[PATCH] net: Fix the arp error in some cases

[guodeqing <geffrey.guo@huawei.com>]

ie.,
$ ifconfig eth0 6.6.6.6 netmask 255.255.255.0

$ ip rule add from 6.6.6.6 table 6666

$ ip route add 9.9.9.9 via 6.6.6.6

$ ping -I 6.6.6.6 9.9.9.9
PING 9.9.9.9 (9.9.9.9) from 6.6.6.6 : 56(84) bytes of data.

3 packets transmitted, 0 received, 100% packet loss, time 2079ms

$ arp
Address     HWtype  HWaddress           Flags Mask            Iface
6.6.6.6             (incomplete)                              eth0

The arp request address is error, this is because fib_table_lookup in 
fib_check_nh lookup the destnation 9.9.9.9 nexthop, the scope of 
the fib result is RT_SCOPE_LINK,the correct scope is RT_SCOPE_HOST.  
Here I add a check of whether this is RT_TABLE_MAIN to solve this problem. 

Fixes: 3bfd847203c6("net: Use passed in table for nexthop lookups")
Signed-off-by: guodeqing <geffrey.guo@huawei.com>
---
 net/ipv4/fib_semantics.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index e53871e..1f75dc6 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1109,7 +1109,7 @@ static int fib_check_nh_v4_gw(struct net *net, struct fib_nh *nh, u32 table,
 		if (fl4.flowi4_scope < RT_SCOPE_LINK)
 			fl4.flowi4_scope = RT_SCOPE_LINK;
 
-		if (table)
+		if (table && table != RT_TABLE_MAIN)
 			tbl = fib_get_table(net, table);
 
 		if (tbl)
-- 
2.7.4