Re: [net-next]: unable to add routes to tables

[David Ahern]

On 8/18/15 10:57 AM, Andreas Schultz wrote:
Hi,
It seems that the policy for adding routes to tables has changed between
Linux 4.2-rc6 and net-next.

In Linux main line (tested up to 4.2-rc6), with this main routing table:
# ip route show table main
...
172.28.0.0/24 dev vnf-xe1p0  proto kernel  scope link  src 172.28.0.16

and an empty table 100, this works:

# ip route add 10.0.0.0/8 via 172.28.0.32 table 100 dev vnf-xe1p0

With net-next at commit d52736e24fe2e927c26817256f8d1a3c8b5d51a0, the
same command leads to an:

# ip route add 10.0.0.0/8 via 172.28.0.32 table 100 dev vnf-xe1p0
RTNETLINK answers: Resource temporarily unavailable

Is this expected behavior?


The attached works for me and so does my original problem. Can you 
confirm it resolves your problem? If so I'll send a formal patch.

David


diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index c8025851dac7..01a237278dd2 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -710,9 +710,16 @@ static int fib_check_nh(struct fib_config *cfg, struct 
fib_info *fi,
                                err = fib_table_lookup(tbl, &fl4, &res,
                                                       
FIB_LOOKUP_IGNORE_LINKSTATE |
                                                       FIB_LOOKUP_NOREF);
-                       else
+
+                       /* on error or if no table given do full lookup. This is
+                        * needed for example when nexthops are in the local 
table
+                        * rather than the given table
+                        */
+                       if (!tbl || err) {
                                err = fib_lookup(net, &fl4, &res,
                                                 FIB_LOOKUP_IGNORE_LINKSTATE);
+                       }
+
                        if (err) {
                                rcu_read_unlock();
                                return err;