pkt_sched: fq: fix non TCP flows pacing

Steinar reported FQ pacing was not working for UDP flows.

It looks like the initial sk->sk_pacing_rate value of 0 was
a wrong choice. We should init it to ~0U (unlimited)

Then, TCA_FQ_FLOW_DEFAULT_RATE should be removed because it makes
no real sense. The default rate is really unlimited, and we
need to avoid a zero divide.

Reported-by: Steinar H. Gunderson <sesse@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 10 insertions, 11 deletions

diff --git a/net/core/sock.c b/net/core/sock.c
index 5b6beba494a3..0b39e7ae4383 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2319,6 +2319,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
         sk->sk_ll_usec          =       sysctl_net_busy_read;
 #endif
 
+        sk->sk_pacing_rate = ~0U;
         /*
          * Before updating sk_refcnt, we must commit prior changes to memory
          * (Documentation/RCU/rculist_nulls.txt for details)
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 48501a2baf75..a9dfdda9ed1d 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -472,20 +472,16 @@ begin:
         if (f->credit > 0 || !q->rate_enable)
                 goto out;
 
-        if (skb->sk && skb->sk->sk_state != TCP_TIME_WAIT) {
-                rate = skb->sk->sk_pacing_rate ?: q->flow_default_rate;
+        rate = q->flow_max_rate;
+        if (skb->sk && skb->sk->sk_state != TCP_TIME_WAIT)
+                rate = min(skb->sk->sk_pacing_rate, rate);
 
-                rate = min(rate, q->flow_max_rate);
-        } else {
-                rate = q->flow_max_rate;
-                if (rate == ~0U)
-                        goto out;
-        }
-        if (rate) {
+        if (rate != ~0U) {
                 u32 plen = max(qdisc_pkt_len(skb), q->quantum);
                 u64 len = (u64)plen * NSEC_PER_SEC;
 
-                do_div(len, rate);
+                if (likely(rate))
+                        do_div(len, rate);
                 /* Since socket rate can change later,
                  * clamp the delay to 125 ms.
                  * TODO: maybe segment the too big skb, as in commit
@@ -735,12 +731,14 @@ static int fq_dump(struct Qdisc *sch, struct sk_buff *skb)
         if (opts == NULL)
                 goto nla_put_failure;
 
+        /* TCA_FQ_FLOW_DEFAULT_RATE is not used anymore,
+         * do not bother giving its value
+         */
         if (nla_put_u32(skb, TCA_FQ_PLIMIT, sch->limit) ||
             nla_put_u32(skb, TCA_FQ_FLOW_PLIMIT, q->flow_plimit) ||
             nla_put_u32(skb, TCA_FQ_QUANTUM, q->quantum) ||
             nla_put_u32(skb, TCA_FQ_INITIAL_QUANTUM, q->initial_quantum) ||
             nla_put_u32(skb, TCA_FQ_RATE_ENABLE, q->rate_enable) ||
-            nla_put_u32(skb, TCA_FQ_FLOW_DEFAULT_RATE, q->flow_default_rate) ||
             nla_put_u32(skb, TCA_FQ_FLOW_MAX_RATE, q->flow_max_rate) ||
             nla_put_u32(skb, TCA_FQ_BUCKETS_LOG, q->fq_trees_log))
                 goto nla_put_failure;