assumption is no longer valid and the
BUG_ON() needs to be removed.

Note that purging only takes place if the initial reference count is
different than 1. I've left that check intact, as in the majority of
systems (where routes are only referenced by the FIB), it does actually
mean the route is present in intermediate nodes.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/ipv6/ip6_fib.c |    2 --
 1 file changed, 2 deletions(-)

--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -763,8 +763,6 @@ static void fib6_purge_rt(struct rt6_inf
 			}
 			fn = fn->parent;
 		}
-		/* No more references are possible at this point. */
-		BUG_ON(atomic_read(&rt->rt6i_ref) != 1);
 	}
 }