ipv4: use l4 hash for locally generated multipath flows

This patch changes how the multipath hash is computed for locally
generated flows: now the hash comprises l4 information.

This allows better utilization of the available paths when the existing
flows have the same source IP and the same destination IP: with l3 hash,
even when multiple connections are in place simultaneously, a single path
will be used, while with l4 hash we can use all the available paths.

v2 changes:
- use get_hash_from_flowi4() instead of implementing just another l4 hash
  function

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 42778d9d71e5..f30df0ee4f4d 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1564,7 +1564,8 @@ void fib_select_path(struct net *net, struct fib_result *res,
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
         if (res->fi->fib_nhs > 1 && fl4->flowi4_oif == 0) {
                 if (mp_hash < 0)
-                        mp_hash = fib_multipath_hash(fl4->saddr, fl4->daddr);
+                        mp_hash = get_hash_from_flowi4(fl4) >> 1;
+
                 fib_select_multipath(res, mp_hash);
         }
         else