ipv4: Elide fib_validate_source() completely when possible.
If rpfilter is off (or the SKB has an IPSEC path) and there are not
tclassid users, we don't have to do anything at all when
fib_validate_source() is invoked besides setting the itag to zero.
We monitor tclassid uses with a counter (modified only under RTNL and
marked __read_mostly) and we protect the fib_validate_source() real
work with a test against this counter and whether rpfilter is to be
done.
Having a way to know whether we need no tclassid processing or not
also opens the door for future optimized rpfilter algorithms that do
not perform full FIB lookups.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 415f823..c46c20b 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -163,6 +163,12 @@
return;
}
fib_info_cnt--;
+#ifdef CONFIG_IP_ROUTE_CLASSID
+ change_nexthops(fi) {
+ if (nexthop_nh->nh_tclassid)
+ fib_num_tclassid_users--;
+ } endfor_nexthops(fi);
+#endif
call_rcu(&fi->rcu, free_fib_info_rcu);
}
@@ -421,6 +427,8 @@
#ifdef CONFIG_IP_ROUTE_CLASSID
nla = nla_find(attrs, attrlen, RTA_FLOW);
nexthop_nh->nh_tclassid = nla ? nla_get_u32(nla) : 0;
+ if (nexthop_nh->nh_tclassid)
+ fib_num_tclassid_users++;
#endif
}
@@ -815,6 +823,8 @@
nh->nh_flags = cfg->fc_flags;
#ifdef CONFIG_IP_ROUTE_CLASSID
nh->nh_tclassid = cfg->fc_flow;
+ if (nh->nh_tclassid)
+ fib_num_tclassid_users++;
#endif
#ifdef CONFIG_IP_ROUTE_MULTIPATH
nh->nh_weight = 1;
