[PATCH net-next] fq_codel: Avoid regenerating skb flow hash unless necessary

The fq_codel qdisc currently always regenerates the skb flow hash.
This wastes some cycles and prevents flow seperation in cases where
the traffic has been encrypted and can no longer be understood by the
flow dissector.

Change it to use the prexisting flow hash if one exists, and only
regenerate if necessary.

Signed-off-by: Andrew Collins <redacted>
---
 net/sched/sch_fq_codel.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index a5ea0e9..2f50e4c 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c

@@ -57,7 +57,6 @@ struct fq_codel_sched_data {
        struct fq_codel_flow *flows;    /* Flows table [flows_cnt] */
        u32             *backlogs;      /* backlog table [flows_cnt] */
        u32             flows_cnt;      /* number of flows */
-       u32             perturbation;   /* hash perturbation */
        u32             quantum;        /* psched_mtu(qdisc_dev(sch)); */
        u32             drop_batch_size;
        u32             memory_limit;

@@ -75,9 +74,7 @@ struct fq_codel_sched_data {
 static unsigned int fq_codel_hash(const struct fq_codel_sched_data *q,
                                  struct sk_buff *skb)
 {
-       u32 hash = skb_get_hash_perturb(skb, q->perturbation);
-
-       return reciprocal_scale(hash, q->flows_cnt);
+       return reciprocal_scale(skb_get_hash(skb), q->flows_cnt);

 }

 static unsigned int fq_codel_classify(struct sk_buff *skb, struct Qdisc *sch,

@@ -482,7 +479,6 @@ static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
        q->memory_limit = 32 << 20; /* 32 MBytes */
        q->drop_batch_size = 64;
        q->quantum = psched_mtu(qdisc_dev(sch));
-       q->perturbation = prandom_u32();
        INIT_LIST_HEAD(&q->new_flows);
        INIT_LIST_HEAD(&q->old_flows);
        codel_params_init(&q->cparams);
--

2.9.3