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>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 075f1e3a0fe..e361f488242 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -52,6 +52,7 @@ struct fib_rules_ops {
                                              struct sk_buff *,
                                              struct fib_rule_hdr *,
                                              struct nlattr **);
+        void                    (*delete)(struct fib_rule *);
         int                     (*compare)(struct fib_rule *,
                                            struct fib_rule_hdr *,
                                            struct nlattr **);