sch_sfb: use skb_flow_dissect()

Current SFB double hashing is not fulfilling SFB theory, if two flows
share same rxhash value.

Using skb_flow_dissect() permits to really have better hash dispersion,
and get tunnelling support as well.

Double hashing point was mentioned by Florian Westphal

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 3 deletions

diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c
index e83c272c0325..96e42cae4c7a 100644
--- a/net/sched/sch_sfb.c
+++ b/net/sched/sch_sfb.c
@@ -26,6 +26,7 @@
 #include <net/ip.h>
 #include <net/pkt_sched.h>
 #include <net/inet_ecn.h>
+#include <net/flow_keys.h>
 
 /*
  * SFB uses two B[l][n] : L x N arrays of bins (L levels, N bins per level)
@@ -286,6 +287,7 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
         u32 minqlen = ~0;
         u32 r, slot, salt, sfbhash;
         int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+        struct flow_keys keys;
 
         if (unlikely(sch->q.qlen >= q->limit)) {
                 sch->qstats.overlimits++;
@@ -309,13 +311,19 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
                 /* If using external classifiers, get result and record it. */
                 if (!sfb_classify(skb, q, &ret, &salt))
                         goto other_drop;
+                keys.src = salt;
+                keys.dst = 0;
+                keys.ports = 0;
         } else {
-                salt = skb_get_rxhash(skb);
+                skb_flow_dissect(skb, &keys);
         }
 
         slot = q->slot;
 
-        sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
+        sfbhash = jhash_3words((__force u32)keys.dst,
+                               (__force u32)keys.src,
+                               (__force u32)keys.ports,
+                               q->bins[slot].perturbation);
         if (!sfbhash)
                 sfbhash = 1;
         sfb_skb_cb(skb)->hashes[slot] = sfbhash;
@@ -347,7 +355,10 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
         if (unlikely(p_min >= SFB_MAX_PROB)) {
                 /* Inelastic flow */
                 if (q->double_buffering) {
-                        sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
+                        sfbhash = jhash_3words((__force u32)keys.dst,
+                                               (__force u32)keys.src,
+                                               (__force u32)keys.ports,
+                                               q->bins[slot].perturbation);
                         if (!sfbhash)
                                 sfbhash = 1;
                         sfb_skb_cb(skb)->hashes[slot] = sfbhash;