The recent change to netlink dump "done" callback handling broke IPv6
which played dirty tricks with the "done" callback.  This causes an
infinite loop during a dump.
The following patch fixes it.
This bug was reported by Jeff Garzik.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
                fib6_walker_unlink(w);
                kfree(w);
        }
-       if (cb->args[1]) {
-               cb->done = (void*)cb->args[1];
-               cb->args[1] = 0;
-       }
+       cb->done = (void*)cb->args[1];
+       cb->args[1] = 0;
 }
 
 static int fib6_dump_done(struct netlink_callback *cb)