net: ndo_fdb_dump should report -EMSGSIZE to rtnl_fdb_dump.

When the send skbuff reaches the end, nlmsg_put and friends returns
-EMSGSIZE but it is silently thrown away in ndo_fdb_dump. It is called
within a for_each_netdev loop and the first fdb entry of a following
netdev could fit in the remaining skbuff.  This breaks the mechanism
of cb->args[0] and idx to keep track of the entries that are already
dumped, which results missing entries in bridge fdb show command.

Signed-off-by: Minoura Makoto <minoura@valinux.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index e6944b2..b601139 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -931,8 +931,10 @@
 						     cb->nlh->nlmsg_seq,
 						     RTM_NEWNEIGH,
 						     NLM_F_MULTI, rd);
-				if (err < 0)
+				if (err < 0) {
+					cb->args[1] = err;
 					goto out;
+				}
 skip:
 				++idx;
 			}