[PATCH net] net_sched: sch_fq: ensure maxrate fq parameter applies to EDT flows

[Eric Dumazet]

When EDT conversion happened, fq lost the ability to enfore a maxrate
for all flows. It kept it for non EDT flows.

This commit restores the functionality.

Tested:

tc qd replace dev eth0 root fq maxrate 500Mbit
netperf -P0 -H host -- -O THROUGHPUT
489.75

Fixes: ab408b6dc744 ("tcp: switch tcp and sch_fq to new earliest departure time 
model")
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
 net/sched/sch_fq.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 
4b1af706896c07e5a0fe6d542dfcd530acdcf8f5..25a7cf6d380fd1ef5610a43a06dea488121b8206
 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -469,22 +469,29 @@ static struct sk_buff *fq_dequeue(struct Qdisc *sch)
                goto begin;
        }
        prefetch(&skb->end);
-       f->credit -= qdisc_pkt_len(skb);
+       plen = qdisc_pkt_len(skb);
+       f->credit -= plen;
 
-       if (ktime_to_ns(skb->tstamp) || !q->rate_enable)
+       if (!q->rate_enable)
                goto out;
 
        rate = q->flow_max_rate;
-       if (skb->sk)
-               rate = min(skb->sk->sk_pacing_rate, rate);
 
-       if (rate <= q->low_rate_threshold) {
-               f->credit = 0;
-               plen = qdisc_pkt_len(skb);
-       } else {
-               plen = max(qdisc_pkt_len(skb), q->quantum);
-               if (f->credit > 0)
-                       goto out;
+       /* If EDT time was provided for this skb, we need to
+        * update f->time_next_packet only if this qdisc enforces
+        * a flow max rate.
+        */
+       if (!skb->tstamp) {
+               if (skb->sk)
+                       rate = min(skb->sk->sk_pacing_rate, rate);
+
+               if (rate <= q->low_rate_threshold) {
+                       f->credit = 0;
+               } else {
+                       plen = max(plen, q->quantum);
+                       if (f->credit > 0)
+                               goto out;
+               }
        }
        if (rate != ~0UL) {
                u64 len = (u64)plen * NSEC_PER_SEC;
-- 
2.19.1.930.g4563a0d9d0-goog